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http://openstudy.com/updates/5069ba00e4b0d9c2d4c3a5e3
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## anonymous 3 years ago Express the repeating decimal number as a quotient of two integers Delete Cancel Submit
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1. anonymous
• 3 years ago
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|dw:1349106177251:dw|
2. anonymous
• 3 years ago
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I know the answer is 317/11 I just can't figure out how to get the answer
3. klimenkov
• 3 years ago
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$$\frac{2853}{99}$$
4. klimenkov
• 3 years ago
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Let 28.(81) be x. So 100x=2881.(81). Now substract the first from the second: 99x=2853. Find x.
5. anonymous
• 3 years ago
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so what am I subtracting
6. klimenkov
• 3 years ago
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x=28.(81) and 100x=2881.(81). The first from the second.
7. anonymous
• 3 years ago
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so subtracting 28
8. anonymous
• 3 years ago
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and 1
9. anonymous
• 3 years ago
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I see how to get 2853 I just don't understand the other side of the equation
10. klimenkov
• 3 years ago
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Can you subtract 2881.(81)-28.(81). You do this to cancel the periond and get an integer.
11. anonymous
• 3 years ago
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okay I got it now thank you
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https://arxiv.org/abs/1707.04982
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cs.DS
(what is this?)
# Title: Practical Locally Private Heavy Hitters
Abstract: We present new practical local differentially private heavy hitters algorithms achieving optimal or near-optimal worst-case error and running time -- TreeHist and Bitstogram. In both algorithms, server running time is $\tilde O(n)$ and user running time is $\tilde O(1)$, hence improving on the prior state-of-the-art result of Bassily and Smith [STOC 2015] requiring $O(n^{5/2})$ server time and $O(n^{3/2})$ user time. With a typically large number of participants in local algorithms ($n$ in the millions), this reduction in time complexity, in particular at the user side, is crucial for making locally private heavy hitters algorithms usable in practice. We implemented Algorithm TreeHist to verify our theoretical analysis and compared its performance with the performance of Google's RAPPOR code.
Subjects: Data Structures and Algorithms (cs.DS) Cite as: arXiv:1707.04982 [cs.DS] (or arXiv:1707.04982v1 [cs.DS] for this version)
## Submission history
From: Uri Stemmer [view email]
[v1] Mon, 17 Jul 2017 02:34:55 GMT (603kb,D)
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http://math.stackexchange.com/questions/74931/integral-solutions-of-x2y21-z2
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# Integral solutions of $x^2+y^2+1=z^2$
I am interested in integral solutions of $$x^2+y^2+1=z^2.$$ Is there a complete theory comparable to the one for $x^2+y^2=z^2?$
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I think writing $(x+iy)(x-iy) = (z-1)(z+1)$ might help. – Joel Cohen Oct 22 '11 at 22:52
You are not trying to solve Project Euler problem 224, are you? projecteuler.net/problem=224 – starblue Oct 23 '11 at 13:15
@starblue. No, it came up when I tried to make up an example in hyperbolic geometry. – TCL Oct 23 '11 at 16:55
The question is essentially for which $z$ both $z-1$ and $z+1$ are the sum of two squares. There are some related questions asked before, such as math.stackexchange.com/questions/438818 and math.stackexchange.com/questions/46451. – barto Sep 8 '14 at 8:15
I would look at Catalan’s [well-known] complete solution for $x_1^2+x_2^2+x_3^2=y_1^2$, and set $x_3 = a^2+b^2-c^2-d^2=1$. This implies another equal sums-of-squares equation $a^2+b^2=c^2+d^2+1$, so you probably have a nice orbit to chase. See also Spira's paper <jstor.org/stable/2312125>;, etc.. – Kieren MacMillan Oct 6 '14 at 1:48
The equation defines a conic with a rational point (0,0,1). The other rational solutions can be parametrized by lines through that point. As with $x^2+y^2 = z^2$ the integer solutions can be deduced from the rational ones, and the quadratic form $x^2+y^2 - z^2$ has a large linear symmetry group allowing one to move between solutions. In these respects the theory is the same as the one for Pythagorean triples.
There is a difference in the structure of the symmetry group. For $a=0$ the hyperboloid $x^2+y^2 - z^2 = a$ becomes a cone, with additional scaling symmetries in addition to the linear transformations of the hyperboloid; in effect the $O(2,1)$ symmetry group of the rational solutions collapses into a product of scalings and circle isometries. For integer solutions, with Pythagorean triples there is a reduction to the case of primitive triples, but when $a \neq 0$ there is a bound on the shared factors of $(x,y,z)$, and for $a = \pm 1$ all integer solutions are primitive. The organization of Pythagorean triples using several 3x3 integer matrices as transformations connecting different solutions does use the $O(2,1)$ structure, and the solution set for the equation with $a \neq 0$ could be presented in the same way (possibly with more than one connected component when $|a| > 1$).
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Note: This is not a complete answer. First, I want to point out that both $x$ and $y$ must be even.
We can trivially get one infinitely family of solutions from the following: Consider triplets of the form $$(x,y,z)=(2r^2,2r,2r^2+1).$$ Then they satisfy the above as $$(2r^2 )^2 +(2r)^2+1=(2r^2+1)^2.$$ This gives rise to $$(2,2,3), \ (4,8,9), \ (6,18,19),\ \cdots$$
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the equation: $X^2+Y^2=Z^2-1$
Solutions can be written using the solutions of Pell's equation: $p^2-2k(k-1)s^2=1$
$k$ - given by us.
Solutions have form:
$X=2kps-2(k-1)s^2$
$Y=2(k-1)ps+2ks^2$
$Z=p^2+2(k^2-k+1)s^2$
And more:
$X=2p^2-2(3k-2)ps+2(2k-1)(k-1)s^2$
$Y=2p^2-2(3k-1)ps+2k(2k-1)s^2$
$Z=3p^2-4(2k-1)ps+2(3k^2-3k+1)s^2$
Although it should be a more general solution to record.
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I do not understand. And what you've edited? – individ May 11 '14 at 8:52
All of numbers can be any character.In Equation: $qX^2+Y^2=Z^2+a$
If the ratio is factored so: $a=(b-c)(b+c)$
Then we use the solutions of Pell's equation: $p^2-fs^2=\pm1$
where: $f=(q+1)k^2-2kt-(q-1)t^2$
Then the solutions are of the form:
$X=2(ck-bt)ps+2(bk^2-(b+c)kt+ct^2)s^2$
$Y=bp^2+2c(k-t)ps-(b(q-1)k^2+2(b-qc)kt+b(q-1)t^2)s^2$
$Z=cp^2+2b(k-t)ps+(c(q+1)k^2-2(bq+c)kt+c(q+1)t^2)s^2$
All of numbers can be any character.
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For the equation: $qX^2+Y^2=Z^2+j$
In the case where a square: $a=\sqrt{\frac{j}{q}}$
Using equation Pell: $p^2-(q+1)s^2=1$
Then the solution can be written:
$X=2s(s\pm{p})L\pm{ap^2}+2aps\pm{a(q+1)s^2}=bL+af$
$Y=(p^2\pm2ps+(1-q)s^2)L\pm{ap^2}+2aps\pm{a(q+1)s^2}=cL+af$
$Z=(p^2\pm2ps+(q+1)s^2)L\pm{ap^2}+2a(q+1)ps\pm{a(q+1)s^2}=fL+at$
$L$ - any integer number given by us.
The most interesting thing is that these numbers are solutions of equations:
$qb^2+c^2=f^2$
$t^2-(q+1)f^2=\pm{q}$
If we use the equation Pell: $p^2-(q+1)s^2=k$
And substituting the solutions in the upper formula, we have solutions of the following equations.
$qb^2+c^2=f^2$
where: $c-b=k$
$t^2-(q+1)f^2=\pm{qk^2}$
True, I use this formula in reverse order. Find solutions of Pell's equation is much more complicated than the simple equations like Pythagorean triples. So find them and then have solutions of Pell's equation. The most interesting thing is that the solution of Pell related to Pythagorean triples.
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https://kb.osu.edu/dspace/handle/1811/15682
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# THE RESONANCE RAMAN EFFECT IN HALOGEN GASES WITH AGRON ION LASER EXCITATION.
Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/15682
Files Size Format View
1969-D-03.jpg 95.34Kb JPEG image
Title: THE RESONANCE RAMAN EFFECT IN HALOGEN GASES WITH AGRON ION LASER EXCITATION. Creators: Holzer, W.; Murphy, W. F.; Bernstein, H. J. Issue Date: 1969 Publisher: Ohio State University Abstract: Resonance Raman scattering has been observed in $Br_{2}, I_{2}, BrCl, ICl$ and IBr gas, with excitation energy above the convergence limit of the $^{3}\Pi^{+}_{0} \rightarrow ^{1}\Sigma^{+}$ transition of these molecules. The argon ion laser lines use for excitation were those at 5145, 5017, 4965, 4880, and $4765{\AA}$. Overtone sequences up to the 10th harmonic were recorded. The difference between resonance Raman effect and resonance fluorescence (observed with excitation energy below the covergence limit in $Cl_{2}, Br_{2}$ and $I_{2}$) will be discussed in some detail. Description: Author Institution: Division of Pure Chemistry, National Research Council of Canada URI: http://hdl.handle.net/1811/15682 Other Identifiers: 1969-D-3
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https://www.mathdoubts.com/evaluate-lim-e-power-3-plus-x-sinx-e-cube-by-x-as-x-approaches-to-0-by-l-hopital-s-rule/
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# Evaluate $\displaystyle \large \lim_{x\,\to\,0}{\normalsize \dfrac{e^{3\normalsize +\large x}-\sin{x}-e^3}{x}}$ by L’Hopital’s Rule
The limit of $e$ raised to the power $3$ plus $x$ minus $\sin{x}$ minus $e$ raised to the power $3$ by $x$ as $x$ approaches to $0$ is solved in fundamental limit method and it will be solved here by L’Hospital’s Rule (or L’Hopital’s rule)
$\displaystyle \large \lim_{x\,\to\,0}{\normalsize \dfrac{e^{3\displaystyle +x}-\sin{x}-e^3}{x}}$
Let’s get started to learn how to find the limit of the given rational function by L’Hopital’s Rule (or L’Hospital’s Rule).
### Calculate the Limit by the Direct substitution
Let us try to find the limit of the given rational function by using direct substitution method as the value of $x$ approaches to $0$.
$=\,\,\,$ $\dfrac{e^{3 \displaystyle + \small 0}-\sin{(0)}-e^3}{0}$
$=\,\,\,$ $\dfrac{e^3-0-e^3}{0}$
The sine of angle zero radian is equal to zero as per the trigonometric mathematics.
$=\,\,\,$ $\dfrac{e^3-e^3}{0}$
$=\,\,\,$ $\dfrac{0}{0}$
It is evaluated that the limit of the function is indeterminate. Hence, it is better to think about an alternative mathematical approach to find its limit.
### Differentiate the Numerator and Denominator
The given function is eligible for evaluating its limit by the L’Hopital’s Rule (or L’Hospital’s Rule). Now, differentiate the expressions in both numerator and denominator with respect to $x$.
$=\,\,\,$ $\displaystyle \large \lim_{x\,\to\,0}{\normalsize \dfrac{\dfrac{d}{dx}\Big(e^{3\large +\Large x}-\sin{x}-e^3\Big)}{\dfrac{d}{dx}{(x)}}}$
The derivative of the difference of the terms can be evaluated as per the difference rule of the differentiation.
$=\,\,\,$ $\displaystyle \large \lim_{x\,\to\,0}{\normalsize \dfrac{\dfrac{d}{dx}\big(e^{3\large +\Large x}\big)-\dfrac{d}{dx}{\sin{x}}-\dfrac{d}{dx}{(e^3)}}{\dfrac{d}{dx}{(x)}}}$
The $e$ raised to the power $3$ plus $x$ can be split as a product of two quantities in exponential notation as per the product rule of the exponents.
$=\,\,\,$ $\displaystyle \large \lim_{x\,\to\,0}{\normalsize \dfrac{\dfrac{d}{dx}\big(e^3 \times e^{\Large x}\big)-\dfrac{d}{dx}{\sin{x}}-\dfrac{d}{dx}{(e^3)}}{\dfrac{d}{dx}{(x)}}}$
The factor $e$ raised to the power $3$vcolkfaZZ is a constant. Hence, it can be separated from the differentiation by using the constant multiple rule of the limits.
$=\,\,\,$ $\displaystyle \large \lim_{x\,\to\,0}{\normalsize \dfrac{e^3 \times \dfrac{d}{dx}\big(e^{\Large x}\big)-\dfrac{d}{dx}{\sin{x}}-\dfrac{d}{dx}{(e^3)}}{\dfrac{d}{dx}{(x)}}}$
Use derivative rule of natural exponential function, derivative rule of sine function and derivative rule of a constant to find the derivatives in the numerator. Similarly, find the derivative of the variable by using the derivative rule of a variable.
$=\,\,\,$ $\displaystyle \large \lim_{x\,\to\,0}{\normalsize \dfrac{e^3 \times e^{\Large x}-\cos{x}-0}{1}}$
$=\,\,\,$ $\displaystyle \large \lim_{x\,\to\,0}{\normalsize \big(e^3 \times e^{\Large x}-\cos{x}\big)}$
### Evaluate the Limit by the Direct substitution
Now, use the direct substitution method one more time to find the limit of the function as the value of $x$ approaches to zero.
$=\,\,\,$ $e^3 \times e^0-\cos{(0)}$
According to the zero power rule, the mathematical constant $e$ raised to the power zero is equal to one. The cosine of angle zero radian is equal to one as per the trigonometry.
$=\,\,\,$ $e^3 \times 1-1$
$=\,\,\,$ $e^3-1$
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http://www.advanceduninstaller.com/Realtek-Ethernet-Controller-Driver-2cb79419df4bb23b3adbb08f67962c5e-application.htm
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# Realtek Ethernet Controller Driver
## A guide to uninstall Realtek Ethernet Controller Driver from your system
You can find below details on how to remove Realtek Ethernet Controller Driver for Windows. The Windows release was developed by Realtek. More information on Realtek can be found here. Click on to get more details about Realtek Ethernet Controller Driver on Realtek's website. The application is frequently placed in the C:\Program Files (x86)\Realtek\NICDRV_8169 directory (same installation drive as Windows). C:\Program Files (x86)\InstallShield Installation Information\{8833FFB6-5B0C-4764-81AA-06DFEED9A476}\setup.exe -runfromtemp -removeonly is the full command line if you want to remove Realtek Ethernet Controller Driver. RTINSTALLER64.EXE is the Realtek Ethernet Controller Driver's main executable file and it takes about 182.64 KB (187024 bytes) on disk.
Realtek Ethernet Controller Driver is composed of the following executables which take 182.64 KB (187024 bytes) on disk:
• RTINSTALLER64.EXE (182.64 KB)
The current page applies to Realtek Ethernet Controller Driver version 7.72.410.2013 alone. Click on the links below for other Realtek Ethernet Controller Driver versions:
...click to view all...
Some files, folders and Windows registry entries can be left behind when you want to remove Realtek Ethernet Controller Driver from your PC.
Folders left behind when you uninstall Realtek Ethernet Controller Driver:
• C:\Program Files (x86)\Realtek\NICDRV_8169
Check for and remove the following files from your disk when you uninstall Realtek Ethernet Controller Driver:
• C:\Program Files (x86)\Realtek\NICDRV_8169\ICON\remove.ico
• C:\Program Files (x86)\Realtek\NICDRV_8169\InstallLog.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\RTInstaller32.dat
• C:\Program Files (x86)\Realtek\NICDRV_8169\RTINSTALLER64.EXE
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\EngLangID.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\FAQ\8168C_manual_install.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\FAQ\Change_installer_language.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\FAQ\Driver_Installer_Rollback.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\FAQ\INF_default_option_changed.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\FAQ\Use_installer_to_auto_remove_driver.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\FAQ\WAIK_Ver_RTM_with_new_driver.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\InstCtrl.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\InstOpt.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\note.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\rt64win7.cat
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\rt64win7.inf
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\rt64win7.sys
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\RtNicprop64.DLL
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\RTNUninst64.dll
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\setupctrl.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\WIN7\32\note.txt
• C:\Program Files (x86)\Realtek\NICDRV_8169\WIN7\WIN7\64\note.txt
Generally the following registry data will not be cleaned:
• HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\{8833FFB6-5B0C-4764-81AA-06DFEED9A476}
## A way to remove Realtek Ethernet Controller Driver from your PC using Advanced Uninstaller PRO
Realtek Ethernet Controller Driver is an application offered by the software company Realtek. Sometimes, people want to uninstall it. Sometimes this can be hard because doing this manually takes some advanced knowledge related to PCs. The best EASY solution to uninstall Realtek Ethernet Controller Driver is to use Advanced Uninstaller PRO. Here are some detailed instructions about how to do this:
1. If you don't have Advanced Uninstaller PRO already installed on your Windows PC, add it. This is a good step because Advanced Uninstaller PRO is an efficient uninstaller and all around tool to maximize the performance of your Windows computer.
2. Run Advanced Uninstaller PRO. Take your time to get familiar with Advanced Uninstaller PRO's design and number of features available. Advanced Uninstaller PRO is a very useful Windows optimizer.
3. Click on the General Tools button
4. Press the Uninstall Programs tool
5. All the programs installed on the PC will appear
6. Navigate the list of programs until you locate Realtek Ethernet Controller Driver or simply activate the Search feature and type in "Realtek Ethernet Controller Driver". The Realtek Ethernet Controller Driver app will be found automatically. Notice that when you click Realtek Ethernet Controller Driver in the list , the following data about the program is made available to you:
• Safety rating (in the lower left corner). The star rating tells you the opinion other users have about Realtek Ethernet Controller Driver, from "Highly recommended" to "Very dangerous".
• Opinions by other users - Click on the Read reviews button.
• Technical information about the program you wish to uninstall, by clicking on the Properties button.
For example you can see that for Realtek Ethernet Controller Driver:
• The web site of the application is: http://www.realtek.com
• The uninstall string is: C:\Program Files (x86)\InstallShield Installation Information\{8833FFB6-5B0C-4764-81AA-06DFEED9A476}\setup.exe -runfromtemp -removeonly
7. Click the Uninstall button. A confirmation window will show up. accept the removal by clicking the Uninstall button. Advanced Uninstaller PRO will automatically remove Realtek Ethernet Controller Driver.
8. After removing Realtek Ethernet Controller Driver, Advanced Uninstaller PRO will offer to run an additional cleanup. Click Next to start the cleanup. All the items of Realtek Ethernet Controller Driver that have been left behind will be found and you will be able to delete them. By removing Realtek Ethernet Controller Driver with Advanced Uninstaller PRO, you can be sure that no registry items, files or directories are left behind on your computer.
Your system will remain clean, speedy and able to take on new tasks.
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https://sppumoodle.unipune.ac.in/course/index.php?categoryid=121
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#### Numerical Methods for Scientific Computing
It is the first course in Numerical Methods. It starts with an introduction to finite precision mathematics. It covers the methods of root finding, linear equation solvers, eigen value computation, curve fitting & approximations and numerical integration & differentiation.
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https://mathoverflow.net/questions/233778/a-question-on-the-commutativity-degree-of-the-monoid-of-subsets-of-a-finite-grou
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A question on the commutativity degree of the monoid of subsets of a finite group
The commutativity degree $d(G)$ of a finite group $G$ is defined as the ratio $$\frac{|\{(x,y)\in G^2 | xy=yx\}|}{|G|^2}.$$It is well known that $d(G)\leq5/8$ for any finite non-abelian group $G$. If $P(G)$ is the monoid of subsets of $G$ with respect to the usual product of group subsets, then the commutativity degree $d(P(G))$ of $P(G)$ can be defined similarly: $$d(P(G))=\frac{|\{(A,B)\in P(G)^2 | AB=BA\}|}{|P(G)|^2}.$$Which are the connections between $d(G)$ and $d(P(G))$? Is there a constant $c\in (0,1)$ such that $d(P(G))\leq c$ for any finite non-abelian group $G$?
Additional Question: Let $P_k(G)$ be the subset of $P(G)$ consisting of all $k$-subsets of $G$ and $$d(P_k(G))=\frac{|\{(A,B)\in P_k(G)^2 | AB=BA\}|}{|P_k(G)|^2}.$$Clearly, $d(P_1(G))=d(G)$ and, for every $k\in\{1,2,3\}$, $G$ is abelian iff $d(P_k(G))=1$. A similar question can be asked for $d(P_k(G))$, $k=2,3$: is there a constant $c_k\in (0,1)$ such that $d(P_k(G))\leq c_k$ for any finite non-abelian group $G$?
• @Derek Holt: I would say that your argument shows just that any two subsets $A$ and $B$ of cardinality $>|G|/2$ each commute, since $AB=BA=G$... – Ilya Bogdanov Mar 16 '16 at 12:08
• Yes that's right - I have deleted my comment. – Derek Holt Mar 16 '16 at 12:40
• That raises the question for what fraction of the pairs $(A,B)$ of subsets of $G$ is $AB=BA=G$. Could this approach $1$ for large $G$? If so, there would be no such constant $c$. – Derek Holt Mar 16 '16 at 13:55
@Derek Holt is completely right: as $|G|\to \infty$, the fraction of subsets $(A,B)$ with $AB=G$ tends to $1$, so there is no such $c$.
Indeed, assume that $|G|=n$. Let us choose the subsets $A$ and $B$ uniformly and independently. Fix any $g\in G$; there are $n$ pairs $(a,b)$ with $ab=g$, each pair belongs to $A\times B$ with probability $1/4$, and these events are independent for distinct pairs. Thus the probability that $g\notin AB$ is $(3/4)^n$, so the probability that $AB\neq G$ is at most $n(3/4)^n$ which tends to $0$ as $n\to\infty$.
To conclude: if $n$ is large, almost all pairs $(A,B)\in P(G)\times P(G)$ satisfy $AB=BA=G$.
• @GeoffRobinson: I do not fix the cardinalities of $A$ abd $B$; I simply put every element to $A$ with probability $1/2$, the same for $B$ (all $2n$ choices are independent). – Ilya Bogdanov Mar 17 '16 at 12:25
|
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https://gateoverflow.in/290835/gatebook-2019-grand-test-cn-23
|
67 views
Which of the following statements is false about $\text{link state routing (LS)}$, and $\text{distance vector routing (DV)}$
$S1:$ LS, DV both requires each router to obtain a map of the complete topology
$S2:$ DV requires flooding
$S3:$ DV suffers from the count to infinity problem
1. Only $S1$
2. Only $S1$ and $S3$
3. $S1$ and $S2$
4. Only $S2$ and $S3$
+1 vote
DV do not require a map of complete topology. Each node in DV learns topology of its neighbours only.
DV do not require flooding and DV suffers from count to infinity problem.
0
do link state routing flooding ?
|
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https://infoscience.epfl.ch/record/177428
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Infoscience
Journal article
Mathematical modeling of (13)C label incorporation of the TCA cycle: the concept of composite precursor function
A novel approach for the mathematical modeling of (13)C label incorporation into amino acids via the TCA cycle that eliminates the explicit calculation of the labeling of the TCA cycle intermediates is described, resulting in one differential equation per measurable time course of labeled amino acid. The equations demonstrate that both glutamate C4 and C3 labeling depend in a predictable manner on both transmitochondrial exchange rate, V(X), and TCA cycle rate, V(TCA). For example, glutamate C4 labeling alone does not provide any information on either V(X) or V(TCA) but rather a composite "flux". Interestingly, glutamate C3 simultaneously receives label not only from pyruvate C3 but also from glutamate C4, described by composite precursor functions that depend in a probabilistic way on the ratio of V(X) to V(TCA): An initial rate of labeling of glutamate C3 (or C2) being close to zero is indicative of a high V(X)/V(TCA). The derived analytical solution of these equations shows that, when the labeling of the precursor pool pyruvate reaches steady state quickly compared with the turnover rate of the measured amino acids, instantaneous labeling can be assumed for pyruvate. The derived analytical solution has acceptable errors compared with experimental uncertainty, thus obviating precise knowledge on the labeling kinetics of the precursor. In conclusion, a substantial reformulation of the modeling of label flow via the TCA cycle turnover into the amino acids is presented in the current study. This approach allows one to determine metabolic rates by fitting explicit mathematical functions to measured time courses.
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https://www.gamedev.net/forums/topic/467946-references--pointers/
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# References & Pointers
## Recommended Posts
I'm studying a C++ book and I'm stuck on one of the exercises. I was asked whether or not the following code would display the same memory addresses:
#include <iostream>
using namespace std;
int main()
{
int a = 10;
int& b = a;
int* c = &b;
cout << &a << endl;
cout << &b << endl;
cout << &(*c) << endl;
}
I suspected that they would, but I wasn't sure, so I typed it into my IDE, compiled, and ran it. They were the same, but heres what I don't get. &(*c) would equal &b, of course, but why would &b equal &a? b should equal &a, but shouldn't b have it's own memory address? I really shouldn't have read the chapter on pointers in front of the TV. [grin] [Edited by - Silicon Viking on October 10, 2007 6:32:49 PM]
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A reference could be understood as an alias, nothing but another name for the same object or an always-dereferenced pointer.
So in your case you should just think that b is another name for a.
You seem to think that a reference is actually a pointer (saying "b should equal &a") but this is not the case.
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Oh, okay! Thanks!
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References forward all operations, including the ampersand 'address of' operator, onto the referenced instance.
A reference can have its own address, however theres not much overly useful you can do with the address of a reference so there's no easy way to get it. If you need to do things like that then you'd use pointers instead as getting the address of a pointer is a simple case of using a pointer to a pointer.
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The answer to this question may be too advanced for me, or there may be simply too many answers, but for what would you use the address of a variable? The book keeps talking about how efficient it is to pass a reference to a function, but other than that, why would I use either a reference or a pointer?
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Use a reference when:
• you pass a complex type to function or method
• you need to manipulate the value of a function/method argument
• your method/function requires valid (e.g. non-null) input
Use a pointer if you accept invalid (e.g. null) input, since references cannot be null. Use a pointer also, if you need to perform pointer-arithmetic, because you can't do that with references. This includes the use of pointers as iterators for SC++L algorithms.
I hope this is somewhat correct - been a while since I last toyed with C++ [smile]
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1) Forget about pointers. Until you get to the step where I tell you to remember them again, they don't exist.
2) A reference is a way of aliasing a variable that already exists. It has a type like Foo&, where Foo is the type of the thing being aliased. This is basically just so the compiler knows that you want to alias something, rather than create a new variable of the same type.
3) Because a reference *has* to alias something that *already exists*, a variable of a reference type *must* be initialized in its declaration, or the compiler will report an error (i.e. "what is this supposed to reference right now?")
4) Once the reference exists, for all intents and purposes, it *is* the referred-to variable. If you assign to it, it doesn't change what the reference refers to; instead, it changes the value of the referred-to thing. You *can't* make it refer to something else.
5) Why is this useful? Well, normally, when you pass data between functions (in via parameters, or out via a return value), the data is copied. The function works with its own copy of the parameters, and the caller's data is not changed. Similarly, if the function returns, say, some data member of a structure, then the caller gets a copy of that data member: if it changes the copy, the structure is left unchanged.
Sometimes, that's not what you want. By "passing by reference" (i.e. passing a reference to the caller's variable) or "returning by reference" (i.e. returning a reference to some already-existing data), you enable "sharing" of data between functions. That can make a difference to performance (since copying things takes time), but the *primary* reason for using references is because of the *semantics*; i.e. use them for situations where using a separate copy would be *wrong*. (In cases where we use them for performance, we often mark the reference as 'const': this is a promise not to change the referred-to value via that reference. If you don't change something, there's no risk of the calling function "seeing" a change that it shouldn't.)
References can also be used in some circumstances to avoid repeating code, but this technique, its practical applications, etc. are well beyond the scope of this post. (Besides which, when it *is* useful, it's often a sign that the code is badly organized in more fundamental ways.)
6) This can allow for writing obscure code: in particular, it's tempting to use pass by reference to communicate data back from a function, where a return value is more appropriate (i.e. by having the caller examine the changes to the thing it passed in). But it can also be very useful: for example, the standard library container std::vector does this, to allow you to treat it like an array. In particular, its operator[] overload returns one of the elements by reference, so that if the caller assigns to it (e.g. 'myvec[3] = 12;'), it changes the actual contents of the vector automatically.
7) How do we make this work? Well, conceptually, and making huge simplifications for teaching purposes, every variable has a location in memory - its address. We think of memory as linear: a billions-long line of buckets, each of which has numbers 0 through to whatever painted on them, and each of which holds one byte of data. We'll model this with tennis balls: the bucket can hold up to 255 balls in it, and it represents a number, according to the number of balls we put in the bucket.
8) Actually, all our variables are like this. We represent individual characters, for example (and again, we make huge simplifications by ignoring things like Unicode) with a bucket, using an *implicit understanding* that each possible number of balls in the bucket represents some specific symbol; e.g., 65 balls represents a capital 'A'.
9) Of course, some variables could be in more than 256 possible states, so we need multiple buckets (we take a few consecutive ones) to represent them. Common home PC hardware is designed to prefer taking the buckets in groups of four. The C++ 'int' type, on typical compilers for home PC hardware, will use a group of four buckets, which represent a number up to a few billion or so, by basically writing it in base 256 (i.e. the "most significant bucket" contains balls that are 256 times as "valuable" as balls in the next bucket, etc. down to the "least significant bucket", where balls have unit value, and we calculate the number as the sum of the total value of the balls).
10) Remember, though, the buckets have numbers written on the outsides, too. So, we can store a number in a 'quad' of buckets, and have, again, an *implicit understanding* that the number represents some *other* bucket. In particular, we could have it represent the first bucket in a sequence that's used for another variable.
11) So, *one* way that the compiler *could* handle references is to make a reference-variable store a number that indicates the referred-to variable, and *translate* all the code that modifies the reference, so that it instead fetches the number, finds the corresponding bucket(s) (referred-to variable), and modifies that instead.
12) But as far as you're concerned, references are magic. You don't need to think about any of these things; it's the compiler's responsibility to get them right. Sometimes it doesn't need to do any "indirection". It depends on context.
13) Now pointers exist. I deliberately arranged for this to be item 13 ;)
14) The pointer is a variable which is a special kind of number: it represents some memory address (bucket ID). But we can set it to *any* bucket ID. Because of how modern hardware works, the bucket we refer to might be in the middle of a group used for a variable, be part of a variable we're not interested in, be "allocated" (assigned for use) by another program (on modern operating systems, though, if we try to use those buckets, we'll simply crash; we can't actually affect other programs so easily), or in fact not exist.
15) Because of this, they are potentially very dangerous. However, they can also be quite useful, and it is possible in C++ to design classes that 'wrap' them and let us avoid doing "wrong" things with them.
16) There is no magic with pointers. If you assign to the pointer variable, you really assign to it, and change what it points at. (Notice the difference in terminology: "refer to" vs. "point at".) If you want to access the pointed-at thing, you do it manually, via the '*' syntax in C++ ('*ptr' gives you the thing that ptr points at, assuming it really is a pointer).
17) Because there is no magic, C++ doesn't require that you initialize pointers right away. But of course, an uninitialized pointer could be storing *any* memory location, and trying to grab what's at an *unknown* location is a *very* bad idea ("go on, I DARE you to reach in there").
18) For these reasons, the rule of proper C++ design is: use references when you can, and pointers when you have to. There are, of course, a few other such rules of the form "use X when you can, and (raw) pointers when you have to" - the idea being, take whatever steps you can to protect yourself, because in most cases, you won't really pay any performance cost.
19) One of the main reasons for using (wrapped) pointers is the creation of complex data structures, which either need to "share" data, hold on to "optional" data, or hold on to different kinds of data (of different sizes) depending on context. We can share data by declaring a structure that holds a pointer-to-something, and have two instances of the structure have pointers which point at the same thing. In C++, we most commonly hold different "kinds" of data by setting them up to be related through inheritance, and then using a pointer to the base class (which is allowed to point at instances of any derived class, as well, without a cast). For "optional" data, the convention exists that a pointer can be "null"; such pointers are considered to not, in fact, be pointing at anything (another thing references can't do). Note that assigning an integer 0 to a pointer causes it to be null, but the reverse does NOT hold: depending on your platform, the bits that make up a null pointer do NOT necessarily represent a 0 value (i.e. there may be balls in those buckets). The value 0 is handled as a special case by the C++ compiler, and assigning other integers to a pointer value is not legal in C++. (Although you can certainly assign an integer to a pointed-at thing, if that thing is of an appropriate type.)
20) With the '&' syntax, you can ask for the 'address of' a variable - i.e., a value which is a pointer to the variable. This lets you check where things are in memory. In particular, comparing '&a == &b' checks whether a and b are "the same thing", as opposed to merely being equal. (Here we assume that they are of the same exact type.)
Unfortunately, the syntax is a bit confusing, but you must remember that the '&' and '*' you use in expressions are totally different things from the '&' and '*' you use to declare a variable type. Context is king.
21) In C, there were no references, only pointers. They made the '*' symbol work like that so that you could read 'int *foo' and think "*foo is an int". In C++, we are more interested in reading 'int* foo' and thinking "foo is a pointer to an int", because there is more emphasis on type theory in C++. But in both languages, you could write either 'int *foo' or 'int* foo' and have it mean the same thing - or even 'int * foo', for that matter. The whitespace is simply ignored here, in the same way that '2 + 3' and '2+3' are equivalent.
Unfortunately, C++ inherited all of C's behaviour in this regard - in particular, 'int* foo, bar' means that 'foo' is a pointer to an int, but 'bar' is an int. (Looked at from the C perspective, '*foo' and 'bar' are both ints.)
C used the '&' symbol as well to mean "address-of" (to create pointer values), but didn't have the reference meaning (since there were no references in C). The confusion between the uses of '&' in C++ is therefore particularly unfortunate (because it seems to have been set rather arbitrarily). However, it's not that difficult to understand, and should not cause you any problems with a little practice.
22) Therefore, in the original code, 'b' is a reference to 'a', meaning that it IS 'a', for all intents and purposes. So it should come as no surprise that asking for its address gives the same result.
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|
http://mathhelpforum.com/differential-geometry/110747-intersection-compact-sets.html
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# Thread: intersection of compact sets
1. ## intersection of compact sets
Let X be the cartesian product of $\mathbb{R}$ with the usual topology and a two point set with the indiscrete topology. Find two compact subspaces of X such that their intersection is not compact.
Can I get some help please?
2. That's not possible. A compact set is closed in any topology. The intersection of two closed sets is closed in any topology. A closed subset of a compact set is compact in any topology. Therefore, the intersection of two compact sets is compact is always compact no matter what topology you have.
3. Originally Posted by HallsofIvy
That's not possible. A compact set is closed in any topology.
Only if the topology is Hausdorff, otherwise it may not be true. In remark 1.3. in A Note on Topological Properties of Non-Hausdorff Manifolds there's a nice example of a compact non-closed set. It is rather bewildering since the set is the well-known closed interval [0,1], and even more anti-intuitive: this set is Hausdorff (but the whole space, of course, isn't), yet it is a cute exercise to show that under the topology defined there this interval indeed isn't closed.
Tonio
The intersection of two closed sets is closed in any topology. A closed subset of a compact set is compact in any topology. Therefore, the intersection of two compact sets is compact is always compact no matter what topology you have.
.
4. Originally Posted by tonio
.
By the way, all the rest of the argument the Hallsofivy is true. Closed in compact space (i.e closed intersected compact) is always compact, in every topological space, as it is discussed in other threads. Hence this exercise needs to show that there is a non closed compact in this space. Further, they are needed two of these compacts for intersecting them, because closed and compact would give compact . I suppose the non discrete topology in {0,1} is that whose unique open sets are all the space and the empty set. Thus we have to take benefit from the fact that neither $\{0\}$ or $\{1\}$ are open nor closed in $\{0,1\}$ endowed with the trivial topology.
I guess these two subsets
$K_1:=[-1,1]\times \{1\}$
$K_2:=([-1,0] \times \{0\})\cup ((0,1]\times \{1\})$
are compact, and the intersection
$K_1\cap K_2 =(0,1]\times \{1\}$ clearly is not (is isomorphic to (0,1]).
I suggest proving the compactness of these subsets
5. Originally Posted by Enrique2
By the way, all the rest of the argument the Hallsofivy is true. Closed in compact space (i.e closed intersected compact) is always compact, in every topological space, as it is discussed in other threads. Hence this exercise needs to show that there is a non closed compact in this space. Further, they are needed two of these compacts for intersecting them, because closed and compact would give compact . I suppose the non discrete topology in {0,1} is that whose unique open sets are all the space and the empty set. Thus we have to take benefit from the fact that neither $\{0\}$ or $\{1\}$ are open nor closed in $\{0,1\}$ endowed with the trivial topology.
I guess these two subsets
$K_1:=[-1,1]\times \{1\}$
$K_2:=([-1,0] \times \{0\})\cup ((0,1]\times \{1\})$
are compact, and the intersection
$K_1\cap K_2 =(0,1]\times \{1\}$ clearly is not (is isomorphic to (0,1]).
I suggest proving the compactness of these subsets
Is $K_1$ compact? I believe that compact subspaces in this space are exactly those of the form $K \times \{ \pm \infty \}$ where $K$ is compact in $\mathbb{R}$
6. Originally Posted by Jose27
Is $K_1$ compact? I believe that compact subspaces in this space are exactly those of the form $K \times \{ \pm \infty \}$ where $K$ is compact in $\mathbb{R}$
I believe both are compacts. $K_1$ is homeomorphic to $[-1,1]$. Any sequence or net $(x_i,y_i)_i$ in this space is convergent if and only if $(x_i)_i$ is. Notice that $(y_i)_i$ is always convergent to both 0 and 1. Hence, roughly speaking,
$K\times$"anything" is compact iff $K$ is compact in $\mathbb{R}$. The argument of an open recovering
$V_i\times W_i$ also work because $W_i$ is always the whole space. I think $K\subset X$ is compact if and only if the projection $p_1(K)$ is compact in $\mathbb{R}$.
Anyway I prefer people to check this, non Hausdorff spaces are not familiar to me, but I like the problem.
7. Originally Posted by Enrique2
$K_1:=[-1,1]\times \{1\}$
$K_2:=([-1,0] \times \{0\})\cup ((0,1]\times \{1\})$
are compact, and the intersection
$K_1\cap K_2 =(0,1]\times \{1\}$ clearly is not (is isomorphic to (0,1]).
I think this is a nice example. To see $K_1$ is compact and $K_1\cap K_2$ is not compact are rather straightforward.
To check if $K_2$ is compact as Enrique2 already mentioned, any open cover for $K_2$ must cover $K_2':=([-1,0] \times \{0,1\})\cup ((0,1]\times \{0, 1\}) = [-1,1] \times \{0,1\}$. Now we see that $K_2$ is compact.
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,
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# the intersection of two comact sets need not be compact
Click on a term to search for related topics.
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http://www.chegg.com/homework-help/questions-and-answers/particle-track-detectors-used-measure-speed-particles-lifetime-particle-known-particle-x-l-q2654725
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Particle track detectors are used to measure the speed of particles if the lifetime of the particle is known. Particle X has a lifetime of 256.2 ps. These particles are created in an experiment inside the detector by a given reaction. The particles leave 10.6 cm long tracks on average before they decay into other particles not observable by the detector.
--------------------------------------------------------------------------------
What is the average speed of the particles in terms of the speed of light?
Hints:
The speed of the particle is the ratio of the track length and the lifetime. However the simple ratio of these two quantities gives unphysically high speed: 1.379 c. The reason is that the length of the track is measured in the resting frame of the detector. On the other hand the lifetime of the particle is its life expectancy measured in the frame moving with the particle. Either transform the length of the track to the particle's frame, or the particle's lifetime to the detector's frame. You can take the ratio of the tracklength and the lifetime only if they are from the same reference frame.
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https://developer.aliyun.com/article/248576
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# Hybris 体系结构
The hybris Commerce Suite uses a license file which holds information about unlocked functionality in the hybris Commerce Suite. For example, you may or may not be allowed to use Cluster - Technical Guidefunctionality.
license文件当hybris Server启动的时候，被放在${HYBRIS_CONFIG_DIR}/licence这个目录下，我们没有必要明确的去安装这个licenses文件，我们只需要把这个licenses文件放到${HYBRIS_CONFIG_DIR}/licence这个目录下，然后重启hybris Server，就能自动的安装这个Licenses了。
3. Stop the hybris Server.
4. Start the hybris Server:
2、环境变量：
The hybris Commerce Suite uses a number of environment variables that are defined to reference the paths of its various components.
# Default Values of Environment Variables
The table below summarizes the hybris environment variables.
Variable Name
Description
Factory Default
HYBRIS_BIN_DIR
Points to the /bin directory of the hybris Commerce Suite, in which the platform and all extensions are located.
hybris/bin
HYBRIS_CONFIG_DIR
Points to the /config directory of the hybris Commerce Suite, where custom configuration files are stored.
hybris/config
HYBRIS_DATA_DIR
Points to the /data directory of the hybris Commerce Suite, where runtime data is stored.
hybris/data
HYBRIS_LOG_DIR
Points to the /log directory of the hybris Commerce Suite, containing log files from the hybris Server, JDBC logging, etc.
hybris/log
HYBRIS_TEMP_DIR
Points to the /temp directory of the hybris Commerce Suite, where temporary files are stored.
hybris/temp/hybris
3、配置模板（Configuration Templates
The hybris Commerce Suite comes with pre-defined configuration sets ready to use as configuration templates. A configuration template consists of a set of configuration files pre-optimized by hybris for a certain aspect of running the hybris Commerce Suite, such as for use in development and production environment.
# Configuration Template Structure（配置模板的结构）
A configuration template can consist of the following:
• local.properties file
• Configuration files for the Apache Tomcat, such as wrapper.conf or wrapper-debug.conf
4、目录结构：
All extensions developed by hybris are grouped in specific directories under the /bin directory to distinguish between the different kinds of extensions that hybris offers. Additionally, distinguishing the /bin directory from the other directories is beneficial for both partner developers and system administrators when updating the hybris Commerce Suite.
hybris把bin目录和其他的目录分开，其他的目录包括数据啦、日志啦、配置模板啦、、、等等。这样一个显著的好处就是bin目录只有固定的代码，不会有任何改变，若你升级hybris，直接替换这个bin目录就行了，别的客户化的东西，都不用管的。
## Directory Structure Overview
Directory
Description
Environment Variable
For details see hybris Environment Variables.
/bin
Contains the hybris Platform directories, the template directory, and the hybris extensions directory. It may also contain the directory for partner extensions or custom extensions made by customers for their own use.
${HYBRIS_BIN_DIR} • /bin/custom This directory is created during the process of creating the custom extensions. It should contain your own project extensions. For details about creating extensions see the Creating a New Extension document. • /bin/ext-accelerator This directory contains acceleratorcms, acceleratorfacades, acceleratorservices, b2bacceleratorfacades, b2bacceleratorservice. • /bin/ext-addon This directory contains addon extensions. • /bin/ext-channel This directory contains cscockpit, instore, mobileoptionals,mobileservices,print,printcockpit,printhmc. • /bin/ext-commerce This directory contains commerce-related extensions. • /bin/ext-content This directory contains bmecat, classificationsystems,cms2,cmscockpit,importcockpit,mam, productcockpit. • /bin/ext-data This directory contains sample data extensions. • /bin/ext-platform This directory contains admincockpit, backoffice, cockpit, hmc, mcc, platformhmc extensions.${HYBRIS_EXT-PLATFORM_DIR}
• /bin/ext-platform-optional
This directory contains optional platform extensions.
${HYBRIS_EXT-PLATFORM_DIR} • /bin/ext-print This directory contains print, printcockpit and printhmc extensions${HYBRIS_EXT-PRINT}
• /bin/ext-template
This directory contains all extgen templates.
${HYBRIS_EXT-TEMPLATE_DIR} • /bin/platform This directory contains the actual hybris Platform functionalities. It includes core extensions, the build framework, custom extension templates in /extgen, and the application server directories.${HYBRIS_PLATFORM_DIR}
/config
The directory contains your custom configuration files for the hybris Commerce Suite, such as: local.properties,localextensions.xml, andhybrislicence.jar. This directory also contains the files for the customization mechanism of the hybris Commerce Suite.
${HYBRIS_CONFIG_DIR} /data This directory contains runtime data, such as: • Media files, such as product pictures. See also Media folder. • LuceneSearch indexes • HSQLDB files${HYBRIS_DATA_DIR}
/log
This directory contains log files from the hybris Server, JDBC logging, and so on.
${HYBRIS_LOG_DIR} /temp This directory contains temporary files.${HYBRIS_TEMP_DIR}
+ 订阅
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https://dsp.stackexchange.com/questions/481/does-the-autocorrelation-function-completely-describe-a-stochastic-process/488
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# Does the autocorrelation function completely describe a stochastic process?
Is a stochastic process completely described by its autocorrelation function?
If not, which additional properties would be needed?
What is meant by a complete description of a stochastic process? Well, mathematically, a stochastic process is a collection $$\{X(t) : t \in {\mathbb T}\}$$ of random variables, one for each time instant $$t$$ in an index set $$\mathbb T$$, where usually $$\mathbb T$$ is the entire real line or the positive real line, and a complete description means that for each integer $$n \geq 1$$ and $$n$$ time instants $$t_1, t_2, \ldots, t_n \in \mathbb T$$, we know the (joint) distributions of the $$n$$ random variables $$X(t_1)$$, $$X(t_2)$$, $$\ldots, X(t_n)$$. This is an enormous amount of information: we need to know the CDF of $$X(t)$$ for each time instant $$t$$, the (two-dimensional) joint CDF of $$X(t_1)$$ and $$X(t_2)$$ for all choices of time instants $$t_1$$ and $$t_2$$, the (three-dimensional) CDFs of $$X(t_1)$$, $$X(t_2)$$, and $$X(t_3)$$, etc. etc. etc.
So naturally people have looked about for simpler descriptions and more restrictive models. One simplification occurs when the process is invariant to a change in the time origin. What this means is that
• All the random variables in the process have identical CDFs: $$F_{X(t_1)}(x) = F_{X(t_2)}(x)$$ for all $$t_1, t_2$$.
• Any two random variables separated by some specified amount of time have the same joint CDF as any other pair of random variables separated by the same amount of time. For example, the random variables $$X(t_1)$$ and $$X(t_1 + \tau)$$ are separated by $$\tau$$ seconds, as are the random variables $$X(t_2)$$ and $$X(t_2 + \tau)$$, and thus $$F_{X(t_1), X(t_1 + \tau)}(x,y) = F_{X(t_2), X(t_2 + \tau)}(x,y)$$
• Any three random variables $$X(t_1)$$, $$X(t_1 + \tau_1)$$, $$X(t_1 + \tau_1 + \tau_2)$$ spaced $$\tau_1$$ and $$\tau_2$$ apart have the same joint CDF as $$X(t_2)$$, $$X(t_2 + \tau_1)$$, $$X(t_2 + \tau_1 + \tau_2)$$ which as also spaced $$\tau_1$$ and $$\tau_2$$ apart,
• and so on for all multidimensional CDFs. See, for example, Peter K.'s answer for details of the multidimensional case.
Effectively, the probabilistic descriptions of the random process do not depend on what we choose to call the origin on the time axis: shifting all time instants $$t_1, t_2, \ldots, t_n$$ by some fixed amount $$\tau$$ to $$t_1 + \tau, t_2 + \tau, \ldots, t_n + \tau$$ gives the same probabilistic description of the random variables. This property is called strict-sense stationarity and a random process that enjoys this property is called a strictly stationary random process or, more simply, s stationary random process.
Note that strict stationarity by itself does not require any particular form of CDF. For example, it does not say that all the variables are Gaussian.
The adjective strictly suggests that is possible to define a looser form of stationarity. If the $$N^{\text{th}}$$-order joint CDF of $$X(t_1), X(t_2), \ldots, X(t_N)$$ is the same as the $$N^{\text{th}}$$-order joint CDF of $$X(t_1+\tau), X(t_2+\tau), \ldots, X(t_N +\tau)$$ for all choices of $$t_1,t_2, \ldots, t_N$$ and $$\tau$$, then the random process is said to be stationary to order $$N$$ and is referred to as a $$N^{\text{th}}$$-order stationary random process. Note that a $$N^{\text{th}}$$-order stationary random process is also stationary to order $$n$$ for each positive $$n < N$$. (This is because the $$n^{\text{th}}$$-order joint CDF is the limit of the $$N^{\text{th}}$$-order CDF as $$N-n$$ of the arguments approach $$\infty$$: a generalization of $$F_X(x) = \lim_{y\to\infty}F_{X,Y}(x,y)$$). A strictly stationary random process then is a random process that is stationary to all orders $$N$$.
If a random process is stationary to (at least) order $$1$$, then all the $$X(t)$$'s have the same distribution and so, assuming the mean exists, $$E[X(t)] = \mu$$ is the same for all $$t$$. Similarly, $$E[(X(t))^2]$$ is the same for all $$t$$, and is referred to as the power of the process. All physical processes have finite power and so it is common to assume that $$E[(X(t))^2] < \infty$$ in which case, and especially in the older engineering literature, the process is called a second-order process. The choice of name is unfortunate because it invites confusion with second-order stationarity (cf. this answer of mine on stats.SE), and so here we will call a process for which $$E[(X(t))^2]$$ is finite for all $$t$$ (whether or not $$E[(X(t))^2]$$ is a constant) as a finite-power process and avoid this confusion. But note again that
a first-order stationary process need not be a finite-power process.
Consider a random process that is stationary to order $$2$$. Now, since the joint distribution of $$X(t_1)$$ and $$X(t_1 + \tau)$$ is the same as the joint distribution function of $$X(t_2)$$ and $$X(t_2 + \tau)$$, $$E[X(t_1)X(t_1 + \tau)] = E[X(t_2)X(t_2 + \tau)]$$ and the value depends only on $$\tau$$. These expectations are finite for a finite-power process and their value is called the autocorrelation function of the process: $$R_X(\tau) = E[X(t)X(t+\tau)]$$ is a function of $$\tau$$, the time separation of the random variables $$X(t)$$ and $$X(t+\tau)$$, and does not depend on $$t$$ at all. Note also that $$E[X(t)X(t+\tau)] = E[X(t+\tau)X(t)] = E[X(t+\tau)X(t + \tau - \tau)] = R_X(-\tau),$$ and so the autocorrelation function is an even function of its argument.
A finite-power second-order stationary random process has the properties that
1. Its mean $$E[X(t)]$$ is a constant
2. Its autocorrelation function $$R_X(\tau) = E[X(t)X(t+\tau)]$$ is a function of $$\tau$$, the time separation of the random variables $$X(t)$$ and $$X(t+\tau)$$, and does not depend on $$t$$ at all.
The assumption of stationarity simplifies the description of a random process to some extent but, for engineers and statisticians interested in building models from experimental data, estimating all those CDFs is a nontrivial task, particularly when there is only a segment of one sample path (or realization) $$x(t)$$ on which measurements can be made. Two measurements that are relatively easy to make (because the engineer already has the necessary instruments on his workbench (or programs in MATLAB/Python/Octave/C++ in his software library) are the DC value $$\frac 1T\int_0^T x(t)\,\mathrm dt$$ of $$x(t)$$ and the autocorrelation function $$R_x(\tau) = \frac 1T\int_0^T x(t)x(t+\tau)\,\mathrm dt$$ (or its Fourier transform, the power spectrum of $$x(t)$$). Taking these measurements as estimates of the mean and the autocorrelation function of a finite-power process leads to a very useful model that we discuss next.
A finite-power random process is called a wide-sense-stationary (WSS) process (also weakly stationary random process which fortunately also has the same initialism WSS) if it has a constant mean and its autocorrelation function $$R_X(t_1, t_2) = E[X(t_1)X(t_2)]$$ depends only on the time difference $$t_1 - t_2$$ (or $$t_2 - t_1$$).
Note that the definition says nothing about the CDFs of the random variables comprising the process; it is entirely a constraint on the first-order and second-order moments of the random variables. Of course, a finite-power second-order stationary (or $$N^{\text{th}}$$-order stationary (for $$N>2$$) or strictly stationary) random process is a WSS process, but the converse need not be true.
A WSS process need not be stationary to any order.
Consider, for example, the random process $$\{X(t)\colon X(t)= \cos (t + \Theta), -\infty < t < \infty\}$$ where $$\Theta$$ takes on four equally likely values $$0, \pi/2, \pi$$ and $$3\pi/2$$. (Do not be scared: the four possible sample paths of this random process are just the four signal waveforms of a QPSK signal). Note that each $$X(t)$$ is a discrete random variable that, in general, takes on four equally likely values $$\cos(t), \cos(t+\pi/2)=-\sin(t), \cos(t+\pi) = -\cos(t)$$ and $$\cos(t+3\pi/2)=\sin(t)$$, It is easy to see that in general $$X(t)$$ and $$X(s)$$ have different distributions, and so the process is not even first-order stationary. On the other hand, $$E[X(t)] = \frac 14\cos(t)+ \frac 14(-\sin(t)) + \frac 14(-\cos(t))+\frac 14 \sin(t) = 0$$ for every $$t$$ while \begin{align} E[X(t)X(s)]&= \left.\left.\frac 14\right[\cos(t)\cos(s) + (-\cos(t))(-\cos(s)) + \sin(t)\sin(s) + (-\sin(t))(-\sin(s))\right]\\ &= \left.\left.\frac 12\right[\cos(t)\cos(s) + \sin(t)\sin(s)\right]\\ &= \frac 12 \cos(t-s). \end{align} In short, the process has zero mean and its autocorrelation function depends only on the time difference $$t-s$$, and so the process is wide sense stationary. But it is not first-order stationary and so cannot be stationary to higher orders either.
Even for WSS processes that are second-order stationary (or strictly stationary) random processes, little can be said about the specific forms of the distributions of the random variables. In short,
A WSS process is not necessarily stationary (to any order), and the mean and autocorrelation function of a WSS process is not enough to give a complete statistical description of the process.
Finally, suppose that a stochastic process is assumed to be a Gaussian process ("proving" this with any reasonable degree of confidence is not a trivial task). This means that for each $$t$$, $$X(t)$$ is a Gaussian random variable and for all positive integers $$n \geq 2$$ and choices of $$n$$ time instants $$t_1$$, $$t_2$$, $$\ldots, t_n$$, the $$N$$ random variables $$X(t_1)$$, $$X(t_2)$$, $$\ldots, X(t_n)$$ are jointly Gaussian random variables. Now a joint Gaussian density function is completely determined by the means, variances, and covariances of the random variables, and in this case, knowing the mean function $$\mu_X(t) = E[X(t)]$$ (it need not be a constant as is required for wide-sense-stationarity) and the autocorrelation function $$R_X(t_1, t_2) = E[X(t_1)X(t_2)]$$ for all $$t_1, t_2$$ (it need not depend only on $$t_1-t_2$$ as is required for wide-sense-stationarity) is sufficient to determine the statistics of the process completely.
If the Gaussian process is a WSS process, then it is also a strictly stationary Gaussian process. Fortunately for engineers and signal processors, many physical noise processes can be well-modeled as WSS Gaussian processes (and therefore strictly stationary processes), so that experimental observation of the autocorrelation function readily provides all the joint distributions. Furthermore since Gaussian processes retain their Gaussian character as they pass through linear systems, and the output autocorrelation function is related to th input autocorrelation function as $$R_y = h*\tilde{h}*R_X$$ so that the output statistics can also be easily determined, WSS process in general and WSS Gaussian processes in particular are of great importance in engineering applications.
• Could you, please, comment on "White Noise" in that sense? By definition the Autocorrelation at $\tau = 0$ is the variance of the random variables. Does it mean that AWGN (Additive White Gaussian Noise) has infinite variance? I ask it because usually people write $n(t) ~ N(0, {N}_{0} / 2)$, is wrong? Should it be written $n(t) ~ N(0, \delta(0) {N}_{0} / 2)$? Thanks. – Royi Jan 9 '12 at 6:57
• @Drazick Please ask a separate question. – Dilip Sarwate Jan 9 '12 at 14:23
• This is a fantastic mini-course in the definition of stationary processes. I've never seen anything like it--laid out so methodically and clearly. Community Wiki? – abalter Feb 3 '18 at 21:57
• @Dilip Sarwate Excuse me for my ignorance. In the example. Why is E[X(t)]=0 for all t ? Did you assume ergodicity? How did you derive the probability density function of X(t) from the probability density function of theta to compute the expected value? E[X(t)X(s)] = E[cos(t+theta)*cos(s+theta)] right? Which steps did you take to simplify this expression and get to what you wrote? Thanks – VMMF Feb 8 '18 at 16:12
• @VMMF There is NO ergodicity used. $X(t)=\cos(t+\Theta)$ is a discrete random variable because $\Theta$ is a discrete random variable and it takes on values $\pm\cos(t)$ and $\pm\sin(t)$ with equal probability $\frac 14$. Ergo, $E[X(t)]=0$. $X(t)X(s)$ takes on values $\cos(t)\cos(s)$, $(-\cos(t))(-\cos(s))=\cos(t)\cos(s)$, $\sin(t)\sin(s)$ and $(-\sin(t))(-\sin(s))=\sin(t)\sin(s)$ with equal probability $\frac 14$. Hence, $E[X(t)(X(s)]=\frac 12\big(\cos(t)\cos(s)+\sin(t)\sin(s)\big) = \frac 12\cos(t-s)$. Hence, – Dilip Sarwate Feb 9 '18 at 0:12
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http://nrich.maths.org/public/leg.php?code=12&cl=2&cldcmpid=6605
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# Search by Topic
#### Resources tagged with Factors and multiples similar to Some Games That May Be Nice or Nasty:
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### There are 140 results
Broad Topics > Numbers and the Number System > Factors and multiples
### Multiplication Square Jigsaw
##### Stage: 2 Challenge Level:
Can you complete this jigsaw of the multiplication square?
### Multiples Grid
##### Stage: 2 Challenge Level:
What do the numbers shaded in blue on this hundred square have in common? What do you notice about the pink numbers? How about the shaded numbers in the other squares?
### What Do You Need?
##### Stage: 2 Challenge Level:
Four of these clues are needed to find the chosen number on this grid and four are true but do nothing to help in finding the number. Can you sort out the clues and find the number?
### Factor Lines
##### Stage: 2 Challenge Level:
Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.
### Factor-multiple Chains
##### Stage: 2 Challenge Level:
Can you see how these factor-multiple chains work? Find the chain which contains the smallest possible numbers. How about the largest possible numbers?
### A Dotty Problem
##### Stage: 2 Challenge Level:
Starting with the number 180, take away 9 again and again, joining up the dots as you go. Watch out - don't join all the dots!
### What's in the Box?
##### Stage: 2 Challenge Level:
This big box multiplies anything that goes inside it by the same number. If you know the numbers that come out, what multiplication might be going on in the box?
### Seven Flipped
##### Stage: 2 Challenge Level:
Investigate the smallest number of moves it takes to turn these mats upside-down if you can only turn exactly three at a time.
### American Billions
##### Stage: 3 Challenge Level:
Play the divisibility game to create numbers in which the first two digits make a number divisible by 2, the first three digits make a number divisible by 3...
### Which Is Quicker?
##### Stage: 2 Challenge Level:
Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
### Becky's Number Plumber
##### Stage: 2 Challenge Level:
Becky created a number plumber which multiplies by 5 and subtracts 4. What do you notice about the numbers that it produces? Can you explain your findings?
### Light the Lights
##### Stage: 2 Challenge Level:
Investigate which numbers make these lights come on. What is the smallest number you can find that lights up all the lights?
### Got it for Two
##### Stage: 2 and 3 Challenge Level:
Got It game for an adult and child. How can you play so that you know you will always win?
##### Stage: 2 Challenge Level:
If you have only four weights, where could you place them in order to balance this equaliser?
### Crossings
##### Stage: 2 Challenge Level:
In this problem we are looking at sets of parallel sticks that cross each other. What is the least number of crossings you can make? And the greatest?
### Got It
##### Stage: 2 and 3 Challenge Level:
A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.
### Ben's Game
##### Stage: 3 Challenge Level:
Ben passed a third of his counters to Jack, Jack passed a quarter of his counters to Emma and Emma passed a fifth of her counters to Ben. After this they all had the same number of counters.
### What Two ...?
##### Stage: 2 Short Challenge Level:
56 406 is the product of two consecutive numbers. What are these two numbers?
### Divide it Out
##### Stage: 2 Challenge Level:
What is the lowest number which always leaves a remainder of 1 when divided by each of the numbers from 2 to 10?
### GOT IT Now
##### Stage: 2 and 3 Challenge Level:
For this challenge, you'll need to play Got It! Can you explain the strategy for winning this game with any target?
### Repeaters
##### Stage: 3 Challenge Level:
Choose any 3 digits and make a 6 digit number by repeating the 3 digits in the same order (e.g. 594594). Explain why whatever digits you choose the number will always be divisible by 7, 11 and 13.
### Three Times Seven
##### Stage: 3 Challenge Level:
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
### Colour Wheels
##### Stage: 2 Challenge Level:
Imagine a wheel with different markings painted on it at regular intervals. Can you predict the colour of the 18th mark? The 100th mark?
### Odds and Threes
##### Stage: 2 Challenge Level:
A game for 2 people using a pack of cards Turn over 2 cards and try to make an odd number or a multiple of 3.
### Down to Nothing
##### Stage: 2 Challenge Level:
A game for 2 or more people. Starting with 100, subratct a number from 1 to 9 from the total. You score for making an odd number, a number ending in 0 or a multiple of 6.
### A First Product Sudoku
##### Stage: 3 Challenge Level:
Given the products of adjacent cells, can you complete this Sudoku?
### Factors and Multiples Game
##### Stage: 2 and 3 Challenge Level:
A game in which players take it in turns to choose a number. Can you block your opponent?
##### Stage: 3 Challenge Level:
A mathematician goes into a supermarket and buys four items. Using a calculator she multiplies the cost instead of adding them. How can her answer be the same as the total at the till?
### Mystery Matrix
##### Stage: 2 Challenge Level:
Can you fill in this table square? The numbers 2 -12 were used to generate it with just one number used twice.
### The Moons of Vuvv
##### Stage: 2 Challenge Level:
The planet of Vuvv has seven moons. Can you work out how long it is between each super-eclipse?
### Product Sudoku 2
##### Stage: 3 and 4 Challenge Level:
Given the products of diagonally opposite cells - can you complete this Sudoku?
### Times Right
##### Stage: 3 Challenge Level:
Using the digits 1, 2, 3, 4, 5, 6, 7 and 8, mulitply a two two digit numbers are multiplied to give a four digit number, so that the expression is correct. How many different solutions can you find?
### It Figures
##### Stage: 2 Challenge Level:
Suppose we allow ourselves to use three numbers less than 10 and multiply them together. How many different products can you find? How do you know you've got them all?
### Diggits
##### Stage: 3 Challenge Level:
Can you find what the last two digits of the number $4^{1999}$ are?
### Multiplication Series: Number Arrays
##### Stage: 1 and 2
This article for teachers describes how number arrays can be a useful reprentation for many number concepts.
### Cuboids
##### Stage: 3 Challenge Level:
Find a cuboid (with edges of integer values) that has a surface area of exactly 100 square units. Is there more than one? Can you find them all?
### Factor Track
##### Stage: 2 Challenge Level:
Factor track is not a race but a game of skill. The idea is to go round the track in as few moves as possible, keeping to the rules.
### Curious Number
##### Stage: 2 Challenge Level:
Can you order the digits from 1-6 to make a number which is divisible by 6 so when the last digit is removed it becomes a 5-figure number divisible by 5, and so on?
### Multiply Multiples 1
##### Stage: 2 Challenge Level:
Can you complete this calculation by filling in the missing numbers? In how many different ways can you do it?
### Multiply Multiples 2
##### Stage: 2 Challenge Level:
Can you work out some different ways to balance this equation?
### Factors and Multiples for Two
##### Stage: 2 and 3 Challenge Level:
Factors and Multiples game for an adult and child. How can you make sure you win this game?
### Multiply Multiples 3
##### Stage: 2 Challenge Level:
Have a go at balancing this equation. Can you find different ways of doing it?
### Three Dice
##### Stage: 2 Challenge Level:
Investigate the sum of the numbers on the top and bottom faces of a line of three dice. What do you notice?
### Number Detective
##### Stage: 2 Challenge Level:
Follow the clues to find the mystery number.
### Tiling
##### Stage: 2 Challenge Level:
An investigation that gives you the opportunity to make and justify predictions.
### Stars
##### Stage: 3 Challenge Level:
Can you find a relationship between the number of dots on the circle and the number of steps that will ensure that all points are hit?
### Venn Diagrams
##### Stage: 1 and 2 Challenge Level:
Use the interactivities to complete these Venn diagrams.
### The Remainders Game
##### Stage: 2 and 3 Challenge Level:
A game that tests your understanding of remainders.
### Neighbours
##### Stage: 2 Challenge Level:
In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square?
### Round and Round the Circle
##### Stage: 2 Challenge Level:
What happens if you join every second point on this circle? How about every third point? Try with different steps and see if you can predict what will happen.
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https://theanimegallery.com/sego-lily-orhkov/tsivxt.php?tag=29594f-permutation-matrix-squared
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Let D = {d ij}, i = 1,…, N; j = 1,…, N consist of the distances or dissimilarities between every pair (i, j) of sampling units. Every row and column therefore contains precisely a single 1 with 0s everywhere else, and every permutation corresponds to a unique permutation matrix. Novel set during Roman era with main protagonist is a werewolf. Go to your Tickets dashboard to see if you won! $\left[ \begin{array}{r} 3 & 6 & -5 & 4 \\ -2 & 0 & 6 & 0 \\ 1 & 1 & 2 & 2 \\ 0 & 3 & -1 & -1 \end{array} \right]$, In Exercises $23-28,$ find the determinant of the matrix. Description : The calculator allows to calculate online the number of permutation of a set of n elements without repetition. And it doesn't need to be … Working on it. Let us assume that one of them, (ii 1,, k ) has length k, and let λ∈ p be an eigenvalue of pλ an kth-root , of unity. We also classify the quantum magic squares that dilate to a quantum permutation matrix with commuting entries and prove a quantitative lower bound on the diameter of this set. An example is 1 0 0 0 1 P= 0 . The vector, as you said, is (i+j). Generating all permutations of a given string, Multiplication of (0,1)-matrix with a (0,1)-vector. $F(A)=c d$c. A permutation of a set of n elements is an arrangement of this n elements. Odd Permutation. For example m[0][100] will be very far from m[100][0] and all others with similar probability. 0. On the algorithmic front, the seriation problem was shown to be NP-Complete by [10]. In this paper a square cellular network for data per-mutation in a SIMD model is described. Shifting rows and columns (if you want to rearrange the rows, you must rearrange the columns in the same way, or the matrix won't make sense for most operations) is called "permutation" of the matrix. It has n 2 = 4 2–permuters only, and realizes an arbitrary permutation pattern in two passes. The number of iterations . Now suppose that we multiply this adjacency matrix times itself (i.e. Sparse matrices provide efficient storage of double or logical data that has a large percentage of zeros. The function above works for d<=N, but not d>N (the lower right half of the matrix). This matrix and the next 19 matrices are represented at the same time. A Matrix that exchanges 2 or more rows is called a permutation matrix. If the transpose of a matrix is equal to the negative of itself, the matrix is said to be skew symmetric. The symmetries are determined by the images of the vertices, that can, in turn, be described by permutations. $$\text{max}(n_a, m_a, n_b, m_b)$$. permutation matrices of size n: Section: A magic square is a square of … The Order of a Permutation. So this would be square. Permutation Matrix A permutation matrix is a square matrix1 in which is zero everywhere apart from having only one ‘1’ on every row and in every column. Now to deal with the lower right half. In the ShuffleNet architecture [14, 23], �is preset by the designers and will be called “manual”. How can I pay respect for a recently deceased team member without seeming intrusive? But it can be some other way as long as elements of the same diagonal are mostly grouped. 1.Compute an orthogonal matrix Q2R m, an upper triangular matrix R2R n, and a permutation matrix P2R such that QT AP= R 0 : 2.Compute QT b= c d : 3.Solve Ry= c: 4.Set x= Py: D. Leykekhman - MATH 3795 Introduction to Computational MathematicsLinear Least Squares { 9 1 0 0 Find the determinant of this matrix. Such a matrix is always row equivalent to an identity. For a diagonalizable matrix like yours, you can use the eigendecomposition A = Q*L*Q^-1. Click 'Join' if it's correct, By clicking Sign up you accept Numerade's Terms of Service and Privacy Policy. I (n) for . no squares and division but programatic conditionals are OK), For a more graphical reference, I'm looking for something like this. I don't have an account. A permutation matrix is a square matrix obtained from the same size identity matrix by a permutation of rows. First things first. A square matrix is called a permutation matrix if it contains the entry 1 exactly once in each row and in each column, with all other entries being 0. site design / logo © 2020 Stack Exchange Inc; user contributions licensed under cc by-sa. [From BBC's The Story of Maths on Cantor's argument]. EMAILWhoops, there might be a typo in your email. How much did the first hard drives for PCs cost? Det(P) = An example is Find the determinant of this matrix. Your question is a little unclear, but by the graphic you want a function that describes the mapping of that path, for example f(1,2) = 8. i+j gives the index of the diagonal, call it d. There are (d+1)d/2 elements in the diagonals above that one. Here’s an example of a $5\times5$ permutation matrix. Whoops, there might be a typo in your email. Just that the elements walked on the diagonals are mostly grouped nearby. I can break it down into cycles: sigma = <1,4,6>compose<3,5> thanks. How can I confirm the "change screen resolution dialog" in Windows 10 using keyboard only? Not necessarily. I have a set of items of size N. The items are sorted by probability. Thanks for contributing an answer to Stack Overflow! Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide. a 2x6 permutation matrix. however, there's actually no need for the, @lijie: I would expect you to have continuity problems without the, yeah i mean, OP doesn't seem to need it. Find a noninvertible $2 \times 2$ matrix whose entries are four distinct prime numbers, or explain why no such matrix existsb. You must be logged in to bookmark a video. (1 point) A square matrix is called a permutation matrix if each row and each column contains exactly one entry 1, with all other entries being 0. Before we look at determinants, we need to learn a little about permutations. For example m[0][100] will be very far from m[100][0] and all others with similar probability. if PPT = , then P is its own inverse and for every i and j in {1, 2, 3, … n}, ,,(),,1(), T ij jipi j p j ipji Function as.matrix.word () coerces a vector of permutations in word form to a matrix, each row of which is a word. Squaring matrix 5.13. Repeated application of a particular permutation of the elements of an . det (P) =. Default=False. For this reason, using sparse matrices can significantly reduce the amount of memory required for data storage. Permutation Matrix. A permutation matrix is obtained by performing a sequence of row and column interchanges on the identity matrix. The first thing to note is that a square matrix in row echelon form is upper triangular. Skew Symmetric Matrix. Stack Overflow for Teams is a private, secure spot for you and Every row and every column of a permutation matrix contain exactly one nonzero entry, which is 1: There are two 2 2 permutation matrices: [1 0 0 1]; [0 1 1 0]: There are six 3 3 permutation matrices. See Example 4, Which of the following functions $F$ of $A=\left[\begin{array}{ll}a & b \\ c & d\end{array}\right]$ are linear in both columns? I'm looking for a function f(i,j) to give the position on the permutated matrix/vector. On the one hand, ex A matrix consisting of only zero elements is called a zero matrix or null matrix. Each such matrix, say P, represents a permutation of m elements and, when used to multiply another matrix, say A, results in permuting the rows (when pre-multiplying, to form PA) or columns (when post-multiplying, to form AP) of the matrix A. If two rows of a matrix are equal, its determinant is zero. Let $$A$$ be a square matrix with a row or a column of 0's. The element position in the vector is min(i, N-j). (1 point) A square matrix is called a permutation matrix if each row and each column contains exactly one entry 1, with all other entries being 0. The dimension of square array is specified based on the highest dimension, i.e. Notice that column space of M' is of higher order than the column space of elem'.This implies that there does not exist a linear mapping from elem' to M' because a linear mapping cannot increase the row or column space of a matrix (useful to think about this as a transformation of basis).. Define 2x2 and 3x3 permutation matrices. The amd function tends to be faster than symamd, and also tends to return better orderings than symamd. $F(A)=a c$d. by solving the seriation problem on the squared data matrix. This preview shows page 1 - 2 out of 2 pages.. 6. R squares tells us the proportion of variance in the outcome measure that is explained by the predictors. Who first called natural satellites "moons"? Our educator team will work on creating an answer for you in the next 6 hours. From these three properties we can deduce many others: 4. Active 9 years, 9 months ago. $F(A)=b c$b. See Example 4. See Example 6. Equality of matrices Two matrices $$A$$ and $$B$$ are equal if and only if they have the same size $$m \times n$$ and their corresponding elements are equal. This matrix and the next 19 matrices are represented at the same time. to C1P can be obtained by solving the seriation problem on the squared data matrix. The permutation matrix �is a square binary matrix with exactly one entry of one in each row and each column and zeros elsewhere. The following are the full set of all 2 2 permutation matrices: 1 0 0 1 (1) 0 1 1 0 (2) Let P be an n n permutation matrix. Well, I know this is probably something very simple but it's been many years since school/uni and Wolframalpha isn't helping. Is Statistics less important in the era of big data than in old days? The thing I'm missing now is how to deal when the diagonal index > N, then the (d+1)*(d/2) prior elements isn't true anymore. Positional chess understanding in the early game. Let's call it sigma. Why did I measure the magnetic field to vary exponentially with distance? how would I calculate (sigma)^2? We start from the identity matrix , we perform one interchange and obtain a matrix , we perform a second interchange and obtain another matrix , and so on until at the … I. It is denoted by a permutation sumbol of -1. A piece of wax from a toilet ring fell into the drain, how do I address this? By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Service. Efficient search for permutations that contain sub-permutations via array operations? In Exercises 39-54, find the determinant of the matrix.Expand by cofactors on the row or column that appears to make the computations easiest. While full (or dense) matrices store every single element in memory regardless of value, sparse matrices store only the nonzero elements and their row indices. Are you looking for space filling curves? Matrix A must be square. The Order of a Permutation. It doesn't need to be a square matrix, it can be a vector [N*N]. So a square matrix is any matrix that has the same number of rows as columns. For the intents of this calculator, "power of a matrix" means to raise a given matrix to a given power. The square root of the matrix can then be computed with the square root of each element of L , as B = Q*L^(1/2)*Q^-1 . Now, if we had matrix such as this one, this has two columns, but only one row, so this wouldn't be square anymore. I assume you mean that all matrix entries are to be non-negative integers and that, correspondingly, the permutations are to be considered as among objects for which these are the counts - that is, an arrangement of [5,7,11,4] like objects is considered a "permutation" or rearrangement of [4,7,3,13] objects. We will treat "self-ties" as zeros, which, effectively, ignores them. And the length of the vector N-abs(N-(i+j)). A square matrix m[N][N] of those items, in C style memory organization, would have elements with similar probabilities spread out. Permutation Matrix A permutation matrix is a matrix obtained by permuting the rows of an identity matrix according to some permutation of the numbers 1 to. A diagonal matrix is called the identity matrix if the elements on its main diagonal are all equal to $$1.$$ (All other elements are zero). Let the vertices of a square be labeled 1, 2, 3 and 4 (counterclockwise around the square starting with 1 in the top left corner). So if you don't mind I'll remove that +1, so that f(0,0)=0. What does it mean to “key into” something? Therefore, this permutation is also the transformation "diagram" which represents the "type" of the square. How to generate all permutations of a list? Summary : To calculate online the number of permutation of a set of n elements. Matrix permutation, blocks, and images. Note: the permutation "complement to n²+1" is the permutation which makes a correspondence between each number and its complement to n²+1. $\left[ \begin{array}{r} 5 & 2 & 0 & 0 & -2 \\ 0 & 1 & 4 & 3 & 2 \\ 0 & 0 & 2 & 6 & 3 \\ 0 & 0 & 3 & 4 & 1 \\ 0 & 0 & 0 & 0 & 2 \end{array} \right]$, $\left[ \begin{array}{r} 3 & 2 & 4 & -1 & 5 \\ -2 & 0 & 1 & 3 & 2 \\ 1 & 0 & 0 & 4 & 0 \\ 6 & 0 & 2 & -1 & 0 \\ 3 & 0 & 5 & 1 & 0 \end{array} \right]$, $\left[ \begin{array}{r} 1 & 4 & 3 & 2 \\ -5 & 6 & 2 & 1 \\ 0 & 0 & 0 & 0 \\ 3 & -2 & 1 & 5 \end{array} \right]$, Given a square matrix $A^{-1}$, find matrix $A$.$$A^{-1}=\left[\begin{array}{lll}0 & 0 & 1 \\0 & 1 & 0 \\1 & 0 & 0\end{array}\right]$$, $\left[ \begin{array}{r} 1 & 0 & 0 \\ -1 & -1 & 0 \\ 4 & 11 & 5 \end{array} \right]$.
2020 permutation matrix squared
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https://math.stackexchange.com/questions/3013705/prove-o-bigcup-j-1-infty-o-j-and-e-subset-bigcup-j-1-infty-e-j-im/3013706
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# Prove $O = \bigcup_{j=1}^\infty O_j$ and $E \subset \bigcup_{j=1}^\infty E_j \implies O-E \subset \bigcup_{j=1}^{+\infty}\left(O_j-E_j\right)$
Prove that
$$O = \bigcup_{j=1}^\infty O_j \quad \text{and} \quad E = \bigcup_{j=1}^\infty E_j \quad \implies \quad O-E \subset \bigcup_{j=1}^{+\infty}\left(O_j-E_j\right)$$
Below is my attempted proof, I'm stuck at the last expression.
Proof
$$O - E = \left(\bigcup_{j=1}^\infty O_j\right) - \left(\bigcup_{j=1}^\infty E_j\right) = \left(\bigcup_{j=1}^\infty O_j\right) \cap \left(\bigcup_{j=1}^\infty E_j\right)^c = \left(\bigcup_{j=1}^\infty O_j\right) \cap \left(\bigcap_{j=1}^\infty E^c_j\right)$$
I'm not sure how to handle the last "intersection of intersections". But I get the feeling my approach is just confusing in general. Thank you.
If $$x \in O - E$$, then there exists $$j$$ such that $$x \in O_j$$. Then $$x \in O_j - E_j$$ as well since $$x \notin E_j$$.
• What if $O_j=E_j=\{1\}$ for every $j,$ and $E=\emptyset$? Then $\{1\}=O=O-E$ but $\cup_j(O_j-E_j)=\cup_j\emptyset=\emptyset.$ – DanielWainfleet Nov 26 '18 at 7:01
• @DanielWainfleet I misread $E \subset \bigcup_j E_j$ as $E = \bigcup_j E_j$. I suspsect this is a typo, since in the first step of OP's proof attempt they use the latter. – angryavian Nov 26 '18 at 17:09
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https://proofwiki.org/wiki/Fourth_Sylow_Theorem
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Fourth Sylow Theorem
Theorem
The number of Sylow $p$-subgroups of a finite group is congruent to $1 \pmod p$.
Proof 1
Let $G$ be a finite group such that $\order G = k p^n$ where $p \nmid k$ and $n > 0$.
Let $r$ be the number of Sylow $p$-subgroups of $G$.
We want to show that $r \equiv 1 \pmod p$.
Let $\mathbb S = \set {S \subseteq G: \card S = p^n}$, that is, the set of all of subsets of $G$ which have exactly $p^n$ elements.
From the reasoning in the First Sylow Theorem, we have:
$\size {\mathbb S} = \dbinom {p^n k} {p^n}$
Let $G$ act on $\mathbb S$ by the group action defined in Group Action on Sets with k Elements::
$\forall S \in \mathbb S: g \wedge S = g S = \set {x \in G: x = g s: s \in S}$
there are exactly as many Sylow $p$-subgroups as there are orbits whose length is not divisible by $p$.
all the terms in the Partition Equation are divisible by $k$, perhaps also divisible by $p$.
We can write the Partition Equation as:
$\size {\mathbb S} = \size {\Orb {S_1} } + \size {\Orb {S_2} } + \cdots + \size {\Orb {S_r} } + \size {\Orb {S_{r + 1} } } + \cdots + \size {\Orb {S_s} }$
where the first $r$ terms are the orbits containing the Sylow $p$-subgroups:
$\Stab {S_i}$
For each of these:
$\order G = \size {\Orb {S_i} } \times \size {\Stab {S_i} } = p^n \size {\Orb {S_i} }$
Thus:
$\size {\Orb {S_i} } = k$
for $1 \le i \le r$.
Each of the rest of the orbits are divisible by both $p$ and $k$, as we have seen.
So:
$\size {\mathbb S} = k r + m p k$
where:
the first term corresponds to the $r$ orbits containing the Sylow $p$-subgroups
the second term corresponds to all the rest of the orbits
$m$ is some unspecified integer.
That is, there exists some integer $m$ such that:
$\size {\mathbb S} = \dbinom {p^n k} {p^n} = k r + m p k$
Now this of course applies to the special case of the cyclic group $C_{p^n k}$.
In this case, there is exactly one subgroup for each divisor of $p^n k$.
In particular, there is exactly one subgroup of order $p^n$.
Hence, in this case:
$r = 1$
So we have an integer $m'$ such that $\dbinom {p^n k} {p^n} = k + m' p k$.
We can now equate these expressions:
$\displaystyle k r + m p k$ $=$ $\displaystyle k + m' p k$ $\displaystyle \leadsto \ \$ $\displaystyle r + m p$ $=$ $\displaystyle 1 + m' p$ dividing by $k$ $\displaystyle \leadsto \ \$ $\displaystyle r - 1$ $=$ $\displaystyle p \paren {m' - m}$ $\displaystyle \leadsto \ \$ $\displaystyle r - 1$ $\equiv$ $\displaystyle 0 \pmod p$ $\displaystyle \leadsto \ \$ $\displaystyle r$ $\equiv$ $\displaystyle 1 \pmod p$
and the proof is complete.
$\blacksquare$
Proof 2
Let $G$ be a finite group of order $p^n m$, where $p \nmid m$ and $n > 0$.
Let $r$ be the number of Sylow $p$-subgroups of $G$.
Let $H$ be a Sylow $p$-subgroup of $G$.
We have that:
$\order H = p^n$
$\index G H = m$
Let $S_1, S_2, \ldots, S_m$ denote the elements of the left coset space of $G / H$.
We have that $H$ acts on $G / H$ by the rule:
$g * S_i = g S_i$
for $S_i \in G / H$.
Unless $H = G$ and $r = 1$, there is more than $1$ orbit.
We have that $H$ is the stabilizer of the coset $H$, which must be one of $S_1, S_2, \ldots, S_m$.
Let $S_1, S_2, \ldots, S_k$ be the elements of $G / H$ whose stabilizer is $H$.
From the Orbit-Stabilizer Theorem and from $\order H = p^n$ we see there are $2$ cases:
$(1): \quad$ The orbit of $S_i$ contains $p^t$ elements where $0 < t < n$
$(2): \quad$ The orbit of $S_i$ contains only the element $S_i$.
$(2)$ occurs if and only if $S_i$ is one of the cosets $S_1, S_2, \ldots, S_k$ whose stabilizer is $H$.
So counting the elements of $G / H$, we see that:
$m = k + u p$
or:
$m \equiv k \pmod p$
From the Fifth Sylow Theorem, we have:
$m \equiv k r \pmod p$
and so:
$k r \equiv k \pmod p$
from which it follows:
$r \equiv 1 \pmod p$
because $k \not \equiv 0 \pmod p$.
Hence the result.
$\blacksquare$
Also known as
Some sources call this the second Sylow theorem.
Others merge this result with what we call the Fifth Sylow Theorem and call it the third Sylow theorem.
Source of Name
This entry was named for Peter Ludwig Mejdell Sylow.
Historical Note
When cracking open the structure of a group, it is a useful plan to start with investigating the prime subgroups.
The Sylow Theorems are a set of results which provide us with just the sort of information we need.
Ludwig Sylow was a Norwegian mathematician who established some important facts on this subject.
He published what are now referred to as the Sylow Theorems in $1872$.
The name is pronounced something like Soolof.
There is no standard numbering for the Sylow Theorems.
Different authors use different labellings.
Therefore, the nomenclature as defined on $\mathsf{Pr} \infty \mathsf{fWiki}$ is to a greater or lesser extent arbitrary.
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http://math.stackexchange.com/users/34472/johannes-bauer
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Johannes Bauer
less info
reputation
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1 Proof that $\mathbb N$ is finite
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+5 Submanifolds of a space of functions? +18 Proof that $\mathbb N$ is finite
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4 Tags
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http://www.physicsforums.com/showthread.php?t=297491
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# Energy balance from mechanical to electrical energy
by PhiliosKassin
Tags: balance, electrical, energy, mechanical
P: 1 A mass is winded via string aroung a flywheel and allowed to fall a specific height before detachement. The flywheel is connected to a small DC motor via gears and starts generating electricity once the mass is allowed to fall.. Now without the DC motor ( generator) the equation of energy balance is: mgh = (0.5mv^2+ (0.5Iω^2) + ( 0.5Iω^2 x (n1/n2) where I is the moment of inertia of flywheel and ω is the angular velocity ( which should be equal to the angular max velocity at point of mass detachment) n1 = number of revs of flywheel before detachement of mass n2 = number of revs of flywheel after detachement the third term in the equation is the work done to overcome friction. Now the question is : What form is the equation going to have when a DC motor is attached to the flywheel to be allowed to transform rotational energy to electrical? mgh = ? the electrical energy is in the form of UIt
P: 107 It seems that one has to assume the friction is independent of the load. Let n3 = number of revs of flywheel after detachment, and E = electrical energy. I think it is not hard to see E = (0.5Iω^2)(n2-n3)/n2 Is that what you are after?
P: 4,664 Suppose the height of initial release of the mass minus the height of detachment is h. Then if the mass falls freely (without flywheel), the total kinetic energy of the mass is mgh = (1/2)mv2. But in the case where it is attached to the flywheel, its final velocity at point of detachment is v1. So its energy at release is now (1/2)mv12. So the missing energy is (1/2)m[v2 - v12]. This was all transferred to the flywheel. If the flywheel were frictionless and the generator perfect, all the flywheel energy would be converted to electric power. All inertial energy remaining in the flywheel after release of the mass would also be converted to electric power. To maximize the total electric energy, the objective then is to make the final velocity of the mass v1 as small as possible. If the flywheel were massive and v1 were small, then the electrical energy would be nearly mgh. If mgh were expressed in joules, then mgh/3600 would be the energy in watt-hours, or in volt amp hours.
P: 1
## Energy balance from mechanical to electrical energy
pls what is the energy balance equation in electric machines?
Related Discussions Classical Physics 2 Classical Physics 2 Electrical Engineering 2 General Physics 4 Introductory Physics Homework 3
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https://www.physicsforums.com/threads/electron-charge.106906/
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# Electron charge
1. Jan 15, 2006
### Punchlinegirl
You have 0.6 kg of water. One mole of water has a mass of 18 g/mol and each molecule of water contains 10 electrons since water is H2O. What is the total electron charge contained in this volume of water? Answer in units for C.
First I converted 0.6 kg to 600 g. Then I divided that by 18 to get the number of moles, which was 33.3. Then I multiplied it by Avogadro's number to get the number of molecules and got 2.01 x 10^25. Then I multiplied it by the number of electrons, and got 2.01 x 10^26. Finally, I multiplied it by the electon charge, 1.602 x 10^-19, and got 3.21 x 10^7. This isn't right.
2. Jan 15, 2006
### stunner5000pt
it seems fine to me.. why do you think it's wrong?
3. Jan 16, 2006
### Punchlinegirl
It's an online homework problem, and when I typed in the answer it said it was wrong... I have no idea why though... I don't know any other way to do it.
Similar Discussions: Electron charge
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http://schools-wikipedia.org/images/90/9065.gif.htm
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# File:Exp series.gif
Exp_series.gif(292 × 392 pixels, file size: 51 KB, MIME type: image/gif, looped, 9 frames, 9.0 s)
Description Illustration of the en:Exponential function Date Oleg Alexandrov 03:11, 30 August 2007 (UTC) Source self-made with MATLAB. Author Oleg Alexandrov
This chart was created with MATLAB.
I, the copyright holder of this work, release this work into the public domain. This applies worldwide.In some countries this may not be legally possible; if so:I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.
## MATLAB source code
% The exponential function as the sum of its Taylor series
function main()
% KSmrq's colors
red = [0.867 0.06 0.14];
blue = [0, 129, 205]/256;
green = [0, 200, 70]/256;
yellow = [254, 194, 0]/256;
white = 0.99*[1, 1, 3];
% Set up the grid and other parameters
N = 100;
A = -3; B = 3;
X = linspace(A, B, N);
Y = exp(X);
D = max(Y); C = -0.2*D;
% plot the frames
Sum = 0*X; Term = 0*X+1;
num_frames = 8;
for j=0:num_frames
Sum = Sum+Term;
Term = Term.*X/(j+1);
% Set up the figure
lw = 3; % linewidth
fs = 20; % font size
figure(1); clf; set(gca, 'fontsize', fs);
hold on; grid on;
set(gca, 'DataAspectRatio', [1 3 1]); % aspect ratio
plot_axes (A, B, C, D, lw/1.3);
plot(X, Sum, 'colour', blue, 'linewidth', lw);
plot(X, Y, 'colour', red, 'linewidth', lw);
axis([A, B, C, D]);
text_str = sprintf('{\\it n}=%d', j)
H= text (1.2, 18, text_str, 'fontsize', floor(1.2*fs))
frame=sprintf('Frame%d.eps', 1000+j);
disp(frame)
saveas(gcf, frame, 'psc2');
end
% Convert to animation with the command
% convert -antialias -loop 10000 -delay 100 -compress LZW Frame100* Exp_series.gif
function plot_axes (A, B, C, D, lw)
black = [0, 0, 0];
plot([A B], [0, 0], 'linewidth', lw, 'colour', black);
plot([0, 0], [C, D], 'linewidth', lw, 'colour', black);
The following pages on Schools Wikipedia link to this image (list may be incomplete):
## Want to know more?
Wikipedia for Schools was collected by SOS Childrens Villages. Thanks to SOS Children, 62,000 children are enjoying a happy childhood, with a healthy, prosperous future ahead of them. You can help by sponsoring a child.
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https://socratic.org/questions/how-do-you-solve-4-2-5x-6-3-1-3x
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Algebra
Topics
# How do you solve 4( 2- 5x ) = 6- 3( 1- 3x )?
Jul 28, 2018
$x = \frac{5}{29}$
#### Explanation:
$4 \left(2 - 5 x\right) = 6 - 3 \left(1 - 3 x\right)$
Expand the brackets
$8 - 20 x = 6 - \left(3 - 9 x\right)$
$8 - 20 x = 6 - 3 + 9 x$
Simplify
$8 - 20 x = 3 + 9 x$
Move the $x$ onto one side
$29 x = 5$
Divide both sides by $29$
$x = \frac{5}{29}$
Jul 28, 2018
$x = \frac{5}{29}$
#### Explanation:
We can distribute the $4$ on the left side, and the $- 3$ on the right. Doing this, we now have
$8 - 20 x = 6 - 3 + 9 x$
We can combine like terms to get
$8 - 20 x = 3 + 9 x$
Let's get our constants on one side by subtracting $8$ from both sides:
$- 20 x = - 5 + 9 x$
Next, subtract $9 x$ from both sides to get
$- 29 x = - 5$
Lastly, we can divide both sides by $- 29$ to get
$x = \frac{5}{29}$
Hope this helps!
##### Impact of this question
1361 views around the world
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http://www.science.gov/topicpages/r/root+3ag+due.html
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These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1
E-print Network
Increased nitrogen leaching following soil freezing is due to decreased root uptake in a northern inorganic nitrogen losses from soil during the following growing season. Decreased nitrogen retention the effects of soil freezing on root uptake and leaching of inorganic nitrogen simultaneously. Snow removal
Templer, Pamela
2
PubMed
The prognosis for surgical treatment in cases of upper brachial plexus palsy due to spinal roots avulsion is somewhat better than in cases of total palsy. The main reasons are better possibilities for surgical reinnervation using regional donors i.e. the medial pectoral and the thoracodorsal nerves, and a shorter time span for nerve regeneration. Regional donor nerves, alone or in combination with upper intercostals and/or the spinal accessory nerve, were used in 13 cases for the reinnervation of the musculocutaneous and/or the axillary nerves. The value of the regional donors is analysed and compared with that of the spinal accessory and intercostal nerves. The value is documented throughout the results of surgical treatment with a follow-up period of at least 18 months after surgery. PMID:2573856
Samardzic, M; Joksimovic, M; Antunovic, V; Grujicic, D
1989-09-01
3
PubMed
Tarlov cysts and nerve roots anomalies usually involve lumbosacral roots and are often asymptomatic. MRI has enabled recognition of many conditions that used to be missed by CT or myelography investigations performed for back and leg pain. However, even without additional compressive impingement (disc hernia, spondylolisthesis or lumbar canal stenosis) these anomalies can be responsible for sciatica, motor deficit and bladder sphincter dysfunction. Tarlov cysts are perinervous dilatations of the dorsal root ganglion. CT and especially MRI can reveal these cysts and their precise relations with the neighboring structures. Delayed filling of the cysts can be visualized on the myelogram. MRI is more sensitive than CT myelography for a positive diagnosis of nerve root anomalies, a differential diagnosis with disc hernia and classification of these anomalies. Surgical treatment is indicated for symptomatic Tarlov cysts and nerve root anomalies resistant to conservative treatment. Better outcome is observed in patients with an additional compressive impingement component. We report two cases of sciatica: one caused by Tarlov cysts diagnosed by MRI and the other by nerve root anomalies diagnosed by CT myelography. In both cases, conservative treatment was undertaken. The clinical, radiological and therapeutic aspects of these disorders are discussed. PMID:18809189
Younes, M; Korbaa, W; Zrour, S; Bejia, I; Touzi, M; Bergaoui, N
2009-03-01
4
PubMed
Intradiscal oxygen-ozone (O2-O3) chemonucleolysis is a well-known effective treatment for pain caused by protruding disc disease and nerve root compression due to bulging or herniated disc. The most widely used therapeutic combination is intradiscal injection of an O2-O3 mixture (chemonucleolysis), followed by periradicular injection of O2-O3, steroid and local anaesthetic to enhance the anti-inflammatory and analgesic effect. The treatment is designed to resolve pain and is administered to patients without motor weakness, whereas patients with acute paralysis caused by nerve root compression undergo surgery 24-48h after the onset of neurological deficit. This paper reports on the efficacy of O2-O3 chemonucleolysis associated with anti-inflammatory foraminal injection in 13 patients with low back pain and cruralgia, low back pain and sciatica and subacute partial motor weakness caused by nerve root compression unresponsive to medical treatment. All patients were managed in conjunction with our colleagues in the Neurosurgery Unit of Bellaria Hospital and the IRCCS Institute of Neurological Sciences, Bologna. The outcomes obtained are promising: 100% patients had a resolution of motor weakness, while 84.6% had complete pain relief. Our results demonstrate that O2-O3 therapy can be considered a valid treatment option for this category of patients. PMID:25363257
Dall'Olio, Massimo; Princiotta, Ciro; Cirillo, Luigi; Budai, Caterina; de Santis, Fabio; Bartolini, Stefano; Serchi, Elena; Leonardi, Marco
2014-10-31
5
PubMed
The depth and duration of snow pack is declining in the northeastern United States as a result of warming air temperatures. Since snow insulates soil, a decreased snow pack can increase the frequency of soil freezing, which has been shown to have important biogeochemical implications. One of the most notable effects of soil freezing is increased inorganic nitrogen losses from soil during the following growing season. Decreased nitrogen retention is thought to be due to reduced root uptake, but has not yet been measured directly. We conducted a 2-year snow-removal experiment at Hubbard Brook Experimental Forest in New Hampshire, USA to determine the effects of soil freezing on root uptake and leaching of inorganic nitrogen simultaneously. Snow removal significantly increased the depth of maximal soil frost by 37.2 and 39.5 cm in the first and second winters, respectively (P < 0.001 in 2008/2009 and 2009/2010). As a consequence of soil freezing, root uptake of ammonium declined significantly during the first and second growing seasons after snow removal (P = 0.023 for 2009 and P = 0.005 for 2010). These observed reductions in root nitrogen uptake coincided with significant increases in soil solution concentrations of ammonium in the Oa horizon (P = 0.001 for 2009 and 2010) and nitrate in the B horizon (P < 0.001 and P = 0.003 for 2009 and 2010, respectively). The excess flux of dissolved inorganic nitrogen from the Oa horizon that was attributable to soil freezing was 7.0 and 2.8 kg N ha(-1) in 2009 and 2010, respectively. The excess flux of dissolved inorganic nitrogen from the B horizon was lower, amounting to 1.7 and 0.7 kg N ha(-1) in 2009 and 2010, respectively. Results of this study provide direct evidence that soil freezing reduces root nitrogen uptake, demonstrating that the effects of winter climate change on root function has significant consequences for nitrogen retention and loss in forest ecosystems. PMID:24574104
Campbell, John L; Socci, Anne M; Templer, Pamela H
2014-08-01
6
PubMed Central
Background and Aims Phosphorus (P) is a major factor controlling cluster-root formation. Cluster-root proliferation tends to concentrate in organic matter (OM)-rich surface-soil layers, but the nature of this response of cluster-root formation to OM is not clear. Cluster-root proliferation in response to localized application of OM was characterized in Lupinus albus (white lupin) grown in stratified soil columns to test if the stimulating effect of OM on cluster-root formation was due to (a) P release from breakdown of OM; (b) a decrease in soil density; or (c) effects of micro-organisms other than releasing P from OM. Methods Lupin plants were grown in three-layer stratified soil columns where P was applied at 0 or 330 mg P kg?1 to create a P-deficient or P-sufficient background, and OM, phytate mixed with OM, or perlite was applied to the top or middle layers with or without sterilization. Key Results Non-sterile OM stimulated cluster-root proliferation and root length, and this effect became greater when phytate was supplied in the presence of OM. Both sterile OM and perlite significantly decreased cluster-root formation in the localized layers. The OM position did not change the proportion of total cluster roots to total roots in dry biomass among no-P treatments, but more cluster roots were concentrated in the OM layers with a decreased proportion in other places. Conclusions Localized application of non-sterile OM or phytate plus OM stimulated cluster-root proliferation of L. albus in the localized layers. This effect is predominantly accounted for by P release from breakdown of OM or phytate, but not due to a change in soil density associated with OM. No evidence was found for effects of micro-organisms in OM other than those responsible for P release. PMID:20150198
Li, Hai-Gang; Shen, Jian-Bo; Zhang, Fu-Suo; Lambers, Hans
2010-01-01
7
PubMed
Tris (8-hydroxyquinoline) aluminum (Alq3) is an organic semiconductor molecule, widely used as an electron transport layer, light emitting layer in organic light-emitting diodes and a host for fluorescent and phosphorescent dyes. In this work thin films of pure and silver (Ag), cupper (Cu), terbium (Tb) doped Alq3 nanoparticles were synthesized using the physical vapor condensation method. They were fabricated on glass substrates and characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectroscopy, atomic force microscope (AFM), UV-visible absorption spectra and studied for their photoluminescence (PL) properties. SEM and AFM results show spherical nanoparticles with size around 70-80 nm. These nanoparticles have almost equal sizes and a homogeneous size distribution. The maximum absorption of Alq3 nanoparticles is observed at 300 nm, while the surface plasmon resonant band of Ag doped sample appears at 450 nm. The PL emission spectra of Tb, Cu and Ag doped Alq3 nanoparticles show a single broad band at around 515 nm, which is similar to that of the pure one, but with enhanced PL intensity. The sample doped with Ag at a concentration ratio of Alq3:Ag = 1:0.8 is found to have the highest PL intensity, which is around 2 times stronger than that of the pure one. This enhancement could be attributed to the surface plasmon resonance of Ag ions that might have increased the absorption and then the quantum yield. These remarkable result suggest that Alq3 nanoparticles incorporated with Ag ions might be quite useful for future nano-optoelectronic devices. PMID:23653126
Salah, Numan; Habib, Sami S; Khan, Zishan H
2013-09-01
8
The melt quenching method is used to prepare erbium-doped silver nanoparticle (NP) embedded phosphate glass. The effect of annealing on the glass on the formation of silver NPs produced by the reduction of silver (Ag+ ?Ag°) is studied. The glass samples are characterized by x-ray diffraction, UV-vis-NIR absorption, photoluminescence spectroscopy and transmission electron microscopy (TEM) imaging. The absorption spectra reveal not only the peaks due to Er3+ ions, but also the surface plasmon resonance band of silver NPs located around ~442 nm. The TEM imaging shows the homogeneous distribution of silver NPs of almost spherical shape with an average diameter of ~5 nm. Upconversion luminescence spectra show two major emissions at 550 and 638 nm, originating from the 4S3/2 and 4F9/2 energy levels of the Er3+ ions, respectively. The enhancement in the luminescence intensity of both the green and red bands is found to be due to the effective local field of the silver NPs as well as the energy transfer from the nanoclusters, comprised of centers with silver ions bound to silver atoms in dimers or trimers to Er3+ ions, whereas quenching occurred due to the energy transfer from erbium ions to silver NPs (Er3+ ?Ag°).
Raja, J. Amjad; R. Sahar, M.; K. Ghoshal, S.; R. Dousti, M.; Riaz, S.; R. Samavati, A.; N. A Jamaludin, M.; Naseem, S.
2013-02-01
9
Summary. The effect of aluminum on hydrogen peroxide production and peroxidase-catalyzed NADH oxidation was studied in barley roots germinated and grown between two layers of moistened filter paper. Guaiacol peroxidase activity significantly increased after 48?h and was approximately two times higher after 72?h in Al-treated roots. The oxidation of NADH was also significantly increased and, like guaiacol peroxidase activity, it
M. šimonovi?ová; J. Huttová; I. Mistrík; B. široká; L. Tamás
2004-01-01
10
An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 A·m-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 g·m-2·h-1, respectively, in accelerated corrosion test for 8 h at 2000 A·m-2. The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.
Yang, Hai-tao; Liu, Huan-rong; Zhang, Yong-chun; Chen, Bu-ming; Guo, Zhong-cheng; Xu, Rui-dong
2013-10-01
11
PubMed
Dark septate endophytes (DSE) are very common root colonizers of woody plant species. Ascomycetes of the Phialocephala fortinii s.l.-Acephala applanata species complex (PAC) are the main representatives of DSE fungi in forest ecosystems. PAC and mycorrhizal fungi share the same habitat, but interactions among PAC, mycorrhizal fungi and plants are poorly understood. We compared the effects of single and dual inoculation of Norway spruce seedlings with PAC and the ectomycorrhizal (ECM) fungus Hebeloma crustuliniforme on host growth, degree of mycorrhization and density of endophytic PAC biomass. Single colonization by H.?crustuliniforme or PAC significantly reduced plant biomass. Dual colonization reduced or neutralized plant growth depression caused by single fungal colonization. The degree of mycorrhization was independent on PAC colonization, and mycorrhization significantly reduced endophytic PAC biomass. Plant biomass of dually colonized plants positively correlated with PAC biomass. These results demonstrate the ability of dual inoculation of PAC and H.?crustuliniforme to neutralize plant growth depression caused by single fungal inoculation. Our explanations of enhanced plant growth in dually inoculated plants are the inhibition of PAC during root colonization by the ECM mantle and ECM-mediated access to plant growth-promoting nutrients resulting from the mineralization of the potting medium by PAC. PMID:24249297
Reininger, Vanessa; Sieber, Thomas N
2013-12-01
12
PubMed
Cyanamide (CA) has been reported as a natural compound produced by hairy vetch (Vicia villosa Roth.) and it was shown also to be an allelochemical, responsible for strong allelopathic potential in this species. CA phytotoxicity has been demonstrated on various plant species, but to date little is known about its mode of action at cellular level. Treatment of tomato (Solanum lycopersicum L.) roots with CA (1.2 mM) resulted in inhibition of growth accompanied by alterations in cell division, and imbalance of plant hormone (ethylene and auxin) homeostasis. Moreover, the phytotoxic effect of CA was also manifested by modifications in expansin gene expression, especially in expansins responsible for cell wall remodeling after the cytokinesis (LeEXPA9, LeEXPA18). Based on these results the phytotoxic activity of CA on growth of roots of tomato seedlings is likely due to alterations associated with cell division. PMID:22847024
Soltys, Dorota; Rudzi?ska-Langwald, Anna; Gniazdowska, Agnieszka; Wi?niewska, Anita; Bogatek, Renata
2012-11-01
13
The WO3 loaded Ag-ZnO (WO3-Ag-ZnO) was successfully synthesized by precipitation-decomposition method. The catalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) images, energy dispersive spectrum (EDS), transmission electron microscope (TEM), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV) and BET surface area measurements. The photocatalytic activity of WO3-Ag-ZnO was investigated for the degradation of Naphthol Blue Black (NBB) in aqueous solution using solar light. WO3-Ag-ZnO is found to be more efficient than Ag-ZnO, WO3-ZnO, Ag-WO3, WO3, commercial ZnO, bare ZnO, TiO2-P25 and TiO2 (Merck) at pH 9 for the mineralization of NBB dye. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of NBB dye have been analyzed. The mineralization of NBB has been confirmed by Chemical Oxygen Demand (COD) measurements. A degradation mechanism is proposed for the degradation of NBB under solar light. This catalyst is found to be reusable.
Subash, B.; Krishnakumar, B.; Sreedhar, B.; Swaminathan, M.; Shanthi, M.
2013-02-01
14
Electroluminescence (EL) and electron emission into vacuum (EM) occur when a non-destructive dielectric breakdown of Al-Al2O3-Ag diodes, electroforming, results in the development of a filamentary region in which current-voltage (I-V) characteristics exhibit voltage-controlled negative resistance. The temperature dependence of I-V curves, EM, and, particularly, EL of Al-Al2O3-Ag diodes with anodic Al2O3 thicknesses between 12 nm and 30 nm, has been studied. Two filters, a long-pass (LP) filter with transmission of photons with energies less than 3.0 eV and a short-pass (SP) filter with photon transmission between 3.0 and 4.0 eV, have been used to characterize EL. The voltage threshold for EL with the LP filter, VLP, is ˜1.5 V. VLP is nearly independent of Al2O3 thickness and of temperature and is 0.3-0.6 V less than the threshold voltage for EL for the SP filter, VSP. EL intensity is primarily between 1.8 and 3.0 eV when the bias voltage, VS ? 7 V. EL in the thinnest diodes is enhanced compared to EL in thicker diodes. For increasing VS, for diodes with the smallest Al2O3 thicknesses, there is a maximum EL intensity, LMX, at a voltage, VLMX, followed by a decrease to a plateau. LMX and EL intensity at 4.0 V in the plateau region depend exponentially on Al2O3 thickness. The ratio of LMX at 295 K for a diode with 12 nm of Al2O3 to LMX for a diode with 25 nm of Al2O3 is ˜140. The ratio of EL intensity with the LP filter to EL intensity with the SP filter, LP/SP, varies between ˜3 and ˜35; it depends on Al2O3 thickness and VS. Enhanced EL is attributed to the increase of the spontaneous emission rate of a dipole in a non-resonant optical microcavity. EL photons interact with the Ag and Al films to create surface plasmon polaritons (SPPs) at the metal-Al2O3 interfaces. SPPs generate large electromagnetic fields in the filamentary region of the electroformed Al-Al2O3-Ag diode, which then acts as an optical microcavity. A model is proposed for electronic processes in electroformed Al-Al2O3-Ag diodes.
Hickmott, T. W.
2013-12-01
15
Er3+:Ag-antimony glass nanocomposites are synthesized in a new reducing glass (dielectric) matrix K2O-B2O3-Sb2O3 by a single-step melt-quench technique involving selective thermochemical reduction. The UV-vis-near-infrared absorption spectra show typical surface plasmon resonance (SPR) band of Ag0 nanoparticles (NPs) in addition to the distinctive absorption peaks of Er3+ ion. X-ray diffraction and selected area electron diffraction results indicate formation of Ag0 NPs
Tirtha Som; Basudeb Karmakar
2009-01-01
16
PubMed
Objective To construct an autophagy-targeted vaccine harboring the genes encoding Ag85B and microtubule-associated protein light chain-3 (LC3) and to explore its immunoprotection against Mycobacterium tuberculosis (MTB). Methods The pCMV-LC3-Ag85B plasmid was constructed and used to transfect RAW264.7 cells. The level of LC3-Ag85B was detected using Western blotting. Then, BALB/c mice were immunized with pCMV, pCMV-Ag85B and pCMV-LC3-Ag85B plasmid, respectively. In vitro, two weeks after the last immunization, the secretion of IL-2, IFN-?, IL-4 and IL-10 from Ag85B-stimulated lymphocytes was measured by ELISA. Three months after the last immunization, all mice were challenged with MTB H37Rv via the tail vein and the bacterial loads in their spleens and lungs were determined by colony formation assay. Results The LC3-Ag85B fusion protein was expressed in RAW264.7 cells that had been transfected with pCMV-LC3-Ag85B and the expression level was in a dose-dependent manner. Compared with the pCMV-Ag85B treatment group, pCMV-LC3-Ag85B-immunized mice showed a significant increase of IL-2 and IFN-? levels and the lower loads of MTB in the spleens and lungs. Conclusion pCMV-LC3-Ag85B can enhance a specific Th1-predominant immunity and a superior immunoprotection against MTB, which may provide a new practical strategy for the development of improved vaccines against MTB. PMID:25374074
Hu, Dong; Yang, Xiaokang; Wang, Wan; Xing, Yingru; Wang, Wenyang; DU, Zhaohong; Yiu, Qi; Zhang, Li; Chen, Liping; Wu, Jing; Zhang, Rongbo
2014-11-01
17
We examine electromigration fatigue reliability and morphological patterns of Sn–37Pb and Sn–3Ag–1.5Cu\\/Sn–3Ag–0.5Cu composite solder bumps in a flip–chip package assembly with Ti\\/Ni(V)\\/Cu UBM. The flip–chip test vehicle was subjected to test conditions of five combinations of applied electric currents and ambient temperatures, namely, 0.4A\\/150°C, 0.5A\\/150°C, 0.6A\\/125°C, 0.6A\\/135°C, and 0.6A\\/150°C. The electrothermal coupling analysis was employed to investigate the current crowding
Yi-Shao Lai; Kuo-Ming Chen; Chin-Li Kao; Chiu-Wen Lee; Ying-Ta Chiu
2007-01-01
18
Arsenic (As) toxicity and its biochemical effects have been mostly evaluated in ferns and a few higher plants. In this study,\\u000a we investigated the effect of As (10.0 and 50.0 ?M) on seedling growth, root anatomy, lipid peroxidation (malondialdehyde\\u000a and conjugated dienes), electrolyte leakage, H2O2 content, root oxidizability and the activities of antioxidant enzymes in mung bean (Phaseolus aureus Roxb.). Arsenic
Harminder Pal Singh; Daizy R. Batish; Ravinder Kumar Kohli; Komal Arora
2007-01-01
19
E-print Network
diagram in the coverage-temperature plane for surface superstructures induced by additional Ag adsorption onto the Si 111 - 3 3-Ag surface at low temperatures is determined; a 21 21 phase below 250 K and a 6 6 Ag atoms are deposited onto the respective surfaces at room temperature RT , they are known to grow
Hasegawa, Shuji
20
A number of double pancake coils have been wound in order to test the winding procedure and tape performance for the development of a 4 T, 50 mm inner bore diameter, Bi(2 2 2 3)/AgMg magnet operating at liquid Ne temperature. Much attention has been paid in testing different winding designs in order to reduce the performance degradation due to tape handling. All the double pancake coil samples have been tested in different field and temperature conditions. The experimental data have been used to estimate critical current degradation and the quality index n at simulated working conditions. Internal temperature distribution of the magnet, at operating current, has been calculated by means of a FEM simulation.
Ariante, M.; Cavaliere, V.; Masullo, G.; Matrone, A.; Santoro, A.; Ferdeghini, C.; Grasso, G.; Siri, A. S.; Bigoni, L.; Curcio, F.; Martini, L.
2002-08-01
21
PubMed
Activator of G-protein signaling 3 (AGS3, gene name G-protein signaling modulator-1, Gpsm1), an accessory protein for G-protein signaling, has functional roles in the kidney and CNS. Here we show that AGS3 is expressed in spleen, thymus, and bone marrow-derived dendritic cells, and is up-regulated upon leukocyte activation. We explored the role of AGS3 in immune cell function by characterizing chemokine receptor signaling in leukocytes from mice lacking AGS3. No obvious differences in lymphocyte subsets were observed. Interestingly, however, AGS3-null B and T lymphocytes and bone marrow-derived dendritic cells exhibited significant chemotactic defects as well as reductions in chemokine-stimulated calcium mobilization and altered ERK and Akt activation. These studies indicate a role for AGS3 in the regulation of G-protein signaling in the immune system, providing unexpected venues for the potential development of therapeutic agents that modulate immune function by targeting these regulatory mechanisms. PMID:24573680
Branham-O'Connor, Melissa; Robichaux, William G; Zhang, Xian-Kui; Cho, Hyeseon; Kehrl, John H; Lanier, Stephen M; Blumer, Joe B
2014-04-11
22
E-print Network
alloy and its apatite-inducing abilities Le-gan HOU1 , Li LI2 , Yu-feng ZHENG1,2 1. Center milling time (1, 2, 5 and 10 h) and sintered into porous Ti-3Ag alloys. The samples were treated treated porous Ti-3Ag alloys prepared by the powders ball milled for 10 h possess the best apatite
Zheng, Yufeng
23
The relationships between plant organs and root hydrological traits are not well known and the question arises whether elevated\\u000a CO2 changes these relationships. This study attempted to answer this question. A pseudo-replicated experiment was conducted with\\u000a two times 24 American elm (Ulmus americana L.) and 23 and 24 red oak (Quercus rubra L.) seedlings growing in ambient CO2 (around 360
Song Cheng
2009-01-01
24
PubMed
The compounds Ba3FeUS6 and Ba3AgUS6 have been synthesized by the reactions of BaS, U, S, and M (= Fe or Ag) at 1223 K. These two isostructural compounds crystallize in the K4CdCl6 structure type in the trigonal system in space group D3d(6)–R3c. Both structures feature infinite ?(1)[MUS6(6–)] chains along c that are separated by Ba atoms. The ?(1)[FeUS6(6–)] chains are formed by the face-sharing of US6 trigonal prisms with FeS6 octahedra; in contrast, the ?(1)[AgUS6(6–)] chains are formed by the face-sharing of US6 octahedra with AgS6 trigonal prisms. The Ba3FeUS6 compound charge balances with 3 Ba(2+), 1 Fe(2+), 1 U4+, and 6 S(2–), whereas Ba3AgUS6 charge balances with 3 Ba(2+), 1 Ag(1+), 1 U(5+), and 6 S(2–). This structure offers a remarkable flexibility in terms of the oxidation state of the incorporated uranium depending on the oxidation state of the d-block metal. DFT calculations performed with the HSE functional have led to band gaps of 2.3 and 2.2 eV for Ba3FeUS6 and Ba3AgUS6, respectively. From resistivity measurements, the Arrhenius activation energies are 0.12(1) and 0.43(1) eV for Ba3FeUS6 and Ba3AgUS6, respectively. PMID:24564267
Mesbah, Adel; Malliakas, Christos D; Lebègue, Sébastien; Sarjeant, Amy A; Stojko, Wojciech; Koscielski, Lukasz A; Ibers, James A
2014-03-17
25
This document is part of Subvolume A Substances Containing Ag … C10H15' of Volume 48 Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III Condensed Matter'. It contains an extract of Section 3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for Ag3AsS3 [Ag3(AsS3)] (Subst. No. 0013)
Chihara, H.; Nakamura, N.
26
Root networks contribute to slope stability through complicated interactions that include mechanical compression and tension. Due to the spatial heterogeneity of root distribution and the dynamic of root turnover, the quantification of root reinforcement on steep slope is challenging and consequently the calculation of slope stability as well. Although the considerable advances in root reinforcement modeling, some important aspect remain neglected. In this study we address in particular to the role of root strength variability on the mechanical behaviors of a root bundle. Many factors may contribute to the variability of root mechanical properties even considering a single class of diameter. This work presents a new approach for quantifying root reinforcement that considers the variability of mechanical properties of each root diameter class. Using the data of laboratory tensile tests and field pullout tests, we calibrate the parameters of the Weibull survival function to implement the variability of root strength in a numerical model for the calculation of root reinforcement (RBMw). The results show that, for both laboratory and field datasets, the parameters of the Weibull distribution may be considered constant with the exponent equal to 2 and the normalized failure displacement equal to 1. Moreover, the results show that the variability of root strength in each root diameter class has a major influence on the behavior of a root bundle with important implications when considering different approaches in slope stability calculation. Sensitivity analysis shows that the calibration of the tensile force and the elasticity of the roots are the most important equations, as well as the root distribution. The new model allows the characterization of root reinforcement in terms of maximum pullout force, stiffness, and energy. Moreover, it simplifies the implementation of root reinforcement in slope stability models. The realistic quantification of root reinforcement for tensile, shear and compression behavior allows the consideration of the stabilization effects of root networks on steep slopes and the influence that this has on the triggering of shallow landslides.
Schwarz, M.; Giadrossich, F.; Cohen, D.
2013-03-01
27
Root-soil mechanical interactions play an important role in strength and force redistribution in rooted soil. Recent advances in root reinforcement modeling implement detailed representation of root geometry and mechanical properties as well as root-soil mechanical interactions. Nevertheless, root-soil mechanical interactions are often considered at the single root scale ignoring interactions between neighboring roots and root bundles known to play important role in similar applications such as engineered composite material reinforcement. The objective was to quantify mechanical interactions among neighboring roots or roots network using pullout laboratory experiments and modeling. We focus on the on effects of such interactions on global pull out force of a bundle of roots via better understanding of transmission of radial stresses to soil matrix due to the friction at the interface soil-root. Additionally, we wish to predict how cumulative friction changes along a single root axis with and without branching points during the slipping out. Analytical models of fiber reinforced materials show the magnitude of bonded friction depends on three key parameters: bond modulus, maximal bond strength and difference between the Young moduli of fiber and Young moduli of matrix. Debonded friction is calculated assuming failure follows Coulomb failure that includes apparent cohesion, effective normal stress and residual root soil friction angle. We used a pullout device to measure displacement and force of individual roots and for the bundle of roots. Additionally, we monitored and detected activation of root-soil friction by six acoustic emission sensors placed on waveguide in contact with the soil matrix. Results from experiments with parallel and crossing roots demonstrated the importance of considering factors such as distance of root axis, branching points, crossing of roots and roots diameter for the behavior of bundle of roots and inclined roots during pullout. Acoustic emission measurements provided interesting insights into progressive activation of root-soil friction. These results enhance understanding of root reinforcement mechanism and enable more realistic implementation of root reinforcement modeling for stability calculation of vegetated slopes.
Giadrossich, Filippo; Schwarz, Massimiliano; Preti, Federico; Or, Dani
2010-05-01
28
SciTech Connect
Electroluminescence (EL) and electron emission into vacuum (EM) occur when a non-destructive dielectric breakdown of Al-Al{sub 2}O{sub 3}-Ag diodes, electroforming, results in the development of a filamentary region in which current-voltage (I-V) characteristics exhibit voltage-controlled negative resistance. The temperature dependence of I-V curves, EM, and, particularly, EL of Al-Al{sub 2}O{sub 3}-Ag diodes with anodic Al{sub 2}O{sub 3} thicknesses between 12?nm and 30?nm, has been studied. Two filters, a long-pass (LP) filter with transmission of photons with energies less than 3.0?eV and a short-pass (SP) filter with photon transmission between 3.0 and 4.0?eV, have been used to characterize EL. The voltage threshold for EL with the LP filter, V{sub LP}, is ?1.5?V. V{sub LP} is nearly independent of Al{sub 2}O{sub 3} thickness and of temperature and is 0.3–0.6?V less than the threshold voltage for EL for the SP filter, V{sub SP}. EL intensity is primarily between 1.8 and 3.0?eV when the bias voltage, V{sub S} ? 7?V. EL in the thinnest diodes is enhanced compared to EL in thicker diodes. For increasing V{sub S}, for diodes with the smallest Al{sub 2}O{sub 3} thicknesses, there is a maximum EL intensity, L{sub MX}, at a voltage, V{sub LMX}, followed by a decrease to a plateau. L{sub MX} and EL intensity at 4.0?V in the plateau region depend exponentially on Al{sub 2}O{sub 3} thickness. The ratio of L{sub MX} at 295?K for a diode with 12?nm of Al{sub 2}O{sub 3} to L{sub MX} for a diode with 25?nm of Al{sub 2}O{sub 3} is ?140. The ratio of EL intensity with the LP filter to EL intensity with the SP filter, LP/SP, varies between ?3 and ?35; it depends on Al{sub 2}O{sub 3} thickness and V{sub S}. Enhanced EL is attributed to the increase of the spontaneous emission rate of a dipole in a non-resonant optical microcavity. EL photons interact with the Ag and Al films to create surface plasmon polaritons (SPPs) at the metal-Al{sub 2}O{sub 3} interfaces. SPPs generate large electromagnetic fields in the filamentary region of the electroformed Al-Al{sub 2}O{sub 3}-Ag diode, which then acts as an optical microcavity. A model is proposed for electronic processes in electroformed Al-Al{sub 2}O{sub 3}-Ag diodes.
Hickmott, T. W. [Department of Physics, State University of New York at Albany, Albany, New York 12222 (United States)
2013-12-21
29
PubMed
Roots hairs are cylindrical extensions of root epidermal cells that are important for acquisition of nutrients, microbe interactions, and plant anchorage. The molecular mechanisms involved in the specification, differentiation, and physiology of root hairs in Arabidopsis are reviewed here. Root hair specification in Arabidopsis is determined by position-dependent signaling and molecular feedback loops causing differential accumulation of a WD-bHLH-Myb transcriptional complex. The initiation of root hairs is dependent on the RHD6 bHLH gene family and auxin to define the site of outgrowth. Root hair elongation relies on polarized cell expansion at the growing tip, which involves multiple integrated processes including cell secretion, endomembrane trafficking, cytoskeletal organization, and cell wall modifications. The study of root hair biology in Arabidopsis has provided a model cell type for insights into many aspects of plant development and cell biology. PMID:24982600
Grierson, Claire; Nielsen, Erik; Ketelaarc, Tijs; Schiefelbein, John
2014-01-01
30
The effect of Pd(P) thickness on the solid-solid reaction between Sn-3Ag-0.5Cu and Au/Pd(P)/Ni(P) at 180°C was investigated in this study. The reaction was conducted after reflow, thereby removing the Au/Pd finish before the solid-state reaction. The reaction products included (Cu,Ni)6Sn5, Ni2SnP, and Ni3P, and their growth strongly depended on the Pd(P) thickness, especially for the former phases [i.e., (Cu,Ni)6Sn5 and Ni2SnP]. As the Pd(P) thickness increased from 0 ?m, to 0.1 ?m, to 0.22 ?m, the (Cu,Ni)6Sn5 exhibited a needle-like dense layer, chunk-like morphology, and discontinuous morphology, respectively. The alternative phase (Ni2SnP) behaved in a manner opposite to that of (Cu,Ni)6Sn5, growing with a discontinuous morphology to a dense layer with increasing Pd(P) thickness. However, this strong dependence disappeared when the solder joints were subsequently subjected to solid-state aging. The (Cu,Ni)6Sn5 and Ni2SnP both became layered structures for all cases examined. A high-speed ball shear (HSBS) test was conducted to quantify the mechanical response of the interfacial microstructures. The HSBS test results showed that any initial difference in shear strength caused by the various Pd(P) thicknesses could be reduced after the solid-state aging, which is consistent with the microstructural evolution observed. The mechanical strength of the solder joints was decreased due to the presence of a bi-intermetallic structure of (Cu,Ni)6Sn5/Ni2SnP at the interface. Detailed analysis of the growth of (Cu,Ni)6Sn5 and Ni2SnP is also provided.
Ho, C. E.; Wu, W. H.; Hsu, L. H.; Lin, C. S.
2012-01-01
31
PubMed
Geothermal water is a clean, cheap and renewable resource and it is widely distributed all over the world. In this work, ternary Ag2CO3/Ag/AgCl photocatalyst has been successfully synthesized via a one-pot precipitation method in natural geothermal water at room temperature, wherein the geothermal water serves as the source of chlorine and carbonate. The results suggest that the Ag/AgCl nanoparticles are anchored on the surface of Ag2CO3 and Ag2CO3/Ag/AgCl composite shows strong absorption ability in the visible light region. The evaluation of the photocatalytic activity indicates that the as-synthesized Ag2CO3/Ag/AgCl photocatalyst exhibits higher photocatalytic performance for the degradation of methylene blue (MB) aqueous solution under visible light irradiation than one-component (Ag2CO3), two-component (Ag/AgCl, Ag2CO3/AgCl) and the mechanical mixture of Ag2CO3 and Ag/AgCl. The trapping experiments confirmed that holes (h(+)) and (•)O2(-) were the two main active species in the photocatalytic process. Finally, a possible Z-scheme photocatalytic mechanism of the charge transfer was proposed for the enhanced photocatalytic performance. This work may open up new insights into the application of cheap geothermal water resources in the word and provide new opportunities for facile fabrication of Ag/AgCl-based photocatalysts. PMID:25164388
Yao, Xiaxi; Liu, Xiaoheng
2014-09-15
32
SciTech Connect
Thin PdAg alloy membranes with 20–25% Ag are being developed for hydrogen separation technology. Despite many investigations on such membranes as well as representative experimental and theoretical model systems, unresolved issues remain concerning the effect of the alloy surface structure and composition on adsorption and vice versa. Therefore, the interaction between hydrogen, carbon monoxide or oxygen with the surface of a PdAg model alloy was studied using periodic self-consistent density functional theory (DFT-GGA) calculations. In particular, the adsorption structure, coverage dependence and possible adsorption-induced segregation phenomena were addressed using Pd3Ag(1 1 1) model surfaces with varying degrees of surface segregation. In agreement with previous experimental and theoretical investigations, we predict Ag surface termination to be energetically favorable in vacuum. The segregation of Ag is then reversed upon adsorption of H, CO or O. For these adsorbates, the binding is strongest on Pd three-fold hollow sites, and hence complete Pd termination is favored at high coverage of H or CO, while 25% Ag may remain under oxygen because of the lower O-saturation coverage. CO adsorption provides a somewhat stronger driving force for Pd segregation when compared to H, and this may have implications with respect to permeation properties of PdAg alloy surfaces. Our predictions for high coverage are particularly relevant in underlining the importance of segregation phenomena to the hydrogen transport properties of thin PdAg alloy membranes.
Svenum, I. H.; Herron, Jeffrey A.; Mavrikakis, Manos; Venvik, H. J.
2012-10-15
33
Nd3Cu4Sn4, Nd3Ag4Sn4, and Ho3Cu4Sn4 have been studied using S119n Mössbauer spectroscopy. Contrary to recent neutron diffraction data, Nd3Cu4Sn4 shows a clear magnetic signal at 1.6 K and has an ordering temperature of 2.0(1) K. Nd3Ag4Sn4 orders at 4.8(1) K, in agreement with neutron diffraction measurements. We observe the ordering of the Ho 2d sublattice in Ho3Cu4Sn4 at 8.2(1) K but we also see some residual magnetic splitting up to 10.5(2) K, which was not previously detected by neutron scattering.
Voyer, C. J.; Ryan, D. H.; Cadogan, J. M.
2009-04-01
34
We analyzed depth distribution of composition and growth modes during Ga deposition on Si(111)-2?3 × 2?3-Sn and ?3 × ?3-Ag structures at room temperature. Applying RHEED-TRAXS (total reflection angle X-ray spectroscopy), the dependence of the X-ray (GaK, SnL, AgL, and SiK) emission on the glancing angle of the electron beam was measured. When 1 ML of Ga was deposited on the 2?3 × 2?3-Sn structure, the mixing of Ga and Sn atoms was clearly observed, and a quasi-?3 × ?3-(Sn,Ga) structure was formed. After further Ga deposition, a liquid-like film of Ga?Sn alloy was formed. When 1 ML of Ga was deposited on the ?3 × ?3-Ag surface, the structure was destroyed and a Ga layer was formed on the Si(111) surface, and Ag atoms which dissociated from the ?3 × ?3-Ag structure formed particles on the underlying Ga layer. For further deposition, a liquid-like Ga film grew, and Ag particles were buried in the Ga film without being destroyed. This alloying and separation of metals in atomic scale is discussed referring to the bulk phase diagrams of binary alloys.
Yamanaka, Toshiro; Ino, Shozo
1995-06-01
35
NASA Technical Reports Server (NTRS)
When a plant root is reoriented within the gravity field, it responds by initiating a curvature which eventually results in vertical growth. Gravity sensing occurs primarily in the root tip. It may involve amyloplast sedimentation in the columella cells of the root cap, or the detection of forces exerted by the mass of the protoplast on opposite sides of its cell wall. Gravisensing activates a signal transduction cascade which results in the asymmetric redistribution of auxin and apoplastic Ca2+ across the root tip, with accumulation at the bottom side. The resulting lateral asymmetry in Ca2+ and auxin concentration is probably transmitted to the elongation zone where differential cellular elongation occurs until the tip resumes vertical growth. The Cholodny-Went theory proposes that gravity-induced auxin redistribution across a gravistimulated plant organ is responsible for the gravitropic response. However, recent data indicate that the gravity-induced reorientation is more complex, involving both auxin gradient-dependent and auxin gradient-independent events.
Masson, P. H.
1995-01-01
36
ERIC Educational Resources Information Center
Discusses graviperception and gravitropism by plant roots. Indicates that graviperception occurs via sedimentation of amyloplasts in columella cells of the root cap and that the minimal graviresponsiveness of lateral roots may be due to the intensity of their caps to establish a concentration gradient of inhibitor(s) sufficient to affect…
Moore, Randy
1984-01-01
37
Root networks contribute to slope stability through complex interactions with soil that include mechanical compression and tension. Due to the spatial heterogeneity of root distribution and the dynamics of root turnover, the quantification of root reinforcement on steep slopes is challenging and consequently the calculation of slope stability also. Although considerable progress has been made, some important aspects of root mechanics remain neglected. In this study we address specifically the role of root-strength variability on the mechanical behavior of a root bundle. Many factors contribute to the variability of root mechanical properties even within a single class of diameter. This work presents a new approach for quantifying root reinforcement that considers the variability of mechanical properties of each root diameter class. Using the data of laboratory tensile tests and field pullout tests, we calibrate the parameters of the Weibull survival function to implement the variability of root strength in a numerical model for the calculation of root reinforcement (RBMw). The results show that, for both laboratory and field data sets, the parameters of the Weibull distribution may be considered constant with the exponent equal to 2 and the normalized failure displacement equal to 1. Moreover, the results show that the variability of root strength in each root diameter class has a major influence on the behavior of a root bundle with important implications when considering different approaches in slope stability calculation. Sensitivity analysis shows that the calibration of the equations of the tensile force, the elasticity of the roots, and the root distribution are the most important steps. The new model allows the characterization of root reinforcement in terms of maximum pullout force, stiffness, and energy. Moreover, it simplifies the implementation of root reinforcement in slope stability models. The realistic quantification of root reinforcement for tensile, shear and compression behavior allows for the consideration of the stabilization effects of root networks on steep slopes and the influence that this has on the triggering of shallow landslides.
Schwarz, M.; Giadrossich, F.; Cohen, D.
2013-11-01
38
PubMed
Novel conjugated G-quadruplex-forming d(TG3AG) oligonucleotides, linked to hydrophobic groups through phosphodiester bonds at 5'-end, have been synthesized as potential anti-HIV aptamers, via a fully automated, online phosphoramidite-based solid-phase strategy. Conjugated quadruplexes showed pronounced anti-HIV activity with some preference for HIV-1, with inhibitory activity invariably in the low micromolar range. The CD and DSC monitored thermal denaturation studies on the resulting quadruplexes, indicated the insertion of lipophilic residue at the 5'-end, conferring always improved stability to the quadruplex complex (203AG) quadruplexes plays an important role in the thermodynamic stabilization but a minor influence on the anti-HIV activity. Moreover, a detailed CD and DSC analyses indicate a monophasic behaviour for sequences I and V, while for ODNs (II-IV) clearly show that these quadruplex structures deviate from simple two-state melting, supporting the hypothesis that intermediate states along the dissociation pathway may exist. PMID:24433967
Romanucci, Valeria; Milardi, Danilo; Campagna, Tiziana; Gaglione, Maria; Messere, Anna; D'Urso, Alessandro; Crisafi, Emanuela; La Rosa, Carmelo; Zarrelli, Armando; Balzarini, Jan; Di Fabio, Giovanni
2014-02-01
39
Root research has been hampered by a lack of good methods and by the amount of time involved in making measurements. In general the studies from root system are made with either monolith or minirhizotron method which is used as a quantitative tool but requires comparison with conventional destructive methods. This work aimed to analyze roots systems images, obtained from a root atlas book, to different crops in order to find the root length and root length density and correlate them with the literature. Five crops images from Zea mays, Secale cereale, Triticum aestivum, Medicago sativa and Panicum miliaceum were divided in horizontal and vertical layers. Root length distribution was analyzed for horizontal as well as vertical layers. In order to obtain the root length density, a cuboidal volume was supposed to correspond to each part of the image. The results from regression analyses showed root length distributions according to horizontal or vertical layers. It was possible to find the root length distribution for single horizontal layers as a function of vertical layers, and also for single vertical layers as a function of horizontal layers. Regression analysis showed good fits when the root length distributions were grouped in horizontal layers according to the distance from the root center. When root length distributions were grouped according to soil horizons the fits worsened. The resulting root length density estimates were lower than those commonly found in literature, possibly due to (1) the fact that the crop images resulted from single plant situations, while the analyzed field experiments had more than one plant; (2) root overlapping may occur in the field; (3) root experiments, both in the field and image analyses as performed here, are subject to sampling errors; (4) the (hand drawn) images used in this study may have omitted some of the smallest roots.
Casaroli, D.; Jong van Lier, Q.; Metselaar, K.
2009-04-01
40
SciTech Connect
We have demonstrated electronic structure and magnetic properties of Cu{sub 3}, Ag{sub 3} and Au{sub 3} trimers using a full potential local orbital method in the framework of relativistic density functional theory. We have also shown that the non-relativistic generalized gradient approximation for the exchange-correlation energy functional gives reliable magnetic properties in coinage metal trimers compared to experiment. In addition we have indicated that the spin-orbit coupling changes the structure and magnetic properties of gold trimer while the structure and magnetic properties of copper and silver trimers are marginally affected. A significant orbital moment of 0.21?{sub B} was found for most stable geometry of the gold trimer whereas orbital magnetism is almost quenched in the copper and silver trimers.
Afshar, Mahdi [Department of Physics, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)] [Department of Physics, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Sargolzaei, Mohsen [Department of Chemistry, Shahrood University of Technology, Shahrood (Iran, Islamic Republic of)] [Department of Chemistry, Shahrood University of Technology, Shahrood (Iran, Islamic Republic of)
2013-11-15
41
Time-resolved pump-probe stimulated-emission and transient-absorption spectra were recorded after excitation with ˜30 fs pulses to the 1Bu+(0) and optically-forbidden diabatic levels of carotenoids, neurosporene, spheroidene and lycopene having n = 9-11 double bonds, bound to LH2 antenna complexes from Rhodobacter sphaeroides G1C, 2.4.1 and Rhodospirillum molischianum. The low-energy shift of stimulated emission from the covalent 1Bu-(0) and 3Ag-(0) levels slightly larger than that from the ionic 1Bu+(0) state suggests the polarization, whereas more efficient triplet generation suggests the twisting of the conjugated chain in Cars bound to the LH2 complexes, when compared to Cars free in solution.
Christiana, Rebecca; Miki, Takeshi; Kakitani, Yoshinori; Aoyagi, Shiho; Koyama, Yasushi; Limantara, Leenawaty
2009-10-01
42
NSDL National Science Digital Library
In this outdoor activity, learners discover that plants aren't just shoots (stem, branches, leaves, and flowers) growing above ground, but contain plenty of roots growing undergroundâmore than half the mass of a plant can be its roots. Learners dig up "mystery" plants to investigate their root structures, and match them to different types of root systems. Learners also learn about animals found near plant roots and how humans use roots.
Science, Lawrence H.
2008-01-01
43
MoO3/Ag/MoO3 (MAM) multilayer structures (layers thickness 20 nm/10 nm/35 nm) are used as anode in CuPc/C60/Alq3/Al organic photovoltaic cells. The averaged transmittance (400 nm-800 nm) of these MoO3/Ag/MoO3 multilayer structures is 70% ± 2% and their sheet resistance is 3.5 ± 1.0 ?/sq. When these multilayer structures are used as anode, the power conversion efficiency of the MoO3/Ag/MoO3/CuPc/C60/Alq3/Al cells is around 1%, this efficiency is increased of 50% when a thin CuI film (3 nm) is introduced at the interface between the anode and the organic film. This improvement is attributed to the templating effect of CuI on the CuPc molecules.
Makha, M.; Cattin, L.; Lare, Y.; Barkat, L.; Morsli, M.; Addou, M.; Khelil, A.; Bernède, J. C.
2012-12-01
44
PubMed
Arabidopsis roots grown on inclined agarose gels exhibit a sinusoidal growth pattern known as root waving. While root waving has been attributed to both intrinsic factors (e.g. circumnutation) and growth responses to external signals such as gravity, the potential for physical interactions between the root and its substrate to influence the development of this complex phenotype has been generally ignored. Using a rotating stage microscope and time-lapse digital imaging, we show that (1) root tip mobility is impeded by the gel surface, (2) this impedance causes root tip deflections by amplifying curvature in the elongation zone in a way that is distinctly nontropic, and (3) root tip impedance is augmented by normal gravitropic pressure applied by the root tip against the gel surface. Thus, both lateral corrective bending near the root apex and root tip impedance could be due to different vector components of the same graviresponse. Furthermore, we speculate that coupling between root twisting and bending is a mechanical effect resulting from root tip impedance. PMID:15247406
Thompson, Matthew V; Holbrook, N Michele
2004-07-01
45
PubMed
We report a new semitransparent inverted polymer solar cell (PSC) with a structure of glass/FTO/nc-TiO2/P3HT:PCBM/MoO3/Ag/MoO3. Because high-temperature annealing which decreased the conductivity of indium tin oxide (ITO) must be handled in the process of preparation of nanocrystalline titanium oxide (nc-TiO2), we replace glass/ITO with a glass/fluorine-doped tin oxide (FTO) substrate to improve the device performance. The experimental results show that the replacing FTO substrate enhances light transmittance between 400 and 600 nm and does not change sheet resistance after annealing treatment. The dependence of device performances on resistivity, light transmittance, and thickness of the MoO3/Ag/MoO3 film was investigated. High power conversion efficiency (PCE) was achieved for FTO substrate inverted PSCs, which showed about 75% increase compared to our previously reported ITO substrate device at different thicknesses of the MoO3/Ag/MoO3 transparent electrode films illuminated from the FTO side (bottom side) and about 150% increase illuminated from the MoO3/Ag/MoO3 side (top side). PMID:25332693
Li, Fumin; Chen, Chong; Tan, Furui; Li, Chunxi; Yue, Gentian; Shen, Liang; Zhang, Weifeng
2014-01-01
46
PubMed Central
We report a new semitransparent inverted polymer solar cell (PSC) with a structure of glass/FTO/nc-TiO2/P3HT:PCBM/MoO3/Ag/MoO3. Because high-temperature annealing which decreased the conductivity of indium tin oxide (ITO) must be handled in the process of preparation of nanocrystalline titanium oxide (nc-TiO2), we replace glass/ITO with a glass/fluorine-doped tin oxide (FTO) substrate to improve the device performance. The experimental results show that the replacing FTO substrate enhances light transmittance between 400 and 600 nm and does not change sheet resistance after annealing treatment. The dependence of device performances on resistivity, light transmittance, and thickness of the MoO3/Ag/MoO3 film was investigated. High power conversion efficiency (PCE) was achieved for FTO substrate inverted PSCs, which showed about 75% increase compared to our previously reported ITO substrate device at different thicknesses of the MoO3/Ag/MoO3 transparent electrode films illuminated from the FTO side (bottom side) and about 150% increase illuminated from the MoO3/Ag/MoO3 side (top side). PMID:25332693
2014-01-01
47
PubMed
A tree's root system accounts for between 10 and 65% of its total biomass, yet our understanding of the factors that cause this proportion to vary is limited because of the difficulty encountered when studying tree root systems. There is a need to develop new sampling and measuring techniques for tree root systems. Ground penetrating radar (GPR) offers the potential for direct nondestructive measurements of tree root biomass and root distributions to be made. We tested the ability of GPR, with 500 MHz, 800 MHz and 1 GHz antennas, to detect tree roots and determine root size by burying roots in a 32 m3 pit containing damp sand. Within this test bed, tree roots were buried in two configurations: (1) roots of various diameters (1-10 cm) were buried at a single depth (50 cm); and (2) roots of similar diameter (about 5 cm) were buried at various depths (15-155 cm). Radar antennas were drawn along transects perpendicular to the buried roots. Radar profile normalization, filtration and migration were undertaken based on standard algorithms. All antennas produced characteristic reflection hyperbolas on the radar profiles allowing visual identification of most root locations. The 800 MHz antenna resulted in the clearest radar profiles. An unsupervised, maximum-convexity migration algorithm was used to focus information contained in the hyperbolas back to a point. This resulted in a significant gain in clarity with roots appearing as discrete shapes, thereby reducing confusion due to overlapping of hyperbolas when many roots are detected. More importantly, parameters extracted from the resultant waveform through the center of a root correlated well with root diameter for the 500 MHz antenna, but not for the other two antennas. A multiple regression model based on the extracted parameters was calibrated on half of the data (R2 = 0.89) and produced good predictions when tested on the remaining data. Root diameters were predicted with a root mean squared error of 0.6 cm, allowing detection and quantification of roots as small as 1 cm in diameter. An advantage of this processing technique is that it produces results independently of signal strength. These waveform parameters represent a major advance in the processing of GPR profiles for estimating root diameters. We conclude that enhanced data analysis routines combined with improvements in GPR hardware design could make GPR a valuable tool for studying tree root systems. PMID:15465695
Barton, Craig V M; Montagu, Kelvin D
2004-12-01
48
PubMed Central
Plant root systems have a key role in ecology and agronomy. In spite of fast increase in root studies, still there is no classification that allows distinguishing among distinctive characteristics within the diversity of rooting strategies. Our hypothesis is that a multivariate approach for “plant functional type” identification in ecology can be applied to the classification of root systems. The classification method presented is based on a data-defined statistical procedure without a priori decision on the classifiers. The study demonstrates that principal component based rooting types provide efficient and meaningful multi-trait classifiers. The classification method is exemplified with simulated root architectures and morphological field data. Simulated root architectures showed that morphological attributes with spatial distribution parameters capture most distinctive features within root system diversity. While developmental type (tap vs. shoot-borne systems) is a strong, but coarse classifier, topological traits provide the most detailed differentiation among distinctive groups. Adequacy of commonly available morphologic traits for classification is supported by field data. Rooting types emerging from measured data, mainly distinguished by diameter/weight and density dominated types. Similarity of root systems within distinctive groups was the joint result of phylogenetic relation and environmental as well as human selection pressure. We concluded that the data-define classification is appropriate for integration of knowledge obtained with different root measurement methods and at various scales. Currently root morphology is the most promising basis for classification due to widely used common measurement protocols. To capture details of root diversity efforts in architectural measurement techniques are essential. PMID:23914200
Bodner, Gernot; Leitner, Daniel; Nakhforoosh, Alireza; Sobotik, Monika; Moder, Karl; Kaul, Hans-Peter
2013-01-01
49
This study provides a comparison of the influence of Pd(P) thickness on reactions during soldering with the Sn-3Ag-0.5Cu alloy. Soldering was carried out in an infrared-enhanced conventional reflow oven, and a multiple reflow test method (up to ten cycles) was performed. With increasing Pd(P) thickness, the (Cu,Ni)6Sn5 grew more slowly at the solder/Ni(P) interface, while the Ni2SnP/Ni3P bilayer became predominant after the first reflow. These three intermetallics, i.e., (Cu,Ni)6Sn5, Ni2SnP, and Ni3P, gradually coarsened as the number of reflow cycles increased. Furthermore, an additional (Ni,Cu)3Sn4 layer appeared between (Cu,Ni)6Sn5 and Ni2SnP, especially for the case of a thicker Pd(P) layer (0.2 ?m). The attachment of the (Ni,Cu)3Sn4 to the Ni2SnP, however, was fairly poor, and a series of microcracks formed along the (Ni,Cu)3Sn4/Ni2SnP interface. To quantify the mechanical response of the interfacial microstructures, shear testing was conducted at two different shear speeds (0.0007 m/s and 2 m/s). The results indicated that the interfacial strength and the Pd(P) thickness were strongly correlated.
Wu, W. H.; Lin, C. S.; Huang, S. H.; Ho, C. E.
2010-11-01
50
NASA Technical Reports Server (NTRS)
The basic techniques applied in the square root least squares and square root filtering solutions are applied to the smoothing problem. Both conventional and square root solutions are obtained by computing the filtered solutions, then modifying the results to include the effect of all measurements. A comparison of computation requirements indicates that the square root information smoother (SRIS) is more efficient than conventional solutions in a large class of fixed interval smoothing problems.
Kaminski, P. G.; Bryson, A. E., Jr.
1972-01-01
51
SciTech Connect
I explore the origins of the unphysical predictions from rooted staggered fermion algorithms. Before rooting, the exact chiral symmetry of staggered fermions is a flavored symmetry among the four 'tastes.' The rooting procedure averages over tastes of different chiralities. This averaging forbids the appearance of the correct 't Hooft vertex for the target theory.
CREUTZ,M.
2007-07-30
52
Travel for the purpose of seeking roots, or roots tourism, is understood to be focused on the descendants of a diaspora living in contemporary multicultural societies and travelling to ancestral homelands in search of identity and belongingness. It is an almost negligible niche segment of heritage tourism due to an obscure amalgam of contextual concepts. The primary purpose of this
Gregory Higginbotham
2012-01-01
53
Information from field studies investigating the responses of roots to increasing atmospheric CO2 is limited and somewhat inconsistent, due partly to the difficulty in studying root systems in situ. In this report, we present standing root biomass of species and root length and diameter after five years of CO2 enrichment (?720 ?mol mol?1) in large (16 m2 ground area) open-top chambers placed over
D. R. LeCain; J. A. Morgan; D. G. Milchunas; A. R. Mosier; J. A. Nelson; D. P. Smith
2006-01-01
54
PubMed
The dielectric/metal/dielectric multilayer is suitable for a transparent electrode because of its high-optical and high-electrical properties; however, it is fabricated by an expensive and inefficient multistep vacuum process. We present a WO3/Ag/WO3 (WAW) multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes (PLEDs). This WAW multilayer not only has high transmittance and low resistance but also can be easily and rapidly fabricated. We devised a novel method to deposit a thin WO3 layer by a solution process in an air environment. A tungstic acid solution was prepared from an aqueous solution of Na2WO4 and then converted to WO3 nanoparticles (NPs) by a thermal treatment. Thin WO3 NP layers form WAW multilayer with a thermal-evaporated Ag layer, and they improve the transmittance of the WAW multilayer because of its high transmittance and refractive index. Moreover, the surface of the WO3 layer is homogeneous and flat with low roughness because of the WO3 NP generation from the tungstic acid solution without aggregation. We performed optical simulation and experiments, and the optimized WAW multilayer had a high transmittance of 85% with a sheet resistance of 4 ?/sq. Finally, PLEDs based on the WAW multilayer anode achieved a maximum luminance of 35,550 cd/m2 at 8 V, and this result implies that the solution-processed WAW multilayer is appropriate for use as a transparent anode in PLEDs. PMID:22587669
Jeon, Kangmin; Youn, Hongseok; Kim, Seongbeom; Shin, Seongbeom; Yang, Minyang
2012-01-01
55
NASA Technical Reports Server (NTRS)
VEGGIE is a plant growth facility that utilizes the phenomenon of capillary action as its primary watering system. A cloth made of Meta Aramid fiber, known as Nomex is used to wick water up from a reservoir to the bottom of the plants roots. This root mat system is intended to be low maintenance with no moving parts and requires minimal crew interface time. Unfortunately, the water wicking rates are inconsistent throughout the plant life cycle, thus causing plants to die. Over-wicking of water occurs toward the beginning of the cycle, while under-wicking occurs toward the middle. This inconsistency of wicking has become a major issue, drastically inhibiting plant growth. The primary objective is to determine the root cause of the inconsistent wicking through experimental testing. Suspect causes for the capillary water column to break include: a vacuum effect due to a negative pressure gradient in the water reservoir, contamination of material due to minerals in water and back wash from plant fertilizer, induced air bubbles while using syringe refill method, and material limitations of Nomex's ability to absorb and retain water. Experimental testing will be conducted to systematically determine the cause of under and over-wicking. Pressure gages will be used to determine pressure drop during the course of the plant life cycle and during the water refill process. A debubbler device will be connected to a root mat in order to equalize pressure inside the reservoir. Moisture and evaporation tests will simultaneously be implemented to observe moisture content and wicking rates over the course of a plant cycle. Water retention tests will be performed using strips of Nomex to determine materials wicking rates, porosity, and absorptivity. Through these experimental tests, we will have a better understanding of material properties of Nomex, as well as determine the root cause of water column breakage. With consistent test results, a forward plan can be achieved to resolve the issue and give valuable insight for the next generation of VEGGIE.
Subbiah, Arun M.
2013-01-01
56
Plant roots help to reinforce the soil, increase slope stability and decrease water erosion. Root tensile strength plays an important role in soil reinforcement and slope stabilization. The relationship between tensile strength and internal chemical composition of roots is unknown due to limited studies. Thus, it is difficult to determine why root tensile strength tends to decrease with increasing root diameter. In this study, biomechanical and biochemical tests were performed on the roots of Chinese pine (Pinus tabulaeformis) to determine the relationships among tensile strength and the contents of the main chemical composition: cellulose, alpha-cellulose and lignin in the roots with different diameters. Our results confirmed that the tensile strength of Chinese pine roots decreased with increasing root diameter, and this relationship might be a power function. The chemical contents of the roots and root diameter were also related to each other with significant power regression. With increasing root diameter, the cellulose content and alpha-cellulose content increased, but the lignin content decreased. In addition, the lignin content exhibited a significantly positive relationship with tensile strength. Furthermore, the ratios of lignin/cellulose and lignin/alpha-cellulose decreased with increasing root diameter following significant power regressions, and they also demonstrated a positive relationship with tensile strength. Taken together, these results may be useful for studies on root tensile strength, soil reinforcement and slope stability.
Zhang, Chao-Bo; Chen, Li-Hua; Jiang, Jing
2014-02-01
57
Root branching happens through the formation of new meristems out of a limited number of pericycle cells inside the parent\\u000a root. As opposed to shoot branching, the study of lateral root formation has been complicated due to its internal nature,\\u000a and a lot of questions remain unanswered. However, due to the availability of new molecular tools and more complete genomic
Ive De Smet; Steffen Vanneste; Dirk Inzé; Tom Beeckman
2006-01-01
58
PubMed
The root system has a crucial role for plant growth and productivity. Due to the challenges of heterogeneous soil environments, diverse environmental signals are integrated into root developmental decisions. While root growth and growth responses are genetically determined, there is substantial natural variation for these traits. Studying the genetic basis of the natural variation of root growth traits can not only shed light on their evolution and ecological relevance but also can be used to map the genes and their alleles responsible for the regulation of these traits. Analysis of root phenotypes has revealed growth strategies and root growth responses to a variety of environmental stimuli, as well as the extent of natural variation of a variety of root traits including ion content, cellular properties, and root system architectures. Linkage and association mapping approaches have uncovered causal genes underlying the variation of these traits. PMID:25104725
Ristova, Daniela; Busch, Wolfgang
2014-10-01
59
ERIC Educational Resources Information Center
If students are presented the standard proof of irrationality of [square root]2, can they generalize it to a proof of the irrationality of "[square root]p", "p" a prime if, instead of considering divisibility by "p", they cling to the notions of even and odd used in the standard proof?
Misiurewicz, Michal
2013-01-01
60
E-print Network
Advanced mathematical and statistical computational methods are required by the LHC experiments for analyzing their data. Some of these methods are provided by the ROOT project, a C++ Object Oriented framework for large scale data handling applications. We review the current mathematical and statistical classes present in ROOT, emphasizing the recent developments.
Moneta, Lorenzo; Brun, R; Kreshuk, Anna
2008-01-01
61
E-print Network
. Armillaria root rot usually becomes apparent when indigenous forests are cleared for afforestation to the fact that indigenous forests are uncommon and few plantations have been established on stands where unsuccessful. It has been found that infection centres apparently disappear after a number of pine rotations
62
PubMed
During a plant's lifecycle, the availability of nutrients in the soil is mostly heterogeneous in space and time. Plants are able to adapt to nutrient shortage or localized nutrient availability by altering their root system architecture to efficiently explore soil zones containing the limited nutrient. It has been shown that the deficiency of different nutrients induces root architectural and morphological changes that are, at least to some extent, nutrient specific. Here, we highlight what is known about the importance of individual root system components for nutrient acquisition and how developmental and physiological responses can be coupled to increase nutrient foraging by roots. In addition, we review prominent molecular mechanisms involved in altering the root system in response to local nutrient availability or to the plant's nutritional status. PMID:25082891
Giehl, Ricardo F H; von Wirén, Nicolaus
2014-10-01
63
PubMed
While water shortage remains the single-most important factor influencing world agriculture, there are very few studies on how plants grow in response to water potential, i.e., hydrotropism. Terrestrial plant roots dwell in the soil, and their ability to grow and explore underground requires many sensors for stimuli such as gravity, humidity gradients, light, mechanical stimulations, temperature, and oxygen. To date, extremely limited information is available on the components of such sensors; however, all of these stimuli are sensed in the root cap. Directional growth of roots is controlled by gravity, which is fixed in direction and intensity. However, other environmental factors, such as water potential gradients, which fluctuate in time, space, direction, and intensity, can act as a signal for modifying the direction of root growth accordingly. Hydrotropism may help roots to obtain water from the soil and at the same time may participate in the establishment of the root system. Current genetic analysis of hydrotropism in Arabidopsis has offered new players, mainly AHR1, NHR1, MIZ1, and MIZ2, which seem to modulate how root caps sense and choose to respond hydrotropically as opposed to other tropic responses. Here we review the mechanism(s) by which these genes and the plant hormones abscisic acid and cytokinins coordinate hydrotropism to counteract the tropic responses to gravitational field, light or touch stimuli. The biological consequence of hydrotropism is also discussed in relation to water stress avoidance. PMID:23258371
Cassab, Gladys I; Eapen, Delfeena; Campos, María Eugenia
2013-01-01
64
PubMed
Podostemaceae have markedly specialized and diverse roots that are adapted to extreme habitats, such as seasonally submerged or exposed rocks in waterfalls and rapids. This paper describes the developmental anatomy of roots of four species of Zeylanidium, with emphasis on the unusual association between root branching and root-borne adventitious shoots. In Z. subulatum and Z. lichenoides with subcylindrical or ribbon-like roots, the apical meristem distal (exterior) to a shoot that is initiated within the meristem area reduces and loses meristematic activity. This results in a splitting into two meristems that separate the parental root and lateral root (anisotomous dichotomy). In Z. olivaceum with lobed foliose roots, shoots are initiated in the innermost zone of the marginal meristem, and similar, but delayed, meristem reduction usually occurs, producing a parenchyma exterior to shoots located between root lobes. In some extreme cases, due to meristem recovery, root lobing does not occur, so the margin is entire. In Z. maheshwarii with foliose roots, shoots are initiated proximal to the marginal meristem and there is no shoot-root lobe association. Results suggest that during evolution from subcylindrical or ribbon-like roots to foliose roots, reduction of meristem exterior to a shoot was delayed and then arrested as a result of inward shifting of the sites of shoot initiation. The evolutionary reappearance of a protective tissue or root cap in Z. olivaceum and Z. maheshwarii in the Zeylanidium clade is implied, taking into account the reported molecular phylogeny and root-cap development in Hydrobryum. PMID:12451029
Hiyama, Y; Tsukamoto, I; Imaichi, R; Kato, M
2002-12-01
65
PubMed Central
Podostemaceae have markedly specialized and diverse roots that are adapted to extreme habitats, such as seasonally submerged or exposed rocks in waterfalls and rapids. This paper describes the developmental anatomy of roots of four species of Zeylanidium, with emphasis on the unusual association between root branching and root?borne adventitious shoots. In Z. subulatum and Z. lichenoides with subcylindrical or ribbon?like roots, the apical meristem distal (exterior) to a shoot that is initiated within the meristem area reduces and loses meristematic activity. This results in a splitting into two meristems that separate the parental root and lateral root (anisotomous dichotomy). In Z. olivaceum with lobed foliose roots, shoots are initiated in the innermost zone of the marginal meristem, and similar, but delayed, meristem reduction usually occurs, producing a parenchyma exterior to shoots located between root lobes. In some extreme cases, due to meristem recovery, root lobing does not occur, so the margin is entire. In Z. maheshwarii with foliose roots, shoots are initiated proximal to the marginal meristem and there is no shoot–root lobe association. Results suggest that during evolution from subcylindrical or ribbon?like roots to foliose roots, reduction of meristem exterior to a shoot was delayed and then arrested as a result of inward shifting of the sites of shoot initiation. The evolutionary reappearance of a protective tissue or root cap in Z. olivaceum and Z. maheshwarii in the Zeylanidium clade is implied, taking into account the reported molecular phylogeny and root?cap development in Hydrobryum. PMID:12451029
HIYAMA, Y.; TSUKAMOTO, I.; IMAICHI, R.; KATO, M.
2002-01-01
66
SciTech Connect
A four-probe ac method over a wide frequency range was used to study the resistivity in ceramic samples of solid solutions of Na/sub 2/O x 6Al/sub 2/O/sub 3/-Ag/sub 2/O x 6Al/sub 2/O/sub 3/. It was found that the change in the conductivity for a transition from sodium b-alumina to silver b-alumina is characterized by the existence of a polyalkali effect.
Barkovskii, A.I.; Volkova, N.F.; Kaul', A.R.; Tret'yakov, Yu.D.
1987-04-01
67
In computational physics very often roots and local extrema of a function have to be determined. In one dimension bisection is a very robust but rather inefficient root finding method. If a good starting point close to the root is available and the function is smooth enough, the Newton-Raphson method converges much faster. Special strategies are necessary to find roots of not so well behaved functions or higher order roots. The combination of bisection and interpolation as by the methods of Dekker, Brent and more recently Chandrupatla provides generally applicable algorithms. In multidimensions Quasi-Newton methods are a good choice. Whereas local extrema can be found as the roots of the gradient, at least in principle, direct optimization can be more efficient. In one dimension the ternary search method or Brent's more efficient golden section search method can be used. In multidimensions the class of direction set search methods is very popular which includes the methods of steepest descent and conjugate gradients, the Newton-Raphson method and, if calculation of the full Hessian matrix is too expensive, the Quasi-Newton methods.
Scherer, Philipp O. J.
68
PubMed Central
The contrasting hydraulic properties of wheat (Triticum aestivum), narrow-leafed lupin (Lupinus angustifolius), and yellow lupin (Lupinus luteus) roots were identified by integrating measurements of water flow across different structural levels of organization with anatomy and modeling. Anatomy played a major role in root hydraulics, influencing axial conductance (Lax) and the distribution of water uptake along the root, with a more localized role for aquaporins (AQPs). Lupin roots had greater Lax than wheat roots, due to greater xylem development. Lax and root hydraulic conductance (Lr) were related to each other, such that both variables increased with distance from the root tip in lupin roots. Lax and Lr were constant with distance from the tip in wheat roots. Despite these contrasting behaviors, the hydraulic conductivity of root cells (Lpc) was similar for all species and increased from the root surface toward the endodermis. Lpc was largely controlled by AQPs, as demonstrated by dramatic reductions in Lpc by the AQP blocker mercury. Modeling the root as a series of concentric, cylindrical membranes, and the inhibition of AQP activity at the root level, indicated that water flow in lupin roots occurred primarily through the apoplast, without crossing membranes and without the involvement of AQPs. In contrast, water flow across wheat roots crossed mercury-sensitive AQPs in the endodermis, which significantly influenced Lr. This study demonstrates the importance of examining root morphology and anatomy in assessing the role of AQPs in root hydraulics. PMID:19321713
Bramley, Helen; Turner, Neil C.; Turner, David W.; Tyerman, Stephen D.
2009-01-01
69
PubMed
Strawberry roots were sampled through the year to determine the populations and distribution of Pratylenchus penetrans and Meloidogyne hapla. Three strawberry root types were sampled-structural roots; feeder roots without secondary tissues; and suberized, black perennial roots. Both lesion and root-knot nematodes primarily infected feeder roots from structural roots or healthy perennial roots. Few nematodes were recovered from soil, diseased roots, or suberized roots. Lesion nematode recovery was correlated with healthy roots. In both 1997 and 1998, P. penetrans populations peaked about day 150 (end of May) and then declined. The decline in numbers corresponded to changes in total strawberry root weight and root type distribution. The loss of nematode habitat resulted from loss of roots due to disease and the transition from structural to suberized perennial roots. Meloidogyne hapla juvenile recovery peaked around 170 days (mid June) in 1997 and at 85, 147, 229, and 308 days (late March, late May, mid August, and early November, respectively) in 1998. There appear to be at least four generations per year of M. hapla in Connecticut. Diagnostic samples from an established strawberry bed may be most reliable and useful when they include feeder roots taken in late May. PMID:19265965
Lamindia, J A
2002-12-01
70
Roots strongly contribute to soil organic carbon accrual, but the rate of soil carbon input via root litter decomposition is still uncertain. Root systems are built up of roots with a variety of different diameter size classes, ranging from very fine to very coarse roots. Since fine roots have low C:N ratios and coarse roots have high C:N ratios, root systems are heterogeneous in quality, spanning a range of different C:N ratios. Litter decomposition rates are generally well predicted by litter C:N ratios, thus decomposition of roots may be controlled by the relative abundance of fine versus coarse roots. With this study we asked how root architecture (i.e. the relative abundance of fine versus coarse roots) affects the decomposition of roots systems in the biofuels crop switchgrass (Panicum virgatum L.). To understand how root architecture affects root decomposition rates, we collected roots from eight switchgrass cultivars (Alamo, Kanlow, Carthage, Cave-in-Rock, Forestburg, Southlow, Sunburst, Blackwell), grown at FermiLab (IL), by taking 4.8-cm diameter soil cores from on top of the crown and directly next to the crown of individual plants. Roots were carefully excised from the cores by washing and analyzed for root diameter size class distribution using WinRhizo. Subsequently, root systems of each of the plants (4 replicates per cultivar) were separated in 'fine' (0-0.5 mm), 'medium' (0.5-1 mm) and 'coarse' roots (1-2.5 mm), dried, cut into 0.5 cm (medium and coarse roots) and 2 mm pieces (fine roots), and incubated for 90 days. For each of the cultivars we established five root-treatments: 20g of soil was amended with 0.2g of (1) fine roots, (2) medium roots, (3) coarse roots, (4) a 1:1:1 mixture of fine, medium and coarse roots, and (5) a mixture combining fine, medium and coarse roots in realistic proportions. We measured CO2 respiration at days 1, 3, 7, 15, 30, 60 and 90 during the experiment. The 13C signature of the soil was -26‰, and the 13C signature of plants was -12‰, enabling us to differentiate between root-derived C and native SOM-C respiration. We found that the relative abundance of fine, medium and coarse roots were significantly different among cultivars. Root systems of Alamo, Kanlow and Cave-in-Rock were characterized by a large abundance of coarse-, relative to fine roots, whereas Carthage, Forestburg and Blackwell had a large abundance of fine, relative to coarse roots. Fine roots had a 28% lower C:N ratio than medium and coarse roots. These differences led to different root decomposition rates. We conclude that root architecture should be taken into account when predicting root decomposition rates; enhanced understanding of the mechanisms of root decomposition will improve model predictions of C input to soil organic matter.
de Graaff, M.; Schadt, C.; Garten, C. T.; Jastrow, J. D.; Phillips, J.; Wullschleger, S. D.
2010-12-01
71
Fine root biomass can be estimated from the quantity of DNA of a target plant extracted from fine root samples using regression analysis. However, the application of this method to fine root samples mixed with soil particles (mixed samples) is difficult due to the high DNA adsorption capacity of some clay minerals. Our aim in this study was to clarify
Shin Ugawa; Muneyoshi Yamaguchi; Satoru Miura; Shinji Kaneko
2012-01-01
72
ERIC Educational Resources Information Center
No, your students will not be drinking green root beer for St. Patrick's Day--this "green" root beer laboratory promotes environmental awareness in the science classroom, and provides a venue for some very sound science content! While many science classrooms incorporate root beer-brewing activities, the root beer lab presented in this article has…
Clary, Renee; Wandersee, James
2010-01-01
73
PubMed Central
Background and Aims Basic information about the root and root nodule structure of leguminous crop plants is incomplete, with many aspects remaining unresolved. Peanut (Arachis hypogaea) forms root nodules in a unique process. Structures of various peanut root types were studied with emphasis on insufficiently characterized lateral roots, changes in roots during their ontogenesis and root modification by nodule formation. Methods Peanut plants were grown in the field, in vermiculite or in filter paper. The taproot, first-order and second-order lateral roots and root nodules were analysed using bright-field and fluorescence microscopy with hand sections and resin sections. Key Results Three root categories were recognized. The primary seminal root was thick, exhibiting early and intensive secondary thickening mainly on its base. It was tetrarch and contained broad pith. First-order lateral roots were long and thin, with limited secondary thickening; they contained no pith. Particularly different were second- and higher-order lateral roots, which were anatomically simple and thin, with little or no secondary growth. Unusual wall ingrowths were visible in the cells of the central part of the cortex in the first-order and second-order lateral roots. The nodule body was formed at the junction of the primary and lateral roots by the activity of proliferating cells derived originally from the pericycle. Conclusions Two morphologically and anatomically distinct types of lateral roots were recognized: long, first-order lateral roots, forming the skeleton of the root system, and thin and short second- and higher-order lateral roots, with an incomplete second state of endodermal development, which might be classified as peanut ‘feeder roots’. Formation of root nodules at the base of the lateral roots was the result of proliferating cell divisions derived originally from the pericycle. PMID:18256023
Tajima, Ryosuke; Abe, Jun; Lee, O. New; Morita, Shigenori; Lux, Alexander
2008-01-01
74
PubMed Central
Studying development and physiology of growing roots is challenging due to limitations regarding cellular and subcellular analysis under controlled environmental conditions. We describe a microfluidic chip platform, called RootChip, that integrates live-cell imaging of growth and metabolism of Arabidopsis thaliana roots with rapid modulation of environmental conditions. The RootChip has separate chambers for individual regulation of the microenvironment of multiple roots from multiple seedlings in parallel. We demonstrate the utility of The RootChip by monitoring time-resolved growth and cytosolic sugar levels at subcellular resolution in plants by a genetically encoded fluorescence sensor for glucose and galactose. The RootChip can be modified for use with roots from other plant species by adapting the chamber geometry and facilitates the systematic analysis of root growth and metabolism from multiple seedlings, paving the way for large-scale phenotyping of root metabolism and signaling. PMID:22186371
Grossmann, Guido; Guo, Woei-Jiun; Ehrhardt, David W.; Frommer, Wolf B.; Sit, Rene V.; Quake, Stephen R.; Meier, Matthias
2011-01-01
75
\\u000a Root hairs are long tubular outgrowths of root epidermis cell that form to increase the root surface in order to assist in\\u000a the uptake of water and nutrients from soil. Root hair development consists of two distinct processes: root hair initiation\\u000a and tip growth. During both events, the dynamic organization of the cytoskeleton translates local signaling events into a\\u000a focused
Eunsook Park; Andreas Nebenführ
76
NASA Technical Reports Server (NTRS)
It is widely accepted that the Arabidopsis Adh (alcohol dehydrogenase) gene is constitutively expressed at low levels in the roots of young plants grown on agar media, and that the expression level is greatly induced by anoxic or hypoxic stresses. We questioned whether the agar medium itself created an anaerobic environment for the roots upon their growing into the gel. beta-Glucuronidase (GUS) expression driven by the Adh promoter was examined by growing transgenic Arabidopsis plants in different growing systems. Whereas roots grown on horizontal-positioned plates showed high Adh/GUS expression levels, roots from vertical-positioned plates had no Adh/GUS expression. Additional results indicate that growth on vertical plates closely mimics the Adh/GUS expression observed for soil-grown seedlings, and that growth on horizontal plates results in induction of high Adh/GUS expression that is consistent with hypoxic or anoxic conditions within the agar of the root zone. Adh/GUS expression in the shoot apex is also highly induced by root penetration of the agar medium. This induction of Adh/GUS in shoot apex and roots is due, at least in part, to mechanisms involving Ca2+ signal transduction.
Chung, H. J.; Ferl, R. J.
1999-01-01
77
PubMed Central
Background Phosphorus (P) is an essential macronutrient for all living organisms. Maize (Zea mays) is an important human food, animal feed and energy crop throughout the world, and enormous quantities of phosphate fertilizer are required for maize cultivation. Thus, it is important to improve the efficiency of the use of phosphate fertilizer for maize. Results In this study, we analyzed the maize root response to phosphate starvation and performed a transcriptomic analysis of the 1.0-1.5?cm lateral root primordium zone. In the growth of plants, the root-to-shoot ratio (R/L) was reduced in both low-phosphate (LP) and sufficient-phosphate (SP) solutions, but the ratio (R/L) exhibited by the plants in the LP solution was higher than that of the SP plants. The growth of primary roots was slightly promoted after 6?days of phosphate starvation, whereas the numbers of lateral roots and lateral root primordia were significantly reduced, and these differences were increased when associated with the stress caused by phosphate starvation. Among the results of a transcriptomic analysis of the maize lateral root primordium zone, there were two highlights: 1) auxin signaling participated in the response and the modification of root morphology under low-phosphate conditions, which may occur via local concentration changes due to the biosynthesis and transport of auxin, and LOB domain proteins may be an intermediary between auxin signaling and root morphology; and 2) the observed retardation of lateral root development was the result of co-regulation of DNA replication, transcription, protein synthesis and degradation and cell growth. Conclusions These results indicated that maize roots show a different growth pattern than Arabidopsis under low-phosphate conditions, as the latter species has been observed to halt primary root growth when the root tip comes into contact with low-phosphate media. Moreover, our findings enrich our understanding of plant responses to phosphate deficits and of root morphogenesis in maize. PMID:22704465
2012-01-01
78
Roots mechanically reinforce many soils. Root tensile strength and stiffness is critical for soil stabilisation with plants potentially providing civil engineers a 'green' alternative for soil stabilisation. Relatively little is known on factors influencing root tensile strength. Through a better understanding of these factors the adoption of 'green engineering' techniques by civil engineers will improve. Existing models are limited in their accuracy due to simplistic assumptions to derive root contributions to the resistance of soil to failure. Current models typically use relationships between strength and diameter, however, there are a number of other factors potentially influencing root biomechanical properties. The effects of root age on biomechanical properties have largely been overlooked. Barley (Hordeum vulgare) was grown under differing soil conditions, waterlogged, moderate mechanical impedance and in unimpeded, control, conditions. The root system was excavated and tensile tests performed on root sections along the length of each root axis. Root tensile strength increased with increasing distance along the root axes in control soil from 0.5 MPa to 7.0 MPa at a distance of 800mm from the root tip and from 1.0 Mpa to 8.0 MPa, 500mm from the root tip when under moderate mechanical impedance. Increases in strength were also observed when plants were subjected to waterlogging with tensile strength increasing from 1.0 MPa to 3.0 MPa, 200mm from the root tip. Young's modulus increased from ~10 MPa at the root tip to ~60 MPa 400mm and 800mm from the root tip in mechanically impeded and control treatments respectively. Distance from root tip explained over 47% of the variance in root tensile strength and 34% of root stiffness. Including root diameter in the model led to further improvements in predicting root properties, explaining ~54% of root strength variance and ~49% of root stiffness. Root age has been shown to improve predictions of root tensile strength and modulus with the inclusion of root diameter improving predictions further. Laser sectioning of maize (Zea mays) roots demonstrate the damage caused during biomechanical testing and help explain potential reasons for poor relationships between diameter and strength due to stress localisation within the stele. Furthermore, changes in biomechanical root properties associated with age maybe as a result of lignin deposition but this remains to be established.
Loades, Kenneth; Hallett, Paul; Lynch, Jonathan; Chimungu, Joseph; Bengough, Anthony
2014-05-01
79
NASA Technical Reports Server (NTRS)
Half-tipped primary and lateral roots of Phaseolus vulgaris bend toward the side of the root on which the intact half tip remains. Therefore, tips of lateral and primary roots produce growth effectors capable of inducing gravicurvature. The asymmetrical placement of a tip of a lateral root onto a detipped primary root results in the root bending toward the side of the root onto which the tip was placed. That is, the lesser graviresponsiveness of lateral roots as compared with primary roots is not due to the inability of their caps to produce growth inhibitors. The more pronounced graviresponsiveness of primary roots is positively correlated with the presence of columella tissues that are 3.8 times longer, 1.7 times wider, and 10.5 times more voluminous than the columellas of lateral roots. We propose that the lack of graviresponsiveness exhibited by lateral roots is due to the fact that they (i) produce smaller amounts of the inhibitor than primary (i.e., strongly graviresponsive) roots and (ii) are unable to redistribute the inhibitor so as to be able to create a concentration gradient sufficient to induce a pronounced gravitropic response.
Ransom, J. S.; Moore, R.
1985-01-01
80
Many studies exist that characterise plant root architecture by calculating the fractal dimension of the root network, but few studies quantify the branching characteristics of the root network. This paper examines the Tokunaga side-branching statistics for the root systems of four plants--Sugar Beet (Beta vulgaris), Lucern (Medicago sativa), Common Wheat (Triticum aestivum) and White Clover (Trifolium michelianum)--and compares the resulting statistics to those calculated by similar means (by other authors) for the Kentucky and Powder River drainage basins and several Diffusion Limited Aggregation (DLA) models. The plant root networks studied all contained similar numbers of different order roots, but the side-branching statistics differed, offering one explanation for the differing visual appearance of the branching root networks. The White Clover plant had similar Tokunaga branching statistics to the drainage networks and DLA models. This may be due to the dichotomous root structure of the White Clover plant, which produces a network that is much more similar in appearance to the two drainage networks and DLA models than the other three plants, which had herringbone root. All of the root networks, drainage basins, and DLA models had branching networks that could be quantified well to very well by Tokunaga side-branching statistics. For many years, engineers have avoided implementation of stabilisation schemes involving vegetation, due to the inherent problems involved in the quantification of their dynamic and complex root structures. The use of Tokunaga statistics as a simplifying measure of root branching characteristics, may aid in this aspect, as well as others, such as the modelling of nutrient or water uptake.
Pollen, N.; Malamud, B.
2001-12-01
81
PubMed Central
Background and Aims The Finite Element Method (FEM) has been used in recent years to simulate overturning processes in trees. This study aimed at using FEM to determine the role of individual roots in tree anchorage with regard to different rooting patterns, and to estimate stress distribution in the soil and roots during overturning. Methods The FEM was used to carry out 2-D simulations of tree uprooting in saturated soft clay and loamy sand-like soil. The anchorage model consisted of a root system embedded in a soil block. Two root patterns were used and individual roots removed to determine their contribution to anchorage. Key Results In clay-like soil the size of the root–soil plate formed during overturning was defined by the longest roots. Consequently, all other roots localized within this plate had no influence on anchorage strength. In sand-like soil, removing individual root elements altered anchorage resistance. This result was due to a modification of the shape and size of the root–soil plate, as well as the location of the rotation axis. The tap root and deeper roots had more influence on overturning resistance in sand-like soil compared with clay-like soil. Mechanical stresses were higher in the most superficial roots and also in leeward roots in sand-like soil. The relative difference in stresses between the upper and lower sides of lateral roots was sensitive to root insertion angle. Assuming that root eccentricity is a response to mechanical stresses, these results explain why eccentricity differs depending on root architecture. Conclusions A simple 2-D Finite Element model was developed to better understand the mechanisms involved during tree overturning. It has been shown how root system morphology and soil mechanical properties can modify the shape of the root plate slip surface as well as the position of the rotation axis, which are major components of tree anchorage. PMID:17942593
Fourcaud, Thierry; Ji, Jin-Nan; Zhang, Zhi-Qiang; Stokes, Alexia
2008-01-01
82
PubMed
A vertical root fracture (VRF) is a frustrating complication that may occur following root canal treatment, and in almost every case leads to the extraction of the affected tooth. This type of fracture is usually diagnosed by secondary symptoms that develop some time after primary treatment, often when prosthodontic restoration has already been completed. The fracture line itself is often not directly visible, and therefore clinical and radiographic signs and symptoms indicate the diagnosis indirectly. Knowledge of the condition and pathogenesis of VRF is required in order to avoid hopeless trials of periodontal and/or endodontic therapy. Several etiologic factors are discussed that make teeth susceptible to VRF, such as the loss of substance due to restorative and endodontic therapy and stress factors associated with root canal debridement, and filling. PMID:23757466
Haueisen, Helga; Gärtner, Kathrin; Kaiser, Lea; Trohorsch, Dominik; Heidemann, Detlef
2013-07-01
83
ERIC Educational Resources Information Center
This newsletter covers educational issues affecting schools in the Western Regional Educational Laboratory's 4-state region (Arizona, California, Nevada, and Utah) and nationwide. The following articles appear in the Volume 4, Number 1 issue: (1) "The Roots of Reading"; (2) "Breaking the Code: Reading Literacy in K-3"; (3) "Improving Secondary…
Montoya, Colleen, Ed.
2002-01-01
84
In the mathematical theory of stable populations, when the net maternity function is scaled by a constant divisor, changing its level without changing its shape, the rates of attrition of transient waves in the age structure of the population as it converges toward stability are altered. The attrition rates are specified by the real parts of the complex roots of
Kenneth W. Wachter
1984-01-01
85
Local wound debridement in the diseased pulp space is the main step in root canal treatment to prevent the tooth from being a source of infection. In this review article, the specifics of the pulpal microenvironment and the resulting requirements for irrigating solutions are spelled out. Sodium hypochlorite solutions are recommended as the main irrigants. This is because of their
Matthias Zehnder
2006-01-01
86
EPA Science Inventory
PRZM3 is a modeling system that links two subordinate models - PRZM and VADOFT to predict pesticide transport and transformation down through the crop root and unsaturated zone. PRZM3 includes modeling capabilities for such phenomena as soil temperature simulation, vo...
87
ERIC Educational Resources Information Center
Sandy White Hawk, Sicangu Lakota, was adopted by white missionaries as an infant and suffered child abuse. After 33 years, she found her birth family and formed First Nations Orphans Association, which uses songs and ceremonies to help adoptees return to their roots. Until the 1970s, federal agencies and welfare organizations facilitated removal…
Frey, Jennifer
2001-01-01
88
A frequent criticism of unit root tests concerns the poor power and size properties that many such tests exhibit. However, during the past decade or so intensive research has been conducted to alleviate these problems and great advances have been made. The present paper provides a selective survey of recent contributions to improve upon both the size and power of
Niels Haldrup; Michael Jansson
89
PubMed
Plants associate with a wide range of beneficial fungi in their roots which facilitate plant mineral nutrient uptake in exchange for carbohydrates and other organic metabolites. These associations play a key role in shaping terrestrial ecosystems and are widely believed to have promoted the evolution of land plants. To establish compatibility with their host, root-associated fungi have evolved diverse colonization strategies with distinct morphological, functional and genomic specializations as well as different degrees of interdependence. They include obligate biotrophic arbuscular mycorrhizal (AM), and facultative biotrophic ectomycorrhizal (ECM) interactions but are not restricted to these well-characterized symbioses. There is growing evidence that root endophytic associations, which due to their inconspicuous nature have been often overlooked, can be of mutualistic nature and represent important players in natural and managed environments. Recent research into the biology and genomics of root associations revealed fascinating insight into the phenotypic and trophic plasticity of these fungi and underlined genomic traits associated with biotrophy and saprotrophy. In this review we will consider the commonalities and differences of AM and ECM associations and contrast them with root endophytes. PMID:24929298
Zuccaro, Alga; Lahrmann, Urs; Langen, Gregor
2014-08-01
90
PubMed
The phytotoxicity of Mn is important globally due to its increased solubility in acid or waterlogged soils. Short-term (?24 h) solution culture studies with 150 µM Mn were conducted to investigate the in situ distribution and speciation of Mn in apical tissues of hydrated roots of cowpea [Vigna unguiculata (L.) Walp. cv. Red Caloona] using synchrotron-based techniques. Accumulation of Mn was rapid; exposure to 150 µM Mn for only 5 min resulting in substantial Mn accumulation in the root cap and associated mucigel. The highest tissue concentrations of Mn were in the root cap, with linear combination fitting of the data suggesting that??80% of this Mn(II) was associated with citrate. Interestingly, although the primary site of Mn toxicity is typically the shoots, concentrations of Mn in the stele of the root were not noticeably higher than in the surrounding cortical tissues in the short-term (?24 h). The data provided here from the in situ analyses of hydrated roots exposed to excess Mn are, to our knowledge, the first of this type to be reported for Mn and provide important information regarding plant responses to high Mn in the rooting environment. PMID:22892034
Kopittke, Peter M; Lombi, Enzo; McKenna, Brigid A; Wang, Peng; Donner, Erica; Webb, Richard I; Blamey, F Pax C; de Jonge, Martin D; Paterson, David; Howard, Daryl L; Menzies, Neal W
2013-04-01
91
Rooting of axillary shoots of two blue honeysuckle forms, Lonicera caerulea f. caerulea and L. caerulea f. edulis, was studied.\\u000a Both in vitro and ex vitro rooting procedures were used, and the effects of mineral and auxin concentrations of the rooting\\u000a media were tested. Reduced mineral nutrient concentrations of modified MS medium allowed more root elongation but did not\\u000a affect
Saila T. Karhu
1997-01-01
92
PubMed Central
The contribution of savannas to global carbon storage is poorly understood, in part due to lack of knowledge of the amount of belowground biomass. In these ecosystems, the coexistence of woody and herbaceous life forms is often explained on the basis of belowground interactions among roots. However, the distribution of root biomass in savannas has seldom been investigated, and the dependence of root biomass on rainfall regime remains unclear, particularly for woody plants. Here we investigate patterns of belowground woody biomass along a rainfall gradient in the Kalahari of southern Africa, a region with consistent sandy soils. We test the hypotheses that (1) the root depth increases with mean annual precipitation (root optimality and plant hydrotropism hypothesis), and (2) the root-to-shoot ratio increases with decreasing mean annual rainfall (functional equilibrium hypothesis). Both hypotheses have been previously assessed for herbaceous vegetation using global root data sets. Our data do not support these hypotheses for the case of woody plants in savannas. We find that in the Kalahari, the root profiles of woody plants do not become deeper with increasing mean annual precipitation, whereas the root-to-shoot ratios decrease along a gradient of increasing aridity. PMID:22470506
Bhattachan, Abinash; Tatlhego, Mokganedi; Dintwe, Kebonye; O'Donnell, Frances; Caylor, Kelly K.; Okin, Gregory S.; Perrot, Danielle O.; Ringrose, Susan; D'Odorico, Paolo
2012-01-01
93
Strigolactones (SLs) were defined as a new group of plant hormones that suppress lateral shoot branching. Our previous studies suggested SLs to be regulators of root development. SLs were shown to alter root architecture by regulating lateral root formation and to affect root hair elongation in Arabidopsis. Another important effect of SLs on root growth was shown to be associated with root directional growth. Supplementation of SLs to roots led to alterations in root directional growth, whereas associated mutants showed asymmetrical root growth, which was influenced by environmental factors. The regulation by SLs of root development was shown to be conducted via a cross talk of SLs with other plant hormones, including auxin. SLs were shown to regulate auxin transport, and to interfere with the activity of auxin-efflux carriers. Therefore, it might be that SLs are regulators of root directional growth as a result of their ability to regulated auxin transport. However, other evidences suggest a localized effect of SLs on cell division, which may not necessarily be associated with auxin efflux. These and other, recent hypothesis as to the SLs mode of action and the associated root perception and response to environmental factors will be discussed.
Koltai, Hinanit
2012-07-01
94
NSDL National Science Digital Library
Exponential notation for Nth roots and radicals is introduced. A short discussion about Nth roots and irrational numbers follows before symbolic manipulation of fractional exponents and solving equations is presented. Power functions and solving radical equations are presented before the lesson concludes with roots of negative numbers.
2011-01-01
95
In the present work, series of silver doped Ge-Ga-S-AgI chalcohalide glasses have been prepared and their optical transmission spectra are compared before and after ?-ray irradiation at different doses. The differential transmission spectra of the irradiated samples with and without Ag doping have been compared to characterize the ?-ray irradiation induced red-shift of electronic absorption and formation of color centers. Ag doping plays an important role in increasing ?-ray irradiation resistance of the chalcohalide glasses due to its specific effect on the valence band and the network structure of glasses.
Zhou, Y.; Shen, W.; Zhang, Z.; Yang, Y.; Chen, G.; Baccaro, S.; Cemmi, A.
2014-06-01
96
In the present work, series of silver doped Ge-Ga-S-AgI chalcohalide glasses have been prepared and their optical transmission spectra are compared before and after ?-ray irradiation at different doses. The differential transmission spectra of the irradiated samples with and without Ag doping have been compared to characterize the ?-ray irradiation induced red-shift of electronic absorption and formation of color centers. Ag doping plays an important role in increasing ?-ray irradiation resistance of the chalcohalide glasses due to its specific effect on the valence band and the network structure of glasses.
Shen, W.; Baccaro, S.; Cemmi, A.; Ren, J.; Zhang, Z.; Zhou, Y.; Yang, Y.; Chen, G.
2014-06-01
97
NASA Technical Reports Server (NTRS)
Conditions under which a gravistimulus of Merit corn roots (Zea mays L.) is withdrawn result in a subsequent loss of gravitropic curvature, an effect which we refer to as springback.' This loss of curvature begins within 1 to 10 minutes after removal of the gravistimulus. It occurs regardless of the presence or absence of the root cap. It is insensitive to inhibitors of auxin transport (2,3,5-triiodobenzoic acid, naphthylphthalamic [correction of naphthylphthalmaic] acid) or to added auxin (2,4-dichlorophenoxyacetic acid). Springback is prevented if a clinostat treatment is interjected to neutralize gravistimulation during germination, which suggests that the change in curvature is a response to a memory' effect carried over from a prior gravistimulation.
Leopold, A. C.; Wettlaufer, S. H.
1989-01-01
98
E-print Network
We present an open-source Mathematica importer for CERN ROOT files. Taking advantage of Mathematica's import/export plug-in mechanism, the importer offers a simple, unified interface that cleanly wraps around its MathLink-based core that links the ROOT libraries with Mathematica. Among other tests for accuracy and efficiency, the importer has also been tested on a large (~5 Gbyte) file structure, D3PD, used by the ATLAS experiment for offline analysis without problems. In addition to describing the installation and usage of the importer, we discuss how the importer may be further improved and customized. A link to the package can be found at: http://library.wolfram.com/infocenter/Articles/7793/ and a related presentation is at: http://cd-docdb.fnal.gov/cgi-bin/DisplayMeeting?conferenceid=522
Ken Hsieh; Thomas G. Throwe; Sebastian White
2011-02-24
99
E-print Network
excelsa, Pinus sylvestri.s, Strobw, P. Laricio, Larix Europoea, Acer platanoides. Fagus. This disease manifests itself by the blackening of the roots and rootlets. The Cotylcdons have a spotted appearance. Warm and moist weather causes the fungus... is a case of symbiosis, and Kamien- ski holds that symbiosis cannot be applied to all the ~Kycorhiza forms described by Frank; that in case of Carpinzn Betulus and Pinus Sylvestris the niycelium of the fungns causes hyper- trophy of the tissues. Dr...
Pammel, L. H. (Louis Herman)
1889-01-01
100
PubMed
The specialized root epidermis cells of higher plants produce long, tubular outgrowths called root hairs. Root hairs play an important role in nutrient and water uptake, and they serve as a valuable model in studies of plant cell morphogenesis. More than 1,300 articles that describe the biological processes of these unique cells have been published to date. As new fields of root hair research are emerging, the number of new papers published each year and the volumes of new relevant data are continuously increasing. Therefore, there is a general need to facilitate studies on root hair biology by collecting, presenting, and sharing the available information in a systematic, curated manner. Consequently, in this paper, we present a comprehensive database of root hair genomics, iRootHair, which is accessible as a Web-based service. The current version of the database includes information about 153 root hair-related genes that have been identified to date in dicots and monocots along with their putative orthologs in higher plants with sequenced genomes. In order to facilitate the use of the iRootHair database, it is subdivided into interrelated, searchable sections that describe genes, processes of root hair formation, root hair mutants, and available references. The database integrates bioinformatics tools with a focus on sequence identification and annotation. iRootHair is a unique resource for root hair research that integrates the large volume of data related to root hair genomics in a single, curated, and expandable database that is freely available at www.iroothair.org. PMID:23129204
Kwasniewski, Miroslaw; Nowakowska, Urszula; Szumera, Jakub; Chwialkowska, Karolina; Szarejko, Iwona
2013-01-01
101
NSF Publications Database
... plant roots secrete a wide variety of compounds that affect other nearby roots, as well as insects ... from Arabidopsis roots kill a wide range of bacteria, confirming that roots are not always ...
102
NASA Technical Reports Server (NTRS)
A non-destructive technique (minirhizotron observation tubes) was used to assess the effects of CO2 enrichment on root growth and development in experimental plots in a scrub oak-palmetto community at the Kennedy Space Center. Potential effects of CO2 enrichment on plants have a global significance in light of concerns over increasing CO2 concentrations in the Earth's atmosphere. The study at Kennedy Space Center focused on aboveground physiological responses (photosynthetic efficiency and water use efficiency), effects on process rates (litter decomposition and nutrient turnover), and belowground responses of the plants. Belowground dynamics are an exceptionally important component of total plant response but are frequently ignored due to methodological difficulties. Most methods used to examine root growth and development are destructive and, therefore, severely compromise results. Minirhizotrons allow nondestructive observation and quantification of the same soil volume and roots through time. Root length density and root phenology were evaluated for CO2 effects with this nondestructive technique.
Day, Frank P., Jr.
1994-01-01
103
We shall consider the philosophical roots of cosmology in the earlier Greek philosophy. Our goal is to answer the question: Are earlier Greek theories of pure philosophical-mythological character, as often philosophers cited it, or they have scientific character. On the bases of methodological criteria, we shall contend that the latter is the case. In order to answer the question about contemporary situation of the relation philosophy-cosmology, we shall consider the next question: Is contemporary cosmology completely independent of philosophical conjectures? The answer demands consideration of methodological character about scientific status of contemporary cosmology. We also consider some aspects of the relation contemporary philosophy-cosmology.
Ivanovic, M.
2008-10-01
104
PubMed
The microtubules of root hairs of Raphanus sativus, Lepidium sativum, Equisetum hyemale, Limnobium stoloniferum, Ceratopteris thalictroides, Allium sativum and Urtica dioica were investigated using immunofluorescence and electron microscopy. Arrays of cortical microtubules were observed in all hairs. The microtubules in the hairs show net axial orientations, but in Allium and Urtica helical microtubule patterns are also present. Numerical parameters of microtubules in Raphanus, Equisetum and Limnobium were determined from dry-cleave preparations. The results are discussed with respect to cell wall deposition and cell morphogenesis. PMID:4066793
Traas, J A; Braat, P; Emons, A M; Meekes, H; Derksen, J
1985-06-01
105
PubMed Central
Background Plants form the base of the terrestrial food chain and provide medicines, fuel, fibre and industrial materials to humans. Vascular land plants rely on their roots to acquire the water and mineral elements necessary for their survival in nature or their yield and nutritional quality in agriculture. Major biogeochemical fluxes of all elements occur through plant roots, and the roots of agricultural crops have a significant role to play in soil sustainability, carbon sequestration, reducing emissions of greenhouse gasses, and in preventing the eutrophication of water bodies associated with the application of mineral fertilizers. Scope This article provides the context for a Special Issue of Annals of Botany on ‘Matching Roots to Their Environment’. It first examines how land plants and their roots evolved, describes how the ecology of roots and their rhizospheres contributes to the acquisition of soil resources, and discusses the influence of plant roots on biogeochemical cycles. It then describes the role of roots in overcoming the constraints to crop production imposed by hostile or infertile soils, illustrates root phenotypes that improve the acquisition of mineral elements and water, and discusses high-throughput methods to screen for these traits in the laboratory, glasshouse and field. Finally, it considers whether knowledge of adaptations improving the acquisition of resources in natural environments can be used to develop root systems for sustainable agriculture in the future. PMID:23821619
White, Philip J.; George, Timothy S.; Gregory, Peter J.; Bengough, A. Glyn; Hallett, Paul D.; McKenzie, Blair M.
2013-01-01
106
PubMed
We present a novel image analysis tool that allows the semiautomated quantification of complex root system architectures in a range of plant species grown and imaged in a variety of ways. The automatic component of RootNav takes a top-down approach, utilizing the powerful expectation maximization classification algorithm to examine regions of the input image, calculating the likelihood that given pixels correspond to roots. This information is used as the basis for an optimization approach to root detection and quantification, which effectively fits a root model to the image data. The resulting user experience is akin to defining routes on a motorist's satellite navigation system: RootNav makes an initial optimized estimate of paths from the seed point to root apices, and the user is able to easily and intuitively refine the results using a visual approach. The proposed method is evaluated on winter wheat (Triticum aestivum) images (and demonstrated on Arabidopsis [Arabidopsis thaliana], Brassica napus, and rice [Oryza sativa]), and results are compared with manual analysis. Four exemplar traits are calculated and show clear illustrative differences between some of the wheat accessions. RootNav, however, provides the structural information needed to support extraction of a wider variety of biologically relevant measures. A separate viewer tool is provided to recover a rich set of architectural traits from RootNav's core representation. PMID:23766367
Pound, Michael P; French, Andrew P; Atkinson, Jonathan A; Wells, Darren M; Bennett, Malcolm J; Pridmore, Tony
2013-08-01
107
PubMed
Future ecosystem properties of grasslands will be driven largely by belowground biomass responses to climate change, which are challenging to understand due to experimental and technical constraints. We used a multi-faceted approach to explore single and combined impacts of elevated CO2 and warming on root carbon (C) and nitrogen (N) dynamics in a temperate, semiarid, native grassland at the Prairie Heating and CO2 Enrichment experiment. To investigate the indirect, moisture mediated effects of elevated CO2, we included an irrigation treatment. We assessed root standing mass, morphology, residence time and seasonal appearance/disappearance of community-aggregated roots, as well as mass and N losses during decomposition of two dominant grass species (a C3 and a C4). In contrast to what is common in mesic grasslands, greater root standing mass under elevated CO2 resulted from increased production, unmatched by disappearance. Elevated CO2 plus warming produced roots that were longer, thinner and had greater surface area, which, together with greater standing biomass, could potentially alter root function and dynamics. Decomposition increased under environmental conditions generated by elevated CO2, but not those generated by warming, likely due to soil desiccation with warming. Elevated CO2, particularly under warming, slowed N release from C4-but not C3-roots, and consequently could indirectly affect N availability through treatment effects on species composition. Elevated CO2 and warming effects on root morphology and decomposition could offset increased C inputs from greater root biomass, thereby limiting future net C accrual in this semiarid grassland. PMID:24643718
Carrillo, Yolima; Dijkstra, Feike A; LeCain, Dan; Morgan, Jack A; Blumenthal, Dana; Waldron, Sarah; Pendall, Elise
2014-06-01
108
PubMed Central
Water encounters various resistances in moving along a path of decreasing potential energy from the soil through the plant to the atmosphere. The reported relative magnitudes of these pathway resistances vary widely and often these results are conflicting. One reason for such inconsistency is the difficulty in measuring the potential drop across various segments of the soil-plant-atmosphere continuum. The measurement of water potentials at the soil-root interface and in the root xylem of a transpiring plant remains a challenging problem. In the divided root experiment reported here, the measured water potential of an enclosed, nonabsorbing branch of the root system of young corn (Bonanza) plants to infer the water potential of the remaining roots growing in soil was used. The selected root branch of the seedling was grown in a specially constructed Teflon test tube into which a screen-enclosed thermocouple psychrometer was inserted and sealed to monitor the root's water potential. The root and its surrounding atmosphere were assumed to be in vapor equilibrium. Images PMID:16661886
Adeoye, Kingsley B.; Rawlins, Stephen L.
1981-01-01
109
PubMed Central
A double pressure probe technique was used to measure simultaneously water flows and hydraulic parameters of individual cells and of excised roots of young seedlings of maize (Zea mays L.) in osmotic experiments. By following initial flows of water at the cell and root level and by estimating the profiles of driving forces (water potentials) across the root, the hydraulic conductivity of individual cell layers was evaluated. Since the hydraulic conductivity of the cell-to-cell path was determined separately, the hydraulic conductivity of the cell wall material could be evaluated as well (Lpcw = 0.3 to 6.10?9 per meter per second per megapascal). Although, for radial water flow across the cortex and rhizodermis, the apoplasmic path was predominant, the contribution of the hydraulic conductance of the cell-to-cell path to the overall conductance increased significantly from the first layer of the cortex toward the inner layers from 2% to 23%. This change was mainly due to an increase of the hydraulic conductivity of the cell membranes which was Lp = 1.9.10?7 per meter per second per megapascal in the first layer and Lp = 14 to 9.10?7 per meter per second per megapascal in the inner layers of the cortex. The hydraulic conductivity of entire roots depended on whether hydrostatic or osmotic forces were used to induce water flows. Hydrostatic Lpr was 1.2 to 2.3.10?7 per meter per second per megapascal and osmotic Lpr = 1.6 to 2.8.10?8 per meter per second per megapascal. The apparent reflection coefficients of root cells (?s) of nonpermeating solutes (KCI, PEG 6000) decreased from values close to unity in the rhizodermis to about 0.7 to 0.8 in the cortex. In all cases, however, ?s was significantly larger than the reflection coefficient of entire roots (?sr). For KCI and PEG 6000, ?sr was 0.53 and 0.64, respectively. The results are discussed in terms of a composite membrane model of the root. PMID:16667970
Zhu, Guo Li; Steudle, Ernst
1991-01-01
110
PubMed
A new phytotoxicity test method based on root elongation of three Lemna species (Lemna gibba, L. minor, and L. paucicostata) has been developed. Tests with aquatic plants have, typically, favored measurements on fronds (e.g. frond number, area, biomass) rather than on roots, due, in part, to issues associated with handling fragile roots and the time-consuming procedures of selecting roots with identical root lengths. The present method differs in that roots were excised prior to exposure with subsequent measurements on newly developed roots. Results show that there were species-specific difference in sensitivity to the five metals tested (Ag, Cd, Cr, Cu and Hg), with Ag being the most toxic (EC50=5.3-37.6 ?gL(-1)) to all three species, and Cr the least toxic for L. gibba and L. minor (1148.3 and 341.8 ?gL(-1), respectively) and Cu for L. paucicostata (470.4 ?gL(-1)). Direct comparisons were made with measurements of frond area, which were found to be less sensitive. More generally, root re-growth was shown to reflect the toxic responses of all three Lemna species to these five important metals. The root growth bioassay differs from three internationally standardized methods (ISO, OCED and US EPA) in that it is completed in 48 h, the required volume of test solutions is only 3 ml and non-axenic plants are used. Our results show that the Lemna root method is a simple, rapid, cost-effective, sensitive and precise bioassay to assess the toxic risks of metals and has practical application for monitoring municipal and industrial waste waters where metals are common constituents. PMID:23917640
Park, Areum; Kim, Youn-Jung; Choi, Eun-Mi; Brown, Murray T; Han, Taejun
2013-09-15
111
USGS Publications Warehouse
The origin and evolution of cratonic roots has been debated for many years. Precambrian cratons are underlain by cold lithospheric roots that are chemically depleted. Thermal and petrologic data indicate that Archean roots are colder and more chemically depleted than Proterozoic roots. This observation has led to the hypothesis that the degree of depletion in a lithospheric root depends mostly on its age. Here we test this hypothesis using gravity, thermal, petrologic, and seismic data to quantify differences in the density of cratonic roots globally. In the first step in our analysis we use a global crustal model to remove the crustal contribution to the observed gravity. The result is the mantle gravity anomaly field, which varies over cratonic areas from -100 to +100 mGal. Positive mantle gravity anomalies are observed for cratons in the northern hemisphere: the Baltic shield, East European Platform, and the Siberian Platform. Negative anomalies are observed over cratons in the southern hemisphere: Western Australia, South America, the Indian shield, and Southern Africa. This indicates that there are significant differences in the density of cratonic roots, even for those of similar age. Root density depends on temperature and chemical depletion. In order to separate these effects we apply a lithospheric temperature correction using thermal estimates from a combination of geothermal modeling and global seismic tomography models. Gravity anomalies induced by temperature variations in the uppermost mantle range from -200 to +300 mGal, with the strongest negative anomalies associated with mid-ocean ridges and the strongest positive anomalies associated with cratons. After correcting for thermal effects, we obtain a map of density variations due to lithospheric compositional variations. These maps indicate that the average density decrease due to the chemical depletion within cratonic roots varies from 1.1% to 1.5%, assuming the chemical boundary layer has the same thickness as the thermal boundary layer. The maximal values of the density drop are in the range 1.7-2.5%, and correspond to the Archean portion of each craton. Temperatures within cratonic roots vary strongly, and our analysis indicates that density variations in the roots due to temperature are larger than the variations due to chemical differences. ?? 2003 Elsevier Science B.V. All rights reserved.
Kaban, M.K.; Schwintzer, P.; Artemieva, I.M.; Mooney, W.D.
2003-01-01
112
PubMed
Antiseptics used in endodontics for disinfection purposes include root canal dressings and irrigants. Osmotic shock is known to cause the alteration of microbial cell viability and might have a role in the mechanism of action of root canal antiseptics. The aim of this review was to determine the role of osmolarity on the performance of antiseptics in root canal treatment. A literature search using the Medline electronic database was conducted up to 30 May 2013 using the following search terms and combinations: 'osmolarity AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; osmolality AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; osmotic AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; osmosis AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; sodium chloride AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm'. Publications were included if the effects of osmolarity on the clinical performance of antiseptics in root canal treatment were stated, if preparations with different osmolarities values were compared and if they were published in English. A hand search of articles published online, 'in press' and 'early view', and in the reference list of the included papers was carried out following the same criteria. A total of 3274 publications were identified using the database, and three were included in the review. The evidence available in endodontics suggests a possible role for hyperosmotic root canal medicaments as disinfectants, and that there is no influence of osmolarity on the tissue dissolution capacity of sodium hypochlorite. There are insufficient data to obtain a sound conclusion regarding the role of hypo-osmosis in root canal disinfection, or osmosis in any further desirable ability. PMID:23889531
Rossi-Fedele, G; Guastalli, A R
2014-04-01
113
As plant roots take up water and the soil dries, water depletion is expected to occur in the rhizosphere. However, recent experiments showed that the rhizosphere of lupines was wetter than the bulk soil during root water uptake. On the other hand, after irrigation the rhizosphere remained markedly dry and it rewetted only after one-two days. We hypothesize that: 1) drying/wetting rates of the rhizosphere are controlled by mucilage exuded by roots; 2) mucilage alters the soil hydraulic conductivity: in particular, wet mucilage increases the soil hydraulic conductivity and dry mucilage makes the soil water repellent; 3) mucilage exudation favors root water uptake in dry soil; and 4) dry mucilage limits water loss from roots to dry soils. We used a root pressure probe to measure the hydraulic conductance of artificial roots sitting in soils. As an artificial root we employed a suction cup with a diameter of 2 mm and a length of 45 mm. The root pressure probe gave the hydraulic conductance of the soil-root continuum during pulse experiments in which water was injected into or sucked from the soil. First, we performed experiments with roots in a relatively dry soil with a volumetric water content of 0.03. Then, we repeated the experiment with artificial roots covered with mucilage and then placed into the soil. As a model for mucilage, we collected mucilage from Chia seeds. The water contents (including that of mucilage) in the experiments with and without mucilage were equal. The pressure curves were fitted with a model of root water that includes rhizosphere dynamics. We found that the artificial roots covered with wet mucilage took up water more easily. In a second experimental set-up we measured the outflow of water from the artificial roots into dry soils. We compared two soils: 1) a sandy soil and 2) the same soil wetted with mucilage from Chia seeds and then let dry. The latter soil became water repellent. Due to the water repellency, the outflow of water from the root in this soil was significantly reduced. The experiments demonstrated that mucilage increased the hydraulic conductance of the root-soil continuum and facilitated the extraction of water from dry soils. The increase in conductivity resulted from the higher water content of the soil near the roots. Mucilage has a lower surface tension than pure water and a higher viscosity, resulting in a slower penetration of mucilage into the soil. After mucilage was placed into the soil, it did not spread into the bulk soil, but it remained near the roots, maintaining the rhizosphere wetter and more conductive than the bulk soil. However, as mucilage dried, it turned water repellent and reduced the back flow of water from the root to soil. We hypothesize that mucilage exudation is a plant strategy to locally and temporally facilitate water uptake from dry soils. After drying, mucilage becomes water repellent and may limit the local uptake of water after irrigation. On the other hand, mucilage water repellency may as well be a strategy to reduce water loss from roots to dry soils.
Ahmed, Mutez; Kroener, Eva; Holz, Maire; Zarebanadkouki, Mohsen; Carminati, Andrea
2014-05-01
114
NSDL National Science Digital Library
No, your students will not be drinking green root beer for St. Patrick's Day--this "green" root beer laboratory promotes environmental awareness in the science classroom, and provides a venue for some very sound science content! While many science classroo
Wandersee, James; Clary, Renee
2010-02-01
115
ERIC Educational Resources Information Center
Theon's ladder is an ancient algorithm for calculating rational approximations for the square root of 2. It features two columns of integers (called a ladder), in which the ratio of the two numbers in each row is an approximation to the square root of 2. It is remarkable for its simplicity. This algorithm can easily be generalized to find rational…
Osler, Thomas J.; Wright, Marcus; Orchard, Michael
2005-01-01
116
PubMed Central
Animal guts and plant roots have absorption roles for nutrient uptake and converge in harboring large, complex, and dynamic groups of microbes that participate in degradation or modification of nutrients and other substances. Gut and root bacteria regulate host gene expression, provide metabolic capabilities, essential nutrients, and protection against pathogens, and seem to share evolutionary trends. PMID:23104406
Ramirez-Puebla, Shamayim T.; Servin-Garciduenas, Luis E.; Jimenez-Marin, Berenice; Bolanos, Luis M.; Rosenblueth, Monica; Martinez, Julio; Rogel, Marco Antonio; Ormeno-Orrillo, Ernesto
2013-01-01
117
ERIC Educational Resources Information Center
Methods of investigating plant root growth developed for research purposes can be adopted for student use. Investigations of the effect of water table level and of ethylene concentration are described, and techniques of measuring root growth are explained. (Author/ML)
Devonald, V. G.
1986-01-01
118
PubMed Central
Background and Aims Cereals have two root systems. The primary system originates from the embryo when the seed germinates and can support the plant until it produces grain. The nodal system can emerge from stem nodes throughout the plant's life; its value for yield is unclear and depends on the environment. The aim of this study was to test the role of nodal roots of sorghum and millet in plant growth in response to variation in soil moisture. Sorghum and millet were chosen as both are adapted to dry conditions. Methods Sorghum and millet were grown in a split-pot system that allowed the primary and nodal roots to be watered separately. Key Results When primary and nodal roots were watered (12 % soil water content; SWC), millet nodal roots were seven times longer than those of sorghum and six times longer than millet plants in dry treatments, mainly from an 8-fold increase in branch root length. When soil was allowed to dry in both compartments, millet nodal roots responded and grew 20 % longer branch roots than in the well-watered control. Sorghum nodal roots were unchanged. When only primary roots received water, nodal roots of both species emerged and elongated into extremely dry soil (0·6–1·5 % SWC), possibly with phloem-delivered water from the primary roots in the moist inner pot. Nodal roots were thick, short, branchless and vertical, indicating a tropism that was more pronounced in millet. Total nodal root length increased in both species when the dry soil was covered with plastic, suggesting that stubble retention or leaf mulching could facilitate nodal roots reaching deeper moist layers in dry climates. Greater nodal root length in millet than in sorghum was associated with increased shoot biomass, water uptake and water use efficiency (shoot mass per water). Millet had a more plastic response than sorghum to moisture around the nodal roots due to (1) faster growth and progression through ontogeny for earlier nodal root branch length and (2) partitioning to nodal root length from primary roots, independent of shoot size. Conclusions Nodal and primary roots have distinct responses to soil moisture that depend on species. They can be selected independently in a breeding programme to shape root architecture. A rapid rate of plant development and enhanced responsiveness to local moisture may be traits that favour nodal roots and water use efficiency at no cost to shoot growth. PMID:23749473
Rostamza, M.; Richards, R. A.; Watt, M.
2013-01-01
119
Vetiver roots have a tufted vertically growing root structure. The roots are one of the most important organizational systems that make vetiver a miracle grass for its multifarious applications in soil and water conservation, soil health, and raw material for vetiver root handicrafts, environmental and perfumery products. A lot of diversity is found in vetiver root system in nature, and
Seshu Lavania
120
Detailed three-dimensional models of root water uptake have become increasingly popular for investigating the process of root water uptake. However they suffer from a lack of information in important parameters, especially distribution of root hydraulic properties. In this paper we explore the role that arrangement of root hydraulic properties and root system topology play for modelled uptake dynamics. We apply microscopic models of single root structures to investigate the mechanisms shaping uptake dynamics and demonstrate the effects in a complex three dimensional root water uptake model. We introduce two efficiency indices, for (a) overall plant resistance and (b) water stress and show that an appropriate arrangement of root hydraulic properties can increase modelled efficiency of root water uptake in single roots, branched roots and entire root systems. The average uptake depth of the complete root system was not influenced by parameterization. However, other factors such as evolution of collar potential, which is related to the plant resistance, root bleeding and redistribution patterns were strongly affected by the parameterization. Root systems are more efficient when they are assembled of different root types, allowing for separation of root function in uptake (short young) roots and transport (longer mature) roots. Results become similar, as soon as this composition is accounted for to some degree (between 40 and 80% of young uptake roots). Overall resistance to root water uptake was decreased up to 40% and total transpiration was increased up to 25% in these composed root systems, compared to homogenous root systems. Also, one parameterization (homogenous young root system) was characterized by excessive bleeding (hydraulic lift), which was accompanied by lowest efficiency. We conclude that heterogeneity of root hydraulic properties is a critical component of complex three dimensional uptake models. Efficiency measures together with information on critical xylem potentials may be useful in parameterizing root property distribution.
Bechmann, M.; Schneider, C.; Carminati, A.; Vetterlein, D.; Attinger, S.; Hildebrandt, A.
2014-01-01
121
The mode of gravisensing in higher plants is not yet elucidated. Although, it is generally accepted that the amyloplasts (statoliths) in the root cap cells (statocytes) are responsible for susception of gravity. However, the hypothesis that the whole protoplast acts as gravisusceptor cannot be dismissed. The nature of the sensor that is able to transduce and amplify the mechanical energy into a biochemical factor is even more controversial. Several cell structures could potentially serve as gravireceptors: the endoplasmic reticulum, the actin network, the plasma membrane, or the cytoskeleton associated with this membrane. The nature of the gravisusceptors and gravisensors is discussed by taking into account the characteristics of the gravitropic reaction with respect to the presentation time, the threshold acceleration, the reciprocity rule, the deviation from the sine rule, the movement of the amyloplasts, the pre-inversion effect, the response of starch free and intermediate mutants and the effects of cytochalasin treatment. From this analysis, it can be concluded that both the amyloplasts and the protoplast could be the gravisusceptors, the former being more efficient than the latter since they can focus pressure on limited areas. The receptor should be located in the plasma membrane and could be a stretch-activated ion channel.
Perbal, G.
1999-01-01
122
Plants forage for nutrients by increasing their root length density (RLD) in nutrient-rich soil microsites through root morphological changes resulting in increased root biomass density (RBD), specific root length (SRL), or branching frequency (BF). It is commonly accepted that fast-growing species will forage more than slow-growing species. However, foraging responses may be due solely to differences in relative growth rates
Zachary T. Aanderud; Caroline S. Bledsoe; James H. Richards
2003-01-01
123
Immobile higher plants are oriented in the gravitational field due to gravitropim that is a physiological growth reaction and consists of three phases: reception of a gravitational signal by statocytes, its transduction to the elongation zone, and finally the organ bending. As it is known, roots are characterized with positive gravitropism, i. e. they grow in the direction of a gravitational vector, stems - with negative gravitropism, i. e. they grow in the direction opposite to a gravitational vector. According to the Nemec’s and Haberlandt’s starch-statolith hypothesis, amyloplasts in diameter of 1.5 - 3 ? in average, which appear to act as gravity sensors and fulfill a statolythic function in the specialized graviperceptive cells - statocytes, sediment in the direction of a gravitational vector in the distal part of a cell, while a nucleus is in the proximal one. There are reasonable data that confirm the amyloplasts-statoliths participation in gravity perception: 1) correlation between the statoliths localization and the site of gravity sensing, 2) significant redistribution (sedimentation) of amyloplasts in statocytes under gravistimulation in comparison with other cell organelles, 3) root decreased ability to react on gravity under starch removal from amyloplasts, 4) starchless Arabidopsis thaliana mutants are agravitropic, 5) amyloplasts-statoliths do not sediment in the absence of the gravitational vector and are in different parts or more concentrated in the center of statocytes. Plant tropisms have been intensively studied for many decades and continue to be investigated. Nevertheless, the mechanisms by which plants do so is still not clearly explained and many questions on gravisensing and graviresponse remain unanswered. Even accepted hypotheses are now being questioned and recent data are critically evaluated. Although the available data show the Ca2+ and cytoskeleton participation in graviperception and signal transduction, the clear evidence with regard to the participation of calcium ions and cytoskeletal elements in these processes is therefore substantial but still circumstantial and requires new experimental data. Using a new model - weak combined magnetic fields (CMFs), which elicit a variety of responses in plants, growth rate and fresh weight, seed germination, Ca2+ concentration, membrane permeability, with a frequency resonance to cyclotron frequency of calcium ions, we firstly showed that a root positive gravitropic reaction changes on a negative one. In this case, the paradoxical displacement of amylopasts-statoliths to the upper longitudinal cell wall of statocytes occurred in the direction opposite to a gravitational vector. Displacement of amyloplasts, which contain the abundance of free Ca2+ in the stroma, was accompanied with Ca2+ redistribution in the same direction in the cytosol and increasing around amyloplasts in comparison with the state magnetic field. In the elongation zone, calcium ions accumulated in the upper site of a gravistimulated root unlike a positive gravitropic reaction, and a root is bending in the same direction in which amyloplasts are displacing. It seems that a root gravitropic reaction, if it began, occurs by an usual physiological way resulting in root bending with an opposite sign. It is of a special interest that a root is bending to the same direction with displacing of amyloplasts: in positive gravitropism - downwards, in negative gravitropism - upwards. Peculiarities of calcium ion redistribution in statocytes under gravistimulation in such combined magnetic field are a new additional evidence of a Ca2+ ion significant role in gravitropism. Thus, our data support the starch-statolith hypothesis but also pose the question as to which forces displace amyloplasts against the gravity vector? We hope that these data will stimulate new research to better understand the mechanisms of plant graviperception and graviresponse. Gravistimulation of a root in the CMF with the frequency resonance to the cyclotron frequency of Ca2+ ions is an effective model for future
Kordyum, Elizabeth
124
The microstructural evolution between Sn-3Ag-0.5Cu (SAC305) solder and Ni(P)/Pd(P)/Au finish during the reflow process was investigated for various Pd(P) thicknesses (0 ?m to 0.6 ?m). The reflow process was carried out in a belt-conveying reflow oven with peak temperature of 260°C. In the early stages of the reflow process, the Pd(P) layer either dissolved or spalled in the form of (Pd,Ni)Sn4 into the molten solder, leaving behind an Ni2SnP/Ni3P bilayer on the Ni(P) layer. From the dissolution of the spalled (Pd,Ni)Sn4 particles during the reflow process, the solubility of Pd in the molten SAC305 solder in the reflow process was estimated to be 0.18 wt.% to 0.25 wt.%. Regardless of the ratio of solder volume to pad opening size, the Ni2SnP layer that formed in the early stage of reflow had a significant influence on the subsequent formation and growth of (Cu,Ni)6Sn5 at the solder interface. As the Ni2SnP layer became thicker with increasing Pd(P) thickness, the formation of (Cu,Ni)6Sn5 became increasingly sluggish and occurred only at locations where the Ni2SnP layer was locally thin or discontinuous, leading to a discontinuous morphology of (Cu,Ni)6Sn5. This was attributed to the Ni2SnP layer that became an increasingly effective barrier to Ni diffusion with increasing thickness. Based on the experimental results, this study suggests detailed mechanisms underlying the effects of the Pd(P) thickness on the morphology and growth of the (Cu,Ni)6Sn5 formed during the reflow process.
Chung, Bo-Mook; Baek, Yong-Ho; Choi, Jaeho; Huh, Joo-Youl
2012-12-01
125
PubMed Central
Wound-induced adventitious root (AR) formation is a requirement for plant survival upon root damage inflicted by pathogen attack, but also during the regeneration of plant stem cuttings for clonal propagation of elite plant varieties. Yet, adventitious rooting also takes place without wounding. This happens for example in etiolated Arabidopsis thaliana hypocotyls, in which AR initiate upon de-etiolation or in tomato seedlings, in which AR initiate upon flooding or high water availability. In the hypocotyl AR originate from a cell layer reminiscent to the pericycle in the primary root (PR) and the initiated AR share histological and developmental characteristics with lateral roots (LRs). In contrast to the PR however, the hypocotyl is a determinate structure with an established final number of cells. This points to differences between the induction of hypocotyl AR and LR on the PR, as the latter grows indeterminately. The induction of AR on the hypocotyl takes place in environmental conditions that differ from those that control LR formation. Hence, AR formation depends on differentially regulated gene products. Similarly to AR induction in stem cuttings, the capacity to induce hypocotyl AR is genotype-dependent and the plant growth regulator auxin is a key regulator controlling the rooting response. The hormones cytokinins, ethylene, jasmonic acid, and strigolactones in general reduce the root-inducing capacity. The involvement of this many regulators indicates that a tight control and fine-tuning of the initiation and emergence of AR exists. Recently, several genetic factors, specific to hypocotyl adventitious rooting in A. thaliana, have been uncovered. These factors reveal a dedicated signaling network that drives AR formation in the Arabidopsis hypocotyl. Here we provide an overview of the environmental and genetic factors controlling hypocotyl-born AR and we summarize how AR formation and the regulating factors of this organogenesis are distinct from LR induction. PMID:25324849
Verstraeten, Inge; Schotte, Sebastien; Geelen, Danny
2014-01-01
126
PubMed
Root hairs are a key trait for improving the acquisition of phosphorus (P) by plants. However, it is not known whether root hairs provide significant advantage for plant growth under combined soil stresses, particularly under conditions that are known to restrict root hair initiation or elongation (e.g. compacted or high-strength soils). To investigate this, the root growth and P uptake of root hair genotypes of barley, Hordeum vulgare L. (i.e. genotypes with and without root hairs), were assessed under combinations of P deficiency and high soil strength. Genotypes with root hairs were found to have an advantage for root penetration into high-strength layers relative to root hairless genotypes. In P-deficient soils, despite a 20% reduction in root hair length under high-strength conditions, genotypes with root hairs were also found to have an advantage for P uptake. However, in fertilized soils, root hairs conferred an advantage for P uptake in low-strength soil but not in high-strength soil. Improved root-soil contact, coupled with an increased supply of P to the root, may decrease the value of root hairs for P acquisition in high-strength, high-P soils. Nevertheless, this work demonstrates that root hairs are a valuable trait for plant growth and nutrient acquisition under combined soil stresses. Selecting plants with superior root hair traits is important for improving P uptake efficiency and hence the sustainability of agricultural systems. PMID:23861547
Haling, Rebecca E; Brown, Lawrie K; Bengough, A Glyn; Young, Iain M; Hallett, Paul D; White, Philip J; George, Timothy S
2013-09-01
127
Root diseases caused by root-rotting fungi and root-knot nematodes are a serious problem in tomato (Lycopersicon esculentum Mill.) production throughout the world. Due to constraints in use of synthetic pesticides, alternate methods for disease management including biocontrol and cultural practices are being sought out. The effect of rhizobia (Bradyrhizobium japonicum), Pseudomonas aeruginosa, a plant growth–promoting bacterium (PGPR), and mineral fertilizers
Gulnaz Parveen; Syed Ehteshamul-Haque; Viqar Sultana; Jehan Ara; Mohammad Athar
2008-01-01
128
NSDL National Science Digital Library
Overview: Herbicides must be absorbed into plants inorder to be effective. Plant roots and below ground shoots have fewbarriers to herbicide absorption; however, interactions with soilparticles and soil organic matter have significant impacts on theamount of herbicide available for plant absorption. Plant roots andbelow ground shoots (hypocotyls or coleoptiles) are lipophilic bynature and do not have thick, waxy cuticles like leaves. Lipophilic andhydrophilic herbicides reach the root surface by bulk transport in soilwater; however, there are a few examples of herbicides that reach theroot as a vapor or gas. Soil-applied herbicides can translocate to theshoot or remain in the root system. Soil-applied herbicides translocateto the shoot in the xylem and tend to accumulate in mature leaves thattranspire the most water. The lipophilic/hydrophilic nature of theherbicide will determine if the herbicide translocates to the shoot.Absorption and translocation of phloem-mobile herbicides will bediscussed in another lesson.
129
\\u000a Together, the relationship between the mechanical response of neural tissues and the related mechanisms of injury provide\\u000a a foundation for defining relevant thresholds for injury. The nerves and nerve roots are biologic structures with specific\\u000a and important functions, and whose response to mechanical loading can have immediate, long-lasting and widespread consequences.\\u000a In particular, when nerves or nerve roots are mechanically
Kristen J. Nicholson; Beth A. Winkelstein
130
PubMed
Transgenic tobacco roots offer a potential alternative to leaves for monoclonal antibody (MAb) production. A possible method for extraction of MAbs from roots is by homogenization, breaking the roots into fragments to release the antibody. This process was assessed by shearing 10?mm root sections ("roots") in a 24?mL ultra-scale down shearing device, including an impeller with serrated blade edges, intended to mimic the action of a large-scale homogenizer. Size distributions of the remaining intact roots and root fragments were obtained as a function of shearing time. The data suggest that about 36% of the roots could not be broken under the prevailing conditions and, beyond these unbreakable roots, the fragmentation was approximately first order with respect to intact root number. It was postulated that root breakage in such a high shearing device was due to root-impeller collisions and the particle size data suggest that roots colliding with the impeller were completely fragmented into debris particles of the order of 0.1?mm in length. IgG release normalized to release by grinding appeared to lag behind the number of roots that had fragmented, suggesting that a process of leakage followed fragmentation in the ultra-scale down shearing device. PMID:23860965
Hassan, Sally; Keshavarz-Moore, Eli; Ma, Julian; Thomas, Colin
2014-01-01
131
Research on gravity responses in plants has mostly focused on primary roots and shoots, which typically orient to a vertical orientation. However, the distribution of lateral organs and their characteristically non-vertical growth orientation are critical for the determination of plant form. For example, in Arabidopsis, when lateral roots emerge from the primary root, they grow at a nearly horizontal orientation. As they elongate, the roots slowly curve until they eventually reach a vertical orientation. The regulation of this lateral root orientation is an important component affecting overall root system architecture. We found that this change in orientation is not simply due to the onset of gravitropic competence, as non-vertical lateral roots are capable of both positive and negative gravitropism. Thus, the horizontal growth of new lateral roots appears to be determined by what is called the gravitropic set-point angle (GSA). This developmental control of the GSA of lateral roots in Arabidopsis provides a useful system for investigating the components involved in regulating gravitropic responses. Using this system, we have identified several Arabidopsis mutants that have altered lateral root orientations but maintain normal primary root orientation.
Mullen, J. L.; Hangarter, R. P.
2003-05-01
132
NASA Technical Reports Server (NTRS)
Research on gravity responses in plants has mostly focused on primary roots and shoots, which typically orient to a vertical orientation. However, the distribution of lateral organs and their characteristically non-vertical growth orientation are critical for the determination of plant form. For example, in Arabidopsis, when lateral roots emerge from the primary root, they grow at a nearly horizontal orientation. As they elongate, the roots slowly curve until they eventually reach a vertical orientation. The regulation of this lateral root orientation is an important component affecting overall root system architecture. We found that this change in orientation is not simply due to the onset of gravitropic competence, as non-vertical lateral roots are capable of both positive and negative gravitropism. Thus, the horizontal growth of new lateral roots appears to be determined by what is called the gravitropic set-point angle (GSA). This developmental control of the GSA of lateral roots in Arabidopsis provides a useful system for investigating the components involved in regulating gravitropic responses. Using this system, we have identified several Arabidopsis mutants that have altered lateral root orientations but maintain normal primary root orientation. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.
Mullen, J. L.; Hangarter, R. P.; Kiss, J. Z. (Principal Investigator)
2003-01-01
133
Detailed three-dimensional models of root water uptake have become increasingly popular for investigating the process of root water uptake. However, they suffer from a lack of information on important parameters, particularly on the spatial distribution of root axial and radial conductivities, which vary greatly along a root system. In this paper we explore how the arrangement of those root hydraulic properties and branching within the root system affects modelled uptake dynamics, xylem water potential and the efficiency of root water uptake. We first apply a simple model to illustrate the mechanisms at the scale of single roots. By using two efficiency indices based on (i) the collar xylem potential ("effort") and (ii) the integral amount of unstressed root water uptake ("water yield"), we show that an optimal root length emerges, depending on the ratio between roots axial and radial conductivity. Young roots with high capacity for radial uptake are only efficient when they are short. Branching, in combination with mature transport roots, enables soil exploration and substantially increases active young root length at low collar potentials. Second, we investigate how this shapes uptake dynamics at the plant scale using a comprehensive three-dimensional root water uptake model. Plant-scale dynamics, such as the average uptake depth of entire root systems, were only minimally influenced by the hydraulic parameterization. However, other factors such as hydraulic redistribution, collar potential, internal redistribution patterns and instantaneous uptake depth depended strongly on the arrangement on the arrangement of root hydraulic properties. Root systems were most efficient when assembled of different root types, allowing for separation of root function in uptake (numerous short apical young roots) and transport (longer mature roots). Modelling results became similar when this heterogeneity was accounted for to some degree (i.e. if the root systems contained between 40 and 80% of young uptake roots). The average collar potential was cut to half and unstressed transpiration increased by up to 25% in composed root systems, compared to homogenous ones. Also, the least efficient root system (homogenous young root system) was characterized by excessive bleeding (hydraulic lift), which seemed to be an artifact of the parameterization. We conclude that heterogeneity of root hydraulic properties is a critical component for efficient root systems that needs to be accounted for in complex three-dimensional root water uptake models.
Bechmann, M.; Schneider, C.; Carminati, A.; Vetterlein, D.; Attinger, S.; Hildebrandt, A.
2014-10-01
134
SciTech Connect
Ambient ozone concentrations have become problematic even in rural, agricultural areas such as the San Joaquin Valley of California. Pima cotton (cv. S6) has been shown to be relatively sensitive to ozone air pollution, at levels occurring in this production area. In this semi-arid area acquisition of water and nutrients may limit yield and biological productivity. Therefore maximal proliferation, exploration, and efficiency of root systems is desirable. Hydraulic conductance provides a parameter to characterize the efficiency of roots and shoots and their interaction. The authors have used a variety of transpiration and pressure vessel techniques to document ozone-induced reduction of root hydraulic conductance in cotton. They hypothesized that these effects are caused by reduced carbohydrate supply due to reduction of photosynthetic capacity of the shoot associated with direct oxidant damage to foliage. However, the authors simulated this reduced photosynthetic capacity by continuously removing leaf area to match that of ozone treated plants. This resulted in a reduction of whole plant biomass similar to ozone-treated plants, but a root/shoot biomass ratio and root hydraulic properties similar to control plants and contrasting with ozone-treated plants. Thus leaf removal did not simulate effects of ozone on root hydraulic properties. A systematic effect of ozone on whole plant function is indicated, perhaps mediated by direct effects on carbohydrate translocation throughout the plant.
Grantz, D.A.; Yang, S. [Univ. of California, Riverside, CA (United States); [Kearney Agricultural Center, Parlier, CA (United States)
1995-12-31
135
PubMed
Interactions among the foraging behaviours of co-occurring animal species can impact population and community dynamics; the consequences of interactions between plant and animal foraging behaviours have received less attention. In North American forests, invasions by European earthworms have led to substantial changes in plant community composition. Changes in leaf litter have been identified as a critical indirect mechanism driving earthworm impacts on plants. However, there has been limited examination of the direct effects of earthworm burrowing on plant growth. Here we show a novel second pathway exists, whereby earthworms (Lumbricus terrestris L.) impact plant root foraging. In a mini-rhizotron experiment, roots occurred more frequently in burrows and soil cracks than in the soil matrix. The roots of Achillea millefolium L. preferentially occupied earthworm burrows, where nutrient availability was presumably higher than in cracks due to earthworm excreta. In contrast, the roots of Campanula rotundifolia L. were less likely to occur in burrows. This shift in root behaviour was associated with a 30% decline in the overall biomass of C. rotundifolia when earthworms were present. Our results indicate earthworm impacts on plant foraging can occur indirectly via physical and chemical changes to the soil and directly via root consumption or abrasion and thus may be one factor influencing plant growth and community change following earthworm invasion. More generally, this work demonstrates the potential for interactions to occur between the foraging behaviours of plants and soil animals and emphasizes the importance of integrating behavioural understanding in foraging studies involving plants. PMID:25268503
Cameron, Erin K; Cahill, James F; Bayne, Erin M
2014-01-01
136
PubMed Central
Interactions among the foraging behaviours of co-occurring animal species can impact population and community dynamics; the consequences of interactions between plant and animal foraging behaviours have received less attention. In North American forests, invasions by European earthworms have led to substantial changes in plant community composition. Changes in leaf litter have been identified as a critical indirect mechanism driving earthworm impacts on plants. However, there has been limited examination of the direct effects of earthworm burrowing on plant growth. Here we show a novel second pathway exists, whereby earthworms (Lumbricus terrestris L.) impact plant root foraging. In a mini-rhizotron experiment, roots occurred more frequently in burrows and soil cracks than in the soil matrix. The roots of Achillea millefolium L. preferentially occupied earthworm burrows, where nutrient availability was presumably higher than in cracks due to earthworm excreta. In contrast, the roots of Campanula rotundifolia L. were less likely to occur in burrows. This shift in root behaviour was associated with a 30% decline in the overall biomass of C. rotundifolia when earthworms were present. Our results indicate earthworm impacts on plant foraging can occur indirectly via physical and chemical changes to the soil and directly via root consumption or abrasion and thus may be one factor influencing plant growth and community change following earthworm invasion. More generally, this work demonstrates the potential for interactions to occur between the foraging behaviours of plants and soil animals and emphasizes the importance of integrating behavioural understanding in foraging studies involving plants. PMID:25268503
Cameron, Erin K.; Cahill, James F.; Bayne, Erin M.
2014-01-01
137
E-print Network
This note gives an explicit formula for the elements of the E(8) root system. The formula is triacontagonally symmetric in that one may clearly see an action by the cyclic group with 30 elements. The existence of such a formula is due to the fact that the Coxeter number of E(8) is 30.
David A. Richter
2007-04-24
138
Abbreviations: CeX: the osmotic concentration of the xylem exudate (osmolm 3), Cex(px): CeX as a function of root pressure px (osmol m-3). ci: the osmotic concentration in the symplast (osmol m-3), Cs(x): the osmotic concentration of absorbable solute in the canal at x (osmolm-3), Cs(x, px): C~(x) as a function of root pressure (osmolm 3), C~V: the average of Cs(x)
Kiyoshi Katou; Takehide Taura; Muneyoshi Furumoto
1988-01-01
139
PubMed
Root knot (Meloidogyne spp.) and cyst (Heterodera and Globodera spp.) nematodes infect all important crop species, and the annual economic loss due to these pathogens exceeds $90 billion. We screened the worldwide accession collection with the root-knot nematodes Meloidogyne incognita, M. arenaria and M. hapla, soybean cyst nematode (SCN-Heterodera glycines), sugar beet cyst nematode (SBCN-Heterodera schachtii) and clover cyst nematode (CLCN-Heterodera trifolii), revealing resistant and susceptible accessions. In the over 100 accessions evaluated, we observed a range of responses to the root-knot nematode species, and a non-host response was observed for SCN and SBCN infection. However, variation was observed with respect to infection by CLCN. While many cultivars including Jemalong A17 were resistant to H. trifolii, cultivar Paraggio was highly susceptible. Identification of M. truncatula as a host for root-knot nematodes and H. trifolii and the differential host response to both RKN and CLCN provide the opportunity to genetically and molecularly characterize genes involved in plant-nematode interaction. Accession DZA045, obtained from an Algerian population, was resistant to all three root-knot nematode species and was used for further studies. The mechanism of resistance in DZA045 appears different from Mi-mediated root-knot nematode resistance in tomato. Temporal analysis of nematode infection showed that there is no difference in nematode penetration between the resistant and susceptible accessions, and no hypersensitive response was observed in the resistant accession even several days after infection. However, less than 5% of the nematode population completed the life cycle as females in the resistant accession. The remainder emigrated from the roots, developed as males, or died inside the roots as undeveloped larvae. Genetic analyses carried out by crossing DZA045 with a susceptible French accession, F83005, suggest that one gene controls resistance in DZA045. PMID:19259519 Dhandaydham, Murali; Charles, Lauren; Zhu, Hongyan; Starr, James L; Huguet, Thierry; Cook, Douglas R; Prosperi, Jean-Marie; Opperman, Charles 2008-03-01 140 Microsoft Academic Search Knowledge of root respiration is a prerequisite for a better understanding of ecosystem carbon budget and carbon allocation.\\u000a However, there are not many relevant data in the literature on direct measurements of in situ root respiration by root chamber\\u000a method. Furthermore, few studies have been focused on the effects of root diameter (D\\u000a r) and root nitrogen concentration (N\\u000a r) Dima Chen; Lixia Zhou; Xingquan Rao; Yongbiao Lin; Shenglei Fu 2010-01-01 141 Microsoft Academic Search Fine root processes play a prominent role in the carbon and nutrient cycling of boreal ecosystems due to the high proportion of biomass allocated belowground and the rapid decomposition of fine roots relative to aboveground tissues. To examine these issues in detail, major components of ecosystem carbon flux were studied in three mature black spruce forests in interior Alaska, where Roger W. Ruess; Ronald L. Hendrick; Andrew J. Burton; Kurt S. Pregitzer; Bjartmar Sveinbjornssön; Michael F. Allen; Gregory E. Maurer 2003-01-01 142 PubMed Central Complex root canal system with atypical variations is a common finding among mandibular premolars. Endodontic treatment in these teeth may not be successful due to the failure to recognise and treat multiple canals. This paper presents endodontic treatment of a mandibular second premolar with three roots and three canals. Paul, Bonny; Dube, Kavita 2014-01-01 143 Microsoft Academic Search Since the late 1990s, the grass-roots sporting workforce in England has been subjected to increasing policy intervention, primarily due to Government desire to use the private and voluntary sector to deliver a range of political objectives. English grass-roots football is arguably the most important site for this policy delivery given its huge popularity – providing the largest numbers of volunteers Jim Lusted; Jimmy OGorman 2010-01-01 144 E-print Network thought due to the pre- sence of an "alkali" in the soil, but its continued growth on the same land, showing widening circles of disease with each succeeding year, mould indicate at once a fungus trouble. Mr. W. H. Farley, whose lettera we select... shov that fungus must attack the healthy plants for some time before there are any visible signs ofdisease and for an area much larger than the small circle seemingly affected-or that the disease is not at all checked by plowing. As a matter of fact... Curtis, Geo. W. 1892-01-01 145 Microsoft Academic Search Root plasticity has been largely studied on herbaceous species of north European temperate flora and is defined as the ratio between root depth in dry soils and root depth in wet soils. In summer dry habitats such as Mediterranean environments, the soil water deficit is a common feature to which root systems of plant species should adapt to improve their M. De Lillis; F. Manes; F. Tufaro 2005-01-01 146 Microsoft Academic Search This work tests the ability of the bacterium hairy-root (Agrobacterium rhizogenes) to induce the formation of adventitious roots on Pacific mad- rone (Arbutus menziesii) stems and cuttings. Madrone stems 6, 9, 12 and 18 months of age are innoculated at different seasons of the year and tested for the production of adventitious roots. Successful rooting of stems with endogenously produced Barbara Selemon; Toby Bradshaw 147 PubMed Central Background The Arabidopsis thaliana gene SPATULA (SPT), encoding a bHLH transcription factor, was originally identified for its role in pistil development. SPT is necessary for the growth and development of all carpel margin tissues including the style, stigma, septum and transmitting tract. Since then, it has been shown to have pleiotropic roles during development, including restricting the meristematic region of the leaf primordia and cotyledon expansion. Although SPT is expressed in roots, its role in this organ has not been investigated. Results An analysis of embryo and root development showed that loss of SPT function causes an increase in quiescent center size in both the embryonic and postembryonic stem cell niches. In addition, root meristem size is larger due to increased division, which leads to a longer primary root. spt mutants exhibit other pleiotropic developmental phenotypes, including more flowers, shorter internodes and an extended flowering period. Genetic and molecular analysis suggests that SPT regulates cell proliferation in parallel to gibberellic acid as well as affecting auxin accumulation or transport. Conclusions Our data suggest that SPT functions in growth control throughout sporophytic growth of Arabidopsis, but is not necessary for cell fate decisions except during carpel development. SPT functions independently of gibberellic acid during root development, but may play a role in regulating auxin transport or accumulation. Our data suggests that SPT plays a role in control of root growth, similar to its roles in above ground tissues. PMID:23280064 2013-01-01 148 PubMed To prevent acid mine drainage arising from oxygen and water penetration of sulphide-rich mine tailings, the tailings are covered with layers of dry sealing material. Plant roots have a great ability to penetrate dense materials, and if the roots are able to penetrate the sealing layer of a tailings deposit, its oxygen-shielding properties could be reduced. The objective of this study was to evaluate whether plant roots are able to penetrate sealing layers covering mine tailings deposits. Root penetration into layers of various sealing materials, such as clayey moraine (clay, 8-10%; silt, 22-37%; sand, 37-55%; gravel, 15-18%), moraine (unspecified), 6-mm bentonite (kaolin clay) fabric, lime and clay, Cefyll (mixture of pulverized coal fly ash, cement and water) and a mixture containing biosludge (30-35%) and bioashes (65-70%), was investigated. In the field, roots were studied by digging trenches alongside vegetation growing in 3- and 10-year-old mine sites. In the greenhouse root growth of Betula pendula, Pinus sylvestris, Poa pratensis and Salix viminalis were studied in compartments where the plants had been growing for 22 months. The results from the field experiment indicated that roots are able to penetrate both deep down in the cover layer (1.7 m) and also into the sealing layers of various materials, and even to penetrate hard Cefyll. The addition of nutrients in the top cover reduced deep root growth and thereby also penetration through the sealing layer. Low hydraulic conductivity of the sealing layer or a thick cover layer had less effect on root penetration. In the greenhouse experiment roots did not penetrate the thin bentonite fabric, due to low pH (2.1-2.7) that was created from the underlying weathered mine tailings. The clayey moraine was penetrated by all species used in the greenhouse experiment; Pinus sylvestris had the greatest ability to penetrate. To prevent root penetration of the other sealing layer, a suitable condition for the plants should be created in the upper part of the cover layer, namely a sufficient amount of plant nutrients. However, to define such a condition is difficult since different plant species have different requirements. PMID:17253002 Stoltz, Eva; Greger, Maria 2006-12-01 149 PubMed > Abstract To determine if spatial variation in soluble carbon sources along the root coincides with different trophic groups of bacteria, copiotrophic and oligotrophic bacteria were enumerated from bulk soil and rhizosphere samples at 2 cm intervals along wheat roots 2, 3, and 4 weeks after planting. There was a moderate rhizosphere effect in one experiment with soil rich in fresh plant debris, and a very pronounced rhizosphere effect in the second experiment with soil low in organic matter. We obtained wavelike patterns of both trophic groups of bacteria as well as water-soluble total organic carbon (TOC) along the whole root length (60 or 90 cm). TOC concentrations were maximal at the root tip and base and minimal in the middle part of the roots. Oscillations in populations of copiotrophic and oligotrophic bacteria had two maxima close to the root tip and at the root base, or three maxima close to the tip, in the middle section, and at the root base. The location and pattern of the waves in bacterial populations changed progressively from week to week and was not consistently correlated with TOC concentrations or the location of lateral root formation. Thus, the traditional view that patterns in bacterial numbers along the root directly reflect patterns in exudation and rhizodeposition from several fixed sources along the root may not be true. We attributed the observed wavelike patterns in bacterial populations to bacterial growth and death cycles (due to autolysis or grazing by predators). Considering the root tip as a moving nutrient source, temporal oscillations in bacterial populations at any location where the root tip passed would result in moving waves along the root. This change in concept about bacterial populations in the rhizosphere could have significant implications for plant growth promotion and bioremediation. PMID:9929400 Semenov; van Bruggen AHC; Zelenev 1999-02-01 150 PubMed Central • Background Maize (Zea mays) forms a complex root system comprising embryonic and post?embryonic roots. The embryonically formed root system is made up of the primary root and a variable number of seminal roots. Later in development the post?embryonic shoot?borne root system becomes dominant and is responsible together with its lateral roots for the major portion of water and nutrient uptake. Although the anatomical structure of the different root?types is very similar they are initiated from different tissues during embryonic and post?embryonic development. Recently, a number of mutants specifically affected in maize root development have been identified. These mutants indicate that various root?type specific developmental programmes are involved in the establishment of the maize root stock. • Scope This review summarizes these genetic data in the context of the maize root morphology and anatomy and gives an outlook on possible perspectives of the molecular analysis of maize root formation. PMID:14980975 HOCHHOLDINGER, FRANK; WOLL, KATRIN; SAUER, MICHAELA; DEMBINSKY, DIANA 2004-01-01 151 SciTech Connect In this talk the authors review the major additions and improvements made to the ROOT system in the last 18 months and present their plans for future developments. The additions and improvements range from modifications to the I/O sub-system to allow users to save and restore objects of classes that have not been instrumented by special ROOT macros, to the addition of a geometry package designed for building, browsing, tracking and visualizing detector geometries. Other improvements include enhancements to the quick analysis sub-system (TTree::Draw()), the addition of classes that allow inter-file object references (TRef, TRefArray), better support for templates and STL classes, amelioration of the Automatic Script Compiler and the incorporation of new fitting and mathematical tools. Efforts have also been made to increase the modularity of the ROOT system with the introduction of more abstract interfaces and the development of a plug-in manager. In the near future, they intend to continue the development of PROOF and its interfacing with GRID environments. They plan on providing an interface between Geant3, Geant4 and Fluka and the new geometry package. The ROOT-GUI classes will finally be available on Windows and they plan to release a GUI inspector and builder. In the last year, ROOT has drawn the endorsement of additional experiments and institutions. It is now officially supported by CERN and used as key I/O component by the LCG project. Rene Brun et al. 2003-10-01 152 PubMed Arbuscular mycorrhizal fungi (AMF) play important roles as plant protection agents, reducing or suppressing nematode colonization. However, it has never been investigated whether the galls produced in roots by nematode infection are colonized by AMF. This study tested whether galls produced by Meloidogyne incognita infection in Prunus persica roots are colonized by AMF. We also determined the changes in AMF composition and biodiversity mediated by infection with this root-knot nematode. DNA from galls and roots of plants infected by M. incognita and from roots of noninfected plants was extracted, amplified, cloned, and sequenced using AMF-specific primers. Phylogenetic analysis using the small-subunit (SSU) ribosomal DNA (rDNA) data set revealed 22 different AMF sequence types (17 Glomus sequence types, 3 Paraglomus sequence types, 1 Scutellospora sequence type, and 1 Acaulospora sequence type). The highest AMF diversity was found in uninfected roots, followed by infected roots and galls. This study indicates that the galls produced in P. persica roots due to infection with M. incognita were colonized extensively by a community of AMF, belonging to the families Paraglomeraceae and Glomeraceae, that was different from the community detected in roots. Although the function of the AMF in the galls is still unknown, we hypothesize that they act as protection agents against opportunistic pathogens. PMID:21984233 Alguacil, Maria del Mar; Torrecillas, Emma; Lozano, Zenaida; Roldán, Antonio 2011-12-01 153 PubMed Central In terrestrial ecosystems, plant roots are colonized by various clades of mycorrhizal and endophytic fungi. Focused on the root systems of an oak-dominated temperate forest in Japan, we used 454 pyrosequencing to explore how phylogenetically diverse fungi constitute an ecological community of multiple ecotypes. In total, 345 operational taxonomic units (OTUs) of fungi were found from 159 terminal-root samples from 12 plant species occurring in the forest. Due to the dominance of an oak species (Quercus serrata), diverse ectomycorrhizal clades such as Russula, Lactarius, Cortinarius, Tomentella, Amanita, Boletus, and Cenococcum were observed. Unexpectedly, the root-associated fungal community was dominated by root-endophytic ascomycetes in Helotiales, Chaetothyriales, and Rhytismatales. Overall, 55.3% of root samples were colonized by both the commonly observed ascomycetes and ectomycorrhizal fungi; 75.0% of the root samples of the dominant Q. serrata were so cocolonized. Overall, this study revealed that root-associated fungal communities of oak-dominated temperate forests were dominated not only by ectomycorrhizal fungi but also by diverse root endophytes and that potential ecological interactions between the two ecotypes may be important to understand the complex assembly processes of belowground fungal communities. PMID:23762515 Toju, Hirokazu; Yamamoto, Satoshi; Sato, Hirotoshi; Tanabe, Akifumi S; Gilbert, Gregory S; Kadowaki, Kohmei 2013-01-01 154 PubMed Previous studies suggest that younger roots are more vulnerable to mortality than older roots. We analyzed minirhizotron data using a mixed-age, proportional hazards regression approach to determine whether the risk of mortality (or "hazard") was higher for younger roots than for older roots in a West Virginia peach orchard. While root age apparently had a strong effect on the hazard when considered alone, this effect was largely due to different rates of mortality among roots of different orders, diameters, and depths. Roots with dependent laterals (higher order roots) had a lower hazard than first-order roots in 1996 and 1997. Greater root diameter was also associated with a decreased hazard in both 1996 and 1997. In both years, there was a significant decrease in the hazard with depth. When considered alone, age appeared to be a strong predictor of risk: a 1-d increase in initial root age was associated with a 1.26-2.62% decrease in the hazard. However, when diameter, order, and depth were incorporated into the model, the effect of root age disappeared or was greatly reduced. Baseline hazard function plots revealed that the timing of high-risk periods was generally related to seasonal factors rather than individual root age. PMID:21669714 Wells, Christina E; Glenn, D Michael; Eissenstat, David M 2002-01-01 155 NASA Astrophysics Data System (ADS) We present parallel algorithms with optimal cache complexity for the kernel routine of many real root isolation algorithms, namely the Taylor shift by 1. We then report on multicore implementation for isolating the real roots of univariate polynomials with integer coefficients based on a classical algorithm due to Vincent, Collins and Akritas. For processing some well-known benchmark examples with sufficiently large size, our software tool reaches linear speedup on an 8-core machine. In addition, we show that our software is able to fully utilize the many cores and the memory space of a 32-core machine to tackle large problems that are out of reach for a desktop implementation. Chen, Changbo; Moreno Maza, Marc; Xie, Yuzhen 2012-02-01 156 PubMed This Article begins in Part I with a doctrinal evaluation of the status of Washington v. Glucksberg ten years after that decision was handed down. Discussion begins with consideration of the Roberts Court's recent decision in Gonzales v. Carhart and then turns to the subject of Justice Kennedy's views in particular on substantive due process. In Part II, the Article goes on to consider whether the Glucksberg test for substantive due process decision making is correct in light of the original meaning of the Fourteenth Amendment. The Article concludes in Parts II and III that Glucksberg is right to confine substantive due process rights recognition to recognition only of those rights that are deeply rooted in history and tradition. PMID:18595213 Calabresi, Steven G 2008-06-01 157 PubMed Active polar transport establishes directional auxin flow and the generation of local auxin gradients implicated in plant responses and development. Auxin modulates gravitropism at the root tip and root hair morphogenesis at the differentiation zone. Genetic and biochemical analyses provide evidence for defective basipetal auxin transport in trh1 roots. The trh1, pin2, axr2 and aux1 mutants, and transgenic plants overexpressing PIN1, all showing impaired gravity response and root hair development, revealed ectopic PIN1 localization. The auxin antagonist hypaphorine blocked root hair elongation and caused moderate agravitropic root growth, also leading to PIN1 mislocalization. These results suggest that auxin imbalance leads to proximal and distal developmental defects in Arabidopsis root apex, associated with agravitropic root growth and root hair phenotype, respectively, providing evidence that these two auxin-regulated processes are coupled. Cell-specific subcellular localization of TRH1-YFP in stele and epidermis supports TRH1 engagement in auxin transport, and hence impaired function in trh1 causes dual defects of auxin imbalance. The interplay between intrinsic cues determining root epidermal cell fate through the TTG/GL2 pathway and environmental cues including abiotic stresses modulates root hair morphogenesis. As a consequence of auxin imbalance in Arabidopsis root apex, ectopic PIN1 mislocalization could be a risk aversion mechanism to trigger root developmental responses ensuring root growth plasticity. PMID:23252740 Rigas, Stamatis; Ditengou, Franck Anicet; Ljung, Karin; Daras, Gerasimos; Tietz, Olaf; Palme, Klaus; Hatzopoulos, Polydefkis 2013-03-01 158 NASA Astrophysics Data System (ADS) Understanding the mechanisms of ecosystem root water uptake (RWU) is paramount for parameterizing hydrological models. With the increase in computational power it is possible to calculate RWU explicitly up to the single plant scale using physical models. However, application of these models for increasing our understanding of ecosystem root water uptake is hindered by the deficit in knowledge about the detailed hydraulic parameter distribution within root systems. However, those physical models may help us to identify efficient parameterizations and to describe the influence of these hydraulic parameters on RWU profiles. In this research, we investigated the combined influence of root hydraulic parameters and different root topologies on shaping efficient root water uptake. First, we use a conceptual model of simple branching structures to understand the influence of branching location and transitions in root hydraulic properties on the RWU patterns in typical sub root structures. Second, we apply a physical model called "aRoot" to test our conclusions on complex root system architectures of single plants. aRoot calculates the distribution of xylem potential within arbitrary root geometries to satisfy a given water demand depending on the available water in the soil. Redistribution of water within the bulk soil is calculated using the Richards equation. We analyzed results using a measure of uptake efficiency, which describes the effort necessary for transpiration. Simulations with the conceptual model showed that total transpiration in sub root structures is independent of root hydraulic properties over a wide range of hydraulic parameters. On the other hand efficiency of root water uptake depends crucially on distribution hydraulic parameters in line with root topology. At the same time, these parameters shape strongly the distribution of RWU along the roots, and its evolution in time, thus leading to variable individual root water uptake profiles. Calculating RWU of three dimensional root architectures unveiled that the same effects can be observed at the single plant scale. Total transpiration is almost independent of root hydraulic properties. On the other hand, the arrangement of hydraulic properties significantly influences RWU efficiency. Furthermore the vertical root water uptake profiles are governed by the different root properties. They result from two combined re-distribution patterns over time: One within a rooting branch similar to the results mentioned above, and a second one between the different rooting branches within the root system. This leads to complex vertical uptake profiles, which cannot be predicted from a combination of root abundance and soil moisture, and depend strongly on the individual morphology. Bechmann, Marcel; Schneider, Christoph; Carminati, Andrea; Hildebrandt, Anke 2013-04-01 159 PubMed Central Rooting phylogenies is critical for understanding evolution, yet the importance, intricacies and difficulties of rooting are often overlooked. For rooting, polymorphic characters among the group of interest (ingroup) must be compared to those of a relative (outgroup) that diverged before the last common ancestor (LCA) of the ingroup. Problems arise if an outgroup does not exist, is unknown, or is so distant that few characters are shared, in which case duplicated genes originating before the LCA can be used as proxy outgroups to root diverse phylogenies. Here, we describe a genome-wide expansion of this technique that can be used to solve problems at the other end of the evolutionary scale: where ingroup individuals are all very closely related to each other, but the next closest relative is very distant. We used shared orthologous single nucleotide polymorphisms (SNPs) from 10 whole genome sequences of Coxiella burnetii, the causative agent of Q fever in humans, to create a robust, but unrooted phylogeny. To maximize the number of characters informative about the rooting, we searched entire genomes for polymorphic duplicated regions where orthologs of each paralog could be identified so that the paralogs could be used to root the tree. Recent radiations, such as those of emerging pathogens, often pose rooting challenges due to a lack of ingroup variation and large genomic differences with known outgroups. Using a phylogenomic approach, we created a robust, rooted phylogeny for C. burnetii. [Coxiella burnetii; paralog SNPs; pathogen evolution; phylogeny; recent radiation; root; rooting using duplicated genes.] PMID:23736103 Pearson, Talima; Hornstra, Heidie M.; Sahl, Jason W.; Schaack, Sarah; Schupp, James M.; Beckstrom-Sternberg, Stephen M.; O'Neill, Matthew W.; Priestley, Rachael A.; Champion, Mia D.; Beckstrom-Sternberg, James S.; Kersh, Gilbert J.; Samuel, James E.; Massung, Robert F.; Keim, Paul 2013-01-01 160 PubMed Central Roots play important roles in plant survival and productivity as they not only anchor the plants in the soil but are also the primary organ for the uptake of nutrients from the outside. The growth and development of roots depend on the specification and maintenance of the root meristem. Here, we report a previously unknown role of TIME FOR COFFEE (TIC) in controlling root meristem size in Arabidopsis. The results showed that loss of function of TIC reduced root meristem length and cell number by decreasing the competence of meristematic cells to divide. This was due to the repressed expression of PIN genes for decreased acropetal auxin transport in tic-2, leading to low auxin accumulation in the roots responsible for reduced root meristem, which was verified by exogenous application of indole-3-acetic acid. Downregulated expression of PLETHORA1 (PLT1) and PLT2, key transcription factors in mediating the patterning of the root stem cell niche, was also assayed in tic-2. Similar results were obtained with tic-2 and wild-type plants at either dawn or dusk. We also suggested that the MYC2-mediated jasmonic acid signalling pathway may not be involved in the regulation of TIC in controlling the root meristem. Taken together, these results suggest that TIC functions in an auxin–PLTs loop for maintenance of post-embryonic root meristem. PMID:24277277 Lu, Ying-Tang 2014-01-01 161 PubMed Rooting phylogenies is critical for understanding evolution, yet the importance, intricacies and difficulties of rooting are often overlooked. For rooting, polymorphic characters among the group of interest (ingroup) must be compared to those of a relative (outgroup) that diverged before the last common ancestor (LCA) of the ingroup. Problems arise if an outgroup does not exist, is unknown, or is so distant that few characters are shared, in which case duplicated genes originating before the LCA can be used as proxy outgroups to root diverse phylogenies. Here, we describe a genome-wide expansion of this technique that can be used to solve problems at the other end of the evolutionary scale: where ingroup individuals are all very closely related to each other, but the next closest relative is very distant. We used shared orthologous single nucleotide polymorphisms (SNPs) from 10 whole genome sequences of Coxiella burnetii, the causative agent of Q fever in humans, to create a robust, but unrooted phylogeny. To maximize the number of characters informative about the rooting, we searched entire genomes for polymorphic duplicated regions where orthologs of each paralog could be identified so that the paralogs could be used to root the tree. Recent radiations, such as those of emerging pathogens, often pose rooting challenges due to a lack of ingroup variation and large genomic differences with known outgroups. Using a phylogenomic approach, we created a robust, rooted phylogeny for C. burnetii. [Coxiella burnetii; paralog SNPs; pathogen evolution; phylogeny; recent radiation; root; rooting using duplicated genes.]. PMID:23736103 Pearson, Talima; Hornstra, Heidie M; Sahl, Jason W; Schaack, Sarah; Schupp, James M; Beckstrom-Sternberg, Stephen M; O'Neill, Matthew W; Priestley, Rachael A; Champion, Mia D; Beckstrom-Sternberg, James S; Kersh, Gilbert J; Samuel, James E; Massung, Robert F; Keim, Paul 2013-09-01 162 NASA Technical Reports Server (NTRS) The effect of ABA on root growth, secondary-root formation and root gravitropism in seedlings of Zea mays was investigated by using Fluridone-treated seedlings and a viviparous mutant, both of which lack carotenoids and ABA. Primary roots of seedlings grown in the presence of Fluridone grew significantly slower than those of control (i.e. untreated) roots. Elongation of Fluridone-treated roots was inhibited significantly by the exogenous application of 1 mM ABA. Exogenous application of 1 micromole and 1 nmole ABA had either no effect or only a slight stimulatory effect on root elongation, depending on the method of application. The absence of ABA in Fluridone-treated plants was not an important factor in secondary-root formation in seedlings less than 9-10 d old. However, ABA may suppress secondary-root formation in older seedlings, since 11-d-old control seedlings had significantly fewer secondary roots than Fluridone-treated seedlings. Roots of Fluridone-treated and control seedlings were graviresponsive. Similar data were obtained for vp-9 mutants of Z. mays, which are phenotypically identical to Fluridone-treated seedlings. These results indicate that ABA is necessary for neither secondary-root formation nor for positive gravitropism by primary roots. Ng, Y. K.; Moore, R. 1985-01-01 163 Microsoft Academic Search Analysis of the effects of soil management practices on crop production requires knowledge of these effects on plant roots.\\u000a Much time is required to wash plant roots from soil and separate the living plant roots from organic debris and previous years’\\u000a roots. We developed a root washer that can accommodate relatively large soil samples for washing. The root washer has J. G. Benjamin; D. C. Nielsen 2004-01-01 164 Microsoft Academic Search Sprays of 3000 ppm indole-3-butyric acid (IBA) and napthaleneacetic acid (NAA), applied to freshly cut roots of 250-300 cm tall red oaks (Quercus rubra L) dug by tree spade, increased the number of roots regenerated from medium (5-1 5 mm) and large (15-25 mm) diameter roots. IBA stimulated more new roots than NAA on large roots only. As root diameter Glen P. Lumis 165 NASA Astrophysics Data System (ADS) Immobile higher plants are oriented in the gravitational field due to gravitropim that is a physiological growth reaction and consists of three phases: reception of a gravitational signal by statocytes, its transduction to the elongation zone, and finally the organ bending. According to the starch-statolith hypothesis, amyloplasts in the specialized graviperceptive cells - statocytes sediment in the direction of a gravitational vector in the distal part of a cell. The polar arrangement of organelles is maintained by means of the cytoskeleton. On the Kholodny-Went's, theory the root bending is provided by the polar movement of auxin from a root cap to the elongation zone. It is also known that gravistimulation initiates a rapid Ca2+ redistribution in a root apex. Calcium ions modify an activity of many cytoskeletal proteins and clustering of calcium channels may be directed by actin microfilaments. Although the available data show the Ca2+ and cytoskeleton participation in graviperception and signal transduction, the clear evidence with regard to the participation of cytoskeletal elements and calcium ions in these processes is therefore substantial but still circumstantial and requires new experimental data. Roots are characterized with positive gravitropism, i. e. they grow in the direction of a gravitational vector. It was first shown by us that roots change the direction of a gravitropic reaction under gravistimulation in the weak combined magnetic field with a frequency of 32 Hz. 2-3-day old cress seedlings were gravistimulated in moist chambers, which are placed in ?-metal shields. Inside ? -metal shields, combined magnetic fields have been created. Experiments were performed in darkness at temperature 20±10C. Measurements of the magnitude of magnetic fields were carried out with a flux-gate magnetometer. Cress roots reveal negative gravitropism, i. e. they grow in the opposite direction to a gravitational vector, during 2 h of gravistimulation and then roots begin to grow more or less parallel to the Earth's surface, i.e. they reveal plagiotropism. Since such combined magnetic field is adjusted to the cyclotron frequency of Ca2+ ions, these observations demonstrate the participation of calcium ions in root gravitropism. Cyclotron frequency of Ca2+ ions is the formal frequency of ion rotation in the static magnetic field. Simultaneous applying the altering magnetic field with the same frequency can provoke auto-oscillation in the system and consequently change the rate and/or the direction of Ca2+ ion flow in a root under gravistimulation. The data of light, electron, and confocal laser microscopy and kinetics of a gravitropic reaction, which have been obtained on such the new original model, are discussed in the light of current concepts of root gravitropism. Kordyum, E. L.; Bogatina, N. I.; Kalinina, Ja. M.; Sheykina, N. V. 166 Microsoft Academic Search Studies in global plant biogeography have almost exclusively analyzed re- lationships of abiotic and biotic factors with the distribution and structure of vegetation aboveground. The goal of this study was to extend such analyses to the belowground structure of vegetation by determining the biotic and abiotic factors that influence vertical root distributions in the soil, including soil, climate, and plant H. Jochen Schenk; Robert B. Jackson 2002-01-01 167 NSDL National Science Digital Library This lesson introduces quadratic equations and graphs. Equations of the form ax^2 + c = 0 are solved via extraction of roots. Later application problems involving volume and surface area and compound interest (problems of the form a(x - p)^2 = q ) are presented. 2011-01-01 168 NSDL National Science Digital Library In this lesson, students measure the sides of many squares and their diagonals, then consider the ratio of diagonal length to side length. They can note that in all cases the ratio hovers near 1.4 or the square root of 2. The very complete lesson plan contains handouts, questions for discussion, and problems for applying the new learning. Johnston, Christopher 2000-01-01 169 ERIC Educational Resources Information Center Violence is rooted in obedience to authority and in comparisons--foundations of our institutions of parenting and schooling. Obedience brings reward and punishment, comparison perpetuates a cycle of competition and conflict. Television violence is especially harmful because children easily understand visual images. The Reality Research approach to… Koziey, Paul W. 1996-01-01 170 NASA Astrophysics Data System (ADS) The Western Ghats of Kerala, India is prone to shallow landslides and consequent debris flows. An earlier study (Kuriakose et al., DOI:10.1002/esp.1794) with limited data had already demonstrated the possible effects of vegetation on slope hydrology and stability. Spatially distributed root cohesion is one of the most important data necessary to assess the effects of anthropogenic disturbances on the probability of shallow landslide initiation, results of which are reported in sessions GM6.1 and HS13.13/NH3.16. Thus it is necessary to the know the upper limits of reinforcement that the roots are able to provide and its spatial and vertical distribution in such an anthropogenically intervened terrain. Root tensile strength and root pull out tests were conducted on nine species of plants that are commonly found in the region. They are 1) Rubber (Hevea Brasiliensis), 2) Coconut Palm (Cocos nucifera), 3) Jackfruit trees (Artocarpus heterophyllus), 4) Teak (Tectona grandis), 5) Mango trees (Mangifera indica), 6) Lemon grass (Cymbopogon citratus), 7) Gambooge (Garcinia gummi-gutta), 8) Coffee (Coffea Arabica) and 9) Tea (Camellia sinensis). About 1500 samples were collected of which only 380 could be tested (in the laboratory) due to breakage of roots during the tests. In the successful tests roots failed in tension. Roots having diameters between 2 mm and 12 mm were tested. Each sample tested had a length of 15 cm. Root pull out tests were conducted in the field. Root tensile strength vs root diameter, root pull out strength vs diameter, root diameter vs root depth and root count vs root depth relationships were derived. Root cohesion was computed for nine most dominant plants in the region using the perpendicular root model of Wu et al. (1979) modified by Schimidt et al. (2001). A soil depth map was derived using regression kriging as suggested by Kuriakose et al., (doi:10.1016/j.catena.2009.05.005) and used along with the land use map of 2008 to distribute the computed root tensile strength both vertically and spatially. Root cohesion varies significantly with the type of land use and the depth of soil. The computation showed that a maximum root reinforcement of 40 kPa was available in the first 30 cm of soil while exponentially decreased with depth to just about 3 kPa at 3 m depth. Mixed crops land use unit had the maximum root cohesion while fallow land, degraded forest and young rubber plantation had the lowest root reinforcement. These are the upper limits of root reinforcement that the vegetation can provide. When the soil is saturated, the bond between soil and roots reduces and thus the applicable root reinforcement is limited by the root pullout strength. Root reinforcement estimated from pullout strength vs diameter relationships was significantly lower than those estimated from tensile strength vs diameter relationships. Lukose Kuriakose, Sekhar; van Beek, L. P. H. 2010-05-01 171 Microsoft Academic Search Natural vegetation is a dynamic component of the climate system, which plays a key role in determination of weather and climate. Forests, due to their higher leaf area, larger roughness length, lower albedo and deeper roots compared to other vegetated surfaces affect the exchange of water- energy- and momentum with the atmosphere. Thus climatic feedbacks of forest cover change can Borbala Galos; Daniela Jacob 2010-01-01 172 NASA Astrophysics Data System (ADS) To improve the efficiency of water use in irrigation practices and to provide information for modeling the knowledge of plants root system becomes necessary. The use of subsurface drip irrigation (SDI) in sugarcane cultivation is an interesting cultural practice to improve production and allow cultivation in marginal lands due to water deficits conditions. The SDI provides better water use efficiency, due to the water and nutrients application in root zone plants. However, despite of the agronomic importance, few studies about the root system of sugarcane were performed. The use of root scanner is an alternative to the evaluation of the root system, which enables the continuous study of the roots throughout the cycle and for many years, but data about the use of this method for sugarcane are still scarce. The aim of this study was to determine the time required for stabilization of the root system growth of sugarcane cultivar IACSP-5000 around the access tube in which images were captured. The field experiment was carried out in Campinas, São Paulo State, Brazil. The fertigation was applied by a subsurface drip system.. The soil moisture was monitored by capacitance probes. The pH and electrical conductivity of the soil solution were monitored through solution extractor. Two access tubes with 1.05 m length were used, with 7 days difference between installations. The images were captured at 110, 128, 136, 143 and 151 days after harvest cane-plant, in the second cycle (1st cane ratoon), with the Root Scanner CI-600 ™ and were analyzed the number of roots and root length in each layer in different depths in the soil profile by software RootSnap! ™. The results show that the highest rates of increase in the number and length of roots were observed in the first 27 days. Absolute growth rates of up to 81 mm day-1 and 38 mm day-1 were presented in 0-20 and 20-40 cm layer respectively. The number of roots stabilized from 27 days after installation of the tube, while the length of the root system stabilized between 30 and 40 days. Root growth was more intense in the first two layers (0 to 0.4 m depth) of soil profile, which presented more than 80% of the total root length after the stabilization. Yukitaka Pessinatti Ohashi, Augusto; Célia de Matos Pires, Regina; Barros de Oliveira Silva, Andre Luiz; Vasconcelos Ribeiro, Rafael 2013-04-01 173 NASA Astrophysics Data System (ADS) Root architectural models are essential tools to understand how plants access and utilize soil resources during their development. However, root architectural models use complex geometrical descriptions of the root system and this has limitations to model interactions with the soil. This paper presents the development of continuous models based on the concept of oriented density distribution function. The growth of the root system is built as a hierarchical system of partial differential equations (PDEs) that incorporate single root growth parameters such as elongation rate, gravitropism and branching rate which appear explicitly as coefficients of the PDE. Acquisition and transport of nutrients are then modelled by extending Darcy's law to oriented density distribution functions. This framework was applied to build a model of the growth and water uptake of barley root system. This study shows that simplified and computer effective continuous models of the root system development can be constructed. Such models will allow application of root growth models at field scale. Dupuy, Lionel X. 2011-09-01 174 E-print Network (tree food) produced by the leaves. About 85% of a tree's roots are within the top 18 inches of the soil the trunk two to three times the height of the tree! Figure 1: Area of Root Distribution vs. Crown 175 E-print Network Name ___KEY_______________ Due Date: __________________ GEOL 106 Writing #1  Intro & Overview 1 with interstellar (between star) dust that came from a supernovae star explosion, briefly explain how we think our solar system formed. Following the Big Bang, some first generation stars became supernovae, spreading Kirby, Carl S. 176 NASA Astrophysics Data System (ADS) Mineral phosphate fertilisers are a non-renewable resource; rock phosphate reserves are estimated to be depleted in 50 to 100 years. In order to prevent a severe phosphate crisis in the 21st century, there is a need to decrease agricultural inputs such as P fertilisers by making use of plant mechanisms that increase P acquisition efficiency. Most plants establish mycorrhizal symbiosis as an adaptation to increase/economize their P acquisition from the soil. However, there is a great functional diversity in P acquisition mechanisms among different fungal species that colonize the roots (Thonar et al. 2011), and the composition of mycorrhizal community is known to depend strongly on agricultural management practices. Thus, the agroecosystem management may substantially affect the mycorrhizal functioning and also the use of P fertilizers. To date, it is still difficult to quantify the potential input savings for the agricultural crops through manipulation of their symbiotic microbiome, mainly due to lack of mechanistic understanding of P uptake dynamics by the fungal hyphae. In a first attempt, Schnepf et al. (2008b) have used mathematical modelling to show on the single root scale how different fungal growth pattern influence root P uptake. However, their approach was limited by the fact that it was restricted to the scale of a single root. The goal of this work is to advance the dynamic, three-dimensional root architecture model of Leitner et al. (2010) to include root system infection with arbuscular mycorrhizal fungi and growth of external mycelium. The root system infection model assumes that there is an average probability of infection (primary infection), that the probability of infection of a new root segment immediately adjacent to an existing infection is much higher than the average (secondary infection), that infected root segments have entry points that are the link between internal and external mycelium, that only uninfected root segments are susceptible (since new infection can only be detected in previously uninfected root) and that there is a maximum percentage of overall root system infection. Growth of external mycelium is based on the model of Schnepf et al. (2008a) but translated into L-system form. Different hypotheses about the effect of inoculum position (dispersed vs. localized) and about root system infection mechanisms can be tested with this model. This will help to quantify the role of the complex geometric structure of external mycelia in plant P acquisition and to gain mechanistic insights into whole-plant processes affected by mycorrhizal symbiosis. Literature Leitner, D., Klepsch, S., Bodner, G., Schnepf, A., 2010a. A dynamic root system growth model based on L-Systems. Plant Soil 332, 177-192. Schnepf, A., Roose, T., Schweiger, P., 2008a. Growth model for arbuscular mycorrhizal fungi. J R Soc Interface 5, 773-784. Schnepf, A., Roose, T., Schweiger, P., 2008b. Impact of growth and uptake patterns of arbuscular mycorrhizal fungi on plant phosphorus uptake - a modelling study. Plant Soil 312, 85-99. Thonar C, Schnepf A, Frossard E, Roose T, Jansa J (2011) Traits related to differences in function among three arbuscular mycorrhizal fungi. Plant and Soil 339: 231-245. Acknowledgements This research was partly supported by the Austrian Science Fund FWF (Grant No.: V220-N13) and by an APART fellowship of the Austrian Academy of Sciences at the Computational Science Center, University of Vienna (to D.L.). Schnepf, Andrea; Schweiger, Peter; Jansa, Jan; Leitner, Daniel 2014-05-01 177 PubMed Shrubs of the Great Basin desert in Utah are subjected to a prolonged summer drought with the potential consequence of reduced water transport capability of the xylem due to drought-induced cavitation. Hydraulic redistribution (HR) is the passive movement of water from deep to shallow soil through plant roots. Hydraulic redistribution can increase water availability in shallow soil and ameliorate drought stress, providing better soil and root water status, which could affect shallow root conductivity (Ks) and native root embolism. We tested this hypothesis in an Artemisia tridentata Nutt. mono-specific stand grown in a common garden in Utah. We enhanced HR artificially by applying a once a week deep-irrigation treatment increasing the water potential gradient between deep and shallow soil layers. Plants that were deep-watered had less negative water potentials and greater stomatal conductance and transpiration rates than non-watered control plants. After irrigation with labeled water (?D), xylem water in stems and shallow roots of watered shrubs was enriched with respect to control shrubs, a clear indication of deep water uptake and HR. Shallow root conductivity was threefold greater and shrubs experienced lower native embolism when deep-watered. We found clear evidence of water transfer between deep and shallow roots through internal HR that delayed depletion of shallow soil water content, maintained Ks and prevented root embolism. Overall, our results show a positive effect of HR on root water transport capacity in otherwise dry soil, with important implications for plant water status. PMID:24436338 Prieto, Iván; Ryel, Ronald J 2014-01-01 178 USGS Publications Warehouse This study examined the potential for inter-specific differences in root aeration to determine wetland plant distribution in nature. We compared aeration in species that differ in the type of sediment and depth of water they colonize. Differences in root anatomy, structure and physiology were applied to aeration models that predicted the maximum possible aerobic lengths and development of anoxic zones in primary adventitious roots. Differences in anatomy and metabolism that provided higher axial fluxes of oxygen allowed deeper root growth in species that favour more reducing sediments and deeper water. Modelling identified factors that affected growth in anoxic soils through their effects on aeration. These included lateral root formation, which occurred at the expense of extension of the primary root because of the additional respiratory demand they imposed, reducing oxygen fluxes to the tip and stele, and the development of stelar anoxia. However, changes in sediment oxygen demand had little detectable effect on aeration in the primary roots due to their low wall permeability and high surface impedance, but appeared to reduce internal oxygen availability by accelerating loss from laterals. The development of pressurized convective gas flow in shoots and rhizomes was also found to be important in assisting root aeration, as it maintained higher basal oxygen concentrations at the rhizome-root junctions in species growing into deep water. (C) 2000 Annals of Botany Company. Sorrell, B.K.; Mendelssohn, I.A.; McKee, K.L.; Woods, R.A. 2000-01-01 179 PubMed *Deep root water uptake in tropical Amazonian forests has been a major discovery during the last 15 yr. However, the effects of extended droughts, which may increase with climate change, on deep soil moisture utilization remain uncertain. *The current study utilized a 1999-2005 record of volumetric water content (VWC) under a throughfall exclusion experiment to calibrate a one-dimensional model of the hydrologic system to estimate VWC, and to quantify the rate of root uptake through 11.5 m of soil. *Simulations with root uptake compensation had a relative root mean square error (RRMSE) of 11% at 0-40 cm and < 5% at 350-1150 cm. The simulated contribution of deep root uptake under the control was c. 20% of water demand from 250 to 550 cm and c. 10% from 550 to 1150 cm. Furthermore, in years 2 (2001) and 3 (2002) of throughfall exclusion, deep root uptake increased as soil moisture was available but then declined to near zero in deep layers in 2003 and 2004. *Deep root uptake was limited despite high VWC (i.e. > 0.30 cm(3) cm(-3)). This limitation may partly be attributable to high residual water contents (theta(r)) in these high-clay (70-90%) soils or due to high soil-to-root resistance. The ability of deep roots and soils to contribute increasing amounts of water with extended drought will be limited. PMID:20659251 Markewitz, Daniel; Devine, Scott; Davidson, Eric A; Brando, Paulo; Nepstad, Daniel C 2010-08-01 180 NASA Astrophysics Data System (ADS) North California enjoys wet and mild winters, but experiences extreme hot, dry summer conditions, with occasional drought years. Despite the severity of summer conditions, blue oaks are winter-deciduous. We hypothesized that the binary nature of water availability would be reflected in blue oak root architecture. Our objective was to understand how the form of the root system facilitates ecosystem functioning. To do this, we sought to characterize the structure of the root system, and survey coarse root distribution with ground penetrating radar (GPR), due to its advantages in covering large areas rapidly and non-destructively. Because GPR remains a relatively new technology for examining root distribution, an ancillary objective was to test this methodology, and help facilitate its application more broadly. A third objective was to test the potential for upscaling coarse root biomass by developing allometric relations based on LIDAR measurements of above ground canopy structure. We surveyed six 8x8 m locations with trees varying in size, age and clumping (i.e. isolated trees vs. tree clusters). GPR signals were transformed to root biomass by calibrating them against excavated roots. Toward this goal, we positioned two rectangles of size 60x100 cm in each of the grids, excavated and sieved soil to harvest roots. Our results indicate that coarse roots occupy the full soil profile, and that root biomass of old large trees peaks just above the bedrock. As opposed to other semi-arid regions, where trees often develop extensive shallow coarse lateral roots, in order to exploit the entire wet-soil medium, we found that coarse root density decreased with distance from the bole, and dropped sharply at a distance of 2 m. We upscaled root biomass to stand-scale (2.8±0.4 kg m-2) based on LiDAR analysis of the relative abundance of each tree configuration. We argue that the deep and narrow root structure we observed reflects the ecohydrology of oaks in this ecosystem, because extensive lateral roots would not be beneficial during the growing season (water is sufficiently abundant), nor during the summer season (soil water is highly limited). Our research has shown that the combination of resource availability, which is primarily water in this ecosystem, and plant demand, are portrayed in the form of the root system. Raz-Yaseef, N.; Koteen, L. E.; Baldocchi, D. D. 2012-12-01 181 NASA Astrophysics Data System (ADS) Crop productivity is highly dependent on a good supply of water and nutrients. With increasing demand for food and variable water regimes due to climate change, it is important to get a better understanding on the processes involved in water and nutrient uptake by roots. Changes in soil structure affect water and nutrient availabilities for plants. It is known that roots change their environment during growth but little is known on how soil structural properties change as roots penetrate soils. More detailed information on root growth induced changes in the rhizosphere will help us to model water and nutrient uptake by plants. The objective of this study was to measure directly how soil structure changes in close proximity to the root as a seedling root penetrates through the soil. 3D volumetric images of maize root growth during six hours were obtained using X-ray microtomography at a resolution of 21 ?m. Roots were grown in soils of two different compaction levels (50 kPa and 200 kPa uniaxial load) and matric potentials (10 kPa and 100 kPa). Changes in porosity, pore connectivity and root-soil contact were determined from 2D cross sections for each time step. The 2D cross sections were chosen at 4 different positions in the sample, and each section was divided into sections of 64 voxels (1.3 mm2) to determine changes in porosity and connectivity with distance from the root. Soil movement caused by root growth was quantified from 2D cross sections at different positions along the sample using Particle image velocimetry (PIV). Changes in soil structure during root growth were observed. Porosity in close proximity to the root decreased whereas root-soil contact increased with time. The PIV showed a radial deformation of the soil. Greatest deformation was found close to the root. Some aggregates fractured during root growth whereas others were pushed into the pore space. These data on the changes in soil structure will help us to predict water and nutrient availability for plants. They are also a useful first step in a better understanding of root growth mechanisms and how they overcome physical constraints imposed by soils. Schmidt, Sonja; Bengough, Glyn; Hallett, Paul 2014-05-01 182 NASA Astrophysics Data System (ADS) Earlier research on debris flows in the Tikovil River basin of the Western Ghats concluded that root cohesion is significant in maintaining the overall stability of the region. In this paper we present the most recent results (December 2008) of root tensile strength tests conducted on nine species of plants that are commonly found in the region. They are 1) Rubber (Hevea Brasiliensis), 2) Coconut Palm (Cocos nucifera), 3) Jackfruit trees (Artocarpus heterophyllus), 4) Teak (Tectona grandis), 5) Mango trees (Mangifera indica), 6) Lemon grass (Cymbopogon citratus), 7) A variety of Tamarind (Garcinia gummigutta), 8) Coffee (Coffea Arabica) and Tea (Camellia sinensis). About 1500 samples were collected of which only 380 could be tested (in the laboratory) due to breakage of roots during the tests. In the successful tests roots failed in tension. Roots having diameters between 2 mm and 12 mm were tested. Each sample tested has a length of 15 cm. Results indicate that the roots of Coffee, Tamarind, Lemon grass and Jackfruit are the strongest of the nine plant types tested whereas Tea and Teak plants had the most fragile roots. Coconut roots behaved atypical to the others, as the bark of the roots was crushed and slipped from the clamp when tested whereas its internal fiber was the strongest of all tested. Root tensile strength decreases with increasing diameters, Rubber showing more ductile behaviour than Coffee and Tamarind that behaved more brittle, root tensile strength increasing exponentially for finer roots. Teak and Tea showed almost a constant root tensile strength over the range of diameters tested and little variability. Jack fruit and mango trees showed the largest variability, which may be explained by the presence of root nodules, preventing the derivation of an unequivocal relationship between root diameters and tensile strength. This results in uncertainty of root strength estimates that are applicable. These results provide important information to quantify the upper limit of the root cohesion at the stand level in combination with land use maps. This is an indispensable component in the evaluation of slope stability in the region. Lukose Kuriakose, S.; van Beek, L. P. H.; van Westen, C. J. 2009-04-01 183 EPA Science Inventory Ozone alters root growth and root processes by first reducing photosynthesis and altering foliar metabolic pathways. The alteration in foliar metabolism is reflected in lowered carbohydrate levels in the roots. This can reduce key metabolic processes such as mineral uptake and sy... 184 Microsoft Academic Search DURING investigations into the fine structure of apical meristems under the electron microscope, one of us (S. G.) discovered that it was possible, in maize and barley, to detach the intact root cap cleanly from the rest of the root tip. This is shown in Fig. 1. The roots of grasses are characterized by having a discrete cap meristem and, B. E. Juniper; Suzanne Groves; BRURIA LANDAU-SCHACHAR; L. J. AUDUS 1966-01-01 185 E-print Network of the CRNs #12;Motoneurons Cochlear Root Neurons PnC Muscles Auditory Startle reflex Cochlear Root Neurons of the CRNs explain its role in the ASR #12;AUDITORY STARTLE REFLEX Sudden and loud sounds (> 90 dB) Rapid. · They can be immunostained and visualized with the protein calbindin Cochlear Root Neurons - Characteristics Oliver, Douglas L. 186 ERIC Educational Resources Information Center This instructional unit is intended for use in training operations personnel and others involved in scram analysis at nuclear power plants in the techniques of root cause analysis. Four lessons are included. The first lesson provides an overview of the goals and benefits of the root cause analysis method. Root cause analysis techniques are covered… Kluch, Jacob H. 187 E-print Network . Indeed, root and butt rots cause more economic damage to commercial forestry in the temperate world thanFOREST PATHOLOGY Root and Butt Rot Diseases M Garbelotto, University of California  Berkeley Diseases caused by root rots figure prominently amongst the most-studied pathologies of forest trees California at Berkeley, University of 188 PubMed Central The rhizosphere was defined over 100 years ago as the zone around the root where microorganisms and processes important for plant growth and health are located. Recent studies show that the diversity of microorganisms associated with the root system is enormous. This rhizosphere microbiome extends the functional repertoire of the plant beyond imagination. The rhizosphere microbiome of Arabidopsis thaliana is currently being studied for the obvious reason that it allows the use of the extensive toolbox that comes with this model plant. Deciphering plant traits that drive selection and activities of the microbiome is now a major challenge in which Arabidopsis will undoubtedly be a major research object. Here we review recent microbiome studies and discuss future research directions and applicability of the generated knowledge. PMID:23755059 Bakker, Peter A. H. M.; Berendsen, Roeland L.; Doornbos, Rogier F.; Wintermans, Paul C. A.; Pieterse, Corné M. J. 2013-01-01 189 PubMed The effects of Si on growth, the anatomy of the roots, radial oxygen loss (ROL) and Fe/Mn plaque on the root surface were investigated in Avicennia marina (Forsk.) Vierh. seedlings under Cd stress. Si prompted the growth of seedlings and reduced the Cd concentration in the root, stem and leaf of A. marina. Si prompted the development of the apoplastic barrier in the roots, which may be related to the reduction of Cd uptake. The higher amount of ROL and Mn plaque on the root surface due to Si were also related to the promotion of Cd tolerance in A. marina seedlings. Therefore, it is concluded that the alteration of the anatomy of the roots, the increase of ROL and Mn plaque of A. marina seedlings play an important role in alleviation of Cd toxicity due to Si. PMID:24095049 Zhang, Qiong; Yan, Chongling; Liu, Jingchun; Lu, Haoliang; Wang, Wenyun; Du, Jingna; Duan, Hanhui 2013-11-15 190 PubMed Thiazides are widely used diuretics that first became available in the 1950s. The first reports of photosensitivity reactions to thiazides were published shortly after the introduction of these drugs, but few cases have been described since. We review all the cases of photosensitivity due to thiazides published up to December 2011. We found 62 cases, 33 in women and 29 in men. The most common presentation was eczematous lesions in a photodistributed pattern, and the most common causative agent was hydrochlorothiazide. The results of photobiological studies were published in only some of the cases reviewed. In most cases, phototesting revealed an abnormal response to UV-A alone or to both UV-A and UV-B. In some cases, the results of phototesting were normal and only photopatch testing yielded abnormal results. Diagnosis of photosensitivity due to thiazides requires a high degree of suspicion. Ideally, diagnosis should be confirmed by a photobiological study. PMID:23664250 Gómez-Bernal, S; Alvarez-Pérez, A; Rodríguez-Pazos, L; Gutiérrez-González, E; Rodríguez-Granados, M T; Toribio, J 2014-05-01 191 E-print Network We reconsider Archimedes' evaluations of several square roots in 'Measurement of a Circle'. We show that several methods proposed over the last century or so for his evaluations fail one or more criteria of plausibility. We also provide internal evidence that he probably used an interpolation technique. The conclusions are relevant to the precise calculations by which he obtained upper and lower bounds on pi. Davies, E B 2011-01-01 192 E-print Network 1 Auxin fluxes in the root apex co-regulate gravitropism and lateral root1 initiation2 Running title: Co-regulation of root gravitropism and branching by auxin3 transport4 Lucas, M.1,2 , Godin, C.2 and root5 gravitropism, two processes that are regulated by auxin, are co-regulated in6 Arabidopsis. We Paris-Sud XI, Université de 193 Microsoft Academic Search Summary Using a vibrating probe technique, four distinct electric patterns around growing cress roots were observed. The growth rate of the root with a particular one of them was apparently faster than that with the others. No direct correlation between the intensity of electric field and the root growth rate could be found. When gravistimulation was applied to the root, Akira Iwabuchi; Masafumi Yano; Hiroshi Shimizu 1989-01-01 194 Microsoft Academic Search Deuterated water absorbed by deep roots of Artemisia tridentata appeared in the stem water of neighboring Agropyron desertorum tussocks. This supports the hypothesis that water absorbed by deep roots in moist soil moves through the roots, is released in the upper soil profile at night, and is stored there until it is resorbed by roots the following day. This phenomenon M. M. Caldwell; J. H. Richards 1989-01-01 195 NASA Technical Reports Server (NTRS) A gravitational stimulus was used to induce the curvature of the main root of Arabidopsis thaliana. The number of secondary roots increased on the convex side and decreased on the concave side of any curved main root axes in comparison with straight roots used as the control. The same phenomenon was observed with the curved main roots of plants grown on a clinostat and of mutant plants exhibiting random root orientation. The data suggest that the pattern of lateral root formation is associated with curvature but is independent of the environmental stimuli used to induce curvature. Fortin, M. C.; Pierce, F. J.; Poff, K. L. 1989-01-01 196 Microsoft Academic Search Root branching order supports a powerful approach to understanding complex root systems; however, how the pattern of root\\u000a morphological characteristics, tissue carbon (C) and nitrogen (N) concentrations, and root lifespan are related to anatomical\\u000a features of variable root orders for mature shrubs (?19 years old) in sandy habitats is still unclear. In this study, these\\u000a relationships were investigated for three typical Gang Huang; Xue-yong Zhao; Ha-lin Zhao; Ying-xin Huang; Xiao-an Zuo 2010-01-01 197 Microsoft Academic Search The organogenetic competence of roots and Agrobacterium rhizogenes-induced hairy roots of twelve Lycopersicon genotypes was investigated. Both roots and hairy roots of L. peruvianum, L. chilense, L. hirsutum and two L. peruvianum-derived genotypes regenerated shoots after 2–4 weeks of incubation on zeatin-contained medium. Anatomical analysis showed\\u000a that shoot regeneration in roots could be direct or indirect, depending on the genotype Lázaro E. P. Peres; Patrícia G. Morgante; Cláudia Vecchi; Jane E. Kraus; Marie-Anne van Sluys 2001-01-01 198 Microsoft Academic Search Root tips of Hyoscyamus niger were cultivated on agar or in liquid medium, and patterns of elongation and branching were investigated.\\u000a The elongation of roots compared to branching, particularly tertiary root branching, was more effective in liquid medium than\\u000a on agar medium. The number (0.06 per cm) of tertiary roots which branched out from secondary roots was far less than Seung Han Woo; Jong Moon Park; Ji-Won Yang 1997-01-01 199 PubMed Central The maize root system is crucial for plant establishment as well as water and nutrient uptake. There is substantial genetic and phenotypic variation for root architecture, which gives opportunity for selection. Root traits, however, have not been used as selection criterion mainly due to the difficulty in measuring them, as well as their quantitative mode of inheritance. Seedling root traits offer an opportunity to study multiple individuals and to enable repeated measurements per year as compared to adult root phenotyping. We developed a new software framework to capture various traits from a single image of seedling roots. This framework is based on the mathematical notion of converting images of roots into an equivalent graph. This allows automated querying of multiple traits simply as graph operations. This framework is furthermore extendable to 3D tomography image data. In order to evaluate this tool, a subset of the 384 inbred lines from the Ames panel, for which extensive genotype by sequencing data are available, was investigated. A genome wide association study was applied to this panel for two traits, Total Root Length and Total Surface Area, captured from seedling root images from WinRhizo Pro 9.0 and the current framework (called ARIA) for comparison using 135,311 single nucleotide polymorphism markers. The trait Total Root Length was found to have significant SNPs in similar regions of the genome when analyzed by both programs. This high-throughput trait capture software system allows for large phenotyping experiments and can help to establish relationships between developmental stages between seedling and adult traits in the future. PMID:25251072 Pace, Jordon; Lee, Nigel; Naik, Hsiang Sing; Ganapathysubramanian, Baskar; Lubberstedt, Thomas 2014-01-01 200 PubMed Central A 59-year-old male patient with Marfan's syndrome was referred to our clinic due to acute chest pain. His medical history contains complex surgery for type A aortic dissection 19 years ago including composite root replacement using a mechanical aortic valve. Immediate computed tomography indicated perforation at the distal ascending aortic anastomosis plus complete avulsion of both coronary ostia. The patient underwent successful rescue surgery with ascending aortic and arch replacement using a modified Cabrol technique. PMID:23662240 Seeburger, Joerg; Etz, Christian D.; Sauer, Matthias; Lehmkuhl, Lukas; Misfeld, Martin; Mohr, Friedrich W. 2013-01-01 201 PubMed Central Background and Aims Phenotypic plasticity is based on the organism's ability to perceive, integrate and respond to multiple signals and cues informative of environmental opportunities and perils. A growing body of evidence demonstrates that plants are able to adapt to imminent threats by perceiving cues emitted from their damaged neighbours. Here, the hypothesis was tested that unstressed plants are able to perceive and respond to stress cues emitted from their drought- and osmotically stressed neighbours and to induce stress responses in additional unstressed plants. Methods Split-root Pisum sativum, Cynodon dactylon, Digitaria sanguinalis and Stenotaphrum secundatum plants were subjected to osmotic stress or drought while sharing one of their rooting volumes with an unstressed neighbour, which in turn shared its other rooting volume with additional unstressed neighbours. Following the kinetics of stomatal aperture allowed testing for stress responses in both the stressed plants and their unstressed neighbours. Key Results In both P. sativum plants and the three wild clonal grasses, infliction of osmotic stress or drought caused stomatal closure in both the stressed plants and in their unstressed neighbours. While both continuous osmotic stress and drought induced prolonged stomatal closure and limited acclimation in stressed plants, their unstressed neighbours habituated to the stress cues and opened their stomata 3–24 h after the beginning of stress induction. Conclusions The results demonstrate a novel type of plant communication, by which plants might be able to increase their readiness to probable future osmotic and drought stresses. Further work is underway to decipher the identity and mode of operation of the involved communication vectors and to assess the potential ecological costs and benefits of emitting and perceiving drought and osmotic stress cues under various ecological scenarios. PMID:22408186 Falik, Omer; Mordoch, Yonat; Ben-Natan, Daniel; Vanunu, Miriam; Goldstein, Oron; Novoplansky, Ariel 2012-01-01 202 PubMed Hydrogenases were measured in intact actinorhizal root nodules and from disrupted nodules of Alnus glutinosa, Alnus rhombifolia, Alnus rubra, and Myrica pensylvanica. Whole nodules took up H2 in an O2-dependent reaction. Endophyte preparations oxidized H2 through the oxyhydrogen reaction, but rates were enhanced when hydrogen uptake was coupled to artificial electron acceptors. Oxygen inhibited artifical acceptor-dependent H2 uptake. The hydrogenase system from M. pensylvanica had a different pattern of coupling to various electron acceptors than the hydrogenase systems from the alders; only the bayberry system evolved H2 from reduced viologen dyes. PMID:6989799 Benson, D R; Arp, D J; Burris, R H 1980-04-01 203 PubMed Central The production and turnover of fine roots play substantial roles in the biogeochemical cycles of terrestrial ecosystems. However, the disparity among the estimates of both production and turnover, particularly due to technical limitations, has been debated for several decades. Here, we conducted a meta-analysis to compare published estimates of fine root production and turnover rates derived from different methods at the same sites and at the same sampling time. On average, the estimates of fine root production and turnover rates were 87% and 124% higher, respectively, by indirect methods than by direct methods. The substantially higher fine root production and turnover estimated by indirect methods, on which most global carbon models are based, indicate the necessity of re-assessing the global carbon model predictions for atmospheric carbon sequestration in soils as a result of the production and turnover of fine roots. PMID:23166603 Yuan, Z. Y.; Chen, Han Y. H. 2012-01-01 204 E-print Network dry weight and length. High concentrations of NaNO&, NaZS04, and NaC1 inhibited root number more than high concentrations of KCl and KNO&. The effect of NaC1 on root dry weight and length were due to ionic toxicities and/or increased osmotic... not affect root number. High concentrat1ons of NaCl, NaNO&, and Na&SO& 1nhibi ted root number 1nd1cati ng that Cl was not the inhibi- tory ion. KCl did not 1nhib1t root number at high concentrations, whereas, NaC1 did. Th1s ind1cates that Na+ was the cause... Janssen, Antonius Hendrick 2012-06-07 205 NASA Astrophysics Data System (ADS) After zinc stress the total micropore volume decreased remarkably while the average micropore radius increased remarkably for the rye roots. Pore size distribution functions of the roots after the additional zinc application showed the decrease of the small micropore fraction from ca 2 to 10 nm and the increase of the large micropore from ca 22 to 50 nm. The root surface pores were fractal. After the stress pore fractal dimension increased. The changes of the microporosity observed in the roots surface can be related to the high content of zinc in the cell wall and/or due to the shortage of Ca+2 the intercellular spaces particularly in the tissues of seminal cortex of the studied roots might have grown. Szatanik-Kloc, A. 2012-07-01 206 PubMed Cyanamide (CA) is a phytotoxic compound produced by four Fabaceae species: hairy vetch, bird vetch, purple vetch and black locust. Its toxicity is due to complex activity that involves the modification of both cellular structures and physiological processes. To date, CA has been investigated mainly in dicot plants. The goal of this study was to investigate the effects of CA in the restriction of the root growth of maize (Zea mays), representing the monocot species. CA (3mM) reduced the number of border cells in the root tips of maize seedlings and degraded their protoplasts. However, CA did not induce any significant changes in the organelle structure of other root cells, apart from increased vacuolization. CA toxicity was also demonstrated by its effect on cell cycle activity, endoreduplication intensity, and modifications of cyclins CycA2, CycD2, and histone HisH3 gene expression. In contrast, the arrangement of microtubules was not altered by CA. Treatment of maize seedlings with CA did not completely arrest mitotic activity, although the frequency of dividing cells was reduced. Furthermore, prolonged CA treatment increased the proportion of endopolyploid cells in the root tip. Cytological malformations were accompanied by an induction of oxidative stress in root cells, which manifested as enhanced accumulation of H2O2. Exposure of maize seedlings to CA resulted in an increased concentration of auxin and stimulated ethylene emission. Taken together, these findings suggested that the inhibition of root growth by CA may be a consequence of stress-induced morphogenic responses. PMID:24709147 Soltys, Dorota; Rudzi?ska-Langwald, Anna; Kurek, Wojciech; Szajko, Katarzyna; Sliwinska, Elwira; Bogatek, Renata; Gniazdowska, Agnieszka 2014-05-01 207 Microsoft Academic Search Research work on wilt\\/root rot diseases of chickpea (Cicer arietinum L.) in Ethiopia is reviewed. The five important wilt\\/root rot diseases in Ethiopia are wilt, dry root rot, wet root rot, black root rot and collar rot, which are caused by Fusarium oxysporum f. sp. ciceri, Rhizoctonia bataticola, R. solani, F. solani and Sclerotium rolfsii respectively. Of these, dry root S. P. S. Beniwal; S. Ahmed; D. Gorfu 1992-01-01 208 E-print Network distributed cylindrical roots. The growth direction of the root is dictated by gravity, therefore fixed a macroscopic model for the root growth, in presence of many roots. We assume that the roots are planted an effective model for the root growth and for the nutrient concentration when tends to zero. The motivation Rheinisch-Westfälische Technische Hochschule Aachen (RWTH) 209 PubMed The root system is crucial for acquisition of resources from the soil. In legumes, the efficiency of mineral and water uptake by the roots may be reinforced due to establishment of symbiotic relationships with mycorrhizal fungi and interactions with soil rhizobia. Here, we investigated the role of miR396 in regulating the architecture of the root system and in symbiotic interactions in the model legume Medicago truncatula. Analyses with promoter-GUS fusions suggested that the mtr-miR396a and miR396b genes are highly expressed in root tips, preferentially in the transition zone, and display distinct expression profiles during lateral root and nodule development. Transgenic roots of composite plants that over-express the miR396b precursor showed lower expression of six growth-regulating factor genes (MtGRF) and two bHLH79-like target genes, as well as reduced growth and mycorrhizal associations. miR396 inactivation by mimicry caused contrasting tendencies, with increased target expression, higher root biomass and more efficient colonization by arbuscular mycorrhizal fungi. In contrast to MtbHLH79, repression of three GRF targets by RNA interference severely impaired root growth. Early activation of mtr-miR396b, concomitant with post-transcriptional repression of MtGRF5 expression, was also observed in response to exogenous brassinosteroids. Growth limitation in miR396 over-expressing roots correlated with a reduction in cell-cycle gene expression and the number of dividing cells in the root apical meristem. These results link the miR396 network to the regulation of root growth and mycorrhizal associations in plants. PMID:23566016 Bazin, Jérémie; Khan, Ghazanfar Abbas; Combier, Jean-Philippe; Bustos-Sanmamed, Pilar; Debernardi, Juan Manuel; Rodriguez, Ramiro; Sorin, Céline; Palatnik, Javier; Hartmann, Caroline; Crespi, Martin; Lelandais-Brière, Christine 2013-06-01 210 SciTech Connect DOE Order 5000.3A, Occurrence Reporting and Processing of Operations Information,'' requires the investigation and reporting of occurrences (including the performance of root cause analysis) and the selection, implementation, and follow-up of corrective actions. The level of effort expended should be based on the significance attached to the occurrence. Most off-normal occurrences need only a scaled-down effort while most emergency occurrences should be investigated using on or more of the formal analytical models. A discussion of methodologies, instructions, and worksheets in this document guides the analysis of occurrences as specified by DOE Order 5000.3A. Not Available 1992-02-01 211 Microsoft Academic Search Light-induced inhibition of the elongation of primary roots of Zea mays seedlings is dependent upon the perception of light by the root cap. Separate exposure of detached root caps and roots from which root caps have been removed (i.e. decapped roots) to white light or darkness has shown that the elongation of a dark-exposed root to which a light-exposed root Henry Wilkins; R. L. Wain 1974-01-01 212 PubMed Resource exploitation of patches is influenced not simply by the rate of root production in the patches but also by the lifespan of the roots inhabiting the patches. We examined the effect of sustained localized nitrogen (N) fertilization on root lifespan in four tree species that varied widely in root morphology and presumed foraging strategy. The study was conducted in a 12-year-old common garden in central Pennsylvania using a combination of data from minirhizotron and root in-growth cores. The two fine-root tree species, Acer negundo L. and Populus tremuloides Michx., exhibited significant increases in root lifespan with local N fertilization; no significant responses were observed in the two coarse-root tree species, Sassafras albidum Nutt. and Liriodendron tulipifera L. Across species, coarse-root tree species had longer median root lifespan than fine-root tree species. Localized N fertilization did not significantly increase the N concentration or the respiration of the roots growing in the N-rich patch. Our results suggest that some plant species appear to regulate the lifespan of different portions of their root system to improve resource acquisition while other species do not. Our results are discussed in the context of different strategies of foraging of nutrient patches in species of different root morphology. PMID:24128849 Adams, Thomas S; McCormack, M Luke; Eissenstat, David M 2013-09-01 213 PubMed The architecture of a root system plays a major role in determining how efficiently a plant can capture water and nutrients from the soil. Growth occurs at the root tips and the process of exploring the soil volume depends on the behaviour of large numbers of individual root tips at different orders of branching. Each root tip is equipped with a battery of sensory mechanisms that enable it to respond to a range of environmental signals, including nutrients, water potential, light, gravity and touch. We have previously identified a MADS (MCM1, agamous, deficiens and SRF) box gene (ANR1) in Arabidopsis thaliana that is involved in modulating the rate of lateral root growth in response to changes in the external NO(3)(-) supply. Transgenic plants have been generated in which a constitutively expressed ANR1 protein can be post-translationally activated by treatment with dexamethasone (DEX). When roots of these lines are treated with DEX, lateral root growth is markedly stimulated but there is no effect on primary root growth, suggesting that one or more components of the regulatory pathway that operate in conjunction with ANR1 in lateral roots may be absent in the primary root tip. We have recently observed some very specific effects of low concentrations of glutamate on root growth, resulting in significant changes in root architecture. Experimental evidence suggests that this response involves the sensing of extracellular glutamate by root tip cells. We are currently investigating the possible role of plant ionotropic glutamate receptors in this sensory mechanism. PMID:15667327 Filleur, S; Walch-Liu, P; Gan, Y; Forde, B G 2005-02-01 214 SciTech Connect X-ray photoelectron spectroscopy (XPS) has been used to analyze root surface changes when Dayton barley (Hordeum vulgare) (Al tolerant) and Kearney barley (Al sensitive) seedlings were grown in nutrient solution in the presence and absence of 37.0 micromolar Al. The electron spectra from root surfaces contained strong lines in order of decreasing intensity from organic forms of carbon, oxygen, and nitrogen and weak lines due to inorganic elements in the form of anions and cations on the surface. The surface composition of root tips from Kearney was C, 65.6%; 0, 26.8%; N, 4.4% and tips from Dayton was C, 72.7%; O, 23.6%; N, 1.9%, grown in the absence of aluminum. Electron lines characteristic of nitrate, potassium, chloride, phosphate were also present in the spectra from those roots. Dayton roots grown in the presence of 37.0 micromolar aluminum contained 2.1% aluminum while Kearney contained 1.3% aluminum. The ratio of aluminum to phosphate was close to 1.0. Dayton roots usually contained twice as much aluminum phosphate in the surface region as Kearney. Dayton may be less susceptible to Al toxic effects by accumulation of aluminum phosphate on the root surface which then acts as a barrier to the transport of aluminum into the interior of the roots. Millard, M.M.; Foy, C.D.; Coradetti, C.A.; Reinsel, M.D. (Department of Agriculture, Beltsville, MD (USA)) 1990-06-01 215 NASA Technical Reports Server (NTRS) Orientation of root growth on earth and under microgravity conditions can possibly be controlled by hydrotropism--growth toward a moisture source in the absence of or reduced gravitropism. A porous-tube water delivery system being used for plant growth studies is appropriate for testing this hypothesis since roots can be grown aeroponically in this system. When the roots of the agravitropic mutant pea ageotropum (Pisum sativum L.) were placed vertically in air of 91% relative humidity and 2 to 3 mm from the water-saturated porous tube placed horizontally, the roots responded hydrotropically and grew in a continuous arch along the circular surface of the tube. By contrast, normal gravitropic roots of Alaska' pea initially showed a slight transient curvature toward the tube and then resumed vertical downward growth due to gravitropism. Thus, in microgravity, normal gravitropic roots could respond to a moisture gradient as strongly as the agravitropic roots used in this study. Hydrotropism should be considered a significant factor responsible for orientation of root growth in microgravity. Takahashi, H.; Brown, C. S.; Dreschel, T. W.; Scott, T. K.; Knott, W. M. (Principal Investigator) 1992-01-01 216 Microsoft Academic Search The role played by lateral roots and root hairs in promoting plant anchorage, and specifically resist- ance to vertical uprooting forces has been deter- mined experimentally. Two species were studied, Allium cepa (onion) which has a particularly simple root system and two mutants of Arabidopsis thaliana, one without root hairs (rhd 2-1) and another with reduced lateral root branching (axr Peter H. J. Bailey; J. D. Currey; A. H. Fitter 2002-01-01 217 PubMed Entomophthoromycosis due to Conidiobolus coronatus is a granulomatous infection characterized by lesions that originate in the inferior turbinate, spread through ostia and foramina to involve the facial and subcutaneous tissues and paranasal sinuses. The majority of the cases have been described from areas of tropical rainforest in West Africa, agricultural and outdoor workers (aged 20-60 years) being the ones most frequently affected. The fungus is common in soil and decaying vegetation. Infection probably occurs by implantation of the spores of the fungus in nasal mucosa. C. incongruus is a rare agent of the disease, so far known only from two cases with lesions involving the pericardium, mediastinum, lungs, liver, oesophagus and jejunum. C. coronatus is known to cause a clinically similar disease in horses, mules, a dolphin and a chimpanzee. A characteristic histological feature is the presence of thin-walled, broad, often septate hyphae or hyphal fragments with a thick eosinophilic sheath, frequently phagocytosed within giant cells. The fungus is known to produce in vitro several enzymes, e.g., elastase, esterase, collagenase and lipase, which have a possible role in pathogenicity. A concentrated brain heart infusion culture filtrate antigen is useful for immunodiagnosis. Several drugs e.g., potassium iodide, cotrimoxazole, amphotericin B, ketoconazole and itraconazole have been tried with varying success. Investigations on the immunology of disease and the role of proteases and lipases in the pathogenesis of infection is an important area of further research. PMID:1397203 Gugnani, H C 1992-05-01 218 PubMed Central Background and Aims The mobile carbon supply to different compartments of a tree is affected by climate, but its impact on cell-wall chemistry and mechanics remains unknown. To understand better the variability in root growth and biomechanics in mountain forests subjected to substrate mass movement, we investigated root chemical and mechanical properties of mature Abies georgei var. smithii (Smith fir) growing at different elevations on the Tibet–Qinghai Plateau. Methods Thin and fine roots (0·1–4·0 mm in diameter) were sampled at three different elevations (3480, 3900 and 4330 m, the last corresponding to the treeline). Tensile resistance of roots of different diameter classes was measured along with holocellulose and non-structural carbon (NSC) content. Key Results The mean force necessary to break roots in tension decreased significantly with increasing altitude and was attributed to a decrease in holocellulose content. Holocellulose was significantly lower in roots at the treeline (29·5 ± 1·3 %) compared with those at 3480 m (39·1 ± 1·0 %). Roots also differed significantly in NSC, with 35·6 ± 4·1 mg g?1 dry mass of mean total soluble sugars in roots at 3480 m and 18·8 ± 2·1 mg g?1 dry mass in roots at the treeline. Conclusions Root mechanical resistance, holocellulose and NSC content all decreased with increasing altitude. Holocellulose is made up principally of cellulose, the biosynthesis of which depends largely on NSC supply. Plants synthesize cellulose when conditions are optimal and NSC is not limiting. Thus, cellulose synthesis in the thin and fine roots measured in our study is probably not a priority in mature trees growing at very high altitudes, where climatic factors will be limiting for growth. Root NSC stocks at the treeline may be depleted through over-demand for carbon supply due to increased fine root production or winter root growth. PMID:21186240 Genet, Marie; Li, Mingcai; Luo, Tianxiang; Fourcaud, Thierry; Clement-Vidal, Anne; Stokes, Alexia 2011-01-01 219 SciTech Connect Sensing in the roots of higher plants has long been recognized to be restricted mainly to gravitropism and thigmotropism. However, root responses to temperature gradients have not been extensively studied. We have designed experiments under controlled conditions to test if and how root direction of maize can be altered by thermal gradients perpendicular to the gravity vector. Primary roots of maize grown on agar plates exhibit positive thermotropism (curvature toward the warmer temperature) when exposed to gradients of 0.5 to 4.2{degree}C cm{sup {minus}1}. The extent of thermotropism depends on the temperature gradient and the temperature at which the root is placed within the gradient. The curvature cannot be accounted for by differential growth as a direct effect of temperature on each side of the root. Fortin, M.-C.; Poff, K.L. (MSU-DOE Plant Research Laboratory, East Lansing, MI (USA)) 1990-05-01 220 Microsoft Academic Search Flow cytometry and terminal deoxynucleotidyl transferase-mediated biotinylated uridine triphosphate nick end-labelling (TUNEL) immunohistochemistry have been used to assess cell death in the dorsal root ganglia (DRG) or spinal cord 1, 2 or 14 days after multiple lumbar dorsal root rhizotomy or dorsal root avulsion injury in adult rats. Neither injury induced significant cell death in the DRG compared to sham-operated Daniel J. Chew; Veronica H. L. Leinster; Mathuri Sakthithasan; Lesley G. Robson; Thomas Carlstedt; Peter J. Shortland 2008-01-01 221 Microsoft Academic Search \\u000a Of all the economically important plant parasitic nematodes, root-knot nematodes (Meloidogyne species) are amongst the most widespread, the best recognized and most widely studied. This is partly because infected roots\\u000a develop galls where the nematodes feed, which with severe infection give roots a ‘knotted’ appearance. They have a remarkably\\u000a wide host range, and are ubiquitous especially in tropical and sub-tropical Michael G. K. Jones; Derek B. Goto 222 PubMed Central Physicians in primary care recognize that as many as 65 percent of the patients seen in their offices are there for psychological reasons. In any southern town with a moderate population of blacks, there are at least two “root doctors.” These root doctors have mastered the power of autosuggestion and are treating these patients with various forms of medication and psychological counseling. This paper updates the practicing physician on root doctors who practice primary care. PMID:6887277 Stitt, Van J. 1983-01-01 223 Microsoft Academic Search BackgroundEcologically meaningful classification of bacterial populations is essential for understanding the structure and function of bacterial communities. As in soils, the ecological strategy of the majority of root-colonizing bacteria is mostly unknown. Among those are Massilia (Oxalobacteraceae), a major group of rhizosphere and root colonizing bacteria of many plant species.Methodology\\/Principal FindingsThe ecology of Massilia was explored in cucumber root and Maya Ofek; Yitzhak Hadar; Dror Minz 2012-01-01 224 PubMed Cleaning and shaping are important steps in the root canal treatment. Despite the technological advances in endodontics, K and Hedstroen files are still widely used. In an attempt to be more effective in preparing the root canals, faster and more cutting efficient kinematic, alloys and design alternatives utilizing mechanically oscillating or rotary files are proposed. Even with all these technological innovating alternatives, the preparation of root canals remains a challenge. PMID:23579914 Leonardo, Renato de Toledo; Puente, Carlos Garcia; Jaime, Alejandro; Jent, Carol 2013-01-01 225 E-print Network Given a graph and a root, the Maximum Bounded Rooted-Tree Packing (MBRTP) problem aims at finding K rooted-trees that span the largest subset of vertices, when each vertex has a limited outdegree. This problem is motivated by peer-to-peer streaming overlays in under-provisioned systems. We prove that the MBRTP problem is NP-complete. We present two polynomial-time algorithms that computes an optimal solution on complete graphs and trees respectively. Kerivin, Herve; Simon, Gwendal; Zhou, Fen 2011-01-01 226 PubMed Central A root pressure probe has been used to measure the root pressure (Pr) exerted by excised main roots of young maize plants (Zea Mays L.). Defined gradients of hydrostatic and osmotic pressure could be set up between root xylem and medium to induce radial water flows across the root cylinder in both directions. The hydraulic conductivity of the root (Lpr) was evaluated from root pressure relaxations. When permeating solutes were added to the medium, biphasic root pressure relaxations were observed with water and solute phases and root pressure minima (maxima) which allowed the estimation of permeability (PSr) and reflection coefficients (?sr) of roots. Reflection coefficients were: ethanol, 0.27; mannitol, 0.74; sucrose, 0.54; PEG 1000, 0.82; NaCl, 0.64; KNO3, 0.67, and permeability coefficients (in 10?8 meters per second): ethanol, 4.7; sucrose, 1.6; and NaCl, 5.7. Lpr was very different for osmotic and hydrostatic gradients. For hydrostatic gradients Lpr was 1·10?7 meters per second per megapascal, whereas in osmotic experiments the hydraulic conductivity was found to be an order of magnitude lower. For hydrostatic gradients, the exosmotic Lpr was about 15% larger than the endosmotic, whereas in osmotic experiments the polarity in the water movement was reversed. These results either suggest effects of unstirred layers at the osmotic barrier in the root, an asymmetrical barrier, and/or mechanical effects. Measurements of the hydraulic conductivity of individual root cortex cells revealed an Lp similar to Lpr (hydrostatic). It is concluded that, in the presence of external hydrostatic gradients, water moves primarily in the apoplast, whereas in the presence of osmotic gradients this component is much smaller in relation to the cell-to-cell component (symplasmic plus transcellular transport). PMID:16665588 Steudle, Ernst; Oren, Ram; Schulze, Ernst-Detlef 1987-01-01 227 Microsoft Academic Search Cluster roots are an adaptation for nutrient acquisition from nutrient-poor soils. They develop on root systems of a range\\u000a of species belonging to a number of different families (e.g., Proteaceae, Casuarinaceae, Fabaceae and Myricaceae) and are\\u000a also found on root systems of some crop species (e.g., albus, Macadamia integrifoliaandCucurbita pepo). Their morphology is variable but typically, large numbers of determinate Michael W. Shane; Hans Lambers 2005-01-01 228 PubMed Central The root-to-root travel of the beneficial bacterium Azospirillum brasilense on wheat and soybean roots in agar, sand, and light-textured soil was monitored. We used a motile wild-type (Mot+) strain and a motility-deficient (Mot-) strain which was derived from the wild-type strain. The colonization levels of inoculated roots were similar for the two strains. Mot+ cells moved from inoculated roots (either natural or artificial roots in agar, sand, or light-textured soil) to noninoculated roots, where they formed a band-type colonization composed of bacterial aggregates encircling a limited part of the root, regardless of the plant species. The Mot- strain did not move toward noninoculated roots of either plant species and usually stayed at the inoculation site and root tips. The effect of attractants and repellents was the primary factor governing the motility of Mot+ cells in the presence of adequate water. We propose that interroot travel of A. brasilense is an essential preliminary step in the root-bacterium recognition mechanism. Bacterial motility might have a general role in getting Azospirillum cells to the site where firmer attachment favors colonization of the root system. Azospirillum travel toward plants is a nonspecific active process which is not directly dependent on nutrient deficiency but is a consequence of a nonspecific bacterial chemotaxis, influenced by the balance between attractants and possibly repellents leaked by the root. PMID:16349297 Bashan, Yoav; Holguin, Gina 1994-01-01 229 NASA Technical Reports Server (NTRS) The root cap is increasingly appreciated as a complex and dynamic plant organ. Root caps sense and transmit environmental signals, synthesize and secrete small molecules and macromolecules, and in some species shed metabolically active cells. However, it is not known whether root caps are essential for normal shoot and root development. We report the identification of a root cap-specific promoter and describe its use to genetically ablate root caps by directing root cap-specific expression of a diphtheria toxin A-chain gene. Transgenic toxin-expressing plants are viable and have normal aerial parts but agravitropic roots, implying loss of root cap function. Several cell layers are missing from the transgenic root caps, and the remaining cells are abnormal. Although the radial organization of the roots is normal in toxin-expressing plants, the root tips have fewer cytoplasmically dense cells than do wild-type root tips, suggesting that root meristematic activity is lower in transgenic than in wild-type plants. The roots of transgenic plants have more lateral roots and these are, in turn, more highly branched than those of wild-type plants. Thus, root cap ablation alters root architecture both by inhibiting root meristematic activity and by stimulating lateral root initiation. These observations imply that the root caps contain essential components of the signaling system that determines root architecture. Tsugeki, R.; Fedoroff, N. V. 1999-01-01 230 PubMed Central Root system growth and development is highly plastic and is influenced by the surrounding environment. Roots frequently grow in heterogeneous environments that include interactions from neighboring plants and physical impediments in the rhizosphere. To investigate how planting density and physical objects affect root system growth, we grew rice in a transparent gel system in close proximity with another plant or a physical object. Root systems were imaged and reconstructed in three dimensions. Root–root interaction strength was calculated using quantitative metrics that characterize the extent to which the reconstructed root systems overlap each other. Surprisingly, we found the overlap of root systems of the same genotype was significantly higher than that of root systems of different genotypes. Root systems of the same genotype tended to grow toward each other but those of different genotypes appeared to avoid each other. Shoot separation experiments excluded the possibility of aerial interactions, suggesting root communication. Staggered plantings indicated that interactions likely occur at root tips in close proximity. Recognition of obstacles also occurred through root tips, but through physical contact in a size-dependent manner. These results indicate that root systems use two different forms of communication to recognize objects and alter root architecture: root-root recognition, possibly mediated through root exudates, and root-object recognition mediated by physical contact at the root tips. This finding suggests that root tips act as local sensors that integrate rhizosphere information into global root architectural changes. PMID:23362379 Fang, Suqin; Clark, Randy T.; Zheng, Ying; Iyer-Pascuzzi, Anjali S.; Weitz, Joshua S.; Kochian, Leon V.; Edelsbrunner, Herbert; Liao, Hong; Benfey, Philip N. 2013-01-01 231 PubMed Central Summary Cell fate in the Arabidopsis root is determined by positional information mediated by plant hormones and interpreted by transcriptional networks. In this review, we summarize recent advances in our understanding of the regulatory networks that control cell fate within the root meristem, and in the interplay of these networks with phytohormones. Recent work describing the importance of chromatin organization in tissue patterning is also highlighted. A new, high resolution root expression map detailing the transciptome of nearly all cell types in the Arabidopsis root across developmental timepoints will provide a framework for understanding these networks. PMID:18973837 Iyer-Pascuzzi, Anjali S.; Benfey, Philip N. 2009-01-01 232 E-print Network the growing season, Take-all Root Rot of Turfgrass Joseph P. Krausz* L-5170 4-05 *Professor and Extension Program Leader for Plant Pathology, The Texas A&M University System. Characteristic infection pads (hypho - podia) of the take-all root rot fungus... the growing season, Take-all Root Rot of Turfgrass Joseph P. Krausz* L-5170 4-05 *Professor and Extension Program Leader for Plant Pathology, The Texas A&M University System. Characteristic infection pads (hypho - podia) of the take-all root rot fungus... Krausz, Joseph P. 2005-04-21 233 NASA Astrophysics Data System (ADS) Evaporation of water out of a soil involves complicated and well-debated mechanisms. When plant roots are added into the soil, water transfer between the soil and the outside environment is even more complicated. Indeed, plants provide an additional process of water transfer. Water is pumped by the roots, channeled to the leaf surface, and released into the surrounding air by a process called transpiration. Prediction of the evapotranspiration of water over time in the presence of roots helps keep track of the amount of water that remains in the soil. Using a controlled visual setup of a two-dimensional model soil consisting of monodisperse glass beads, we perform experiments on actual roots grown under different relative humidity conditions. We record the total water mass loss in the medium and the position of the evaporating front that forms within the medium. We then develop a simple analytical model that predicts the position of the evaporating front as a function of time as well as the total amount of water that is lost from the medium due to the combined effects of evaporation and transpiration. The model is based on fundamental principles of evaporation fluxes and includes empirical assumptions on the quantity of open stomata in the leaves, where water transpiration occurs. Comparison between the model and experimental results shows excellent prediction of the position of the evaporating front as well as the total mass loss from evapotranspiration in the presence of roots. The model also provides a way to predict the lifetime of a plant. Cejas, Cesare M.; Hough, L. A.; Castaing, Jean-Christophe; Frétigny, Christian; Dreyfus, Rémi 2014-10-01 234 EPA Science Inventory Storage carbohydrates are extremely important for new shoot and root development following dormancy or during periods of high stress. he hypothesis that ozone decreases carbohydrate storage and decreases new root growth during the year following exposure was investigated. eedling... 235 SciTech Connect Root Cause Analysis (RCA) identifies the cause of an adverse condition that, if corrected, will preclude recurrence or greatly reduce the probability of recurrence of the same or similar adverse conditions and thereby protect the health and safety of the public, the workers, and the environment. This procedure sets forth the requirements for management determination and the selection of RCA methods and implementation of RCAs that are a result of significant findings from Price-Anderson Amendments Act (PAAA) violations, occurrences/events, Significant Adverse Conditions, and external oversight Corrective Action Requests (CARs) generated by the Office of Enforcement (PAAA headquarters), the U.S. Environmental Protection Agency, and other oversight entities against Lawrence Berkeley National Laboratory (LBNL). Performance of an RCA may result in the identification of issues that should be reported in accordance with the Issues Management Program Manual. Gravois, Melanie C. 2007-05-02 236 DOEpatents In accordance with this invention, a porous sheet material is provided at intervals with bodies of a polymer which contain a 2,6-dinitroaniline. The sheet material is made porous to permit free passage of water. It may be either a perforated sheet or a woven or non-woven textile material. A particularly desirable embodiment is a non-woven fabric of non-biodegradable material. This type of material is known as a "geotextile" and is used for weed control, prevention of erosion on slopes, and other landscaping purposes. In order to obtain a root repelling property, a dinitroaniline is blended with a polymer which is attached to the geotextile or other porous material. Burton, Frederick G. (Stansbury Park, UT); Cataldo, Dominic A. (Kennewick, WA); Cline, John F. (Prosser, WA); Skiens, W. Eugene (Wilsonville, OR); Van Voris, Peter (Richland, WA) 1993-01-01 237 PubMed Trauma or infection to the primary tooth may have deleterious effects on the underlying developing tooth buds. Anatomically the root apices of primary teeth are in close proximity to the developing permanent tooth buds; hence spread of infection originating from pulp necrosis of primary tooth may not only affect the underlying tooth bud but may also affect the adjacent tooth buds. The extent of malformation depends on the developmental stage of tooth or the age of patient. Presented here is a rare case of complete arrest of maxillary first permanent molar root growth due to spread of periapical infection originating from second primary molar leading to failure of its eruption and finally extraction. Histopathlogical analysis revealed compound odontoma associated with maxillary first permanent molar. PMID:23832997 Gunda, Sachin A; Patil, Anil; Varekar, Aniruddha 2013-01-01 238 PubMed Central Background and Aims Most studies of exodermal structure and function have involved species with a uniseriate exodermis. To extend this work, the development and apoplastic permeability of Iris germanica roots with a multiseriate exodermis (MEX) were investigated. The effects of different growth conditions on MEX maturation were also tested. In addition, the exodermises of eight Iris species were observed to determine if their mature anatomy correlated with habitat. Methods Plants were grown in soil, hydroponics (with and without a humid air gap) or aeroponics. Roots were sectioned and stained with various dyes to detect MEX development from the root apical meristem, Casparian bands, suberin lamellae and tertiary wall thickenings. Apoplastic permeability was tested using dye (berberine) and ionic (ferric) tracers. Key Results The root apical meristem was open and MEX development non-uniform. In soil-grown roots, the exodermis started maturing (i.e. Casparian bands and suberin lamellae were deposited) 10 mm from the tip, and two layers had matured by 70 mm. In both hydro- and aeroponically grown roots, exodermal maturation was delayed. However, in areas of roots exposed to an air gap in the hydroponic system, MEX maturation was accelerated. In contrast, maturation of the endodermis was not influenced by the growth conditions. The mature MEX had an atypical Casparian band that was continuous around the root circumference. The MEX prevented the influx and efflux of berberine, but had variable resistance to ferric ions due to their toxic effects. Iris species living in well-drained soils developed a MEX, but species in water-saturated substrates had a uniseriate exodermis and aerenchyma. Conclusions MEX maturation was influenced by the roots' growth medium. The MEX matures very close to the root tip in soil, but much further from the tip in hydro- and aeroponic culture. The air gap accelerated maturation of the second exodermal layer. In Iris, the type of exodermis was correlated with natural habitat suggesting that a MEX may be advantageous for drought tolerance. PMID:19151041 Meyer, Chris J.; Seago, James L.; Peterson, Carol A. 2009-01-01 239 Microsoft Academic Search Fine root lifespan and turnover play an important role in carbon allocation and nutrient cycling in forest ecosystems. Fine\\u000a roots are typically defined as less than 1 or 2 mm in diameter. However, when categorizing roots by this diameter size, the\\u000a position of an individual root on the complex lateral branching pattern has often been ignored, and our knowledge about Xiangrong Wang; Zhengquan Wang; Youzhi Han; Jiacun Gu; Dali Guo; Li Mei 2007-01-01 240 E-print Network CHEMICAL ROOT PRUNING AND ITS EFFECTS ON WATER RELATIONS AND ROOT MORPHOLOGY OF PHOT1IVIA A Thesis by DIPTISH RAMESH VARTAK Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1993 Major Subject: Agricultural Engineering CHEMICAL ROOT PRUNING AND ITS EFFECTS ON WATER RELATIONS AND ROOT MORPHOLOGY OF PHOTJIVIA A Thesis by DIPTISH RAMESH VARTAK Submitted to Texas A&M University... Vartak, Diptish Ramesh 2012-06-07 241 Microsoft Academic Search Lowered temperatures may reduce the root water uptake of tropical trees at high elevations through several mechanisms; however, field studies to test their relevance are lacking. We measured sap flux density (J) in small-diameter tree roots across a 2000-m elevation transect in a tropical mountain forest for quantifying the effects of temperature (Ta), VPD and soil moisture (?) on root Sophie Graefe; Christoph Leuschner; Heinz Coners; Dietrich Hertel 2011-01-01 242 E-print Network and clonal forestry systems are reviewed. Three quantitative rooting experiments were conductedi EFFECTS OF HEDGING ON MATURATION IN LOBLOLLY PINE: ROOTING CAPACITY AND ROOT FORMATION By Andreas State University of New York College of Environmental Science and Forestry Syracuse, New York January Hamann, Andreas 243 Microsoft Academic Search The purpose of this study was to undertake a comprehensive literature review of the root and root canal morphology of the mandibular first premolar. Published studies citing the anatomy and morphology of mandibular premolars report data for over 6,700 teeth. These studies were divided into anatomical studies reporting number of roots, number of canals, and apical morphology. Variations because of Blaine M. Cleghorn; William H. Christie; Cecilia C. S. Dong 2007-01-01 244 Microsoft Academic Search mineralization enhancement of 23% compared with ace- tate-fed controls (Burken and Schnoor, 1996). Parathion To investigate the mechanisms by which slender oat (Avena barbata mineralization was also stimulated in soils amended with Pott ex Link) enhances phenanthrene biodegradation, we analyzed the impacts of root exudates and root debris on phenanthrene biodeg- root exudates, but greater stimulation resulted from the radation Ryan K. Miya; Mary K. Firestone 2001-01-01 245 NASA Astrophysics Data System (ADS) A simple macroscopic vertically distributed plant root water uptake (RWU) model based on traditional water-potential-gradient formulation (Vogel et al., 2013), in which the uptake rates are directly proportional to the potential gradient and indirectly proportional to the local soil and root resistances to water flow, was tested. This RWU modeling approach was implemented in a one-dimensional dual-continuum model of soil water flow based on Richards' equation and used to simulate soil water distribution changes during a vegetation season at a forest site located in a temperate humid climate of central Europe. The main objectives were to test the ability of the presented RWU model to simulate the observed soil-plant-atmosphere interactions, and to examine the differences between empirical and more physically-based RWU modeling approaches (accommodated in the same soil water flow model). The tested RWU model was capable of simulating both the compensatory root water uptake, in situations when reduced uptake from dry layers was compensated for by increased uptake from wetter layers, and the root-mediated hydraulic redistribution of soil water, contributing to more natural soil moisture distribution throughout the root zone. Comparison of the model results with the sap flow observed reveals some limitations related to the quasi-steady-state assumption for the plant xylem and zero transpiration rates prescribed during nights and precipitation. This stated, the model seems to simulate adequately both the regular nightly hydraulic redistribution, due to reduced night transpiration, and the episodic daytime hydraulic redistribution during wet canopy events. The model results were compared to simulations produced using the semi-empirical RWU model of Feddes. Based on both an improved agreement between the observed and simulated soil water pressure responses to daily variations of transpiration, and a more realistic seasonal distribution of the transpiration rate reduction, we concluded that the physically based root water uptake model with negative RWU rates enabled substantially better approximation of the soil water extraction by spruce trees under moderate water scarcity. Vogel T., M. Dohnal, J. Dusek, J. Votrubova, and M. Tesar. 2013. Macroscopic modeling of plant water uptake in a forest stand involving root-mediated soil-water redistribution. Vadose Zone Journal, accepted. Votrubova, Jana; Vogel, Tomas; Dohnal, Michal; Dusek, Jaromir; Tesar, Miroslav 2013-04-01 246 NASA Technical Reports Server (NTRS) The overall purpose of this experiment was to study how cress roots respond to a withdrawal of a gravity stimulus i.e. when and how much the roots straighten (autotropism) after curving (gravitropism). This question was studied both in extensive ground-based research and in microgravity on BioRack. Sack, Fred D. 1998-01-01 247 EPA Science Inventory Minirhizotrons provide a nondestructive, in situ method for directly viewing and studying fine roots. Although many insights into fine roots have been gained using minirhizotrons, it is clear from the literature that there is still wide variation in how minirhizotrons and minirhi... 248 PubMed Four new compounds (+)-jasminoids A, B, C, and D, together with seven known compounds, were isolated from the roots of Jasminum sambac. Their structures were identified using spectroscopic methods. This study provides a better understanding to the chemical composition of J. sambac roots that have been thought to be one ingredient of an ancient prescription 'Ma-Fei-San'. PMID:23134371 Zeng, Lin-Hong; Hu, Min; Yan, Yong-Ming; Lu, Qing; Cheng, Yong-Xian 2012-01-01 249 EPA Science Inventory Seagrasses are adapted to being rooted in reduced, anoxic sediments with high rates of sulfate reduction. During the day, an oxygen gradient is generated around the roots, becoming anoxic at night. Thus, obligate anaerobic bacteria in the rhizosphere have to tolerate elevated oxy... 250 Microsoft Academic Search Shallow landslides are a significant hazard in steep, soil-mantled landscapes. During intense rainfall events, the distribution of shallow landslides is controlled by variations in landscape gradient, the frictional and cohesive properties of soil and roots, and the subsurface hydrologic response. While gradients can be estimated from digital elevation models, information on soil and root properties remains sparse. We investigated whether T. C. Hales; C. R. Ford; T. Hwang; J. M. Vose; L. E. Band 2009-01-01 251 Microsoft Academic Search This paper proposes unit root tests for dynamic heterogeneous panels based on the mean of individual unit root statistics. In particular it proposes a standardized t-bar test statistic based on the (augmented) Dickey–Fuller statistics averaged across the groups. Under a general setting this statistic is shown to converge in probability to a standard normal variate sequentially with T (the time Kyung So Im; M. Hashem Pesaran; Yongcheol Shin 2003-01-01 252 Microsoft Academic Search Root Kits are tool boxes containing a collection of highly skilled tools for attacking computer systems. Their algorithms and databases contain professional knowledge about methods and mecha- nisms for completely automated attacks both over a network as well as from within a system. Root kits attack by maneuvering a system into executing a script with supervisor privileges. Once having g~ned Winfried E. Kfihnhauser 253 Microsoft Academic Search Root Kits are tool boxes containing a collection of highly skilled tools for attacking computer systems. Their algorithms and databases contain professional knowledge about methods and mechanisms for completely automated attacks both over a network as well as from within a system. Root kits attack by maneuvering a system into executing a script with supervisor privileges. Once having gained full Winfried E. Kfihnhauser 2004-01-01 254 E-print Network Square Root SAM Simultaneous Localization and Mapping via Square Root Information Smoothing Frank Solving the SLAM problem is one way to enable a robot to explore, map, and navigate in a previously of these methods as an alternative to EKF-based approaches. 1 Introduction The problem of simultaneous localization Leonard, John J. 255 NASA Technical Reports Server (NTRS) The anatomy and fine structure of roots from oat and mung bean seedlings, grown under microgravity conditions for 8 days aboard the Space Shuttle, was examined and compared to that of roots from ground control plants grown under similar conditions. Roots from both sets of oat seedlings exhibited characteristic monocotyledonous tissue organization and normal ultrastructural features, except for cortex cell mitochondria, which exhibited a 'swollen' morphology. Various stages of cell division were observed in the meristematic tissues of oat roots. Ground control and flight-grown mung bean roots also showed normal tissue organization, but root cap cells in the flight-grown roots were collapsed and degraded in appearance, especially at the cap periphery. At the ultrastructural level, these cells exhibited a loss of organelle integrity and a highly-condensed cytoplasm. This latter observation perhaps suggests a differing tissue sensitivity for the two species to growth conditions employed in space flight. The basis for abnormal root cap cell development is not understood, but the loss of these putative gravity-sensing cells holds potential significance for long term plant growth orientation during space flight. Slocum, R. D.; Gaynor, J. J.; Galston, A. W. 1984-01-01 256 PubMed Central This special issue is dedicated to root biologists past and present who have been exploring all aspects of root structure and function with an extensive publication record going over 100 years. The content of the Special Issue on Root Biology covers a wide scale of contributions, spanning interactions of roots with microorganisms in the rhizosphere, the anatomy of root cells and tissues, the subcellular components of root cells, and aspects of metal accumulation and stresses on root function and structure. We have organized the papers into three topic categories: (1) root ecology, interactions with microbes, root architecture and the rhizosphere; (2) experimental root biology, root structure and physiology; and (3) applications of new technology to study root biology. Finally, we will speculate on root research for the future. PMID:22966495 Lux, Alexander; Rost, Thomas L. 2012-01-01 257 PubMed Root branching is critical for plants to secure anchorage and ensure the supply of water, minerals, and nutrients. To date, research on root branching has focused on lateral root development in young seedlings. However, many other programs of postembryonic root organogenesis exist in angiosperms. In cereal crops, the majority of the mature root system is composed of several classes of adventitious roots that include crown roots and brace roots. In this Update, we initially describe the diversity of postembryonic root forms. Next, we review recent advances in our understanding of the genes, signals, and mechanisms regulating lateral root and adventitious root branching in the plant models Arabidopsis (Arabidopsis thaliana), maize (Zea mays), and rice (Oryza sativa). While many common signals, regulatory components, and mechanisms have been identified that control the initiation, morphogenesis, and emergence of new lateral and adventitious root organs, much more remains to be done. We conclude by discussing the challenges and opportunities facing root branching research. PMID:25136060 Atkinson, Jonathan A; Rasmussen, Amanda; Traini, Richard; Voß, Ute; Sturrock, Craig; Mooney, Sacha J; Wells, Darren M; Bennett, Malcolm J 2014-10-01 258 PubMed Analysis of genes preferentially expressed in hairy roots caused by infection with Agrobacterium rhizogenes has provided insights into the regulation of lateral root formation. A hairy root preferential cDNA, HR7, has been cloned from hairy roots of Hyoscyamus niger. HR7 encodes a novel protein partially homologous to a metallocarboxypeptidase inhibitor and is expressed exclusively in the primordium and base of lateral roots in hairy roots. Overexpression of HR7 in transgenic roots of H. niger dramatically enhances the frequency of lateral root formation. The results of this study indicate that expression of HR7 plays a critical role in initiating lateral root formation. PMID:10356981 Mikami, Y; Horiike, G; Kuroyanagi, M; Noguchi, H; Shimizu, M; Niwa, Y; Kobayashi, H 1999-05-14 259 PubMed Central Background Characterizing root system architecture (RSA) is essential to understanding the development and function of vascular plants. Identifying RSA-associated genes also represents an underexplored opportunity for crop improvement. Software tools are needed to accelerate the pace at which quantitative traits of RSA are estimated from images of root networks. Results We have developed GiA Roots (General Image Analysis of Roots), a semi-automated software tool designed specifically for the high-throughput analysis of root system images. GiA Roots includes user-assisted algorithms to distinguish root from background and a fully automated pipeline that extracts dozens of root system phenotypes. Quantitative information on each phenotype, along with intermediate steps for full reproducibility, is returned to the end-user for downstream analysis. GiA Roots has a GUI front end and a command-line interface for interweaving the software into large-scale workflows. GiA Roots can also be extended to estimate novel phenotypes specified by the end-user. Conclusions We demonstrate the use of GiA Roots on a set of 2393 images of rice roots representing 12 genotypes from the species Oryza sativa. We validate trait measurements against prior analyses of this image set that demonstrated that RSA traits are likely heritable and associated with genotypic differences. Moreover, we demonstrate that GiA Roots is extensible and an end-user can add functionality so that GiA Roots can estimate novel RSA traits. In summary, we show that the software can function as an efficient tool as part of a workflow to move from large numbers of root images to downstream analysis. PMID:22834569 2012-01-01 260 PubMed Alnus glutinosa is an important pioneer species that forms effective symbioses with Frankia and ecto and arbuscular mycorrhizal fungi (AMF). There is evidence that Frankia and AMF interact and the focus of this study was to investigate how interactions affected root system and root hair development. A. glutinosa seedlings were grown in pots in soil pre-inoculated with the AMF Gigaspora rosea. Seedlings were inoculated with Frankia either immediately on transfer to AMF-inoculated pots (day 0) on day 15 or on day 30 following AMF inoculation so the effect of timing of inoculation on interactions could be determined. Seedlings were harvested in batches at intervals of 10, 15, 20, 25 and 30 days after the commencement of each treatment. Both G. rosea and Frankia increased root branching and effects were greater when both were present. By contrast, both G. rosea and Frankia decreased root hair numbers markedly. Effects on root hair development were not a consequence of phosphorous, as P levels were not changed significantly in seedlings colonised by G. rosea or nodulated by Frankia. Effects are not due to differences in root system size but conceivably could offset some of the carbon costs incurred by the symbioses. PMID:19690898 Orfanoudakis, Michail; Wheeler, Christopher T; Hooker, John E 2010-02-01 261 DOEpatents A method and system for long-term control of root growth without killing the plants bearing those roots involves incorporating a 2,6-dinitroaniline in a polymer and disposing the polymer in an area in which root control is desired. This results in controlled release of the substituted aniline herbicide over a period of many years. Herbicides of this class have the property of preventing root elongation without translocating into other parts of the plant. The herbicide may be encapsulated in the polymer or mixed with it. The polymer-herbicide mixture may be formed into pellets, sheets, pipe gaskets, pipes for carrying water, or various other forms. The invention may be applied to other protection of buried hazardous wastes, protection of underground pipes, prevention of root intrusion beneath slabs, the dwarfing of trees or shrubs and other applications. The preferred herbicide is 4-difluoromethyl-N,N-dipropyl-2,6-dinitro-aniline, commonly known as trifluralin. Burton, Frederick G. (West Richland, WA); Cataldo, Dominic A. (Kennewick, WA); Cline, John F. (Prosser, WA); Skiens, W. Eugene (Richland, WA) 1992-05-26 262 PubMed Central Lead (Pb) is one of the most widespread heavy metal contaminant in soils. It is highly toxic to living organisms. Pb has no biological function but can cause morphological, physiological, and biochemical dysfunctions in plants. Plants have developed a wide range of tolerance mechanisms that are activated in response to Pb exposure. Pb affects plants primarily through their root systems. Plant roots rapidly respond either (i) by the synthesis and deposition of callose, creating a barrier that stops Pb entering (ii) through the uptake of large amounts of Pb and its sequestration in the vacuole accompanied by changes in root growth and branching pattern or (iii) by its translocation to the aboveground parts of plant in the case of hyperaccumulators plants. Here we review the interactions of roots with the presence of Pb in the rhizosphere and the effect of Pb on the physiological and biochemical mechanisms of root development. PMID:23750165 Fahr, Mouna; Laplaze, Laurent; Bendaou, Najib; Hocher, Valerie; Mzibri, Mohamed El; Bogusz, Didier; Smouni, Abdelaziz 2013-01-01 263 NASA Technical Reports Server (NTRS) Graviperception by plant roots is believed to occur via the sedimentation of amyloplasts in columella cells of the root cap. This physical stimulus results in an accumulation of calcium on the lower side of the cap, which in turn induces gravicurvature. In this paper we present a model for root gravitropism integrating gravity-induced changes in electrical potential, cytochemical localization of calcium in cells of gravistimulated roots, and the interdependence of calcium and auxin movement. Key features of the model are that 1) gravity-induced redistribution of calcium is an early event in the transduction mechanism, and 2) apoplastic movement of calcium through the root-cap mucilage may be an important component of the pathway for calcium movement. Moore, R.; Evans, M. L. 1986-01-01 264 PubMed Central The plant root system is essential for providing anchorage to the soil, supplying minerals and water, and synthesizing metabolites. It is a dynamic organ modulated by external cues such as environmental signals, water and nutrients availability, salinity and others. Lateral roots (LRs) are initiated from the primary root post-embryonically, after which they progress through discrete developmental stages which can be independently controlled, providing a high level of plasticity during root system formation. Within this review, main contributions are presented, from the classical forward genetic screens to the more recent high-throughput approaches, combined with computer model predictions, dissecting how LRs and thereby root system architecture is established and developed. PMID:24421783 Cuesta, Candela; Wabnik, Krzysztof; Benkova, Eva 2013-01-01 265 SciTech Connect A method and system for long-term control of root growth without killing the plants bearing those roots involves incorporating a 2,6-dinitroaniline in a polymer and disposing the polymer in an area in which root control is desired. This results in controlled release of the substituted aniline herbicide over a period of many years. Herbicides of this class have the property of preventing root elongation without translocating into other parts of the plant. The herbicide may be encapsulated in the polymer or mixed with it. The polymer-herbicide mixture may be formed into pellets, sheets, pipe gaskets, pipes for carrying water, or various other forms. The invention may be applied to other protection of buried hazardous wastes, protection of underground pipes, prevention of root intrusion beneath slabs, the dwarfing of trees or shrubs and other applications. The preferred herbicide is 4-difluoromethyl-N,N-dipropyl-2,6-dinitro-aniline, commonly known as trifluralin. 7 figs. Burton, F.G.; Cataldo, D.A.; Cline, J.F.; Skiens, W.E. 1992-05-26 266 PubMed Geological sites of exceptional fossil preservation are becoming a focus of research on root evolution because they retain edaphic and ecological context, and the remains of plant soft tissues are preserved in some. New information is emerging on the origins of rooting systems, their interactions with fungi, and their nature and diversity in the earliest forest ecosystems. Remarkably well-preserved fossils prove that mycorrhizal symbionts were diverse in simple rhizoid-based systems. Roots evolved in a piecemeal fashion and independently in several major clades through the Devonian Period (416 to 360 million years ago), rapidly extending functionality and complexity. Evidence from extinct arborescent clades indicates that polar auxin transport was recruited independently in several to regulate wood and root development. The broader impact of root evolution on the geochemical carbon cycle is a developing area and one in which the interests of the plant physiologist intersect with those of the geochemist. PMID:25187527 Kenrick, Paul; Strullu-Derrien, Christine 2014-10-01 267 Microsoft Academic Search Roots avoid depleting their immediate environment of essential nutrients by continuous growth. Root growth is directed by environmental cues, including gravity. Gravity sensing occurs mainly in the columella cells of the root cap. Upon reorientation within the gravity field, the root-cap amyloplasts sediment, generating a physiological signal that promotes the development of a curvature at the root elongation zones. Recent Elizabeth Rosen; Rujin Chen; Patrick H Masson 1999-01-01 268 Microsoft Academic Search Evidence from forestry has shown that part of the forest floor bearing capacity is delivered by tree roots. The beneficial effect however varies and diminishes with increasing number of vehicle passes. Roots potential for reinforcing the soil is known to depend among others on root mechanical properties, distribution, morphology, etc. Rooting intensity and root patterns of forest trees are complicated, P. Cofie 2001-01-01 269 Microsoft Academic Search VEGETATIVE reproduction in Linaria vulgaris is effected by the formation of root-buds at the junction of the parent and some of the lateral roots. Up to four buds may be formed in the superficial layers of the lateral root within the cortex of the parent root1 (Fig. 1), though parent and lateral root tissues are often not separately recognizable in W. A. Charlton 1965-01-01 270 PubMed We used bomb-radiocarbon and raw minirhizotron lifetimes of fine roots (< 0.5 mm in diameter) in the organic layer of Norway spruce (Picea abies) forests in southern Sweden to test if different models are able to reconcile the apparently contradicting turnover time estimates from both techniques. We present a framework based on survival functions that is able to jointly model bomb-radiocarbon and minirhizotron data. At the same time we integrate prior knowledge about biases of both techniques - the classification of dead roots in minirhizotrons and the use of carbon reserves to grow new roots. Two-pool models, either in parallel or in serial setting, were able to reconcile the bomb-radiocarbon and minirhizotron data. These models yielded a mean residence time of 3.80 ± 0.16 yr (mean ± SD). On average 60 ± 2% of fine roots turned over within 0.75 ± 0.10 yr, while the rest was turning over within 8.4 ± 0.2 yr. Bomb-radiocarbon and minirhizotron data alone give a biased estimate of fine-root turnover. The two-pool models allow a mechanistic interpretation for the coexistence of fast- and slow-cycling roots - suberization and branching for the serial-two-pool model and branching due to ectomycorrhizal fungi-root interactions for the parallel-two-pool model. PMID:25196967 Ahrens, Bernhard; Hansson, Karna; Solly, Emily F; Schrumpf, Marion 2014-12-01 271 PubMed Central Current plant phenotyping technologies to characterize agriculturally relevant traits have been primarily developed for use in laboratory and/or greenhouse conditions. In the case of root architectural traits, this limits phenotyping efforts, largely, to young plants grown in specialized containers and growth media. Hence, novel approaches are required to characterize mature root systems of older plants grown under actual soil conditions in the field. Imaging methods able to address the challenges associated with characterizing mature root systems are rare due, in part, to the greater complexity of mature root systems, including the larger size, overlap, and diversity of root components. Our imaging solution combines a field-imaging protocol and algorithmic approach to analyze mature root systems grown in the field. Via two case studies, we demonstrate how image analysis can be utilized to estimate localized root traits that reliably capture heritable architectural diversity as well as environmentally induced architectural variation of both monocot and dicot plants. In the first study, we show that our algorithms and traits (including 13 novel traits inaccessible to manual estimation) can differentiate nine maize (Zea mays) genotypes 8 weeks after planting. The second study focuses on a diversity panel of 188 cowpea (Vigna unguiculata) genotypes to identify which traits are sufficient to differentiate genotypes even when comparing plants whose harvesting date differs up to 14 d. Overall, we find that automatically derived traits can increase both the speed and reproducibility of the trait estimation pipeline under field conditions. PMID:25187526 Bucksch, Alexander; Burridge, James; York, Larry M.; Das, Abhiram; Nord, Eric; Weitz, Joshua S.; Lynch, Jonathan P. 2014-01-01 272 PubMed The speciation and spatial distribution of selenium (Se) in hydrated plant tissues is not well understood. Using synchrotron-based x-ray absorption spectroscopy and x-ray fluorescence microscopy (two-dimensional scanning [and associated mathematical model] and computed tomography), the speciation and distribution of toxic Se were examined within hydrated roots of cowpea (Vigna unguiculata) exposed to either 20 µM selenite or selenate. Based upon bulk solution concentrations, selenate was 9-fold more toxic to the roots than selenite, most likely due to increased accumulation of organoselenium (e.g. selenomethionine) in selenate-treated roots. Specifically, uptake of selenate (probably by sulfate transporters) occurred at a much higher rate than for selenite (apparently by both passive diffusion and phosphate transporters), with bulk root tissue Se concentrations approximately 18-fold higher in the selenate treatment. Although the proportion of Se converted to organic forms was higher for selenite (100%) than for selenate (26%), the absolute concentration of organoselenium was actually approximately 5-fold higher for selenate-treated roots. In addition, the longitudinal and radial distribution of Se in roots differed markedly: the highest tissue concentrations were in the endodermis and cortex approximately 4 mm or more behind the apex when exposed to selenate but in the meristem (approximately 1 mm from the apex) when exposed to selenite. The examination of the distribution and speciation of Se in hydrated roots provides valuable data in understanding Se uptake, transport, and toxicity. PMID:23835408 Wang, Peng; Menzies, Neal W; Lombi, Enzo; McKenna, Brigid A; de Jonge, Martin D; Paterson, David J; Howard, Daryl L; Glover, Chris J; James, Simon; Kappen, Peter; Johannessen, Bernt; Kopittke, Peter M 2013-09-01 273 PubMed Current plant phenotyping technologies to characterize agriculturally relevant traits have been primarily developed for use in laboratory and/or greenhouse conditions. In the case of root architectural traits, this limits phenotyping efforts, largely, to young plants grown in specialized containers and growth media. Hence, novel approaches are required to characterize mature root systems of older plants grown under actual soil conditions in the field. Imaging methods able to address the challenges associated with characterizing mature root systems are rare due, in part, to the greater complexity of mature root systems, including the larger size, overlap, and diversity of root components. Our imaging solution combines a field-imaging protocol and algorithmic approach to analyze mature root systems grown in the field. Via two case studies, we demonstrate how image analysis can be utilized to estimate localized root traits that reliably capture heritable architectural diversity as well as environmentally induced architectural variation of both monocot and dicot plants. In the first study, we show that our algorithms and traits (including 13 novel traits inaccessible to manual estimation) can differentiate nine maize (Zea mays) genotypes 8 weeks after planting. The second study focuses on a diversity panel of 188 cowpea (Vigna unguiculata) genotypes to identify which traits are sufficient to differentiate genotypes even when comparing plants whose harvesting date differs up to 14 d. Overall, we find that automatically derived traits can increase both the speed and reproducibility of the trait estimation pipeline under field conditions. PMID:25187526 Bucksch, Alexander; Burridge, James; York, Larry M; Das, Abhiram; Nord, Eric; Weitz, Joshua S; Lynch, Jonathan P 2014-10-01 274 NASA Astrophysics Data System (ADS) In the evolution process, living organisms have experienced the action of the Earth's magnetic field (MF) that is a natural component of our environment. It is known that a galactic MF induction does not exceed 0.1 nT, since investigations of weak magnetic field (WMF) effects on biological systems have attracted attention of biologists due to planning long-term space flights to other planets where the magnetizing force is near 10-5 Oe. However, the role of WMF and its influence on organisms' functioning are still insufficiently investigated. A large number of experiments with seedlings of different plant species placed in WMF has found that the growth of their primary roots is inhibited during the early terms of germination in comparison with control. The proliferation activity and cell reproduction are reduced in meristem of plant roots under WMF application. The prolongation of total cell reproductive cycle is registered due to the expansion of G phase in1 different plant species as well as of G phase in flax and lentil roots along with2 relative stability of time parameters of other phases of cell cycle. In plant cells exposed to WMF, the decrease in functional activity of genome at early prereplicate period is shown. WMF causes the intensification in the processes of proteins' synthesis and break-up in plant roots. Qualitative and quantitative changes in protein spectrum in growing and differentiated cells of plant roots exposed to WMF are revealed. At ultrastructural level, there are observed such ultrastructural peculiarities as changes in distribution of condensed chromatin and nucleolus compactization in nuclei, noticeable accumulation of lipid bodies, development of a lytic compartment (vacuoles, cytosegresomes and paramural bodies), and reduction of phytoferritin in plastids in meristem cells of pea roots exposed to WMF. Mitochondria are the most sensitive organelle to WMF application: their size and relative volume in cells increase, matrix is electron-transparent, and cristae reduce. Cytochemical studies indicate that cells of plant roots exposed to WMF show the Ca2 + oversaturation both in all organelles and in a hyaloplasm of the cells unlike the control ones. The data presented suggest that prolonged plant exposures to WMF may cause different biological effects at the cellular, tissue and organ level. They may be functionally related to systems that regulate plant metabolism including the intracellular Ca 2 + homeostasis. The understanding of the fundamental mechanisms and sites of interactions between WMF and biological systems are complex and still deserve strong efforts, particular addressed to basic principles of coupling between field energy and biomolecules. Belyavskaya, N. 275 NASA Astrophysics Data System (ADS) Roots are hidden from view and heterogeneously distributed making them difficult to study in situ. As a result, the causes and timing of root production are not well understood. Researchers have long assumed that above and belowground phenology is synchronous; for example, most parameterizations of belowground carbon allocation in terrestrial biosphere models are based on allometry and represent a fixed fraction of net C uptake. However, using results from metaanalysis as well as empirical data from oak and hemlock stands at Harvard Forest, we show that synchronous root and shoot growth is the exception rather than the rule. We collected root and shoot phenology measurements from studies across four biomes (boreal, temperate, Mediterranean, and subtropical). General patterns of root phenology varied widely with 1-5 production peaks in a growing season. Surprisingly, in 9 out of the 15 studies, the first root production peak was not the largest peak. In the majority of cases maximum shoot production occurred before root production (Offset>0 in 32 out of 47 plant sample means). The number of days offset between maximum root and shoot growth was negatively correlated with median annual temperature and therefore differs significantly across biomes (ANOVA, F3,43=9.47, p<0.0001). This decline in offset with increasing temperature may reflect greater year-round coupling between air and soil temperature in warm biomes. Growth form (woody or herbaceous) also influenced the relative timing of root and shoot growth. Woody plants had a larger range of days between root and shoot growth peaks as well as a greater number of growth peaks. To explore the range of phenological relationships within woody plants in the temperate biome, we focused on above and belowground phenology in two common northeastern tree species, Quercus rubra and Tsuga canadensis. Greenness index, rate of stem growth, root production and nonstructural carbohydrate content were measured beginning in April 2012 through August 2013 at the Harvard Forest in Petersham, MA, USA. Greenness and stem growth were highest in late May and early June with one clear maximum growth period. In contrast, root growth was characterized by multiple production peaks. Q. rubra root growth experienced many small flushes around day of year (DOY) 156 (early June) and one large peak on 234 (late August). T. canadensis root growth peaked on DOY 188 (early July), 234.5 (late August) and 287 (mid-October). However, particular phenological patterns varied widely from site to site. Despite large spatial heterogeneity, it appears that Q. rubra experiences greater overall root production as well as more allocation to roots during the growing season. The storage pool of nonstructural carbohydrates experiences a mid-summer drawdown in Q. rubra but not T. canadensis roots. Timing of belowground C allocation to root growth and nonstructural carbohydrate accumulation may be regulated by climate factors as well as endogenous factors such as vessel size, growth form, or tradeoffs in C allocated between plant organs. Plant roots supply substrate to microbial communities and hence their production feeds back to other plant and soil processes that affect ecosystem C fluxes. Abramoff, R. Z.; Finzi, A. 2013-12-01 276 PubMed Central Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite–granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground-penetrating radar and root activity via soil water acquisition using isotopic matching of ?18O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil ?18O isotopic signature declined with depth, providing conditions for plant–soil ?18O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10–20 cm depth but broader under phyllite–granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground-penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic-dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree-based landscapes. PMID:23762519 Isaac, Marney E; Anglaaere, Luke C N 2013-01-01 277 PubMed Central The specialized root epidermis cells of higher plants produce long, tubular outgrowths called root hairs. Root hairs play an important role in nutrient and water uptake, and they serve as a valuable model in studies of plant cell morphogenesis. More than 1,300 articles that describe the biological processes of these unique cells have been published to date. As new fields of root hair research are emerging, the number of new papers published each year and the volumes of new relevant data are continuously increasing. Therefore, there is a general need to facilitate studies on root hair biology by collecting, presenting, and sharing the available information in a systematic, curated manner. Consequently, in this paper, we present a comprehensive database of root hair genomics, iRootHair, which is accessible as a Web-based service. The current version of the database includes information about 153 root hair-related genes that have been identified to date in dicots and monocots along with their putative orthologs in higher plants with sequenced genomes. In order to facilitate the use of the iRootHair database, it is subdivided into interrelated, searchable sections that describe genes, processes of root hair formation, root hair mutants, and available references. The database integrates bioinformatics tools with a focus on sequence identification and annotation. iRootHair is a unique resource for root hair research that integrates the large volume of data related to root hair genomics in a single, curated, and expandable database that is freely available at www.iroothair.org. PMID:23129204 Kwasniewski, Miroslaw; Nowakowska, Urszula; Szumera, Jakub; Chwialkowska, Karolina; Szarejko, Iwona 2013-01-01 278 PubMed The C-shaped root canal constitutes an unusual root morphology that can be found primarily in mandibular second permanent molars. Due to the complexity of their structure, C-shaped root canal systems may complicate endodontic interventions. A thorough understanding of root canal morphology is therefore imperative for proper diagnosis and successful treatment. This review aims to summarize current knowledge regarding C-shaped roots and root canals, from basic morphology to advanced endodontic procedures. To this end, a systematic search was conducted using the MEDLINE, BIOSIS, Cochrane Library, EMBASE, Google Scholar, Web of Science, PLoS and BioMed Central databases, and many rarely cited articles were included. Furthermore, four interactive 3D models of extracted teeth are introduced that will allow for a better understanding of the complex C-shaped root canal morphology. In addition, the present publication includes an embedded best-practice video showing an exemplary root canal procedure on a tooth with a pronounced C-shaped root canal. The survey of this unusual structure concludes with a number of suggestions concerning future research efforts. PMID:24483229 Kato, A; Ziegler, A; Higuchi, N; Nakata, K; Nakamura, H; Ohno, N 2014-11-01 279 PubMed To test direct and indirect effects of glomalin, mycorrhizal hyphae, and roots on aggregate stability, perspex pots separated by 37-?m nylon mesh in the middle were used to form root-free hyphae and root/hyphae chambers, where trifoliate orange (Poncirus trifoliata) seedlings were colonized by Funneliformis mosseae or Paraglomus occultum in the root/hyphae chamber. Both fungal species induced significantly higher plant growth, root total length, easily-extractable glomalin-related soil protein (EE-GRSP) and total GRSP (T-GRSP), and mean weight diameter (an aggregate stability indicator). The Pearson correlation showed that root colonization or soil hyphal length significantly positively correlated with EE-GRSP, difficultly-extractable GRSP (DE-GRSP), T-GRSP, and water-stable aggregates in 2.00-4.00, 0.50-1.00, and 0.25-0.50 mm size fractions. The path analysis indicated that in the root/hyphae chamber, aggregate stability derived from a direct effect of root colonization, EE-GRSP or DE-GRSP. Meanwhile, the direct effect was stronger by EE-GRSP or DE-GRSP than by mycorrhizal colonization. In the root-free hyphae chamber, mycorrhizal-mediated aggregate stability was due to total effect but not direct effect of soil hyphal length, EE-GRSP and T-GRSP. Our results suggest that GRSP among these tested factors may be the primary contributor to aggregate stability in the citrus rhizosphere. PMID:25059396 Wu, Qiang-Sheng; Cao, Ming-Qin; Zou, Ying-Ning; He, Xin-hua 2014-01-01 280 E-print Network produce lat- erals along the length of the primary root (Deak & Malamy 2005); hence, the developing root a rudimentary embryonic root, and most growth and differentiation is post-embryonic (Deak & Malamy 2005). During Kronzucker, Herbert J. 281 Federal Register 2010, 2011, 2012, 2013 ...Drug Enforcement Administration Roots Pharmaceuticals, Inc.; Revocation of Registration...issued an Order to Show Cause to Roots Pharmaceuticals, Inc. (Registrant), of American...Registration BR9610571, issued to Roots Pharmaceuticals, Inc., be, and it hereby... 2011-08-18 282 PubMed Central Background Ecologically meaningful classification of bacterial populations is essential for understanding the structure and function of bacterial communities. As in soils, the ecological strategy of the majority of root-colonizing bacteria is mostly unknown. Among those are Massilia (Oxalobacteraceae), a major group of rhizosphere and root colonizing bacteria of many plant species. Methodology/Principal Findings The ecology of Massilia was explored in cucumber root and seed, and compared to that of Agrobacterium population, using culture-independent tools, including DNA-based pyrosequencing, fluorescence in situ hybridization and quantitative real-time PCR. Seed- and root-colonizing Massilia were primarily affiliated with other members of the genus described in soil and rhizosphere. Massilia colonized and proliferated on the seed coat, radicle, roots, and also on hyphae of phytopathogenic Pythium aphanidermatum infecting seeds. High variation in Massilia abundance was found in relation to plant developmental stage, along with sensitivity to plant growth medium modification (amendment with organic matter) and potential competitors. Massilia absolute abundance and relative abundance (dominance) were positively related, and peaked (up to 85%) at early stages of succession of the root microbiome. In comparison, variation in abundance of Agrobacterium was moderate and their dominance increased at later stages of succession. Conclusions In accordance with contemporary models for microbial ecology classification, copiotrophic and competition-sensitive root colonization by Massilia is suggested. These bacteria exploit, in a transient way, a window of opportunity within the succession of communities within this niche. PMID:22808103 Ofek, Maya; Hadar, Yitzhak; Minz, Dror 2012-01-01 283 PubMed Meniscal root tears, less common than meniscal body tears and frequently unrecognized, are a subset of meniscal injuries that often result in significant knee joint disorders. The meniscus root attachment aids meniscal function by securing the meniscus in place and allowing for optimal shock-absorbing function in the knee. With root tears, meniscal extrusion often occurs, and the transmission of circumferential hoop stresses is impaired. This alters knee biomechanics and kinematics and significantly increases tibiofemoral contact pressure. In recent years, meniscal root tears, which by definition include direct avulsions off the tibial plateau or radial tears adjacent to the root itself, have attracted attention because of concerns that significant meniscal extrusion dramatically inhibits normal meniscal function, leading to a condition biomechanically similar to a total meniscectomy. Recent literature has highlighted the importance of early diagnosis and treatment; fortunately, these processes have been vastly improved by advances in magnetic resonance imaging and arthroscopy. This article presents a review of the clinically relevant anatomic, biomechanical, and functional descriptions of the meniscus root attachments, as well as current strategies for accurate diagnosis and treatment of common injuries to these meniscus root attachments. PMID:24623276 Bhatia, Sanjeev; LaPrade, Christopher M; Ellman, Michael B; LaPrade, Robert F 2014-12-01 284 PubMed Panax ginseng Meyer is one of the major medicinal plants in oriental countries belonging to the Araliaceae family which are the primary source for ginsenosides. However, very few genes were characterized for ginsenoside pathway, due to the limited genome information. Through this study, we obtained a comprehensive transcriptome from adventitious roots, which were treated with methyl jasmonic acids for different time points (control, 2h, 6h, 12h, and 24h) and sequenced by RNA 454 pyrosequencing technology. Reference transcriptome 39,304,529 (0.04GB) was obtained from 5,724,987,880 bases (5.7GB) of 22 libraries by de novo assembly and 35,266 (58.5%) transcripts were annotated with biological schemas (GO and KEGG). The digital gene expression patterns were obtained from in vitro grown adventitious root sequences which mapped to reference, from that, 3813 (6.3%) unique transcripts were involved in ?2 fold up and downregulations. Finally, candidates for ginsenoside pathway genes were predicted from observed expression patterns. Among them, 30 transcription factors, 20 cytochromes, and 11 glycosyl transferases were predicted as ginsenoside candidates. These data can remarkably expand the existing transcriptome resources of Panax, especially to predict existence of gene networks in P. ginseng. The entity of the data provides a valuable platform to reveal more on secondary metabolism and abiotic stresses from P. ginseng in vitro grown adventitious roots. PMID:24831831 Subramaniyam, Sathiyamoorthy; Mathiyalagan, Ramya; Natarajan, Sathishkumar; Kim, Yu-Jin; Jang, Moon-Gi; Park, Jun-Hyung; Yang, Deok Chun 2014-08-01 285 NASA Astrophysics Data System (ADS) Brachial plexus injury is a serious medical problem that affects many patients annually, with most cases involving damage to the nerve roots. Therefore, a chondroitin sulfate hydrogel was designed to both serve as a scaffold for regenerating root neurons and deliver neurotrophic signals. Capillary electrophoresis showed that chondroitin sulfate has a dissociation constant in the micromolar range with several common neurotrophins, and this was determined to be approximately tenfold stronger than with heparin. It was also revealed that nerve growth factor exhibits a slightly stronger affinity for hyaluronic acid than for chondroitin sulfate. However, E8 chick dorsal root ganglia cultured in the presence of nerve growth factor revealed that ganglia cultured in chondroitin sulfate scaffolds showed more robust growth than those cultured in control gels of hyaluronic acid. It is hypothesized that, despite the stronger affinity of nerve growth factor for hyaluronic acid, chondroitin sulfate serves as a better scaffold for neurite outgrowth, possibly due to inhibition of growth by hyaluronic acid chains. Conovaloff, Aaron; Panitch, Alyssa 2011-10-01 286 PubMed Central In plants, genes involved in photosynthesis are encoded separately in nuclei and plastids, and tight cooperation between these two genomes is therefore required for the development of functional chloroplasts. Golden2-like (GLK) transcription factors are involved in chloroplast development, directly targeting photosynthesis-associated nuclear genes for up-regulation. Although overexpression of GLKs leads to chloroplast development in non-photosynthetic organs, the mechanisms of coordination between the nuclear gene expression influenced by GLKs and the photosynthetic processes inside chloroplasts are largely unknown. To elucidate the impact of GLK-induced expression of photosynthesis-associated nuclear genes on the construction of photosynthetic systems, chloroplast morphology and photosynthetic characteristics in greenish roots of Arabidopsis thaliana lines overexpressing GLKs were compared with those in wild-type roots and leaves. Overexpression of GLKs caused up-regulation of not only their direct targets but also non-target nuclear and plastid genes, leading to global induction of chloroplast biogenesis in the root. Large antennae relative to reaction centers were observed in wild-type roots and were further enhanced by GLK overexpression due to the increased expression of target genes associated with peripheral light-harvesting antennae. Photochemical efficiency was lower in the root chloroplasts than in leaf chloroplasts, suggesting that the imbalance in the photosynthetic machinery decreases the efficiency of light utilization in root chloroplasts. Despite the low photochemical efficiency, root photosynthesis contributed to carbon assimilation in Arabidopsis. Moreover, GLK overexpression increased CO2 fixation and promoted phototrophic performance of the root, showing the potential of root photosynthesis to improve effective carbon utilization in plants. PMID:23749810 Kobayashi, Koichi; Sasaki, Daichi; Noguchi, Ko; Fujinuma, Daiki; Komatsu, Hirohisa; Kobayashi, Masami; Sato, Mayuko; Toyooka, Kiminori; Sugimoto, Keiko; Niyogi, Krishna K.; Wada, Hajime; Masuda, Tatsuru 2013-01-01 287 PubMed Central Background Aluminum (Al) toxicity is one of the most important yield-limiting factors of many crops worldwide. The primary symptom of Al toxicity syndrome is the inhibition of root growth leading to poor water and nutrient absorption. Al tolerance has been extensively studied using hydroponic experiments. However, unlike soil conditions, this method does not address all of the components that are necessary for proper root growth and development. In the present study, we grew two maize genotypes with contrasting tolerance to Al in soil containing toxic levels of Al and then compared their transcriptomic responses. Results When grown in acid soil containing toxic levels of Al, the Al-sensitive genotype (S1587-17) showed greater root growth inhibition, more Al accumulation and more callose deposition in root tips than did the tolerant genotype (Cat100-6). Transcriptome profiling showed a higher number of genes differentially expressed in S1587-17 grown in acid soil, probably due to secondary effects of Al toxicity. Genes involved in the biosynthesis of organic acids, which are frequently associated with an Al tolerance response, were not differentially regulated in both genotypes after acid soil exposure. However, genes related to the biosynthesis of auxin, ethylene and lignin were up-regulated in the Al-sensitive genotype, indicating that these pathways might be associated with root growth inhibition. By comparing the two maize lines, we were able to discover genes up-regulated only in the Al-tolerant line that also presented higher absolute levels than those observed in the Al-sensitive line. These genes encoded a lipase hydrolase, a retinol dehydrogenase, a glycine-rich protein, a member of the WRKY transcriptional family and two unknown proteins. Conclusions This work provides the first characterization of the physiological and transcriptional responses of maize roots when grown in acid soil containing toxic levels of Al. The transcriptome profiles highlighted several pathways that are related to Al toxicity and tolerance during growth in acid soil. We found several genes that were not found in previous studies using hydroponic experiments, increasing our understanding of plant responses to acid soil. The use of two germplasms with markedly different Al tolerances allowed the identification of genes that are a valuable tool for assessing the mechanisms of Al tolerance in maize in acid soil. PMID:20828383 2010-01-01 288 PubMed Adventitious root formation, the development of roots on non-root tissue (e.g. leaves, hypocotyls and stems) is a critical step during micropropagation. Although root induction treatments are routinely used for a large number of species micropropagated in vitro as well as for in vivo cuttings, the mechanisms controlling adventitious rooting are still poorly understood. Researchers attempt to gain better insight into the molecular aspects by studying adventitious rooting in Arabidopsis thaliana. The existing assay involves etiolation of seedlings and measurements of de novo formed roots on the elongated hypocotyl. The etiolated hypocotyls express a novel auxin-controlled signal transduction pathway in which auxin response factors (ARFs), microRNAs and environmental conditions that drive adventitious rooting are integrated. An alternative assay makes use of so-called thin cell layers (TCL), excised strips of cells from the inflorescence stem of Arabidopsis thaliana. However, both the etiolated seedling system and the TCL assay are only distantly related to industrial rooting processes in which roots are induced on adult stem tissue. Here, we describe an adventitious root induction system that uses segments of the inflorescence stems of Arabidopsis thaliana, which have a histological structure similar to cuttings or in vitro micropropagated shoots. The system allows multiple treatments with chemicals as well as the evaluation of different environmental conditions on a large number of explants. It is therefore suitable for high throughput chemical screenings and experiments that require numerous data points for statistical analysis. Using this assay, the adventitious root induction capacity of classical auxins was evaluated and a differential response to the different auxins could be demonstrated. NAA, IBA and IAA stimulated adventitious rooting on the stem segment, whereas 2,4-D and picloram did not. Light conditions profoundly influenced the root induction capacity of the auxins. Additionally to the environmental control of adventitious root formation, we also investigated the spatial and temporal aspects of stem-based adventitious root organogenesis. To determine the cells involved in de novo root initiation on the adult stems, we adopted scanning electron microscopy, which allows the visualization of the auxin responsive stem tissue. Using this technique, direct (without callus interface) and indirect (with intermediate callus phase) organogenesis was readily distinguished. The described micro-stem segment system is also suitable for other non-woody species and it is a valuable tool to perform fast evaluations of different treatments to study adventitious root induction. PMID:23299674 Verstraeten, Inge; Beeckman, Tom; Geelen, Danny 2013-01-01 289 NASA Technical Reports Server (NTRS) The BOREAS TE-2 team collected several data sets in support of its efforts to characterize and interpret information on the respiration of the foliage, roots, and wood of boreal vegetation. This data set includes means of tree root respiration measurements on roots having diameters ranging from 0 to 2 mm conducted in the NSA during the growing season of 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). Ryan, Michael G.; Lavigne, Michael; Hall, Forrest G. (Editor); Papagno, Andrea (Editor) 2000-01-01 290 E-print Network May 1, 2013-Apr 30, 2014 Per term 17,235.00$ 34,470.00$100.00$ 1,044.39$648.00$ 36,262.39$PriorDue: Sep 1 Due: Sep 1 Due: Sep 30 Due: Sep 30 Normal Unit Tuition Student Student Units Fee 2014-15 Assistance Levy Activity Fees UHIP (Note 1) (Note 3) (Note 4) (Note 7) After May 1, 2014 30 1,067.66$ 32
Abolmaesumi, Purang
291
PubMed
The architecture of the branched root system of plants is a major determinant of vigor. Water availability is known to impact root physiology and growth; however, the spatial scale at which this stimulus influences root architecture is poorly understood. Here we reveal that differences in the availability of water across the circumferential axis of the root create spatial cues that determine the position of lateral root branches. We show that roots of several plant species can distinguish between a wet surface and air environments and that this also impacts the patterning of root hairs, anthocyanins, and aerenchyma in a phenomenon we describe as hydropatterning. This environmental response is distinct from a touch response and requires available water to induce lateral roots along a contacted surface. X-ray microscale computed tomography and 3D reconstruction of soil-grown root systems demonstrate that such responses also occur under physiologically relevant conditions. Using early-stage lateral root markers, we show that hydropatterning acts before the initiation stage and likely determines the circumferential position at which lateral root founder cells are specified. Hydropatterning is independent of endogenous abscisic acid signaling, distinguishing it from a classic water-stress response. Higher water availability induces the biosynthesis and transport of the lateral root-inductive signal auxin through local regulation of tryptophan aminotransferase of Arabidopsis 1 and PIN-formed 3, both of which are necessary for normal hydropatterning. Our work suggests that water availability is sensed and interpreted at the suborgan level and locally patterns a wide variety of developmental processes in the root. PMID:24927545
Bao, Yun; Aggarwal, Pooja; Robbins, Neil E; Sturrock, Craig J; Thompson, Mark C; Tan, Han Qi; Tham, Cliff; Duan, Lina; Rodriguez, Pedro L; Vernoux, Teva; Mooney, Sacha J; Bennett, Malcolm J; Dinneny, José R
2014-06-24
292
PubMed
The effect of various alkylguanidines on ion absorption and energy metabolism in oat (Avena sativa cv. Goodfield) roots has been investigated. Of several alkylguanidines tested, octylguanidine was the most effective inhibitor of both K(+) and Cl(-) absorption by excised roots. At 225 mum octylguanidine, the transport of both ions was inhibited within 60 seconds and to a similar extent. Octylguanidine inhibited mitochondrial oxidative phosphorylation and mitochondrial adenosine 5'-triphosphatase (ATPase). The plasma membrane ATPase was also inhibited if the membranes were diluted and pretreated with Triton X-100.Concentrations of octylguanidine giving half-maximal inhibition of K(+) influx, mitochondrial ATPase, oxidative phosphorylation, and plasma membrane ATPase were 50, 50, 100, and 275 mum, respectively. With increasing chain length, alkylguanidines (225 mum) became progressively more inhibitory to K(+) absorption and to the mitochondrial ATPase. Shorter chain guanidines slightly inhibited the plasma membrane ATPase, however, these compounds produced a slight stimulation in oxidative phosphorylation.Conditions of Triton treatment that were important in the elimination of permeability barriers of plasma membrane vesicles to ATP, Mg(2+), KCl, and octylguanidine were: concentration of Triton during pretreatment and in the assay media, concentrations of sucrose and plasma membrane during Triton treatment, and temperature of Triton treatment.Inhibition by octylguanidine of K(+) and Cl(-) absorption by excised oat roots may be due to an inhibition of either the plasma membrane ATPase or mitochondrial oxidative phosphorylation. The isolated plasma membrane did not appear to be permeable to octylguanidine since the plasma membrane ATPase was inhibited only after treating the membrane with Triton. This result indicates that the primary site of action of octylguanidine in excised root is more likely to be the plasma membrane ATPase than mitochondrial oxidative phosphorylation. PMID:16660414
Gomez-Lepe, B; Hodges, T K
1978-06-01
293
PubMed Central
The effect of various alkylguanidines on ion absorption and energy metabolism in oat (Avena sativa cv. Goodfield) roots has been investigated. Of several alkylguanidines tested, octylguanidine was the most effective inhibitor of both K+ and Cl? absorption by excised roots. At 225 ?m octylguanidine, the transport of both ions was inhibited within 60 seconds and to a similar extent. Octylguanidine inhibited mitochondrial oxidative phosphorylation and mitochondrial adenosine 5?-triphosphatase (ATPase). The plasma membrane ATPase was also inhibited if the membranes were diluted and pretreated with Triton X-100. Concentrations of octylguanidine giving half-maximal inhibition of K+ influx, mitochondrial ATPase, oxidative phosphorylation, and plasma membrane ATPase were 50, 50, 100, and 275 ?m, respectively. With increasing chain length, alkylguanidines (225 ?m) became progressively more inhibitory to K+ absorption and to the mitochondrial ATPase. Shorter chain guanidines slightly inhibited the plasma membrane ATPase, however, these compounds produced a slight stimulation in oxidative phosphorylation. Conditions of Triton treatment that were important in the elimination of permeability barriers of plasma membrane vesicles to ATP, Mg2+, KCl, and octylguanidine were: concentration of Triton during pretreatment and in the assay media, concentrations of sucrose and plasma membrane during Triton treatment, and temperature of Triton treatment. Inhibition by octylguanidine of K+ and Cl? absorption by excised oat roots may be due to an inhibition of either the plasma membrane ATPase or mitochondrial oxidative phosphorylation. The isolated plasma membrane did not appear to be permeable to octylguanidine since the plasma membrane ATPase was inhibited only after treating the membrane with Triton. This result indicates that the primary site of action of octylguanidine in excised root is more likely to be the plasma membrane ATPase than mitochondrial oxidative phosphorylation. PMID:16660414
Gomez-Lepe, Beatriz; Hodges, Thomas K.
1978-01-01
294
SciTech Connect
In 1981 to 1982 an extensive bibliographic study was completed to document rooting depths of native plants in the United States. The data base presently contains 1034 citations with approximately 12,000 data elements. In this paper the data were analyzed for rooting depths as related to life form, soil type, geographical region, root type, family, root depth to shoot height ratios, and root depth to root lateral ratios. Average rooting depth and rooting frequencies were determined and related to present low-level waste site maintenance.
Foxx, T S; Tierney, G D; Williams, J M
1984-11-01
295
NASA Technical Reports Server (NTRS)
A new geometric way of computing the asymptotic behavior of unbounded root loci of a strictly proper linear time-invariant control system as loop gain goes to infinity is presented. Properties of certain restricted linear maps and nested restrictions of linear maps are developed, and formulas are obtained for the leading coefficient of the asymptotic values of the unbounded multivariable root loci are obtained in terms of eigenvalues of those maps. Published results and a certain simple null structure assumption are used to relate these asymptotic values to the structure at infinity of the Smith-McMillan form of the open loop transfer function. Explicit matrix formulas for the more abstract derived formulas are given and additional geometric insights are developed with orthogonal projections and singular value decomposition. Formulas for the pivots of the unbounded root loci are calculated and shown to have the same form as the coefficients of the unbounded asymptotic root loci.
Sastry, S. S.; Desoer, C. A.
1983-01-01
296
PubMed
Within the root meristem of flowering plants is a group of mitotically inactive cells designated the quiescent center (QC). Recent work links the quiescent state to high levels of the growth regulator auxin that accumulates in the QC via polar transport. This in turn results in elevated levels of the enzyme ascorbic acid oxidase (AAO), resulting in a reduction of ascorbic acid (AA) within the QC and mitotic quiescence. We present evidence for additional interactions between auxin, AAO, and AA, and report that, in vitro, AAO oxidatively decarboxylates auxin, suggesting a mechanism for regulating auxin levels within the QC. We also report that oxidative decarboxylation occurs at the root tip and that an intact root cap must be present for this metabolic event to occur. Finally, we consider how interaction between auxin and AAO may influence root development by regulating the formation of the QC. PMID:10712557
Kerk, N M; Jiang, K; Feldman, L J
2000-03-01
297
NSDL National Science Digital Library
Page one consists of a full color illustration of an idealized plant, showing various leaf, stem and root features. Page two illustrates various adaptations of plant flowers, leaves and stems. All illustrations are accompanied by explanations of the structures' functions.
2000-01-01
298
Fresnel diffraction and lens transformations can be combined to implement optical transformations corresponding to operators that are roots of the identity operator I . Since their nature remains invariant under unitary transformations, new roots can be obtained by Fresnel diffraction. A correspondence is established with ray matrices in periodic lens systems with unit magnification. Consecutive powers of particular roots of I form groups from which the projectors can be obtained by means of optical discrete Fourier transforms (DFT's), conveniently performed by networks of beam splitters and mirrors. One can then obtain additional roots of I from the projectors by reassigning eigenvalues among them, which is done by introducing suitable phase shifts, and reusing the DFT network backward.
Marhic, M. E.
1995-07-01
299
NASA Technical Reports Server (NTRS)
Research during the period 1 March 1992 to 30 November 1993 focused on improvements in a video digitizer system designed to automate the recording of surface extension in plants responding to gravistimulation. The improvements included modification of software to allow detailed analysis of localized extension patterns in roots of Arabidopsis. We used the system to analyze the role of the postmitotic isodiametric growth zone (a region between the meristem and the elongation zone) in the response of maize roots to auxin, calcium, touch and gravity. We also used the system to analyze short-term auxin and gravitropic responses in mutants of Arabidopsis with reduced auxin sensitivity. In a related project, we studied the relationship between growth rate and surface electrical currents in roots by examining the effects of gravity and thigmostimulation on surface potentials in maize roots.
Evans, Michael L.
1993-01-01
300
PubMed
Panoramic images were taken from an anatomically correct phantom with three different buccolingual angulations for each tooth (Original, 10 degrees buccal root torque, and 10 degrees lingual root torque). The true mesiodistal angulation of each tooth was determined with a three-dimensional coordinate measurement machine. Each tooth had at least one angle measurement that was statistically different from the other mesiodistal angles with different buccolingual orientations. Roots with buccal root orientations were projected more distally than they were in reality; and the roots lingually positioned were projected more mesially. The canine and premolars in both arches were most affected and the phenomenon was more pronounced in the maxilla than the mandible. Buccolingual orientation changes did not affect the root angulation expression on the incisor area. PMID:20303900
Garcia-Figueroa, Mariano A; Raboud, Donald W; Lam, Ernest W; Heo, Giseon; Major, Paul W
2009-03-01
301
PubMed
Endogenous indoleacetic acid (IAA) levels of Euphorbia esula L. primary root and root buds were examined at three phenologic stages. High performance liquid chromatography coupled with fluorescence detection and gas chromatography-mass spectrometry, using (13)C(6)[benzene ring]-indole-3-acetic acid as internal standard, were used to measure root bud free and bound IAA levels in vegetative, full flower, and post-flower plants. Highest levels of free IAA (103 nanograms per gram fresh weight) were found in root buds during full flower. Esterified and amide IAA increased significantly in root buds of full flower and post-flower plants, but were not detectable in root buds of vegetative plants. Primary rootfree IAA was highest in vegetative and full flower plants (34.5 nanograms per gram fresh weight) and decreased by 50% in post-flower plants. PMID:16665432
Nissen, S J; Foley, M E
1987-06-01
302
Plant litter is a major source of soil organic carbon (C). This litter is not homogenous, but instead primarily composed of fine root and leaf litter that adapted to different physiological functions. These unique functions suggest that root and leaf litter likely have different biochemical traits, and thus different decomposition patterns. However, few studies have compared their substrate quality and contributions to soil C. Also, much less attention has been given to fine roots although they can represent a substantial litter production. Here we hypothesize that 1) leaf litter and fine roots have different substrate quality as they are highly different in biochemical composition; 2) the biochemical composition of leaf litter and fine roots responds differently to the simulated nitrogen (N) deposition. To test these hypotheses, we collected leaf litter and fine roots of Acer saccharum (the dominant species in the northern temperate ecosystems we studied) in both ambient and N addition treatment plots at four sites of Michigan N deposition gradient study. We quantified ten biochemical components thought to be important on decomposition. Strikingly, we found a consistently three-fold higher lignin concentration in fine roots than that in leaf litter (P< 0.01). On average, lignin concentration of fine roots was 45.4±0.3% while that of leaf litter was 13.5±0.2%. Lignin has been considered highly recalcitrant and hypothesized as the major precursor of humus substance. Condensed tannin (CT) concentration in fine roots (13.13±0.51%) was also substantially higher than that in leaf litter (P< 0.01, 4.63±0.42 %). Tissue CT can inhibit litter decay by both precipitating proteins and by having antimicrobial properties. In contrast, fine roots exhibited lower concentrations of non-structural carbohydrates (NSC), soluble phenolics, and holocellulose (hemicelluloses & cellulose) than leaf litter (P< 0.01). These components are considered more easily accessible, and may stimulate the decay of lignin by providing required energy. Therefore, fine roots of Acer saccharum have a relatively recalcitrant nature based on their distinct biochemical composition, suggesting fine roots may be the major driver of soil carbon formation in the ecosystems we studied. Litter type and N addition had significant interactions on lignin, holocellulose, and NSC (P< 0.05), indicating these traits of different litter types respond differently to N addition. In leaf litter, the concentrations of lignin, NSC, and bound CT were affected by N addition (P< 0.05). By contrast, N addition only reduced the soluble protein concentration in fine roots (P< 0.05). Hence, substrate quality of leaf litter and fine roots responds differently to the simulated N deposition, and may eventually lead to different responses in decomposition pattern. This is one of few studies comparing the detailed biochemical profile of leaf litter and fine roots in a dominant tree species. Different biochemical traits of fine roots and leaf litter may reflect the different specializations for their physiological functions. This work highlights the importance of fine root in the soil carbon formation due to its recalcitrant nature, and emphasizes the necessity of differentiating the responses of leaf litter and fine root decompositions to environmental changes when modeling biogeochemical cycles.
Xia, M.; Pregitzer, K. S.; Talhelm, A. F.
2012-12-01
303
NASA Technical Reports Server (NTRS)
Capillary-effect root-environment system (CERES) is experimental apparatus for growing plants in nutrient solutions. Solution circulated at slight tension in cavity filled with plastic screen and covered by porous plastic membrane. By adsorptive attraction, root draws solution through membrane. Conceived for use in microgravity of space, also finds terrestrial application in germinating seedlings, because it protects them from extremes of temperature, moisture, and soil pH and from overexposure to fertilizers and herbicides.
Wright, Bruce D.
1991-01-01
304
PubMed Central
Background and Aims Anatomy had been one of the foundations in our understanding of plant evolutionary trends and, although recent evo-devo concepts are mostly based on molecular genetics, classical structural information remains useful as ever. Of the various plant organs, the roots have been the least studied, primarily because of the difficulty in obtaining materials, particularly from large woody species. Therefore, this review aims to provide an overview of the information that has accumulated on the anatomy of angiosperm roots and to present possible evolutionary trends between representatives of the major angiosperm clades. Scope This review covers an overview of the various aspects of the evolutionary origin of the root. The results and discussion focus on angiosperm root anatomy and evolution covering representatives from basal angiosperms, magnoliids, monocots and eudicots. We use information from the literature as well as new data from our own research. Key Findings The organization of the root apical meristem (RAM) of Nymphaeales allows for the ground meristem and protoderm to be derived from the same group of initials, similar to those of the monocots, whereas in Amborellales, magnoliids and eudicots, it is their protoderm and lateral rootcap which are derived from the same group of initials. Most members of Nymphaeales are similar to monocots in having ephemeral primary roots and so adventitious roots predominate, whereas Amborellales, Austrobaileyales, magnoliids and eudicots are generally characterized by having primary roots that give rise to a taproot system. Nymphaeales and monocots often have polyarch (heptarch or more) steles, whereas the rest of the basal angiosperms, magnoliids and eudicots usually have diarch to hexarch steles. Conclusions Angiosperms exhibit highly varied structural patterns in RAM organization; cortex, epidermis and rootcap origins; and stele patterns. Generally, however, Amborellales, magnoliids and, possibly, Austrobaileyales are more similar to eudicots, and the Nymphaeales are strongly structurally associated with the monocots, especially the Acorales. PMID:23299993
Seago, James L.; Fernando, Danilo D.
2013-01-01
305
PubMed
This study evaluated changes in neoaortic root geometry in patients who underwent the Ross procedure. Serial postoperative echocardiographic measurements of the neoaortic root indexed to the square root of body surface area (centimeters divided by meters) were obtained from 30 patients (age range 3.1 to 31.4 years) and compared with paired preoperative and immediate postoperative values. Normal aortic root diameter Z scores were derived from root dimensions obtained from 217 healthy controls. Compared with preoperative values, an immediate stretch of the neoaortic versus pulmonary root (annulus and sinuses of valsalva) was observed at a mean follow-up period of 1 week. Additional aortic annular dilation from baseline prehospital discharge values was observed at 2 to 12 months (baseline vs follow-up annulus Z score: 1.4 vs 2.6, p <0.01, n = 16) and at 16 to 33 months follow-up (0.8 vs 2.0, p <0.05, n = 12). In a similar fashion, there was additional enlargement of the aortic sinus from its stretched state at hospital discharge at 2 to 12 months (baseline vs follow-up sinus Z score: 2.0 vs 3.3, p <0.01, n = 17) and at 16 to 33 months (1.7 vs 3.0, p <0.01, n = 13). There were no differences in root size between 2 to 12 and 16 to 33 months after surgery. There was a decrease in left ventricular size with no alteration in blood pressure or degree of aortic valve regurgitation. Thus, aortic root dilation occurs up to the first year after the Ross procedure but does not appear to progress beyond this time. PMID:10190409
Tantengco, M V; Humes, R A; Clapp, S K; Lobdell, K W; Walters, H L; Hakimi, M; Epstein, M L
1999-03-15
306
\\u000a The roots of many plant species develop complex growth behaviors when germinated on hard surfaces, and scientists have learned\\u000a to use this experimental set-up to study the structure and dynamics of cytoskeletal arrays. Our knowledge of the elements\\u000a that lead to anisotropic cell expansion in rapidly elongating cells has increased by finding mutants with altered root growth\\u000a behavior as well
Laura M. Vaughn; Katherine L. Baldwin; Gengxiang Jia; Julian C. Verdonk; Allison K. Strohm; Patrick H. Masson
307
PubMed
Rare earth pollution and acid rain pollution are both important environmental issues worldwide. In regions which simultaneously occur, the combined pollution of rare earth and acid rain becomes a new environmental issue, and the relevant research is rarely reported. Accordingly, we investigated the combined effects and mechanisms of lanthanum ion (La(3+)) and acid rain on the root phenotype of soybean seedlings. The combined pollution of low-concentration La(3+) and acid rain exerted deleterious effects on the phenotype and growth of roots, which were aggravated by the combined pollution of high-concentration La(3+) and acid rain. The deleterious effects of the combined pollution were stronger than those of single La(3+) or acid rain pollution. These stronger deleterious effects on the root phenotype and growth of roots were due to the increased disturbance of absorption and utilization of mineral nutrients in roots. PMID:23726884
Sun, Zhaoguo; Wang, Lihong; Zhou, Qing; Huang, Xiaohua
2013-09-01
308
The light environment of a plant shoot can affect its root size and the shoot\\/root biomass ratio. Photoperiodic influence on shoot\\/root ratios of first?year biennial sweetclover (Melilotus alba Desr.) plants was related to phytochrome measurement of day length and its regulation of photosynthate partitioning to favor successful completion of the life cycle. Short photoperiods alternated with long, uninterrupted nights resulted
M. J. Kasperbauer; P. G. Hunt
1992-01-01
309
The rooting capacities of tips of seedling, juvenile and mature shoots of Sequoiadendron giganteum were compared on different rooting media (inductive and expressive media) after passage on an elongating medium. None of the cuttings rooted when continuously kept on medium containing the auxin NAA and vitamin D2. Peroxidase activity of all those cuttings on NAA+D2 first increased during the 7–9
J. Y. Berthon; N. Boyer; Th. Gaspar
1987-01-01
310
Plants are endangered at their roots by soil-dwelling rhizophagous insects. These below-ground living herbivores may orient to the source of carbon dioxide (CO2), an ubiquitous volatile released by respiring plant roots. Here, we studied the interaction of CO2 and other plant root-derived chemical stimuli with regard to the chemical orientation of the polyphagous larvae of Melolontha melolontha L. (Scarabaeidae). A
Andreas Reinecke; Frank Müller; Monika Hilker
2008-01-01
311
The manner in which water and energy is partitioned and redistributed along a hillslope is the result of complex coupled ecohydrological interactions between the climatic, soils, topography and vegetation operating over a wide range of spatiotemporal scales. Distributed process based modeling creates a framework through which the interaction of vegetation with the subtle differences in the spatial and temporal dynamics of soil moisture that arise under localized abiotic conditions along a hillslope can be simulated and examined. One deficiency in the current dynamic vegetation models is the one sided manner in which vegetation responds to soil moisture dynamics. Above ground, vegetation is given the freedom to dynamically evolve through alterations in fractional vegetation cover and/or canopy height and density; however below ground rooting profiles are simplistically represented and often held constant in time and space. The need to better represent the belowground role of vegetation through dynamic rooting strategies is fundamental in capturing the magnitude and timing of water and energy fluxes between the atmosphere and land surface. In order to allow vegetation to adapt to gradients in soil moisture a dynamic rooting scheme was incorporated into tRIBS+VEGGIE (a physically based distributed ecohydrological model). The dynamic rooting scheme allows vegetation the freedom to adapt their rooting depth and distribution in response abiotic conditions in a way that more closely mimics observed plant behavior. The incorporation of this belowground plasticity results in vegetation employing a suite of rooting strategies based on soil texture, climatic conditions and location on the hillslope.
Sivandran, G.; Bras, R. L.
2011-12-01
312
E-print Network
Let $C$ be a curve in a closed orientable surface $F$ of genus $g \\geq 2$ that separates $F$ into subsurfaces $\\widetilde {F_i}$ of genera $g_i$, for $i = 1,2$. We study the set of roots in $\\Mod(F)$ of the Dehn twist $t_C$ about $C$. All roots arise from pairs of $C_{n_i}$-actions on the $\\widetilde{F_i}$, where $n=\\lcm(n_1,n_2)$ is the degree of the root, that satisfy a certain compatibility condition. The $C_{n_i}$ actions are of a kind that we call nestled actions, and we classify them using tuples that we call data sets. The compatibility condition can be expressed by a simple formula, allowing a classification of all roots of $t_C$ by compatible pairs of data sets. We use these data set pairs to classify all roots for $g = 2$ and $g = 3$. We show that there is always a root of degree at least $2g^2+2g$, while $n \\leq 4g^2+2g$. We also give some additional applications.
Rajeevsarathy, Kashyap
2011-01-01
313
PubMed Central
Land plants associate with a root microbiota distinct from the complex microbial community present in surrounding soil. The microbiota colonizing therhizosphere(immediately surroundingthe root) and the endophytic compartment (within the root) contribute to plant growth, productivity, carbon sequestration and phytoremediation1-3. Colonization of the root occurs despite a sophisticated plant immune system4,5, suggesting finely tuned discrimination of mutualists and commensals from pathogens. Genetic principles governing the derivation of host-specific endophyte communities from soil communities are poorly understood. Here we report the pyrosequencing of the bacterial 16S ribosomal RNA gene of more than 600 Arabidopsis thaliana plants to test the hypotheses that the root rhizosphere and endophytic compartment microbiota of plants grown under controlled conditions in natural soils are sufficiently dependent on the host to remain consistent across different soil types and developmental stages, and sufficiently dependent on host genotype to vary between inbred Arabidopsis accessions. We describe different bacterial communities in two geochemically distinct bulk soils and in rhizosphere and endophytic compartments prepared from roots grown in these soils. The communities in each compartment are strongly influenced by soil type. Endophytic compartments from both soils feature overlapping, low-complexity communities that are markedly enriched in Actinobacteria and specific families from other phyla, notably Proteobacteria. Some bacteria vary quantitatively between plants of different developmental stage and genotype. Our rigorous definition of an endophytic compartment microbiome should facilitate controlled dissection of plantmicrobe interactions derived from complex soil communities. PMID:22859206
Gehring, Jase; Malfatti, Stephanie; Tremblay, Julien; Engelbrektson, Anna; Kunin, Victor; del Rio, Tijana Glavina; Edgar, Robert C.; Eickhorst, Thilo; Ley, Ruth E.; Hugenholtz, Philip; Tringe, Susannah Green; Dangl, Jeffery L.
2014-01-01
314
PubMed
Plant responses to competition have often been described as passive consequences of reduced resource availability. However, plants have mechanisms to forage for favorable conditions and anticipate competition scenarios. Despite the progresses made in understanding the role of light signaling in modulating plant-plant interactions, little is known about how plants use and integrate information gathered by their photoreceptors aboveground to regulate performance belowground. Given that the phytochrome family of photoreceptors plays a key role in the acquisition of information about the proximity of neighbors and canopy cover, it is tempting to speculate that changes in the red:far-red (R:FR) ratio perceived by aboveground plant parts have important implications shaping plant behavior belowground. Exploring data from published experiments, we assess the neglected role of light signaling in the control of root function. The available evidence indicates that plant exposure to low R:FR ratios affects root growth and morphology, root exudate profiles, and interactions with beneficial soil microorganisms. Although dependent on species identity, signals perceived aboveground are likely to affect root-to-root interactions. Root systems could also be guided to deploy new growth predominantly in open areas by light signals perceived by the shoots. Studying interactions between above- and belowground plant-plant signaling is expected to improve our understanding of the mechanisms of plant competition. PMID:24894371
Gundel, Pedro E; Pierik, Ronald; Mommer, Liesje; Ballaré, Carlos L
2014-09-01
315
PubMed Central
Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502
Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj
2014-01-01
316
Physiology of the root system is dependent upon oxygen availability and tissue respiration. During hypoxia nutrient and water acquisition may be inhibited, thus affecting the overall biochemical and physiological status of the plant. For the Astroculture™ plant growth hardware, the availability of oxygen in the root zone was measured by examining the changes in alcohol dehydrogenase (ADH) activity within the root tissue. ADH activity is a sensitive biochemical indicator of hypoxic conditions in plants and was measured in both spaceflight and control roots. In addition to the biochemical enzyme assays, localization of ADH in the root tissue was examined cytochemically. The results of these analyses showed that ADH activity increased significantly as a result of spaceflight exposure. Enzyme activity increased 248% to 304% in dwarf wheat when compared with the ground controls and Brassica showed increases between 334% and 579% when compared with day zero controls. Cytochemical staining revealed no differences in ADH tissue localization in any of the dwarf wheat treatments. These results show the importance of considering root system oxygenation in designing and building nutrient delivery hardware for spaceflight plant cultivation and confirm previous reports of an ADH response associated with spaceflight exposure
Porterfield, D. M.; Barta, D. J.; Ming, D. W.; Morrow, R. C.; Musgrave, M. E.
317
PubMed Central
Tomato (Solanum lycopersicum) crops can be severely damaged due to parasitism by the root-knot nematode (RKN) Meloidogyne incognita, but are protected when intercropped with crown daisy (Chrysanthemum coronarium L.). Root exudate may be the determining factor for this protection. An experiment using pots linked by a tube and Petri dish experiments were undertaken to confirm that tomato–crown daisy intercropping root exudate decreased the number of nematodes and alleviated nematode damage, and to determine crown daisy root exudate-regulated nematode chemotaxis. Following a gas chromatography–mass spectrometry assay, it was found that the intercropping protection was derived from the potent bioactivity of a specific root exudate component of crown daisy, namely lauric acid. The Mi-flp-18 gene, encoding an FMRFamide-like peptide neuromodulator, regulated nematode chemotaxis and infection by RNA interference. Moreover, it was shown that lauric acid acts as both a lethal trap and a repellent for M. incognita by specifically regulating Mi-flp-18 expression in a concentration-dependent manner. Low concentrations of lauric acid (0.5–2.0mM) attract M. incognita and consequently cause death, while high concentrations (4.0mM) repel M. incognita. This study elucidates how lauric acid in crown daisy root exudate regulates nematode chemotaxis and disrupts Mi-flp-18 expression to alleviate nematode damage, and presents a general methodology for studying signalling systems affected by plant root exudates in the rhizosphere. This could lead to the development of economical and feasible strategies for controlling plant-parasitic nematodes, and provide an alternative to the use of pesticides in farming systems. PMID:24170741
Zuo, Yuanmei
2014-01-01
318
PubMed Central
With the aid of an extracellular vibrating electrode, natural electric fields were detected and measured in the medium near growing roots and root hairs of barley seedlings. An exploration of these fields indicates that both the root as a whole, as well as individual root hairs, drive large steady currents through themselves. Current consistently enters both the main elongation zone of the root as well as the growing tips of elongating root hairs; it leaves the surface of the root beneath the root hairs. These currents enter with a density of about 2 microamperes per square centimeter, leave with a density of about 0.5 to 1 microampere per square centimeter, and total about 30 nanoamperes. Responses of the natural fields to changes in the ionic composition of the medium as well as observations of the pH pattern in the medium near the roots (made with bromocresol purple) together indicate that much of the current consists of hydrogen ions. Altogether, H+ ions seem to leak into growing cells or cell parts and to be pumped out of nongrowing ones. Images PMID:16661000
Weisenseel, Manfred H.; Dorn, Alfred; Jaffe, Lionel F.
1979-01-01
319
PubMed
The plant root is the first organ to encounter salinity stress, but the effect of salinity on root system architecture (RSA) remains elusive. Both the reduction in main root (MR) elongation and the redistribution of the root mass between MRs and lateral roots (LRs) are likely to play crucial roles in water extraction efficiency and ion exclusion. To establish which RSA parameters are responsive to salt stress, we performed a detailed time course experiment in which Arabidopsis (Arabidopsis thaliana) seedlings were grown on agar plates under different salt stress conditions. We captured RSA dynamics with quadratic growth functions (root-fit) and summarized the salt-induced differences in RSA dynamics in three growth parameters: MR elongation, average LR elongation, and increase in number of LRs. In the ecotype Columbia-0 accession of Arabidopsis, salt stress affected MR elongation more severely than LR elongation and an increase in LRs, leading to a significantly altered RSA. By quantifying RSA dynamics of 31 different Arabidopsis accessions in control and mild salt stress conditions, different strategies for regulation of MR and LR meristems and root branching were revealed. Different RSA strategies partially correlated with natural variation in abscisic acid sensitivity and different Na(+)/K(+) ratios in shoots of seedlings grown under mild salt stress. Applying root-fit to describe the dynamics of RSA allowed us to uncover the natural diversity in root morphology and cluster it into four response types that otherwise would have been overlooked. PMID:25271266
Julkowska, Magdalena M; Hoefsloot, Huub C J; Mol, Selena; Feron, Richard; de Boer, Gert-Jan; Haring, Michel A; Testerink, Christa
2014-11-01
320
PubMed Central
We present a novel image analysis tool that allows the semiautomated quantification of complex root system architectures in a range of plant species grown and imaged in a variety of ways. The automatic component of RootNav takes a top-down approach, utilizing the powerful expectation maximization classification algorithm to examine regions of the input image, calculating the likelihood that given pixels correspond to roots. This information is used as the basis for an optimization approach to root detection and quantification, which effectively fits a root model to the image data. The resulting user experience is akin to defining routes on a motorist’s satellite navigation system: RootNav makes an initial optimized estimate of paths from the seed point to root apices, and the user is able to easily and intuitively refine the results using a visual approach. The proposed method is evaluated on winter wheat (Triticum aestivum) images (and demonstrated on Arabidopsis [Arabidopsis thaliana], Brassica napus, and rice [Oryza sativa]), and results are compared with manual analysis. Four exemplar traits are calculated and show clear illustrative differences between some of the wheat accessions. RootNav, however, provides the structural information needed to support extraction of a wider variety of biologically relevant measures. A separate viewer tool is provided to recover a rich set of architectural traits from RootNav’s core representation. PMID:23766367
Pound, Michael P.; French, Andrew P.; Atkinson, Jonathan A.; Wells, Darren M.; Bennett, Malcolm J.; Pridmore, Tony
2013-01-01
321
PubMed Central
The inhibitory effects of indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylic acid (ACC) on elongation growth of pea (Pisum sativum L.) seedling roots were investigated in relation to the effects of these compounds on ethylene production by the root tips. When added to the growth solution both compounds caused a progressively increasing inhibition of growth within the concentration range of 0.01 to 1 micromolar. However, only ACC increased ethylene production in root tips excised from the treated seedlings after 24 hours. High auxin concentrations caused a transitory increase of ethylene production during a few hours in the beginning of the treatment period, but even in 1 micromolar IAA this increase was too low to have any appreciable effect on growth. ACC, but not IAA, caused growth curvatures, typical of ethylene treatment, in the root tips. IAA caused conspicuous swelling of the root tips while ACC did not. Cobalt and silver ions reversed the growth inhibitory effects induced by ACC but did not counteract the inhibition of elongation or swelling caused by IAA. The growth effects caused by the ACC treatments were obviously due to ethylene production. We found no evidence to indicate that the growth inhibition or swelling caused by IAA is mediated by ethylene. It is concluded that the inhibitory action of IAA on root growth is caused by this auxin per se. PMID:16667017
Eliasson, Lennart; Bertell, Gertrud; Bolander, Eva
1989-01-01
322
Phototropism as well as gravitropism plays a role in the oriented growth of roots in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism in Arabidopsis roots. Phytochrome A (phyA) and phyB mediate the positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. In blue-light-based negative phototropism, phyA and phyAB (but not phyB) were inhibited in the response relative to the WT. In root gravitropism, phyB and phyAB (but not phyA) were inhibited in the response compared to the WT. The differences observed in tropistic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in roots and that phytochrome plays a key role in plant development by integrating multiple environmental stimuli.
Correll, Melanie J.; Coveney, Katrina M.; Raines, Steven V.; Mullen, Jack L.; Hangarter, Roger P.; Kiss, John Z.
2003-05-01
323
NASA Technical Reports Server (NTRS)
Phototropism as well as gravitropism plays a role in the oriented growth of roots in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism in Arabidopsis roots. Phytochrome A (phyA) and phyB mediate the positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. In blue-light-based negative phototropism, phyA and phyAB (but not phyB) were inhibited in the response relative to the WT. In root gravitropism, phyB and phyAB (but not phyA) were inhibited in the response compared to the WT. The differences observed in tropistic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in roots and that phytochrome plays a key role in plant development by integrating multiple environmental stimuli. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.
Correll, Melanie J.; Coveney, Katrina M.; Raines, Steven V.; Mullen, Jack L.; Hangarter, Roger P.; Kiss, John Z.
2003-01-01
324
PubMed
Due to its wide industrial use, chromium is considered a serious environmental pollutant. Contamination of soil and water by chromium (Cr) is of recent concern. Chromium mainly accumulates in root in plants, and the change in compounds of the root cell wall have a close relation with the Cr accumulation. Compared with the other identification methods, the identification of the Chinese traditional and herbal drugs using Fourier transform infrared spectrometer with OMNI collector is simple and convenient, fast and accurate. In the present paper, the spectra of cell wall of Cr-treated root and control of Eichhornia crassipes and Alternanthera philoxeroides were determined. Absorption peaks were identified to the corresponding functional groups and half-quantitative analysis was also used. The results showed that a significant shift of -OH absorption peaks can be seen when comparing the FTIR spectra of control and Cr-treated plants, and the absorbency of -OH and COO- groups went up in E. crassipes root cell wall while droped in A. philoxeroides root cell wall. It is suggested that -OH and COO groups were referred in binding Cr6+ in aqueous solutions, and this may be included in the mechanism of Cr accumulation in E. crassipes roots. Therefore, FTIR spectrometry could be widely used to monitor changes in chemical composition of plant parts under stresses and environmental restoration. PMID:18720803
Zhang, Xiao-Bin; Liu, Peng; Li, Dan-Ting; Xu, Gen-Di; Jiang, Min-Jiao
2008-05-01
325
Sequential soil coring is a commonly used approach to measure seasonal root biomass and necromass, from which root production can be estimated by maximum-minimum, sum of changes, compartment-flow model, and/or decision matrix methods. Among these methods, decision matrix is the most frequently used. However, the decision matrix, often underestimating fine root production, is frequently misused in research due to inadequate documentation of its underlying logic. In this paper, we reviewed the decision matrix method and provided mathematical logic for the development of the matrix, by which not only root production but also mortality and decomposition rates can be calculated. To ease its use for large datasets, we developed simplified equations to facilitate computation of root production, mortality and decomposition to be used in MS Excel or R. We also presented results from calculations by an example using empirical data from boreal forests to show proper calculations of root production, mortality and decomposition. The simplified decision matrix presented here shall promote its application in ecology, especially for large datasets.
Yuan, Z. Y.; Chen, Han Y. H.
2013-04-01
326
NASA Technical Reports Server (NTRS)
No straightforward method exists for separating the proportion of ion exchange and respiration due to rhizoplane microbial organisms from that of root ion exchange and respiration. We examined several antibiotics that might be used for the temporary elimination of rhizoplane bacteria from hydroponically grown wheat roots (Triticum aestivum cv. Veery 10). Each antibiotic was tested for herbicidal activity and plate counts were used to enumerate bacteria and evaluate antibiotic kinetics. Only lactam antibiotics (penicillins and cephalosporins) did not reduce wheat growth rates. Aminoglycosides, the pyrimidine trimethoprim, colistin and rifampicin reduced growth rates substantially. Antibiotics acted slowly, with maximum reductions in rhizoplane bacteria occurring after more than 48 h of exposure. Combinations of nonphytotoxic antibiotics reduced platable rhizoplane bacteria by as much as 98%; however, this was generally a reduction from about 10(9) to 10(6) colony forming units per gram of dry root mass, so that many viable bacteria remained on root surfaces. We present evidence which suggests that insufficient bacterial biomass exists on root surfaces of nonstressed plants grown under well-aerated conditions to quantitatively interfere with root nitrogen absorption measurements.
Smart, D. R.; Ferro, A.; Ritchie, K.; Bugbee, B. G.
1995-01-01
327
BACKGROUND: Nitrogen (N), the primary limiting factor for plant growth and yield in agriculture, has a patchy distribution in soils due to fertilizer application or decomposing organic matter. Studies in solution culture over-simplify the complex soil environment where microbial competition and spatial and temporal heterogeneity challenge roots' ability to acquire adequate amounts of nutrients required for plant growth. In this
Daniel R Ruzicka; Felipe H Barrios-Masias; Natasha T Hausmann; Louise E Jackson; Daniel P Schachtman
2010-01-01
328
Diffusion of ions in the soil depends on soil moisture content. In a dry soil, transport of nutrients towards the root and the concomitant uptake could be reduced. However, pot and field experiments showed that this is not always the case. The objective of this paper was to investigate possible mechanisms of plants to counteract reduced nutrient supply due to
Horst Liebersbach; Bernd Steingrobe; Norbert Claassen
2004-01-01
329
It is widely reported in the literature that interest rates follow integrated processes. Many empirical studies have, in fact, taken this result as a maintained hypothesis. This article demonstrates that the failure to reject the hypothesis that interest rates contain a unit root may be due to the severe power problem of standard test procedures in small samples. We analyze
YANGRU Wu; HUA Zhang
1997-01-01
330
PubMed Central
Background and Aims Biomass partitioning for resource conservation might affect plant allometry, accounting for a substantial amount of unexplained variation in existing plant allometry models. One means of resource conservation is through direct allocation to storage in particular organs. In this study, storage allocation and biomass allometry of deciduous and evergreen tree species from seasonal environments were considered. It was expected that deciduous species would have greater allocation to storage in roots to support leaf regrowth in subsequent growing seasons, and consequently have lower scaling exponents for leaf to root and stem to root partitioning, than evergreen species. It was further expected that changes to root carbohydrate storage and biomass allometry under different soil nutrient supply conditions would be greater for deciduous species than for evergreen species. Methods Root carbohydrate storage and organ biomass allometries were compared for juveniles of 20 savanna tree species of different leaf habit (nine evergreen, 11 deciduous) grown in two nutrient treatments for periods of 5 and 20 weeks (total dry mass of individual plants ranged from 0·003 to 258·724 g). Key Results Deciduous species had greater root non-structural carbohydrate than evergreen species, and lower scaling exponents for leaf to root and stem to root partitioning than evergreen species. Across species, leaf to stem scaling was positively related, and stem to root scaling was negatively related to root carbohydrate concentration. Under lower nutrient supply, trees displayed increased partitioning to non-structural carbohydrate, and to roots and leaves over stems with increasing plant size, but this change did not differ between leaf habits. Conclusions Substantial unexplained variation in biomass allometry of woody species may be related to selection for resource conservation against environmental stresses, such as resource seasonality. Further differences in plant allometry could arise due to selection for different types of biomass allocation in response to different environmental stressors (e.g. fire vs. herbivory). PMID:23877001
Tomlinson, Kyle W.; van Langevelde, Frank; Ward, David; Bongers, Frans; da Silva, Dulce Alves; Prins, Herbert H. T.; de Bie, Steven; Sterck, Frank J.
2013-01-01
331
PubMed
Depth and area of rooting are important to long-term survival of plants on metal-contaminated, steep-slope soils. We evaluated shoot and root growth and metal uptake of four cool-season grasses grown on a high-Zn soil in a greenhouse. A mixture of biosolids, fly ash, and burnt lime was placed either directly over a Zn-contaminated soil or over a clean, fine-grained topsoil and then the Zn-contaminated soil; the control was the clean topsoil. The grasses were 'Reliant' hard fescue (Festuca brevipila R. Tracey), 'Oahe' intermediate wheatgrass [Elytrigia intermedia (Host) Nevski subsp. intermedia], 'Ruebens' Canada bluegrass (Poa compressa L.), and 'K-31' tall fescue (Festuca arundinacea Schreb.). Root growth in the clean soil and biosolids corresponded to the characteristic rooting ability of each species, while rooting into the Zn-contaminated soil was related to the species' tolerance to Zn. While wheatgrass and tall fescue had the strongest root growth in the surface layers (0-5 cm) of clean soil or biosolids, wheatgrass roots were at least two times more dense than those of the other grasses in the second layer (5-27 cm) of Zn-contaminated soil. When grown over Zn-contaminated soil in the second layer, hard fescue (with 422 mg/kg Zn) was the only species not to have phytotoxic levels of Zn in shoots; tall fescue had the highest Zn uptake (1553 mg/kg). Thus, the best long-term survivors in high-Zn soils should be wheatgrass, due to its ability to root deeply into Zn-contaminated soils, and hard fescue, with its ability to effectively exclude toxic Zn uptake. PMID:12809284
Palazzo, Antonio J; Cary, Timothy J; Hardy, Susan E; Lee, C Richard
2003-01-01
332
E-print Network
Root systems can influence the dynamics of evapotranspiration of water out of a porous medium. The coupling of evapotranspiration remains a key aspect affecting overall root behavior. Predicting the evapotranspiration curve in the presence of roots helps keep track of the amount of water that remains in the porous medium. Using a controlled visual set-up of a 2D model soil system consisting of monodisperse glass beads, we first perform experiments on actual roots grown in partially saturated systems under different relative humidity conditions. We record parameters such as the total mass loss in the medium and the resulting position of the receding fronts and use these experimental results to develop a simple analytical model that predicts the position of the evaporating front as a function of time as well as the total amount of water that is lost from the medium due to the combined effects of evaporation and transpiration. The model is based on fundamental principles of evaporation flux and includes empirical assumptions on the quantity of stoma in the leaves and the transition time between regime 1 and regime 2. The model also underscores the importance of a much prolonged root life as long as the root is exposed to a partially saturated zone composed of a mixture of air and water. Comparison between the model and experimental results shows good prediction of the position of the evaporating front as well as the total mass loss from evapotranspiration in the presence of real root systems. These results provide additional understanding of both complex evaporation phenomenon and its influence on root mechanisms.
Cesare M. Cejas; Larry Hough; Jean-Christophe Castaing; Christian Fretigny; Remi Dreyfus
2014-06-17
333
PubMed Central
Background We have limited understanding of root foraging responses when plants were simultaneously exposed to nutrient heterogeneity and competition, and our goal was to determine whether and how plants integrate information about nutrients and neighbors in root foraging processes. Methodology/Principal Findings The experiment was conducted in split-containers, wherein half of the roots of spruce (Picea asperata) seedlings were subjected to intraspecific root competition (the vegetated half), while the other half experienced no competition (the non-vegetated half). Experimental treatments included fertilization in the vegetated half (FV), the non-vegetated half (FNV), and both compartments (F), as well as no fertilization (NF). The root architecture indicators consisted of the number of root tips over the root surface (RTRS), the length percentage of diameter-based fine root subclasses to total fine root (SRLP), and the length percentage of each root order to total fine root (ROLP). The target plants used novel root foraging behaviors under different combinations of neighboring plant and localized fertilization. In addition, the significant increase in the RTRS of 0–0.2 mm fine roots after fertilization of the vegetated half alone and its significant decrease in fertilizer was applied throughout the plant clearly showed that plant root foraging behavior was regulated by local responses coupled with systemic control mechanisms. Conclusions/Significance We measured the root foraging ability for woody plants by means of root architecture indicators constructed by the roots possessing essential nutrient uptake ability (i.e., the first three root orders), and provided new evidence that plants integrate multiple forms of environmental information, such as nutrient status and neighboring competitors, in a non-additive manner during the root foraging process. The interplay between the responses of individual root modules (repetitive root units) to localized environmental signals and the systemic control of these responses may well account for the non-additive features of the root foraging process. PMID:23762405
Nan, Hongwei; Liu, Qing; Chen, Jinsong; Cheng, Xinying; Yin, Huajun; Yin, Chunying; Zhao, Chunzhang
2013-01-01
334
Post harvest of cassava roots has been a great concern in food industries and producers due to the short shelf life and high perishability. Several phenomena have been pointed out as responsible for root deterioration. Among them there are physiological aspects, that lead to losses in initial quality through vascular discoloration of parenchymatous tissue. On the other hand, phenomena from
Andreia Alves; Rogério Luis Cansian; Giane Stuart; Eunice Valduga
335
BACKGROUND: Eucalyptus globulus and its hybrids are very important for the cellulose and paper industry mainly due to their low lignin content and frost resistance. However, rooting of cuttings of this species is recalcitrant and exogenous auxin application is often necessary for good root development. To date one of the most accurate methods available for gene expression analysis is quantitative
Márcia R de Almeida; Carolina M Ruedell; Felipe K Ricachenevsky; Raul A Sperotto; Giancarlo Pasquali; Arthur G Fett-Neto
2010-01-01
336
PubMed
Apoplastic fluid was extracted from maize (Zea mays L.) roots using two procedures: collection from the surface of intact plant roots by filter paper strips (AF) or vacuum infiltration and/or centrifugation from excised root segments (AWF). The content of cytoplasmic marker (glucose-6-phosphate, G-6-P) and antioxidative components (enzymes, organic acids, phenolics, sugars, ROS) were compared in the extracts. The results obtained demonstrate that AF was completely free of G-6-P, as opposed to AWF where the cytoplasmic constituent was detected even at mildest centrifugation (200×g). Isoelectric focusing of POD and SOD shows the presence of cytoplasmic isoforms in AWF, and HPLC of sugars and phenolics a much more complex composition of AWF, due to cytoplasmic contamination. Organic acid composition differed in the two extracts, much higher concentrations of malic acid being registered in AF, while oxalic acid due to intracellular contamination being present only in AWF. EPR spectroscopy of DEPMPO spin trap in the extracts showed persistent generation of hydroxyl radical adduct in AF. The results obtained argue in favor of the filter strip method for the root apoplastic fluid extraction, avoiding the problems of cytoplasmic contamination and dilution and enabling concentration measurements in minute regions of the root. PMID:24767115
Dragiši? Maksimovi?, Jelena J; Zivanovi?, Branka D; Maksimovi?, Vuk M; Mojovi?, Miloš D; Nikolic, Miroslav T; Vu?ini?, Zeljko B
2014-06-01
337
PubMed
Tip growth is one of the most preferable models in the study of plant cell polarity; cell wall deposition is restricted mainly to a certain area of the cell, and cell expansion at this specific area leads to the development of tubular outgrowth. Tip-growing root hairs are well-established systems for such studies, because their lateral position within the root makes them easily accessible for experimental approaches and microscopic observations. Fundamental structural and molecular processes driving tip growth are exocytosis, endocytosis, and all aspects of vesicular and endosomal dynamic trafficking, as related to targeted membrane flow. Study of vesicles and endosomes in living root hairs, however, is rather difficult, due to their small size and due to the resolution limits of conventional light microscopes. Here we present noninvasive approaches for visualizing vesicular and endosomal compartments in the tip of growing root hairs using electronic light microscopy, contrast-enhanced video light microscopy, and confocal laser scanning microscopy (CLSM). These methods allow utilizing the maximum resolution of the light microscope. Together with protocols for appropriate preparation of living plant samples, the described methods should help improve our understanding on how tiny vesicles and endosomes support the process of tip growth in root hairs. PMID:25117273
Ove?ka, Miroslav; Lichtscheidl, Irene; Samaj, Jozef
2014-01-01
338
PubMed
Plant root architecture is regulated by the initiation and modulation of cell division in regions containing pluripotent stem cells known as meristems. In roots, meristems are formed early in embryogenesis, in the case of the root apical meristem (RAM), and during organogenesis at the site of lateral root or, in legumes, nodule formation. Root meristems can also be generated in vitro from leaf explants cultures supplemented with auxin. microRNAs (miRNAs) have emerged as regulators of many key biological functions in plants including root development. To identify key miRNAs involved in root meristem formation in Medicago truncatula, we used deep sequencing to compare miRNA populations. Comparisons were made between: (1) the root tip (RT), containing the RAM and the elongation zone (EZ) tissue and (2) root forming callus (RFC) and non-root forming callus (NRFC). We identified 83 previously reported miRNAs, 24 new to M. truncatula, in 44 families. For the first time in M. truncatula, members of conserved miRNA families miR165, miR181 and miR397 were found. Bioinformatic analysis identified 38 potential novel miRNAs. Selected miRNAs and targets were validated using Taqman miRNA assays and 5' RACE. Many miRNAs were differentially expressed between tissues, particularly RFC and NRFC. Target prediction revealed a number of miRNAs to target genes previously shown to be differentially expressed between RT and EZ or RFC and NRFC and important in root development. Additionally, we predict the miRNA/target relationships for miR397 and miR160 to be conserved in M. truncatula. Amongst the predictions, were AUXIN RESPONSE FACTOR 10, targeted by miR160 and a LACCASE-like gene, targeted by miR397, both are miRNA/target pairings conserved in other species. PMID:23572382
Eyles, Rodney P; Williams, Philip H; Ohms, Stephen J; Weiller, Georg F; Ogilvie, Huw A; Djordjevic, Michael A; Imin, Nijat
2013-07-01
339
Root systems of three clovers and five pasture grasses grown in sand culture during summer and in soil during winter were examined at two stages of growth.There were large differences in shoot\\/root ratio between harvests, but no consistent differences among species. In general grasses had longer, thinner, more finely branched roots than clovers, but had similar root surface areas per
P. S. Evans
1977-01-01
340
We tested a hypothesis that variable precipitation may induce altered rooting patterns. A nursery study was conducted over 2 years to evaluate the effect of seasonally variable soil moisture on the rooting pattern of shallow-rooted shrub broom snakeweed (Gutierrezia sarothrae Britt and Rusby). Plants irrigated during the spring–summer, but grown under rainout shelters in the winter (S) produced more roots
Changgui Wan; Ibrahim Yilmaz; Ronald E. Sosebee
2002-01-01
341
Although water uptake by roots in the soil has been investigated in numerous studies, it is still not clear which is the main factor controlling the uptake, especially under non-uniform soil moisture distribution or intermediately wet soil. Root activity or root compensation factors are frequently used to adjust 1-D root water uptake models to observations. However, they are fitting parameters,
Sarah Garre; Jan Vanderborght; Mathieu Javaux; Harry Vereecken
2010-01-01
342
The fine roots of trees are concentrated on lateral branches that arise from perennial roots. They are important in the acquisition of water and essential nutrients, and at the ecosystem level, they make a significant contribution to biogeochemical cycling. Fine roots have often been studied according to arbitrary size classes, e.g., all roots less than 1 or 2 mm in
Kurt S. Pregitzer; Jared L. DeForest; Andrew J. Burton; Michael F. Allen; Roger W. Ruess; Ronald L. Hendrick
2002-01-01
343
EPA Science Inventory
A rootbox is described which allows observation of an intact, entire root system. oots are sandwiched against a plexiglass surface by a nylon mesh that is impermeable to roots, but permeable to water and nutrients. o quantify root growth non-destructively, roots of different size...
344
Root hairs are presumably important in the acquisition of immobile soil resources such as phosphorus. The density and length of root hairs vary substantially within and between species, and are highly regulated by soil phosphorus availability, which suggests that at high nutrient availability, root hairs may have a neutral or negative impact on fitness. We used a root-hairless mutant of
Terence R. Bates; Jonathan P. Lynch
2001-01-01
345
Normal root of Hyoscyamus niger was cultivated in various nutrient conditions to optimize root growth and scopolamine production. Nitrate or phosphate concentration had little effect on root growth, while the low levels of nitrate or phosphate enhanced specific scopolamine content by 44% and 39%, respectively. Glucose or fructose was not adequate for the root culture as a carbon source, while
Seung Han Woo; Jong Moon Park; Ji-Won Yang
1995-01-01
346
Nitrogen-fixing bacteria are able to enter into roots from the rhizosphere, particularly at the base of emerging lateral roots, between epidermal cells and through root hairs. In the rhizosphere growing root hairs play an important role in symbiotic recognition in legume crops. Nodulated legumes in endosymbiosis with rhizobia are amongst the most prominent nitrogen-fixing systems in agriculture. The inoculation of
Edward C. Cocking
2003-01-01
347
PubMed Central
Background Almost all land plants develop tip-growing filamentous cells at the interface between the plant and substrate (the soil). Root hairs form on the surface of roots of sporophytes (the multicellular diploid phase of the life cycle) in vascular plants. Rhizoids develop on the free-living gametophytes of vascular and non-vascular plants and on both gametophytes and sporophytes of the extinct rhyniophytes. Extant lycophytes (clubmosses and quillworts) and monilophytes (ferns and horsetails) develop both free-living gametophytes and free-living sporophytes. These gametophytes and sporophytes grow in close contact with the soil and develop rhizoids and root hairs, respectively. Scope Here we review the development and function of rhizoids and root hairs in extant groups of land plants. Root hairs are important for the uptake of nutrients with limited mobility in the soil such as phosphate. Rhizoids have a variety of functions including water transport and adhesion to surfaces in some mosses and liverworts. Conclusions A similar gene regulatory network controls the development of rhizoids in moss gametophytes and root hairs on the roots of vascular plant sporophytes. It is likely that this gene regulatory network first operated in the gametophyte of the earliest land plants. We propose that later it functioned in sporophytes as the diploid phase evolved a free-living habit and developed an interface with the soil. This transference of gene function from gametophyte to sporophyte could provide a mechanism that, at least in part, explains the increase in morphological diversity of sporophytes that occurred during the radiation of land plants in the Devonian Period. PMID:22730024
Jones, Victor A.S.; Dolan, Liam
2012-01-01
348
The question of how to foster rooting in science education points towards a double challenge; efforts to prevent (further) uprooting and efforts to promote rooting/re-rooting. Wolff-Michael Roth's paper discusses the uprooting/rooting pair of concepts, students' feeling of alienation and loss of fundamental sense of the earth as ground, and potential consequences for teaching science in a rooted manner. However, the argumentation raises a number of questions which I try to answer. My argumentation rests on Husserl's critique of science and the "ontological reversal", an ontological position where abstract models from science are considered as more real than the everyday reality itself, where abstract, often mathematical, models are taken to be the real causes behind everyday experiences. In this paper, measures towards an "ontological re-reversal" are discussed by drawing on experiences from phenomenon-based science education. I argue that perhaps the most direct and productive way of promoting rooting in science class is by intentionally cultivating the competencies of sensing and aesthetic experience. An aesthetic experience is defined as a precognitive, sensuous experience, an experience that is opened up for through sensuous perception. Conditions for rooting in science education is discussed against three challenges: Restoring the value of aesthetic experience, allowing time for open inquiry and coping with curriculum. Finally, I raise the question whether dimensions like "reality" or "nature" are self-evident for students. In the era of constructivism, with its focus on cognition and knowledge building, the inquiry process itself has become more important than the object of inquiry. I argue that as educators of science teachers we have to emphasize more explicitly "the nature of nature" as a field of exploration.
Østergaard, Edvin
2014-06-01
349
PubMed
The alkali preparation of the root and fresh leaf juice of Moringa oleifera possessed significant dose -depen-dent anti-ulcer activity in experimentally induced acute gastric ulcers with aspirin, the anti-ulcer effect of the alkali preparation of the root seems to be more pronounced than that of the fresh leaf juice. Te anti-ulcer activity of the alkali preparation of the root could be due to its content of alkaloids or its anticholinergic and antihistaminic activities, or a combination of these factors. PMID:22556845
Ruckmani, K; Kavimani, S; Jayakar, B; Anandan, R
1998-01-01
350
PubMed Central
Introduction Objective of this study was to investigate the incidence and severity of apical root resorptions (ARR) during orthodontic treatment with aligners. Materials and methods The sample comprised 100 patients (17–75 years of age) with a class I occlusion and anterior crowding before treatment, treated exclusively with aligners (Invisalign®, Align Technologies, Santa Clara, CA, USA). The following teeth were assessed: upper and lower anterior teeth and first molars. Root and crown lengths of a total of 1600 teeth were measured twice in pre- and post-treatment panoramic radiographs. Afterwards, relative changes of the root length during treatment were calculated by a root-crown-ratio taking pre- and post-treatment root and crown lengths into consideration. A reduction of this ratio was considered as a shortening of the initial root length. Additionally, tooth movements of the front teeth were assessed by lateral cephalograms and the 3-dimensonal set up of each patient. Results All patients had a reduction of the pre-treatment root length with a minimum of two teeth. On average 7.36 teeth per patient were affected. 54% of 1600 measured teeth showed no measurable root reduction. A reduction of >0%-10% of the pre-treatment root length was found in 27.75%, a distinct reduction of >10%-20% in 11.94%. 6.31% of all teeth were affected with a considerable reduction of >20%. We found no statistically significant correlation between relative root length changes and the individual tooth, gender, age or sagittal and vertical orthodontic tooth movement; except for extrusion of upper front teeth, which was considered as not clinical relevant due to the small amount of mean 4% ARR. Conclusions The present study is the first analyzing ARR in patients with a fully implemented orthodontic treatment with aligners (i.e. resolving anterior crowding). The variety was high and no clinical relevant influence factor could be detected. A minimum of two teeth with a root length reduction was found in every patient. On average, 7.36 teeth per patient were affected. PMID:23941626
2013-01-01
351
Carbon trading schemes fundamentally rely on accurate subsurface carbon quantification in order for governing bodies to grant carbon credits inclusive of root biomass (What is Carbon Credit. 2013). Root biomass makes up a large chunk of the subsurface carbon and is difficult, labor intensive, and costly to measure. This paper stitches together the latest geophysical root measurement techniques into site-dependent recommendations for technique combinations and modifications that maximize large-scale root biomass measurement accuracy and efficiency. "Accuracy" is maximized when actual root biomass is closest to measured root biomass. "Efficiency" is maximized when time, labor, and cost of measurement is minimized. Several combinations have emerged which satisfy both criteria under different site conditions. Use of ground penetrating radar (GPR) and/or electrical resistivity tomography (ERT) allow for large tracts of land to be surveyed under appropriate conditions. Among other characteristics, GPR does best with detecting coarse roots in dry soil. ERT does best in detecting roots in moist soils, but is especially limited by electrode configuration (Mancuso, S. 2012). Integration of these two technologies into a baseline protocol based on site-specific characteristics, especially soil moisture and plants species heterogeneity, will drastically theoretically increase efficiency and accuracy of root biomass measurements. Modifications of current measurement protocols using these existing techniques will also theoretically lead to drastic improvements in both accuracy and efficiency. These modifications, such as efficient 3D imaging by adding an identical electrode array perpendicular to the first array used in the Pulled Array Continuous Electrical Profiling (PACEP) technique for ERT, should allow for more widespread application of these techniques for understanding root biomass. Where whole-site measurement is not feasible either due to financial, equipment, or physical limitations, measurements from randomly selected plots must be assumed representative of the entire system and scaled up. This scaling introduces error roughly inversely proportional to the number and size of plots measured. References Mancuso, S. (2012). Measuring roots: An updated approach Springer. What is carbon credit. (2013). Retrieved 7/20, 2013, from http://carbontradexchange.com/knowledge/what-is-carbon-credit
Boitet, J. I.
2013-12-01
352
PubMed Central
The concentration of acid-soluble thiols other than reduced glutathione (SH - GSH) increases in the roots of zinc-sensitive and zinc-tolerant Silene vulgaris (Moench) Garcke after exposure to zinc for 1 to 3 d. The concentration of SH - GSH in the roots is higher in the sensitive plants than in the tolerant ones, both at equal external zinc concentrations and at zinc concentrations causing the same level of root-length growth inhibition. High performance liquid chromatography analyses show that the increase in the concentration of SH - GSH is not only due to the production of phytochelatins, but is also due to an increase in the concentration of cysteine and the production of nonidentified thiols. The cysteine concentration increases equally in the roots of sensitive and tolerant plants. The accumulation of phytochelatins is higher in the roots of the sensitive plants, whereas the chain length distribution of phytochelatins is the same in sensitive and tolerant plants. It is concluded that increased zinc tolerance in S. vulgaris is not due to increased production of phytochelatins. PMID:12232023
Harmens, H.; Den Hartog, P. R.; Bookum, WMT.; Verkleij, JAC.
1993-01-01
353
Seedling tissues of Gmelina arborea, a medicinally important tree species, were infected with wild type Agrobacterium rhizogenes strain ATTCC 15834, which led to the induction of hairy roots from 32% of the explants. Transgenic status of the roots was confirmed by PCR using rolB specific primers, and subsequently, by Southern analysis of the PCR products. Six transformed clones of hairy
Shrutika Dhakulkar; T. R. Ganapathi; Sujata Bhargava; V. A. Bapat
2005-01-01
354
E-print Network
biology, namely, the chemistry of plant defense against belowground herbivores. Focusing on secondaryUpdate on Root Chemical Defenses In Defense of Roots: A Research Agenda for Studying Plant (Bezemer and van Dam, 2005). When attacked by herbivores, plants defend themselves through a continuum
Agrawal, Anurag
355
E-print Network
biological activity and associated processes are concentrated in the soil located around living plant roots of soil life forms, plants play a dominant role in the regulation of many soil processes. In this paper consider how the response of root systems to their environment affects resource acquisition by plants
356
PubMed Central
Objective To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. Material and Methods eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts- FRC and cast post and core- CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom #2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45°, 37°C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45° device with 1 mm/ min cross-head speed until failure occurred. Results The 3-way ANOVA showed that the root canal preparation strategy (p<0.03) and post type (p<0.0001) affected the fracture strength results, while mechanical cycling (p=0.29) did not. Conclusion The root canal preparation strategy only influenced the root fracture strength when restoring with a fiber post and mechanical cycling, so it does not seem to be an important factor in this scenario. PMID:25025556
RIPPE, Marilia Pivetta; SANTINI, Manuela Favarin; BIER, Carlos Alexandre Souza; BALDISSARA, Paolo; VALANDRO, Luiz Felipe
2014-01-01
357
EPA Science Inventory
Background/Question/Methods To inform an individual-based forest stand model emphasizing belowground competition, we explored the potential of using the relative abundances of ribosomal PCR products from pooled and milled roots, to allocate total root biomass to each of the thre...
358
Asymmetric cell divisions play an important role in the establishment and propagation of the cellular pattern of plant tissues. The SHORT-ROOT (SHR) gene is required for the asymmetric cell division responsible for formation of ground tissue (endodermis and cortex) as well as specification of endodermis in the Arabidopsis root. We show that SHR encodes a putative transcription factor with homology
Yrjo Helariutta; Hidehiro Fukaki; Joanna Wysocka-Diller; Keiji Nakajima; Jee Jung; Giovanni Sena; Marie-Theres Hauser; Philip N. Benfey
2000-01-01
359
PubMed
Miya, R K; Firestone, M K
2001-01-01
360
PubMed Central
Plant root is an organ composed of multiple cell types with different functions. This multicellular complexity limits our understanding of root biology because -omics studies performed at the level of the entire root reflect the average responses of all cells composing the organ. To overcome this difficulty and allow a more comprehensive understanding of root cell biology, an approach is needed that would focus on one single cell type in the plant root. Because of its biological functions (i.e., uptake of water and various nutrients; primary site of infection by nitrogen-fixing bacteria in legumes), the root hair cell is an attractive single cell model to study root cell response to various stresses and treatments. To fully study their biology, we have recently optimized procedures in obtaining root hair cell samples. We culture the plants using an ultrasound aeroponic system maximizing root hair cell density on the entire root systems and allowing the homogeneous treatment of the root system. We then isolate the root hair cells in liquid nitrogen. Isolated root hair yields could be up to 800 to 1000~mg of plant cells from 60 root systems. Using soybean as a model, the purity of the root hair was assessed by comparing the expression level of genes previously identified as soybean root hair specific between preparations of isolated root hair cells and stripped roots, roots devoid in root hairs. Enlarging our tests to include other plant species, our results support the isolation of large quantities of highly purified root hair cells which is compatible with a systems biology approach. PMID:24324480
Qiao, Zhenzhen; Libault, Marc
2013-01-01
361
Predictions of global energy use in this century suggest a continued increase in carbon emissions and rising concentrations of carbon dioxide (CO2) in the atmosphere. This represents a serious environmental problem and contributes significantly to greenhouse gases that affect global warming. Terrestrial ecosystems are a huge natural biological scrubber for CO2 currently sequestering, directly from the atmosphere, about 25% (approximately 2 GtC) of the 7.4 Gt of anthropogenic carbon emitted annually into the atmosphere. The major carbon pathways into soil are through plant litter and roots. Presently, there are no means by which root morphology, distribution, and mass can be measured without serious sampling artifacts that alter these properties. The current methods are destructive and labor intensive. Preliminary results using a high frequency, 1.5 Ghz, impulse Ground Penetrating Radar (GPR) for nondestructive imaging of tree root systems in situ are presented. The 3D reconstructed image is used to assess root morphology and dimensions. The constraints, limitations, and potential solutions for using GPR for tree root systems imaging and analysis are discussed.
Wielopolski, Lucian; Hendrey, George; Daniels, Jeffrey J.; McGuigan, Michael
2000-04-01
362
PubMed
Chlordecone, an organochlorine insecticide, continues to pollute soils in the French West Indies. The main source of human exposure to this pollutant is food. Root vegetables, which are staple foods in tropical regions, can be highly contaminated and are thus a very effective lever for action to reduce consumer exposure. We analyzed chlordecone contamination in three root vegetables, yam, dasheen and sweet potato, which are among the main sources of chlordecone exposure in food in the French West Indies. All soil types do not have the same potential for the contamination of root vegetables, allophanic andosols being two to ten times less contaminating than non-allophanic nitisols and ferralsols. This difference was only partially explained by the higher OC content in allophanic soils. Dasheen corms were shown to accumulate more chlordecone than yam and sweet potato tubers. The physiological nature of the root vegetable may explain this difference. Our results are in good agreement with the hypothesis that chlordecone uptake by root vegetables is based on passive and diffusive processes and limited by transport and dilution during growth. PMID:25043888
Florence, Clostre; Philippe, Letourmy; Magalie, Lesueur-Jannoyer
2015-01-01
363
We have observed that low soil phosphorus availability alters the gravitropic response of basal roots in common bean (Phaseolus vulgaris L.), resulting in a shallower root system. In this study we use a geometric model to test the hypotheses that a shallower\\u000a root system is a positive adaptive response to low soil P availability by (1) concentrating root foraging in
Zhenyang Ge; Gerardo Rubio; Jonathan P Lynch
2000-01-01
364
PubMed Central
Root traits influence the amount of water and nutrient absorption, and are important for maintaining crop yield under drought conditions. The objectives of this research were to characterize variability of root traits among spring wheat genotypes and determine whether root traits are related to shoot traits (plant height, tiller number per plant, shoot dry weight, and coleoptile length), regions of origin, and market classes. Plants were grown in 150-cm columns for 61 days in a greenhouse under optimal growth conditions. Rooting depth, root dry weight, root: shoot ratio, and shoot traits were determined for 297 genotypes of the germplasm, Cultivated Wheat Collection (CWC). The remaining root traits such as total root length and surface area were measured for a subset of 30 genotypes selected based on rooting depth. Significant genetic variability was observed for root traits among spring wheat genotypes in CWC germplasm or its subset. Genotypes Sonora and Currawa were ranked high, and genotype Vandal was ranked low for most root traits. A positive relationship (R2?0.35) was found between root and shoot dry weights within the CWC germplasm and between total root surface area and tiller number; total root surface area and shoot dry weight; and total root length and coleoptile length within the subset. No correlations were found between plant height and most root traits within the CWC germplasm or its subset. Region of origin had significant impact on rooting depth in the CWC germplasm. Wheat genotypes collected from Australia, Mediterranean, and west Asia had greater rooting depth than those from south Asia, Latin America, Mexico, and Canada. Soft wheat had greater rooting depth than hard wheat in the CWC germplasm. The genetic variability identified in this research for root traits can be exploited to improve drought tolerance and/or resource capture in wheat. PMID:24945438
Narayanan, Sruthi; Mohan, Amita; Gill, Kulvinder S.; Prasad, P. V. Vara
2014-01-01
365
PubMed
The hydraulic conductivities of excised whole root systems of wheat (Triticum aestivum L. cv. Atou) and of single excised roots of wheat and maize (Zea mays L. cv. Passat) were measured using an osmotically induced back-flow technique. Ninety minutes after excision the values for single excised roots ranged from 1.6·10(-8) to 5.5·10(-8) m·s(-1)·MPa(-1) in wheat and from 0.9·10(-8) to 4.8·10(-8) m·s(-1)·MPa(-1) in maize. The main source of variation was a decrease in the value as root length increased. The hydraulic conductivities of whole root systems, but not of single excised roots, were smaller 15 h after excision. This was not caused by occlusion of the xylem at the cut end of the coleoptile. The hydraulic conductivities of epidermal, cortical and endodermal cells were measured using a pressure probe. Epidermal and cortical cells of both wheat and maize roots gave mean values of 1.2·10(-7) m·s(-1)·MPa(-1) but in endodermal cells (measured only in wheat) the mean value was 0.5·10(-7) m·s(-1)·MPa(-1). The cellular hydraulic conductivities were used to calculate the root hydraulic conductivities expected if water flow across the root was via transcellular (vacuole-to-vacuole), apoplasmic or symplasmic pathways. The results indicate that, in freshly excised roots, the bulk of water flow is unlikely to be via the transcellular pathway. This is in contrast to our previous conclusion (H. Jones, A.D. Tomos, R.A. Leigh and R.G. Wyn Jones 1983, Planta 158, 230-236) which was based on results obtained with whole root systems of wheat measured 14-15 h after excision and which probably gave artefactually low values for root hydraulic conductivity. It is now concluded that, near the root tip, water flow could be through a symplasmic pathway in which the only substantial resistances to water flow are provided by the outer epidermal and the inner endodermal plasma membranes. Further from the tip, the measured hydraulic conductivities of the roots are consistent with flow either through the symplasmic or apoplasmic pathways. PMID:24221410
Jones, H; Leigh, R A; Wyn Jones, R G; Tomos, A D
1988-04-01
366
Throughout the evolution process, Earth's magnetic field (MF, about 50 ?T) was a natural component of the environment for living organisms. Biological objects, flying on planned long-term interplanetary missions, would experience much weaker magnetic fields, since galactic MF is known to be 0.1-1 nT. However, the role of weak magnetic fields and their influence on functioning of biological organisms are still insufficiently understood, and is actively studied. Numerous experiments with seedlings of different plant species placed in weak magnetic field have shown that the growth of their primary roots is inhibited during early germination stages in comparison with control. The proliferative activity and cell reproduction in meristem of plant roots are reduced in weak magnetic field. Cell reproductive cycle slows down due to the expansion of G 1 phase in many plant species (and of G 2 phase in flax and lentil roots), while other phases of cell cycle remain relatively stabile. In plant cells exposed to weak magnetic field, the functional activity of genome at early pre-replicate period is shown to decrease. Weak magnetic field causes intensification of protein synthesis and disintegration in plant roots. At ultrastructural level, changes in distribution of condensed chromatin and nucleolus compactization in nuclei, noticeable accumulation of lipid bodies, development of a lytic compartment (vacuoles, cytosegresomes and paramural bodies), and reduction of phytoferritin in plastids in meristem cells were observed in pea roots exposed to weak magnetic field. Mitochondria were found to be very sensitive to weak magnetic field: their size and relative volume in cells increase, matrix becomes electron-transparent, and cristae reduce. Cytochemical studies indicate that cells of plant roots exposed to weak magnetic field show Ca 2+ over-saturation in all organelles and in cytoplasm unlike the control ones. The data presented suggest that prolonged exposures of plants to weak magnetic field may cause different biological effects at the cellular, tissue and organ levels. They may be functionally related to systems that regulate plant metabolism including the intracellular Ca 2+ homeostasis. However, our understanding of very complex fundamental mechanisms and sites of interactions between weak magnetic fields and biological systems is still incomplete and still deserve strong research efforts.
Belyavskaya, N. A.
2004-01-01
367
PubMed
The tip of the root is covered by a thimble-shaped root cap that is the site of perception and transduction for many environmental stimuli. Until now, little was known about how the root cap of rice (Oryza sativa) develops and functions to regulate the adaptive behavior of the root. To address this, we examined the formation of the rice root cap during embryogenesis and characterized the anatomy and structure of the rice radicle root cap. We further investigated the role of the quiescent center in the de novo origin of the root cap. At the molecular level, we found that shoot-derived auxin was absolutely needed to trigger root cap regeneration when the quiescent center was removed. Our time-course analysis of transcriptomic dynamics during the early phases of root cap regeneration indicated that changes in auxin signaling and appropriate levels of cytokinin are critical for root cap regeneration after the removal of the root cap. Moreover, we identified 152 genes that produce root cap-specific transcripts in the rice root tip. These findings together offer, to our knowledge, new mechanistic insights into the cellular and molecular events inherent in the formation and development of the root cap in rice and provide a basis for future research on the developmental and physiological function of the root cap of monocot crops. PMID:24958716
Wang, Likai; Chu, Huangwei; Li, Zhiyong; Wang, Juan; Li, Jintao; Qiao, Yang; Fu, Yanru; Mou, Tongmin; Chen, Chunli; Xu, Jian
2014-10-01
368
PubMed
Use of resin-based restorative materials recently has become widely accepted for treatment of endodontically treated teeth. However, some solutions routinely used during endodontic treatment procedures may have an effect on bond strengths of adhesive materials to root canal dentin. The purpose of this in vitro study was to evaluate the effect of various medications on microtensile bond strength to root canal dentin. Fourteen extracted human single-rooted teeth were used. The crowns and the pulp tissues were removed. The root canals were then instrumented and widened to the same size. The teeth were randomly divided into seven groups of two teeth each. The root canal dentin walls of the roots were treated with 5% sodium hypochloride (NaOCI), 3% hydrogen peroxide (H2O2), the combination of H2O2 and NaOCl, or 0.2% chlorhexidine gluconate for 60 s; or calcium hydroxide or formocresol for 24 h. The teeth in control group were irrigated with water. The root canals were obturated using C&B Metabond. After 24 h of storage in distilled water, serial 1-mm-thick cross-sections were cut, and approximately 12 samples were obtained from each group. Microtensile bond strengths to root canal dentin were then measured by using an Instron machine. The data were recorded and expressed as MPa. The results indicated that NaOCI, H2O2, or a combination of NaOCl and H2O2 treatment decreased bond strength to root canal dentin significantly (p < 0.05). The teeth treated with chlorhexidine solution showed the highest bond strength values (p < 0.05). In conclusion, chlorhexidine is an appropriate irrigant solution for root canal treatment before adhesive post core applications. PMID:14977310
Erdemir, Ali; Ari, Hale; Güngüne?, Hakan; Belli, Sema
2004-02-01
369
Coarse root distribution of a semi-arid oak savanna estimated with ground penetrating radar North California enjoys wet and mild winters, but experiences extreme hot, dry summer conditions, with occasional drought years. Despite the severity of summer conditions, blue oaks in this ecosystem are winter-deciduous. Water uptake from groundwater helps explain the incongruity of tree growth with soil water availability in this ecosystem. We hypothesized that the binary nature of water availability, in which water is either abundantly available or scarce, would be reflected in blue oak root architecture. The objective of this research was to understand how the form of the root system facilitates ecosystem functioning. To do this, we sought to characterize the structure of the root system, and survey coarse root distribution with ground penetrating radar (GPR), due to its advantages in covering large areas rapidly and non-destructively. Because GPR remains a relatively new technology for examining root distribution, an ancillary objective was to test this methodology, and help facilitate its application more broadly. We used a GPR Noggin1000 SmartTow (Sensors and Software Inc., Ontario, Canada) 1 GHz configuration. In order to best represent the diversity of tree size and age found at the field site, we surveyed six 8x8 m locations with trees varying in size, age and clumping (i.e. isolated trees vs. tree clusters). GPR raw data was processed with designated software in order to construct three-dimensional values of radar reflection intensity for each surveyed grid. Radar signals were transformed to root biomass by calibrating them against excavated roots in twelve 60x100 cm pits. Our results indicate that coarse roots occupy the full soil profile, and that root biomass of old large trees peaks just above the bedrock. As opposed to other semi-arid regions, where trees often develop extensive shallow coarse lateral roots, in order to exploit the entire wet-soil medium, we found that coarse root density decreased with distance from the bole, and dropped sharply at a distance of 2 m. We upscaled root biomass to stand-scale (2.8±0.4 kg m-2) based on LiDAR analysis of the relative abundance of each tree configuration. We argue that the deep and narrow root structure we observed reflects the ecohydrology of oaks in this ecosystem, because extensive lateral roots would not be beneficial during the growing season (water is sufficiently abundant), nor during the summer season (soil water is highly limited). Our research has shown that the combination of resource availability, which is primarily water in this ecosystem, and plant demand, are portrayed in the form of the root system. Such information is important for future assessment of ecosystem sensitivity to climate change, especially changes in groundwater recharge originating from the Sierra-Nevada snow cover.
Raz-Yaseef, N.; Koteen, L. E.; Baldocchi, D. D.
2013-05-01
370
NASA Technical Reports Server (NTRS)
The parameters and relations associated with optimal systems are examined, taking into account a quadratic performance index and a root square locus plot, including the characteristic roots of the optimal system and its adjoint system as a function of the cost function weights. The calculation of the locus is described and the employment of the considered relations in studies of a drag-free satellite is discussed. Attention is given to weights regarding the initial states, questions of rotating integral control, approaches for experimental verification, and the performance of various methods for the reduction of fuel consumption due to center of spin offsets.
Tashker, M. G.; Debra, D. B.
1976-01-01
371
PubMed Central
Background and Aims This study analysed the differences in nitrogen (N), non-structural carbohydrates (NSC) and biomass allocation to the roots and shoots of 18 species of Mediterranean dwarf shrubs with different shoot-rooting and resprouting abilities. Root N and NSC concentrations of strict root-sprouters and species resprouting from the base of the stems were also compared. Methods Soluble sugars (SS), starch and N concentrations were assessed in roots and shoots. The root : shoot ratio of each species was obtained by thorough root excavations. Cross-species analyses were complemented by phylogenetically independent contrasts (PICs). Key Results Shoot-rooting species showed a preferential allocation of starch to shoots rather than roots as compared with non-shoot-rooting species. Resprouters displayed greater starch concentrations than non-sprouters in both shoots and roots. Trends were maintained after PICs analyses, but differences became weak when root-sprouters versus non-root-sprouters were compared. Within resprouters, strict root-sprouters showed greater root concentrations and a preferential allocation of starch to the roots than stem-sprouters. No differences were found in the root : shoot ratio of species with different rooting and resprouting abilities. Conclusions The shoot-rooting ability of Mediterranean dwarf shrubs seems to depend on the preferential allocation of starch and SS to shoots, though alternative C-sources such as current photosynthates may also be involved. In contrast to plants from other mediterranean areas of the world, the resprouting ability of Mediterranean dwarf shrubs is not related to a preferential allocation of N, NSC and biomass to roots. PMID:17728338
Palacio, Sara; Maestro, Melchor; Montserrat-Marti, Gabriel
2007-01-01
372
Fine root survivorship is an important aspect of root ecology and is known to be influenced by a suite of covariates. However,\\u000a the relative importance of each covariate on root survivorship is not clear. Here, we used minirhizotron-based data from 18\\u000a woody species to evaluate the relative strength of influence on root survivorship by root diameter, branch order, soil depth,
Jiacun GuShuiqiang; Shuiqiang Yu; Yue Sun; Zhengquan Wang; Dali Guo
373
E-print Network
and sweet potatoes, but also trees such as elms and chinaberries, and ornamental shrubs and flowers such as the privet, rose, and chrysan- themum. In the areas where it is serious, root-rot thus concerns the farmer, the truck grower, the nurseryman..., during dry weather. Eithcr of these estrcme soil-moisture conclitions ericlently is unfarorable to the fungus. With resistaiit plants s~zcli as the Turk's-cap Hibiscus and the pomegranate, the yo~~i~g plant!: become infectecl ~rith root-rot hut nre...
Taubenhaus, J. J. (Jacob Joseph); Ezekiel, (Walter Naphtali) Walter N.
1931-01-01
374
Summary and Conclusions The root apical organisation of nine species of dicotyledons belonging to some primitive and some advanced families has been\\u000a investigated.\\u000a \\u000a The structural configurations of these species fall under three types: (i) with four superimposed tiers, a common tier for\\u000a the dermatogen and the peripheral region of the root-cap—the dermocalyptrogen—hypodermis, periblem and plerome, (ii) with\\u000a three tiers of initials,
S. K. Pillai; P. Vijayalekshmi; Omana M. George
1965-01-01
375
E-print Network
by Hartin to assess exudation from both sterile and non-sterile roots grown in soil (25, 27, 28). Data from wheat, clover, and ryegrass indicated that leachates plus root free soil contained from 2. 8-5. 7% of the total C02 (27). Later experiments on 14... wheat gave much higher values (5). From 7-18/ of the assimilated 14C was exuded in sterile and non-sterile soils respectively. Barley yielded still higher percentages of 13-25/. Differences in quantity of exudation between sterile and non-sterile...
Kennedy, Lynne Susan
2012-06-07
376
E-print Network
were y 1. '1 t G~t~l( ht hyhd h ypi 1 thick outer wall and thin inner membrane (Fig. 14, p. 31) . Blackberry (Rubus sp. ) Root and Soil Material The blackberry sample was collected at Stephenville, Texas. Four different spore types were found... were y 1. '1 t G~t~l( ht hyhd h ypi 1 thick outer wall and thin inner membrane (Fig. 14, p. 31) . Blackberry (Rubus sp. ) Root and Soil Material The blackberry sample was collected at Stephenville, Texas. Four different spore types were found...
Yeh, May-Wei Mavix
2012-06-07
377
Riprap is a traditional engineering solution used to protect riverbanks against erosion on developed riparian corridors. However, the traditional riprap does not provide adequate fish and wildlife habitat within the riparian zone, which is normally provided by naturally vegetated stream banks. An innovative approach, which mitigates this issue and at the same time provides stream bank erosion control, is the vegetated riprap technique. This solution, which combines rocks and native vegetation in the form of live cuttings, has been designed and implemented by Terra Erosion Control Ltd for the past 7 years. The aim of this work was to study the effect of the vegetation, in particular the root system, on the stability of the riprap. This analysis was carried out in the late spring of 2013 on the vegetated riprap installation located along the Columbia River riverbank, adjacent to the Teck Metals Ltd. smelter in Trail, British Columbia, Canada. An excavation perpendicular to the river was performed in order to investigate the root system development within the vegetated riprap structure. This excavation exposed one of the Salix bebbiana cuttings installed in 2006. The cutting was 2.3 m long and was set with an inclination of 35° with respect to the horizontal plane: the first 0.3 m was exposed, 1 m was buried within the riprap rocks (which had an average diameter of 30 cm) and the remaining 1.0 m was in the soil matrix below the rocks. The diameter of the roots growing along the cutting were measured in order to obtain the root density at various depths and tensile strength tests were carried out on the Salix bebbiana roots with diameters of up to 9 mm. The aim was to quantitatively estimate the additional cohesion given by the roots. The additional root cohesion was more effective in the deeper soil layer where the soil matrix predominates. In the upper soil layer, where the particle size is significantly higher, roots do not increase the cohesion but act as a network which ties the rocks of the riprap structure together. The uprooting resistance was also tested with a pullout test, which demonstrated that the force necessary to uproot a Salix bebianna cutting, grown in the riprap along the riverbank, was higher if compared with the same species grown in a natural environment.
Tron, Stefania; Raymond, Pierre
2014-05-01
378
PubMed
Parthenolide (PTL), a sesquiterpene lactone (SL) originally purified from the shoots of feverfew (Tanacetum parthenium), has shown potent anticancer and anti-inflammatory activities. It is currently being tested in cancer clinical trials. Structure-activity relationship (SAR) studies of parthenolide revealed key chemical properties required for biological activities and epigenetic mechanisms, and led to the derivatization of an orally bioavailable analog, dimethylamino-parthenolide (DMAPT). Parthenolide is the first small molecule found to be selective against cancer stem cells (CSC), which it achieves by targeting specific signaling pathways and killing cancer from its roots. In this review, we highlight the exciting journey of parthenolide, from plant shoots to cancer roots. PMID:23688583
Ghantous, Akram; Sinjab, Ansam; Herceg, Zdenko; Darwiche, Nadine
2013-09-01
379
PubMed Central
Dental avulsion is the most severe type of traumatic tooth injuries since it causes damage to several structures and results in avulsion of the tooth from its socket. Management protocols for avulsed teeth should include management of the pulp and periodontal ligament (PDL) cells in order to improve the long-term prognosis and survival of these teeth. The prognosis of the treatment as well as the survival of an avulsed tooth depends on intrinsic and extrinsic factors, such as the duration of the tooth’s extra-alveolar period, replantation time, the type of storage medium, PDL status and duration of splinting. Recent research has led to the development of storage media. However, there is not yet a single solution that fulfills all requirements to be considered as the ideal medium for temporary storage of avulsed teeth, and research on this field should carry on. On the other hand in case of delayed replantation, due to the great risk of tooth loss after avulsion, different root surface treatments have been proposed to prevent and delay root resorption before replantation. For this purpose, researchers have applied some different root surface treatment modalities in delayed replantation of avulsed teeth. Several protocols have been used to maintain PDL viability; some involve fluorides, steroids, sodium alendronate, enamel matrix derivatives (EMD) and basic fibroblast growth factor (bFGF, FGF-2). Among these applications, bFGF shows promising results in the regeneration of natural tooth structures and tissues. Better understanding of mechanism of bFGF may help to improve new technologies of regeneration of tooth structures. PMID:25317212
Tuna, Elif B; Yaman, Duygu; Yamamato, Seiko
2014-01-01
380
PubMed
We aim to incorporate deep root traits into future wheat varieties to increase access to stored soil water during grain development, which is twice as valuable for yield as water captured at younger stages. Most root phenotyping efforts have been indirect studies in the laboratory, at young plant stages, or using indirect shoot measures. Here, soil coring to 2 m depth was used across three field environments to directly phenotype deep root traits on grain development (depth, descent rate, density, length, and distribution). Shoot phenotypes at coring included canopy temperature depression, chlorophyll reflectance, and green leaf scoring, with developmental stage, biomass, and yield. Current varieties, and genotypes with breeding histories and plant architectures expected to promote deep roots, were used to maximize identification of variation due to genetics. Variation was observed for deep root traits (e.g. 111.4-178.5cm (60%) for depth; 0.09-0.22cm/°C day (144%) for descent rate) using soil coring in the field environments. There was significant variation for root traits between sites, and variation in the relative performance of genotypes between sites. However, genotypes were identified that performed consistently well or poorly at both sites. Furthermore, high-performing genotypes were statistically superior in root traits than low-performing genotypes or commercial varieties. There was a weak but significant negative correlation between green leaf score (-0.5), CTD (0.45), and rooting depth and a positive correlation for chlorophyll reflectance (0.32). Shoot phenotypes did not predict other root traits. This study suggests that field coring can directly identify variation in deep root traits to speed up selection of genotypes for breeding programmes. PMID:24963000
Wasson, A P; Rebetzke, G J; Kirkegaard, J A; Christopher, J; Richards, R A; Watt, M
2014-11-01
381
PubMed Central
We aim to incorporate deep root traits into future wheat varieties to increase access to stored soil water during grain development, which is twice as valuable for yield as water captured at younger stages. Most root phenotyping efforts have been indirect studies in the laboratory, at young plant stages, or using indirect shoot measures. Here, soil coring to 2 m depth was used across three field environments to directly phenotype deep root traits on grain development (depth, descent rate, density, length, and distribution). Shoot phenotypes at coring included canopy temperature depression, chlorophyll reflectance, and green leaf scoring, with developmental stage, biomass, and yield. Current varieties, and genotypes with breeding histories and plant architectures expected to promote deep roots, were used to maximize identification of variation due to genetics. Variation was observed for deep root traits (e.g. 111.4–178.5cm (60%) for depth; 0.09–0.22cm/°C day (144%) for descent rate) using soil coring in the field environments. There was significant variation for root traits between sites, and variation in the relative performance of genotypes between sites. However, genotypes were identified that performed consistently well or poorly at both sites. Furthermore, high-performing genotypes were statistically superior in root traits than low-performing genotypes or commercial varieties. There was a weak but significant negative correlation between green leaf score (–0.5), CTD (0.45), and rooting depth and a positive correlation for chlorophyll reflectance (0.32). Shoot phenotypes did not predict other root traits. This study suggests that field coring can directly identify variation in deep root traits to speed up selection of genotypes for breeding programmes. PMID:24963000
Wasson, A. P.; Rebetzke, G. J.; Kirkegaard, J. A.; Christopher, J.; Richards, R. A.; Watt, M.
2014-01-01
382
PubMed
The isolation of Actinomyces naeslundii from sound, exposed root surfaces (n = 56) and soft and leathery root carious lesions (n = 71) was investigated. Root carious lesions were sampled after the removal of overlying plaque. Supragingival plaque or carious dentine was sampled using a sterile excavator, the samples were disaggregated and cultured on both selective and non-selective media. A. naeslundii isolates were identified to the genospecies using specific antisera. Significantly greater numbers and proportions of A. naeslundii genospecies 2 than A. naeslundii genospecies 1 were isolated from all sites sampled. There was no significant difference between the numbers and proportions of the two genospecies isolated from leathery and soft lesions. The relationship between the presence of A. naeslundii genospecies and aciduric and acidogenic organisms was investigated. Those sound exposed root surfaces from which A. naeslundii genospecies 1 and/or 2 were isolated yielded significantly lower numbers of lactobacilli and yeasts than the surfaces from which A. naeslundii were not isolated. This difference was also found in leathery lesions but not soft root carious lesions. The microflora of soft root carious lesions was found to comprise primarily gram-positive pleomorphic rods which formed 70+/-7.8% of the flora, while in plaque from exposed root surfaces and in infected dentine from leathery lesions the gram-positive pleomorphic rods represented only 35% of the flora. PMID:9544857
Brailsford, S R; Lynch, E; Beighton, D
1998-01-01
383
PubMed
The luminescence of silver bromide crystals, doped with neodymium, was investigated over the visible and near-infrared spectral ranges. The emission, excitation, and absorption spectra were measured over a broad temperature range. The absolute luminescence quantum yield was estimated by comparing the luminescence with that of a neodymium-doped phosphate glass, for which the manufacturer gives a value of 0.4. The Judd-Ofelt analysis was applied to both materials, and transition rates, branching ratios, and quantum efficiencies were calculated for all the observed bands. Good agreement was obtained between theory and experiment. PMID:18264290
Bunimovich, D; Nagli, L; Katzir, A
1997-10-20
384
Recent publications and reviews concern the major importance of the deep subsoil for carbon (C) storage and cycling in terrestrial environments. However, the subsoil (below A horizon) and especially the deep subsoil (> 1m) is a target not easy to study and especially the relevant processes therein. Therefore, in the current study we focussed on recent and ancient root systems extending in terrestrial sediments until 9 m depth below the present surface and more than 7 m below the present soil. We sampled rhizosphere in the direct vicinity of the roots and with increasing distance (up to 10 cm) from visible root remains, and determined the root frequency in different depths. Additionally, sedimentary material without visible root remains was sampled for each of these depth intervals, and all samples were analysed for C contents and lipid composition. Main aim of the study was to obtain information of root effects on C content and composition in the deep subsoil. The loess-paleosol sequence of Nussloch (SW Germany) with a Cambisol on its top was chosen as a key site as recent and ancient roots were easy to assess and to differentiate. Furthermore, two sites near Sopron (NW Hungary) were sampled for recent tree roots rooting deeply (at least 4 m) into loess sediment. All samples were investigated for Corg, Ccarb and extractable lipid contents and the lipid composition. The frequency of recent roots strongly decreased with depth in the Nussloch profile until zero at 2 m depth below the present soil surface as recent tree vegetation was rather young (<7 years). In comparison to this, ancient tree root remains, frequently visible as carbonate precipitates surrounding the former roots, could be observed continuously until 9 m depth with the largest frequency (~200 roots m-2) at 2-3 m depth. However, only root remains of a diameter larger than 1 mm were counted, thus highly underestimating fine root remains, which were not counted throughout the profile due to their high frequency (>>10,000 m-2). In the rhizosphere of former and recent roots, Corg tended to slightly decrease compared to reference sediment. Ccarb contents revealed in some depths slight changes in the rhizosphere. Especially the precipitates surrounding the former roots were strongly enriched in Ccarb although the investigated sediments were rich in carbonate (20-40 mass-%). Taking into account the rhizolith frequency (only of the carbonate precipitates >1 mm), the bulk density, the carbon concentrations and the estimated extension of the rhizosphere, a decrease of more than 1 kg C m-2 was determined in the rhizosphere by comparison to root-free loess. The C loss was mainly related to the more depth intervals with densely occurring large root remains (>20 m-2) at a depth of less than 5 m, whereas in larger depth intervals with a lower frequency of root remains C contents slightly increased in the rhizosphere. Despite the high C storage in deep subsoil, root related processes might alter the chemical composition in the subsoil and can result in C loss in the long term.
Wiesenberg, Guido; Gocke, Martina
2013-04-01
385
PubMed
The study of proportional relationships between size, shape, and function of part of or the whole organism is traditionally known as allometry. Examination of correlative changes in the size of interbranch distances (IBDs) at different root orders may help to identify root branching rules. Root morphological and functional characteristics in three range grasses {bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Löve], crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.×A. cristatum (L.) Gaert.], and cheatgrass (Bromus tectorum L.)} were examined in response to a soil nutrient gradient. Interbranch distances along the main root axis and the first-order laterals as well as other morphological and allocation root traits were determined. A model of nutrient diffusivity parameterized with root length and root diameter for the three grasses was used to estimate root functional properties (exploitation efficiency and exploitation potential). The results showed a significant negative allometric relationship between the main root axis and first-order lateral IBD (P ? 0.05), but only for bluebunch wheatgrass. The main root axis IBD was positively related to the number and length of roots, estimated exploitation efficiency of second-order roots, and specific root length, and was negatively related to estimated exploitation potential of first-order roots. Conversely, crested wheatgrass and cheatgrass, which rely mainly on root proliferation responses, exhibited fewer allometric relationships. Thus, the results suggested that species such as bluebunch wheatgrass, which display slow root growth and architectural root plasticity rather than opportunistic root proliferation and rapid growth, exhibit correlative allometry between the main axis IBD and morphological, allocation, and functional traits of roots. PMID:21868398
Arredondo, J Tulio; Johnson, Douglas A
2011-11-01
386
PubMed Central
The study of proportional relationships between size, shape, and function of part of or the whole organism is traditionally known as allometry. Examination of correlative changes in the size of interbranch distances (IBDs) at different root orders may help to identify root branching rules. Root morphological and functional characteristics in three range grasses {bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Löve], crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.×A. cristatum (L.) Gaert.], and cheatgrass (Bromus tectorum L.)} were examined in response to a soil nutrient gradient. Interbranch distances along the main root axis and the first-order laterals as well as other morphological and allocation root traits were determined. A model of nutrient diffusivity parameterized with root length and root diameter for the three grasses was used to estimate root functional properties (exploitation efficiency and exploitation potential). The results showed a significant negative allometric relationship between the main root axis and first-order lateral IBD (P ?0.05), but only for bluebunch wheatgrass. The main root axis IBD was positively related to the number and length of roots, estimated exploitation efficiency of second-order roots, and specific root length, and was negatively related to estimated exploitation potential of first-order roots. Conversely, crested wheatgrass and cheatgrass, which rely mainly on root proliferation responses, exhibited fewer allometric relationships. Thus, the results suggested that species such as bluebunch wheatgrass, which display slow root growth and architectural root plasticity rather than opportunistic root proliferation and rapid growth, exhibit correlative allometry between the main axis IBD and morphological, allocation, and functional traits of roots. PMID:21868398
Arredondo, J. Tulio; Johnson, Douglas A.
2011-01-01
387
PubMed Central
In Ayurveda, the roots of Eranda (Ricinus communis Linn.) are used in the treatment Amavata (rheumatism), Sotha (inflammation), Katisula (backache), Udararoga (disease of abdomen), Jwara (fever), etc, Due to high demand, root of the cultivated variety is mainly used in place of wild. But, a comparative phytochemical profile of both varieties is not available till date. Considering this, a preliminary study has been done to ensure basic phytochemical profile of both the varieties. Preliminary physicochemical parameters, phytochemical screening, quantitative estimation of alkaloid, high-performance thin layer chromatography (HPTLC), and heavy metal analysis were carried-out in the study. Analysis of physicochemical data reveals no significant difference in between both varieties of roots, while alkaloid was found to be more in cultivated variety (0.34%) than wild one (0.15%). Though, the analytical profiles are almost identical, except the quantity of alkaloid; inferences should be made through well designed pharmacological and clinical studies. PMID:24250131
Doshi, Krunal A.; Acharya, Rabinarayan; Shukla, V. J.; Kalyani, Renuka; Khanpara, Komal
2013-01-01
388
PubMed
In Ayurveda, the roots of Eranda (Ricinus communis Linn.) are used in the treatment Amavata (rheumatism), Sotha (inflammation), Katisula (backache), Udararoga (disease of abdomen), Jwara (fever), etc, Due to high demand, root of the cultivated variety is mainly used in place of wild. But, a comparative phytochemical profile of both varieties is not available till date. Considering this, a preliminary study has been done to ensure basic phytochemical profile of both the varieties. Preliminary physicochemical parameters, phytochemical screening, quantitative estimation of alkaloid, high-performance thin layer chromatography (HPTLC), and heavy metal analysis were carried-out in the study. Analysis of physicochemical data reveals no significant difference in between both varieties of roots, while alkaloid was found to be more in cultivated variety (0.34%) than wild one (0.15%). Though, the analytical profiles are almost identical, except the quantity of alkaloid; inferences should be made through well designed pharmacological and clinical studies. PMID:24250131
Doshi, Krunal A; Acharya, Rabinarayan; Shukla, V J; Kalyani, Renuka; Khanpara, Komal
2013-04-01
389
PubMed Central
Background and Aims Vegetation has long been recognized to protect the soil from erosion. Understanding species differences in root morphology and functional traits is an important step to assess which species and species mixtures may provide erosion control. Furthermore, extending classification of plant functional types towards root traits may be a useful procedure in understanding important root functions. Methods In this study, pioneer data on traits of alpine plant species, i.e. plant height and shoot biomass, root depth, horizontal root spreading, root length, diameter, tensile strength, plant age and root biomass, from a disturbed site in the Swiss Alps are presented. The applicability of three classifications of plant functional types (PFTs), i.e. life form, growth form and root type, was examined for above- and below-ground plant traits. Key Results Plant traits differed considerably among species even of the same life form, e.g. in the case of total root length by more than two orders of magnitude. Within the same root diameter, species differed significantly in tensile strength: some species (Geum reptans and Luzula spicata) had roots more than twice as strong as those of other species. Species of different life forms provided different root functions (e.g. root depth and horizontal root spreading) that may be important for soil physical processes. All classifications of PFTs were helpful to categorize plant traits; however, the PFTs according to root type explained total root length far better than the other PFTs. Conclusions The results of the study illustrate the remarkable differences between root traits of alpine plants, some of which cannot be assessed from simple morphological inspection, e.g. tensile strength. PFT classification based on root traits seems useful to categorize plant traits, even though some patterns are better explained at the individual species level. PMID:21795278
Pohl, Mandy; Stroude, Raphael; Buttler, Alexandre; Rixen, Christian
2011-01-01
390
PubMed
The meristematic mitotic cells of plant roots are appropriate and efficient cytogenetic materials for the detection of clastogenicity of environmental pollutants, especially for in situ monitoring of water contaminants. Among several cytological endpoints in these fast dividing cells, such as chromosome/chromatid aberrations, sister-chromatid exchanges and micronuclei, the most effective and simplest indicator of cytological damage is micronucleus formation. Although the Allium cepa and Vicia faba root meristem micronucleus assays (Allium/Vicia root MCN) have been used in clastogenicity studies about 12 times by various authors in the last 25 years, there is no report on the comparison of the efficiency of these two plant systems and in different cell populations (meristem and F1) of the root tip as well as under adequate recovery duration. In order to maximize the efficiency of these bioassays, the current study was designed to compare the Allium and the Vicia root MCN assays on the basis of chromosome length, peak sensitivity of the mitotic cells, and the regions of the root tip where the MCN are formed. The total length of the 2n complement of Allium chromosomes is 14.4 microns and the total length of the 2n complement of Vicia is 9.32 microns. The peak sensitivity determined by serial fixation at 12-h intervals after 100 R of X-irradiation is 44 h. The slope of the X-ray dose-response curve of Allium roots derived from the meristematic regions was lower than that derived from cells in the F1 region. Higher efficiency was also demonstrated when the MCN frequencies were scored from the F1 cells in both Allium and Vicia treated with formaldehyde (FA), mitomycin C (MMC), and maleic hydrazide (MH). The results indicated that scoring of MCN frequencies from the F1 cell region of the root tip was more efficient than scoring from the meristematic region. The X-ray linear regression dose-response curves were established in both Allium and Vicia cell systems and the coefficients of correlations, slope values were used to verify the reliability and efficiency of these two plant cell systems. Based on the dose-response slope value of 0.894 for Allium and 0.643 for Vicia, the Allium root MCN was a more efficient test system. The greater sensitivity of the Allium roots is probably due to the greater total length of the diploid complement and the higher number of metacentric chromosomes.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7885371
Ma, T H; Xu, Z; Xu, C; McConnell, H; Rabago, E V; Arreola, G A; Zhang, H
1995-04-01
391
PubMed Central
Background Individual plants adapt to their immediate environment using a combination of biochemical, morphological and life cycle strategies. Because woody plants are long-lived perennials, they cannot rely on annual life cycle strategies alone to survive abiotic stresses. In this study we used suppression subtractive hybridization to identify genes both up- and down-regulated in roots during water deficit treatment and recovery. In addition we followed the expression of select genes in the roots, leaves, bark and xylem of ‘Royal Gala’ apple subjected to a simulated drought and subsequent recovery. Results In agreement with studies from both herbaceous and woody plants, a number of common drought-responsive genes were identified, as well as a few not previously reported. Three genes were selected for more in depth analysis: a high affinity nitrate transporter (MdNRT2.4), a mitochondrial outer membrane translocase (MdTOM7.1), and a gene encoding an NPR1 homolog (MpNPR1-2). Quantitative expression of these genes in apple roots, bark and leaves was consistent with their roles in nutrition and defense. Conclusions Additional genes from apple roots responding to drought were identified using suppression subtraction hybridization compared to a previous EST analysis from the same organ. Genes up- and down-regulated during drought recovery in roots were also identified. Elevated levels of a high affinity nitrate transporter were found in roots suggesting that
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http://tex.stackexchange.com/questions/59197/algorithmicx-how-to-use-latex-maths-delimiters
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Algorithmicx — How to use latex maths delimiters
Today, I decided to migrate from using TeX [$..$] to LaTeX [$$..$$] delimiters for inline maths, and, as usual, fell off the cliff of my somewhat precarious understanding of TeXian gastroenterology, in the middle of an algpseudocode environment.
Here's my MWE:
\documentclass{article}
\usepackage{algpseudocode}
\begin{document}
\begin{algorithmic}[1]
\Procedure{Trigger Dispatching Scheduler}{}
\State \Call{MqOpen}{$\aleph$}
\State \Call{MqOpen}{$$\aleph$$\relax}
%\State \Call{MqOpen}{$$\aleph$$} % <== This one fails
\EndProcedure
\end{algorithmic}
\end{document}
Uncommenting the %-line causes it to fail (PdfLaTeX and XeLaTeX) with:
! Argument of \) has an extra }.
<inserted text>
\par
l.14 \State \Call{MqOpen}{$$\aleph$$}
% <== This one fails
What, if anything, am I doing wrong? If anyone could explain in fairly simple terms what's going on here, I'd be most grateful.
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Does this have anything to do with the word 'fragile' (which precisely describes my understanding of these things) – Brent.Longborough Jun 9 '12 at 15:00
I think so (based on Why is the ifthen package obsolete?) and algorithmicx(http://ctan.org/pkg/algorithmicx) uses [ifthen to condition on many levels. For example, using \State \Call{MqOpen}{\protect$$\aleph\protect$$} works. Not exactly sure why \relax makes it work though. – Werner Jun 9 '12 at 15:03
I give an answer below saying it's a bug in ifthen package, but I think I'm going to reclassify it as a feature.
In unmodified LaTeX2e $$ \nd $$ are fragile commands and as such they should be preceded by \protect if used in a moving argument (as the argument of \equal).
\ifthenelse{\equal{\protect$$a\protect$$}{\protect$$a\protect$$}}{\typeout Y}{\typeout N}
does work as intended.
If you load the fixltx2e package part of the core base distribution then $$ and $$ are made robust so you (and even I) might have expected that \protect is not necessary. However the due to the way \ifthenelse overloads the syntax to be a boolean logic parenthesis rather than math start, $$ is made fragile again. The "fix" below locally gives \($$ robust definitions however due to the "interesting" expansion order implemented in ifthenelse This local redefinition applies to the entire predicate not just the arguments to \equal and so the "fix" is entirely wrong as it removes the ifthenelse definition of entirely.
Sorry (if you want to take away the green tick I'd understand:-) but unless sleeping on it gives me a better idea, or another contributor has a better idea, I think the only thing I can do is more clearly document in ifthen that if you use the ifthen syntax commands (\or\and\isodd etc inside an \equals test, then you need to \protect them.
Sorry it's a bug.
\ifthenelse uses delimiters $$ and $$ to brackets boolean expressions. These are not made safe in the strings used by ifthenelse \equal test. The following inserts a local definition to make things safer,
\let$$\relax\let$$\relax
without this line you get the same error shown in your MWE.
\documentclass{article}
\usepackage{ifthen}
\makeatletter
\long\def\ifthenelse#1{%
\toks@{#1}%
\TE@repl\or\TE@or
\TE@repl\and\TE@and
\TE@repl\not\TE@neg
\TE@repl\OR\TE@or
\TE@repl\AND\TE@and
\TE@repl\NOT\TE@neg
\begingroup
\let\protect\@unexpandable@protect
\def\@setref##1##2##3{%
\ifx##1\relax\z@\else\expandafter##2##1\fi}%
\def\value##1{\the\csname c@##1\endcsname}%
\let\equal\TE@equal \let$$\TE@lparen \let$$\TE@rparen
\let\isodd\TE@odd \let\lengthtest\TE@length
\let\isundefined\TE@undef
\begingroup
\let\@tempa\relax\let\@tempb\relax
\let$$\relax\let$$\relax
\xdef\@gtempa{\expandafter\TE@eval\the\toks@\TE@endeval}%
\endgroup
\@gtempa
\expandafter\endgroup\ifTE@val
\expandafter\@firstoftwo
\else
\expandafter\@secondoftwo
\fi}
\makeatother
\ifthenelse{\equal{a}{a}}{\typeout Y}{\typeout N}
\ifthenelse{\equal{a}{b}}{\typeout Y}{\typeout N}
\ifthenelse{\equal{$$a$$}{$$a$$}}{\typeout Y}{\typeout N}
\ifthenelse{\equal{$$a$$}{$$b$$}}{\typeout Y}{\typeout N}
\stop
This produces
Y
N
Y
N
)
No pages of output.
on the terminal showing the tests worked.
-
Thanks, David. What do you think is the best way of "implementing" this?: (a) make a patched local copy of ifthen.sty, or (b) put your code into a local fixifthen.sty and then \usepackage{fixifthen}? – Brent.Longborough Jun 9 '12 at 21:14 actually I'm not sure that's quite the right fix (I may have broken the ifthen use of \( I need to make a couple of test cases. As it's clearly a bug I would just patch ifthen.sty locally (putting some note in the \ProvidesPackage line to note it is modified) that way the document doesn't need changing once the main distribution gets fixed. – David Carlisle Jun 9 '12 at 22:02
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https://www.physicsforums.com/threads/calculate-force-acting-on-rod-to-holding-it-stable.649737/
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# Calculate force acting on rod to holding it stable.
1. Nov 5, 2012
### sareba
1. The problem statement, all variables and given/known data
A uniform rod AB of weight 20N is hinged at a fixed point A. A force acts at B holding it in equilibrium at 30 degrees to the vertical through A. calculate force acting at B if it is perpendicular to the rod.
3. The attempt at a solution
I figured that the angle between the weight of the rod and the force on B is 60 degrees but i cant seem to find the angle between the weight and the normal reaction force at the hinge...
2. Nov 5, 2012
### tiny-tim
hi sareba!
easy …
there's only three forces on the rod, and so they must all go through the same point (why? ),
so just draw the reaction force (it's not the normal reaction force, btw) so that it goes through the point where the other two forces meet
3. Nov 5, 2012
### sareba
Yes. I did that. If the forces are in equilibrium they should meet at one point. But still I cant calculate the answer with just one force and one angle known... I am sure i am overlooking something... Here is a diagram i came up with... I need to find one of the angles with a question mark on them...
File size:
470.8 KB
Views:
97
4. Nov 5, 2012
### tiny-tim
ah yes, that's exactly the right diagram
ok, call that bottom point C, and the length of the rod 2L …
you want to find angle GCA
you know the length of GA, and the angle CGA, and you can easily find the length of GC
then find the length of AC, and then the angle GCA
5. Nov 5, 2012
### sareba
I am sorry. I didnt quite follow you. How do i know the length of GA? Do you mean GC?
6. Nov 5, 2012
### tiny-tim
GA = L, half the length of the rod
Similar Discussions: Calculate force acting on rod to holding it stable.
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https://brainder.org/2011/07/13/inverse-normal-transformation-in-solar/
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# Inverse normal transformation in SOLAR
SOLAR software can, at the discretion of the user, apply a rank-based inverse-normal transformation to the data using the command inormal. This transformation is the one suggested by Van der Waerden (1952) and is given by:
$\tilde y_i = \Phi^{-1}\left\{\dfrac{r_i}{n+1}\right\}$
where $\tilde y_i$ is the transformed value for observation $i$, $\Phi^{-1}\left\{\cdot\right\}$ is the probit function, $r_i$ is the ordinary rank of the $i$-th case among $n$ observations.
This transformation is a particular case of the family of transformations discussed in the paper by Beasley et al. (2009). The family can be represented as:
$\tilde y_i = \Phi^{-1}\left\{\dfrac{r_i+c}{n-2c+1}\right\}$
where $c$ is a constant and the remaining variables are as above. The value of $c$ varies for different proposed methods. Blom (1958) suggests $c=3/8$, Tukey (1962) suggests $c=1/3$, Bliss (1967) suggests $c=1/2$ and, as just decribed, Van der Waerden suggests $c=0$.
Interesting enough, the Q-Q plots produced by Octave use the Bliss (1967) transformation.
An Octave/matlab function to perform these transformations in arbitrary data is here: inormal.m (note that this function does not require or use SOLAR).
## Version history
• 23.Jul.2011: First public release.
• 19.Jun.2014: Added ability to deal with ties, as well as NaNs in the data.
## 3 thoughts on “Inverse normal transformation in SOLAR”
1. Useful! Here is a function to do the same thing in Python.
from scipy.stats import rankdata, norm
def rank_based_inv_norm(x, c=0):
“””
Perform the rank-based inverse normal transformation on data x.
Reference: Beasley TM, Erickson S, Allison DB. Rank-based inverse normal
transformations are increasingly used, but are they merited? Behav Genet.
2009; 39(5):580-95.
:param x: input array-like
:param c: constant parameter
:return: y
“””
return norm.ppf((rankdata(x) + c) / (x.size – 2*c + 1))
• Hey Sam — good to have this in other languages. You may need to add the extra lines to treat ties, otherwise the results aren’t accurate for all cases. Also note that the default is c=3/8, whereas you’re using c=0 (both are fine, just different).
Cheers,
Anderson
• I chose c=0 because most of the time we will probably want to replicate the SOLAR output (in the IoL lab anyway).
scipy.rankdata has a number of optional methods for handling ties, the default is ‘average’, which I just assumed was the one SOLAR used, but couldn’t find a reference. For continuous traits with high precision the probability of tied ranks is quite low, so I think this function will give us the same output as SOLAR most of the time, but need to check this.
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https://www.fachschaft.informatik.tu-darmstadt.de/forum/viewtopic.php?f=564&t=37638
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## Integration constant acceleration
Forever
Neuling
Beiträge: 7
Registriert: 18. Jun 2017 20:02
### Integration constant acceleration
Hallo,
I have a question about the calculation of position by using Euler method in exercise 8 as shown in the attached picture.
Is it not like "y = 1/2 * (-10) * t^2"? For t = 2, y = –20? Why is it –30?
Dateianhänge
[email protected] (53.91 KiB) 12948 mal betrachtet
Zuletzt geändert von Forever am 16. Feb 2018 17:03, insgesamt 1-mal geändert.
Polona
Windoof-User
Beiträge: 40
Registriert: 10. Okt 2010 10:45
### Re: Integration constant acceleration
Hi,
Look in the script: pos_new = pos_old + v_old * deltaT. The solution actually uses the current velocity.
Perhaps you will find the explanation here https://gafferongames.com/post/integration_basics/ better.
Kind regards
Polona
Forever
Neuling
Beiträge: 7
Registriert: 18. Jun 2017 20:02
### Re: Integration constant acceleration
if I use pos_new = pos_old + v_old * deltaT
pos_old = 0.5 * (-10) * 1^2 = -5 ?
v_old = (-10) * 1= -10 ?
pos_new = -5 + (-10) * 1 = -15 ?
and if I use y = 1/2 * (-10) * t^2" then y = 1/2 * (-10) * 2^2 = 20 ?
RobDangerous
Computerversteher
Beiträge: 363
Registriert: 14. Okt 2014 17:05
### Re: Integration constant acceleration
The formula used in the solution is pos_new = pos_old + v_new * deltaT which is an equally valid approximation (calculate the new speed first vs calculate the new position first). In the exam both variations would get you all the points. But your original question was basically "why is it not the analytical solution" which is actually part of question b. The euler integration is an approximation which does not use t, just delta t. Analytical solutions are typically not usable because many values depend on user input and whatnot and are not formulas you could do proper math on (for example acceleration - typically that is not a constant but some value which changes in unpredictable ways). For that reason we do approximations on small time steps instead of using the proper formulas.
Forever
Neuling
Beiträge: 7
Registriert: 18. Jun 2017 20:02
### Re: Integration constant acceleration
ok, thanks a lot.
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https://www.physicsforums.com/threads/polar-integration.642244/
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# Polar Integration
1. Oct 8, 2012
### ruzfactor
Hi
I have a function [e.g. f(r)] which I want to integrate over r and θ. What would be the integration form? Which one is correct?
∫∫f(r) drdθ OR ∫∫f(r) rdrdθ
Please explain. Also, can it be said as area integration as well like the one in cartesian coordinate?
2. Oct 8, 2012
### haruspex
it depends what you mean by integrating over r and theta. Taken at face value, that just means drdθ. But if you mean that you want to integrate over an area using polar coordinates then it's rdrdθ. The reason is that you can carve up an area into small annular sectors, each running over a range of r to r+dr and θ to θ+dθ. The dimensions of such an area element are dr by rdθ, and approximate a rectangle, so the area of the element is rdrdθ.
3. Oct 8, 2012
### ruzfactor
Thanks. I have a function of r. For example at theta=0, the value of the function have different value at different r values (e.g. r=0 to r=a). I want to evaluate this function over 2∏. So I thought first integrating the function about r and then theta. That is where I am confused, whether to use ∫∫f(r) drdθ or ∫∫f(r) rdrdθ. Please see the attachment where my problem is explained in a pic.
Also, I thought conversion from cartesian coordinate (dxdy) using jacobian makes it rdrdθ in polar coordinate.
File size:
16.1 KB
Views:
79
4. Oct 9, 2012
### haruspex
Clearly you are trying to integrate over an area, so rdrdθ is the correct form.
The Jacobian arises from coordinate transformations where the two coordinate systems describe the same region. In Cartesian, an element of area is dxdy; in polar it is rdrdθ.
5. Oct 9, 2012
### zmp3
In any double integration problem, you can usually start with either. In this situation, you'd be better off starting with the integration of the radius first then integrating with respect to theta.
6. Oct 10, 2012
### haruspex
The OP was not trying to choose between drdθ and dθdr, but between drdθ and rdrdθ.
7. Oct 10, 2012
### HallsofIvy
Staff Emeritus
If your problem is just "given $f(r,\theta)$, integrate it", then you would have $\int\int f(r, \theta)drd\theta$. If, however, the problem is "given $f(r,\theta)$, integrate over a given area in the plane", then you would have $\int\int f(r,\theta) r drd\theta$ because "$rdrd\theta$" is the "differential of area" in polar coordinates. In particular, if you are converting $\int\int f(x,y) dxdy$ to polar coordinates, because dxdy is the "differential of area" in Cartesian coordinates, it would become $\int\int f(r,\theta)r drd\theta$.
8. Oct 10, 2012
### ruzfactor
Thanks. Actually the problem says that, integrate f(r,θ) in radial and circumferential direction. So it is a bit confusing. I guess rdrdθ could be used depending on my problem.
Here, the function f(r,θ) is the mode shape function of a circular plate.
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Similar Discussions: Polar Integration
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https://byjus.com/ncert-solutions-for-class-9-maths-chapter-3-coordinate-geometry-ex-3-2/
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Ncert Solutions For Class 9 Maths Ex 3.2
Ncert Solutions For Class 9 Maths Chapter 3 Ex 3.2
(i) Name the horizontal and the vertical lines drawn to determine the position of any point in the Cartesian plane?
(ii) Name each part of the plane formed by the above two lines?
(iii) Name the point where these two lines intersect.
Sol:
(i) The name of horizontal and vertical lines drawn to determine the position of any point in the Cartesian plane is x-axis and y-axis respectively.
(ii) The name of each part of the plane formed by these two lines x-axis and y-axis is quadrants.
(iii) The point where these two lines intersect is called origin.
Q2. Answer the following referring to the figure given below:
(I) co-ordinates of B.
(II) co-ordinates of C.
(III) co-ordinates of the point L.
(IV) co-ordinates of the point M.
(V) ordinate of the point H.
(VI) abscissa of the point D.
(VII) The point i.e. identified by the co-ordinates (3,5)$(-3,-5)$
(VIII) The point i.e identified by the co-ordinates (2,4)$(2,-4)$.
Solution:
(i) The co-ordinates of B is (5,2)$(-5,2)$.
(ii) The co-ordinates of C is (5,5)$(5,-5)$.
(iii) The co-ordinates of the point L is (0,5)$(0,5)$.
(iv) The co-ordinates of the point M is (3,0)$(-3,0)$.
(v) Ordinate means y coordinate of point H. So, ordinate of point H is -3.
(vi) Abscissa means x co-ordinate of point D. So, abscissa of the point D is 6.
(vii) The point identified by the coordinates (3,5)$(-3,-5)$ is E.
(viii) The point identified by the coordinates (2,4)$(2,-4)$ is G.
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http://mathhelpforum.com/pre-calculus/78812-gains-over-time.html
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1. ## Gains over time
I'll try to explain as thoroughly as possible.
A user gains 1000 population per hour, that is broken down to 0.27 population per second (1000/3600), if X time has passed since the update then the population gain is X*0.27 and then capped at the maximum capacity that a user can have.
The problem is when I want to calculate the gold gain, the gain is dependant on the population and in which the user will gain 1 gold per population that they have per hour. So if they have 1000 population they will gain 1000 population per hour. However to do it the same as above is not accurate and it doesn't take into consideration the gains over time.
----
Population gain:
GainPerHour = 1000;
GainPerSecond = GainPerHour / 3600;
ActualGain = TimeDiffInSeconds * GainPerSec;
Population = Population + ActualGain;
I did the same for gold gain without realising how inaccurate it was, and I have no idea at all how to make it accurate without placing it within a loop for each second and calculating it on a per second basis, which would be far too slow.
One possible solution I think is to do the above for gold but with the OLD population value from before i was updated, and then a formula to work out the gain from what population was added, but with the capacity things that too could become complex. For example if 5000 seconds have passed but the user would have capped their population at 1000 seconds, it would need to take that into consideration for the actual gold gain.
I'm totally confused and lost at how to do this, any help is very much appreciated. I just hope you guys can make sense out of this..
2. After more research and asking about, I've learnt that this will use a series equation..
http://en.wikipedia.org/wiki/Series_(mathematics)
That's as much progress as I've managed to make so far on this.
But to try and make it easier to understand what I have to do i'll try another example.
Say the user gains 1 population per second, the gold income that he would have would be the case of over the course of seconds...
1+2+3+4+5 up to the capacity of the population, so if it capped at 5 population over what was currently there then it would continue as 5+5+5+5 etc up to the end of the range.
I'm so terrible at trying to put things into explainations, so I really hope that this part with the first post makes more sense!
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https://bibbase.org/network/publication/chang-bongarten-hamrick-geneticstructureofnaturalpopulationsofblacklocustrobiniapseudoacacialatcoweetanorthcarolina-1998
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Genetic Structure of Natural Populations of Black Locust (Robinia Pseudoacacia L.) at Coweeta, North Carolina. Chang, C., Bongarten, B., & Hamrick, J. Journal of Plant Research, 111(1):17–24, 1998.
Natural population of black locust maintains very high levels of genetic diversity within populations without any noticeable geographic patterns. In order to assess the species' potential for manipulation through breeding programs, more detailed spatial pattern analyses of fine-scale population structure was attempted in the two study sites (watershed 2 and 21) in the Coweeta River Basin of southern Appalachian mountains using allozyme markers. Of the 200 and 420 plants examined in watershed 21 and 2 respectively, 13 and 15 major genotypes of clone were distinguished. Within watersheds 2 and 21, 60\,% of the pairwise clone combinations had three or four loci differences out of the 8 loci investigated. No correlation between distance between clones and the number of allele difference was found. The similarity values (16 highest and 0 lowest value) among clones for watershed 2 and 21 were 12.82 and 10.19 respectively. Typical distances between clones on both watershed 2 and 21 were from 90 and 190 m, but the range varied from several meters up to 300 m. An average distance among clones were 140.9$\pm$66.0 m and 239.4$\pm$108.6 m in watershed 2 and 21 respectively, whereas an average distance within clone was 38.7$\pm$36.2 m and 145.0$\pm$123.6 m in watershed 2 and 21. Genotype diversity indices (DG) for watershed 2 and 21 were 0.89 and 0.86 respectively. The largest clones on both watersheds covered more than 100 m×100 m. On the other hand, some clones on watershed 2, which had a few fallen trees with many young sprouts (up to 200 individuals), were 45 m×30 m in size under the open habitat. Although clonal substructure and limited seed dispersal may cause near neighbor mating interaction, significant genetic patchiness among clones of black locust was not evident. Although the first establishment of a black locust population would have relied on an off-site seed source, it is more likely that asexual reproduction has occurred for many generations in these black locust populations because of the presence of many different sizes of trees (or ages) in one clone despite widespread opportunities for sexual reproduction. Presence of three or four different sizes of trees within a clone implies that the trees has developed from a clone at each different time. The current study suggested that the amount of sexual reproduction and dispersal rate (especially seed dispersal) should be determined. It would be useful to examine whether or not clonal strategies and patterns of clonal growth of black locust are influenced by density dependent regulation of ramet recruitment and death.
@article{changGeneticStructureNatural1998,
title = {Genetic Structure of Natural Populations of Black Locust ({{Robinia}} Pseudoacacia {{L}}.) at {{Coweeta}}, {{North Carolina}}},
author = {Chang, Chin-Sung and Bongarten, Bruce and Hamrick, James},
year = {1998},
volume = {111},
pages = {17--24},
doi = {10.1007/bf02507146},
abstract = {Natural population of black locust maintains very high levels of genetic diversity within populations without any noticeable geographic patterns. In order to assess the species' potential for manipulation through breeding programs, more detailed spatial pattern analyses of fine-scale population structure was attempted in the two study sites (watershed 2 and 21) in the Coweeta River Basin of southern Appalachian mountains using allozyme markers. Of the 200 and 420 plants examined in watershed 21 and 2 respectively, 13 and 15 major genotypes of clone were distinguished. Within watersheds 2 and 21, 60\,\% of the pairwise clone combinations had three or four loci differences out of the 8 loci investigated. No correlation between distance between clones and the number of allele difference was found. The similarity values (16 highest and 0 lowest value) among clones for watershed 2 and 21 were 12.82 and 10.19 respectively. Typical distances between clones on both watershed 2 and 21 were from 90 and 190 m, but the range varied from several meters up to 300 m. An average distance among clones were 140.9{$\pm$}66.0 m and 239.4{$\pm$}108.6 m in watershed 2 and 21 respectively, whereas an average distance within clone was 38.7{$\pm$}36.2 m and 145.0{$\pm$}123.6 m in watershed 2 and 21. Genotype diversity indices (DG) for watershed 2 and 21 were 0.89 and 0.86 respectively. The largest clones on both watersheds covered more than 100 m\texttimes 100 m. On the other hand, some clones on watershed 2, which had a few fallen trees with many young sprouts (up to 200 individuals), were 45 m\texttimes 30 m in size under the open habitat. Although clonal substructure and limited seed dispersal may cause near neighbor mating interaction, significant genetic patchiness among clones of black locust was not evident. Although the first establishment of a black locust population would have relied on an off-site seed source, it is more likely that asexual reproduction has occurred for many generations in these black locust populations because of the presence of many different sizes of trees (or ages) in one clone despite widespread opportunities for sexual reproduction. Presence of three or four different sizes of trees within a clone implies that the trees has developed from a clone at each different time. The current study suggested that the amount of sexual reproduction and dispersal rate (especially seed dispersal) should be determined. It would be useful to examine whether or not clonal strategies and patterns of clonal growth of black locust are influenced by density dependent regulation of ramet recruitment and death.},
journal = {Journal of Plant Research},
keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-13798425,forest-resources,genetic-diversity,robinia-pseudoacacia,united-states},
lccn = {INRMM-MiD:c-13798425},
number = {1}
}
|
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http://math.stackexchange.com/questions/97147/open-sets-and-poincar%c3%a9s-inequality
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# Open sets and Poincaré's inequality
In many references, Poincaré inequality is presented in the following way :
Let $\Omega\subset \mathbb R^d$ an open bounded set. We can find a constant $C$ which depend of $\Omega$ such that for all $u\in H^1_0(\Omega)$, we have $$\lVert u\rVert_{L^2}\leq C\lVert \nabla u\rVert_{(L^2(\Omega))^d}.$$
In fact it works if $\Omega$ is bounded in one direction. An other sufficient condition is that we can find $v\neq 0$ such that Lebesgue measure of $\{\lambda\in\mathbb R,\lambda v\in \Omega\}$ is finite).
My question, maybe a little vague, is the following: is there a "nice" necessary and sufficient condition on $\Omega$ to have Poincaré's inequality?
-
You know Ziemers Book 'Weakly Differentiable Functions'? Chapter 4 is dedicated to Poincaré type inequalities. – user20266 Jan 7 '12 at 11:19
Yes, but when I looked at it I didn't think about this question. And some pages are missing in Gooble book (which is normal). Anyway, this book is at the library of my university, so I will have a look at it Monday. – Davide Giraudo Jan 7 '12 at 11:29
One generalization I know from one of my teachers can be found here: mathproblems123.wordpress.com/2011/10/05/… This needs $\Omega$ to have Lipschitz boundary, and increases the space of admissible functions $H_0^1(\Omega)$ to a closed subspace of $H^1(\Omega)$ which does not contain the non-zero constant functions. – Beni Bogosel Jan 7 '12 at 17:38
Beni Bogosel: Thanks, I didn't know this result. @Thomas I look at this book, but I didn't find the answer. Maybe should I ask it at MathOverfow. – Davide Giraudo Jan 11 '12 at 10:40
@DavideGiraudo: I suppose such condition can be that $\Omega$ is regular enough such that the Rellich Kondrachov theorem holds. en.wikipedia.org/wiki/Rellich%E2%80%93Kondrachov_theorem – Beni Bogosel Apr 30 '12 at 8:02
Both historically and statistically, the one and only correct name for the inequality in question $$\int\limits_{\Omega}\!|u(x)|^2dx\leqslant C\!\int\limits_{\Omega}\!|\nabla u(x)|^2dx \quad \forall\,u\in H_0^1(\Omega)\tag{\ast}$$ is to be the Friedrichs inequality. Whenever the Sobolev space $H_0^1(\Omega)$ is defined as a closure of the subspace $C_0^{\infty}(\Omega)$ in $H^1(\Omega)$, the Friedrichs inequality $(\ast)$ stays valid for any open set $\Omega\subset\mathbb{R}^d$ of finite thickness, e.g., bounded in at least one direction. Otherwise, a nonsmooth boundary $\partial\Omega$ requires some correct definition of a zero trace on $\partial\Omega$, in which case the validity of inequality $(\ast)$ depends wholly on the nonsmooth domain geometry, while for certain simple generalizations of the zero trace concept, the necessary and sufficient conditions for $(\ast\ast)$ to be valid have already been found. But this is not the case for the true Poincaré inequality that can be written in the form $$\int\limits_{\Omega}\!|u(x)|^2dx\leqslant C\Bigl(\Bigl|\int\limits_{\Omega}\!u(x)dx\Bigr|^2+ \int\limits_{\Omega}\!|\nabla u(x)|^2dx\Bigr) \quad \forall\,u\in H^1(\Omega)\tag{\ast\ast},$$ or in some other equivalent form. Inequality $(\ast\ast)$ is valid for a bounded domain satisfying, e.g., the cone condition, though the cone condition is not necessary for $(\ast\ast)$ to be valid. Alternatively, there is a bounded domain $\Omega$ with just a single singular point $a\in\partial\Omega$ such that $\partial\Omega\backslash\{a\}\in C^1$ while the inequality $(\ast\ast)$ is not valid. But still no condition on the geometry of the nonsmooth bounded domain $\Omega$ necessary and sufficient for the validity of $(\ast\ast)$ has yet been found. And so far, domains for which the inequality $(\ast\ast)$ is valid remain tagged as the Nikodim domains (see p. 330 in R.E. Edwards "Functional Analysis. Theory and Applications". Dover Publ., N.Y., 1995).
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https://direct.mit.edu/neco/article-abstract/29/5/1439/8258/Erratum-to-A-Note-on-Divergences?searchresult=1
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Erratum to “A Note on Divergences” by Xiao Liang, Neural Computation Vol. 28, No. 10, pp. 2045–2062 (2016)
doi:10.1162/NECO_a_00878
In order to assist readers interested in obtaining new results on divergences, I write this erratum to the version of this article initially published.
The second paragraph of Remark 1 should appear as follows:
We just disproved Amari’s conjecture for the general case of
On page 2058, “
Acknowledgments should appear as follows:
I thank the referees very much for helpful comments and suggestions, which led to my revision on section 3. Moreover, I am grateful to the referees for bringing Amari (2016) and Jiao, Courtade, No, Venkat, and Weissman (2015) to my attention. I thank Z. Lei of Fudan University for valuable instructions, comments, and suggestions on the note.
On page 2062, “Interference” in line 2 should be...
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https://forum.qt.io/topic/70662/error-with-xmpp-in-qt-5-2
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# Error with xmpp in qt 5.2
• Hi guys i have problem with xmpp because i cant use in my app. When i included with this:
LIBS += -lxmpp_d0 , anyways it doesnt work
The error that i get:
#include <qxmpp/QXmppClient.h>
^
And the libraries that take me this error obviously it is like this:
#include <qxmpp/QXmppClient.h>
#include <qxmpp/QXmppTransferManager.h>
• You need to specify the path to where that include file is i.e. add in your .pro file:
``````INCLUDEPATH += wherever/qxmpp/folder/is
``````
Also, unless you copied lib to the project directory you need to specify the path to that lib too i.e:
``````LIBS += -Lwherever/the/lib/folder/is -lxmpp_d0
``````
Last but not least, after you make changes in the .pro file remember to re-run qmake (Build->Run qmake) before you compile your project.
Looks like your connection to Qt Forum was lost, please wait while we try to reconnect.
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http://www.o4i.com.cn/singlepage.html
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## SINGLE PAGE
##### What turn out consetetur sadipscing elit
Lorem Ipsum is simply dummy text of the printing and typesetting industry.Lorem Ipsum has been the industry's standard dummy text ever since,Lorem Ipsum is simply dummy text of the printing and typesetting industry.Lorem Ipsum is simply dummy text of the printing and typesetting industryLorem Ipsum has been the industry's standard dummy text ever since Lorem Ipsum has been the industry's standard dummy text ever since the 1500s.
1年的分析师支持，以及excel格式的数据支持。
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https://eprints.iisc.ac.in/5332/
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# The influence of microscopic parameters on the ionic conductivity of $SrBi_{2}(Nb_{1-x}V_{x})_{2}O_{9-\delta}(0 \leq x \leq 0.3)$ ceramics
Venkataraman, Harihara B and Varma, KBR (2005) The influence of microscopic parameters on the ionic conductivity of $SrBi_{2}(Nb_{1-x}V_{x})_{2}O_{9-\delta}(0 \leq x \leq 0.3)$ ceramics. In: Journal of Physics and Chemistry of Solids, 66 (10). pp. 1640-1646.
PDF av137.pdf Restricted to Registered users only Download (335kB) | Request a copy
## Abstract
Layered $SrBi_{2}(Nb_{1-x}V_{x})_{2}O_{9-\delta}$(SBVN) ceramics with x lying in the range 0-0.3 (30 mol%) were fabricated by the conventional sintering technique. The microstructural studies confirmed the truncating effect of $V_{2}O_{5}$ on the abnormal platy growth of SBN grains. The electrical conductivity studies were centred in the 573-823 K as the Curie temperature ties in this range. The concentration of mobile charge carriers (n), the diffusion constant $(D_{O})$ and the mean free path (a) were calculated by using Rice and Roth formalism. The conductivity parameters such as ion-hopping rate $(\omega_{p})$ and the charge carrier concentration (K') term have been calculated using Almond and West formalism. The aforementioned microscopic parameters were found to be $V_{2}O_{5}$ content dependent on $SrBi_{2}(Nb_{1-x}V_{x})_{2}O_{9-\delta}$ ceramics.
Item Type: Journal Article Journal of Physics and Chemistry of Solids Elsevier Science Ltd Copyright for this article belongs to Elsevier. A. Ceramics;C. X-ray diffraction; D. Microstructure; D. Diffusion; D. Electrical properties Division of Chemical Sciences > Materials Research Centre 13 Feb 2006 19 Sep 2010 04:23 http://eprints.iisc.ac.in/id/eprint/5332
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https://quomodocumque.wordpress.com/tag/expanders/
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## Breuillard’s ICM talk: uniform expansion, Lehmer’s conjecture, tauhat
Emmanuel Breuillard is in Korea talking at the ICM; here’s his paper, a very beautiful survey of uniformity results for growth in groups, by himself and others, and of the many open questions that remain.
He starts with the following lovely observation, which was apparently in a 2007 paper of his but which I was unaware of. Suppose you make a maximalist conjecture about uniform growth of finitely generated linear groups. That is, you postulate the existence of a constant c(d) such that, for any finite subset S of GL_d(C), you have a lower bound for the growth rate
$\lim |S^n|^{1/n} > c(d)$.
It turns out this implies Lehmer’s conjecture! Which in case you forgot what that is is a kind of “gap conjecture” for heights of algebraic numbers. There are algebraic integers of height 0, which is to say that all their conjugates lie on the unit circle; those are the roots of unity. Lehmer’s conjecture says that if x is an algebraic integer of degree n which is {\em not} a root of unity, it’s height is bounded below by some absolute constant (in fact, most people believe this constant to be about 1.176…, realized by Lehmer’s number.)
What does this question in algebraic number theory have to do with growth in groups? Here’s the trick; let w be an algebraic integer and consider the subgroup G of the group of affine linear transformations of C (which embeds in GL_2(C)) generated by the two transformations
x -> wx
and
x -> x+1.
If the group G grows very quickly, then there are a lot of different values of g*1 for g in the word ball S^n. But g*1 is going to be a complex number z expressible as a polynomial in w of bounded degree and bounded coefficients. If w were actually a root of unity, you can see that this number is sitting in a ball of size growing linearly in n, so the number of possibilities for z grows polynomially in n. Once w has some larger absolute values, though, the size of the ball containing all possible z grows exponentially with n, and Breuillard shows that the height of z is an upper bound for the number of different z in S^n * 1. Thus a Lehmer-violating sequence of algebraic numbers gives a uniformity-violating sequence of finitely generated linear groups.
These groups are all solvable, even metabelian; and as Breuillard explains, this is actually the hardest case! He and his collaborators can prove the uniform growth results for f.g. linear groups without a finite-index solvable subgroup. Very cool!
One more note: I am also of course pleased to see that Emmanuel found my slightly out-there speculations about “property tau hat” interesting enough to mention in his paper! His formulation is more general and nicer than mine, though; I was only thinking about profinite groups, and Emmanuel is surely right to set it up as a question about topologically finitely generated compact groups in general.
## Superstrong approximation for monodromy groups (and Galois groups?)
Hey, I posted a paper to the arXiv and forgot to blog about it! The paper is called “Superstrong approximation for monodromy groups” and it roughly represents the lectures I gave at the MSRI workshop last February on “Thin Groups and Superstrong Approximation.” Hey, as I write this I see that MSRI has put video of these lectures online:
But the survey paper has more idle speculation in it than the lectures, and fewer “um”s, so I recommend text over video in this case! I mean, if you like idle speculation. But if you don’t, would you be reading this blog?
I’m going to recount one of the idle speculations here, but first:
What is superstrong approximation?
Let’s say you have a graph on N vertices, regular of degree d. One basic thing you want to know about the graph is what the connected components are, or at least how many there are. That seems like a combinatorial question, and it is, but in a sense it is also a spectral question: the random walk on the graph, thought of as an operator T on the space of functions on the graph, is going to have eigenvalues between [1,-1], and the mutiplicity of 1 is precisely the number of components; the eigenspace consists of the locally constant functions which are constant on connected components.
So being connected means that the second-largest eigenvalue of T is strictly less than 1. And so you might say a graph is superconnected (with respect to some positive constant x) if the second-largest eigenvalue is at most 1-x. But we don’t say “superconnected” because we already have a word for this notion; we say the graph has a spectral gap of size x. Now of course any connected graph has a spectral gap! But the point is always to talk about families of graphs, typically with d fixed and N growing; we say the family has a spectral gap if, for some positive x, each graph in the family has a spectral gap of size at least x. (Such a family is also called an expander family, because the random walks on those graphs tend to bust out of any fixed-size region very quickly; the relation between this point of view and the spectral one would be a whole nother post.)
When does life hand you a family of graphs? OK, here’s the situation — let’s say you’ve got d matrices in SL_n(Z), or some other arithmetic group. For every prime p, your matrices project to d elements in SL_n(Z/pZ), which produce a Cayley graph X_p, and X_p is connected just when those elements generate SL_n(Z/pZ). If your original matrices generate SL_n(Z), their reductions mod p generate SL_n(Z/pZ); this is just the (not totally obvious!) fact that SL_n(Z) surjects onto SL_n(Z/pZ). But more is true; it turns out that if the group Gamma generated by your matrices is Zariski-dense in SL_n, this is already enough to guarantee that X_p is connected for almost all p. This statement is called strong approximation for Gamma.
But why stop there — we can ask not only whether X_p is connected, but whether it is superconnected! That is: does the family of graphs X_p have a spectral gap? If so, we say Gamma has superstrong approximation, which is now seen to be a kind of quantitative strengthening of strong approximation.
We know much more than we did five years ago about which groups have superstrong approximation, and what the applications are when this is so. Sarnak’s paper from the same conference provides a good overview.
Idle speculation: superstrong approximation for Galois groups
Another way to express superstrong approximation is to say that Gamma has property tau with respect to the congruence quotients SL_n(Z/pZ).
In the survey paper, I wonder whether there is some way to talk about superstrong approximation for Galois groups with bounded ramification. For instance; let G be the Galois group of the maximal extension of Q which is tamely ramified everywhere, and unramified away from 2,3,5, and 7. OK, that’s some profinite group. I don’t know much about it. By Golod-Shafarevich I could prove it was infinite, unless I couldn’t, in which case I would toss in some more ramified primes until I could.
We could ask something like the following. Given any finite quotient Q of G, and any two elements of G whose images generated Q, we get a connected Cayley graph of degree 4 on the elements of Q, by means of those two elements and their inverses. Is there a uniform spectral gap for all those graphs?
I have no real reason to think so. But remark: this would imply immediately that every finite-index subgroup of G has finite abelianization, and that’s true. It would also imply that there are only finitely many n such that G surjects onto S_n, and that might be true. Reader survey for those who’ve read this far: do you think there’s a finite set S of primes such that there are tamely ramified S_n-extensions of Q, for n arbitrarily large, unramified outside S?
Acknowledgment: I was much aided in formulating this question by the comments on the MathOverflow question I asked about it.
## Gonality, the Bogomolov property, and Habegger’s theorem on Q(E^tors)
I promised to say a little more about why I think the result of Habegger’s recent paper, ” Small Height and Infinite Non-Abelian Extensions,” is so cool.
First of all: we say an algebraic extension K of Q has the Bogomolov property if there is no infinite sequence of non-torsion elements x in K^* whose absolute logarithmic height tends to 0. Equivalently, 0 is isolated in the set of absolute heights in K^*. Finite extensions of Q evidently have the Bogomolov property (henceforth: (B)) but for infinite extensions the question is much subtler. Certainly $\bar{\mathbf{Q}}$ itself doesn’t have (B): consider the sequence $2^{1/2}, 2^{1/3}, 2^{1/4}, \ldots$ On the other hand, the maximal abelian extension of Q is known to have (B) (Amoroso-Dvornicich) , as is any extension which is totally split at some fixed place p (Schinzel for the real prime, Bombieri-Zannier for the other primes.)
Habegger has proved that, when E is an elliptic curve over Q, the field Q(E^tors) obtained by adjoining all torsion points of E has the Bogomolov property.
What does this have to do with gonality, and with my paper with Chris Hall and Emmanuel Kowalski from last year?
Suppose we ask about the Bogomolov property for extensions of a more general field F? Well, F had better admit a notion of absolute Weil height. This is certainly OK when F is a global field, like the function field of a curve over a finite field k; but in fact it’s fine for the function field of a complex curve as well. So let’s take that view; in fact, for simplicity, let’s take F to be C(t).
What does it mean for an algebraic extension F’ of F to have the Bogomolov property? It means that there is a constant c such that, for every finite subextension L of F and every non-constant function x in L^*, the absolute logarithmic height of x is at least c.
Now L is the function field of some complex algebraic curve C, a finite cover of P^1. And a non-constant function x in L^* can be thought of as a nonzero principal divisor. The logarithmic height, in this context, is just the number of zeroes of x — or, if you like, the number of poles of x — or, if you like, the degree of x, thought of as a morphism from C to the projective line. (Not necessarily the projective line of which C is a cover — a new projective line!) In the number field context, it was pretty easy to see that the log height of non-torsion elements of L^* was bounded away from 0. That’s true here, too, even more easily — a non-constant map from C to P^1 has degree at least 1!
There’s one convenient difference between the geometric case and the number field case. The lowest log height of a non-torsion element of L^* — that is, the least degree of a non-constant map from C to P^1 — already has a name. It’s called the gonality of C. For the Bogomolov property, the relevant number isn’t the log height, but the absolute log height, which is to say the gonality divided by [L:F].
So the Bogomolov property for F’ — what we might call the geometric Bogomolov property — says the following. We think of F’ as a family of finite covers C / P^1. Then
(GB) There is a constant c such that the gonality of C is at least c deg(C/P^1), for every cover C in the family.
What kinds of families of covers are geometrically Bogomolov? As in the number field case, you can certainly find some families that fail the test — for instance, gonality is bounded above in terms of genus, so any family of curves C with growing degree over P^1 but bounded genus will do the trick.
On the other hand, the family of modular curves over X(1) is geometrically Bogomolov; this was proved (independently) by Abramovich and Zograf. This is a gigantic and elegant generalization of Ogg’s old theorem that only finitely many modular curves are hyperelliptic (i.e. only finitely many have gonality 2.)
At this point we have actually more or less proved the geometric version of Habegger’s theorem! Here’s the idea. Take F = C(t) and let E/F be an elliptic curve; then to prove that F(E(torsion)) has (GB), we need to give a lower bound for the curve C_N obtained by adjoining an N-torsion point to F. (I am slightly punting on the issue of being careful about other fields contained in F(E(torsion)), but I don’t think this matters.) But C_N admits a dominant map to X_1(N); gonality goes down in dominant maps, so the Abramovich-Zograf bound on the gonality of X_1(N) provides a lower bound for the gonality of C_N, and it turns out that this gives exactly the bound required.
What Chris, Emmanuel and I proved is that (GB) is true in much greater generality — in fact (using recent results of Golsefidy and Varju that slightly postdate our paper) it holds for any extension of C(t) whose Galois group is a perfect Lie group with Z_p or Zhat coefficients and which is ramified at finitely many places; not just the extension obtained by adjoining torsion of an elliptic curve, for instance, but the one you get from the torsion of an abelian variety of arbitrary dimension, or for that matter any other motive with sufficiently interesting Mumford-Tate group.
Question: Is Habegger’s theorem true in this generality? For instance, if A/Q is an abelian variety, does Q(A(tors)) have the Bogomolov property?
Question: Is there any invariant of a number field which plays the role in the arithmetic setting that “spectral gap of the Laplacian” plays for a complex algebraic curve?
A word about Habegger’s proof. We know that number fields are a lot more like F_q(t) than they are like C(t). And the analogue of the Abramovich-Zograf bound for modular curves over F_q is known as well, by a theorem of Poonen. The argument is not at all like that of Abramovich and Zograf, which rests on analysis in the end. Rather, Poonen observes that modular curves in characteristic p have lots of supersingular points, because the square of Frobenius acts as a scalar on the l-torsion in the supersingular case. But having a lot of points gives you a lower bound on gonality! A curve with a degree d map to P^1 has at most d(q+1) points, just because the preimage of each of the q+1 points of P^1(q) has size at most d. (You just never get too old or too sophisticated to whip out the Pigeonhole Principle at an opportune moment….)
Now I haven’t studied Habegger’s argument in detail yet, but look what you find right in the introduction:
The non-Archimedean estimate is done at places above an auxiliary prime number p where E has good supersingular reduction and where some other technical conditions are met…. In this case we will obtain an explicit height lower bound swiftly using the product formula, cf. Lemma 5.1. The crucial point is that supersingularity forces the square of the Frobenius to act as a scalar on the reduction of E modulo p.
Yup! There’s no mention of Poonen in the paper, so I think Habegger came to this idea independently. Very satisfying! The hard case — for Habegger as for Poonen — has to do with the fields obtained by adjoining p-torsion, where p is the characteristic of the supersingular elliptic curve driving the argument. It would be very interesting to hear from Poonen and/or Habegger whether the arguments are similar in that case too!
## JMM, Golsefidy, Silverman, Scanlon
Like Emmanuel, I spent part of last week at the Joint Meetings in New Orleans, thanks to a generous invitation from Alireza Salefi Golsefidy and Alex Lubotzky to speak in their special session on expander graphs. I was happy that Alireza was willing to violate a slight taboo and speak in his own session, since I got to hear about his work with Varju, which caps off a year of spectacular progress on expansion in quotients of Zariski-dense subgroups of arithmetic groups. Emmanuel’s Bourbaki talk is your go-to expose.
I think I’m unlike most mathematicians in that I really like these twenty-minute talks. They’re like little bonbons — you enjoy one and then before you’ve even finished chewing you have the next in hand! One nice bonbon was provided by Joe Silverman, who talked about his recent work on Lehmer’s conjecture for polynomials satisfying special congruences. For instance, he shows that a polynomial which is congruent mod m to a multiple of a large cyclotomic polynomial can’t have a root of small height, unless that root is itself a root of unity. He has a similar result where the implicit G_m is replaced by an elliptic curve, and one gets a lower bound for algebraic points on E which are congruent mod m to a lot of torsion points. This result, to my eye, has the flavor of the work of Bombieri, Pila, and Heath-Brown on rational points. Namely, it obeys the slogan: Low-height rational points repel each other. More precisely — the global condition (low height) is in tension with a bunch of local conditions (p-adic closeness.) This is the engine that drives the upper bounds in Bombieri-Pila and Heath-Brown: if you have too many low-height points, there’s just not enough room for them to repel each other modulo every prime!
Anyway, in Silverman’s situation, the points are forced to nestle very close to torsion points — the lowest-height points of all! So it seems quite natural that their own heights should be bounded away from 0 to some extent. I wonder whether one can combine Silverman’s argument with an argument of the Bombieri-Pila-Heath-Brown type to get good bounds on the number of counterexamples to Lehmer’s conjecture….?
One piece of candy I didn’t get to try was Tom Scanlon’s Current Events Bulletin talk about the work of Pila and Willkie on problems of Manin-Mumford type. Happily, he’s made the notes available and I read it on the plane home. Tom gives a beautifully clear exposition of ideas that are rather alien to most number theorists, but which speak to issues of fundamental importance to us. In particular, I now understand at last what “o-minimality” is, and how Pila’s work in this area grows naturally out of the Bombieri-Pila method mentioned above. Highly recommended!
## Expander graphs, gonality, and variation of Galois representations
Suppose you have a 1-dimensional family of polarized abelian varieties — or, just to make things concrete, an abelian variety A over Q(t) with no isotrivial factor.
You might have some intuition that abelian varieties over Q don’t usually have rational p-torsion points — to make this precise you might ask that A_t[p](Q) be empty for “most” t.
In fact, we prove (among other results of a similar flavor) the following strong version of this statement. Let d be an integer, K a number field, and A/K(t) an abelian variety. Then there is a constant p(A,d) such that, for each prime p > p(A,d), there are only finitely many t such that A_t[p] has a point over a degree-d extension of K.
The idea is to study the geometry of the curve U_p parametrizing pairs (t,S) where S is a p-torsion point of A_t. This curve is a finite cover of the projective line; if you can show it has genus bigger than 1, then you know U_p has only finitely many K-rational points, by Faltings’ theorem.
But we want more — we want to know that U_p has only finitely many points over degree-d extensions of K. This can fail even for high-genus curves: for instance, the curve
C: y^2 = x^100000 + x + 1
has really massive genus, but choosing any rational value of x yields a point on C defined over a quadratic extension of Q. The problem is that C is hyperelliptic — it has a degree-2 map to the projective line. More generally, if U_p has a degree-d map to P^1, then U_p has lots of points over degree-d extensions of K. In fact, Faltings’ theorem can be leveraged to show that a kind of converse is true.
So the relevant task is to show that U_p admits no map to P^1 of degree less than d; in other words, its gonality is at least d.
Now how do you show a curve has large gonality? Unlike genus, gonality isn’t a topological invariant; somehow you really have to use the geometry of the curve. The technique that works here is one we learned from an paper of Abramovich; via a theorem of Li and Yau, you can show that the gonality of U_p is big if you can show that the Laplacian operator on the Riemann surface U_p(C) has a spectral gap. (Abramovich uses this technique to prove the g=1 version of our theorem: the gonality of classical modular curves increases with the level.)
We get a grip on this Laplacian by approximating it with something discrete. Namely: if U is the open subvariety of P^1 over which A has good reduction, then U_p(C) is an unramified cover of U(C), and can be identified with a finite-index subgroup H_p of the fundamental group G = pi_1(U(C)), which is just a free group on finitely many generators g_1, … g_n. From this data you can cook up a Cayley-Schreier graph, whose vertices are cosets of H_p in G, and whose edges connect g H with g_i g H. Thanks to work of Burger, we know that this graph is a good “combinatorial model” of U_p(C); in particular, the Laplacian of U_p(C) has a spectral gap if and only if the adjacency matrix of this Cayley-Schreier graph does.
At this point, we have reduced to a spectral problem having to do with special subgroups of free groups. And if it were 2009, we would be completely stuck. But it’s 2010! And we have at hand a whole spray of brand-new results thanks to Helfgott, Gill, Pyber, Szabo, Breuillard, Green, Tao, and others, which guarantee precisely that Cayley-Schreier graphs of this kind, (corresponding to finite covers of U(C) whose Galois closure has Galois group a perfect linear group over a finite field) have spectral gap; that is, they are expander graphs. (Actually, a slightly weaker condition than spectral gap, which we call esperantism, is all we need.)
Sometimes you think about a problem at just the right time. We would never have guessed that the burst of progress in sum-product estimates in linear groups would make this the right time to think about Galois representations in 1-dimensional families of abelian varieties, but so it turned out to be. Our good luck.
## In which I publish my first paper
The first one I wrote, that is. It happened like this: my undergraduate thesis advisor was Persi Diaconis, and in 1993, my senior year, Diaconis was really peeved about the proof via Selberg that every element of SL_2(F_p) could be expressed as a word of length at most C log p in the standard unipotent generators. (See Emmanuel’s comment on Terry’s blog for useful references.) Diaconis felt it was a combinatorial problem and it should be solvable by purely combinatorial means, and that a hard-working undergraduate who was good at Putnam problems, like me, ought to be able to do it.
That turned out not to be the case.
So Persi gave me another thesis problem; he asked if I could get good bounds on the diameter of the unipotent subgroup U of SL_n(F_p), with its standard generating set id + e_{i,i+1}. When n = 2, this is easy; the unipotent group is just Z/pZ and its diameter is about p. The question is: what happens asymptotically when n and p are allowed to grow?
It’s not possible any longer for the diameter of U to be on order log |U|, as is the case for SL_2(F_p); the abelianization of U looks like (Z/pZ)^{n-1}, which already has diameter on order of np. Unless n is much larger than p, this swamps log |U|.
But it turns out this is in some sense the only obstacle: one can prove that diam(U) is bounded above and below by constant multiples of
np + log |U|.
(My memory is that I conceived the key step of the argument during a boring Advocate meeting.)
Much later, when I was a new postdoc at Princeton, I talked about this problem with Julianna Tymoczko, then a graduate student working with Bob McPherson. Julianna very quickly saw how to make the argument much more conceptual and general, and in particular how to extend it to all the classical groups. So we decided to write it up as a joint paper. That was probably 2002. Then we got around to writing the paper and submitting it. That was 2005. It was accepted in 2007. And now here it is! That’s the abstract; if you’re at a computer that doesn’t subscribe to Forum Math, here’s the arXiv version. 17 years from first version of the theorem to publication!
Update: Harald Helfgott politely comment-hints at something I should have put in the original post, which is that nowadays, thanks to him, there is a combinatorial proof that the diameter of SL_2(F_p) is on order log p! The subject of uniform bounds for word growth and spectral gaps in finite groups of Lie type is currently moving very quickly. I won’t try to summarize the state of the art, but you can expect in the medium-term to hear something about an interesting application of Harald’s work to arithmetic geometry.
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http://math.stackexchange.com/questions/301315/invertibility-of-a-kronecker-product?answertab=active
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# Invertibility of a Kronecker Product
Prove that A Kronecker Product B is invertible if and only if B Kronecker Product A is invertible.
I dont have a clue where to start to be honest. I am not very familiar yet to the Kronecker Product so could you please help me with providing an easyily understandable proof.
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The previous answers assume that $A$ and $B$ are square. This is fair because it is not generally possible for $A\otimes B$ to be invertible when $A$ and $B$ are rectangular.
In the more general setting where $A$ is $m\times n$ and $B$ is $r\times s$ (and $mr = ns$) it is still easy to see that $A\otimes B$ is equivalent to $B \otimes A$ up to permuting the rows and columns.
Both $A \otimes B$ and $B \otimes A$ contain exactly the same entries $a_{ij} b_{kl}$. More explicitly, one places $a_{ij} b_{kl}$ in row $(i-1)r+k$ and column $(j-1)s+l$, and the other places it in row $(k-1)m+i$ and column $(l-1)n+j$. Note that the row numbers are uniquely determined by $i,k$ and the column numbers determined independently by $j,l$.
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Hint: If $A$ is a $m\times m$ matrix and $B$ a $n\times n$ matrix then $$\det(A\otimes B)=(\det A)^n\cdot (\det B)^m.$$
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A square matrix is invertible if and only if its determinant is different from $0$. – Davide Giraudo Feb 12 '13 at 16:57
What do you know about invertible matrices? – Davide Giraudo Feb 12 '13 at 17:02
You can show that $A\otimes B$ is invertible if and only if $A$ and $B$ are invertible, from which this result follows.
If $A$ and $B$ are invertible, do you know how to find $(A\otimes B)^{-1}$?
If $A$ is not invertible, then there exists $C\neq 0$ such that $CA=0$. It follows that $(C\otimes I)(A\otimes B)=0$, which implies that $A\otimes B$ is not invertible.
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http://mathhelpforum.com/calculus/110765-integration-first-converting-spherical-polars-print.html
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# Integration first converting to spherical polars
• Oct 27th 2009, 02:08 AM
StarWrecker
Integration first converting to spherical polars
I'm trying to work through a question, but I cannot get my result to look anything like the model answers.
The question is to integrate
z/((x^2+y^2)^(1/2)) over the volume of a region bounded by the surfaces z=0 and z=(9-x^2-y^2)^(1/2).
I know I need to use spherical polar co-ordinates to do this, but I can't seem to get the substitutions right.
The model answer says that it becomes r^2*cos(theta) integrated over the obvious region, but my attempt to get it is as such:
z = r*cos(theta)
r = (x^2+y^2)^(1/2) (in 2 dimensions, ignoring z)
So,
the integral is
integral( (r*cos(theta) / r) * r^2 * sin(theta) drd(theta)d(phi) )
Of course this gives me r^2*cos(theta)*sin(theta).
What am I missing?
• Oct 27th 2009, 04:14 AM
Mush
Quote:
Originally Posted by StarWrecker
I'm trying to work through a question, but I cannot get my result to look anything like the model answers.
The question is to integrate
z/((x^2+y^2)^(1/2)) over the volume of a region bounded by the surfaces z=0 and z=(9-x^2-y^2)^(1/2).
I know I need to use spherical polar co-ordinates to do this, but I can't seem to get the substitutions right.
The model answer says that it becomes r^2*cos(theta) integrated over the obvious region, but my attempt to get it is as such:
z = r*cos(theta)
r = (x^2+y^2)^(1/2) (in 2 dimensions, ignoring z)
So,
the integral is
integral( (r*cos(theta) / r) * r^2 * sin(theta) drd(theta)d(phi) )
Of course this gives me r^2*cos(theta)*sin(theta).
What am I missing?
Why did you choose to ignore z?
In spherical coordinates $x = r \cos(\varphi) \sin (\theta)$, and $y = r \sin(\varphi) \sin(\theta)$. You should use this definition to calculate $(x^2 + y^2)^{\frac{1}{2}}$, and you should get $(x^2 + y^2)^{\frac{1}{2}} = r \sin(\theta)$
Giving you an integrand of $\frac{r \cos(\theta)}{r \sin(\theta} r^2 \sin(\theta) = r^2 \cos(\theta)$
• Oct 27th 2009, 04:21 AM
HallsofIvy
That's one reason why it is more common to use " $\rho$" as the radial variable in spherical coordinates (and they are NOT normally referred to as "spherical polar coordinates), to avoid confusing 3d and 2d coordinates.
In spherical coordinates $x= \rho cos(\phi) sin(\theta)$ and $y= \rho sin(\phi) sin(\theta)$. Then $x^2+ y^2= \rho^2 cos^2(\phi)sin^2(\theta)+ \rho^2 sin^2(\phi)sin^2(\theta)$ $= \rho^2 sin^2(\theta)(cos^2(\phi)+ sin^2(\phi))= \rho^2 sin^2(\phi)$ so that $(x^2+ y^2)^{1/2}= \rho sin(\phi)$
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http://physics.stackexchange.com/users/6665/vishwas-gagrani?tab=activity
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# Vishwas Gagrani
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bio website location age 32 member for 2 years, 9 months seen Aug 16 at 17:26 profile views 73
A Flash AS3.0/AS2.0 Developer. Have experience into building multiplayer games with Smartfox.
My work-profile videos available at :http://www.youtube.com/watch?v=gje7pI70uJY&feature=channel&list=UL
Thanks for having a look at my profile. :)
# 41 Actions
Aug2 asked Why do physical bodies in the universe follow the law of physics ( or any rule/pattern ) ? Jul27 accepted A vehicle moves from rest to a certain distance. Would the distance time graph always be curved? Jul27 asked A vehicle moves from rest to a certain distance. Would the distance time graph always be curved? Jul9 asked Mathematical calculation of probability of existence of planet similar to earth May29 awarded Popular Question Mar15 asked Is passing on knowledge/information from one body to another and the resultant state is ever studied as any branch of physics? Nov20 comment Why force $F$ is $ma$ but not $md$ or $mv$? How can I observe and understand “force” in real life? hmm... well, yes, it was silly me, where i am not involving the importance of time. As clearly enough, if two quantities with same mass and same displacement need to be compared for the force, then it's time, which will be deciding factor, which force is gonna be greater than the other. :) Thanks for the explanation :) Nov20 accepted Why force $F$ is $ma$ but not $md$ or $mv$? How can I observe and understand “force” in real life? Nov20 comment Why force $F$ is $ma$ but not $md$ or $mv$? How can I observe and understand “force” in real life? Well, i understand, that i cannot debate against hundreds of years of studies developed by geniuses .. but frankly what seems more intuitive to me, is that the force with which i hit, ofcourse involves the quantities like mass and displacement. But why time is important here.. is something, i need to contemplate upon! :P Nov20 comment Why force $F$ is $ma$ but not $md$ or $mv$? How can I observe and understand “force” in real life? So, if my velocity is constant, then i am not applying any force. How come this is similar to real life scenario ? Nov20 asked Why force $F$ is $ma$ but not $md$ or $mv$? How can I observe and understand “force” in real life? Jul18 accepted Velocity is “Distance/Time” in a particular direction OR simply “Displacement/Time”? Jul12 asked Velocity is “Distance/Time” in a particular direction OR simply “Displacement/Time”? Jun6 comment What is the direction of a point vector. A vector with magnitude 0? Ya, so as per the last paragraph, a quick litmus test to know, if a quantity is vector or scalar.. is to play with it's directions. If the output of the quantity changes with directions, it's vector! Otherwise, it's scalar Jun6 awarded Commentator Jun6 comment What is the direction of a point vector. A vector with magnitude 0? Not talking about specific example. Also, "0" is something, that always produce unique results. 1/0 , 0/0 etc. What i am asking, is if their is some quantity which doesnot use direction but still is vector. eg. "distance", doesnot use direction but IS SCALAR. Likewise, any example "x", doesnot use direction but IS VECTOR ? Jun6 comment What is the direction of a point vector. A vector with magnitude 0? Any example of vector quantity, that has magnitude only, but no direction ? What i learnt is, if anything doesnot have a direction then it's scalar. Jun6 accepted What is the direction of a point vector. A vector with magnitude 0? Jun6 comment What is the direction of a point vector. A vector with magnitude 0? true! I studied that in school time. So, is it not mandatory for vectors to have direction? :p Jun6 asked What is the direction of a point vector. A vector with magnitude 0?
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https://cryptocode.wordpress.com/2009/01/29/constructing-a-field/
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Constructing a field
Have just finished reading Chapter 4 from “Finite Fields for Computer Scientists and Engineers – Robert J. McEliece”.
I’ve been away from the computer and spend the whole morning scribbling some calculation on constructing a field. Me now understand that when we have an Euclidean domain $D=F_{2}\left [x \right ]$ with for example $p\left (x \right )=x^{4}+x+1$, that $p$ is irreducible because $p\left (0 \right )=1$ and $p\left (1 \right )=1$, so $p\left (x \right )$ has no zeroes in $F_{2}$.
bla bla bla bla … i have many pages of scribbles…
But I’d like to post this tables here just for a quick reminder for me, it’s unfinished but I’ve got the idea so keeping it up here will be useful someday when I forgot about this $F_{2}^{m}$ stuff 😀
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http://science.sciencemag.org/content/237/4814/535
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Reports
# Full-wave rectification from a mixed electrical-chemical synapse
See allHide authors and affiliations
Science 31 Jul 1987:
Vol. 237, Issue 4814, pp. 535-537
DOI: 10.1126/science.2885921
## Abstract
Electrical and chemical synapses usually reinforce one another, but the pyloric late-to-lateral pyloric (PL-to-LP) neuronal connections in lobster stomatogastric ganglia create an inverted U-shaped transfer function between the two neurons: regardless of whether the PL membrane voltage swings positive or negative, the postsynaptic LP voltage will go negative. When the presynaptic cell voltage goes negative, the effect on the LP voltage is due to electrical coupling. During positive presynaptic voltages, the strong contribution of graded chemical inhibition from the PL to the LP neuron overrides the positive electrical coupling to produce net negativity.
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https://owenduffy.net/blog/?p=855
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# Designing high performance VHF/UHF receive systems – Part 1
## G/T
A metric that may be used to express the performance of an entire receive system is the ratio of antenna gain to total equivalent noise temperature, usually expressed in deciBels as dB/K. G/T is widely used in design and specification of satellite communications systems.
G/T=AntennaGain/TotalNoiseTemperature 1/K
Example: if AntennaGain=50 and TotalNoiseTemperature=120K, then G/T=50/120=0.416 1/K or -3.8 dB/K.
The utility of G/T is that receive S/N changes dB for dB with G/T, in fact you can calculate S/N knowing G/T, wavelength, bandwidth and the field strength of the signal (Duffy 2007).
S/N=S*λ2/(4*π)*G/T/(kb*B) where:
S is power flux density;
λ is wavelength;
kb is Boltzmann’s constant; and
B is receiver effective noise bandwidth
Calculating G/T for configuration alternatives gives a single performance metric that allows comparison of the performance of the configurations. Different levels of performance might be weighed against cost in a cost benefit analysis, eg whether funds applied to antenna improvements will be more cost-effective than applying funds to feed line improvement, whether an LNA with NF=0.8dB and Gain=30dB is more cost-effective than one with NF=0.5dB and Gain=18dB.
Such a quantitative approach cuts through the old wives tales about the relative merit of some approaches, and will quantify the relative performance in the system context. Some options will have different effects depending on other system details, and Rules of Thumb (ROT) that ignore this sensitivity to the rest of the system becomes simply rot.
Inclusion of gain in the metric allows quantitative comparison of configuration changes that include a change in antenna gain.
A key limitation of simple system models is that they assume the system is linear, in particular that there is no significant IMD noise created by system components. Systems with significant IMD are basically unpredictable, and whilst the performance of a particular system can be measured, that does not provide knowledge that is extensible to another system because the environment, and response to the environment are probably different. The bottom line is that components with significant IMD noise don’t belong in a high performance system, fix them or get rid of them.
Note that the popular ham antenna tables published by VE7BQH which show a calculated quantity labelled G/T value for antenna systems appears to ignore receiver equivalent noise (ie it is for a noiseless receiver), and as such, the usage is not consistent with the industry meaning of the term (eg ITU-R. 2000). Don’t confuse this discussion of G/T with those tables.
G/T is calculated with respect to some nominated reference plane. The most common practice is to use the antenna waveguide flange or connector as the reference plane, and to consistently calculate system component contributions relative to that reference plane. In the case of an array of four Yagi antennas, the reference plane would be the connector on the power divider/combiner that provides single connector access to the antenna system.
## References
• Duffy, O. 2006. Effective use of a Low Noise Amplifier on VHF/UHF. VK1OD.net (offline).
• ———. 2006. Receiver sensitivity metric converter. VK1OD.net (offline).
• ———. 2007. Measuring system G/T ratio using Sun noise. VK1OD.net (offline).ITU-R. 2000. Recommendation ITU-R S.733-2 (2000) Determination of the G/T ratio for earth stations operating in the fixed-satellite service .
Designing high performance VHF/UHF receive systems – Part 2
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https://docs.micetoolkit.com/nodes.mask.morphology.closing.html
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# Closing
Class: NodeMaskClosing
Apply the morphological closing operation on a binary mask. The morphological closing of a binary mask $$I$$ is defined as the erosion of the silation of the mask: $$\textrm{Closing}\left(I\right) = \textrm{Erosion}\left(\textrm{Dilation}\left(I\right)\right)$$.
This filter removes small background structures such as holes in the mask. The size of the affected structures is controlled by the shape and size of the kernel.
## Inputs
#### Mask
A binary mask.
Type: Image4DBool, Required, Single
## Outputs
#### Out
A binary mask with the same spatial properties as the input mask.
Type: Image4DBool
## Settings
#### Kernel Selection
The shape of the structuring element.
Values: Annulus, Ball, Box, Cross
#### Radius X Integer
The radius of the kernel in the X direction, specified in voxels.
#### Radius Y Integer
The radius of the kernel in the Y direction, specified in voxels.
#### Radius Z Integer
The radius of the kernel in the Z direction, specified in voxels.
#### Safe Border Boolean
A safe border is added to input image to avoid borders effects. It is removed after the closing operation is done.
Keywords:
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https://eprint.iacr.org/2007/083
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### Public Key Encryption Which is Simultaneously a Locally-Decodable Error-Correcting Code
Brett Hemenway and Rafail Ostrovsky
##### Abstract
In this paper, we introduce the notion of a Public-Key Encryption Scheme that is also a Locally-Decodable Error-Correcting Code (PKLDC). In essence, this is a protocol that is semantically-secure in the standard sense, but possesses the additional property that it is a binary error-correcting locally-decodable code against any polynomial-time Adversary. That is, we allow a polynomial-time Adversary to read the entire ciphertext, perform any polynomial-time computation and change an arbitrary (i.e. adversarially chosen) constant fraction of {\em all} bits of the ciphertext. The goal of the Adversary is to cause error in decoding any bit of the plaintext. Nevertheless, the decoding algorithm can decode {\bf all} bits of the plaintext (given the corrupted ciphertext) while making a mistake on \emph{any} bit of the plaintext with only a negligible in $k$ error probability. In addition, the decoding algorithm has a {\bf Local Decodability} property. That is, given a corrupted ciphertext of $E(x)$ the decoding algorithm, for any $1 \le i \le n$, can recover the $i$'th bit of the plaintext $x$ with overwhelming probability reading a sublinear (in $|x|$) number of bits of the corrupted ciphertext and performing computation polynomial in the security parameter $k$. We present a general reduction from any semantically-secure encryption protocol and any computational Private Information Retrieval (PIR) protocol to a PKLDC. In particular, since it was shown that homomorphic encryption implies PIR, we give a general reduction from any semantically-secure homomorphic encryption protocol to a PKLDC. Applying our construction to the best known PIR protocol (that of Gentry and Ramzan), we obtain a PKLDC, which for messages of size $n$ and security parameter $k$ achieves ciphertexts of size $\O(n)$, public key of size $\O(n+k)$, and locality of size $\O(k^2)$. This means that for messages of length $n = \omega(k^{2+\epsilon})$, we can decode bit of the plaintext from a corrupted ciphertext while doing computation sublinear in $n$. We emphasize that this protocol achieves codewords that are only a \emph{constant} times larger than the underlying plaintext, while the best known locally-decodable codes (due to Yekhanin) have codewords that are only slightly subexponential in the length of the plaintext. In addition, we believe that the tools and techniques developed in this paper will be of independent interest in other settings as well.
Note: Applied construction in a more general setting.
Available format(s)
Publication info
Published elsewhere. A preliminary version of this work appeared in CRYPTO 2008
Keywords
Public Key CryptographyLocally Decodable CodesError Correcting CodesBounded Channel ModelChinese Remainder TheoremPrivate Information Retrieval
Contact author(s)
bhemen @ umich edu
History
2012-03-22: last of 4 revisions
See all versions
Short URL
https://ia.cr/2007/083
CC BY
BibTeX
@misc{cryptoeprint:2007/083,
author = {Brett Hemenway and Rafail Ostrovsky},
title = {Public Key Encryption Which is Simultaneously a Locally-Decodable Error-Correcting Code},
howpublished = {Cryptology ePrint Archive, Paper 2007/083},
year = {2007},
note = {\url{https://eprint.iacr.org/2007/083}},
url = {https://eprint.iacr.org/2007/083}
}
Note: In order to protect the privacy of readers, eprint.iacr.org does not use cookies or embedded third party content.
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http://clay6.com/qa/11643/an-engine-of-weight-6-5-metric-ton-is-going-up-an-incline-of-large-frac-at-
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Browse Questions
# An engine of weight 6.5 metric ton is going up an incline of $\large\frac{5}{13}$ at the rate of $9\; km/hr$ .The power of engine , if co-efficient of friction is $\large\frac{1}{12}$ is
$(a)\;83.5\;KW \quad (b)\;97.5\;KW \quad (c)\;60.5\;KW \quad (d)\;73.5\;KW$
$\sin \theta=\large\frac{5}{13}$
$\cos \theta=\sqrt {1-\sin ^ \theta}$
$\qquad= \sqrt {1-\bigg(\large\frac{5}{13}\bigg)^2}$
$\qquad=\large\frac{12}{13}$
Force against which the engine has to work
$F=mg \sin \theta+\mu mg \cos \theta$
$\quad=6500 \times 9.8 \bigg[\large\frac{5}{13}+\frac{1}{12} \times \frac{12}{13}\bigg]$
$\quad=29400 \;N$
Engine power $=Fv$
$\quad=29400 \times 2.5 \qquad 9km/hr=2.5 m/s$
$\quad=73500 \;W$
$\quad=73.5 KW$
Hence d is the correct answer.
edited Feb 10, 2014 by meena.p
+1 vote
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http://gmatclub.com/blog/2012/09/gmat-question-of-the-day-sept-27-algebra-and-sentence-correction/
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# GMAT Question of the Day (Sept 27): Algebra and Sentence Correction
- Sep 27, 02:00 AM Comments [0]
Math (DS)
Is $x > y^2$ ?
1. $x > y + 5$
2. $x^2 - y^2 = 0$
Question Discussion & Explanation
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Verbal (SC)
Of the twin supernovas, the most recently discovered is the largest, but it is the small one that has irrevocably altered astronomers’ ideas about the origins of the universe.
(A) the most recently discovered is the largest, but it is the small one
(B) the one most recently discovered is the largest, but it is the small one
(C) the most recently discovered is larger, but it is the smaller
(D) the more recently discovered one is the large one but the small one
(E) the more recently discovered is the larger, but it is the smaller one
Question Discussion & Explanation
Like these questions? Get the GMAT Club question collection: online at GMAT Club OR on your Kindle OR on your iPhone/iPad
Browse all GMAT Questions of the Day
Subscribe to GMAT Question of the Day: E-mail | RSS
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https://physics.stackexchange.com/users/146039/chemomechanics?tab=tags
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Chemomechanics
# 117 Tags
191 thermodynamics × 65 30 collision 14 classical-mechanics × 8 7 thermal-conductivity × 4 157 newtonian-mechanics × 13 30 conservation-laws 13 approximations × 2 7 potential × 2 108 forces × 4 30 momentum 12 evaporation × 6 7 water × 2 107 kinematics × 2 28 pressure × 6 12 molecules × 2 7 atomic-physics × 2 105 velocity 27 temperature × 15 11 electrical-resistance × 7 7 crystals 105 acceleration 26 physical-chemistry × 5 10 solid-mechanics × 11 6 fluid-dynamics × 4 86 entropy × 14 21 metals × 3 9 homework-and-exercises × 7 6 experimental-physics × 4 67 energy × 6 20 chemical-potential × 2 9 fluid-statics × 4 5 tensor-calculus × 3 60 sun 19 soft-question 9 heat-conduction × 3 5 electric-circuits × 3 47 elasticity × 18 18 spring × 6 9 condensed-matter 5 quantum-mechanics 39 statistical-mechanics × 7 18 solid-state-physics × 2 8 diffusion × 4 4 continuum-mechanics × 3 34 material-science × 15 15 density × 4 8 everyday-life × 3 4 vibrations × 2 31 estimation × 2 15 phase-transition × 3 7 stress-strain × 9 4 stress-energy-momentum-tensor × 2
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|
https://cstheory.stackexchange.com/questions/10594/whats-the-difference-between-adts-gadts-and-inductive-types
|
# What's the difference between ADTs, GADTs, and inductive types?
Might anyone be able to explain the difference between:
• Algebraic Datatypes (which I am fairly familiar with)
• Generalized Algebraic Datatypes (what makes them generalized?)
• Inductive Types (e.g. Coq)
(Especially inductive types.) Thank you.
Algebraic data types let you define types recursively. Concretely, suppose we have the datatype
$$\mathsf{data\;list = Nil \;\;|\;\; Cons\;of\;\mathbb{N} \times list}$$
What this means is that $\mathsf{list}$ is the smallest set generated by the $\mathsf{Nil}$ and $\mathsf{Cons}$ operators. We can formalize this by defining the operator $F(X)$
$$F(X) == \{ \mathsf{Nil} \} \cup \{ \mathsf{Cons}(n, x) \;|\; n \in \mathbb{N} \land x \in X \}$$
and then defining $\mathsf{list}$ as
$$\mathsf{list} = \bigcup_{i \in \mathbb{N}} F^i(\emptyset)$$
A generalized ADT is what we get when define a type operator recursively. For example, we might define the following type constructor:
$$\mathsf{bush}\;a = \mathsf{Leaf\;of\;}a \;\;|\;\; \mathsf{Nest\;of\;bush}(a \times a)$$
This type means that an element of $\mathsf{bush\;}a$ is a tuple of $a$s of length $2^n$ for some $n$, since each time we go into the $\mathsf{Nest}$ constructor the type argument is paired with itself. So we can define the operator we want to take a fixed point of as:
$$F(R) = \lambda X.\; \{ \mathsf{Leaf}(x) \;|\; x \in X\} \cup \{ \mathsf{Nest}(v) \;|\; v \in R(X) \}$$
An inductive type in Coq is essentially a GADT, where the indexes of the type operator are not restricted to other types (as in, for example, Haskell), but can also be indexed by values of the type theory. This lets you give types for length-indexed lists, and so on.
• Thank you. Wouldn't that just mean, however, that "inductive type" in completely synonymous with "dependent type"? – ninjagecko Mar 8 '12 at 16:27
• @Neel: I've never seen types like bush called GADTs. I have seen them called nested or non-regular types. – jbapple Mar 8 '12 at 16:38
• Nested types are a special case of GADTs. The critical feature of a GADT is simply that it is a recursive definition at higher kind. (Changes to the rhs is basically syntactic sugar for adding a type equality as a component of the constructor.) – Neel Krishnaswami Mar 8 '12 at 20:24
• @ninjagecko: "Inductive types" are types given semantics as the least fixed point of a constructor. Not all types can be described this way (functions cannot, and neither can infinite types such as streams). Dependent types describe types which permit program terms to occur in them (that is, types can "depend on" terms). Since Coq is a dependent type theory, the inductive types it lets you define are also dependent. But non-dependent type theories can support inductive types as well, and those inductive types won't be dependent. – Neel Krishnaswami Mar 8 '12 at 20:27
• @NeelKrishnaswami: Would you be so kind as to clarify your answer by enumerating the "first few smallest" elements of the types of bush a? In this example, is it Nest Leaf(a) Leaf(a) Leaf(a) Leaf(a), or Nest ((Nest Leaf(a) Leaf(a)) (Nest Leaf(a) Leaf(a))) as one example of the set? – ninjagecko Jul 11 '12 at 16:24
Consider algebraic datatypes such as:
data List a = Nil | Cons a (List a)
The return types of each constructor in a datatype are all the same: Nil and Cons both return List a. If we allow the constructors to return different types, we have a GADT:
data Empty -- this is an empty data declaration; Empty has no constructors
data NonEmpty
data NullableList a t where
Vacant :: NullableList a Empty
Occupied :: a -> NullableList a b -> NullableList a NonEmpty
Occupied has the type a -> NullableList a b -> NullableList a NonEmpty, while Cons has the type a -> List a -> List a. It is important to note that NonEmpty is a type, not a term. Another example:
data Zero
data Succ n
data SizedList a t where
Alone :: SizedList a Zero
WithFriends :: a -> SizedList a n -> SizedList a (Succ n)
Inductive types in programming languages that have dependent types allow the return types of the constructors to depend on the values (not just the types) of the arguments.
Inductive Parity := Even | Odd.
Definition flipParity (x:Parity) : Parity :=
match x with
| Even => Odd
| Odd => Even
end.
Fixpoint getParity (x:nat) : Parity :=
match x with
| 0 => Even
| S n => flipParity (getParity n)
end.
(*
A ParityNatList (Some P) is a list in which each member
is a natural number with parity P.
*)
Inductive ParityNatList : option Parity -> Type :=
Nil : forall P, ParityNatList P
| Cons : forall (x:nat) (P:option Parity),
ParityNatList P -> ParityNatList
(match P, getParity x with
| Some Even, Even => Some Even
| Some Odd, Odd => Some Odd
| _, _ => None
end).
A side note: GHC has a mechanism for treating value constructors as type constructors. This is not the same as the dependent inductive types that Coq has, but it lessens the syntactic burden of GADTs somewhat, and it can lead to better error messages.
• Thank you. "Inductive types in programming languages that have dependent types" What then would an inductive type look like in a language with no dependent types, and can you have non-inductive (but GADT-like) dependent types? – ninjagecko Mar 8 '12 at 18:14
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|
https://mathoverflow.net/questions/199404/when-is-a-linear-combination-of-permutation-matrices-unitary
|
# When is a linear combination of permutation matrices unitary?
Question: Let $P_\pi$ denote the matrix representation of permutation $\pi$. Consider a linear combination of all $n \times n$ permutation matrices $$U := \sum_{\pi \in S_n} c_\pi P_\pi$$ where $c_\pi$ are arbitrary complex coefficients. When is the matrix $U$ unitary? It would be great to have a simple parametrization of all tuples of coefficients $(c_\pi : \pi \in S_n)$ for when this happens.
Example: In the $n = 2$ case there are only 2 permutations, so the matrix $U$ looks like this: $$U = \begin{pmatrix} c_0 & c_1 \\ c_1 & c_0\end{pmatrix}$$ where the constants $c_i$ must obey $$|c_0|^2 + |c_1|^2 = 1 \quad \text{and} \quad c_0 c_1^* + c_1 c_0^* = 0$$ for $U$ to be unitary. We can parametrize the solution of these equations as follows: $$c_0 = e^{i\varphi} \cos t \quad c_1 = e^{i\varphi} i \sin t$$ for any $\varphi \in [0,2 \pi)$ and $t \in [0,\pi/2]$. It would be nice to have something similar for general $n$. For example, I can write down the equations for $n = 3$ but I don't know any nice way to parametrize the solutions.
Note: The only reference on this topic I could find is Orthogonal matrices as linear combinations of permulation matrices.
• Linear combinations of permutation matrices are the same thing as constant line-sum matrices (that is, matrices where all the row sums and all the column sums are equal), so we can rephrase the question as, which unitary matrices are constant line-sum? Mar 8, 2015 at 22:06
I think this can be done(in principle) in general. The $n \times n$ permutation matrices span a $\mathbb{C}$-vector space of dimension $1 + (n-1)^{2}$ since the natural permutation representation of $S_{n}$ is the sum of the trivial representation and an irreducible representation of degree $n-1.$ It is necessary for $\sum_{\pi} c_{\pi} P_{\pi}$ to be unitary that $\sum_{\pi} c_{\pi} \in S^{1}$ (just consider the effect on the vector $v$ with every component $\frac{1}{\sqrt{n}}).$ The non-trivial irreducible character comes from the action of $S_{n}$ on $v^{\perp}$, and for the moment it isn't clear me how to give a concise description to characterize which linear combinations of permutation matrices act as a unitary transformation on $v^{\perp}.$ Note that this is not really an issue when $n =2.$ Later edit: Thanks to Sean Eberhard's comment, it becomes clear that the unitary matrices which are linear combinations of permutation matrices are precisely those unitary matrices which have the vector $v$ above as an eigenvector- any unitary matrix which has $v$ as an eigenvector necessarily leaves $v^{\perp}$ invariant, so any linear combination of permutation matrices both has $v$ has an eigenvector and leaves $v^{\perp}$ invariant. By a dimension count, the space of matrices which leave both span($v$)and $v^{\perp}$ invariant, which has dimension $1 + (n-1)^{2}$, is precisely the span of the permutation matrices. In conclusion, the unitary matrices which are linear combinations of permutation matrices are precisely the unitary matrices which have $v$ as an eigenvector.
• This argument also shows that every unitary transformation with $v$ as an eigenvector can be written as a linear combination of permutation matrices. Mar 8, 2015 at 22:48
• @SeanEberhard : Yes, thanks, I have incorporated your commment into my answer now. Mar 8, 2015 at 23:26
• More generally, suppose $\rho : G \rightarrow\mathrm{GL}(V)$ is a unitary representation of a finite group $G$, and that $V = V_1\oplus\cdots\oplus V_r$ is a direct sum of non-isomorphic irreducible representations where $\dim V_i = n_i$. Then a block matrix with blocks of sizes $n_1,\ldots,n_r$ is a linear combination of $\rho(g)$ for $g \in G$, so a matrix $U$ is such a linear combination if and only if $U(V_i) \subseteq V_i$ for each $i$. In the special case when $U$ is unitary and $r=2$, it's enough that $U(V_1) \subseteq V_1$, since then $U(V_2)=U(V_1^\perp) = U(V_1)^\perp=V_1^\perp=V_2$. Mar 9, 2015 at 13:33
|
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|
http://nuit-blanche.blogspot.com/2011_06_01_archive.html
|
## Thursday, June 30, 2011
### ICASSP 2011 videos
Petros boufounos let us know on the twitter that the ICASSP 2011 videos of the talks given there are out on this site. Enjoy!
### The Generalized Approximate Message Passing (GAMP) MATLAB package
Jort Gemmeke continues on providing us some information from SPARS11. Here is the latest refering to the last post about an implementation of the Approximate Message Passing (AMP). There is another, probably more sturdy and supported instance, the
Oops, missed this one somehow. Referred to in Volkan's oral presentation today.
http://gampmatlab.sourceforge.net
Jort
From the Gamp wiki:
Overview: Generalized Approximate Message Passing (GAMP) is an approximate, but computationally efficient method for estimation problems withlinear mixing. In the linear mixing problem an unknown vector, $\mathbf{x}$, with independent components, is first passed through linear transform $\mathbf{z}=\mathbf{A}\mathbf{x}$ and then observed through a general probabilistic, componentwise measurement channel to yield a measurement vector $\mathbf{y}$. The problem is to estimate $\mathbf{x}$ and $\mathbf{z}$ from $\mathbf{y}$ and $\mathbf{A}$. This problem arises in a range of applications including compressed sensing.
Optimal solutions to linear mixing estimation problems are, in general, computationally intractable as the complexity of most brute force algorithms grows exponentially in the dimension of the vector $\mathbf{x}$. GAMP approximately performs the estimation through a Gaussian approximation of loopy belief propagation that reduces the vector-valued estimation problem to a sequence of scalar estimation problems on the components of the vectors $\mathbf{x}$ and $\mathbf{z}$.
This project is intended to develop the theory and applications of GAMP. We also provide open source MATLAB software for others who would like to experiment with the algorithm.
The contributors of this fine package include:
• Jason Parker, Ohio State
Thanks Jort.
### Approximate Message Passing (AMP) Code for Compressive Sensing.
Jort Gemmeke sent me the following:
Hi Igor,
David Donoho had a nice plenary here at SPARS2011 about approximate message passing for CS. After a bit of googling the subject, I stumbled over a matlab solver. Although its a very simple algorithm, still nice that someone implemented it already...you can find it here:
http://people.epfl.ch/ulugbek.kamilov
Maybe something for your big picture pages? Unless I didn't look well enough, I didnt see it there.
Cheers,
Jort
Jort is right, it is not there. Ulugbek Kamilov did make available his code featuring the Approximate Message Passing (AMP) code and I will feature it soon in the big pictureUlugbek Kamilov's master's Thesis is Optimal Quantization for Sparse Reconstruction with Relaxed Belief Propagation. The abstract of the thesis reads:
Compressive sensing theory has demonstrated that sparse signals can be recovered from a small number of random linear measurements. However, for practical purposes, like storage, transmission, or processing with modern digital equipment, continuous-valued compressive sensing measurements need to be quantized. In this thesis we examine the topic of optimal quantization of compressive sensing measurements under reconstruction with messagepassing algorithms by following the work on generalization of relaxed belief propagation (BP) for arbitrary measurement channels. Relaxed BP is an iterative reconstruction algorithm proposed for the task of estimation from random linear measurements. It was inspired by the traditional belief propagation algorithm widely used in decoding of low-density parity-check (LDPC) codes. One of the aspects that makes relaxed belief propagation so appealing is the state evolution framework, which predicts asymptotic error behavior of the algorithm. We utilize the predictive capability of the framework to design mean-square optimal scalar quantizers under relaxed BP signal reconstruction. We demonstrate that error performance of the reconstruction can be significantly improved by using state evolution optimized quantizers, compared to quantizers obtained via traditional design schemes. We finally propose relaxed BP as a practical algorithm for reconstruction from measurements digitized with binned quantizers, which further improve error performance of the reconstruction.
The attendant code for AMP and phase transition related computation is here. I just tried and compared it with SL0, a fast code on its own but relying on finding the SVD of a potentially large matrix and the results are indeed very impressive for a 1-d signal of size 100,000. The code I used:
clear
% Number of iterations of the algorithm
T = 1000;
% Stopping criterion (tolerance for successfull decoding)
tol = 1e-4;
m = 200;
k = 2;
N = 100000;
A = (1/sqrt(m)) .* randn(m, N);
% Sparse signal (with uniform distribution of non-zeros)
x = [sign(rand(k,1) - 0.5); zeros(N-k,1)];
x = x(randperm(N));
% Generate Measurements
y = A*x;
tstart = tic;
% Recover x using AMP
x1 = reconstructAmp(A, y, T, tol);
t_elapsed_AMP = toc(tstart)
sigma_min = 0.00004;
sdf=0.95;
tstart = tic;
x2= SL0(A, y, sigma_min,sdf);
t_elapsed_SL0 = toc(tstart)
figure(1)
plot(x1,'*')
figure(2)
plot(x2,'o')
t_elapsed_AMP =
3.2762
t_elapsed_SL0 =
172.2139
Thanks Jort.
## Wednesday, June 29, 2011
### Multicore LASSO
Danny Bickson let me know the following about a recent blog entry:
Today we released very efficient multicore code for computing LASSO / sprase logistic regression, following our ICML paper. The code is called via a matlab wrapper.
Let us note the paper uses a battery of tests coming from compressive sensing. Thanks Danny! The project's page is here.
## Tuesday, June 28, 2011
### Open Problems in Data Streams, Property Testing, and Related Topics
I just received an email and it's for you!
Hi Igor,
.....We were wondering if we could ask you for a favor. As you know, there was a workshop on sublinear algorithms organized in Bertinoro about a month ago. During the workshop we came up with a list of open problems in the area. The list is here:
and the relevant blog article is here:
http://polylogblog.wordpress.com/2011/06/14/open-problems-the-bertinoro-and-kanpur-lists/
We could certainly use insights and help from other (related) fields to solve the problems. Would it be possible for you to post the link on your blog ? This would help reaching out.
Thanks!
Thanks guys! Reading through the question list, there are indeed numerous questions related in some shape or another to Compressive sensing. Check it out and RT on the Twitter.
Credit: NASA/JPL/Space Science InstituteN00173198.jpg was taken on June 25, 2011 and received on Earth June 25, 2011. The camera was pointing toward TITAN at approximately 2,239,177 kilometers away, and the image was taken using the CL1 and CB3 filters.
## Monday, June 27, 2011
### Jim Gray's Search
Joe Hellerstein has a blog entry on his recent CACM paper on Jim Gray's search. Other entries related to this search can be found here.
### Spring-Summer School on Random matrices - Stochastic geometry - Compressed sensing Presentations
The organizers of the Spring-Summer School on Random matrices - Stochastic geometry - Compressed sensing at IHP last week, have made available the slides of their two speakers:
Thanks Djalil Chafaï, Alain Pajor, Alexandre Tsybakov and Christiane Lafargue.
## Sunday, June 26, 2011
### SPARS11
Evidently, if you are at SPARS11 and want to report on the meeting, you are welcome to send Nuit Blanche your blurb. You can also use the #spars11 tag on the Twitter. In the meantime, you may want to check the fantastic book of abstracts
Lots of good times to be had in Edinburgh!
## Friday, June 24, 2011
### Compressive Sensing Literature for the Week-End.
Here are three CS papers for the weekend and an intriguing paper on BCI utilization with no calibration period. Enjoy!
Sub-Nyquist Sampling: Bridging Theory and Practice by Moshe Mishali, Yonina Eldar. The abstract reads:
Sampling theory encompasses all aspects related to the conversion of continuous-time signals to discrete streams of numbers. The famous Shannon-Nyquist theorem has become a landmark in the development of digital signal processing. In modern applications, an increasingly number of functions is being pushed forward to sophisticated software algorithms, leaving only those delicate finely-tuned tasks for the circuit level.
In this paper, we review sampling strategies which target reduction of the ADC rate below Nyquist. Our survey covers classic works from the early 50's of the previous century through recent publications from the past several years. The prime focus is bridging theory and practice, that is to pinpoint the potential of sub-Nyquist strategies to emerge from the math to the hardware. In that spirit, we integrate contemporary theoretical viewpoints, which study signal modeling in a union of subspaces, together with a taste of practical aspects, namely how the avant-garde modalities boil down to concrete signal processing systems. Our hope is that this presentation style will attract the interest of both researchers and engineers in the hope of promoting the sub-Nyquist premise into practical applications, and encouraging further research into this exciting new frontier.
OFDM pilot allocation for sparse channel estimation by Pooria Pakrooh, Arash Amini, Farrokh Marvasti. The abstract reads:
In communication systems, efficient use of the spectrum is an indispensable concern. Recently the use of compressed sensing for the purpose of estimating Orthogonal Frequency Division Multiplexing (OFDM) sparse multipath channels has been proposed to decrease the transmitted overhead in form of the pilot subcarriers which are essential for channel estimation. In this paper, we investigate the problem of deterministic pilot allocation in OFDM systems. The method is based on minimizing the coherence of the submatrix of the unitary Discrete Fourier Transform (DFT) matrix associated with the pilot subcarriers. Unlike the usual case of equidistant pilot subcarriers, we show that non-uniform patterns based on cyclic difference sets are optimal. In cases where there are no difference sets, we perform a greedy search method for finding a suboptimal solution. We also investigate the performance of the recovery methods such as Orthogonal Matching Pursuit (OMP) and Iterative Method with Adaptive Thresholding (IMAT) for estimation of the channel taps.
Tight Measurement Bounds for Exact Recovery of Structured Sparse Signals by Nikhil Rao, Benjamin Recht, Robert Nowak. The abstract reads:
Standard compressive sensing results state that to exactly recover an s sparse signal in R^p, one requires O(s\cdotlog p) measurements. While this bound is extremely useful in practice, often real world signals are not only sparse, but also exhibit structure in the sparsity pattern. We focus on group-structured patterns in this paper. Under this model, groups of signal coefficients are active (or inactive) together. The groups are predefined, but the particular set of groups that are active (i.e., in the signal support) must be learned from measurements. We show that exploiting knowledge of groups can further reduce the number of measurements required for exact signal recovery, and derive near optimal bounds for the same. The number of measurements needed only depends on the number of groups under consideration, and not the particulars of the groups (e.g., compositions, sizes, extents, overlaps, etc.). The results are also shown to predict experimental performance quite well.
A Subject-Independent Brain-Computer Interface based on Smoothed, Second-Order Baselining by Boris Reuderink, Jason Farquhar, Mannes Poel, Anton Nijholt.
Image Credit: NASA/JPL/Space Science Institute
N00172964.jpg was taken on June 22, 2011 and received on Earth June 23, 2011. The camera was pointing toward TITAN at approximately 817,420 kilometers away, and the image was taken using the CL1 and CB3 filters. This image has not been validated or calibrated.
## Thursday, June 23, 2011
### What's Next ?
Here is a short story of a venture capitalist talking about The Making of Lytro, a company that wants to sell light field cameras. The main selling aspect is take a picture now and worry later. We know of other technologies that can even provide low cost modulation but it does not seem to have caught the imaging scene by storm.
In the imaging world, I know of two companies that are developing something based on compressive sensing .i.e. use a different types of modulation than the one (refractive) developed by Lytro to investigate niche markets:
Inview in particular is developing products based on technology developed at Rice where the modulation is performed with a DMD as in the single pixel camera. Works seems to be in the Infrared region where pixels are expensive. Applied Quantum Technologies seems to be focused on coded masks as developed in the CASSI system by the folks at Duke. That technology is showing interesting applications in hyperspectral imaging. Are there any larger markets that could be served with these compressive imaging technologies ?
That brings me to the next question: when I take a shot, do I generally worry about refocusing ? what do you worry about ?
On a totally different subject, Danny Bickson with his graphlab algorithm is making it to 4th place on the KDD Yahoo! contest. For those of you interested in using GraphLab (a way of performing parallel computation on many different cores), here is a small tutorial on Jacobi method in GraphLab. It would seem that one could think of using this technique for solving very large matrices when using SL0 for instance since the most expensive part of that algorithm is an SVD computation if I recall. Definitely something sparseman should consider if Google is interested in his Exacycle request
## Wednesday, June 22, 2011
### Convex Geometry, Stoichiometry and Combinatorial Chemistry
While on Twitter, I came across this arxiv entry on approaching chemistry through linear algebra: Convex Geometry and Stoichiometry by Jer-Chin (Luke) Chuang. The abstract reads:
We demonstrate the benefits of a convex geometric perspective for questions on chemical stoichiometry. We show that the balancing of chemical equations, the use of "mixtures" to explain multiple stoichiometry, and the half-reaction for balancing redox actions all yield nice convex geometric interpretations. We also relate some natural questions on reaction mechanisms with the enumeration of lattice points in polytopes. Lastly, it is known that a given reaction mechanism imposes linear constraints on observed stoichiometries. We consider the inverse question of deducing reaction mechanism consistent with a given set of linear stoichiometric restrictions.
I see many things here that I did not appreciate before about chemistry. With the lens of compressive sensing, I see underdetermined systems, larger than rank one nullspaces ( a good thing when looking for sparsest solutions), polytopes and convex geometry. And then there is this issue of combinatorial chemistry where I wonder aloud whether if my initial dislike of chemistry is not grounded in rules and conventions that maybe are the sparsest solution of a combinatorial problem. Maybe it's time to talk to a chemist ?
### This Week in Compressive Sensing
Namrata Vaswani just let me know of her recent paper and code:
This work studies the recursive robust principal components' analysis (PCA) problem. Here, "robust" refers to robustness to both independent and correlated sparse outliers, although we focus on the latter. A key application where this problem occurs is in video surveillance where the goal is to separate a slowly changing background from moving foreground objects on-the-fly. The background sequence is well modeled as lying in a low dimensional subspace, that can gradually change over time, while the moving foreground objects constitute the correlated sparse outliers. In this and many other applications, the foreground is an outlier for PCA but is actually the "signal of interest" for the application; where as the background is the corruption or noise. Thus our problem can also be interpreted as one of recursively recovering a time sequence of sparse signals in the presence of large but spatially correlated noise.
This work has two key contributions. First, we provide a new way of looking at this problem and show how a key part of our solution strategy involves solving a noisy compressive sensing (CS) problem. Second, we show how we can utilize the correlation of the outliers to our advantage in order to even deal with very large support sized outliers. The main idea is as follows. The correlation model applied to the previous support estimate helps predict the current support. This prediction serves as "partial support knowledge" for solving the modified-CS problem instead of CS. The support estimate of the modified-CS reconstruction is, in turn, used to update the correlation model parameters using a Kalman filter (or any adaptive filter). We call the resulting approach "support-predicted modified-CS".
The Recursive Projected Compressive Sensing code is available and hosted on this website. The main idea of the approach reads:
Main idea:
This work studies the recursive robust principal components' analysis (PCA) problem. Here, robust" refers to robustness to both independent and correlated sparse outliers, although we focus on the latter. A key application where this problem occurs is in video surveillance where the goal is to separate a slowly changing background from moving foreground objects on-the-fly. The background sequence is well modeled as lying in a low dimensional subspace, that can gradually change over time, while the moving foreground objects constitute the correlated sparse outliers. In this and many other applications, the foreground is an outlier for PCA but is actually the signal of interest" for the application; where as the background is the corruption or noise. Thus our problem can also be interpreted as one of recursively recovering a time sequence of sparse signals in the presence of large but spatially correlated noise.
This work has two key contributions. First, we provide a new way of looking at this problem and show how a key part of our solution strategy involves solving a noisy compressive sensing (CS) problem. Second, we show how we can utilize the correlation of the outliers to our advantage in order to even deal with very large support sized outliers. The main idea is as follows. The correlation model applied to the previous support estimate helps predict the current support. This prediction serves as partial support knowledge" for solving the modified-CS problem instead of CS. The support estimate of the modified-CS reconstruction is, in turn, used to update the correlation model parameters using a Kalman filter (or any adaptive filter). We call the resulting approach support-predicted modified-CS".
From the paper, I note the following excerpt:
In this work we misuse terminology a little and use “compressive sensing” or “CS” to refer to the ℓ1 minimization problem.
Thanks you for acknowledging this. While we are on the L1 regularization subject, did you know that the Youtube Video editor enabled Auto-Directed Video Stabilization with Robust L1 Optimal Camera Paths, well you do now. You can learn more here on the Google Research blog and test it here.
Focusing back on comrpressive sensing, we have the following papers:
Efficient Incremental Analysis of On-Chip Power Grid via Sparse Approximation by Pei Sun and Xin Li, Ming-Yuan Ting. The abstract reads:
In this paper, a new sparse approximation technique is proposed for incremental power grid analysis. Our proposed method is motivated by the observation that when a power grid network is locally updated during circuit design, its response changes locally and, hence, the incremental “change” of the power grid voltage is almost zero at many internal nodes, resulting in a unique sparse pattern. An efficient Orthogonal Matching Pursuit (OMP) algorithm is adopted to solve the proposed sparse approximation problem. In addition, several numerical techniques are proposed to improve the numerical stability of the proposed solver, while simultaneously maintaining its high efficiency. Several industrial circuit examples demonstrate that when applied to incremental power grid analysis, our proposed approach achieves up to 130 runtime speed-up over the traditional Algebraic Multi-Grid (AMG) method, without surrendering any accuracy.
Matrix Co-Factorization on Compressed Sensing by Jiho Yoo and Seungjin Choi. The abstract reads:
In this paper we address the problem of matrix factorization on compressively-sampled measurements which are obtained by random projections. While this approach improves the scalability of matrix factorization, its performance is not satisfactory. We present a matrix co-factorization method where compressed measurements and a small number of uncompressed measurements are jointly decomposed, sharing a factor matrix. We evaluate the performance of three matrix factorization methods in terms of Cram´er-Rao bounds, including: (1) matrix factorization on uncompressed data (MF); (2) matrix factorization on compressed data (CSMF); (3) matrix co-factorization on compressed and uncompressed data (CS-MCF). Numerical experiments demonstrate that CS-MCF improves the performance of CS-MF, emphasizing the useful behavior of exploiting side information (a small number of uncompressed measurements).
Ramsey theory reveals the conditions when sparse coding on subsampled data is unique by Christopher J. Hillar, Friedrich T. Sommer. The abstract reads:
Sparse coding or dictionary learning has been widely used to reveal the sparse underlying structure of many kinds of sensory data. A related advance in signal processing is compressed sensing, a theory explaining how sparse data can be subsampled below the Nyquist-Shannon limit and then efficiently recovered from these subsamples. Here we study whether the conditions for recovery in compressed sensing are sufficient for dictionary learning to discover the original sparse causes of subsampled data. Using combinatorial Ramsey theory, we completely characterize when the learned dictionary matrix and sparse representations of subsampled data are unique (up to the natural equivalences of permutation and scaling). Surprisingly, uniqueness is shown to hold without any assumptions on the learned dictionaries or inferred sparse codes. Our result has implications for the learning of overcomplete dictionaries from subsampled data and has potential applications in data analysis and neuroscience. For instance, it identifies sparse coding as a possible learning mechanism for establishing lossless communication through severe bottlenecks, which might explain how different brain regions communicate through axonal fiber projections.
In this paper, we consider the problem of compressed sensing where the goal is to recover almost all the sparse vectors using a small number of fixed linear measurements. For this problem, we propose a novel partial hard-thresholding operator that leads to a general family of iterative algorithms. While one extreme of the family yields well known hard thresholding algorithms like ITI (Iterative Thresholding with Inversion) and HTP (Hard Thresholding Pursuit), the other end of the spectrum leads to a novel algorithm that we call Orthogonal Matching Pursuit with Replacement (OMPR). OMPR, like the classic greedy algorithm OMP, adds exactly one coordinate to the support at each iteration, based on the correlation with the current residual. However, unlike OMP, OMPR also removes one coordinate from the support. This simple change allows us to prove that OMPR has the best known guarantees for sparse recovery in terms of the Restricted Isometry Property (a condition on the measurement matrix). In contrast, OMP is known to have very weak performance guarantees under RIP. Given its simple structure, we are able to extend OMPR using locality sensitive hashing to get OMPR-Hash, the first provably sub-linear (in dimensionality) algorithm for sparse recovery. Our proof techniques are novel and flexible enough to also permit the tightest known analysis of popular iterative algorithms such as CoSaMP and Subspace Pursuit. We provide experimental results on large problems providing recovery for vectors of size up to million dimensions. We demonstrate that for large-scale problems our proposed methods are more robust and faster than existing methods.
Total Variation Minimization Based Compressive Wideband Spectrum Sensing for Cognitive Radios by Yipeng Liu, Qun Wan. The abstract reads:
Wideband spectrum sensing is a critical component of a functioning cognitive radio system. Its major challenge is the too high sampling rate requirement. Compressive sensing (CS) promises to be able to deal with it. Nearly all the current CS based compressive wideband spectrum sensing methods exploit only the frequency sparsity to perform. Motivated by the achievement of a fast and robust detection of the wideband spectrum change, total variation mnimization is incorporated to exploit the temporal and frequency structure information to enhance the sparse level. As a sparser vector is obtained, the spectrum sensing period would be shorten and sensing accuracy would be enhanced. Both theoretical evaluation and numerical experiments can demonstrate the performance improvement.
Efficient Two-Stage Group Testing Algorithms for DNA Screening by Michael Huber. The abstract reads:
Group testing algorithms are very useful tools for DNA library screening. Building on recent work by Levenshtein (2003) and Tonchev (2008), we construct in this paper new infinite classes of combinatorial structures, the existence of which are essential for attaining the minimum number of individual tests at the second stage of a two-stage disjunctive testing algorithm.
Sparse spike train deconvolution is a classical inverse problem which gave rise to many deterministic and stochastic algorithms since the mid-80’s. In the past decade, sparse approximation has been an intensive field of research, leading to the development of a number of algorithms including greedy strategies and convex relaxation methods. Spike train deconvolution can be seen as a specific sparse approximation problem, where the observation matrix contains highly correlated columns and where the focus is set on the exact recovery of the spike locations. The objective of this paper is to evaluate the performance of algorithms proposed in both fields in terms of detection statistics, with Monte-Carlo simulations of spike deconvolution problems.
Image Credit: NASA/JPL/Space Science Institute, N00172883.jpg was taken on June 18, 2011 and received on Earth June 20, 2011. The camera was pointing toward HELENE, and the image was taken using the CL1 and CL2 filters.
## Tuesday, June 21, 2011
### Two Solvers: R1Magic and YALL1 Group
I just came across a CS solver written in R as shown in this presentation: Compressive Sampling with R: A Tutorial by Mehmet Suzen. The R1Magic package is here. A reference manual is here.
YALL1 now include a group sparsity solving capability. Let us look at what he can do. From the webpage:
YALL1 package now includes:
• YALL1 Basic
• , a solver for sparse reconstruction: Version 1.3, Apr 07, 2011.
• YALL1 Group
• , a solver for group/joint sparse reconstruction: Version 1.0, June 09, 2011. Wiki
YALL1 Basic
solves the following L1-minimization problems:
(BP) min ||Wx||w,1 s.t. Ax = b
(L1/L1) min ||Wx||w,1 + (1/ν)||Ax - b||1 (L1/L2) min ||Wx||w,1 + (1/2ρ)||Ax - b||22 (L1/L2con) min ||Wx||w,1, s.t. ||Ax - b||2 <= δ
(BP+) min ||x||w,1 s.t. Ax = b and x >= 0
(L1/L1+) min ||x||w,1 + (1/ν)||Ax - b||1 s.t. x >= 0
(L1/L2+) min ||x||w,1 + (1/2ρ)||Ax - b||22 s.t. x >= 0
(L1/L2con+) min ||x||w,1, s.t. ||Ax - b||2 <= δ, x >= 0
where
• A
• is an m-by-n matrix with m << n,
• the solution x (or its representation Wx) is supposed to be (approximately) sparse,
• the data and solution can be real or complex, (If complex, then no non-negativity constraint is allowed)
• a unitary sparsifying basis W is optional,
• the 1-norm can be optionally weighted by a nonnegative vector w.
Go to discussions and Q&As.
Supported Features
• Multiple types of A
• explicit matrix
• ensembles of fast transforms such as FFT, DCT, wavelets
• Both real and complex data
• Both sparse and compressible signals
• Non-negative signals
YALL1 Group
The group sparsity code solves the following model
(GroupBP) min sumi wi ||x_gi||2 s.t. Ax = b
where g1, g2, … are groups of coordinates and w1,w2, … are their weights.
Joint sparsity is a special case of group sparsity for recovering X = [x1,x2, ..., xl] where the xi‘s share a common sparse support.
(JointBP) min sumi wi ||Xi,:||2 s.t. AX = B.
Supported Features
• Multiple types of A
• explicit matrix
• ensembles of fast transforms such as FFT, DCT, wavelets
• general function handle
• Groups can overlap
• The union of groups does not need to cover all coordinates
• Easy to modify for the support of complex numbers and your signals
Contributors
Yin Zhang*, Wei Deng, Junfeng Yang, and Wotao Yin.
* The original author of YALL1 (beta 1 – 6).
Tech report
YALL1 Basic: Alternating Direction Algorithms for L1 Problems in Compressive Sensing, Rice CAAM Report TR09-37, 2009.
YALL1 Group/Joint Sparsity: Group Sparse Optimization by Alternating Direction Method, Rice CAAM Report TR11-06, 2011.
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https://learnzillion.com/lesson_plans/2775-1-understand-that-we-can-add-more-than-two-numbers-c
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Lesson plan
# 1. Understand that we can add more than two numbers (C)
teaches Common Core State Standards 1.OA.A.2 http://corestandards.org/Math/Content/1/OA/A/2
teaches Common Core State Standards 1.OA.B.3 http://corestandards.org/Math/Content/1/OA/B/3
teaches Common Core State Standards MP7 http://corestandards.org/Math/Practice/MP7
## You have saved this lesson plan!
Here's where you can access your saved items.
Dismiss
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https://quics.umd.edu/research/publications?page=3&s=author&%3Bf%5Bag%5D=N&%3Bf%5Bauthor%5D=2093&o=asc&f%5Bauthor%5D=1688
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# Publications
Export 4 results:
[ Author] Title Type Year
Filters: Author is Yunseong Nam [Clear All Filters]
N
, Automated optimization of large quantum circuits with continuous parameters, npj:Quantum Information, vol. 4, no. 23, 2018.
, Optimal length of decomposition sequences composed of imperfect gates, Quantum Information Processing, vol. 16, p. 123, 2017.
Y. Nam, Su, Y., and Maslov, D., Approximate Quantum Fourier Transform with O(nlog(n)) T gates, npj Quantum Information , vol. 6, no. 26, 2020.
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https://mathalino.com/blog/civil-engineering-board-exam-subjects
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# Civil Engineering Board Exam Subjects
• Mathematics inside the configured delimiters is rendered by MathJax. The default math delimiters are $$...$$ and $...$ for displayed mathematics, and $...$ and $...$ for in-line mathematics.
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https://www.physicsforums.com/threads/how-to-write-equations-for-salt-dissolving-in-water-ionizing.899013/
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# How to write equations for salt dissolving in water/ionizing
Tags:
1. Jan 2, 2017
### LegitSci
1. The problem statement, all variables and given/known data
Write separate equations for each potassium salt (KH2PO4) dissolving in water and for the ionization reaction of the weak acid anion that each of these salts contains.
2. Relevant equations
None
3. The attempt at a solution
I just needed to clarify when it dissolves in water do I include that in reaction or just do a dissociation of the ion? Furthermore, for ionization reaction of weak anion, it is H2PO4, so what does this mean?
2. Jan 3, 2017
### Staff: Mentor
There is no strict rule to the first step (and I would have no problems if the first step was omitted, but your instructor can have a different opinion).
H2PO4- can dissociate. Actually it can also hydrolyze. Both reactions have to be listed.
Draft saved Draft deleted
Similar Discussions: How to write equations for salt dissolving in water/ionizing
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http://mathhelpforum.com/calculus/15315-supremum-infimum.html
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# Math Help - supremum and infimum
1. ## supremum and infimum
I need help on how to prove this:
If x is an arbitrary real number, prove that there are integers m and n such that m < x < n.
Thank you
2. Originally Posted by PersaGell
I need help on how to prove this:
If x is an arbitrary real number, prove that there are integers m and n such that m < x < n.
Thank you
WLOG for any $x>0$ consider $k=1$. By the Archimedean Ordering on $\mathbb{R}$ there shall exist $n$ such that $n\cdot 1 > x$. Hence we can find $n>x$. That completes the second inequality.
For any $x>0$ consider $x-1$. I claim we can choose an integer $m$ such that $x-1\leq m .
Above we can find an integer $n>x$. Hence consider the interval $[-n,n]$. Define the set of integers $S=\{ k \in \mathbb{Z} | x-1 \leq k \leq n\}$. This is a finite non-empty set. So choose $m=\min S$. I leave it to you to prove that $m$ is the desired integer.
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https://zenodo.org/record/45541/export/json
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Conference paper Open Access
# A Neuro-Fuzzy System to Calculate a Journal Internationality Index
Perakakis, Pandelis; Taylor, Michael; Buela-Casal, Gualberto; Checa, Purificacion
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"description": "<p>Internationality as a concept is being applied ambiguously and erroneously, particularly in the world of academic journal publication where it is often used as a quality indicator. Although different qualitative criteria have been used by scientometrists in order to attempt a measure of internationality in various contexts, it is now clear that the literal definition of internationality is a minimal one while other proposed measures based on individual criteria fail to provide a complete and accurate assessment. As such, internationality remains to be defined2.</p>\n\n<p>Here, we present a holistic approach to the problem based on fuzzy logic. We surveyed, critically-assessed and pruned the set of internationality criteria in the context of academic publishing, selecting those that are semantically precise and amenable to <em>quantitative </em>measure. We have tested the ability of each criterion to measure internationality by applying them to four thematically-connected journals from the field of Health and Clinical Psychology, using descriptive</p>\n\n<p>statistics and the Gini Coefficient. The results of this case study revealed that, in the absence of a method of numerically weighting the criteria, any measurement of internationality remains ambiguous and incorrect.</p>\n\n<p>We propose that internationality is best represented by a neuro-fuzzy system of fuzzy sets of the weighted criteria linked by fuzzy rules in a multi-layer perceptron, whose output defuzzification gives a new measure – a <em>Journal Internationality Index </em>akin to the Impact Factor for citations. Viewing internationality in this way as an approximated fuzzy function means a quantitative measure can be found while keeping intact its semantic rule origins and meaning. </p>",
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"url": "http://cedi2005.ugr.es/2005/index.php",
"dates": "13-16 September 2005",
"title": "Congreso Espa\u00f1ol de Informatica"
},
"access_right": "open",
"resource_type": {
"subtype": "conferencepaper",
"type": "publication",
"title": "Conference paper"
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59
12
views
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|
http://slh.alljournals.cn/search_by_author.aspx?subject=mathematical_chemical&major=sx&field=author_name&encoding=utf-8&q=Magda+Peligrad
|
首页 | 本学科首页 官方微博 | 高级检索
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1.
Almost-Sure Results for a Class of Dependent Random Variables 总被引：17，自引：0，他引：17
The aim of this note is to establish almost-sure Marcinkiewicz-Zygmund type results for a class of random variables indexed by d + —the positive d-dimensional lattice points—and having maximal coefficient of correlation strictly smaller than 1. The class of applications include filters of certain Gaussian sequences and Markov processes. 相似文献
2.
The aim of this paper is to investigate the properties of the maximum of partial sums for a class of weakly dependent random variables which includes the instantaneous filters of a Gaussian sequence having a positive continuous spectral density. The results are used to obtain an invariance principle for strongly mixing sequences of random variables in the absence of stationarity or strong mixing rates. An additional condition is imposed to the coefficients of interlaced mixing. The results are applied to linear processes of strongly mixing sequences. 相似文献
3.
Summary In this note we estimate the rate of convergence in Marcinkiewicz-Zygmung strong law, for partial sumsS n of strong stationary mixing sequences of random variables. The results improve the corresponding ones obtained by Tze Leung Lai (1977) and Christian Hipp (1979). 相似文献
4.
The aim of this paper is to investigate the properties of the maximum of partial sums for a class of weakly dependent random variables which includes the instantaneous filters of a Gaussian sequence having a positive continuous spectral density. The results are used to obtain an invariance principle and the convergence of the moments in the central limit theorem.
5.
6.
7.
8.
The aim of this paper is to give a functional form for the central limit theorem obtained by Bradley for strong mxing sequences of random variables, under a certain assumption about the size of the maximal coefficients of correlations. The convergence of the moments of order 2 + δ in the central limit theorem for this class of random variables is also obtained. 相似文献
9.
The paper aims to establish a new sharp Burkholder-type maximal inequality in for a class of stationary sequences that includes martingale sequences, mixingales and other dependent structures. The case when the variables are bounded is also addressed, leading to an exponential inequality for a maximum of partial sums. As an application we present an invariance principle for partial sums of certain maps of Bernoulli shifts processes.
10.
In this note we investigate the coupling of a class of dependent sequences with an independent one having the same marginal distributions. This method is then used to prove that a uniform law of averages for this class holds if a similar law holds for the associated independent sequence. 相似文献
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http://umj.imath.kiev.ua/article/?lang=en&article=8493
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2018
Том 70
№ 12
# Some Approximation Properties of Szasz–Mirakyan–Bernstein Operators of the Chlodovsky Type
Abstract
We motivate a new sequence of positive linear operators by means of the Chlodovsky-type Szasz–Mirakyan–Bernstein operators and investigate some approximation properties of these operators in the space of continuous functions defined on the right semiaxis. We also find the order of this approximation by using the modulus of continuity and present the Voronovskaya-type theorem.
English version (Springer): Ukrainian Mathematical Journal 66 (2014), no. 6, pp 928-936.
Citation Example: Simsek E., Tunç E. Some Approximation Properties of Szasz–Mirakyan–Bernstein Operators of the Chlodovsky Type // Ukr. Mat. Zh. - 2014. - 66, № 6. - pp. 826–834.
Full text
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http://nl.mathworks.com/help/physmod/sps/powersys/ref/staticsynchronouscompensatorphasortype.html?nocookie=true
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Static Synchronous Compensator (Phasor Type)
Implement phasor model of three-phase static synchronous compensator
Library
FACTS/Power-Electronics Based FACTS
Description
The Static Synchronous Compensator (STATCOM) is a shunt device of the Flexible AC Transmission Systems (FACTS) family using power electronics to control power flow and improve transient stability on power grids [1]. The STATCOM regulates voltage at its terminal by controlling the amount of reactive power injected into or absorbed from the power system. When system voltage is low, the STATCOM generates reactive power (STATCOM capacitive). When system voltage is high, it absorbs reactive power (STATCOM inductive).
The variation of reactive power is performed by means of a Voltage-Sourced Converter (VSC) connected on the secondary side of a coupling transformer. The VSC uses forced-commutated power electronic devices (GTOs, IGBTs or IGCTs) to synthesize a voltage V2 from a DC voltage source. The principle of operation of the STATCOM is explained on the figure below showing the active and reactive power transfer between a source V1 and a source V2. In this figure, V1 represents the system voltage to be controlled and V2 is the voltage generated by the VSC.
Operating Principle of the STATCOM
P = (V1V2)sinδ / X , Q = V1(V1V2cosδ) / X
SymbolMeaning
V1Line to line voltage of source 1
V2Line to line voltage of source 2
XReactance of interconnection transformer and filters
δPhase angle of V1 with respect to V2
In steady state operation, the voltage V2 generated by the VSC is in phase with V1 (δ=0), so that only reactive power is flowing (P=0). If V2 is lower than V1, Q is flowing from V1 to V2 (STATCOM is absorbing reactive power). On the reverse, if V2 is higher than V1, Q is flowing from V2 to V1 (STATCOM is generating reactive power). The amount of reactive power is given by
Q = (V1(V1V2 )) / X.
A capacitor connected on the DC side of the VSC acts as a DC voltage source. In steady state the voltage V2 has to be phase shifted slightly behind V1 in order to compensate for transformer and VSC losses and to keep the capacitor charged. Two VSC technologies can be used for the VSC:
• VSC using GTO-based square-wave inverters and special interconnection transformers. Typically four three-level inverters are used to build a 48-step voltage waveform. Special interconnection transformers are used to neutralize harmonics contained in the square waves generated by individual inverters. In this type of VSC, the fundamental component of voltage V2 is proportional to the voltage Vdc. Therefore Vdc has to be varied for controlling the reactive power.
• VSC using IGBT-based PWM inverters. This type of inverter uses Pulse-Width Modulation (PWM) technique to synthesize a sinusoidal waveform from a DC voltage source with a typical chopping frequency of a few kilohertz. Harmonic voltages are cancelled by connecting filters at the AC side of the VSC. This type of VSC uses a fixed DC voltage Vdc. Voltage V2 is varied by changing the modulation index of the PWM modulator.
The STATCOM (Phasor Type) block models an IGBT-based STATCOM (fixed DC voltage). However, as details of the inverter and harmonics are not represented, it can be also used to model a GTO-based STATCOM in transient stability studies. A detailed model of a GTO-based STATCOM is provided in the FACTS example library (`power_statcom_gto48p` example).
The figure below shows a single-line diagram of the STATCOM and a simplified block diagram of its control system.
Single-line Diagram of a STATCOM and Its Control System Block Diagram
The control system consists of:
• A phase-locked loop (PLL) which synchronizes on the positive-sequence component of the three-phase primary voltage V1. The output of the PLL (angle Θ=ωt) is used to compute the direct-axis and quadrature-axis components of the AC three-phase voltage and currents (labeled as Vd, Vq or Id, Iq on the diagram).
• Measurement systems measuring the d and q components of AC positive-sequence voltage and currents to be controlled as well as the DC voltage Vdc.
• An outer regulation loop consisting of an AC voltage regulator and a DC voltage regulator. The output of the AC voltage regulator is the reference current Iqref for the current regulator (Iq = current in quadrature with voltage which controls reactive power flow). The output of the DC voltage regulator is the reference current Idref for the current regulator (Id = current in phase with voltage which controls active power flow).
• An inner current regulation loop consisting of a current regulator. The current regulator controls the magnitude and phase of the voltage generated by the PWM converter (V2d V2q) from the Idref and Iqref reference currents produced respectively by the DC voltage regulator and the AC voltage regulator (in voltage control mode). The current regulator is assisted by a feed forward type regulator which predicts the V2 voltage output (V2d V2q) from the V1 measurement (V1d V1q) and the transformer leakage reactance.
The STACOM block is a phasor model which does not include detailed representations of the power electronics. You must use it with the phasor simulation method, activated with the Powergui block. It can be used in three-phase power systems together with synchronous generators, motors, dynamic loads and other FACTS and Renewable Energy systems to perform transient stability studies and observe impact of the STATCOM on electromechanical oscillations and transmission capacity at fundamental frequency.
STATCOM V-I Characteristic
The STATCOM can be operated in two different modes:
• In voltage regulation mode (the voltage is regulated within limits as explained below)
• In var control mode (the STATCOM reactive power output is kept constant)
When the STATCOM is operated in voltage regulation mode, it implements the following V-I characteristic.
STATCOM V-I characteristic
As long as the reactive current stays within the minimum and minimum current values (-Imax, Imax) imposed by the converter rating, the voltage is regulated at the reference voltage Vref. However, a voltage droop is normally used (usually between 1% and 4% at maximum reactive power output), and the V-I characteristic has the slope indicated in the figure. In the voltage regulation mode, the V-I characteristic is described by the following equation:
V = Vref + Xs I
where
V Positive sequence voltage (pu) I Reactive current (pu/Pnom) (I > 0 indicates an inductive current) Xs Slope or droop reactance (pu/Pnom) Pnom Three-phase nominal power of the converter specified in the block dialog box
STATCOM vs SVC
The STATCOM performs the same function as the SVC. However at voltages lower than the normal voltage regulation range, the STATCOM can generate more reactive power than the SVC. This is due to the fact that the maximum capacitive power generated by a SVC is proportional to the square of the system voltage (constant susceptance) while the maximum capacitive power generated by a STATCOM decreases linearly with voltage (constant current). This ability to provide more capacitive reactive power during a fault is one important advantage of the STATCOM over the SVC. In addition, the STATCOM will normally exhibits a faster response than the SVC because with the VSC, the STATCOM has no delay associated with the thyristor firing (in the order of 4 ms for a SVC).
Dialog Box and Parameters
The STATCOM parameters are grouped in two categories: ```Power data``` and `Control parameters`. Use the Display listbox to select which group of parameters you want to visualize.
Power Tab
Nominal voltage and frequency
The nominal line-to-line voltage in Vrms and the nominal system frequency in hertz.
Converter rating
The nominal power of the converter in VA.
Converter impedance
The positive-sequence resistance and inductance of the converter, in pu based on the nominal power and voltage ratings. R and L represent the resistance and leakage inductance of the coupling transformer and the resistance and inductance of the series filtering inductors connected at the VSC output.
Converter initial current
The initial value of the positive-sequence current phasor (Magnitude in pu and Phase in degrees). If you know the initial value of the current corresponding to the STATCOM operating point you may specify it in order to start simulation in steady state. If you don't know this value, you can leave [0 0]. The system will reach steady-state after a short transient.
DC link nominal voltage
The nominal voltage of the DC link in volts.
DC link total equivalent capacitance
The total capacitance of the DC link in farads. This capacitance value is related to the STATCOM rating and to the DC link nominal voltage. The energy stored in the capacitance (in joules) divided by the STATCOM rating (in VA) is a time duration which is usually a fraction of a cycle at nominal frequency. For example, for the default parameters, (C=375 µF, Vdc=40 000 V, Snom=100 MVA) this ratio $\left(C\cdot {V}_{\text{dc}}^{2}/2\right)/{S}_{\text{nom}}$ is 3.0 ms, which represents 0.18 cycle for a 60 Hz frequency. If you change the default values of the nominal power rating and DC voltage, you should change the capacitance value accordingly.
Controller Tab
Mode
Specifies the STATCOM mode of operation. Select either ```Voltage regulation``` or `Var Control`.
Reference voltage Vref
This parameter is not visible when the Mode of operation parameter is set to `Var Control`.
Reference voltage, in pu, used by the voltage regulator.
When External is selected, a Simulink® input named Vref appears on the block, allowing you to control the reference voltage from an external signal (in pu). The Reference grid voltage parameter is therefore unavailable.
Maximum rate of change of reference voltage
This parameter is not visible when the Mode of operation parameter is set to `Var Control`.
Maximum rate of change of the reference voltage, in pu/s, when an external reference voltage is used.
Droop (pu):
This parameter is not visible when the Mode of operation parameter is set to `Var Control`.
Droop reactance, in pu/converter rating Snom, defining the slope of the V-I characteristic.
Vac Regulator Gains: [Kp Ki]
This parameter is not visible when the Mode of operation parameter is set to `Var Control`.
Gains of the AC voltage PI regulator. Specify proportional gain Kp in (pu of I)/(pu of V), and integral gain Ki, in (pu of I)/(pu of V)/s, where V is the AC voltage error and I is the output of the voltage regulator.
Reactive power setpoint Qref
This parameter is not visible when the Mode of operation parameter is set to `Voltage Control`.
Reference reactive power, in pu, when the STATCOM is in ```Var Control```.
Maximum rate of change of reactive power setpoint Qref
This parameter is not visible when the Mode of operation parameter is set to `Voltage Control`.
Maximum rate of change of the reference reactive power, in pu/s.
Vdc Regulator Gains: [Kp Ki]
Gains of the DC voltage PI regulator which controls the voltage across the DC bus capacitor. Specify proportional gain Kp in (pu of I)/Vdc, and integral gain Ki, in (pu of I)/Vdc/s, where Vdc is the DC voltage error and I is the output of the voltage regulator.
Current Regulators Gains: [Kp Ki Kf]
Gains of the inner current regulation loop.
Specify proportional gain Kp in (pu of V)/(pu of I), integral gain Ki, in (pu of V)/(pu of I)/s, and feed forward gain Kf in (pu of V)/(pu of I), where V is the output V2d or V2q of the current regulator and I is the Id or Iq current error.
For optimal performance, the feed forward gain should be set to the converter reactance (in pu) given by parameter L in the Converter impedance [R L] parameters.
Inputs and Outputs
`A B C`
The three terminals of the STATCOM.
`Trip`
Apply a simulink logical signal (0 or 1) to this input. When this input is high the STATCOM is disconnected and its control system is disabled. Use this input to implement a simplified version of the protection system.
`Vref`
Simulink input of the external reference voltage signal.
This input is visible only the External control of reference voltage Vref parameter is checked.
`m`
Simulink output vector containing 16 STATCOM internal signals. These signals are either voltage and current phasors (complex signals) or control signals. They can be individually accessed by using the Bus Selector block. They are, in order:
Signal
Signal Group
Signal Names
Definition
1-3
Power Vabc (cmplx)
Va_prim (pu) Vb_prim (pu)
Vc_prim (pu)
Phasor voltages (phase to ground) Va, Vb, Vc at the STATCOM primary terminals (pu)
4-6
Power Iabc (cmplx)
Ia_prim (pu)
Ib_prim (pu) Ic_prim (pu)
Phasor currents Ia, Ib, Ic flowing into the STATCOM (pu)
7
Power
Vdc (V)
DC voltage (V)
8
Control
Vm (pu)
Positive-sequence value of the measured voltage (pu)
9
Control
Vref (pu)
Reference voltage (pu)
10
Control
Qm (pu)
STATCOM reactive power. A positive value indicates inductive operation.
11
Control
Qref (pu)
Reference reactive power (pu)
12
Control
Id (pu)
Direct-axis component of current (active current) flowing into STATCOM (pu). A positive value indicates active power flowing into STATCOM.
13
Control
Iq (pu)
Quadrature-axis component of current (reactive current) flowing into STATCOM (pu). A positive value indicates capacitive operation.
14
Control
Idref (pu)
Reference value of direct-axis component of current flowing into STATCOM (pu)
15
Control
Iqref (pu)
Reference value of quadrature-axis component of current flowing into STATCOM (pu)
16
Control
modindex
The modulation index m of the PWM modulator. A positive number 0<m<1. m=1 corresponds to the maximum voltage V2 which can be generated by the VSC without overmodulation.
Example
See the `power_statcom` example which illustrates the steady-state and dynamic performance of a STATCOM regulating voltage on a 500 kV, 60 Hz, system. The example also compares the performance of the STACOM with an SVC having the same rating.
References
[1] N. G. Hingorani, L. Gyugyi, "Understanding FACTS; Concepts and Technology of Flexible AC Transmission Systems," IEEE® Press book, 2000.
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https://calculationworld.com/block-calculator/
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# Block Calculator
Projects can vary in size and the amount of materials needed with it.Before you start building anything it is imperative that you have an estimate of what material you will need along with the cost and amount. This calculator allows you to calculate the amount of materials needed!
### How to Use Block Calculator
First enter the length in feet.
Second enter the width in feet.
Press calculate and you'll be informed of how many blocks are needed
L
W
T
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|
https://apboardsolutions.in/ap-board-7th-class-maths-solutions-chapter-2-intext-questions/
|
AP Board 7th Class Maths Solutions Chapter 2 Fractions, Decimals and Rational Numbers InText Questions
AP State Syllabus AP Board 7th Class Maths Solutions Chapter 2 Fractions, Decimals and Rational Numbers InText Questions and Answers.
AP State Syllabus 7th Class Maths Solutions 2nd Lesson Fractions, Decimals and Rational Numbers InText Questions
Do This
Question 1.
Write five examples, each of proper, improper, mixed fractions. ? (Page No. 27)
Solution:
Proper fractions
$$\frac{1}{5}, \frac{2}{3}, \frac{4}{7}, \frac{3}{8}, \frac{4}{9}$$
Improper fractions
$$\frac{7}{2}, \frac{3}{2}, \frac{9}{4}, \frac{11}{5}, \frac{8}{3}$$
Mixed fractions
$$1 \frac{2}{3}, 2 \frac{3}{5}, 4 \frac{1}{7}, 8 \frac{6}{7}$$
Question 2.
Write five equivalent fractions for. i) $$\frac{3}{5}$$ ii) $$\frac{4}{7}$$ (Page No. 28)
Solution:
Do This
Question 1. (Page No. 31)
i) 4 x $$\frac { 2 }{ 7 }$$
ii) 4 x $$\frac { 3 }{ 5 }$$
iii) 7 x $$\frac { 1 }{ 3 }$$
Solution:
i) 4 x $$\frac{2}{7}=\frac{4 \times 2}{7}=\frac{8}{7}$$
ii) 4 x $$\frac{3}{5}=\frac{4 \times 3}{5}=\frac{12}{5}$$
iii) 7 x $$\frac{1}{3}=\frac{7 \times 1}{3}=\frac{7}{3}$$
Question 2.
Find i) 5 x $$\frac { 3 }{ 2 }$$ =
ii) 4 x $$\frac { 7 }{ 5 }$$ =
iii) 7 x $$\frac { 8 }{ 3 }$$ = (Page No. 31)
Solution:
i) 5 x $$\frac{3}{2}=\frac{5 \times 3}{2}=\frac{15}{2}=7 \frac{1}{2}$$
ii) 4 x $$\frac{7}{5}=\frac{4 \times 7}{5}=\frac{28}{5}=5 \frac{3}{5}$$
iii) 7 x $$\frac{8}{3}=\frac{7 \times 8}{3}=\frac{56}{3}=18 \frac{2}{3}$$
Question 3.
Find the following: (Page No. 32)
i) 3 x 2 $$\frac{2}{7}$$
ii) 5 x 2$$\frac{1}{3}$$
iii) 8 x 4$$\frac{1}{7}$$
iv) 4 x 1$$\frac{2}{9}$$
v) 5 x 1$$\frac{1}{3}$$
Solution:
Do These
Question 1.
Fill in these boxes. (Page No. 35)
i) $$\frac{1}{5} \times \frac{1}{7}=\frac{1 \times 1}{5 \times 7}$$ = ……………
ii) $$\frac{1}{2} \times \frac{1}{6}=\frac{1 \times 1}{2 \times 6}=$$ = …………………
Solution:
i) $$\frac{1}{5} \times \frac{1}{7}=\frac{1 \times 1}{5 \times 7}=\frac{1}{35}$$
ii) $$\frac{1}{2} \times \frac{1}{6}=\frac{1 \times 1}{2 \times 6}=\frac{1}{12}$$
Do This
Question 1.
Find (Page No. 39)
i) 2 ÷ $$\frac{1}{4}$$
ii) 7 ÷ $$\frac{1}{2}$$
iii) 3 ÷ $$\frac{1}{5}$$ (Page No. 39)
Solution:
i) 2 ÷ $$\frac{1}{4}=2 \times \frac{4}{1}=\frac{8}{1}$$ = 8
ii) 7 ÷ $$\frac{1}{2}=7 \times \frac{2}{1}$$ = 14
iii) 3 ÷ $$\frac{1}{5}=3 \times \frac{5}{1}$$ = 15
Question 2.
Find (Page No. 41)
i) 9 ÷ $$\frac{2}{5}$$
ii) 3 ÷ $$\frac{4}{7}$$
iii) 2 ÷ $$\frac{8}{9}$$
Solution:
i) 9 ÷ $$\frac{2}{5}$$ = $$9 \times \frac{5}{2}=\frac{45}{2}$$
ii) 3 ÷ $$\frac{4}{7}$$ = $$3 \times \frac{7}{4}=\frac{21}{4}$$
iii) 2 ÷ $$\frac{8}{9}$$ = $$2 \times \frac{9}{8}=\frac{9}{4}$$
Question 3.
Find (Page No. 41)
i) 7 ÷ 5$$\frac{1}{3}$$
ii) 5 ÷ 2$$\frac{4}{7}$$
Solution:
i) 7 ÷ 5$$\frac{1}{3}$$ = $$7 \div \frac{16}{3}=7 \times \frac{3}{16}=\frac{21}{16}$$
ii) 5 ÷ 2$$\frac{4}{7}$$ = $$5 \div \frac{18}{7}=5 \times \frac{7}{18}=\frac{35}{18}$$
Question 4.
Find (Page No. 42)
i) $$\frac{3}{5} \div \frac{1}{2}$$
ii) $$\frac{1}{2} \div \frac{3}{5}$$
iii) $$2 \frac{1}{2} \div \frac{3}{5}$$
iv) $$5 \frac{1}{6} \div \frac{9}{2}$$
Solution:
Do This
Question
Find (Page No. 45)
i) 0.25 + 5.30
ii) 29.75 – 25.97
Solution:
i) 0.25 + 5.30
ii) 29.75 – 25.97
Do These
Question 1.
Find (Page No. 48)
i) 1.7 x 3
ii)2.0 x 1.5
iii) 2.3 x 4.35
Solution:
i)1.7 x 3 = 5.1
ii) 2.0 x 1.5 = 3.00
iii) 2.3 x 4.35 = 10.005
Question 2.
Arrange the products obtained in (I) In descending order.
Solution:
Arranging above answers in descending order 10.005 > 5.1 > 3.00
Question 3.
Find (Page No. 50)
i) 35.7 ÷ 3
ii) 25.5 ÷ 3
Solution:
Do These
Question 1.
Find the greatest and the smallest numbers among the following groups. (Page No. 52)
i) 2, -2, -3, 4, 0, -5
ii) -3, -7, -8,0,-5,-2
Solution:
i) 2, -2, -3, 4, 0, -5 : greatest number = 4; smallest number = -5
ii) -3, -7, -8, 0, -5, -2: greatest number = 0; smallest number = -8
Question 2.
Write the following numbers In ascending order. (Page No. 52)
i) -5,-75,3,-2,4, $$\frac{3}{2}$$
ii) $$\frac{2}{3}, \frac{3}{2}$$, 0, -1, -2, 5
Solution:
i) -5, -75, 3, -2, 4, $$\frac{3}{2}$$
Ascending order = -75 <-5 <-2 < $$\frac{3}{2}$$ <3 < 4 or -75, -5, -2, $$\frac{3}{2}$$, 3, 4
ii) $$\frac{2}{3}$$,$$\frac{3}{2}$$, 0, -1, -2, 5
Ascending order = -2, -1, 0, $$\frac{2}{3}$$, $$\frac{3}{2}$$, 5
Question 3.
Write 5 equlvalent rational numbers to (i) $$\frac{5}{2}$$ (Page No. 56)
(ii) $$\frac{-7}{8}$$
(iii) $$\frac{-3}{7}$$
Solution:
Do These
Question 1.
Which is bigger $$\frac{5}{8}$$ or $$\frac{3}{5}$$ ? (PageNo.28)
Solution:
$$\frac{5}{8} \times \frac{5}{5}=\frac{25}{40}$$ and $$\frac{3}{5} \times \frac{8}{8}=\frac{24}{40}$$
As $$\frac{24}{40}<\frac{25}{40}$$ $$\frac{5}{8}$$ is bigger than $$\frac{3}{5}$$
Question 2.
Determine if the following pairs are equal by writing each in their simplest form. (Page No. 28)
i) $$\frac{3}{8}$$ and $$\frac{375}{1000}$$
Solution:
ii) $$\frac{18}{54}$$ and $$\frac{23}{69}$$
Solution:
iii) $$\frac{6}{10}$$ and $$\frac{600}{1000}$$
Solution:
iv) $$\frac{17}{27}$$ and $$\frac{25}{45}$$
Solution”
Do These
Question 1.
Identify the equivalent rational number is each question
i) $$\frac{-1}{2}, \frac{-3}{4}, \frac{-2}{4}, \frac{-4}{8}$$
Solution:
$$\frac{-1}{2}=\frac{-2}{4}=\frac{-4}{8}$$
ii) $$\frac{1}{4}, \frac{3}{4}, \frac{5}{3}, \frac{10}{6}, \frac{2}{4}, \frac{20}{12}$$
Solution:
$$\frac{5}{3}=\frac{20}{12}=\frac{10}{6}$$
Try This
Question 1.
You have seen that the product of two natural numbers is one or more than one is bigger than each of the two natural numbers. For example 3 x 4 = 12; 12 > 4 and 12 > 3. What happens to the value of the product when we multiply two proper fractions? (Page No.37)
Fill the following table and conclude your observations.
Solution:
Question 2.
Will the reciprocal of a proper fraction be a proper fraction? (Page No. 40)
Solution:
No. Reciprocal of a proper fraction is always an improper fraction.
Question 3.
Will the reciprocal of an Improper fraction be an Improper fraction?
Solution:
No. The reciprocal of an improper fraction is always a proper fraction.
Question 4.
Look at the following table and fill up the blank spaces. (Page No. 44)
Solution:
Question 5.
WrIte the following numbers in their expanded form. (Page No.44)
i) 30.807
ii) 968.038
iii) 8370. 705
Solution:
i) 30.8O7 = 10 x 3 + 1 x 0 + $$\frac{1}{10}$$ x 8 +$$\frac{1}{100}$$ x 0 + $$\frac{1}{1000}$$ x 7 = 30 + $$\frac{8}{10}+\frac{7}{1000}$$
ii) 968.038 = 100 x 9 + 10 x 6 + 1 x 8 + $$\frac{1}{10}$$ x 0 + $$\frac{1}{100}$$ x 3 + $$\frac{1}{1000}$$ x 8 = 900 + 60 + 8 + $$\frac{3}{100}+\frac{8}{1000}$$
iii) 8370.705 = 1000 x 8 + 100 x 3 + 10 x 7 + $$\frac{1}{10}$$ x 7 + $$\frac{1}{1000}$$ x 5 = 8000 + 300 + 70 + $$\frac{7}{10}+\frac{5}{1000}$$
Question 6.
Take any5 Integers and make all possible rational numbrs with them. (Page No. 54)
Solution:
Consider 2, 3, 4, 5 and 7
Ratlonalnumberare $$\frac{2}{3}, \frac{2}{4}, \frac{2}{5}, \frac{2}{7}, \frac{3}{4}, \frac{3}{5}, \frac{3}{7}, \frac{3}{2}, \frac{4}{2}, \frac{4}{3}, \frac{4}{5}, \frac{4}{7}, \frac{5}{2}, \frac{5}{3}, \frac{5}{4}, \frac{5}{7}, \frac{7}{2}, \frac{7}{3}, \frac{7}{4}, \frac{7}{5}$$
Question 7.
Consider any 5 rational numbers. Find out which itegers constitute them? (Page No.54)
Solution:
Take $$\frac{3}{4}, \frac{5}{8}, \frac{6}{11}, \frac{2}{7}$$ and $$\frac{1}{5}$$.
The integers are 1, 2, 3, 4, 5, 6, 7, 8 and 11.
Do This
Question 1.
Find (i) 50 paise = ₹………….. (ii) 22 g = ………….. kg (iii) 80 cm = ………………m (Page No. 44)
Solution:
(i) 50 paise =₹$$\frac{50}{100}$$ = ₹ 0.5
(ii) 22 g = $$\frac{22}{1000}$$ kg = 0.022 kg
(iii) 80 cm = $$\frac{80}{100}$$ m = 0.8 m
Try This
Question 1.
Represent $$\frac{3}{4}$$ and $$\frac{1}{4}$$ in different ways using different figures. Justify your representation. Share, and check it with your friends. (Page No.27)
Solution:
Question 2.
Represents 2 1/4 pictorially. How many units are needed for this. (Page No. 27)
Solution:
We need 3 units to represent 2½
Do These
Question 1.
Represent pictorially 2 x $$\frac{1}{5}=\frac{2}{5}$$ (Page No. 32)
Solution:
Do These
Question 1.
Find $$\frac{1}{2} \times \frac{1}{5}$$ and $$\frac{1}{5} \times \frac{1}{2}$$ using diagram check whether $$\frac{1}{2} \times \frac{1}{5}=\frac{1}{5} \times \frac{1}{2}$$ (Page No. 35)
Solution:
Do These
Question 1.
Write 5 more fractions between (i) 0 and 1 (ii) 1 and 2. (Page No. 52)
Solution:
i) Fractions between 0 and 1 are $$\frac{1}{7}, \frac{2}{7}, \frac{3}{7}, \frac{4}{7}, \frac{5}{7}, \frac{6}{7}$$
ii) Fractions between land 2 are $$\frac{8}{7}, \frac{9}{7}, \frac{10}{7}, \frac{11}{7}, \frac{12}{7}, \frac{13}{7}$$
Question 2.
Where does 4$$\frac{3}{5}$$ lie on the number line? (Page No. 52)
Solution:
4$$\frac{3}{5}$$ lies between 4 and 5 on the number line.
Question 3.
On the number line given below represent the following numbei. (Page No.53)
i) $$\frac{-7}{2}$$
ii) $$\frac{3}{2}$$
iii) $$\frac{7}{4}$$
iv) $$\frac{-7}{4}$$
v) $$\frac{-1}{2}$$
vi) $$\frac{1}{4}$$
Solution:
Question 4.
Consider the following numbers on a number line. (Page No. 53)
27, $$\frac{-7}{8}, \frac{11}{943}, \frac{54}{17}$$, -68, -3, $$\frac{-9}{6}, \frac{7}{2}$$
i) Which of these are to the left of a) 0
Solution:
Left to zero are negative numbers
∴ $$\frac{-7}{8}$$, -68, -3, $$\frac{-9}{6}$$
b) -2
Left to – 2 are less than – 2.
∴ -3, -68
c) 4
Left to 4 are less than 4.
d) 2
Left to 2 are less than 2.
∴ $$\frac{-7}{8}, \frac{11}{943}-68,-3, \frac{-9}{6}$$
ii) Which of these would be to the right of
a) 0
Right to zero are positive number.
∴ $$27, \frac{11}{943}, \frac{54}{17}, \frac{7}{2}$$
b) -5
Right to -5 are greater than -5.
$$27, \frac{-7}{8}, \frac{11}{943}, \frac{54}{17}-3, \frac{-9}{6}, \frac{7}{2}$$
c) 3$$\frac{1}{2}$$
Right to 3$$\frac{1}{2}$$ are more than 3$$\frac{1}{2}$$.
∴ 27
d) $$\frac{-5}{2}$$
Right to $$\frac{-5}{2}$$ are more than $$\frac{-5}{2}$$
∴ $$-27, \frac{-7}{8}, \frac{11}{943}, \frac{54}{17} \frac{-9}{6}, \frac{7}{2}$$
Try These
Question 1.
Write three more equivalent fractions of $$\frac{3}{4}$$ and mark them on the number line. What do you observe? (Page No. 55)
Solution:
Equivalent fractions of $$\frac{3}{4}$$ lie on the same mark.
Question 2.
Do all equivalent fractions of $$\frac{6}{7}$$ represent the same point on the number line.
(Page No. 55)
Solution:
Yes.
Question 3.
Are $$\frac{-1}{2}$$ and $$\frac{-3}{6}$$ represent same point on the number line? (Page No. 55)
Solution:
Yes.
Question 4.
Are $$\frac{-2}{3}$$ and $$\frac{-4}{6}$$ equivalent? . (Page No. 55)
Solution:
Yes.
Question 5.
Mark the following rational numbers on the number line. (In Ex 7,3)
(i) $$\frac{1}{2}$$
(ii) $$\frac{3}{4}$$
(iii) $$\frac{3}{2}$$
(iv) $$\frac{10}{3}$$
Solution:
|
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|
https://puzzling.stackexchange.com/questions/101074/find-the-area-of-the-given-triangle
|
# Find the area of the given triangle
Another mathematical puzzle:
Find the area of $$\triangle FGH$$, given that $$FG=FH$$ and the radii of the circles shown are $$2$$ and $$1$$
• please provide the source if this is not your own work. else it will likely be closed. thanks – Omega Krypton Aug 12 at 14:17
• The question says FG=GH but the diagram is drawn as if FG=FH and GH is very different. Is there a typo in the question, or is the diagram deliberately very misleading? – Gareth McCaughan Aug 12 at 14:38
• It somewhat looks like a homework... – CiaPan Aug 12 at 14:47
• Duplicate of math.stackexchange.com/q/1766545/369453 :D – Marius Aug 12 at 15:10
• @GarethMcCaughan Thanks for pointing that out, I've fixed it. Also, good catch by Marius! I didn't know that this had been asked before. It's purely coincidential :) – Aniruddha Deb Aug 12 at 15:16
$$16\sqrt2$$
Because:
if you draw radii where the circles are tangent to the triangles with tangent points marked as $$D$$ (smaller circle) and $$E$$ (larger circle; this forms right angles), you get the following similar triangles: $$\triangle FDA \sim \triangle FEB \sim \triangle FXG$$. $$A$$ is the center of the small circle and $$B$$ is the center of the large one. $$X$$ is the midpoint of $$HG$$.
From this, we get this proportion:
$$\frac{FA}{FB} = \frac{DA}{EB}$$ OR $$\frac{FA}{FA+3} = \frac{1}{2}$$ because of the radii lengths.
So:
$$FA=3$$
Using Pythagorean Theorem:
$$FD = \sqrt8$$
Using our similar triangle relations from the beginning, we get:
$$XG = 2\sqrt2$$
Finally, we use the area of a triangle formula to get:
$$16\sqrt2$$
• Sorry, I got tired of showing my work... – Voldemort's Wrath Aug 12 at 14:52
• I'm sure this is a good answer, but I got kind of lost when you started drawing new things. If you had a picture, that would help greatly. – Chipster Aug 12 at 22:38
• @Chipster - No, you're right... I'll add that in when I find time! – Voldemort's Wrath Aug 13 at 11:57
• A picture would help, but even with no picture, please could you clarify which point is $D$ and which is $E$? – Rosie F Aug 14 at 8:57
• @RosieF -- $D$ is for the smaller circle and $E$ is for the larger one. – Voldemort's Wrath Aug 14 at 15:48
Let $$h$$ denote the height of the triangle from F onto GH. Then, by Pythagoras' theorem, $$FG^2=h^2+(GH/2)^2,$$ and by triangles' similarity $$h:(GH/2) = (FG-GH/2):2$$ and $$(h-4):h = 1:2.$$
Can you continue from this?
From the last we get $$h-4=h/2$$ which resolves to $$h=8.$$ Plug it to previous two to get
$$\begin{cases}FG^2=64+(GH/2)^2\\8:(GH/2) = (FG-GH/2):2\end{cases}$$ The last equation is equivalent to $$16:(GH/2) = (FG-GH/2)$$
hence
$$FG = (GH/2)+16:(GH/2)$$ and $$FG^2 = (GH/2)^2 + 32 + 256:(GH/2)^2$$
Compare it to the first equation: $$64+(GH/2)^2 = (GH/2)^2 + 32 + 256:(GH/2)^2$$ $$64 = 32 + 256:(GH/2)^2$$ $$32 = 256:(GH/2)^2$$ $$(GH/2)^2 = 256:32 = 8$$ $$GH/2 = \sqrt 8 = 2\sqrt 2$$
Finally the area sought is
$$S_{\triangle FGH} = h\cdot GH/2 = 16\sqrt 2.$$
• See my answer; I think I got it?? – Voldemort's Wrath Aug 12 at 14:50
• @Voldemort'sWrath Yes, you did. I didn't show my solution at first, because the question looks like a homework (my comment), so I wanted the author to show some effort first. Now I uncommented the hiden part with the same result as yours. – CiaPan Aug 13 at 7:39
Let me chip in with a streamlined answer.
$$8\sqrt 8$$
All the smaller circle is telling us is that the height of the triangle must be $$8$$, so let's jot that down and from here pretend the small circle never existed.
The points where the circle (there is only one circle!) touches the triangle divide the long sides into two segments of lengths $$y>x$$ and the base into two equal segments of length $$x$$. Let us now compute the area $$A$$ of the triangle from base and height $$A=8x$$, from incircle radius and circumference $$A=2(2x+y)$$ and from Heron's formula $$A^2=x^2y(2x+y)$$. Comparing the first two gives $$2x=y$$, together with the last we get $$x=\sqrt 8$$ and $$A=8\sqrt 8$$.
• Please explain where A = 2(2x + y) came from. Thanks. – asg Aug 13 at 8:56
• @asg as it says "from incircle radius and circumference". $2x+y$ is the semicircumference often written $s$ of the triangle. – Paul Panzer Aug 13 at 9:21
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|
https://ideaexchange.uakron.edu/polymerscience_ideas/191/
|
## Polymer Science Faculty Research
#### Title
Solvent-induced collapse of a helical semiflexible polymer
Article
Fall 2005
#### Abstract
It has been stated that the class of materials richest in the occurrence of phase transitions are polymers'' (E. A. Di Marzio, \textit{Prog. Polym. Sci}. \textbf{24}, 329 (1999)). This wealth of phase transitions is unique to polymers and is a consequence of the myriad of possible ways of coupling the basic ten classes of polymeric phase transitions into pairs, triplets and so forth. Two of these transitions are the helix-coil and coil-globule transitions. In this talk we explore the coupling of these two transitions, its molecular origins and physical consequences. For this purpose, we extend a recently developed model of helical polymers to describe the effect of solvent quality and solve it using Monte Carlo simulations based on the Wang and Landau algorithm. We find a very rich phase diagram consisting of 6 phases characterized by very specific conformations of the chain, i.e., a perfect helix, a random coil, a globule or other globular states with residual helical strands. We study the phase boundaries and provide further insight into the physics of the problem with a detailed analysis of the conformational and thermodynamic properties of the polymer chain.
COinS
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http://alexanderpruss.blogspot.com/2012/12/uniform-measure-and-nonmeasurable-sets.html
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## Tuesday, December 11, 2012
### Uniform measure and nonmeasurable sets, without the Axiom of Choice
Given the Axiom of Choice, there is no translation invariant probability measure on the interval [0,1) (the relevant translation is translation modulo 1). But this fact really does need something in the way of the Axiom of Choice. Moreover, the fact only obtains for countably additive measures. Interestingly, however, if we add the assumption that our measure assigns non-zero (presumably infinitesimal) weight to each point of [0,1), then the non-existence of a translation invariant finitely additive measure follows without the Axiom of Choice. I got the proof of this from Paul Pedersen who thinks he got it from the classic Bernstein and Wattenberg piece (I don't have their paper at hand). I am generalizing trivially.
Theorem: Let P be any finitely additive measure taking values in a partially ordered group G and defined on a collection of subsets of [0,1) such that every countable subset has a measure in G. Suppose P({x})>0 for some x in [0,1). Then P is not translation invariant (modulo 1).
Proof: To obtain a contradiction, suppose P is translation invariant. Then P({x})>0 for every x in [0,1). Let r be any irrational number in (0,1), and let R be the set of numbers of the form nr modulo 1, as n ranges over the positive integers. Let R' be the set of numbers of the form nr modulo 1, as n ranges over the integers greater than 1. Then R' is a translation of R by r, modulo 1. Observe that r is not a member of R' since there is no natural number n greater than 1 such that r=nr modulo 1, since if there were, we would have (n−1)r=0 modulo 1, and hence r would be a rational number with denominator n−1. Thus by finite additivity P(R)=P(R')+P({r})>P(R'). Hence, R is a counterexample to translation invariance, contradicting our assumption.
Note 1: On the assumption that the half-open intervals are all measurable and the measurable sets form an algebra (the standard case), translation invariance modulo 1 follows from ordinary translation invariance within the interval, namely the condition that P(A)=P(A+x) whenever both A and A+x={y+x:y in A} are subsets of [0,1).
Note 2: The proof above shows that if P({x})>0 for every x in [0,1), then the set of all positive integral multiples of any fixed irrational number (modulo 1) is nonmeasurable. It is interesting to note that this nonmeasurable set is actually measurable using standard Lebesgue measure. Thus, by enforcing regularity using infinitesimals, one is making some previously measurable sets nonmeasurable if one insists on translation invariance.
Note 3: Bernstein and Wattenberg construct a hyperreal valued measure that is almost translation invariant: the difference between the measure of a set and of a translation of the set is infinitesimal.
Alexander R Pruss said...
Slight generalization.
Let P be a finitely additive measure on the countable subsets of some set Omega taking values in some partially ordered group G. Let H be a group that acts on Omega such that there are g in H and w in Omega with { g^n w : n in N } infinite.
Then (a) P assigns null weight to some non-empty sets (i.e., P is not regular) or (b) P is not H-invariant.
If H acts transitively on Omega, then (a) implies P assigns null weight to all singletons.
Matt said...
Could you please explain the first sentence? Surely Lebesgue measure is translation-invariant in the requisite sense, no?
Matt said...
This comment has been removed by the author.
Alexander R Pruss said...
I meant: on all subsets of [0,1).
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https://jcgoran.github.io/2021/05/04/apocalypse-problem.html
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I’ve recently been going through the book Cracking the coding interview (6th ed.), and an interesting problem was stated there (abridged for brevity):
In a new post-apocalyptic world, the world leader decides that all families must have one girl, or face massive fines. If all families continue to have children until they have one girl, at which point they immediately stop, what will the gender ratio of the new generation be? Assume that the probabilities of having a boy or a girl are equal.
The solution
Since all families must eventually have exactly one girl, then $N_\text{girls} = N$, where $N$ is the number of families. The probability of having $n$ boys (denoted $B$) before having a girl (denoted $G$) is therefore:
$P(\underbrace{BB\ldots B}_{n}G) = \underbrace{\frac{1}{2}\times\frac{1}{2} \times \cdots \times \frac{1}{2}}_{n} \times \frac{1}{2} = \frac{1}{2^{n + 1}}$
While we don’t know exactly how many boys are in each individual family, we can still compute the average, or the expectation value, of the number of boys in a family, defined as:
$\mathbb{E}(X) = \sum_{n}x_n\, p_n = \sum_{n=0}^\infty\frac{n}{2^{n + 1}} = \frac{1}{2} \times \sum_{n=0}^\infty\frac{n}{2^{n}}$
where we’ve taken the random variable $X$ to be the number of boys in a family, hence $x_n = n$ and $p_n = 1/2^{n + 1}$, and the sum goes over all possibilities ($[0,\ldots,\infty)$ boys)1.
How do we compute this sum without a computer? Well, let’s first consider the following sum instead:
$S_n (q) = \sum_{i = 0}^n q^i$
This is the well-known geometric sum, whose sum is equal to2:
$S_n (q) = \frac{q^{n + 1} - 1}{q - 1}$
We can see that, for $0 < q < 1$, we have the following:
$\lim_{n \rightarrow \infty} S_n(q) = \lim_{n \rightarrow \infty} \sum_{i = 0}^n q^i = \lim_{n \rightarrow \infty} \frac{q^{n + 1} - 1}{q - 1} = \frac{1}{1 - q}$
The reason is that, since $0 < q < 1$, we have that $q^2 < q < 1$, etc., and in fact the entire sequence $\left\lbrace 1, q, q^2, \ldots \right\rbrace$ is decreasing, and since it’s bounded below by 0, it means that we have $\displaystyle\lim_{n \rightarrow \infty} q^n = 0$, which gives the above. We may as well define:
$S(q) = \sum_{i = 0}^\infty q^i = \frac{1}{1 - q}$
to keep things concise. Now, how does this apply to our problem? Well, if we put $q = 1/2$ in the above, we get:
$S\left(\frac{1}{2}\right) = \sum_{i = 0}^\infty \left(\frac{1}{2}\right)^i = \frac{1}{1 - 1/2} = 2$
Now, if we compute the first derivative of $S(q)$, on the right-hand side we get:
$\frac{\text{d}}{\text{d} q}S(q) = \frac{1}{(1 - q)^2}$
while the left-hand side is just:
$\frac{\text{d}}{\text{d} q}S(q) = \sum_{i = 1}^\infty i\, q^{i - 1} = \sum_{i = 0}^\infty (i + 1)\, q^i = \sum_{i = 0}^\infty i\, q^i + \sum_{i = 0}^\infty q^i$
where in the last step we’ve just split one sum into two. However, you may notice that the second term is actually just $S(q) = 1/(1 - q)$, so we have:
$\sum_{i = 0}^\infty i\, q^i = \frac{1}{(1 - q)^2} - \frac{1}{1 - q} = \frac{q}{(1 - q)^2}$
where we’ve simplified the final expression with a bit of algebra. But the expression on the left-hand side is exactly what we’re looking for, provided we take $q = 1/2$! Therefore, going back to the original problem, we have that:
$\mathbb{E}(X) = \frac{1}{2} \times \sum_{n=0}^\infty\frac{n}{2^{n}} = \frac{1}{2} \times \frac{1 / 2}{(1 - 1 / 2)^2} = 1$
This result may be a bit puzzling: it seems that the policy of the world leader is completely useless, since in the end we just end up with 1 boy and 1 girl per family, on average. But recall that biology hasn’t been altered, so we sort of expect that things would even out.
Going beyond: unequal probabilities
What happens if the probabilities are not equal though? Let’s say the probability of having a boy is $p$; then the probability of having a girl would be $1 - p$, and the probability of having a girl after $n$ boys is now:
$P(\underbrace{BB\ldots B}_{n}G) = \underbrace{p\times p\times\cdots\times p}_{n}\, (1 - p) = p^n\, (1 - p)$
Then the expectation value for the number of boys is:
$\mathbb{E}(X) = \sum_{n=0}^\infty n \times p^n (1 - p) = (1 - p) \sum_{n=0}^\infty n \times p^n = (1 - p) \times \frac{p}{(1 - p)^2} = \frac{p}{1 - p}$
From this we can see that the original problem is just the special case $p = 1/2$. I’ve plotted the expectation value of the number of boys as a function of the value of $p$ below.
The number of boys as a function of the value of $p$. The red diamond represents the special value $p = 1/2$, for which the expectation value is 1.
It’s worthwhile to note that an equivalent problem is to consider $N$ (in the general case, biased) coins, which we keep flipping until we get one of the outcomes, say, heads. Actually, we don’t even need $N$ coins; since the coin flips are statistically independent, we may as well keep throwing the same coin until we get heads, and then repeat this procedure $N$ times.
Footnotes
1. since there are infinitely many terms in the sum, it’s technically called a series
2. this can be proved using mathematical induction
|
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http://gudhi.gforge.inria.fr/python/latest/persistence_graphical_tools_user.html
|
# Persistence graphical tools user manual¶
## Definition¶
These graphical tools comes on top of persistence results and allows the user to display easily persistence barcode, diagram or density. Note that these functions return the matplotlib axis, allowing for further modifications (title, aspect, etc.) Author Vincent Rouvreau, Theo Lacombe Since GUDHI 2.0.0 License MIT Requires Matplotlib
## Show persistence as a barcode¶
This function can display the persistence result as a barcode:
import matplotlib.pyplot as plt
import gudhi
off_file = gudhi.__root_source_dir__ + '/data/points/tore3D_300.off'
rips_complex = gudhi.RipsComplex(points=point_cloud, max_edge_length=0.7)
simplex_tree = rips_complex.create_simplex_tree(max_dimension=3)
diag = simplex_tree.persistence(min_persistence=0.4)
gudhi.plot_persistence_barcode(diag)
plt.show()
## Show persistence as a diagram¶
This function can display the persistence result as a diagram:
import matplotlib.pyplot as plt
import gudhi
# rips_on_tore3D_1307.pers obtained from write_persistence_diagram method
persistence_file=gudhi.__root_source_dir__ + \
'/data/persistence_diagram/rips_on_tore3D_1307.pers'
ax = gudhi.plot_persistence_diagram(persistence_file=persistence_file,
legend=True)
# We can modify the title, aspect, etc.
ax.set_title("Persistence diagram of a torus")
ax.set_aspect("equal") # forces to be square shaped
plt.show()
Note that (as barcode and density) it can also take a simple np.array of shape (N x 2) encoding a persistence diagram (in a given dimension).
import matplotlib.pyplot as plt
import gudhi
import numpy as np
d = np.array([[0, 1], [1, 2], [1, np.inf]])
gudhi.plot_persistence_diagram(d)
plt.show()
## Persistence density¶
Requires
SciPy
import matplotlib.pyplot as plt
import gudhi
# rips_on_tore3D_1307.pers obtained from write_persistence_diagram method
persistence_file=gudhi.__root_source_dir__ + \
'/data/persistence_diagram/rips_on_tore3D_1307.pers'
persistence_file=persistence_file,
only_this_dim=1)
pers_diag = [(1, elt) for elt in birth_death]
# Use subplots to display diagram and density side by side
fig, axes = plt.subplots(nrows=1, ncols=2, figsize=(12, 5))
gudhi.plot_persistence_diagram(persistence=pers_diag,
axes=axes[0])
gudhi.plot_persistence_density(persistence=pers_diag,
dimension=1, legend=True, axes=axes[1])
plt.show()
## LaTeX support¶
If you are facing issues with LaTeX rendering, you can still deactivate LaTeX rendering by saying:
import gudhi
gudhi.persistence_graphical_tools._gudhi_matplotlib_use_tex=False
|
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|
https://deepai.org/publication/stabilized-sparse-online-learning-for-sparse-data
|
DeepAI
# Stabilized Sparse Online Learning for Sparse Data
Stochastic gradient descent (SGD) is commonly used for optimization in large-scale machine learning problems. Langford et al. (2009) introduce a sparse online learning method to induce sparsity via truncated gradient. With high-dimensional sparse data, however, the method suffers from slow convergence and high variance due to the heterogeneity in feature sparsity. To mitigate this issue, we introduce a stabilized truncated stochastic gradient descent algorithm. We employ a soft-thresholding scheme on the weight vector where the imposed shrinkage is adaptive to the amount of information available in each feature. The variability in the resulted sparse weight vector is further controlled by stability selection integrated with the informative truncation. To facilitate better convergence, we adopt an annealing strategy on the truncation rate, which leads to a balanced trade-off between exploration and exploitation in learning a sparse weight vector. Numerical experiments show that our algorithm compares favorably with the original algorithm in terms of prediction accuracy, achieved sparsity and stability.
• 2 publications
• 14 publications
06/12/2021
03/22/2016
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Stochastic gradient descent (SGD) has taken the stage as the primary wor...
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### Stochastic Gradient Made Stable: A Manifold Propagation Approach for Large-Scale Optimization
Stochastic gradient descent (SGD) holds as a classical method to build l...
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### Unbiased Online Recurrent Optimization
The novel Unbiased Online Recurrent Optimization (UORO) algorithm allows...
01/18/2021
### Screening for Sparse Online Learning
Sparsity promoting regularizers are widely used to impose low-complexity...
08/24/2020
### Noise-induced degeneration in online learning
In order to elucidate the plateau phenomena caused by vanishing gradient...
None
## 1 Introduction
Modern datasets pose many challenges for existing learning algorithms due to their unprecedented large scales in both sample sizes and input dimensions. It demands both efficient processing of massive data and effective extraction of crucial information from an enormous pool of heterogeneous features. In response to these challenges, a promising approach is to exploit online learning methodologies that performs incremental learning over the training samples in a sequential manner. In an online learning algorithm, one sample instance is processed at a time to obtain a simple update, and the process is repeated via multiple passes over the entire training set. In comparison with batch learning algorithms in which all sample points are scrutinized at every single step, online learning algorithms have been shown to be more efficient and scalable for data of large size that cannot fit into the limited memory of a single computer. As a result, online learning algorithms have been widely adopted for solving large-scale machine learning tasks (Bottou, 1998).
In this paper, we focus on first-order subgradient-based online learning algorithms, which have been studied extensively in the literature for dense data.111Dense data is defined as a dataset in which the number of nonzero entries in all columns of its design matrix are in the order of while the ones of sparse data are in the order of or less. Among these algorithms, popular methods include the Stochastic Gradient Descent (SGD) algorithm (Zhang, 2004; Bottou, 2010), the mirror descent algorithm (Beck and Teboulle, 2003) and the dual averaging algorithm (Nesterov, 2009). Since these methods only require the computation of a (sub)gradient for each incoming sample, they can be scaled efficiently to high-dimensional inputs by taking advantage of the finiteness of the training sample. In particular, the stochastic gradient descent algorithm is the most commonly used algorithm in the literature of subgradient-based online learning. It enjoys an exceptionally low computational complexity while attaining steady convergence under mild conditions (Bottou, 1998)
, even for cases where the loss function is not everywhere differentiable.
Despite of their computational efficiency, online learning algorithms without further constraint on the parameter space suffers the “curse of dimensionality” to the same extent as their non-online counterparts. Embedded in a dense high-dimensional parameter space, not only does the resulted model lack interpretability, its variance is also inflated. As a solution,
sparse online learning was introduced to induce sparsity in the parameter space under the online learning framework (Langford et al., 2009)
. It aims at learning a linear classifier with a sparse weight vector, which has been an active topic in this area. For most efforts in the literature, sparsity is introduced by applying
regularization on a loss function as in the classific LASSO method (Tibshirani, 1996; Shalev-Shwartz and Tewari, 2011). For example, Duchi and Singer (2009) extend the framework of Forward-Backward splitting (Lions and Mercier, 1979) by alternating between an unconstrained truncation step on the sample gradient and an optimization step on the loss function with a penalty on the distance from the truncated weight vector.Langford et al. (2009) and Carpenter (2008) both explore the idea of imposing a soft-threshold on the weight vector updated by the stochastic gradient descent algorithm:
wj=sign(wj)max(|wj|−λ,0),j=1,…,p.
This class of methods is known as the truncated gradient algorithm. For every standard SGD updates, the weight vector is shrunk by a fixed amount to induce sparsity. In the work of Duchi et al. (2010), the same strategy has also been combined with a variant of the mirror descent algorithm (Beck and Teboulle, 2003). Wang et al. (2015) further extends the truncated gradient framework to adjust for cost-effectiveness. This simple yet efficient method of truncated gradients particularly motivates the algorithm proposed in this paper. Strategies different from the truncation-based algorithm have also been proposed. For example, Xiao (2009) proposed the Regularized Dual-Averaging (RDA) algorithm which builds upon the primal-dual subgradient method by Nesterov (2009). The RDA algorithm learns a sparse weight vector by solving an optimization problem using the running average over all preceding gradients, instead of a single gradient at each iteration.
Closely related to sparse online learning is another area of active research, online feature selection. Instead of enforcing just a shrinkage on the weight vectors via
regularization, online feature selection algorithms explicitly invoke feature selection by imposing a hard
constraint on the weight vector, (e.g., Wang et al., 2014; Wu et al., 2014). In other words, online feature selection algorithms focus on generating a resulted weight vector that has a high sparsity level by directly shrinking a large proportion of the weights directly to zero (also referred to as a hard thresholding). In practice, regularization is computationally expensive to solve due to its non-differentiability. The set of selected features also suffers from high variability as the decisions of hard-thresholding are based on single random samples in an online learning setting. Therefore, important features can be discarded simply owing to random perturbations.
Most recent subgradient-based online learning algorithms do not consider potential structures or heterogeneity in the input features. As pointed out by Duchi et al. (2011), current methods largely follow a predetermined procedural scheme that is oblivious to the characteristics of data being used at each iteration. In large-scale applications, a common and important structure is heterogeneity in sparsity levels of the input features, i.e., the variability in the number of nonzero entries among features. For instance, consider the bag-of-word features in text mining applications.222Here, by sparse features, we refer to features for which most samples assume a constant value (e.g., 0) and a few samples take on other values. Without loss of generality, we assume the majority constant is 0 throughout this paper. For a learning task, the importance of a feature is not necessarily associated with the frequencies of its values. In genetics, for example, rare variants ( in the population) have been found to be associated with disease risks (Morris and Zeggini, 2010). Both dense and sparse features may contain important information for the learning task. However, in the presence of heterogeneity in sparsity levels, using a simple regularization in an online setting will predispose rare features to be truncated more than necessary. The resulted sparse weight vectors usually exhibit high variance in terms of both weight values and the membership in the set of features with nonzero weights. As a result, the convergence of the standard truncation-based framework may also be hampered by this high variability. When the amount of information is scarce due to sparsity at each iteration, the convergence of the weight vector would understandably take a large number of iterations to approach the optimum. In two recent papers, Oiwa et al. (2011) and Oiwa et al. (2012) tackle this problem via penalty weighted by the accumulated norm of subgradients for extending several basic frameworks in sparse online learning. Their results suggest that, by acknowledging the sparsity structure in the features, both prediction accuracy and sparsity are improved over the original algorithms while maintaining the same convergence rate. However, their resulted weight vectors are unstable as the imposed subgradient-based regularization are excessively noisy due to the randomness of incoming samples in online learning. The membership in the set of selected features with nonzero weights is also very sensitive to the orderings of the training samples.
In this paper, we propose a stabilized truncated stochastic gradient descent algorithm for high-dimensional sparse data. The learning framework is motivated by that of the Truncated Gradient algorithm proposed by Langford et al. (2009). To deal with the aforementioned issues with sparse online learning methods applied to high-dimensional sparse data, we introduce three innovative components to reduce variability in the learned weight vector and stabilize the selected features. First, when applying the soft-thresholding, instead of a uniform truncation on all features, we perform only informative truncations, based on actual information from individual features during the preceding computation window of updates. By doing so, we reduce the heterogeneous truncation bias associated with feature sparsity. The key idea here is to ensure that each truncation for each feature is based on sufficient information, and the amount of shrinkage is adjusted for the information available on each feature. Second, beyond the soft-thresholding corresponding to the ordinary regularization, the resulted weight vector is stabilized by staged purges of irrelevant features permanently from the active set of features. Here, irrelevant features are defined as features whose weights have been repeatedly truncated. Motivated by stability selection introduced in Meinshausen and Bühlmann (2010), these permanent purges prevent irrelevant features from oscillating between the active and non-active set of features, The “purging” process also resembles hard-thresholding in online feature selection and results in a stabler sparse solution than other sparse online learning algorithms. Results on the theoretical regret bound (See Section 4
) show that this stabilization step helps improve over the original truncated gradient algorithm, especially when the target weight vector is notably sparse. To attune the proposed learning algorithm to the sparsity of the remaining active features, the third component of our algorithm is adjusting the amount of shrinkage progressively instead of fixing it at a predetermined value across all stages of the learning process. A novel hyperparameter,
rejection rate, is introduced to balance between exploration of different sparse combinations of features at the beginning and the exploitation
of the selected features to construct accurate estimate at a later stage. Our method gradually anneal the rejection rate to acquire the necessary amount of shrinkage on the fly for achieving the desired balance.
The rest of paper is organized as follows. Section 2 reviews the Truncated Gradient algorithm based on Stochastic Gradient Descent (SGD) framework for sparse learning proposed in Langford et al. (2009). In Section 3, we introduce, in details, the three novel components of our proposed algorithm. Theoretical analysis of the expected online regret bound is given in Section 4, along with the computational complexity. Section 5 gives practical remarks for efficient implementation. In Section 6, we evaluate the performance of the proposed algorithm on several real-world high-dimensional datasets with varying sparsity levels. We illustrate that the proposed method leads to improved stability and prediction performance for both sparse and dense data, with the most improvement observed in data with the highest average sparsity level. Section 7 concludes with further discussion on the proposed algorithm.
## 2 Truncated Stochastic Gradient Descent for Sparse Learning
Assume that we have a set of training data , where the feature vector and the scalar output . In the following, we use to represent the vector of the sample of length and for the feature vector of all samples of length . In this paper, we are interested in the case that both and are large and the feature vectors ’s, , are sparse. We consider a loss function that measures the cost of predicting when the truth is . The prediction is given by function from a family parametrized by a weight vector . Denote . The learning goal is to obtain an optimal weight vector that minimize the loss function over the training data, with sparsity in the weight vector induced by a regularization term . We can then formulate the learning task as a regularized minimization problem:
^w =argminw∈Rp n∑i=1L(w,zi)+Ψ(w). (1)
The above optimization problem is often solved using some version of gradient descent. When both and are large, the computation becomes very demanding. To address this computational complexity, the Stochastic Gradient Descent (SGD) algorithm was proposed as a stochastic approximation of the full gradient algorithm Bottou (1998). Instead of computing the gradient over the entire training set as under the batch setting, the stochastic gradient descent algorithm uses approximate gradients based on subsets of the training data. This is particularly attractive to large scale problems as it leads to a substantial reduction in computing complexity and potentially distributed implementation.
For applications with large data sets or streaming data feeds, SGD has also been used as a subgradient-based online learning method. Online learning and stochastic optimization are closely related and interchangeable most of the time (Cesa-Bianchi et al., 2004). For simplicity, in the following, we focus our discussion and algorithmic description under the online learning framework with regret bound models. Nonetheless, our results can be readily generalized to stochastic optimization as well.
In online learning, the algorithm receives a training sample at a time from a continuous feed. Without sparsity regularization, at time , the weight vector is updated in an online fashion with a single training sample drawn randomly,
wt =wt−1−ηL′(wt−1,zt) (2)
where is the learning rate and is a subgradient of the loss function with respect to . The set of subgradients of f at the point is called the subdifferential of at , and is denoted . A function is called subdifferentiable if it is subdifferentiable at all dom . When is differentiable at , . At the same time, a sequence of decisions is generated at , that encounters a loss respectively.
The goal of online learning algorithm with sparsity regularization is to achieve low regret with respect to a fixed optimal weight vector . Here, is the parameter space for sparse weights vectors (see Assumption 3 on page 15 for more details.) The regret is defined as:
RT(w∗)≜T∑t=1(L(wt,zt)+Ψ(wt))−T∑t=1(L(w∗,zt)+Ψ(w∗)). (3)
In this paper, we focus on the regularization where and is the regularizing parameter. When adopted in an online learning framework, standard SGD algorithm does not work well in addressing (1) with penalty. Firstly, a simple online update requires the projection of the weight vector onto a -ball at each step, which is computationally expensive with a large number of features. Secondly, with noisy approximate subgradient computed using a single sample, the weights can easily deviate from zero due to the random fluctuations in ’s. Such a scheme is therefore inefficient to maintain a sufficiently sparse weight vector.
To address this issue, Langford et al. (2009) induced sparsity in by subjecting the stochastic gradient descent algorithm to soft-thresholding. For every iterations at step , each of which is as defined in (2), the weight vector is shrunk by a soft-threshold operator with a gravity parameter with for . For a vector ,
^wt=T(wt,g), (4)
where with the operator defined by
T(wj,gj) ≜{max(wj−gj,0),if% wj>0;min(wj+gj,0),if wj≤0. (5)
As one can see, the sequence of SGD updates can be treated as a unit computational block, which will be referred to as a burst hereafter. Here the word burst indicates that it is a sequence of repetitive actions, e.g., the standard SGD updates as defined in (2), without interruption. Each burst is followed by a soft-thresholding truncation defined in (4), which puts a shrinkage on the learned weight vector.
A burst can be viewed as a base feature selection realized on a set of random samples with regularization as in the classical LASSO (Tibshirani, 1996). Within a burst, let be the set of random samples on which the weight vector is stochastically learned. We define the set of features with nonzero weights in as its active (feature) set:
^Sg(^w;XK)={j:|^wj|>0}, (6)
with a corresponding gravity . The steps within a truncated burst are summarized in Algorithm 1.
In the truncated gradient algorithm of Langford et al. (2009), the gravity parameter is a constant across all dimensions as , where is a base gravity for each update in a burst and . In general, with greater parameter and smaller burst size , more sparsity is attained. When , the update in (4) becomes identical to the standard stochastic gradient descent update in (2). Langford et al. (2009) showed that this updating process can be regarded as an online counterpart of regularization in the sense that it approximately solves (1) in the limit as and .
## 3 Stabilized Truncated SGD for Sparse Learning
Truncated SGD Langford et al. (2009) works well for dense data. When it comes to high-dimensional sparse inputs, however, it suffers from a number of issues. Shalev-Shwartz and Tewari (2011) observe that the truncated gradient algorithm is incapable of maintaining sparsity of the weight vector as it iterates. Recall that, under the online learning setting, the weight vector
is updated with a noisy approximation of the true expected gradient using one sample at a time, from a random ordering of the data. With sparse inputs, it is highly probable that an important feature does not have a nonzero entry for many consequent samples, and is meaningfully updated for only a few times out of the
updates in a burst. As a result, it would be truncated after a few iterations and brought back to nonzero after another few updates. At the same time, sparsity in inputs will also give rise to sporadic large nonzero updates for irrelevant features, which cannot be fully resolved by the soft-threshold operator. The derived weight vector ’s are of high variance, inadequate sparsity and poor generalizability. As an example, the number of nonzero variables in the weight vector during the last 1000 stochastic updates from the truncated gradient algorithm implemented on a high-dimensional sparse dataset (Dexter text mining data set; see Section 6 for details.) are shown in Figure 1. It can be seen that the numbers of nonzero features in the weight vectors learned by the truncated SGD algorithm () remain large and highly unstable throughout these 1000 iterations, oscillating within 10% of the total number of features. As a comparison, also in Figure 1, we plot the results from our proposed stabilized truncated SGD applied to the same data. During these last 1000 updates, the proposed algorithm is using a less frequent truncation schedule due to our annealed reject rate. It attains both high sparsity in the weight vector and high stability with high-dimensional sparse data.
In this section, we introduce the stabilized truncated Stochastic Gradient Descent (SGD) algorithm. It attains a truly sparse weight vector that is stable and gives generalizable performance. Our proposed method attunes to the sparsity of each feature and adopts informative truncation. The algorithm keeps track of whether individual features have had enough information to be confidently subject to soft-thresholding. Based on the truncation results, we systematically reduce the active feature set by permanently discarding features that are truncated to zero with high probability via stability selection. We further improve the efficiency of our algorithm by adapting gravity to the sparsity of the current active feature set as the algorithm proceeds.
### 3.1 Informative Truncation
For the truncated SGD algorithm, Langford et al. (2009) suggest a general guideline for determining gravity in the batch mode by scaling a base gravity by , the number of updates, for a single truncation after a burst. A direct online adaptation of a regularization would shrinks the weight vector at every iteration. The above batch mode operation is to delay the shrinkage for iterations so that the truncation is executed based on information collected from random samples instead of from a single instance. This guideline implicitly assumes that the SGD updates in a burst are equally informative, which is in general true for dense features. For sparse features, however, under the online learning setting, not every update is informative about every feature due to the scarcity of nonzero entries. The original uniform formula, , for gravity would then create an undesirable differential treatment for features with different levels of sparsity. With a relatively small , it is very likely that a substantial proportion of features would have no non-zero values on a size- subsample used in a particular burst. The weights for these features remain unchanged after updates. Consequently, the set of sparse features run the risk of being truncated to zero based on very few informative updates. The truncation decision is therefore mostly determined by a feature’s sparsity level, rather than its relevance to the class boundary.
To make the learning be informed of the heterogeneity in sparsity level among features, we introduce the informative truncation step, extended from the idea of base gradient used in Algorithm 1. Instead of applying a universal gravity proportional to to all features, the amount of shrinkage is set proportional to the number of times that a feature is actually updated with nonzero values in the size- subsample, i.e., the number of informative updates. Specifically, within each burst, the algorithm keeps a vector of counters, , of the numbers of informative updates for the features , . Let be the base gravity parameter that serves as the unit amount of shrinkage for each informative update on each feature. At the end of each burst, we shrink feature by . In other words, here we set . The computational steps for a burst with informative truncation in summarized in Algorithm 2.
The proposed informative truncation scheme ensures that the decision of truncation is made based on sufficient and equivalent amount of evidence for evaluating each feature. A theoretical justification of how informative truncation helps improving truncation bias can be found in Lemma 2 (Section 4). This feature-specific gravity attunes to the sparsity structure incurred at each burst without ad-hoc adjustment. It also avoids data pre-processing for locating sparse entries, which can be computationally expensive and compromises the advantage of online computation. In comparison to the truncated gradient algorithm in Langford et al. (2009) that quickly shrinks many features to zero indiscriminately, informative truncation keeps sparse features until enough evaluation is conducted. In doing so, sparse yet important features will be retained. The proposed approach also reduce the variability in the resulted sparse weight vector during the training process. Duchi et al. (2011) uses a similar strategy that allows the learning algorithm to adaptively adjust its learning rates for different features based on cumulative update history. They use the norm of accumulated gradients to regulate the learning rate. By adapting the gravity with the counter within each burst, our proposed strategy here can be viewed as applying the norm to the accumulated gradients that is refreshed every steps.
### 3.2 Stability Selection
Despite of its scalability, subgradient-based online learning algorithms commonly suffer from instability. It has been shown both theoretically and empirically that stochastic gradient descent algorithms are sensitive to random perturbations in training data as well as specifications of learning rate (Toulis et al., 2015; Hardt et al., 2015). This instability is particularly pronounced in sparse online learning with sparse data, as discussed in Section 1. Under an online learning setting, using random ordering of the training sample as inputs, the algorithm would produce distinct weight vectors and unstable memberships of the final active feature set. Moreover, there has been a lot of discussion, in the literature, on the link between the instability of an learning algorithm and its deteriorated generalizability (Bousquet and Elisseeff, 2002; Kutin and Niyogi, 2002; Rakhlin et al., 2005; Shalev-Shwartz et al., 2010).
To tackle this instability issue, in the proposed algorithm, we exploit the method of stability selection to improve its robustness to random perturbation in the training data. Stability selection (Meinshausen and Bühlmann, 2010) does not launch a new feature selection method. Rather, its aim is to enhance and improve a sparse learning method via subsampling. The key idea of stability selection is similar to the generic bootstrap (Meinshausen and Bühlmann, 2010). It feeds the base feature selection procedure with multiple random subsamples to derive an empirical selection probability. Based on aggregated results from subsamples, a subset of features is selected with low variability across different subsamples. With proven consistency in variable selection, stability selection helps remove noisy irrelevant features and thus reduce the variability in learning a sparse weight vector.
Incorporating stability selection into our proposed framework, each truncated burst with gravity parameter is treated as an individual sparse learning engine. It takes random samples and carries out a feature selection to obtain a sparse weight vector. In the following, we define first the notion of selection probability for the stability selection step in our proposed algorithm.
###### Definition 1 (selection probability).
Let be a random subsample of of size , drawn without placement. Parametrized by the gravity parameter , the probability of the feature being in the active set of a truncated burst that returns is
Πgj=P∗(j∈^Sg(^w;XK))=ED[1(|^wj|>0)],
where the probability is with respect to the random subsampling of . Let .
For simplicity, we drop the superscript of in later discussions. For the rest of the paper, the selection probability always refers to that corresponds to weight vector with gravity parameter .
Under unknown data distribution, the selection probabilities cannot be computed explicitly. Instead, they are estimated empirically. Since each truncation burst performs a screening on all features, the frequency of each feature being selected by a sequence of bursts can be used to derive an estimator of the selection probability. We denote a sequence of truncated bursts as a stage. A preliminary empirical estimate of the selection probability is given by
^Πj=⎧⎪ ⎪ ⎪⎨⎪ ⎪ ⎪⎩∑τ:~kj,τ>01(|^wj,τ|>0)nk∑τ=11(~kj,τ>0),for j s.t.nK∑τ=1~kj,τ>01,otherwise, (7)
where are the counters of informative updates for burst , .
Different from the conventional stability selection setting, ’s are obtained sequentially and thus are dependent with each other. When is small, different subsamples produce selection probability estimates using (7) exhibit high variability, even when initialized with the same weight vector at . On the other hand, a large value of requires a prohibitively large number of iterations for convergence. To resolve the issues of estimating selection probability using a single sequence of SGD updates, we introduce a multi-thread framework of updating paths. Multiple threads of sequential SGD updates are executed in a distributed fashion, which readily utilizes modern multi-core computer architecture. With processors, we initialize the algorithm on each path of SGD updates with a random permutation of the training data, , denoted as . Then independently, stages of bursts run in parallel along paths, which return with , , . The joint estimate of selection probability with gravity is obtained as
^Πj=⎧⎪ ⎪ ⎪ ⎪ ⎪⎨⎪ ⎪ ⎪ ⎪ ⎪⎩M∑m=1∑τ:~k(m)j,τ>01(|^w(m)j,τ|>0)M∑m=1nk∑τ=11(~k(m)j,τ>0),for j s.t.M∑m=1nK∑τ=1~k(m)j,τ>01,otherwise. (8)
When more processors are available, a smaller is required for the algorithm to obtain a stable estimate of selection probability. The dependence among ’s is also attenuated when random subsets of samples are used for the estimation. This strategy falls under parallelized stochastic gradient descent methods, which is discussed in detail by Zinkevich et al. (2010).
Under the framework of stability selection, each stage on every path uses a random subsample. The estimated selection probability quantifies the chance that a feature is found to have high relevance to class differences given a random subsample. At the end of each stage, stable features are identified as those that belong to a large fraction of active sets incurred during this stage of bursts.
###### Definition 2 (Stable Features).
For a purging threshold , the set of stable features with gravity parameter is defined as
^Ωg={j:Πgj≥π0}. (9)
For simplicity, we write the stable set as when there is no ambiguity.
Stability selection retains features that have high selection probabilities and discard those with low selection probabilities. At the end of a stage of paths, we purge the features that are not in the set of stable features by permanently setting their corresponding weights to zero, and remove them from subsequent updates. We define the stabilized weight vector as
~w=^w⋅1^Ω. (10)
As discussed above, due to the nature of online learning with sparse data, there are two undesirable learning setbacks in a single truncated burst. The first occurs when an important feature has its weight stuck at zero due to inadequate information in the subsample used, while the second case is when a noise feature’s weight gets sporadic large updates by chance. Using informative bursts, we can avert the first type of setbacks and using selection probability based on multiple bursts, we can spot noisy features more easily. In the presence of a large number of noisy features, the learned weights for important features suffer from high variance. Via stability selection, we systematically remove noisy features permanently from the feature pool. Furthermore, the choice of a proper regularization parameter is crucial yet known to be difficult for sparse learning, especially due to the unknown noise level. Applying stability selection renders the algorithm less sensitive to choice of the base gravity parameter in learning a sparse weight vector via truncated gradient. As we will show using results from our numerical experiments, this purging by stability selection leads to a notable reduction in the estimation variance of the weight vector. Here, is a tuning parameter in practice. We have found that the learning results in the numerical experiments are not sensitive to different values of within a reasonable range. Under mild assumptions discussed in Section 4, we derive a lower bound of the expected improvement in convergence by employing stability selection in the learning process in Lemma 1.
### 3.3 Adaptive Gravity with Annealed Rejection Rate
The truncated SGD (Langford et al., 2009) adopts a universal and fixed base gravity parameter at all truncations. As pointed out in Langford et al. (2009) , a large value of the base gravity achieves more sparsity but the accuracy is compromised, while a small value of leads to less sparse weight vector yet attaining better performance. In other words, different extents of shrinkage serve different purposes of a learning algorithm. The needs for shrinkage also changes as the weight vector and the stable set evolves. Intuitively, the truncation is expected to be greedy at the beginning so that the number of nonzero feature can be quickly reduced for better computational efficiency and learning performance. As the algorithm proceeds, fewer features remain in the stable set. We should then be careful not to shrink important features with a truncation that is too harsh.
A large base gravity is effective in inducing sparsity at the beginning of the algorithm when the weight vector is dense. As the algorithm proceeds, the same value of gravity is likely to impose too much shrinkage when the learned weight vector becomes very sparse, exposing some truly important features at the risk of being purged. On the other hand, a small fixed gravity is over-conservative so that the algorithm will not shrink irrelevant features effectively, leading to slow convergence and a dense weight vector overridden by noise. Tuning a reasonable fixed base gravity parameter for a particular data set does not only creates additional computational burden, but also inadequate in addressing different learning needs during different stages of the algorithm.
As the role of gravity in a learning algorithm is to induce sparse estimates, in this paper, we propose an adaptive gravity scheme that delivers the right amount of shrinkage at each stage of the algorithm towards a desirable level of sparsity for the learned weight vector. We propose to control sparsity by a target rejection rate , that is, the proportion of updates that are expected to be truncated. Guided by this target rejection rate, we derive the necessary shrinkage amount and the corresponding gravity. As we discussed in Section 3.1, a base gravity is used in our learning algorithms to create gravity values for individual features that are attuned to their data sparsity levels. Therefore our adaptive gravity scheme is carried out by adjusting . At the beginning of a particular stage, we examine the truncations carried out during the previous stage. The base gravity is then adjusted to project the target rejection rate during the current stage. Specifically, at stage , we look at the pooled set of non-truncated weight vectors and informative truncation counters from all the bursts conducted in the previous stages on multiple threads. The adaptive base gravity for a target rejection rate is then obtained as
g0,s(βs)≜sup{g0≥0:^ps(g0)≤βs}. (11)
Here is the empirical probability, i.e.,
^ps(g0)≜M∑m=1nk∑τ=1∑{j:j∈^Ωs,~k(m)j,τ>0}1(∣∣ ∣∣Δw(m)j,τ~k(m)j,τ∣∣ ∣∣>g0)M∑m=1nk∑τ=1∑j∈^Ωs1(~k(m)j,τ>0),
where is the amount of updates on feature during the burst.
We initialize the algorithm with a high rejection rate so that a large proportion of the weight vector can be reduced to zero at the end of each burst during the early stage of the algorithm. It allows the algorithm to explore as many sparse combination of features as possible at the early stage of the learning process. Along with the stability selection, the set of stable features can be quickly reduced to a manageable size by removing the majority of noises. When the weight vector becomes sparse, we decrease the rejection rate proportionally. With a lower rejection rate, and consequently a lower gravity, the algorithm can better exploit the subsequent standard SGD updates for a more accurate estimate of the true weight vector. As the rejection rate decreases to 0, the algorithm converges to the standard stochastic gradient descent algorithm on a small subset of stable features.
To achieve the balance between exploration and exploitation, we construct an annealing function for the rejection rate that decreases monotonically as the level of sparsity decreases. Let be the maximum rejection rate at initialization and let be the annealing rate. The annealing function for the rejection rate at stage is given by
βs+1 =ϕ(ds;β0,γ) =⎧⎨⎩β0[exp(−γds)−dse−γ]γ≥0β0log(1−γ(1−ds))log(1−γ),γ<0, (12)
where is the level of weight vector sparsity at the end of stage . The greater the value is, the faster the rejection rate is annealed to zero as the number of stable features decreases.
A positive, zero and negative value of corresponds to exponential decay, linear decay and logarithmic decay of the rejection rate, respectively. Figure 2 presents examples of the rejection rate anneal function with , and respectively.
By using adaptive gravity (11) with annealed rejection rate (12), the amount of shrinkage is adjusted to the current level of sparsity of the weight vector quantified by the size of the stable set or the norm of the purged . Instead of tuning a fixed gravity parameter as in Langford et al. (2009), for our proposed algorithm, we tune the annealing rate and the maximum rejection rate . Here balances the trade-off between exploration and exploitation and determines the initial intensity of truncation. It enables the tuning process to be tailored to the data at hand as well as being comparable across different datasets. In Section 6, the tuning results instantiate that a negative annealing rate is preferred for highly sparse data, such as the RCV1 dataset, since the a high rejection rate needs to be maintained longer allowing sufficient information of sparse features to be evaluated by the learning process. On the other hand, a positive annealing rate is chosen for relatively dense data, such as the Arcene dataset, where the high frequency of nonzero values permit fast reduction of the active set. The complete algorithm of the stabilized truncated stochastic gradient descent algorithm is summarized in Algorithm 4.
## 4 Properties of the Stabilized Truncated Stochastic Gradient Descent Algorithm
The learning goal of sparse online learning is to achieve a low regret as defined in (3). In this section, we analyze the online regret bound of the proposed stabilized truncated SGD algorithm in Algorithm 4 with convex loss. For simplicity, the effect of adaptive gravity with annealed rejection rate is not considered here. To achieve viable result, we make the following assumptions.
###### Assumption 1.
The absolute values of the weight vector are bounded above, that is, for some , .
###### Assumption 2.
The loss function is convex in , and there exist non-negative constants and such that, for all and , .
For linear prediction problems, the class of loss function that satisfies Assumption 2 includes common loss functions used in machine learning problems, such as the loss, the hinge loss and the logistic loss, with the condition that for some constant .
###### Assumption 3.
Assume that the set for identifying has the following properties:
1. is the parameter space for weight vectors that is subject to a sparsity constraint
||w||0=d∗.
For the optimal weight vector , we denote and . We further assume that is sufficiently small and the gravity parameter associated with is reasonably large so that, for , the average number of active selected features from each truncated bursts, , given a gravity , is greater than or equal to .
2. Assume features has various sparsity distribution that , where , for , and if , for .
Assumption 3 posits that ’s parameter space of interest is substantially sparse, which is the main focus of sparse learning and of this paper. The theoretical analysis in the following concerns for an fixed optimal weight vector , if exists, under such a constraint. Nevertheless, this condition does not confine the applicable scenarios of the proposed method to a fixed subclass of problems. It suggests a balance between the model sparsity and the value of the gravity parameter that is implicitly embedded within the parameter tuning process.
###### Lemma 1.
Let be a non-stabilized dense weight vector, i.e., an output weight vector from Algorithm 3. Let be the stabilized weight vector derived from , which is purged by the stability selection (10) with a set of stable features . Let be the average number of nonzero entries in ’s of the previous truncated bursts, i.e.,the number of selected features from truncated bursts, with gravity . Then, if Assumption 1 holds, there exists an with such that the bound on the expected difference between the distance from the non-stabilized weight vector to under Assumption 3 and the distance from the stabilized weight vector to is given by
E(||^w−w∗||2−||~w−w∗||2) ≥ ε2(|^Sε|−|^Ω|)+2π0C2[(1−qg2π0p−p)qg−d∗] (13)
When the purging threshold is sufficiently high such that ,
E(||^w−w∗||2−||~w−w∗||2)≥0.
###### Proof.
: See Appendix A. ∎
Lemma 1 quantifies the gain of using stabilization when is highly sparse, where stability selection efficiently shrinks high variable estimates to zero. When the purging threshold is sufficiently high such that , the lower bound achieved by (13) is guaranteed to be positive. Furthermore, this result also indicates that the expected difference between distances from the non-stabilized and stabilized weight vector to the sparse depends on the differences between the sizes of the temporary nonzero set of features before purging, , and the size of the stable features after purging. In expectation, the stabilized weight vector is closer to the target sparse weight vector as the operation of purging efficiently reduces the size of stable features. This suggests a much faster convergence with stabilization. Lemma 1 also provides an insight on the benefit from using adaptive gravity with annealed rejection rate. At the beginning of the algorithm, the gap between the size of and the size of the set of stable features is large when aiming for extensive exploration of different sparse combination of features. Hence, the improvement brought by stabilization is more substantial during the early state of learning period. As the algorithm proceeds and the set of stable features becomes smaller and stabler, it dwindles the leeway that allows the aforementioned two sets to be different. Consequently, the proposed algorithm is gradually tuned toward the standard stochastic gradient descent algorithm to facilitate better convergence at the later period of the learning process.
###### Lemma 2.
Let be the weight vector at initialization. After the first burst, let be the truncated weight vector using universal gravity as in Algorithm 1 and let be the truncated weight vector with informative truncation as in Algorithm 2. Then, under Assumption 3,
E(||¯w1−w∗||2−||^w1−w∗||2)≥2g0K∑t=1∥ζtw∗∥1≥0 (14)
where for and .
###### Proof.
: See Appendix B. ∎
In Lemma 2, we compare the distances towards from 1) the weight vector with uniform gravity and 2) the weight vector with informative truncation that depends on the number of zero entries occurred in a burst. Such a gap suggests the effectiveness of informative truncation on sparse data in which feature sparsity is highly heterogeneous. In the scenarios where very few nonzero entries appear in a burst, the informative truncation imposes gravity that is proportional to the information presented in a burst. It is a fairer treatment than uniform truncation and leads to a large improvement in expectation. When features are all considerably dense in a burst, the informative truncation is equivalent to the uniform truncation.
In short, Lemma 1 demonstrates the improvement in expected squared error due to stabilization on the weight vector. Lemma 2, on the other hand, quantifies the improvements in reduce truncation bias when implementing informative truncation on sparse features with heterogeneous sparsity levels.
Given Lemma 1 and Lemma 2, we have the expected regret bound of the proposed Algorithm 4 in Theorem 1.
###### Theorem 1.
Consider the updating rules for the weight vector in Algorithm 3. On an arbitrary path, with and , let be the resulted weight vector and be the gravity values applied to the weight vectors generated by Algorithm 4, along with the base gravity parameters . Set the purging threshold to be sufficiently large such that . If Assumption 1, 2, and 3 hold, then there exists a sequence of at each stability selection with the set of stable features such that the expectation of the regret defined in (3) is bounded above by
E(T∑t=1[L(w––t,zt)+Kg–t||w––t||1]−T∑t=1[L(w∗,zt)+Kg–t||w∗||1]) ≤ ηA2−ηA(E[T∑t=1L(w∗,zt)+Kg–0,t(||w∗||1−||w––t||1)])+12−ηA(ηTB+1η||w∗||2) −12η−η2AT∑t=1ε2t1(tKnK∈Z)(|^Sεt,t|−|^Ωt|) (15)
where and is the weight vector at time before stabilization.
###### Proof.
: See Appendix C. ∎
In the result of Theorem 1, the first two parts of the right-hand-side of the expected regret bound (15) is similar to the bound obtained in Langford et al. (2009). It implies the trade-off between attained sparsity in the resulted weight vector and the regret performance. When the applied gravity is small under the joint effect of the base gravity and the size of each burst , the sparsity is less but the expected regret bound is lower. On the other hand, when the applied gravity is large, the resulted weight vector is more sparse but at the risk of higher regret. Based on Lemma 1, the proposed algorithm is guaranteed to achieve lower regret bound in expectation when the target sparse weight vector is highly sparse. As quantified in the third term of the right-hand-side of (15), the improvement comes from the reduction of the active set at each purging. By its virtue, noisy features are removed from the set of stable features and thus are absent in later SGD updates and truncations.
Theorem 1 is stated with a constant learning rate . It is possible to obtain a lower regret bound in expectation with adaptive learning rate decaying with , such as , which is commonly used in the literature of online learning and stochastic optimization. However, the discussion of using an varying learning rate is not a main focus of this paper and adds extra complexity of the analysis. Without knowing in advance, this may lead to a no-regret bound as suggested in Langford et al. (2009). Instead, in Corollary 1, we show that the convergence rate of the proposed algorithm is with .
###### Corollary 1.
Assume that all conditions of Theorem 1 are satisfied. Let the learning rate be . The upper bound of the expected regret is
where .
###### Proof.
By plugging in to the result from Theorem 1, we get
E(T∑t=1[L(w––t,zt)+g–t||w––t||1]−T∑t=1[L(w∗,zt)+g–t||w∗||1]) ≤ A2√T−A(E[T∑t=1L(w∗,zt)+g–t(||w∗||1−||w––t||1]) +T2√T−A(ηTB+1η||w∗||2)−T2√T−AT∑t=1ε2t1(tKnK∈Z)(|^Sε,t|−|^Ωt|).
The result is then straightforward. ∎
Assume that the input features have nonzero entries on average. With linear prediction model , the computational complexity at each iteration is . Leveraging the sparse structure, the informative truncation only requires an additional space for recording the counters. The purging process of stability selection consumes , , space for storing the generated intermediate weight vectors and computational complexity. Both storage and computational cost decrease when the set of stable features diminishes as the algorithm proceeds. Since the parameters , , and is normally set to be small values, the complexity mostly depends on . In summary, the proposed algorithm scales with the number of nonzero entries instead of the total dimensions, making it appealing to high-dimensional applications.
## 5 Practical Remarks
When implementing Algorithm 4 in practice, the performance can be further improved in terms of both accuracy and computational efficiency by employing a couple of practical techniques. It includes applying informative purging and attenuating the truncation frequency to achieve more accurate sparse learning and steadier convergence.
The first improvement can be implemented by better addressing the issue of scarcity of incoming samples. For computing selection probabilities, instead of using only information from the current stage, we can inherit information from previous stages for features that are too scarce to accumulate enough updates during one stage. Specifically, we introduce an accumulated counter at stage as the total number of times that a feature is updated within a burst during this stage:
κj,s=M∑m=1nK∑τ=1~k(m)j,τ,j=1,…,p,
which is essentially the denominator of the selection probability in (8). Similarly, we define an accumulated truncation indicator at stage as the total number of times that a feature is truncated to zero given valid update(s):
bj,s=M∑m=1∑τ:~k(m)j,τ>01(|^w(m)j,τ|>0),j=1,…,p.
A feature is then evaluated in the stability selection only if there are enough updates from the present stage and from any unused information carried over from previous stages. Given a threshold , let and . The selection probability is modified as
^Πj,s=⎧⎨⎩~bj,s~κs,for j s.t.~κs>δK1,otherwise, for j=1,…,p. (16)
This strategy extends the key idea in Section 3.1 that, with sparse data, each decision need to be based on sufficient evidence. Using the “carried-over” information allows the algorithm to utilize information available in a sequence of SGD updates while attuned to the needs of features with different levels of sparsity. In practice, this modification facilitates faster convergence especially for ultra-sparse data.
The second practical strategy is that the size of each burst, , can be adaptively adjusted in a similar fashion as the rejection rate in (12). At the end of each stage, the burst size is updated as
Ks=⌈K0log(1αds−1)⌉,
where is the initial burst size and, as in (12), . The tuning parameter adjusts the annealing rate of the truncation frequency. Although the result in Theorem 1 is based on a fixed , it can be easily shown that the same upper bound can also be attained with an increasing . By increasing in the later stage of the algorithm, when the majority of irrelevant features have been removed from the stable set, the chance of erroneous truncation is reduced. Such scheme further steers the algorithm from the mode of exploring potential sparse combination of features in the early stage toward the fine tuning of the weight vector by exploiting information from more samples in a sequence. It also facilitates faster convergence as the size of the stable set approaches to a sufficiently small number, as the algorithm converges to the standard stochastic gradient descent approximately.
## 6 Results
In this section, we present experimental results evaluating the performance of the proposed stabilized truncated SGD algorithm in high-dimensional classification problems with sparsity regularization. In this paper, we focus on linear prediction model for binary classification where and with the observed class label . We consider two commonly used convex loss functions in machine learning tasks that both satisfy Assumption 1:
• Hinge loss:
• Logistic loss:
Using five datasets from different domains, the performance of our algorithm and other algorithms for comparison are evaluated on classification performance and feature selection stability and sparsity. We first define measure of feature stability in Section 6.1.
### 6.1 Feature Selection Stability
The goal of sparse learning is to select a subset of truly informative features with stabilized estimation variance as well as increased classification accuracy and model interpretability. Subgradient-based online learning methods depend heavily by the random ordering of samples on which they are fed to the algorithm. Such dependence leads to much deteriorated performance when it comes to high-dimensional sparse inputs. For a particular feature, the positions of its nonzero occurrences in a random ordering of samples greatly affect its learning outcome, in terms of learnt weight and membership in the set of selected features. Therefore, in addition to attaining a low generalization error, a desirable sparse online learning method should also produce an informative feature subset that is stable and robust to random permutations of input data. To evaluate feature selection stability of subgradient-based sparse learning methods, we define in the following a numerical measure of similarity between selected feature subsets resulted from different random permutations of data. Given an output weight vector from a subgradient-based algorithm with input data , similarly as in (6), we denote the selected feature subset as
S(w––;D)={j:|w––j|>0,w––=Ψ(D}.
Given two random permutations of the training data , and , the similarity between the two sets of selected feature subsets and is measured by the Cohen’s kappa coefficient (Cohen, 1960),
κ(S1,S2)=qo−qe1−qe,
where is the relative observed agreement between and
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http://math.stackexchange.com/questions/13562/an-application-of-the-optional-sampling-theorem
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# An application of the Optional Sampling Theorem
let $S(k), k\geq 0$ a discrete random process. Suppose $S(N)$ is with probability one either 100 or 0 and that $S(0)=50$. Suppose further there is at least a sixty percent probability that the price will at some point dip below 40 and then subsequently rise above 60 before time $N$. How do you prove that $S(k)$ cannot be a martingale?
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https://classic.runescape.wiki/w/Crafting
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# Crafting
Stats Quests The RuneScape Classic Wiki Skills Fletching Attack Fishing Defense Firemaking Strength Crafting Hits Smithing Ranged Mining Prayer Herblaw Magic Agility Cooking Thieving Woodcut Quest Points Fatigue Equipment Status Armour Magic WeaponAim Prayer WeaponPower Overall levels Skill total Combat level
For information on training this skill, see Crafting training.
Crafting is a very diverse production skill in RuneScape Classic. Crafting consists of leather working, pottery making, crafting jewellery, spinning, crafting glass, and crafting battlestaves. At level 40, players may enter the Crafting Guild .
## Tools
The crafting skill requires many tools that must be kept in the inventory whilst crafting. All of the tools except the glassblowing pipe can be purchased in the Dommik's Crafting Store at the east side of Al Kharid or in the Rommik's Crafty Supplies at Rimmington. The glassblowing pipe can be found in a building on Entrana or Hemenster.
Image Name Description
Needle Used with thread for leather working.
Thread Used with a needle for leather working.
Ring mould Used to make rings.
Necklace mould Used to make necklaces.
Amulet mould Used to make amulets.
Holy symbol mould Used to make holy symbols.
Unholy symbol mould Used to make unholy symbols.
Chisel Used to cut gems.
Glassblowing pipe Used to make molten glass.
Shears Used to get wool from sheep to make a ball of wool.
## Leather Working
Leather working is a great way to start crafting, however it does require a small amount of cash to start out. In order to make leather, players need cowhides, a needle, multiple thread and some coins.
Image Name Level Experience
Leather Gloves 1 13.75
Boots 7 16.25
Leather Armour 14 25
Steps for making leather:
1. Obtain a cowhide from killing a cow. Cows can be found in Lumbridge.
2. With a cowhide and coins in your inventory, speak to the Tanner in Al Kharid to tan your cowhide. The cost is 1 coin per cowhide.
3. With a needle and thread in your inventory (Crafting supplies shop in Al Kharid), use the needle on the leather.
## Pottery
Making pottery is a great way to start crafting. Players will need to use a pottery wheel and pottery oven in order to make pottery.
Image Name Level Experience (unfired) Total Experience*
Pot 1 6.25 12.5
Pie dish 4 15 25
Bowl 7 10 25
Steps for making pottery:
1. Obtain some clay by mining a clay rock.
2. Obtain a bucket from buying one at any general store and fill it up by using it with a water source.
3. Use the bucket of water with the clay to make soft clay.
4. Use the soft clay with a pottery wheel and receive an unfired piece of pottery. A pottery wheel is found in Barbarian Village.
5. Use the unfired piece of pottery with a pottery oven. A pottery oven is found right next to the pottery wheel.
* At lower levels players may fail to fire the piece of pottery
## Gems
Cutting gems requires the player to use a chisel on an uncut gem.
Image Name Level Experience
Sapphire 20 50
Emerald 27 67.5
Ruby 34 85
Diamond 43 107.5
Dragonstone 55 137.5
### Shilo Village gems
There are also three types of gems that can be mined from gem rocks in Shilo Village. These gems can be cut for Crafting experience. However, with these you can fail this task, leaving only a Crushed Gemstone.
Image Uncut/Cut Name Level Experience Experience (Crushed)
Opal 10 15 3.75
Red topaz 16 25 6.25
## Jewellery
Jewellery is a major part of the crafting skill where players can create jewellery to wear. Each form of jewellery requires a mould, a gold bar and a gem for the type of jewellery the player wishes to create. Once a player has these materials in their inventory, using a gold bar on a furnace will allow the player to craft the jewellery. Furnaces can be found in Lumbridge, Falador, Ardougne, Al Kharid, and Lost City.
After a player has crafted an amulet from a furnace, they must complete the amulet by attaching a string to it by using a ball of wool on the amulet. This does not grant additional experience.
Rings and necklaces are relatively useless in RuneScape Classic as they cannot be enchanted through magic spells. Only the amulets can be enchanted by casting the correct enchantment spell on a fully completed amulet. See magic for more details on enchantment spells.
### Silver
Image Name Level Experience
Holy symbol 16 50
Unholy symbol 16 50
### Gold
Gold jewellery provides no bonuses and the amulet cannot be enchanted.
Image Name Level Experience
Gold ring 5 15
Gold necklace 6 20
Gold amulet 8 30
### Sapphire
Image Name Level Experience
Sapphire ring 8 40
Sapphire necklace 10 55
Sapphire amulet 13 65
### Emerald
Image Name Level Experience
Emerald ring 18 55
Emerald necklace 24 60
Emerald amulet 30 70
### Ruby
Image Name Level Experience
Ruby ring 30 70
Ruby necklace 40 75
Ruby amulet 50 85
### Diamond
Image Name Level Experience
Diamond ring 42 85
Diamond necklace 56 90
Diamond amulet 70 100
### Dragonstone
Image Name Level Experience
Dragonstone ring 54 100
Dragonstone necklace 72 105
Dragonstone amulet 80 150
## Spinning
Spinning is done on spinning wheels found throughout RuneScape Classic. Spinning wheels can be found next to the Falador east bank, upstairs in a building south west of Seers' Village bank, in the small building closest to Varrock in Barbarian Village, and upstairs in Lumbridge Castle. To spin wool or flax, simply use the item on the spinning wheel.
Image Name Level Experience Item Needed
Ball of wool 1 2.5 Wool
Bow string 10 15 Flax
## Glass Making
Making glass is a long process that requires a glassblowing pipe which can be found in a building on Entrana.
Image Name Level Experience
Molten glass 1 20
Beer glass 1 17.5
Vial 33 35
Orb 46 52.5
Steps for making glass:
1. Obtain a bucket (available from any general store).
2. Go to Entrana and use the bucket on a sand pit to get a bucket of sand.
3. On the other side of Entrana, pick up some seaweed.
4. Use the seaweed on a range giving soda ash.
5. Use the bucket of sand on a furnace while the sodium carbonate is in your inventory to receive Molten glass.
6. Use a Glassblowing pipe on the Molten glass and choose the item you wish to make.
## Battlestaves
Making elemental battlestaves is a long and involved process and requires relatively high crafting and magic levels.
Image Name Level Experience Obelisk
Battlestaff of water 54 100 Obelisk of water (Taverley dungeon)
Battlestaff of earth 58 112.5 Obelisk of earth (Edgeville dungeon)
Battlestaff of fire 62 125 Obelisk of fire (Taverley dungeon)
Battlestaff of air 66 137.5 Obelisk of air (Edgeville dungeon)
Steps for making battlestaves:
1. Obtain a battlestaff from Zaff's Superior Staves in Varrock or from Magic Guild Store.
2. Craft an unpowered orb from molten glass with a glassblowing pipe.
3. Go to the obelisk of the type of staff you want to make.
4. Cast the relevant charge orb spell on the obelisk to charge your orb.
5. Attach the charged orb to the battlestaff.
Battlestaves can also be enchanted by Thormac the sorceror upon completion of the Scorpion Catcher quest for 40,000 coins to increase the WeaponAim and WeaponPower stats from +35 to +50.
## Boosts
Item Boost Visibility
Poison chalice* 1 level Visible
* Only when the response from drinking the item is: You feel a little strange
## Quests
Crafting is used in various quests.
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https://stats.stackexchange.com/questions/109352/clustering-high-dimensional-data-p-n-in-r
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# Clustering high dimensional data (p > n) in R
I have a situation where we have a number of quantitative features / variables (p) than the number of samples (n). My objective is to classify these samples into groups (may be hierarchical). I can see a good discussion about this in this Q/A post, here at CV. I am aware of discussion about clustering based on high-dimensional data in wiki and its needs.
Here is data example for workout:
set.seed(123)
# matrix of X variable
xmat <- matrix(sample(-1:1, 2000000, replace = TRUE), ncol = 10000)
colnames(xmat) <- paste ("M", 1:10000, sep ="")
rownames(xmat) <- paste("sample", 1:200, sep = "")
Here are my questions:
1. What would be best approach ?
2. I am interested to find implementation codes for a suitable method (may be Subspace clustering or Projected clustering or Correlation clustering or Hybrid approaches) for my case.
First some background:
R is good choice and have so many clustering methods in different packages. The functions include Hierarchical Clustering, Partitioning Clustering, Model-Based Clustering, and Cluster-wise Regression.
Connectivity based clustering or Hierarchical clustering (also called hierarchical cluster analysis or HCA) is a method of cluster analysis which seeks to build a hierarchy of clusters. Strategies for hierarchical clustering generally fall into two types:
• Agglomerative: This is a "bottom up" approach: each observation starts in its own cluster, and pairs of clusters are merged as one moves up the hierarchy.
• Divisive: This is a "top down" approach: all observations start in one cluster, and splits are performed recursively as one moves down the hierarchy. In this method, at different distances, different clusters will form, which can be represented using a dendrogram.
Centroid-based clustering: In centroid-based clustering, clusters are represented by a central vector, which may not necessarily be a member of the data set. When the number of clusters is fixed to k, k-means clustering gives a formal definition as an optimization problem: find the k cluster centers and assign the objects to the nearest cluster center, such that the squared distances from the cluster are minimized.
km <- kmeans(iris[,1:4], 3)
plot(iris[,1], iris[,2], col=km$cluster) points(km$centers[,c(1,2)], col=1:3, pch=8, cex=2)
table(km$cluster, iris$Species)
Distribution-based clustering: the clustering model most closely related to statistics is based on distribution models. Clusters can then easily be defined as objects belonging most likely to the same distribution. The problem is overfitting.
Density-based clustering: n density-based clustering,[8] clusters are defined as areas of higher density than the remainder of the data set. Objects in these sparse areas - that are required to separate clusters - are usually considered to be noise and border points.
In density based cluster, a cluster is extend along the density distribution. Two parameters is important: "eps" defines the radius of neighborhood of each point, and "minpts" is the number of neighbors within my "eps" radius. The basic algorithm called DBscan proceeds as follows:
First scan: For each point, compute the distance with all other points. Increment a neighbor count if it is smaller than "eps".
Second scan: For each point, mark it as a core point if its neighbor count is greater than "mints"
Third scan: For each core point, if it is not already assigned a cluster, create a new cluster and assign that to this core point as well as all of its neighbors within "eps" radius.
Unlike other cluster, density based cluster can have some outliers (data points that doesn't belong to any clusters). On the other hand, it can detect cluster of arbitrary shapes (doesn't have to be circular at all).
library(fpc)
# eps is radius of neighborhood, MinPts is no of neighbors
# within eps
cluster <- dbscan(sampleiris[,-5], eps=0.6, MinPts=4)
plot(cluster, sampleiris)
plot(cluster, sampleiris[,c(1,4)])
# Notice points in cluster 0 are unassigned outliers
table(cluster$cluster, sampleiris$Species)
With the recent need to process larger and larger data sets (also known as big data), the willingness to trade semantic meaning of the generated clusters for performance has been increasing. This led to the development of pre-clustering methods such as canopy clustering, which can process huge data sets efficiently, but the resulting "clusters" are merely a rough pre-partitioning of the data set to then analyze the partitions with existing slower methods such as k-means clustering.
For high-dimensional data, many of the existing methods fail due to the curse of dimensionality, which renders particular distance functions problematic in high-dimensional spaces. This led to new clustering algorithms for high-dimensional data that focus on subspace clustering (where only some attributes are used, and cluster models include the relevant attributes for the cluster) and correlation clustering that also looks for arbitrary rotated ("correlated") subspace clusters that can be modeled by giving a correlation of their attributes. The three clustering algorithms include PROCLUS, P3C and STATPC.
The package Package ‘orclus’ is available to perform subspace clustering and classification. The following is example from the manual:
# definition of a function for parameterized data simulation
sim.orclus <- function(k = 3, nk = 100, d = 10, l = 4, sd.cl = 0.05, sd.rest = 1, locshift = 1){
### input parameters for data generation
# k # nk # d # l
# sd.cl
# sd.rest # locshift
number of clusters
observations per cluster
original dimension of the data
subspace dimension where the clusters are concentrated
(univariate) standard deviations for data generation (within cluster subspace concentration) standard deviations in the remaining space
parameter of a uniform distribution to sample different cluster means
x <- NULL
for(i in 1:k){
# cluster centers
apts <- locshift*matrix(runif(l*k), ncol = l)
# sample points in original space
xi.original <- cbind(matrix(rnorm(nk * l, sd = sd.cl), ncol=l) + matrix(rep(apts[i,], nk), ncol = l, byrow = TRUE)
matrix(rnorm(nk * (d-l), sd = sd.rest), ncol = (d-l)))
# subspace generation
sym.mat <- matrix(nrow=d, ncol=d)
for(m in 1:d){
for(n in 1:m){
sym.mat[m,n] <- sym.mat[n,m] <- runif(1)
}
}
subspace <- eigen(sym.mat)$vectors # transformation xi.transformed <- xi.original %*% subspace x <- rbind(x, xi.transformed) } clids <- rep(1:k, each = nk) result <- list(x = x, cluster = clids) return(result) } # simulate data of 2 classes where class 1 consists of 2 subclasses simdata <- sim.orclus(k = 3, nk = 200, d = 15, l = 4, sd.cl = 0.05, sd.rest = 1, locshift = 1) x <- simdata$x
y <- c(rep(1,400), rep(2,200))
res <- orclass(x, y, k = 3, l = 4, k0 = 15, a = 0.75)
res
# compare results
table(res$predict.train$class, y)
You may also be interested in HDclassif (An R Package for Model-Based Clustering and Discriminant Analysis of High-Dimensional Data).
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https://www.physicsforums.com/threads/interesting-analytical-chem-problem.634008/
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# Interesting Analytical Chem Problem
1. Sep 6, 2012
### ghelman
Hi all,
I need to solve this problem for my environmental chemistry class. It is supposed to be a "review" problem of concepts from analytical and gen. chem. but I certainly do not know how to do it.
1. The problem statement, all variables and given/known data
If you work at the wastewater treatment plant, you are exposed to 1,4-dichlorobenzene, which is used in urinal deodorant cakes.
a. If you work in a 500 m3 space with an exposed body of wastewater and can still smell the DCB (smell threshold 500 ppbv) what is the concentration of DCB in the water?
b. In the winter the temperature of the water falls to 5C and you can no longer smell the DCB; what is the maximum concentration of DCB in the water at the new temperature?
3. The attempt at a solution
V=500 m3
CDCB=500 parts per billion by volume
P=1 atm (assumably)
I assume that the wastewater plant operates at a temperature of 25o C. I am not sure if that is a good assumption or not. Anyone have any insight to that?
I also assumed that the system is in equilibrium. I am not sure if I am allowed to assume that, but it seems reasonable. Doing so gives:
Vapor pressure of DCB = 1.76 mm Hg
At this point I do not know what to do. I have a concentration for DCB in air, but how do I relate that to the concentration of DCB in water at equilibrium?
I know that the fugacities will be equal at equilibrium, but I am not sure whether that will be useful or if it is just a wild goose chase.
Help!
2. Sep 7, 2012
### AGNuke
1.) Assumption is justified. 25°C is totally justified. It is a standard Temperature.
2.) Henry's Law for conc. of DCB in water?
3. Sep 9, 2012
### ghelman
Hmmmm...but how would using Henry's Law make use of the given concentration in the air?
4. Sep 10, 2012
### Staff: Mentor
Unless I am missing something, there is not enough data to solve the problem.
And no idea how you got 1.76 mmHg.
5. Sep 10, 2012
### ghelman
I got the vapor pressure from a research article. We are allowed to look up any values we think we may need. Given that, what will we need to know in order to solve the problem?
6. Sep 10, 2012
### Staff: Mentor
It is probably vapor pressure over a solid DCB at STP - so of no use here (unless it can be somehow related to solubility/pressure over solution). You need either a Henry's constant, or some kind of information that will let you calculate it.
7. Sep 10, 2012
### ghelman
I can probably find an article with a Henry's law constant, but if I solved it that way, how would that make use of the given concentration? Also, how would I solve part b?
8. Sep 10, 2012
### Staff: Mentor
Huh? Simple plug and chug. Or is your problem conversion between concentration and partial pressure?
Assuming Henry's constant is not temperature dependent. Or using value for 5°C. It is almost exactly the same problem.
9. Sep 10, 2012
### ghelman
So would I assume that the system is in equilibrium and use the vapor pressure as the partial pressure in Henry's Law? If I did that then how would I use the given concentration of 500 ppbv?
Or am I supposed to plug in the given concentration and solve for the partial pressure? But then what would I do with that?
10. Sep 10, 2012
### AGNuke
Convert 500ppbv into partial pressure. That's the amount of DCB in atmosphere, by volume, and by ideality (which we generally consider to make our life at least not miserable) 500ppb(pressure).
11. Sep 10, 2012
### JohnRC
(1) I suspect that the "given" 500 cubic metre of workspace is irrelevant except insofar as it suggests an environment where the vapour phase DCB will be in equilibrium with the liquid phase DCB -- that is, that the volume is fairly small, and suggests an enclosed, draught free workspace.
(2) I also think that it is important to remember that you are dealing with inequalities here -- the conc of DCB is not = 500 ppbv but >= 500 ppbv
(3) The equilibrium vapour pressure of the solid is relevant if you combine it with the (low) solubility of the solid in water, because the PCB activity in the solid is 1, and so the PCB concentration in the solution will therefore be equal to the same proportion of the saturation concentration as that of the vapour is to the saturated vapour in equilibrium with the solid (as expressed in the saturation vapour pressure).
(4) Wastewater facilities are usually kept to around 5-10°C if the outdoor temperature is below freezing, but they are usually places where no other heating or cooling is applied. If a temperature is not specified, an assumption of 15°, 20° or 25 °C would be reasonable.
12. Sep 11, 2012
### Staff: Mentor
If you have air at 1 atm, and 21% of the air by volume is oxygen (in other words: concentration of oxygen is 21% v/v), what is the partial pressure of oxygen?
This is an application of Avogadro's principle.
13. Sep 11, 2012
### JohnRC
I do not believe that an answer like this is really grasping the difficult part of this problem, which hinges on how to relate a concentration in air to a concentration in aqueous solution
(Borek again):
A datum like this can be brought into the solution of the problem, since the saturation vapour pressure is effectively the "solubility" of the solid in air, which can be matched to the actual solubility of the solid in water, and provide the information needed to match other airborne and aqueous concentrations.
14. Sep 11, 2012
### Staff: Mentor
My understanding of the situation is that OP has no idea how to convert 500 ppb to partial pressure (at least that's what I read between lines in earlier posts). Without doing this (simple) step, you can't proceed with the more difficult part.
If I understand you correctly you want to assume activity of the DCP to be the same in the air and in the solution? Perhaps it will work, I have never seen it done this way (but I am far from claiming I have seen everything, quite the opposite).
15. Sep 11, 2012
### JohnRC
Not the activity, but the chemical potential -- the chemical potential must be equal in the solid, the saturated vapour, and the saturated solution. The last two can therefore be equated and scaled down to lower concentrations. This is really just the fugacity or Henry's law approach in another guise, and an accurate solubility figure for DCB can be fairly easily obtained.
Similar Discussions: Interesting Analytical Chem Problem
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https://www.physicsforums.com/threads/verilog-display-module.749936/
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# Verilog Display module
1. Apr 21, 2014
### Drao92
Hello,
I have to make a Display module in verilog and first time i want to create a ball which is moving and i have a question, the vertial/horizontal synchronization module is done, the question is about displaying the image using RGB. So, i use 640x480 display and 25Mhz clock frequency and first time when i created the module i didnt took in consideration that the fpga displays 60 frames in 1.15 second and i wrote somthing like move evreytime when x=? and y=? with 2px and then i realised that i wouldnt be able to see the image because it will be moving too fast. Aint i am right??? I was thinking to implement a counter which counts the number of frames and makes the ball to move every 20, 30, 40 frames. So first of all i want to ask if it is right what i am saying and in this case what is the best delay to chose?
Also, i will have acces to the the FPGA to test the modules in a few days, i dont know whats happening in reality :D. I only simulated the HV signals in modelsim and they look good.
Last edited: Apr 21, 2014
2. Apr 21, 2014
### meBigGuy
I would look at the final result. There is probably no issue. 480p updates at 60Hz, movies at 24Hz, 480i at interleaved 60Hz. Let's say you moved 5 pixels every frame. That will move a ball across the screen in 640/5 or about 150 frames which is over 2 seconds. 1/2 second isn't unreasonable which is over 20 pixels per frame.
3. Apr 22, 2014
### Drao92
I want to ask 1 more thing. What is happening if i dont give a specific value to a pixel? its black by default?
For exemple:
if(x>30&&x<80&&y>30&&y<50) begin
R=3b111;
G=3b000;
B=2b00;
end
The pixels of the specified area in if statement will be red, but what is happening with the others? Do i have to make an else and to give them a color or its automatically black?
4. Apr 22, 2014
### meBigGuy
Depends on the surrounding code. What do you set R, G, B to for other values of x and y. For example if you set R,G,B to 0 before you enter the "if", then they would be 0 by default if the "if" was not entered.
Question: What value do you think they would be if you didn't set them to a default value? Where would that value come from?
Question: What happens when you don't define all possible states for a case statement (or a sequence of if-else statements)?
Last edited: Apr 22, 2014
5. Apr 28, 2014
### Drao92
Hello, I have some problems with implementing a vga controller on a nexys 2 fpga board.The HV synchronization module works fine at first view, monitors says it displays the right resolution 640x480. The problem is that the RGB module doesnt display what i write to do. For exmple for the folowing code it displays black instead of green and purple instead of white.
if(posx<=60&&posy<=100) begin
red<=3'b000;
green<=3'b111;
blue<=2'b00;
end else begin
blue<=2'b11;
red<=3'b111;
green<=3'b111;
end
Also for the next code it displays for 60x100 area green and if posy<100 and posx>60 it displays blue and rest of the screen is black... and it should display in 60x100 green and the rest of the screen must be blue.
if(posx<=60&&posy<=100) begin
red<=3'b000;
green<=3'b111;
blue<=2'b00;
end else begin
blue<=2'b11;
red<=3'b000;
green<=3'b000;
end
Does anybody had such problems and know what its wrong???
This is the UFC file.
net "clk50" loc = "B8";
net "HS" loc = "T4" ;
net "VS" loc = "U3";
net "red[0]" loc = "R9";
net "red[1]" loc = "T8";
net "red[2]" loc = "R8";
net "green[0]" loc = "N8";
net "green[1]" loc = "P8";
net "green[2]" loc = "P6";
net "blue[0]" loc = "U5";
net "blue[1]" loc = "U4";
6. Apr 29, 2014
### meBigGuy
first just display 1 color at a time on the whole screen to debug the color channels. Then once that is sorted out the rest will be easy.
7. Apr 29, 2014
### Drao92
If i dont put an if or else statement it doesnt display anything. Ill try to create another sync module. I think the one i use at this moment its buggy.
8. Apr 29, 2014
### meBigGuy
I have no idea what your code does overall.
If you just set red, green, blue in the always block, it should drive those pins to what you set them, which should be easy enough to probe.
9. May 2, 2014
### Drao92
I will display the code. It makes me crazy, it works like a paranormal thing :D.
The problem is the following. In RGB module in the always block if i say red<=x value, green <=y value etc it doesnt display anything, i must use an if-else statement to display anything. With the current code from RGB it displays a black rectangler for the positions posx<=60, posy<=100 only what is above posy=100 is magenta, the rest of the screen is black. So in this case if i combine green with red or blue, green it doesnt work. On the other hand, if i dont combine green with anything, it displays the right colors, but in the same way, with an if-else statement and anything below posy is black.
meBigGuy thanks for trying to help me. As i said above, i cant display any color without if-else. If i must use if posx<=639 && posy<=479 --- give values to red,green,blue else give other values to red green blue.
If i dont use the else it doesnt display any color, if i use if-else it displays the colors from if statements and the colors which must be displayed in else arent displayed below the value of posy from if.... I cant understand what is the reason of this.
Code (Text):
module VGASync(
input clock,
output reg HS,
output reg VS,
output reg [9:0] posx,
output reg [9:0] posy);
parameter hsync_width=799;
parameter hsync_fall=655; //pozitia unde se termina front porch sau unde semnalul devin 0
parameter hsync_rise=751; //pozitia unde incepe back porch sau unde semnalul revine la 1
parameter vsync_width=524;
parameter vsync_fall=490; //pozitia unde se termina front porch sau unde semnalul devin 0
parameter vsync_rise=492; //pozitia unde incepe back porch sau unde semnalul revine la 1
always @(posedge clock) begin
if(posx >= hsync_fall && posx < hsync_rise) begin
HS=0;
end else begin
HS=1;
end
if(posy >= vsync_fall && posy < vsync_rise) begin
VS=0;
end else begin
VS=1;
end
if (posx < hsync_width) begin
posx<=posx+1;
end else begin
posx<=0;
if(posy < vsync_width) begin
posy<=posy+1;
end else begin
posy<=0;
end
end
end
endmodule
Code (Text):
module RGB(
input clock,
input [9:0] posx,
input [9:0] posy,
output reg [2:0] red,
output reg [2:0] green,
output reg [1:0] blue
);
reg [6:0] size=0;
always @(posedge clock)begin
if(posx<=60&&posy<=100) begin
red<=3'b000;
green<=3'b111;
blue<=2'b00;
end else begin
blue<=2'b11;
red<=3'b111;
green<=3'b111;
end
end
endmodule
Code (Text):
module clock(
input clk50,
output clk25
);
reg clk25_int;
always @(posedge clk50) begin
clk25_int<=~clk25_int;
end
BUFG buffer(.I(clk25_int),.O(clk25));
endmodule
Code (Text):
module testop(
input clk50,
output HS,
output VS,
output [2:0] red,
output [2:0] green,
output [1:0] blue
);
wire clk25;
wire [9:0] posx;
wire [9:0] posy;
clock clock_inst(.clk50(clk50),
.clk25(clk25));
VGASync VGASync_inst(.clock(clk25),
.HS(HS),
.VS(VS),
.posx(posx),
.posy(posy));
RGB RGB_inst(.clock(clk25),
.posx(posx),
.posy(posy),
.red(red),
.green(green),
.blue(blue));
endmodule
Last edited: May 2, 2014
10. May 3, 2014
### meBigGuy
If you have a simulator, then that is the way to do it. Build a testbench and look at waveforms.
I expect the IO is incorrectly connected/defined. I don't see anything obvious in your code.
I would set 1 color at a time in the if and make sure what I am seeing makes sense. Set the else section to all zeros. Or, just do the opposite. set the if portion to zero and set the else portion.
Try all ones for 1 color to start. Then verify each bit works for the color.
Regarding the verilog itself:
It is a good idea to name module outputs with _o and inputs with _i. Really helps with reading the code.
Also, line up the begin ends in whatever consistent method you want to use.
Similar Discussions: Verilog Display module
|
{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.19996652007102966, "perplexity": 5728.969531475259}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-39/segments/1505818687833.62/warc/CC-MAIN-20170921153438-20170921173438-00599.warc.gz"}
|
http://www.quanty.org/documentation/standard_operators/spin/sy
|
# Sy
The $S_y$ operator is defined as: $$S_y = \sum_{\tau} \frac{\imath}{2}\left(-a^{\dagger}_{\tau\uparrow}a^{\phantom{\dagger}}_{\tau\downarrow} + a^{\dagger}_{\tau\downarrow}a^{\phantom{\dagger}}_{\tau\uparrow}\right).$$ The equivalent operator in Quanty is created by:
Example.Quanty
OppSy = NewOperator("Sy", NF, IndexUp, IndexDn)
|
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|
https://worldwidescience.org/topicpages/a/auditory+feedback+differs.html
|
Sample records for auditory feedback differs
1. Different Auditory Feedback Control for Echolocation and Communication in Horseshoe Bats
OpenAIRE
Ying Liu; Jiang Feng; Walter Metzner
2013-01-01
Auditory feedback from the animal's own voice is essential during bat echolocation: to optimize signal detection, bats continuously adjust various call parameters in response to changing echo signals. Auditory feedback seems also necessary for controlling many bat communication calls, although it remains unclear how auditory feedback control differs in echolocation and communication. We tackled this question by analyzing echolocation and communication in greater horseshoe bats, whose echoloca...
2. Effect of auditory feedback differs according to side of hemiparesis: a comparative pilot study
Directory of Open Access Journals (Sweden)
Bensmail Djamel
2009-12-01
Full Text Available Abstract Background Following stroke, patients frequently demonstrate loss of motor control and function and altered kinematic parameters of reaching movements. Feedback is an essential component of rehabilitation and auditory feedback of kinematic parameters may be a useful tool for rehabilitation of reaching movements at the impairment level. The aim of this study was to investigate the effect of 2 types of auditory feedback on the kinematics of reaching movements in hemiparetic stroke patients and to compare differences between patients with right (RHD and left hemisphere damage (LHD. Methods 10 healthy controls, 8 stroke patients with LHD and 8 with RHD were included. Patient groups had similar levels of upper limb function. Two types of auditory feedback (spatial and simple were developed and provided online during reaching movements to 9 targets in the workspace. Kinematics of the upper limb were recorded with an electromagnetic system. Kinematics were compared between groups (Mann Whitney test and the effect of auditory feedback on kinematics was tested within each patient group (Friedman test. Results In the patient groups, peak hand velocity was lower, the number of velocity peaks was higher and movements were more curved than in the healthy group. Despite having a similar clinical level, kinematics differed between LHD and RHD groups. Peak velocity was similar but LHD patients had fewer velocity peaks and less curved movements than RHD patients. The addition of auditory feedback improved the curvature index in patients with RHD and deteriorated peak velocity, the number of velocity peaks and curvature index in LHD patients. No difference between types of feedback was found in either patient group. Conclusion In stroke patients, side of lesion should be considered when examining arm reaching kinematics. Further studies are necessary to evaluate differences in responses to auditory feedback between patients with lesions in opposite
3. Different auditory feedback control for echolocation and communication in horseshoe bats.
Directory of Open Access Journals (Sweden)
Ying Liu
Full Text Available Auditory feedback from the animal's own voice is essential during bat echolocation: to optimize signal detection, bats continuously adjust various call parameters in response to changing echo signals. Auditory feedback seems also necessary for controlling many bat communication calls, although it remains unclear how auditory feedback control differs in echolocation and communication. We tackled this question by analyzing echolocation and communication in greater horseshoe bats, whose echolocation pulses are dominated by a constant frequency component that matches the frequency range they hear best. To maintain echoes within this "auditory fovea", horseshoe bats constantly adjust their echolocation call frequency depending on the frequency of the returning echo signal. This Doppler-shift compensation (DSC behavior represents one of the most precise forms of sensory-motor feedback known. We examined the variability of echolocation pulses emitted at rest (resting frequencies, RFs and one type of communication signal which resembles an echolocation pulse but is much shorter (short constant frequency communication calls, SCFs and produced only during social interactions. We found that while RFs varied from day to day, corroborating earlier studies in other constant frequency bats, SCF-frequencies remained unchanged. In addition, RFs overlapped for some bats whereas SCF-frequencies were always distinctly different. This indicates that auditory feedback during echolocation changed with varying RFs but remained constant or may have been absent during emission of SCF calls for communication. This fundamentally different feedback mechanism for echolocation and communication may have enabled these bats to use SCF calls for individual recognition whereas they adjusted RF calls to accommodate the daily shifts of their auditory fovea.
4. Representation of Reward Feedback in Primate Auditory Cortex
Directory of Open Access Journals (Sweden)
Michael eBrosch
2011-02-01
Full Text Available It is well established that auditory cortex is plastic on different time scales and that this plasticity is driven by the reinforcement that is used to motivate subjects to learn or to perform an auditory task. Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback. We recorded from the auditory cortex of two monkeys while they were performing an auditory categorization task. Monkeys listened to a sequence of tones and had to signal when the frequency of adjacent tones stepped in downward direction, irrespective of the tone frequency and step size. Correct identifications were rewarded with either a large or a small amount of water. The size of reward depended on the monkeys' performance in the previous trial: it was large after a correct trial and small after an incorrect trial. The rewards served to maintain task performance. During task performance we found three successive periods of neuronal firing in auditory cortex that reflected (1 the reward expectancy for each trial, (2 the reward size received and (3 the mismatch between the expected and delivered reward. These results, together with control experiments suggest that auditory cortex receives reward feedback that could be used to adapt auditory cortex to task requirements. Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized.
5. Representation of reward feedback in primate auditory cortex.
Science.gov (United States)
Brosch, Michael; Selezneva, Elena; Scheich, Henning
2011-01-01
It is well established that auditory cortex is plastic on different time scales and that this plasticity is driven by the reinforcement that is used to motivate subjects to learn or to perform an auditory task. Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback. We recorded from the auditory cortex of two monkeys while they were performing an auditory categorization task. Monkeys listened to a sequence of tones and had to signal when the frequency of adjacent tones stepped in downward direction, irrespective of the tone frequency and step size. Correct identifications were rewarded with either a large or a small amount of water. The size of reward depended on the monkeys' performance in the previous trial: it was large after a correct trial and small after an incorrect trial. The rewards served to maintain task performance. During task performance we found three successive periods of neuronal firing in auditory cortex that reflected (1) the reward expectancy for each trial, (2) the reward-size received, and (3) the mismatch between the expected and delivered reward. These results, together with control experiments suggest that auditory cortex receives reward feedback that could be used to adapt auditory cortex to task requirements. Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized.
6. Formant compensation for auditory feedback with English vowels
DEFF Research Database (Denmark)
Mitsuya, Takashi; MacDonald, Ewen N; Munhall, Kevin G;
2015-01-01
Past studies have shown that speakers spontaneously adjust their speech acoustics in response to their auditory feedback perturbed in real time. In the case of formant perturbation, the majority of studies have examined speaker's compensatory production using the English vowel /ɛ/ as in the word...... to differences in the degree of lingual contact or jaw openness. This may in turn influence the ways in which speakers compensate for auditory feedback. The aim of the current study was to examine speakers' compensatory behavior with six English monophthongs. Specifically, the current study tested to see...
7. Altered Sensory Feedbacks in Pianist's Dystonia: the altered auditory feedback paradigm and the glove effect
Directory of Open Access Journals (Sweden)
Felicia Pei-Hsin Cheng
2013-12-01
Full Text Available Background: This study investigates the effect of altered auditory feedback (AAF in musician's dystonia (MD and discusses whether altered auditory feedback can be considered as a sensory trick in MD. Furthermore, the effect of AAF is compared with altered tactile feedback, which can serve as a sensory trick in several other forms of focal dystonia. Methods: The method is based on scale analysis (Jabusch et al. 2004. Experiment 1 employs synchronization paradigm: 12 MD patients and 25 healthy pianists had to repeatedly play C-major scales in synchrony with a metronome on a MIDI-piano with 3 auditory feedback conditions: 1. normal feedback; 2. no feedback; 3. constant delayed feedback. Experiment 2 employs synchronization-continuation paradigm: 12 MD patients and 12 healthy pianists had to repeatedly play C-major scales in two phases: first in synchrony with a metronome, secondly continue the established tempo without the metronome. There are 4 experimental conditions, among them 3 are the same altered auditory feedback as in Experiment 1 and 1 is related to altered tactile sensory input. The coefficient of variation of inter-onset intervals of the key depressions was calculated to evaluate fine motor control. Results: In both experiments, the healthy controls and the patients behaved very similarly. There is no difference in the regularity of playing between the two groups under any condition, and neither did AAF nor did altered tactile feedback have a beneficial effect on patients’ fine motor control. Conclusions: The results of the two experiments suggest that in the context of our experimental designs, AAF and altered tactile feedback play a minor role in motor coordination in patients with musicians' dystonia. We propose that altered auditory and tactile feedback do not serve as effective sensory tricks and may not temporarily reduce the symptoms of patients suffering from MD in this experimental context.
8. Feedback delays eliminate auditory-motor learning in speech production.
Science.gov (United States)
Max, Ludo; Maffett, Derek G
2015-03-30
Neurologically healthy individuals use sensory feedback to alter future movements by updating internal models of the effector system and environment. For example, when visual feedback about limb movements or auditory feedback about speech movements is experimentally perturbed, the planning of subsequent movements is adjusted - i.e., sensorimotor adaptation occurs. A separate line of studies has demonstrated that experimentally delaying the sensory consequences of limb movements causes the sensory input to be attributed to external sources rather than to one's own actions. Yet similar feedback delays have remarkably little effect on visuo-motor adaptation (although the rate of learning varies, the amount of adaptation is only moderately affected with delays of 100-200ms, and adaptation still occurs even with a delay as long as 5000ms). Thus, limb motor learning remains largely intact even in conditions where error assignment favors external factors. Here, we show a fundamentally different result for sensorimotor control of speech articulation: auditory-motor adaptation to formant-shifted feedback is completely eliminated with delays of 100ms or more. Thus, for speech motor learning, real-time auditory feedback is critical. This novel finding informs theoretical models of human motor control in general and speech motor control in particular, and it has direct implications for the application of motor learning principles in the habilitation and rehabilitation of individuals with various sensorimotor speech disorders.
9. Weak responses to auditory feedback perturbation during articulation in persons who stutter: evidence for abnormal auditory-motor transformation.
Directory of Open Access Journals (Sweden)
Shanqing Cai
Full Text Available Previous empirical observations have led researchers to propose that auditory feedback (the auditory perception of self-produced sounds when speaking functions abnormally in the speech motor systems of persons who stutter (PWS. Researchers have theorized that an important neural basis of stuttering is the aberrant integration of auditory information into incipient speech motor commands. Because of the circumstantial support for these hypotheses and the differences and contradictions between them, there is a need for carefully designed experiments that directly examine auditory-motor integration during speech production in PWS. In the current study, we used real-time manipulation of auditory feedback to directly investigate whether the speech motor system of PWS utilizes auditory feedback abnormally during articulation and to characterize potential deficits of this auditory-motor integration. Twenty-one PWS and 18 fluent control participants were recruited. Using a short-latency formant-perturbation system, we examined participants' compensatory responses to unanticipated perturbation of auditory feedback of the first formant frequency during the production of the monophthong [ε]. The PWS showed compensatory responses that were qualitatively similar to the controls' and had close-to-normal latencies (∼150 ms, but the magnitudes of their responses were substantially and significantly smaller than those of the control participants (by 47% on average, p<0.05. Measurements of auditory acuity indicate that the weaker-than-normal compensatory responses in PWS were not attributable to a deficit in low-level auditory processing. These findings are consistent with the hypothesis that stuttering is associated with functional defects in the inverse models responsible for the transformation from the domain of auditory targets and auditory error information into the domain of speech motor commands.
10. Temporal coordination in joint music performance: effects of endogenous rhythms and auditory feedback.
Science.gov (United States)
Zamm, Anna; Pfordresher, Peter Q; Palmer, Caroline
2015-02-01
Many behaviors require that individuals coordinate the timing of their actions with others. The current study investigated the role of two factors in temporal coordination of joint music performance: differences in partners' spontaneous (uncued) rate and auditory feedback generated by oneself and one's partner. Pianists performed melodies independently (in a Solo condition), and with a partner (in a duet condition), either at the same time as a partner (Unison), or at a temporal offset (Round), such that pianists heard their partner produce a serially shifted copy of their own sequence. Access to self-produced auditory information during duet performance was manipulated as well: Performers heard either full auditory feedback (Full), or only feedback from their partner (Other). Larger differences in partners' spontaneous rates of Solo performances were associated with larger asynchronies (less effective synchronization) during duet performance. Auditory feedback also influenced temporal coordination of duet performance: Pianists were more coordinated (smaller tone onset asynchronies and more mutual adaptation) during duet performances when self-generated auditory feedback aligned with partner-generated feedback (Unison) than when it did not (Round). Removal of self-feedback disrupted coordination (larger tone onset asynchronies) during Round performances only. Together, findings suggest that differences in partners' spontaneous rates of Solo performances, as well as differences in self- and partner-generated auditory feedback, influence temporal coordination of joint sensorimotor behaviors.
11. Effects of visual and auditory feedback on sensorimotor circuits in the basal ganglia.
Science.gov (United States)
Prodoehl, Janey; Yu, Hong; Wasson, Pooja; Corcos, Daniel M; Vaillancourt, David E
2008-06-01
Previous work using visual feedback has identified two distinct sensorimotor circuits in the basal ganglia (BG): one that scaled with the duration of force and one that scaled with the rate of change of force. The present study compared functional MRI signal changes in the BG during a grip force task using either visual or auditory feedback to determine whether the BG nuclei process auditory and visual feedback similarly. We confirmed the same two sensorimotor circuits in the BG. Activation in the striatum and external globus pallidus (GPe) scaled linearly with the duration of force under visual and auditory feedback conditions, with similar slopes and intercepts across feedback type. The pattern of signal change for the internal globus pallidus (GPi) and subthalamic nucleus (STN) was nonlinear and parameters of the exponential function were altered by feedback type. Specifically, GPi and STN activation decreased exponentially with the rate of change of force. The rate constant and asymptote of the exponential functions for GPi and STN were greater during auditory than visual feedback. In a comparison of the BOLD signal between BG regions, GPe had the highest percentage of variance accounted for and this effect was preserved for both feedback types. These new findings suggest that neuronal activity of specific BG nuclei is affected by whether the feedback is derived from visual or auditory inputs. Also, the data are consistent with the hypothesis that the GPe has a high level of information convergence from other BG nuclei, which is preserved across different sensory feedback modalities.
12. Effect of task-related continuous auditory feedback during learning of tracking motion exercises
Directory of Open Access Journals (Sweden)
Rosati Giulio
2012-10-01
Full Text Available Abstract Background This paper presents the results of a set of experiments in which we used continuous auditory feedback to augment motor training exercises. This feedback modality is mostly underexploited in current robotic rehabilitation systems, which usually implement only very basic auditory interfaces. Our hypothesis is that properly designed continuous auditory feedback could be used to represent temporal and spatial information that could in turn, improve performance and motor learning. Methods We implemented three different experiments on healthy subjects, who were asked to track a target on a screen by moving an input device (controller with their hand. Different visual and auditory feedback modalities were envisaged. The first experiment investigated whether continuous task-related auditory feedback can help improve performance to a greater extent than error-related audio feedback, or visual feedback alone. In the second experiment we used sensory substitution to compare different types of auditory feedback with equivalent visual feedback, in order to find out whether mapping the same information on a different sensory channel (the visual channel yielded comparable effects with those gained in the first experiment. The final experiment applied a continuously changing visuomotor transformation between the controller and the screen and mapped kinematic information, computed in either coordinate system (controller or video, to the audio channel, in order to investigate which information was more relevant to the user. Results Task-related audio feedback significantly improved performance with respect to visual feedback alone, whilst error-related feedback did not. Secondly, performance in audio tasks was significantly better with respect to the equivalent sensory-substituted visual tasks. Finally, with respect to visual feedback alone, video-task-related sound feedback decreased the tracking error during the learning of a novel
13. Selective and divided attention modulates auditory-vocal integration in the processing of pitch feedback errors.
Science.gov (United States)
Liu, Ying; Hu, Huijing; Jones, Jeffery A; Guo, Zhiqiang; Li, Weifeng; Chen, Xi; Liu, Peng; Liu, Hanjun
2015-08-01
Speakers rapidly adjust their ongoing vocal productions to compensate for errors they hear in their auditory feedback. It is currently unclear what role attention plays in these vocal compensations. This event-related potential (ERP) study examined the influence of selective and divided attention on the vocal and cortical responses to pitch errors heard in auditory feedback regarding ongoing vocalisations. During the production of a sustained vowel, participants briefly heard their vocal pitch shifted up two semitones while they actively attended to auditory or visual events (selective attention), or both auditory and visual events (divided attention), or were not told to attend to either modality (control condition). The behavioral results showed that attending to the pitch perturbations elicited larger vocal compensations than attending to the visual stimuli. Moreover, ERPs were likewise sensitive to the attentional manipulations: P2 responses to pitch perturbations were larger when participants attended to the auditory stimuli compared to when they attended to the visual stimuli, and compared to when they were not explicitly told to attend to either the visual or auditory stimuli. By contrast, dividing attention between the auditory and visual modalities caused suppressed P2 responses relative to all the other conditions and caused enhanced N1 responses relative to the control condition. These findings provide strong evidence for the influence of attention on the mechanisms underlying the auditory-vocal integration in the processing of pitch feedback errors. In addition, selective attention and divided attention appear to modulate the neurobehavioral processing of pitch feedback errors in different ways.
14. Speech Compensation for Time-Scale-Modified Auditory Feedback
Science.gov (United States)
Ogane, Rintaro; Honda, Masaaki
2014-01-01
Purpose: The purpose of this study was to examine speech compensation in response to time-scale-modified auditory feedback during the transition of the semivowel for a target utterance of /ija/. Method: Each utterance session consisted of 10 control trials in the normal feedback condition followed by 20 perturbed trials in the modified auditory…
15. Feedback valence affects auditory perceptual learning independently of feedback probability
OpenAIRE
Amitay, S.; Moore, D. R.; Molloy, K.; Halliday, L. F.
2015-01-01
Previous studies have suggested that negative feedback is more effective in driving learning than positive feedback. We investigated the effect on learning of providing varying amounts of negative and positive feedback while listeners attempted to discriminate between three identical tones; an impossible task that nevertheless produces robust learning. Four feedback conditions were compared during training: 90% positive feedback or 10% negative feedback informed the participants that they wer...
16. Task-irrelevant auditory feedback facilitates motor performance in musicians
Directory of Open Access Journals (Sweden)
Virginia eConde
2012-05-01
Full Text Available An efficient and fast auditory–motor network is a basic resource for trained musicians due to the importance of motor anticipation of sound production in musical performance. When playing an instrument, motor performance always goes along with the production of sounds and the integration between both modalities plays an essential role in the course of musical training. The aim of the present study was to investigate the role of task-irrelevant auditory feedback during motor performance in musicians using a serial reaction time task (SRTT. Our hypothesis was that musicians, due to their extensive auditory–motor practice routine during musical training, have a superior performance and learning capabilities when receiving auditory feedback during SRTT relative to musicians performing the SRTT without any auditory feedback. Here we provide novel evidence that task-irrelevant auditory feedback is capable to reinforce SRTT performance but not learning, a finding that might provide further insight into auditory-motor integration in musicians on a behavioral level.
17. Auditory Masking Effects on Speech Fluency in Apraxia of Speech and Aphasia: Comparison to Altered Auditory Feedback
Science.gov (United States)
Jacks, Adam; Haley, Katarina L.
2015-01-01
Purpose: To study the effects of masked auditory feedback (MAF) on speech fluency in adults with aphasia and/or apraxia of speech (APH/AOS). We hypothesized that adults with AOS would increase speech fluency when speaking with noise. Altered auditory feedback (AAF; i.e., delayed/frequency-shifted feedback) was included as a control condition not…
18. Stuttering Inhibition via Altered Auditory Feedback during Scripted Telephone Conversations
Science.gov (United States)
Hudock, Daniel; Kalinowski, Joseph
2014-01-01
Background: Overt stuttering is inhibited by approximately 80% when people who stutter read aloud as they hear an altered form of their speech feedback to them. However, levels of stuttering inhibition vary from 60% to 100% depending on speaking situation and signal presentation. For example, binaural presentations of delayed auditory feedback…
19. Partial Compensation for Altered Auditory Feedback: A Tradeoff with Somatosensory Feedback?
Science.gov (United States)
Katseff, Shira; Houde, John; Johnson, Keith
2012-01-01
Talkers are known to compensate only partially for experimentally-induced changes to their auditory feedback. In a typical experiment, talkers might hear their F1 feedback shifted higher (so that /[epsilon]/ sounds like /[ash]/, for example), and compensate by lowering F1 in their subsequent speech by about a quarter of that distance. Here, we…
20. Intensity of guitar playing as a function of auditory feedback.
Science.gov (United States)
Johnson, C I; Pick, H L; Garber, S R; Siegel, G M
1978-06-01
Subjects played an electric guitar while auditory feedback was attenuated or amplified at seven sidetone levels varying 10-dB steps around a comfortable listening level. The sidetone signal was presented in quiet (experiment I) and several levels of white noise (experiment II). Subjects compensated for feedback changes, demonstrating a sidetone amplification as well as a Lombard effect. The similarity of these results to those found previously for speech suggests that guitar playing can be a useful analog for the function of auditory feedback in speech production. Unlike previous findings for speech, the sidetone-amplification effect was not potentiated by masking, consistent with a hypothesis that potentiation in speech is attributable to interference with bone conduction caused by the masking noise.
1. Brain responses to altered auditory feedback during musical keyboard production: an fMRI study.
Science.gov (United States)
Pfordresher, Peter Q; Mantell, James T; Brown, Steven; Zivadinov, Robert; Cox, Jennifer L
2014-03-27
Alterations of auditory feedback during piano performance can be profoundly disruptive. Furthermore, different alterations can yield different types of disruptive effects. Whereas alterations of feedback synchrony disrupt performed timing, alterations of feedback pitch contents can disrupt accuracy. The current research tested whether these behavioral dissociations correlate with differences in brain activity. Twenty pianists performed simple piano keyboard melodies while being scanned in a 3-T magnetic resonance imaging (MRI) scanner. In different conditions they experienced normal auditory feedback, altered auditory feedback (asynchronous delays or altered pitches), or control conditions that excluded movement or sound. Behavioral results replicated past findings. Neuroimaging data suggested that asynchronous delays led to increased activity in Broca's area and its right homologue, whereas disruptive alterations of pitch elevated activations in the cerebellum, area Spt, inferior parietal lobule, and the anterior cingulate cortex. Both disruptive conditions increased activations in the supplementary motor area. These results provide the first evidence of neural responses associated with perception/action mismatch during keyboard production.
2. Effects of altered auditory feedback across effector systems: production of melodies by keyboard and singing.
Science.gov (United States)
Pfordresher, Peter Q; Mantell, James T
2012-01-01
We report an experiment that tested whether effects of altered auditory feedback (AAF) during piano performance differ from its effects during singing. These effector systems differ with respect to the mapping between motor gestures and pitch content of auditory feedback. Whereas this action-effect mapping is highly reliable during phonation in any vocal motor task (singing or speaking), mapping between finger movements and pitch occurs only in limited situations, such as piano playing. Effects of AAF in both tasks replicated results previously found for keyboard performance (Pfordresher, 2003), in that asynchronous (delayed) feedback slowed timing whereas alterations to feedback pitch increased error rates, and the effect of asynchronous feedback was similar in magnitude across tasks. However, manipulations of feedback pitch had larger effects on singing than on keyboard production, suggesting effector-specific differences in sensitivity to action-effect mapping with respect to feedback content. These results support the view that disruption from AAF is based on abstract, effector independent, response-effect associations but that the strength of associations differs across effector systems.
3. The Effect of Gender on the N1-P2 Auditory Complex while Listening and Speaking with Altered Auditory Feedback
Science.gov (United States)
Swink, Shannon; Stuart, Andrew
2012-01-01
The effect of gender on the N1-P2 auditory complex was examined while listening and speaking with altered auditory feedback. Fifteen normal hearing adult males and 15 females participated. N1-P2 components were evoked while listening to self-produced nonaltered and frequency shifted /a/ tokens and during production of /a/ tokens during nonaltered…
4. Using on-line altered auditory feedback treating Parkinsonian speech
Science.gov (United States)
Wang, Emily; Verhagen, Leo; de Vries, Meinou H.
2005-09-01
Patients with advanced Parkinson's disease tend to have dysarthric speech that is hesitant, accelerated, and repetitive, and that is often resistant to behavior speech therapy. In this pilot study, the speech disturbances were treated using on-line altered feedbacks (AF) provided by SpeechEasy (SE), an in-the-ear device registered with the FDA for use in humans to treat chronic stuttering. Eight PD patients participated in the study. All had moderate to severe speech disturbances. In addition, two patients had moderate recurring stuttering at the onset of PD after long remission since adolescence, two had bilateral STN DBS, and two bilateral pallidal DBS. An effective combination of delayed auditory feedback and frequency-altered feedback was selected for each subject and provided via SE worn in one ear. All subjects produced speech samples (structured-monologue and reading) under three conditions: baseline, with SE without, and with feedbacks. The speech samples were randomly presented and rated for speech intelligibility goodness using UPDRS-III item 18 and the speaking rate. The results indicted that SpeechEasy is well tolerated and AF can improve speech intelligibility in spontaneous speech. Further investigational use of this device for treating speech disorders in PD is warranted [Work partially supported by Janus Dev. Group, Inc.].
5. A Bayesian Account of Vocal Adaptation to Pitch-Shifted Auditory Feedback
Science.gov (United States)
Hahnloser, Richard H. R.
2017-01-01
Motor systems are highly adaptive. Both birds and humans compensate for synthetically induced shifts in the pitch (fundamental frequency) of auditory feedback stemming from their vocalizations. Pitch-shift compensation is partial in the sense that large shifts lead to smaller relative compensatory adjustments of vocal pitch than small shifts. Also, compensation is larger in subjects with high motor variability. To formulate a mechanistic description of these findings, we adapt a Bayesian model of error relevance. We assume that vocal-auditory feedback loops in the brain cope optimally with known sensory and motor variability. Based on measurements of motor variability, optimal compensatory responses in our model provide accurate fits to published experimental data. Optimal compensation correctly predicts sensory acuity, which has been estimated in psychophysical experiments as just-noticeable pitch differences. Our model extends the utility of Bayesian approaches to adaptive vocal behaviors. PMID:28135267
6. Effects of auditory feedback during gait training on hemiplegic patients' weight bearing and dynamic balance ability.
Science.gov (United States)
Ki, Kyong-Il; Kim, Mi-Sun; Moon, Young; Choi, Jong-Duk
2015-04-01
[Purpose] This study examined the effects of auditory feedback during gait on the weight bearing of patients with hemiplegia resulting from a stroke. [Subjects] Thirty hemiplegic patients participated in this experiment and they were randomly allocated to an experimental group and a control group. [Methods] Both groups received neuro-developmental treatment for four weeks and the experimental group additionally received auditory feedback during gait training. In order to examine auditory feedback effects on weight bearing during gait, a motion analysis system GAITRite was used to measure the duration of the stance phase and single limb stance phase of the subjects. [Results] The experimental group showed statistically significant improvements in the duration of the stance phase and single limb stance phase of the paretic side and the results of the Timed Up and Go Test after the training. [Conclusion] Auditory feedback during gait training significantly improved the duration of the stance phase and single limb stance phase of hemiplegic stroke patients.
7. Ring a bell? Adaptive Auditory Game Feedback to Sustain Performance in Stroke Rehabilitation
DEFF Research Database (Denmark)
Hald, Kasper; Knoche, Hendrik Ole
2016-01-01
Abstract. This paper investigates the effect of adaptive auditory feed- back on continued player performance for stroke patients in a Whack- a-Mole style tablet game. The feedback consisted of accumulatively in- creasing the pitch of positive feedback sounds on tasks with fast reaction time...... and resetting it after slow reaction times. The analysis was based on data was obtained in a field trial with lesion patients during their regular rehabilitation. The auditory feedback events were categorized by feedback type (positive/negative) and the associated pitch change of ei- ther high or low magnitude...
8. Role of auditory feedback in speech produced by cochlear implanted adults and children
Science.gov (United States)
Bharadwaj, Sneha V.; Tobey, Emily A.; Assmann, Peter F.; Katz, William F.
2002-05-01
A prominent theory of speech production proposes that speech segments are largely controlled by reference to an internal model, with minimal reliance on auditory feedback. This theory also maintains that suprasegmental aspects of speech are directly regulated by auditory feedback. Accordingly, if a talker is briefly deprived of auditory feedback speech segments should not be affected, but suprasegmental properties should show significant change. To test this prediction, comparisons were made between speech samples obtained from cochlear implant users who repeated words under two conditions (1) implant device turned ON, and (2) implant switched OFF immediately before the repetition of each word. To determine whether producing unfamiliar speech requires greater reliance on auditory feedback than producing familiar speech, English and French words were elicited from English-speaking subjects. Subjects were congenitally deaf children (n=4) and adventitiously deafened adults (n=4). Vowel fundamental frequency and formant frequencies, vowel and syllable durations, and fricative spectral moments were analyzed. Preliminary data only partially confirm the predictions, in that both segmental and suprasegmental aspects of speech were significantly modified in the absence of auditory feedback. Modifications were greater for French compared to English words, suggesting greater reliance on auditory feedback for unfamiliar words. [Work supported by NIDCD.
9. An Experimental Investigation of the Effect of Altered Auditory Feedback on the Conversational Speech of Adults Who Stutter
Science.gov (United States)
Lincoln, Michelle; Packman, Ann; Onslow, Mark; Jones, Mark
2010-01-01
Purpose: To investigate the impact on percentage of syllables stuttered of various durations of delayed auditory feedback (DAF), levels of frequency-altered feedback (FAF), and masking auditory feedback (MAF) during conversational speech. Method: Eleven adults who stuttered produced 10-min conversational speech samples during a control condition…
10. Psycho-physiological assessment of a prosthetic hand sensory feedback system based on an auditory display: a preliminary study
Directory of Open Access Journals (Sweden)
Gonzalez Jose
2012-06-01
Full Text Available Abstract Background Prosthetic hand users have to rely extensively on visual feedback, which seems to lead to a high conscious burden for the users, in order to manipulate their prosthetic devices. Indirect methods (electro-cutaneous, vibrotactile, auditory cues have been used to convey information from the artificial limb to the amputee, but the usability and advantages of these feedback methods were explored mainly by looking at the performance results, not taking into account measurements of the user’s mental effort, attention, and emotions. The main objective of this study was to explore the feasibility of using psycho-physiological measurements to assess cognitive effort when manipulating a robot hand with and without the usage of a sensory substitution system based on auditory feedback, and how these psycho-physiological recordings relate to temporal and grasping performance in a static setting. Methods 10 male subjects (26+/-years old, participated in this study and were asked to come for 2 consecutive days. On the first day the experiment objective, tasks, and experiment setting was explained. Then, they completed a 30 minutes guided training. On the second day each subject was tested in 3 different modalities: Auditory Feedback only control (AF, Visual Feedback only control (VF, and Audiovisual Feedback control (AVF. For each modality they were asked to perform 10 trials. At the end of each test, the subject had to answer the NASA TLX questionnaire. Also, during the test the subject’s EEG, ECG, electro-dermal activity (EDA, and respiration rate were measured. Results The results show that a higher mental effort is needed when the subjects rely only on their vision, and that this effort seems to be reduced when auditory feedback is added to the human-machine interaction (multimodal feedback. Furthermore, better temporal performance and better grasping performance was obtained in the audiovisual modality. Conclusions The performance
11. Vocal responses to perturbations in voice auditory feedback in individuals with Parkinson's disease.
Directory of Open Access Journals (Sweden)
Hanjun Liu
Full Text Available BACKGROUND: One of the most common symptoms of speech deficits in individuals with Parkinson's disease (PD is significantly reduced vocal loudness and pitch range. The present study investigated whether abnormal vocalizations in individuals with PD are related to sensory processing of voice auditory feedback. Perturbations in loudness or pitch of voice auditory feedback are known to elicit short latency, compensatory responses in voice amplitude or fundamental frequency. METHODOLOGY/PRINCIPAL FINDINGS: Twelve individuals with Parkinson's disease and 13 age- and sex-matched healthy control subjects sustained a vowel sound (/α/ and received unexpected, brief (200 ms perturbations in voice loudness (±3 or 6 dB or pitch (±100 cents auditory feedback. Results showed that, while all subjects produced compensatory responses in their voice amplitude or fundamental frequency, individuals with PD exhibited larger response magnitudes than the control subjects. Furthermore, for loudness-shifted feedback, upward stimuli resulted in shorter response latencies than downward stimuli in the control subjects but not in individuals with PD. CONCLUSIONS/SIGNIFICANCE: The larger response magnitudes in individuals with PD compared with the control subjects suggest that processing of voice auditory feedback is abnormal in PD. Although the precise mechanisms of the voice feedback processing are unknown, results of this study suggest that abnormal voice control in individuals with PD may be related to dysfunctional mechanisms of error detection or correction in sensory feedback processing.
12. Tap Arduino: An Arduino microcontroller for low-latency auditory feedback in sensorimotor synchronization experiments.
Science.gov (United States)
Schultz, Benjamin G; van Vugt, Floris T
2016-12-01
Timing abilities are often measured by having participants tap their finger along with a metronome and presenting tap-triggered auditory feedback. These experiments predominantly use electronic percussion pads combined with software (e.g., FTAP or Max/MSP) that records responses and delivers auditory feedback. However, these setups involve unknown latencies between tap onset and auditory feedback and can sometimes miss responses or record multiple, superfluous responses for a single tap. These issues may distort measurements of tapping performance or affect the performance of the individual. We present an alternative setup using an Arduino microcontroller that addresses these issues and delivers low-latency auditory feedback. We validated our setup by having participants (N = 6) tap on a force-sensitive resistor pad connected to the Arduino and on an electronic percussion pad with various levels of force and tempi. The Arduino delivered auditory feedback through a pulse-width modulation (PWM) pin connected to a headphone jack or a wave shield component. The Arduino's PWM (M = 0.6 ms, SD = 0.3) and wave shield (M = 2.6 ms, SD = 0.3) demonstrated significantly lower auditory feedback latencies than the percussion pad (M = 9.1 ms, SD = 2.0), FTAP (M = 14.6 ms, SD = 2.8), and Max/MSP (M = 15.8 ms, SD = 3.4). The PWM and wave shield latencies were also significantly less variable than those from FTAP and Max/MSP. The Arduino missed significantly fewer taps, and recorded fewer superfluous responses, than the percussion pad. The Arduino captured all responses, whereas at lower tapping forces, the percussion pad missed more taps. Regardless of tapping force, the Arduino outperformed the percussion pad. Overall, the Arduino is a high-precision, low-latency, portable, and affordable tool for auditory experiments.
13. Comparisons of Stuttering Frequency during and after Speech Initiation in Unaltered Feedback, Altered Auditory Feedback and Choral Speech Conditions
Science.gov (United States)
Saltuklaroglu, Tim; Kalinowski, Joseph; Robbins, Mary; Crawcour, Stephen; Bowers, Andrew
2009-01-01
Background: Stuttering is prone to strike during speech initiation more so than at any other point in an utterance. The use of auditory feedback (AAF) has been found to produce robust decreases in the stuttering frequency by creating an electronic rendition of choral speech (i.e., speaking in unison). However, AAF requires users to self-initiate…
14. Combined mirror visual and auditory feedback therapy for upper limb phantom pain: a case report
Directory of Open Access Journals (Sweden)
Yan Kun
2011-01-01
Full Text Available Abstract Introduction Phantom limb sensation and phantom limb pain is a very common issue after amputations. In recent years there has been accumulating data implicating 'mirror visual feedback' or 'mirror therapy' as helpful in the treatment of phantom limb sensation and phantom limb pain. Case presentation We present the case of a 24-year-old Caucasian man, a left upper limb amputee, treated with mirror visual feedback combined with auditory feedback with improved pain relief. Conclusion This case may suggest that auditory feedback might enhance the effectiveness of mirror visual feedback and serve as a valuable addition to the complex multi-sensory processing of body perception in patients who are amputees.
15. Different Students, Different Corrective Feedback%Different Students,Different Corrective Feedback
Institute of Scientific and Technical Information of China (English)
施瑞
2016-01-01
There are many kinds of corrective feedback for SLA learners, which include explicit feedback, recast and prompts. Since teacher plays a very important role in SLA teaching, we should carefully use corrective feedback. From the book A Research Agenda For Second Language Acquisition Of Pre-literate And Low-literate Adult And Adolescent Learners's examples and my own real teaching experience, I assume that teacher should choose different corrective feedback to different students. Their learning abilities, English levels as well as their characteristics and personalities should be all taken into account when you are giving a corrective feedback to students. In other words, as a SLA teacher, we should teach students in accordance with their aptitude. And teachers better use different corrective feedback when they are going to response or react to their different students.
16. Attentional demands influence vocal compensations to pitch errors heard in auditory feedback.
Directory of Open Access Journals (Sweden)
Anupreet K Tumber
Full Text Available Auditory feedback is required to maintain fluent speech. At present, it is unclear how attention modulates auditory feedback processing during ongoing speech. In this event-related potential (ERP study, participants vocalized/a/, while they heard their vocal pitch suddenly shifted downward a ½ semitone in both single and dual-task conditions. During the single-task condition participants passively viewed a visual stream for cues to start and stop vocalizing. In the dual-task condition, participants vocalized while they identified target stimuli in a visual stream of letters. The presentation rate of the visual stimuli was manipulated in the dual-task condition in order to produce a low, intermediate, and high attentional load. Visual target identification accuracy was lowest in the high attentional load condition, indicating that attentional load was successfully manipulated. Results further showed that participants who were exposed to the single-task condition, prior to the dual-task condition, produced larger vocal compensations during the single-task condition. Thus, when participants' attention was divided, less attention was available for the monitoring of their auditory feedback, resulting in smaller compensatory vocal responses. However, P1-N1-P2 ERP responses were not affected by divided attention, suggesting that the effect of attentional load was not on the auditory processing of pitch altered feedback, but instead it interfered with the integration of auditory and motor information, or motor control itself.
17. Relationship between Sympathetic Skin Responses and Auditory Hypersensitivity to Different Auditory Stimuli.
Science.gov (United States)
Kato, Fumi; Iwanaga, Ryoichiro; Chono, Mami; Fujihara, Saori; Tokunaga, Akiko; Murata, Jun; Tanaka, Koji; Nakane, Hideyuki; Tanaka, Goro
2014-07-01
[Purpose] Auditory hypersensitivity has been widely reported in patients with autism spectrum disorders. However, the neurological background of auditory hypersensitivity is currently not clear. The present study examined the relationship between sympathetic nervous system responses and auditory hypersensitivity induced by different types of auditory stimuli. [Methods] We exposed 20 healthy young adults to six different types of auditory stimuli. The amounts of palmar sweating resulting from the auditory stimuli were compared between groups with (hypersensitive) and without (non-hypersensitive) auditory hypersensitivity. [Results] Although no group × type of stimulus × first stimulus interaction was observed for the extent of reaction, significant type of stimulus × first stimulus interaction was noted for the extent of reaction. For an 80 dB-6,000 Hz stimulus, the trends for palmar sweating differed between the groups. For the first stimulus, the variance became larger in the hypersensitive group than in the non-hypersensitive group. [Conclusion] Subjects who regularly felt excessive reactions to auditory stimuli tended to have excessive sympathetic responses to repeated loud noises compared with subjects who did not feel excessive reactions. People with auditory hypersensitivity may be classified into several subtypes depending on their reaction patterns to auditory stimuli.
18. Auditory display as a prosthetic hand sensory feedback for reaching and grasping tasks.
Science.gov (United States)
Gonzalez, Jose; Suzuki, Hiroyuki; Natsumi, Nakayama; Sekine, Masashi; Yu, Wenwei
2012-01-01
Upper limb amputees have to rely extensively on visual feedback in order to monitor and manipulate successfully their prosthetic device. This situation leads to high consciousness burden, which generates fatigue and frustration. Therefore, in order to enhance motor-sensory performance and awareness, an auditory display was used as a sensory feedback system for the prosthetic hand's spatio-temporal and force information in a complete reaching and grasping setting. The main objective of this study was to explore the effects of using the auditory display to monitor the prosthetic hand during a complete reaching and grasping motion. The results presented in this paper point out that the usage of an auditory display to monitor and control a robot hand improves the temporal and grasping performance greatly, while reducing mental effort and improving their confidence.
19. Individual Variability in Delayed Auditory Feedback Effects on Speech Fluency and Rate in Normally Fluent Adults
Science.gov (United States)
Chon, HeeCheong; Kraft, Shelly Jo; Zhang, Jingfei; Loucks, Torrey; Ambrose, Nicoline G.
2013-01-01
Purpose: Delayed auditory feedback (DAF) is known to induce stuttering-like disfluencies (SLDs) and cause speech rate reductions in normally fluent adults, but the reason for speech disruptions is not fully known, and individual variation has not been well characterized. Studying individual variation in susceptibility to DAF may identify factors…
20. Shop 'til you hear it drop - Influence of Interactive Auditory Feedback in a Virtual Reality Supermarket
DEFF Research Database (Denmark)
Sikström, Erik; Høeg, Emil Rosenlund; Mangano, Luca
2016-01-01
In this paper we describe an experiment aiming to investigate the impact of auditory feedback in a virtual reality supermarket scenario. The participants were asked to read a shopping list and collect items one by one and place them into a shopping cart. Three conditions were presented randomly, ...
1. Auditory feedback affects perception of effort when exercising with a Pulley machine
DEFF Research Database (Denmark)
Bordegoni, Monica; Ferrise, Francesco; Grani, Francesco
2013-01-01
In this paper we describe an experiment that investigates the role of auditory feedback in affecting the perception of effort when using a physical pulley machine. Specifically, we investigated whether variations in the amplitude and frequency content of the pulley sound affect perception of effort....... Results show that variations in frequency content affect the perception of effort....
2. Attentional demands modulate sensorimotor learning induced by persistent exposure to changes in auditory feedback.
Science.gov (United States)
Scheerer, Nichole E; Tumber, Anupreet K; Jones, Jeffery A
2016-02-01
Hearing one's own voice is important for regulating ongoing speech and for mapping speech sounds onto articulator movements. However, it is currently unknown whether attention mediates changes in the relationship between motor commands and their acoustic output, which are necessary as growth and aging inevitably cause changes to the vocal tract. In this study, participants produced vocalizations while they heard their vocal pitch persistently shifted downward one semitone in both single- and dual-task conditions. During the single-task condition, participants vocalized while passively viewing a visual stream. During the dual-task condition, participants vocalized while also monitoring a visual stream for target letters, forcing participants to divide their attention. Participants' vocal pitch was measured across each vocalization, to index the extent to which their ongoing vocalization was modified as a result of the deviant auditory feedback. Smaller compensatory responses were recorded during the dual-task condition, suggesting that divided attention interfered with the use of auditory feedback for the regulation of ongoing vocalizations. Participants' vocal pitch was also measured at the beginning of each vocalization, before auditory feedback was available, to assess the extent to which the deviant auditory feedback was used to modify subsequent speech motor commands. Smaller changes in vocal pitch at vocalization onset were recorded during the dual-task condition, suggesting that divided attention diminished sensorimotor learning. Together, the results of this study suggest that attention is required for the speech motor control system to make optimal use of auditory feedback for the regulation and planning of speech motor commands.
3. Adaptation to delayed auditory feedback induces the temporal recalibration effect in both speech perception and production.
Science.gov (United States)
Yamamoto, Kosuke; Kawabata, Hideaki
2014-12-01
We ordinarily speak fluently, even though our perceptions of our own voices are disrupted by various environmental acoustic properties. The underlying mechanism of speech is supposed to monitor the temporal relationship between speech production and the perception of auditory feedback, as suggested by a reduction in speech fluency when the speaker is exposed to delayed auditory feedback (DAF). While many studies have reported that DAF influences speech motor processing, its relationship to the temporal tuning effect on multimodal integration, or temporal recalibration, remains unclear. We investigated whether the temporal aspects of both speech perception and production change due to adaptation to the delay between the motor sensation and the auditory feedback. This is a well-used method of inducing temporal recalibration. Participants continually read texts with specific DAF times in order to adapt to the delay. Then, they judged the simultaneity between the motor sensation and the vocal feedback. We measured the rates of speech with which participants read the texts in both the exposure and re-exposure phases. We found that exposure to DAF changed both the rate of speech and the simultaneity judgment, that is, participants' speech gained fluency. Although we also found that a delay of 200 ms appeared to be most effective in decreasing the rates of speech and shifting the distribution on the simultaneity judgment, there was no correlation between these measurements. These findings suggest that both speech motor production and multimodal perception are adaptive to temporal lag but are processed in distinct ways.
4. Auditory place theory and frequency difference limen
Institute of Scientific and Technical Information of China (English)
ZHANG Jialu
2006-01-01
It has been a barrier that the place code is far too coarse a mechanism to account for the finest frequency difference limen for place theory of hearing since it was proposed in 19th century. A place correlation model, which takes the energy distribution of a pure tone in neighboring bands of auditory filters into full account, was presented in this paper. The model based on the place theory and some experimental results of the psychophysical tuning curves of hearing can explain the finest difference limen for frequency (about 0.02 or 0.3% at 1000 Hz)easily. Using a standard 1/3 octave filter bank of which the relationship between the frequency of a input pure tone apart from the centre frequency of K-th filter band, △f, and the output intensity difference between K-th and (K + 1)-th filters, △E, was established in order to show the fine frequency detection ability of the filter bank. This model can also be used to abstract the fundamental frequency of speech and to measure the frequency of pure tone precisely.
5. Comparison of auditory hallucinations across different disorders and syndromes
NARCIS (Netherlands)
Sommer, Iris E. C.; Koops, Sanne; Blom, Jan Dirk
2012-01-01
Auditory hallucinations can be experienced in the context of many different disorders and syndromes. The differential diagnosis basically rests on the presence or absence of accompanying symptoms. In terms of clinical relevance, the most important distinction to be made is between auditory hallucina
6. Functional sex differences in human primary auditory cortex
NARCIS (Netherlands)
Ruytjens, Liesbet; Georgiadis, Janniko R.; Holstege, Gert; Wit, Hero P.; Albers, Frans W. J.; Willemsen, Antoon T. M.
2007-01-01
Background We used PET to study cortical activation during auditory stimulation and found sex differences in the human primary auditory cortex (PAC). Regional cerebral blood flow (rCBF) was measured in 10 male and 10 female volunteers while listening to sounds (music or white noise) and during a bas
7. Functional sex differences in human primary auditory cortex
Energy Technology Data Exchange (ETDEWEB)
Ruytjens, Liesbet [University Medical Center Groningen, Department of Otorhinolaryngology, Groningen (Netherlands); University Medical Center Utrecht, Department Otorhinolaryngology, P.O. Box 85500, Utrecht (Netherlands); Georgiadis, Janniko R. [University of Groningen, University Medical Center Groningen, Department of Anatomy and Embryology, Groningen (Netherlands); Holstege, Gert [University of Groningen, University Medical Center Groningen, Center for Uroneurology, Groningen (Netherlands); Wit, Hero P. [University Medical Center Groningen, Department of Otorhinolaryngology, Groningen (Netherlands); Albers, Frans W.J. [University Medical Center Utrecht, Department Otorhinolaryngology, P.O. Box 85500, Utrecht (Netherlands); Willemsen, Antoon T.M. [University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Groningen (Netherlands)
2007-12-15
We used PET to study cortical activation during auditory stimulation and found sex differences in the human primary auditory cortex (PAC). Regional cerebral blood flow (rCBF) was measured in 10 male and 10 female volunteers while listening to sounds (music or white noise) and during a baseline (no auditory stimulation). We found a sex difference in activation of the left and right PAC when comparing music to noise. The PAC was more activated by music than by noise in both men and women. But this difference between the two stimuli was significantly higher in men than in women. To investigate whether this difference could be attributed to either music or noise, we compared both stimuli with the baseline and revealed that noise gave a significantly higher activation in the female PAC than in the male PAC. Moreover, the male group showed a deactivation in the right prefrontal cortex when comparing noise to the baseline, which was not present in the female group. Interestingly, the auditory and prefrontal regions are anatomically and functionally linked and the prefrontal cortex is known to be engaged in auditory tasks that involve sustained or selective auditory attention. Thus we hypothesize that differences in attention result in a different deactivation of the right prefrontal cortex, which in turn modulates the activation of the PAC and thus explains the sex differences found in the activation of the PAC. Our results suggest that sex is an important factor in auditory brain studies. (orig.)
8. Sex differences in the representation of call stimuli in a songbird secondary auditory area
Directory of Open Access Journals (Sweden)
Nicolas eGiret
2015-10-01
Full Text Available Understanding how communication sounds are encoded in the central auditory system is critical to deciphering the neural bases of acoustic communication. Songbirds use learned or unlearned vocalizations in a variety of social interactions. They have telencephalic auditory areas specialized for processing natural sounds and considered as playing a critical role in the discrimination of behaviorally relevant vocal sounds. The zebra finch, a highly social songbird species, forms lifelong pair bonds. Only male zebra finches sing. However, both sexes produce the distance call when placed in visual isolation. This call is sexually dimorphic, is learned only in males and provides support for individual recognition in both sexes. Here, we assessed whether auditory processing of distance calls differs between paired males and females by recording spiking activity in a secondary auditory area, the caudolateral mesopallium (CLM, while presenting the distance calls of a variety of individuals, including the bird itself, the mate, familiar and unfamiliar males and females. In males, the CLM is potentially involved in auditory feedback processing important for vocal learning. Based on both the analyses of spike rates and temporal aspects of discharges, our results clearly indicate that call-evoked responses of CLM neurons are sexually dimorphic, being stronger, lasting longer and conveying more information about calls in males than in females. In addition, how auditory responses vary among call types differ between sexes. In females, response strength differs between familiar male and female calls. In males, temporal features of responses reveal a sensitivity to the bird’s own call. These findings provide evidence that sexual dimorphism occurs in higher-order processing areas within the auditory system. They suggest a sexual dimorphism in the function of the CLM, contributing to transmit information about the self-generated calls in males and to storage of
9. Adaptation to Delayed Speech Feedback Induces Temporal Recalibration between Vocal Sensory and Auditory Modalities
Directory of Open Access Journals (Sweden)
Kosuke Yamamoto
2011-10-01
Full Text Available We ordinarily perceive our voice sound as occurring simultaneously with vocal production, but the sense of simultaneity in vocalization can be easily interrupted by delayed auditory feedback (DAF. DAF causes normal people to have difficulty speaking fluently but helps people with stuttering to improve speech fluency. However, the underlying temporal mechanism for integrating the motor production of voice and the auditory perception of vocal sound remains unclear. In this study, we investigated the temporal tuning mechanism integrating vocal sensory and voice sounds under DAF with an adaptation technique. Participants read some sentences with specific delay times of DAF (0, 30, 75, 120 ms during three minutes to induce ‘Lag Adaptation’. After the adaptation, they then judged the simultaneity between motor sensation and vocal sound given feedback in producing simple voice but not speech. We found that speech production with lag adaptation induced a shift in simultaneity responses toward the adapted auditory delays. This indicates that the temporal tuning mechanism in vocalization can be temporally recalibrated after prolonged exposure to delayed vocal sounds. These findings suggest vocalization is finely tuned by the temporal recalibration mechanism, which acutely monitors the integration of temporal delays between motor sensation and vocal sound.
10. Temporal recalibration in vocalization induced by adaptation of delayed auditory feedback.
Directory of Open Access Journals (Sweden)
Kosuke Yamamoto
Full Text Available BACKGROUND: We ordinarily perceive our voice sound as occurring simultaneously with vocal production, but the sense of simultaneity in vocalization can be easily interrupted by delayed auditory feedback (DAF. DAF causes normal people to have difficulty speaking fluently but helps people with stuttering to improve speech fluency. However, the underlying temporal mechanism for integrating the motor production of voice and the auditory perception of vocal sound remains unclear. In this study, we investigated the temporal tuning mechanism integrating vocal sensory and voice sounds under DAF with an adaptation technique. METHODS AND FINDINGS: Participants produced a single voice sound repeatedly with specific delay times of DAF (0, 66, 133 ms during three minutes to induce 'Lag Adaptation'. They then judged the simultaneity between motor sensation and vocal sound given feedback. We found that lag adaptation induced a shift in simultaneity responses toward the adapted auditory delays. This indicates that the temporal tuning mechanism in vocalization can be temporally recalibrated after prolonged exposure to delayed vocal sounds. Furthermore, we found that the temporal recalibration in vocalization can be affected by averaging delay times in the adaptation phase. CONCLUSIONS: These findings suggest vocalization is finely tuned by the temporal recalibration mechanism, which acutely monitors the integration of temporal delays between motor sensation and vocal sound.
11. Effects of different kinds of robot feedback
DEFF Research Database (Denmark)
Fischer, Kerstin; Lohan, K. S.; Nehaniv, C.
2013-01-01
In this paper, we investigate to what extent tutors' behavior is influenced by different kinds of robot feedback. In particular, we study the effects of online robot feedback in which the robot responds either contingently to the tutor's social behavior or by tracking the objects presented. Also...
12. Auditory feedback control of vocal pitch during sustained vocalization: a cross-sectional study of adult aging.
Directory of Open Access Journals (Sweden)
Peng Liu
Full Text Available BACKGROUND: Auditory feedback has been demonstrated to play an important role in the control of voice fundamental frequency (F(0, but the mechanisms underlying the processing of auditory feedback remain poorly understood. It has been well documented that young adults can use auditory feedback to stabilize their voice F(0 by making compensatory responses to perturbations they hear in their vocal pitch feedback. However, little is known about the effects of aging on the processing of audio-vocal feedback during vocalization. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we recruited adults who were between 19 and 75 years of age and divided them into five age groups. Using a pitch-shift paradigm, the pitch of their vocal feedback was unexpectedly shifted ±50 or ±100 cents during sustained vocalization of the vowel sound/u/. Compensatory vocal F(0 response magnitudes and latencies to pitch feedback perturbations were examined. A significant effect of age was found such that response magnitudes increased with increasing age until maximal values were reached for adults 51-60 years of age and then decreased for adults 61-75 years of age. Adults 51-60 years of age were also more sensitive to the direction and magnitude of the pitch feedback perturbations compared to younger adults. CONCLUSION: These findings demonstrate that the pitch-shift reflex systematically changes across the adult lifespan. Understanding aging-related changes to the role of auditory feedback is critically important for our theoretical understanding of speech production and the clinical applications of that knowledge.
13. A Study of Teacher Feedback in Different English Class Types
Institute of Scientific and Technical Information of China (English)
CHEN Huan
2016-01-01
This essay mainly focuses on the feedback move in IRF(initiate-response-feedback) to investigate the characters and functions of teacher feedback in different class types through classroom observation. The research finds that (1) teachers in dif-ferent class types prefer to adopt evaluative feedback and use more positive feedback .(2) the proportion of each feedback is dif-ferent in listening and speaking, reading and writing class. The implications are that English teachers in senior high school should adopt different feedback flexibly and consider what kind of feedback is more likely elicit the students’output in different class types.
14. A software module for implementing auditory and visual feedback on a video-based eye tracking system
Science.gov (United States)
Rosanlall, Bharat; Gertner, Izidor; Geri, George A.; Arrington, Karl F.
2016-05-01
We describe here the design and implementation of a software module that provides both auditory and visual feedback of the eye position measured by a commercially available eye tracking system. The present audio-visual feedback module (AVFM) serves as an extension to the Arrington Research ViewPoint EyeTracker, but it can be easily modified for use with other similar systems. Two modes of audio feedback and one mode of visual feedback are provided in reference to a circular area-of-interest (AOI). Auditory feedback can be either a click tone emitted when the user's gaze point enters or leaves the AOI, or a sinusoidal waveform with frequency inversely proportional to the distance from the gaze point to the center of the AOI. Visual feedback is in the form of a small circular light patch that is presented whenever the gaze-point is within the AOI. The AVFM processes data that are sent to a dynamic-link library by the EyeTracker. The AVFM's multithreaded implementation also allows real-time data collection (1 kHz sampling rate) and graphics processing that allow display of the current/past gaze-points as well as the AOI. The feedback provided by the AVFM described here has applications in military target acquisition and personnel training, as well as in visual experimentation, clinical research, marketing research, and sports training.
15. Sex differences in brain structure in auditory and cingulate regions
OpenAIRE
Brun, Caroline C.; Lepore, Natasha; Luders, Eileen; Chou, Yi-Yu; Madsen, Sarah K.; Toga, Arthur W; Thompson, Paul M.
2009-01-01
We applied a new method to visualize the three-dimensional profile of sex differences in brain structure based on MRI scans of 100 young adults. We compared 50 men with 50 women, matched for age and other relevant demographics. As predicted, left hemisphere auditory and language-related regions were proportionally expanded in women versus men, suggesting a possible structural basis for the widely replicated sex differences in language processing. In men, primary visual, and visuo-spatial asso...
16. Functional role of delta and theta band oscillations for auditory feedback processing during vocal pitch motor control.
Science.gov (United States)
Behroozmand, Roozbeh; Ibrahim, Nadine; Korzyukov, Oleg; Robin, Donald A; Larson, Charles R
2015-01-01
The answer to the question of how the brain incorporates sensory feedback and links it with motor function to achieve goal-directed movement during vocalization remains unclear. We investigated the mechanisms of voice pitch motor control by examining the spectro-temporal dynamics of EEG signals when non-musicians (NM), relative pitch (RP), and absolute pitch (AP) musicians maintained vocalizations of a vowel sound and received randomized ± 100 cents pitch-shift stimuli in their auditory feedback. We identified a phase-synchronized (evoked) fronto-central activation within the theta band (5-8 Hz) that temporally overlapped with compensatory vocal responses to pitch-shifted auditory feedback and was significantly stronger in RP and AP musicians compared with non-musicians. A second component involved a non-phase-synchronized (induced) frontal activation within the delta band (1-4 Hz) that emerged at approximately 1 s after the stimulus onset. The delta activation was significantly stronger in the NM compared with RP and AP groups and correlated with the pitch rebound error (PRE), indicating the degree to which subjects failed to re-adjust their voice pitch to baseline after the stimulus offset. We propose that the evoked theta is a neurophysiological marker of enhanced pitch processing in musicians and reflects mechanisms by which humans incorporate auditory feedback to control their voice pitch. We also suggest that the delta activation reflects adaptive neural processes by which vocal production errors are monitored and used to update the state of sensory-motor networks for driving subsequent vocal behaviors. This notion is corroborated by our findings showing that larger PREs were associated with greater delta band activity in the NM compared with RP and AP groups. These findings provide new insights into the neural mechanisms of auditory feedback processing for vocal pitch motor control.
17. Sensory Processing: Advances in Understanding Structure and Function of Pitch-Shifted Auditory Feedback in Voice Control
Directory of Open Access Journals (Sweden)
Charles R Larson
2016-02-01
Full Text Available The pitch-shift paradigm has become a widely used method for studying the role of voice pitch auditory feedback in voice control. This paradigm introduces small, brief pitch shifts in voice auditory feedback to vocalizing subjects. The perturbations trigger a reflexive mechanism that counteracts the change in pitch. The underlying mechanisms of the vocal responses are thought to reflect a negative feedback control system that is similar to constructs developed to explain other forms of motor control. Another use of this technique requires subjects to voluntarily change the pitch of their voice when they hear a pitch shift stimulus. Under these conditions, short latency responses are produced that change voice pitch to match that of the stimulus. The pitch-shift technique has been used with magnetoencephalography (MEG and electroencephalography (EEG recordings, and has shown that at vocal onset there is normally a suppression of neural activity related to vocalization. However, if a pitch-shift is also presented at voice onset, there is a cancellation of this suppression, which has been interpreted to mean that one way in which a person distinguishes self-vocalization from vocalization of others is by a comparison of the intended voice and the actual voice. Studies of the pitch shift reflex in the fMRI environment show that the superior temporal gyrus (STG plays an important role in the process of controlling voice F0 based on auditory feedback. Additional studies using fMRI for effective connectivity modeling show that the left and right STG play critical roles in correcting for an error in voice production. While both the left and right STG are involved in this process, a feedback loop develops between left and right STG during perturbations, in which the left to right connection becomes stronger, and a new negative right to left connection emerges along with the emergence of other feedback loops within the cortical network tested.
18. Fast negative feedback enables mammalian auditory nerve fibers to encode a wide dynamic range of sound intensities.
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Mark Ospeck
Full Text Available Mammalian auditory nerve fibers (ANF are remarkable for being able to encode a 40 dB, or hundred fold, range of sound pressure levels into their firing rate. Most of the fibers are very sensitive and raise their quiescent spike rate by a small amount for a faint sound at auditory threshold. Then as the sound intensity is increased, they slowly increase their spike rate, with some fibers going up as high as ∼300 Hz. In this way mammals are able to combine sensitivity and wide dynamic range. They are also able to discern sounds embedded within background noise. ANF receive efferent feedback, which suggests that the fibers are readjusted according to the background noise in order to maximize the information content of their auditory spike trains. Inner hair cells activate currents in the unmyelinated distal dendrites of ANF where sound intensity is rate-coded into action potentials. We model this spike generator compartment as an attenuator that employs fast negative feedback. Input current induces rapid and proportional leak currents. This way ANF are able to have a linear frequency to input current (f-I curve that has a wide dynamic range. The ANF spike generator remains very sensitive to threshold currents, but efferent feedback is able to lower its gain in response to noise.
19. Interaural intensity and latency difference in the dolphin's auditory system.
Science.gov (United States)
Popov, V V; Supin AYa
1991-12-09
Binaural hearing mechanisms were measured in dolphins (Inia geoffrensis) by recording the auditory nerve evoked response from the body surface. The azimuthal position of a sound source at 10-15 degrees from the longitudinal axis elicited interaural intensity disparity up to 20 dB and interaural latency difference as large as 250 microseconds. The latter was many times greater than the acoustical interaural time delay. This latency difference seems to be caused by the intensity disparity. The latency difference seems to be an effective way of coding of intensity disparity.
20. Neuronal mechanisms of voice control are affected by implicit expectancy of externally triggered perturbations in auditory feedback.
Directory of Open Access Journals (Sweden)
Oleg Korzyukov
Full Text Available Accurate vocal production relies on several factors including sensory feedback and the ability to predict future challenges to the control processes. Repetitive patterns of perturbations in sensory feedback by themselves elicit implicit expectations in the vocal control system regarding the timing, quality and direction of perturbations. In the present study, the predictability of voice pitch-shifted auditory feedback was experimentally manipulated. A block of trials where all pitch-shift stimuli were upward, and therefore predictable was contrasted against an unpredictable block of trials in which the stimulus direction was randomized between upward and downward pitch-shifts. It was found that predictable perturbations in voice auditory feedback led to a reduction in the proportion of compensatory vocal responses, which might be indicative of a reduction in vocal control. The predictable perturbations also led to a reduction in the magnitude of the N1 component of cortical Event Related Potentials (ERP that was associated with the reflexive compensations to the perturbations. We hypothesize that formation of expectancy in our study is accompanied by involuntary allocation of attentional resources occurring as a result of habituation or learning, that in turn trigger limited and controlled exploration-related motor variability in the vocal control system.
1. Effect of visual distraction and auditory feedback on patient effort during robot-assisted movement training after stroke
Directory of Open Access Journals (Sweden)
Reinkensmeyer David J
2011-04-01
Full Text Available Abstract Background Practicing arm and gait movements with robotic assistance after neurologic injury can help patients improve their movement ability, but patients sometimes reduce their effort during training in response to the assistance. Reduced effort has been hypothesized to diminish clinical outcomes of robotic training. To better understand patient slacking, we studied the role of visual distraction and auditory feedback in modulating patient effort during a common robot-assisted tracking task. Methods Fourteen participants with chronic left hemiparesis from stroke, five control participants with chronic right hemiparesis and fourteen non-impaired healthy control participants, tracked a visual target with their arms while receiving adaptive assistance from a robotic arm exoskeleton. We compared four practice conditions: the baseline tracking task alone; tracking while also performing a visual distracter task; tracking with the visual distracter and sound feedback; and tracking with sound feedback. For the distracter task, symbols were randomly displayed in the corners of the computer screen, and the participants were instructed to click a mouse button when a target symbol appeared. The sound feedback consisted of a repeating beep, with the frequency of repetition made to increase with increasing tracking error. Results Participants with stroke halved their effort and doubled their tracking error when performing the visual distracter task with their left hemiparetic arm. With sound feedback, however, these participants increased their effort and decreased their tracking error close to their baseline levels, while also performing the distracter task successfully. These effects were significantly smaller for the participants who used their non-paretic arm and for the participants without stroke. Conclusions Visual distraction decreased participants effort during a standard robot-assisted movement training task. This effect was greater for
2. Self-Generated Auditory Feedback as a Cue to Support Rhythmic Motor Stability
Directory of Open Access Journals (Sweden)
Gopher Daniel
2011-12-01
Full Text Available A goal of the SKILLS project is to develop Virtual Reality (VR-based training simulators for different application domains, one of which is juggling. Within this context the value of multimodal VR environments for skill acquisition is investigated. In this study, we investigated whether it was necessary to render the sounds of virtual balls hitting virtual hands within the juggling training simulator. First, we recorded sounds at the jugglers’ ears and found the sound of ball hitting hands to be audible. Second, we asked 24 jugglers to juggle under normal conditions (Audible or while listening to pink noise intended to mask the juggling sounds (Inaudible. We found that although the jugglers themselves reported no difference in their juggling across these two conditions, external juggling experts rated rhythmic stability worse in the Inaudible condition than in the Audible condition. This result suggests that auditory information should be rendered in the VR juggling training simulator.
3. Utility estimation of the application of auditory-visual-tactile sense feedback in respiratory gated radiation therapy
Energy Technology Data Exchange (ETDEWEB)
Jo, Jung Hun; KIm, Byeong Jin; Roh, Shi Won; Lee, Hyeon Chan; Jang, Hyeong Jun; Kim, Hoi Nam [Dept. of Radiation Oncology, Biomedical Engineering, Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Song, Jae Hoon [Dept. of Biomedical Engineering, Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Kim, Young Jae [Dept. of Radiological Technology, Gwang Yang Health Collage, Gwangyang (Korea, Republic of)
2013-03-15
The purpose of this study was to evaluate the possibility to optimize the gated treatment delivery time and maintenance of stable respiratory by the introduction of breath with the assistance of auditory-visual-tactile sense. The experimenter's respiration were measured by ANZAI 4D system. We obtained natural breathing signal, monitor-induced breathing signal, monitor and ventilator-induced breathing signal, and breath-hold signal using real time monitor during 10 minutes beam-on-time. In order to check the stability of respiratory signals distributed in each group were compared with means, standard deviation, variation value, beam{sub t}ime of the respiratory signal. The stability of each respiratory was measured in consideration of deviation change studied in each respiratory time lapse. As a result of an analysis of respiratory signal, all experimenters has showed that breathing signal used both Real time monitor and Ventilator was the most stable and shortest time. In this study, it was evaluated that respiratory gated radiation therapy with auditory-visual-tactual sense and without auditory-visual-tactual sense feedback. The study showed that respiratory gated radiation therapy delivery time could significantly be improved by the application of video feedback when this is combined with audio-tactual sense assistance. This delivery technique did prove its feasibility to limit the tumor motion during treatment delivery for all patients to a defined value while maintaining the accuracy and proved the applicability of the technique in a conventional clinical schedule.
4. A temporal predictive code for voice motor control: Evidence from ERP and behavioral responses to pitch-shifted auditory feedback.
Science.gov (United States)
Behroozmand, Roozbeh; Sangtian, Stacey; Korzyukov, Oleg; Larson, Charles R
2016-04-01
The predictive coding model suggests that voice motor control is regulated by a process in which the mismatch (error) between feedforward predictions and sensory feedback is detected and used to correct vocal motor behavior. In this study, we investigated how predictions about timing of pitch perturbations in voice auditory feedback would modulate ERP and behavioral responses during vocal production. We designed six counterbalanced blocks in which a +100 cents pitch-shift stimulus perturbed voice auditory feedback during vowel sound vocalizations. In three blocks, there was a fixed delay (500, 750 or 1000 ms) between voice and pitch-shift stimulus onset (predictable), whereas in the other three blocks, stimulus onset delay was randomized between 500, 750 and 1000 ms (unpredictable). We found that subjects produced compensatory (opposing) vocal responses that started at 80 ms after the onset of the unpredictable stimuli. However, for predictable stimuli, subjects initiated vocal responses at 20 ms before and followed the direction of pitch shifts in voice feedback. Analysis of ERPs showed that the amplitudes of the N1 and P2 components were significantly reduced in response to predictable compared with unpredictable stimuli. These findings indicate that predictions about temporal features of sensory feedback can modulate vocal motor behavior. In the context of the predictive coding model, temporally-predictable stimuli are learned and reinforced by the internal feedforward system, and as indexed by the ERP suppression, the sensory feedback contribution is reduced for their processing. These findings provide new insights into the neural mechanisms of vocal production and motor control.
5. Differences in the Uptake of Peer and Teacher Feedback
Science.gov (United States)
Ruegg, Rachael
2015-01-01
This study aimed to determine differences in the uptake of peer and teacher feedback after writing students received longitudinal feedback from only one of these sources. It also investigates the types of feedback given by peers and a teacher in order to explain those any differences. Data was collected from 64 Japanese university students in four…
6. Synchronization between two different chaotic systems with nonlinear feedback control
Institute of Scientific and Technical Information of China (English)
Lü Ling; Guo Zhi-An; Zhang Chao
2007-01-01
This paper presents chaos synchronization between two different chaotic systems by using a nonlinear controller, in which the nonlinear functions of the system are used as a nonlinear feedback term. The feedback controller is designed on the basis of stability theory, and the area of feedback gain is determined. The artificial simulation results show that this control method is commendably effective and feasible.
7. The Unresponsive Partner: Roles of Social Status, Auditory Feedback, and Animacy in Coordination of Joint Music Performance
Science.gov (United States)
Demos, Alexander P.; Carter, Daniel J.; Wanderley, Marcelo M.; Palmer, Caroline
2017-01-01
We examined temporal synchronization in joint music performance to determine how social status, auditory feedback, and animacy influence interpersonal coordination. A partner’s coordination can be bidirectional (partners adapt to the actions of one another) or unidirectional (one partner adapts). According to the dynamical systems framework, bidirectional coordination should be the optimal (preferred) state during live performance. To test this, 24 skilled pianists each performed with a confederate while their coordination was measured by the asynchrony in their tone onsets. To promote social balance, half of the participants were told the confederate was a fellow participant – an equal social status. To promote social imbalance, the other half was told the confederate was an experimenter – an unequal social status. In all conditions, the confederate’s arm and finger movements were occluded from the participant’s view to allow manipulation of animacy of the confederate’s performances (live or recorded). Unbeknownst to the participants, half of the confederate’s performances were replaced with pre-recordings, forcing the participant into unidirectional coordination during performance. The other half of the confederate’s performances were live, which permitted bidirectional coordination between performers. In a final manipulation, both performers heard the auditory feedback from one or both of the performers’ parts removed at unpredictable times to disrupt their performance. Consistently larger asynchronies were observed in performances of unidirectional (recorded) than bidirectional (live) performances across all conditions. Participants who were told the confederate was an experimenter reported their synchrony as more successful than when the partner was introduced as a fellow participant. Finally, asynchronies increased as auditory feedback was removed; removal of the confederate’s part hurt coordination more than removal of the participant
8. The Unresponsive Partner: Roles of Social Status, Auditory Feedback, and Animacy in Coordination of Joint Music Performance.
Science.gov (United States)
Demos, Alexander P; Carter, Daniel J; Wanderley, Marcelo M; Palmer, Caroline
2017-01-01
We examined temporal synchronization in joint music performance to determine how social status, auditory feedback, and animacy influence interpersonal coordination. A partner's coordination can be bidirectional (partners adapt to the actions of one another) or unidirectional (one partner adapts). According to the dynamical systems framework, bidirectional coordination should be the optimal (preferred) state during live performance. To test this, 24 skilled pianists each performed with a confederate while their coordination was measured by the asynchrony in their tone onsets. To promote social balance, half of the participants were told the confederate was a fellow participant - an equal social status. To promote social imbalance, the other half was told the confederate was an experimenter - an unequal social status. In all conditions, the confederate's arm and finger movements were occluded from the participant's view to allow manipulation of animacy of the confederate's performances (live or recorded). Unbeknownst to the participants, half of the confederate's performances were replaced with pre-recordings, forcing the participant into unidirectional coordination during performance. The other half of the confederate's performances were live, which permitted bidirectional coordination between performers. In a final manipulation, both performers heard the auditory feedback from one or both of the performers' parts removed at unpredictable times to disrupt their performance. Consistently larger asynchronies were observed in performances of unidirectional (recorded) than bidirectional (live) performances across all conditions. Participants who were told the confederate was an experimenter reported their synchrony as more successful than when the partner was introduced as a fellow participant. Finally, asynchronies increased as auditory feedback was removed; removal of the confederate's part hurt coordination more than removal of the participant's part in live
9. A do-it-yourself membrane-activated auditory feedback device for weight bearing and gait training: a case report.
Science.gov (United States)
Batavia, M; Gianutsos, J G; Vaccaro, A; Gold, J T
2001-04-01
An augmented auditory feedback device comprised of a thin membrane switch mini-buzzer, and battery is described as a modification of a previously described feedback device. The membrane switch can be customized for the patient and is designed to fit inside a patient's shoe without altering the heel height. Its appeal lies in its simplicity of construction, low cost, and ease of implementation during a patient's training for weight bearing and gait. An ever-present source of information, it provides performance-relevant cues to both patient and clinician about the occurrence, duration, and location of a force component of motor performance. The report includes suggested applications of the device, instructions to construct it, and a case report in which the device was used to improve weight bearing and gait in a cognitively healthy person with spina bifida.
10. The predictability of frequency-altered auditory feedback changes the weighting of feedback and feedforward input for speech motor control.
Science.gov (United States)
Scheerer, Nichole E; Jones, Jeffery A
2014-12-01
Speech production requires the combined effort of a feedback control system driven by sensory feedback, and a feedforward control system driven by internal models. However, the factors that dictate the relative weighting of these feedback and feedforward control systems are unclear. In this event-related potential (ERP) study, participants produced vocalisations while being exposed to blocks of frequency-altered feedback (FAF) perturbations that were either predictable in magnitude (consistently either 50 or 100 cents) or unpredictable in magnitude (50- and 100-cent perturbations varying randomly within each vocalisation). Vocal and P1-N1-P2 ERP responses revealed decreases in the magnitude and trial-to-trial variability of vocal responses, smaller N1 amplitudes, and shorter vocal, P1 and N1 response latencies following predictable FAF perturbation magnitudes. In addition, vocal response magnitudes correlated with N1 amplitudes, vocal response latencies, and P2 latencies. This pattern of results suggests that after repeated exposure to predictable FAF perturbations, the contribution of the feedforward control system increases. Examination of the presentation order of the FAF perturbations revealed smaller compensatory responses, smaller P1 and P2 amplitudes, and shorter N1 latencies when the block of predictable 100-cent perturbations occurred prior to the block of predictable 50-cent perturbations. These results suggest that exposure to large perturbations modulates responses to subsequent perturbations of equal or smaller size. Similarly, exposure to a 100-cent perturbation prior to a 50-cent perturbation within a vocalisation decreased the magnitude of vocal and N1 responses, but increased P1 and P2 latencies. Thus, exposure to a single perturbation can affect responses to subsequent perturbations.
11. Behavioral and brain pattern differences between acting and observing in an auditory task
Directory of Open Access Journals (Sweden)
Ventouras Errikos M
2009-01-01
Full Text Available Abstract Background Recent research has shown that errors seem to influence the patterns of brain activity. Additionally current notions support the idea that similar brain mechanisms are activated during acting and observing. The aim of the present study was to examine the patterns of brain activity of actors and observers elicited upon receiving feedback information of the actor's response. Methods The task used in the present research was an auditory identification task that included both acting and observing settings, ensuring concurrent ERP measurements of both participants. The performance of the participants was investigated in conditions of varying complexity. ERP data were analyzed with regards to the conditions of acting and observing in conjunction to correct and erroneous responses. Results The obtained results showed that the complexity induced by cue dissimilarity between trials was a demodulating factor leading to poorer performance. The electrophysiological results suggest that feedback information results in different intensities of the ERP patterns of observers and actors depending on whether the actor had made an error or not. The LORETA source localization method yielded significantly larger electrical activity in the supplementary motor area (Brodmann area 6, the posterior cingulate gyrus (Brodmann area 31/23 and the parietal lobe (Precuneus/Brodmann area 7/5. Conclusion These findings suggest that feedback information has a different effect on the intensities of the ERP patterns of actors and observers depending on whether the actor committed an error. Certain neural systems, including medial frontal area, posterior cingulate gyrus and precuneus may mediate these modulating effects. Further research is needed to elucidate in more detail the neuroanatomical and neuropsychological substrates of these systems.
12. Long-range correlation properties in timing of skilled piano performance: the influence of auditory feedback and deep brain stimulation.
Directory of Open Access Journals (Sweden)
Maria eHerrojo Ruiz
2014-09-01
Full Text Available Unintentional timing deviations during musical performance can be conceived of as timing errors. However, recent research on humanizing computer-generated music has demonstrated that timing fluctuations that exhibit long-range temporal correlations (LRTC are preferred by human listeners. This preference can be accounted for by the ubiquitous presence of LRTC in human tapping and rhythmic performances. Interestingly, the manifestation of LRTC in tapping behavior seems to be driven in a subject-specific manner by the LRTC properties of resting-state background cortical oscillatory activity. In this framework, the current study aimed to investigate whether propagation of timing deviations during the skilled, memorized piano performance (without metronome of 17 professional pianists exhibits LRTC and whether the structure of the correlations is influenced by the presence or absence of auditory feedback.As an additional goal, we set out to investigate the influence of altering the dynamics along the cortico-basal-ganglia-thalamo-cortical network via deep brain stimulation (DBS on the LRTC properties of musical performance. Specifically, we investigated temporal deviations during the skilled piano performance of a non-professional pianist who was treated with subthalamic-deep brain stimulation (STN-DBS due to severe Parkinson's disease, with predominant tremor affecting his right upper extremity. In the tremor-affected right hand, the timing fluctuations of the performance exhibited random correlations with DBS OFF. By contrast, DBS restored long-range dependency in the temporal fluctuations, corresponding with the general motor improvement on DBS.Overall, the present investigations are the first to demonstrate the presence of LRTC in skilled piano performances, indicating that unintentional temporal deviations are correlated over a wide range of time scales. This phenomenon is stable after removal of the auditory feedback, but is altered by STN
13. Long-range correlation properties in timing of skilled piano performance: the influence of auditory feedback and deep brain stimulation.
Science.gov (United States)
Herrojo Ruiz, María; Hong, Sang Bin; Hennig, Holger; Altenmüller, Eckart; Kühn, Andrea A
2014-01-01
Unintentional timing deviations during musical performance can be conceived of as timing errors. However, recent research on humanizing computer-generated music has demonstrated that timing fluctuations that exhibit long-range temporal correlations (LRTC) are preferred by human listeners. This preference can be accounted for by the ubiquitous presence of LRTC in human tapping and rhythmic performances. Interestingly, the manifestation of LRTC in tapping behavior seems to be driven in a subject-specific manner by the LRTC properties of resting-state background cortical oscillatory activity. In this framework, the current study aimed to investigate whether propagation of timing deviations during the skilled, memorized piano performance (without metronome) of 17 professional pianists exhibits LRTC and whether the structure of the correlations is influenced by the presence or absence of auditory feedback. As an additional goal, we set out to investigate the influence of altering the dynamics along the cortico-basal-ganglia-thalamo-cortical network via deep brain stimulation (DBS) on the LRTC properties of musical performance. Specifically, we investigated temporal deviations during the skilled piano performance of a non-professional pianist who was treated with subthalamic-deep brain stimulation (STN-DBS) due to severe Parkinson's disease, with predominant tremor affecting his right upper extremity. In the tremor-affected right hand, the timing fluctuations of the performance exhibited random correlations with DBS OFF. By contrast, DBS restored long-range dependency in the temporal fluctuations, corresponding with the general motor improvement on DBS. Overall, the present investigations demonstrate the presence of LRTC in skilled piano performances, indicating that unintentional temporal deviations are correlated over a wide range of time scales. This phenomenon is stable after removal of the auditory feedback, but is altered by STN-DBS, which suggests that cortico
14. Similar structural dimensions in bushcricket auditory organs in spite of different foreleg size: consequences for auditory tuning.
Science.gov (United States)
Rössler, W; Kalmring, K
1994-11-01
The bushcricket species Decticus albifrons, Decticus verrucivorus and Pholidoptera griseoaptera (Tettigoniidae) belong to the same subfamily (Decticinae) but differ significantly in body size. In spite of the great differences in the dimensions of the forelegs, where the auditory organs are located, the most sensitive range of the hearing threshold lies between 6 and 25 kHz in each case. Only in the frequency range from 2 to 5 kHz and above 25 kHz, significant differences are present. The anatomy of the auditory receptor organs was compared quantitatively, using the techniques of semi-thin sectioning and computer-guided morphometry. The overall number of scolopidia and the length of the crista acustica differs in the three species, but the relative distribution of scolopidia along the crista acustica is very similar. Additionally, the scolopidia and their attachment structures (tectorial membrane, dorsal tracheal wall, cap cells) are of equal size at equivalent relative positions along the crista acustica. The results indicate that the constant relations and dimensions of corresponding structures within the cristae acusticae of the three species are responsible for the similarities in the tuning of the auditory thresholds.
15. Immediate effects of different frequencies of auditory stimulation on lower limb motor function of healthy people
Science.gov (United States)
Yu, Lili; Huang, Qiuchen; Hu, Chunying; Ye, Miao
2016-01-01
[Purpose] The purpose of this study was to explore the immediate effects of different frequencies of auditory stimulation on the lower limb motor function of healthy people. [Subjects and Methods] The subjects were 7 healthy people (5 males and 2 females). The subjects’ lower limb function was measured without auditory stimulation (control), and with auditory stimulation of 500, 1,000, 1,500, and 2,000 Hz. The measured parameters were maximum knee extension torque, average knee extension torque, the Timed Up and Go test (TUG) time, Functional Reach (FR), and the 10-meter walking time. [Results] The TUG times of 500, 1,500, and 2,000 Hz auditory stimulation showed significant decreases compared to the control. The 10-m walking times of 1,000 and 2,000 Hz auditory stimulation showed significant decreases compared to the control. [Conclusion] The results show that auditory stimulation improved the TUG and 10-meter walking times of healthy people and that different frequencies of auditory stimulation had different effects on lower limb motor function. PMID:27630392
16. Bimanual Coordination Learning with Different Augmented Feedback Modalities and Information Types.
Science.gov (United States)
Chiou, Shiau-Chuen; Chang, Erik Chihhung
2016-01-01
Previous studies have shown that bimanual coordination learning is more resistant to the removal of augmented feedback when acquired with auditory than with visual channel. However, it is unclear whether this differential "guidance effect" between feedback modalities is due to enhanced sensorimotor integration via the non-dominant auditory channel or strengthened linkage to kinesthetic information under rhythmic input. The current study aimed to examine how modalities (visual vs. auditory) and information types (continuous visuospatial vs. discrete rhythmic) of concurrent augmented feedback influence bimanual coordination learning. Participants either learned a 90°-out-of-phase pattern for three consecutive days with Lissajous feedback indicating the integrated position of both arms, or with visual or auditory rhythmic feedback reflecting the relative timing of the movement. The results showed diverse performance change after practice when the feedback was removed between Lissajous and the other two rhythmic groups, indicating that the guidance effect may be modulated by the type of information provided during practice. Moreover, significant performance improvement in the dual-task condition where the irregular rhythm counting task was applied as a secondary task also suggested that lower involvement of conscious control may result in better performance in bimanual coordination.
17. Effects of auditory stimulation with music of different intensities on heart period
OpenAIRE
do Amaral, Joice A.T.; Guida, Heraldo L; de Abreu, Luiz Carlos; Barnabé, Viviani; Vanderlei,Franciele M.; Valenti, Vitor E.
2015-01-01
Various studies have indicated that music therapy with relaxant music improves cardiac function of patients treated with cardiotoxic medication and heavy-metal music acutely reduces heart rate variability (HRV). There is also evidence that white noise auditory stimulation above 50 dB causes cardiac autonomic responses. In this study, we aimed to evaluate the acute effects of musical auditory stimulation with different intensities on cardiac autonomic regulation. This study was performed on 24...
18. OLED lightings with optical feedback for luminance difference compensation
Science.gov (United States)
Shin, D. K.; Park, J. W.
2013-12-01
We have employed an optical feedback circuit in an organic light-emitting diode (OLED) lighting system to ensure uniform light output across large-area OLED lighting tiles. In a lighting system with several large-area OLED lighting tiles involved, the panel aging (luminance decrease) may appear differently in each, resulting in a falling-off in lighting quality. To tackle this, light output from each OLED tile is monitored by the optical feedback circuit that consists of a photodetector, I-V converter, 10-bit analogue-digital converter (ADC), and comparator. A photodetector mounted on a glass side generates a feedback signal (current) by detecting side-emitting OLED light. To monitor bottom-emitting output light by detecting side-emitting OLED light, a mapping table between the ADC value and the luminance of bottom emission has been established. If the ADC value is lower or higher than the reference one corresponding to the target luminance of OLED tiles, a micro controller unit adjusts the pulse width modulation used for the control of the power supplied to OLED tiles in such a way that the ADC value obtained from optical feedback is the same as the reference one. As a result, the target luminance of each individual OLED tile is kept unchanged. With the optical feedback circuit included in the lighting system, we have observed less than 2% difference in relative intensity of neighboring OLED tiles.
19. The predictive ability of different customer feedback metrics for retention
NARCIS (Netherlands)
de Haan, Evert; Verhoef, Peter C.; Wiesel, Thorsten
2015-01-01
This study systematically compares different customer feedback metrics (CFMs) - namely customer satisfaction, the Net Promoter Score, and the Customer Effort Score - to test their ability to predict retention across a wide range of industries. We classify the CFMs according to a time focus (past, pr
20. Different Sequences of Feedback Types: Effectiveness, Attitudes, and Preferences
Science.gov (United States)
Wanchid, Raveewan
2015-01-01
The purposes of this research were to: 1) to compare the effects of different sequences of feedback types on the students' writing ability and their effect size; 2) to compare the effects of the levels of general English proficiency (high, moderate, and low) on the students' writing ability and their effect size; 3) to investigate the interaction…
1. Preferences for Interactional Feedback: Differences between Learners and Teachers
Science.gov (United States)
Kaivanpanah, Shiva; Alavi, Sayyed Mohammad; Sepehrinia, Sajjad
2015-01-01
The present study examines Iranian language learners' views on different types of oral corrective feedback and explores the relationship with learners' language proficiency. It then compares the learners' views with those of their teachers. The study is based on a 36-item questionnaire completed by 154 English as a foreign language (EFL) learners…
2. Age differences in visual-auditory self-motion perception during a simulated driving task
Directory of Open Access Journals (Sweden)
Robert eRamkhalawansingh
2016-04-01
Full Text Available Recent evidence suggests that visual-auditory cue integration may change as a function of age such that integration is heightened among older adults. Our goal was to determine whether these changes in multisensory integration are also observed in the context of self-motion perception under realistic task constraints. Thus, we developed a simulated driving paradigm in which we provided older and younger adults with visual motion cues (i.e. optic flow and systematically manipulated the presence or absence of congruent auditory cues to self-motion (i.e. engine, tire, and wind sounds. Results demonstrated that the presence or absence of congruent auditory input had different effects on older and younger adults. Both age groups demonstrated a reduction in speed variability when auditory cues were present compared to when they were absent, but older adults demonstrated a proportionally greater reduction in speed variability under combined sensory conditions. These results are consistent with evidence indicating that multisensory integration is heightened in older adults. Importantly, this study is the first to provide evidence to suggest that age differences in multisensory integration may generalize from simple stimulus detection tasks to the integration of the more complex and dynamic visual and auditory cues that are experienced during self-motion.
3. Tuning Shifts of the Auditory System By Corticocortical and Corticofugal Projections and Conditioning
OpenAIRE
Suga, Nobuo
2011-01-01
The central auditory system consists of the lemniscal and nonlemniscal systems. The thalamic lemniscal and non-lemniscal auditory nuclei are different from each other in response properties and neural connectivities. The cortical auditory areas receiving the projections from these thalamic nuclei interact with each other through corticocortical projections and project down to the subcortical auditory nuclei. This corticofugal (descending) system forms multiple feedback loops with the ascendin...
4. Auditory and motor imagery modulate learning in music performance
Directory of Open Access Journals (Sweden)
Rachel M. Brown
2013-07-01
Full Text Available Skilled performers such as athletes or musicians can improve their performance by imagining the actions or sensory outcomes associated with their skill. Performers vary widely in their auditory and motor imagery abilities, and these individual differences influence sensorimotor learning. It is unknown whether imagery abilities influence both memory encoding and retrieval. We examined how auditory and motor imagery abilities influence musicians’ encoding (during Learning, as they practiced novel melodies, and retrieval (during Recall of those melodies. Pianists learned melodies by listening without performing (auditory learning or performing without sound (motor learning; following Learning, pianists performed the melodies from memory with auditory feedback (Recall. During either Learning (Experiment 1 or Recall (Experiment 2, pianists experienced either auditory interference, motor interference, or no interference. Pitch accuracy (percentage of correct pitches produced and temporal regularity (variability of quarter-note interonset intervals were measured at Recall. Independent tests measured auditory and motor imagery skills. Pianists’ pitch accuracy was higher following auditory learning than following motor learning and lower in motor interference conditions (Experiments 1 and 2. Both auditory and motor imagery skills improved pitch accuracy overall. Auditory imagery skills modulated pitch accuracy encoding (Experiment 1: Higher auditory imagery skill corresponded to higher pitch accuracy following auditory learning with auditory or motor interference, and following motor learning with motor or no interference. These findings suggest that auditory imagery abilities decrease vulnerability to interference and compensate for missing auditory feedback at encoding. Auditory imagery skills also influenced temporal regularity at retrieval (Experiment 2: Higher auditory imagery skill predicted greater temporal regularity during Recall in the
5. Self-generated auditory feedback as a cue to support rhythmic motor stability
DEFF Research Database (Denmark)
Krupenia, Stas S.; Hoffmann, Pablo F.; Zalmanov, Hagar
2011-01-01
A goal of the SKILLS project is to develop Virtual Reality (VR)-based training simulators for different application domains, one of which is juggling. Within this context the value of multimodal VR environments for skill acquisition is investigated. In this study, we investigated whether it was n...
6. Exploration of auditory P50 gating in schizophrenia by way of difference waves
DEFF Research Database (Denmark)
Arnfred, Sidse M
2006-01-01
ABSTRACT : Electroencephalographic measures of information processing encompass both mid-latency evoked potentials like the pre-attentive auditory P50 potential and a host of later more cognitive components like P300 and N400.Difference waves have mostly been employed in studies of later event...
7. Auditory feedback of one’s own voice is used for high-level semantic monitoring: the self-comprehension hypothesis
Directory of Open Access Journals (Sweden)
Andreas eLind
2014-03-01
Full Text Available What would it be like if we said one thing, and heard ourselves saying something else? Would we notice something was wrong? Or would we believe we said the thing we heard? Is feedback of our own speech only used to detect errors, or does it also help to specify the meaning of what we say? Comparator models of self-monitoring favor the first alternative, and hold that our sense of agency is given by the comparison between intentions and outcomes, while inferential models argue that agency is a more fluent construct, dependent on contextual inferences about the most likely cause of an action. In this paper, we present a theory about the use of feedback during speech. Specifically, we discuss inferential models of speech production that question the standard comparator assumption that the meaning of our utterances is fully specified before articulation. We then argue that auditory feedback provides speakers with a channel for high-level, semantic self-comprehension. In support of this we discuss results using a method we recently developed called Real-time Speech Exchange (RSE. In our first study using RSE (Lind et al, submitted participants were fitted with headsets and performed a computerized Stroop task. We surreptitiously recorded words they said, and later in the test we played them back at the exact same time that the participants uttered something else, while blocking the actual feedback of their voice. Thus, participants said one thing, but heard themselves saying something else. The results showed that when timing conditions were ideal, more than two thirds of the manipulations went undetected. Crucially, in a large proportion of the non-detected manipulated trials, the inserted words were experienced as self-produced by the participants. This indicates that our sense of agency for speech has a strong inferential component, and that auditory feedback of our own voice acts as a pathway for semantic monitoring.
8. Asymmetric excitatory synaptic dynamics underlie interaural time difference processing in the auditory system.
Directory of Open Access Journals (Sweden)
Pablo E Jercog
Full Text Available Low-frequency sound localization depends on the neural computation of interaural time differences (ITD and relies on neurons in the auditory brain stem that integrate synaptic inputs delivered by the ipsi- and contralateral auditory pathways that start at the two ears. The first auditory neurons that respond selectively to ITD are found in the medial superior olivary nucleus (MSO. We identified a new mechanism for ITD coding using a brain slice preparation that preserves the binaural inputs to the MSO. There was an internal latency difference for the two excitatory pathways that would, if left uncompensated, position the ITD response function too far outside the physiological range to be useful for estimating ITD. We demonstrate, and support using a biophysically based computational model, that a bilateral asymmetry in excitatory post-synaptic potential (EPSP slopes provides a robust compensatory delay mechanism due to differential activation of low threshold potassium conductance on these inputs and permits MSO neurons to encode physiological ITDs. We suggest, more generally, that the dependence of spike probability on rate of depolarization, as in these auditory neurons, provides a mechanism for temporal order discrimination between EPSPs.
9. Material differences of auditory source retrieval:Evidence from event-related potential studies
Institute of Scientific and Technical Information of China (English)
NIE AiQing; GUO ChunYan; SHEN MoWei
2008-01-01
Two event-related potential experiments were conducted to investigate the temporal and the spatial distributions of the old/new effects for the item recognition task and the auditory source retrieval task using picture and Chinese character as stimuli respectively. Stimuli were presented on the center of the screen with their names read out either by female or by male voice simultaneously during the study phase and then two testa were performed separately. One test task was to differentiate the old items from the new ones, and the other task was to judge the items read out by a certain voice during the study phase as targets and other ones as non-targets. The results showed that the old/new effect of the auditory source retrieval task was more sustained over time than that of the item recognition task in both experiments, and the spatial distribution of the former effect was wider than that of the latter one. Both experiments recorded reliable old/new effect over the prefrontal cortex during the source retrieval task. However, there existed some differences of the old/new effect for the auditory source retrieval task between picture and Chinese character, and LORETA source analysis indicated that the differ-ences might be rooted in the temporal lobe. These findings demonstrate that the relevancy of the old/new effects between the item recognition task and the auditory source retrieval task supports the dual-process model; the spatial and the temporal distributions of the old/new effect elicited by the auditory source retrieval task are regulated by both the feature of the experimental material and the perceptual attribute of the voice.
10. Differences in auditory processing of words and pseudowords: an fMRI study.
Science.gov (United States)
Newman, S D; Twieg, D
2001-09-01
Although there has been great interest in the neuroanatomical basis of reading, little attention has been focused on auditory language processing. The purpose of this study was to examine the differential neuroanatomical response to the auditory processing of real words and pseudowords. Eight healthy right-handed participants performed two phoneme monitoring tasks (one with real word stimuli and one with pseudowords) during a functional magnetic resonance imaging (fMRI) scan with a 4.1 T system. Both tasks activated the inferior frontal gyrus (IFG), the posterior superior temporal gyrus (pSTG) and the inferior parietal lobe (IPL). Pseudoword processing elicited significantly more activation within the posterior cortical regions compared with real word processing. Previous reading studies have suggested that this increase is due to an increased demand on the lexical access system. The left inferior frontal gyrus, on the other hand, did not reveal a significant difference in the amount of activation as a function of stimulus type. The lack of a differential response in IFG for auditory processing supports its hypothesized involvement in grapheme to phoneme conversion processes. These results are consistent with those from previous neuroimaging reading studies and emphasize the utility of examining both input modalities (e.g., visual or auditory) to compose a more complete picture of the language network.
11. Auditory skills and brain morphology predict individual differences in adaptation to degraded speech.
Science.gov (United States)
Erb, Julia; Henry, Molly J; Eisner, Frank; Obleser, Jonas
2012-07-01
Noise-vocoded speech is a spectrally highly degraded signal, but it preserves the temporal envelope of speech. Listeners vary considerably in their ability to adapt to this degraded speech signal. Here, we hypothesised that individual differences in adaptation to vocoded speech should be predictable by non-speech auditory, cognitive, and neuroanatomical factors. We tested 18 normal-hearing participants in a short-term vocoded speech-learning paradigm (listening to 100 4-band-vocoded sentences). Non-speech auditory skills were assessed using amplitude modulation (AM) rate discrimination, where modulation rates were centred on the speech-relevant rate of 4 Hz. Working memory capacities were evaluated (digit span and nonword repetition), and structural MRI scans were examined for anatomical predictors of vocoded speech learning using voxel-based morphometry. Listeners who learned faster to understand degraded speech also showed smaller thresholds in the AM discrimination task. This ability to adjust to degraded speech is furthermore reflected anatomically in increased grey matter volume in an area of the left thalamus (pulvinar) that is strongly connected to the auditory and prefrontal cortices. Thus, individual non-speech auditory skills and left thalamus grey matter volume can predict how quickly a listener adapts to degraded speech.
12. Rehabilitation of the Upper Extremity after Stroke: A Case Series Evaluating REO Therapy and an Auditory Sensor Feedback for Trunk Control
Directory of Open Access Journals (Sweden)
G. Thielman
2012-01-01
Full Text Available Background and Purpose. Training in the virtual environment in post stroke rehab is being established as a new approach for neurorehabilitation, specifically, ReoTherapy (REO a robot-assisted virtual training device. Trunk stabilization strapping has been part of the concept with this device, and literature is lacking to support this for long-term functional changes with individuals after stroke. The purpose of this case series was to measure the feasibility of auditory trunk sensor feedback during REO therapy, in moderate to severely impaired individuals after stroke. Case Description. Using an open label crossover comparison design, 3 chronic stroke subjects were trained for 12 sessions over six weeks on either the REO or the control condition of task related training (TRT; after a washout period of 4 weeks; the alternative therapy was given. Outcomes. With both interventions, clinically relevant improvements were found for measures of body function and structure, as well as for activity, for two participants. Providing auditory feedback during REO training for trunk control was found to be feasible. Discussion. The degree of changes evident varied per protocol and may be due to the appropriateness of the technique chosen, as well as based on patients impaired arm motor control.
13. Feedback.
Science.gov (United States)
Richardson, Barbara K
2004-12-01
The emergency department provides a rich environment for diverse patient encounters, rapid clinical decision making, and opportunities to hone procedural skills. Well-prepared faculty can utilize this environment to teach residents and medical students and gain institutional recognition for their incomparable role and teamwork. Giving effective feedback is an essential skill for all teaching faculty. Feedback is ongoing appraisal of performance based on direct observation aimed at changing or sustaining a behavior. Tips from the literature and the author's experience are reviewed to provide formats for feedback, review of objectives, and elements of professionalism and how to deal with poorly performing students. Although the following examples pertain to medical student education, these techniques are applicable to the education of all adult learners, including residents and colleagues. Specific examples of redirection and reflection are offered, and pitfalls are reviewed. Suggestions for streamlining verbal and written feedback and obtaining feedback from others in a fast-paced environment are given. Ideas for further individual and group faculty development are presented.
14. Acute auditory stimulation with different styles of music influences cardiac autonomic regulation in men
OpenAIRE
da Silva, Sheila Ap. F.; Guida, Heraldo L; Ana Marcia dos Santos Antonio; Luiz Carlos de Abreu; Monteiro, Carlos B. M.; Celso Ferreira; Ribeiro, Vivian F.; Viviani Barnabe; Silva, Sidney B; FERNANDO L.A. FONSECA; Fernando Adami; Marcio Petenusso; Raimundo, Rodrigo D; Valenti, Vitor E.
2014-01-01
Background: No clear evidence is available in the literature regarding the acute effect of different styles of music on cardiac autonomic control. Objectives: The present study aimed to evaluate the acute effects of classical baroque and heavy metal musical auditory stimulation on Heart Rate Variability (HRV) in healthy men. Patients and Methods: In this study, HRV was analyzed regarding time (SDNN, RMSSD, NN50, and pNN50) and frequency domain (LF, HF, and LF / HF) in 12 healthy men. ...
15. The effects of different styles of musical auditory stimulation on cardiac autonomic regulation in healthy women
OpenAIRE
Roque, Adriano L. [UNESP; Valenti, Vitor E.; Guida, Heraldo L; Campos, Mônica F.; André Knap; Vanderlei, Luiz Carlos M. [UNESP; Celso Ferreira; Luiz Carlos de Abreu
2013-01-01
The literature investigated the effects of chronic baroque music auditory stimulation on the cardiovascular system. However, it lacks in the literature the acute effects of different styles of music on cardiac autonomic regulation. To evaluate the acute effects of baroque and heavy metal music on heart rate variability (HRV) in women. The study was performed in 21 healthy women between 18 and 30 years old. We excluded persons with previous experience with music instrument and those who had af...
16. The effects of different styles of musical auditory stimulation on cardiac autonomic regulation in healthy women
OpenAIRE
Roque, Adriano Luís; Valenti, Vitor Engrácia; Guida, Heraldo Lorena; Campos, Monica F.; Knap, Andre; Vanderlei, Luiz Carlos Marques; Ferreira, Celso; de Abreu, Luiz Carlos
2013-01-01
The literature investigated the effects of chronic baroque music auditory stimulation on the cardiovascular system. However, it lacks in the literature the acute effects of different styles of music on cardiac autonomic regulation. To evaluate the acute effects of baroque and heavy metal music on heart rate variability (HRV) in women. the study was performed in 21 healthy women between 18 and 30 years old. We excluded persons with previous experience with music instrument and those who had af...
17. Gender differences in reward and punishment for monetary and social feedback in children: An ERP study
Science.gov (United States)
Zou, Yuchen; Song, Yan; Xiao, Xue; Huang, Wanyi; Li, Yanfang
2017-01-01
Gender differences in feedback processing have been observed among adolescents and adults through event-related potentials. However, information on whether and how this feedback processing is affected by feedback valence, feedback type, and individual sensitivity in reward/punishment among children remains minimal. In this study, we used a guessing game task coupled with electroencephalography to investigate gender differences in feedback processing, in which feedback to reward and punishment was presented in the context of monetary and social conditions. Results showed that boys were less likely to switch their response after punishment, had generally less feedback-related negativity (FRN) amplitude, and longer FRN latency in monetary and punishment conditions than girls. Moreover, FRN for monetary punishment, which is related to individual difference in reward sensitivity, was observed only in girls. The study provides gender-specific evidence for the neural processing of feedback, which may offer educational guidance for appropriate feedback for girls and boys. PMID:28346515
18. Enhanced entanglement of two different mechanical resonators via coherent feedback
CERN Document Server
Li, Jie; Zippilli, Stefano; Vitali, David; Zhang, Tiancai
2016-01-01
It is shown [New J. Phys. 17, 103037 (2015)] that extremely large and robust entanglement between two different mechanical resonators could be achieved, either dynamically or in the steady state, in an optomechanical system in which a single cavity mode driven by a suitably chosen two-tone field is coupled to two mechanical modes. The main limitation of the scheme is that the cavity decay rate must be much smaller than the two mechanical frequencies and their difference, allowing taking the rotating wave approximation where counter-rotating, non-resonant terms associated with the bichromatic driving are negligible. Here we show that, by simply adding a coherent feedback loop, the large entanglement can be remarkably enhanced and the effective cavity decay rate can be significantly reduced. Therefore, it improves the results of Ref. [New J. Phys. 17, 103037 (2015)] and meantime greatly extends the validity of the scheme.
19. Effects of broadband noise on cortical evoked auditory responses at different loudness levels in young adults.
Science.gov (United States)
Sharma, Mridula; Purdy, Suzanne C; Munro, Kevin J; Sawaya, Kathleen; Peter, Varghese
2014-03-26
Young adults with no history of hearing concerns were tested to investigate their /da/-evoked cortical auditory evoked potentials (P1-N1-P2) recorded from 32 scalp electrodes in the presence and absence of noise at three different loudness levels (soft, comfortable, and loud), at a fixed signal-to-noise ratio (+3 dB). P1 peak latency significantly increased at soft and loud levels, and N1 and P2 latencies increased at all three levels in the presence of noise, compared with the quiet condition. P1 amplitude was significantly larger in quiet than in noise conditions at the loudest level. N1 amplitude was larger in quiet than in noise for the soft level only. P2 amplitude was reduced in the presence of noise to a similar degree at all loudness levels. The differential effects of noise on P1, N1, and P2 suggest differences in auditory processes underlying these peaks. The combination of level and signal-to-noise ratio should be considered when using cortical auditory evoked potentials as an electrophysiological indicator of degraded speech processing.
20. Using auditory pre-information to solve the cocktail-party problem: electrophysiological evidence for age-specific differences
Directory of Open Access Journals (Sweden)
Stephan eGetzmann
2014-12-01
Full Text Available Speech understanding in complex and dynamic listening environments requires (a auditory scene analysis, namely auditory object formation and segregation, and (b allocation of the attentional focus to the talker of interest. There is evidence that pre-information is actively used to facilitate these two aspects of the so-called cocktail-party problem. Here, a simulated multi-talker scenario was combined with electroencephalography to study scene analysis and allocation of attention in young and middle-aged adults. Sequences of short words (combinations of brief company names and stock-price values from four talkers at different locations were simultaneously presented, and the detection of target names and the discrimination between critical target values were assessed. Immediately prior to speech sequences, auditory pre-information was provided via cues that either prepared auditory scene analysis or attentional focusing, or non-specific pre-information was given. While performance was generally better in younger than older participants, both age groups benefited from auditory pre-information. The analysis of the cue-related event-related potentials revealed age-specific differences in the use of pre-cues: Younger adults showed a pronounced N2 component, suggesting early inhibition of concurrent speech stimuli; older adults exhibited a stronger late P3 component, suggesting increased resource allocation to process the pre-information. In sum, the results argue for an age-specific utilization of auditory pre-information to improve listening in complex dynamic auditory environments.
1. Cardiac autonomic regulation during exposure to auditory stimulation with classical baroque or heavy metal music of different intensities
OpenAIRE
Amaral, Joice Anaize Tonon do; Nogueira, MArcela Leme; Roque, Adriano L. [UNESP; Guida, Heraldo Lorena; de Abreu, Luiz Carlos; Raimundo, Rodrigo Daminello; Vanderlei, Luiz Carlos Marques; Ribeiro, Vivian F.; Ferreira, Celso; Valenti, Vitor Engrácia
2014-01-01
Objectives: The effects of chronic music auditory stimulation on the cardiovascular system have been investigated in the literature. However, data regarding the acute effects of different styles of music on cardiac autonomic regulation are lacking. The literature has indicated that auditory stimulation with white noise above 50 dB induces cardiac responses. We aimed to evaluate the acute effects of classical baroque and heavy metal music of different intensities on cardiac autonomic regulatio...
2. Muscle involvement during intermittent contraction patterns with different target force feedback modes
DEFF Research Database (Denmark)
Sjøgaard, G; Jørgensen, L V; Ekner, D
2000-01-01
OBJECTIVE: Assess the effect of different feedback modes during intermittent contractions on primary and assessory muscle activity. BACKGROUND: Intermittent contractions and physiological responses have been studied in laboratory settings. However, the feedback given to the subjects regarding...... the two different feedback modes. In line with this, EMG recorded from four shoulder/arm muscles analyzed for amplitude and frequency showed similar activity initially; but later, during the 30 min contraction larger amplitudes were attained during proprioceptive feedback than visual feedback. CONCLUSIONS......: Feedback mode significantly effects the muscle involvement and fatigue during intermittent contractions. RelevanceIntermittent contractions are common in many work places and various feedback modes are being given regarding work requirements. The choice of feedback may significantly affect the muscle load...
3. [Age differences of event-related potentials in the perception of successive and spacial components of auditory information].
Science.gov (United States)
Portnova, G V; Martynova, O V; Ivanitskiĭ, G A
2014-01-01
The perception of spatial and successive contexts of auditory information develops during human ontogeny. We compared event-related potentials (ERPs) recorded in 5- to 6-year-old children (N = 15) and adults (N = 15) in response to a digital series with omitted digits to explore age differences in the perception of successive auditory information. In addition, ERPs in response to the sound of falling drops delivered binaurally were obtained to examine the spatial context of auditory information. The ERPs obtained from the omitted digits significantly differed in the amplitude and latency of the N200 and P300 components between adults and children, which supports the hypothesis that the perception of a successive auditory structure is less automated in children compared with adults. Although no significant differences were found in adults, the sound of falling drops presented to the left ears of children elicited ERPs with earlier latencies and higher amplitudes of P300 and N400 components in the right temporal area. Stimulation of the right ear caused increasing amplitude of the N100 component in children. Thus, the observed differences in auditory ERPs of children and adults reflect developmental changes in the perception of spatial and successive auditory information.
4. Auditory same/different concept learning and generalization in black-capped chickadees (Poecile atricapillus).
Science.gov (United States)
Hoeschele, Marisa; Cook, Robert G; Guillette, Lauren M; Hahn, Allison H; Sturdy, Christopher B
2012-01-01
Abstract concept learning was thought to be uniquely human, but has since been observed in many other species. Discriminating same from different is one abstract relation that has been studied frequently. In the current experiment, using operant conditioning, we tested whether black-capped chickadees (Poecile atricapillus) could discriminate sets of auditory stimuli based on whether all the sounds within a sequence were the same or different from one another. The chickadees were successful at solving this same/different relational task, and transferred their learning to same/different sequences involving novel combinations of training notes and novel notes within the range of pitches experienced during training. The chickadees showed limited transfer to pitches that was not used in training, suggesting that the processing of absolute pitch may constrain their relational performance. Our results indicate, for the first time, that black-capped chickadees readily form relational auditory same and different categories, adding to the list of perceptual, behavioural, and cognitive abilities that make this species an important comparative model for human language and cognition.
5. State-dependent changes in auditory sensory gating in different cortical areas in rats.
Directory of Open Access Journals (Sweden)
Renli Qi
Full Text Available Sensory gating is a process in which the brain's response to a repetitive stimulus is attenuated; it is thought to contribute to information processing by enabling organisms to filter extraneous sensory inputs from the environment. To date, sensory gating has typically been used to determine whether brain function is impaired, such as in individuals with schizophrenia or addiction. In healthy subjects, sensory gating is sensitive to a subject's behavioral state, such as acute stress and attention. The cortical response to sensory stimulation significantly decreases during sleep; however, information processing continues throughout sleep, and an auditory evoked potential (AEP can be elicited by sound. It is not known whether sensory gating changes during sleep. Sleep is a non-uniform process in the whole brain with regional differences in neural activities. Thus, another question arises concerning whether sensory gating changes are uniform in different brain areas from waking to sleep. To address these questions, we used the sound stimuli of a Conditioning-testing paradigm to examine sensory gating during waking, rapid eye movement (REM sleep and Non-REM (NREM sleep in different cortical areas in rats. We demonstrated the following: 1. Auditory sensory gating was affected by vigilant states in the frontal and parietal areas but not in the occipital areas. 2. Auditory sensory gating decreased in NREM sleep but not REM sleep from waking in the frontal and parietal areas. 3. The decreased sensory gating in the frontal and parietal areas during NREM sleep was the result of a significant increase in the test sound amplitude.
6. Effects of auditory stimulation with music of different intensities on heart period.
Science.gov (United States)
do Amaral, Joice A T; Guida, Heraldo L; de Abreu, Luiz Carlos; Barnabé, Viviani; Vanderlei, Franciele M; Valenti, Vitor E
2016-01-01
Various studies have indicated that music therapy with relaxant music improves cardiac function of patients treated with cardiotoxic medication and heavy-metal music acutely reduces heart rate variability (HRV). There is also evidence that white noise auditory stimulation above 50 dB causes cardiac autonomic responses. In this study, we aimed to evaluate the acute effects of musical auditory stimulation with different intensities on cardiac autonomic regulation. This study was performed on 24 healthy women between 18 and 25 years of age. We analyzed HRV in the time [standard deviation of normal-to-normal RR intervals (SDNN), percentage of adjacent RR intervals with a difference of duration >50 ms (pNN50), and root-mean square of differences between adjacent normal RR intervals in a time interval (RMSSD)] and frequency [low frequency (LF), high frequency (HF), and LF/HF ratio] domains. HRV was recorded at rest for 10 minutes. Subsequently, the volunteers were exposed to baroque or heavy-metal music for 5 minutes through an earphone. The volunteers were exposed to three equivalent sound levels (60-70, 70-80, and 80-90 dB). After the first baroque or heavy-metal music, they remained at rest for 5 minutes and then they were exposed to the other music. The sequence of songs was randomized for each individual. Heavy-metal musical auditory stimulation at 80-90 dB reduced the SDNN index compared with control (44.39 ± 14.40 ms vs. 34.88 ± 8.69 ms), and stimulation at 60-70 dB decreased the LF (ms(2)) index compared with control (668.83 ± 648.74 ms(2) vs. 392.5 ± 179.94 ms(2)). Baroque music at 60-70 dB reduced the LF (ms(2)) index (587.75 ± 318.44 ms(2) vs. 376.21 ± 178.85 ms(2)). In conclusion, heavy-metal and baroque musical auditory stimulation at lower intensities acutely reduced global modulation of the heart and only heavy-metal music reduced HRV at higher intensities.
7. Automatic Thermal Control System with Temperature Difference or Derivation Feedback
Directory of Open Access Journals (Sweden)
Darina Matiskova
2016-02-01
Full Text Available Automatic thermal control systems seem to be non-linear systems with thermal inertias and time delay. A controller is also non-linear because its information and power signals are limited. The application of methods that are available to on-linear systems together with computer simulation and mathematical modelling creates a possibility to acquire important information about the researched system. This paper provides a new look at the heated system model and also designs the structure of the thermal system with temperature derivation feedback. The designed system was simulated by using a special software in Turbo Pascal. Time responses of this system are compared to responses of a conventional thermal system. The thermal system with temperature derivation feedback provides better transients, better quality of regulation and better dynamical properties.
8. Employing Different Ways to Provide Large Class Formative Feedback in College English Teaching
Institute of Scientific and Technical Information of China (English)
Yang Lihua; Yang Bo; Ou Ying
2015-01-01
Formative feedback is usually regarded as crucial for encouraging and consolidating students’ learning. Appropriate and timely formative feedback can help motivate and develop student’s knowledge, skills and understanding in some content area or general skills. In this paper, the authors provide college English instructors with different ways of offering flexible, prompt, effective and directive formative feedback to large class in college English teaching.
9. Driver reactions on ecological feedback via different HMI modalities
OpenAIRE
Staubach, Maria; Kassner, Astrid; Fricke, Nicola; Schießl, Caroline; Brockmann, Martin; Kuck, Detlef
2012-01-01
Nowadays there already exists a large amount of driving-related information displayed in the dashboard and thus additional information concerning ecological driving might enlarge the workload of the driver further. This raises the question whether the presentation of additional ecologic information via the haptic channel is more efficient and comfortable for the driver compared to a visual presentation. Previous studies proved the impact of driver feedback systems on the reduction of fuel con...
10. Time course of auditory streaming: Do CI users differ from normal-hearing listeners?
Directory of Open Access Journals (Sweden)
Martin eBöckmann-Barthel
2014-07-01
Full Text Available In a complex acoustical environment with multiple sound sources the auditory system uses streaming as a tool to organize the incoming sounds in one or more streams depending on the stimulus parameters. Streaming is commonly studied by alternating sequences of signals. These are often tones with different frequencies. The present study investigates stream segregation in cochlear implant (CI users, where hearing is restored by electrical stimulation of the auditory nerve. CI users listened to 30-s long sequences of alternating A and B harmonic complexes at four different fundamental frequency separations, ranging from 2 to 14 semitones. They had to indicate as promptly as possible after sequence onset, if they perceived one stream or two streams and, in addition, any changes of the percept throughout the rest of the sequence. The conventional view is that the initial percept is always that of a single stream which may after some time change to a percept of two streams. This general build-up hypothesis has recently been challenged on the basis of a new analysis of data of normal-hearing listeners which showed a build-up response only for an intermediate frequency separation. Using the same experimental paradigm and analysis, the present study found that the results of CI users agree with those of the normal-hearing listeners: (i the probability of the first decision to be a one-stream percept decreased and that of a two-stream percept increased as Δf increased, and (ii a build-up was only found for 6 semitones. Only the time elapsed before the listeners made their first decision of the percept was prolonged as compared to normal-hearing listeners. The similarity in the data of the CI user and the normal-hearing listeners indicates that the quality of stream formation is similar in these groups of listeners.
11. Auditory and Visual Differences in Time Perception? An Investigation from a Developmental Perspective with Neuropsychological Tests
Science.gov (United States)
Zelanti, Pierre S.; Droit-Volet, Sylvie
2012-01-01
Adults and children (5- and 8-year-olds) performed a temporal bisection task with either auditory or visual signals and either a short (0.5-1.0s) or long (4.0-8.0s) duration range. Their working memory and attentional capacities were assessed by a series of neuropsychological tests administered in both the auditory and visual modalities. Results…
12. Individual Differences in Auditory Sentence Comprehension in Children: An Exploratory Event-Related Functional Magnetic Resonance Imaging Investigation
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Yeatman, Jason D.; Ben-Shachar, Michal; Glover, Gary H.; Feldman, Heidi M.
2010-01-01
The purpose of this study was to explore changes in activation of the cortical network that serves auditory sentence comprehension in children in response to increasing demands of complex sentences. A further goal is to study how individual differences in children's receptive language abilities are associated with such changes in cortical…
13. Auditory efferent feedback system deficits precede age-related hearing loss: contralateral suppression of otoacoustic emissions in mice.
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Zhu, Xiaoxia; Vasilyeva, Olga N; Kim, Sunghee; Jacobson, Michael; Romney, Joshua; Waterman, Marjorie S; Tuttle, David; Frisina, Robert D
2007-08-10
The C57BL/6J mouse has been a useful model of presbycusis, as it displays an accelerated age-related peripheral hearing loss. The medial olivocochlear efferent feedback (MOC) system plays a role in suppressing cochlear outer hair cell (OHC) responses, particularly for background noise. Neurons of the MOC system are located in the superior olivary complex, particularly in the dorsomedial periolivary nucleus (DMPO) and in the ventral nucleus of the trapezoid body (VNTB). We previously discovered that the function of the MOC system declines with age prior to OHC degeneration, as measured by contralateral suppression (CS) of distortion product otoacoustic emissions (DPOAEs) in humans and CBA mice. The present study aimed to determine the time course of age changes in MOC function in C57s. DPOAE amplitudes and CS of DPOAEs were collected for C57s from 6 to 40 weeks of age. MOC responses were observed at 6 weeks but were gone at middle (15-30 kHz) and high (30-45 kHz) frequencies by 8 weeks. Quantitative stereological analyses of Nissl sections revealed smaller neurons in the DMPO and VNTB of young adult C57s compared with CBAs. These findings suggest that reduced neuron size may underlie part of the noteworthy rapid decline of the C57 efferent system. In conclusion, the C57 mouse has MOC function at 6 weeks, but it declines quickly, preceding the progression of peripheral age-related sensitivity deficits and hearing loss in this mouse strain.
14. The Same or Different? A Phenomenological Comparison of Auditory Verbal Hallucinations in Healthy and Psychotic Individuals
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Daalman, Kirstin; Boks, Marco P. M.; Diederen, Kelly M. J.; de Weijer, Antoin D.; Blom, Jan Dirk; Kahn, Rene S.; Sommer, Iris E. C.
2011-01-01
Objective: Whereas auditory verbal hallucinations (AVHs) are most characteristic of schizophrenia, their presence has frequently been described in a continuum, ranging from severely psychotic patients to schizotypal personality disorder patients to otherwise healthy participants. It remains unclear
15. How do auditory verbal hallucinations in patients differ from those in non-patients?
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Larøi, Frank
2012-01-01
Auditory verbal hallucinations (AVHs) are experienced by individuals with various clinical diagnoses, such as psychosis, but also a significant minority of healthy individuals from the general population may experience them. Although much research has been carried out the past few decades, the mechanisms and factors underlying the emergence of AVHs is still poorly understood. One way of clarifying this issue involves comparing AVHs in patient and non-patient populations. In particular, differences between these groups will provide important information concerning the emergence of AVHs. After a general presentation and discussion of the notion of a continuum hypothesis, studies comparing patients with non-patients experiencing AVHs will be reviewed. This will comprise studies examining the phenomenological characteristics of AVHs in addition to neuroimaging and cognitive studies. Although we are beginning to elucidate important differences on a phenomenological level between these two types of AVHs, far too few studies have directly compared patient and non-patient AVHs in terms of underlying cerebral correlates and cognitive mechanisms. Nevertheless, and based on recent research on phenomenological differences, two issues stand out that need to be addressed, namely, the highly negative emotional content of AVHs in patients and the early onset of AVHs in non-patients populations. Suggestions for future research will be discussed.
16. ERP Indications for Sustained and Transient Auditory Spatial Attention with Different Lateralization Cues
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Widmann, Andreas; Schröger, Erich
The presented study was designed to investigate ERP effects of auditory spatial attention in sustained attention condition (where the to-be-attended location is defined in a blockwise manner) and in a transient attention condition (where the to-be-attended location is defined in a trial-by-trial manner). Lateralization in the azimuth plane was manipulated (a) via monaural presentation of l- and right-ear sounds, (b) via interaural intensity differences, (c) via interaural time differences, (d) via an artificial-head recording, and (e) via free-field stimulation. Ten participants were delivered with frequent Nogo- and infrequent Go-Stimuli. In one half of the experiment participants were instructed to press a button if they detected a Go-stimulus at a predefined side (sustained attention), in the other half they were required to detect Go-stimuli following an arrow-cue at the cued side (transient attention). Results revealed negative differences (Nd) between ERPs elicited by to-be-attended and to-be-ignored sounds in all conditions. These Nd-effects were larger for the sustained than for the transient attention condition indicating that attentional selection according to spatial criteria is improved when subjects can focus to one and the same location for a series of stimuli.
17. Neural basis of the time window for subjective motor-auditory integration
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Koichi eToida
2016-01-01
Full Text Available Temporal contiguity between an action and corresponding auditory feedback is crucial to the perception of self-generated sound. However, the neural mechanisms underlying motor–auditory temporal integration are unclear. Here, we conducted four experiments with an oddball paradigm to examine the specific event-related potentials (ERPs elicited by delayed auditory feedback for a self-generated action. The first experiment confirmed that a pitch-deviant auditory stimulus elicits mismatch negativity (MMN and P300, both when it is generated passively and by the participant’s action. In our second and third experiments, we investigated the ERP components elicited by delayed auditory feedback of for a self-generated action. We found that delayed auditory feedback elicited an enhancement of P2 (enhanced-P2 and a N300 component, which were apparently different from the MMN and P300 components observed in the first experiment. We further investigated the sensitivity of the enhanced-P2 and N300 to delay length in our fourth experiment. Strikingly, the amplitude of the N300 increased as a function of the delay length. Additionally, the N300 amplitude was significantly correlated with the conscious detection of the delay (the 50% detection point was around 200 ms, and hence reduction in the feeling of authorship of the sound (the sense of agency. In contrast, the enhanced-P2 was most prominent in short-delay (≤ 200 ms conditions and diminished in long-delay conditions. Our results suggest that different neural mechanisms are employed for the processing of temporally-deviant and pitch-deviant auditory feedback. Additionally, the temporal window for subjective motor–auditory integration is likely about 200 ms, as indicated by these auditory ERP components.
18. Sex differences in equiprobable auditory Go/NoGo task: effects on N2 and P3.
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Melynyte, Sigita; Ruksenas, Osvaldas; Griskova-Bulanova, Inga
2017-03-03
The Go/NoGo variants of the auditory event-related potentials were shown promising for clinical researches; however, prior to the wider application, it is important to evaluate potential modulating factors. We aimed to evaluate gender effect on the behavioral and electrophysiological responses in an auditory equiprobable Go/NoGo task. The auditory equal probability Go/NoGo paradigm with two types of stimuli was presented to 79 healthy subjects (40 females and 39 males, age 18-30 years) during EEG recording. Behavioral performance, latency and amplitude of N2 and P3 waves in the Go and the NoGo conditions were evaluated and compared between genders. The response times did not differ between genders; however, females were less accurate on the task. They also exhibited slower N2s and P3s in both Go and NoGo conditions and higher P3 amplitudes. Our results suggest that females require longer times for monitoring of response conflict (N2s) and outcome inhibition (NoGo-P3) and more neural resources and longer processing times for motor response execution (Go-P3). The research provides evidence that gender factor is important in the Go/NoGo studies employing auditory equiprobable paradigm.
19. Audit and feedback intervention: An examination of differences in chiropractic record-keeping compliance.
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Homb, Nicole M; Sheybani, Shayan; Derby, Dustin; Wood, Kurt
2014-10-01
Objective : The objective of this study was to investigate the association of a clinical documentation quality improvement program using audit-feedback with clinical compliance to indicators of quality chart documentation. Methods : This was an analysis of differences between adherence to quality indicators of chiropractic record documentation and audit-feedback intervention (feedback report only vs. feedback report with one-on-one educational consultation) at different campuses. Comparisons among groups were analyzed using analysis of variance (ANOVA), Tukey or Dunnett post hoc tests, and Cohen's d effect size estimates. Results : There was a significant increase in the mean percentile compliance in 2 of 5 compliance areas and 1 of 11 compliance objectives. Campus B demonstrated significantly higher levels of compliance relative to campus A and/or campus C in 5 of 5 compliance areas and 7 of 11 compliance objectives. Across-campus comparisons indicated that the compliance area Review (Non-Medicare) Treatment Plan [F(2,18) = 17.537, p importance for clinical compliance practice. Conclusions : Feedback of performance improved compliance to indicators of quality health record documentation, especially when baseline adherence is relatively low. Required educational consultations with clinicians combined with audit-feedback were no more effective at increasing compliance to indicators of quality health record documentation than audit-feedback alone.
20. Tuning shifts of the auditory system by corticocortical and corticofugal projections and conditioning.
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Suga, Nobuo
2012-02-01
The central auditory system consists of the lemniscal and nonlemniscal systems. The thalamic lemniscal and nonlemniscal auditory nuclei are different from each other in response properties and neural connectivities. The cortical auditory areas receiving the projections from these thalamic nuclei interact with each other through corticocortical projections and project down to the subcortical auditory nuclei. This corticofugal (descending) system forms multiple feedback loops with the ascending system. The corticocortical and corticofugal projections modulate auditory signal processing and play an essential role in the plasticity of the auditory system. Focal electric stimulation - comparable to repetitive tonal stimulation - of the lemniscal system evokes three major types of changes in the physiological properties, such as the tuning to specific values of acoustic parameters of cortical and subcortical auditory neurons through different combinations of facilitation and inhibition. For such changes, a neuromodulator, acetylcholine, plays an essential role. Electric stimulation of the nonlemniscal system evokes changes in the lemniscal system that is different from those evoked by the lemniscal stimulation. Auditory signals ascending from the lemniscal and nonlemniscal thalamic nuclei to the cortical auditory areas appear to be selected or adjusted by a "differential" gating mechanism. Conditioning for associative learning and pseudo-conditioning for nonassociative learning respectively elicit tone-specific and nonspecific plastic changes. The lemniscal, corticofugal and cholinergic systems are involved in eliciting the former, but not the latter. The current article reviews the recent progress in the research of corticocortical and corticofugal modulations of the auditory system and its plasticity elicited by conditioning and pseudo-conditioning.
1. Temporal sequence of visuo-auditory interaction in multiple areas of the guinea pig visual cortex.
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Masataka Nishimura
Full Text Available Recent studies in humans and monkeys have reported that acoustic stimulation influences visual responses in the primary visual cortex (V1. Such influences can be generated in V1, either by direct auditory projections or by feedback projections from extrastriate cortices. To test these hypotheses, cortical activities were recorded using optical imaging at a high spatiotemporal resolution from multiple areas of the guinea pig visual cortex, to visual and/or acoustic stimulations. Visuo-auditory interactions were evaluated according to differences between responses evoked by combined auditory and visual stimulation, and the sum of responses evoked by separate visual and auditory stimulations. Simultaneous presentation of visual and acoustic stimulations resulted in significant interactions in V1, which occurred earlier than in other visual areas. When acoustic stimulation preceded visual stimulation, significant visuo-auditory interactions were detected only in V1. These results suggest that V1 is a cortical origin of visuo-auditory interaction.
2. Spatial selective auditory attention in the presence of reverberant energy: individual differences in normal-hearing listeners.
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Ruggles, Dorea; Shinn-Cunningham, Barbara
2011-06-01
Listeners can selectively attend to a desired target by directing attention to known target source features, such as location or pitch. Reverberation, however, reduces the reliability of the cues that allow a target source to be segregated and selected from a sound mixture. Given this, it is likely that reverberant energy interferes with selective auditory attention. Anecdotal reports suggest that the ability to focus spatial auditory attention degrades even with early aging, yet there is little evidence that middle-aged listeners have behavioral deficits on tasks requiring selective auditory attention. The current study was designed to look for individual differences in selective attention ability and to see if any such differences correlate with age. Normal-hearing adults, ranging in age from 18 to 55 years, were asked to report a stream of digits located directly ahead in a simulated rectangular room. Simultaneous, competing masker digit streams were simulated at locations 15° left and right of center. The level of reverberation was varied to alter task difficulty by interfering with localization cues (increasing localization blur). Overall, performance was best in the anechoic condition and worst in the high-reverberation condition. Listeners nearly always reported a digit from one of the three competing streams, showing that reverberation did not render the digits unintelligible. Importantly, inter-subject differences were extremely large. These differences, however, were not significantly correlated with age, memory span, or hearing status. These results show that listeners with audiometrically normal pure tone thresholds differ in their ability to selectively attend to a desired source, a task important in everyday communication. Further work is necessary to determine if these differences arise from differences in peripheral auditory function or in more central function.
3. Different mechanisms are responsible for dishabituation of electrophysiological auditory responses to a change in acoustic identity than to a change in stimulus location.
Science.gov (United States)
Smulders, Tom V; Jarvis, Erich D
2013-11-01
Repeated exposure to an auditory stimulus leads to habituation of the electrophysiological and immediate-early-gene (IEG) expression response in the auditory system. A novel auditory stimulus reinstates this response in a form of dishabituation. This has been interpreted as the start of new memory formation for this novel stimulus. Changes in the location of an otherwise identical auditory stimulus can also dishabituate the IEG expression response. This has been interpreted as an integration of stimulus identity and stimulus location into a single auditory object, encoded in the firing patterns of the auditory system. In this study, we further tested this hypothesis. Using chronic multi-electrode arrays to record multi-unit activity from the auditory system of awake and behaving zebra finches, we found that habituation occurs to repeated exposure to the same song and dishabituation with a novel song, similar to that described in head-fixed, restrained animals. A large proportion of recording sites also showed dishabituation when the same auditory stimulus was moved to a novel location. However, when the song was randomly moved among 8 interleaved locations, habituation occurred independently of the continuous changes in location. In contrast, when 8 different auditory stimuli were interleaved all from the same location, a separate habituation occurred to each stimulus. This result suggests that neuronal memories of the acoustic identity and spatial location are different, and that allocentric location of a stimulus is not encoded as part of the memory for an auditory object, while its acoustic properties are. We speculate that, instead, the dishabituation that occurs with a change from a stable location of a sound is due to the unexpectedness of the location change, and might be due to different underlying mechanisms than the dishabituation and separate habituations to different acoustic stimuli.
4. The effects of different styles of musical auditory stimulation on cardiac autonomic regulation in healthy women
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2013-01-01
Full Text Available The literature investigated the effects of chronic baroque music auditory stimulation on the cardiovascular system. However, it lacks in the literature the acute effects of different styles of music on cardiac autonomic regulation. To evaluate the acute effects of baroque and heavy metal music on heart rate variability (HRV in women. The study was performed in 21 healthy women between 18 and 30 years old. We excluded persons with previous experience with music instrument and those who had affinity with the song styles. All procedures were performed in the same sound-proof room. We analyzed HRV in the time (standard deviation of normal-to-normal respiratory rate (RR intervals, root-mean square of differences between adjacent normal RR intervals in a time interval, and the percentage of adjacent RR intervals with a difference of duration greater than 50 ms and frequency (low frequency [LF], high frequency [HF], and LF/HF ratio domains. HRV was recorded at rest for 10 min. Subsequently they were exposed to baroque or heavy metal music for 5 min through an earphone. After the first music exposure they remained at rest for more 5 min and them they were exposed again to baroque or heavy metal music. The sequence of songs was randomized for each individual. The power analysis provided a minimal number of 18 subjects. Shapiro-Wilk to verify normality of data and analysis of variance for repeated measures followed by the Bonferroni test for parametric variables and Friedman′s followed by the Dunn′s post-test for non-parametric distributions. During the analysis of the time-domain indices were not changed. In the frequency-domain analysis, the LF in absolute units was reduced during the heavy metal music stimulation compared to control. Acute exposure to heavy metal music affected the sympathetic activity in healthy women.
5. The effects of different styles of musical auditory stimulation on cardiac autonomic regulation in healthy women.
Science.gov (United States)
Roque, Adriano L; Valenti, Vitor E; Guida, Heraldo L; Campos, Mônica F; Knap, André; Vanderlei, Luiz Carlos M; Ferreira, Celso; de Abreu, Luiz Carlos
2013-01-01
The literature investigated the effects of chronic baroque music auditory stimulation on the cardiovascular system. However, it lacks in the literature the acute effects of different styles of music on cardiac autonomic regulation. To evaluate the acute effects of baroque and heavy metal music on heart rate variability (HRV) in women. The study was performed in 21 healthy women between 18 and 30 years old. We excluded persons with previous experience with music instrument and those who had affinity with the song styles. All procedures were performed in the same sound-proof room. We analyzed HRV in the time (standard deviation of normal-to-normal respiratory rate (RR) intervals, root-mean square of differences between adjacent normal RR intervals in a time interval, and the percentage of adjacent RR intervals with a difference of duration greater than 50 ms) and frequency (low frequency [LF], high frequency [HF], and LF/HF ratio) domains. HRV was recorded at rest for 10 min. Subsequently they were exposed to baroque or heavy metal music for 5 min through an earphone. After the first music exposure they remained at rest for more 5 min and them they were exposed again to baroque or heavy metal music. The sequence of songs was randomized for each individual. The power analysis provided a minimal number of 18 subjects. Shapiro-Wilk to verify normality of data and analysis of variance for repeated measures followed by the Bonferroni test for parametric variables and Friedman's followed by the Dunn's post-test for non-parametric distributions. During the analysis of the time-domain indices were not changed. In the frequency-domain analysis, the LF in absolute units was reduced during the heavy metal music stimulation compared to control. Acute exposure to heavy metal music affected the sympathetic activity in healthy women.
6. Can feedback analysis be used to uncover the physical origin of climate sensitivity and efficacy differences?
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Rieger, Vanessa S.; Dietmüller, Simone; Ponater, Michael
2016-12-01
Different strengths and types of radiative forcings cause variations in the climate sensitivities and efficacies. To relate these changes to their physical origin, this study tests whether a feedback analysis is a suitable approach. For this end, we apply the partial radiative perturbation method. Combining the forward and backward calculation turns out to be indispensable to ensure the additivity of feedbacks and to yield a closed forcing-feedback-balance at top of the atmosphere. For a set of CO2-forced simulations, the climate sensitivity changes with increasing forcing. The albedo, cloud and combined water vapour and lapse rate feedback are found to be responsible for the variations in the climate sensitivity. An O3-forced simulation (induced by enhanced NOx and CO surface emissions) causes a smaller efficacy than a CO2-forced simulation with a similar magnitude of forcing. We find that the Planck, albedo and most likely the cloud feedback are responsible for this effect. Reducing the radiative forcing impedes the statistical separability of feedbacks. We additionally discuss formal inconsistencies between the common ways of comparing climate sensitivities and feedbacks. Moreover, methodical recommendations for future work are given.
7. Schizophrenia and borderline personality disorder: similarities and differences in the experience of auditory hallucinations, paranoia, and childhood trauma.
Science.gov (United States)
Kingdon, David G; Ashcroft, Katie; Bhandari, Bharathi; Gleeson, Stefan; Warikoo, Nishchint; Symons, Matthew; Taylor, Lisa; Lucas, Eleanor; Mahendra, Ravi; Ghosh, Soumya; Mason, Anthony; Badrakalimuthu, Raja; Hepworth, Claire; Read, John; Mehta, Raj
2010-06-01
This study investigated similarities and differences in the experience of auditory hallucinations, paranoia, and childhood trauma in schizophrenia and borderline personality disorder (BPD). Patients with clinical diagnoses of schizophrenia or BPD were interviewed using the Structured Clinical Interviews for DSM-IV. Axes 1 and 2 and auditory hallucinations, paranoia, and childhood trauma were assessed. A total of 111 patients participated; 59 met criteria for schizophrenia, 33 for BPD, and 19 for both. The groups were similar in their experiences of voices, including the perceived location of them, but they differed in frequency of paranoid delusions. Those with a diagnosis of BPD, including those with schizophrenia comorbidity, reported more childhood trauma, especially emotional abuse. BPD and schizophrenia frequently coexist, and this comorbidity has implications for diagnostic classification and treatment. Levels of reported childhood trauma are especially high in those with a BPD diagnosis, whether they have schizophrenia or not, and this requires assessment and appropriate management.
8. Different Verbal Learning Strategies in Autism Spectrum Disorder: Evidence from the Rey Auditory Verbal Learning Test
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Bowler, Dermot M.; Limoges, Elyse; Mottron, Laurent
2009-01-01
The Rey Auditory Verbal Learning Test, which requires the free recall of the same list of 15 unrelated words over 5 trials, was administered to 21 high-functioning adolescents and adults with autism spectrum disorder (ASD) and 21 matched typical individuals. The groups showed similar overall levels of free recall, rates of learning over trials and…
9. Influence of different envelope maskers on signal recognition and neuronal representation in the auditory system of a grasshopper.
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Daniela Neuhofer
Full Text Available BACKGROUND: Animals that communicate by sound face the problem that the signals arriving at the receiver often are degraded and masked by noise. Frequency filters in the receiver's auditory system may improve the signal-to-noise ratio (SNR by excluding parts of the spectrum which are not occupied by the species-specific signals. This solution, however, is hardly amenable to species that produce broad band signals or have ears with broad frequency tuning. In mammals auditory filters exist that work in the temporal domain of amplitude modulations (AM. Do insects also use this type of filtering? PRINCIPAL FINDINGS: Combining behavioural and neurophysiological experiments we investigated whether AM filters may improve the recognition of masked communication signals in grasshoppers. The AM pattern of the sound, its envelope, is crucial for signal recognition in these animals. We degraded the species-specific song by adding random fluctuations to its envelope. Six noise bands were used that differed in their overlap with the spectral content of the song envelope. If AM filters contribute to reduced masking, signal recognition should depend on the degree of overlap between the song envelope spectrum and the noise spectra. Contrary to this prediction, the resistance against signal degradation was the same for five of six masker bands. Most remarkably, the band with the strongest frequency overlap to the natural song envelope (0-100 Hz impaired acceptance of degraded signals the least. To assess the noise filter capacities of single auditory neurons, the changes of spike trains as a function of the masking level were assessed. Increasing levels of signal degradation in different frequency bands led to similar changes in the spike trains in most neurones. CONCLUSIONS: There is no indication that auditory neurones of grasshoppers are specialized to improve the SNR with respect to the pattern of amplitude modulations.
10. Partial synchronization of different chaotic oscillators using robust PID feedback
Energy Technology Data Exchange (ETDEWEB)
Aguilar-Lopez, Ricardo [Departamento de Energia, Universidad Autonoma Metropolitana - Azcapotzalco, San Pablo 180, Reynosa-Tamaulipas, Azcapotzalco, 02200 Mexico, D.F. (Mexico)]. E-mail: [email protected]; Martinez-Guerra, Rafael [Departamento de Control Automatico, CINVESTAV IPN, Apartado Postal 14-740, Mexico, D.F. C.P. 07360 (Mexico)]. E-mail: [email protected]
2007-07-15
This work deals with the partial synchronization problem of two different chaotic oscillators considering model uncertainties in the slave system via control approach. The slave system is forced to follow the master signal via a linearizing controller based on model uncertainty reconstructor which leads to proportional-integral-derivative (PID) control structure. This reconstructor is related with a proportional-derivative (PD) reduced-order observer, it would be considered as a sub-slave system for the original slave of the synchronization procedure. The asymptotic performance of the synchronization methodology is proven via the dynamic of the synchronization error. Numerical experiment illustrates the closed-loop behavior of the proposed methodology.
11. Using Relevance Feedback to Distinguish the Changes in EEG During Different Absence Seizure Phases.
Science.gov (United States)
Li, Jing; Liu, Xianzeng; Ouyang, Gaoxiang
2016-07-01
We carried out a series of statistical experiments to explore the utility of using relevance feedback on electroencephalogram (EEG) data to distinguish between different activity states in human absence epilepsy. EEG recordings from 10 patients with absence epilepsy are sampled, filtered, selected, and dissected from seizure-free, preseizure, and seizure phases. A total of 112 two-second 19-channel EEG epochs from 10 patients were selected from each phase. For each epoch, multiscale permutation entropy of the EEG data was calculated. The feature dimensionality was reduced by linear discriminant analysis to obtain a more discriminative and compact representation. Finally, a relevance feedback technique, that is, direct biased discriminant analysis, was applied to 68 randomly selected queries over nine iterations. This study is a first attempt to apply the statistical analysis of relevance feedback to the distinction of different EEG activity states in absence epilepsy. The average precision in the top 10 returned results was 97.5%, and the standard deviation suggested that embedding relevance feedback can effectively distinguish different seizure phases in absence epilepsy. The experimental results indicate that relevance feedback may be an effective tool for the prediction of different activity states in human absence epilepsy. The simultaneous analysis of multichannel EEG signals provides a powerful tool for the exploration of abnormal electrical brain activity in patients with epilepsy.
12. Knowledge about Sounds – Context-Specific Meaning Differently Activates Cortical Hemispheres, Auditory Cortical Fields and Layers in House Mice
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Diana B. Geissler
2016-03-01
Full Text Available Activation of the auditory cortex (AC by a given sound pattern is plastic, depending, in largely unknown ways, on the physiological state and the behavioral context of the receiving animal and on the receiver's experience with the sounds. Such plasticity can be inferred when house mouse mothers respond maternally to pup ultrasounds right after parturition and naïve females have to learn to respond. Here we use c-FOS immunocytochemistry to quantify highly activated neurons in the AC fields and layers of seven groups of mothers and naïve females who have different knowledge about and are differently motivated to respond to acoustic models of pup ultrasounds of different behavioral significance. Profiles of FOS-positive cells in the AC primary fields (AI, AAF, the ultrasonic field (UF, the secondary field (AII, and the dorsoposterior field (DP suggest that activation reflects in AI, AAF, and UF the integration of sound properties with animal state-dependent factors, in the higher-order field AII the news value of a given sound in the behavioral context, and in the higher-order field DP the level of maternal motivation and, by left-hemisphere activation advantage, the recognition of the meaning of sounds in the given context. Anesthesia reduced activation in all fields, especially in cortical layers 2/3. Thus, plasticity in the AC is field-specific preparing different output of AC fields in the process of perception, recognition and responding to communication sounds. Further, the activation profiles of the auditory cortical fields suggest the differentiation between brains hormonally primed to know (mothers and brains which acquired knowledge via implicit learning (naïve females. In this way, auditory cortical activation discriminates between instinctive (mothers and learned (naïve females cognition.
13. A Study of the Central Auditory Function in Stutters by Masking Level Difference and Synthetic Sentence Identification Tests
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Afsaneh Rajab
2007-06-01
Full Text Available Background and Aim: There are evidences that indicate a relationship between auditory processing disor¬ders and stuttering,¬ and any disorder in the central auditory function can be at least one of the underly¬ing causes of stuttering. Even though, using the most state of the art radiographic technologies, i.e. MRI, no definitive answer has been given in relative to this question. In this research, using Mask-ing Level Difference (MLD and Synthetic Sentence Identification (SSI tests, the central auditory func¬tion of stutters and normal group was evaluated.Materials and Methods: In this study was analytic cross-sectional, fifteen male patients with stutter-ing and 15 male normal cases with the age range from 16 to 40 years (average age 26.78 year were evalu¬ated. SSI-ICM, SSI-CCM and MLD tests were performed. The results were compared in both groups.Results: Although stutterers mean MLD was less than that of normal group, the different was not signifi¬cant between stutters and normal group in SSI test in right ear at negative MCRs. There was a signifi¬cant difference in ICM state, but in CCM state, there was no significant difference between the aver¬age score of two groups in various MCRs.Conclusion: The findings of this research is compatible with those of similar researches about the SSI test and the pattern of results, probably indicates a partial dysfunction of brainstem in some of the stutters.
14. Knowledge About Sounds-Context-Specific Meaning Differently Activates Cortical Hemispheres, Auditory Cortical Fields, and Layers in House Mice.
Science.gov (United States)
Geissler, Diana B; Schmidt, H Sabine; Ehret, Günter
2016-01-01
Activation of the auditory cortex (AC) by a given sound pattern is plastic, depending, in largely unknown ways, on the physiological state and the behavioral context of the receiving animal and on the receiver's experience with the sounds. Such plasticity can be inferred when house mouse mothers respond maternally to pup ultrasounds right after parturition and naïve females have to learn to respond. Here we use c-FOS immunocytochemistry to quantify highly activated neurons in the AC fields and layers of seven groups of mothers and naïve females who have different knowledge about and are differently motivated to respond to acoustic models of pup ultrasounds of different behavioral significance. Profiles of FOS-positive cells in the AC primary fields (AI, AAF), the ultrasonic field (UF), the secondary field (AII), and the dorsoposterior field (DP) suggest that activation reflects in AI, AAF, and UF the integration of sound properties with animal state-dependent factors, in the higher-order field AII the news value of a given sound in the behavioral context, and in the higher-order field DP the level of maternal motivation and, by left-hemisphere activation advantage, the recognition of the meaning of sounds in the given context. Anesthesia reduced activation in all fields, especially in cortical layers 2/3. Thus, plasticity in the AC is field-specific preparing different output of AC fields in the process of perception, recognition and responding to communication sounds. Further, the activation profiles of the auditory cortical fields suggest the differentiation between brains hormonally primed to know (mothers) and brains which acquired knowledge via implicit learning (naïve females). In this way, auditory cortical activation discriminates between instinctive (mothers) and learned (naïve females) cognition.
15. Hand-opening feedback for myoelectric forearm prostheses: performance in virtual grasping tasks influenced by different levels of distraction.
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Witteveen, Heidi J B; de Rond, Leonie; Rietman, Johan S; Veltink, Peter H
2012-01-01
Sensory feedback and the required attentional demands are important aspects in prosthesis acceptance. In this study, hand-opening feedback is provided and the performance in a virtual grasping task is investigated. Simultaneously, a secondary task was performed to investigate the attentional demands. Ten nondisabled subjects performed the tasks with and without feedback about the hand opening through an array of eight vibrotactile stimulators on the forearm. Activation of one stimulator corresponded to one hand-opening position. For the dual-task experiments, subjects simultaneously performed a secondary auditory counting task. The addition of vibrotactile feedback increased the performance (expressed in percentages of correct hand positions, mean absolute errors in position, and percentages of deviations up to one hand-opening position), but the duration of the tasks was also increased. Three levels of distraction (no distraction, counting task, count and subtract task) were applied, which did not influence the performance in the grasping tasks except for the highest level of distraction. We concluded that the proposed method to provide hand-opening feedback through an array of eight vibrotactile stimulators is successful because the performance in a grasping task increases but it is not significantly attention demanding.
16. The Relative Effectiveness of Different Types of Direct Written Corrective Feedback
Science.gov (United States)
Bitchener, John; Knoch, Ute
2009-01-01
The effectiveness of different types of written corrective feedback has been investigated over the last twenty years but it is still not possible to make firm conclusions about which options are the most beneficial to ESL learners. This article first provides an overview of the currently available research findings and then presents the results of…
17. Effects of Signal Spectrum Bandwidth on Different PMD Compensation Feedback Methods
Institute of Scientific and Technical Information of China (English)
Na Young Kim; Duckey Lee; Sangin Kim; Namkyoo Park
2003-01-01
We compared efficiencies of different PMD compensation feedback methods against transmission signal bandwidth,including NRZ, RZ, CRZ format under various duty cycles. We found that the critical factor determining the efficiency of PMD compensation is not the modulation format, but the spectral bandwidth of the transmission signal.
18. Effects of Signal Spectrum Bandwidth on Different PMD Compensation Feedback Methods
Institute of Scientific and Technical Information of China (English)
Na; Young; Kim; Duckey; Lee; Sangin; Kim; Namkyoo; Park
2003-01-01
We compared efficiencies of different PMD compensation feedback methods against transmission signal bandwidth, including NRZ, RZ, CRZ format under various duty cycles. We found that the critical factor determining the efficiency of PMD compensation is not the modulation format, but the spectral bandwidth of the transmission signal.
19. The effects of different quantum feedback operator types on the parameter precision of detection efficiency in optimal quantum estimation
Science.gov (United States)
Ma, Shao-Qiang; Zhu, Han-Jie; Zhang, Guo-Feng
2017-04-01
The effects of different quantum feedback types on the estimation precision of the detection efficiency are studied. It is found that the precision can be more effective enhanced by a certain feedback type through comparing these feedbacks and the precision has a positive relation with detection efficiency for the optimal feedback when the system reach the state of dynamic balance. In addition, the bigger the proportion of |1> is the higher the precision is and we will not obtain any information about the parameter to be estimated if |0> is chosen as initial state for the feedback type λσz.
20. Exploring cultural differences in feedback processes and perceived instructiveness during clerkships : Replicating a Dutch study in Indonesia
NARCIS (Netherlands)
Suhoyo, Yoyo; van Hell, Elisabeth A.; Prihatiningsih, Titi S.; Kuks, Jan B. M.; Cohen-Schotanus, Janke
2014-01-01
Context: Cultural differences between countries may entail differences in feedback processes. Aims: By replicating a Dutch study in Indonesia, we analysed whether differences in processes influenced the perceived instructiveness of feedback. Methods: Over a two-week period, Indonesian students (n =
1. Auditory-motor mapping for pitch control in singers and nonsingers.
Science.gov (United States)
Jones, Jeffery A; Keough, Dwayne
2008-09-01
Little is known about the basic processes underlying the behavior of singing. This experiment was designed to examine differences in the representation of the mapping between fundamental frequency (F0) feedback and the vocal production system in singers and nonsingers. Auditory feedback regarding F0 was shifted down in frequency while participants sang the consonant-vowel /ta/. During the initial frequency-altered trials, singers compensated to a lesser degree than nonsingers, but this difference was reduced with continued exposure to frequency-altered feedback. After brief exposure to frequency altered auditory feedback, both singers and nonsingers suddenly heard their F0 unaltered. When participants received this unaltered feedback, only singers' F0 values were found to be significantly higher than their F0 values produced during baseline and control trials. These aftereffects in singers were replicated when participants sang a different note than the note they produced while hearing altered feedback. Together, these results suggest that singers rely more on internal models than nonsingers to regulate vocal productions rather than real time auditory feedback.
2. Visual phonology: the effects of orthographic consistency on different auditory word recognition tasks.
Science.gov (United States)
Ziegler, Johannes C; Ferrand, Ludovic; Montant, Marie
2004-07-01
In this study, we investigated orthographic influences on spoken word recognition. The degree of spelling inconsistency was manipulated while rime phonology was held constant. Inconsistent words with subdominant spellings were processed more slowly than inconsistent words with dominant spellings. This graded consistency effect was obtained in three experiments. However, the effect was strongest in lexical decision, intermediate in rime detection, and weakest in auditory naming. We conclude that (1) orthographic consistency effects are not artifacts of phonological, phonetic, or phonotactic properties of the stimulus material; (2) orthographic effects can be found even when the error rate is extremely low, which rules out the possibility that they result from strategies used to reduce task difficulty; and (3) orthographic effects are not restricted to lexical decision. However, they are stronger in lexical decision than in other tasks. Overall, the study shows that learning about orthography alters the way we process spoken language.
3. Auditory event-related responses to diphthongs in different attention conditions
DEFF Research Database (Denmark)
Morris, David Jackson; Steinmetzger, Kurt; Tøndering, John
2016-01-01
The modulation of auditory event-related potentials (ERP) by attention generally results in larger amplitudes when stimuli are attended. We measured the P1-N1-P2 acoustic change complex elicited with synthetic overt (second formant, F2 = 1000 Hz) and subtle (F2 = 100 Hz) diphthongs, while subjects....... Multivariate analysis of ERP components from the rising F2 changes showed main effects of attention on P2 amplitude and latency, and N1-P2 amplitude. P2 amplitude decreased by 40% between the attend and ignore conditions, and by 60% between the attend and divert conditions. The effect of diphthong magnitude...... was significant for components from a broader temporal window which included P1 latency and N1 amplitude. N1 latency did not vary between attention conditions, a finding that may be related to stimulation with a continuous vowel. These data show that a discernible P1-N1-P2 response can be observed to subtle vowel...
4. Bayesian Modeling of the Dynamics of Phase Modulations and their Application to Auditory Evoked Responses at Different Loudness Scales
Directory of Open Access Journals (Sweden)
Zeinab eMortezapouraghdam
2016-01-01
Full Text Available We study the effect of long-term habituation signatures of auditory selective attention reflected in the instantaneous phase information of the auditory event-related potentials (ERPs at four distinct stimuli levels of 60dB SPL, 70dB SPL, 80dB SPL and 90dB SPL. The analysis is based on the single-trial level. The effect of habituation can be observed in terms of the changes (jitter in the instantaneous phase information of ERPs. In particular, the absence of habituation is correlated with a consistently high phase synchronization over ERP trials.We estimate the changes in phase concentration over trials using a Bayesian approach, in which the phase is modeled as being drawn from a von Mises distribution with a concentration parameter which varies smoothly over trials. The smoothness assumption reflects the fact that habituation is a gradual process.We differentiate between different stimuli based on the relative changes and absolute values of the estimated concentration parameter using the proposed Bayesian model.
5. Learning English vowels with different first-language vowel systems II: Auditory training for native Spanish and German speakers.
Science.gov (United States)
Iverson, Paul; Evans, Bronwen G
2009-08-01
This study investigated whether individuals with small and large native-language (L1) vowel inventories learn second-language (L2) vowel systems differently, in order to better understand how L1 categories interfere with new vowel learning. Listener groups whose L1 was Spanish (5 vowels) or German (18 vowels) were given five sessions of high-variability auditory training for English vowels, after having been matched to assess their pre-test English vowel identification accuracy. Listeners were tested before and after training in terms of their identification accuracy for English vowels, the assimilation of these vowels into their L1 vowel categories, and their best exemplars for English (i.e., perceptual vowel space map). The results demonstrated that Germans improved more than Spanish speakers, despite the Germans' more crowded L1 vowel space. A subsequent experiment demonstrated that Spanish listeners were able to improve as much as the German group after an additional ten sessions of training, and that both groups were able to retain this learning. The findings suggest that a larger vowel category inventory may facilitate new learning, and support a hypothesis that auditory training improves identification by making the application of existing categories to L2 phonemes more automatic and efficient.
6. Contributions of sensory coding and attentional control to individual differences in performance in spatial auditory selective attention tasks
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Lengshi Dai
2016-10-01
Full Text Available Listeners with normal hearing thresholds differ in their ability to steer attention to whatever sound source is important. This ability depends on top-down executive control, which modulates the sensory representation of sound in cortex. Yet, this sensory representation also depends on the coding fidelity of the peripheral auditory system. Both of these factors may thus contribute to the individual differences in performance. We designed a selective auditory attention paradigm in which we could simultaneously measure envelope following responses (EFRs, reflecting peripheral coding, onset event-related potentials from the scalp (ERPs, reflecting cortical responses to sound, and behavioral scores. We performed two experiments that varied stimulus conditions to alter the degree to which performance might be limited due to fine stimulus details vs. due to control of attentional focus. Consistent with past work, in both experiments we find that attention strongly modulates cortical ERPs. Importantly, in Experiment I, where coding fidelity limits the task, individual behavioral performance correlates with subcortical coding strength (derived by computing how the EFR is degraded for fully masked tones compared to partially masked tones; however, in this experiment, the effects of attention on cortical ERPs were unrelated to individual subject performance. In contrast, in Experiment II, where sensory cues for segregation are robust (and thus less of a limiting factor on task performance, inter-subject behavioral differences correlate with subcortical coding strength. In addition, after factoring out the influence of subcortical coding strength, behavioral differences are also correlated with the strength of attentional modulation of ERPs. These results support the hypothesis that behavioral abilities amongst listeners with normal hearing thresholds can arise due to both subcortical coding differences and differences in attentional control, depending on
7. Distinct patterns of corticogeniculate feedback to different layers of the lateral geniculate nucleus
Directory of Open Access Journals (Sweden)
Ichida JM
2014-09-01
Full Text Available Jennifer M Ichida,1 Julia A Mavity-Hudson,2 Vivien A Casagrande1–3 1Department of Psychology, 2Department of Cell and Developmental Biology, 3Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, TN, USA Abstract: In primates, feedforward visual pathways from retina to lateral geniculate nucleus (LGN are segregated to different layers. These layers also receive strong reciprocal feedback pathways from cortex. The degree to which feedforward streams in primates are segregated from feedback streams remains unclear. Here, we asked whether corticogeniculate cells that innervate the magnocellular (M, parvocellular (P, and koniocellular (K layers of the LGN in the prosimian primate bush baby (Otolemur garnettii can be distinguished based on either the laminar distribution or morphological characteristics of their axons and synaptic contacts in LGN, or on their cell body position, size, and dendritic distribution in cortex. Corticogeniculate axons and synapses were labeled anterogradely with biotinylated dextran injections in layer 6 of cortex. Corticogeniculate cell bodies were first labeled with fluorescent dextran injections limited to individual M, P, or K LGN layers and then filled with biotinylated Lucifer yellow. Results showed that feedback to the M or P LGN layers arises from cells with dendrites primarily confined to cortical layer 6 and axons restricted to either M or P LGN layers, but not both. Feedback to K LGN layers arises from cells: 1 whose dendrites distribute rather evenly across cortical layers 5 and 6; 2 whose dendrites always extend into layer 4; and 3 whose axons are never confined to K layers but always overlap with either P or M layers. Corticogeniculate axons also showed distributions that were retinotopically precise based on known receptive field sizes of layer 6 cells, and these axons mainly made synapses with glutamatergic projection neurons in the LGN in all layers. Taken together with prior
8. Cognitive Strategy Use as an Index of Developmental Differences in Neural Responses to Feedback
DEFF Research Database (Denmark)
Andersen, Lau M.; Visser, Ingmar; Crone, Eveline A.;
2014-01-01
Developmental differences in dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC) and superior parietal cortex (SPC) activation are associated with differences in how children, adolescents, and adults learn from performance feedback in rule-learning tasks (Crone, Zanolie...... strategy groups except for the best performing one. Strategy use was a mediator and largely explained the relation between age and variance in activation patterns in the DLPFC and the SPC, but not in the ACC. These findings are interpreted vis-à-vis age versus performance predictors of brain development...
9. Implicit learning of predictable sound sequences modulates human brain responses at different levels of the auditory hierarchy
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Françoise eLecaignard
2015-09-01
Full Text Available Deviant stimuli, violating regularities in a sensory environment, elicit the Mismatch Negativity (MMN, largely described in the Event-Related Potential literature. While it is widely accepted that the MMN reflects more than basic change detection, a comprehensive description of mental processes modulating this response is still lacking. Within the framework of predictive coding, deviance processing is part of an inference process where prediction errors (the mismatch between incoming sensations and predictions established through experience are minimized. In this view, the MMN is a measure of prediction error, which yields specific expectations regarding its modulations by various experimental factors. In particular, it predicts that the MMN should decrease as the occurrence of a deviance becomes more predictable. We conducted a passive oddball EEG study and manipulated the predictability of sound sequences by means of different temporal structures. Importantly, our design allows comparing mismatch responses elicited by predictable and unpredictable violations of a simple repetition rule and therefore departs from previous studies that investigate violations of different time-scale regularities. We observed a decrease of the MMN with predictability and interestingly, a similar effect at earlier latencies, within 70 ms after deviance onset. Following these pre-attentive responses, a reduced P3a was measured in the case of predictable deviants. We conclude that early and late deviance responses reflect prediction errors, triggering belief updating within the auditory hierarchy. Beside, in this passive study, such perceptual inference appears to be modulated by higher-level implicit learning of sequence statistical structures. Our findings argue for a hierarchical model of auditory processing where predictive coding enables implicit extraction of environmental regularities.
10. Sex-related differences in auditory processing in adolescents with fetal alcohol spectrum disorder: A magnetoencephalographic study
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Claudia D. Tesche
2015-01-01
Full Text Available Children exposed to substantial amounts of alcohol in utero display a broad range of morphological and behavioral outcomes, which are collectively referred to as fetal alcohol spectrum disorders (FASDs. Common to all children on the spectrum are cognitive and behavioral problems that reflect central nervous system dysfunction. Little is known, however, about the potential effects of variables such as sex on alcohol-induced brain damage. The goal of the current research was to utilize magnetoencephalography (MEG to examine the effect of sex on brain dynamics in adolescents and young adults with FASD during the performance of an auditory oddball task. The stimuli were short trains of 1 kHz “standard” tone bursts (80% randomly interleaved with 1.5 kHz “target” tone bursts (10% and “novel” digital sounds (10%. Participants made motor responses to the target tones. Results are reported for 44 individuals (18 males and 26 females ages 12 through 22 years. Nine males and 13 females had a diagnosis of FASD and the remainder were typically-developing age- and sex-matched controls. The main finding was widespread sex-specific differential activation of the frontal, medial and temporal cortex in adolescents with FASD compared to typically developing controls. Significant differences in evoked-response and time–frequency measures of brain dynamics were observed for all stimulus types in the auditory cortex, inferior frontal sulcus and hippocampus. These results underscore the importance of considering the influence of sex when analyzing neurophysiological data in children with FASD.
11. THE EXISTENCE OF POSITIVE PERIODIC SOLUTIONS IN A LOGISTIC DIFFERENCE MODEL WITH A FEEDBACK CONTROL
Institute of Scientific and Technical Information of China (English)
刘智钢; 陈安平
2004-01-01
Consider the following nonautonomous delayed periodic logistic difference model with feedback control term N(k+1)=N(k)exp[r(k)-a1(k)N(k)-a2(k)N(k-τ(k))-c(k)u(k)],Δu(k)=-a(k)u(k)+b(k)N(k-τ(k)), which describes the evolution of a single species. The existence of a positive periodic solution is established by using the method of Mawhin's coincidence degree. This work has important significance in both theory and applications.
12. Feedback Control System for Antenna Phase Difference in the LHCD Experiments
Institute of Scientific and Technical Information of China (English)
Jiang Min; Kuang Guangli; Shan Jiafang; Lin Jian'an; Kong Jun; HT-7 Team
2005-01-01
It is well accepted that lower hybrid current drive (LHCD) is the most efficient method for non-inductive current drive in fusion devices and the effect of the current drive is dependent on not only microwave power but also its grill phase shift. This paper presents a new kind of feedback control system for antenna phase difference in LHCD experiments. In this high-speed control system, a lot of new technologies and methods are incorporated. The results of the experiments show a very good agreement with the system design.
13. Auditory pathways: anatomy and physiology.
Science.gov (United States)
Pickles, James O
2015-01-01
This chapter outlines the anatomy and physiology of the auditory pathways. After a brief analysis of the external, middle ears, and cochlea, the responses of auditory nerve fibers are described. The central nervous system is analyzed in more detail. A scheme is provided to help understand the complex and multiple auditory pathways running through the brainstem. The multiple pathways are based on the need to preserve accurate timing while extracting complex spectral patterns in the auditory input. The auditory nerve fibers branch to give two pathways, a ventral sound-localizing stream, and a dorsal mainly pattern recognition stream, which innervate the different divisions of the cochlear nucleus. The outputs of the two streams, with their two types of analysis, are progressively combined in the inferior colliculus and onwards, to produce the representation of what can be called the "auditory objects" in the external world. The progressive extraction of critical features in the auditory stimulus in the different levels of the central auditory system, from cochlear nucleus to auditory cortex, is described. In addition, the auditory centrifugal system, running from cortex in multiple stages to the organ of Corti of the cochlea, is described.
14. Animal models for auditory streaming.
Science.gov (United States)
Itatani, Naoya; Klump, Georg M
2017-02-19
Sounds in the natural environment need to be assigned to acoustic sources to evaluate complex auditory scenes. Separating sources will affect the analysis of auditory features of sounds. As the benefits of assigning sounds to specific sources accrue to all species communicating acoustically, the ability for auditory scene analysis is widespread among different animals. Animal studies allow for a deeper insight into the neuronal mechanisms underlying auditory scene analysis. Here, we will review the paradigms applied in the study of auditory scene analysis and streaming of sequential sounds in animal models. We will compare the psychophysical results from the animal studies to the evidence obtained in human psychophysics of auditory streaming, i.e. in a task commonly used for measuring the capability for auditory scene analysis. Furthermore, the neuronal correlates of auditory streaming will be reviewed in different animal models and the observations of the neurons' response measures will be related to perception. The across-species comparison will reveal whether similar demands in the analysis of acoustic scenes have resulted in similar perceptual and neuronal processing mechanisms in the wide range of species being capable of auditory scene analysis.This article is part of the themed issue 'Auditory and visual scene analysis'.
15. Auditory Cortex is Important in the Extinction of Two Different Tone-Based Conditioned Fear Memories in Rats.
Science.gov (United States)
Song, Eun Young; Boatman, Jeffrey A; Jung, Min Whan; Kim, Jeansok J
2010-01-01
Extensive fear extinction research is guided by the view that there are structures in the brain that develop inhibitory control over the expression of conditioned fear memories. While the medial prefrontal cortex has recently captured attention as the locus of plasticity essential for extinction of conditioned fear, the auditory cortex is another plausible cortical area involved in extinction learning since it is considered a sufficient conditioned stimulus (CS) pathway in tone fear conditioning. We examined the role of auditory cortex in extinction of auditory-based fear memories with a standard tone-on conditioning, wherein a tone CS predicted a footshock unconditioned stimulus (US), or a novel tone-off conditioning, in which the tone was continually present and the offset of the tone was the CS predicting the US. Rats with bilateral auditory cortex lesions were trained in either paradigm and subsequently trained in extinction to the CS. Auditory cortex lesions had no effect on acquisition but impaired extinction to both CSs. These findings indicate that the auditory cortex contributes to extinction of wide-ranging auditory fear memories, as evidenced by deficits in both tone-on CS and tone-off CS extinction training.
16. Corrective Feedback in Classrooms at Different Proficiency Levels: A Case Study of Chinese as a Foreign Language
Directory of Open Access Journals (Sweden)
Liu Li
2014-08-01
Full Text Available This paper presents a study investigating the relationship between corrective feedback, students’ language proficiency and classroom communication orientation in classrooms of Chinese as a Foreign Language (CFL at a US university. Inspired by Lyster and Mori (2006, this comparative analysis of teacher-student interaction investigates the immediate effects of prompt, recast, and explicit correction on learner uptake and repair across three different Chinese proficiency levels. By use of two measurement tools—Error Treatment Model and COLT coding scheme, the study attempts to seek the distribution pattern of feedbacks and the sequent uptakes, as well as the impact of learners’ proficiency levels on the pattern of feedback and uptakes in CFL classrooms. Results show that recasts still remain the most common feedback type across the classes in this study. The uptake of feedback is influenced both by classroom communication orientation and the students’ language proficiency.
17. Evaluating the effectiveness of an educational and feedback intervention aimed at improving consideration of sex differences in guideline development
NARCIS (Netherlands)
Keuken, D.G.; Haafkens, J.A.; Mohrs, J.; Klazinga, N.S.; Bindels, P.J.E.
2010-01-01
Objectives To investigate the effect of an educational and feedback intervention to enhance consideration of sex differences in clinical guideline development. Design Preintervention and postintervention questionnaires in intervention and control groups. Content analysis of intervention guidelines a
18. OPTIMAL EXISTENCE THEORY FOR SINGLE AND MULTIPLE POSITIVE PERIODIC SOLUTIONS TO FUNCTIONAL DIFFERENCE EQUATIONS WITH FEEDBACK CONTROL
Institute of Scientific and Technical Information of China (English)
2006-01-01
Using a fixed point theorem in a cone, we obtain some optimal existence results for single and multiple positive periodic solutions to a functional difference system with feedback control. Moreover, we apply our results to a population model.
19. Targeting Treatment-Resistant Auditory Verbal Hallucinations in Schizophrenia with fMRI-Based Neurofeedback - Exploring Different Cases of Schizophrenia.
Science.gov (United States)
Dyck, Miriam S; Mathiak, Krystyna A; Bergert, Susanne; Sarkheil, Pegah; Koush, Yury; Alawi, Eliza M; Zvyagintsev, Mikhail; Gaebler, Arnim J; Shergill, Sukhi S; Mathiak, Klaus
2016-01-01
Auditory verbal hallucinations (AVHs) are a hallmark of schizophrenia and can significantly impair patients' emotional, social, and occupational functioning. Despite progress in psychopharmacology, over 25% of schizophrenia patients suffer from treatment-resistant hallucinations. In the search for alternative treatment methods, neurofeedback (NF) emerges as a promising therapy tool. NF based on real-time functional magnetic resonance imaging (rt-fMRI) allows voluntarily change of the activity in a selected brain region - even in patients with schizophrenia. This study explored effects of NF on ongoing AVHs. The selected participants were trained in the self-regulation of activity in the anterior cingulate cortex (ACC), a key monitoring region involved in generation and intensity modulation of AVHs. Using rt-fMRI, three right-handed patients, suffering from schizophrenia and ongoing, treatment-resistant AVHs, learned control over ACC activity on three separate days. The effect of NF training on hallucinations' severity was assessed with the Auditory Vocal Hallucination Rating Scale (AVHRS) and on the affective state - with the Positive and Negative Affect Schedule (PANAS). All patients yielded significant upregulation of the ACC and reported subjective improvement in some aspects of AVHs (AVHRS) such as disturbance and suffering from the voices. In general, mood (PANAS) improved during NF training, though two patients reported worse mood after NF on the third day. ACC and reward system activity during NF learning and specific effects on mood and symptoms varied across the participants. None of them profited from the last training set in the prolonged three-session training. Moreover, individual differences emerged in brain networks activated with NF and in symptom changes, which were related to the patients' symptomatology and disease history. NF based on rt-fMRI seems a promising tool in therapy of AVHs. The patients, who suffered from continuous hallucinations for
20. Training-induced plasticity of auditory localization in adult mammals.
Directory of Open Access Journals (Sweden)
Oliver Kacelnik
2006-04-01
Full Text Available Accurate auditory localization relies on neural computations based on spatial cues present in the sound waves at each ear. The values of these cues depend on the size, shape, and separation of the two ears and can therefore vary from one individual to another. As with other perceptual skills, the neural circuits involved in spatial hearing are shaped by experience during development and retain some capacity for plasticity in later life. However, the factors that enable and promote plasticity of auditory localization in the adult brain are unknown. Here we show that mature ferrets can rapidly relearn to localize sounds after having their spatial cues altered by reversibly occluding one ear, but only if they are trained to use these cues in a behaviorally relevant task, with greater and more rapid improvement occurring with more frequent training. We also found that auditory adaptation is possible in the absence of vision or error feedback. Finally, we show that this process involves a shift in sensitivity away from the abnormal auditory spatial cues to other cues that are less affected by the earplug. The mature auditory system is therefore capable of adapting to abnormal spatial information by reweighting different localization cues. These results suggest that training should facilitate acclimatization to hearing aids in the hearing impaired.
1. Auditory hallucinations.
Science.gov (United States)
Blom, Jan Dirk
2015-01-01
Auditory hallucinations constitute a phenomenologically rich group of endogenously mediated percepts which are associated with psychiatric, neurologic, otologic, and other medical conditions, but which are also experienced by 10-15% of all healthy individuals in the general population. The group of phenomena is probably best known for its verbal auditory subtype, but it also includes musical hallucinations, echo of reading, exploding-head syndrome, and many other types. The subgroup of verbal auditory hallucinations has been studied extensively with the aid of neuroimaging techniques, and from those studies emerges an outline of a functional as well as a structural network of widely distributed brain areas involved in their mediation. The present chapter provides an overview of the various types of auditory hallucination described in the literature, summarizes our current knowledge of the auditory networks involved in their mediation, and draws on ideas from the philosophy of science and network science to reconceptualize the auditory hallucinatory experience, and point out directions for future research into its neurobiologic substrates. In addition, it provides an overview of known associations with various clinical conditions and of the existing evidence for pharmacologic and non-pharmacologic treatments.
2. Sex-specific differences in agonistic behaviour, sound production and auditory sensitivity in the callichthyid armoured catfish Megalechis thoracata.
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Full Text Available BACKGROUND: Data on sex-specific differences in sound production, acoustic behaviour and hearing abilities in fishes are rare. Representatives of numerous catfish families are known to produce sounds in agonistic contexts (intraspecific aggression and interspecific disturbance situations using their pectoral fins. The present study investigates differences in agonistic behaviour, sound production and hearing abilities in males and females of a callichthyid catfish. METHODOLOGY/PRINCIPAL FINDINGS: Eight males and nine females of the armoured catfish Megalechis thoracata were investigated. Agonistic behaviour displayed during male-male and female-female dyadic contests and sounds emitted were recorded, sound characteristics analysed and hearing thresholds measured using the auditory evoked potential (AEP recording technique. Male pectoral spines were on average 1.7-fold longer than those of same-sized females. Visual and acoustic threat displays differed between sexes. Males produced low-frequency harmonic barks at longer distances and thumps at close distances, whereas females emitted broad-band pulsed crackles when close to each other. Female aggressive sounds were significantly shorter than those of males (167 ms versus 219 to 240 ms and of higher dominant frequency (562 Hz versus 132 to 403 Hz. Sound duration and sound level were positively correlated with body and pectoral spine length, but dominant frequency was inversely correlated only to spine length. Both sexes showed a similar U-shaped hearing curve with lowest thresholds between 0.2 and 1 kHz and a drop in sensitivity above 1 kHz. The main energies of sounds were located at the most sensitive frequencies. CONCLUSIONS/SIGNIFICANCE: Current data demonstrate that both male and female M. thoracata produce aggressive sounds, but the behavioural contexts and sound characteristics differ between sexes. Sexes do not differ in hearing, but it remains to be clarified if this is a general pattern
3. Modeling laser-induced periodic surface structures: Finite-difference time-domain feedback simulations
Energy Technology Data Exchange (ETDEWEB)
Skolski, J. Z. P., E-mail: [email protected]; Vincenc Obona, J. [Materials innovation institute M2i, Faculty of Engineering Technology, Chair of Applied Laser Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Römer, G. R. B. E.; Huis in ' t Veld, A. J. [Faculty of Engineering Technology, Chair of Applied Laser Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)
2014-03-14
A model predicting the formation of laser-induced periodic surface structures (LIPSSs) is presented. That is, the finite-difference time domain method is used to study the interaction of electromagnetic fields with rough surfaces. In this approach, the rough surface is modified by “ablation after each laser pulse,” according to the absorbed energy profile, in order to account for inter-pulse feedback mechanisms. LIPSSs with a periodicity significantly smaller than the laser wavelength are found to “grow” either parallel or orthogonal to the laser polarization. The change in orientation and periodicity follow from the model. LIPSSs with a periodicity larger than the wavelength of the laser radiation and complex superimposed LIPSS patterns are also predicted by the model.
4. Modeling laser-induced periodic surface structures: Finite-difference time-domain feedback simulations
Science.gov (United States)
Skolski, J. Z. P.; Römer, G. R. B. E.; Vincenc Obona, J.; Huis in't Veld, A. J.
2014-03-01
A model predicting the formation of laser-induced periodic surface structures (LIPSSs) is presented. That is, the finite-difference time domain method is used to study the interaction of electromagnetic fields with rough surfaces. In this approach, the rough surface is modified by "ablation after each laser pulse," according to the absorbed energy profile, in order to account for inter-pulse feedback mechanisms. LIPSSs with a periodicity significantly smaller than the laser wavelength are found to "grow" either parallel or orthogonal to the laser polarization. The change in orientation and periodicity follow from the model. LIPSSs with a periodicity larger than the wavelength of the laser radiation and complex superimposed LIPSS patterns are also predicted by the model.
5. Effective Relaying in Two-user Interference Channel with Different Models of Channel Output Feedback
CERN Document Server
Sahai, Achaleshwar; Yuksel, Melda; Sabharwal, Ashutosh
2011-01-01
In this paper, we study the impact of channel output feedback architectures on the capacity of two-user interference channel. For a two-user interference channel, a feedback link can exist between receivers and transmitters in 9 canonical architectures, ranging from only one feedback link to four-feedback links. We derive exact capacity region for the deterministic interference channel and constant-gap capacity region for the Gaussian interference channel for all but two of the 9 architectures (or models). We find that the sum-capacity in deterministic interference channel with only one feedback link, from any one receiver to its own transmitter, is identical to the interference channel with four feedback links; for the Gaussian model, the gap is bounded for all channel gains. However, one feedback link is not sufficient to achieve the whole capacity region of four feedback links. To achieve the full capacity region requires at least two feedback links. To prove the results, we derive several new outer bounds...
6. The Impact of Feedback on the Different Time Courses of Multisensory Temporal Recalibration
Directory of Open Access Journals (Sweden)
Matthew A. De Niear
2017-01-01
Full Text Available The capacity to rapidly adjust perceptual representations confers a fundamental advantage when confronted with a constantly changing world. Unexplored is how feedback regarding sensory judgments (top-down factors interacts with sensory statistics (bottom-up factors to drive long- and short-term recalibration of multisensory perceptual representations. Here, we examined the time course of both cumulative and rapid temporal perceptual recalibration for individuals completing an audiovisual simultaneity judgment task in which they were provided with varying degrees of feedback. We find that in the presence of feedback (as opposed to simple sensory exposure temporal recalibration is more robust. Additionally, differential time courses are seen for cumulative and rapid recalibration dependent upon the nature of the feedback provided. Whereas cumulative recalibration effects relied more heavily on feedback that informs (i.e., negative feedback rather than confirms (i.e., positive feedback the judgment, rapid recalibration shows the opposite tendency. Furthermore, differential effects on rapid and cumulative recalibration were seen when the reliability of feedback was altered. Collectively, our findings illustrate that feedback signals promote and sustain audiovisual recalibration over the course of cumulative learning and enhance rapid trial-to-trial learning. Furthermore, given the differential effects seen for cumulative and rapid recalibration, these processes may function via distinct mechanisms.
7. The Impact of Feedback on the Different Time Courses of Multisensory Temporal Recalibration
Science.gov (United States)
Noel, Jean-Paul; Wallace, Mark T.
2017-01-01
The capacity to rapidly adjust perceptual representations confers a fundamental advantage when confronted with a constantly changing world. Unexplored is how feedback regarding sensory judgments (top-down factors) interacts with sensory statistics (bottom-up factors) to drive long- and short-term recalibration of multisensory perceptual representations. Here, we examined the time course of both cumulative and rapid temporal perceptual recalibration for individuals completing an audiovisual simultaneity judgment task in which they were provided with varying degrees of feedback. We find that in the presence of feedback (as opposed to simple sensory exposure) temporal recalibration is more robust. Additionally, differential time courses are seen for cumulative and rapid recalibration dependent upon the nature of the feedback provided. Whereas cumulative recalibration effects relied more heavily on feedback that informs (i.e., negative feedback) rather than confirms (i.e., positive feedback) the judgment, rapid recalibration shows the opposite tendency. Furthermore, differential effects on rapid and cumulative recalibration were seen when the reliability of feedback was altered. Collectively, our findings illustrate that feedback signals promote and sustain audiovisual recalibration over the course of cumulative learning and enhance rapid trial-to-trial learning. Furthermore, given the differential effects seen for cumulative and rapid recalibration, these processes may function via distinct mechanisms.
8. Feedback Provision in Mentoring Conversation--Differing Mentor and Student Perceptions
Science.gov (United States)
Korver, Bettina; Tillema, Harm
2014-01-01
Diverging perceptions between a mentor and a mentee on the nature and content of feedback given in mentoring conversations may have a profound impact on the mentee's learning from conversation. This study gauges whether approaches to mentoring relate to establishing congruency in perceptions on provided feedback. The aim of this research is to…
9. Effects of different feedback types on information integration in repeated monetary gambles
Directory of Open Access Journals (Sweden)
Peter eHaffke
2015-01-01
Full Text Available Most models of risky decision making assume that all relevant information is taken into account (e.g., Kahneman & Tversky, 1979; von Neumann & Morgenstern, 1944. However, there are also some models supposing that only part of the information is considered (e.g., Brandstätter, Gigerenzer, & Hertwig, 2006; Gigerenzer & Gaissmaier, 2011. To further investigate the amount of information that is usually used for decision making, and how the use depends on feedback, we conducted a series of three experiments in which participants choose between two lotteries and where no feedback, outcome feedback, and error feedback was provided, respectively. The result show that without feedback participants mostly chose the lottery with the higher winning probability, and largely ignored the potential gains. The same result occurred when the outcome of each decision was fed back. Only after presenting error feedback (i.e., signaling whether a choice was optimal or not, participants considered probabilities as well as gains, resulting in more optimal choices. We propose that outcome feedback was ineffective, because of its probabilistic and ambiguous nature. Participants improve information integration only if provided with a consistent and deterministic signal such as error feedback.
10. Effects of different feedback types on information integration in repeated monetary gambles.
Science.gov (United States)
Haffke, Peter; Hübner, Ronald
2014-01-01
Most models of risky decision making assume that all relevant information is taken into account (e.g., von Neumann and Morgenstern, 1944; Kahneman and Tversky, 1979). However, there are also some models supposing that only part of the information is considered (e.g., Brandstätter et al., 2006; Gigerenzer and Gaissmaier, 2011). To further investigate the amount of information that is usually used for decision making, and how the use depends on feedback, we conducted a series of three experiments in which participants choose between two lotteries and where no feedback, outcome feedback, and error feedback was provided, respectively. The results show that without feedback participants mostly chose the lottery with the higher winning probability, and largely ignored the potential gains. The same results occurred when the outcome of each decision was fed back. Only after presenting error feedback (i.e., signaling whether a choice was optimal or not), participants considered probabilities as well as gains, resulting in more optimal choices. We propose that outcome feedback was ineffective, because of its probabilistic and ambiguous nature. Participants improve information integration only if provided with a consistent and deterministic signal such as error feedback.
11. Emotional feedback for mobile devices
CERN Document Server
Seebode, Julia
2015-01-01
This book investigates the functional adequacy as well as the affective impression made by feedback messages on mobile devices. It presents an easily adoptable experimental setup to examine context effects on various feedback messages, and applies it to auditory, tactile and auditory-tactile feedback messages. This approach provides insights into the relationship between the affective impression and functional applicability of these messages as well as an understanding of the influence of unimodal components on the perception of multimodal feedback messages. The developed paradigm can also be extended to investigate other aspects of context and used to investigate feedback messages in modalities other than those presented. The book uses questionnaires implemented on a Smartphone, which can easily be adopted for field studies to broaden the scope even wider. Finally, the book offers guidelines for the design of system feedback.
12. Auditory and Cognitive Factors Underlying Individual Differences in Aided Speech-Understanding among Older Adults
Directory of Open Access Journals (Sweden)
Larry E. Humes
2013-10-01
Full Text Available This study was designed to address individual differences in aided speech understanding among a relatively large group of older adults. The group of older adults consisted of 98 adults (50 female and 48 male ranging in age from 60 to 86 (mean = 69.2. Hearing loss was typical for this age group and about 90% had not worn hearing aids. All subjects completed a battery of tests, including cognitive (6 measures, psychophysical (17 measures, and speech-understanding (9 measures, as well as the Speech, Spatial and Qualities of Hearing (SSQ self-report scale. Most of the speech-understanding measures made use of competing speech and the non-speech psychophysical measures were designed to tap phenomena thought to be relevant for the perception of speech in competing speech (e.g., stream segregation, modulation-detection interference. All measures of speech understanding were administered with spectral shaping applied to the speech stimuli to fully restore audibility through at least 4000 Hz. The measures used were demonstrated to be reliable in older adults and, when compared to a reference group of 28 young normal-hearing adults, age-group differences were observed on many of the measures. Principal-components factor analysis was applied successfully to reduce the number of independent and dependent (speech understanding measures for a multiple-regression analysis. Doing so yielded one global cognitive-processing factor and five non-speech psychoacoustic factors (hearing loss, dichotic signal detection, multi-burst masking, stream segregation, and modulation detection as potential predictors. To this set of six potential predictor variables were added subject age, Environmental Sound Identification (ESI, and performance on the text-recognition-threshold (TRT task (a visual analog of interrupted speech recognition. These variables were used to successfully predict one global aided speech-understanding factor, accounting for about 60% of the variance.
13. Contributions of Different Cloud Types to Feedbacks and Rapid Adjustments in CMIP5*
Energy Technology Data Exchange (ETDEWEB)
Zelinka, Mark D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Program for Climate Model Diagnosis and Intercomparison; Klein, Stephen A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Program for Climate Model Diagnosis and Intercomparison; Taylor, Karl E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Program for Climate Model Diagnosis and Intercomparison; Andrews, Timothy [Met Office Hadley Center, Exeter (United Kingdom); Webb, Mark J. [Met Office Hadley Center, Exeter (United Kingdom); Gregory, Jonathan M. [Univ. of Reading, Exeter (United Kingdom). National Center for Atmospheric Science; Forster, Piers M. [Univ. of Leeds (United Kingdom)
2013-07-01
When using five climate model simulations of the response to an abrupt quadrupling of CO2, the authors perform the first simultaneous model intercomparison of cloud feedbacks and rapid radiative adjustments with cloud masking effects removed, partitioned among changes in cloud types and gross cloud properties. After CO2 quadrupling, clouds exhibit a rapid reduction in fractional coverage, cloud-top pressure, and optical depth, with each contributing equally to a 1.1 W m-2 net cloud radiative adjustment, primarily from shortwave radiation. Rapid reductions in midlevel clouds and optically thick clouds are important in reducing planetary albedo in every model. As the planet warms, clouds become fewer, higher, and thicker, and global mean net cloud feedback is positive in all but one model and results primarily from increased trapping of longwave radiation. As was true for earlier models, high cloud changes are the largest contributor to intermodel spread in longwave and shortwave cloud feedbacks, but low cloud changes are the largest contributor to the mean and spread in net cloud feedback. The importance of the negative optical depth feedback relative to the amount feedback at high latitudes is even more marked than in earlier models. Furthermore, the authors show that the negative longwave cloud adjustment inferred in previous studies is primarily caused by a 1.3 W m-2 cloud masking of CO2 forcing. Properly accounting for cloud masking increases net cloud feedback by 0.3 W m-2 K-1, whereas accounting for rapid adjustments reduces by 0.14 W m-2 K-1 the ensemble mean net cloud feedback through a combination of smaller positive cloud amount and altitude feedbacks and larger negative optical depth feedbacks.
14. Differences in brain circuitry for appetitive and reactive aggression as revealed by realistic auditory scripts
Directory of Open Access Journals (Sweden)
James Kenneth Moran
2014-12-01
Full Text Available Aggressive behavior is thought to divide into two motivational elements: The first being a self-defensively motivated aggression against threat and a second, hedonically motivated ‘appetitive’ aggression. Appetitive aggression is the less understood of the two, often only researched within abnormal psychology. Our approach is to understand it as a universal and adaptive response, and examine the functional neural activity of ordinary men (N=50 presented with an imaginative listening task involving a murderer describing a kill. We manipulated motivational context in a between-subjects design to evoke appetitive or reactive aggression, against a neutral control, measuring activity with Magnetoencephalography (MEG. Results show differences in left frontal regions in delta (2-5 Hz and alpha band (8-12 Hz for aggressive conditions and right parietal delta activity differentiating appetitive and reactive aggression. These results validate the distinction of reward-driven appetitive aggression from reactive aggression in ordinary populations at the level of functional neural brain circuitry.
15. Clinical Study on Effect of Electro-acupuncture Combined with Different Anesthetics on Auditory-evoked Potential Index
Institute of Scientific and Technical Information of China (English)
2006-01-01
Objective: To observe the effect of electro-acupuncture (EA) on auto regressive with exogenous input model (ARX-model) auditory evoked index (AAI) in patients anesthetized with different anesthetics. Methods: Forty-eight adult patients undergoing scheduled surgical operation were enrolled and divided into two groups (24 in each group) according to the anesthetics applied, Group A was anesthetized with propofol sedation and Group B with Isoflurane-epidural anesthesia. Group A was subdivided into three groups of low, middle and high concentration of target effect-site of 1.0 μg/ml, 1.5 μg/ml and 2.0 μg/ml through target controlled infusion (TCI) and Group B into 3 subgroups of minimum alveolar effective concentration of isoflurane (0.4 MAC, 0.6 MAC and 0.8 MAC for B1, B2 and B3 subgroups) respectively, with 8 patients in every subgroup. EA on acupoints of Hegu (LI4) and Neiguan (P6) was applied on all the patients during anesthesia, and the change of AAI at various time points was recorded. Results: In the three subgroups of Group A, levels of AAI were significantly elevated in the first few minutes after EA, and significantly lowered 20 min after EA in subgroup A2. While in the subgroups of Group B, except the elevating in Group B1 1 -2 min after EA, levels of AAI remained unchanged at other time points. Conclusion: Pain response could be reflected by AAI during EA. EA could enhance the sedative effect of propofol in middle concentration, but its effect on isoflurane epidural anesthesia is insignificant.
16. Objective measures of binaural masking level differences and comodulation masking release based on late auditory evoked potentials
DEFF Research Database (Denmark)
Epp, Bastian; Yasin, Ifat; Verhey, Jesko L.
2013-01-01
The audibility of important sounds is often hampered due to the presence of other masking sounds. The present study investigates if a correlate of the audibility of a tone masked by noise is found in late auditory evoked potentials measured from human listeners. The audibility of the target sound...
17. Examination of Individual Differences in Outcomes from a Randomized Controlled Clinical Trial Comparing Formal and Informal Individual Auditory Training Programs
Science.gov (United States)
Smith, Sherri L.; Saunders, Gabrielle H.; Chisolm, Theresa H.; Frederick, Melissa; Bailey, Beth A.
2016-01-01
Purpose: The purpose of this study was to determine if patient characteristics or clinical variables could predict who benefits from individual auditory training. Method: A retrospective series of analyses were performed using a data set from a large, multisite, randomized controlled clinical trial that compared the treatment effects of at-home…
18. Understanding the differing governance of EU emissions trading and renewable: feedback mechanisms and policy entrepreneurs
Energy Technology Data Exchange (ETDEWEB)
Boasson, Elin Lerum; Wettestad, Joergen
2010-04-15
This paper presents a comparative study of two central EU climate policies: the revised Emissions Trading System (ETS), and the revised Renewable Energy Directive (RES). Both were originally developed in the early 2000s and revised policies were adopted in December 2008. While the ETS from 2013 on will have a quite centralized and market-streamlined design, the revised RES stands forward as a more decentralized and technology-focused policy. Differing institutional feed-back mechanisms and related roles of policy entrepreneurs can shed considerable light on these policy differences. Due to member states' cautiousness and contrary to the preferences of the Commission, the initial ETS was designed as a rather decentralized and 'politicized' market system, creating a malfunctioning institutional dynamic. In the revision process, the Commission skillfully highlighted this ineffective dynamic to win support for a much more centralized and market-streamlined approach. In the case of RES, national technology-specific support schemes and the strong links between the renewable industry and member states promoted the converse outcome: decentralization and technology development. Members of the European Parliament utilized these mechanisms through policy networking, while the Commission successfully used developments within the global climate regime to induce some degree of centralization. (Author)
19. Judgments of learning are significantly higher following feedback on relatively good versus relatively poor trials despite no actual learning differences.
Science.gov (United States)
Carter, Michael J; Smith, Victoria; Ste-Marie, Diane M
2016-02-01
Studies have consistently shown that prospective metacognitive judgments of learning are often inaccurate because humans mistakenly interpret current performance levels as valid indices of learning. These metacognitive discrepancies are strongly related to conditions of practice. Here, we examined how the type of feedback (after good versus poor trials) received during practice and awareness (aware versus unaware) of this manipulation affected judgments of learning and actual learning. After each six-trial block, participants received feedback on their three best trials or three worst trials and half of the participants were made explicitly aware of the type of feedback they received while the other half were unaware. Judgments of learning were made at the end of each six-trial block and before the 24-h retention test. Results indicated no motor performance differences between groups in practice or retention; however, receiving feedback on relatively good compared to relatively poor trials resulted in significantly higher judgments of learning in practice and retention, irrespective of awareness. These results suggest that KR on relatively good versus relatively poor trials can have dissociable effects on judgments of learning in the absence of actual learning differences, even when participants are made aware of their feedback manipulation.
20. The interplay between feedback-related negativity and individual differences in altruistic punishment: An EEG study.
Science.gov (United States)
Mothes, Hendrik; Enge, Sören; Strobel, Alexander
2016-04-01
To date, the interplay betwexen neurophysiological and individual difference factors in altruistic punishment has been little understood. To examine this issue, 45 individuals participated in a Dictator Game with punishment option while the feedback-related negativity (FRN) was derived from the electroencephalogram (EEG). Unlike previous EEG studies on the Dictator Game, we introduced a third party condition to study the effect of fairness norm violations in addition to employing a first person perspective. For the first time, we also examined the role of individual differences, specifically fairness concerns, positive/negative affectivity, and altruism/empathy as well as recipients' financial situation during altruistic punishment. The main results show that FRN amplitudes were more pronounced for unfair than for fair assignments in both the first person and third party perspectives. These findings suggest that FRN amplitudes are sensitive to fairness norm violations and play a crucial role in the recipients' evaluation of dictator assignments. With respect to individual difference factors, recipients' current financial situation affected the FRN fairness effect in the first person perspective, indicating that when being directly affected by the assignments, more affluent participants experienced stronger violations of expectations in altruistic punishment decisions. Regarding individual differences in trait empathy, in the third party condition FRN amplitudes were more pronounced for those who scored lower in empathy. This may suggest empathy as another motive in third party punishment. Independent of the perspective taken, higher positive affect was associated with more punishment behavior, suggesting that positive emotions may play an important role in restoring violated fairness norms.
1. Auditory N1 reveals planning and monitoring processes during music performance.
Science.gov (United States)
Mathias, Brian; Gehring, William J; Palmer, Caroline
2017-02-01
The current study investigated the relationship between planning processes and feedback monitoring during music performance, a complex task in which performers prepare upcoming events while monitoring their sensory outcomes. Theories of action planning in auditory-motor production tasks propose that the planning of future events co-occurs with the perception of auditory feedback. This study investigated the neural correlates of planning and feedback monitoring by manipulating the contents of auditory feedback during music performance. Pianists memorized and performed melodies at a cued tempo in a synchronization-continuation task while the EEG was recorded. During performance, auditory feedback associated with single melody tones was occasionally substituted with tones corresponding to future (next), present (current), or past (previous) melody tones. Only future-oriented altered feedback disrupted behavior: Future-oriented feedback caused pianists to slow down on the subsequent tone more than past-oriented feedback, and amplitudes of the auditory N1 potential elicited by the tone immediately following the altered feedback were larger for future-oriented than for past-oriented or noncontextual (unrelated) altered feedback; larger N1 amplitudes were associated with greater slowing following altered feedback in the future condition only. Feedback-related negativities were elicited in all altered feedback conditions. In sum, behavioral and neural evidence suggests that future-oriented feedback disrupts performance more than past-oriented feedback, consistent with planning theories that posit similarity-based interference between feedback and planning contents. Neural sensory processing of auditory feedback, reflected in the N1 ERP, may serve as a marker for temporal disruption caused by altered auditory feedback in auditory-motor production tasks.
2. Brain activity is related to individual differences in the number of items stored in auditory short-term memory for pitch: evidence from magnetoencephalography.
Science.gov (United States)
Grimault, Stephan; Nolden, Sophie; Lefebvre, Christine; Vachon, François; Hyde, Krista; Peretz, Isabelle; Zatorre, Robert; Robitaille, Nicolas; Jolicoeur, Pierre
2014-07-01
We used magnetoencephalography (MEG) to examine brain activity related to the maintenance of non-verbal pitch information in auditory short-term memory (ASTM). We focused on brain activity that increased with the number of items effectively held in memory by the participants during the retention interval of an auditory memory task. We used very simple acoustic materials (i.e., pure tones that varied in pitch) that minimized activation from non-ASTM related systems. MEG revealed neural activity in frontal, temporal, and parietal cortices that increased with a greater number of items effectively held in memory by the participants during the maintenance of pitch representations in ASTM. The present results reinforce the functional role of frontal and temporal cortices in the retention of pitch information in ASTM. This is the first MEG study to provide both fine spatial localization and temporal resolution on the neural mechanisms of non-verbal ASTM for pitch in relation to individual differences in the capacity of ASTM. This research contributes to a comprehensive understanding of the mechanisms mediating the representation and maintenance of basic non-verbal auditory features in the human brain.
3. Measurements of the linewidth enhancement factor of mid-infrared quantum cascade lasers by different optical feedback techniques
Directory of Open Access Journals (Sweden)
L. Jumpertz
2016-01-01
Full Text Available Precise knowledge of the linewidth enhancement factor of a semiconductor laser under actual operating conditions is of prime importance since this parameter dictates various phenomena such as linewidth broadening or optical nonlinearities enhancement. The above-threshold linewidth enhancement factor of a mid-infrared quantum cascade laser structure operated at 10∘C is determined experimentally using two different methods based on optical feedback. Both Fabry-Perot and distributed feedback quantum cascade lasers based on the same active area design are studied, the former by following the wavelength shift as a function of the feedback strength and the latter by self-mixing interferometry. The results are consistent and unveil a clear pump current dependence of the linewidth enhancement factor, with values ranging from 0.8 to about 3.
4. Measurements of the linewidth enhancement factor of mid-infrared quantum cascade lasers by different optical feedback techniques
Energy Technology Data Exchange (ETDEWEB)
Jumpertz, L., E-mail: [email protected] [Université Paris-Saclay, Télécom ParisTech, CNRS LTCI, 46 rue Barrault, F-75013 Paris (France); MirSense, 8 avenue de la Vauve, F-91120 Palaiseau (France); Michel, F.; Pawlus, R.; Elsässer, W. [Technische Universität Darmstadt, Schlossgartenstr. 7, D-64289 Darmstadt (Germany); Schires, K. [Université Paris-Saclay, Télécom ParisTech, CNRS LTCI, 46 rue Barrault, F-75013 Paris (France); Carras, M. [MirSense, 8 avenue de la Vauve, F-91120 Palaiseau (France); Grillot, F. [Université Paris-Saclay, Télécom ParisTech, CNRS LTCI, 46 rue Barrault, F-75013 Paris (France); also with Center for High Technology Materials, University of New-Mexico, 1313 Goddard SE, Albuquerque, NM (United States)
2016-01-15
Precise knowledge of the linewidth enhancement factor of a semiconductor laser under actual operating conditions is of prime importance since this parameter dictates various phenomena such as linewidth broadening or optical nonlinearities enhancement. The above-threshold linewidth enhancement factor of a mid-infrared quantum cascade laser structure operated at 10{sup ∘}C is determined experimentally using two different methods based on optical feedback. Both Fabry-Perot and distributed feedback quantum cascade lasers based on the same active area design are studied, the former by following the wavelength shift as a function of the feedback strength and the latter by self-mixing interferometry. The results are consistent and unveil a clear pump current dependence of the linewidth enhancement factor, with values ranging from 0.8 to about 3.
5. The Effect of Online Gaming, Cognition and Feedback Type in Facilitating Delayed Achievement of Different Learning Objectives
Science.gov (United States)
Cameron, Brian; Dwyer, Francis
2005-01-01
Online and computer-based instructional gaming is becoming a viable instructional strategy at all levels of education. The purpose of this study was to examine the effect of (a) gaming, (b) gaming plus embedded questions, and (c) gaming plus questions plus feedback on delayed retention of different types of educational objectives for students…
6. Auditory Cortex is Important in the Extinction of Two Different Tone-Based Conditioned Fear Memories in Rats
OpenAIRE
Eun Young Song; Boatman, Jeffrey A; Jung, Min W.; Kim, Jeansok J.
2010-01-01
Extensive fear extinction research is guided by the view that there are structures in the brain that develop inhibitory control over the expression of conditioned fear memories. While the medial prefrontal cortex has recently captured attention as the locus of plasticity essential for extinction of conditioned fear, the auditory cortex is another plausible cortical area involved in extinction learning since it is considered a sufficient conditioned stimulus (CS) pathway in tone fear conditio...
7. The Effect of Six Different Corrective Feedback Strategies on Iranian English Language Learners’ IELTS Writing Task 2
Directory of Open Access Journals (Sweden)
Reza Vahdani Sanavi
2014-06-01
Full Text Available Scholars have long studied the effect of corrective feedback strategies on the writing ability of language learners, but few have formed designs in which more than three feedback strategies have been used. In this research, the ultimate goal was to discover how International English Language Testing System (IELTS- candidates could be helped to perform better in the writing component of the test with the feedback they get. To this end, 186 learners attending IELTS preparation classes in three different English language institutes participated in this quasi-experimental study. A one-way ANOVA was run to discover the significant difference among the six groups. The findings proposed that Iranian English as a Foreign Language (EFL students’ writing ability improved as a result of the employment of writing feedback strategies but that reformulation strategy was the most effective one. Teachers can, thus, benefit from the finding of this research by studying the way they should tackle the learners’ inaccurate productions as far as different writing score band descriptors are concerned.
8. The effects of different quantum feedback types on the tightness of the variance-based uncertainty
Science.gov (United States)
Zheng, Xiao; Zhang, Guo-Feng
2017-03-01
The effect of the quantum feedback on the tightness of the variance-based uncertainty, the possibility of using quantum feedback to prepare the state with a better tightness, and the relationship between the tightness of the uncertainty and the mixedness of the system are studied. It is found that the tightness of Schrodinger-Robertson uncertainty (SUR) relation has a strict liner relationship with the mixedness of the system. As for the Robertson uncertainty relation (RUR), we find that the tightness can be enhanced by tuning the feedback at the beginning of the evolution. In addition, we deduce that the tightness of RUR has an inverse relationship with the mixedness and the relationship turns into a strict linear one when the system reach the steady state.
9. Auditory and audio-visual processing in patients with cochlear, auditory brainstem, and auditory midbrain implants: An EEG study.
Science.gov (United States)
Schierholz, Irina; Finke, Mareike; Kral, Andrej; Büchner, Andreas; Rach, Stefan; Lenarz, Thomas; Dengler, Reinhard; Sandmann, Pascale
2017-04-01
There is substantial variability in speech recognition ability across patients with cochlear implants (CIs), auditory brainstem implants (ABIs), and auditory midbrain implants (AMIs). To better understand how this variability is related to central processing differences, the current electroencephalography (EEG) study compared hearing abilities and auditory-cortex activation in patients with electrical stimulation at different sites of the auditory pathway. Three different groups of patients with auditory implants (Hannover Medical School; ABI: n = 6, CI: n = 6; AMI: n = 2) performed a speeded response task and a speech recognition test with auditory, visual, and audio-visual stimuli. Behavioral performance and cortical processing of auditory and audio-visual stimuli were compared between groups. ABI and AMI patients showed prolonged response times on auditory and audio-visual stimuli compared with NH listeners and CI patients. This was confirmed by prolonged N1 latencies and reduced N1 amplitudes in ABI and AMI patients. However, patients with central auditory implants showed a remarkable gain in performance when visual and auditory input was combined, in both speech and non-speech conditions, which was reflected by a strong visual modulation of auditory-cortex activation in these individuals. In sum, the results suggest that the behavioral improvement for audio-visual conditions in central auditory implant patients is based on enhanced audio-visual interactions in the auditory cortex. Their findings may provide important implications for the optimization of electrical stimulation and rehabilitation strategies in patients with central auditory prostheses. Hum Brain Mapp 38:2206-2225, 2017. © 2017 Wiley Periodicals, Inc.
10. Two distinct auditory-motor circuits for monitoring speech production as revealed by content-specific suppression of auditory cortex.
Science.gov (United States)
Ylinen, Sari; Nora, Anni; Leminen, Alina; Hakala, Tero; Huotilainen, Minna; Shtyrov, Yury; Mäkelä, Jyrki P; Service, Elisabet
2015-06-01
Speech production, both overt and covert, down-regulates the activation of auditory cortex. This is thought to be due to forward prediction of the sensory consequences of speech, contributing to a feedback control mechanism for speech production. Critically, however, these regulatory effects should be specific to speech content to enable accurate speech monitoring. To determine the extent to which such forward prediction is content-specific, we recorded the brain's neuromagnetic responses to heard multisyllabic pseudowords during covert rehearsal in working memory, contrasted with a control task. The cortical auditory processing of target syllables was significantly suppressed during rehearsal compared with control, but only when they matched the rehearsed items. This critical specificity to speech content enables accurate speech monitoring by forward prediction, as proposed by current models of speech production. The one-to-one phonological motor-to-auditory mappings also appear to serve the maintenance of information in phonological working memory. Further findings of right-hemispheric suppression in the case of whole-item matches and left-hemispheric enhancement for last-syllable mismatches suggest that speech production is monitored by 2 auditory-motor circuits operating on different timescales: Finer grain in the left versus coarser grain in the right hemisphere. Taken together, our findings provide hemisphere-specific evidence of the interface between inner and heard speech.
11. From ear to hand: the role of the auditory-motor loop in pointing to an auditory source
Directory of Open Access Journals (Sweden)
Eric Olivier Boyer
2013-04-01
Full Text Available Studies of the nature of the neural mechanisms involved in goal-directed movements tend to concentrate on the role of vision. We present here an attempt to address the mechanisms whereby an auditory input is transformed into a motor command. The spatial and temporal organization of hand movements were studied in normal human subjects as they pointed towards unseen auditory targets located in a horizontal plane in front of them. Positions and movements of the hand were measured by a six infrared camera tracking system. In one condition, we assessed the role of auditory information about target position in correcting the trajectory of the hand. To accomplish this, the duration of the target presentation was varied. In another condition, subjects received continuous auditory feedback of their hand movement while pointing to the auditory targets. Online auditory control of the direction of pointing movements was assessed by evaluating how subjects reacted to shifts in heard hand position. Localization errors were exacerbated by short duration of target presentation but not modified by auditory feedback of hand position. Long duration of target presentation gave rise to a higher level of accuracy and was accompanied by early automatic head orienting movements consistently related to target direction. These results highlight the efficiency of auditory feedback processing in online motor control and suggest that the auditory system takes advantages of dynamic changes of the acoustic cues due to changes in head orientation in order to process online motor control. How to design an informative acoustic feedback needs to be carefully studied to demonstrate that auditory feedback of the hand could assist the monitoring of movements directed at objects in auditory space.
12. From ear to hand: the role of the auditory-motor loop in pointing to an auditory source
Science.gov (United States)
Boyer, Eric O.; Babayan, Bénédicte M.; Bevilacqua, Frédéric; Noisternig, Markus; Warusfel, Olivier; Roby-Brami, Agnes; Hanneton, Sylvain; Viaud-Delmon, Isabelle
2013-01-01
Studies of the nature of the neural mechanisms involved in goal-directed movements tend to concentrate on the role of vision. We present here an attempt to address the mechanisms whereby an auditory input is transformed into a motor command. The spatial and temporal organization of hand movements were studied in normal human subjects as they pointed toward unseen auditory targets located in a horizontal plane in front of them. Positions and movements of the hand were measured by a six infrared camera tracking system. In one condition, we assessed the role of auditory information about target position in correcting the trajectory of the hand. To accomplish this, the duration of the target presentation was varied. In another condition, subjects received continuous auditory feedback of their hand movement while pointing to the auditory targets. Online auditory control of the direction of pointing movements was assessed by evaluating how subjects reacted to shifts in heard hand position. Localization errors were exacerbated by short duration of target presentation but not modified by auditory feedback of hand position. Long duration of target presentation gave rise to a higher level of accuracy and was accompanied by early automatic head orienting movements consistently related to target direction. These results highlight the efficiency of auditory feedback processing in online motor control and suggest that the auditory system takes advantages of dynamic changes of the acoustic cues due to changes in head orientation in order to process online motor control. How to design an informative acoustic feedback needs to be carefully studied to demonstrate that auditory feedback of the hand could assist the monitoring of movements directed at objects in auditory space. PMID:23626532
13. Application of a model of the auditory primal sketch to cross-linguistic differences in speech rhythm: Implications for the acquisition and recognition of speech
Science.gov (United States)
Todd, Neil P. M.; Lee, Christopher S.
2002-05-01
It has long been noted that the world's languages vary considerably in their rhythmic organization. Different languages seem to privilege different phonological units as their basic rhythmic unit, and there is now a large body of evidence that such differences have important consequences for crucial aspects of language acquisition and processing. The most fundamental finding is that the rhythmic structure of a language strongly influences the process of spoken-word recognition. This finding, together with evidence that infants are sensitive from birth to rhythmic differences between languages, and exploit rhythmic cues to segmentation at an earlier developmental stage than other cues prompted the claim that rhythm is the key which allows infants to begin building a lexicon and then go on to acquire syntax. It is therefore of interest to determine how differences in rhythmic organization arise at the acoustic/auditory level. In this paper, it is shown how an auditory model of the primitive representation of sound provides just such an account of rhythmic differences. Its performance is evaluated on a data set of French and English sentences and compared with the results yielded by the phonetic accounts of Frank Ramus and his colleagues and Esther Grabe and her colleagues.
14. Auditory-perceptual learning improves speech motor adaptation in children.
Science.gov (United States)
Shiller, Douglas M; Rochon, Marie-Lyne
2014-08-01
Auditory feedback plays an important role in children's speech development by providing the child with information about speech outcomes that is used to learn and fine-tune speech motor plans. The use of auditory feedback in speech motor learning has been extensively studied in adults by examining oral motor responses to manipulations of auditory feedback during speech production. Children are also capable of adapting speech motor patterns to perceived changes in auditory feedback; however, it is not known whether their capacity for motor learning is limited by immature auditory-perceptual abilities. Here, the link between speech perceptual ability and the capacity for motor learning was explored in two groups of 5- to 7-year-old children who underwent a period of auditory perceptual training followed by tests of speech motor adaptation to altered auditory feedback. One group received perceptual training on a speech acoustic property relevant to the motor task while a control group received perceptual training on an irrelevant speech contrast. Learned perceptual improvements led to an enhancement in speech motor adaptation (proportional to the perceptual change) only for the experimental group. The results indicate that children's ability to perceive relevant speech acoustic properties has a direct influence on their capacity for sensory-based speech motor adaptation.
15. Exergaming for elderly: : effects of different types of game feedback on performance of a balance task.
NARCIS (Netherlands)
Lamoth, Claude; Alingh, Rolinde; Caljouw, Simone; Wiederhold, B.K.; Riva, G.
2012-01-01
Balance training to improve postural control in elderly can contribute to the prevention of falls. Video games that require body movements have the potential to improve balance. However, research about the effects of type of visual feedback (i.e. the exergame) on the quality of movement and experien
16. The Effect of Different Types of Corrective Feedback on ESL Student Writing
Science.gov (United States)
Bitchener, John; Young, Stuart; Cameron, Denise
2005-01-01
Debate about the value of providing corrective feedback on L2 writing has been prominent in recent years as a result of Truscott's [Truscott, J. (1996). The case against grammar correction in L2 writing classes. Language Learning, 46, 327-369] claim that it is both ineffective and harmful and should therefore be abandoned. A growing body of…
17. Goal orientations and the seeking of different types of feedback information
NARCIS (Netherlands)
Janssen, Onne; Prins, Jelle
2007-01-01
Based on the goal orientation model of feedback-seeking behaviour, goal orientations are proposed to influence employees in the type of information they seek from knowledgeable others in the work environment. As hypothesized, a survey conducted among 170 medical residents of a Dutch university hospi
18. Noise exposure of immature rats can induce different age-dependent extra-auditory alterations that can be partially restored by rearing animals in an enriched environment.
Science.gov (United States)
Molina, S J; Capani, F; Guelman, L R
2016-04-01
It has been previously shown that different extra-auditory alterations can be induced in animals exposed to noise at 15 days. However, data regarding exposure of younger animals, that do not have a functional auditory system, have not been obtained yet. Besides, the possibility to find a helpful strategy to restore these changes has not been explored so far. Therefore, the aims of the present work were to test age-related differences in diverse hippocampal-dependent behavioral measurements that might be affected in noise-exposed rats, as well as to evaluate the effectiveness of a potential neuroprotective strategy, the enriched environment (EE), on noise-induced behavioral alterations. Male Wistar rats of 7 and 15 days were exposed to moderate levels of noise for two hours. At weaning, animals were separated and reared either in standard or in EE cages for one week. At 28 days of age, different hippocampal-dependent behavioral assessments were performed. Results show that rats exposed to noise at 7 and 15 days were differentially affected. Moreover, EE was effective in restoring all altered variables when animals were exposed at 7 days, while a few were restored in rats exposed at 15 days. The present findings suggest that noise exposure was capable to trigger significant hippocampal-related behavioral alterations that were differentially affected, depending on the age of exposure. In addition, it could be proposed that hearing structures did not seem to be necessarily involved in the generation of noise-induced hippocampal-related behaviors, as they were observed even in animals with an immature auditory pathway. Finally, it could be hypothesized that the differential restoration achieved by EE rearing might also depend on the degree of maturation at the time of exposure and the variable evaluated, being younger animals more susceptible to environmental manipulations.
19. Two different modes of oscillation in a gene transcription regulatory network with interlinked positive and negative feedback loops
Science.gov (United States)
Karmakar, Rajesh
2016-12-01
We study the oscillatory behavior of a gene regulatory network with interlinked positive and negative feedback loop. The frequency and amplitude are two important properties of oscillation. The studied network produces two different modes of oscillation. In one mode (mode-I), frequency of oscillation remains constant over a wide range of amplitude and in the other mode (mode-II) the amplitude of oscillation remains constant over a wide range of frequency. Our study reproduces both features of oscillations in a single gene regulatory network and shows that the negative plus positive feedback loops in gene regulatory network offer additional advantage. We identified the key parameters/variables responsible for different modes of oscillation. The network is flexible in switching between different modes by choosing appropriately the required parameters/variables.
20. [Auditory-evoked responses to a monaural or a binaural click, recorded from the vertex, as in two temporal derivations; effect of interaural time differences (author's transl)].
Science.gov (United States)
Botte, M C; Chocholle, R
1976-01-01
The auditory-evoked responses have been recorded on 5 subject by vertex, right temporal and left temporal electrodes simultaneously. 30 dB sensation level clicks were used as stimuli; one click was presented only to the right ear, or one click only to the left ear, or one click to the right ear and another click to the left ear with a variable interaural time difference in this latter case (0-150 ms). The N-P amplitude variations and the N and P latency variations have been studied and compared to those observed in the perceived lateralizations of the sound source.
1. How Do Batters Use Visual, Auditory, and Tactile Information about the Success of a Baseball Swing?
Science.gov (United States)
Gray, Rob
2009-01-01
Bat/ball contact produces visual (the ball leaving the bat), auditory (the "crack" of the bat), and tactile (bat vibration) feedback about the success of the swing. We used a batting simulation to investigate how college baseball players use visual, tactile, and auditory feedback. In Experiment 1, swing accuracy (i.e., the lateral separation…
2. Auditory Hallucination
Directory of Open Access Journals (Sweden)
2003-09-01
Full Text Available Auditory Hallucination or Paracusia is a form of hallucination that involves perceiving sounds without auditory stimulus. A common is hearing one or more talking voices which is associated with psychotic disorders such as schizophrenia or mania. Hallucination, itself, is the most common feature of perceiving the wrong stimulus or to the better word perception of the absence stimulus. Here we will discuss four definitions of hallucinations:1.Perceiving of a stimulus without the presence of any subject; 2. hallucination proper which are the wrong perceptions that are not the falsification of real perception, Although manifest as a new subject and happen along with and synchronously with a real perception;3. hallucination is an out-of-body perception which has no accordance with a real subjectIn a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid, substantial, and located in external objective space. We are going to discuss it in details here.
3. Adaptation in the auditory system: an overview
Directory of Open Access Journals (Sweden)
David ePérez-González
2014-02-01
Full Text Available The early stages of the auditory system need to preserve the timing information of sounds in order to extract the basic features of acoustic stimuli. At the same time, different processes of neuronal adaptation occur at several levels to further process the auditory information. For instance, auditory nerve fiber responses already experience adaptation of their firing rates, a type of response that can be found in many other auditory nuclei and may be useful for emphasizing the onset of the stimuli. However, it is at higher levels in the auditory hierarchy where more sophisticated types of neuronal processing take place. For example, stimulus-specific adaptation, where neurons show adaptation to frequent, repetitive stimuli, but maintain their responsiveness to stimuli with different physical characteristics, thus representing a distinct kind of processing that may play a role in change and deviance detection. In the auditory cortex, adaptation takes more elaborate forms, and contributes to the processing of complex sequences, auditory scene analysis and attention. Here we review the multiple types of adaptation that occur in the auditory system, which are part of the pool of resources that the neurons employ to process the auditory scene, and are critical to a proper understanding of the neuronal mechanisms that govern auditory perception.
4. Auditory feedback influences perceived driving speeds.
Science.gov (United States)
Horswill, Mark S; Plooy, Annaliese M
2008-01-01
Reducing the level of internal noise is seen as a goal when designing modern cars. One danger of such a philosophy is that one is systematically attempting to alter one of the cues that can be used by drivers to estimate speed and this could bias speed judgments and driving behaviour. Seven participants were presented with pairs of video-based driving scenes and asked to judge whether the second scene appeared faster or slower than the first (2-alternative forced-choice task using the method of constant stimuli). They either heard in-car noise at the level it occurred in the real world or reduced in volume by 5 dB. The reduction in noise led to participants judging speeds to be significantly slower and this effect was evident for all participants. This finding indicates that, when in-car noise is attenuated, drivers are likely to underestimate their speed, potentially encouraging them to drive faster and placing them at greater risk of crashing.
5. The Difference in the Profile of Working Memory, Auditory Working Memory, and Spatial Working Memory between Drug, Stimulant, and Methadone Abusers and Normal People
Directory of Open Access Journals (Sweden)
2015-06-01
Full Text Available Objective: The present study was an attempt to examine the difference in the profile of working memory, auditory working memory, and spatial working memory between drug, stimulant, and methadone abusers and normal people. Method: This study was a causal-comparative one with between-group comparison methodology. All the individuals addicted to opiates, stimulants, and methadone who had referred to Khomeini treatment centers of the city from September 2013 to February 2014 constituted the statistical population of the study. The number of 154 abusers (54 drug abusers, 50 stimulant abusers, and 50 methadone abusers and the number of 50 normal participants were chosen as the sample of the study by purposive sampling method. The participants responded to Wechsler Memory Scale—third edition (WMS-III. Results: There was a significant difference between the normal group and drug, stimulant, and methadone abusers in terms of working memory, auditory working memory, and spatial working memory. Conclusion: Drug and stimulant use leads to sustained damage in cognitive processes such as working memory. However, research indicates that these cognitive processes will improve with the passage of time.
6. Electrostimulation mapping of comprehension of auditory and visual words.
Science.gov (United States)
Roux, Franck-Emmanuel; Miskin, Krasimir; Durand, Jean-Baptiste; Sacko, Oumar; Réhault, Emilie; Tanova, Rositsa; Démonet, Jean-François
2015-10-01
In order to spare functional areas during the removal of brain tumours, electrical stimulation mapping was used in 90 patients (77 in the left hemisphere and 13 in the right; 2754 cortical sites tested). Language functions were studied with a special focus on comprehension of auditory and visual words and the semantic system. In addition to naming, patients were asked to perform pointing tasks from auditory and visual stimuli (using sets of 4 different images controlled for familiarity), and also auditory object (sound recognition) and Token test tasks. Ninety-two auditory comprehension interference sites were observed. We found that the process of auditory comprehension involved a few, fine-grained, sub-centimetre cortical territories. Early stages of speech comprehension seem to relate to two posterior regions in the left superior temporal gyrus. Downstream lexical-semantic speech processing and sound analysis involved 2 pathways, along the anterior part of the left superior temporal gyrus, and posteriorly around the supramarginal and middle temporal gyri. Electrostimulation experimentally dissociated perceptual consciousness attached to speech comprehension. The initial word discrimination process can be considered as an "automatic" stage, the attention feedback not being impaired by stimulation as would be the case at the lexical-semantic stage. Multimodal organization of the superior temporal gyrus was also detected since some neurones could be involved in comprehension of visual material and naming. These findings demonstrate a fine graded, sub-centimetre, cortical representation of speech comprehension processing mainly in the left superior temporal gyrus and are in line with those described in dual stream models of language comprehension processing.
7. 电脑式微波炉控制面板按键反馈类型的比较研究%A Comparative Study on Feedback Types of Key - press on the Control Panel of Computer- type Microwave Oven
Institute of Scientific and Technical Information of China (English)
胡绎茜; 葛列众
2011-01-01
The research aimed to investigate the optimal feedback type of the key - press on the control panel of computer - type microwave oven by comparing different feedback types of the key - press. The experiment adopted the serial target task and 24 participants were invited. The results showed that, there was no significant difference in operation performance among the following three types: the visual feedback, the auditory feedback and the visual - auditory feedback. However, each of these three feedback types in operation performance was better than that of no feedback type. The data of subjective assessment showed that the visual - auditory feedback was the optimal feedback type.%本实验是对电脑式微波炉控制面板中按键反馈类型的比较研究,其目的是确定较优的按键反馈类型.实验采用了系列目标任务的方法,结果表明:视觉反馈、听觉反馈和视听反馈三种反馈类型的操作绩效之间无明显差异,但均优于无反馈条件下的操作绩效,而被试主观评价的数据表明,视听反馈是三种反馈类型中较好的一种.
8. Dynamic Evaluation of LCL-type Grid-Connected Inverters with Different Current Feedback Control Schemes
DEFF Research Database (Denmark)
Han, Yang; Li, Zipeng; Guerrero, Josep M.
2015-01-01
Proportional-resonant (PR) compensator and LCL filter becomes a better choice in grid-connected inverter system with high performance and low costs. However, the resonance phenomenon caused by LCL filter affect the system stability significantly. In this paper, the stability problem of three...... typical current feedback control schemes in LCL grid-connected system are analyzed and compared systematically. Analysis in s-domain take the effect of the digital computation and modulation delay into account. The stability analysis is presented by root locus in the discrete domain, the optimal values...
9. Auditory Neuropathy - A Case of Auditory Neuropathy after Hyperbilirubinemia
Directory of Open Access Journals (Sweden)
Maliheh Mazaher Yazdi
2007-12-01
Full Text Available Background and Aim: Auditory neuropathy is an hearing disorder in which peripheral hearing is normal, but the eighth nerve and brainstem are abnormal. By clinical definition, patient with this disorder have normal OAE, but exhibit an absent or severely abnormal ABR. Auditory neuropathy was first reported in the late 1970s as different methods could identify discrepancy between absent ABR and present hearing threshold. Speech understanding difficulties are worse than can be predicted from other tests of hearing function. Auditory neuropathy may also affect vestibular function. Case Report: This article presents electrophysiological and behavioral data from a case of auditory neuropathy in a child with normal hearing after bilirubinemia in a 5 years follow-up. Audiological findings demonstrate remarkable changes after multidisciplinary rehabilitation. Conclusion: auditory neuropathy may involve damage to the inner hair cells-specialized sensory cells in the inner ear that transmit information about sound through the nervous system to the brain. Other causes may include faulty connections between the inner hair cells and the nerve leading from the inner ear to the brain or damage to the nerve itself. People with auditory neuropathy have OAEs response but absent ABR and hearing loss threshold that can be permanent, get worse or get better.
10. How Do Young Students with Different Profiles of Reading Skill Mastery, Perceived Ability, and Goal Orientation Respond to Holistic Diagnostic Feedback?
Science.gov (United States)
Jang, Eunice Eunhee; Dunlop, Maggie; Park, Gina; van der Boom, Edith H.
2015-01-01
One critical issue with cognitive diagnostic assessment (CDA) lies in its lack of research evidence that shows how diagnostic feedback from CDA is interpreted and used by young students. This mixed methods research examined how holistic diagnostic feedback (HDF) is processed by young learners with different profiles of reading skills, goal…
11. Audio Feedback -- Better Feedback?
Science.gov (United States)
Voelkel, Susanne; Mello, Luciane V.
2014-01-01
National Student Survey (NSS) results show that many students are dissatisfied with the amount and quality of feedback they get for their work. This study reports on two case studies in which we tried to address these issues by introducing audio feedback to one undergraduate (UG) and one postgraduate (PG) class, respectively. In case study one…
12. THE EFFECT OF THE DIFFERENT TYPES OF FEEDBACK ON THE VOLLEYBALL TRAINEES’ INTERNAL IMPULSION.
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Karolina Barzouka
2009-06-01
Full Text Available In physical education there is a two-way relation between acquiring moving skills and the mechanisms ofimpulsion. The goal of the present text was to confirm the effect of this kind of model observation on theinternal impulsion of the participants. Fifty three high school girls of 12-15 years old, separated randomly intolevels, in three teams and practiced in one common intervention programme consisted of 12 practice sessions forthe volleyball skill acquisition (the serve skill – ball reception. The participants of the 1st and the 2ndexperimental teams were receiving as feedback a model observation, while all the three teams were receivingverbal instructions during the intervention programme. At the beginning and the end of the intervention the trainees fulfilled the questionary (Ryan 1982 for the internal impulsion. For the statistic process of the internal impulsion data, the method of fluctuation analysis with 2 factors (3X2 was used. The level of importance wasdefined as p<0.5. The outcome demonstrated that no type of feedback influenced essentially the internal impulsion. There were only tendencies in favor of the second group.
13. Functional dissociation of transient and sustained fMRI BOLD components in human auditory cortex revealed with a streaming paradigm based on interaural time differences.
Science.gov (United States)
Schadwinkel, Stefan; Gutschalk, Alexander
2010-12-01
A number of physiological studies suggest that feature-selective adaptation is relevant to the pre-processing for auditory streaming, the perceptual separation of overlapping sound sources. Most of these studies are focused on spectral differences between streams, which are considered most important for streaming. However, spatial cues also support streaming, alone or in combination with spectral cues, but physiological studies of spatial cues for streaming remain scarce. Here, we investigate whether the tuning of selective adaptation for interaural time differences (ITD) coincides with the range where streaming perception is observed. FMRI activation that has been shown to adapt depending on the repetition rate was studied with a streaming paradigm where two tones were differently lateralized by ITD. Listeners were presented with five different ΔITD conditions (62.5, 125, 187.5, 343.75, or 687.5 μs) out of an active baseline with no ΔITD during fMRI. The results showed reduced adaptation for conditions with ΔITD ≥ 125 μs, reflected by enhanced sustained BOLD activity. The percentage of streaming perception for these stimuli increased from approximately 20% for ΔITD = 62.5 μs to > 60% for ΔITD = 125 μs. No further sustained BOLD enhancement was observed when the ΔITD was increased beyond ΔITD = 125 μs, whereas the streaming probability continued to increase up to 90% for ΔITD = 687.5 μs. Conversely, the transient BOLD response, at the transition from baseline to ΔITD blocks, increased most prominently as ΔITD was increased from 187.5 to 343.75 μs. These results demonstrate a clear dissociation of transient and sustained components of the BOLD activity in auditory cortex.
14. Radiative feedback and cosmic molecular gas: the role of different radiative sources
CERN Document Server
Maio, U; De Lucia, G; Borgani, S
2016-01-01
We present results from multifrequency radiative hydrodynamical chemistry simulations addressing primordial star formation and related stellar feedback from various populations of stars, stellar energy distributions (SEDs) and initial mass functions. Spectra for massive stars, intermediate-mass stars and regular solar-like stars are adopted over a grid of 150 frequency bins and consistently coupled with hydrodynamics, heavy-element pollution and non-equilibrium species calculations. Powerful massive population III stars are found to be able to largely ionize H and, subsequently, He and He$^+$, causing an inversion of the equation of state and a boost of the Jeans masses in the early intergalactic medium. Radiative effects on star formation rates are between a factor of a few and 1 dex, depending on the SED. Radiative processes are responsible for gas heating and photoevaporation, although emission from soft SEDs has minor impacts. These findings have implications for cosmic gas preheating, primordial direct-c...
15. The effect of background music in auditory health persuasion
NARCIS (Netherlands)
Elbert, Sarah; Dijkstra, Arie
2013-01-01
In auditory health persuasion, threatening information regarding health is communicated by voice only. One relevant context of auditory persuasion is the addition of background music. There are different mechanisms through which background music might influence persuasion, for example through mood (
16. The Effect of Positive and Negative Feedback on Risk-Taking across Different Contexts.
Directory of Open Access Journals (Sweden)
Annabel B Losecaat Vermeer
Full Text Available Preferences for risky choices have often been shown to be unstable and context-dependent. Though people generally avoid gambles with mixed outcomes, a phenomenon often attributed to loss aversion, contextual factors can impact this dramatically. For example, people typically prefer risky options after a financial loss, while generally choosing safer options after a monetary gain. However, it is unclear what exactly contributes to these preference shifts as a function of prior outcomes, as these gain/loss outcomes are usually confounded with participant performance, and therefore it is unclear whether these effects are driven purely by the monetary gains or losses, or rather by success or failure at the actual task. Here, we experimentally separated the effects of monetary gains/losses from performance success/failure prior to a standard risky choice. Participants performed a task in which they experienced contextual effects: 1 monetary gain or loss based directly on performance, 2 monetary gain or loss that was randomly awarded and was, crucially, independent from performance, and 3 success or failure feedback based on performance, but without any monetary incentive. Immediately following these positive/negative contexts, participants were presented with a gain-loss gamble that they had to decide to either play or pass. We found that risk preferences for identical sets of gambles were biased by positive and negative contexts containing monetary gains and losses, but not by contexts containing performance feedback. This data suggests that the observed framing effects are driven by aversion for monetary losses and not simply by the positive or negative valence of the context, or by potential moods resulting from positive or negative contexts. These results highlight the specific context dependence of risk preferences.
17. Experience and information loss in auditory and visual memory.
Science.gov (United States)
Gloede, Michele E; Paulauskas, Emily E; Gregg, Melissa K
2017-07-01
Recent studies show that recognition memory for sounds is inferior to memory for pictures. Four experiments were conducted to examine the nature of auditory and visual memory. Experiments 1-3 were conducted to evaluate the role of experience in auditory and visual memory. Participants received a study phase with pictures/sounds, followed by a recognition memory test. Participants then completed auditory training with each of the sounds, followed by a second memory test. Despite auditory training in Experiments 1 and 2, visual memory was superior to auditory memory. In Experiment 3, we found that it is possible to improve auditory memory, but only after 3 days of specific auditory training and 3 days of visual memory decay. We examined the time course of information loss in auditory and visual memory in Experiment 4 and found a trade-off between visual and auditory recognition memory: Visual memory appears to have a larger capacity, while auditory memory is more enduring. Our results indicate that visual and auditory memory are inherently different memory systems and that differences in visual and auditory recognition memory performance may be due to the different amounts of experience with visual and auditory information, as well as structurally different neural circuitry specialized for information retention.
18. Postnatal auditory preferences in piglets differ according to maternal emotional experience with the same sounds during gestation
Science.gov (United States)
Tallet, Céline; Rakotomahandry, Marine; Guérin, Carole; Lemasson, Alban; Hausberger, Martine
2016-01-01
Prenatal sensory experience, notably auditory experience, is a source of fetal memories in many species. The contiguity between sensory stimuli and maternal emotional reactions provides opportunity for associative learning in utero but no clear evidence for this associative learning has been presented to date. Understanding this phenomenon would advance our knowledge of fetal sensory learning capacities. In the present study we tested the hypothesis that sounds (human voice) broadcast to pregnant sows while they experienced positive or negative emotional situations influences postnatal reactions of their offspring to these same sounds. The results show that: 1) from the first testing at the age of 2 days, the experimental piglets were less distressed by a social separation than controls if they heard the “familiar” voice, 2) piglets generalized to any human voice although the influence of novel voices was less pronounced, 3) in a challenging situation, piglets were more distressed if they heard the voice that was associated with maternal negative emotional state in utero. These findings open a whole line of new research on the long term effect of in utero associative learning that goes well beyond pigs, providing a framework for reconsidering the importance of sensory and emotional experiences during gestation. PMID:27857224
19. Differences in Speech Recognition Between Children with Attention Deficits and Typically Developed Children Disappear when Exposed to 65 dB of Auditory Noise
Directory of Open Access Journals (Sweden)
Göran B W Söderlund
2016-01-01
Full Text Available The most common neuropsychiatric condition in the in children is attention deficit hyperactivity disorder (ADHD, affecting approximately 6-9 % of the population. ADHD is distinguished by inattention and hyperactive, impulsive behaviors as well as poor performance in various cognitive tasks often leading to failures at school. Sensory and perceptual dysfunctions have also been noticed. Prior research has mainly focused on limitations in executive functioning where differences are often explained by deficits in pre-frontal cortex activation. Less notice has been given to sensory perception and subcortical functioning in ADHD. Recent research has shown that children with ADHD diagnosis have a deviant auditory brain stem response compared to healthy controls. The aim of the present study was to investigate if the speech recognition threshold differs between attentive and children with ADHD symptoms in two environmental sound conditions, with and without external noise. Previous research has namely shown that children with attention deficits can benefit from white noise exposure during cognitive tasks and here we investigate if noise benefit is present during an auditory perceptual task. For this purpose we used a modified Hagerman’s speech recognition test where children with and without attention deficits performed a binaural speech recognition task to assess the speech recognition threshold in no noise and noise conditions (65 dB. Results showed that the inattentive group displayed a higher speech recognition threshold than typically developed children (TDC and that the difference in speech recognition threshold disappeared when exposed to noise at supra threshold level. From this we conclude that inattention can partly be explained by sensory perceptual limitations that can possibly be ameliorated through noise exposure.
20. Tarefa N-back auditiva: desempenho entre diferentes grupos etários Auditory N-back task: different age groups performance
Directory of Open Access Journals (Sweden)
Tatiana De Nardi
2013-01-01
Full Text Available Um dos instrumentos mais utilizados internacionalmente para avaliação da Memória de Trabalho (MT é a Tarefa N-back Auditiva. Recursos para avaliação desse sistema são escassos no Brasil. O presente estudo objetiva observar o desempenho da Tarefa N-back Auditiva em indivíduos de diferentes faixas etárias: 27 crianças, 22 pré-adolescentes, 26 adultos e 27 idosos. Os resultados mostram que o grupo etário influencia no desempenho da Tarefa N-back Auditiva. A acurácia foi aumentando na transição da infância para a pré-adolescência e seguiu em crescimento até a adultez. Observou-se um declínio no desempenho de idosos. Os dados da Tarefa N-back Auditiva corrobora a trajetória desenvolvimental, sugerindo que essa tarefa possa ser utilizada no contexto experimental. Pesquisas de normatização contribuirão para melhor compreensão dessa tarefa.One of the most internationally used instruments for evaluation of Working Memory (WM is the Auditory N-Back Task. In Brazil, resources to evaluate this system are scarce. The aim of this study is to investigate the performance of different age subjects in auditory n-back tasks. We divided the 102 subjects in four groups: 27 children, 22 adolescents, 26 young adults and 27 older adults. The results demonstrate an age-related difference in the n-back task performance. The accuracy increased in the transition from childhood to adolescence and kept growing from adolescence to adulthood. We also found a decrease in the performance of aged subjects. The Auditory N-Back Task results are in agreement with WM development trajectory, and so, it demonstrates to be an adjusted instrument to evaluate this system in experimental setting.
1. Development of auditory-vocal perceptual skills in songbirds.
Directory of Open Access Journals (Sweden)
Vanessa C Miller-Sims
Full Text Available Songbirds are one of the few groups of animals that learn the sounds used for vocal communication during development. Like humans, songbirds memorize vocal sounds based on auditory experience with vocalizations of adult "tutors", and then use auditory feedback of self-produced vocalizations to gradually match their motor output to the memory of tutor sounds. In humans, investigations of early vocal learning have focused mainly on perceptual skills of infants, whereas studies of songbirds have focused on measures of vocal production. In order to fully exploit songbirds as a model for human speech, understand the neural basis of learned vocal behavior, and investigate links between vocal perception and production, studies of songbirds must examine both behavioral measures of perception and neural measures of discrimination during development. Here we used behavioral and electrophysiological assays of the ability of songbirds to distinguish vocal calls of varying frequencies at different stages of vocal learning. The results show that neural tuning in auditory cortex mirrors behavioral improvements in the ability to make perceptual distinctions of vocal calls as birds are engaged in vocal learning. Thus, separate measures of neural discrimination and behavioral perception yielded highly similar trends during the course of vocal development. The timing of this improvement in the ability to distinguish vocal sounds correlates with our previous work showing substantial refinement of axonal connectivity in cortico-basal ganglia pathways necessary for vocal learning.
2. Development of auditory-vocal perceptual skills in songbirds.
Science.gov (United States)
Miller-Sims, Vanessa C; Bottjer, Sarah W
2012-01-01
Songbirds are one of the few groups of animals that learn the sounds used for vocal communication during development. Like humans, songbirds memorize vocal sounds based on auditory experience with vocalizations of adult "tutors", and then use auditory feedback of self-produced vocalizations to gradually match their motor output to the memory of tutor sounds. In humans, investigations of early vocal learning have focused mainly on perceptual skills of infants, whereas studies of songbirds have focused on measures of vocal production. In order to fully exploit songbirds as a model for human speech, understand the neural basis of learned vocal behavior, and investigate links between vocal perception and production, studies of songbirds must examine both behavioral measures of perception and neural measures of discrimination during development. Here we used behavioral and electrophysiological assays of the ability of songbirds to distinguish vocal calls of varying frequencies at different stages of vocal learning. The results show that neural tuning in auditory cortex mirrors behavioral improvements in the ability to make perceptual distinctions of vocal calls as birds are engaged in vocal learning. Thus, separate measures of neural discrimination and behavioral perception yielded highly similar trends during the course of vocal development. The timing of this improvement in the ability to distinguish vocal sounds correlates with our previous work showing substantial refinement of axonal connectivity in cortico-basal ganglia pathways necessary for vocal learning.
3. High-resolution dynamic atomic force microscopy in liquids with different feedback architectures
Directory of Open Access Journals (Sweden)
John Melcher
2013-02-01
Full Text Available The recent achievement of atomic resolution with dynamic atomic force microscopy (dAFM [Fukuma et al., Appl. Phys. Lett. 2005, 87, 034101], where quality factors of the oscillating probe are inherently low, challenges some accepted beliefs concerning sensitivity and resolution in dAFM imaging modes. Through analysis and experiment we study the performance metrics for high-resolution imaging with dAFM in liquid media with amplitude modulation (AM, frequency modulation (FM and drive-amplitude modulation (DAM imaging modes. We find that while the quality factors of dAFM probes may deviate by several orders of magnitude between vacuum and liquid media, their sensitivity to tip–sample forces can be remarkable similar. Furthermore, the reduction in noncontact forces and quality factors in liquids diminishes the role of feedback control in achieving high-resolution images. The theoretical findings are supported by atomic-resolution images of mica in water acquired with AM, FM and DAM under similar operating conditions.
4. Galactic outflow and diffuse gas properties at z>=1 using different baryonic feedback models
CERN Document Server
Barai, Paramita; Murante, Giuseppe; Ragagnin, Antonio; Viel, Matteo
2014-01-01
We measure and quantify properties of galactic outflows and diffuse gas at $z \\geq 1$ in cosmological hydrodynamical simulations. Our novel sub-resolution model, MUPPI, implements supernova feedback using fully local gas properties, where the wind velocity and mass loading are not given as input. We find the following trends at $z = 2$ by analysing central galaxies having a stellar mass higher than $10^{9} M_{\\odot}$. The outflow velocity and mass outflow rate ($\\dot{M}_{\\rm out}$) exhibit positive correlations with galaxy mass and with the star formation rate (SFR). However, most of the relations present a large scatter. The outflow mass loading factor ($\\eta$) is between $0.2 - 10$. The comparison Effective model generates a constant outflow velocity, and a negative correlation of $\\eta$ with halo mass. The number fraction of galaxies where outflow is detected decreases at lower redshifts, but remains more than $80 \\%$ over $z = 1 - 5$. High SF activity at $z \\sim 2 - 4$ drives strong outflows, causing the ...
5. Radiative feedback and cosmic molecular gas: the role of different radiative sources
Science.gov (United States)
Maio, Umberto; Petkova, Margarita; De Lucia, Gabriella; Borgani, Stefano
2016-08-01
We present results from multifrequency radiative hydrodynamical chemistry simulations addressing primordial star formation and related stellar feedback from various populations of stars, stellar spectral energy distributions (SEDs) and initial mass functions. Spectra for massive stars, intermediate-mass stars and regular solar-like stars are adopted over a grid of 150 frequency bins and consistently coupled with hydrodynamics, heavy-element pollution and non-equilibrium species calculations. Powerful massive Population III stars are found to be able to largely ionize H and, subsequently, He and He+, causing an inversion of the equation of state and a boost of the Jeans masses in the early intergalactic medium. Radiative effects on star formation rates are between a factor of a few and 1 dex, depending on the SED. Radiative processes are responsible for gas heating and photoevaporation, although emission from soft SEDs has minor impacts. These findings have implications for cosmic gas preheating, primordial direct-collapse black holes, the build-up of cosmic fossils' such as low-mass dwarf galaxies, the role of active galactic nuclei during reionization, the early formation of extended discs and angular-momentum catastrophe.
6. Central auditory function of deafness genes.
Science.gov (United States)
Willaredt, Marc A; Ebbers, Lena; Nothwang, Hans Gerd
2014-06-01
The highly variable benefit of hearing devices is a serious challenge in auditory rehabilitation. Various factors contribute to this phenomenon such as the diversity in ear defects, the different extent of auditory nerve hypoplasia, the age of intervention, and cognitive abilities. Recent analyses indicate that, in addition, central auditory functions of deafness genes have to be considered in this context. Since reduced neuronal activity acts as the common denominator in deafness, it is widely assumed that peripheral deafness influences development and function of the central auditory system in a stereotypical manner. However, functional characterization of transgenic mice with mutated deafness genes demonstrated gene-specific abnormalities in the central auditory system as well. A frequent function of deafness genes in the central auditory system is supported by a genome-wide expression study that revealed significant enrichment of these genes in the transcriptome of the auditory brainstem compared to the entire brain. Here, we will summarize current knowledge of the diverse central auditory functions of deafness genes. We furthermore propose the intimately interwoven gene regulatory networks governing development of the otic placode and the hindbrain as a mechanistic explanation for the widespread expression of these genes beyond the cochlea. We conclude that better knowledge of central auditory dysfunction caused by genetic alterations in deafness genes is required. In combination with improved genetic diagnostics becoming currently available through novel sequencing technologies, this information will likely contribute to better outcome prediction of hearing devices.
7. Auditory Imagery: Empirical Findings
Science.gov (United States)
Hubbard, Timothy L.
2010-01-01
The empirical literature on auditory imagery is reviewed. Data on (a) imagery for auditory features (pitch, timbre, loudness), (b) imagery for complex nonverbal auditory stimuli (musical contour, melody, harmony, tempo, notational audiation, environmental sounds), (c) imagery for verbal stimuli (speech, text, in dreams, interior monologue), (d)…
8. A vision-free brain-computer interface (BCI) paradigm based on auditory selective attention.
Science.gov (United States)
Kim, Do-Won; Cho, Jae-Hyun; Hwang, Han-Jeong; Lim, Jeong-Hwan; Im, Chang-Hwan
2011-01-01
Majority of the recently developed brain computer interface (BCI) systems have been using visual stimuli or visual feedbacks. However, the BCI paradigms based on visual perception might not be applicable to severe locked-in patients who have lost their ability to control their eye movement or even their vision. In the present study, we investigated the feasibility of a vision-free BCI paradigm based on auditory selective attention. We used the power difference of auditory steady-state responses (ASSRs) when the participant modulates his/her attention to the target auditory stimulus. The auditory stimuli were constructed as two pure-tone burst trains with different beat frequencies (37 and 43 Hz) which were generated simultaneously from two speakers located at different positions (left and right). Our experimental results showed high classification accuracies (64.67%, 30 commands/min, information transfer rate (ITR) = 1.89 bits/min; 74.00%, 12 commands/min, ITR = 2.08 bits/min; 82.00%, 6 commands/min, ITR = 1.92 bits/min; 84.33%, 3 commands/min, ITR = 1.12 bits/min; without any artifact rejection, inter-trial interval = 6 sec), enough to be used for a binary decision. Based on the suggested paradigm, we implemented a first online ASSR-based BCI system that demonstrated the possibility of materializing a totally vision-free BCI system.
9. The Effect of Six Different Corrective Feedback Strategies on Iranian English Language Learners’ IELTS Writing Task 2
OpenAIRE
Reza Vahdani Sanavi; Majid Nemati
2014-01-01
Scholars have long studied the effect of corrective feedback strategies on the writing ability of language learners, but few have formed designs in which more than three feedback strategies have been used. In this research, the ultimate goal was to discover how International English Language Testing System (IELTS-) candidates could be helped to perform better in the writing component of the test with the feedback they ...
10. Congestion phenomenon analysis and delayed-feedback control in a modified coupled map traffic flow model containing the velocity difference
Science.gov (United States)
Fang, Ya-Ling; Shi, Zhong-Ke; Cao, Jin-Liang
2015-06-01
Based on the coupled map car-following model which was presented by Konishi et al. (1999), a modified coupled map car-following model is proposed. Specifically, the velocity difference between two successive vehicles is included in the model. The stability condition is given for the change of the speed of the preceding vehicle on the base of the control theory. We derive a condition under which the traffic jam never occurs in our model. Furthermore, in order to suppress traffic jams, we use static and dynamic version of decentralized delayed-feedback control for each vehicle, respectively, and provide a systematic procedure for designing the controller. In addition, the controller of each vehicle does not include any other vehicle information in real traffic flows.
11. Targeting treatment-resistant auditory verbal hallucinations in schizophrenia with fMRI-based neurofeedback – exploring different cases of schizophrenia
Directory of Open Access Journals (Sweden)
Miriam S. Dyck
2016-03-01
Full Text Available Auditory verbal hallucinations (AVHs are a hallmark of schizophrenia and can significantly impair patients’ emotional, social, and occupational functioning. Despite progress in psychopharmacology, over 25% of schizophrenia patients suffer from treatment-resistant hallucinations. In the search for alternative treatment methods, neurofeedback (NF emerges as a promising therapy tool. NF based on real-time functional magnetic resonance imaging (rt-fMRI allows voluntarily change of the activity in a selected brain region – even in patients with schizophrenia. This study explored effects of NF on ongoing AVHs. The selected participants were trained in the self-regulation of activity in the anterior cingulate cortex (ACC, a key monitoring region involved in generation and intensity modulation of AVHs. Using rt-fMRI, three right-handed patients, suffering from schizophrenia and ongoing, treatment-resistant AVHs, learned control over ACC activity on three separate days. The effect of NF training on hallucinations’ severity was assessed with the Auditory Vocal Hallucination Rating Scale (AVHRS and on the affective state – with the Positive and Negative Affect Schedule (PANAS.All patients yielded significant up-regulation of the ACC and reported subjective improvement in some aspects of AVHs (AVHRS such as disturbance and suffering from the voices. In general, mood (PANAS improved during NF training, though two patients reported worse mood after NF on the third day. ACC and reward system activity during NF learning and specific effects on mood and symptoms varied across the participants. None of them profited from the last training set in the prolonged 3-session training. Moreover, individual differences emerged in brain networks activated with NF and in symptom changes, which were related to the patients’ symptomatology and disease history.NF based on rt-fMRI seems a promising tool in therapy of AVHs. The patients, who suffered from continuous
12. Targeting Treatment-Resistant Auditory Verbal Hallucinations in Schizophrenia with fMRI-Based Neurofeedback – Exploring Different Cases of Schizophrenia
Science.gov (United States)
Dyck, Miriam S.; Mathiak, Krystyna A.; Bergert, Susanne; Sarkheil, Pegah; Koush, Yury; Alawi, Eliza M.; Zvyagintsev, Mikhail; Gaebler, Arnim J.; Shergill, Sukhi S.; Mathiak, Klaus
2016-01-01
Auditory verbal hallucinations (AVHs) are a hallmark of schizophrenia and can significantly impair patients’ emotional, social, and occupational functioning. Despite progress in psychopharmacology, over 25% of schizophrenia patients suffer from treatment-resistant hallucinations. In the search for alternative treatment methods, neurofeedback (NF) emerges as a promising therapy tool. NF based on real-time functional magnetic resonance imaging (rt-fMRI) allows voluntarily change of the activity in a selected brain region – even in patients with schizophrenia. This study explored effects of NF on ongoing AVHs. The selected participants were trained in the self-regulation of activity in the anterior cingulate cortex (ACC), a key monitoring region involved in generation and intensity modulation of AVHs. Using rt-fMRI, three right-handed patients, suffering from schizophrenia and ongoing, treatment-resistant AVHs, learned control over ACC activity on three separate days. The effect of NF training on hallucinations’ severity was assessed with the Auditory Vocal Hallucination Rating Scale (AVHRS) and on the affective state – with the Positive and Negative Affect Schedule (PANAS). All patients yielded significant upregulation of the ACC and reported subjective improvement in some aspects of AVHs (AVHRS) such as disturbance and suffering from the voices. In general, mood (PANAS) improved during NF training, though two patients reported worse mood after NF on the third day. ACC and reward system activity during NF learning and specific effects on mood and symptoms varied across the participants. None of them profited from the last training set in the prolonged three-session training. Moreover, individual differences emerged in brain networks activated with NF and in symptom changes, which were related to the patients’ symptomatology and disease history. NF based on rt-fMRI seems a promising tool in therapy of AVHs. The patients, who suffered from continuous
13. Neural correlates of short-term memory in primate auditory cortex
Directory of Open Access Journals (Sweden)
James eBigelow
2014-08-01
Full Text Available Behaviorally-relevant sounds such as conspecific vocalizations are often available for only a brief amount of time; thus, goal-directed behavior frequently depends on auditory short-term memory (STM. Despite its ecological significance, the neural processes underlying auditory STM remain poorly understood. To investigate the role of the auditory cortex in STM, single- and multi-unit activity was recorded from the primary auditory cortex (A1 of two monkeys performing an auditory STM task using simple and complex sounds. Each trial consisted of a sample and test stimulus separated by a 5-s retention interval. A brief wait period followed the test stimulus, after which subjects pressed a button if the sounds were identical (match trials or withheld button presses if they were different (nonmatch trials. A number of units exhibited significant changes in firing rate for portions of the retention interval, although these changes were rarely sustained. Instead, they were most frequently observed during the early and late portions of the retention interval, with inhibition being observed more frequently than excitation. At the population level, responses elicited on match trials were briefly suppressed early in the sound period relative to nonmatch trials. However, during the latter portion of the sound, firing rates increased significantly for match trials and remained elevated throughout the wait period. Related patterns of activity were observed in prior experiments from our lab in the dorsal temporal pole (dTP and prefrontal cortex (PFC of the same animals. The data suggest that early match suppression occurs in both A1 and the dTP, whereas later match enhancement occurs first in the PFC, followed by A1 and later in dTP. Because match enhancement occurs first in the PFC, we speculate that enhancement observed in A1 and dTP may reflect top-down feedback. Overall, our findings suggest that A1 forms part of the larger neural system recruited during
14. Supervisor Feedback.
Science.gov (United States)
Hayman, Marilyn J.
1981-01-01
Investigated the effectiveness of supervisor feedback in contributing to learning counseling skills. Counselor trainees (N=64) were assigned to supervisor feedback, no supervisor feedback, or control groups for three training sessions. Results indicated counseling skills were learned best by students with no supervisor feedback but self and peer…
15. Do transformational CEOs always make the difference? The role of TMT feedback seeking behavior
NARCIS (Netherlands)
Stoker, Janka I.; Grutterink, Hanneke; Kolk, Nanja J.
2012-01-01
In the present paper, we raise the question whether CEO transformational leadership invariably makes a difference for team performance and change effectiveness. Since in general, CEOs are surrounded by a team of highly influential top managers, we argue that the effectiveness of CEO transformational
16. Effects of Peer Feedback on ESL Student Writers at Different Levels of English Proficiency: A Japanese Context
Science.gov (United States)
Kamimura, Taeko
2006-01-01
A study was conducted to explore the nature and effectiveness of peer feedback in EFL writing classrooms. High- and low-proficient Japanese EFL learners participated in the study where they exchanged comments with peers after receiving training in peer feedback. The two groups were compared in terms of their pre- and post-tests, original drafts…
17. Sex Differences in Gamma Band Functional Connectivity Between the Frontal Lobe and Cortical Areas During an Auditory Oddball Task, as Revealed by Imaginary Coherence Assessment
Science.gov (United States)
Fujimoto, Toshiro; Okumura, Eiichi; Kodabashi, Atsushi; Takeuchi, Kouzou; Otsubo, Toshiaki; Nakamura, Katsumi; Yatsushiro, Kazutaka; Sekine, Masaki; Kamiya, Shinichiro; Shimooki, Susumu; Tamura, Toshiyo
2016-01-01
We studied sex-related differences in gamma oscillation during an auditory oddball task, using magnetoencephalography and electroencephalography assessment of imaginary coherence (IC). We obtained a statistical source map of event-related desynchronization (ERD) / event-related synchronization (ERS), and compared females and males regarding ERD / ERS. Based on the results, we chose respectively seed regions for IC determinations in low (30-50 Hz), mid (50-100 Hz) and high gamma (100-150 Hz) bands. In males, ERD was increased in the left posterior cingulate cortex (CGp) at 500 ms in the low gamma band, and in the right caudal anterior cingulate cortex (cACC) at 125 ms in the mid-gamma band. ERS was increased in the left rostral anterior cingulate cortex (rACC) at 375 ms in the high gamma band. We chose the CGp, cACC and rACC as seeds, and examined IC between the seed and certain target regions using the IC map. IC changes depended on the height of the gamma frequency and the time window in the gamma band. Although IC in the mid and high gamma bands did not show sex-specific differences, IC at 30-50 Hz in males was increased between the left rACC and the frontal, orbitofrontal, inferior temporal and fusiform target regions. Increased IC in males suggested that males may acomplish the task constructively, analysingly, emotionally, and by perfoming analysis, and that information processing was more complicated in the cortico-cortical circuit. On the other hand, females showed few differences in IC. Females planned the task with general attention and economical well-balanced processing, which was explained by the higher overall functional cortical connectivity. CGp, cACC and rACC were involved in sex differences in information processing and were likely related to differences in neuroanatomy, hormones and neurotransmitter systems. PMID:27708745
18. Feedback and Incentives
DEFF Research Database (Denmark)
Eriksson, Tor Viking; Poulsen, Anders; Villeval, Marie Claire
2009-01-01
This paper experimentally investigates the impact of different pay schemes and relative performance feedback policies on employee effort. We explore three feedback rules: no feedback on relative performance, feedback given halfway through the production period, and continuously updated feedback. We...... use two pay schemes, a piece rate and a tournament. We find that overall feedback does not improve performance. In contrast to the piece-rate pay scheme there is some evidence of positive peer effects in tournaments since the underdogs almost never quit the competition even when lagging significantly...... behind, and front runners do not slack off. But in both pay schemes relative performance feedback reduces the quality of the low performers' work; we refer to this as a "negative quality peer effect"....
19. Understanding visual-auditory correlation from heterogeneous features for cross-media retrieval
Institute of Scientific and Technical Information of China (English)
2008-01-01
Cross-media retrieval is an interesting research topic, which seeks to remove the barriers among different modalities. To enable cross-media retrieval, it is needed to find the correlation measures between heterogeneous low-level features and to judge the semantic similarity. This paper presents a novel approach to learn cross-media correlation between visual features and auditory features for image-audio retrieval. A semi-supervised correlation preserving mapping (SSCPM) method is described to construct the isomorphic SSCPM subspace where canonical correlations between the original visual and auditory features are further preserved. Subspace optimization algorithm is proposed to improve the local image cluster and audio cluster quality in an interactive way. A unique relevance feedback strategy is developed to update the knowledge of cross-media correlation by learning from user behaviors, so retrieval performance is enhanced in a progressive manner. Experimental results show that the performance of our approach is effective.
20. Auditory Evoked Potentials and Hand Preference in 6-Month-Old Infants: Possible Gender-Related Differences in Cerebral Organization.
Science.gov (United States)
Shucard, Janet L.; Shucard, David W.
1990-01-01
Verbal and musical stimuli were presented to infants in a study of the relations of evoked potential left-right amplitude asymmetries to gender and hand preference. There was a relation between asymmetry and hand preference, and for girls, between asymmetry and stimulus condition. Results suggest a gender difference in cerebral hemisphere…
1. Implementation Considerations, Not Topological Differences, Are the Main Determinants of Noise Suppression Properties in Feedback and Incoherent Feedforward Circuits.
Science.gov (United States)
Buzi, Gentian; Khammash, Mustafa
2016-06-01
Biological systems use a variety of mechanisms to deal with the uncertain nature of their external and internal environments. Two of the most common motifs employed for this purpose are the incoherent feedforward (IFF) and feedback (FB) topologies. Many theoretical and experimental studies suggest that these circuits play very different roles in providing robustness to uncertainty in the cellular environment. Here, we use a control theoretic approach to analyze two common FB and IFF architectures that make use of an intermediary species to achieve regulation. We show the equivalence of both circuits topologies in suppressing static cell-to-cell variations. While both circuits can suppress variations due to input noise, they are ineffective in suppressing inherent chemical reaction stochasticity. Indeed, these circuits realize comparable improvements limited to a modest 25% variance reduction in best case scenarios. Such limitations are attributed to the use of intermediary species in regulation, and as such, they persist even for circuit architectures that combine both IFF and FB features. Intriguingly, while the FB circuits are better suited in dealing with dynamic input variability, the most significant difference between the two topologies lies not in the structural features of the circuits, but in their practical implementation considerations.
2. Auditory short-term memory activation during score reading.
Directory of Open Access Journals (Sweden)
Veerle L Simoens
Full Text Available Performing music on the basis of reading a score requires reading ahead of what is being played in order to anticipate the necessary actions to produce the notes. Score reading thus not only involves the decoding of a visual score and the comparison to the auditory feedback, but also short-term storage of the musical information due to the delay of the auditory feedback during reading ahead. This study investigates the mechanisms of encoding of musical information in short-term memory during such a complicated procedure. There were three parts in this study. First, professional musicians participated in an electroencephalographic (EEG experiment to study the slow wave potentials during a time interval of short-term memory storage in a situation that requires cross-modal translation and short-term storage of visual material to be compared with delayed auditory material, as it is the case in music score reading. This delayed visual-to-auditory matching task was compared with delayed visual-visual and auditory-auditory matching tasks in terms of EEG topography and voltage amplitudes. Second, an additional behavioural experiment was performed to determine which type of distractor would be the most interfering with the score reading-like task. Third, the self-reported strategies of the participants were also analyzed. All three parts of this study point towards the same conclusion according to which during music score reading, the musician most likely first translates the visual score into an auditory cue, probably starting around 700 or 1300 ms, ready for storage and delayed comparison with the auditory feedback.
3. Motor Training: Comparison of Visual and Auditory Coded Proprioceptive Cues
Directory of Open Access Journals (Sweden)
Philip Jepson
2012-05-01
Full Text Available Self-perception of body posture and movement is achieved through multi-sensory integration, particularly the utilisation of vision, and proprioceptive information derived from muscles and joints. Disruption to these processes can occur following a neurological accident, such as stroke, leading to sensory and physical impairment. Rehabilitation can be helped through use of augmented visual and auditory biofeedback to stimulate neuro-plasticity, but the effective design and application of feedback, particularly in the auditory domain, is non-trivial. Simple auditory feedback was tested by comparing the stepping accuracy of normal subjects when given a visual spatial target (step length and an auditory temporal target (step duration. A baseline measurement of step length and duration was taken using optical motion capture. Subjects (n=20 took 20 ‘training’ steps (baseline ±25% using either an auditory target (950 Hz tone, bell-shaped gain envelope or visual target (spot marked on the floor and were then asked to replicate the target step (length or duration corresponding to training with all feedback removed. Visual cues (mean percentage error=11.5%; SD ± 7.0%; auditory cues (mean percentage error = 12.9%; SD ± 11.8%. Visual cues elicit a high degree of accuracy both in training and follow-up un-cued tasks; despite the novelty of the auditory cues present for subjects, the mean accuracy of subjects approached that for visual cues, and initial results suggest a limited amount of practice using auditory cues can improve performance.
4. Neural cryptography with feedback.
Science.gov (United States)
Ruttor, Andreas; Kinzel, Wolfgang; Shacham, Lanir; Kanter, Ido
2004-04-01
Neural cryptography is based on a competition between attractive and repulsive stochastic forces. A feedback mechanism is added to neural cryptography which increases the repulsive forces. Using numerical simulations and an analytic approach, the probability of a successful attack is calculated for different model parameters. Scaling laws are derived which show that feedback improves the security of the system. In addition, a network with feedback generates a pseudorandom bit sequence which can be used to encrypt and decrypt a secret message.
5. Integrating temporal difference methods and self-organizing neural networks for reinforcement learning with delayed evaluative feedback.
Science.gov (United States)
Tan, A H; Lu, N; Xiao, D
2008-02-01
This paper presents a neural architecture for learning category nodes encoding mappings across multimodal patterns involving sensory inputs, actions, and rewards. By integrating adaptive resonance theory (ART) and temporal difference (TD) methods, the proposed neural model, called TD fusion architecture for learning, cognition, and navigation (TD-FALCON), enables an autonomous agent to adapt and function in a dynamic environment with immediate as well as delayed evaluative feedback (reinforcement) signals. TD-FALCON learns the value functions of the state-action space estimated through on-policy and off-policy TD learning methods, specifically state-action-reward-state-action (SARSA) and Q-learning. The learned value functions are then used to determine the optimal actions based on an action selection policy. We have developed TD-FALCON systems using various TD learning strategies and compared their performance in terms of task completion, learning speed, as well as time and space efficiency. Experiments based on a minefield navigation task have shown that TD-FALCON systems are able to learn effectively with both immediate and delayed reinforcement and achieve a stable performance in a pace much faster than those of standard gradient-descent-based reinforcement learning systems.
6. Investigating the role of auditory and tactile modalities in violin quality evaluation.
Directory of Open Access Journals (Sweden)
Indiana Wollman
Full Text Available The role of auditory and tactile modalities involved in violin playing and evaluation was investigated in an experiment employing a blind violin evaluation task under different conditions: i normal playing conditions, ii playing with auditory masking, and iii playing with vibrotactile masking. Under each condition, 20 violinists evaluated five violins according to criteria related to violin playing and sound characteristics and rated their overall quality and relative preference. Results show that both auditory and vibrotactile feedback are important in the violinists' evaluations but that their relative importance depends on the violinist, the violin and the type of evaluation (different criteria ratings or preference. In this way, the overall quality ratings were found to be accurately predicted by the rating criteria, which also proved to be perceptually relevant to violinists, but were poorly correlated with the preference ratings; this suggests that the two types of ratings (overall quality vs preference may stem from different decision-making strategies. Furthermore, the experimental design confirmed that violinists agree more on the importance of criteria in their overall evaluation than on their actual ratings for different violins. In particular, greater agreement was found on the importance of criteria related to the sound of the violin. Nevertheless, this study reveals that there are fundamental differences in the way players interpret and evaluate each criterion, which may explain why correlating physical properties with perceptual properties has been challenging so far in the field of musical acoustics.
7. Investigating the role of auditory and tactile modalities in violin quality evaluation.
Science.gov (United States)
Wollman, Indiana; Fritz, Claudia; Poitevineau, Jacques; McAdams, Stephen
2014-01-01
The role of auditory and tactile modalities involved in violin playing and evaluation was investigated in an experiment employing a blind violin evaluation task under different conditions: i) normal playing conditions, ii) playing with auditory masking, and iii) playing with vibrotactile masking. Under each condition, 20 violinists evaluated five violins according to criteria related to violin playing and sound characteristics and rated their overall quality and relative preference. Results show that both auditory and vibrotactile feedback are important in the violinists' evaluations but that their relative importance depends on the violinist, the violin and the type of evaluation (different criteria ratings or preference). In this way, the overall quality ratings were found to be accurately predicted by the rating criteria, which also proved to be perceptually relevant to violinists, but were poorly correlated with the preference ratings; this suggests that the two types of ratings (overall quality vs preference) may stem from different decision-making strategies. Furthermore, the experimental design confirmed that violinists agree more on the importance of criteria in their overall evaluation than on their actual ratings for different violins. In particular, greater agreement was found on the importance of criteria related to the sound of the violin. Nevertheless, this study reveals that there are fundamental differences in the way players interpret and evaluate each criterion, which may explain why correlating physical properties with perceptual properties has been challenging so far in the field of musical acoustics.
8. Differences between Dyslexic and Non-Dyslexic Children in the Performance of Phonological Visual-Auditory Recognition Tasks: An Eye-Tracking Study.
Directory of Open Access Journals (Sweden)
Full Text Available The object of this study was to explore further phonological visual-auditory recognition tasks in a group of fifty-six healthy children (mean age: 9.9 ± 0.3 and to compare these data to those recorded in twenty-six age-matched dyslexic children (mean age: 9.8 ± 0.2. Eye movements from both eyes were recorded using an infrared video-oculography system (MobileEBT® e(ye BRAIN. The recognition task was performed under four conditions in which the target object was displayed either with phonologically unrelated objects (baseline condition, or with cohort or rhyme objects (cohort and rhyme conditions, respectively, or both together (rhyme + cohort condition. The percentage of the total time spent on the targets and the latency of the first saccade on the target were measured. Results in healthy children showed that the percentage of the total time spent in the baseline condition was significantly longer than in the other conditions, and that the latency of the first saccade in the cohort condition was significantly longer than in the other conditions; interestingly, the latency decreased significantly with the increasing age of the children. The developmental trend of phonological awareness was also observed in healthy children only. In contrast, we observed that for dyslexic children the total time spent on the target was similar in all four conditions tested, and also that they had similar latency values in both cohort and rhyme conditions. These findings suggest a different sensitivity to the phonological competitors between dyslexic and non-dyslexic children. Also, the eye-tracking technique provides online information about phonological awareness capabilities in children.
9. Role of the auditory system in speech production.
Science.gov (United States)
Guenther, Frank H; Hickok, Gregory
2015-01-01
This chapter reviews evidence regarding the role of auditory perception in shaping speech output. Evidence indicates that speech movements are planned to follow auditory trajectories. This in turn is followed by a description of the Directions Into Velocities of Articulators (DIVA) model, which provides a detailed account of the role of auditory feedback in speech motor development and control. A brief description of the higher-order brain areas involved in speech sequencing (including the pre-supplementary motor area and inferior frontal sulcus) is then provided, followed by a description of the Hierarchical State Feedback Control (HSFC) model, which posits internal error detection and correction processes that can detect and correct speech production errors prior to articulation. The chapter closes with a treatment of promising future directions of research into auditory-motor interactions in speech, including the use of intracranial recording techniques such as electrocorticography in humans, the investigation of the potential roles of various large-scale brain rhythms in speech perception and production, and the development of brain-computer interfaces that use auditory feedback to allow profoundly paralyzed users to learn to produce speech using a speech synthesizer.
10. Efficiency of visual feedback integration differs between dominant and non-dominant arms during a reaching task.
Science.gov (United States)
Apker, Gregory A; Dyson, Keith; Frantz, Garrett; Buneo, Christopher A
2015-01-01
Recent studies have shown that patterns of endpoint variability following double-step reach sequences reflect the influence of both planning and execution-related processes, but are strongly dominated by noise associated with the online updating of movement plans based on visual feedback. However, it is currently unclear whether these results reflect the dominant arm/hemisphere's postulated specialization for visual feedback processing, or whether these effects reflect a more general "arm/hemisphere independent" preference for visual feedback in the control of reaching. To explore this, twelve subjects performed double-step reach sequences with their dominant and non-dominant arms to targets in 3D space with and without visual feedback of the arm. Variability was quantified using the volumes, aspect ratios, and orientations of 95% confidence ellipsoids fit to the distributions of reach endpoints. In consonance with previous findings, the availability of visual feedback resulted in ellipsoids that were significantly smaller, had greater aspect ratios, and were more aligned with the depth axis than those performed without visual feedback. Moreover, the effects of vision on aspect ratio and orientation were similar in magnitude for the dominant and non-dominant arms, suggesting that noise associated with planning and execution-related processes is managed in a similar way by the sensorimotor systems of each arm. However, the degree to which vision decreased ellipsoid volume was found to be significantly greater for the dominant arm. This suggests that the feedback control system of the dominant arm uses visual information more efficiently to control reaches to visual targets.
11. Development of kinesthetic-motor and auditory-motor representations in school-aged children.
Science.gov (United States)
Kagerer, Florian A; Clark, Jane E
2015-07-01
In two experiments using a center-out task, we investigated kinesthetic-motor and auditory-motor integrations in 5- to 12-year-old children and young adults. In experiment 1, participants moved a pen on a digitizing tablet from a starting position to one of three targets (visuo-motor condition), and then to one of four targets without visual feedback of the movement. In both conditions, we found that with increasing age, the children moved faster and straighter, and became less variable in their feedforward control. Higher control demands for movements toward the contralateral side were reflected in longer movement times and decreased spatial accuracy across all age groups. When feedforward control relies predominantly on kinesthesia, 7- to 10-year-old children were more variable, indicating difficulties in switching between feedforward and feedback control efficiently during that age. An inverse age progression was found for directional endpoint error; larger errors increasing with age likely reflect stronger functional lateralization for the dominant hand. In experiment 2, the same visuo-motor condition was followed by an auditory-motor condition in which participants had to move to acoustic targets (either white band or one-third octave noise). Since in the latter directional cues come exclusively from transcallosally mediated interaural time differences, we hypothesized that auditory-motor representations would show age effects. The results did not show a clear age effect, suggesting that corpus callosum functionality is sufficient in children to allow them to form accurate auditory-motor maps already at a young age.
12. Impairments of auditory scene analysis in Alzheimer's disease.
Science.gov (United States)
Goll, Johanna C; Kim, Lois G; Ridgway, Gerard R; Hailstone, Julia C; Lehmann, Manja; Buckley, Aisling H; Crutch, Sebastian J; Warren, Jason D
2012-01-01
Parsing of sound sources in the auditory environment or 'auditory scene analysis' is a computationally demanding cognitive operation that is likely to be vulnerable to the neurodegenerative process in Alzheimer's disease. However, little information is available concerning auditory scene analysis in Alzheimer's disease. Here we undertook a detailed neuropsychological and neuroanatomical characterization of auditory scene analysis in a cohort of 21 patients with clinically typical Alzheimer's disease versus age-matched healthy control subjects. We designed a novel auditory dual stream paradigm based on synthetic sound sequences to assess two key generic operations in auditory scene analysis (object segregation and grouping) in relation to simpler auditory perceptual, task and general neuropsychological factors. In order to assess neuroanatomical associations of performance on auditory scene analysis tasks, structural brain magnetic resonance imaging data from the patient cohort were analysed using voxel-based morphometry. Compared with healthy controls, patients with Alzheimer's disease had impairments of auditory scene analysis, and segregation and grouping operations were comparably affected. Auditory scene analysis impairments in Alzheimer's disease were not wholly attributable to simple auditory perceptual or task factors; however, the between-group difference relative to healthy controls was attenuated after accounting for non-verbal (visuospatial) working memory capacity. These findings demonstrate that clinically typical Alzheimer's disease is associated with a generic deficit of auditory scene analysis. Neuroanatomical associations of auditory scene analysis performance were identified in posterior cortical areas including the posterior superior temporal lobes and posterior cingulate. This work suggests a basis for understanding a class of clinical symptoms in Alzheimer's disease and for delineating cognitive mechanisms that mediate auditory scene analysis
13. "Feedback" For Instructioal Television.
Science.gov (United States)
Schramm, Wilbur
A number of different methods have been used by instructional television (ITV) projects to obtain audience feedback, and some of these are now being used in the ITV system in El Salvador. We know that pretesting programs on a representative sample can bring considerable gains in learning. Another feedback source can be a classroom of pupils in the…
14. Tuning up the developing auditory CNS.
Science.gov (United States)
Sanes, Dan H; Bao, Shaowen
2009-04-01
Although the auditory system has limited information processing resources, the acoustic environment is infinitely variable. To properly encode the natural environment, the developing central auditory system becomes somewhat specialized through experience-dependent adaptive mechanisms that operate during a sensitive time window. Recent studies have demonstrated that cellular and synaptic plasticity occurs throughout the central auditory pathway. Acoustic-rearing experiments can lead to an over-representation of the exposed sound frequency, and this is associated with specific changes in frequency discrimination. These forms of cellular plasticity are manifest in brain regions, such as midbrain and cortex, which interact through feed-forward and feedback pathways. Hearing loss leads to a profound re-weighting of excitatory and inhibitory synaptic gain throughout the auditory CNS, and this is associated with an over-excitability that is observed in vivo. Further behavioral and computational analyses may provide insights into how theses cellular and systems plasticity effects underlie the development of cognitive functions such as speech perception.
15. Distribution of input and output synapses on the central branches of bushcricket and cricket auditory afferent neurones: immunocytochemical evidence for GABA and glutamate in different populations of presynaptic boutons.
Science.gov (United States)
Hardt, M; Watson, A H
1999-01-18
In order to investigate the synapses on the terminals of primary auditory afferents in the bushcricket and cricket, these were impaled with microelectrodes and after physiological characterisation, injected intracellularly with horseradish peroxidase. The tissue was prepared for electron microscopy, and immunocytochemistry for gamma-aminobutyric acid (GABA) and glutamate was carried out on ultrathin sections by using a post-embedding immunogold technique. The afferent terminals received many input synapses. Between 60-65% of these were made by processes immunoreactive for GABA and approximately 25% from processes immunoreactive for glutamate. The relative distribution of the different classes of input were analysed from serial section reconstruction of terminal afferent branches. Inputs from GABA and glutamate-immunoreactive processes appeared to be scattered at random over the terminal arborisation of the afferents both with respect to each other and to the architecture of the terminals. They were, however, always found close to the output synapses. The possible roles of presynaptic inhibition in the auditory afferents is discussed in the context of the auditory responses of the animals.
16. Translation and adaptation of functional auditory performance indicators (FAPI
Directory of Open Access Journals (Sweden)
Karina Ferreira
2011-12-01
Full Text Available Work with deaf children has gained new attention since the expectation and goal of therapy has expanded to language development and subsequent language learning. Many clinical tests were developed for evaluation of speech sound perception in young children in response to the need for accurate assessment of hearing skills that developed from the use of individual hearing aids or cochlear implants. These tests also allow the evaluation of the rehabilitation program. However, few of these tests are available in Portuguese. Evaluation with the Functional Auditory Performance Indicators (FAPI generates a child's functional auditory skills profile, which lists auditory skills in an integrated and hierarchical order. It has seven hierarchical categories, including sound awareness, meaningful sound, auditory feedback, sound source localizing, auditory discrimination, short-term auditory memory, and linguistic auditory processing. FAPI evaluation allows the therapist to map the child's hearing profile performance, determine the target for increasing the hearing abilities, and develop an effective therapeutic plan. Objective: Since the FAPI is an American test, the inventory was adapted for application in the Brazilian population. Material and Methods: The translation was done following the steps of translation and back translation, and reproducibility was evaluated. Four translated versions (two originals and two back-translated were compared, and revisions were done to ensure language adaptation and grammatical and idiomatic equivalence. Results: The inventory was duly translated and adapted. Conclusion: Further studies about the application of the translated FAPI are necessary to make the test practicable in Brazilian clinical use.
17. Speech Evoked Auditory Brainstem Response in Stuttering
Directory of Open Access Journals (Sweden)
Ali Akbar Tahaei
2014-01-01
Full Text Available Auditory processing deficits have been hypothesized as an underlying mechanism for stuttering. Previous studies have demonstrated abnormal responses in subjects with persistent developmental stuttering (PDS at the higher level of the central auditory system using speech stimuli. Recently, the potential usefulness of speech evoked auditory brainstem responses in central auditory processing disorders has been emphasized. The current study used the speech evoked ABR to investigate the hypothesis that subjects with PDS have specific auditory perceptual dysfunction. Objectives. To determine whether brainstem responses to speech stimuli differ between PDS subjects and normal fluent speakers. Methods. Twenty-five subjects with PDS participated in this study. The speech-ABRs were elicited by the 5-formant synthesized syllable/da/, with duration of 40 ms. Results. There were significant group differences for the onset and offset transient peaks. Subjects with PDS had longer latencies for the onset and offset peaks relative to the control group. Conclusions. Subjects with PDS showed a deficient neural timing in the early stages of the auditory pathway consistent with temporal processing deficits and their abnormal timing may underlie to their disfluency.
18. The auditory brainstem is a barometer of rapid auditory learning.
Science.gov (United States)
Skoe, E; Krizman, J; Spitzer, E; Kraus, N
2013-07-23
To capture patterns in the environment, neurons in the auditory brainstem rapidly alter their firing based on the statistical properties of the soundscape. How this neural sensitivity relates to behavior is unclear. We tackled this question by combining neural and behavioral measures of statistical learning, a general-purpose learning mechanism governing many complex behaviors including language acquisition. We recorded complex auditory brainstem responses (cABRs) while human adults implicitly learned to segment patterns embedded in an uninterrupted sound sequence based on their statistical characteristics. The brainstem's sensitivity to statistical structure was measured as the change in the cABR between a patterned and a pseudo-randomized sequence composed from the same set of sounds but differing in their sound-to-sound probabilities. Using this methodology, we provide the first demonstration that behavioral-indices of rapid learning relate to individual differences in brainstem physiology. We found that neural sensitivity to statistical structure manifested along a continuum, from adaptation to enhancement, where cABR enhancement (patterned>pseudo-random) tracked with greater rapid statistical learning than adaptation. Short- and long-term auditory experiences (days to years) are known to promote brainstem plasticity and here we provide a conceptual advance by showing that the brainstem is also integral to rapid learning occurring over minutes.
19. Subdivisions of the auditory midbrain (n. mesencephalicus lateralis, pars dorsalis in zebra finches using calcium-binding protein immunocytochemistry.
Directory of Open Access Journals (Sweden)
Priscilla Logerot
Full Text Available The midbrain nucleus mesencephalicus lateralis pars dorsalis (MLd is thought to be the avian homologue of the central nucleus of the mammalian inferior colliculus. As such, it is a major relay in the ascending auditory pathway of all birds and in songbirds mediates the auditory feedback necessary for the learning and maintenance of song. To clarify the organization of MLd, we applied three calcium binding protein antibodies to tissue sections from the brains of adult male and female zebra finches. The staining patterns resulting from the application of parvalbumin, calbindin and calretinin antibodies differed from each other and in different parts of the nucleus. Parvalbumin-like immunoreactivity was distributed throughout the whole nucleus, as defined by the totality of the terminations of brainstem auditory afferents; in other words parvalbumin-like immunoreactivity defines the boundaries of MLd. Staining patterns of parvalbumin, calbindin and calretinin defined two regions of MLd: inner (MLd.I and outer (MLd.O. MLd.O largely surrounds MLd.I and is distinct from the surrounding intercollicular nucleus. Unlike the case in some non-songbirds, however, the two MLd regions do not correspond to the terminal zones of the projections of the brainstem auditory nuclei angularis and laminaris, which have been found to overlap substantially throughout the nucleus in zebra finches.
20. Auditory evoked potentials in peripheral vestibular disorder individuals
Directory of Open Access Journals (Sweden)
Matas, Carla Gentile
2011-07-01
Full Text Available Introduction: The auditory and vestibular systems are located in the same peripheral receptor, however they enter the CNS and go through different ways, thus creating a number of connections and reaching a wide area of the encephalon. Despite going through different ways, some changes can impair both systems. Such tests as Auditory Evoked Potentials can help find a diagnosis when vestibular alterations are seen. Objective: describe the Auditory Evoked Potential results in individuals complaining about dizziness or vertigo with Peripheral Vestibular Disorders and in normal individuals having the same complaint. Methods: Short, middle and long latency Auditory Evoked Potentials were performed as a transversal prospective study. Conclusion: individuals complaining about dizziness or vertigo can show some changes in BAEP (Brainstem Auditory Evoked Potential, MLAEP (Medium Latency Auditory Evoked Potential and P300.
1. A trade-off between somatosensory and auditory related brain activity during object naming but not reading.
Science.gov (United States)
Seghier, Mohamed L; Hope, Thomas M H; Prejawa, Susan; Parker Jones, 'Ōiwi; Vitkovitch, Melanie; Price, Cathy J
2015-03-18
The parietal operculum, particularly the cytoarchitectonic area OP1 of the secondary somatosensory area (SII), is involved in somatosensory feedback. Using fMRI with 58 human subjects, we investigated task-dependent differences in SII/OP1 activity during three familiar speech production tasks: object naming, reading and repeatedly saying "1-2-3." Bilateral SII/OP1 was significantly suppressed (relative to rest) during object naming, to a lesser extent when repeatedly saying "1-2-3" and not at all during reading. These results cannot be explained by task difficulty but the contrasting difference between naming and reading illustrates how the demands on somatosensory activity change with task, even when motor output (i.e., production of object names) is matched. To investigate what determined SII/OP1 deactivation during object naming, we searched the whole brain for areas where activity increased as that in SII/OP1 decreased. This across subject covariance analysis revealed a region in the right superior temporal sulcus (STS) that lies within the auditory cortex, and is activated by auditory feedback during speech production. The tradeoff between activity in SII/OP1 and STS was not observed during reading, which showed significantly more activation than naming in both SII/OP1 and STS bilaterally. These findings suggest that, although object naming is more error prone than reading, subjects can afford to rely more or less on somatosensory or auditory feedback during naming. In contrast, fast and efficient error-free reading places more consistent demands on both types of feedback, perhaps because of the potential for increased competition between lexical and sublexical codes at the articulatory level.
2. Contextual modulation of primary visual cortex by auditory signals
Science.gov (United States)
Paton, A. T.
2017-01-01
Early visual cortex receives non-feedforward input from lateral and top-down connections (Muckli & Petro 2013 Curr. Opin. Neurobiol. 23, 195–201. (doi:10.1016/j.conb.2013.01.020)), including long-range projections from auditory areas. Early visual cortex can code for high-level auditory information, with neural patterns representing natural sound stimulation (Vetter et al. 2014 Curr. Biol. 24, 1256–1262. (doi:10.1016/j.cub.2014.04.020)). We discuss a number of questions arising from these findings. What is the adaptive function of bimodal representations in visual cortex? What type of information projects from auditory to visual cortex? What are the anatomical constraints of auditory information in V1, for example, periphery versus fovea, superficial versus deep cortical layers? Is there a putative neural mechanism we can infer from human neuroimaging data and recent theoretical accounts of cortex? We also present data showing we can read out high-level auditory information from the activation patterns of early visual cortex even when visual cortex receives simple visual stimulation, suggesting independent channels for visual and auditory signals in V1. We speculate which cellular mechanisms allow V1 to be contextually modulated by auditory input to facilitate perception, cognition and behaviour. Beyond cortical feedback that facilitates perception, we argue that there is also feedback serving counterfactual processing during imagery, dreaming and mind wandering, which is not relevant for immediate perception but for behaviour and cognition over a longer time frame. This article is part of the themed issue ‘Auditory and visual scene analysis’. PMID:28044015
3. The plastic ear and perceptual relearning in auditory spatial perception.
Science.gov (United States)
Carlile, Simon
2014-01-01
The auditory system of adult listeners has been shown to accommodate to altered spectral cues to sound location which presumably provides the basis for recalibration to changes in the shape of the ear over a life time. Here we review the role of auditory and non-auditory inputs to the perception of sound location and consider a range of recent experiments looking at the role of non-auditory inputs in the process of accommodation to these altered spectral cues. A number of studies have used small ear molds to modify the spectral cues that result in significant degradation in localization performance. Following chronic exposure (10-60 days) performance recovers to some extent and recent work has demonstrated that this occurs for both audio-visual and audio-only regions of space. This begs the questions as to the teacher signal for this remarkable functional plasticity in the adult nervous system. Following a brief review of influence of the motor state in auditory localization, we consider the potential role of auditory-motor learning in the perceptual recalibration of the spectral cues. Several recent studies have considered how multi-modal and sensory-motor feedback might influence accommodation to altered spectral cues produced by ear molds or through virtual auditory space stimulation using non-individualized spectral cues. The work with ear molds demonstrates that a relatively short period of training involving audio-motor feedback (5-10 days) significantly improved both the rate and extent of accommodation to altered spectral cues. This has significant implications not only for the mechanisms by which this complex sensory information is encoded to provide spatial cues but also for adaptive training to altered auditory inputs. The review concludes by considering the implications for rehabilitative training with hearing aids and cochlear prosthesis.
4. Contextual modulation of primary visual cortex by auditory signals.
Science.gov (United States)
Petro, L S; Paton, A T; Muckli, L
2017-02-19
Early visual cortex receives non-feedforward input from lateral and top-down connections (Muckli & Petro 2013 Curr. Opin. Neurobiol. 23, 195-201. (doi:10.1016/j.conb.2013.01.020)), including long-range projections from auditory areas. Early visual cortex can code for high-level auditory information, with neural patterns representing natural sound stimulation (Vetter et al. 2014 Curr. Biol. 24, 1256-1262. (doi:10.1016/j.cub.2014.04.020)). We discuss a number of questions arising from these findings. What is the adaptive function of bimodal representations in visual cortex? What type of information projects from auditory to visual cortex? What are the anatomical constraints of auditory information in V1, for example, periphery versus fovea, superficial versus deep cortical layers? Is there a putative neural mechanism we can infer from human neuroimaging data and recent theoretical accounts of cortex? We also present data showing we can read out high-level auditory information from the activation patterns of early visual cortex even when visual cortex receives simple visual stimulation, suggesting independent channels for visual and auditory signals in V1. We speculate which cellular mechanisms allow V1 to be contextually modulated by auditory input to facilitate perception, cognition and behaviour. Beyond cortical feedback that facilitates perception, we argue that there is also feedback serving counterfactual processing during imagery, dreaming and mind wandering, which is not relevant for immediate perception but for behaviour and cognition over a longer time frame.This article is part of the themed issue 'Auditory and visual scene analysis'.
5. The plastic ear and perceptual relearning in auditory spatial perception.
Directory of Open Access Journals (Sweden)
Simon eCarlile
2014-08-01
Full Text Available The auditory system of adult listeners has been shown to accommodate to altered spectral cues to sound location which presumably provides the basis for recalibration to changes in the shape of the ear over a life time. Here we review the role of auditory and non-auditory inputs to the perception of sound location and consider a range of recent experiments looking at the role of non-auditory inputs in the process of accommodation to these altered spectral cues. A number of studies have used small ear moulds to modify the spectral cues that result in significant degradation in localization performance. Following chronic exposure (10-60 days performance recovers to some extent and recent work has demonstrated that this occurs for both audio-visual and audio-only regions of space. This begs the questions as to the teacher signal for this remarkable functional plasticity in the adult nervous system. Following a brief review of influence of the motor state in auditory localisation, we consider the potential role of auditory-motor learning in the perceptual recalibration of the spectral cues. Several recent studies have considered how multi-modal and sensory-motor feedback might influence accommodation to altered spectral cues produced by ear moulds or through virtual auditory space stimulation using non-individualised spectral cues. The work with ear moulds demonstrates that a relatively short period of training involving sensory-motor feedback (5 – 10 days significantly improved both the rate and extent of accommodation to altered spectral cues. This has significant implications not only for the mechanisms by which this complex sensory information is encoded to provide a spatial code but also for adaptive training to altered auditory inputs. The review concludes by considering the implications for rehabilitative training with hearing aids and cochlear prosthesis.
6. Auditory Integration Training
Directory of Open Access Journals (Sweden)
Zahra Jafari
2002-07-01
Full Text Available Auditory integration training (AIT is a hearing enhancement training process for sensory input anomalies found in individuals with autism, attention deficit hyperactive disorder, dyslexia, hyperactivity, learning disability, language impairments, pervasive developmental disorder, central auditory processing disorder, attention deficit disorder, depressin, and hyperacute hearing. AIT, recently introduced in the United States, and has received much notice of late following the release of The Sound of a Moracle, by Annabel Stehli. In her book, Mrs. Stehli describes before and after auditory integration training experiences with her daughter, who was diagnosed at age four as having autism.
7. Frequency tuning of individual auditory receptors in female mosquitoes (Diptera, Culicidae).
Science.gov (United States)
Lapshin, D N; Vorontsov, D D
2013-08-01
The acoustic sensory organs in mosquitoes (Johnston organs) have been thoroughly studied; yet, to date, no data are available on the individual tuning properties of the numerous receptors that convert sound-induced vibrations into electrical signals. All previous measurements of frequency tuning in mosquitoes have been based on the acoustically evoked field potentials recorded from the entire Johnston organ. Here, we present evidence that individual receptors have various frequency tunings and that differently tuned receptors are unequally represented within the Johnston organ. We devised a positive feedback stimulation paradigm as a new and effective approach to test individual receptor properties. Alongside the glass microelectrode technique, the positive feedback stimulation paradigm has allowed us to obtain data on receptor tuning in females from three mosquito species: Anopheles messeae, Aedes excrucians and Culex pipiens pipiens. The existence of individually tuned auditory receptors implies that frequency analysis in mosquitoes may be possible.
8. Auditory Responses of Infants
Science.gov (United States)
Watrous, Betty Springer; And Others
1975-01-01
Forty infants, 3- to 12-months-old, participated in a study designed to differentiate the auditory response characteristics of normally developing infants in the age ranges 3 - 5 months, 6 - 8 months, and 9 - 12 months. (Author)
9. Organization of the auditory brainstem in a lizard, Gekko gecko. I. Auditory nerve, cochlear nuclei, and superior olivary nuclei
DEFF Research Database (Denmark)
Tang, Y. Z.; Christensen-Dalsgaard, J.; Carr, C. E.
2012-01-01
We used tract tracing to reveal the connections of the auditory brainstem in the Tokay gecko (Gekko gecko). The auditory nerve has two divisions, a rostroventrally directed projection of mid- to high best-frequency fibers to the nucleus angularis (NA) and a more dorsal and caudal projection of lo...... of auditory connections in lizards and archosaurs but also different processing of low- and high-frequency information in the brainstem. J. Comp. Neurol. 520:17841799, 2012. (C) 2011 Wiley Periodicals, Inc...
10. Formativ Feedback
DEFF Research Database (Denmark)
Hyldahl, Kirsten Kofod
Denne bog undersøger, hvordan lærere kan anvende feedback til at forbedre undervisningen i klasselokalet. I denne sammenhæng har John Hattie, professor ved Melbourne Universitet, udviklet en model for feedback, hvilken er baseret på synteser af meta-analyser. I 2009 udgav han bogen "Visible...
11. Proximity effect on hydrodynamic interaction between a sphere and a plane measured by force feedback microscopy at different frequencies
Science.gov (United States)
Carpentier, Simon; Rodrigues, Mario S.; Charlaix, Elisabeth; Chevrier, Joël
2015-07-01
In this article, we measure the viscous damping G″, and the associated stiffness G', of a liquid flow in sphere-plane geometry over a large frequency range. In this regime, the lubrication approximation is expected to dominate. We first measure the static force applied to the tip. This is made possible thanks to a force feedback method. Adding a sub-nanometer oscillation of the tip, we obtain the dynamic part of the interaction with solely the knowledge of the lever properties in the experimental context using a linear transformation of the amplitude and phase change. Using a Force Feedback Microscope (FFM), we are then able to measure simultaneously the static force, the stiffness, and the dissipative part of the interaction in a broad frequency range using a single AFM probe. Similar measurements have been performed by the Surface Force Apparatus (SFA) with a probe radius hundred times bigger. In this context, the FFM can be called nano-SFA.
12. Proximity effect on hydrodynamic interaction between a sphere and a plane measured by Force Feedback Microscopy at different frequencies
CERN Document Server
Carpentier, Simon; Charlaix, Elisabeth; Chevrier, Joel
2015-01-01
In this article, we measure the viscous damping $G'',$ and the associated stiffness $G',$ of a liquid flow in sphere-plane geometry in a large frequency range. In this regime, the lubrication approximation is expected to dominate. We first measure the static force applied to the tip. This is made possible thanks to a force feedback method. Adding a sub-nanometer oscillation of the tip, we obtain the dynamic part of the interaction with solely the knowledge of the lever properties in the experimental context using a linear transformation of the amplitude and phase change. Using a Force Feedback Microscope (FFM)we are then able to measure simultaneously the static force, the stiffness and the dissipative part of the interaction in a broad frequency range using a single AFM probe. Similar measurements have been performed by the Surface Force Apparatus with a probe radius hundred times bigger. In this context the FFM can be called nano-SFA.
13. The ironies of vehicle feedback in car design.
Science.gov (United States)
Walker, Guy H; Stanton, Neville A; Young, Mark S
2006-02-10
Car drivers show an acute sensitivity towards vehicle feedback, with most normal drivers able to detect 'the difference in vehicle feel of a medium-size saloon car with and without a fairly heavy passenger in the rear seat' (Joy and Hartley 1953-54). The irony is that this level of sensitivity stands in contrast to the significant changes in vehicle 'feel' accompanying modern trends in automotive design, such as drive-by-wire and increased automation. The aim of this paper is to move the debate from the anecdotal to the scientific level. This is achieved by using the Brunel University driving simulator to replicate some of these trends and changes by presenting (or removing) different forms of non-visual vehicle feedback, and measuring resultant driver situational awareness (SA) using a probe-recall method. The findings confirm that vehicle feedback plays a key role in coupling the driver to the dynamics of their environment (Moray 2004), with the role of auditory feedback particularly prominent. As a contrast, drivers in the study also rated their self-perceived levels of SA and a concerning dissociation occurred between the two sets of results. Despite the large changes in vehicle feedback presented in the simulator, and the measured changes in SA, drivers appeared to have little self-awareness of these changes. Most worryingly, drivers demonstrated little awareness of diminished SA. The issues surrounding vehicle feedback are therefore similar to the classic problems and ironies studied in aviation and automation, and highlight the role that ergonomics can also play within the domain of contemporary vehicle design.
14. Feedback and Incentives:
DEFF Research Database (Denmark)
Eriksson, Tor Viking; Poulsen, Anders; Villeval, Marie-Claire
This paper experimentally investigates the impact of different pay and relative performance information policies on employee effort. We explore three information policies: No feedback about relative performance, feedback given halfway through the production period, and continuously updated feedback....... The pay schemes are a piece rate payment scheme and a winner-takes-all tournament. We find that, regardless of the pay scheme used, feedback does not improve performance. There are no significant peer effects in the piece-rate pay scheme. In contrast, in the tournament scheme we find some evidence...... of positive peer effects since the underdogs almost never quit the competition even when lagging significantly behind, and frontrunners do not slack off. Moreover, in both pay schemes information feedback reduces the quality of the low performers' work....
15. Multimode optical feedback dynamics of InAs/GaAs quantum-dot lasers emitting on different lasing states
Science.gov (United States)
Huang, H.; Arsenijević, D.; Schires, K.; Sadeev, T.; Bimberg, D.; Grillot, F.
2016-12-01
Quantum dot lasers are envisioned to be the next generation of optical transmitters used for short-reach communication links, owing to their low threshold current and high temperature operation. However, in a context of steady increase in both speed and reach, quantum dot lasers emitting on their upper energy levels have been recently of greater interest as they are touted for their faster modulation dynamics. This work aims at further evaluating the potential impact of such lasers in communication links by characterizing their long-delay optical feedback responses as well as the role of the lasing states on the multimode dynamics of InAs/GaAs quantum-dot Fabry-Perot devices sharing the same design. Results unveil that the excited-state laser shows a much larger sensitivity to optical feedback, with a more complex route to chaos, and a first destabilization point occurring at lower feedback strengths than for a comparable ground-state laser, which remains almost unaffected.
16. Duration reproduction with sensory feedback delay: Differential involvement of perception and action time
Directory of Open Access Journals (Sweden)
Stephanie eGanzenmüller
2012-10-01
Full Text Available Previous research has shown that voluntary action can attract subsequent, delayed feedback events towards the action, and adaptation to the sensorimotor delay can even reverse motor-sensory temporal-order judgments. However, whether and how sensorimotor delay affects duration reproduction is still unclear. To investigate this, we injected an onset- or offset-delay to the sensory feedback signal from a duration reproduction task. We compared duration reproductions within (visual, auditory modality and across audiovisual modalities with feedback signal onset- and offset-delay manipulations. We found that the reproduced duration was lengthened in both visual and auditory feedback signal onset-delay conditions. The lengthening effect was evident immediately, on the first trial with the onset delay. However, when the onset of the feedback signal was prior to the action, the lengthening effect was diminished. In contrast, a shortening effect was found with feedback signal offset-delay, though the effect was weaker and manifested only in the auditory offset-delay condition. These findings indicate that participants tend to mix the onset of action and the feedback signal more when the feedback is delayed, and they heavily rely on motor-stop signals for the duration reproduction. Furthermore, auditory duration was overestimated compared to visual duration in crossmodal feedback conditions, and the overestimation of auditory duration (or the underestimation of visual duration was independent of the delay manipulation.
17. Source reliability in auditory health persuasion : Its antecedents and consequences
NARCIS (Netherlands)
Elbert, Sarah P.; Dijkstra, Arie
2015-01-01
Persuasive health messages can be presented through an auditory channel, thereby enhancing the salience of the source, making it fundamentally different from written or pictorial information. We focused on the determinants of perceived source reliability in auditory health persuasion by investigatin
18. Auditory Backward Masking Deficits in Children with Reading Disabilities
Science.gov (United States)
Montgomery, Christine R.; Morris, Robin D.; Sevcik, Rose A.; Clarkson, Marsha G.
2005-01-01
Studies evaluating temporal auditory processing among individuals with reading and other language deficits have yielded inconsistent findings due to methodological problems (Studdert-Kennedy & Mody, 1995) and sample differences. In the current study, seven auditory masking thresholds were measured in fifty-two 7- to 10-year-old children (26…
19. Auditory sustained field responses to periodic noise
Directory of Open Access Journals (Sweden)
Keceli Sumru
2012-01-01
Full Text Available Abstract Background Auditory sustained responses have been recently suggested to reflect neural processing of speech sounds in the auditory cortex. As periodic fluctuations below the pitch range are important for speech perception, it is necessary to investigate how low frequency periodic sounds are processed in the human auditory cortex. Auditory sustained responses have been shown to be sensitive to temporal regularity but the relationship between the amplitudes of auditory evoked sustained responses and the repetitive rates of auditory inputs remains elusive. As the temporal and spectral features of sounds enhance different components of sustained responses, previous studies with click trains and vowel stimuli presented diverging results. In order to investigate the effect of repetition rate on cortical responses, we analyzed the auditory sustained fields evoked by periodic and aperiodic noises using magnetoencephalography. Results Sustained fields were elicited by white noise and repeating frozen noise stimuli with repetition rates of 5-, 10-, 50-, 200- and 500 Hz. The sustained field amplitudes were significantly larger for all the periodic stimuli than for white noise. Although the sustained field amplitudes showed a rising and falling pattern within the repetition rate range, the response amplitudes to 5 Hz repetition rate were significantly larger than to 500 Hz. Conclusions The enhanced sustained field responses to periodic noises show that cortical sensitivity to periodic sounds is maintained for a wide range of repetition rates. Persistence of periodicity sensitivity below the pitch range suggests that in addition to processing the fundamental frequency of voice, sustained field generators can also resolve low frequency temporal modulations in speech envelope.
20. Mirror Visual Feedback Training Improves Intermanual Transfer in a Sport-Specific Task: A Comparison between Different Skill Levels
Directory of Open Access Journals (Sweden)
Fabian Steinberg
2016-01-01
Full Text Available Mirror training therapy is a promising tool to initiate neural plasticity and facilitate the recovery process of motor skills after diseases such as stroke or hemiparesis by improving the intermanual transfer of fine motor skills in healthy people as well as in patients. This study evaluated whether these augmented performance improvements by mirror visual feedback (MVF could be used for learning a sport-specific skill and if the effects are modulated by skill level. A sample of 39 young, healthy, and experienced basketball and handball players and 41 novices performed a stationary basketball dribble task at a mirror box in a standing position and received either MVF or direct feedback. After four training days using only the right hand, performance of both hands improved from pre- to posttest measurements. Only the left hand (untrained performance of the experienced participants receiving MVF was more pronounced than for the control group. This indicates that intermanual motor transfer can be improved by MVF in a sport-specific task. However, this effect cannot be generalized to motor learning per se since it is modulated by individuals’ skill level, a factor that might be considered in mirror therapy research.
1. Mirror Visual Feedback Training Improves Intermanual Transfer in a Sport-Specific Task: A Comparison between Different Skill Levels
Science.gov (United States)
Pixa, Nils Henrik; Doppelmayr, Michael
2016-01-01
Mirror training therapy is a promising tool to initiate neural plasticity and facilitate the recovery process of motor skills after diseases such as stroke or hemiparesis by improving the intermanual transfer of fine motor skills in healthy people as well as in patients. This study evaluated whether these augmented performance improvements by mirror visual feedback (MVF) could be used for learning a sport-specific skill and if the effects are modulated by skill level. A sample of 39 young, healthy, and experienced basketball and handball players and 41 novices performed a stationary basketball dribble task at a mirror box in a standing position and received either MVF or direct feedback. After four training days using only the right hand, performance of both hands improved from pre- to posttest measurements. Only the left hand (untrained) performance of the experienced participants receiving MVF was more pronounced than for the control group. This indicates that intermanual motor transfer can be improved by MVF in a sport-specific task. However, this effect cannot be generalized to motor learning per se since it is modulated by individuals' skill level, a factor that might be considered in mirror therapy research. PMID:27642526
2. Auditory and Visual Sensations
CERN Document Server
Ando, Yoichi
2010-01-01
Professor Yoichi Ando, acoustic architectural designer of the Kirishima International Concert Hall in Japan, presents a comprehensive rational-scientific approach to designing performance spaces. His theory is based on systematic psychoacoustical observations of spatial hearing and listener preferences, whose neuronal correlates are observed in the neurophysiology of the human brain. A correlation-based model of neuronal signal processing in the central auditory system is proposed in which temporal sensations (pitch, timbre, loudness, duration) are represented by an internal autocorrelation representation, and spatial sensations (sound location, size, diffuseness related to envelopment) are represented by an internal interaural crosscorrelation function. Together these two internal central auditory representations account for the basic auditory qualities that are relevant for listening to music and speech in indoor performance spaces. Observed psychological and neurophysiological commonalities between auditor...
3. Mode-locking neurodynamics predict human auditory brainstem responses to musical intervals.
Science.gov (United States)
Lerud, Karl D; Almonte, Felix V; Kim, Ji Chul; Large, Edward W
2014-02-01
The auditory nervous system is highly nonlinear. Some nonlinear responses arise through active processes in the cochlea, while others may arise in neural populations of the cochlear nucleus, inferior colliculus and higher auditory areas. In humans, auditory brainstem recordings reveal nonlinear population responses to combinations of pure tones, and to musical intervals composed of complex tones. Yet the biophysical origin of central auditory nonlinearities, their signal processing properties, and their relationship to auditory perception remain largely unknown. Both stimulus components and nonlinear resonances are well represented in auditory brainstem nuclei due to neural phase-locking. Recently mode-locking, a generalization of phase-locking that implies an intrinsically nonlinear processing of sound, has been observed in mammalian auditory brainstem nuclei. Here we show that a canonical model of mode-locked neural oscillation predicts the complex nonlinear population responses to musical intervals that have been observed in the human brainstem. The model makes predictions about auditory signal processing and perception that are different from traditional delay-based models, and may provide insight into the nature of auditory population responses. We anticipate that the application of dynamical systems analysis will provide the starting point for generic models of auditory population dynamics, and lead to a deeper understanding of nonlinear auditory signal processing possibly arising in excitatory-inhibitory networks of the central auditory nervous system. This approach has the potential to link neural dynamics with the perception of pitch, music, and speech, and lead to dynamical models of auditory system development.
4. Functional outcome of auditory implants in hearing loss.
Science.gov (United States)
Di Girolamo, S; Saccoccio, A; Giacomini, P G; Ottaviani, F
2007-01-01
The auditory implant provides a new mechanism for hearing when a hearing aid is not enough. It is the only medical technology able to functionally restore a human sense i.e. hearing. The auditory implant is very different from a hearing aid. Hearing aids amplify sound. Auditory implants compensate for damaged or non-working parts of the inner ear because they can directly stimulate the acoustic nerve. There are two principal types of auditory implant: the cochlear implant and the auditory brainstem implant. They have common basic characteristics, but different applications. A cochlear implant attempts to replace a function lost by the cochlea, usually due to an absence of functioning hair cells; the auditory brainstem implant (ABI) is a modification of the cochlear implant, in which the electrode array is placed directly into the brain when the acoustic nerve is not anymore able to carry the auditory signal. Different types of deaf or severely hearing-impaired patients choose auditory implants. Both children and adults can be candidates for implants. The best age for implantation is still being debated, but most children who receive implants are between 2 and 6 years old. Earlier implantation seems to perform better thanks to neural plasticity. The decision to receive an implant should involve a discussion with many medical specialists and an experienced surgeon.
5. Effects of Caffeine on Auditory Brainstem Response
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Saleheh Soleimanian
2008-06-01
Full Text Available Background and Aim: Blocking of the adenosine receptor in central nervous system by caffeine can lead to increasing the level of neurotransmitters like glutamate. As the adenosine receptors are present in almost all brain areas like central auditory pathway, it seems caffeine can change conduction in this way. The purpose of this study was to evaluate the effects of caffeine on latency and amplitude of auditory brainstem response(ABR.Materials and Methods: In this clinical trial study 43 normal 18-25 years old male students were participated. The subjects consumed 0, 2 and 3 mg/kg BW caffeine in three different sessions. Auditory brainstem responses were recorded before and 30 minute after caffeine consumption. The results were analyzed by Friedman and Wilcoxone test to assess the effects of caffeine on auditory brainstem response.Results: Compared to control group the latencies of waves III,V and I-V interpeak interval of the cases decreased significantly after 2 and 3mg/kg BW caffeine consumption. Wave I latency significantly decreased after 3mg/kg BW caffeine consumption(p<0.01. Conclusion: Increasing of the glutamate level resulted from the adenosine receptor blocking brings about changes in conduction in the central auditory pathway.
6. Facilitated auditory detection for speech sounds.
Science.gov (United States)
Signoret, Carine; Gaudrain, Etienne; Tillmann, Barbara; Grimault, Nicolas; Perrin, Fabien
2011-01-01
If it is well known that knowledge facilitates higher cognitive functions, such as visual and auditory word recognition, little is known about the influence of knowledge on detection, particularly in the auditory modality. Our study tested the influence of phonological and lexical knowledge on auditory detection. Words, pseudo-words, and complex non-phonological sounds, energetically matched as closely as possible, were presented at a range of presentation levels from sub-threshold to clearly audible. The participants performed a detection task (Experiments 1 and 2) that was followed by a two alternative forced-choice recognition task in Experiment 2. The results of this second task in Experiment 2 suggest a correct recognition of words in the absence of detection with a subjective threshold approach. In the detection task of both experiments, phonological stimuli (words and pseudo-words) were better detected than non-phonological stimuli (complex sounds), presented close to the auditory threshold. This finding suggests an advantage of speech for signal detection. An additional advantage of words over pseudo-words was observed in Experiment 2, suggesting that lexical knowledge could also improve auditory detection when listeners had to recognize the stimulus in a subsequent task. Two simulations of detection performance performed on the sound signals confirmed that the advantage of speech over non-speech processing could not be attributed to energetic differences in the stimuli.
7. Facilitated auditory detection for speech sounds
Directory of Open Access Journals (Sweden)
Carine eSignoret
2011-07-01
Full Text Available If it is well known that knowledge facilitates higher cognitive functions, such as visual and auditory word recognition, little is known about the influence of knowledge on detection, particularly in the auditory modality. Our study tested the influence of phonological and lexical knowledge on auditory detection. Words, pseudo words and complex non phonological sounds, energetically matched as closely as possible, were presented at a range of presentation levels from sub threshold to clearly audible. The participants performed a detection task (Experiments 1 and 2 that was followed by a two alternative forced choice recognition task in Experiment 2. The results of this second task in Experiment 2 suggest a correct recognition of words in the absence of detection with a subjective threshold approach. In the detection task of both experiments, phonological stimuli (words and pseudo words were better detected than non phonological stimuli (complex sounds, presented close to the auditory threshold. This finding suggests an advantage of speech for signal detection. An additional advantage of words over pseudo words was observed in Experiment 2, suggesting that lexical knowledge could also improve auditory detection when listeners had to recognize the stimulus in a subsequent task. Two simulations of detection performance performed on the sound signals confirmed that the advantage of speech over non speech processing could not be attributed to energetic differences in the stimuli.
8. Auditory perceptual simulation: Simulating speech rates or accents?
Science.gov (United States)
Zhou, Peiyun; Christianson, Kiel
2016-07-01
When readers engage in Auditory Perceptual Simulation (APS) during silent reading, they mentally simulate characteristics of voices attributed to a particular speaker or a character depicted in the text. Previous research found that auditory perceptual simulation of a faster native English speaker during silent reading led to shorter reading times that auditory perceptual simulation of a slower non-native English speaker. Yet, it was uncertain whether this difference was triggered by the different speech rates of the speakers, or by the difficulty of simulating an unfamiliar accent. The current study investigates this question by comparing faster Indian-English speech and slower American-English speech in the auditory perceptual simulation paradigm. Analyses of reading times of individual words and the full sentence reveal that the auditory perceptual simulation effect again modulated reading rate, and auditory perceptual simulation of the faster Indian-English speech led to faster reading rates compared to auditory perceptual simulation of the slower American-English speech. The comparison between this experiment and the data from Zhou and Christianson (2016) demonstrate further that the "speakers'" speech rates, rather than the difficulty of simulating a non-native accent, is the primary mechanism underlying auditory perceptual simulation effects.
9. Inter-comparison of two land-surface models applied at different scales and their feedbacks while coupled with a regional climate model
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F. Zabel
2012-03-01
Full Text Available Downstream models are often used in order to study regional impacts of climate and climate change on the land surface. For this purpose, they are usually driven offline (i.e., 1-way with results from regional climate models (RCMs. However, the offline approach does not allow for feedbacks between these models. Thereby, the land surface of the downstream model is usually completely different to the land surface which is used within the RCM. Thus, this study aims at investigating the inconsistencies that arise when driving a downstream model offline instead of interactively coupled with the RCM, due to different feedbacks from the use of different land surface models (LSM. Therefore, two physically based LSMs which developed from different disciplinary backgrounds are compared in our study: while the NOAH-LSM was developed for the use within RCMs, PROMET was originally developed to answer hydrological questions on the local to regional scale. Thereby, the models use different physical formulations on different spatial scales and different parameterizations of the same land surface processes that lead to inconsistencies when driving PROMET offline with RCM output. Processes that contribute to these inconsistencies are, as described in this study, net radiation due to land use related albedo and emissivity differences, the redistribution of this net radiation over sensible and latent heat, for example, due to different assumptions about land use impermeability or soil hydraulic reasons caused by different plant and soil parameterizations. As a result, simulated evapotranspiration, e.g., shows considerable differences of max. 280 mm yr−1. For a full interactive coupling (i.e., 2-way between PROMET and the atmospheric part of the RCM, PROMET returns the land surface energy fluxes to the RCM and, thus, provides the lower boundary conditions for the RCM subsequently. Accordingly, the RCM responses to the replacement of the LSM with overall
10. A Comparison of Peer and Tutor Feedback
Science.gov (United States)
Hamer, John; Purchase, Helen; Luxton-Reilly, Andrew; Denny, Paul
2015-01-01
We report on a study comparing peer feedback with feedback written by tutors on a large, undergraduate software engineering programming class. Feedback generated by peers is generally held to be of lower quality to feedback from experienced tutors, and this study sought to explore the extent and nature of this difference. We looked at how…
11. Positive feedback promotes oscillations in negative feedback loops.
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Bharath Ananthasubramaniam
Full Text Available A simple three-component negative feedback loop is a recurring motif in biochemical oscillators. This motif oscillates as it has the three necessary ingredients for oscillations: a three-step delay, negative feedback, and nonlinearity in the loop. However, to oscillate, this motif under the common Goodwin formulation requires a high degree of cooperativity (a measure of nonlinearity in the feedback that is biologically "unlikely." Moreover, this recurring negative feedback motif is commonly observed augmented by positive feedback interactions. Here we show that these positive feedback interactions promote oscillation at lower degrees of cooperativity, and we can thus unify several common kinetic mechanisms that facilitate oscillations, such as self-activation and Michaelis-Menten degradation. The positive feedback loops are most beneficial when acting on the shortest lived component, where they function by balancing the lifetimes of the different components. The benefits of multiple positive feedback interactions are cumulative for a majority of situations considered, when benefits are measured by the reduction in the cooperativity required to oscillate. These positive feedback motifs also allow oscillations with longer periods than that determined by the lifetimes of the components alone. We can therefore conjecture that these positive feedback loops have evolved to facilitate oscillations at lower, kinetically achievable, degrees of cooperativity. Finally, we discuss the implications of our conclusions on the mammalian molecular clock, a system modeled extensively based on the three-component negative feedback loop.
12. The many facets of auditory display
Science.gov (United States)
Blattner, Meera M.
1995-01-01
In this presentation we will examine some of the ways sound can be used in a virtual world. We make the case that many different types of audio experience are available to us. A full range of audio experiences include: music, speech, real-world sounds, auditory displays, and auditory cues or messages. The technology of recreating real-world sounds through physical modeling has advanced in the past few years allowing better simulation of virtual worlds. Three-dimensional audio has further enriched our sensory experiences.
13. Auditory evacuation beacons
NARCIS (Netherlands)
Wijngaarden, S.J. van; Bronkhorst, A.W.; Boer, L.C.
2005-01-01
Auditory evacuation beacons can be used to guide people to safe exits, even when vision is totally obscured by smoke. Conventional beacons make use of modulated noise signals. Controlled evacuation experiments show that such signals require explicit instructions and are often misunderstood. A new si
14. Virtual Auditory Displays
Science.gov (United States)
2000-01-01
timbre , intensity, distance, room modeling, radio communication Virtual Environments Handbook Chapter 4 Virtual Auditory Displays Russell D... musical note “A” as a pure sinusoid, there will be 440 condensations and rarefactions per second. The distance between two adjacent condensations or...and complexity are pitch, loudness, and timbre respectively. This distinction between physical and perceptual measures of sound properties is an
15. The neglected neglect: auditory neglect.
Science.gov (United States)
Gokhale, Sankalp; Lahoti, Sourabh; Caplan, Louis R
2013-08-01
Whereas visual and somatosensory forms of neglect are commonly recognized by clinicians, auditory neglect is often not assessed and therefore neglected. The auditory cortical processing system can be functionally classified into 2 distinct pathways. These 2 distinct functional pathways deal with recognition of sound ("what" pathway) and the directional attributes of the sound ("where" pathway). Lesions of higher auditory pathways produce distinct clinical features. Clinical bedside evaluation of auditory neglect is often difficult because of coexisting neurological deficits and the binaural nature of auditory inputs. In addition, auditory neglect and auditory extinction may show varying degrees of overlap, which makes the assessment even harder. Shielding one ear from the other as well as separating the ear from space is therefore critical for accurate assessment of auditory neglect. This can be achieved by use of specialized auditory tests (dichotic tasks and sound localization tests) for accurate interpretation of deficits. Herein, we have reviewed auditory neglect with an emphasis on the functional anatomy, clinical evaluation, and basic principles of specialized auditory tests.
16. Influence of Feedback Levels on Polarized Optical Feedback Characteristics in Zeeman-Birefringence Dual Frequency Lasers
Institute of Scientific and Technical Information of China (English)
MAO Wei; ZHANG Shu-Lian; ZHOU Lu-Fei; LIU Xiao-Yan; WANG Ming-Ming
2007-01-01
The influence of Feedback levels on the intensity and polarization properties of polarized optical feedback in a Zeeman-birefringence dual frequency laser is systematically investigated. By changing the feedback power ratio, different feedback levels are obtained. Three distinct regimes of polarized optical feedback effects are found and defined as regimes Ⅰ, Ⅱand Ⅲ. The feedback level boundaries among the regimes are acquired experimentally. The theoretical analysis is presented to be in good agreement with the experimental results.
17. Impact of Educational Level on Performance on Auditory Processing Tests.
Science.gov (United States)
Murphy, Cristina F B; Rabelo, Camila M; Silagi, Marcela L; Mansur, Letícia L; Schochat, Eliane
2016-01-01
Research has demonstrated that a higher level of education is associated with better performance on cognitive tests among middle-aged and elderly people. However, the effects of education on auditory processing skills have not yet been evaluated. Previous demonstrations of sensory-cognitive interactions in the aging process indicate the potential importance of this topic. Therefore, the primary purpose of this study was to investigate the performance of middle-aged and elderly people with different levels of formal education on auditory processing tests. A total of 177 adults with no evidence of cognitive, psychological or neurological conditions took part in the research. The participants completed a series of auditory assessments, including dichotic digit, frequency pattern and speech-in-noise tests. A working memory test was also performed to investigate the extent to which auditory processing and cognitive performance were associated. The results demonstrated positive but weak correlations between years of schooling and performance on all of the tests applied. The factor "years of schooling" was also one of the best predictors of frequency pattern and speech-in-noise test performance. Additionally, performance on the working memory, frequency pattern and dichotic digit tests was also correlated, suggesting that the influence of educational level on auditory processing performance might be associated with the cognitive demand of the auditory processing tests rather than auditory sensory aspects itself. Longitudinal research is required to investigate the causal relationship between educational level and auditory processing skills.
18. Strategy choice mediates the link between auditory processing and spelling.
Science.gov (United States)
Kwong, Tru E; Brachman, Kyle J
2014-01-01
Relations among linguistic auditory processing, nonlinguistic auditory processing, spelling ability, and spelling strategy choice were examined. Sixty-three undergraduate students completed measures of auditory processing (one involving distinguishing similar tones, one involving distinguishing similar phonemes, and one involving selecting appropriate spellings for individual phonemes). Participants also completed a modified version of a standardized spelling test, and a secondary spelling test with retrospective strategy reports. Once testing was completed, participants were divided into phonological versus nonphonological spellers on the basis of the number of words they spelled using phonological strategies only. Results indicated a) moderate to strong positive correlations among the different auditory processing tasks in terms of reaction time, but not accuracy levels, and b) weak to moderate positive correlations between measures of linguistic auditory processing (phoneme distinction and phoneme spelling choice in the presence of foils) and spelling ability for phonological spellers, but not for nonphonological spellers. These results suggest a possible explanation for past contradictory research on auditory processing and spelling, which has been divided in terms of whether or not disabled spellers seemed to have poorer auditory processing than did typically developing spellers, and suggest implications for teaching spelling to children with good versus poor auditory processing abilities.
19. Use of auditory learning to manage listening problems in children.
Science.gov (United States)
Moore, David R; Halliday, Lorna F; Amitay, Sygal
2009-02-12
This paper reviews recent studies that have used adaptive auditory training to address communication problems experienced by some children in their everyday life. It considers the auditory contribution to developmental listening and language problems and the underlying principles of auditory learning that may drive further refinement of auditory learning applications. Following strong claims that language and listening skills in children could be improved by auditory learning, researchers have debated what aspect of training contributed to the improvement and even whether the claimed improvements reflect primarily a retest effect on the skill measures. Key to understanding this research have been more circumscribed studies of the transfer of learning and the use of multiple control groups to examine auditory and non-auditory contributions to the learning. Significant auditory learning can occur during relatively brief periods of training. As children mature, their ability to train improves, but the relation between the duration of training, amount of learning and benefit remains unclear. Individual differences in initial performance and amount of subsequent learning advocate tailoring training to individual learners. The mechanisms of learning remain obscure, especially in children, but it appears that the development of cognitive skills is of at least equal importance to the refinement of sensory processing. Promotion of retention and transfer of learning are major goals for further research.
20. Auditory-motor learning during speech production in 9-11-year-old children.
Directory of Open Access Journals (Sweden)
Douglas M Shiller
Full Text Available BACKGROUND: Hearing ability is essential for normal speech development, however the precise mechanisms linking auditory input and the improvement of speaking ability remain poorly understood. Auditory feedback during speech production is believed to play a critical role by providing the nervous system with information about speech outcomes that is used to learn and subsequently fine-tune speech motor output. Surprisingly, few studies have directly investigated such auditory-motor learning in the speech production of typically developing children. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we manipulated auditory feedback during speech production in a group of 9-11-year old children, as well as in adults. Following a period of speech practice under conditions of altered auditory feedback, compensatory changes in speech production and perception were examined. Consistent with prior studies, the adults exhibited compensatory changes in both their speech motor output and their perceptual representations of speech sound categories. The children exhibited compensatory changes in the motor domain, with a change in speech output that was similar in magnitude to that of the adults, however the children showed no reliable compensatory effect on their perceptual representations. CONCLUSIONS: The results indicate that 9-11-year-old children, whose speech motor and perceptual abilities are still not fully developed, are nonetheless capable of auditory-feedback-based sensorimotor adaptation, supporting a role for such learning processes in speech motor development. Auditory feedback may play a more limited role, however, in the fine-tuning of children's perceptual representations of speech sound categories.
1. Effects of digital vibrotactile speech feedback on overt stuttering frequency.
Science.gov (United States)
Snyder, Gregory J; Blanchet, Paul; Waddell, Dwight; Ivy, Lennette J
2009-02-01
Fluency-enhancing speech feedback, originating from internally or externally generated sources via auditory or visual sensory modalities is not restricted to a specific sensory modality or signal origination. Research suggests that externally generated digital vibrotactile speech feedback serves as an effective fluency enhancer. The present purpose was to test the fluency-enhancing effects of self-generated digital vibrotactile speech feedback on stuttering frequency. Adults who stutter read passages aloud over the telephone, both with and without digital vibrotactile speech feedback. Digital vibrotactile speech feedback was operationally defined as feeling the vibrations of the thyroid cartilage with the thumb and index finger while speaking. Analysis indicated that self-generated digital vibrotactile speech feedback reduced overt stuttering frequency by an average of 72%. As the specific neural mechanisms associated with stuttering and fluency enhancement from tactile speech feedback remain unknown, theoretical implications and clinical applications were discussed.
2. Autosomal recessive hereditary auditory neuropathy
Institute of Scientific and Technical Information of China (English)
王秋菊; 顾瑞; 曹菊阳
2003-01-01
evidence of peripheral neuropathy at the time of this writing. Conclusions: In this study, patients with feature of non- syndromic hereditary auditory neuropathy were identified in three Chinese families.Pedigree analysis indicates autosomal recessive inheritances in the pedigrees. The observed inheritance and clinical audiologic findings are different from those previously described for non-syndromic low-frequency sensorineural hearing loss. This information should facilitate future molecular candidate genes screening for understanding the mechanism of AN.
3. The Effect of Performance Feedback on Student Help-Seeking and Learning Strategy Use: Do Clickers Make a Difference?
Directory of Open Access Journals (Sweden)
Tom Haffie
2010-06-01
Full Text Available Two studies were performed to investigate the impact of students’ clicker performance feedback on their help-seeking behaviour and use of other learning strategies. In study 1, we investigated the relationship between students’ clicker performance, self-efficacy, help-seeking behavior, and academic achievement. We found that there was a significant positive correlation between their clicker performance and their course grades, and help-seeking behavior was negatively and significantly related to clicker and course performance but only for participants with high self-efficacy. In study 2, we expanded our focus to determine if participants modified a number of learning strategies as a result of receiving clicker performance feedback as well as attempting to replicate the clicker-course performance relationship found in study 1. Although participants reported an increase in their use of various learning strategies as a result of using the clickers, changes in learning strategy use was not significantly related to clicker or term test performance. The relationship between clicker and course performance was replicated. The results suggest that clicker-based feedback alone may not be sufficient to lead to a successful change in learning strategy use and that students may need more specific instruction on self-regulation and effective learning strategy use in order to improve their learning.Deux études ont évalué l’impact de la rétroaction sur la performance des étudiants indiquée par télévoteur sur leur comportement de recherche d’aide et sur les autres stratégies d’apprentissage utilisées. Dans la première étude, les chercheurs se sont penchés sur la relation entre la performance indiquée par télévoteur, le sentiment d’auto-efficacité, la recherche d’aide et la réussite scolaire. Nous avons trouvé une corrélation positive significative entre la performance indiquée par télévoteur et les notes de cours. De plus
4. Interactions across Multiple Stimulus Dimensions in Primary Auditory Cortex.
Science.gov (United States)
Sloas, David C; Zhuo, Ran; Xue, Hongbo; Chambers, Anna R; Kolaczyk, Eric; Polley, Daniel B; Sen, Kamal
2016-01-01
Although sensory cortex is thought to be important for the perception of complex objects, its specific role in representing complex stimuli remains unknown. Complex objects are rich in information along multiple stimulus dimensions. The position of cortex in the sensory hierarchy suggests that cortical neurons may integrate across these dimensions to form a more gestalt representation of auditory objects. Yet, studies of cortical neurons typically explore single or few dimensions due to the difficulty of determining optimal stimuli in a high dimensional stimulus space. Evolutionary algorithms (EAs) provide a potentially powerful approach for exploring multidimensional stimulus spaces based on real-time spike feedback, but two important issues arise in their application. First, it is unclear whether it is necessary to characterize cortical responses to multidimensional stimuli or whether it suffices to characterize cortical responses to a single dimension at a time. Second, quantitative methods for analyzing complex multidimensional data from an EA are lacking. Here, we apply a statistical method for nonlinear regression, the generalized additive model (GAM), to address these issues. The GAM quantitatively describes the dependence between neural response and all stimulus dimensions. We find that auditory cortical neurons in mice are sensitive to interactions across dimensions. These interactions are diverse across the population, indicating significant integration across stimulus dimensions in auditory cortex. This result strongly motivates using multidimensional stimuli in auditory cortex. Together, the EA and the GAM provide a novel quantitative paradigm for investigating neural coding of complex multidimensional stimuli in auditory and other sensory cortices.
5. Interactions across Multiple Stimulus Dimensions in Primary Auditory Cortex
Science.gov (United States)
Zhuo, Ran; Xue, Hongbo; Chambers, Anna R.; Kolaczyk, Eric; Polley, Daniel B.
2016-01-01
Although sensory cortex is thought to be important for the perception of complex objects, its specific role in representing complex stimuli remains unknown. Complex objects are rich in information along multiple stimulus dimensions. The position of cortex in the sensory hierarchy suggests that cortical neurons may integrate across these dimensions to form a more gestalt representation of auditory objects. Yet, studies of cortical neurons typically explore single or few dimensions due to the difficulty of determining optimal stimuli in a high dimensional stimulus space. Evolutionary algorithms (EAs) provide a potentially powerful approach for exploring multidimensional stimulus spaces based on real-time spike feedback, but two important issues arise in their application. First, it is unclear whether it is necessary to characterize cortical responses to multidimensional stimuli or whether it suffices to characterize cortical responses to a single dimension at a time. Second, quantitative methods for analyzing complex multidimensional data from an EA are lacking. Here, we apply a statistical method for nonlinear regression, the generalized additive model (GAM), to address these issues. The GAM quantitatively describes the dependence between neural response and all stimulus dimensions. We find that auditory cortical neurons in mice are sensitive to interactions across dimensions. These interactions are diverse across the population, indicating significant integration across stimulus dimensions in auditory cortex. This result strongly motivates using multidimensional stimuli in auditory cortex. Together, the EA and the GAM provide a novel quantitative paradigm for investigating neural coding of complex multidimensional stimuli in auditory and other sensory cortices. PMID:27622211
6. Comparison of Electrophysiological Auditory Measures in Fishes.
Science.gov (United States)
Maruska, Karen P; Sisneros, Joseph A
2016-01-01
Sounds provide fishes with important information used to mediate behaviors such as predator avoidance, prey detection, and social communication. How we measure auditory capabilities in fishes, therefore, has crucial implications for interpreting how individual species use acoustic information in their natural habitat. Recent analyses have highlighted differences between behavioral and electrophysiologically determined hearing thresholds, but less is known about how physiological measures at different auditory processing levels compare within a single species. Here we provide one of the first comparisons of auditory threshold curves determined by different recording methods in a single fish species, the soniferous Hawaiian sergeant fish Abudefduf abdominalis, and review past studies on representative fish species with tuning curves determined by different methods. The Hawaiian sergeant is a colonial benthic-spawning damselfish (Pomacentridae) that produces low-frequency, low-intensity sounds associated with reproductive and agonistic behaviors. We compared saccular potentials, auditory evoked potentials (AEP), and single neuron recordings from acoustic nuclei of the hindbrain and midbrain torus semicircularis. We found that hearing thresholds were lowest at low frequencies (~75-300 Hz) for all methods, which matches the spectral components of sounds produced by this species. However, thresholds at best frequency determined via single cell recordings were ~15-25 dB lower than those measured by AEP and saccular potential techniques. While none of these physiological techniques gives us a true measure of the auditory "perceptual" abilities of a naturally behaving fish, this study highlights that different methodologies can reveal similar detectable range of frequencies for a given species, but absolute hearing sensitivity may vary considerably.
7. Investigation into the response of the auditory and acoustic communications systems in the Beluga whale (Delphinapterus leucas) of the St. Lawrence River Estuary to noise, using vocal classification
Science.gov (United States)
Scheifele, Peter Martin
2003-06-01
Noise pollution has only recently become recognized as a potential danger to marine mammals in general, and to the Beluga Whale (Delphinapterus leucas) in particular. These small gregarious Odontocetes make extensive use of sound for social communication and pod cohesion. The St. Lawrence River Estuary is habitat to a small, critically endangered population of about 700 Beluga whales who congregate in four different sites in its upper estuary. The population is believed to be threatened by the stress of high-intensity, low frequency noise. One way to determine whether noise is having an effect on an animal's auditory ability might be to observe a natural and repeatable response of the auditory and vocal systems to varying noise levels. This can be accomplished by observing changes in animal vocalizations in response to auditory feedback. A response such as this observed in humans and some animals is known as the Lombard Vocal Response, which represents a reaction of the auditory system directly manifested by changes in vocalization level. In this research this population of Beluga Whales was tested to determine whether a vocalization-as-a-function-of-noise phenomenon existed by using Hidden Markhov "classified" vocalizations as targets for acoustical analyses. Correlation and regression analyses indicated that the phenomenon does exist and results of a human subjects experiment along with results from other animal species known to exhibit the response strongly implicate the Lombard Vocal Response in the Beluga.
8. Self-recognition Deficits in Schizophrenia Patients With Auditory Hallucinations : A Meta-analysis of the Literature
NARCIS (Netherlands)
Waters, Flavie; Woodward, Todd; Allen, Paul; Aleman, Andre; Sommers, Iris
2012-01-01
Theories about auditory hallucinations in schizophrenia suggest that these experiences occur because patients fail to recognize thoughts and mental events as self-generated. Different theoretical models have been proposed about the cognitive mechanisms underlying auditory hallucinations. Regardless
9. Resizing Auditory Communities
DEFF Research Database (Denmark)
Kreutzfeldt, Jacob
2012-01-01
Heard through the ears of the Canadian composer and music teacher R. Murray Schafer the ideal auditory community had the shape of a village. Schafer’s work with the World Soundscape Project in the 70s represent an attempt to interpret contemporary environments through musical and auditory...... parameters highlighting harmonious and balanced qualities while criticizing the noisy and cacophonous qualities of modern urban settings. This paper present a reaffirmation of Schafer’s central methodological claim: that environments can be analyzed through their sound, but offers considerations on the role...... musicalized through electro acoustic equipment installed in shops, shopping streets, transit areas etc. Urban noise no longer acts only as disturbance, but also structure and shape the places and spaces in which urban life enfold. Based on research done in Japanese shopping streets and in Copenhagen the paper...
10. Attention Modulates the Auditory Cortical Processing of Spatial and Category Cues in Naturalistic Auditory Scenes
Science.gov (United States)
Renvall, Hanna; Staeren, Noël; Barz, Claudia S.; Ley, Anke; Formisano, Elia
2016-01-01
This combined fMRI and MEG study investigated brain activations during listening and attending to natural auditory scenes. We first recorded, using in-ear microphones, vocal non-speech sounds, and environmental sounds that were mixed to construct auditory scenes containing two concurrent sound streams. During the brain measurements, subjects attended to one of the streams while spatial acoustic information of the scene was either preserved (stereophonic sounds) or removed (monophonic sounds). Compared to monophonic sounds, stereophonic sounds evoked larger blood-oxygenation-level-dependent (BOLD) fMRI responses in the bilateral posterior superior temporal areas, independent of which stimulus attribute the subject was attending to. This finding is consistent with the functional role of these regions in the (automatic) processing of auditory spatial cues. Additionally, significant differences in the cortical activation patterns depending on the target of attention were observed. Bilateral planum temporale and inferior frontal gyrus were preferentially activated when attending to stereophonic environmental sounds, whereas when subjects attended to stereophonic voice sounds, the BOLD responses were larger at the bilateral middle superior temporal gyrus and sulcus, previously reported to show voice sensitivity. In contrast, the time-resolved MEG responses were stronger for mono- than stereophonic sounds in the bilateral auditory cortices at ~360 ms after the stimulus onset when attending to the voice excerpts within the combined sounds. The observed effects suggest that during the segregation of auditory objects from the auditory background, spatial sound cues together with other relevant temporal and spectral cues are processed in an attention-dependent manner at the cortical locations generally involved in sound recognition. More synchronous neuronal activation during monophonic than stereophonic sound processing, as well as (local) neuronal inhibitory mechanisms in
11. Restoring natural sensory feedback in real-time bidirectional hand prostheses.
Science.gov (United States)
Raspopovic, Stanisa; Capogrosso, Marco; Petrini, Francesco Maria; Bonizzato, Marco; Rigosa, Jacopo; Di Pino, Giovanni; Carpaneto, Jacopo; Controzzi, Marco; Boretius, Tim; Fernandez, Eduardo; Granata, Giuseppe; Oddo, Calogero Maria; Citi, Luca; Ciancio, Anna Lisa; Cipriani, Christian; Carrozza, Maria Chiara; Jensen, Winnie; Guglielmelli, Eugenio; Stieglitz, Thomas; Rossini, Paolo Maria; Micera, Silvestro
2014-02-05
Hand loss is a highly disabling event that markedly affects the quality of life. To achieve a close to natural replacement for the lost hand, the user should be provided with the rich sensations that we naturally perceive when grasping or manipulating an object. Ideal bidirectional hand prostheses should involve both a reliable decoding of the user's intentions and the delivery of nearly "natural" sensory feedback through remnant afferent pathways, simultaneously and in real time. However, current hand prostheses fail to achieve these requirements, particularly because they lack any sensory feedback. We show that by stimulating the median and ulnar nerve fascicles using transversal multichannel intrafascicular electrodes, according to the information provided by the artificial sensors from a hand prosthesis, physiologically appropriate (near-natural) sensory information can be provided to an amputee during the real-time decoding of different grasping tasks to control a dexterous hand prosthesis. This feedback enabled the participant to effectively modulate the grasping force of the prosthesis with no visual or auditory feedback. Three different force levels were distinguished and consistently used by the subject. The results also demonstrate that a high complexity of perception can be obtained, allowing the subject to identify the stiffness and shape of three different objects by exploiting different characteristics of the elicited sensations. This approach could improve the efficacy and "life-like" quality of hand prostheses, resulting in a keystone strategy for the near-natural replacement of missing hands.
12. Orthographic consistency affects spoken word recognition at different grain-sizes
DEFF Research Database (Denmark)
2014-01-01
A number of previous studies found that the consistency of sound-to-spelling mappings (feedback consistency) affects spoken word recognition. In auditory lexical decision experiments, words that can only be spelled one way are recognized faster than words with multiple potential spellings. Previous.......g., lobe) faster than words with consistent rhymes where the vowel has a less typical spelling (e.g., loaf). The present study extends previous literature by showing that auditory word recognition is affected by orthographic regularities at different grain sizes, just like written word recognition...
13. Mudança significativa do limiar auditivo em trabalhadores expostos a diferentes níveis de ruído Significant auditory threshold shift among workers exposed to different noise levels
Directory of Open Access Journals (Sweden)
Flavia Cardoso Oliva
2011-09-01
and noise exposure records were selected for this study. The 63 assessments selected were classified according to subjects' noise exposure into three levels: 79 to 84.9 dB(A, 85 to 89.9 dB(A, and 90 to 98.9 dB(A. Occurrences of hearing loss and significant auditory threshold shifts were assessed, in each group. RESULTS: Differences in the mean thresholds were observed in all test frequencies among the different groups. A significant correlation was found between occurrence of noise-induced hearing loss and duration of noise exposure (in years at the present industrial facility (R=0.373; p=0.079. Significant auditory threshold shifts were found in all three levels of noise exposure. CONCLUSION: The findings of the present study suggest the existence of an association between significant auditory threshold shifts in workers and the years of exposure to low risk noise levels.
14. Feedback strategies for wireless communication
CERN Document Server
Ozbek, Berna
2014-01-01
This book explores the different strategies regarding the feedback information for wireless communication systems. The text analyzes the impact of quantization and correlation of channel state information (CSI) on the system performance. The authors show the effect of the reduced and limited feedback information and gives an overview about the feedback strategies in the standards. This volume presents theoretical analysis as well as practical algorithms for the required feedback information at the base stations to perform adaptive resource allocation efficiently and mitigate interference coming from other cells.
15. Equal autophonic level curves under different room acoustics conditions
DEFF Research Database (Denmark)
Pelegrin Garcia, David; Mendizábal, Oier Fuentes; Brunskog, Jonas;
2011-01-01
The indirect auditory feedback from one’s own voice arises from sound reflections at the room boundaries or from sound reinforcement systems. The relative variations of indirect auditory feedback are quantified through room acoustic parameters such as the room gain and the voice support, rather...... than the reverberation time. Fourteen subjects matched the loudness level of their own voice (the autophonic level) to that of a constant and external reference sound, under different synthesized room acoustics conditions. The matching voice levels are used to build a set of equal autophonic level...... curves. These curves give an indication of the amount of variation in voice level induced by the acoustic environment as a consequence of the sidetone compensation or Lombard effect. In the range of typical rooms for speech, the variations in overall voice level that result in a constant autophonic level...
16. Selective memory retrieval of auditory what and auditory where involves the ventrolateral prefrontal cortex.
Science.gov (United States)
Kostopoulos, Penelope; Petrides, Michael
2016-02-16
There is evidence from the visual, verbal, and tactile memory domains that the midventrolateral prefrontal cortex plays a critical role in the top-down modulation of activity within posterior cortical areas for the selective retrieval of specific aspects of a memorized experience, a functional process often referred to as active controlled retrieval. In the present functional neuroimaging study, we explore the neural bases of active retrieval for auditory nonverbal information, about which almost nothing is known. Human participants were scanned with functional magnetic resonance imaging (fMRI) in a task in which they were presented with short melodies from different locations in a simulated virtual acoustic environment within the scanner and were then instructed to retrieve selectively either the particular melody presented or its location. There were significant activity increases specifically within the midventrolateral prefrontal region during the selective retrieval of nonverbal auditory information. During the selective retrieval of information from auditory memory, the right midventrolateral prefrontal region increased its interaction with the auditory temporal region and the inferior parietal lobule in the right hemisphere. These findings provide evidence that the midventrolateral prefrontal cortical region interacts with specific posterior cortical areas in the human cerebral cortex for the selective retrieval of object and location features of an auditory memory experience.
17. Feedforward and Feedback Control in Apraxia of Speech: Effects of Noise Masking on Vowel Production
Science.gov (United States)
Maas, Edwin; Mailend, Marja-Liisa; Guenther, Frank H.
2015-01-01
Purpose: This study was designed to test two hypotheses about apraxia of speech (AOS) derived from the Directions Into Velocities of Articulators (DIVA) model (Guenther et al., 2006): the feedforward system deficit hypothesis and the feedback system deficit hypothesis. Method: The authors used noise masking to minimize auditory feedback during…
18. Behind the Scenes of Auditory Perception
OpenAIRE
Shamma, Shihab A.; Micheyl, Christophe
2010-01-01
Auditory scenes” often contain contributions from multiple acoustic sources. These are usually heard as separate auditory “streams”, which can be selectively followed over time. How and where these auditory streams are formed in the auditory system is one of the most fascinating questions facing auditory scientists today. Findings published within the last two years indicate that both cortical and sub-cortical processes contribute to the formation of auditory streams, and they raise importan...
19. Continuity of visual and auditory rhythms influences sensorimotor coordination.
Directory of Open Access Journals (Sweden)
Manuel Varlet
Full Text Available People often coordinate their movement with visual and auditory environmental rhythms. Previous research showed better performances when coordinating with auditory compared to visual stimuli, and with bimodal compared to unimodal stimuli. However, these results have been demonstrated with discrete rhythms and it is possible that such effects depend on the continuity of the stimulus rhythms (i.e., whether they are discrete or continuous. The aim of the current study was to investigate the influence of the continuity of visual and auditory rhythms on sensorimotor coordination. We examined the dynamics of synchronized oscillations of a wrist pendulum with auditory and visual rhythms at different frequencies, which were either unimodal or bimodal and discrete or continuous. Specifically, the stimuli used were a light flash, a fading light, a short tone and a frequency-modulated tone. The results demonstrate that the continuity of the stimulus rhythms strongly influences visual and auditory motor coordination. Participants' movement led continuous stimuli and followed discrete stimuli. Asymmetries between the half-cycles of the movement in term of duration and nonlinearity of the trajectory occurred with slower discrete rhythms. Furthermore, the results show that the differences of performance between visual and auditory modalities depend on the continuity of the stimulus rhythms as indicated by movements closer to the instructed coordination for the auditory modality when coordinating with discrete stimuli. The results also indicate that visual and auditory rhythms are integrated together in order to better coordinate irrespective of their continuity, as indicated by less variable coordination closer to the instructed pattern. Generally, the findings have important implications for understanding how we coordinate our movements with visual and auditory environmental rhythms in everyday life.
20. Measuring Auditory Selective Attention using Frequency Tagging
Directory of Open Access Journals (Sweden)
2014-02-01
Full Text Available Frequency tagging of sensory inputs (presenting stimuli that fluctuate periodically at rates to which the cortex can phase lock has been used to study attentional modulation of neural responses to inputs in different sensory modalities. For visual inputs, the visual steady-state response (VSSR at the frequency modulating an attended object is enhanced, while the VSSR to a distracting object is suppressed. In contrast, the effect of attention on the auditory steady-state response (ASSR is inconsistent across studies. However, most auditory studies analyzed results at the sensor level or used only a small number of equivalent current dipoles to fit cortical responses. In addition, most studies of auditory spatial attention used dichotic stimuli (independent signals at the ears rather than more natural, binaural stimuli. Here, we asked whether these methodological choices help explain discrepant results. Listeners attended to one of two competing speech streams, one simulated from the left and one from the right, that were modulated at different frequencies. Using distributed source modeling of magnetoencephalography results, we estimate how spatially directed attention modulates the ASSR in neural regions across the whole brain. Attention enhances the ASSR power at the frequency of the attended stream in the contralateral auditory cortex. The attended-stream modulation frequency also drives phase-locked responses in the left (but not right precentral sulcus (lPCS, a region implicated in control of eye gaze and visual spatial attention. Importantly, this region shows no phase locking to the distracting stream suggesting that the lPCS in engaged in an attention-specific manner. Modeling results that take account of the geometry and phases of the cortical sources phase locked to the two streams (including hemispheric asymmetry of lPCS activity help partly explain why past ASSR studies of auditory spatial attention yield seemingly contradictory
1. Auditory and non-auditory effects of noise on health
NARCIS (Netherlands)
Basner, M.; Babisch, W.; Davis, A.; Brink, M.; Clark, C.; Janssen, S.A.; Stansfeld, S.
2013-01-01
Noise is pervasive in everyday life and can cause both auditory and non-auditory health eff ects. Noise-induced hearing loss remains highly prevalent in occupational settings, and is increasingly caused by social noise exposure (eg, through personal music players). Our understanding of molecular mec
2. Auditory distraction transmitted by a cochlear implant alters allocation of attentional resources
Directory of Open Access Journals (Sweden)
Mareike eFinke
2015-03-01
Full Text Available Cochlear implants (CIs are auditory prostheses which restore hearing via electrical stimulation of the auditory nerve. The successful adaptation of auditory cognition to the CI input depends to a substantial degree on individual factors. We pursued an electrophysiological approach towards an analysis of cortical responses that reflect perceptual processing stages and higher-level responses to CI input. Performance and event-related potentials on two cross-modal discrimination-following-distraction tasks from CI users and normal-hearing (NH individuals were compared. The visual-auditory distraction task combined visual distraction with following auditory discrimination performance. Here, we observed similar cortical responses to visual distractors (Novelty-N2 and slowed, less accurate auditory discrimination performance in CI users when compared to NH individuals. Conversely, the auditory-visual distraction task was used to combine auditory distraction with visual discrimination performance. In this task we found attenuated cortical responses to auditory distractors (Novelty-P3, slowed visual discrimination performance, and attenuated cortical P3-responses to visual targets in CI users compared to NH individuals. These results suggest that CI users process auditory distractors differently than NH individuals and that the presence of auditory CI input has an adverse effect on the processing of visual targets and the visual discrimination ability in implanted individuals. We propose that this attenuation of the visual modality occurs through the allocation of neural resources to the CI input.
3. A laser feedback interferometer with an oscillating feedback mirror
Institute of Scientific and Technical Information of China (English)
Wang Zhi-Guo; Wang Fei; Xiao Guang-Zong
2012-01-01
A method is proposed to solve the problem of direction discrimination for laser feedback interferometers.By vibrating the feedback mirror with a small-amplitude and high-frequency sine wave,laser intensity is modulated accordingly.The modulation amplitude can be extracted using a phase sensitive detector (PSD).When the feedback mirror moves,the PSD output shows a quasi-sine waveform similar to a laser intensity interference fringe but with a phase difference of approximately ±π/2.If the movement direction of the feedback mirror changes,the phase difference sign reverses.Therefore,the laser feedback interferometer offers a potential application in displacement measurement with a resolution of 1/8 wavelength and in-time direction discrimination.Without using optical components such as polarization beam splitters and wave plates,the interferometer is very simple,easy to align,and less costly.
4. Auditory discrimination of force of impact.
Science.gov (United States)
Lutfi, Robert A; Liu, Ching-Ju; Stoelinga, Christophe N J
2011-04-01
The auditory discrimination of force of impact was measured for three groups of listeners using sounds synthesized according to first-order equations of motion for the homogenous, isotropic bar [Morse and Ingard (1968). Theoretical Acoustics pp. 175-191]. The three groups were professional percussionists, nonmusicians, and individuals recruited from the general population without regard to musical background. In the two-interval, forced-choice procedure, listeners chose the sound corresponding to the greater force of impact as the length of the bar varied from one presentation to the next. From the equations of motion, a maximum-likelihood test for the task was determined to be of the form Δlog A + αΔ log f > 0, where A and f are the amplitude and frequency of any one partial and α = 0.5. Relative decision weights on Δ log f were obtained from the trial-by-trial responses of listeners and compared to α. Percussionists generally outperformed the other groups; however, the obtained decision weights of all listeners deviated significantly from α and showed variability within groups far in excess of the variability associated with replication. Providing correct feedback after each trial had little effect on the decision weights. The variability in these measures was comparable to that seen in studies involving the auditory discrimination of other source attributes.
5. Which Feedback Is More Effective for Pursuing Multiple Goals of Differing Importance? The Interaction Effects of Goal Importance and Performance Feedback Type on Self-Regulation and Task Achievement
Science.gov (United States)
Lee, Hyunjoo
2016-01-01
This study examined how performance feedback type (progress vs. distance) affects Korean college students' self-regulation and task achievement according to relative goal importance in the pursuit of multiple goals. For this study, 146 students participated in a computerised task. The results showed the interaction effects of goal importance and…
6. Partial Epilepsy with Auditory Features
Directory of Open Access Journals (Sweden)
J Gordon Millichap
2004-07-01
Full Text Available The clinical characteristics of 53 sporadic (S cases of idiopathic partial epilepsy with auditory features (IPEAF were analyzed and compared to previously reported familial (F cases of autosomal dominant partial epilepsy with auditory features (ADPEAF in a study at the University of Bologna, Italy.
7. Word Recognition in Auditory Cortex
Science.gov (United States)
DeWitt, Iain D. J.
2013-01-01
Although spoken word recognition is more fundamental to human communication than text recognition, knowledge of word-processing in auditory cortex is comparatively impoverished. This dissertation synthesizes current models of auditory cortex, models of cortical pattern recognition, models of single-word reading, results in phonetics and results in…
8. Associative Plasticity in the Medial Auditory Thalamus and Cerebellar Interpositus Nucleus During Eyeblink Conditioning
Science.gov (United States)
Halverson, Hunter E.; Lee, Inah; Freeman, John H.
2010-01-01
Eyeblink conditioning, a type of associative motor learning, requires the cerebellum. The medial auditory thalamus is a necessary source of stimulus input to the cerebellum during auditory eyeblink conditioning. Nothing is currently known about interactions between the thalamus and cerebellum during associative learning. In the current study, neuronal activity was recorded in the cerebellar interpositus nucleus and medial auditory thalamus simultaneously from multiple tetrodes during auditory eyeblink conditioning to examine the relative timing of learning-related plasticity within these interconnected areas. Learning-related changes in neuronal activity correlated with the eyeblink conditioned response were evident in the cerebellum before the medial auditory thalamus over the course of training and within conditioning trials, suggesting that thalamic plasticity may be driven by cerebellar feedback. Short-latency plasticity developed in the thalamus during the first conditioning session and may reflect attention to the conditioned stimulus. Extinction training resulted in a decrease in learning-related activity in both structures and an increase in inhibition within the cerebellum. A feedback projection from the cerebellar nuclei to the medial auditory thalamus was identified, which may play a role in learning by facilitating stimulus input to the cerebellum via the thalamo-pontine projection. PMID:20592200
9. Left hemispheric dominance during auditory processing in a noisy environment
Directory of Open Access Journals (Sweden)
Ross Bernhard
2007-11-01
Full Text Available Abstract Background In daily life, we are exposed to different sound inputs simultaneously. During neural encoding in the auditory pathway, neural activities elicited by these different sounds interact with each other. In the present study, we investigated neural interactions elicited by masker and amplitude-modulated test stimulus in primary and non-primary human auditory cortex during ipsi-lateral and contra-lateral masking by means of magnetoencephalography (MEG. Results We observed significant decrements of auditory evoked responses and a significant inter-hemispheric difference for the N1m response during both ipsi- and contra-lateral masking. Conclusion The decrements of auditory evoked neural activities during simultaneous masking can be explained by neural interactions evoked by masker and test stimulus in peripheral and central auditory systems. The inter-hemispheric differences of N1m decrements during ipsi- and contra-lateral masking reflect a basic hemispheric specialization contributing to the processing of complex auditory stimuli such as speech signals in noisy environments.
10. Multi-bunch Feedback Systems
CERN Document Server
Lonza, M
2014-01-01
Coupled-bunch instabilities excited by the interaction of the particle beam with its surroundings can seriously limit the performance of circular particle accelerators. These instabilities can be cured by the use of active feedback systems based on sensors capable of detecting the unwanted beam motion and actuators that apply the feedback correction to the beam. Advances in electronic technology now allow the implementation of feedback loops using programmable digital systems. Besides important advantages in terms of flexibility and reproducibility, digital systems open the way to the use of novel diagnostic tools and additional features. We first introduce coupled-bunch instabilities, analysing the equation of motion of charged particles and the different modes of oscillation of a multi-bunch beam, showing how they can be observed and measured. Different types of feedback systems will then be presented as examples of real implementations that belong to the history of multi-bunch feedback systems. The main co...
11. The Perception of Cooperativeness Without Any Visual or Auditory Communication.
Science.gov (United States)
Chang, Dong-Seon; Burger, Franziska; Bülthoff, Heinrich H; de la Rosa, Stephan
2015-12-01
Perceiving social information such as the cooperativeness of another person is an important part of human interaction. But can people perceive the cooperativeness of others even without any visual or auditory information? In a novel experimental setup, we connected two people with a rope and made them accomplish a point-collecting task together while they could not see or hear each other. We observed a consistently emerging turn-taking behavior in the interactions and installed a confederate in a subsequent experiment who either minimized or maximized this behavior. Participants experienced this only through the haptic force-feedback of the rope and made evaluations about the confederate after each interaction. We found that perception of cooperativeness was significantly affected only by the manipulation of this turn-taking behavior. Gender- and size-related judgments also significantly differed. Our results suggest that people can perceive social information such as the cooperativeness of other people even in situations where possibilities for communication are minimal.
12. Development of auditory localization accuracy and auditory spatial discrimination in children and adolescents.
Science.gov (United States)
Kühnle, S; Ludwig, A A; Meuret, S; Küttner, C; Witte, C; Scholbach, J; Fuchs, M; Rübsamen, R
2013-01-01
The present study investigated the development of two parameters of spatial acoustic perception in children and adolescents with normal hearing, aged 6-18 years. Auditory localization accuracy was quantified by means of a sound source identification task and auditory spatial discrimination acuity by measuring minimum audible angles (MAA). Both low- and high-frequency noise bursts were employed in the tests, thereby separately addressing auditory processing based on interaural time and intensity differences. Setup consisted of 47 loudspeakers mounted in the frontal azimuthal hemifield, ranging from 90° left to 90° right (-90°, +90°). Target signals were presented from 8 loudspeaker positions in the left and right hemifields (±4°, ±30°, ±60° and ±90°). Localization accuracy and spatial discrimination acuity showed different developmental courses. Localization accuracy remained stable from the age of 6 onwards. In contrast, MAA thresholds and interindividual variability of spatial discrimination decreased significantly with increasing age. Across all age groups, localization was most accurate and MAA thresholds were lower for frontal than for lateral sound sources, and for low-frequency compared to high-frequency noise bursts. The study also shows better performance in spatial hearing based on interaural time differences rather than on intensity differences throughout development. These findings confirm that specific aspects of central auditory processing show continuous development during childhood up to adolescence.
13. Peripheral Auditory Mechanisms
CERN Document Server
Hall, J; Hubbard, A; Neely, S; Tubis, A
1986-01-01
How weIl can we model experimental observations of the peripheral auditory system'? What theoretical predictions can we make that might be tested'? It was with these questions in mind that we organized the 1985 Mechanics of Hearing Workshop, to bring together auditory researchers to compare models with experimental observations. Tbe workshop forum was inspired by the very successful 1983 Mechanics of Hearing Workshop in Delft [1]. Boston University was chosen as the site of our meeting because of the Boston area's role as a center for hearing research in this country. We made a special effort at this meeting to attract students from around the world, because without students this field will not progress. Financial support for the workshop was provided in part by grant BNS- 8412878 from the National Science Foundation. Modeling is a traditional strategy in science and plays an important role in the scientific method. Models are the bridge between theory and experiment. Tbey test the assumptions made in experim...
14. Effect of auditory training on the middle latency response in children with (central) auditory processing disorder.
Science.gov (United States)
Schochat, E; Musiek, F E; Alonso, R; Ogata, J
2010-08-01
The purpose of this study was to determine the middle latency response (MLR) characteristics (latency and amplitude) in children with (central) auditory processing disorder [(C)APD], categorized as such by their performance on the central auditory test battery, and the effects of these characteristics after auditory training. Thirty children with (C)APD, 8 to 14 years of age, were tested using the MLR-evoked potential. This group was then enrolled in an 8-week auditory training program and then retested at the completion of the program. A control group of 22 children without (C)APD, composed of relatives and acquaintances of those involved in the research, underwent the same testing at equal time intervals, but were not enrolled in the auditory training program. Before auditory training, MLR results for the (C)APD group exhibited lower C3-A1 and C3-A2 wave amplitudes in comparison to the control group [C3-A1, 0.84 microV (mean), 0.39 (SD--standard deviation) for the (C)APD group and 1.18 microV (mean), 0.65 (SD) for the control group; C3-A2, 0.69 microV (mean), 0.31 (SD) for the (C)APD group and 1.00 microV (mean), 0.46 (SD) for the control group]. After training, the MLR C3-A1 [1.59 microV (mean), 0.82 (SD)] and C3-A2 [1.24 microV (mean), 0.73 (SD)] wave amplitudes of the (C)APD group significantly increased, so that there was no longer a significant difference in MLR amplitude between (C)APD and control groups. These findings suggest progress in the use of electrophysiological measurements for the diagnosis and treatment of (C)APD.
15. Effect of auditory training on the middle latency response in children with (central auditory processing disorder
Directory of Open Access Journals (Sweden)
E. Schochat
2010-08-01
Full Text Available The purpose of this study was to determine the middle latency response (MLR characteristics (latency and amplitude in children with (central auditory processing disorder [(CAPD], categorized as such by their performance on the central auditory test battery, and the effects of these characteristics after auditory training. Thirty children with (CAPD, 8 to 14 years of age, were tested using the MLR-evoked potential. This group was then enrolled in an 8-week auditory training program and then retested at the completion of the program. A control group of 22 children without (CAPD, composed of relatives and acquaintances of those involved in the research, underwent the same testing at equal time intervals, but were not enrolled in the auditory training program. Before auditory training, MLR results for the (CAPD group exhibited lower C3-A1 and C3-A2 wave amplitudes in comparison to the control group [C3-A1, 0.84 µV (mean, 0.39 (SD - standard deviation for the (CAPD group and 1.18 µV (mean, 0.65 (SD for the control group; C3-A2, 0.69 µV (mean, 0.31 (SD for the (CAPD group and 1.00 µV (mean, 0.46 (SD for the control group]. After training, the MLR C3-A1 [1.59 µV (mean, 0.82 (SD] and C3-A2 [1.24 µV (mean, 0.73 (SD] wave amplitudes of the (CAPD group significantly increased, so that there was no longer a significant difference in MLR amplitude between (CAPD and control groups. These findings suggest progress in the use of electrophysiological measurements for the diagnosis and treatment of (CAPD.
16. A unique cellular scaling rule in the avian auditory system.
Science.gov (United States)
Corfield, Jeremy R; Long, Brendan; Krilow, Justin M; Wylie, Douglas R; Iwaniuk, Andrew N
2016-06-01
Although it is clear that neural structures scale with body size, the mechanisms of this relationship are not well understood. Several recent studies have shown that the relationship between neuron numbers and brain (or brain region) size are not only different across mammalian orders, but also across auditory and visual regions within the same brains. Among birds, similar cellular scaling rules have not been examined in any detail. Here, we examine the scaling of auditory structures in birds and show that the scaling rules that have been established in the mammalian auditory pathway do not necessarily apply to birds. In galliforms, neuronal densities decrease with increasing brain size, suggesting that auditory brainstem structures increase in size faster than neurons are added; smaller brains have relatively more neurons than larger brains. The cellular scaling rules that apply to auditory brainstem structures in galliforms are, therefore, different to that found in primate auditory pathway. It is likely that the factors driving this difference are associated with the anatomical specializations required for sound perception in birds, although there is a decoupling of neuron numbers in brain structures and hair cell numbers in the basilar papilla. This study provides significant insight into the allometric scaling of neural structures in birds and improves our understanding of the rules that govern neural scaling across vertebrates.
17. Auditory-model-based Feature Extraction Method for Mechanical Faults Diagnosis
Institute of Scientific and Technical Information of China (English)
LI Yungong; ZHANG Jinping; DAI Li; ZHANG Zhanyi; LIU Jie
2010-01-01
It is well known that the human auditory system possesses remarkable capabilities to analyze and identify signals. Therefore, it would be significant to build an auditory model based on the mechanism of human auditory systems, which may improve the effects of mechanical signal analysis and enrich the methods of mechanical faults features extraction. However the existing methods are all based on explicit senses of mathematics or physics, and have some shortages on distinguishing different faults, stability, and suppressing the disturbance noise, etc. For the purpose of improving the performances of the work of feature extraction, an auditory model, early auditory(EA) model, is introduced for the first time. This auditory model transforms time domain signal into auditory spectrum via bandpass filtering, nonlinear compressing, and lateral inhibiting by simulating the principle of the human auditory system. The EA model is developed with the Gammatone filterbank as the basilar membrane. According to the characteristics of vibration signals, a method is proposed for determining the parameter of inner hair cells model of EA model. The performance of EA model is evaluated through experiments on four rotor faults, including misalignment, rotor-to-stator rubbing, oil film whirl, and pedestal looseness. The results show that the auditory spectrum, output of EA model, can effectively distinguish different faults with satisfactory stability and has the ability to suppress the disturbance noise. Then, it is feasible to apply auditory model, as a new method, to the feature extraction for mechanical faults diagnosis with effect.
18. Multimodal information Management: Evaluation of Auditory and Haptic Cues for NextGen Communication Displays
Science.gov (United States)
Begault, Durand R.; Bittner, Rachel M.; Anderson, Mark R.
2012-01-01
Auditory communication displays within the NextGen data link system may use multiple synthetic speech messages replacing traditional ATC and company communications. The design of an interface for selecting amongst multiple incoming messages can impact both performance (time to select, audit and release a message) and preference. Two design factors were evaluated: physical pressure-sensitive switches versus flat panel "virtual switches", and the presence or absence of auditory feedback from switch contact. Performance with stimuli using physical switches was 1.2 s faster than virtual switches (2.0 s vs. 3.2 s); auditory feedback provided a 0.54 s performance advantage (2.33 s vs. 2.87 s). There was no interaction between these variables. Preference data were highly correlated with performance.
19. AN OVERVIEW OF THE DEVELOPMENT OF LOW GAIN FEEDBACK AND LOW-AND-HIGH GAIN FEEDBACK
Institute of Scientific and Technical Information of China (English)
Zongli LIN
2009-01-01
Low gain feedback refers to certain families of stabilizing state feedback gains that are parameterized in a scalar and go to zero as the scalar decreases to zero. Low gain feedback was initially proposed to achieve semi-global stabilization of linear systems subject to input saturation. It was then combined with high gain feedback in different ways for solving various control problems. The resulting feedback laws are referred to as low-and-high gain feedback. Since the introduction of low gain feedback in the context of semi-global stabilization of linear systems subject to input saturation,there has been effort to develop alternative methods for low gain design, to characterize key features of low gain feedback, and to explore new applications of the low gain and low-and-high gain feedback.This paper reviews the developments in low gain and low-and-high gain feedback designs.
20. Firing-rate resonances in the peripheral auditory system of the cricket, Gryllus bimaculatus.
Science.gov (United States)
Rau, Florian; Clemens, Jan; Naumov, Victor; Hennig, R Matthias; Schreiber, Susanne
2015-11-01
In many communication systems, information is encoded in the temporal pattern of signals. For rhythmic signals that carry information in specific frequency bands, a neuronal system may profit from tuning its inherent filtering properties towards a peak sensitivity in the respective frequency range. The cricket Gryllus bimaculatus evaluates acoustic communication signals of both conspecifics and predators. The song signals of conspecifics exhibit a characteristic pulse pattern that contains only a narrow range of modulation frequencies. We examined individual neurons (AN1, AN2, ON1) in the peripheral auditory system of the cricket for tuning towards specific modulation frequencies by assessing their firing-rate resonance. Acoustic stimuli with a swept-frequency envelope allowed an efficient characterization of the cells' modulation transfer functions. Some of the examined cells exhibited tuned band-pass properties. Using simple computational models, we demonstrate how different, cell-intrinsic or network-based mechanisms such as subthreshold resonances, spike-triggered adaptation, as well as an interplay of excitation and inhibition can account for the experimentally observed firing-rate resonances. Therefore, basic neuronal mechanisms that share negative feedback as a common theme may contribute to selectivity in the peripheral auditory pathway of crickets that is designed towards mate recognition and predator avoidance.
1. Modality specific neural correlates of auditory and somatic hallucinations
Science.gov (United States)
Shergill, S; Cameron, L; Brammer, M; Williams, S; Murray, R; McGuire, P
2001-01-01
Somatic hallucinations occur in schizophrenia and other psychotic disorders, although auditory hallucinations are more common. Although the neural correlates of auditory hallucinations have been described in several neuroimaging studies, little is known of the pathophysiology of somatic hallucinations. Functional magnetic resonance imaging (fMRI) was used to compare the distribution of brain activity during somatic and auditory verbal hallucinations, occurring at different times in a 36 year old man with schizophrenia. Somatic hallucinations were associated with activation in the primary somatosensory and posterior parietal cortex, areas that normally mediate tactile perception. Auditory hallucinations were associated with activation in the middle and superior temporal cortex, areas involved in processing external speech. Hallucinations in a given modality seem to involve areas that normally process sensory information in that modality.
PMID:11606687
2. Auditory Signal Processing in Communication: Perception and Performance of Vocal Sounds
Science.gov (United States)
Prather, Jonathan F.
2013-01-01
Learning and maintaining the sounds we use in vocal communication require accurate perception of the sounds we hear performed by others and feedback-dependent imitation of those sounds to produce our own vocalizations. Understanding how the central nervous system integrates auditory and vocal-motor information to enable communication is a fundamental goal of systems neuroscience, and insights into the mechanisms of those processes will profoundly enhance clinical therapies for communication disorders. Gaining the high-resolution insight necessary to define the circuits and cellular mechanisms underlying human vocal communication is presently impractical. Songbirds are the best animal model of human speech, and this review highlights recent insights into the neural basis of auditory perception and feedback-dependent imitation in those animals. Neural correlates of song perception are present in auditory areas, and those correlates are preserved in the auditory responses of downstream neurons that are also active when the bird sings. Initial tests indicate that singing-related activity in those downstream neurons is associated with vocal-motor performance as opposed to the bird simply hearing itself sing. Therefore, action potentials related to auditory perception and action potentials related to vocal performance are co-localized in individual neurons. Conceptual models of song learning involve comparison of vocal commands and the associated auditory feedback to compute an error signal that is used to guide refinement of subsequent song performances, yet the sites of that comparison remain unknown. Convergence of sensory and motor activity onto individual neurons points to a possible mechanism through which auditory and vocal-motor signals may be linked to enable learning and maintenance of the sounds used in vocal communication. PMID:23827717
3. Feedback Perceptions and Attribution by Secretarial Employees: Effects of Feedback-Content and Sender Characteristics
Science.gov (United States)
Raemdonck, Isabel; Strijbos, Jan-Willem
2013-01-01
Purpose: Theoretical explanations for the diverse reactive feedback from secretarial employees in different career phases are relatively unexplored. However, research examining age differences in the impact of feedback suggests that the effects of performance feedback may differ for employees in the early career phase and employees in the late…
4. Cognitive mechanisms associated with auditory sensory gating
OpenAIRE
Jones, L. A.; Hills, P.J.; Dick, K.M.; Jones, S. P.; Bright, P
2015-01-01
Sensory gating is a neurophysiological measure of inhibition that is characterised by a reduction in the P50 event-related potential to a repeated identical stimulus. The objective of this work was to determine the cognitive mechanisms that relate to the neurological phenomenon of auditory sensory gating. Sixty participants underwent a battery of 10 cognitive tasks, including qualitatively different measures of attentional inhibition, working memory, and fluid intelligence. Participants addit...
5. Feedback systems for linear colliders
CERN Document Server
Hendrickson, L; Himel, Thomas M; Minty, Michiko G; Phinney, N; Raimondi, Pantaleo; Raubenheimer, T O; Shoaee, H; Tenenbaum, P G
1999-01-01
Feedback systems are essential for stable operation of a linear collider, providing a cost-effective method for relaxing tight tolerances. In the Stanford Linear Collider (SLC), feedback controls beam parameters such as trajectory, energy, and intensity throughout the accelerator. A novel dithering optimization system which adjusts final focus parameters to maximize luminosity contributed to achieving record performance in the 1997-98 run. Performance limitations of the steering feedback have been investigated, and improvements have been made. For the Next Linear Collider (NLC), extensive feedback systems are planned as an intregal part of the design. Feedback requiremetns for JLC (the Japanese Linear Collider) are essentially identical to NLC; some of the TESLA requirements are similar but there are significant differences. For NLC, algorithms which incorporate improvements upon the SLC implementation are being prototyped. Specialized systems for the damping rings, rf and interaction point will operate at hi...
6. A Typology of Written Corrective Feedback Types
Science.gov (United States)
Ellis, Rod
2009-01-01
As a basis for a systematic approach to investigating the effects of written corrective feedback, this article presents a typology of the different types available to teachers and researchers. The typology distinguishes two sets of options relating to (1) strategies for providing feedback (for example, direct, indirect, or metalinguistic feedback)…
7. Temporal factors affecting somatosensory-auditory interactions in speech processing
Directory of Open Access Journals (Sweden)
Takayuki eIto
2014-11-01
Full Text Available Speech perception is known to rely on both auditory and visual information. However, sound specific somatosensory input has been shown also to influence speech perceptual processing (Ito et al., 2009. In the present study we addressed further the relationship between somatosensory information and speech perceptual processing by addressing the hypothesis that the temporal relationship between orofacial movement and sound processing contributes to somatosensory-auditory interaction in speech perception. We examined the changes in event-related potentials in response to multisensory synchronous (simultaneous and asynchronous (90 ms lag and lead somatosensory and auditory stimulation compared to individual unisensory auditory and somatosensory stimulation alone. We used a robotic device to apply facial skin somatosensory deformations that were similar in timing and duration to those experienced in speech production. Following synchronous multisensory stimulation the amplitude of the event-related potential was reliably different from the two unisensory potentials. More importantly, the magnitude of the event-related potential difference varied as a function of the relative timing of the somatosensory-auditory stimulation. Event-related activity change due to stimulus timing was seen between 160-220 ms following somatosensory onset, mostly around the parietal area. The results demonstrate a dynamic modulation of somatosensory-auditory convergence and suggest the contribution of somatosensory information for speech processing process is dependent on the specific temporal order of sensory inputs in speech production.
8. Auditory Neuropathy: Findings of Behavioral, Physiological and Neurophysiological Tests
Directory of Open Access Journals (Sweden)
2006-12-01
Full Text Available Background and Aim: Auditory neuropathy (AN can be diagnosed by abnormal auditory brainstem response (ABR, in the presence of normal cochlear microphonic (CM and otoacoustic emissions (OAEs.The aim of this study was to investigate the ABR and other electrodiagnostic test results of 6 patients suspicious to AN with problems in speech recognition. Materials and Methods: this cross sectional study was conducted on 6 AN patients with different ages evaluated by pure tone audiometry, speech discrimination score (SDS , immittance audiometry. ElectroCochleoGraphy , ABR, middle latency response (MLR, Late latency response (LLR, and OAEs. Results: Behavioral pure tone audiometric tests showed moderate to profound hearing loss. SDS was so poor which is not in accordance with pure tone thresholds. All patients had normal tympanogram but absent acoustic reflexes. CMs and OAEs were within normal limits. There was no contra lateral suppression of OAEs. None of cases had normal ABR or MLR although LLR was recorded in 4. Conclusion: All patients in this study are typical cases of auditory neuropathy. Despite having abnormal input, LLR remains normal that indicates differences in auditory evoked potentials related to required neural synchrony. These findings show that auditory cortex may play a role in regulating presentation of deficient signals along auditory pathways in primary steps.
9. Visual speech gestures modulate efferent auditory system.
Science.gov (United States)
Namasivayam, Aravind Kumar; Wong, Wing Yiu Stephanie; Sharma, Dinaay; van Lieshout, Pascal
2015-03-01
Visual and auditory systems interact at both cortical and subcortical levels. Studies suggest a highly context-specific cross-modal modulation of the auditory system by the visual system. The present study builds on this work by sampling data from 17 young healthy adults to test whether visual speech stimuli evoke different responses in the auditory efferent system compared to visual non-speech stimuli. The descending cortical influences on medial olivocochlear (MOC) activity were indirectly assessed by examining the effects of contralateral suppression of transient-evoked otoacoustic emissions (TEOAEs) at 1, 2, 3 and 4 kHz under three conditions: (a) in the absence of any contralateral noise (Baseline), (b) contralateral noise + observing facial speech gestures related to productions of vowels /a/ and /u/ and (c) contralateral noise + observing facial non-speech gestures related to smiling and frowning. The results are based on 7 individuals whose data met strict recording criteria and indicated a significant difference in TEOAE suppression between observing speech gestures relative to the non-speech gestures, but only at the 1 kHz frequency. These results suggest that observing a speech gesture compared to a non-speech gesture may trigger a difference in MOC activity, possibly to enhance peripheral neural encoding. If such findings can be reproduced in future research, sensory perception models and theories positing the downstream convergence of unisensory streams of information in the cortex may need to be revised.
10. Auditory short-term memory in the primate auditory cortex.
Science.gov (United States)
Scott, Brian H; Mishkin, Mortimer
2016-06-01
Sounds are fleeting, and assembling the sequence of inputs at the ear into a coherent percept requires auditory memory across various time scales. Auditory short-term memory comprises at least two components: an active ׳working memory' bolstered by rehearsal, and a sensory trace that may be passively retained. Working memory relies on representations recalled from long-term memory, and their rehearsal may require phonological mechanisms unique to humans. The sensory component, passive short-term memory (pSTM), is tractable to study in nonhuman primates, whose brain architecture and behavioral repertoire are comparable to our own. This review discusses recent advances in the behavioral and neurophysiological study of auditory memory with a focus on single-unit recordings from macaque monkeys performing delayed-match-to-sample (DMS) tasks. Monkeys appear to employ pSTM to solve these tasks, as evidenced by the impact of interfering stimuli on memory performance. In several regards, pSTM in monkeys resembles pitch memory in humans, and may engage similar neural mechanisms. Neural correlates of DMS performance have been observed throughout the auditory and prefrontal cortex, defining a network of areas supporting auditory STM with parallels to that supporting visual STM. These correlates include persistent neural firing, or a suppression of firing, during the delay period of the memory task, as well as suppression or (less commonly) enhancement of sensory responses when a sound is repeated as a ׳match' stimulus. Auditory STM is supported by a distributed temporo-frontal network in which sensitivity to stimulus history is an intrinsic feature of auditory processing. This article is part of a Special Issue entitled SI: Auditory working memory.
11. Cognitive mechanisms associated with auditory sensory gating.
Science.gov (United States)
Jones, L A; Hills, P J; Dick, K M; Jones, S P; Bright, P
2016-02-01
Sensory gating is a neurophysiological measure of inhibition that is characterised by a reduction in the P50 event-related potential to a repeated identical stimulus. The objective of this work was to determine the cognitive mechanisms that relate to the neurological phenomenon of auditory sensory gating. Sixty participants underwent a battery of 10 cognitive tasks, including qualitatively different measures of attentional inhibition, working memory, and fluid intelligence. Participants additionally completed a paired-stimulus paradigm as a measure of auditory sensory gating. A correlational analysis revealed that several tasks correlated significantly with sensory gating. However once fluid intelligence and working memory were accounted for, only a measure of latent inhibition and accuracy scores on the continuous performance task showed significant sensitivity to sensory gating. We conclude that sensory gating reflects the identification of goal-irrelevant information at the encoding (input) stage and the subsequent ability to selectively attend to goal-relevant information based on that previous identification.
12. Presentation of dynamically overlapping auditory messages in user interfaces
Energy Technology Data Exchange (ETDEWEB)
Papp, III, Albert Louis [Univ. of California, Davis, CA (United States)
1997-09-01
This dissertation describes a methodology and example implementation for the dynamic regulation of temporally overlapping auditory messages in computer-user interfaces. The regulation mechanism exists to schedule numerous overlapping auditory messages in such a way that each individual message remains perceptually distinct from all others. The method is based on the research conducted in the area of auditory scene analysis. While numerous applications have been engineered to present the user with temporally overlapped auditory output, they have generally been designed without any structured method of controlling the perceptual aspects of the sound. The method of scheduling temporally overlapping sounds has been extended to function in an environment where numerous applications can present sound independently of each other. The Centralized Audio Presentation System is a global regulation mechanism that controls all audio output requests made from all currently running applications. The notion of multimodal objects is explored in this system as well. Each audio request that represents a particular message can include numerous auditory representations, such as musical motives and voice. The Presentation System scheduling algorithm selects the best representation according to the current global auditory system state, and presents it to the user within the request constraints of priority and maximum acceptable latency. The perceptual conflicts between temporally overlapping audio messages are examined in depth through the Computational Auditory Scene Synthesizer. At the heart of this system is a heuristic-based auditory scene synthesis scheduling method. Different schedules of overlapped sounds are evaluated and assigned penalty scores. High scores represent presentations that include perceptual conflicts between over-lapping sounds. Low scores indicate fewer and less serious conflicts. A user study was conducted to validate that the perceptual difficulties predicted by
13. Understanding balance differences in individuals with multiple sclerosis with mild disability: An investigation of differences in sensory feedback on postural and dynamic balance control
Science.gov (United States)
Denomme, Luke T.
Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system (CNS) and causes a broad range of neurological symptoms. One of the most common symptoms experienced by individuals with MS is poor balance control during standing and walking. The main mechanism underlying impaired balance control in MS appears to result from slowed somatosensory conduction and impaired central integration. The current thesis assessed postural and dynamic control of balance of 'individuals with MS with mild disability' (IwMS). IwMS were compared to 'healthy age-matched individuals' (HAMI) and community-dwelling 'older adults' (OA). The purpose of this thesis was to quantify differences in postural and dynamic control of balance in IwMS to the two populations who display balance control differences across the lifespan and represent two extreme ends of the balance control continuum due to natural aging. IwMS (n = 12, x¯age: 44 +/- 9.4 years), HAMI (n = 12, x¯age: 45 +/- 9.9 years) and community-dwelling OA (n = 12, x¯ age: 68.1 +/- 4.5 years) postural and dynamic balance control were evaluated during a Romberg task as well as a dynamic steering task. The Romberg task required participants to stand with their feet together and hands by their sides for 45 seconds with either their eyes open or closed. The dynamic steering task required participants to walk and change direction along the M-L plane towards a visual goal. Results from these two tasks reveal that IwMS display differences in postural control when compared to HAMI when vision was removed as well as differences in dynamic stability margin during steering situations. During the postural control task IwMS displayed faster A-P and M-L COP velocities when vision was removed and their COP position was closer to their self-selected maximum stability limits compared to HAMI. Assessment of dynamic stability during the steering task revealed that IwMS displayed reduced walking speed and cadence during the
14. Feedback as real-time constructions
DEFF Research Database (Denmark)
Keiding, Tina Bering; Qvortrup, Ane
2014-01-01
This article offers a re-description of feedback and the significance of time in feedback constructions based on systems theory. It describes feedback as internal, real-time constructions in a learning system. From this perspective, feedback is neither immediate nor delayed, but occurs in the very...... instant it takes place. This article argues for a clear distinction between the timing of communicative events, such as responses that are provided as help for feedback constructions, and the feedback construction itself as an event in a psychic system. Although feedback is described as an internal......, system-relative construction, different teaching environments offer diverse conditions for feedback constructions. The final section of this article explores this idea with the help of examples from both synchronous oral interaction and asynchronous text-based interaction mediated by digital media....
15. [Analysis of auditory information in the brain of the cetacean].
Science.gov (United States)
Popov, V V; Supin, A Ia
2006-01-01
The cetacean brain specifics involve an exceptional development of the auditory neural centres. The place of projection sensory areas including the auditory that in the cetacean brain cortex is essentially different from that in other mammals. The EP characteristics indicated presence of several functional divisions in the auditory cortex. Physiological studies of the cetacean auditory centres were mainly performed using the EP technique. Of several types of the EPs, the short-latency auditory EP was most thoroughly studied. In cetacean, it is characterised by exceptionally high temporal resolution with the integration time about 0.3 ms which corresponds to the cut-off frequency 1700 Hz. This much exceeds the temporal resolution of the hearing in terranstrial mammals. The frequency selectivity of hearing in cetacean was measured using a number of variants of the masking technique. The hearing frequency selectivity acuity in cetacean exceeds that of most terraneous mammals (excepting the bats). This acute frequency selectivity provides the differentiation among the finest spectral patterns of auditory signals.
16. Auditory Processing Disorder (For Parents)
Science.gov (United States)
... CAPD often have trouble maintaining attention, although health, motivation, and attitude also can play a role. Auditory ... programs. Several computer-assisted programs are geared toward children with APD. They mainly help the brain do ...
17. Effects of sequential streaming on auditory masking using psychoacoustics and auditory evoked potentials.
Science.gov (United States)
Verhey, Jesko L; Ernst, Stephan M A; Yasin, Ifat
2012-03-01
The present study was aimed at investigating the relationship between the mismatch negativity (MMN) and psychoacoustical effects of sequential streaming on comodulation masking release (CMR). The influence of sequential streaming on CMR was investigated using a psychoacoustical alternative forced-choice procedure and electroencephalography (EEG) for the same group of subjects. The psychoacoustical data showed, that adding precursors comprising of only off-signal-frequency maskers abolished the CMR. Complementary EEG data showed an MMN irrespective of the masker envelope correlation across frequency when only the off-signal-frequency masker components were present. The addition of such precursors promotes a separation of the on- and off-frequency masker components into distinct auditory objects preventing the auditory system from using comodulation as an additional cue. A frequency-specific adaptation changing the representation of the flanking bands in the streaming conditions may also contribute to the reduction of CMR in the stream conditions, however, it is unlikely that adaptation is the primary reason for the streaming effect. A neurophysiological correlate of sequential streaming was found in EEG data using MMN, but the magnitude of the MMN was not correlated with the audibility of the signal in CMR experiments. Dipole source analysis indicated different cortical regions involved in processing auditory streaming and modulation detection. In particular, neural sources for processing auditory streaming include cortical regions involved in decision-making.
18. 听觉皮层信号处理%Information processing in auditory cortex
Institute of Scientific and Technical Information of China (English)
王晓勤
2009-01-01
In contrast to the visual system, the auditory system has longer subcortical pathways and more spiking synapses between the peripheral receptors and the cortex. This unique organization reflects the needs of the auditory system to extract behaviorally relevant information from a complex acoustic environment using strategies different from those used by other sensory systems. The neural representations of acoustic information in auditory cortex include two types of important transformations: the non-isomorphic transformation of acoustic features and the transformation from acoustical to perceptual dimensions. Neural representations in auditory cortex are also modulated by auditory feedback and vocal control signals during speaking or vocalization. The challenges facing auditory neuroscientists and biomedical engineers are to understand neural coding mechanisms in the brain underlying such transformations. I will use recent findings from my laboratory to illustrate how acoustic information is processed in the primate auditory cortex and discuss its implications for neural processing of speech and music in the brain as well as for the design of neural prosthetic devices such as cochlear implants. We have used a combination of neurophysiological techniques and quantitative engineering tools to investigate these problems.%听觉系统和视觉系统的不同之处在于:听觉系统在外周感受器和听皮层间具有更长的皮层下通路和更多的突触联系.该特殊结构反应了听觉系统从复杂听觉环境中提取与行为相关信号的机制与其他感觉系统不同.听皮层神经信号处理包括两种重要的转换机制,声音信号的非同构转换以及从声音感受到知觉层面的转换.听觉皮层神经编码机制同时也受到听觉反馈和语言或发声过程中发声信号的调控.听觉神经科学家和生物医学工程师所面临的挑战便是如何去理解大脑中这些转换的编码机制.我将会用我实验
19. Musical experience, auditory perception and reading-related skills in children.
Directory of Open Access Journals (Sweden)
Karen Banai
Full Text Available BACKGROUND: The relationships between auditory processing and reading-related skills remain poorly understood despite intensive research. Here we focus on the potential role of musical experience as a confounding factor. Specifically we ask whether the pattern of correlations between auditory and reading related skills differ between children with different amounts of musical experience. METHODOLOGY/PRINCIPAL FINDINGS: Third grade children with various degrees of musical experience were tested on a battery of auditory processing and reading related tasks. Very poor auditory thresholds and poor memory skills were abundant only among children with no musical education. In this population, indices of auditory processing (frequency and interval discrimination thresholds were significantly correlated with and accounted for up to 13% of the variance in reading related skills. Among children with more than one year of musical training, auditory processing indices were better, yet reading related skills were not correlated with them. A potential interpretation for the reduction in the correlations might be that auditory and reading-related skills improve at different rates as a function of musical training. CONCLUSIONS/SIGNIFICANCE: Participants' previous musical training, which is typically ignored in studies assessing the relations between auditory and reading related skills, should be considered. Very poor auditory and memory skills are rare among children with even a short period of musical training, suggesting musical training could have an impact on both. The lack of correlation in the musically trained population suggests that a short period of musical training does not enhance reading related skills of individuals with within-normal auditory processing skills. Further studies are required to determine whether the associations between musical training, auditory processing and memory are indeed causal or whether children with poor auditory and
20. Spontaneous kisspeptin neuron firing in the adult mouse reveals marked sex and brain region differences but no support for a direct role in negative feedback.
Science.gov (United States)
de Croft, Simon; Piet, Richard; Mayer, Christian; Mai, Oliver; Boehm, Ulrich; Herbison, Allan E
2012-11-01
Kisspeptin-Gpr54 signaling is critical for the GnRH neuronal network controlling fertility. The present study reports on a kisspeptin (Kiss)-green fluorescent protein (GFP) mouse model enabling brain slice electrophysiological recordings to be made from Kiss neurons in the arcuate nucleus (ARN) and rostral periventricular region of the third ventricle (RP3V). Using dual immunofluorescence, approximately 90% of GFP cells in the RP3V of females, and ARN in both sexes, are shown to be authentic Kiss-synthesizing neurons in adult mice. Cell-attached recordings of ARN Kiss-GFP cells revealed a marked sex difference in their mean firing rates; 90% of Kiss-GFP cells in males exhibited slow irregular firing (0.17 ± 0.04 Hz) whereas neurons from diestrous (0.01 ± 0.01 Hz) and ovariectomized (0 Hz) mice were mostly or completely silent. In contrast, RP3V Kiss-GFP cells were all spontaneously active, exhibiting tonic, irregular, and bursting firing patterns. Mean firing rates were significantly (P neurons at the time of the proestrous GnRH surge revealed a significant decline in firing rate after the surge. Together, these observations demonstrate unexpected sex differences in the electrical activity of ARN Kiss neurons and markedly different patterns of firing by Kiss neurons in the ARN and RP3V. Although data supported a positive influence of gonadal steroids on RP3V Kiss neuron firing, no direct evidence was found to support the previously postulated role of ARN Kiss neurons in the estrogen-negative feedback mechanism.
1. Electrophysiological evidence for a general auditory prediction deficit in adults who stutter.
Science.gov (United States)
Daliri, Ayoub; Max, Ludo
2015-11-01
We previously found that stuttering individuals do not show the typical auditory modulation observed during speech planning in nonstuttering individuals. In this follow-up study, we further elucidate this difference by investigating whether stuttering speakers' atypical auditory modulation is observed only when sensory predictions are based on movement planning or also when predictable auditory input is not a consequence of one's own actions. We recorded 10 stuttering and 10 nonstuttering adults' auditory evoked potentials in response to random probe tones delivered while anticipating either speaking aloud or hearing one's own speech played back and in a control condition without auditory input (besides probe tones). N1 amplitude of nonstuttering speakers was reduced prior to both speaking and hearing versus the control condition. Stuttering speakers, however, showed no N1 amplitude reduction in either the speaking or hearing condition as compared with control. Thus, findings suggest that stuttering speakers have general auditory prediction difficulties.
2. Frequent external focus feedback enhances motor learning
Directory of Open Access Journals (Sweden)
Gabriele eWulf
2010-11-01
Full Text Available The present study examined the hypothesis that feedback inducing an external focus of attention enhances motor learning if it is provided frequently (i.e., 100% rather than less frequently. Children (10-12 year olds practiced a soccer throw-in task and were provided feedback about movement form. The feedback statements, provided either after every (100% or every third (33% practice trial, were similar in content but induced either an internal focus (body-movement related or external focus (movement-effect related. The results demonstrated that learning of the movement form was enhanced by external-focus feedback after every trial (100% relative to external-focus feedback after every third trial (33% or internal-focus feedback (100%, 33%, as demonstrated by immediate and delayed transfer tests without feedback. There was no difference between the two internal-focus feedback groups. These findings indicate that the attentional focus induced by feedback is an important factor in determining the effectiveness of different feedback frequencies. We argue that the informational properties of feedback cannot sufficiently account for these and related findings, and suggest that the attentional role of feedback be given greater consideration in future studies.
3. Clinical Observation on Treatment of Auditory Hallucinosis by Electroacupuncture--A Report of 30 Cases
Institute of Scientific and Technical Information of China (English)
Lin Hong; Li Cheng
2005-01-01
@@ Auditory hallucinosis, a kind of hallucinations in sensory disturbance, is very common in psychopathic clinic. Patients with this disorder could hear sounds of different variety or nature in the absence of any appropriate external stimulus. It is especially true in patients with schizophrenia, organic psychonosema,and alcoholic psychonosema. At present, the neuroleptic agents are often used to relieve auditory hallucinosis during treatment of the mental disease,and there is not a therapy that is effective in treating auditory hallucinosis. With electro-acupuncture, the authors have treated 30 cases of auditory hallucinosis with satisfactory results. A report follows.
4. Midbrain auditory selectivity to natural sounds.
Science.gov (United States)
Wohlgemuth, Melville J; Moss, Cynthia F
2016-03-01
This study investigated auditory stimulus selectivity in the midbrain superior colliculus (SC) of the echolocating bat, an animal that relies on hearing to guide its orienting behaviors. Multichannel, single-unit recordings were taken across laminae of the midbrain SC of the awake, passively listening big brown bat, Eptesicus fuscus. Species-specific frequency-modulated (FM) echolocation sound sequences with dynamic spectrotemporal features served as acoustic stimuli along with artificial sound sequences matched in bandwidth, amplitude, and duration but differing in spectrotemporal structure. Neurons in dorsal sensory regions of the bat SC responded selectively to elements within the FM sound sequences, whereas neurons in ventral sensorimotor regions showed broad response profiles to natural and artificial stimuli. Moreover, a generalized linear model (GLM) constructed on responses in the dorsal SC to artificial linear FM stimuli failed to predict responses to natural sounds and vice versa, but the GLM produced accurate response predictions in ventral SC neurons. This result suggests that auditory selectivity in the dorsal extent of the bat SC arises through nonlinear mechanisms, which extract species-specific sensory information. Importantly, auditory selectivity appeared only in responses to stimuli containing the natural statistics of acoustic signals used by the bat for spatial orientation-sonar vocalizations-offering support for the hypothesis that sensory selectivity enables rapid species-specific orienting behaviors. The results of this study are the first, to our knowledge, to show auditory spectrotemporal selectivity to natural stimuli in SC neurons and serve to inform a more general understanding of mechanisms guiding sensory selectivity for natural, goal-directed orienting behaviors.
5. Response recovery in the locust auditory pathway.
Science.gov (United States)
Wirtssohn, Sarah; Ronacher, Bernhard
2016-01-01
Temporal resolution and the time courses of recovery from acute adaptation of neurons in the auditory pathway of the grasshopper Locusta migratoria were investigated with a response recovery paradigm. We stimulated with a series of single click and click pair stimuli while performing intracellular recordings from neurons at three processing stages: receptors and first and second order interneurons. The response to the second click was expressed relative to the single click response. This allowed the uncovering of the basic temporal resolution in these neurons. The effect of adaptation increased with processing layer. While neurons in the auditory periphery displayed a steady response recovery after a short initial adaptation, many interneurons showed nonlinear effects: most prominent a long-lasting suppression of the response to the second click in a pair, as well as a gain in response if a click was preceded by a click a few milliseconds before. Our results reveal a distributed temporal filtering of input at an early auditory processing stage. This set of specified filters is very likely homologous across grasshopper species and thus forms the neurophysiological basis for extracting relevant information from a variety of different temporal signals. Interestingly, in terms of spike timing precision neurons at all three processing layers recovered very fast, within 20 ms. Spike waveform analysis of several neuron types did not sufficiently explain the response recovery profiles implemented in these neurons, indicating that temporal resolution in neurons located at several processing layers of the auditory pathway is not necessarily limited by the spike duration and refractory period.
6. Stroke caused auditory attention deficits in children
Directory of Open Access Journals (Sweden)
Karla Maria Ibraim da Freiria Elias
2013-01-01
Full Text Available OBJECTIVE: To verify the auditory selective attention in children with stroke. METHODS: Dichotic tests of binaural separation (non-verbal and consonant-vowel and binaural integration - digits and Staggered Spondaic Words Test (SSW - were applied in 13 children (7 boys, from 7 to 16 years, with unilateral stroke confirmed by neurological examination and neuroimaging. RESULTS: The attention performance showed significant differences in comparison to the control group in both kinds of tests. In the non-verbal test, identifications the ear opposite the lesion in the free recall stage was diminished and, in the following stages, a difficulty in directing attention was detected. In the consonant- vowel test, a modification in perceptual asymmetry and difficulty in focusing in the attended stages was found. In the digits and SSW tests, ipsilateral, contralateral and bilateral deficits were detected, depending on the characteristics of the lesions and demand of the task. CONCLUSION: Stroke caused auditory attention deficits when dealing with simultaneous sources of auditory information.
7. Hierarchical processing of auditory objects in humans.
Directory of Open Access Journals (Sweden)
Sukhbinder Kumar
2007-06-01
Full Text Available This work examines the computational architecture used by the brain during the analysis of the spectral envelope of sounds, an important acoustic feature for defining auditory objects. Dynamic causal modelling and Bayesian model selection were used to evaluate a family of 16 network models explaining functional magnetic resonance imaging responses in the right temporal lobe during spectral envelope analysis. The models encode different hypotheses about the effective connectivity between Heschl's Gyrus (HG, containing the primary auditory cortex, planum temporale (PT, and superior temporal sulcus (STS, and the modulation of that coupling during spectral envelope analysis. In particular, we aimed to determine whether information processing during spectral envelope analysis takes place in a serial or parallel fashion. The analysis provides strong support for a serial architecture with connections from HG to PT and from PT to STS and an increase of the HG to PT connection during spectral envelope analysis. The work supports a computational model of auditory object processing, based on the abstraction of spectro-temporal "templates" in the PT before further analysis of the abstracted form in anterior temporal lobe areas.
8. Auditory function in vestibular migraine
Directory of Open Access Journals (Sweden)
John Mathew
2016-01-01
Full Text Available Introduction: Vestibular migraine (VM is a vestibular syndrome seen in patients with migraine and is characterized by short spells of spontaneous or positional vertigo which lasts between a few seconds to weeks. Migraine and VM are considered to be a result of chemical abnormalities in the serotonin pathway. Neuhauser′s diagnostic criteria for vestibular migraine is widely accepted. Research on VM is still limited and there are few studies which have been published on this topic. Materials and Methods: This study has two parts. In the first part, we did a retrospective chart review of eighty consecutive patients who were diagnosed with vestibular migraine and determined the frequency of auditory dysfunction in these patients. The second part was a prospective case control study in which we compared the audiological parameters of thirty patients diagnosed with VM with thirty normal controls to look for any significant differences. Results: The frequency of vestibular migraine in our population is 22%. The frequency of hearing loss in VM is 33%. Conclusion: There is a significant difference between cases and controls with regards to the presence of distortion product otoacoustic emissions in both ears. This finding suggests that the hearing loss in VM is cochlear in origin.
9. Frequency-specific modulation of population-level frequency tuning in human auditory cortex
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Roberts Larry E
2009-01-01
Full Text Available Abstract Background Under natural circumstances, attention plays an important role in extracting relevant auditory signals from simultaneously present, irrelevant noises. Excitatory and inhibitory neural activity, enhanced by attentional processes, seems to sharpen frequency tuning, contributing to improved auditory performance especially in noisy environments. In the present study, we investigated auditory magnetic fields in humans that were evoked by pure tones embedded in band-eliminated noises during two different stimulus sequencing conditions (constant vs. random under auditory focused attention by means of magnetoencephalography (MEG. Results In total, we used identical auditory stimuli between conditions, but presented them in a different order, thereby manipulating the neural processing and the auditory performance of the listeners. Constant stimulus sequencing blocks were characterized by the simultaneous presentation of pure tones of identical frequency with band-eliminated noises, whereas random sequencing blocks were characterized by the simultaneous presentation of pure tones of random frequencies and band-eliminated noises. We demonstrated that auditory evoked neural responses were larger in the constant sequencing compared to the random sequencing condition, particularly when the simultaneously presented noises contained narrow stop-bands. Conclusion The present study confirmed that population-level frequency tuning in human auditory cortex can be sharpened in a frequency-specific manner. This frequency-specific sharpening may contribute to improved auditory performance during detection and processing of relevant sound inputs characterized by specific frequency distributions in noisy environments.
10. Auditory Sketches: Very Sparse Representations of Sounds Are Still Recognizable.
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Vincent Isnard
Full Text Available Sounds in our environment like voices, animal calls or musical instruments are easily recognized by human listeners. Understanding the key features underlying this robust sound recognition is an important question in auditory science. Here, we studied the recognition by human listeners of new classes of sounds: acoustic and auditory sketches, sounds that are severely impoverished but still recognizable. Starting from a time-frequency representation, a sketch is obtained by keeping only sparse elements of the original signal, here, by means of a simple peak-picking algorithm. Two time-frequency representations were compared: a biologically grounded one, the auditory spectrogram, which simulates peripheral auditory filtering, and a simple acoustic spectrogram, based on a Fourier transform. Three degrees of sparsity were also investigated. Listeners were asked to recognize the category to which a sketch sound belongs: singing voices, bird calls, musical instruments, and vehicle engine noises. Results showed that, with the exception of voice sounds, very sparse representations of sounds (10 features, or energy peaks, per second could be recognized above chance. No clear differences could be observed between the acoustic and the auditory sketches. For the voice sounds, however, a completely different pattern of results emerged, with at-chance or even below-chance recognition performances, suggesting that the important features of the voice, whatever they are, were removed by the sketch process. Overall, these perceptual results were well correlated with a model of auditory distances, based on spectro-temporal excitation patterns (STEPs. This study confirms the potential of these new classes of sounds, acoustic and auditory sketches, to study sound recognition.
11. Auditory Sketches: Very Sparse Representations of Sounds Are Still Recognizable.
Science.gov (United States)
Isnard, Vincent; Taffou, Marine; Viaud-Delmon, Isabelle; Suied, Clara
2016-01-01
Sounds in our environment like voices, animal calls or musical instruments are easily recognized by human listeners. Understanding the key features underlying this robust sound recognition is an important question in auditory science. Here, we studied the recognition by human listeners of new classes of sounds: acoustic and auditory sketches, sounds that are severely impoverished but still recognizable. Starting from a time-frequency representation, a sketch is obtained by keeping only sparse elements of the original signal, here, by means of a simple peak-picking algorithm. Two time-frequency representations were compared: a biologically grounded one, the auditory spectrogram, which simulates peripheral auditory filtering, and a simple acoustic spectrogram, based on a Fourier transform. Three degrees of sparsity were also investigated. Listeners were asked to recognize the category to which a sketch sound belongs: singing voices, bird calls, musical instruments, and vehicle engine noises. Results showed that, with the exception of voice sounds, very sparse representations of sounds (10 features, or energy peaks, per second) could be recognized above chance. No clear differences could be observed between the acoustic and the auditory sketches. For the voice sounds, however, a completely different pattern of results emerged, with at-chance or even below-chance recognition performances, suggesting that the important features of the voice, whatever they are, were removed by the sketch process. Overall, these perceptual results were well correlated with a model of auditory distances, based on spectro-temporal excitation patterns (STEPs). This study confirms the potential of these new classes of sounds, acoustic and auditory sketches, to study sound recognition.
12. Coding of melodic gestalt in human auditory cortex.
Science.gov (United States)
Schindler, Andreas; Herdener, Marcus; Bartels, Andreas
2013-12-01
The perception of a melody is invariant to the absolute properties of its constituting notes, but depends on the relation between them-the melody's relative pitch profile. In fact, a melody's "Gestalt" is recognized regardless of the instrument or key used to play it. Pitch processing in general is assumed to occur at the level of the auditory cortex. However, it is unknown whether early auditory regions are able to encode pitch sequences integrated over time (i.e., melodies) and whether the resulting representations are invariant to specific keys. Here, we presented participants different melodies composed of the same 4 harmonic pitches during functional magnetic resonance imaging recordings. Additionally, we played the same melodies transposed in different keys and on different instruments. We found that melodies were invariantly represented by their blood oxygen level-dependent activation patterns in primary and secondary auditory cortices across instruments, and also across keys. Our findings extend common hierarchical models of auditory processing by showing that melodies are encoded independent of absolute pitch and based on their relative pitch profile as early as the primary auditory cortex.
13. A hardware model of the auditory periphery to transduce acoustic signals into neural activity
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Takashi eTateno
2013-11-01
Full Text Available To improve the performance of cochlear implants, we have integrated a microdevice into a model of the auditory periphery with the goal of creating a microprocessor. We constructed an artificial peripheral auditory system using a hybrid model in which polyvinylidene difluoride was used as a piezoelectric sensor to convert mechanical stimuli into electric signals. To produce frequency selectivity, the slit on a stainless steel base plate was designed such that the local resonance frequency of the membrane over the slit reflected the transfer function. In the acoustic sensor, electric signals were generated based on the piezoelectric effect from local stress in the membrane. The electrodes on the resonating plate produced relatively large electric output signals. The signals were fed into a computer model that mimicked some functions of inner hair cells, inner hair cell–auditory nerve synapses, and auditory nerve fibers. In general, the responses of the model to pure-tone burst and complex stimuli accurately represented the discharge rates of high-spontaneous-rate auditory nerve fibers across a range of frequencies greater than 1 kHz and middle to high sound pressure levels. Thus, the model provides a tool to understand information processing in the peripheral auditory system and a basic design for connecting artificial acoustic sensors to the peripheral auditory nervous system. Finally, we discuss the need for stimulus control with an appropriate model of the auditory periphery based on auditory brainstem responses that were electrically evoked by different temporal pulse patterns with the same pulse number.
14. Potencial evocado auditivo de longa latência para estímulo de fala apresentado com diferentes transdutores em crianças ouvintes Late auditory evoked potentials to speech stimuli presented with different transducers in hearing children
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Raquel Sampaio Agostinho-Pesse
2013-01-01
rate of 1.9 stimuli per second. Whenever present, P1, N1 and P2 components were analyzed as to latency and amplitude. RESULTS: it was found a strong level of agreement between the researcher and the judge. There was no statistically significant difference when comparing the values of latency and amplitude of the P1, N1 and P2 components, when considering gender and ear, as well as the latency of components when considering the types of transducers. However, there was a statistically significant difference for the amplitude of the P1 and N1 components with greater amplitude for the speaker transducer. CONCLUSION: the latency values of the P1, N1 and P2 components and P2 amplitude obtained with insertion phone may be used as normal reference independent of the transducer used for the recording of auditory evoked potentials of long latency.
15. Listen, you are writing!Speeding up online spelling with a dynamic auditory BCI
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Martijn eSchreuder
2011-10-01
Full Text Available Representing an intuitive spelling interface for Brain-Computer Interfaces (BCI in the auditory domain is not straightforward. In consequence, all existing approaches based on event-related potentials (ERP rely at least partially on a visual representation of the interface. This online study introduces an auditory spelling interface that eliminates the necessity for such a visualization. In up to two sessions, a group of healthy subjects (N=21 was asked to use a text entry application, utilizing the spatial cues of the AMUSE paradigm (Auditory Multiclass Spatial ERP. The speller relies on the auditory sense both for stimulation and the core feedback. Without prior BCI experience, 76% of the participants were able to write a full sentence during the first session. By exploiting the advantages of a newly introduced dynamic stopping method, a maximum writing speed of 1.41 characters/minute (7.55 bits/minute could be reached during the second session (average: .94 char/min, 5.26 bits/min. For the first time, the presented work shows that an auditory BCI can reach performances similar to state-of-the-art visual BCIs based on covert attention. These results represent an important step towards a purely auditory BCI.
16. How Should Different Types of Feedback Be Administered to Create More Effective Learning among Advanced ESL Writing Students? A Student Perspective
Science.gov (United States)
Bao, Ze
2015-01-01
This paper is set in the context of my experience in advanced ESL writing classes at two Canadian universities. Based on my experience and the research literature, several types of feedback should be administered by teachers to create more effective learning opportunities among advanced ESL writing students. In this paper, I examine the advantages…
17. Representation of lateralization and tonotopy in primary versus secondary human auditory cortex
NARCIS (Netherlands)
Langers, Dave R. M.; Backes, Walter H.; van Dijk, Pim
2007-01-01
Functional MRI was performed to investigate differences in the basic functional organization of the primary and secondary auditory cortex regarding preferred stimulus lateratization and frequency. A modified sparse acquisition scheme was used to spatially map the characteristics of the auditory cort
18. Interaction of speech and script in human auditory cortex: insights from neuro-imaging and effective connectivity.
Science.gov (United States)
van Atteveldt, Nienke; Roebroeck, Alard; Goebel, Rainer
2009-12-01
In addition to visual information from the face of the speaker, a less natural, but nowadays extremely important visual component of speech is its representation in script. In this review, neuro-imaging studies are examined which were aimed to understand how speech and script are associated in the adult "literate" brain. The reviewed studies focused on the role of different stimulus and task factors and effective connectivity between different brain regions. The studies will be summarized in a neural mechanism for the integration of speech and script that can serve as a basis for future studies addressing (the failure of) literacy acquisition. In this proposed mechanism, speech sound processing in auditory cortex is modulated by co-presented visual letters, depending on the congruency of the letter-sound pairs. Other factors of influence are temporal correspondence, input quality and task instruction. We present results showing that the modulation of auditory cortex is most likely mediated by feedback from heteromodal areas in the superior temporal cortex, but direct influences from visual cortex are not excluded. The influence of script on speech sound processing occurs automatically and shows extended development during reading acquisition. This review concludes with suggestions to answer currently still open questions to get closer to understanding the neural basis of normal and impaired literacy.
19. The tool of microbial genomics research for interpreting the lability of permafrost carbon and potential greenhouse gas feedbacks at different scales of resolution.
Science.gov (United States)
Waldrop, M. P.; Machelprang, R.; Hultman, J.; Wickland, K. P.
2012-12-01
One quarter of the earth's terrestrial surface is underlain by permafrost, or perennially frozen soils. Permafrost soils contain approximately 25% to 50% of the total global soil carbon pool nearly double the atmospheric carbon (C) reservoir. Decomposition of this C by microorganisms may produce globally significant quantities of both carbon dioxide and methane. These processes provide a positive feedback between climate change and the altered biogeochemistry of northern ecosystems. The fate of carbon residing in thawing permafrost soils depends on a number of physical factors including the thermal properties of soils (which affect heat flow rates), its disturbance regime (controlling changes in physical properties), and hydrologic regime (where soil-water interactions can rapidly thaw permafrost). Yet the mechanism of soil organic matter decomposition and greenhouse gas production operates primarily through the microbial loop: growth, carbon and nutrient mineralization, electron transfer, and enzyme production. We tested whether molecular analysis of microbial communities can be utilized as an indicator of permafrost C lability and potential greenhouse gas production from permafrost soils across multiple temporal and spatial scales. For short term studies of lability we compared rates of C turnover in soil incubations to chemical indices of soil lability, soil enzymes, and the abundance of soil microbial populations. Permafrost soils for the incubation ranged from frozen peatlands to dry uplands and Pleistocene Yedoma. For analysis at the annual to decadal scale, we utilized a permafrost thaw gradient at the Bonanza Creek LTER near Fairbanks Alaska. At this gradient, a Black Spruce forest underlain by permafrost thawed to form a thermokarst bog growth and energy. At the decadal scale, permafrost thaw will result in wholesale change in plant community composition and ecosystem function, thus relying on an entirely different interpretation of shifts in microbial
20. Evaluation of Multi-sensory Feedback on the Usability of a Virtual Assembly Environment
Directory of Open Access Journals (Sweden)
Ying Zhang
2007-02-01
Full Text Available Virtual assembly environment (VAE technology has the great potential for benefiting the manufacturing applications in industry. Usability is an important aspect of the VAE. This paper presents the usability evaluation of a developed multi-sensory VAE. The evaluation is conducted by using its three attributes: (a efficiency of use; (b user satisfaction; and (c reliability. These are addressed by using task completion times (TCTs, questionnaires, and human performance error rates (HPERs, respectively. A peg-in-a-hole and a Sener electronic box assembly task have been used to perform the experiments, using sixteen participants. The outcomes showed that the introduction of 3D auditory and/or visual feedback could improve the usability. They also indicated that the integrated feedback (visual plus auditory offered better usability than either feedback used in isolation. Most participants preferred the integrated feedback to either feedback (visual or auditory or no feedback. The participants’ comments demonstrated that nonrealistic or inappropriate feedback had negative effects on the usability, and easily made them feel frustrated. The possible reasons behind the outcomes are also analysed.
1. Auditory Hallucinations in Acute Stroke
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Yair Lampl
2005-01-01
Full Text Available Auditory hallucinations are uncommon phenomena which can be directly caused by acute stroke, mostly described after lesions of the brain stem, very rarely reported after cortical strokes. The purpose of this study is to determine the frequency of this phenomenon. In a cross sectional study, 641 stroke patients were followed in the period between 1996–2000. Each patient underwent comprehensive investigation and follow-up. Four patients were found to have post cortical stroke auditory hallucinations. All of them occurred after an ischemic lesion of the right temporal lobe. After no more than four months, all patients were symptom-free and without therapy. The fact the auditory hallucinations may be of cortical origin must be taken into consideration in the treatment of stroke patients. The phenomenon may be completely reversible after a couple of months.
2. Corrective feedback, learner uptake, and feedback perception in a Chinese as a foreign language classroom
Directory of Open Access Journals (Sweden)
Tingfeng Fu
2016-03-01
Full Text Available The role of corrective feedback in second language classrooms has received considerable research attention in the past few decades. However, most of this research has been conducted in English-teaching settings, either ESL or EFL. This study examined teacher feedback, learner uptake as well as learner and teacher perception of feedback in an adult Chinese as a foreign language classroom. Ten hours of classroom interactions were videotaped, transcribed and coded for analysis. Lyster and Ranta’s (1997 coding system involving six types of feedback was initially used to identify feedback frequency and learner uptake. However, the teacher was found to use a number of additional feedback types. Altogether, 12 types of feedback were identified: recasts, delayed recasts, clarification requests, translation, metalinguistic feedback, elicitation, explicit correction, asking a direct question, repetition, directing question to other students, re-asks, and using L1-English. Differences were noted in the frequency of some of the feedback types as well as learner uptake compared to what had been reported in some previous ESL and EFL studies. With respect to the new feedback types, some led to noticeable uptake. As for the students’ and teacher’s perceptions, they did not match and both the teacher and the students were generally not accurate in perceiving the frequency of each feedback type. The findings are discussed in terms of the role of context in affecting the provision and effectiveness of feedback and its relationship to student and teacher perception of feedback.
3. Visual and auditory perception in preschool children at risk for dyslexia.
Science.gov (United States)
Ortiz, Rosario; Estévez, Adelina; Muñetón, Mercedes; Domínguez, Carolina
2014-11-01
Recently, there has been renewed interest in perceptive problems of dyslexics. A polemic research issue in this area has been the nature of the perception deficit. Another issue is the causal role of this deficit in dyslexia. Most studies have been carried out in adult and child literates; consequently, the observed deficits may be the result rather than the cause of dyslexia. This study addresses these issues by examining visual and auditory perception in children at risk for dyslexia. We compared children from preschool with and without risk for dyslexia in auditory and visual temporal order judgment tasks and same-different discrimination tasks. Identical visual and auditory, linguistic and nonlinguistic stimuli were presented in both tasks. The results revealed that the visual as well as the auditory perception of children at risk for dyslexia is impaired. The comparison between groups in auditory and visual perception shows that the achievement of children at risk was lower than children without risk for dyslexia in the temporal tasks. There were no differences between groups in auditory discrimination tasks. The difficulties of children at risk in visual and auditory perceptive processing affected both linguistic and nonlinguistic stimuli. Our conclusions are that children at risk for dyslexia show auditory and visual perceptive deficits for linguistic and nonlinguistic stimuli. The auditory impairment may be explained by temporal processing problems and these problems are more serious for processing language than for processing other auditory stimuli. These visual and auditory perceptive deficits are not the consequence of failing to learn to read, thus, these findings support the theory of temporal processing deficit.
4. Time computations in anuran auditory systems
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Gary J Rose
2014-05-01
Full Text Available Temporal computations are important in the acoustic communication of anurans. In many cases, calls between closely related species are nearly identical spectrally but differ markedly in temporal structure. Depending on the species, calls can differ in pulse duration, shape and/or rate (i.e., amplitude modulation, direction and rate of frequency modulation, and overall call duration. Also, behavioral studies have shown that anurans are able to discriminate between calls that differ in temporal structure. In the peripheral auditory system, temporal information is coded primarily in the spatiotemporal patterns of activity of auditory-nerve fibers. However, major transformations in the representation of temporal information occur in the central auditory system. In this review I summarize recent advances in understanding how temporal information is represented in the anuran midbrain, with particular emphasis on mechanisms that underlie selectivity for pulse duration and pulse rate (i.e., intervals between onsets of successive pulses. Two types of neurons have been identified that show selectivity for pulse rate: long-interval cells respond well to slow pulse rates but fail to spike or respond phasically to fast pulse rates; conversely, interval-counting neurons respond to intermediate or fast pulse rates, but only after a threshold number of pulses, presented at optimal intervals, have occurred. Duration-selectivity is manifest as short-pass, band-pass or long-pass tuning. Whole-cell patch recordings, in vivo, suggest that excitation and inhibition are integrated in diverse ways to generate temporal selectivity. In many cases, activity-related enhancement or depression of excitatory or inhibitory processes appear to contribute to selective responses.
5. Fault Tolerant Feedback Control
DEFF Research Database (Denmark)
Stoustrup, Jakob; Niemann, H.
2001-01-01
An architecture for fault tolerant feedback controllers based on the Youla parameterization is suggested. It is shown that the Youla parameterization will give a residual vector directly in connection with the fault diagnosis part of the fault tolerant feedback controller. It turns out...... that there is a separation be-tween the feedback controller and the fault tolerant part. The closed loop feedback properties are handled by the nominal feedback controller and the fault tolerant part is handled by the design of the Youla parameter. The design of the fault tolerant part will not affect the design...... of the nominal feedback con-troller....
6. The use of visual stimuli during auditory assessment.
Science.gov (United States)
Pearlman, R C; Cunningham, D R; Williamson, D G; Amerman, J D
1975-01-01
Two groups of male subjects beyond 50 years of age were given audiometric tasks with and without visual stimulation to determine if visual stimuli changed auditory perception. The first group consisted of 10 subjects with normal auditory acuity; the second, 10 with sensorineural hearing losses greater than 30 decibels. The rate of presentation of the visual stimuli, consisting of photographic slides of various subjects, was determined in experiment I of the study. The subjects, while viewing the slides at their own rate, took an audiotry speech discrimination test. Advisedly they changed the slides at a speed which they felt facilitated attention while performing the auditory task. The mean rate of slide-changing behavior was used as the "optimum" visual stimulation rate in experiment II, which was designed to explore the interaction of the bisensory presentation of stimuli. Bekesy tracings and Rush Hughes recordings were administered without and with visual stimuli, the latter presented at the mean rate of slide changes found in experiment I. Analysis of data indicated that (1) no statistically significant difference exists between visual and nonvisual conditions during speech discrimination and Bekesy testing; and (2) subjects did not believe that visual stimuli as presented in this study helped them to listen more effectively. The experimenter concluded that the various auditory stimuli encountered in the auditory test situation may actually be a deterrent to boredom because of the variety of tasks required in a testing situation.
7. The auditory attention status in Iranian bilingual and monolingual people
Directory of Open Access Journals (Sweden)
Nayiere Mansoori
2013-05-01
Full Text Available Background and Aim: Bilingualism, as one of the discussing issues of psychology and linguistics, can influence the speech processing. Of several tests for assessing auditory processing, dichotic digit test has been designed to study divided auditory attention. Our study was performed to compare the auditory attention between Iranian bilingual and monolingual young adults. Methods: This cross-sectional study was conducted on 60 students including 30 Turkish-Persian bilinguals and 30 Persian monolinguals aged between 18 to 30 years in both genders. Dichotic digit test was performed on young individuals with normal peripheral hearing and right hand preference. Results: No significant correlation was found between the results of dichotic digit test of monolinguals and bilinguals (p=0.195, and also between the results of right and left ears in monolingual (p=0.460 and bilingual (p=0.054 groups. The mean score of women was significantly more than men (p=0.031. Conclusion: There was no significant difference between bilinguals and monolinguals in divided auditory attention; and it seems that acquisition of second language in lower ages has no noticeable effect on this type of auditory attention.
8. Effect of background music on auditory-verbal memory performance
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Sona Matloubi
2014-12-01
Full Text Available Background and Aim: Music exists in all cultures; many scientists are seeking to understand how music effects cognitive development such as comprehension, memory, and reading skills. More recently, a considerable number of neuroscience studies on music have been developed. This study aimed to investigate the effects of null and positive background music in comparison with silence on auditory-verbal memory performance.Methods: Forty young adults (male and female with normal hearing, aged between 18 and 26, participated in this comparative-analysis study. An auditory and speech evaluation was conducted in order to investigate the effects of background music on working memory. Subsequently, the Rey auditory-verbal learning test was performed for three conditions: silence, positive, and null music.Results: The mean score of the Rey auditory-verbal learning test in silence condition was higher than the positive music condition (p=0.003 and the null music condition (p=0.01. The tests results did not reveal any gender differences.Conclusion: It seems that the presence of competitive music (positive and null music and the orientation of auditory attention have negative effects on the performance of verbal working memory. It is possibly owing to the intervention of music with verbal information processing in the brain.
9. Effects of Background Music on Objective and Subjective Performance Measures in an Auditory BCI
Science.gov (United States)
Zhou, Sijie; Allison, Brendan Z.; Kübler, Andrea; Cichocki, Andrzej; Wang, Xingyu; Jin, Jing
2016-01-01
Several studies have explored brain computer interface (BCI) systems based on auditory stimuli, which could help patients with visual impairments. Usability and user satisfaction are important considerations in any BCI. Although background music can influence emotion and performance in other task environments, and many users may wish to listen to music while using a BCI, auditory, and other BCIs are typically studied without background music. Some work has explored the possibility of using polyphonic music in auditory BCI systems. However, this approach requires users with good musical skills, and has not been explored in online experiments. Our hypothesis was that an auditory BCI with background music would be preferred by subjects over a similar BCI without background music, without any difference in BCI performance. We introduce a simple paradigm (which does not require musical skill) using percussion instrument sound stimuli and background music, and evaluated it in both offline and online experiments. The result showed that subjects preferred the auditory BCI with background music. Different performance measures did not reveal any significant performance effect when comparing background music vs. no background. Since the addition of background music does not impair BCI performance but is preferred by users, auditory (and perhaps other) BCIs should consider including it. Our study also indicates that auditory BCIs can be effective even if the auditory channel is simultaneously otherwise engaged. PMID:27790111
10. Auditory presentation and synchronization in Adobe Flash and HTML5/JavaScript Web experiments.
Science.gov (United States)
Reimers, Stian; Stewart, Neil
2016-09-01
Substantial recent research has examined the accuracy of presentation durations and response time measurements for visually presented stimuli in Web-based experiments, with a general conclusion that accuracy is acceptable for most kinds of experiments. However, many areas of behavioral research use auditory stimuli instead of, or in addition to, visual stimuli. Much less is known about auditory accuracy using standard Web-based testing procedures. We used a millisecond-accurate Black Box Toolkit to measure the actual durations of auditory stimuli and the synchronization of auditory and visual presentation onsets. We examined the distribution of timings for 100 presentations of auditory and visual stimuli across two computers with difference specs, three commonly used browsers, and code written in either Adobe Flash or JavaScript. We also examined different coding options for attempting to synchronize the auditory and visual onsets. Overall, we found that auditory durations were very consistent, but that the lags between visual and auditory onsets varied substantially across browsers and computer systems.
11. ON FEEDBACK CONTROL OF DELAYED CHAOTIC SYSTEM
Institute of Scientific and Technical Information of China (English)
李丽香; 彭海朋; 卢辉斌; 关新平
2001-01-01
In this paper two different types of feedback control technique are discussed: the standard feedback control and the time-delay feedback control which have been successfully used in many control systems. In order to understand to what extent the two different types of control technique are useful in delayed chaotic systems, some analytic stabilization conditions for chaos control from the two types of control technique are derived based on Lyapunov stabilization arguments. Similarly, we discuss the tracking problem by applying the time-delay feedback control. Finally, numerical examples are provided.
12. Feedback on floods in Var, south of France, 15th June 2010 : different societal impacts and responses linked to levels of prevention, organization and information
Science.gov (United States)
Moreau, K.; Roumagnac, A.
2010-09-01
Observing the last dramatical floods in Var in south of France on 15th June 2010, very differents responses and impacts can be identified. 23 death, people missing, more than 50 communities impacted, 700 Millions Euros of damages were to declare after the event. Most of human loss, 12 people, were to deplore in Draguignan in Var were 270 mm of rainfall were registered in the city center. This tragedy reminds all the necessity of prevention, organization and communication. In term of flood disaster, the fact is that physical protection is necessary but inevitably limited. To manage these kinds of crisis, local authorities need to be able to base their policy against flood on prevention, warnings, post-crisis analysis and feedback from former experience. While many damages were observed in Draguignan, the event was different in Hyères, Sainte-Maxime, Cogolin, Grimaud or Toulon who behaved to face it by minimizing the effects, and economic impacts of the flood. The fact is that they had prepared their organization to face flood crisis, they had informed the population of what had to be done, they had given security advices, they had reacted from the vigilance information and kept on being informed during the event to adapt their plans and actions: opening security centers, closing roads before they get flooded, evacuating when necessary. The most relevant example is in Sainte-Maxime where 260 mm of rainfall were registered in the city center, a volume close to the 270 mm registered in Draguignan during the same event. In Sainte-Maxime, no human loss was to deplore, the community was informed, had the information of rainfall intensity and rainfall effects in anticipation and could inform the citizen with the help of the police circulating and communicating in the streets. Getting informed the citizen could elevate and protect their property, evacuate their cars on the hights of the community, and secure themselves and family. Comparing this event with what happened in
13. Exploring the value of usability feedback formats
DEFF Research Database (Denmark)
Nørgaard, Mie; Hornbæk, Kasper Anders Søren
2009-01-01
The format used to present feedback from usability evaluations to developers affects whether problems are understood, accepted, and fixed. Yet, little research has investigated which formats are the most effective. We describe an explorative study where three developers assess 40 usability findings...... presented using five feedback formats. Our usability findings comprise 35 problems and 5 positive comments. Data suggest that feedback serves multiple purposes. Initially, feedback must convince developers about the relevance of a problem and convey an understanding of this. Feedback must next be easy...... working with the feedback to address the usability problems, there were no significant differences among the developers' ratings of the value of the different formats. This suggests that all of the formats may serve equally well as reminders in later stages of working with usability problems...
14. Auditory Memory deficit in Elderly People with Hearing Loss
Directory of Open Access Journals (Sweden)
Zahra Shahidipour
2013-06-01
Full Text Available Introduction: Hearing loss is one of the most common problems in elderly people. Functional side effects of hearing loss are various. Due to the fact that hearing loss is the common impairment in elderly people; the importance of its possible effects on auditory memory is undeniable. This study aims to focus on the hearing loss effects on auditory memory. Materials and Methods: Dichotic Auditory Memory Test (DVMT was performed on 47 elderly people, aged 60 to 80; that were divided in two groups, the first group consisted of elderly people with hearing range of 24 normal and the second one consisted of 23 elderly people with bilateral symmetrical ranged from mild to moderate Sensorineural hearing loss in the high frequency due to aging in both genders. Results: Significant difference was observed in DVMT between elderly people with normal hearing and those with hearing loss (P
15. Robust speech features representation based on computational auditory model
Institute of Scientific and Technical Information of China (English)
LU Xugang; JIA Chuan; DANG Jianwu
2004-01-01
A speech signal processing and features extracting method based on computational auditory model is proposed. The computational model is based on psychological, physiological knowledge and digital signal processing methods. In each stage of a hearing perception system, there is a corresponding computational model to simulate its function. Based on this model, speech features are extracted. In each stage, the features in different kinds of level are extracted. A further processing for primary auditory spectrum based on lateral inhibition is proposed to extract much more robust speech features. All these features can be regarded as the internal representations of speech stimulation in hearing system. The robust speech recognition experiments are conducted to test the robustness of the features. Results show that the representations based on the proposed computational auditory model are robust representations for speech signals.
16. Impaired timing adjustments in response to time-varying auditory perturbation during connected speech production in persons who stutter.
Science.gov (United States)
Cai, Shanqing; Beal, Deryk S; Ghosh, Satrajit S; Guenther, Frank H; Perkell, Joseph S
2014-02-01
Auditory feedback (AF), the speech signal received by a speaker's own auditory system, contributes to the online control of speech movements. Recent studies based on AF perturbation provided evidence for abnormalities in the integration of auditory error with ongoing articulation and phonation in persons who stutter (PWS), but stopped short of examining connected speech. This is a crucial limitation considering the importance of sequencing and timing in stuttering. In the current study, we imposed time-varying perturbations on AF while PWS and fluent participants uttered a multisyllabic sentence. Two distinct types of perturbations were used to separately probe the control of the spatial and temporal parameters of articulation. While PWS exhibited only subtle anomalies in the AF-based spatial control, their AF-based fine-tuning of articulatory timing was substantially weaker than normal, especially in early parts of the responses, indicating slowness in the auditory-motor integration for temporal control.
17. Effect of neonatal asphyxia on the impairment of the auditory pathway by recording auditory brainstem responses in newborn piglets: a new experimentation model to study the perinatal hypoxic-ischemic damage on the auditory system.
Directory of Open Access Journals (Sweden)
Francisco Jose Alvarez
Full Text Available Hypoxia-ischemia (HI is a major perinatal problem that results in severe damage to the brain impairing the normal development of the auditory system. The purpose of the present study is to study the effect of perinatal asphyxia on the auditory pathway by recording auditory brain responses in a novel animal experimentation model in newborn piglets.Hypoxia-ischemia was induced to 1.3 day-old piglets by clamping 30 minutes both carotid arteries by vascular occluders and lowering the fraction of inspired oxygen. We compared the Auditory Brain Responses (ABRs of newborn piglets exposed to acute hypoxia/ischemia (n = 6 and a control group with no such exposure (n = 10. ABRs were recorded for both ears before the start of the experiment (baseline, after 30 minutes of HI injury, and every 30 minutes during 6 h after the HI injury.Auditory brain responses were altered during the hypoxic-ischemic insult but recovered 30-60 minutes later. Hypoxia/ischemia seemed to induce auditory functional damage by increasing I-V latencies and decreasing wave I, III and V amplitudes, although differences were not significant.The described experimental model of hypoxia-ischemia in newborn piglets may be useful for studying the effect of perinatal asphyxia on the impairment of the auditory pathway.
18. Auditory streaming of tones of uncertain frequency, level, and duration.
Science.gov (United States)
Chang, An-Chieh; Lutfi, Robert A; Lee, Jungmee
2015-12-01
Stimulus uncertainty is known to critically affect auditory masking, but its influence on auditory streaming has been largely ignored. Standard ABA-ABA tone sequences were made increasingly uncertain by increasing the sigma of normal distributions from which the frequency, level, or duration of tones were randomly drawn. Consistent with predictions based on a model of masking by Lutfi, Gilbertson, Chang, and Stamas [J. Acoust. Soc. Am. 134, 2160-2170 (2013)], the frequency difference for which A and B tones formed separate streams increased as a linear function of sigma in tone frequency but was much less affected by sigma in tone level or duration.
19. Auditory Hallucinations Nomenclature and Classification
NARCIS (Netherlands)
Blom, Jan Dirk; Sommer, Iris E. C.
2010-01-01
Introduction: The literature on the possible neurobiologic correlates of auditory hallucinations is expanding rapidly. For an adequate understanding and linking of this emerging knowledge, a clear and uniform nomenclature is a prerequisite. The primary purpose of the present article is to provide an
20. Nigel: A Severe Auditory Dyslexic
Science.gov (United States)
Cotterell, Gill
1976-01-01
Reported is the case study of a boy with severe auditory dyslexia who received remedial treatment from the age of four and progressed through courses at a technical college and a 3-year apprenticeship course in mechanics by the age of eighteen. (IM)
1. A Framework for Teacher Verbal Feedback: Lessons from Chinese Mathematics Classrooms
Science.gov (United States)
Li, Na; Cao, Yiming; Mok, Ida Ah Chee
2016-01-01
Teacher verbal feedback plays an important role in classroom teaching. Different types of feedback can have different effect on students' learning. Praise and blame feedback could provide positive and negative results for learners. The gap was left in considering teachers' attitudes in providing verbal feedback to students. Due to feedback which…
2. An Analysis of Feedback Given to Strong and Weak Student Writers
Science.gov (United States)
Dinnen, Janet L. D.; Collopy, Rachel M. B.
2009-01-01
Improvement-oriented feedback has been shown to be more effective at raising writing achievement than simple evaluative feedback. This study investigates whether teachers differ in the feedback they give to weak and strong writers as well as how feedback differs across grades. Interviews were conducted with 15 teachers about the feedback they gave…
3. Rateless feedback codes
DEFF Research Database (Denmark)
Sørensen, Jesper Hemming; Koike-Akino, Toshiaki; Orlik, Philip
2012-01-01
This paper proposes a concept called rateless feedback coding. We redesign the existing LT and Raptor codes, by introducing new degree distributions for the case when a few feedback opportunities are available. We show that incorporating feedback to LT codes can significantly decrease both...... the coding overhead and the encoding/decoding complexity. Moreover, we show that, at the price of a slight increase in the coding overhead, linear complexity is achieved with Raptor feedback coding....
4. Pulsed feedback defers cellular differentiation.
Directory of Open Access Journals (Sweden)
Joe H Levine
2012-01-01
Full Text Available Environmental signals induce diverse cellular differentiation programs. In certain systems, cells defer differentiation for extended time periods after the signal appears, proliferating through multiple rounds of cell division before committing to a new fate. How can cells set a deferral time much longer than the cell cycle? Here we study Bacillus subtilis cells that respond to sudden nutrient limitation with multiple rounds of growth and division before differentiating into spores. A well-characterized genetic circuit controls the concentration and phosphorylation of the master regulator Spo0A, which rises to a critical concentration to initiate sporulation. However, it remains unclear how this circuit enables cells to defer sporulation for multiple cell cycles. Using quantitative time-lapse fluorescence microscopy of Spo0A dynamics in individual cells, we observed pulses of Spo0A phosphorylation at a characteristic cell cycle phase. Pulse amplitudes grew systematically and cell-autonomously over multiple cell cycles leading up to sporulation. This pulse growth required a key positive feedback loop involving the sporulation kinases, without which the deferral of sporulation became ultrasensitive to kinase expression. Thus, deferral is controlled by a pulsed positive feedback loop in which kinase expression is activated by pulses of Spo0A phosphorylation. This pulsed positive feedback architecture provides a more robust mechanism for setting deferral times than constitutive kinase expression. Finally, using mathematical modeling, we show how pulsing and time delays together enable "polyphasic" positive feedback, in which different parts of a feedback loop are active at different times. Polyphasic feedback can enable more accurate tuning of long deferral times. Together, these results suggest that Bacillus subtilis uses a pulsed positive feedback loop to implement a "timer" that operates over timescales much longer than a cell cycle.
5. The role of auditory cortices in the retrieval of single-trial auditory-visual object memories.
Science.gov (United States)
Matusz, Pawel J; Thelen, Antonia; Amrein, Sarah; Geiser, Eveline; Anken, Jacques; Murray, Micah M
2015-03-01
Single-trial encounters with multisensory stimuli affect both memory performance and early-latency brain responses to visual stimuli. Whether and how auditory cortices support memory processes based on single-trial multisensory learning is unknown and may differ qualitatively and quantitatively from comparable processes within visual cortices due to purported differences in memory capacities across the senses. We recorded event-related potentials (ERPs) as healthy adults (n = 18) performed a continuous recognition task in the auditory modality, discriminating initial (new) from repeated (old) sounds of environmental objects. Initial presentations were either unisensory or multisensory; the latter entailed synchronous presentation of a semantically congruent or a meaningless image. Repeated presentations were exclusively auditory, thus differing only according to the context in which the sound was initially encountered. Discrimination abilities (indexed by d') were increased for repeated sounds that were initially encountered with a semantically congruent image versus sounds initially encountered with either a meaningless or no image. Analyses of ERPs within an electrical neuroimaging framework revealed that early stages of auditory processing of repeated sounds were affected by prior single-trial multisensory contexts. These effects followed from significantly reduced activity within a distributed network, including the right superior temporal cortex, suggesting an inverse relationship between brain activity and behavioural outcome on this task. The present findings demonstrate how auditory cortices contribute to long-term effects of multisensory experiences on auditory object discrimination. We propose a new framework for the efficacy of multisensory processes to impact both current multisensory stimulus processing and unisensory discrimination abilities later in time.
6. Changes in otoacoustic emissions during selective auditory and visual attention.
Science.gov (United States)
Walsh, Kyle P; Pasanen, Edward G; McFadden, Dennis
2015-05-01
Previous studies have demonstrated that the otoacoustic emissions (OAEs) measured during behavioral tasks can have different magnitudes when subjects are attending selectively or not attending. The implication is that the cognitive and perceptual demands of a task can affect the first neural stage of auditory processing-the sensory receptors themselves. However, the directions of the reported attentional effects have been inconsistent, the magnitudes of the observed differences typically have been small, and comparisons across studies have been made difficult by significant procedural differences. In this study, a nonlinear version of the stimulus-frequency OAE (SFOAE), called the nSFOAE, was used to measure cochlear responses from human subjects while they simultaneously performed behavioral tasks requiring selective auditory attention (dichotic or diotic listening), selective visual attention, or relative inattention. Within subjects, the differences in nSFOAE magnitude between inattention and attention conditions were about 2-3 dB for both auditory and visual modalities, and the effect sizes for the differences typically were large for both nSFOAE magnitude and phase. These results reveal that the cochlear efferent reflex is differentially active during selective attention and inattention, for both auditory and visual tasks, although they do not reveal how attention is improved when efferent activity is greater.
7. Preventing Feedback Fizzle
Science.gov (United States)
Brookhart, Susan M.
2012-01-01
Feedback is certainly about saying or writing helpful, learning-focused comments. But that is only part of it. What happens beforehand? What happens afterward? Feedback that is helpful and learning-focused fits into a context. Before a teacher gives feedback, students need to know the learning target so they have a purpose for using the feedback…
8. Developing Sustainable Feedback Practices
Science.gov (United States)
Carless, David; Salter, Diane; Yang, Min; Lam, Joy
2011-01-01
Feedback is central to the development of student learning, but within the constraints of modularized learning in higher education it is increasingly difficult to handle effectively. This article makes a case for sustainable feedback as a contribution to the reconceptualization of feedback processes. The data derive from the Student Assessment and…
9. Cortical oscillations in auditory perception and speech: evidence for two temporal windows in human auditory cortex
Directory of Open Access Journals (Sweden)
Huan eLuo
2012-05-01
Full Text Available Natural sounds, including vocal communication sounds, contain critical information at multiple time scales. Two essential temporal modulation rates in speech have been argued to be in the low gamma band (~20-80 ms duration information and the theta band (~150-300 ms, corresponding to segmental and syllabic modulation rates, respectively. On one hypothesis, auditory cortex implements temporal integration using time constants closely related to these values. The neural correlates of a proposed dual temporal window mechanism in human auditory cortex remain poorly understood. We recorded MEG responses from participants listening to non-speech auditory stimuli with different temporal structures, created by concatenating frequency-modulated segments of varied segment durations. We show that these non-speech stimuli with temporal structure matching speech-relevant scales (~25 ms and ~200 ms elicit reliable phase tracking in the corresponding associated oscillatory frequencies (low gamma and theta bands. In contrast, stimuli with non-matching temporal structure do not. Furthermore, the topography of theta band phase tracking shows rightward lateralization while gamma band phase tracking occurs bilaterally. The results support the hypothesis that there exists multi-time resolution processing in cortex on discontinuous scales and provide evidence for an asymmetric organization of temporal analysis (asymmetrical sampling in time, AST. The data argue for a macroscopic-level neural mechanism underlying multi-time resolution processing: the sliding and resetting of intrinsic temporal windows on privileged time scales.
10. Event-related potentials in response to 3-D auditory stimuli.
Science.gov (United States)
Fuchigami, Tatsuo; Okubo, Osami; Fujita, Yukihiko; Kohira, Ryutaro; Arakawa, Chikako; Endo, Ayumi; Haruyama, Wakako; Imai, Yuki; Mugishima, Hideo
2009-09-01
To evaluate auditory spatial cognitive function, age correlations for event-related potentials (ERPs) in response to auditory stimuli with a Doppler effect were studied in normal children. A sound with a Doppler effect is perceived as a moving audio image. A total of 99 normal subjects (age range, 4-21 years) were tested. In the task-relevant oddball paradigm, P300 and key-press reaction time were elicited using auditory stimuli (1000 Hz fixed and enlarged tones with a Doppler effect). From the age of 4 years, the P300 latency for the enlarged tone with a Doppler effect shortened more rapidly with age than did the P300 latency for tone-pips, and the latencies for the different conditions became similar towards the late teens. The P300 of auditory stimuli with a Doppler effect may be used to evaluate auditory spatial cognitive function in children.
11. Enhanced auditory evoked potentials in musicians:A review of recent findings
Institute of Scientific and Technical Information of China (English)
2016-01-01
Auditory evoked potentials serve as an objective mode for assessment to check the functioning of the auditory system and neuroplasticity. Literature has reported enhanced electrophysiological responses in musicians, which shows neuroplasticity in musicians. Various databases including PubMed, Google, Google Scholar and Medline were searched for references related to auditory evoked potentials in musicians from 1994 till date. Different auditory evoked potentials in musicians have been summarized in the present article. The findings of various studies may support as evidences for music-induced neuroplasticity which can be used for the treatment of various clinical disorders. The search results showed enhanced auditory evoked potentials in musicians compared to non-musicians from brainstem to cortical levels. Also, the present review showed enhanced attentive and pre-attentive skills in musicians compared to non-musicians.
12. Modeling auditory processing and speech perception in hearing-impaired listeners
DEFF Research Database (Denmark)
Jepsen, Morten Løve
A better understanding of how the human auditory system represents and analyzes sounds and how hearing impairment affects such processing is of great interest for researchers in the fields of auditory neuroscience, audiology, and speech communication as well as for applications in hearing......-instrument and speech technology. In this thesis, the primary focus was on the development and evaluation of a computational model of human auditory signal-processing and perception. The model was initially designed to simulate the normal-hearing auditory system with particular focus on the nonlinear processing...... aimed at experimentally characterizing the effects of cochlear damage on listeners' auditory processing, in terms of sensitivity loss and reduced temporal and spectral resolution. The results showed that listeners with comparable audiograms can have very different estimated cochlear input...
13. Direct Contribution of Auditory Motion Information to Sound-Induced Visual Motion Perception
Directory of Open Access Journals (Sweden)
Souta Hidaka
2011-10-01
Full Text Available We have recently demonstrated that alternating left-right sound sources induce motion perception to static visual stimuli along the horizontal plane (SIVM: sound-induced visual motion perception, Hidaka et al., 2009. The aim of the current study was to elucidate whether auditory motion signals, rather than auditory positional signals, can directly contribute to the SIVM. We presented static visual flashes at retinal locations outside the fovea together with a lateral auditory motion provided by a virtual stereo noise source smoothly shifting in the horizontal plane. The flashes appeared to move in the situation where auditory positional information would have little influence on the perceived position of visual stimuli; the spatiotemporal position of the flashes was in the middle of the auditory motion trajectory. Furthermore, the auditory motion altered visual motion perception in a global motion display; in this display, different localized motion signals of multiple visual stimuli were combined to produce a coherent visual motion perception so that there was no clear one-to-one correspondence between the auditory stimuli and each visual stimulus. These findings suggest the existence of direct interactions between the auditory and visual modalities in motion processing and motion perception.
14. The impact of educational level on performance on auditory processing tests
Directory of Open Access Journals (Sweden)
Cristina F.B. Murphy
2016-03-01
Full Text Available Research has demonstrated that a higher level of education is associated with better performance on cognitive tests among middle-aged and elderly people. However, the effects of education on auditory processing skills have not yet been evaluated. Previous demonstrations of sensory-cognitive interactions in the aging process indicate the potential importance of this topic. Therefore, the primary purpose of this study was to investigate the performance of middle-aged and elderly people with different levels of formal education on auditory processing tests. A total of 177 adults with no evidence of cognitive, psychological or neurological conditions took part in the research. The participants completed a series of auditory assessments, including dichotic digit, frequency pattern and speech-in-noise tests. A working memory test was also performed to investigate the extent to which auditory processing and cognitive performance were associated. The results demonstrated positive but weak correlations between years of schooling and performance on all of the tests applied. The factor years of schooling was also one of the best predictors of frequency pattern and speech-in-noise test performance. Additionally, performance on the working memory, frequency pattern and dichotic digit tests was also correlated, suggesting that the influence of educational level on auditory processing performance might be associated with the cognitive demand of the auditory processing tests rather than auditory sensory aspects itself. Longitudinal research is required to investigate the causal relationship between educational level and auditory processing skills.
15. Neural Representation of Concurrent Vowels in Macaque Primary Auditory Cortex.
Science.gov (United States)
Fishman, Yonatan I; Micheyl, Christophe; Steinschneider, Mitchell
2016-01-01
Successful speech perception in real-world environments requires that the auditory system segregate competing voices that overlap in frequency and time into separate streams. Vowels are major constituents of speech and are comprised of frequencies (harmonics) that are integer multiples of a common fundamental frequency (F0). The pitch and identity of a vowel are determined by its F0 and spectral envelope (formant structure), respectively. When two spectrally overlapping vowels differing in F0 are presented concurrently, they can be readily perceived as two separate "auditory objects" with pitches at their respective F0s. A difference in pitch between two simultaneous vowels provides a powerful cue for their segregation, which in turn, facilitates their individual identification. The neural mechanisms underlying the segregation of concurrent vowels based on pitch differences are poorly understood. Here, we examine neural population responses in macaque primary auditory cortex (A1) to single and double concurrent vowels (/a/ and /i/) that differ in F0 such that they are heard as two separate auditory objects with distinct pitches. We find that neural population responses in A1 can resolve, via a rate-place code, lower harmonics of both single and double concurrent vowels. Furthermore, we show that the formant structures, and hence the identities, of single vowels can be reliably recovered from the neural representation of double concurrent vowels. We conclude that A1 contains sufficient spectral information to enable concurrent vowel segregation and identification by downstream cortical areas.
16. The Auditory Verbal Learning Test (Rey AVLT): An Arabic Version
Science.gov (United States)
Sharoni, Varda; Natur, Nazeh
2014-01-01
The goals of this study were to adapt the Rey Auditory Verbal Learning Test (AVLT) into Arabic, to compare recall functioning among age groups (6:0 to 17:11), and to compare gender differences on various memory dimensions (immediate and delayed recall, learning rate, recognition, proactive interferences, and retroactive interferences). This…
17. Quantum feedback channels
CERN Document Server
Bowen, G
2002-01-01
In classical information theory the capacity of a noisy communication channel cannot be increased by the use of feedback. In quantum information theory the no-cloning theorem means that noiseless copying and feedback of quantum information cannot be achieved. In this paper, quantum feedback is defined as the unlimited use of a noiseless quantum channel from receiver to sender. Given such quantum feedback, it is shown to provide no increase in the entanglement-assisted capacities of a noisy quantum channel, in direct analogy to the classical case. It is also shown that in various cases of non-assisted capacities, feedback can increase the capacity of many quantum channels.
18. Effectiveness of Corrective Feedback on Writing
Institute of Scientific and Technical Information of China (English)
高砚
2012-01-01
This study aims to find out the effectiveness of corrective feedback on ESL writing. By reviewing and analyzing the previous six research studies, the author tries to reveal the most effective way to provide corrective feedback for L2 students and the factors that impact the processing of error feedback. Findings indicated that corrective feedback is helpful for students to improve ESL writing on both accuracy and fluency. Furthermore, correction and direct corrective feedbacks as well as the oral and written meta-linguistic explanation are the most effective ways to help students improving their writing. However, in⁃dividual learner’s difference has influence on processing corrective feedback. At last, limitation of present study and suggestion for future research were made.
19. Situated Formative Feedback
DEFF Research Database (Denmark)
Lukassen, Niels Bech; Wahl, Christian; Sorensen, Elsebeth Korsgaard
2016-01-01
This study addresses the conceptual challenge of providing students with good quality feedback to enhance student learning in an online community of practice (COP). The aim of the study is to identify feedback mechanisms in a virtual learning environment (VLE) and to create a full formative...... feedback episode (FFE) through an online dialogue. The paper argues that dialogue is crucial for student learning and that feedback is not only something the teacher gives to the student. Viewing good quality feedback as social, situated, formative, emphasis is put on the establishment of dialogue. We...... refer to this type of feedback as, Situated Formative Feedback (SFF). As a basis for exploring, identifying and discussing relevant aspects of SFF the paper analyses qualitative data from a Moodle dialogue. Data are embedded in the qualitative analytic program Nvivo and are analysed with a system...
20. Male great tit song perch selection in response to noise-dependent female feedback
NARCIS (Netherlands)
Halfwerk, Wouter; Bot, Sander; Slabbekoorn, Hans
2012-01-01
1. Anthropogenic noise can affect intra-pair communication and therefore interfere with reproductive success. However, many animals have various signal strategies to cope with noise, although it is unclear whether they rely on direct auditory feedback from their own perception of noise or signal-to-
1. The Impact of Wireless Technology Feedback on Inventory Management at a Dairy Manufacturing Plant
Science.gov (United States)
Goomas, David T.
2012-01-01
Replacing the method of counting inventory from paper count sheets to that of wireless reliably reduced the elapsed time to complete a daily inventory of the storage cooler in a dairy manufacturing plant. The handheld computers delivered immediate prompts as well as auditory and visual feedback. Reducing the time to complete the daily inventory…
2. Theoretical feasibility of suppressing offensive sports chants by means of delayed feedback of sound
NARCIS (Netherlands)
Wijngaarden, S.J. van; Balken, J.A. van
2007-01-01
A novel approach for disrupting offensive chants at sporting events is proposed, based on attacking synchronization between individuals. Since timing is crucial for coordination between chanters, disruption of timing is expected to be effective against undesired chants. Delayed auditory feedback is
3. Behavioral semantics of learning and crossmodal processing in auditory cortex: the semantic processor concept.
Science.gov (United States)
Scheich, Henning; Brechmann, André; Brosch, Michael; Budinger, Eike; Ohl, Frank W; Selezneva, Elena; Stark, Holger; Tischmeyer, Wolfgang; Wetzel, Wolfram
2011-01-01
Two phenomena of auditory cortex activity have recently attracted attention, namely that the primary field can show different types of learning-related changes of sound representation and that during learning even this early auditory cortex is under strong multimodal influence. Based on neuronal recordings in animal auditory cortex during instrumental tasks, in this review we put forward the hypothesis that these two phenomena serve to derive the task-specific meaning of sounds by associative learning. To understand the implications of this tenet, it is helpful to realize how a behavioral meaning is usually derived for novel environmental sounds. For this purpose, associations with other sensory, e.g. visual, information are mandatory to develop a connection between a sound and its behaviorally relevant cause and/or the context of sound occurrence. This makes it plausible that in instrumental tasks various non-auditory sensory and procedural contingencies of sound generation become co-represented by neuronal firing in auditory cortex. Information related to reward or to avoidance of discomfort during task learning, that is essentially non-auditory, is also co-represented. The reinforcement influence points to the dopaminergic internal reward system, the local role of which for memory consolidation in auditory cortex is well-established. Thus, during a trial of task performance, the neuronal responses to the sounds are embedded in a sequence of representations of such non-auditory information. The embedded auditory responses show task-related modulations of auditory responses falling into types that correspond to three basic logical classifications that may be performed with a perceptual item, i.e. from simple detection to discrimination, and categorization. This hierarchy of classifications determine the semantic "same-different" relationships among sounds. Different cognitive classifications appear to be a consequence of learning task and lead to a recruitment of
4. Auditory adaptation improves tactile frequency perception.
Science.gov (United States)
Crommett, Lexi E; Pérez-Bellido, Alexis; Yau, Jeffrey M
2017-01-11
Our ability to process temporal frequency information by touch underlies our capacity to perceive and discriminate surface textures. Auditory signals, which also provide extensive temporal frequency information, can systematically alter the perception of vibrations on the hand. How auditory signals shape tactile processing is unclear: perceptual interactions between contemporaneous sounds and vibrations are consistent with multiple neural mechanisms. Here we used a crossmodal adaptation paradigm, which separated auditory and tactile stimulation in time, to test the hypothesis that tactile frequency perception depends on neural circuits that also process auditory frequency. We reasoned that auditory adaptation effects would transfer to touch only if signals from both senses converge on common representations. We found that auditory adaptation can improve tactile frequency discrimination thresholds. This occurred only when adaptor and test frequencies overlapped. In contrast, auditory adaptation did not influence tactile intensity judgments. Thus, auditory adaptation enhances touch in a frequency- and feature-specific manner. A simple network model in which tactile frequency information is decoded from sensory neurons that are susceptible to auditory adaptation recapitulates these behavioral results. Our results imply that the neural circuits supporting tactile frequency perception also process auditory signals. This finding is consistent with the notion of supramodal operators performing canonical operations, like temporal frequency processing, regardless of input modality.
5. Auditory Dysfunction in Patients with Cerebrovascular Disease
Directory of Open Access Journals (Sweden)
2014-01-01
Full Text Available Auditory dysfunction is a common clinical symptom that can induce profound effects on the quality of life of those affected. Cerebrovascular disease (CVD is the most prevalent neurological disorder today, but it has generally been considered a rare cause of auditory dysfunction. However, a substantial proportion of patients with stroke might have auditory dysfunction that has been underestimated due to difficulties with evaluation. The present study reviews relationships between auditory dysfunction and types of CVD including cerebral infarction, intracerebral hemorrhage, subarachnoid hemorrhage, cerebrovascular malformation, moyamoya disease, and superficial siderosis. Recent advances in the etiology, anatomy, and strategies to diagnose and treat these conditions are described. The numbers of patients with CVD accompanied by auditory dysfunction will increase as the population ages. Cerebrovascular diseases often include the auditory system, resulting in various types of auditory dysfunctions, such as unilateral or bilateral deafness, cortical deafness, pure word deafness, auditory agnosia, and auditory hallucinations, some of which are subtle and can only be detected by precise psychoacoustic and electrophysiological testing. The contribution of CVD to auditory dysfunction needs to be understood because CVD can be fatal if overlooked.
6. Present and past: Can writing abilities in school children be associated with their auditory discrimination capacities in infancy?
Science.gov (United States)
Schaadt, Gesa; Männel, Claudia; van der Meer, Elke; Pannekamp, Ann; Oberecker, Regine; Friederici, Angela D
2015-12-01
Literacy acquisition is highly associated with auditory processing abilities, such as auditory discrimination. The event-related potential Mismatch Response (MMR) is an indicator for cortical auditory discrimination abilities and it has been found to be reduced in individuals with reading and writing impairments and also in infants at risk for these impairments. The goal of the present study was to analyze the relationship between auditory speech discrimination in infancy and writing abilities at school age within subjects, and to determine when auditory speech discrimination differences, relevant for later writing abilities, start to develop. We analyzed the MMR registered in response to natural syllables in German children with and without writing problems at two points during development, that is, at school age and at infancy, namely at age 1 month and 5 months. We observed MMR related auditory discrimination differences between infants with and without later writing problems, starting to develop at age 5 months-an age when infants begin to establish language-specific phoneme representations. At school age, these children with and without writing problems also showed auditory discrimination differences, reflected in the MMR, confirming a relationship between writing and auditory speech processing skills. Thus, writing problems at school age are, at least, partly grounded in auditory discrimination problems developing already during the first months of life.
7. Distraction task rather than focal attention modulates gamma activity associated with auditory steady-state responses (ASSRs)
DEFF Research Database (Denmark)
Griskova-Bulanova, Inga; Ruksenas, Osvaldas; Dapsys, Kastytis;
2011-01-01
To explore the modulation of auditory steady-state response (ASSR) by experimental tasks, differing in attentional focus and arousal level.......To explore the modulation of auditory steady-state response (ASSR) by experimental tasks, differing in attentional focus and arousal level....
8. Sensory feedback in interlimb coordination
DEFF Research Database (Denmark)
Gervasio, Sabata; Voigt, Michael; Kersting, Uwe G.
2017-01-01
direct communication between the two sides without the need for the involvement of higher centers. These may also exist in humans since sensory feedback elicited by tibial nerve stimulation on one side (ipsilateral) can affect the muscles activation in the opposite side (contralateral), provoking short......-latency crossed responses (SLCRs). The current study investigated whether contralateral afferent feedback contributes to the mechanism controlling the SLCR in human gastrocnemius muscle. Surface electromyogram, kinematic and kinetic data were recorded from subjects during normal walking and hybrid walking (with.......04). Moreover, estimated spindle secondary afferent and Golgi tendon organ activity were significantly different (P ≤ 0.01) when opposite responses have been observed, that is during normal (facilitation) and hybrid walking (inhibition) conditions. Contralateral sensory feedback, specifically spindle secondary...
9. Intrinsic modulators of auditory thalamocortical transmission.
Science.gov (United States)
Lee, Charles C; Sherman, S Murray
2012-05-01
Neurons in layer 4 of the primary auditory cortex receive convergent glutamatergic inputs from thalamic and cortical projections that activate different groups of postsynaptic glutamate receptors. Of particular interest in layer 4 neurons are the Group II metabotropic glutamate receptors (mGluRs), which hyperpolarize neurons postsynaptically via the downstream opening of GIRK channels. This pronounced effect on membrane conductance could influence the neuronal processing of synaptic inputs, such as those from the thalamus, essentially modulating information flow through the thalamocortical pathway. To examine how Group II mGluRs affect thalamocortical transmission, we used an in vitro slice preparation of the auditory thalamocortical pathways in the mouse to examine synaptic transmission under conditions where Group II mGluRs were activated. We found that both pre- and post-synaptic Group II mGluRs are involved in the attenuation of thalamocortical EPSP/Cs. Thus, thalamocortical synaptic transmission is suppressed via the presynaptic reduction of thalamocortical neurotransmitter release and the postsynaptic inhibition of the layer 4 thalamorecipient neurons. This could enable the thalamocortical pathway to autoregulate transmission, via either a gating or gain control mechanism, or both.
10. Auditory evoked potentials in postconcussive syndrome.
Science.gov (United States)
Drake, M E; Weate, S J; Newell, S A
1996-12-01
The neuropsychiatric sequelae of minor head trauma have been the source of controversy. Most clinical and imaging studies have shown no alteration after concussion, but neuropsychological and neuropathological abnormalities have been reported. Some changes in neurophysiologic diagnostic tests have been described in postconcussive syndrome. We recorded middle latency auditory evoked potentials (MLR) and slow vertex responses (SVR) in 20 individuals with prolonged cognitive difficulties, behavior changes, dizziness, and headache after concussion. MLR is utilized alternating polarity clicks presented monaurally at 70 dB SL at 4 per second, with 40 dB contralateral masking. Five hundred responses were recorded and replicated from Cz-A1 and Cz-A2, with 50 ms. analysis time and 20-1000 Hz filter band pass. SVRs were recorded with the same montage, but used rarefaction clicks, 0.5 Hz stimulus rate, 500 ms. analysis time, and 1-50 Hz filter band pass. Na and Pa MLR components were reduced in amplitude in postconcussion patients. Pa latency was significantly longer in patients than in controls. SVR amplitudes were longer in concussed individuals, but differences in latency and amplitude were not significant. These changes may reflect posttraumatic disturbance in presumed subcortical MLR generators, or in frontal or temporal cortical structures that modulate them. Middle and long-latency auditory evoked potentials may be helpful in the evaluation of postconcussive neuropsychiatric symptoms.
11. Selective attention in an insect auditory neuron.
Science.gov (United States)
Pollack, G S
1988-07-01
Previous work (Pollack, 1986) showed that an identified auditory neuron of crickets, the omega neuron, selectively encodes the temporal structure of an ipsilateral sound stimulus when a contralateral stimulus is presented simultaneously, even though the contralateral stimulus is clearly encoded when it is presented alone. The present paper investigates the physiological basis for this selective response. The selectivity for the ipsilateral stimulus is a result of the apparent intensity difference of ipsi- and contralateral stimuli, which is imposed by auditory directionality; when simultaneous presentation of stimuli from the 2 sides is mimicked by presenting low- and high-intensity stimuli simultaneously from the ipsilateral side, the neuron responds selectively to the high-intensity stimulus, even though the low-intensity stimulus is effective when it is presented alone. The selective encoding of the more intense (= ipsilateral) stimulus is due to intensity-dependent inhibition, which is superimposed on the cell's excitatory response to sound. Because of the inhibition, the stimulus with lower intensity (i.e., the contralateral stimulus) is rendered subthreshold, while the stimulus with higher intensity (the ipsilateral stimulus) remains above threshold. Consequently, the temporal structure of the low-intensity stimulus is filtered out of the neuron's spike train. The source of the inhibition is not known. It is not a consequence of activation of the omega neuron. Its characteristics are not consistent with those of known inhibitory inputs to the omega neuron.
12. Stabilization using both noisy and noiseless feedback
OpenAIRE
Sahai, Anant
2006-01-01
When designing a distributed control system, the system designer has a choice in how to connect the different units through communication channels. In practice, noiseless and noisy channels may coexist. Using the standard toy example of scalar stabilization, this paper shows how a small amount of noiseless feedback can perform a `supervisory'' role and thereby boost the effectiveness of noisy feedback.
13. Performance Feedback and Probabilistic Bonus Contingencies among Employees in a Human Service Organization
Science.gov (United States)
Cook, Tracy; Dixon, Mark R.
2006-01-01
The present study examined the effects of performance feedback on the behavior of front line supervisory employees at a social service agency. A multiple baseline across three participants was used with three different feedback procedures consisting of verbal feedback, verbal plus individual comparative graphic feedback, and verbal feedback,…
14. Effect of stimulus hemifield on free-field auditory saltation.
Science.gov (United States)
Ishigami, Yoko; Phillips, Dennis P
2008-07-01
Auditory saltation is the orderly misperception of the spatial location of repetitive click stimuli emitted from two successive locations when the inter-click intervals (ICIs) are sufficiently short. The clicks are perceived as originating not only from the actual source locations, but also from locations between them. In two tasks, the present experiment compared free-field auditory saltation for 90 degrees excursions centered in the frontal, rear, left and right acoustic hemifields, by measuring the ICI at which subjects report 50% illusion strength (subjective task) and the ICI at which subjects could not distinguish real motion from saltation (objective task). A comparison of the saltation illusion for excursions spanning the midline (i.e. for frontal or rear hemifields) with that for stimuli in the lateral hemifields (left or right) revealed that the illusion was weaker for the midline-straddling conditions (i.e. the illusion was restricted to shorter ICIs). This may reflect the contribution of two perceptual channels to the task in the midline conditions (as opposed to one in the lateral hemifield conditions), or the fact that the temporal dynamics of localization differ between the midline and lateral hemifield conditions. A subsidiary comparison of saltation supported in the left and right auditory hemifields, and therefore by the right and left auditory forebrains, revealed no difference.
15. Background sounds contribute to spectrotemporal plasticity in primary auditory cortex.
Science.gov (United States)
Moucha, Raluca; Pandya, Pritesh K; Engineer, Navzer D; Rathbun, Daniel L; Kilgard, Michael P
2005-05-01
The mammalian auditory system evolved to extract meaningful information from complex acoustic environments. Spectrotemporal selectivity of auditory neurons provides a potential mechanism to represent natural sounds. Experience-dependent plasticity mechanisms can remodel the spectrotemporal selectivity of neurons in primary auditory cortex (A1). Electrical stimulation of the cholinergic nucleus basalis (NB) enables plasticity in A1 that parallels natural learning and is specific to acoustic features associated with NB activity. In this study, we used NB stimulation to explore how cortical networks reorganize after experience with frequency-modulated (FM) sweeps, and how background stimuli contribute to spectrotemporal plasticity in rat auditory cortex. Pairing an 8-4 kHz FM sweep with NB stimulation 300 times per day for 20 days decreased tone thresholds, frequency selectivity, and response latency of A1 neurons in the region of the tonotopic map activated by the sound. In an attempt to modify neuronal response properties across all of A1 the same NB activation was paired in a second group of rats with five downward FM sweeps, each spanning a different octave. No changes in FM selectivity or receptive field (RF) structure were observed when the neural activation was distributed across the cortical surface. However, the addition of unpaired background sweeps of different rates or direction was sufficient to alter RF characteristics across the tonotopic map in a third group of rats. These results extend earlier observations that cortical neurons can develop stimulus specific plasticity and indicate that background conditions can strongly influence cortical plasticity.
16. Tuned with a tune: Talker normalization via general auditory processes
Directory of Open Access Journals (Sweden)
Erika J C Laing
2012-06-01
Full Text Available Voices have unique acoustic signatures, contributing to the acoustic variability listeners must contend with in perceiving speech, and it has long been proposed that listeners normalize speech perception to information extracted from a talker’s speech. Initial attempts to explain talker normalization relied on extraction of articulatory referents, but recent studies of context-dependent auditory perception suggest that general auditory referents such as the long-term average spectrum (LTAS of a talker’s speech similarly affect speech perception. The present study aimed to differentiate the contributions of articulatory/linguistic versus auditory referents for context-driven talker normalization effects and, more specifically, to identify the specific constraints under which such contexts impact speech perception. Synthesized sentences manipulated to sound like different talkers influenced categorization of a subsequent speech target only when differences in the sentences’ LTAS were in the frequency range of the acoustic cues relevant for the target phonemic contrast. This effect was true both for speech targets preceded by spoken sentence contexts and for targets preceded by nonspeech tone sequences that were LTAS-matched to the spoken sentence contexts. Specific LTAS characteristics, rather than perceived talker, predicted the results suggesting that general auditory mechanisms play an important role in effects considered to be instances of perceptual talker normalization.
17. Active stream segregation specifically involves the left human auditory cortex.
Science.gov (United States)
Deike, Susann; Scheich, Henning; Brechmann, André
2010-06-14
An important aspect of auditory scene analysis is the sequential grouping of similar sounds into one "auditory stream" while keeping competing streams separate. In the present low-noise fMRI study we presented sequences of alternating high-pitch (A) and low-pitch (B) complex harmonic tones using acoustic parameters that allow the perception of either two separate streams or one alternating stream. However, the subjects were instructed to actively and continuously segregate the A from the B stream. This was controlled by the additional instruction to listen for rare level deviants only in the low-pitch stream. Compared to the control condition in which only one non-separable stream was presented the active segregation of the A from the B stream led to a selective increase of activation in the left auditory cortex (AC). Together with a similar finding from a previous study using a different acoustic cue for streaming, namely timbre, this suggests that the left auditory cortex plays a dominant role in active sequential stream segregation. However, we found cue differences within the left AC: Whereas in the posterior areas, including the planum temporale, activation increased for both acoustic cues, the anterior areas, including Heschl's gyrus, are only involved in stream segregation based on pitch.
18. Startle auditory stimuli enhance the performance of fast dynamic contractions.
Science.gov (United States)
Fernandez-Del-Olmo, Miguel; Río-Rodríguez, Dan; Iglesias-Soler, Eliseo; Acero, Rafael M
2014-01-01
Fast reaction times and the ability to develop a high rate of force development (RFD) are crucial for sports performance. However, little is known regarding the relationship between these parameters. The aim of this study was to investigate the effects of auditory stimuli of different intensities on the performance of a concentric bench-press exercise. Concentric bench-presses were performed by thirteen trained subjects in response to three different conditions: a visual stimulus (VS); a visual stimulus accompanied by a non-startle auditory stimulus (AS); and a visual stimulus accompanied by a startle auditory stimulus (SS). Peak RFD, peak velocity, onset movement, movement duration and electromyography from pectoralis and tricep muscles were recorded. The SS condition induced an increase in the RFD and peak velocity and a reduction in the movement onset and duration, in comparison with the VS and AS condition. The onset activation of the pectoralis and tricep muscles was shorter for the SS than for the VS and AS conditions. These findings point out to specific enhancement effects of loud auditory stimulation on the rate of force development. This is of relevance since startle stimuli could be used to explore neural adaptations to resistance training.
19. Auditory Motion Elicits a Visual Motion Aftereffect
Directory of Open Access Journals (Sweden)
Christopher C. Berger
2016-12-01
Full Text Available The visual motion aftereffect is a visual illusion in which exposure to continuous motion in one direction leads to a subsequent illusion of visual motion in the opposite direction. Previous findings have been mixed with regard to whether this visual illusion can be induced cross-modally by auditory stimuli. Based on research on multisensory perception demonstrating the profound influence auditory perception can have on the interpretation and perceived motion of visual stimuli, we hypothesized that exposure to auditory stimuli with strong directional motion cues should induce a visual motion aftereffect. Here, we demonstrate that horizontally moving auditory stimuli induced a significant visual motion aftereffect—an effect that was driven primarily by a change in visual motion perception following exposure to leftward moving auditory stimuli. This finding is consistent with the notion that visual and auditory motion perception rely on at least partially overlapping neural substrates.
20. Opportunistic Relay Selection With Limited Feedback
KAUST Repository
Eltayeb, Mohammed E.
2015-08-01
Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. Generally, relay selection algorithms require channel state information (CSI) feedback from all cooperating relays to make a selection decision. This requirement poses two important challenges, which are often neglected in the literature. Firstly, the fed back channel information is usually corrupted by additive noise. Secondly, CSI feedback generates a great deal of feedback overhead (air-time) that could result in significant performance hits. In this paper, we propose a compressive sensing (CS) based relay selection algorithm that reduces the feedback overhead of relay networks under the assumption of noisy feedback channels. The proposed algorithm exploits CS to first obtain the identity of a set of relays with favorable channel conditions. Following that, the CSI of the identified relays is estimated using least squares estimation without any additional feedback. Both single and multiple relay selection cases are considered. After deriving closed-form expressions for the asymptotic end-to-end SNR at the destination and the feedback load for different relaying protocols, we show that CS-based selection drastically reduces the feedback load and achieves a rate close to that obtained by selection algorithms with dedicated error-free feedback. © 1972-2012 IEEE.
1. Speech distortion measure based on auditory properties
Institute of Scientific and Technical Information of China (English)
CHEN Guo; HU Xiulin; ZHANG Yunyu; ZHU Yaoting
2000-01-01
The Perceptual Spectrum Distortion (PSD), based on auditory properties of human being, is presented to measure speech distortion. The PSD measure calculates the speech distortion distance by simulating the auditory properties of human being and converting short-time speech power spectrum to auditory perceptual spectrum. Preliminary simulative experiments in comparison with the Itakura measure have been done. The results show that the PSD measure is a perferable speech distortion measure and more consistent with subjective assessment of speech quality.
2. Auditory evoked potentials and multiple sclerosis
OpenAIRE
Carla Gentile Matas; Sandro Luiz de Andrade Matas; Caroline Rondina Salzano de Oliveira; Isabela Crivellaro Gonçalves
2010-01-01
Multiple sclerosis (MS) is an inflammatory, demyelinating disease that can affect several areas of the central nervous system. Damage along the auditory pathway can alter its integrity significantly. Therefore, it is important to investigate the auditory pathway, from the brainstem to the cortex, in individuals with MS. OBJECTIVE: The aim of this study was to characterize auditory evoked potentials in adults with MS of the remittent-recurrent type. METHOD: The study comprised 25 individuals w...
3. From Perception to Metacognition: Auditory and Olfactory Functions in Early Blind, Late Blind, and Sighted Individuals
Science.gov (United States)
Cornell Kärnekull, Stina; Arshamian, Artin; Nilsson, Mats E.; Larsson, Maria
2016-01-01
Although evidence is mixed, studies have shown that blind individuals perform better than sighted at specific auditory, tactile, and chemosensory tasks. However, few studies have assessed blind and sighted individuals across different sensory modalities in the same study. We tested early blind (n = 15), late blind (n = 15), and sighted (n = 30) participants with analogous olfactory and auditory tests in absolute threshold, discrimination, identification, episodic recognition, and metacognitive ability. Although the multivariate analysis of variance (MANOVA) showed no overall effect of blindness and no interaction with modality, follow-up between-group contrasts indicated a blind-over-sighted advantage in auditory episodic recognition, that was most pronounced in early blind individuals. In contrast to the auditory modality, there was no empirical support for compensatory effects in any of the olfactory tasks. There was no conclusive evidence for group differences in metacognitive ability to predict episodic recognition performance. Taken together, the results showed no evidence of an overall superior performance in blind relative sighted individuals across olfactory and auditory functions, although early blind individuals exceled in episodic auditory recognition memory. This observation may be related to an experience-induced increase in auditory attentional capacity. PMID:27729884
4. Task-dependent calibration of auditory spatial perception through environmental visual observation.
Science.gov (United States)
Tonelli, Alessia; Brayda, Luca; Gori, Monica
2015-01-01
Visual information is paramount to space perception. Vision influences auditory space estimation. Many studies show that simultaneous visual and auditory cues improve precision of the final multisensory estimate. However, the amount or the temporal extent of visual information, that is sufficient to influence auditory perception, is still unknown. It is therefore interesting to know if vision can improve auditory precision through a short-term environmental observation preceding the audio task and whether this influence is task-specific or environment-specific or both. To test these issues we investigate possible improvements of acoustic precision with sighted blindfolded participants in two audio tasks [minimum audible angle (MAA) and space bisection] and two acoustically different environments (normal room and anechoic room). With respect to a baseline of auditory precision, we found an improvement of precision in the space bisection task but not in the MAA after the observation of a normal room. No improvement was found when performing the same task in an anechoic chamber. In addition, no difference was found between a condition of short environment observation and a condition of full vision during the whole experimental session. Our results suggest that even short-term environmental observation can calibrate auditory spatial performance. They also suggest that echoes can be the cue that underpins visual calibration. Echoes may mediate the transfer of information from the visual to the auditory system.
5. From perception to metacognition: Auditory and olfactory functions in early blind, late blind, and sighted individuals
Directory of Open Access Journals (Sweden)
Stina Cornell Kärnekull
2016-09-01
Full Text Available Although evidence is mixed, studies have shown that blind individuals perform better than sighted at specific auditory, tactile, and chemosensory tasks. However, few studies have assessed blind and sighted individuals across different sensory modalities in the same study. We tested early blind (n = 15, late blind (n = 15, and sighted (n = 30 participants with analogous olfactory and auditory tests in absolute threshold, discrimination, identification, episodic recognition, and metacognitive ability. Although the multivariate analysis of variance (MANOVA showed no overall effect of blindness and no interaction with modality, follow-up between-group contrasts indicated a blind-over-sighted advantage in auditory episodic recognition, that was most pronounced in early blind individuals. In contrast to the auditory modality, there was no empirical support for compensatory effects in any of the olfactory tasks. There was no conclusive evidence for group differences in metacognitive ability to predict episodic recognition performance. Taken together, the results showed no evidence of an overall superior performance in blind relative sighted individuals across olfactory and auditory functions, although early blind individuals exceled in episodic auditory recognition memory. This observation may be related to an experience-induced increase in auditory attentional capacity.
6. Odors bias time perception in visual and auditory modalities
Directory of Open Access Journals (Sweden)
Zhenzhu eYue
2016-04-01
Full Text Available Previous studies have shown that emotional states alter our perception of time. However, attention, which is modulated by a number of factors, such as emotional events, also influences time perception. To exclude potential attentional effects associated with emotional events, various types of odors (inducing different levels of emotional arousal were used to explore whether olfactory events modulated time perception differently in visual and auditory modalities. Participants were shown either a visual dot or heard a continuous tone for 1000 ms or 4000 ms while they were exposed to odors of jasmine, lavender, or garlic. Participants then reproduced the temporal durations of the preceding visual or auditory stimuli by pressing the spacebar twice. Their reproduced durations were compared to those in the control condition (without odor. The results showed that participants produced significantly longer time intervals in the lavender condition than in the jasmine or garlic conditions. The overall influence of odor on time perception was equivalent for both visual and auditory modalities. The analysis of the interaction effect showed that participants produced longer durations than the actual duration in the short interval condition, but they produced shorter durations in the long interval condition. The effect sizes were larger for the auditory modality than those for the visual modality. Moreover, by comparing performance across the initial and the final blocks of the experiment, we found odor adaptation effects were mainly manifested as longer reproductions for the short time interval later in the adaptation phase, and there was a larger effect size in the auditory modality. In summary, the present results indicate that odors imposed differential impacts on reproduced time durations, and they were constrained by different sensory modalities, valence of the emotional events, and target durations. Biases in time perception could be accounted for by a
7. RF feedback for KEKB
Energy Technology Data Exchange (ETDEWEB)
Ezura, Eizi; Yoshimoto, Shin-ichi; Akai, Kazunori [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)
1996-08-01
This paper describes the present status of the RF feedback development for the KEK B-Factory (KEKB). A preliminary experiment concerning the RF feedback using a parallel comb-filter was performed through a choke-mode cavity and a klystron. The RF feedback has been tested using the beam of the TRISTAN Main Ring, and has proved to be effective in damping the beam instability. (author)
8. Glucocorticoid feedback resistance.
Science.gov (United States)
De Kloet, E R; Vreugdenhil, E; Oitzl, M S; Joëls, M
1997-01-01
Glucocorticoid feedback resistance can be inherited or locally acquired. The implications of these two forms of resistance for disease are strikingly different. The inherited form is characterized by enhanced adrenocortical function and hypercorticism to compensate for a generalized deficit in the glucocorticoid receptor gene, but these individuals lack symptoms of Cushing's syndrome. By contrast, resistance acquired at the level of the hypothalamic corticotropin-releasing hormone (CRH) neurons is linked to hypercorticism, which is not compensatory but overexposes the rest of the body and the brain to glucocorticoids. This cell-specific glucocorticoid resistance can be acquired by genetically predisposed individuals failing to cope with (early) life events and causes enhanced vulnerability to disease-specific actions of glucocorticoids. (c) 1997, Elsevier Science Inc. (Trends Endocrinol Metab 1997; 8:26-33).
9. Seeing the song: left auditory structures may track auditory-visual dynamic alignment.
Directory of Open Access Journals (Sweden)
Julia A Mossbridge
Full Text Available Auditory and visual signals generated by a single source tend to be temporally correlated, such as the synchronous sounds of footsteps and the limb movements of a walker. Continuous tracking and comparison of the dynamics of auditory-visual streams is thus useful for the perceptual binding of information arising from a common source. Although language-related mechanisms have been implicated in the tracking of speech-related auditory-visual signals (e.g., speech sounds and lip movements, it is not well known what sensory mechanisms generally track ongoing auditory-visual synchrony for non-speech signals in a complex auditory-visual environment. To begin to address this question, we used music and visual displays that varied in the dynamics of multiple features (e.g., auditory loudness and pitch; visual luminance, color, size, motion, and organization across multiple time scales. Auditory activity (monitored using auditory steady-state responses, ASSR was selectively reduced in the left hemisphere when the music and dynamic visual displays were temporally misaligned. Importantly, ASSR was not affected when attentional engagement with the music was reduced, or when visual displays presented dynamics clearly dissimilar to the music. These results appear to suggest that left-lateralized auditory mechanisms are sensitive to auditory-visual temporal alignment, but perhaps only when the dynamics of auditory and visual streams are similar. These mechanisms may contribute to correct auditory-visual binding in a busy sensory environment.
10. Auditory Training and Its Effects upon the Auditory Discrimination and Reading Readiness of Kindergarten Children.
Science.gov (United States)
Cullen, Minga Mustard
The purpose of this investigation was to evaluate the effects of a systematic auditory training program on the auditory discrimination ability and reading readiness of 55 white, middle/upper middle class kindergarten students. Following pretesting with the "Wepman Auditory Discrimination Test,""The Clymer-Barrett Prereading Battery," and the…
11. Effects of Methylphenidate (Ritalin) on Auditory Performance in Children with Attention and Auditory Processing Disorders.
Science.gov (United States)
Tillery, Kim L.; Katz, Jack; Keller, Warren D.
2000-01-01
A double-blind, placebo-controlled study examined effects of methylphenidate (Ritalin) on auditory processing in 32 children with both attention deficit hyperactivity disorder and central auditory processing (CAP) disorder. Analyses revealed that Ritalin did not have a significant effect on any of the central auditory processing measures, although…
12. Discrimination of auditory stimuli during isoflurane anesthesia.
Science.gov (United States)
Rojas, Manuel J; Navas, Jinna A; Greene, Stephen A; Rector, David M
2008-10-01
Deep isoflurane anesthesia initiates a burst suppression pattern in which high-amplitude bursts are preceded by periods of nearly silent electroencephalogram. The burst suppression ratio (BSR) is the percentage of suppression (silent electroencephalogram) during the burst suppression pattern and is one parameter used to assess anesthesia depth. We investigated cortical burst activity in rats in response to different auditory stimuli presented during the burst suppression state. We noted a rapid appearance of bursts and a significant decrease in the BSR during stimulation. The BSR changes were distinctive for the different stimuli applied, and the BSR decreased significantly more when stimulated with a voice familiar to the rat as compared with an unfamiliar voice. These results show that the cortex can show differential sensory responses during deep isoflurane anesthesia.
13. Augmenting Environmental Interaction in Audio Feedback Systems
Directory of Open Access Journals (Sweden)
Seunghun Kim
2016-04-01
Full Text Available Audio feedback is defined as a positive feedback of acoustic signals where an audio input and output form a loop, and may be utilized artistically. This article presents new context-based controls over audio feedback, leading to the generation of desired sonic behaviors by enriching the influence of existing acoustic information such as room response and ambient noise. This ecological approach to audio feedback emphasizes mutual sonic interaction between signal processing and the acoustic environment. Mappings from analyses of the received signal to signal-processing parameters are designed to emphasize this specificity as an aesthetic goal. Our feedback system presents four types of mappings: approximate analyses of room reverberation to tempo-scale characteristics, ambient noise to amplitude and two different approximations of resonances to timbre. These mappings are validated computationally and evaluated experimentally in different acoustic conditions.
14. Policy Feedback System (PFS)
Data.gov (United States)
Social Security Administration — The Policy Feedback System (PFS) is a web application developed by the Office of Disability Policy Management Information (ODPMI) team that gathers empirical data...
15. Feedback Loop Gains and Feedback Behavior (1996)
DEFF Research Database (Denmark)
Kampmann, Christian Erik
2012-01-01
Linking feedback loops and system behavior is part of the foundation of system dynamics, yet the lack of formal tools has so far prevented a systematic application of the concept, except for very simple systems. Having such tools at their disposal would be a great help to analysts in understanding...... large, complicated simulation models. The paper applies tools from graph theory formally linking individual feedback loop strengths to the system eigenvalues. The significance of a link or a loop gain and an eigenvalue can be expressed in the eigenvalue elasticity, i.e., the relative change...... of an eigenvalue resulting from a relative change in the gain. The elasticities of individual links and loops may be found through simple matrix operations on the linearized system. Even though the number of feedback loops can grow rapidly with system size, reaching astronomical proportions even for modest systems...
16. Neuronal representations of distance in human auditory cortex.
Science.gov (United States)
Kopčo, Norbert; Huang, Samantha; Belliveau, John W; Raij, Tommi; Tengshe, Chinmayi; Ahveninen, Jyrki
2012-07-03
Neuronal mechanisms of auditory distance perception are poorly understood, largely because contributions of intensity and distance processing are difficult to differentiate. Typically, the received intensity increases when sound sources approach us. However, we can also distinguish between soft-but-nearby and loud-but-distant sounds, indicating that distance processing can also be based on intensity-independent cues. Here, we combined behavioral experiments, fMRI measurements, and computational analyses to identify the neural representation of distance independent of intensity. In a virtual reverberant environment, we simulated sound sources at varying distances (15-100 cm) along the right-side interaural axis. Our acoustic analysis suggested that, of the individual intensity-independent depth cues available for these stimuli, direct-to-reverberant ratio (D/R) is more reliable and robust than interaural level difference (ILD). However, on the basis of our behavioral results, subjects' discrimination performance was more consistent with complex intensity-independent distance representations, combining both available cues, than with representations on the basis of either D/R or ILD individually. fMRI activations to sounds varying in distance (containing all cues, including intensity), compared with activations to sounds varying in intensity only, were significantly increased in the planum temporale and posterior superior temporal gyrus contralateral to the direction of stimulation. This fMRI result suggests that neurons in posterior nonprimary auditory cortices, in or near the areas processing other auditory spatial features, are sensitive to intensity-independent sound properties relevant for auditory distance perception.
17. Brainstem auditory evoked potential abnormalities in type 2 diabetes mellitus
Directory of Open Access Journals (Sweden)
Sharat Gupta
2013-01-01
Full Text Available Background: Diabetes mellitus represents a syndrome complex in which multiple organ systems, including the central nervous system, are affected. Aim: The study was conducted to determine the changes in the brainstem auditory evoked potentials in type 2 diabetes mellitus. Materials and Methods: A cross sectional study was conducted on 126 diabetic males, aged 35-50 years, and 106 age-matched, healthy male volunteers. Brainstem auditory evoked potentials were recorded and the results were analyzed statistically using student′s unpaired t-test. The data consisted of wave latencies I, II, III, IV, V and interpeak latencies I-III, III-V and I-V, separately for both ears. Results: The latency of wave IV was significantly delayed only in the right ear, while the latency of waves III, V and interpeak latencies III-V, I-V showed a significant delay bilaterally in diabetic males. However, no significant difference was found between diabetic and control subjects as regards to the latency of wave IV unilaterally in the left ear and the latencies of waves I, II and interpeak latency I-III bilaterally. Conclusion: Diabetes patients have an early involvement of central auditory pathway, which can be detected with fair accuracy with auditory evoked potential studies.
18. Thalamic and parietal brain morphology predicts auditory category learning.
Science.gov (United States)
Scharinger, Mathias; Henry, Molly J; Erb, Julia; Meyer, Lars; Obleser, Jonas
2014-01-01
Auditory categorization is a vital skill involving the attribution of meaning to acoustic events, engaging domain-specific (i.e., auditory) as well as domain-general (e.g., executive) brain networks. A listener's ability to categorize novel acoustic stimuli should therefore depend on both, with the domain-general network being particularly relevant for adaptively changing listening strategies and directing attention to relevant acoustic cues. Here we assessed adaptive listening behavior, using complex acoustic stimuli with an initially salient (but later degraded) spectral cue and a secondary, duration cue that remained nondegraded. We employed voxel-based morphometry (VBM) to identify cortical and subcortical brain structures whose individual neuroanatomy predicted task performance and the ability to optimally switch to making use of temporal cues after spectral degradation. Behavioral listening strategies were assessed by logistic regression and revealed mainly strategy switches in the expected direction, with considerable individual differences. Gray-matter probability in the left inferior parietal lobule (BA 40) and left precentral gyrus was predictive of "optimal" strategy switch, while gray-matter probability in thalamic areas, comprising the medial geniculate body, co-varied with overall performance. Taken together, our findings suggest that successful auditory categorization relies on domain-specific neural circuits in the ascending auditory pathway, while adaptive listening behavior depends more on brain structure in parietal cortex, enabling the (re)direction of attention to salient stimulus properties.
19. Central projections of auditory receptor neurons of crickets.
Science.gov (United States)
Imaizumi, Kazuo; Pollack, Gerald S
2005-12-19
We describe the central projections of physiologically characterized auditory receptor neurons of crickets as revealed by confocal microscopy. Receptors tuned to ultrasonic frequencies (similar to those produced by echolocating, insectivorous bats), to a mid-range of frequencies, and a subset of those tuned to low, cricket-like frequencies have similar projections, terminating medially within the auditory neuropile. Quantitative analysis shows that despite the general similarity of these projections they are tonotopic, with receptors tuned to lower frequencies terminating more medially. Another subset of cricket-song-tuned receptors projects more laterally and posteriorly than the other types. Double-fills of receptors and identified interneurons show that the three medially projecting receptor types are anatomically well positioned to provide monosynaptic input to interneurons that relay auditory information to the brain and to interneurons that modify this ascending information. The more laterally and posteriorly branching receptor type may not interact directly with this ascending pathway, but is well positioned to provide direct input to an interneuron that carries auditory information to more posterior ganglia. These results suggest that information about cricket song is segregated into functionally different pathways as early as the level of receptor neurons. Ultrasound-tuned and mid-frequency tuned receptors have approximately twice as many varicosities, which are sites of transmitter release, per receptor as either anatomical type of cricket-song-tuned receptor. This may compensate in part for the numerical under-representation of these receptor types.
20. Clinical presentation and audiologic findings in pediatric auditory neuropathy
Directory of Open Access Journals (Sweden)
Navneet Gupta
2014-01-01
Full Text Available Aim: of the study was to rule out audiologic findings, related etiologies and its effect in pediatric patients having hearing deficits that are most likely due to a neuropathy of the eighth nerve. Study Design: Retrospective neo-natal hearing screening programme based. Subject and Methods: Subjects include 30 children aged from 0 yrs to 12 yrs, were tested with pure tone audiometry, behavioral observation audiometry, free-filed audiometry, speech audiometry, auditory brainstem response, and click evoked otoacoustic emissions. Results: Pure tone and free-field testing revealed 40 ears (66.67%, n = 60 with sloping type, sensorineural hearing loss, 20 ears (33.3%, n = 60 had flat configuration. Out of this 18 (6%, n = 30 subject showed bilateral similar configuration (either bilateral sloping type/ flat type of audiogram. Rest 12 (40%, n = 30 subject showed bilateral different pattern. 10 (33.3%, n = 30 children demonstrated fair to poor word discrimination scores and the other 2 (6.67%, n = 30 had fair to good word discrimination. For other rest of 18 (60%, n = 30 children speech test couldn′t be performed because of age limit and poor speech and language development. Out of 30 subjects 28 (93.3%, n = 30 showed normal distortion product Otoacoustic emissions and 2(6.67%, n = 30 subjects showed absent emissions. Conclusions: All thirty children demonstrated absent or marked abnormalities of brainstem auditory evoked potentials which suggest cochlear outer hair cell function is normal; mostly lesion is located at the eighth nerve or beyond. Generally auditory neuropathy is associated with different etiologies and it is difficult to diagnose auditory neuropathy with single audiological test; sufficient test of battery is required for complete assessment and diagnosis of auditory neuropathy
1. Prediction of auditory and visual p300 brain-computer interface aptitude.
Directory of Open Access Journals (Sweden)
Sebastian Halder
Full Text Available OBJECTIVE: Brain-computer interfaces (BCIs provide a non-muscular communication channel for patients with late-stage motoneuron disease (e.g., amyotrophic lateral sclerosis (ALS or otherwise motor impaired people and are also used for motor rehabilitation in chronic stroke. Differences in the ability to use a BCI vary from person to person and from session to session. A reliable predictor of aptitude would allow for the selection of suitable BCI paradigms. For this reason, we investigated whether P300 BCI aptitude could be predicted from a short experiment with a standard auditory oddball. METHODS: Forty healthy participants performed an electroencephalography (EEG based visual and auditory P300-BCI spelling task in a single session. In addition, prior to each session an auditory oddball was presented. Features extracted from the auditory oddball were analyzed with respect to predictive power for BCI aptitude. RESULTS: Correlation between auditory oddball response and P300 BCI accuracy revealed a strong relationship between accuracy and N2 amplitude and the amplitude of a late ERP component between 400 and 600 ms. Interestingly, the P3 amplitude of the auditory oddball response was not correlated with accuracy. CONCLUSIONS: Event-related potentials recorded during a standard auditory oddball session moderately predict aptitude in an audiory and highly in a visual P300 BCI. The predictor will allow for faster paradigm selection. SIGNIFICANCE: Our method will reduce strain on patients because unsuccessful training may be avoided, provided the results can be generalized to the patient population.
2. Developmental evaluation of atypical auditory sampling in dyslexia: Functional and structural evidence.
Science.gov (United States)
Lizarazu, Mikel; Lallier, Marie; Molinaro, Nicola; Bourguignon, Mathieu; Paz-Alonso, Pedro M; Lerma-Usabiaga, Garikoitz; Carreiras, Manuel
2015-12-01
Whether phonological deficits in developmental dyslexia are associated with impaired neural sampling of auditory information at either syllabic- or phonemic-rates is still under debate. In addition, whereas neuroanatomical alterations in auditory regions have been documented in dyslexic readers, whether and how these structural anomalies are linked to auditory sampling and reading deficits remains poorly understood. In this study, we measured auditory neural synchronization at different frequencies corresponding to relevant phonological spectral components of speech in children and adults with and without dyslexia, using magnetoencephalography. Furthermore, structural MRI was used to estimate cortical thickness of the auditory cortex of participants. Dyslexics showed atypical brain synchronization at both syllabic (slow) and phonemic (fast) rates. Interestingly, while a left hemispheric asymmetry in cortical thickness was functionally related to a stronger left hemispheric lateralization of neural synchronization to stimuli presented at the phonemic rate in skilled readers, the same anatomical index in dyslexics was related to a stronger right hemispheric dominance for neural synchronization to syllabic-rate auditory stimuli. These data suggest that the acoustic sampling deficit in development dyslexia might be linked to an atypical specialization of the auditory cortex to both low and high frequency amplitude modulations.
3. The role of auditory abilities in basic mechanisms of cognition in older adults
Directory of Open Access Journals (Sweden)
Massimo eGrassi
2013-10-01
Full Text Available The aim of this study was to assess age-related differences between young and older adults in auditory abilities and to investigate the relationship between auditory abilities and basic mechanisms of cognition in older adults. Although there is a certain consensus that the participant’s sensitivity to the absolute intensity of sounds (such as that measured via pure tone audiometry explains his/her cognitive performance, there is not yet much evidence that the participant’s auditory ability (i.e., the whole supra-threshold processing of sounds explains his/her cognitive performance. Twenty-eight young adults (age < 35, 26 young-old adults (65 ≤ age ≤75 and 28 old-old adults (age > 75 were presented with a set of tasks estimating several auditory abilities (i.e., frequency discrimination, intensity discrimination, duration discrimination, timbre discrimination, gap detection, amplitude modulation detection, and the absolute threshold for a 1 kHz pure tone and the participant’s working memory, cognitive inhibition, and processing speed. Results showed an age-related decline in both auditory and cognitive performance. Moreover, regression analyses showed that a subset of the auditory abilities (i.e., the ability to discriminate frequency, duration, timbre, and the ability to detect amplitude modulation explained a significant part of the variance observed in processing speed in older adults. Overall, the present results highlight the relationship between auditory abilities and basic mechanisms of cognition.
4. Feedback is good or bad? Medical residents’ points of view on feedback in clinical education
Directory of Open Access Journals (Sweden)
LEILA BAZRAFKAN
2013-04-01
Full Text Available Introduction: Feedback is very important in education and can help quality in the training process and orient the trainees in clinical contexts. This study aimed to assess the residents’ points of view about feedback in clinical education at Shiraz University of Medical Sciences. Methods: The sample of this study included 170 medical residents attending medical workshops in Shiraz University of Medical Sciences. The residents filled a valid and reliable questionnaire containing 21 items on their perceptions of the feedback they got throughout the workshops. The data were analyzed using SPSS version 14. Results: The study revealed that residents, generally, have a positive perception of feedback in their training. The highest score belonged to the items such as “feedback was applicable to future work”, “feedback corrected my behavior”, “feedback worked as a motivation for education” and “feedback was specific in one subject”. Residents who had a negative feedback experience also increased their efforts to learn. The Surgery residents acquired the highest scores while radiology residents got the lowest. The difference between these groups was statistically significant (P = 0.000. Conclusion: The highest mean score belonged to internal medicine residents. This shows that residents believe that obstetrics & gynecology ward is a ward in which the formative assessment is much more powerful in comparison to the other three major wards. The surgery ward received the lowest score for formative assessment and this shows that the feedback in surgery ward is very low.
5. Students’ perceptions on feedback module in pharmacology
Science.gov (United States)
Patel, Varsha J.; Malhotra, Supriya D.; Rana, Devang A.
2016-01-01
Context: Feedback is an integral part of formative assessment though underutilized in medical education. The objective of this study was to review our feedback module through students’ perceptions. Methodology: We have developed a feedback module which is practiced by us for last 10 years for term ending examination that gives collective feedback to the whole class, followed by individual student-teacher interactions. Students were also exposed to 6–7 multiple choice questions (MCQs) based assessment during the course of pharmacology. Immediately after each MCQ test the answer keys is displayed along with an explanation. Two classes of students were requested to give their perceptions about the feedback by responding on Likert scale for the statements in the questionnaire. All the 206 students who volunteered for the study were enrolled in the study. Mann–Whitney test was used to calculate the difference in perceptions. Results: Of 278 students of two classes, 206 responded (74%). Students’ agreement varied from 93% to 98% for 5 items in the questionnaire for the feedback after term ending examinations. Perception of students attending one or more than one feedback session did not differ significantly. For MCQs, tests agreement was 91% to 98% for the 4 items. There was no significant difference between two classes in their perceptions regarding feedback practices (P < 0.05). Conclusion: Students gave a favorable opinion for our feedback module. In the medical colleges with a large number of students, this module is feasible for feedback in formative assessment in the form of written tests. PMID:27500170
6. Impact of online visual feedback on motor acquisition and retention when learning to reach in a force field.
Science.gov (United States)
Batcho, C S; Gagné, M; Bouyer, L J; Roy, J S; Mercier, C
2016-11-19
When subjects learn a novel motor task, several sources of feedback (proprioceptive, visual or auditory) contribute to the performance. Over the past few years, several studies have investigated the role of visual feedback in motor learning, yet evidence remains conflicting. The aim of this study was therefore to investigate the role of online visual feedback (VFb) on the acquisition and retention stages of motor learning associated with training in a reaching task. Thirty healthy subjects made ballistic reaching movements with their dominant arm toward two targets, on 2 consecutive days using a robotized exoskeleton (KINARM). They were randomly assigned to a group with (VFb) or without (NoVFb) VFb of index position during movement. On day 1, the task was performed before (baseline) and during the application of a velocity-dependent resistive force field (adaptation). To assess retention, participants repeated the task with the force field on day 2. Motor learning was characterized by: (1) the final endpoint error (movement accuracy) and (2) the initial angle (iANG) of deviation (motor planning). Even though both groups showed motor adaptation, the NoVFb-group exhibited slower learning and higher final endpoint error than the VFb-group. In some condition, subjects trained without visual feedback used more curved initial trajectories to anticipate for the perturbation. This observation suggests that learning to reach targets in a velocity-dependent resistive force field is possible even when feedback is limited. However, the absence of VFb leads to different strategies that were only apparent when reaching toward the most challenging target.
7. Feedback og interpersonel kommunikation
DEFF Research Database (Denmark)
Dindler, Camilla
2016-01-01
Som interpersonel kommunikationsform handler feedback om at observere, mærke og italesætte det, som handler om relationen mellem samtaleparterne mere end om samtaleemnet. Her er fokus på, hvad der siges og hvordan der kommunikeres sammen. Feedback er her ikke en korrigerende tilbagemelding til...
8. Low power adder based auditory filter architecture.
Science.gov (United States)
Rahiman, P F Khaleelur; Jayanthi, V S
2014-01-01
Cochlea devices are powered up with the help of batteries and they should possess long working life to avoid replacing of devices at regular interval of years. Hence the devices with low power consumptions are required. In cochlea devices there are numerous filters, each responsible for frequency variant signals, which helps in identifying speech signals of different audible range. In this paper, multiplierless lookup table (LUT) based auditory filter is implemented. Power aware adder architectures are utilized to add the output samples of the LUT, available at every clock cycle. The design is developed and modeled using Verilog HDL, simulated using Mentor Graphics Model-Sim Simulator, and synthesized using Synopsys Design Compiler tool. The design was mapped to TSMC 65 nm technological node. The standard ASIC design methodology has been adapted to carry out the power analysis. The proposed FIR filter architecture has reduced the leakage power by 15% and increased its performance by 2.76%.
9. Enhanced Negative Feedback Responses in Remitted Depression
Science.gov (United States)
Santesso, Diane L.; Steele, Katherine T.; Bogdan, Ryan; Holmes, Avram J.; Deveney, Christen M.; Meites, Tiffany M.; Pizzagalli, Diego A.
2011-01-01
Major depressive disorder (MDD) is characterized by hypersensitivity to negative feedback that might involve frontocingulate dysfunction. MDD subjects exhibit enhanced electrophysiological responses to negative internal (errors) and external (feedback) cues. Whether this dysfunction extends to remitted depressed (RD) subjects with a history of MDD is currently unknown. To address this issue, we examined the feedback-related negativity (FRN) in RD and control subjects using a probabilistic punishment learning task. Despite equivalent behavioral performance, RD subjects showed larger FRNs to negative feedback relative to controls; group differences remained after accounting for residual anxiety and depressive symptoms. The present findings suggest that abnormal responses to negative feedback extend to samples at increased risk for depressive episodes in the absence of current symptoms. PMID:18580576
10. Cooperative Feedback for MIMO Interference Channels
CERN Document Server
Huang, Kaibin
2010-01-01
Multi-antenna precoding effectively mitigates the interference in wireless networks. However, the precoding efficiency can be significantly degraded by the overhead due to the required feedback of channel state information (CSI). This paper addresses such an issue by proposing a systematic method of designing precoders for the two-user multiple-input-multiple-output (MIMO) interference channels based on finite-rate CSI feedback from receivers to their interferers, called cooperative feedback. Specifically, each precoder is decomposed into inner and outer precoders for nulling interference and improving the data link array gain, respectively. The inner precoders are further designed to suppress residual interference resulting from finite-rate cooperative feedback. To regulate residual interference due to precoder quantization, additional scalar cooperative feedback signals are designed to control transmitters' power using different criteria including applying interference margins, maximizing sum throughput, an...
11. Critical Thinking in Gifted Children's Offline and Online Peer Feedback
Science.gov (United States)
Miller, Myriah T.; Olthouse, Jill
2013-01-01
This comparative study identified the differences between gifted children's offline and online peer feedback within a summer talented writer's workshop. Researchers analyzed ten students' writings for degrees of critical thinking evident in their feedback. Online feedback included students' writings in social writing sites Storybird.com and…
12. A Content Analysis of Peer Feedback in Triadic Supervision
Science.gov (United States)
Avent, Janeé R.; Wahesh, Edward; Purgason, Lucy L.; Borders, L. DiAnne; Mobley, A. Keith
2015-01-01
There is limited research on the types of peer feedback exchanged during triadic supervision. Through a content analysis, the authors found that students provided feedback about counseling performance and cognitive counseling skills most often in supervision sessions. However, there were differences in the types of feedback exchanged across three…
13. Comparison of the domain and frequency domain state feedbacks
Energy Technology Data Exchange (ETDEWEB)
Zhang, S.Y.
1986-01-01
In this paper, we present explicitly the equivalence of the time domain and frequency domain state feedbacks, as well as the dynamic state feedback and a modified frequency domain state feedback, from the closed-loop transfer function point of view. The difference of the two approaches is also shown.
14. Academic Writing and Grammatical Accuracy: The Role of Corrective Feedback
Science.gov (United States)
Baleghizadeh, Sasan; Gordani, Yahya
2012-01-01
Investigations into the effect of providing corrective feedback on L2 writing have often produced contradictory results. This study, following a line of research concerned with the role of corrective feedback in writing, contributes to this line of research by analyzing different feedback types in an EFL academic writing context. 45 graduate…
15. Group Projects in Interior Design Studio Classes: Peer Feedback Benefits
Science.gov (United States)
2011-01-01
Group projects have been shown to be effective for providing peer feedback in classrooms. While students in regular enrollment classes benefit from peer feedback, low-enrollment classes face many challenges. This study compares peer feedback effectiveness between two interior design studio classes with different design projects. In one class,…
16. Feedback i matematik
DEFF Research Database (Denmark)
Sortkær, Bent
2017-01-01
Feedback bliver i litteraturen igen og igen fremhævet som et af de mest effektive midler til at fremme elevers præstationer i skolen (Hartberg, Dobson, & Gran, 2012; Hattie & Timperley, 2007; Wiliam, 2015). Dette på trods af, at flere forskere påpeger, at feedback ikke altid er læringsfremmende...... (Hattie & Gan, 2011), og nogle endda viser, at feedback kan have en negativ virkning i forhold til præstationer (Kluger & DeNisi, 1996). Artiklen vil undersøge disse tilsyneladende modstridende resultater ved at stille spørgsmålet: Under hvilke forudsætninger virker feedback i matematik læringsfremmende......? Dette gøres ved at dykke ned i forskningslitteraturen omhandlende feedback ud fra en række temaer for på den måde at besvare ovenstående spørgsmål....
17. A unified framework for the organisation of the primate auditory cortex
Directory of Open Access Journals (Sweden)
Simon eBaumann
2013-04-01
Full Text Available In nonhuman primates a scheme for the organisation of the auditory cortex is frequently used to localise auditory processes. The scheme allows a common basis for comparison of functional organisation across nonhuman primate species. However, although a body of functional and structural data in nonhuman primates supports an accepted scheme of nearly a dozen neighbouring functional areas, can this scheme be directly applied to humans? Attempts to expand the scheme of auditory cortical fields in humans have been severely hampered by a recent controversy about the organisation of tonotopic maps in humans, centred on two different models with radically different organisation. We point out observations that reconcile the previous models and suggest a distinct model in which the human cortical organisation is much more like that of other primates. This unified framework allows a more robust and detailed comparison of auditory cortex organisation across primate species including humans.
18. Presenting multiple auditory signals using multiple sound cards in Visual Basic 6.0.
Science.gov (United States)
Chan, Jason S; Spence, Charles
2003-02-01
In auditory research, it is often desirable to present more than two auditory stimuli at any one time. Although the technology has been available for some time, the majority of researchers have not utilized it. This article provides a simple means of presenting multiple, concurrent, independent auditory events, using two or more different sound cards installed within a single computer. By enabling the presentation of more auditory events, we can hope to gain a better understanding of the cognitive and attentional processes operating under more complex and realistic scenes, such as that embodied by the cocktail party effect. The software requirements are Windows 98SR2/Me/NT4/2000/XP, Visual Basic 6.0, and DirectX 7.0 or above. The hardware requirements are a Pentium II, 128 MB RAM, and two or more different sound cards.
19. Auditory hallucinations in nonverbal quadriplegics.
Science.gov (United States)
Hamilton, J
1985-11-01
When a system for communicating with nonverbal, quadriplegic, institutionalized residents was developed, it was discovered that many were experiencing auditory hallucinations. Nine cases are presented in this study. The "voices" described have many similar characteristics, the primary one being that they give authoritarian commands that tell the residents how to behave and to which the residents feel compelled to respond. Both the relationship of this phenomenon to the theoretical work of Julian Jaynes and its effect on the lives of the residents are discussed.
20. Narrow, duplicated internal auditory canal
Energy Technology Data Exchange (ETDEWEB)
Ferreira, T. [Servico de Neurorradiologia, Hospital Garcia de Orta, Avenida Torrado da Silva, 2801-951, Almada (Portugal); Shayestehfar, B. [Department of Radiology, UCLA Oliveview School of Medicine, Los Angeles, California (United States); Lufkin, R. [Department of Radiology, UCLA School of Medicine, Los Angeles, California (United States)
2003-05-01
A narrow internal auditory canal (IAC) constitutes a relative contraindication to cochlear implantation because it is associated with aplasia or hypoplasia of the vestibulocochlear nerve or its cochlear branch. We report an unusual case of a narrow, duplicated IAC, divided by a bony septum into a superior relatively large portion and an inferior stenotic portion, in which we could identify only the facial nerve. This case adds support to the association between a narrow IAC and aplasia or hypoplasia of the vestibulocochlear nerve. The normal facial nerve argues against the hypothesis that the narrow IAC is the result of a primary bony defect which inhibits the growth of the vestibulocochlear nerve. (orig.)
1. Neural plasticity expressed in central auditory structures with and without tinnitus
Directory of Open Access Journals (Sweden)
Larry E Roberts
2012-05-01
Full Text Available Sensory training therapies for tinnitus are based on the assumption that, notwithstanding neural changes related to tinnitus, auditory training can alter the response properties of neurons in auditory pathways. To address this question, we investigated whether brain changes induced by sensory training in tinnitus sufferers and measured by EEG are similar to those induced in age and hearing loss matched individuals without tinnitus trained on the same auditory task. Auditory training was given using a 5 kHz 40-Hz amplitude-modulated sound that was in the tinnitus frequency region of the tinnitus subjects and enabled extraction of the 40-Hz auditory steady-state response (ASSR and P2 transient response known to localize to primary and nonprimary auditory cortex, respectively. P2 amplitude increased with training equally in participants with tinnitus and in control subjects, suggesting normal remodeling of nonprimary auditory regions in tinnitus. However, training-induced changes in the ASSR differed between the tinnitus and control groups. In controls ASSR phase advanced toward the stimulus waveform by about ten degrees over training, in agreement with previous results obtained in young normal hearing individuals. However, ASSR phase did not change significantly with training in the tinnitus group, although some participants showed phase shifts resembling controls. On the other hand, ASSR amplitude increased with training in the tinnitus group, whereas in controls this response (which is difficult to remodel in young normal hearing subjects did not change with training. These results suggest that neural changes related to tinnitus altered how neural plasticity was expressed in the region of primary but not nonprimary auditory cortex. Auditory training did not reduce tinnitus loudness although a small effect on the tinnitus spectrum was detected.
2. Representation of speech in human auditory cortex: is it special?
Science.gov (United States)
Steinschneider, Mitchell; Nourski, Kirill V; Fishman, Yonatan I
2013-11-01
Successful categorization of phonemes in speech requires that the brain analyze the acoustic signal along both spectral and temporal dimensions. Neural encoding of the stimulus amplitude envelope is critical for parsing the speech stream into syllabic units. Encoding of voice onset time (VOT) and place of articulation (POA), cues necessary for determining phonemic identity, occurs within shorter time frames. An unresolved question is whether the neural representation of speech is based on processing mechanisms that are unique to humans and shaped by learning and experience, or is based on rules governing general auditory processing that are also present in non-human animals. This question was examined by comparing the neural activity elicited by speech and other complex vocalizations in primary auditory cortex of macaques, who are limited vocal learners, with that in Heschl's gyrus, the putative location of primary auditory cortex in humans. Entrainment to the amplitude envelope is neither specific to humans nor to human speech. VOT is represented by responses time-locked to consonant release and voicing onset in both humans and monkeys. Temporal representation of VOT is observed both for isolated syllables and for syllables embedded in the more naturalistic context of running speech. The fundamental frequency of male speakers is represented by more rapid neural activity phase-locked to the glottal pulsation rate in both humans and monkeys. In both species, the differential representation of stop consonants varying in their POA can be predicted by the relationship between the frequency selectivity of neurons and the onset spectra of the speech sounds. These findings indicate that the neurophysiology of primary auditory cortex is similar in monkeys and humans despite their vastly different experience with human speech, and that Heschl's gyrus is engaged in general auditory, and not language-specific, processing. This article is part of a Special Issue entitled
3. Computational spectrotemporal auditory model with applications to acoustical information processing
Science.gov (United States)
Chi, Tai-Shih
A computational spectrotemporal auditory model based on neurophysiological findings in early auditory and cortical stages is described. The model provides a unified multiresolution representation of the spectral and temporal features of sound likely critical in the perception of timbre. Several types of complex stimuli are used to demonstrate the spectrotemporal information preserved by the model. Shown by these examples, this two stage model reflects the apparent progressive loss of temporal dynamics along the auditory pathway from the rapid phase-locking (several kHz in auditory nerve), to moderate rates of synchrony (several hundred Hz in midbrain), to much lower rates of modulations in the cortex (around 30 Hz). To complete this model, several projection-based reconstruction algorithms are implemented to resynthesize the sound from the representations with reduced dynamics. One particular application of this model is to assess speech intelligibility. The spectro-temporal Modulation Transfer Functions (MTF) of this model is investigated and shown to be consistent with the salient trends in the human MTFs (derived from human detection thresholds) which exhibit a lowpass function with respect to both spectral and temporal dimensions, with 50% bandwidths of about 16 Hz and 2 cycles/octave. Therefore, the model is used to demonstrate the potential relevance of these MTFs to the assessment of speech intelligibility in noise and reverberant conditions. Another useful feature is the phase singularity emerged in the scale space generated by this multiscale auditory model. The singularity is shown to have certain robust properties and carry the crucial information about the spectral profile. Such claim is justified by perceptually tolerable resynthesized sounds from the nonconvex singularity set. In addition, the singularity set is demonstrated to encode the pitch and formants at different scales. These properties make the singularity set very suitable for traditional
4. Behavioral and EEG evidence for auditory memory suppression
Directory of Open Access Journals (Sweden)
Maya Elizabeth Cano
2016-03-01
Full Text Available The neural basis of motivated forgetting using the Think/No-Think (TNT paradigm is receiving increased attention with a particular focus on the mechanisms that enable memory suppression. However, most TNT studies have been limited to the visual domain. To assess whether and to what extent direct memory suppression extends across sensory modalities, we examined behavioral and electroencephalographic (EEG effects of auditory Think/No-Think in healthy young adults by adapting the TNT paradigm to the auditory modality. Behaviorally, suppression of memory strength was indexed by prolonged response times during the retrieval of subsequently remembered No-Think words. We examined task-related EEG activity of both attempted memory retrieval and inhibition of a previously learned target word during the presentation of its paired associate. Event-related EEG responses revealed two main findings: 1 a centralized Think > No-Think positivity during auditory word presentation (from approximately 0-500ms, and 2 a sustained Think positivity over parietal electrodes beginning at approximately 600ms reflecting the memory retrieval effect which was significantly reduced for No-Think words. In addition, word-locked theta (4-8 Hz power was initially greater for No-Think compared to Think during auditory word presentation over fronto-central electrodes. This was followed by a posterior theta increase indexing successful memory retrieval in the Think condition.The observed event-related potential pattern and theta power analysis are similar to that reported in visual Think/No-Think studies and support a modality non-specific mechanism for memory inhibition. The EEG data also provide evidence supporting differing roles and time courses of frontal and parietal regions in the flexible control of auditory memory.
5. Mapping tonotopy in human auditory cortex
NARCIS (Netherlands)
van Dijk, Pim; Langers, Dave R M; Moore, BCJ; Patterson, RD; Winter, IM; Carlyon, RP; Gockel, HE
2013-01-01
Tonotopy is arguably the most prominent organizational principle in the auditory pathway. Nevertheless, the layout of tonotopic maps in humans is still debated. We present neuroimaging data that robustly identify multiple tonotopic maps in the bilateral auditory cortex. In contrast with some earlier
6. Bilateral duplication of the internal auditory canal
Energy Technology Data Exchange (ETDEWEB)
Weon, Young Cheol; Kim, Jae Hyoung; Choi, Sung Kyu [Seoul National University College of Medicine, Department of Radiology, Seoul National University Bundang Hospital, Seongnam-si (Korea); Koo, Ja-Won [Seoul National University College of Medicine, Department of Otolaryngology, Seoul National University Bundang Hospital, Seongnam-si (Korea)
2007-10-15
Duplication of the internal auditory canal is an extremely rare temporal bone anomaly that is believed to result from aplasia or hypoplasia of the vestibulocochlear nerve. We report bilateral duplication of the internal auditory canal in a 28-month-old boy with developmental delay and sensorineural hearing loss. (orig.)
7. Primary Auditory Cortex Regulates Threat Memory Specificity
Science.gov (United States)
Wigestrand, Mattis B.; Schiff, Hillary C.; Fyhn, Marianne; LeDoux, Joseph E.; Sears, Robert M.
2017-01-01
Distinguishing threatening from nonthreatening stimuli is essential for survival and stimulus generalization is a hallmark of anxiety disorders. While auditory threat learning produces long-lasting plasticity in primary auditory cortex (Au1), it is not clear whether such Au1 plasticity regulates memory specificity or generalization. We used…
8. Further Evidence of Auditory Extinction in Aphasia
Science.gov (United States)
Marshall, Rebecca Shisler; Basilakos, Alexandra; Love-Myers, Kim
2013-01-01
Purpose: Preliminary research ( Shisler, 2005) suggests that auditory extinction in individuals with aphasia (IWA) may be connected to binding and attention. In this study, the authors expanded on previous findings on auditory extinction to determine the source of extinction deficits in IWA. Method: Seventeen IWA (M[subscript age] = 53.19 years)…
9. Auditory Processing Disorder and Foreign Language Acquisition
Science.gov (United States)
Veselovska, Ganna
2015-01-01
This article aims at exploring various strategies for coping with the auditory processing disorder in the light of foreign language acquisition. The techniques relevant to dealing with the auditory processing disorder can be attributed to environmental and compensatory approaches. The environmental one involves actions directed at creating a…
10. Instantaneous Current Feedback Control Strategy on Buck Mode Inverter
Institute of Scientific and Technical Information of China (English)
2011-01-01
Control strategies for Buck mode inverter have important effect on static and dynamic characteristics, reliability, load capacity, and short-circuit resistance. Instantaneous current feedback control strategies include instantaneous inductor current feedback control and instantaneous capacitor current feedback control, both of which have essential difference. When the Buck mode inverter respectively adopts instantaneous inductor current and capacitor current feedback control strategies, characteristics of stability, output voltage and power, short circuit, nonlinear load and dynamic are fully investigated in this paper.
11. English Learners Perception on Lecturers’ Corrective Feedback
Directory of Open Access Journals (Sweden)
2016-04-01
Full Text Available The importance of written corrective feedback (CF has been an issue of substantial debate in the literature and this controversial issue has led to a development in latest studies to draw on foreign language acquisition (FLA research as a way to further comprehend the complexities of this issue particularly how students and teachers perceive the effectiveness of written corrective feedback. This research has largely focused on students’ perception on Lecturers’ corrective feedback, perceives the usefulness of different types of corrective feedback and the reasons they have for their preferences. Qualitative data was collected from 40 EFL students in 6th semester, by means of written questionnaires, interview and observation. Four feedback strategies were employed in this research and ranked each statement by using five-point Likert scale. Findings showed that almost all students 81.43 % want correction or feedback from lecturers for the mistakes on their writing. For the type of written corrective feedback, students prefer lecturers mark their mistakes and give comment on their work with the percentage as follows: 93% students found that giving clues or comment about how to fix errors can improve their writing ability, 76.69% of the students found that error identification is the most useful type of feedback, and 57.50% of students have a positive opinion for the provision of correction which is accompanied by comment. Those percentages of students perspective is supported by students’ explanation in an open ended question of questionnaire. Pedagogical implications of the study are also discussed.
12. Auditory-Verbal Comprehension Development of 2-5 Year Old Normal Persian Speaking Children in Tehran, Iran
Directory of Open Access Journals (Sweden)
2011-06-01
Full Text Available Background and Aim: Understanding and defining developmental norms of auditory comprehension is a necessity for detecting auditory-verbal comprehension impairments in children. We hereby investigated lexical auditory development of Persian (Farsi speaking children.Methods: In this cross-sectional study, auditory comprehension of four 2-5 year old normal children of adult’s child-directed utterance at available nurseries was observed by researchers primarily to gain a great number of comprehendible words for the children of the same age. The words were classified into nouns, verbs and adjectives. Auditory-verbal comprehension task items were also considered in 2 sections of subordinates and superordinates auditory comprehension. Colored pictures were provided for each item. Thirty 2-5 year old normal children were randomly selected from nurseries all over Tehran. Children were tested by this task and subsequently, mean of their correct response were analyzed. Results: The findings revealed that there is a high positive correlation between auditory-verbal comprehension and age (r=0.804, p=0.001. Comparing children in 3 age groups of 2-3, 3-4 and 4-5 year old, showed that subordinate and superordinate auditory comprehension of the former group is significantly lower (p0.05, while the difference between subordinate and superordinate auditory comprehension was significant in all age groups (p<0.05.Conclusion: Auditory-verbal comprehension develop much faster at lower than older ages and there is no prominent difference between word linguistic classes including nouns, verbs and adjectives. Slower development of superordinate auditory comprehension implies semantic hierarchical evolution of words.
13. Classification of Underwater Target Echoes Based on Auditory Perception Characteristics
Institute of Scientific and Technical Information of China (English)
Xiukun Li; Xiangxia Meng; Hang Liu; Mingye Liu
2014-01-01
In underwater target detection, the bottom reverberation has some of the same properties as the target echo, which has a great impact on the performance. It is essential to study the difference between target echo and reverberation. In this paper, based on the unique advantage of human listening ability on objects distinction, the Gammatone filter is taken as the auditory model. In addition, time-frequency perception features and auditory spectral features are extracted for active sonar target echo and bottom reverberation separation. The features of the experimental data have good concentration characteristics in the same class and have a large amount of differences between different classes, which shows that this method can effectively distinguish between the target echo and reverberation.
14. Litter feedbacks, evolutionary change and exotic plant
NARCIS (Netherlands)
Eppinga, M.B.; Kaproth, M.A.; Collins, A.R.; Molofsky, J.
2011-01-01
1. Understanding the mechanisms driving exotic plant invasions is important for designing successful invader control strategies. Previous studies have highlighted different invasion mechanisms, including alteration of nutrient cycles through plant–soil feedback and evolutionary change toward more co
15. Auditory and visual interhemispheric communication in musicians and non-musicians.
Science.gov (United States)
Woelfle, Rebecca; Grahn, Jessica A
2013-01-01
The corpus callosum (CC) is a brain structure composed of axon fibres linking the right and left hemispheres. Musical training is associated with larger midsagittal cross-sectional area of the CC, suggesting that interhemispheric communication may be faster in musicians. Here we compared interhemispheric transmission times (ITTs) for musicians and non-musicians. ITT was measured by comparing simple reaction times to stimuli presented to the same hemisphere that controlled a button-press response (uncrossed reaction time), or to the contralateral hemisphere (crossed reaction time). Both visual and auditory stimuli were tested. We predicted that the crossed-uncrossed difference (CUD) for musicians would be smaller than for non-musicians as a result of faster interhemispheric transfer times. We did not expect a difference in CUDs between the visual and auditory modalities for either musicians or non-musicians, as previous work indicates that interhemispheric transfer may happen through the genu of the CC, which contains motor fibres rather than sensory fibres. There were no significant differences in CUDs between musicians and non-musicians. However, auditory CUDs were significantly smaller than visual CUDs. Although this auditory-visual difference was larger in musicians than non-musicians, the interaction between modality and musical training was not significant. Therefore, although musical training does not significantly affect ITT, the crossing of auditory information between hemispheres appears to be faster than visual information, perhaps because subcortical pathways play a greater role for auditory interhemispheric transfer.
16. Inter-individual difference in the effect of mirror reflection-induced visual feedback on phantom limb awareness in forearm amputees.
Directory of Open Access Journals (Sweden)
Noritaka Kawashima
Full Text Available OBJECTIVE: To test whether the phantom limb awareness could be altered by observing mirror reflection-induced visual feedback (MVF in unilateral forearm amputees. METHODS: Ten unilateral forearm amputees were asked to perform bilateral (intact and phantom synchronous wrist motions with and without MVF. During wrist motion, electromyographic activities in the extensor digitorum longus (EDL and flexor carpi radialis muscles (FCR were recorded with bipolar electrodes. Degree of wrist range of motion (ROM was also recorded by electrogoniometry attached to the wrist joint of intact side. Subjects were asked to answer the degree of attainment of phantom limb motion using a visual analog scale (VAS: ranging from 0 (hard to 10 (easy. RESULTS: VAS and ROM were significantly increased by utilizing MVF, and the extent of an enhancement of the VAS and wrist ROM was positively correlated (r = 0.72, p<0.05. Although FCR EMG activity also showed significant enhancement by MVF, this was not correlated with the changes of VAS and ROM. Interestingly, while we found negative correlation between EDL EMG activity and wrist ROM, MVF generally affected to be increasing both EDL EMG and ROM. CONCLUSIONS: Although there was larger extent of variability in the effect of MVF on phantom limb awareness, MVF has a potential to enhance phantom limb awareness, in case those who has a difficulty for the phantom limb motion. The present result suggests that the motor command to the missing limb can be re-activated by an appropriate therapeutic strategy such as mirror therapy.
17. Speech perception as complex auditory categorization
Science.gov (United States)
Holt, Lori L.
2002-05-01
Despite a long and rich history of categorization research in cognitive psychology, very little work has addressed the issue of complex auditory category formation. This is especially unfortunate because the general underlying cognitive and perceptual mechanisms that guide auditory category formation are of great importance to understanding speech perception. I will discuss a new methodological approach to examining complex auditory category formation that specifically addresses issues relevant to speech perception. This approach utilizes novel nonspeech sound stimuli to gain full experimental control over listeners' history of experience. As such, the course of learning is readily measurable. Results from this methodology indicate that the structure and formation of auditory categories are a function of the statistical input distributions of sound that listeners hear, aspects of the operating characteristics of the auditory system, and characteristics of the perceptual categorization system. These results have important implications for phonetic acquisition and speech perception.
18. Audio versus Written Feedback: Exploring Learners' Preference and the Impact of Feedback Format on Students' Academic Performance
Science.gov (United States)
Morris, Cecile; Chikwa, Gladson
2016-01-01
Very little is known about the impact of the different types of feedback on students' academic performance. This article explores students' preference in the use of audio and written feedback and how each type of feedback received by students impacts their academic performance in subsequent assignments. The study involved 68 students who were…
19. Altered Auditory BOLD Response to Conspecific Birdsong in Zebra Finches with Stuttered Syllables
OpenAIRE
Voss, Henning U.; Delanthi Salgado-Commissariat; Helekar, Santosh A.
2010-01-01
How well a songbird learns a song appears to depend on the formation of a robust auditory template of its tutor's song. Using functional magnetic resonance neuroimaging we examine auditory responses in two groups of zebra finches that differ in the type of song they sing after being tutored by birds producing stuttering-like syllable repetitions in their songs. We find that birds that learn to produce the stuttered syntax show attenuated blood oxygenation level-dependent (BOLD) responses to t...
20. 不同部位参考电极诱发的豚鼠听性脑干反应差异分析%The Auditory Brainstem Response of Guinea Pigs Recorded at Different Electrode Positions
Institute of Scientific and Technical Information of China (English)
刘文杰; 傅仲鹰; 刘淑芳; 陈玮伦
2015-01-01
Objective To observe auditory brainstem response evoked at different electrode positions adopting electrode slices .Methods The ABRs of 12 normal guinea pigs (24 ears)were recorded by two methods using clicks as stimulation .Active electrode was positioned at the vertex while the ground electrode at the nose .The reference e‐lectrode was placed on bilateral pinnas or mastoids .Then observe waveforms ,response thresholds (RT) ,peak la‐tencies(PL) and inter-peak latencies (IPL)of ABR .Results No significant difference were observed in the RT ,Ⅰ ,Ⅱand Ⅲ PL ,Ⅰ - Ⅲ IPL of ABR between the two methods(P>0 .05) .When stimulation was decreasing and with the reference electrode slices placed at bilateral pinnas ,waveⅡpeak was stable and discernable of ABR record‐ings across twenty -four ears of guinea pigs .The amplitude decreased more slowly than any other waves ,and dis‐appeared at the last .While reference electrode slices were placed on bilateral mastoids ,the amplitude of wave Ⅲ de‐creased more slowly than any other waves except wave Ⅳ ,and disappeared at lost .Ⅱ - Ⅲ ,Ⅲ - Ⅳ IPL became shorter .These two positions both recorded amplitude higher and PL advanced for wave Ⅳ as the stimulation de‐creased by 20 to 40 dB nHL ,and Ⅲ - Ⅳ IPL became shorter .This phenomenon was more obvious when reference electrode was placed at mastoid .Conclusion Wave Ⅱwas more stable and discernible with reference electrode placed at the bilateral pinnas .Therefore wave Ⅱ recorded by this way can be a new method to record the ABR threshold of g uinea pig s .%目的：分析不同部位参考电极诱发豚鼠听性脑干反应（ABR ）的差异。方法健康豚鼠12只（24耳），分别采用双侧耳廓或双侧乳突作为参考电极，鼻尖部为接地电极，颅顶为记录电极，给予短声刺激，分别观察以耳廓和乳突为参考电极时的ABR波形、反应阈、潜伏期、波间期。结果两
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https://www.ncbi.nlm.nih.gov/pubmed/9738504?dopt=Abstract
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Format
Choose Destination
Nature. 1998 Sep 3;395(6697):89-93.
# DNA hypomethylation leads to elevated mutation rates.
### Author information
1
Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA.
### Abstract
Genome-wide demethylation has been suggested to be a step in carcinogenesis. Evidence for this notion comes from the frequently observed global DNA hypomethylation in tumour cells, and from a recent study suggesting that defects in DNA methylation might contribute to the genomic instability of some colorectal tumour cell lines. DNA hypomethylation has also been associated with abnormal chromosomal structures, as observed in cells from patients with ICF (Immunodeficiency, Centromeric instability and Facial abnormalities) syndrome and in cells treated with the demethylating agent 5-azadeoxycytidine. Here we report that murine embryonic stem cells nullizygous for the major DNA methyltransferase (Dnmt1) gene exhibited significantly elevated mutation rates at both the endogenous hypoxanthine phosphoribosyltransferase (Hprt) gene and an integrated viral thymidine kinase (tk) transgene. Gene deletions were the predominant mutations at both loci. The major cause of the observed tk deletions was either mitotic recombination or chromosomal loss accompanied by duplication of the remaining chromosome. Our results imply an important role for mammalian DNA methylation in maintaining genome stability.
PMID:
9738504
DOI:
10.1038/25779
[Indexed for MEDLINE]
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http://blog.sigfpe.com/2008/06/categories-of-polynomials-and-comonadic.html?showComment=1214097840000
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# A Neighborhood of Infinity
## Saturday, June 14, 2008
### Categories of polynomials and comonadic plumbing
Suppose you have a Haskell program and you want to introduce a new global constant into your program. There are at least two approaches you could take:
1. Simply introduce a new global constant. You could name it x and write something like x=1.23456 and refer to x throughout your code. This has the advantage of being easy to implement.
2. Write all of your code in monadic style and make use of the reader monad. This is intrusive in the sense that you may have to make many changes to your code to support it. But it has the advantage that all of your functions now explicitly become functions of your global constant.
Now I’m going to roughly sketch a more categorical view of both of these approaches. So let’s restrict ourselves to the subset of Haskell that corresponds to typed lambda calculus without general recursion so that we know all of our functions will be total and correspond to the mathematical notion of a function. Then all of our functions become arrows in the category that we’ll call Hask.
Firstly consider approach (1). Suppose we want to introduce a new constant, x, of type A. Category theory talks about arrows rather than elements of objects, so instead of introducing x of type A, introduce the function x:1->A where 1 is the terminal object in Hask, normally called (). An element of A is the same thing as an element of 1->A, but in the latter case we have an arrow in the category Hask.
Before continuing, let me digress to talk about polynomials. Suppose we have a ring (with an identity) R. We define R[x], where x is an indeterminate, to be the ring of polynomials in x. Another way to describe that is to say that R[x] is the smallest ring containing R and an indeterminate x, that makes no assumptions about x other than those required to make R[x] a ring. For example we know that (1+x)(1-x)=1-x2, because that must hold in any ring. Given a polynomial p in R[x] we can think of it as a function fp from R to R. fp(a) is the value we get when substituting the value of a for x in p. So a polynomial in R[x] is the same as a function from R to R that can be written in terms of elements of R, multiplication and addition.
We can do the same with category theory. Given a category A we can ask for the smallest category extending A and containing an indeterminate arrow x:1 -> A. Just as with polynomials we have to allow all possible arrows that can be made by composing arrows of A with x. The resulting expressions for arrows will contain x as a free variable, just like the way x appears in polynomials. In fact, by analogy we can call the resulting category, A[x], the category of polynomials in x:1->A. In the special case A=Hask, you can see that Hask[x] is the category of Haskell functions extended by a new constant of type x:1->A but assuming no equations other than those necessary to make Hask[x] a category. Just as an arrow in Hask is a Haskell function, an arrow in Hask[x] is a Haskell function making use of an as yet undefined constant x.
(I've glossed over some subtleties. Just as we need a suitable equivalence relation to ensure that (1+x)(1-x)=1-x2 in R[x], we need suitable equivalence relations in our category. I'll be showing you where to find the missing details later.)
Here's the implementation of a function, h, making use of a constant x:
(Note that I'll be using Edward Kmett's category-extras shortly so I need some imports)
> import Control.Monad.Reader> import Control.Comonad> import Control.Comonad.Reader> x = 1.23456> f a = 2*a+x> g a = x*a> h a = f (g a)> test1 = h 2
Now consider the second approach. The easiest thing is to just give an implementation of the above using the reader monad:
> f' a = do> x <- ask> return $2*a+x> g' a = do> x <- ask> return$ x*a> h' a = return a >>= g' >>= f'> test2 = runReader (h' 2) 1.23456
So here's the important point: Hask[x] is the same category as HaskR. In both cases the arrows are things, which when supplied a value of the right type (like 1.23456), give arrows in Hask from their head object to their tail object.
But there's another way to do this. We can use the reader comonad:
> f'' a = 2*extract a+askC a> g'' a = extract a*askC a> h'' a = a =>> g'' =>> f''> test3 = runCoreader (h'' (Coreader 1.23456 2))
In a similar way, we're dealing with arrows of the form wa -> b and we can compose them using =>>. These arrows form the coKleisli category of the reader comonad, S, which we can write HaskS. So we must have
Now some back story. Over 20 years ago I was intrigued by the idea that logic might form a category with logical ‘and’ and ‘or’ forming a product and coproduct. I came across the book Introduction to Higher Order Categorical Logic by Lambek and Scott for ₤30.00. That’s ₤60.00 at today's prices, or about \$120.00. On a student grant? What was I thinking? And as it bore no relation to anything I was studying at the time, I barely understood a word of it. I was probably fairly applied at that point doing courses in stuff like solid state physics and electromagnetism as well as a bit of topology and algebra. I doubt I'd heard of lambda calculus though I could program in BASIC and APL. So there it sat on my bookshelf for 22 years. Periodically I’d look at it, realise that I still didn’t understand enough of the prerequisites, and put it back on the shelf. And then a month or so ago I picked it up again and realised that the first third or so of it could be interpreted as being about almost trivial Haskell programs. For example, on page 62 was
Proposition 7.1
The category A[x] of all polynomials in the indeterminate x:1->A over the cartesian or cartesian closed category A is isomorphic to the Kleisli category AA=ASA of the cotriple (SA,&epsilonAA).
The language is a little different. Lambek and Scott used the term cotriple instead of comonad and Kleisli category where I’d say coKleisli category. δ and ε are cojoin and coreturn. And Lambek and Scott's theorem applies to any cartesian closed category. But after staring at this claim for a while it dawned on me that all it was really saying was this: here are two ways to introduce new constants into a category. But there’s no way I would have seen that without having practical experience of programming with monads. Learning Haskell has finally paid off. It’s given me enough intuition about category theory for me to get some return on my ₤30.00 investment paid to Heffers all those years ago. I expected to take this book to my deathbed, never having read it.
Anyway, for the details I left out above, especially the correct equivalence relation on Hask[x], you'll just have to read the book yourself.
Also, note the similarity to the deduction theorem. This theorem says that if we can prove B, assuming A, then we can deduce A implies B without making any assumptions. It unifies two way to introduce a proposition A, either as a hypothesis, or as an antecedent in an implication. In fact, the above theorem is just a categorical version of the deduction theorem.
Also note the connection with writing pointfree code. In fact, the pointfree lambdabot plugin makes use good use of the reader monad to eliminate named parameters from functions.
I’m amazed by seeing a book from 1986 that describes how to use a comonad to plumb a value through some code. As far as I know, this predates the explicit use of the reader monad in a program, Wadler and Moggi’s papers on monads, and certainly Haskell. Of course monads and comonads existed in category theory well before this date, but not, as far as I know, for plumbing computer programs. I’d love to hear from anyone who knows more about the history these ideas.
Anonymous said...
Nice post. I've also found that haskell can really help in learning category theory.
Btw, what you say about polynomials as functions is incorrect:
"So a polynomial in R[x] is the same as a function from R to R that can be written in terms of elements of R, multiplication and addition."
This is not true in general, as for example x^p - x == 0 as a function in F_p. It is of course true only for infinite fields.
sigfpe said...
Anonymous,
While I tried to make it clear for categories, I should have also made it clearer for ordinary polynomials too - you need to have a suitable equivalence relationship on your polynomials before they are in 1-1 correspondence with functions written in terms of elements of R, multiplication and addition.
Derek Elkins said...
You will probably find this paper and the papers also discussed (at least some of which I'm sure you've already read) interesting.
Decomposing typed lambda calculus into a couple of categorical programming languages
Edward Kmett said...
sigfpe said...
Edward,
And of course the 'three way' version of the isomorphism I give involving monads requires a CCC as it uses currying. I should write out the full details as it's not in the book. When I have a moment...
Mikael Vejdemo-Johansson said...
Edward, does that difference in categories needed dualize neatly? Is there such a thing as a writer comonad, and do you get similar differences in category properties needed between the writer monad and comonad?
sigfpe said...
Hmm...if we dualise this we should get the notion of a coindeterminate, a symbol that sucks the value of subexpressions out of expressions.
Kim-Ee Yeoh said...
Mikael,
There is a monoidal comonad, although I'm not sure you'd want to call it a writer comonad. See Tarmo.
The usage is distinctly different, and I don't believe you get another monad/comonad isomorphism. The one above is the only one I know of, a consequence of product being left-adjoint to exponentiation.
Perhaps sigfpe might want to blog a nice illustration of the monoidal comonad?
sigfpe said...
Thanks Derek, that paper looks does look interesting.
Edward Kmett said...
Mikael,
the dual of the writer monad is takes a comonoidal structure. in other words instead of a binary operation
join :: a * a -> a,
you need a
split :: a -> a * a
The Iavor's implementation of Augustsson, Rittri, and Synek's Supply comonad (included in category-extras) models this approximately, but uses dirty unsafePerformIO tricks to avoid excessive splitting.
I have intended to get around to adding a SupplyT comonad transformer and a pure Supply comonad, but haven't taken the time.
Finally, note that linear implicit parameters in Haskell (plague though they may be on the semantics of Haskell) implement pretty much this very idea and are a useful source of inspiration if you are looking for intuition on the use of this comonad.
Edward Kmett said...
kim-ee:
An implementation of the exponent comonad:
Peter Berry said...
What's wrong with the idea of "Kleisli category of a comonad"? It seems unambiguous to me (even if I don't fully understand comonads). Or is there some difference between "Kleisli" and "coKleisli", e.g. does it make sense to have the coKleisli category of a monad?
Edward Kmett said...
Peter:
The 'Kleisli category of a comonad' is unambiguous. It is also more verbose than saying 'coKleisli category'. Since one often just says the 'Kleisli construction', this enables the use of 'coKleisli construction' without introducing ambiguity into the root term.
That said, one might argue that 'co' is used a little to freely. e.g. Why aren't 'cofree comonads' just free? After all, you have to say 'comonad' in there anyways. On the other hand, you have codensity monads and density comonads, so the co- in the adjective doesn't always follow from the root idea.
In the end, I tend to subscribe to the idea that using the shotgun approach of 'co-' everywhere it is applicable enables easier application and facilitates easier communication than requiring the user of the term to know in every case which form is appropriate.
Peter Berry said...
Hmm, I suppose "Kleisli category of T" for some functor T is ambiguous if T is both a monad and a comonad. Then you could say "Kleisli category of T as a monad" and "Kleisli category of T as a comonad", but since they're pretty verbose you'd rather just say "(co)Kleisli category", understanding that "Kleisli" refers to the monad and "coKleisli" to the comonad.
Anonymous said...
Off-topic, Dan, but would you have any opinion on Dorst/Mann's use of geometric algebra to present a unified view of ray-tracing?
geophf said...
sigfpe, the link to Wikipedia for rings seems to be broken. The link that I got working is the following:
http://en.wikipedia.org/wiki/Ring_(mathematics)
... but the link on the blog entry is currently ...
http://sigfpe.blogspot.com/%E2%80%9Dhttp://en.wikipedia.org/wiki/Ring_%28mathematics%29%E2%80%9D
... which seems not to work
geophf said...
sigfpe, FYI, the link to wikipedia for Ring seems to be broken. The link on your blog currently points to ...
http://sigfpe.blogspot.com/%E2%80%9Dhttp://en.wikipedia.org/wiki/Ring_%28mathematics%29%E2%80%9D
... which doesn't seem to work. The link to Ring in wikipedia that does work is the following:
http://en.wikipedia.org/wiki/Ring_(mathematics)
Piet Delport said...
"[...] introduce the function x:1->A where 1 is the terminal object in Hask, normally called ()."
s/terminal/initial/ ?
sigfpe said...
Piet,
1 is definitely terminal, there's always a map from X to 1 defined (in Haskell) by
const () :: a -> ()
0, or the 'empty' type defined by the (extended) Haskell
data Void
is initial.
'Elements' of objects X can be picked out using maps from the terminal object to X. So in Set maps 1->X are the same as elements of X.
Edward Kmett said...
() has two inhabitants _|_ and (), so there are multiple functions from a -> () the moment you allow recursion, which causes () to fail to be terminal.
Also because Haskell is not total you need to be careful, since
data Void
has a single inhabitant _|_ and satisfies (most of) the conditions for a terminal object.
Of course all of this is a pleasant fiction because in the presence of seq you can even distinguish some inhabitants of a -> _|_. But if we ignore seq we get nice properties.
Unfortunately, since _|_ is an inhabitant of every type in Haskell, there is no initial object in Hask.
One way to see Void is not initial is to see that there is no uniqueness to the function from Void -> a for each a in Haskell. you are free to choose any inhabitant of a, each giving rise to another morphism in the category. The uniqueness constraint is violated. If we were strict then we might be able to say that the only member of that type was a function returning _|_.
Another way to look at it: for Hask to be comonoidal there would have to be a type Void for which 'Either Void a' can only contain 'Right a's since you can have 'Left _|_'s. This prevents the category of Haskell types from being CoCartesian.
This is why in category-extras this constraint is captured by saying Hask is pre-(co-Cartesian closed).
sigfpe said...
Edward,
I did mention that I was dealing with a subset of Haskell that allows only total functions. It's messy otherwise.
Edward Kmett said...
Sorry about that. I forgot the context of the article. It has been long enough that this thread has kind of taken on a life of its own. =)
Piet Delport said...
Dan, Edward, thank you for the explanation; it makes sense now.
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http://crypto.stackexchange.com/questions?page=34&sort=active
|
# All Questions
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### On the Definition of a PRG and a CSPRG
I've been looking at the definition of a PRG, here. This is a broader notion than a cryptographically secure PRG ("CSPRG"), which is described here. I am realizing that I am very confused by this ...
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### Is digest=HASH(HASH(a)+HASH(b)) equivalent to publishing two digests?
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### Why do we append the length of the message in SHA-1 pre-processing?
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### Weaker Notion of Target Collision Resistance
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### Random numbers for Rabin-Miller primality tests
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### Importance of block size in CBC mode
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### Why are the constants so simple in Keccak?
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### Perfect Secrecy -> One Time Semantic Security -> Secure PRG
I think I have some sense of what Perfect Security means, and even Semantic Security, but I am struggling with randomness, so I'm going to ask a question about CSPRG's (Cryptographically Secure PRG's) ...
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### How do you find the inverse degree of a hash function?
I am trying to learn cryptanalysis on the Keccak hash function. One of the papers on zero sum distinguishers talks about Keccak having inverse degree of 3. I am unable to figure this out: how do you ...
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### Breaking a PRNG Scheme
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### Signing the hash of a key with the same key
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### Public-Key Deterministic Encryption : Why does not provide perfect security?
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### Encryption of a number with RSA bigger than $n$
I'm having trouble understanding why encrypting a number $m$, which is larger than $n=p\cdot q$. I've looked into the following threads: Why RSA can't handle numbers above 76? Why does plain RSA ...
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https://indico.tlabs.ac.za/event/85/contributions/1446/
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# Conference on Neutrino and Nuclear Physics (CNNP2020) Arabella Hotel and Spa, South Africa, 24-28 February 2020
23-28 February 2020
Africa/Johannesburg timezone
See YouTube for CNNP2020 presentations!
## Implications of new theoretical calculations on reactor antineutrino and gallium anomalies
28 Feb 2020, 09:20
20m
Parallel Venue
### Speaker
Joel Kostensalo (University of Jyvaskyla, Finland)
### Description
The reactor antineutrino and gallium anomalies have been long unexplained. Possible explanations for both of these anomalies include new physics, such as the existence of one or more eV-scale sterile neutrino [Ga15]. However, the previous theoretical calculations, which do not replicate the experimental results, rely on many simplifying approximations [Ba97,Ha19].
In the reactor-antineutrino analysis the beta decays contributing to the cumulative electron spectrum are usually assumed to have allowed spectral shapes. However, many of these decays are actually first-forbidden. Moreover, these decays dominate the experimentally observable region. In some cases, like in the case of the ground-state-to-ground-state decay of $^{140}\rm Cs$ (see figure), this is found to be a rather poor approximation. Based on the recent results, the use of this allowed approximation can at least partially explain the so called reactor antineurtino anomaly.
Our new large-scale shell model calculations regarding the neutrino-nucleus scattering cross section off $^{71}\rm Ga$ shows no statistical difference to the experimental results of GALLEX and SAGE experiments. Conflict between charge-exchange BGTs and the neutrino-nucleus cross sections can to some extent be explained by destructive interference between Gamow-Teller and tensor contributions. A Bayesian approach to estimating the significance of the gallium anomaly is discussed.
[Ga15] S. Gariazzo, C. Giunti, M. Laveder, Y. F. Li, and
E. M. Zavanin, J. Phys. G: Nucl. Part. Phys. 43, 033001
(2015).
[Ba97] J. N. Bahcall Phys. Rev. C 56, 3391 (1997).
[Ha19] L. Hayen, J. Kostensalo, N. Severijns, and J. Suhonen
Phys. Rev. C 99, 031301(R) (2019).
### Primary authors
Joel Kostensalo (University of Jyvaskyla, Finland) Jouni Suhonen (University of Jyväskylä) Dr Leendert Hayen (KU Leuven)
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https://hsm.stackexchange.com/questions/8050/what-geometric-results-were-first-proven-by-assuming-all-real-numbers-are-ration
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# What geometric results were first proven by assuming all real numbers are rational?
Pythagoras and his followers believed that all magnitudes are commensurable; that is, the ratio of two magnitudes of the same kind, like two lengths or two areas, is equal to the ratio of natural numbers. In modern language, this means that all real numbers are rational numbers. This allowed them to find out whether any two ratios of magnitude are equal: you just find out what ratio of natural numbers each one is equal to, and then compare those ratios to each other.
But Hippassus of Metapontum discovered that the ratio of a diagonal of a square to its side is not equal to a ratio of natural numbers. So a new definition was needed for when two ratios of magnitudes are equal. This was done by Eudoxus of Cnidus. In modern language, his definition says that two real numbers are equal if the same rational numbers are less than, equal to, and greater than them (basically the idea behind Dedekind cuts).
My question is, what results of geometry did the Pythagoreans prove using the incorrect assumption that all real numbers were rational? Long ago, I read a book, whose name I don't recall, which listed some results, and described how they had to be reproved with Eudoxus' new definition.
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http://slideplayer.com/slide/1420999/
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# 15.1 Notes Numerical approach to evaluating limits as x approaches negative or positive infinity.
## Presentation on theme: "15.1 Notes Numerical approach to evaluating limits as x approaches negative or positive infinity."— Presentation transcript:
15.1 Notes Numerical approach to evaluating limits as x approaches negative or positive infinity
15.1 Notes In addition to limits where x approaches a number, there are limits where x approaches infinity (or negative infinity). A limit as x is approaching infinity (or negative infinity) is asking what f(x) is getting close to as x is getter larger and larger.
15.1 Notes In todays do now assignment you were actually evaluating a limit where x approaches infinity. As larger and larger values are x were evaluated in the function provided, the f(x) values got closer and closer to one half. Although f(x) will never reach one half, the limit is equal to one half.
15.1 Notes Just like a graphing calculators table feature was used to evaluate limits as x approached a number, it can be used to evaluate limits as x approaches infinity. However, rather than setting up the table to simulate x jumping by small increments to get close to some number, the table is set up to simulate x approaching infinity.
15.1 Notes The functions equation is typed in on the Y= screen as before. In the Table Setup menu we were starting the table (TblStart) at the value x is approaching and choosing a small number for the increment (ΔTbl) by which the x values changed. How should the menu be set up to simulate approaching infinity? By choosing relatively large numbers for both the TblStart and the ΔTbl.
15.1 Notes Consider todays do now assignment again: Go to the Y= screen and type in the function.
15.1 Notes Press 2 nd and WINDOW (TBL SET) to bring up the Table Setup Menu. Start the table at some large value, say 10, and set the increment ( Tbl) to some large value, say 50.
15.1 Notes Press 2 nd and GRAPH (TABLE) to view the table.
15.1 Notes Scrolling further down the table reveals that.5 appears in the y column. Realize however, that because the Y column only has five decimal places, the calculator is rounding. The f(x) values get very close to but never actually reach it.
15.1 Notes Another example… Type the equation on the Y= screen.
15.1 Notes Choose large numbers in the Table Setup Menu. This time 50 is chosen for TblStart, 100 for ΔTbl.
15.1 Notes View the t-table: As you scroll up the table (simulating x approaching negative infinity) the y values appear to be getting closer to -.5.
15.1 Notes Another example… Type the equation on the Y= screen.
15.1 Notes Make sure the calculator is in radian mode since the limit is of a trigonometric function. Choose large numbers in the Table Setup Menu. This time 100 is chosen for TblStart and ΔTbl.
15.1 Notes View the t-table: As you scroll down the table (simulating x approaching infinity) the y values appear to be getting closer to 0.
15.1 Notes One more example… Type the equation on the Y= screen.
15.1 Notes Setup the table. 100 is used for TblStart and ΔTbl.
15.1 Notes View the table: Notice as you look down the values in the y column that they are getting larger and larger rather than approaching some value. The y values are also approaching infinity.
15.1 Notes – Practice Problems: 1. 2. 3. 4.
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https://math.stackexchange.com/questions/2584490/corollary-25-3-humphreys-linear-algebraic-groups
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# Corollary 25.3, Humphrey's Linear Algebraic Groups
I'm reading Humphrey's Linear Algebraic Groups (GTM 21). I don't understand the proof of Corollary 25.3(d).
Corollary. Let $G$ be reductive, $rank_{ss}G = 1$, $T$ a maximal torus of $G$, $Z = Z(G)^\circ$. Then:
(a) $(G,G)$ is semisimple, of dimension 3.
(b) $G = (G,G)\cdot Z$, the intersection of $(G,G)$ with $Z$ being finite.
(c) $C_G(T) = T$, and in particular, $Z(G) \subset T$.
(d) If $\varphi : G \to \mathrm{PGL}(2,\mathsf{K})$ is an epimorphism, $\operatorname{Ker}\varphi = Z(G)$.
You don't need to read all the proof. I can understand the proof of (a) (b) (c). I just don't understand the last sentence: "So (c) and (d) follows."
Proof. We get from part (f) of the theorem an epimorphism $\varphi : G \to \mathrm{PGL}(2,\mathsf{K})$, with $(\operatorname{Ker}\varphi)^\circ = R(G)$. Since $G$ is reductive, $R(G) = Z$ and is a torus. On the other hand, $\mathrm{PGL}(2, \mathsf{K})$ is its own derived group: for example, otherwise the derived group would be solvable, contrary to the semisimplicity of $\mathrm{PGL}(2,\mathsf{K})$. It follows that $\varphi$ maps $(G,G)$ onto $\mathrm{PGL}(2,\mathsf{K})$. Combined with the fact that $(G,G)$ is connected and the fact that $(G,G)\cap Z$ is finite, this proves both (a) and (b). It is easy to see that a maximal torus in $\mathrm{PGL}(2,\mathsf{K})$ is its own centralizer, by computing in $\mathrm{SL}(2,\mathsf{K})$, so $C_G(T)$ and $T$ have the same image under $\varphi$, forcing $T \subset C_G(T) \subset T\cdot \operatorname{Ker}\varphi$. But $T$ has finite index in the right side, while $C_G(T)$ is connected. So (c) and (d) follows.
It seems that the proof doesn't say anything about $\operatorname{Ker}\varphi$ except that $(\operatorname{Ker}\varphi)^\circ = Z$. we also know that $Z(G) \subset \operatorname{Ker}\varphi$, because the center of $\mathrm{PGL}(2,\mathsf{K})$ is trivial. So $Z(G)$ has finite index in $\operatorname{Ker}\varphi$.
How can I prove that $\operatorname{Ker}\varphi \subset Z(G)$? Am i missing something?
• I don't remember all these details when I learned linear algebraic groups. But I do remember constantly switching between Borel, Springer, and Humphreys when I was stuck on one book's explanation of something. – D_S Dec 31 '17 at 16:01
I'm not sure what Humphreys had in mind, but I think the following argument works. If $N$ is a finite normal subgroup of a connected group, then $N$ is contained in the center of that group (Exercise 7.11). We have $(\operatorname{Ker}\phi)^0 = Z(G)^0 = Z$, the radical of $G$. And we want to show that in fact $\operatorname{Ker}\phi = Z(G)$.
In the quotient group $G/(\operatorname{Ker}\phi)^0$, the subgroup $\operatorname{Ker}\phi/(\operatorname{Ker}\phi)^0$ is finite, hence contained in the center of $G/(\operatorname{Ker}\phi)^0$. Let $x \in \operatorname{Ker}\phi$, so that $x(\operatorname{Ker}\phi)^0$ is in the center of $G/(\operatorname{Ker}\phi)^0$. Then for all $y \in G$, $xyx^{-1}y^{-1} \in (\operatorname{Ker}\phi)^0 = Z$. But also $xyxy^{-1}$ is in the derived group of $G$, which has finite intersection with $Z$ (Lemma 19.5). So the image of the morphism
$$G \rightarrow G, y \mapsto xyx^{-1}y^{-1}$$
is finite and irreducible, hence a point. Therefore, $x \in Z(G)$.
On the other hand, if $x \in Z(G)$, then as you say, the image of $x$ in $G/\operatorname{Ker}\phi \cong \operatorname{PGL}_2$ is trivial, because $\operatorname{PGL}_2$ has trivial center.
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https://psychology.stackexchange.com/questions/13617/how-to-interpret-neuron-spiking-models-one-comes-across-in-literature
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# How to interpret neuron spiking models one comes across in literature?
## Background
I'm in high school currently conducting research (obviously it is relatively rudimentary compared to what is being done in the labs, etc.) in computational neuroscience.
I'm dealing with multiple datasets each containing time series data for a majority of neurons in C. Elegans (the dataset is the one used in Saul Kato's Global Brain Dynamics Embed the Motor Command Sequence of Caenorhabditis elegans).
I'm looking to do a pairwise comparison of each neuron in every dataset; if $N_{ij}$ is the $j^{th}$ neuron in the $i^{th}$ dataset, then I will do a pairwise comparison of all neurons in the $j^{th}$ column.
## Question
I'm going through this paper which proposes a method of comparing time series data across neurons. The paper uses this spiking model:
I'm wondering how neuroscientists approach such models they read about in literature; how they dissect it mathematically, what crosses their mind when they look at these models, etc. and where I can go to gain a rigorous foundation to truly and intuitively understand the models I read about in the future.
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https://ja.overleaf.com/latex/templates/quantum-journal-template/gsjgyhxrtrzy
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# Quantum journal template
Author
Christian Gogolin, Christopher Granade, Johannes J. Meyer, and Victor V. Albert
View Count
6446
AbstractThis is version 5.0 of quantumarticle, the document class for typesetting articles in Quantum - the open journal for quantum science.
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http://wangchaofeng.com/parseNote.php?note=notes_OS_tcp.note
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All notes
Tcp
# Intro
TcpIPGuide. TCP is implemented as a Finite State Machine.
### Congestion window
• The congestion window is maintained by the sender. Not to be confused with the TCP window size which is maintained by the receiver.
• The congestion window is a means of stopping a link between the sender and the receiver from getting overloaded with too much traffic, and is calculated by estimating how much congestion there is between the two places.
#### Congestion window vs reveiver window
To give a short answer: the receive window is managed by the receiver, who sends out window sizes to the sender. The window sizes announce the number of bytes still free in the receiver buffer, i.e. the number of bytes the sender can still send without needing an acknowledgement from the receiver.
The congestion window is a sender imposed window that was implemented to avoid overrunning some routers in the middle of the network path. The sender, with each segment sent, increases the congestion window slightly, i.e. the sender will allow itself more outstanding sent data. But if the sender detects packet loss, it will cut the window in half. The rationale behind this is that the sender assumes that packet loss has occurred because of a buffer overflow somewhere (which is almost always true), so the sender wants to keep less data "in flight" to avoid further packet loss in the future.
For more, start here: http://en.wikipedia.org/wiki/Slow-start
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https://eng.libretexts.org/Bookshelves/Computer_Science/Book3A_Programming_Fundamentals_-_A_Modular_Structured_Approach_using_C___(Busbee)/09%3A_Standard_Libraries/9.02%3A_Practice_8_Standard_Libraries
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# 9.2: Practice 8 Standard Libraries
## Learning Objectives
With 100% accuracy during a: memory building activity, exercises, lab assignment, problems, or timed quiz/exam; the student is expected to:
Define the terms on the definitions as listed in the modules associated with this chapter.
Given a testing shell program already coded and tested, add another specific task function, and test it, then create a user defined specific task header file, a user defined specific task prototypes document and a source code program to verify that the header file works properly.
## Exercises
Questions
1. The standard library is a set of specific task functions that have been added to the programming language for universal use.
2. Programmers should not have confidence that standard library functions work properly.
3. It would be easier to write programs without using specific task functions.
1. True
2. False
3. False
## Lab Assignment
#### Creating a Folder or Sub-Folder for Chapter 08 Files
Depending on your compiler/IDE, you should decide where to download and store source code files for processing. Prudence dictates that you create these folders as needed prior to downloading source code files. A suggested sub-folder for the Bloodshed Dev-C++ 5 compiler/IDE might be named:
• Chapter_08 within the folder named: Cpp_Source_Code_Files
If you have not done so, please create the folder(s) and/or sub-folder(s) as appropriate.
Download and store the following file(s) to your storage device in the appropriate folder(s). You may need to right click on the link and select "Save Target As" in order to download the file.
#### Detailed Lab Instructions
Read and follow the directions below carefully, and perform the steps in the order listed.
• Navigate to your sub-folder: Chapter_08. Compile and run the Lab 08 Testing Shell source code. Note: This program uses an include file that points to the "udst_monitor.h" file as explained in Connexions Chapter 7 materials.
• You need to add another function to this testing shell titled: area_triangle that is to calculate the area of a triangle. Define the function, prototype it, and within the function main add an area for calling the function (similar to the existing functions with test data). Be confident that it is working properly.
• Following same process as shown in the Connexions module "Using a Header File for User Defined Specific Task Functions" that is within the Chapter 7 materials; make the following files: udst_geo_area.h and udst_geo_area_prototypes.txt and Lab_08_Verify_Header.cpp
• After you have successfully written this program, if you are taking this course for college credit, follow the instructions from your professor/instructor for submitting it for grading.
## Problems
#### Problems 08a - Instructions
Write the C++ code to do the following specific task function.
Pseudocode
Function area_regular_hexagon
Pass In: side
Calculate: side times side times 3 times the square root of 0.75
Pass Out: the calculation
Endfunction
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https://aimsciences.org/article/doi/10.3934/dcdsb.2013.18.377
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# American Institute of Mathematical Sciences
March 2013, 18(2): 377-401. doi: 10.3934/dcdsb.2013.18.377
## Hysteresis and post Walrasian economics
1 Department of Economics, University of Strathclyde, Glasgow G4 0GE, United Kingdom 2 Oxford Centre for Collaborative Applied Mathematics, University of Oxford, Oxford OX1 3LB, United Kingdom 3 32 Campus Drive, Department of Mathematical Sciences, University of Montana, Missoula, MT 59812, United States 4 Department of Applied Mathematics, University College, Cork
Received September 2011 Revised January 2012 Published November 2012
The new consensus'' DSGE(dynamic stochastic general equilibrium) macroeconomic model has microfoundations provided by a single representative agent. In this model shocks to the economic environment do not have any lasting effects. In reality adjustments at the micro level are made by heterogeneous agents, and the aggregation problem cannot be assumed away. In this paper we show that the discontinuous adjustments made by heterogeneous agents at the micro level mean that shocks have lasting effects, aggregate variables containing a selective, erasable memory of the shocks experienced. This hysteresis framework provides foundations for the post-Walrasian analysis of macroeconomic systems.
Citation: Rod Cross, Hugh McNamara, Leonid Kalachev, Alexei Pokrovskii. Hysteresis and post Walrasian economics. Discrete & Continuous Dynamical Systems - B, 2013, 18 (2) : 377-401. doi: 10.3934/dcdsb.2013.18.377
##### References:
show all references
##### References:
[1] Vincenzo Recupero. Hysteresis operators in metric spaces. Discrete & Continuous Dynamical Systems - S, 2015, 8 (4) : 773-792. doi: 10.3934/dcdss.2015.8.773 [2] J. Samuel Jiang, Hans G. Kaper, Gary K Leaf. Hysteresis in layered spring magnets. Discrete & Continuous Dynamical Systems - B, 2001, 1 (2) : 219-232. doi: 10.3934/dcdsb.2001.1.219 [3] Jiyu Zhong, Shengfu Deng. Two codimension-two bifurcations of a second-order difference equation from macroeconomics. Discrete & Continuous Dynamical Systems - B, 2018, 23 (4) : 1581-1600. doi: 10.3934/dcdsb.2018062 [4] Jana Kopfová. Nonlinear semigroup methods in problems with hysteresis. Conference Publications, 2007, 2007 (Special) : 580-589. doi: 10.3934/proc.2007.2007.580 [5] Martin Brokate, Pavel Krejčí. Weak differentiability of scalar hysteresis operators. Discrete & Continuous Dynamical Systems - A, 2015, 35 (6) : 2405-2421. doi: 10.3934/dcds.2015.35.2405 [6] Antonio DeSimone, Natalie Grunewald, Felix Otto. A new model for contact angle hysteresis. Networks & Heterogeneous Media, 2007, 2 (2) : 211-225. doi: 10.3934/nhm.2007.2.211 [7] Pavel Gurevich. Periodic solutions of parabolic problems with hysteresis on the boundary. Discrete & Continuous Dynamical Systems - A, 2011, 29 (3) : 1041-1083. doi: 10.3934/dcds.2011.29.1041 [8] Claudio Giorgi. Phase-field models for transition phenomena in materials with hysteresis. Discrete & Continuous Dynamical Systems - S, 2015, 8 (4) : 693-722. doi: 10.3934/dcdss.2015.8.693 [9] Emil Minchev, Mitsuharu Ôtani. $L^∞$-energy method for a parabolic system with convection and hysteresis effect. Communications on Pure & Applied Analysis, 2018, 17 (4) : 1613-1632. doi: 10.3934/cpaa.2018077 [10] Michela Eleuteri, Pavel Krejčí. An asymptotic convergence result for a system of partial differential equations with hysteresis. Communications on Pure & Applied Analysis, 2007, 6 (4) : 1131-1143. doi: 10.3934/cpaa.2007.6.1131 [11] Augusto Visintin. P.D.E.s with hysteresis 30 years later. Discrete & Continuous Dynamical Systems - S, 2015, 8 (4) : 793-816. doi: 10.3934/dcdss.2015.8.793 [12] Pavel Krejčí. The Preisach hysteresis model: Error bounds for numerical identification and inversion. Discrete & Continuous Dynamical Systems - S, 2013, 6 (1) : 101-119. doi: 10.3934/dcdss.2013.6.101 [13] Augusto Visintin. Ohm-Hall conduction in hysteresis-free ferromagnetic processes. Discrete & Continuous Dynamical Systems - B, 2013, 18 (2) : 551-563. doi: 10.3934/dcdsb.2013.18.551 [14] Youssef Amal, Martin Campos Pinto. Global solutions for an age-dependent model of nucleation, growth and ageing with hysteresis. Discrete & Continuous Dynamical Systems - B, 2010, 13 (3) : 517-535. doi: 10.3934/dcdsb.2010.13.517 [15] Dmitrii Rachinskii. Realization of arbitrary hysteresis by a low-dimensional gradient flow. Discrete & Continuous Dynamical Systems - B, 2016, 21 (1) : 227-243. doi: 10.3934/dcdsb.2016.21.227 [16] Takanobu Okazaki. Large time behaviour of solutions of nonlinear ode describing hysteresis. Conference Publications, 2007, 2007 (Special) : 804-813. doi: 10.3934/proc.2007.2007.804 [17] Steffen Härting, Anna Marciniak-Czochra, Izumi Takagi. Stable patterns with jump discontinuity in systems with Turing instability and hysteresis. Discrete & Continuous Dynamical Systems - A, 2017, 37 (2) : 757-800. doi: 10.3934/dcds.2017032 [18] Stefano Bosia, Michela Eleuteri, Elisabetta Rocca, Enrico Valdinoci. Preface: Special issue on rate-independent evolutions and hysteresis modelling. Discrete & Continuous Dynamical Systems - S, 2015, 8 (4) : i-i. doi: 10.3934/dcdss.2015.8.4i [19] Xiao-Ping Wang, Xianmin Xu. A dynamic theory for contact angle hysteresis on chemically rough boundary. Discrete & Continuous Dynamical Systems - A, 2017, 37 (2) : 1061-1073. doi: 10.3934/dcds.2017044 [20] Nobuyuki Kenmochi, Jürgen Sprekels. Phase-field systems with vectorial order parameters including diffusional hysteresis effects. Communications on Pure & Applied Analysis, 2002, 1 (4) : 495-511. doi: 10.3934/cpaa.2002.1.495
2018 Impact Factor: 1.008
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https://brilliant.org/problems/two-squares-2/
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# Two squares
How many integers between 1 and 100 inclusive can be expressed as the sum of 2 perfect squares?
×
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http://math.stackexchange.com/users/55007/undo?tab=activity&sort=comments
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Undo
Reputation
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Jan 2 comment In a Calculator, Which Button Should be Bigger: $\sinh()$ or $\rm asin()$? @CBenni Thanks a ton! Jan 2 comment In a Calculator, Which Button Should be Bigger: $\sinh()$ or $\rm asin()$? Thanks! Will take into consideration! Jan 2 comment In a Calculator, Which Button Should be Bigger: $\sinh()$ or $\rm asin()$? Thanks! You just changed how my app works! (Good Thing)
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https://math.meta.stackexchange.com/questions/27838/how-to-discourage-users-from-using-the-functions-tag?noredirect=1
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# How to discourage users from using the “functions” tag
The following is the tag info for the functions tags:
In mathematics, a function is a relation between a set of inputs and a set of permissible outputs with the property that each input is related to exactly one output. A function is defined by its set of inputs, called the domain; a set containing the set of outputs, and possibly additional elements, as members, called its codomain ; and the set of all input-output pairs, called its graph. Sometimes the codomain is called the function's range, but more commonly the word "range" is used to mean, instead, specifically the set of outputs (also called the image of the function). For example, we could define a function using the rule $f(x) = x^2$ by saying that the domain and codomain are the real numbers, and that the graph consists of all pairs of real numbers $(x, x^2)$.
In 2010 the tags emerged and it is suggested to be deleted. Seems nothing had been done. There were around 500 questions tagged with "functions" in 2011. Now in 2018, we have over 19,000 questions tagged with "functions".
Probably we all know why: whenever a question involves functions, people add the "functions" tag.
Not only that this is not what the tag info suggested, but also it makes the tag useless.
My questions is: How can we discourage people from using the "function" tag?
This is what I have in mind:
• Add to the tag info that one should not use the tag simply because you used functions in the questions (But really, who will read the tag info before using the tag?)
• Change the name from function to mapping. (Not sure how it can be done).
• I agree - the functions tag is useless and way too broad. Basically every question could be tagged that. – user223391 Feb 5 '18 at 3:47
• Does having it as a tag even contribute anything at all? The only usage I can see other than "this question has a function in it" is when the questuon specifically relates to the function-ness of a function, which may be better served by something like a "well-defined" tag. – Alexander Gruber Feb 5 '18 at 5:42
• @AlexanderGruber I have made a suggestion about what should be in the functions tag some time ago: About (functions) tag. Other than one comment, nobody participated in that discussion - and the answer with the proposal got to score +1, which doesn't really count as consensus. – Martin Sleziak Feb 5 '18 at 7:27
• To add som specific examples, I would consider the question listed here as reasonable candidates for the (functions) tag: Overview of basic results about images and preimages. Similarly, the typical questions about properties of injective/surjective/bijective functions. – Martin Sleziak Feb 5 '18 at 7:29
• There are currently 3294 questions with only the [functions] tag. This is quite an immense effort to retag them and blacklist the tag entirely. – Asaf Karagila Feb 5 '18 at 10:36
• @MartinSleziak: The question you linked probably include most of the questions types that should be tagged "functions", if not all. If used correctly I guess there should not be more than 1k such questions, dupicates included. – user99914 Feb 5 '18 at 14:43
• @AsafKaragila That's why I hesitated to suggest blacklisting the tag. – user99914 Feb 5 '18 at 14:45
• John, in the past with blacklisted the [homework] tag. I don't remember the exact number, but there were a lot of questions which had only that as a tag. After it was clear the consensus was to blacklist, a massive effort was undertaken to fix these questions, and then the blacklist happened. So first we need to discuss, in a certain urgent immediacy, whether or not this tag should be phased out entirely. – Asaf Karagila Feb 5 '18 at 14:46
• I am not sure if we will have a majority decision on that. I think it is clear this tag are misused everyday, but some questions could be tagged "functions", as Martin suggested. In the mean time I will try to re-tag/close/delete some questions with that tags slowly. – user99914 Feb 5 '18 at 19:03
• This is why I said we first need to poll for more opinions. I flagged for moderator attention to add a [featured] tag to increase visibility. I hope this will be done. – Asaf Karagila Feb 5 '18 at 22:08
• While I agree that there is a certain class of questions that could benefit from being tagged [functions], I'm not sure how much benefit there is to this that would not already be gained by tagging them with [elementary-set-theory]. And as long as the [functions] tag exists, it's going to be abused a lot. – Eric Wofsey Feb 6 '18 at 0:10
• What about renaming it to "function-properties"? It's certainly more specific than "functions" and probably wouldn't be applied to anything with a function in it. – celtschk Feb 6 '18 at 9:03
• I think that some polling answers should be posted, perhaps. It would help to get some actual feedback from the community. So far all we have is a bunch of comments and very little active participation as far as discussions go. – Asaf Karagila Feb 12 '18 at 16:13
• 2) I don't think moderators are responsible for that. Moreover, if such a measure is needed, probably stronger measure has to be done on the tag itself. 3) Most of the question wrongly tagged as "functions" are not from "functional analysis". @Narasimham – user99914 Feb 25 '18 at 3:11
• The description of the function tag should not just be a definition of "function." The description of a tag should be what the tag is for, not a definition. Doubt that would help solve the problem of misuse of the tag, since most posters don't read the description, I'd guess. – Thomas Andrews Feb 28 '18 at 15:55
The name of the "functions" tag should be changed.
We could change it to "mapping", or "functions-properties" as suggested.
Quoting celtschk: It's certainly more specific than "functions" and probably wouldn't be applied to anything with a function in it.
This should also be implemented quite easily. It is not completely clear how effectively it could be though. We might also needs to go back to the existing 19000 questions to see if the new name are suitable for them.
• BTW, my suggestion was "function-properties", not "functions-properties". – celtschk Feb 26 '18 at 7:37
We should blacklist the "functions" tag.
Just like what we did for homework. In paricular, this means similarly that we will request the SE team to completely remove the tag from the system and ensure that it cannot be re-created. This will result in a large number (at present over 3200) of untagged questions, which will be the responsibility of the community to fix.
If the problem is the existence of the tag itself, blacklisting would completely solve the problem.
However, as suggested in the comment, there are some questions that "functions" serves as an suitable tag. And after trying to retag some questions in the tag, the retagging work is not completely trivial.
The "functions" tag should be deprecated.
We should add in the tag wiki that users should use a more specific tag, like "algebra-precalculus or elementary-set-theory. This is similar to what we did on "analysis" tag, see here.
One advantage is that it can be implemented easily. The disadvantage is, obviously, that it is not so effective. There are more than 240000 questions tagged with "analysis", and around 100 new questions tagged with "analysis" every week. The tag info page shows that the page has only around 400 views.
• This is not a great solution. To some extent, the discrete-mathematics was "deprecated", and it is still alive and kicking. If the functions tag is so bad, I'd rather put the effort into retagging and blacklisting, with the option of creating new tags to compensate for that. – Asaf Karagila Feb 15 '18 at 10:05
I suggest extending functions with the specific self-describing names that the tags might apply to. The extensions serve to more appropriately label the space to a degree whose efficacy varies directly with the propriety of the tags. I suggest prepending the word function to tags that might want to specify so that users may explore the space of tags through autocomplete. This might lead to better questions.
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https://robotics.stackexchange.com/questions/21390/create2-getting-strange-data-reading-sensor-data
|
# Create2: Getting strange data reading sensor data
I am new to Create2 and I hope someone can help me.
I have a problem with reading the sensor data or the data I get.
I have setup a nodeJS application running on a Raspberry PI 3B+. Sending data (e.g: drive commands) is no problem - the robot makes what I want.
At program start I send the optcodes 128 (start) and 132 (full mode). After that I send optcode 148 with the packageIds to start streaming. This works also very fine. I have defined the sensors I need in an array:
this.readCommands = [
{
packetId: 21, //Charging state
len: 1,
name: 'Charging state',
signed: false,
value: 0
},
{
packetId: 25, //Battery charge
len: 2,
name: 'Battery charge',
signed: false,
value: 0
},
{
packetId: 26, //Battery capacity
len: 2,
name: 'Battery capacity',
signed: false,
value: 0
},
{
packetId: 28, //Cliff left Signal
len: 2,
name: 'Cliff left Signal',
signed: false,
value: 0
},
{
packetId: 29, //Cliff front left Signal
len: 2,
name: 'Cliff font left Signal',
signed: false,
value: 0
},
{
packetId: 30, //Cliff front right Signal
len: 2,
name: 'Cliff front right Signal',
signed: false,
value: 0
},
{
packetId: 31, //Cliff right Signal
len: 2,
name: 'Cliff right Signal',
signed: false,
value: 0
},
{
packetId: 46, //Light Bump Left Signal
len: 2,
name: 'Light Bump Left Signal',
signed: false,
value: 0
},
{
packetId: 47, //Light Bump Front Left Signal
len: 2,
name: 'Light Bump Front Left Signal',
signed: false,
value: 0
},
{
packetId: 48, //Light Bump Center Left Signal
len: 2,
name: 'Light Bump Center Left Signal',
signed: false,
value: 0
},
{
packetId: 49, //Light Bump Center Right Signal
len: 2,
name: 'Light Bump Center Right Signal',
signed: false,
value: 0
},
{
packetId: 50, //Light Bump Front Right Signal
len: 2,
name: 'Light Bump Front Right Signal',
signed: false,
value: 0
},
{
packetId: 51, //Light Bump Right Signal
len: 2,
name: 'Light Bump Right Signal',
signed: false,
value: 0
}
];
To fill the 148-data:
const tempArr = [148, this.readCommands.length];
this.writeToPort(Uint8Array.from(tempArr)).subscribe(() => {
});
When data arrives I collect the data and when I have a full package I try to interpret the data. The packets I get seem to be ok (also the checksum is fine)
Here one as UINT8s:
19, 38, 21, 0, 25, 9, 253, 26, 10, 137, 28, 10, 46, 29, 10, 77, 30, 10, 86, 31, 10, 83, 46, 0, 31, 47, 0, 65, 48, 0, 59, 49, 0, 22, 50, 0, 24, 51, 0, 6, 50
But when I take these values I have data, e.g. for cliff-signals, that are much more greater than 4095 as described in the OI spec.
Also I get a battery capacity of 35082 while battery charge is greater than 60000.
Here's my code for reading the packet:
if (!this._checkData(data))
return;
let index = 2;
while (index < data.length-1) {
const cmd = this.readCommands.find(c => c.packetId === id);
if (!cmd) {
index++;
continue;
}
switch (cmd.len) {
case 1:
index+=2;
break;
case 2:
index+=3;
break;
}
}
What am I doing wrong?
When I reset the robot I get the message:
Soft reset!
Roomba by iRobot!
stm32 2016-06-13-1127-L
battery-current-zero
254
b
box vars restored!
languages: english (0)
Is the firmware too old? Can someone help me with that problem?
Daniel
I think you're swapping the bytes in your multi-byte messages. Considering just the battery charge and capacity, you said:
Here one as UINT8s:
19, 38, 21, 0, 25, 9, 253, 26, 10, 137, 28, 10, 46, 29, 10, 77, 30, 10, 86, 31, 10, 83, 46, 0, 31, 47, 0, 65, 48, 0, 59, 49, 0, 22, 50, 0, 24, 51, 0, 6, 50
I get a battery capacity of 35082 while battery charge is greater than 60000
So, looking at battery charge:
25, 9, 253
That's giving you packet ID 25, which is battery charge, and then two bytes, which in hex are:
9 = 0x09
253 = 0xFD
You need to merge the two bytes to get the full value; if you put them together as 0x09FD then you get 2,557. If you swap them, then you get 0xFD09, which is 64,777.
Similarly, with the battery capacity, you have the response
26, 10, 137
which would be the hex values 10 = 0x0A and 137 = 0x89. You can join them as 0x0A89 and get 2,697 or you can swap them and join as 0x890A and get 35,082.
A test like this, where you try interpreting the data both ways, can be an easy way to check if you're doing it correctly - with the bytes swapped, your charge is greater than your capacity, which doesn't make sense. When done correctly, though, it looks like the battery capacity is about 2.7 Ah and the current charge is about 2.6 Ah - looks good!
It took me a while to find which way it should be interpreted in the Open Interface specification (warning: direct download). I didn't see where it said anything about byte order until the "Quick Reference" section at the end of the spec, where it states
Some of the sensor data values are 16 bit values. These values are sent as two bytes, high byte first.
That's telling you that the first byte is the "most significant" byte and the second byte is the "least significant" byte, which is exactly how we're treating the data in the correct interpretation.
Hope this helps!
• Oh, you're right. I guess I didn't think enough about the values and was irritated by the maximum value of over 60,000 in the specs. I guess I found values around 2,000 to be a bit low :-)<br> But it would be a top battery with more than 60Ah. <br><br> So, thanks for your help! – Daniel Nov 17 '20 at 14:50
|
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|
http://physics.stackexchange.com/questions/57000/number-of-configurations-of-the-universe
|
# Number of configurations of the universe
I have read that quantum mechanics says that the amount of possible particle configurations is $10^{10^{122}}$ to be exact in the universe. Do we know this figure to be exactly true to the exact figure? Wouldn't we need to know a true theory of quantum gravity to know the exact answer? Is the amount exactly that figure or just an estimate?
-
John, you have the power to delete question with no upvoted answers, but you should not remove the content from posts and leave it on the site. Posts here are not ephemeral, they are expected to last delete it if you must but do not erase it that way. – dmckee Mar 16 '13 at 0:18
I'm sorry I was embarrassed by my question in the end will not happen again – John rose Mar 16 '13 at 1:53
This is clearly an estimate, not an exact figure. It comes from ideas about quantum gravity (not proven but very strong conjecture) that say that the maximum entropy of a region is
$$S = \frac{A}{4 \ell_P^2},$$
where $A$ is the area of a surface bounding the region and $\ell_P \approx 10^{-35}\ \mathrm{m}$ is the Planck length.
Now entropy is a measure of the number of configurations available to a system (units where $k_B=1$):
$$S = \ln \Omega.$$
Putting this together with the observed size of the universe for $A$ gives roughly the figure you mention.
-
|
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|
https://www.physicsforums.com/threads/cylindrical-spherical-coordinates.667344/
|
# Cylindrical / Spherical Coordinates
1. Jan 27, 2013
### eurekameh
I'm trying to convert the below Cartesian coordinate system into cylindrical and spherical coordinate systems. For the cylindrical system, I had r,vector = er,hat + sint(e3,hat).
While I do have a technically correct answer for the spherical coordinate system, I believe, I was wondering if there was a way to simplify the expression 1/cos[tan^-1*(sint)]. Thanks.
2. Jan 27, 2013
### Staff: Mentor
$r=\sqrt{x^2+y^2+z^2} = \sqrt{1+\sin^2(t)}$?
3. Jan 27, 2013
### eurekameh
Also, am I right in thinking r = rad(x^2 + y^2) = 1 for cylindrical coordinates?
4. Jan 27, 2013
### Staff: Mentor
Would be interesting to check this in an analytic way.
If you use (r,theta,z) as coordinates: Right.
|
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|
https://www.vedantu.com/question-answer/the-product-of-two-consecutive-positive-integers-class-10-maths-icse-5eeb4e158a7c21162c2c2865
|
Question
The product of two consecutive positive integers is 306. Form the quadratic equation to find x, if x denotes the smaller integer.
Hint: In this particular question assume any variable be the smallest positive integer so (variable + 1) is the consecutive positive integer greater than the variable so use these concepts to reach the solution of the question.
Let x be the smallest positive integer.
So, (x + 1) is the consecutive positive integer greater than x.
Now it is given that the product of two consecutive positive integers is 306.
So, first form the quadratic equation.
$\Rightarrow x\left( {x + 1} \right) = 306$
Now simplify the above equation we have,
$\Rightarrow {x^2} + x - 306 = 0$
So this is the required quadratic equation.
Now factorize this equation we have,
$\Rightarrow {x^2} + 18x - 17x - 306 = 0$
Now simplify the above equation we have,
$\Rightarrow x\left( {x + 18} \right) - 17\left( {x + 18} \right) = 0$
$\Rightarrow \left( {x + 18} \right)\left( {x - 17} \right) = 0$
$\Rightarrow \left( {x + 18} \right) = 0,{\text{ }}\left( {x - 17} \right) = 0$
$\Rightarrow x = 17, - 18$
So the positive integer is 17.
Therefore two consecutive positive integers are 17 and (17 + 1 = 18) whose product is 306.
Therefore the smallest positive integer is 17.
So this is the required answer.
Note: Whenever we face such types of questions the key concept is the construction of a quadratic equation according to given information in the problem statement then solve this quadratic equation as above and calculate the value of x which is the required smallest positive integer so that the product of two consecutive positive integer is 306.
|
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|
https://gmatclub.com/forum/calling-all-2014-consortium-applicants-153311-240.html
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Calling All 2014 Consortium Applicants
Author Message
Intern
Joined: 06 Nov 2013
Posts: 9
Location: United States
Followers: 0
Kudos [?]: 5 [0], given: 0
Re: Calling All 2014 Consortium Applicants [#permalink]
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19 Jan 2014, 20:53
tdesena wrote:
ceecee wrote:
PolicyWonk wrote:
I just got my email about the Ross interview. Apparently they have an on-campus CGSM interview day in Feb. Nothing on my end from Haas. I submitted everything on the deadline day.
good luck R2s!
I too received an invite from Ross and plan to attend during CGSM event. Congrats!
Posted from my mobile device
I got the cgsm event/interview invite as well! I'm really nervous about the group exercise though....
are you guys planning on attending the event for sure? where are you guys located? I can't decide whether to interview with alumni in town or attend the event....
Manager
Joined: 25 Jul 2012
Posts: 53
Concentration: General Management
Followers: 0
Kudos [?]: 22 [0], given: 12
Re: Calling All 2014 Consortium Applicants [#permalink]
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20 Jan 2014, 10:19
.
Last edited by BigUp on 21 Jan 2014, 14:27, edited 1 time in total.
Manager
Joined: 21 Nov 2009
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Re: Calling All 2014 Consortium Applicants [#permalink]
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21 Jan 2014, 09:05
I received an interview invite from Ross, but then I received an email from CGSM that they needed my transcript. I checked the application and my transcript was uploaded successfully. Did anyone else get this?
Current Student
Joined: 02 Feb 2012
Posts: 56
Location: United States
Concentration: Finance
WE: Asset Management (Mutual Funds and Brokerage)
Followers: 0
Kudos [?]: 16 [0], given: 1
Re: Calling All 2014 Consortium Applicants [#permalink]
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21 Jan 2014, 09:42
SCBooth wrote:
I received an interview invite from Ross, but then I received an email from CGSM that they needed my transcript. I checked the application and my transcript was uploaded successfully. Did anyone else get this?
I got the email regarding my transcript as well this past Thursday. When I talked to Corey Webb, the director of recruiting, he said that my transcript was unreadable. I guess because when I scanned it to upload it, the word void appears all over the digital copy. I just had to have my school send an official copy to him electronically to rectify this issue.
Just contact him to make sure.
On another note, I still haven't recieved an email stating that my application was sent to the schools I applied to. Getting a little nervous.
Manager
Joined: 27 Feb 2012
Posts: 94
Concentration: General Management, Nonprofit
GMAT 1: 700 Q47 V39
Followers: 0
Kudos [?]: 27 [1] , given: 42
Re: Calling All 2014 Consortium Applicants [#permalink]
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21 Jan 2014, 11:09
1
KUDOS
BigUp wrote:
So, the timing of this fellowship draft is not really optimal. I have been fortunate enough to get into a couple of my round 1 schools (non-consortium), but they require that I pay a deposit to hold my spot in the class in late feb/early march. The draft is in mid march. I would definitely attend one of these schools, but I'm hoping for the fellowship from my #1 consortium school...
Anyone else in a similar position? How would you guys approach this?
This is my biggest gripe with the draft system of the Consortium. There is absolutely no benefit to applying round 1 when it comes to fellowships unless you're putting Ross or Yale #1. I was in a similar position as you and just decided to do all my apps round 2. The risk was that my competition would be tougher. But I decided I'd rather see all my financial options in front of me at the same time.
So really you have two choices.
1. Pay the deposit at your round 1 school and wait. If you get a fellowship then you lose a few thousand that you put down for a deposit.
2. Decline admission and gamble on the CGSM fellowship
Manager
Joined: 25 Jul 2012
Posts: 53
Concentration: General Management
Followers: 0
Kudos [?]: 22 [0], given: 12
Re: Calling All 2014 Consortium Applicants [#permalink]
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21 Jan 2014, 14:27
So, if I received a "consortium scholarship" from my number two ranked school but have yet to receive an admission decision from my number one, what exactly does that mean? I thought that schools not ranked #1 wouldnt be able to offer any consortium related money until the draft...
And is it safe to assume that a "consortium scholarship" is not a "consortium fellowship"?
Current Student
Joined: 02 Feb 2012
Posts: 56
Location: United States
Concentration: Finance
WE: Asset Management (Mutual Funds and Brokerage)
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Re: Calling All 2014 Consortium Applicants [#permalink]
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21 Jan 2014, 14:27
Just got an email from one of the schools I submitted to stating that the Consortium has extended their application deadline to January 31st.
Manager
Joined: 20 Jun 2011
Posts: 77
Concentration: Healthcare, Strategy
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Kudos [?]: 22 [1] , given: 24
Re: Calling All 2014 Consortium Applicants [#permalink]
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21 Jan 2014, 14:37
1
KUDOS
BigUp wrote:
So, if I received a "consortium scholarship" from my number two ranked school but have yet to receive an admission decision from my number one, what exactly does that mean? I thought that schools not ranked #1 wouldnt be able to offer any consortium related money until the draft...
And is it safe to assume that a "consortium scholarship" is not a "consortium fellowship"?
BigUp,
I would say that you did not get the Consortium named fellowship. More than likely the school found you worthy of a merit based scholarship. Since you applied to them through the Consortium they called it "Consortium Scholarship." An Ad Com member from UNC told me that they review CGSM applicants against all available money, not just CGSM fellowship dollars. Some CGSM admits get other scholarships and fellowships besides the named Consortium Fellowship. It really does not matter if the money is scholarship or fellowship, if you are granted membership into the Consortium you will still go to OP. Congrats on the $though! Intern Joined: 13 Nov 2013 Posts: 14 Followers: 0 Kudos [?]: 10 [0], given: 5 Re: Calling All 2014 Consortium Applicants [#permalink] Show Tags 21 Jan 2014, 15:12 Anyone receive an interview invite from Darden yet? I noticed on the school's GC msg board that invitations were sent out today. Manager Joined: 01 Jan 2013 Posts: 75 Location: United States GPA: 3.5 WE: Consulting (Consulting) Followers: 0 Kudos [?]: 30 [0], given: 2 Re: Calling All 2014 Consortium Applicants [#permalink] Show Tags 22 Jan 2014, 10:58 Round 2: I've gotten an interview invite from Ross, and a receiving confirmation from Haas. Has anyone gotten anything from Anderson?? Manager Joined: 01 May 2013 Posts: 77 Followers: 0 Kudos [?]: 23 [0], given: 13 Re: Calling All 2014 Consortium Applicants [#permalink] Show Tags 22 Jan 2014, 12:25 I haven't heard anything at all from Haas or Anderson. I received confirmation of application from UT, NYU and UNC. Intern Joined: 17 Jan 2014 Posts: 23 Location: United States Concentration: Healthcare GMAT 1: 640 Q39 V39 GPA: 3.57 WE: Psychology and Counseling (Health Care) Followers: 0 Kudos [?]: 12 [0], given: 18 Re: Calling All 2014 Consortium Applicants [#permalink] Show Tags 22 Jan 2014, 12:45 meeeshelleee wrote: are you guys planning on attending the event for sure? where are you guys located? I can't decide whether to interview with alumni in town or attend the event.... I am planning on attending their Consortium/Conference weekend. I'm from Boston, but as Ross is my first choice I felt like it was too good of an opportunity to pass up going to Ann Arbor! Manager Joined: 06 Oct 2013 Posts: 56 Location: United States Concentration: Marketing, Other WE: Sales (Consumer Products) Followers: 0 Kudos [?]: 21 [5] , given: 5 Re: Calling All 2014 Consortium Applicants [#permalink] Show Tags 22 Jan 2014, 19:21 5 This post received KUDOS Just got admitted to Stern this evening! Intern Joined: 03 Sep 2012 Posts: 5 Followers: 0 Kudos [?]: 2 [0], given: 2 Re: Calling All 2014 Consortium Applicants [#permalink] Show Tags 22 Jan 2014, 21:37 tdesena wrote: meeeshelleee wrote: are you guys planning on attending the event for sure? where are you guys located? I can't decide whether to interview with alumni in town or attend the event.... I am planning on attending their Consortium/Conference weekend. I'm from Boston, but as Ross is my first choice I felt like it was too good of an opportunity to pass up going to Ann Arbor! Tdesena, I'll be there too. I'm driving in from Chicago but will be staying at a Red Roof Inn which I managed to get through Priceline for only$60. Looking forward to seeing you guys.
Senior Manager
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Re: Calling All 2014 Consortium Applicants [#permalink]
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23 Jan 2014, 08:31
hopefulmba23 wrote:
Just got admitted to Stern this evening!
congrats!
_________________
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Re: Calling All 2014 Consortium Applicants [#permalink]
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23 Jan 2014, 08:33
I still haven't recieved the email stating that my application has been released. Anyone else have the same problem?
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Re: Calling All 2014 Consortium Applicants [#permalink]
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23 Jan 2014, 13:58
Congrats hopeful!
Marc, I'd suggest emailing or calling the Consortium to sort out your application status.
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Re: Calling All 2014 Consortium Applicants [#permalink]
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23 Jan 2014, 22:02
Marcg153 wrote:
I still haven't recieved the email stating that my application has been released. Anyone else have the same problem?
When (day) did you submit the application (they process by order of receipt)? Are all portions of it complete, including the Consortium mission/recommender portion? I would agree that you should call or email them for a status.
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Re: Calling All 2014 Consortium Applicants [#permalink]
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24 Jan 2014, 08:00
JavertHL wrote:
Marcg153 wrote:
I still haven't recieved the email stating that my application has been released. Anyone else have the same problem?
When (day) did you submit the application (they process by order of receipt)? Are all portions of it complete, including the Consortium mission/recommender portion? I would agree that you should call or email them for a status.
I just recieved the release email this morning. Such a relief. Now I can worry about getting interviews lol.
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Re: Calling All 2014 Consortium Applicants [#permalink]
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24 Jan 2014, 08:03
1
KUDOS
You can add NYU alongside Ross and Yale for schools that are offering the Fellowship with your admission - I just got the call that I received it (two days after getting admission letter)!!
Re: Calling All 2014 Consortium Applicants [#permalink] 24 Jan 2014, 08:03
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http://math.stackexchange.com/questions/227042/closed-subset-of-complete-metric-space-dont-understand-last-part-of-theorem?answertab=oldest
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# Closed subset of complete metric space…don't understand last part of theorem.
A closed subset of a complete metric space is a complete subspace. Proof. Let $S$ be a closed subspace of a complete metric space X. Let $(x_n)$ be a Cauchy sequence in $S$. Then $(x_n)$ is a Cauchy sequence in $X$ and hence it must converge to a point $x$ in $X$. But then $x \in \bar{S} = S$. Thus $S$ is complete.
I have seen this theorem in several places but I never know why they are able to say "But then $x \in \bar{S} = S$"...Why is $x$ in $\bar{S}$?
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Because S is a closed subset, hence $S = \bar{S}$ – amWhy Nov 1 '12 at 20:48
Do you know what $\bar S$ means? – Chris Eagle Nov 1 '12 at 20:48
Yes, its the closure of $S$, ie. the smallest closed subset containing $S$ or alternatively the set $S \cup$ the limit points of $S$. I don't see how they can say $x$ is in the closure of $S$ though. – sonicboom Nov 1 '12 at 20:53
Let $U$ be any open nbhd of $x$. There is an $r>0$ such that $B(x,r)\subseteq U$, where $B(x,r)$ is the open ball of radius $r$ centred at $x$. Since $\langle x_n:n\in\Bbb N\rangle\to x$, there is an $m\in\Bbb N$ such that $d(x_n,x)<r$ whenever $n\ge m$. In particular, $d(x_m,x)<r$, so $x_m\in B(x,r)\subseteq U$. Moreover, $x_m\in S$, so $x_m\in U\cap S$. This shows that $U\cap S\ne\varnothing$ for every open nbhd $U$ of $x$, and it follows at once that $x\in\operatorname{cl}S$.
Added: Here in one place are some definitions that seem to be giving you a bit of trouble. Let $\langle X,d\rangle$ be a metric space, $S\subseteq X$ and $x\in X$.
• $x\in\operatorname{cl}S$: for each $r>0$, $B(x,r)\cap S\ne\varnothing$. In words, every open ball at $x$ contains at least one point of $S$.
• $x$ is a limit point (or cluster point) of $S$: for each $r>0$, $B(x,r)\cap(S\setminus\{x\})\ne\varnothing$. In words, every open ball at $x$ contains at least one point of $S$ other than $x$.
• $x\in\operatorname{int}S$: there is an $r>0$ such that $B(x,r)\subseteq S$.
-
Cheers, I am going to have to write that out and draw some diagrams to make sure I understand whats going on. – sonicboom Nov 1 '12 at 21:00
When they say "Let $(x_n)$ be a Cauchy sequence in $S$" are they saying that all values of $x_n$ will be in $S$ and the only question is then where the limit of the sequence lies? – sonicboom Nov 1 '12 at 21:07
I get it now...no matter how small we make $r$ there will be an open ball with center $x$, radius $r$ that contains a point of $S$ other than $x$ itself, hence $x$ is a limit point. – sonicboom Nov 1 '12 at 21:14
@sonicboom: Actually, it’s possible that $x\in S$ and that the sequence is eventually constant at $x$, so $x$ might not be a limit point. But either it’s a limit point or it’s in $S$, and either way it’s in $\operatorname{cl}S$. – Brian M. Scott Nov 1 '12 at 23:23
@sonicboom: No, points of $S$ are not necessarily limit points of $S$: $x$ is a limit point of $S$ if every open neighborhood of $x$ contains a point of $S\setminus\{x\}$. Thus, $3$ is not a limit point of $S=[0,1]\cup\{3\}$: $(2,4)$ is an open nbhd of $3$ that contains no point of $S\setminus\{3\}$. If $x$ has an open nbhd that lies entirely within $S$, then $x$ is in the interior of $S$. – Brian M. Scott Nov 2 '12 at 11:11
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http://blog.jpolak.org/?p=977
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# Highlights in Linear Algebraic Groups 13: Centralisers of Tori
In Highlights 12, we used some of the equivalent conditions for a connected algebraic group $G$ over a field $k=\overline{k}$ to have semisimple rank 1 in the study of reductive groups (these are the groups whose unipotent radical $R(G)_u$ is trivial).
Precisely, we showed that such a $G$ must have a semisimple commutator $[G,G]$ subgroup whose dimension is three, and that we can write
$G = Z(G)^\circ\cdot [G,G]$
where the $-\cdot-$ denotes that this is an almost direct product: in other words, the multiplication map $Z(G)^\circ\times[G,G]\to G$ is surjective with finite kernel.
Let $T\subseteq G$ be a maximal torus. We will show in this post that $C_G(T) = T$ for a connected reductive group $G$ of semisimple rank 1.
This post shall conclude the detailed explanation of the concise proof of Corollary 25.3 in Humphrey’s book, which I encourage the reader to peruse for more information.
### Centralisers of Tori in $\mathrm{PGL}_2(k)$
The first step to show that $C_G(T) = T$ is to show that this is true for $G = \mathrm{PGL}_2(k)$. We have shown that $\mathrm{PGL}_2(k)$ is the image of a connected group in the previous post so it is connected. We have the quotient morphism $\mathrm{SL}_2(k)\to \mathrm{PGL}_2(k)$ of connected groups, and so each maximal torus of $\mathrm{PGL}_2(k)$ is the image of some maximal torus in $\mathrm{SL}_2(k)$. A couple lines of calculations will convince the reader that to show $C_G(T) = T$ for $G = \mathrm{PGL}_2(k)$, it is sufficient to show that $C_G(T) = T$ for $G = \mathrm{SL}_2(k)$ , which is also a short calculation.
### Centralisers of Tori in Reductive Groups of SS Rank 1
We can now proceed with the general $G$.
Theorem.
Let $G$ be a connected reductive group of semisimple rank $1$ (i.e. the group $G/R(G)$ has rank 1). If $T\subseteq G$ is a maximal torus then $C_G(T) = T$.
Proof. Fix a morphism $\varphi:G\to\mathrm{PGL}_2(k)$ with $\ker\varphi = R(G) = Z(G)^\circ$. From the previous section, we see that the torus $T$ and its centraliser $C_G(T)$ have the same image under $\varphi$.
Hence we have the inclusions $T\subseteq C_G(T) \subseteq T\ker\varphi = TR(G)$, since for any element $x\in C_G(T)$ there is a $t\in T$ such that $\varphi(y) = \varphi(t)$. However, $R(G)$ is a normal torus and hence contained in $T$ so $TR(G) = T$. QED
Notice that since $Z(G)$ centralises any torus, $Z(G)$ is contained in every torus.
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http://tex.stackexchange.com/questions/56093/pdfpages-addtolist-and-list-of-tables
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# pdfpages, addtolist and list of tables
These may be separate questions, but the following MWE:
\usepackage{pdfpages}
...
\includepdf[pages={-}, pagecommand={\label{tab:UserRoles}}, offset=0in -1in, addtolist={9, table, {The User Roles table}, tab:UserRoles}]{UserRolesTable}
...
has several unexpected behaviors.
1. I get the following warning:
Package pdfpages Warning: There's something wrong with the entries of addtolist'.
Not all entries were processed. Check addtolist' [in the MWE]."
2. Probably due to the \label not being bound to the inserted pdf (in a table environment), my inserted PDF is numbered using the section, and not the expected "Table X" value.
3. The manually-inserted LoT line (which also uses the section number rather than the incremented table number) is not formatted like the other lines in the LoT - the number lines up, but the table caption itself is not aligned with the others in the list.
The source PDF has no errors and displays correctly in the output PDF.
PDFLaTeX -> BibTex
MWE:
\documentclass[11pt,letterpaper,twoside,final]{article}
\usepackage{pdfpages}
\begin{document}
\listoftables
\begin{center}
\textbf{Table \ref{tab:UserRoles} - The User Roles Table} \addcontentsline{lot}{subsection}{\ref{tab:UserRoles}
\textbf{User Roles}} % manual entry in ToC
\includepdf[pages={-}, pagecommand={\label{tab:UserRoles}}, offset=0in -1in, addtolist={9, table, {The User Roles table}, tab:UserRoles, lot}]{UserRolesTable}
\end{center}
\end{document}
-
How many pages does the included PDF have? – egreg May 16 '12 at 16:01
5 pages in the included PDF. I tried specifying ('\includepdf{pages=1-5...' but that threw the same errors. – Yonah May 16 '12 at 16:45
Can you upload the pdf file? – Marco Daniel Jun 2 '12 at 22:07
Can't figure out how to attach to this page. The PDF is not hosted online (nor will it be), and I've had to strip out all identifying info. By way of update, the new PDF is only 2 pages, but that isn't an issue in the MWE - the "unspecified error" (#1 above) still shows. – Yonah Jun 4 '12 at 15:32
There are some errors in the MWE:
• pagecommand={\label{tab:UserRoles}}: This is executed on each builded page. In case of more than one page the result are warnings because of multiply defined labels. Also the label setting is already done by your option setting for addtolist. (Edit: Fix of PolGab applied, thanks)
• The argument list for addtolist expects four parameters, the page number, the type, the title and the label. However there is a fifth element lot in the MWE. The package pdfpages sets the list entry by calling \caption, where \@makecaption is a dummy. Thus the caption is not actually typeset, but the counter is incremented and the entry for the list is done.
• With a working addtolist the manual \addcontentsline is not longer needed. Also it should be called at the right page to get the correct page number.
The corrected MWE:
\documentclass[11pt,letterpaper,twoside,final]{article}
\usepackage{pdfpages}
\begin{document}
\listoftables
\section*{Table \ref{tab:UserRoles} - The User Roles Table}
\includepdf[
pages={-},
offset=0in -1in,
addtolist={3, table, {The User Roles table}, tab:UserRoles},
]{test}
\end{document}
The result:
The first page contains the list of tables and the "table section title". The third page of the included pages gets the entry in the list of tables, that is the fourth page.
-
Thanks so much for your help! – Yonah Jul 30 '12 at 18:54
Thanks so much for your help! The reason I used \pagecommand is that it adds my custom header/footer around the inserted PDF (which also explains the offsets). Your MWE does not insert a line to the LoT (I also tried changing it to \subsection* to fit with my hierarchy, but no dice). I get a section titled "Table ?? - The User Roles Table" with nothing else on the page, then the PDF starts on the following page. Thanks, all, for your help so far. – Yonah Jul 30 '12 at 20:30
The entry in the LoT is present, see the result image. The entry is done by option addtolist alone and has nothing to do with the previous \section*. Ignore this line if you like; it's only there to show \ref. – Heiko Oberdiek Jul 30 '12 at 21:34
So now I have to wonder what else is causing TeX to ignore the label. I'm still not seeing (MWE below) an entry in the ToC and the table comes out a page too late (and dialing it back to p12 doesn't help). \includepdf[ pages={ - }, pagecommand={}, offset=0in -1in, addtolist={13, table, {The User Roles table}, tab:UserRoles}, ]{UserRolesTable} Is it possible that pdfpages conflicts with another package I use? – Yonah Jul 31 '12 at 13:34
First make sure that you are indeed including 13 or more pages, your addtolist specification fires on the 13th page. If it does not work, a complete MWE would make sense (it could be appended to the question). – Heiko Oberdiek Jul 31 '12 at 14:13
The addtolist option uses 4 (or any multiple of 4) arguments.
For example, if your external PDF file (UserRolesTable.pdf) contains three pages, you can say:
\documentclass[11pt,letterpaper,twoside,final]{article}
\usepackage{pdfpages}
\pagestyle{empty}
\begin{document}
\listoftables
\includepdf[%
pages={-},
offset=0in -1in,%
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