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https://www.givewell.org/united-states/charities/Vocational-Foundation
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# Vocational Foundation (VFI)
GiveWell aims to find the best giving opportunities we can and recommend them to donors. We tend to put a lot of investigation into the organizations we find most promising, and de-prioritize others based on limited information. When we decide not to prioritize an organization, we try to create a brief writeup of our thoughts on that charity because we want to be as transparent as possible about our reasoning.
The following write-up should be viewed in this context: it explains why we determined that (for the time being), we won't be prioritizing the organization in question as potential top charity. This write-up should not be taken as a "negative rating" of the charities. Rather, it is our attempt to be as clear as possible about the process by which we came to our top recommendations.
### A note on this page's publication date
The last time we examined the charities working primarily in the U.S. was in 2010. As of 2011, we have de-prioritized further work on this cause.
The content we created in 2007 appears below. This content is likely to be no longer fully accurate, both with respect to what it says about the organization and with respect to what it implies about our own views and positions.
Published: 2007
Vocational Foundation applied for a grant GiveWell offered in 2007, but did not receive the grant. The information below explains why.
# In a nutshell
What they do: VFI works with disconnected youth and puts them through a 15-week program including GED prep, skills training, "soft skills" training, and followup. It aims to place them in jobs paying around $10/hr on average. Does it work? We believe that VFI's clients benefit substantially, relative to what they could likely do on their own. What do you get for your money? We roughly estimate that it costs VFI about$17,000 to sustainably place a disconnected youth in a relatively low-paying job (averaging around $10/hr). Where they rank: VFI and HOPE are the two strongest organizations we've seen in the category of helping extremely disadvantaged people obtain relatively low-wage (around$10/hr) jobs. We are more impressed by HOPE, but recommend VFI over other organizations with this goal.
# The Details
## Whom do they serve?
VFI serves “disconnected youth”: 17-21 year olds who are neither employed nor in school. VFI's entrance requirements are less strict (in terms of the level of education required) than those of Year Up or the skills training programs for Highbridge and St. Nick's, although we believe that VFI's population served faces fewer barriers than those of organizations like CCCS, Covenant House, and HOPE.
Selection. VFI gets its clients through referrals from the New York City Housing Authority, DOE, and other organizations (Attachment A-2 Pg 2). The program requires at least a 6th-grade level proficiency in reading (Attachment A-2 Pg 2), and the numbers on Attachment A-2 Pg 2 imply that applicants must be between 17-21, and classified as "low-income" (we aren't sure exactly what this means). VFI conducts a several-stage screening process, and about 2/3 of those who originally express interest end up self-selecting out, although VFI accepts all or nearly all of those that meet its fairly basic requirements (the source for this information is a response to our initial draft of the review, which we do not have clearance to make public).
Attachment B-4 Pg 10 makes it sound as though VFI's screening process is unusually involved, and thus ends up causing more people to self-select out, than is typical. We don't know whether this is the case, though (it could easily be true that HOPE and Covenant House conduct similar screening and experience similar self-selection).
Characteristics. VFI states that its clients have the following characteristics (Attachment A-2 Pg 2):
• Ethnicity: predominantly African-American and Latin-American.
• Income: Low. 25% are on government assistance, which implies being below the federal poverty line (we see a "self-supporting" income as being roughly twice the federal poverty line).
• GED/HS degree: 23%
• In public housing: 75%
• Past conviction: 15%
## What do they do?
VFI offers a fifteen-week, 7.5 hours/day program, including:
• Vocation-specific training (medical administrative assistant, office support specialist, computer technology, security guard and bank teller – see Attachment A-2 Pg 1).
• General job training (writing a resume, what to wear to work, etc. – see Attachment A-2 Pg 3).
• Pre-GED literacy and GED training (Attachment A-2 Pg 3).
• Job placement services.
• A relationship with a counselor who continues working with graduates for two years after program completion (Attachment A-2 Pg 3).
## What are the results?
Below data is from Attachment A-4 Pgs 1-4.
Spring 04 Fall 04 Spring 05 Fall 05 Spring 06 Fall 06 Spring 07
Enrollees 94 108 110 108 150 150 150
Graduates (%enrollees) 62 (66%) 77 (71%) 70 (64%) 79 (73%) 114 (76%) 123 (82%) 125 (83%)
Placements (%graduates) 56 (90%) 66 (86%) 59 (84%) 72 (91%) 98 (86%) 105 (85%) 105 (84%)
3m retained (%placements) 53 (95%) 64 (97%) 57 (97%) 69 (96%) 96 (98%) 103 (98%) N/A
6m retained (%placements) 45 (80%) 59 (89%) 54 (92%) 69 (96%) 94 (96%) 92 (88%) N/A
12m retained (%placements) 42 (75%) 58 (88%) 53 (90%) 67 (93%) 86 (88%) N/A N/A
24m retained (%placements) 35 (63%) 50 (76%) 38 (64%) N/A N/A N/A N/A
Avg wage $8.08$7.98 $8.16$8.40 $9.13$9.22 $9.82 Career advancement wage ?$9.96 $9.39$10.75 $10.71 ? ? Took GED 39 37 17 46 35 57 36 Passed GED (%took GED) 18 (46%) 25 (68%) 12 (71%) 17 (37%) 23 (66%) 37 (65%) 23 (64%) ### Placements VFI places about 60% of its enrollees in sustainable employment (lasting at least 12 months). Graduate to enrollee ratios have improved dramatically as time has gone on; going forward, we'd expect 80% of enrollees to graduate (as they have recently). Placement-to-graduate rates have held pretty constant in the 85% range. 12m retention, as a percentage of placements, has generally been around 90%. 80% * 85% * 90% =~ 60% of all enrollees placed sustainably (12m+). We have very little data on 24-month retention, but what we have shows further attrition (note that VFI defines retention as having no periods of unemployment lasting 3 months or more - see Attachment A-4 Pg 4). We ignore this for purposes of discussing "sustainable job placements," because (a) it is a small sample; (b) we don't have 24-month retention data for our other applicants, and are using as consistent as possible a definition of "sustainable job placements." 25% or fewer of those who are sustainably placed also obtain their GED through VFI, which presumably improves their future earning potential (see immediately below). ("Or fewer" is meant to account for the fact that the GED figures may include those who were not placed in jobs.) ### Incomes and career paths Clients initially earn an average of around$10/hr; career paths vary by occupation but appear generally limited.
Attachment A-4 Pg 8-10 indicates that VFI trains people as bank tellers, security guards, and administrative assistants (general and medical). According to the US Department of Labor data that VFI included with its application, bank teller appears to be the role with the best career path, starting at $9-12/hr and getting up to$30,000-50,000 (pg 8); no salary data is given on administrative assistants, and security guards are stated to be in the $8.50-$13/hr range (pg 9).
## Conclusion
VFI is a standout in terms of providing clear, thorough documentation and evaluation of itself; we find it second only to HOPE in this respect. It also places a large proportion (~60%) of people in jobs, sustainably, despite serving a highly undereducated population.
We lack strong comparison group data for any of our organizations, which would help us more clearly identify how much they help clients beyond what the clients could likely accomplish themselves. We rank VFI behind HOPE, because we find HOPE's results more impressive for the population it is working with (this is partly because we have more semblance of comparison group data for HOPE, and partly simply because of our intuitions about the difficulty of serving HOPE's population).
## We'd like to know more about:
• Comparison group data. We still lack the information necessary to look at a moderately relevant "comparison group" for VFI, in order to gauge the extent of its impact beyond what clients would likely accomplish without its help. Above we describe a couple of attempts to get a very rough sense of this.
## Attachments
### C. Organization related attachments
See Attachment A-4 for general organization information.
### D. Financials
The audit we were sent is available in hard copy only. Form 990s are available from GuideStar.
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http://mathhelpforum.com/calculus/26849-integrating-factor.html
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# Math Help - integrating factor
1. ## integrating factor
dy/dx + 2y = sin x
In this equation what is the integrating factor?
Is it e^2x?
2. Originally Posted by geton
dy/dx + 2y = sin x
In this equation what is the integrating factor?
Is it e^2x?
Finally I’ve done & this equation is really awesome. Problem resolved
3. Originally Posted by geton
Finally I’ve done & this equation is really awesome. Problem resolved
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http://www.real-statistics.com/mathematical-notation/functions-polynomials-limits-graphs/
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# Functions, polynomials, limits and graphs
A function is a mapping between two sets, called the domain and the range, where for every value in the domain there is a unique value in the range assigned by the function. Generally functions are defined by some formula; for example f(x) = x2 is the function that maps values of x into their square. The mapping is between all numbers (the domain) and non-negative numbers (the range).
A function is polynomial if it has the form
for some non-negative integer n (called the degree of the polynomial) and some constants a0, a1, …, an where an ≠ 0 (unless n = 0). The function is linear if n = 1 and quadratic if n = 2.
We often use limit notation such as
as a shorthand for as x gets larger the value of the function f(xapproaches the value a. Some examples for various values of f(x) are as follows:
We can also evaluate the limit of a function when x approaches some other value. For example in the following example as x gets close to 0 the value of the function approaches 1.
We can also use the limit notation with series. If xn = 1 – 1/n where n is a positive integer then
since the series $\frac{1}{2}$, $\frac{2}{3}$, $\frac{3}{4}$, $\frac{4}{5}$, … converges to 1.
Often we use a graph to show the relationship between x and f(x). A graph consists of all the points (x,y) in what is called the xy plane where x is in the domain of f and y = f(x). The graph is drawn in a rectangular grid defined by the x-axis (drawn horizontally) and the y-axis (drawn vertically) meeting at a point (0, 0) call the origin. In particular, the graph of y = f(x) for f(x) = x2 is given in Figure 1.
Figure 1 – Graph of y = f(x) where f(x) = x2
A line is a set of points (x, y) such that y = bx + a for some constants a and b. b is called the slope of the line and a is called the y-intercept.
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https://www.jpe.ac.cn/EN/10.1093/jpe/rtv033
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J Plant Ecol ›› 2016, Vol. 9 ›› Issue (1): 30-39.
• Research Articles •
### The effects of temporal variation in soil carbon inputs on resource allocation in an annual plant
Hagai Shemesh1,?, Uri Ben-Yosef2,?, Stav Livne2 and Ofer Ovadia2,*
1. 1 Department of Environmental Sciences, Tel-Hai Academic College, Upper Galilee 12208, Israel; 2 Department of Life Sciences, Ben-Gurion University of the Negev, POB 653 Beer Sheva 8410501, Israel
• Received:2014-07-12 Accepted:2015-03-21 Published:2016-01-27
• Contact: Ovadia, Ofer
Abstract: Aims Resource allocation in plants can be strongly affected by competition. Besides plant–plant interactions, terrestrial plants compete with the soil bacterial community over nutrients. Since the bacterial communities cannot synthesize their own energy sources, they are dependent on external carbon sources. Unlike the effect of overall amounts of carbon (added to the soil) on plant performance, the effect of fine scale temporal variation in soil carbon inputs on the bacterial biomass and its cascading effects on plant growth are largely unknown. We hypothesize that continuous carbon supply (small temporal variance) will result in a relatively constant bacterial biomass that will effectively compete with plants for nutrients. On the other hand, carbon pulses (large temporal variance) are expected to cause oscillations in bacterial biomass, enabling plants temporal escape from competition and possibly enabling increased growth. We thus predicted that continuous carbon supply would increase root allocation at the expense of decreased reproductive output. We also expected this effect to be noticeable only when sufficient nutrients were present in the soil.
Methods Wheat plants were grown for 64 days in pots containing either sterilized or inoculated soils, with or without slow-release fertilizer, subjected to one of the following six carbon treatments: daily (1.5mg glucose), every other day (3mg glucose), 4 days (6mg glucose), 8 days (12mg glucose), 16 days (24mg glucose) and no carbon control.
Important findings Remarkably, carbon pulses (every 2–16 days) led to increased reproductive allocation at the expense of decreased root allocation in plants growing in inoculated soils. Consistent with our prediction, these effects were noticeable only when sufficient nutrients were present in the soil. Furthermore, soil inoculation in plants subjected to low nutrient availability resulted in decreased total plant biomass. We interpret this to mean that when the amount of available nutrients is low, these nutrients are mainly used by the bacterial community. Our results show that temporal variation in soil carbon inputs may play an important role in aboveground–belowground interactions, affecting plant resource allocation.
Aims Resource allocation in plants can be strongly affected by competition. Besides plant–plant interactions, terrestrial plants compete with the soil bacterial community over nutrients. Since the bacterial communities cannot synthesize their own energy sources, they are dependent on external carbon sources. Unlike the effect of overall amounts of carbon (added to the soil) on plant performance, the effect of fine scale temporal variation in soil carbon inputs on the bacterial biomass and its cascading effects on plant growth are largely unknown. We hypothesize that continuous carbon supply (small temporal variance) will result in a relatively constant bacterial biomass that will effectively compete with plants for nutrients. On the other hand, carbon pulses (large temporal variance) are expected to cause oscillations in bacterial biomass, enabling plants temporal escape from competition and possibly enabling increased growth. We thus predicted that continuous carbon supply would increase root allocation at the expense of decreased reproductive output. We also expected this effect to be noticeable only when sufficient nutrients were present in the soil.
Methods Wheat plants were grown for 64 days in pots containing either sterilized or inoculated soils, with or without slow-release fertilizer, subjected to one of the following six carbon treatments: daily (1.5mg glucose), every other day (3mg glucose), 4 days (6mg glucose), 8 days (12mg glucose), 16 days (24mg glucose) and no carbon control.
Important findings Remarkably, carbon pulses (every 2–16 days) led to increased reproductive allocation at the expense of decreased root allocation in plants growing in inoculated soils. Consistent with our prediction, these effects were noticeable only when sufficient nutrients were present in the soil. Furthermore, soil inoculation in plants subjected to low nutrient availability resulted in decreased total plant biomass. We interpret this to mean that when the amount of available nutrients is low, these nutrients are mainly used by the bacterial community. Our results show that temporal variation in soil carbon inputs may play an important role in aboveground–belowground interactions, affecting plant resource allocation.
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https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=129&t=27704
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-w vs +w
$w=-P\Delta V$
and
$w=-\int_{V_{1}}^{V_{2}}PdV=-nRTln\frac{V_{2}}{V_{1}}$
Kassandra Molina 2B
Posts: 43
Joined: Wed Nov 16, 2016 3:03 am
-w vs +w
Just to clarify: if work is positive that means expansion and if it is negative it means compression?
Kaylin Krahn 1I
Posts: 57
Joined: Fri Sep 29, 2017 7:04 am
Been upvoted: 1 time
Re: -w vs +w
If work is done by the system, -w, it means expansion. If work is done onto the system, +w, it means compression.
Tim Nguyen 2J
Posts: 31
Joined: Sat Jul 22, 2017 3:00 am
Re: -w vs +w
If work is negative, the system is losing energy as it uses it to expand.
If work is positive, the system is gaining energy as it gains it from the compressing force.
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https://brilliant.org/problems/interesting-summation-2/
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# Interesting Summation
Algebra Level 5
When $$M$$ is a digit, $M + \overline{MM} + \overline{MMM} + \cdots + \underbrace{\overline{MMM\cdots M}}_{n \ M\text{'s}} = \frac{M}{a}\left [ 10^{n+1}-10-9n \right ].$ Find the value of $$a.$$
Note that $$\overline{MM}$$ represents a two-digit number with both digits being $$M.$$
×
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http://eprints.ma.man.ac.uk/1148/
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You are here: MIMS > EPrints
MIMS EPrints
## 2008.83: Pure-injective modules
2008.83: Mike Prest (2008) Pure-injective modules.
Full text available as:
PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader232 Kb
## Abstract
The pure-injective $R$-modules are defined easily enough: as those modules which are injective over all pure embeddings, where an embedding $A\rightarrow B$ is said to be pure if every finite system of $R$-linear equations with constants from $A$ and a solution in $B$ has a solution in $A.$ But the definition itself gives no indication of the rich theory around purity and pure-injectivity. The purpose of this survey is to present and illustrate the definitions and a number of the results around pure-injective modules.
Item Type: MIMS Preprint A short survey pure-injective, algebraically compact, module MSC 2000 > 03 Mathematical logic and foundationsMSC 2000 > 16 Associative rings and algebras 2008.83 Professor Mike Prest 27 September 2008
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http://mathhelpforum.com/calculus/187924-calculate-following-integral-print.html
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# Calculate The Following Integral
• Sep 13th 2011, 06:05 PM
antz215
Calculate The Following Integral
Hello! The problem is:
Calculate The Following Integral:
(e^x + e^-x) from ln2 to ln3.
I'm pretty sure the next step is to change it to (e^x - e^-x) as those are the anti-derivatives right? Or maybe I'm starting horrible hence why I can't solve it.
Thanks in advance for any help! I've been stuck only on this one problem for hours!
• Sep 13th 2011, 06:14 PM
Plato
re: Calculate The Following Integral
Quote:
Originally Posted by antz215
Hello! The problem is:
Calculate The Following Integral:
(e^x + e^-x) from ln2 to ln3.
I'm pretty sure the next step is to change it to (e^x - e^-x) as those are the anti-derivatives right?
You can always find help here.
Know that $e^{\ln(3)}=3~\&~e^{-\ln(3)}=\frac{1}{3}~.$
• Sep 13th 2011, 06:23 PM
HallsofIvy
re: Calculate The Following Integral
Quote:
Originally Posted by antz215
Hello! The problem is:
Calculate The Following Integral:
(e^x + e^-x) from ln2 to ln3.
I'm pretty sure the next step is to change it to (e^x - e^-x) as those are the anti-derivatives right? Or maybe I'm starting horrible hence why I can't solve it.
Thanks in advance for any help! I've been stuck only on this one problem for hours!
It's easy to check isn't it: the derivative of $e^x- e^{-x}$ is $e^x-(-1)e^{-1}= e^x+ e^{-x}$ so yes, an anti-derivative of $e^x+ e^{-x}$ is $e^x- e^{-x}$.
Fundamental theorem of Calculus: if F(x) is an anti-derivative of f(x) then $\int_a^b f(x)dx= F(b)- F(a)$.
• Sep 13th 2011, 06:58 PM
antz215
re: Calculate The Following Integral
From both helps I am getting:
e^x + e^-x dx
(e^x - e^-x)
(e^ln3 - e^-ln3) - (e^ln2 - e^-ln2)
3 - 1/3 - 2 + 1/2
= 7/6
I think that is correct? Thanks for your guys' help!
• Sep 14th 2011, 01:30 PM
HallsofIvy
Re: Calculate The Following Integral
Yes, that is correct. Congratulations!
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https://www.earthdoc.org/content/papers/10.3997/2214-4609-pdb.19.p02
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1887
### Abstract
P-2 THE ROLE OF PETROPHYSICAL PROPERTIES IN SEISMIC INTERPRETATION IN MIOCENE GAS-BEARING FORMATIONS OF THE POLISH CARPATHIAN FOREDEEP JADWIGA A. JARZYNA and KAJA PIETSCH Mining and Metallurgy University Department of Geophysics al. Mickiewicza 30 30-059 Kraków Poland Abstract 1 Usually seismic interpretation delivers structural and stratigraphic traps successfully identified and located. Problems with interpretation of seismic sections in sandy-shaly Miocene formations occur in eastern part of the Polish Carpathian Foredeep. There the structural picture yielded by the seismic section does not often agree with the geological arrangement of layers. Hence only correctly done geological interpretation of the seismic wave field
/content/papers/10.3997/2214-4609-pdb.19.p02
2000-08-06
2020-04-08
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http://seankross.com/rbootcamp/
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## Welcome to the Winter R Bootcamp!
### Schedule
The Winter R Bootcamp will be taking place at the Johns Hopkins University on January 6th, 8th, 11th, 13th, 20th, and 22nd from 1pm to 3:30pm.
### Contact
If you have any questions please send me an email: [email protected]
There will be no graded assignments or in-class assessments. To get the most out of this course you should complete the swirl courses that will be assigned at the end of each lecture. Students will receive no credit for this course.
### Syllabus
#### Lecture 1
• Installing R
• The R Console & How to Read these Notes
• Types & Logic
• Data Structures
• Flow Control
• Loops
• Functions
• Extras
#### Lecture 2
• Workspace & Files
• Extras
#### Lecture 3
• Plotting & Base Graphics
• R Markdown
• Extras
#### Lecture 4
• Statistical Functions
• Simulation
• Basic Linear Modeling
• apply
• Extras
#### Lecture 5
• Strings, regex & stringr
• dplyr & magrittr
• Extras
• Shiny
• Extras
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https://science.sciencemag.org/content/325/5940/597
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Report
# Probing Spin-Charge Separation in a Tomonaga-Luttinger Liquid
See allHide authors and affiliations
Science 31 Jul 2009:
Vol. 325, Issue 5940, pp. 597-601
DOI: 10.1126/science.1171769
## Electron Breakdown
An electron possesses charge and spin. In general, these properties are confined to the electron. However, in strongly interacting many-body electronic systems, such as one-dimensional wires, it has long been theorized that the charge and spin should separate. There have been tantalizing glimpses of this separation experimentally, but questions remain. Jompol et al. (p. 597) looked at the tunneling current between an array of one-dimensional wires and a two-dimensional electron gas and argue that the results reveal a clear signature of spin-charge separation.
## Abstract
In a one-dimensional (1D) system of interacting electrons, excitations of spin and charge travel at different speeds, according to the theory of a Tomonaga-Luttinger liquid (TLL) at low energies. However, the clear observation of this spin-charge separation is an ongoing challenge experimentally. We have fabricated an electrostatically gated 1D system in which we observe spin-charge separation and also the predicted power-law suppression of tunneling into the 1D system. The spin-charge separation persists even beyond the low-energy regime where the TLL approximation should hold. TLL effects should therefore also be important in similar, but shorter, electrostatically gated wires, where interaction effects are being studied extensively worldwide.
View Full Text
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https://www.nag.com/numeric/nl/nagdoc_27cpp/flhtml/f08/f08cgf.html
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# NAG FL Interfacef08cgf (dormql)
## 1Purpose
f08cgf multiplies a general real $m$ by $n$ matrix $C$ by the real orthogonal matrix $Q$ from a $QL$ factorization computed by f08cef.
## 2Specification
Fortran Interface
Subroutine f08cgf ( side, m, n, k, a, lda, tau, c, ldc, work, info)
Integer, Intent (In) :: m, n, k, lda, ldc, lwork Integer, Intent (Out) :: info Real (Kind=nag_wp), Intent (In) :: tau(*) Real (Kind=nag_wp), Intent (Inout) :: a(lda,*), c(ldc,*) Real (Kind=nag_wp), Intent (Out) :: work(max(1,lwork)) Character (1), Intent (In) :: side, trans
#include <nag.h>
void f08cgf_ (const char *side, const char *trans, const Integer *m, const Integer *n, const Integer *k, double a[], const Integer *lda, const double tau[], double c[], const Integer *ldc, double work[], const Integer *lwork, Integer *info, const Charlen length_side, const Charlen length_trans)
The routine may be called by the names f08cgf, nagf_lapackeig_dormql or its LAPACK name dormql.
## 3Description
f08cgf is intended to be used following a call to f08cef, which performs a $QL$ factorization of a real matrix $A$ and represents the orthogonal matrix $Q$ as a product of elementary reflectors.
This routine may be used to form one of the matrix products
$QC , QTC , CQ , CQT ,$
overwriting the result on $C$, which may be any real rectangular $m$ by $n$ matrix.
A common application of this routine is in solving linear least squares problems, as described in the F08 Chapter Introduction, and illustrated in Section 10 in f08cef.
## 4References
Anderson E, Bai Z, Bischof C, Blackford S, Demmel J, Dongarra J J, Du Croz J J, Greenbaum A, Hammarling S, McKenney A and Sorensen D (1999) LAPACK Users' Guide (3rd Edition) SIAM, Philadelphia https://www.netlib.org/lapack/lug
## 5Arguments
1: $\mathbf{side}$Character(1) Input
On entry: indicates how $Q$ or ${Q}^{\mathrm{T}}$ is to be applied to $C$.
${\mathbf{side}}=\text{'L'}$
$Q$ or ${Q}^{\mathrm{T}}$ is applied to $C$ from the left.
${\mathbf{side}}=\text{'R'}$
$Q$ or ${Q}^{\mathrm{T}}$ is applied to $C$ from the right.
Constraint: ${\mathbf{side}}=\text{'L'}$ or $\text{'R'}$.
2: $\mathbf{trans}$Character(1) Input
On entry: indicates whether $Q$ or ${Q}^{\mathrm{T}}$ is to be applied to $C$.
${\mathbf{trans}}=\text{'N'}$
$Q$ is applied to $C$.
${\mathbf{trans}}=\text{'T'}$
${Q}^{\mathrm{T}}$ is applied to $C$.
Constraint: ${\mathbf{trans}}=\text{'N'}$ or $\text{'T'}$.
3: $\mathbf{m}$Integer Input
On entry: $m$, the number of rows of the matrix $C$.
Constraint: ${\mathbf{m}}\ge 0$.
4: $\mathbf{n}$Integer Input
On entry: $n$, the number of columns of the matrix $C$.
Constraint: ${\mathbf{n}}\ge 0$.
5: $\mathbf{k}$Integer Input
On entry: $k$, the number of elementary reflectors whose product defines the matrix $Q$.
Constraints:
• if ${\mathbf{side}}=\text{'L'}$, ${\mathbf{m}}\ge {\mathbf{k}}\ge 0$;
• if ${\mathbf{side}}=\text{'R'}$, ${\mathbf{n}}\ge {\mathbf{k}}\ge 0$.
6: $\mathbf{a}\left({\mathbf{lda}},*\right)$Real (Kind=nag_wp) array Input
Note: the second dimension of the array a must be at least $\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{k}}\right)$.
On entry: details of the vectors which define the elementary reflectors, as returned by f08cef.
On exit: is modified by f08cgf but restored on exit.
7: $\mathbf{lda}$Integer Input
On entry: the first dimension of the array a as declared in the (sub)program from which f08cgf is called.
Constraints:
• if ${\mathbf{side}}=\text{'L'}$, ${\mathbf{lda}}\ge \mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{m}}\right)$;
• if ${\mathbf{side}}=\text{'R'}$, ${\mathbf{lda}}\ge \mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{n}}\right)$.
8: $\mathbf{tau}\left(*\right)$Real (Kind=nag_wp) array Input
Note: the dimension of the array tau must be at least $\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{k}}\right)$.
On entry: further details of the elementary reflectors, as returned by f08cef.
9: $\mathbf{c}\left({\mathbf{ldc}},*\right)$Real (Kind=nag_wp) array Input/Output
Note: the second dimension of the array c must be at least $\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{n}}\right)$.
On entry: the $m$ by $n$ matrix $C$.
On exit: c is overwritten by $QC$ or ${Q}^{\mathrm{T}}C$ or $CQ$ or $C{Q}^{\mathrm{T}}$ as specified by side and trans.
10: $\mathbf{ldc}$Integer Input
On entry: the first dimension of the array c as declared in the (sub)program from which f08cgf is called.
Constraint: ${\mathbf{ldc}}\ge \mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{m}}\right)$.
11: $\mathbf{work}\left(\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{lwork}}\right)\right)$Real (Kind=nag_wp) array Workspace
On exit: if ${\mathbf{info}}={\mathbf{0}}$, ${\mathbf{work}}\left(1\right)$ contains the minimum value of lwork required for optimal performance.
12: $\mathbf{lwork}$Integer Input
On entry: the dimension of the array work as declared in the (sub)program from which f08cgf is called.
If ${\mathbf{lwork}}=-1$, a workspace query is assumed; the routine only calculates the optimal size of the work array, returns this value as the first entry of the work array, and no error message related to lwork is issued.
Suggested value: for optimal performance, ${\mathbf{lwork}}\ge {\mathbf{n}}×\mathit{nb}$ if ${\mathbf{side}}=\text{'L'}$ and at least ${\mathbf{m}}×\mathit{nb}$ if ${\mathbf{side}}=\text{'R'}$, where $\mathit{nb}$ is the optimal block size.
Constraints:
• if ${\mathbf{side}}=\text{'L'}$, ${\mathbf{lwork}}\ge \mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{n}}\right)$ or ${\mathbf{lwork}}=-1$;
• if ${\mathbf{side}}=\text{'R'}$, ${\mathbf{lwork}}\ge \mathrm{max}\phantom{\rule{0.125em}{0ex}}\left(1,{\mathbf{m}}\right)$ or ${\mathbf{lwork}}=-1$.
13: $\mathbf{info}$Integer Output
On exit: ${\mathbf{info}}=0$ unless the routine detects an error (see Section 6).
## 6Error Indicators and Warnings
$-999<{\mathbf{info}}<0$
If ${\mathbf{info}}=-i$, argument $i$ had an illegal value. An explanatory message is output, and execution of the program is terminated.
${\mathbf{info}}=-999$
Dynamic memory allocation failed.
See Section 9 in the Introduction to the NAG Library FL Interface for further information.
An explanatory message is output, and execution of the program is terminated.
## 7Accuracy
The computed result differs from the exact result by a matrix $E$ such that
$E2 = Oε C2$
where $\epsilon$ is the machine precision.
## 8Parallelism and Performance
f08cgf makes calls to BLAS and/or LAPACK routines, which may be threaded within the vendor library used by this implementation. Consult the documentation for the vendor library for further information.
Please consult the X06 Chapter Introduction for information on how to control and interrogate the OpenMP environment used within this routine. Please also consult the Users' Note for your implementation for any additional implementation-specific information.
The total number of floating-point operations is approximately $2nk\left(2m-k\right)$ if ${\mathbf{side}}=\text{'L'}$ and $2mk\left(2n-k\right)$ if ${\mathbf{side}}=\text{'R'}$.
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http://math.stackexchange.com/questions/412817/easiest-example-of-rearrangement-of-infinite-leading-to-different-sums
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# Easiest example of rearrangement of infinite leading to different sums
I am reading the section on the rearrangement of infinite series in Ok, E. A. (2007). Real Analysis with Economic Applications. Princeton University Press.
As an example, the author shows that
is a rearrangement of the sequence
\begin{align} \frac{(-1)^{m+1}}{m} \end{align}
and that the infinite sum of these two sequences must be different.
My question is : what is to you the easiest and most intuitive example of such infinite series having different values for different arrangements of the terms? Ideally, I hope to find something as intuitive as the illustration that some infinite series do not have limits through $\sum_\infty (-1)^i$.
I found another example in http://www.math.ku.edu/~lerner/m500f09/Rearrangements.pdf but it is still too abstract to feed my intuition...
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It may be easier for future questioners to see this if you mentioned conditionally converging series. – Loki Clock Jun 6 '13 at 19:04
I am not familiar with the notion of conditionally converging series. Is it that I should replace any instance of "infinite series" by "conditionally converging series"? Anyways, fell free to edit my question if you have an improvement. – Martin Van der Linden Jun 7 '13 at 7:33
– Loki Clock Jun 7 '13 at 7:41
$$1/2-1/3+1/4-1/5+1/6-1/7+\cdots=(1/2-1/3)+(1/4-1/5)+(1/6-1/7)+\cdots$$ is obviously positive. The rearrangement $$1/2-1/3-1/5+1/4-1/7-1/9+1/6-1/11-1/13+\cdots$$ is clearly negative; just group it as $$(1/2-1/3-1/5)+(1/4-1/7-1/9)+(1/6-1/11-1/13)+\cdots$$ which is $$(1/2-8/15)+(1/4-16/63)+(1/6-24/143)+\cdots\lt(1/2-8/16)+(1/4-16/64)+(1/6-24/144)+\cdots=0$$
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Nice! The rearrangement function even has an explicit formulation, the second sequence being $\frac{1}{\sigma(i)}$, where $\sigma(i) = \begin{cases} i - (2 - \frac{i}{2}), & \text{ when } i \text{ is even}\\ i - \frac{i-1}{2}, & \text{ when } i \text{ is odd and} \frac{i +(i-2)}{4} \text{ is odd} \\ i - \frac{i-3}{2}, & \text{ when } i \text{ is odd and} \frac{i +(i-2)}{4} \text{ is even} \\ \end{cases}$ – Martin Van der Linden Jun 6 '13 at 11:29
The following variant of the alternating harmonic is computationally easy. Consider the series $$1-1+\frac{1}{2}-\frac{1}{2}+\frac{1}{2}-\frac{1}{2}+\frac{1}{4}-\frac{1}{4}+\frac{1}{4}-\frac{1}{4}+\frac{1}{4}-\frac{1}{4}+\frac{1}{4}-\frac{1}{4}+\frac{1}{8}-\frac{1}{8}+\cdots.$$ The sum is $0$. For the partial sums are either $0$ or $\frac{1}{2^k}$ for suitable $k$ that go to infinity.
Let us rearrange this series to give sum $1$. Use \begin{align} 1+&\frac{1}{2}+\frac{1}{2}-1+\frac{1}{4}+\frac{1}{4}-\frac{1}{2}+\frac{1}{4}+\frac{1}{4}-\frac{1}{2}+\frac{1}{8}+\frac{1}{8}-\frac{1}{4}+\frac{1}{8}+\frac{1}{8}-\frac{1}{4}+\frac{1}{8}+\frac{1}{8}-\frac{1}{4}\\&+\frac{1}{8}+\frac{1}{8}-\frac{1}{4}+\frac{1}{16}+\frac{1}{16}-\frac{1}{8}+\frac{1}{16}+\frac{1}{16}-\frac{1}{8}+\cdots.\end{align} That the series converges to $1$ follows from the fact that the sum of the first $3n+1$ terms is always $1$, and that the sum of the first $3n+2$ terms, and the sum of the first $3n+3$ terms, differ from the sum of the first $3n+1$ terms by an amount that $\to 0$ as $n\to\infty$.
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This argument is incomplete. The latter series has to converge to a different value, and hence has to be independent of groupings. – Loki Clock Jun 6 '13 at 17:27
There is no grouping, the "triplets" remark is just a description of how the sequence is built. The convergence to $1$ is obvious, since the sum of the first $3k+1$ elements is always $1$, and for large $k$ the $3k+2$-th sum and the $3k+3$-th sum differ from $1$ by an amount that $\to 0$. But I will change the sentence at the end since it may cause confusion. – André Nicolas Jun 6 '13 at 18:55
There is an argument in the Stewart calculus book 5th edition (the one I learned from) which uses the alternating harmonic series since it is conditionally convergent which goes like this:
The series: $$1 - \frac{1}{2} + \frac{1}{3} - \frac{1}{4} + \frac{1}{5} - \dots = \ln 2$$ Multiplying the series by half yields: $$\frac{1}{2} - \frac{1}{4} + \frac{1}{6} - \frac{1}{8} + \dots = \frac{1}{2} \ln 2$$ He then does a trick by inserting zeros between each number: $$0 + \frac{1}{2} +0 - \frac{1}{4}+0 + \frac{1}{6}+0 - \frac{1}{8}+ \dots = \frac{1}{2} \ln 2$$ He then adds the original sum and the newly acquired sum above and obtains: $$1 + \frac{1}{3} - \frac{1}{2} + \frac{1}{5} + \frac{1}{7} - \frac{1}{4} + \dots = \frac{3}{2} \ln 2$$ He asserts that this is the original series with it's terms rearranged with pairwise positive terms followed by negatives yielding a completely different sum.
Stewart, J "Single-Variable Calculus" 5th edition
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While I am not sure about how intuitive it might seem, I find the argument solid and understandable – Dan Jun 6 '13 at 9:47
And now that I look at what you referenced I see its the same example...I suppose it's that popular – Dan Jun 6 '13 at 9:48
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https://optimization-online.org/author/werner-schachinger/
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## The complexity of simple models – a study of worst and typical hard cases for the Standard Quadratic Optimization Problem
In a Standard Quadratic Optimization Problem (StQP), a possibly indefinite quadratic form (the simplest nonlinear function) is extremized over the standard simplex, the simplest polytope. Despite this simplicity, the nonconvex instances of this problem class allow for remarkably rich patterns of coexisting local solutions, which are closely related to practical difficulties in solving StQPs globally. … Read more
## New lower bounds and asymptotics for the cp-rank
Let $p_n$ denote the largest possible cp-rank of an $n\times n$ completely positive matrix. This matrix parameter has its significance both in theory and applications, as it sheds light on the geometry and structure of the solution set of hard optimization problems in their completely positive formulation. Known bounds for $p_n$ are $s_n=\binom{n+1}2-4$, the current … Read more
## From seven to eleven: completely positive matrices with high cp-rank
We study $n\times n$ completely positive matrices $M$ on the boundary of the completely positive cone, namely those orthogonal to a copositive matrix $S$ which generates a quadratic form with finitely many zeroes in the standard simplex. Constructing particular instances of $S$, we are able to construct counterexamples to the famous Drew-Johnson-Loewy conjecture (1994) for … Read more
## On the cp-rank and minimal cp factorizations of a completely positive matrix
We show that the maximal cp-rank of $n\times n$ completely positive matrices is attained at a positive-definite matrix on the boundary of the cone of $n\times n$ completely positive matrices, thus answering a long standing question. We also show that the maximal cp-rank of $5\times 5$ matrices equals six, which proves the famous Drew-Johnson-Loewy conjecture … Read more
## Think co(mpletely )positive ! Matrix properties, examples and a clustered bibliography on copositive optimization
Copositive optimization is a quickly expanding scientific research domain with wide-spread applications ranging from global nonconvex problems in engineering to NP-hard combinatorial optimization. It falls into the category of conic programming (optimizing a linear functional over a convex cone subject to linear constraints), namely the cone of all completely positive symmetric nxn matrices, and its … Read more
## Improved bounds for interatomic distance in Morse clusters
We improve the best known lower bounds on the distance between two points of a Morse cluster in $\mathbb{R}^3$, with $\rho \in [4.967,15]$. Our method is a generalization of the one applied to the Lennard-Jones potential in~\cite{Schac}, and it also leads to improvements of lower bounds for the energy of a Morse cluster. Some of … Read more
A Standard Quadratic Optimization Problem (StQP) consists of maximizing a (possibly indefinite) quadratic form over the standard simplex. Likewise, in a multi-StQP we have to maximize a (possibly indefinite) quadratic form over the cartesian product of several standard simplices (of possibly different dimensions). Two converging monotone interior point methods are established. Further, we prove an … Read more
## A First-Order Interior-Point Method for Linearly Constrained Smooth Optimization
We propose a first-order interior-point method for linearly constrained smooth optimization that unifies and extends first-order affine-scaling method and replicator dynamics method for standard quadratic programming. Global convergence and, in the case of quadratic programs, (sub)linear convergence rate and iterate convergence results are derived. Numerical experience on simplex constrained problems with 1000 variables is reported. … Read more
## A conic duality Frank–Wolfe type theorem via exact penalization in quadratic optimization
The famous Frank–Wolfe theorem ensures attainability of the optimal value for quadratic objective functions over a (possibly unbounded) polyhedron if the feasible values are bounded. This theorem does not hold in general for conic programs where linear constraints are replaced by more general convex constraints like positive-semidefiniteness or copositivity conditions, despite the fact that the … Read more
## New results for molecular formation under pairwise potential minimization
We establish new lower bounds on the distance between two points of a minimum energy configuration of $N$ points in $\mathbb{R}^3$ interacting according to a pairwise potential function. For the Lennard-Jones case, this bound is 0.67985 (and 0.7633 in the planar case). A similar argument yields an estimate for the minimal distance in Morse clusters, … Read more
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http://en.wikipedia.org/wiki/Shannon_number
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# Shannon number
Claude Shannon
The Shannon number, named after Claude Shannon, is an estimated lower bound on the game-tree complexity of chess. Shannon calculated it as an aside in his 1950 paper "Programming a Computer for Playing Chess".[1] (This influential paper introduced the field of computer chess.)
Shannon also estimated the number of possible positions, "of the general order of $\scriptstyle \frac{64!}{32!{8!}^2{2!}^6}$, or roughly 1043 ". This includes some illegal positions (e.g., pawns on the first rank, both kings in check) and excludes legal positions following captures and promotions. Taking these into account, Victor Allis calculated an upper bound of 5×1052 for the number of positions, and estimated the true number to be about 1050.[2] Recent results[3]improve that estimate, by proving an upper bound of only 2155, which is less than 1046.7 and showing[4] an upper bound 2×1040 in the absence of promotions.
Allis also estimated the game-tree complexity to be at least 10123, "based on an average branching factor of 35 and an average game length of 80". As a comparison, the number of atoms in the observable universe, to which it is often compared, is estimated to be between 4×1079 and 4×1081.
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https://zbmath.org/?q=an:0819.05035
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×
## Total dominating functions in trees: Minimality and convexity.(English)Zbl 0819.05035
Authors’ abstract: A total dominating function (TDF) of a graph $$G= (V,E)$$ is a function $$f: V\to [0, 1]$$ such that for each $$v\in V$$, $$\sum_{u\in N(v)} f(u)\geq 1$$ (where $$N(v)$$ denotes the set of neighbors of vertex $$v$$). Convex combinations of TDFs are also TDFs. However, convex combinations of minimal TDFs (i.e., MTDFs) are not necessarily minimal. In this paper we discuss the existence in trees of a universal MTDF (i.e., an MTDF whose convex combinations with any other MTDF are also minimal).
### MSC:
05C35 Extremal problems in graph theory 05C40 Connectivity 05C05 Trees
### Keywords:
convexity; total dominating function; convex combinations; trees
Full Text:
### References:
[1] Cockayne, Networks 24 pp 83– (1994) [2] Masters thesis, University of Victoria (1992).
This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. It attempts to reflect the references listed in the original paper as accurately as possible without claiming the completeness or perfect precision of the matching.
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http://sandordargo.com/blog/2018/01/11/mutation-testing
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A few weeks ago I introduced chaos engineering and this week I am going write briefly about mutation testing. Next week I'll compare these two concepts.
The goal of mutation testing or mutation analysis is to evaluate the quality of your existing software tests. In this kind of white-box testing your production code gets modified in tiny ways. A modified piece of code is called a mutant and if it makes a test fail, the mutant gets killed.
The more mutants are killed, the better your tests are.
But who should be a mutant created? There are well defined mutation operators that either mimic typical programming errors or force creation of valuable tests.
An example for the previous one can be using a wrong operator or variable name and for the latter one it can be forcing divisions by zero.
What does it mean if a mutant doesn’t get killed? It means that either the modification never gets executed, so you have dead code, or that the tests do not cover the outputs enough.
The idea of mutation testing is based on two hypotheses. One is that most of the bugs are introduced by experienced programmers and those are small syntatic errors. The other hypothesis is that these small errors will cascade and couple to form other faults. Fault makes fault.
### The RIP model
To kill a mutant three conditions should be met which are collectively called the RIP model
• Reach the mutated statement
• Infect the program state with the test data
• Propagate the incorrect state to the output
Here is an example. This is the original code:
if a or b:
c = 1
else:
c = 0
And here is the modified code, where or is replaced by and:
if a and b:
c = 1
else:
c = 0
The RIP is for strong mutation testing. If only the first two are satisfied, we can call it weak mutation testing. It’s more related to code coverage.
If a mutant doesn’t make a test fail so if it is not killed. it’s called an equvalent mutant.
At the end of the test execution you will get your test suite’s mutation score by dividing the number of mutants killed by the total number of mutants.
mutation score = number of mutants killed / total number of mutants
### Mutation operators
Just to give you some ideas how a program is modified by a mutation testing framework, I list a few so called mutation operators here.
• Statement deletion
• Statement duplication or insertion
• Remove Conditionals Mutator (e.g. Replacement of boolean subexpressions with true and false)
• Replacement of some arithmetic operations with others (e.g. + with *, - with /)
• Conditionals Boundary Mutator (e.g. replace < with <=)
• Negate Conditionals Mutator
• Invert Negatives Mutator
• Replacement of variables with others from the same scope (where variable types must be compatible)
• Return Values Mutator
• Remove method calls to void methods
• Non Void Method Call Mutator (i.e. replace return values by their type’s defaults)
• Constructor Call Mutator (i.e. constructor returns null instead of an instance)
Happy experimentation and testing!
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http://science.sciencemag.org/content/333/6047/1238
|
NEWS
# Algae's Second Try
See allHide authors and affiliations
Science 02 Sep 2011:
Vol. 333, Issue 6047, pp. 1238-1239
DOI: 10.1126/science.333.6047.1238
## Summary
Fifteen years ago, the United States gave up on algae-based biofuels. But since 2000, more than $2 billion in private funds have flooded into the field. In May, Solazyme, an algae biofuels company, raised$227 million on the stock market. Last year, ExxonMobil announced it would invest up to $600 million in the field, with up to half going to Synthetic Genomics, a start-up looking, like Solazyme, to use synthetic biology to create commercial fuelmaking algae strains. And the U.S. Department of Energy and other federal agencies have jumped back on board contributing hundreds of millions of dollars more, including$104 million from the recent economic stimulus package to Sapphire Energy to build a large-scale algae fuel demonstration facility. So why the change? Biotechnology has made massive strides in recent decades, now making it relatively easy to tinker with algae in ways not possible during the first flurry of interest.
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http://gmatclub.com/forum/of-all-the-students-in-a-certain-dormitory-1-2-are-first-ye-88471.html?sort_by_oldest=true
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# Of all the students in a certain dormitory, 1/2 are first-ye
Author Message
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Of all the students in a certain dormitory, 1/2 are first-ye [#permalink] 27 Dec 2009, 09:47
2
This post was
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Difficulty:
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Question Stats:
76% (02:30) correct 24% (01:37) wrong based on 159 sessions
Of all the students in a certain dormitory, 1/2 are first-year students and the rest are second-year students. If 4/5 of the first-year students have not declared a major and if the fraction of second-year students who have declared a major is 3 times the fraction of first-year students who have declared a major, what fraction of all the students in the dormitory are second-year students who have not declared a major?
A. 1/15
B. 1/5
C. 4/15
D. 1/3
E. 2/5
[Reveal] Spoiler: OA
Last edited by Bunuel on 30 Jan 2013, 06:28, edited 2 times in total.
Renamed the topic and edited the question.
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Re: FDP problem [#permalink] 27 Dec 2009, 13:31
1
KUDOS
I think you dropped a fraction when you typed/copied this in. Working backward from the spoiler answer, I'm thinking the second sentence should read as follows? Please confirm.
"If 4/5 of the first-year students have not declared a major ..."
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Re: FDP problem [#permalink] 27 Dec 2009, 17:09
1
KUDOS
Expert's post
1
This post was
BOOKMARKED
msand wrote:
Of all the students in a certain dormitory, 1/2 are first-year students and the rest are second-year students. If 4/5 of the first-year students have not declared a major and if the fraction of second-year students who have declared a major is 3 times the fraction of first-year students who have declared a major, what fraction of all the students in the dormitory are second-year students who have not declared a major?
A. 1/15
B. 1/5
C. 4/15
D. 1/3
E. 2/5
OA :
[Reveal] Spoiler:
B
First-year=Second-year=x --> all students $$2x$$;
$$\frac{4}{5}x$$ of the first-year students have not declared a major --> $$\frac{1}{5}x$$ declared;
Second-year students who have declared a major is 3 times the fraction of first-year students who have declared a major =$$\frac{3}{5}x$$ --> who have not $$\frac{2}{5}x$$;
Hence: $$\frac{\frac{2}{5}x}{2x}=\frac{1}{5}$$
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Re: FDP problem [#permalink] 27 Dec 2009, 21:10
tot students=x
1st year student=x/2----> non majaor=4/5(x/2)-----> maj=1/5(x/2)
2nd year student=x/2---->maj=3(1/5(x/2))=3/10(x)--->non major=x/2-3/10(x)=1/5(x)
hence 1/5
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Re: FDP problem [#permalink] 27 Dec 2009, 23:05
1/5...dude form the table as given i manhattan series for sets..this would be a cake walk
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Re: FDP problem [#permalink] 30 Jan 2013, 06:25
1
KUDOS
100 Students Total:
1st yr = 50 students
4/5x50 = 40 = No Major
Therefore: 10 = Major
2nd yr = 50 students
10x3 = 30 = Major
Therefore: 20 = No Major
20/100 = 1/5 = B
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Re: Of all the students in a certain dormitory, 1/2 are first-ye [#permalink] 08 Jun 2013, 06:34
1
KUDOS
In this kind of problem table structure is the weapon for me...
Let 2X would be total student which revealed that 1 yrs student is X and 2nd Yr is X as well.
No form the table
MAJOR NO MAJOR Total Student
1st yr Student x/5 4x/5 x
2nd yr Student 3x/5 2x/5 x
Total Student 4x/5 6x/5 2x
From the table 2nd yr student with major is 2x/5 so the answer would be =2x/5/2x =>1/5 Ans
Rgds
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Re: Of all the students in a certain dormitory, 1/2 are first-ye [#permalink] 01 Sep 2014, 18:09
Hello from the GMAT Club BumpBot!
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Re: Of all the students in a certain dormitory, 1/2 are first-ye [#permalink] 03 Sep 2014, 01:26
First ............................................. Second ........................................ Total
x ........................................................ x ................................................ 2x
Major........... NotMajor ................... Major ............ NotMajor ..........
$$\frac{4x}{5}$$ ................ $$\frac{x}{5}$$ ........................ $$\frac{3x}{5}$$ ................... $$\frac{2x}{5}$$ ...................... 2x
Fraction $$= \frac{\frac{2x}{5}}{2x} = \frac{1}{5}$$
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Re: Of all the students in a certain dormitory, 1/2 are first-ye [#permalink] 03 Sep 2014, 01:26
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http://tex.stackexchange.com/questions/125797/need-help-with-modifying-ntheorem-environments
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# Need help with modifying ntheorem environments
I am trying to modify some of the theorem environments defined in ntheorem. I wanted the definitions in my document to be boxed the way in which ntheorem does for the framed theorem classes which they define by:
\theoremclass{Theorem}
\theoremstyle{break}
\newframedtheorem{importantTheorem}[Theorem]{Theorem}
and so I modified the above code to the following:
\theoremclass{Theorem}
\theoremstyle{break}
\newframedtheorem{defn}[Theorem]{Definition}
then in my document called up an instance of a definition by:
\begin{defn}[Logical Equivalance] Two propositions are said to be logically equivalent iff ...
\end{defn}
Now, I wish to modify their shaded theorem environment which is coded as follows:
\theoremclass{Theorem}
\theoremstyle{break}
I tried the following:
\theoremclass{Theorem}
\theoremstyle{break}
but keep getting the error:
Undefined control sequence: begin{prop}
Can anyone help me with this?
\documentclass[10pt,a4paper]{article}
\usepackage[left=2.50cm,right=2.50cm,top=2.50cm,bottom=2.75cm]{geometry}
\usepackage{amsmath,amssymb,amscd,amstext,amsbsy,array,color,epsfig}
\usepackage{fancyhdr,framed,latexsym,multicol,pstricks,slashed,xcolor}
\usepackage[amsmath,framed,thmmarks]{ntheorem}
\begin{document}
\theoremstyle{marginbreak}
\theorembodyfont{\slshape}
\theoremsymbol{\ensuremath{\star}}
\theoremseparator{:}
\newtheorem{axm}{Axiom}[section]
\theoremstyle{marginbreak}
\theorembodyfont{\slshape}
\theoremsymbol{\ensuremath{\diamondsuit}}
\theoremseparator{:}
\newtheorem{Theorem}{Theorem}[section]
\theoremclass{Theorem}
\theoremstyle{break}
\theoremstyle{changebreak}
\theoremsymbol{\ensuremath{\heartsuit}}
\theoremindent0.5cm
\theoremnumbering{greek}
\newtheorem{lem}{Lemma}[section]
\theoremindent0cm
\theoremnumbering{arabic}
\newtheorem{cor}[Theorem]{Corollary}
\theoremstyle{plain}
\theorembodyfont{\upshape}
\theoremsymbol{\ensuremath{\bullet}}
\theoremseparator{}
\newtheorem{exm}{Example}
\theoremclass{Theorem}
\theoremstyle{plain}
\theoremsymbol{\ensuremath{\clubsuit}}
\newframedtheorem{defn}[Theorem]{Definition}
\theorembodyfont{\upshape}
\theoremstyle{nonumberplain}
\theoremseparator{.}
\theoremsymbol{\rule{1ex}{1ex}}
\newtheorem{proof}{Proof}
\theoremstyle{plain}
\theorembodyfont{\upshape}
\theoremsymbol{\ensuremath{\ast}}
\theoremseparator{.}
\newtheorem{rem}{Remark}
\theoremstyle{plain}
\theorembodyfont{\upshape}
\newtheorem{exc}{Exercise}[section]
\begin{defn}[Logical Equivalance] Two propositions are said to be logically equivalent iff ...
\end{defn}
\begin{prop}
Let $P$ and $Q$ be propositions. Then ...
\end{prop}
\end{document}
Thanks!!!
I am now added more "theorem"-like enviornments and am getting even more errors and would ask that some one please help me use mdframed to fix the problem if that is possible. Here is a current and up-to-date mwe:
\documentclass[a4paper,12pt,twoside]{book}
\usepackage[left=2.50cm,right=2.50cm,top=2.50cm,bottom=2.75cm]{geometry}
\usepackage{amsmath,amssymb,amscd,amsbsy,array,color,epsfig}
\usepackage{fancyhdr,framed,latexsym,multicol,pstricks,slashed,xcolor}
\usepackage{picture}
\usepackage{indentfirst}
\usepackage{enumitem}
\usepackage{tikz}
\usepackage{subfig}
\usetikzlibrary{calc,positioning,shapes.geometric}
\setenumerate[1]{label=(\alph*)}
\usepackage[amsmath,framed,thmmarks]{ntheorem}
\newtheorem{Theorem}{Thm}
\theoremclass{Theorem}
\theoremstyle{break}
\theoremclass{Theorem}
\theoremstyle{break}
\theoremclass{Theorem}
\theoremstyle{plain}
\newframedtheorem{lema}[Theorem]{Lemma}
\theoremclass{Theorem}
\theoremstyle{plain}
\newframedtheorem{coro}[Theorem]{Corollary}
\theoremstyle{plain}
\theoremsymbol{\ensuremath{\blacktriangle}}
\theoremseparator{.}
\theoremprework{\bigskip\hrule}
\theorempostwork{\hrule\bigskip}
\newtheorem{defn}{Definition}
\theoremstyle{plain}
\theorembodyfont{\upshape}
\theoremsymbol{\ensuremath{\bullet}}
\theoremseparator{}
\newtheorem{exam}{Example}
\theoremstyle{plain}
\theorembodyfont{\upshape}
\theoremsymbol{\ensuremath{\bullet}}
\newtheorem{exer}{Exercise}[section]
\theorembodyfont{\color{blue}\bfseries\boldmath}
\theoremstyle{nonumberplain}
\theoremseparator{.}
\theoremsymbol{\rule{1ex}{1ex}}
\newtheorem{proof}{Proof}
\theoremstyle{plain}
\theorembodyfont{\upshape}
\theoremsymbol{\ensuremath{\bigstar}}
\theoremseparator{.}
\newtheorem{remk}{Remark}
\def \all {\forall}
\def \ex {\exists}
\def \imp {\Rightarrow}
\def \limp {\Leftarrow}
\def \iff {\Longleftrightarrow}
\def \contra {\rightarrow\negmedspace\leftarrow}
\def \es {\emptyset}
\def \st {\backepsilon}
\def \bn{\mathbb N}
\def \bz{\mathbb Z}
\def \bq{\mathbb Q}
\def \br{\mathbb R}
\def \bc{\mathbb C}
\def \bp{\mathbb P}
\def \bt{\mathbb T}
\begin{defn}[Statement/Proposition]
Declarative sentences or strings of symbols in mathematics which can be said to have \textit{exactly} one \textit{truth value}, that is, are either true (denoted T), or false (denoted F), are known as \textbf{statements} or \textbf{propositions}.
\end{defn}
\begin{exam}
Hence, the truth value of the negation of a proposition is \textit{merely} the opposite of the truth value of said proposition. Hence, the truth value of the proposition '$7$ is divisible by $2$' is the proposition 'It is not the case that $7$ is not divisible by $2$' or '$7$ is not divisible by $2$' (both of which are true).
\end{exam}
\begin{prop}
Let $P$ and $Q$ be propositions. Then:
\begin{enumerate}
\item $P \imp Q \equiv (\neg Q) \imp (\neg P).$
\item $P \imp Q \not \equiv Q \imp P.$
\end{enumerate}
\end{prop}
\begin{prop}
Let $P,Q,$ and $R$ be propositions. Then:
\begin{enumerate}
\item $P \imp Q \equiv (\neg P) \vee (Q).$
\item $P \iff Q \equiv (P \imp Q) \wedge (Q \imp P).$
\item $\neg(P \imp Q) \equiv (P) \wedge (\neg Q).$
\item $\neg(P \wedge Q) \equiv (P) \imp (\neg Q) \equiv (Q) \imp (\neg P).$
\item $P \imp (Q \imp R) \equiv (P \wedge Q) \imp R.$
\item $P \imp (Q \vee R) \equiv (P \imp Q) \wedge (P \imp R).$
\item $(P \vee Q) \imp R \equiv (P \imp R) \wedge (Q \imp R).$
\end{enumerate}
\end{prop}
\begin{proof}
The proof for the above proposition is left to the reader. All of the above statements may be proved using truth tables.
\end{proof}
\begin{axm}[Field Axioms of $\br$]
On the set $\br$ of real numbers, there are two binary operations, denoted by $\pmb{+}$ and $\pmb{\cdot}$ and called \textbf{addition} and \textbf{multiplication} respectively. These operations satisfy the following properties:
\begin{itemize}
\item[$A_0$] $x,y \in \br \imp x+y \in \br \q \all \, x,y \in \br$. [additive closure]
\item[$A_1$] $x+y=y+x \q \all \, x,y \in \br$. [additive commutativity]
\item[$A_2$] $(x+y)+z=x+(y+z) \q \all \, x,y,z \in \br$. [additive associativity]
\item[$A_3$] There is a unique $0 \in \br \text{ such that } 0+x=x=x+0 \q \all \, x \in \br$. [existence of an additive identity]
\item[$A_4$] There is a unique $-x \in \br \text{ such that } x+(-x)=0=(-x)+x \q \all \, x \in \br$. [existence of an additive inverse]
\item[$M_0$] $x,y \in \br \imp x \cdot y \in \br \q \all \, x,y \in \br$. [multiplicative closure]
\item[$M_1$] $x \cdot y=y \cdot x \q \all \, x,y \in \br$. [multiplicative commutativity]
\item[$M_2$] $(x \cdot y) \cdot z=x \cdot (y \cdot z) \q \all \, x,y,z \in \br$. [multiplicative associativity]
\item[$M_3$] There is a unique $1 \in \br \text{ such that } 1 \cdot x=x=x \cdot 1 \q \all \, x \in \br$. [existence of multiplicative identity]
\item[$M_4$] There is a unique $\nicefrac{1}{x} \in \br \text{ such that } x \cdot (\nicefrac{1}{x})=1=(\nicefrac{1}{x}) \cdot x \q \all x \in \br$. [existence of multiplicative inverse]
\item[$AM_1$] $x \cdot (y+z) = (x \cdot y) + (x \cdot z)$ and $(y + z) \cdot x = (y \cdot x) + (z \cdot x)$. [distributivity]
\end{itemize}
\end{axm}
\begin{rem}
The reader should be familiar with all of the aforementioned field properties. We note that all of the familiar' properties of algebra (those learned in middle school and high school, for example) may be deduced from this list. We now establish the basic fact that both the additive identity, $0$, and the multiplicative identity are in fact unique; and that multiplication by $0$ always results in $0$.
\end{rem}
\end{document}
-
Please, add a minimal working example; it doesn't matter if it produces the error, but for help us in finding the issue it should start with \documentclass and end with \end{document}. However, the undefined sequence seems to be \psframebox, due to not loading PSTricks. – egreg Jul 28 '13 at 20:26
\newtheorem{Theorem}{Thm}
which is needed for both of your subsequent theorem-like environments, prop and defn.
% arara: latex
% arara: dvips
% arara: ps2pdf
% !arara: indent: {overwrite: yes}
\documentclass[10pt,a4paper]{article}
\usepackage[left=2.50cm,right=2.50cm,top=2.50cm,bottom=2.75cm]{geometry}
\usepackage{amsmath}
\usepackage{pstricks}
\usepackage{framed}
\usepackage[amsmath,framed,thmmarks]{ntheorem}
\newtheorem{Theorem}{Thm}
\theoremclass{Theorem}
\theoremstyle{break}
\theoremclass{Theorem}
\theoremstyle{plain}
\theoremsymbol{\ensuremath{\clubsuit}}
\newframedtheorem{defn}[Theorem]{Definition}
\begin{document}
\begin{defn}[Logical Equivalance]
Two propositions are said to be logically equivalent iff ...
\end{defn}
\begin{prop}
Let $P$ and $Q$ be propositions. Then ...
\end{prop}
\end{document}
Note that this MWE relies upon the pstricks package, so needs to be compiled through the latex->dvips->ps2pdf unless you want to follow the instructions in How to use PSTricks in pdfLaTeX?
For all of your framing needs I would highly recommend the mdframed package, which addresses the many short comings of its competitors.
Here's a version of the previous MWE using the mdframed package; note that this package does not rely upon the pstricks package (in contrast to the previous method). As such, you can (easily) compile this document with pdflatex.
% arara: pdflatex
% !arara: indent: {overwrite: yes}
\documentclass[10pt,a4paper]{article}
\usepackage[left=2.50cm,right=2.50cm,top=2.50cm,bottom=2.75cm]{geometry}
\usepackage{amsmath}
\usepackage[amsmath,framed,thmmarks]{ntheorem}
\usepackage[ntheorem,xcolor]{mdframed}
\newtheorem{Theorem}{Thm}
\theoremclass{Theorem}
\theoremstyle{break}
\newmdtheoremenv[
outerlinewidth = 2 ,%
roundcorner = 10 pt ,%
leftmargin = 40 ,%
rightmargin = 40 ,%
backgroundcolor=yellow!40,%
outerlinecolor=blue!70!black,%
innertopmargin=\topskip,%
splittopskip = \topskip ,%
ntheorem = true ,%
]{prop}[Theorem]{Proposition}
\theoremstyle{plain}
\theoremsymbol{\ensuremath{\clubsuit}}
%\newframedtheorem{defn}[Theorem]{Definition}
\newmdtheoremenv{defn}[Theorem]{Definition}
\begin{document}
\begin{defn}[Logical Equivalance]
Two propositions are said to be logically equivalent iff ...
\end{defn}
\begin{prop}
Let $P$ and $Q$ be propositions. Then ...
\end{prop}
\end{document}
Of course, the mdframed package can be told to use pstricks or tikz if you wish, but that is beyond the scope of the question- see the manual for more details.
Update, following the question edit.
With the additional theorem-like environments, this MWE works- note that you can't define a theorem-like environment twice using \newtheorem
% arara: latex
% arara: dvips
% arara: ps2pdf
% !arara: indent: {overwrite: yes}
\documentclass[10pt,a4paper]{article}
\usepackage[left=2.50cm,right=2.50cm,top=2.50cm,bottom=2.75cm]{geometry}
\usepackage{amsmath}
\usepackage{pstricks}
\usepackage{framed}
\usepackage[amsmath,framed,thmmarks]{ntheorem}
\theoremstyle{marginbreak}
\theorembodyfont{\slshape}
\theoremsymbol{\ensuremath{\diamondsuit}}
\theoremseparator{:}
\newtheorem{Theorem}{Theorem}[section]
\theoremclass{Theorem}
\theoremstyle{break}
\theoremclass{Theorem}
\theoremstyle{plain}
\theoremsymbol{\ensuremath{\clubsuit}}
\newframedtheorem{defn}[Theorem]{Definition}
\theoremstyle{marginbreak}
\theorembodyfont{\slshape}
\theoremsymbol{\ensuremath{\star}}
\theoremseparator{:}
\newtheorem{axm}{Axiom}[section]
\theoremstyle{changebreak}
\theoremsymbol{\ensuremath{\heartsuit}}
\theoremindent0.5cm
\theoremnumbering{greek}
\newtheorem{lem}{Lemma}[section]
\theoremindent0cm
\theoremnumbering{arabic}
\newtheorem{cor}[Theorem]{Corollary}
\theoremstyle{plain}
\theorembodyfont{\upshape}
\theoremsymbol{\ensuremath{\bullet}}
\theoremseparator{}
\newtheorem{exm}{Example}
\theorembodyfont{\upshape}
\theoremstyle{nonumberplain}
\theoremseparator{.}
\theoremsymbol{\rule{1ex}{1ex}}
\newtheorem{proof}{Proof}
\theoremstyle{plain}
\theorembodyfont{\upshape}
\theoremsymbol{\ensuremath{\ast}}
\theoremseparator{.}
\newtheorem{rem}{Remark}
\theoremstyle{plain}
\theorembodyfont{\upshape}
\newtheorem{exc}{Exercise}[section]
\begin{document}
\begin{defn}[Logical Equivalance]
Two propositions are said to be logically equivalent iff ...
\end{defn}
\begin{prop}
Let $P$ and $Q$ be propositions. Then ...
\end{prop}
\end{document}
-
I just added my current definitions of theorem-like environments that I use for this document, and when I add \newtheorem{Theorem}{thm} I get the error message: Command \Theorem already defined. – Michael Dykes Jul 28 '13 at 23:20
@MichaelDykes you've added them after your \end{document}`. Please make a complete MWE :) – cmhughes Jul 29 '13 at 7:51
I just corrected my mistake. Sorry about that :)- – Michael Dykes Jul 29 '13 at 9:41
@MichaelDykes see my updated answer :) – cmhughes Jul 29 '13 at 9:48
Now, I get the errors: No counter theorem defined for the proposition, and definition environments. – Michael Dykes Jul 31 '13 at 1:35
|
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|
https://archive.softwareheritage.org/browse/content/sha1_git:cd1a55efd6156eab02bfc204aa74bedeebd7eadc/?branch=refs/tags/R-2.14.2&path=man/fiadeiro.Rd&snapshot_id=bbc0b94b1c0463480b615c86f1ae2df3fcc700c0
|
swh:1:snp:bbc0b94b1c0463480b615c86f1ae2df3fcc700c0
Tip revision: 72984f1
\name{fiadeiro}
\title{
}
\description{
Weighing coefficients used in the finite difference scheme for advection
calculated according to Fiadeiro and Veronis (1977).
This particular AFDW (advective finite difference weights) scheme switches
from backward differencing (in advection dominated conditions; large Peclet
numbers) to central differencing (under diffusion dominated conditions;
small Peclet numbers).
This way it forms a compromise between stability, accuracy and reduced
numerical dispersion.
}
\usage{
fiadeiro(v, D, dx.aux = NULL, grid = list(dx.aux = dx.aux))
}
\arguments{
\item{v }{advective velocity; either one value or a vector of length N+1,
with N the number of grid cells [L/T]
}
\item{D }{diffusion coefficient; either one value or a vector of length N+1
[L2/T]
}
\item{dx.aux }{auxiliary vector containing the distances between the
locations where the concentration is defined (i.e. the grid cell centers
and the two outer interfaces);
either one value or a vector of length N+1 [L]
}
\item{grid }{discretization grid as calculated by \code{\link{setup.grid.1D}}
}
}
\value{
the Advective Finite Difference Weighing (AFDW) coefficients as used in
either one value or a vector of length N+1 [-]
}
\author{
Filip Meysman <[email protected]>,
Karline Soetaert <[email protected]>
}
\examples{
#============================================
# Model formulation (differential equations)
#============================================
# This is a test model to evaluate the different finite difference schemes
# and evaluate their effect on munerical diffusion. The model describes the
# decay of organic carbon (OC) as it settles through the ocean water column.
model <- function (time, OC, pars, AFDW = 1) {
dOC <- tran.1D(OC, flux.up = F_OC, D = D.eddy,
v = v.sink, AFDW = AFDW, dx = dx)\$dC - k*OC
return(list(dOC))
}
#============================================
# Parameter set
#============================================
L <- 1000 # water depth model domain [m]
x.att <- 200 # attenuation depth of the sinking velocity [m]
v.sink.0 <- 10 # sinking velocity at the surface [m d-1]
D.eddy <- 10 # eddy diffusion coefficient [m2 d-1]
F_OC <- 10 # particle flux [mol m-2 d-1]
k <- 0.1 # decay coefficient [d-1]
## =============================================================================
## Model solution for a coarse grid (10 grid cells)
## =============================================================================
# Setting up the grid
N <- 10 # number of grid layers
dx <- L/N # thickness of boxes [m]
dx.aux <- rep(dx, N+1) # auxilliary grid vector
x.int <- seq(from = 0, to = L, by = dx) # water depth at box interfaces [m]
x.mid <- seq(from = dx/2, to = L, by = dx) # water depth at box centres [m]
# Exponentially declining sink velocity
v.sink <- v.sink.0 * exp(-x.int/x.att) # sink velocity [m d-1]
Pe <- v.sink * dx/D.eddy # Peclet number
# Calculate the weighing coefficients
AFDW <- fiadeiro(v = v.sink, D = D.eddy, dx.aux = dx.aux)
par(mfrow = c(2, 1), cex.main = 1.2, cex.lab = 1.2)
# Plot the Peclet number over the grid
plot(Pe, x.int, log = "x", pch = 19, ylim = c(L,0), xlim = c(0.1, 1000),
xlab = "", ylab = "depth [m]",
main = "Peclet number", axes = FALSE)
abline(h = 0)
axis(pos = NA, side = 2)
axis(pos = 0, side = 3)
# Plot the AFDW coefficients over the grid
plot(AFDW, x.int, pch = 19, ylim = c(L, 0), xlim = c(0.5, 1),
xlab = "", ylab = "depth [m]", main = "AFDW coefficient", axes = FALSE)
abline(h = 0)
axis(pos = NA, side = 2)
axis(pos = 0, side = 3)
# Three steady-state solutions for a coarse grid based on:
# (1) backward differences (BD)
# (2) central differences (CD)
# (3) Fiadeiro & Veronis scheme (FV)
BD <- steady.1D(y = runif(N), func = model, AFDW = 1.0, nspec = 1)
CD <- steady.1D(y = runif(N), func = model, AFDW = 0.5, nspec = 1)
FV <- steady.1D(y = runif(N), func = model, AFDW = AFDW, nspec = 1)
# Plotting output - use rootSolve's plot method
plot(BD, CD, FV, grid = x.mid, xyswap = TRUE, mfrow = c(1,2),
xlab = "", ylab = "depth [m]", main = "conc (Low resolution grid)")
legend("bottomright", col = 1:3, lty = 1:3,
legend = c("backward diff", "centred diff", "Fiadeiro&Veronis"))
## =============================================================================
## Model solution for a fine grid (1000 grid cells)
## =============================================================================
# Setting up the grid
N <- 1000 # number of grid layers
dx <- L/N # thickness of boxes[m]
dx.aux <- rep(dx, N+1) # auxilliary grid vector
x.int <- seq(from = 0, to = L, by = dx) # water depth at box interfaces [m]
x.mid <- seq(from = dx/2, to = L, by = dx) # water depth at box centres [m]
# Exponetially declining sink velocity
v.sink <- v.sink.0 * exp(-x.int/x.att) # sink velocity [m d-1]
Pe <- v.sink * dx/D.eddy # Peclet number
# Calculate the weighing coefficients
AFDW <- fiadeiro(v = v.sink, D = D.eddy, dx.aux = dx.aux)
# Three steady-state solutions for a coarse grid based on:
# (1) backward differences (BD)
# (2) centered differences (CD)
# (3) Fiadeiro & Veronis scheme (FV)
BD <- steady.1D(y = runif(N), func = model, AFDW = 1.0, nspec = 1)
CD <- steady.1D(y = runif(N), func = model, AFDW = 0.5, nspec = 1)
FV <- steady.1D(y = runif(N), func = model, AFDW = AFDW, nspec = 1)
# Plotting output
plot(BD, CD, FV, grid = x.mid, xyswap = TRUE, mfrow = NULL,
xlab = "", ylab = "depth [m]", main = "conc (High resolution grid)")
legend("bottomright", col = 1:3, lty = 1:3,
legend = c("backward diff", "centred diff", "Fiadeiro&Veronis"))
# Results and conclusions:
# - For the fine grid, all three solutions are identical
# - For the coarse grid, the BD and FV solutions show numerical dispersion
# while the CD provides more accurate results
}
\references{
\itemize{
\item Fiadeiro ME and Veronis G (1977) Weighted-mean schemes for
Tellus 29, 512-522.
\item Boudreau (1997) Diagnetic models and their implementation.
Chapter 8: Numerical Methods. Springer.
}
}
\details{
the local situation (checks for advection or diffusion dominance).
Finite difference schemes are based on following rationale:
\itemize{
\item When using forward differences (AFDW = 0), the scheme is first
order accurate, creates a low level of (artificial) numerical dispersion,
but is highly unstable (state variables may become negative).
\item When using backward differences (AFDW = 1), the scheme is first
order accurate, is universally stable (state variables always remain
positive), but the scheme creates high levels of numerical dispersion.
\item When using central differences (AFDW = 0.5), the scheme is second
order accurate, is not universally stable, and has a moderate level of
numerical dispersion, but state variables may become negative.
}
Because of the instability issue, forward schemes should be avoided.
Because of the higher accuracy, the central scheme is preferred over the
backward scheme.
The central scheme is stable when sufficient physical dispersion is present,
it may become unstable when advection is the only transport process.
The Fiadeiro and Veronis (1977) scheme takes this into account: it uses
central differencing when possible (when physical dispersion is high enough),
and switches to backward differing when needed (when advection dominates).
The switching is determined by the Peclet number
\code{Pe = abs(v)*dx.aux/D}
\itemize{
\item the higher the diffusion \code{D} (\code{Pe > 1}), the closer the
AFDW coefficients are to 0.5 (central differencing)
\item the higher the advection \code{v} (\code{Pe < 1}), the closer the
AFDW coefficients are to 1 (backward differencing)
}
}
\note{
\itemize{
\item If the state variables (concentrations) decline in the direction
of the 1D axis, then the central difference scheme will be stable.
If this is known a prioiri, then central differencing is
|
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|
http://mathhelpforum.com/discrete-math/190139-simplify-b-u-upside-u-b.html
|
# Math Help - Simplify (A-B) U (A (upside U) B)
1. ## Simplify (A-B) U (A (upside U) B)
for this problem (A-B) U (A (upside U) B). simplify using laws of set theory.
where do i even begin. my first time using this. not even sure how to put in correct symbols.
any help would be awesome.
2. ## Re: Simplify (A-B) U (A (upside U) B)
Originally Posted by nvm0019
for this problem (A-B) U (A (upside U) B). simplify using laws of set theory.
Consider $U$ as universal set (for example $U=A\cup B$) then:
$(A-B)\cup (A\cap B)=(A\cap B^c)\cup (A\cap B)=\ldots=A$
(Use one distributive law, $M^c\cup M=U$ and $N\cap U=N$ )
3. ## Re: Simplify (A-B) U (A (upside U) B)
Hello, nvm0019!
$\text{Simplify: }\:(A - B) \cup (A \cap B)$
$\begin{array}{cccccccc}1. & (A-B) \cap (A\cap B) && 1. & \text{Given} \\ \\[-3mm] 2. & (A\;\cap \sim\!B) \cup (A \cap B) && 2. & \text{def. Subtr'n} \\ \\[-3mm] 3. & (A \cup A) \cap (A \cup B) \cap (\sim\!B \cup A) \cap (\sim\!B \cup B) && 3. & \text{Distributive} \\ \\[-3mm] 4. & A \cap (A \cup B) \cap (A\;\cup \sim\!B) \cap U && 4. & s \cup s \:=\:s \\ &&&& \sim\!s \cup s \:=\:U \\ \\[-3mm] 5. & A \cap (A \cup B) \cap (A\; \cup \sim\!B) && 5. & s \cap U \:=\:s \\ \\[-3mm] 6. & A \cap \big[A \cup (B \;\cap \sim\!B)\big] && 6. & \text{Distributive} \\ \\[-3mm] 7. & A \cap \big[A \cup \emptyset\big] && 7. & s\;\cap\sim\!s \:=\:\emptyset \\ \\[-3mm] 8. & A \cap A && 8. & s \cup \emptyset \:=\:s \\ \\[-3mm] 9. & A && 9. & s \cap s \:=\:s \end{array}$
|
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https://im.kendallhunt.com/HS/students/4/5/16/index.html
|
# Lesson 16
Over and Over
• Let’s change quantities by a percentage several times.
### 16.1: The Phone for the Lowest Price
A phone is on sale. Which sale results in the lowest price? Explain your reasoning.
1. A $200 phone that is 35% off. 2. A$200 phone for sale at 60% of its original price.
3. A $150 phone for sale at 87.5% of its original price. 4. A$140 phone that is 8.5% off.
### 16.2: Two Saving Methods
Two people open bank accounts and deposit $1,000 each. Both bank accounts earn 7.5% interest every year. • Kiran leaves$1,000 alone, but withdraws the interest each year.
• Jada leaves the interest in the bank account.
How much money does each person have after 5 years? Explain.
### 16.3: Wild Sales
1. Tyler really wanted a $200 jacket he saw in a shop window on his way to school every day. On Monday he noticed a sign on the jacket that said, “20% off each day!” The fine print said, “Price is reduced by 20% today, and will be reduced by an additional 20% of the previous price every day until the jacket is sold.” Tyler wondered if the jacket would be free on Friday. Diego does not think it will be free. Who do you agree with, and why? 2. Elena saw that a local store was having a 50% off everything storewide sale. She had a coupon for 50% off the final price of any item at that store, and the coupon said, “Combine with any other offers!” She said, “I think I can get anything I want for free!” Priya said, “Not for free, but for 75% off, I think.” Who do you agree with, and why? 3. Andre and Clare are saving money. They each started with$20. Each week for 3 weeks, Andre increased his savings by 25%. Clare didn’t increase her savings for 2 weeks, but in the third week, she increased her savings by 75% to keep up with Andre. Andre claims he raised more money. Clare says they are even. Who do you agree with, and why?
4. Jada and Lin are saving money. They each started with \$50. Each week for 4 weeks, Jada increased her savings by 15%. After 2 weeks, Lin increases her savings by 30%, and after another 2 weeks, by 30% again. Jada says that they both increased their savings by 60% and have the same amount. Lin is not sure. Do they have the same amount of savings? If not, who has more savings? Explain your reasoning.
|
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|
http://proceedings.mlr.press/v28/lopes13.html
|
# Estimating Unknown Sparsity in Compressed Sensing
Miles Lopes ;
Proceedings of the 30th International Conference on Machine Learning, PMLR 28(3):217-225, 2013.
#### Abstract
In the theory of compressed sensing (CS), the sparsity \|x\|_0 of the unknown signal x∈\R^p is commonly assumed to be a known parameter. However, it is typically unknown in practice. Due to the fact that many aspects of CS depend on knowing \|x\|_0, it is important to estimate this parameter in a data-driven way. A second practical concern is that \|x\|_0 is a highly unstable function of x. In particular, for real signals with entries not exactly equal to 0, the value \|x\|_0=p is not a useful description of the effective number of coordinates. In this paper, we propose to estimate a stable measure of sparsity s(x):=\|x\|_1^2/\|x\|_2^2, which is a sharp lower bound on \|x\|_0. Our estimation procedure uses only a small number of linear measurements, does not rely on any sparsity assumptions, and requires very little computation. A confidence interval for s(x) is provided, and its width is shown to have no dependence on the signal dimension p. Moreover, this result extends naturally to the matrix recovery setting, where a soft version of matrix rank can be estimated with analogous guarantees. Finally, we show that the use of randomized measurements is essential to estimating s(x). This is accomplished by proving that the minimax risk for estimating s(x) with deterministic measurements is large when n≪p.
|
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https://horovod.readthedocs.io/en/stable/api.html
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# API¶
## horovod.tensorflow¶
class horovod.tensorflow.Compression[source]
Optional gradient compression algorithm used during allreduce.
none
Compress all floating point gradients to 16-bit.
alias of NoneCompressor
fp16
alias of FP16Compressor
horovod.tensorflow.allgather_object(obj, session=None, name=None)[source]
Serializes and allgathers an object from all other processes.
Parameters
• obj – An object capable of being serialized without losing any context.
• session – Session for TensorFlow v1 compatibility.
• name – Optional name to use during allgather, will default to the class type.
Returns
The list of objects that were allgathered across all ranks.
horovod.tensorflow.broadcast_object(obj, root_rank=0, session=None, name=None)[source]
Serializes and broadcasts an object from root rank to all other processes.
Parameters
• obj – An object capable of being serialized without losing any context.
• root_rank – The rank of the process from which parameters will be broadcasted to all other processes.
• session – Session for TensorFlow v1 compatibility.
• name – Optional name to use during broadcast, will default to the class type.
Returns
The object that was broadcast from the root_rank.
horovod.tensorflow.broadcast_variables(variables, root_rank)[source]
Broadcasts variables from root rank to all other processes.
Parameters
• variables – variables for broadcast
• root_rank – rank of the process from which global variables will be broadcasted to all other processes.
horovod.tensorflow.allgather(tensor, name=None, ignore_name_scope=False)[source]
An op which concatenates the input tensor with the same input tensor on all other Horovod processes.
The concatenation is done on the first dimension, so the input tensors on the different processes must have the same rank and shape, except for the first dimension, which is allowed to be different.
Returns
A tensor of the same type as tensor, concatenated on dimension zero across all processes. The shape is identical to the input shape, except for the first dimension, which may be greater and is the sum of all first dimensions of the tensors in different Horovod processes.
horovod.tensorflow.broadcast(tensor, root_rank, name=None, ignore_name_scope=False)[source]
An op which broadcasts the input tensor on root rank to the same input tensor on all other Horovod processes.
The broadcast operation is keyed by the name of the op. The tensor type and shape must be the same on all Horovod processes for a given name. The broadcast will not start until all processes are ready to send and receive the tensor.
Returns
A tensor of the same shape and type as tensor, with the value broadcasted from root rank.
horovod.tensorflow.alltoall(tensor, splits=None, name=None, ignore_name_scope=False)[source]
An op that scatters slices of the input tensor to all other Horovod processes and returns a tensor of gathered slices from all other Horovod processes.
The slicing is done on the first dimension, so the input tensors on the different processes must have the same rank and shape, except for the first dimension, which is allowed to be different.
Parameters
• tensor – A tensor to distribute with alltoall.
• splits – A tensor of integers in rank order describing how many elements in tensor to send to each worker. Splitting is applied along the first dimension of tensor. If splits is not provided, the first dimension is split equally by the number of Horovod processes.
• name – A name of the alltoall operation.
• ignore_name_scope – If True, ignores any outer name scope applied by TensorFlow in the name used by the Horovod operation.
Returns
A tensor of the same type as tensor, concatenated on dimension zero across all processes. The shape is identical to the input shape, except for the first dimension, which may be greater and is the sum of all first dimensions of the gathered tensor slices from different Horovod processes.
horovod.tensorflow.init(comm=None)
A function that initializes Horovod.
Parameters
comm – List specifying ranks for the communicator, relative to the MPI_COMM_WORLD communicator OR the MPI communicator to use. Given communicator will be duplicated. If None, Horovod will use MPI_COMM_WORLD Communicator.
horovod.tensorflow.shutdown()
A function that shuts Horovod down.
horovod.tensorflow.is_initialized()
Returns True if Horovod is initialized
horovod.tensorflow.start_timeline(file_path, mark_cycles=False)
Creates a timeline file at file_path and begins recording.
Parameters
• file_path – String path to the timeline file.
• mark_cycles – Boolean indicating that cycles should be marked on the timeline (default: False).
Raises a ValueError if Horovod is not initialized.
horovod.tensorflow.stop_timeline()
Stops the active timeline recording and closes the file.
Raises a ValueError if Horovod is not initialized.
horovod.tensorflow.size()
A function that returns the number of Horovod processes.
Returns
An integer scalar containing the number of Horovod processes.
horovod.tensorflow.local_size()
A function that returns the number of Horovod processes within the node the current process is running on.
Returns
An integer scalar containing the number of local Horovod processes.
horovod.tensorflow.rank()
A function that returns the Horovod rank of the calling process.
Returns
An integer scalar with the Horovod rank of the calling process.
horovod.tensorflow.local_rank()
A function that returns the local Horovod rank of the calling process, within the node that it is running on. For example, if there are seven processes running on a node, their local ranks will be zero through six, inclusive.
Returns
An integer scalar with the local Horovod rank of the calling process.
horovod.tensorflow.is_homogeneous()
Returns True if the cluster is homogeneous.
Returns
A boolean value indicating whether every node in the cluster has same number of ranks.
horovod.tensorflow.rank_op(name=None)[source]
An op that returns the Horovod rank of the calling process.
This operation determines the return value at the graph execution time, rather than at the graph construction time, and so allows for a graph to be constructed in a different environment than where it will be executed.
Returns
An integer scalar with the Horovod rank of the calling process.
horovod.tensorflow.local_rank_op(name=None)[source]
An op that returns the local Horovod rank of the calling process, within the node that it is running on. For example, if there are seven processes running on a node, their local ranks will be zero through six, inclusive.
This operation determines the return value at the graph execution time, rather than at the graph construction time, and so allows for a graph to be constructed in a different environment than where it will be executed.
Returns
An integer scalar with the local Horovod rank of the calling process.
horovod.tensorflow.size_op(name=None)[source]
An op that returns the number of Horovod processes.
This operation determines the return value at the graph execution time, rather than at the graph construction time, and so allows for a graph to be constructed in a different environment than where it will be executed.
Returns
An integer scalar containing the number of Horovod processes.
horovod.tensorflow.local_size_op(name=None)[source]
An op that returns the number of Horovod processes within the node the current process is running on.
This operation determines the return value at the graph execution time, rather than at the graph construction time, and so allows for a graph to be constructed in a different environment than where it will be executed.
Returns
An integer scalar containing the number of local Horovod processes.
horovod.tensorflow.mpi_threads_supported()
A function that returns a flag indicating whether MPI multi-threading is supported.
If MPI multi-threading is supported, users may mix and match Horovod usage with other MPI libraries, such as mpi4py.
Returns
A boolean value indicating whether MPI multi-threading is supported.
horovod.tensorflow.mpi_enabled()
Returns True if MPI is mode is currently enabled at runtime.
If MPI is enabled, users can use it for controller or data transfer operations.
Returns
A boolean value indicating whether MPI is enabled.
horovod.tensorflow.mpi_built()
Returns True if Horovod was compiled with MPI support.
Returns
A boolean value indicating whether MPI support was compiled.
horovod.tensorflow.gloo_enabled()
Returns True if Gloo is mode is currently enabled at runtime.
If Gloo is enabled, users can use it for controller or data transfer operations.
Returns
A boolean value indicating whether Gloo is enabled.
horovod.tensorflow.gloo_built()
Returns True if Horovod was compiled with Gloo support.
Returns
A boolean value indicating whether Gloo support was compiled.
horovod.tensorflow.nccl_built()
Function to check if Horovod was compiled with NCCL support.
Returns
An integer value indicating whether NCCL support was compiled. If NCCL support was compiled, returns NCCL_VERSION_CODE. Otherwise, returns 0.
horovod.tensorflow.ddl_built()
Returns True if Horovod was compiled with DDL support.
Returns
A boolean value indicating whether DDL support was compiled.
horovod.tensorflow.ccl_built()
Returns True if Horovod was compiled with oneCCL support.
Returns
A boolean value indicating whether oneCCL support was compiled.
horovod.tensorflow.cuda_built()
Returns True if Horovod was compiled with CUDA support.
Returns
A boolean value indicating whether CUDA support was compiled.
horovod.tensorflow.rocm_built()
Returns True if Horovod was compiled with ROCm support.
Returns
A boolean value indicating whether ROCm support was compiled.
horovod.tensorflow.allreduce(tensor, average=None, device_dense='', device_sparse='', compression=<class 'horovod.tensorflow.compression.NoneCompressor'>, op=None, prescale_factor=1.0, postscale_factor=1.0, name=None)[source]
Perform an allreduce on a tf.Tensor or tf.IndexedSlices.
This function performs a bandwidth-optimal ring allreduce on the input tensor. If the input is an tf.IndexedSlices, the function instead does an allgather on the values and the indices, effectively doing an allreduce on the represented tensor.
Parameters
• tensor – tf.Tensor, tf.Variable, or tf.IndexedSlices to reduce. The shape of the input must be identical across all ranks.
• average
Warning
Deprecated since version 0.19.0.
Use op instead. Will be removed in v0.21.0.
• device_dense – Device to be used for dense tensors. Uses GPU by default if Horovod was built with HOROVOD_GPU_OPERATIONS.
• device_sparse – Device to be used for sparse tensors. Uses GPU by default if Horovod was built with HOROVOD_GPU_OPERATIONS.
• compression – Compression algorithm used to reduce the amount of data sent and received by each worker node. Defaults to not using compression.
• op – The reduction operation to combine tensors across different ranks. Defaults to Average if None is given.
• prescale_factor – Multiplicative factor to scale tensor before allreduce.
• postscale_factor – Multiplicative factor to scale tensor after allreduce.
• name – A name of the allreduce operation
Returns
A tensor of the same shape and type as tensor, summed across all processes.
horovod.tensorflow.broadcast_global_variables(root_rank)[source]
Broadcasts all global variables from root rank to all other processes.
NOTE: deprecated in TensorFlow 2.0.
Parameters
root_rank – rank of the process from which global variables will be broadcasted to all other processes.
class horovod.tensorflow.BroadcastGlobalVariablesHook(root_rank, device='')[source]
SessionRunHook that will broadcast all global variables from root rank to all other processes during initialization.
This is necessary to ensure consistent initialization of all workers when training is started with random weights or restored from a checkpoint.
NOTE: deprecated in TensorFlow 2.0.
horovod.tensorflow.DistributedOptimizer(optimizer, name=None, use_locking=False, device_dense='', device_sparse='', compression=<class 'horovod.tensorflow.compression.NoneCompressor'>, sparse_as_dense=False, backward_passes_per_step=1, op=<MagicMock name='mock().horovod_reduce_op_average()' id='140118678302560'>, gradient_predivide_factor=1.0)[source]
Construct a new DistributedOptimizer, which uses another optimizer under the hood for computing single-process gradient values and applying gradient updates after the gradient values have been combined across all the Horovod ranks.
Parameters
• optimizer – Optimizer to use for computing gradients and applying updates.
• name – Optional name prefix for the operations created when applying gradients. Defaults to “Distributed” followed by the provided optimizer type.
• use_locking – Whether to use locking when updating variables. See Optimizer.__init__ for more info.
• device_dense – Device to be used for dense tensors. Uses GPU by default if Horovod was built with HOROVOD_GPU_OPERATIONS.
• device_sparse – Device to be used for sparse tensors. Uses GPU by default if Horovod was built with HOROVOD_GPU_OPERATIONS.
• compression – Compression algorithm used during allreduce to reduce the amount of data sent during each parameter update step. Defaults to not using compression.
• sparse_as_dense – Treat all sparse gradients as dense tensors. This can help improve performance and memory utilization if the original sparse gradient has high density. Defaults to false.
• backward_passes_per_step – Number of backward passes to perform before calling hvd.allreduce. This allows accumulating updates over multiple mini-batches before reducing and applying them.
• op – The reduction operation to use when combining gradients across different ranks.
• gradient_predivide_factor – If op == Average, gradient_predivide_factor splits the averaging before and after the sum. Gradients are scaled by 1.0 / gradient_predivide_factor before the sum and gradient_predivide_factor / size after the sum.
horovod.tensorflow.DistributedGradientTape(gradtape, device_dense='', device_sparse='', compression=<class 'horovod.tensorflow.compression.NoneCompressor'>, sparse_as_dense=False, op=<MagicMock name='mock().horovod_reduce_op_average()' id='140118678302560'>, gradient_predivide_factor=1.0)[source]
A tape that wraps another tf.GradientTape, using an allreduce to combine gradient values before applying gradients to model weights.
Parameters
• device_dense – Device to be used for dense tensors. Uses GPU by default if Horovod was built with HOROVOD_GPU_OPERATIONS.
• device_sparse – Device to be used for sparse tensors. Uses GPU by default if Horovod was built with HOROVOD_GPU_OPERATIONS.
• compression – Compression algorithm used during allreduce to reduce the amount of data sent during each parameter update step. Defaults to not using compression.
• sparse_as_dense – Treat all sparse gradients as dense tensors. This can help improve performance and memory utilization if the original sparse gradient has high density. Defaults to false.
• op – The reduction operation to use when combining gradients across different ranks.
• gradient_predivide_factor – If op == Average, gradient_predivide_factor splits the averaging before and after the sum. Gradients are scaled by 1.0 / gradient_predivide_factor before the sum and gradient_predivide_factor / size after the sum.
horovod.tensorflow.elastic.run(func)[source]
Decorator used to run the elastic training process.
The purpose of this decorator is to allow for uninterrupted execution of the wrapped function across multiple workers in parallel, as workers come and go from the system. When a new worker is added, its state needs to be brought to the same point as the other workers, which is done by synchronizing the state object before executing func.
When a worker is added or removed, other workers will raise an exception to bring them back to such a sync point before executing func again. This ensures that workers do not diverge when such reset events occur.
It’s important to note that collective operations (e.g., broadcast, allreduce) cannot be the call to the wrapped function. Otherwise, new workers could execute these operations during their initialization while other workers are attempting to sync state, resulting in deadlock.
Parameters
func – a wrapped function taking any number of args or kwargs. The first argument must be a horovod.common.elastic.State object used to synchronize state across workers.
class horovod.tensorflow.elastic.TensorFlowKerasState(model, optimizer=None, backend=None, **kwargs)[source]
State representation of a TensorFlow Keras model and optimizer.
Supports TensorFlow 2 models and optimizers, as well as keras and tf.keras.
Parameters
• model – TensorFlow Keras model.
• optimizer – Optional optimizer, can be compiled into model instead.
• backend – For TensorFlow v1, backend used by Keras for obtaining the session.
• kwargs – Additional properties to sync, will be exposed as attributes of the object.
save()[source]
Saves state to host memory.
restore()[source]
Restores the last committed state, undoing any uncommitted modifications.
sync()[source]
Synchronize state across workers.
class horovod.tensorflow.elastic.TensorFlowState(variables=None, session=None, **kwargs)[source]
State representation of a list of TensorFlow variables.
Supports both TensorFlow v1 and v2. For TensorFlow v2, can only be used when eager execution is enabled.
Parameters
• variables – List of tf.Variable objects to track (default: tf.global_variables()).
• session – For TensorFlow v1, session used to materialize variables (default: ops.get_default_session()).
• kwargs – Additional properties to sync, will be exposed as attributes of the object.
save()[source]
Saves state to host memory.
restore()[source]
Restores the last committed state, undoing any uncommitted modifications.
sync()[source]
Synchronize state across workers.
## horovod.tensorflow.keras¶
horovod.tensorflow.keras.init(comm=None)
A function that initializes Horovod.
Parameters
comm – List specifying ranks for the communicator, relative to the MPI_COMM_WORLD communicator OR the MPI communicator to use. Given communicator will be duplicated. If None, Horovod will use MPI_COMM_WORLD Communicator.
horovod.tensorflow.keras.shutdown()
A function that shuts Horovod down.
horovod.tensorflow.keras.is_initialized()
Returns True if Horovod is initialized
horovod.tensorflow.keras.start_timeline(file_path, mark_cycles=False)
Creates a timeline file at file_path and begins recording.
Parameters
• file_path – String path to the timeline file.
• mark_cycles – Boolean indicating that cycles should be marked on the timeline (default: False).
Raises a ValueError if Horovod is not initialized.
horovod.tensorflow.keras.stop_timeline()
Stops the active timeline recording and closes the file.
Raises a ValueError if Horovod is not initialized.
horovod.tensorflow.keras.size()
A function that returns the number of Horovod processes.
Returns
An integer scalar containing the number of Horovod processes.
horovod.tensorflow.keras.local_size()
A function that returns the number of Horovod processes within the node the current process is running on.
Returns
An integer scalar containing the number of local Horovod processes.
horovod.tensorflow.keras.rank()
A function that returns the Horovod rank of the calling process.
Returns
An integer scalar with the Horovod rank of the calling process.
horovod.tensorflow.keras.local_rank()
A function that returns the local Horovod rank of the calling process, within the node that it is running on. For example, if there are seven processes running on a node, their local ranks will be zero through six, inclusive.
Returns
An integer scalar with the local Horovod rank of the calling process.
horovod.tensorflow.keras.mpi_threads_supported()
A function that returns a flag indicating whether MPI multi-threading is supported.
If MPI multi-threading is supported, users may mix and match Horovod usage with other MPI libraries, such as mpi4py.
Returns
A boolean value indicating whether MPI multi-threading is supported.
horovod.tensorflow.keras.mpi_enabled()
Returns True if MPI is mode is currently enabled at runtime.
If MPI is enabled, users can use it for controller or data transfer operations.
Returns
A boolean value indicating whether MPI is enabled.
horovod.tensorflow.keras.mpi_built()
Returns True if Horovod was compiled with MPI support.
Returns
A boolean value indicating whether MPI support was compiled.
horovod.tensorflow.keras.gloo_enabled()
Returns True if Gloo is mode is currently enabled at runtime.
If Gloo is enabled, users can use it for controller or data transfer operations.
Returns
A boolean value indicating whether Gloo is enabled.
horovod.tensorflow.keras.gloo_built()
Returns True if Horovod was compiled with Gloo support.
Returns
A boolean value indicating whether Gloo support was compiled.
horovod.tensorflow.keras.nccl_built()
Function to check if Horovod was compiled with NCCL support.
Returns
An integer value indicating whether NCCL support was compiled. If NCCL support was compiled, returns NCCL_VERSION_CODE. Otherwise, returns 0.
horovod.tensorflow.keras.ddl_built()
Returns True if Horovod was compiled with DDL support.
Returns
A boolean value indicating whether DDL support was compiled.
horovod.tensorflow.keras.ccl_built()
Returns True if Horovod was compiled with oneCCL support.
Returns
A boolean value indicating whether oneCCL support was compiled.
horovod.tensorflow.keras.cuda_built()
Returns True if Horovod was compiled with CUDA support.
Returns
A boolean value indicating whether CUDA support was compiled.
horovod.tensorflow.keras.rocm_built()
Returns True if Horovod was compiled with ROCm support.
Returns
A boolean value indicating whether ROCm support was compiled.
class horovod.tensorflow.keras.Compression[source]
Optional gradient compression algorithm used during allreduce.
none
Compress all floating point gradients to 16-bit.
alias of NoneCompressor
fp16
alias of FP16Compressor
horovod.tensorflow.keras.DistributedOptimizer(optimizer, name=None, device_dense='', device_sparse='', compression=<class 'horovod.tensorflow.compression.NoneCompressor'>, sparse_as_dense=False, gradient_predivide_factor=1.0)[source]
An optimizer that wraps another keras.optimizers.Optimizer, using an allreduce to average gradient values before applying gradients to model weights.
Parameters
• optimizer – Optimizer to use for computing gradients and applying updates.
• name – Optional name prefix for the operations created when applying gradients. Defaults to “Distributed” followed by the provided optimizer type.
• device_dense – Device to be used for dense tensors. Uses GPU by default if Horovod was build with HOROVOD_GPU_OPERATIONS.
• device_sparse – Device to be used for sparse tensors. Uses GPU by default if Horovod was build with HOROVOD_GPU_OPERATIONS.
• compression – Compression algorithm used to reduce the amount of data sent and received by each worker node. Defaults to not using compression.
• sparse_as_dense – Treat all sparse gradients as dense tensors. This can help improve performance and memory utilization if the original sparse gradient has high density. Defaults to false.
• gradient_predivide_factor – gradient_predivide_factor splits the averaging before and after the sum. Gradients are scaled by 1.0 / gradient_predivide_factor before the sum and gradient_predivide_factor / size after the sum.
horovod.tensorflow.keras.broadcast_global_variables(root_rank)[source]
Broadcasts all global variables from root rank to all other processes.
Parameters
root_rank – Rank of the process from which global variables will be broadcasted to all other processes.
horovod.tensorflow.keras.allreduce(value, name=None, average=True, prescale_factor=1.0, postscale_factor=1.0)[source]
Perform an allreduce on a tensor-compatible value.
Parameters
• value – A tensor-compatible value to reduce. The shape of the input must be identical across all ranks.
• name – Optional name for the constants created by this operation.
• average – If True, computes the average over all ranks. Otherwise, computes the sum over all ranks.
• prescale_factor – Multiplicative factor to scale tensor before allreduce.
• postscale_factor – Multiplicative factor to scale tensor after allreduce.
horovod.tensorflow.keras.allgather(value, name=None)[source]
Perform an allgather on a tensor-compatible value.
The concatenation is done on the first dimension, so the input values on the different processes must have the same rank and shape, except for the first dimension, which is allowed to be different.
Parameters
• value – A tensor-compatible value to gather.
• name – Optional name prefix for the constants created by this operation.
horovod.tensorflow.keras.broadcast(value, root_rank, name=None)[source]
Perform a broadcast on a tensor-compatible value.
Parameters
• value – A tensor-compatible value to reduce. The shape of the input must be identical across all ranks.
• root_rank – Rank of the process from which global variables will be broadcasted to all other processes.
• name – Optional name for the constants created by this operation.
horovod.tensorflow.keras.load_model(filepath, custom_optimizers=None, custom_objects=None, compression=<class 'horovod.tensorflow.compression.NoneCompressor'>)[source]
Loads a saved Keras model with a Horovod DistributedOptimizer.
The DistributedOptimizer will wrap the underlying optimizer used to train the saved model, so that the optimizer state (params and weights) will be picked up for retraining.
By default, all optimizers in the module keras.optimizers will be loaded and wrapped without needing to specify any custom_optimizers or custom_objects.
Parameters
• filepath – One of the following: - string, path to the saved model, or - h5py.File object from which to load the model
• custom_optimizers – Optional list of Optimizer subclasses to support during loading.
• custom_objects – Optional dictionary mapping names (strings) to custom classes or functions to be considered during deserialization.
• compression – Compression algorithm used to reduce the amount of data sent and received by each worker node. Defaults to not using compression.
Returns
A Keras model instance.
Raises
• ImportError – If h5py is not available.
• ValueError – In case of an invalid savefile.
class horovod.tensorflow.keras.callbacks.BroadcastGlobalVariablesCallback(root_rank, device='')[source]
Keras Callback that will broadcast all global variables from root rank to all other processes during initialization.
This is necessary to ensure consistent initialization of all workers when training is started with random weights or restored from a checkpoint.
__init__(root_rank, device='')[source]
Construct a new BroadcastGlobalVariablesCallback that will broadcast all global variables from root rank to all other processes during initialization.
Parameters
• root_rank – Rank that will send data, other ranks will receive data.
• device – Device to be used for broadcasting. Uses GPU by default if Horovod was build with HOROVOD_GPU_OPERATIONS.
class horovod.tensorflow.keras.callbacks.MetricAverageCallback(device='')[source]
Keras Callback that will average metrics across all processes at the end of the epoch. Useful in conjuction with ReduceLROnPlateau, TensorBoard and other metrics-based callbacks.
Note: This callback must be added to the callback list before the ReduceLROnPlateau, TensorBoard or other metrics-based callbacks.
__init__(device='')[source]
Construct a new MetricAverageCallback that will average metrics across all processes at the end of the epoch.
Parameters
device – Device to be used for allreduce. Uses GPU by default if Horovod was build with HOROVOD_GPU_OPERATIONS.
class horovod.tensorflow.keras.callbacks.LearningRateScheduleCallback(multiplier, start_epoch=0, end_epoch=None, staircase=True, momentum_correction=True, steps_per_epoch=None, initial_lr=None)[source]
LearningRateScheduleCallback sets learning rate between epochs start_epoch and end_epoch to be initial_lr * multiplier. multiplier can be a constant or a function f(epoch) = lr’.
If multiplier is a function and staircase=True, learning rate adjustment will happen at the beginning of each epoch and the epoch passed to the multiplier function will be an integer.
If multiplier is a function and staircase=False, learning rate adjustment will happen at the beginning of each batch and the epoch passed to the multiplier function will be a floating number: epoch’ = epoch + batch / steps_per_epoch. This functionality is useful for smooth learning rate adjustment schedulers, such as LearningRateWarmupCallback.
initial_lr is the learning rate of the model optimizer at the start of the training.
__init__(multiplier, start_epoch=0, end_epoch=None, staircase=True, momentum_correction=True, steps_per_epoch=None, initial_lr=None)[source]
Construct a new LearningRateScheduleCallback.
Parameters
• multiplier – A constant multiplier or a function f(epoch) = lr’
• start_epoch – The first epoch this adjustment will be applied to. Defaults to 0.
• end_epoch – The epoch this adjustment will stop applying (exclusive end). Defaults to None.
• staircase – Whether to adjust learning rate at the start of epoch (staircase=True) or at the start of every batch (staircase=False).
• momentum_correction – Apply momentum correction to optimizers that have momentum. Defaults to True.
• steps_per_epoch – The callback will attempt to autodetect number of batches per epoch with Keras >= 2.0.0. Provide this value if you have an older version of Keras.
• initial_lr
Initial learning rate at the start of training.
Warning
Will be required in v0.21.0.
class horovod.tensorflow.keras.callbacks.LearningRateWarmupCallback(warmup_epochs=5, momentum_correction=True, steps_per_epoch=None, verbose=0, initial_lr=None)[source]
lr = initial_lr / hvd.size() —> lr = initial_lr
initial_lr is the learning rate of the model optimizer at the start of the training.
This technique was described in the paper “Accurate, Large Minibatch SGD: Training ImageNet in 1 Hour”. See https://arxiv.org/pdf/1706.02677.pdf for details.
Math recap:
\begin{align}\begin{aligned}epoch &= full\_epochs + \frac{batch}{steps\_per\_epoch}\\lr'(epoch) &= \frac{lr}{size} * (\frac{size - 1}{warmup} * epoch + 1)\\lr'(epoch = 0) &= \frac{lr}{size}\\lr'(epoch = warmup) &= lr\end{aligned}\end{align}
__init__(warmup_epochs=5, momentum_correction=True, steps_per_epoch=None, verbose=0, initial_lr=None)[source]
Construct a new LearningRateWarmupCallback that will gradually warm up the learning rate.
Parameters
• warmup_epochs – The number of epochs of the warmup phase. Defaults to 5.
• momentum_correction – Apply momentum correction to optimizers that have momentum. Defaults to True.
• steps_per_epoch – The callback will attempt to autodetect number of batches per epoch with Keras >= 2.0.0. Provide this value if you have an older version of Keras.
• verbose – verbosity mode, 0 or 1.
• initial_lr
Initial learning rate at the start of training.
Warning
Will be required in v0.21.0.
horovod.tensorflow.keras.elastic.run(func)[source]
Decorator used to run the elastic training process.
The purpose of this decorator is to allow for uninterrupted execution of the wrapped function across multiple workers in parallel, as workers come and go from the system. When a new worker is added, its state needs to be brought to the same point as the other workers, which is done by synchronizing the state object before executing func.
When a worker is added or removed, other workers will raise an exception to bring them back to such a sync point before executing func again. This ensures that workers do not diverge when such reset events occur.
It’s important to note that collective operations (e.g., broadcast, allreduce) cannot be the call to the wrapped function. Otherwise, new workers could execute these operations during their initialization while other workers are attempting to sync state, resulting in deadlock.
Parameters
func – a wrapped function taking any number of args or kwargs. The first argument must be a horovod.common.elastic.State object used to synchronize state across workers.
class horovod.tensorflow.keras.elastic.KerasState(model, optimizer=None, **kwargs)[source]
State representation of a tf.keras model and optimizer.
Parameters
• model – Keras model.
• optimizer – Optional optimizer, can be compiled into model instead.
• kwargs – Additional properties to sync, will be exposed as attributes of the object.
class horovod.tensorflow.keras.elastic.CommitStateCallback(state, batches_per_commit=1)[source]
Keras Callback that will commit the state object every batches_per_commit batches at the end of each batch.
class horovod.tensorflow.keras.elastic.UpdateBatchStateCallback(state)[source]
Keras Callback that will update the value of state.batch with the current batch number at the end of each batch. Batch will reset to 0 at the end of each epoch.
If steps_per_epoch is set, then this callback will also ensure that the number of steps in the first epoch following a reset is shortened by the number of batches already processed.
class horovod.tensorflow.keras.elastic.UpdateEpochStateCallback(state)[source]
Keras Callback that will update the value of state.epoch with the current epoch number at the end of each epoch.
## horovod.keras¶
horovod.keras.init(comm=None)
A function that initializes Horovod.
Parameters
comm – List specifying ranks for the communicator, relative to the MPI_COMM_WORLD communicator OR the MPI communicator to use. Given communicator will be duplicated. If None, Horovod will use MPI_COMM_WORLD Communicator.
horovod.keras.shutdown()
A function that shuts Horovod down.
horovod.keras.size()
A function that returns the number of Horovod processes.
Returns
An integer scalar containing the number of Horovod processes.
horovod.keras.is_initialized()
Returns True if Horovod is initialized
horovod.keras.start_timeline(file_path, mark_cycles=False)
Creates a timeline file at file_path and begins recording.
Parameters
• file_path – String path to the timeline file.
• mark_cycles – Boolean indicating that cycles should be marked on the timeline (default: False).
Raises a ValueError if Horovod is not initialized.
horovod.keras.stop_timeline()
Stops the active timeline recording and closes the file.
Raises a ValueError if Horovod is not initialized.
horovod.keras.local_size()
A function that returns the number of Horovod processes within the node the current process is running on.
Returns
An integer scalar containing the number of local Horovod processes.
horovod.keras.rank()
A function that returns the Horovod rank of the calling process.
Returns
An integer scalar with the Horovod rank of the calling process.
horovod.keras.local_rank()
A function that returns the local Horovod rank of the calling process, within the node that it is running on. For example, if there are seven processes running on a node, their local ranks will be zero through six, inclusive.
Returns
An integer scalar with the local Horovod rank of the calling process.
horovod.keras.mpi_threads_supported()
A function that returns a flag indicating whether MPI multi-threading is supported.
If MPI multi-threading is supported, users may mix and match Horovod usage with other MPI libraries, such as mpi4py.
Returns
A boolean value indicating whether MPI multi-threading is supported.
horovod.keras.mpi_enabled()
Returns True if MPI is mode is currently enabled at runtime.
If MPI is enabled, users can use it for controller or data transfer operations.
Returns
A boolean value indicating whether MPI is enabled.
horovod.keras.mpi_built()
Returns True if Horovod was compiled with MPI support.
Returns
A boolean value indicating whether MPI support was compiled.
horovod.keras.gloo_enabled()
Returns True if Gloo is mode is currently enabled at runtime.
If Gloo is enabled, users can use it for controller or data transfer operations.
Returns
A boolean value indicating whether Gloo is enabled.
horovod.keras.gloo_built()
Returns True if Horovod was compiled with Gloo support.
Returns
A boolean value indicating whether Gloo support was compiled.
horovod.keras.nccl_built()
Function to check if Horovod was compiled with NCCL support.
Returns
An integer value indicating whether NCCL support was compiled. If NCCL support was compiled, returns NCCL_VERSION_CODE. Otherwise, returns 0.
horovod.keras.ddl_built()
Returns True if Horovod was compiled with DDL support.
Returns
A boolean value indicating whether DDL support was compiled.
horovod.keras.ccl_built()
Returns True if Horovod was compiled with oneCCL support.
Returns
A boolean value indicating whether oneCCL support was compiled.
horovod.keras.cuda_built()
Returns True if Horovod was compiled with CUDA support.
Returns
A boolean value indicating whether CUDA support was compiled.
horovod.keras.rocm_built()
Returns True if Horovod was compiled with ROCm support.
Returns
A boolean value indicating whether ROCm support was compiled.
class horovod.keras.Compression[source]
Optional gradient compression algorithm used during allreduce.
none
Compress all floating point gradients to 16-bit.
alias of NoneCompressor
fp16
alias of FP16Compressor
horovod.keras.DistributedOptimizer(optimizer, name=None, device_dense='', device_sparse='', compression=<class 'horovod.tensorflow.compression.NoneCompressor'>, sparse_as_dense=False, gradient_predivide_factor=1.0)[source]
An optimizer that wraps another keras.optimizers.Optimizer, using an allreduce to average gradient values before applying gradients to model weights.
Parameters
• optimizer – Optimizer to use for computing gradients and applying updates.
• name – Optional name prefix for the operations created when applying gradients. Defaults to “Distributed” followed by the provided optimizer type.
• device_dense – Device to be used for dense tensors. Uses GPU by default if Horovod was build with HOROVOD_GPU_OPERATIONS.
• device_sparse – Device to be used for sparse tensors. Uses GPU by default if Horovod was build with HOROVOD_GPU_OPERATIONS.
• compression – Compression algorithm used to reduce the amount of data sent and received by each worker node. Defaults to not using compression.
• sparse_as_dense – Treat all sparse gradients as dense tensors. This can help improve performance and memory utilization if the original sparse gradient has high density. Defaults to false.
• gradient_predivide_factor – gradient_predivide_factor splits the averaging before and after the sum. Gradients are scaled by 1.0 / gradient_predivide_factor before the sum and gradient_predivide_factor / size after the sum.
horovod.keras.broadcast_global_variables(root_rank)[source]
Broadcasts all global variables from root rank to all other processes.
Parameters
root_rank – Rank of the process from which global variables will be broadcasted to all other processes.
horovod.keras.allreduce(value, name=None, average=True, prescale_factor=1.0, postscale_factor=1.0)[source]
Perform an allreduce on a tensor-compatible value.
Parameters
• value – A tensor-compatible value to reduce. The shape of the input must be identical across all ranks.
• name – Optional name for the constants created by this operation.
• average – If True, computes the average over all ranks. Otherwise, computes the sum over all ranks.
• prescale_factor – Multiplicative factor to scale tensor before allreduce.
• postscale_factor – Multiplicative factor to scale tensor after allreduce.
horovod.keras.allgather(value, name=None)[source]
Perform an allgather on a tensor-compatible value.
The concatenation is done on the first dimension, so the input values on the different processes must have the same rank and shape, except for the first dimension, which is allowed to be different.
Parameters
• value – A tensor-compatible value to gather.
• name – Optional name prefix for the constants created by this operation.
horovod.keras.broadcast(value, root_rank, name=None)[source]
Perform a broadcast on a tensor-compatible value.
Parameters
• value – A tensor-compatible value to reduce. The shape of the input must be identical across all ranks.
• root_rank – Rank of the process from which global variables will be broadcasted to all other processes.
• name – Optional name for the constants created by this operation.
horovod.keras.load_model(filepath, custom_optimizers=None, custom_objects=None, compression=<class 'horovod.tensorflow.compression.NoneCompressor'>)[source]
Loads a saved Keras model with a Horovod DistributedOptimizer.
The DistributedOptimizer will wrap the underlying optimizer used to train the saved model, so that the optimizer state (params and weights) will be picked up for retraining.
By default, all optimizers in the module keras.optimizers will be loaded and wrapped without needing to specify any custom_optimizers or custom_objects.
Parameters
• filepath – One of the following: - string, path to the saved model, or - h5py.File object from which to load the model
• custom_optimizers – Optional list of Optimizer subclasses to support during loading.
• custom_objects – Optional dictionary mapping names (strings) to custom classes or functions to be considered during deserialization.
• compression – Compression algorithm used to reduce the amount of data sent and received by each worker node. Defaults to not using compression.
Returns
A Keras model instance.
Raises
• ImportError – If h5py is not available.
• ValueError – In case of an invalid savefile.
class horovod.keras.callbacks.BroadcastGlobalVariablesCallback(root_rank, device='')[source]
Keras Callback that will broadcast all global variables from root rank to all other processes during initialization.
This is necessary to ensure consistent initialization of all workers when training is started with random weights or restored from a checkpoint.
__init__(root_rank, device='')[source]
Construct a new BroadcastGlobalVariablesCallback that will broadcast all global variables from root rank to all other processes during initialization.
Parameters
• root_rank – Rank that will send data, other ranks will receive data.
• device – Device to be used for broadcasting. Uses GPU by default if Horovod was build with HOROVOD_GPU_OPERATIONS.
class horovod.keras.callbacks.MetricAverageCallback(device='')[source]
Keras Callback that will average metrics across all processes at the end of the epoch. Useful in conjuction with ReduceLROnPlateau, TensorBoard and other metrics-based callbacks.
Note: This callback must be added to the callback list before the ReduceLROnPlateau, TensorBoard or other metrics-based callbacks.
__init__(device='')[source]
Construct a new MetricAverageCallback that will average metrics across all processes at the end of the epoch.
Parameters
device – Device to be used for allreduce. Uses GPU by default if Horovod was build with HOROVOD_GPU_OPERATIONS.
class horovod.keras.callbacks.LearningRateScheduleCallback(multiplier, start_epoch=0, end_epoch=None, staircase=True, momentum_correction=True, steps_per_epoch=None, initial_lr=None)[source]
LearningRateScheduleCallback sets learning rate between epochs start_epoch and end_epoch to be initial_lr * multiplier. multiplier can be a constant or a function f(epoch) = lr’.
If multiplier is a function and staircase=True, learning rate adjustment will happen at the beginning of each epoch and the epoch passed to the multiplier function will be an integer.
If multiplier is a function and staircase=False, learning rate adjustment will happen at the beginning of each batch and the epoch passed to the multiplier function will be a floating number: epoch’ = epoch + batch / steps_per_epoch. This functionality is useful for smooth learning rate adjustment schedulers, such as LearningRateWarmupCallback.
initial_lr is the learning rate of the model optimizer at the start of the training.
__init__(multiplier, start_epoch=0, end_epoch=None, staircase=True, momentum_correction=True, steps_per_epoch=None, initial_lr=None)[source]
Construct a new LearningRateScheduleCallback.
Parameters
• multiplier – A constant multiplier or a function f(epoch) = lr’
• start_epoch – The first epoch this adjustment will be applied to. Defaults to 0.
• end_epoch – The epoch this adjustment will stop applying (exclusive end). Defaults to None.
• staircase – Whether to adjust learning rate at the start of epoch (staircase=True) or at the start of every batch (staircase=False).
• momentum_correction – Apply momentum correction to optimizers that have momentum. Defaults to True.
• steps_per_epoch – The callback will attempt to autodetect number of batches per epoch with Keras >= 2.0.0. Provide this value if you have an older version of Keras.
• initial_lr
Initial learning rate at the start of training.
Warning
Will be required in v0.21.0.
class horovod.keras.callbacks.LearningRateWarmupCallback(warmup_epochs=5, momentum_correction=True, steps_per_epoch=None, verbose=0, initial_lr=None)[source]
lr = initial_lr / hvd.size() —> lr = initial_lr
initial_lr is the learning rate of the model optimizer at the start of the training.
This technique was described in the paper “Accurate, Large Minibatch SGD: Training ImageNet in 1 Hour”. See https://arxiv.org/pdf/1706.02677.pdf for details.
Math recap:
\begin{align}\begin{aligned}epoch &= full\_epochs + \frac{batch}{steps\_per\_epoch}\\lr'(epoch) &= \frac{lr}{size} * (\frac{size - 1}{warmup} * epoch + 1)\\lr'(epoch = 0) &= \frac{lr}{size}\\lr'(epoch = warmup) &= lr\end{aligned}\end{align}
__init__(warmup_epochs=5, momentum_correction=True, steps_per_epoch=None, verbose=0, initial_lr=None)[source]
Construct a new LearningRateWarmupCallback that will gradually warm up the learning rate.
Parameters
• warmup_epochs – The number of epochs of the warmup phase. Defaults to 5.
• momentum_correction – Apply momentum correction to optimizers that have momentum. Defaults to True.
• steps_per_epoch – The callback will attempt to autodetect number of batches per epoch with Keras >= 2.0.0. Provide this value if you have an older version of Keras.
• verbose – verbosity mode, 0 or 1.
• initial_lr
Initial learning rate at the start of training.
Warning
Will be required in v0.21.0.
horovod.keras.elastic.run(func)[source]
Decorator used to run the elastic training process.
The purpose of this decorator is to allow for uninterrupted execution of the wrapped function across multiple workers in parallel, as workers come and go from the system. When a new worker is added, its state needs to be brought to the same point as the other workers, which is done by synchronizing the state object before executing func.
When a worker is added or removed, other workers will raise an exception to bring them back to such a sync point before executing func again. This ensures that workers do not diverge when such reset events occur.
It’s important to note that collective operations (e.g., broadcast, allreduce) cannot be the call to the wrapped function. Otherwise, new workers could execute these operations during their initialization while other workers are attempting to sync state, resulting in deadlock.
Parameters
func – a wrapped function taking any number of args or kwargs. The first argument must be a horovod.common.elastic.State object used to synchronize state across workers.
class horovod.keras.elastic.KerasState(model, optimizer=None, **kwargs)[source]
State representation of a keras model and optimizer.
Parameters
• model – Keras model.
• optimizer – Optional optimizer, can be compiled into model instead.
• kwargs – Additional properties to sync, will be exposed as attributes of the object.
class horovod.keras.elastic.CommitStateCallback(state, batches_per_commit=1)[source]
Keras Callback that will commit the state object every batches_per_commit batches at the end of each batch.
class horovod.keras.elastic.UpdateBatchStateCallback(state)[source]
Keras Callback that will update the value of state.batch with the current batch number at the end of each batch. Batch will reset to 0 at the end of each epoch.
If steps_per_epoch is set, then this callback will also ensure that the number of steps in the first epoch following a reset is shortened by the number of batches already processed.
class horovod.keras.elastic.UpdateEpochStateCallback(state)[source]
Keras Callback that will update the value of state.epoch with the current epoch number at the end of each epoch.
## horovod.torch¶
class horovod.torch.Compression[source]
Optional gradient compression algorithm used during allreduce.
none
Compress all floating point gradients to 16-bit.
alias of NoneCompressor
fp16
alias of FP16Compressor
horovod.torch.allgather_object(obj, name=None)[source]
Serializes and allgathers an object from all other processes.
Parameters
• obj – An object capable of being serialized without losing any context.
• name – Optional name to use during allgather, will default to the class type.
Returns
The list of objects that were allgathered across all ranks.
horovod.torch.broadcast_object(obj, root_rank=0, name=None)[source]
Serializes and broadcasts an object from root rank to all other processes. Typical usage is to broadcast the optimizer.state_dict(), for example:
state_dict = broadcast_object(optimizer.state_dict(), 0)
if hvd.rank() > 0:
Parameters
• obj – An object capable of being serialized without losing any context.
• root_rank – The rank of the process from which parameters will be broadcasted to all other processes.
• name – Optional name to use during broadcast, will default to the class type.
Returns
The object that was broadcast from the root_rank.
horovod.torch.broadcast_optimizer_state(optimizer, root_rank)[source]
Broadcasts an optimizer state from root rank to all other processes.
Parameters
• optimizer – An optimizer.
• root_rank – The rank of the process from which the optimizer will be broadcasted to all other processes.
horovod.torch.broadcast_parameters(params, root_rank)[source]
Broadcasts the parameters from root rank to all other processes. Typical usage is to broadcast the model.state_dict(), model.named_parameters(), or model.parameters().
Parameters
• params – One of the following: - list of parameters to broadcast - dict of parameters to broadcast
• root_rank – The rank of the process from which parameters will be broadcasted to all other processes.
horovod.torch.allreduce(tensor, average=None, name=None, compression=<class 'horovod.torch.compression.NoneCompressor'>, op=None, prescale_factor=1.0, postscale_factor=1.0)[source]
A function that performs averaging or summation of the input tensor over all the Horovod processes. The input tensor is not modified.
The reduction operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The reduction will not start until all processes are ready to send and receive the tensor.
This acts as a thin wrapper around an autograd function. If your input tensor requires gradients, then callings this function will allow gradients to be computed and backpropagated.
Parameters
• tensor – A tensor to reduce.
• average
Warning
Deprecated since version 0.19.0.
Use op instead. Will be removed in v0.21.0.
• name – A name of the reduction operation.
• compression – Compression algorithm used during allreduce to reduce the amount of data sent during the each parameter update step. Defaults to not using compression.
• op – The reduction operation to combine tensors across different ranks. Defaults to Average if None is given.
• prescale_factor – Multiplicative factor to scale tensor before allreduce.
• postscale_factor – Multiplicative factor to scale tensor after allreduce.
Returns
A tensor of the same shape and type as tensor, averaged or summed across all processes.
horovod.torch.allreduce_async(tensor, average=None, name=None, op=None, prescale_factor=1.0, postscale_factor=1.0)[source]
A function that performs asynchronous averaging or summation of the input tensor over all the Horovod processes. The input tensor is not modified.
The reduction operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The reduction will not start until all processes are ready to send and receive the tensor.
Parameters
• tensor – A tensor to reduce.
• average
Warning
Deprecated since version 0.19.0.
Use op instead. Will be removed in v0.21.0.
• name – A name of the reduction operation.
• op – The reduction operation to combine tensors across different ranks. Defaults to Average if None is given.
• prescale_factor – Multiplicative factor to scale tensor before allreduce.
• postscale_factor – Multiplicative factor to scale tensor after allreduce.
Returns
A handle to the allreduce operation that can be used with poll() or synchronize().
horovod.torch.allreduce_(tensor, average=None, name=None, op=None, prescale_factor=1.0, postscale_factor=1.0)[source]
A function that performs in-place averaging or summation of the input tensor over all the Horovod processes.
The reduction operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The reduction will not start until all processes are ready to send and receive the tensor.
Parameters
• tensor – A tensor to reduce.
• average
Warning
Deprecated since version 0.19.0.
Use op instead. Will be removed in v0.21.0.
• name – A name of the reduction operation.
• op – The reduction operation to combine tensors across different ranks. Defaults to Average if None is given.
• prescale_factor – Multiplicative factor to scale tensor before allreduce.
• postscale_factor – Multiplicative factor to scale tensor after allreduce.
Returns
A tensor of the same shape and type as tensor, averaged or summed across all processes.
horovod.torch.allreduce_async_(tensor, average=None, name=None, op=None, prescale_factor=1.0, postscale_factor=1.0)[source]
A function that performs asynchronous in-place averaging or summation of the input tensor over all the Horovod processes.
The reduction operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The reduction will not start until all processes are ready to send and receive the tensor.
Parameters
• tensor – A tensor to reduce.
• average
Warning
Deprecated since version 0.19.0.
Use op instead. Will be removed in v0.21.0.
• name – A name of the reduction operation.
• op – The reduction operation to combine tensors across different ranks. Defaults to Average if None is given.
• prescale_factor – Multiplicative factor to scale tensor before allreduce.
• postscale_factor – Multiplicative factor to scale tensor after allreduce.
Returns
A handle to the allreduce operation that can be used with poll() or synchronize().
horovod.torch.allgather(tensor, name=None)[source]
A function that concatenates the input tensor with the same input tensor on all other Horovod processes. The input tensor is not modified.
The concatenation is done on the first dimension, so the input tensors on the different processes must have the same rank and shape, except for the first dimension, which is allowed to be different.
This acts as a thin wrapper around an autograd function. If your input tensor requires gradients, then callings this function will allow gradients to be computed and backpropagated.
Parameters
• tensor – A tensor to allgather.
• name – A name of the allgather operation.
Returns
A tensor of the same type as tensor, concatenated on dimension zero across all processes. The shape is identical to the input shape, except for the first dimension, which may be greater and is the sum of all first dimensions of the tensors in different Horovod processes.
horovod.torch.allgather_async(tensor, name=None)[source]
A function that asynchronously concatenates the input tensor with the same input tensor on all other Horovod processes. The input tensor is not modified.
The concatenation is done on the first dimension, so the input tensors on the different processes must have the same rank and shape, except for the first dimension, which is allowed to be different.
Parameters
• tensor – A tensor to allgather.
• name – A name of the allgather operation.
Returns
A handle to the allgather operation that can be used with poll() or synchronize().
horovod.torch.broadcast(tensor, root_rank, name=None)[source]
A function that broadcasts the input tensor on root rank to the same input tensor on all other Horovod processes. The input tensor is not modified.
The broadcast operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The broadcast will not start until all processes are ready to send and receive the tensor.
This acts as a thin wrapper around an autograd function. If your input tensor requires gradients, then callings this function will allow gradients to be computed and backpropagated.
Parameters
• tensor – A tensor to broadcast.
• root_rank – The rank to broadcast the value from.
• name – A name of the broadcast operation.
Returns
A tensor of the same shape and type as tensor, with the value broadcasted from root rank.
horovod.torch.broadcast_async(tensor, root_rank, name=None)[source]
A function that asynchronously broadcasts the input tensor on root rank to the same input tensor on all other Horovod processes. The input tensor is not modified.
The broadcast operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The broadcast will not start until all processes are ready to send and receive the tensor.
Parameters
• tensor – A tensor to broadcast.
• root_rank – The rank to broadcast the value from.
• name – A name of the broadcast operation.
Returns
A handle to the broadcast operation that can be used with poll() or synchronize().
horovod.torch.broadcast_(tensor, root_rank, name=None)[source]
A function that broadcasts the input tensor on root rank to the same input tensor on all other Horovod processes. The operation is performed in-place.
The broadcast operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The broadcast will not start until all processes are ready to send and receive the tensor.
Parameters
• tensor – A tensor to broadcast.
• root_rank – The rank to broadcast the value from.
• name – A name of the broadcast operation.
Returns
A tensor of the same shape and type as tensor, with the value broadcasted from root rank.
horovod.torch.broadcast_async_(tensor, root_rank, name=None)[source]
A function that asynchronously broadcasts the input tensor on root rank to the same input tensor on all other Horovod processes. The operation is performed in-place.
The broadcast operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The broadcast will not start until all processes are ready to send and receive the tensor.
Parameters
• tensor – A tensor to broadcast.
• root_rank – The rank to broadcast the value from.
• name – A name of the broadcast operation.
Returns
A handle to the broadcast operation that can be used with poll() or synchronize().
horovod.torch.alltoall(tensor, splits=None, name=None)[source]
A function that scatters slices of the input tensor to all other Horovod processes and returns a tensor of gathered slices from all other Horovod processes. The input tensor is not modified.
The slicing is done on the first dimension, so the input tensors on the different processes must have the same rank and shape, except for the first dimension, which is allowed to be different.
This acts as a thin wrapper around an autograd function. If your input tensor requires gradients, then callings this function will allow gradients to be computed and backpropagated.
Parameters
• tensor – A tensor to distribute with alltoall.
• splits – A tensor of integers in rank order describing how many elements in tensor to send to each worker. Splitting is applied along the first dimension of tensor. If splits is not provided, the first dimension is split equally by the number of Horovod processes.
• name – A name of the alltoall operation.
Returns
A tensor containing the gathered tensor data from all workers.
horovod.torch.alltoall_async(tensor, splits=None, name=None)[source]
A function that scatters slices of the input tensor to all other Horovod processes and returns a tensor of gathered slices from all other Horovod processes. The input tensor is not modified.
The slicing is done on the first dimension, so the input tensors on the different processes must have the same rank and shape, except for the first dimension, which is allowed to be different.
Parameters
• tensor – A tensor to distribute with alltoall.
• splits – A tensor of integers in rank order describing how many elements in tensor to send to each worker. Splitting is applied along the first dimension of tensor. If splits is not provided, the first dimension is split equally by the number of Horovod processes.
• name – A name of the alltoall operation.
Returns
A handle to the alltoall operation that can be used with poll() or synchronize().
horovod.torch.join(device=-1)[source]
A function that indicates that the rank finished processing data.
All ranks that did not call join() continue to process allreduce operations. This function blocks Python thread until all ranks join.
Parameters
device – An id of the device to create temprorary zero tensors (default -1, CPU)
Returns
Id of the rank that joined last.
horovod.torch.poll(handle)[source]
Polls an allreduce, allgather or broadcast handle to determine whether underlying asynchronous operation has completed. After poll() returns True, synchronize() will return without blocking.
Parameters
handle – A handle returned by an allreduce, allgather or broadcast asynchronous operation.
Returns
A flag indicating whether the operation has completed.
horovod.torch.synchronize(handle)[source]
Synchronizes an asynchronous allreduce, allgather or broadcast operation until it’s completed. Returns the result of the operation.
Parameters
handle – A handle returned by an allreduce, allgather or broadcast asynchronous operation.
Returns
An output tensor of the operation.
horovod.torch.init(comm=None)
A function that initializes Horovod.
Parameters
comm – List specifying ranks for the communicator, relative to the MPI_COMM_WORLD communicator OR the MPI communicator to use. Given communicator will be duplicated. If None, Horovod will use MPI_COMM_WORLD Communicator.
horovod.torch.is_initialized()
Returns True if Horovod is initialized
horovod.torch.start_timeline(file_path, mark_cycles=False)
Creates a timeline file at file_path and begins recording.
Parameters
• file_path – String path to the timeline file.
• mark_cycles – Boolean indicating that cycles should be marked on the timeline (default: False).
Raises a ValueError if Horovod is not initialized.
horovod.torch.stop_timeline()
Stops the active timeline recording and closes the file.
Raises a ValueError if Horovod is not initialized.
horovod.torch.size()
A function that returns the number of Horovod processes.
Returns
An integer scalar containing the number of Horovod processes.
horovod.torch.local_size()
A function that returns the number of Horovod processes within the node the current process is running on.
Returns
An integer scalar containing the number of local Horovod processes.
horovod.torch.rank()
A function that returns the Horovod rank of the calling process.
Returns
An integer scalar with the Horovod rank of the calling process.
horovod.torch.local_rank()
A function that returns the local Horovod rank of the calling process, within the node that it is running on. For example, if there are seven processes running on a node, their local ranks will be zero through six, inclusive.
Returns
An integer scalar with the local Horovod rank of the calling process.
horovod.torch.mpi_threads_supported()
A function that returns a flag indicating whether MPI multi-threading is supported.
If MPI multi-threading is supported, users may mix and match Horovod usage with other MPI libraries, such as mpi4py.
Returns
A boolean value indicating whether MPI multi-threading is supported.
horovod.torch.mpi_enabled()
Returns True if MPI is mode is currently enabled at runtime.
If MPI is enabled, users can use it for controller or data transfer operations.
Returns
A boolean value indicating whether MPI is enabled.
horovod.torch.mpi_built()
Returns True if Horovod was compiled with MPI support.
Returns
A boolean value indicating whether MPI support was compiled.
horovod.torch.gloo_enabled()
Returns True if Gloo is mode is currently enabled at runtime.
If Gloo is enabled, users can use it for controller or data transfer operations.
Returns
A boolean value indicating whether Gloo is enabled.
horovod.torch.gloo_built()
Returns True if Horovod was compiled with Gloo support.
Returns
A boolean value indicating whether Gloo support was compiled.
horovod.torch.nccl_built()
Function to check if Horovod was compiled with NCCL support.
Returns
An integer value indicating whether NCCL support was compiled. If NCCL support was compiled, returns NCCL_VERSION_CODE. Otherwise, returns 0.
horovod.torch.ddl_built()
Returns True if Horovod was compiled with DDL support.
Returns
A boolean value indicating whether DDL support was compiled.
horovod.torch.ccl_built()
Returns True if Horovod was compiled with oneCCL support.
Returns
A boolean value indicating whether oneCCL support was compiled.
horovod.torch.cuda_built()
Returns True if Horovod was compiled with CUDA support.
Returns
A boolean value indicating whether CUDA support was compiled.
horovod.torch.rocm_built()
Returns True if Horovod was compiled with ROCm support.
Returns
A boolean value indicating whether ROCm support was compiled.
horovod.torch.DistributedOptimizer(optimizer, named_parameters=None, compression=<class 'horovod.torch.compression.NoneCompressor'>, backward_passes_per_step=1, op=<MagicMock name='mock().horovod_reduce_op_average()' id='140118672651264'>, gradient_predivide_factor=1.0)[source]
An optimizer that wraps another torch.optim.Optimizer, using an allreduce to combine gradient values before applying gradients to model weights.
Allreduce operations are executed after each gradient is computed by loss.backward() in parallel with each other. The step() method ensures that all allreduce operations are finished before applying gradients to the model.
DistributedOptimizer exposes the synchronize() method, which forces allreduce operations to finish before continuing the execution. It’s useful in conjunction with gradient clipping, or other operations that modify gradients in place before step() is executed. Make sure to use optimizer.skip_synchronize() if you’re calling synchronize() in your code.
output = model(data)
loss = F.nll_loss(output, target)
loss.backward()
optimizer.synchronize()
with optimizer.skip_synchronize():
optimizer.step()
Parameters
• optimizer – Optimizer to use for computing gradients and applying updates.
• named_parameters – A mapping between parameter names and values. Used for naming of allreduce operations. Typically just model.named_parameters().
• compression – Compression algorithm used during allreduce to reduce the amount of data sent during the each parameter update step. Defaults to not using compression.
• backward_passes_per_step – Number of expected backward passes to perform before calling step()/synchronize(). This allows accumulating gradients over multiple mini-batches before reducing and applying them.
• op – The reduction operation to use when combining gradients across different ranks.
• gradient_predivide_factor – If op == Average, gradient_predivide_factor splits the averaging before and after the sum. Gradients are scaled by 1.0 / gradient_predivide_factor before the sum and gradient_predivide_factor / size after the sum.
class horovod.torch.SyncBatchNorm(num_features, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)[source]
Applies synchronous version of N-dimensional BatchNorm.
In this version, normalization parameters are synchronized across workers during forward pass. This is very useful in situations where each GPU can fit a very small number of examples.
See https://pytorch.org/docs/stable/nn.html#batchnorm2d for more details about BatchNorm.
Parameters
• num_features – number of channels C from the shape (N, C, …)
• eps – a value added to the denominator for numerical stability. Default: 1e-5
• momentum – the value used for the running_mean and running_var computation. Can be set to None for cumulative moving average (i.e. simple average). Default: 0.1
• affine – a boolean value that when set to True, this module has learnable affine parameters. Default: True
• track_running_stats – a boolean value that when set to True, this module tracks the running mean and variance, and when set to False, this module does not track such statistics and always uses batch statistics in both training and eval modes. Default: True
Note
Only GPU input tensors are supported in the training mode.
class horovod.torch.elastic.ElasticSampler(dataset, shuffle=True, seed=0)[source]
Sampler that partitions dataset across ranks and repartitions after reset events.
Works similar to DistributedSampler, but with an optional capability to record which dataset indices have been processed each batch. When tracked by a TorchState object, the sampler will automatically repartition the unprocessed indices among the new set of workers.
In order to use this object successfully it is recommended that the user:
1. Include this object in the TorchState.
2. Call record_batch or record_indices after processing a set of samples.
3. Call set_epoch at the end of each epoch to clear the processed indices.
Parameters
• dataset – Dataset used for sampling (assumed to be of constant size).
• shuffle – If True (default), shuffle the indices.
• seed – Random seed used to shuffle the sampler when shuffle=True. This number should be identical across all ranks (default: 0).
set_epoch(epoch)[source]
Sets the epoch for this sampler.
When shuffle=True, this ensures all replicas use a different random ordering for each epoch.
Will clear and reset the processed_indices for the next epoch. It is important that this is called at the end of the epoch (not the beginning) to ensure that partially completed epochs do not reprocess samples.
Parameters
epoch – Epoch number.
record_batch(batch_idx, batch_size)[source]
Record indices at batch batch_idx with length batch_size as processed.
record_indices(indices)[source]
Record set indices as processed.
get_indices(batch_idx, batch_size)[source]
Return list of indices at batch batch_idx with length batch_size.
class horovod.torch.elastic.TorchState(model=None, optimizer=None, **kwargs)[source]
State representation of a PyTorch training process.
Multiple models and optimizers are supported by providing them as kwargs. During initialization, TorchState will assign attributes for every keyword argument, and handle its state synchronization.
Parameters
• model – Optional PyTorch model.
• optimizer – Optional PyTorch optimizer.
• kwargs – Attributes sync, will be exposed as attributes of the object. If a handler exists for the attribute type, it will be used to sync the object, otherwise it will be handled an ordinary Python object.
save()[source]
Saves state to host memory.
restore()[source]
Restores the last committed state, undoing any uncommitted modifications.
sync()[source]
Synchronize state across workers.
horovod.torch.elastic.run(func)[source]
Decorator used to run the elastic training process.
The purpose of this decorator is to allow for uninterrupted execution of the wrapped function across multiple workers in parallel, as workers come and go from the system. When a new worker is added, its state needs to be brought to the same point as the other workers, which is done by synchronizing the state object before executing func.
When a worker is added or removed, other workers will raise an exception to bring them back to such a sync point before executing func again. This ensures that workers do not diverge when such reset events occur.
It’s important to note that collective operations (e.g., broadcast, allreduce) cannot be the call to the wrapped function. Otherwise, new workers could execute these operations during their initialization while other workers are attempting to sync state, resulting in deadlock.
Parameters
func – a wrapped function taking any number of args or kwargs. The first argument must be a horovod.common.elastic.State object used to synchronize state across workers.
## horovod.mxnet¶
horovod.mxnet.allgather_object(obj, name=None)[source]
Serializes and allgathers an object from all other processes.
Parameters
• obj – An object capable of being serialized without losing any context.
• name – Optional name to use during allgather, will default to the class type.
Returns
The list of objects that were allgathered across all ranks.
horovod.mxnet.broadcast_object(obj, root_rank=0, name=None)[source]
Serializes and broadcasts an object from root rank to all other processes.
Parameters
• obj – An object capable of being serialized without losing any context.
• root_rank – The rank of the process from which parameters will be broadcasted to all other processes.
• name – Optional name to use during broadcast, will default to the class type.
Returns
The object that was broadcast from the root_rank.
horovod.mxnet.allgather(tensor, name=None, priority=0)[source]
A function that concatenates the input tensor with the same input tensor on all other Horovod processes. The input tensor is not modified.
The concatenation is done on the first dimension, so the input tensors on the different processes must have the same rank and shape, except for the first dimension, which is allowed to be different.
Parameters
• tensor – A tensor to allgather.
• name – A name of the allgather operation.
• priority – The priority of this operation. Higher priority operations are likely to be executed before other operations.
Returns
A tensor of the same type as tensor, concatenated on dimension zero across all processes. The shape is identical to the input shape, except for the first dimension, which may be greater and is the sum of all first dimensions of the tensors in different Horovod processes.
horovod.mxnet.allreduce(tensor, average=True, name=None, priority=0, prescale_factor=1.0, postscale_factor=1.0)[source]
A function that performs averaging or summation of the input tensor over all the Horovod processes. The input tensor is not modified.
The reduction operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The reduction will not start until all processes are ready to send and receive the tensor.
This acts as a thin wrapper around an autograd function. If your input tensor requires gradients, then callings this function will allow gradients to be computed and backpropagated.
Parameters
• tensor – A tensor to average and sum.
• average – A flag indicating whether to compute average or summation, defaults to average.
• name – A name of the reduction operation.
• priority – The priority of this operation. Higher priority operations are likely to be executed before other operations.
• prescale_factor – Multiplicative factor to scale tensor before allreduce
• postscale_factor – Multiplicative factor to scale tensor after allreduce
Returns
A tensor of the same shape and type as tensor, averaged or summed across all processes.
horovod.mxnet.allreduce_(tensor, average=True, name=None, priority=0, prescale_factor=1.0, postscale_factor=1.0)[source]
A function that performs in-place averaging or summation of the input tensor over all the Horovod processes.
The reduction operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The reduction will not start until all processes are ready to send and receive the tensor.
Parameters
• tensor – A tensor to average and sum.
• average – A flag indicating whether to compute average or summation, defaults to average.
• name – A name of the reduction operation.
• priority – The priority of this operation. Higher priority operations are likely to be executed before other operations.
• prescale_factor – Multiplicative factor to scale tensor before allreduce
• postscale_factor – Multiplicative factor to scale tensor after allreduce
Returns
A tensor of the same shape and type as tensor, averaged or summed across all processes.
horovod.mxnet.alltoall(tensor, splits=None, name=None, priority=0)[source]
A function that scatters slices of the input tensor to all other Horovod processes and returns a tensor of gathered slices from all other Horovod processes. The input tensor is not modified.
The slicing is done on the first dimension, so the input tensors on the different processes must have the same rank and shape, except for the first dimension, which is allowed to be different.
Parameters
• tensor – A tensor to distribute with alltoall.
• splits – A tensor of integers in rank order describing how many elements in tensor to send to each worker. Splitting is applied along the first dimension of tensor. If splits is not provided, the first dimension is split equally by the number of Horovod processes.
• name – A name of the alltoall operation.
• priority – The priority of this operation. Higher priority operations are likely to be executed before other operations.
Returns
A tensor containing the gathered tensor data from all workers.
horovod.mxnet.broadcast(tensor, root_rank, name=None, priority=0)[source]
A function that broadcasts the input tensor on root rank to the same input tensor on all other Horovod processes. The input tensor is not modified.
The broadcast operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The broadcast will not start until all processes are ready to send and receive the tensor.
This acts as a thin wrapper around an autograd function. If your input tensor requires gradients, then callings this function will allow gradients to be computed and backpropagated.
Parameters
• tensor – A tensor to broadcast.
• root_rank – The rank to broadcast the value from.
• name – A name of the broadcast operation.
• priority – The priority of this operation. Higher priority operations are likely to be executed before other operations.
Returns
A tensor of the same shape and type as tensor, with the value broadcasted from root rank.
horovod.mxnet.broadcast_(tensor, root_rank, name=None, priority=0)[source]
A function that broadcasts the input tensor on root rank to the same input tensor on all other Horovod processes. The operation is performed in-place.
The broadcast operation is keyed by the name. If name is not provided, an incremented auto-generated name is used. The tensor type and shape must be the same on all Horovod processes for a given name. The broadcast will not start until all processes are ready to send and receive the tensor.
Parameters
• tensor – A tensor to broadcast.
• root_rank – The rank to broadcast the value from.
• name – A name of the broadcast operation.
• priority – The priority of this operation. Higher priority operations are likely to be executed before other operations.
Returns
A tensor of the same shape and type as tensor, with the value broadcasted from root rank.
horovod.mxnet.init(comm=None)
A function that initializes Horovod.
Parameters
comm – List specifying ranks for the communicator, relative to the MPI_COMM_WORLD communicator OR the MPI communicator to use. Given communicator will be duplicated. If None, Horovod will use MPI_COMM_WORLD Communicator.
horovod.mxnet.shutdown()
A function that shuts Horovod down.
horovod.mxnet.is_initialized()
Returns True if Horovod is initialized
horovod.mxnet.start_timeline(file_path, mark_cycles=False)
Creates a timeline file at file_path and begins recording.
Parameters
• file_path – String path to the timeline file.
• mark_cycles – Boolean indicating that cycles should be marked on the timeline (default: False).
Raises a ValueError if Horovod is not initialized.
horovod.mxnet.stop_timeline()
Stops the active timeline recording and closes the file.
Raises a ValueError if Horovod is not initialized.
horovod.mxnet.size()
A function that returns the number of Horovod processes.
Returns
An integer scalar containing the number of Horovod processes.
horovod.mxnet.local_size()
A function that returns the number of Horovod processes within the node the current process is running on.
Returns
An integer scalar containing the number of local Horovod processes.
horovod.mxnet.rank()
A function that returns the Horovod rank of the calling process.
Returns
An integer scalar with the Horovod rank of the calling process.
horovod.mxnet.local_rank()
A function that returns the local Horovod rank of the calling process, within the node that it is running on. For example, if there are seven processes running on a node, their local ranks will be zero through six, inclusive.
Returns
An integer scalar with the local Horovod rank of the calling process.
horovod.mxnet.mpi_threads_supported()
A function that returns a flag indicating whether MPI multi-threading is supported.
If MPI multi-threading is supported, users may mix and match Horovod usage with other MPI libraries, such as mpi4py.
Returns
A boolean value indicating whether MPI multi-threading is supported.
horovod.mxnet.mpi_enabled()
Returns True if MPI is mode is currently enabled at runtime.
If MPI is enabled, users can use it for controller or data transfer operations.
Returns
A boolean value indicating whether MPI is enabled.
horovod.mxnet.mpi_built()
Returns True if Horovod was compiled with MPI support.
Returns
A boolean value indicating whether MPI support was compiled.
horovod.mxnet.gloo_enabled()
Returns True if Gloo is mode is currently enabled at runtime.
If Gloo is enabled, users can use it for controller or data transfer operations.
Returns
A boolean value indicating whether Gloo is enabled.
horovod.mxnet.gloo_built()
Returns True if Horovod was compiled with Gloo support.
Returns
A boolean value indicating whether Gloo support was compiled.
horovod.mxnet.nccl_built()
Function to check if Horovod was compiled with NCCL support.
Returns
An integer value indicating whether NCCL support was compiled. If NCCL support was compiled, returns NCCL_VERSION_CODE. Otherwise, returns 0.
horovod.mxnet.ddl_built()
Returns True if Horovod was compiled with DDL support.
Returns
A boolean value indicating whether DDL support was compiled.
horovod.mxnet.ccl_built()
Returns True if Horovod was compiled with oneCCL support.
Returns
A boolean value indicating whether oneCCL support was compiled.
horovod.mxnet.cuda_built()
Returns True if Horovod was compiled with CUDA support.
Returns
A boolean value indicating whether CUDA support was compiled.
horovod.mxnet.rocm_built()
Returns True if Horovod was compiled with ROCm support.
Returns
A boolean value indicating whether ROCm support was compiled.
horovod.mxnet.broadcast_parameters(params, root_rank=0, prefix=None)[source]
Broadcasts the parameters from root rank to all other processes. Typical usage is to broadcast the Module.get_params() or the Block.collect_params().
Parameters
• params – One of the following: - dict of parameters to broadcast - ParameterDict to broadcast
• root_rank – The rank of the process from which parameters will be broadcasted to all other processes.
• prefix – The prefix of the parameters to broadcast. If multiple broadcast_parameters are called in the same program, they must be specified by different prefixes to avoid tensor name collision.
## horovod.spark¶
horovod.spark.run(fn, args=(), kwargs={}, num_proc=None, start_timeout=None, use_mpi=None, use_gloo=None, extra_mpi_args=None, env=None, stdout=None, stderr=None, verbose=1, nics=None)[source]
Runs Horovod on Spark. Runs num_proc processes executing fn using the same amount of Spark tasks.
Parameters
• fn – Function to run.
• args – Arguments to pass to fn.
• kwargs – Keyword arguments to pass to fn.
• num_proc – Number of Horovod processes. Defaults to spark.default.parallelism.
• start_timeout – Timeout for Spark tasks to spawn, register and start running the code, in seconds. If not set, falls back to HOROVOD_SPARK_START_TIMEOUT environment variable value. If it is not set as well, defaults to 600 seconds.
• extra_mpi_args – Extra arguments for mpi_run. Defaults to no extra args.
• env – Environment dictionary to use in Horovod run.
• stdout – Horovod stdout is redirected to this stream. Defaults to sys.stdout.
• stderr – Horovod stderr is redirected to this stream. Defaults to sys.stderr.
• verbose – Debug output verbosity (0-2). Defaults to 1.
• nics – List of NICs for tcp network communication.
Returns
List of results returned by running fn on each rank.
horovod.spark.run_elastic(fn, args=(), kwargs={}, num_proc=None, min_np=None, max_np=None, start_timeout=None, elastic_timeout=None, reset_limit=None, env=None, verbose=1, nics=None)[source]
Runs Elastic Horovod on Spark. Runs num_proc processes executing fn using the same amount of Spark tasks.
Parameters
• fn – Function to run.
• args – Arguments to pass to fn.
• kwargs – Keyword arguments to pass to fn.
• num_proc – Number of Horovod processes. Defaults to spark.default.parallelism.
• start_timeout – Timeout for Spark tasks to spawn, register and start running the code, in seconds. If not set, falls back to HOROVOD_SPARK_START_TIMEOUT environment variable value. If it is not set as well, defaults to 600 seconds.
• elastic_timeout – Timeout for elastic initialisation after re-scaling the cluster. If not set, falls back to HOROVOD_ELASTIC_TIMEOUT environment variable value. If it is not set as well, defaults to 600 seconds.
• reset_limit – Maximum number of resets after which the job is terminated.
• env – Environment dictionary to use in Horovod run. Defaults to os.environ.
• verbose – Debug output verbosity (0-2). Defaults to 1.
• nics – List of NICs for tcp network communication.
Returns
List of results returned by running fn on each rank.
## horovod.spark.keras¶
class horovod.spark.keras.KerasEstimator[source]
Bases: horovod.spark.common.estimator.HorovodEstimator, horovod.spark.keras.estimator.KerasEstimatorParamsReadable, horovod.spark.keras.estimator.KerasEstimatorParamsWritable
Spark Estimator for fitting Keras models to a DataFrame.
Supports standalone keras and tf.keras, and TensorFlow 1.X and 2.X.
Parameters
• num_proc – Number of Horovod processes. Defaults to spark.default.parallelism.
• model – Keras model to train.
• backend – Optional Backend object for running distributed training function. Defaults to SparkBackend with num_proc worker processes. Cannot be specified if num_proc is also provided.
• store – Store object that abstracts reading and writing of intermediate data and run results.
• custom_objects – Optional dictionary mapping names (strings) to custom classes or functions to be considered during serialization/deserialization.
• optimizer – Keras optimizer to be converted into a hvd.DistributedOptimizer for training.
• loss – Keras loss or list of losses.
• loss_weights – Optional list of float weight values to assign each loss.
• sample_weight_col – Optional column indicating the weight of each sample.
• metrics – Optional metrics to record.
• feature_cols – Column names used as feature inputs to the model. Must be a list with each feature mapping to a sequential argument in the model’s forward() function.
• label_cols – Column names used as labels. Must be a list with one label for each output of the model.
• validation – Optional validation column name (string) where every row in the column is either 1/True or 0/False, or validation split (float) giving percent of data to be randomly selected for validation.
• callbacks – Keras callbacks.
• batch_size – Number of rows from the DataFrame per batch.
• epochs – Number of epochs to train.
• verbose – Verbosity level [0, 2] (default: 1).
• shuffle_buffer_size – Optional size of in-memory shuffle buffer in rows. Allocating a larger buffer size increases randomness of shuffling at the cost of more host memory. Defaults to estimating with an assumption of 4GB of memory per host.
• partitions_per_process – Number of Parquet partitions to assign per worker process from num_proc (default: 10).
• run_id – Optional unique ID for this run for organization in the Store. Will be automatically assigned if not provided.
• train_steps_per_epoch – Number of steps to train each epoch. Useful for testing that model trains successfully. Defaults to training the entire dataset each epoch.
• validation_steps_per_epoch – Number of validation steps to perform each epoch.
• transformation_fn – Optional function that takes a row as its parameter and returns a modified row that is then fed into the train or validation step. This transformation is applied after batching. See Petastorm [TransformSpec](https://github.com/uber/petastorm/blob/master/petastorm/transform.py) for more details. Note that this fucntion constructs another function which should perform the transformation.
• train_reader_num_workers – This parameter specifies the number of parallel processes that read the training data from data store and apply data transformations to it. Increasing this number will generally increase the reading rate but will also increase the memory footprint. More processes are particularly useful if the bandwidth to the data store is not high enough, or users need to apply transformation such as decompression or data augmentation on raw data.
class horovod.spark.keras.KerasModel[source]
Bases: horovod.spark.common.estimator.HorovodModel, horovod.spark.keras.estimator.KerasEstimatorParamsReadable, horovod.spark.keras.estimator.KerasEstimatorParamsWritable
Spark Transformer wrapping a Keras model, used for making predictions on a DataFrame.
Retrieve the underlying Keras model by calling keras_model.getModel().
Parameters
• history – List of metrics, one entry per epoch during training.
• model – Trained Keras model.
• feature_columns – List of feature column names.
• label_columns – List of label column names.
• custom_objects – Keras custom objects.
• run_id – ID of the run used to train the model.
## horovod.spark.torch¶
class horovod.spark.torch.TorchEstimator[source]
Bases: horovod.spark.common.estimator.HorovodEstimator, horovod.spark.torch.estimator.TorchEstimatorParamsWritable, horovod.spark.torch.estimator.TorchEstimatorParamsReadable
Spark Estimator for fitting PyTorch models to a DataFrame.
Parameters
• num_proc – Number of Horovod processes. Defaults to spark.default.parallelism.
• model – PyTorch model to train.
• backend – Optional Backend object for running distributed training function. Defaults to SparkBackend with num_proc worker processes. Cannot be specified if num_proc is also provided.
• store – Store object that abstracts reading and writing of intermediate data and run results.
• optimizer – PyTorch optimizer to be converted into a hvd.DistributedOptimizer for training.
• loss – PyTorch loss or list of losses.
• loss_constructors – Optional functions that generate losses.
• metrics – Optional metrics to record.
• loss_weights – Optional list of float weight values to assign each loss.
• sample_weight_col – Optional column indicating the weight of each sample.
• feature_cols – Column names used as feature inputs to the model. Must be a list with each feature mapping to a sequential argument in the model’s forward() function.
• input_shapes – List of shapes for each input tensor to the model.
• validation – Optional validation column name (string) where every row in the column is either 1/True or 0/False, or validation split (float) giving percent of data to be randomly selected for validation.
• label_cols – Column names used as labels. Must be a list with one label for each output of the model.
• batch_size – Number of rows from the DataFrame per batch.
• epochs – Number of epochs to train.
• verbose – Verbosity level [0, 2] (default: 1).
• shuffle_buffer_size – Optional size of in-memory shuffle buffer in rows. Allocating a larger buffer size increases randomness of shuffling at the cost of more host memory. Defaults to estimating with an assumption of 4GB of memory per host.
• partitions_per_process – Number of Parquet partitions to assign per worker process from num_proc (default: 10).
• run_id – Optional unique ID for this run for organization in the Store. Will be automatically assigned if not provided.
• train_minibatch_fn – Optional custom function to execute within the training loop. Defaults to standard gradient descent process.
• train_steps_per_epoch – Number of steps to train each epoch. Useful for testing that model trains successfully. Defaults to training the entire dataset each epoch.
• validation_steps_per_epoch – Number of validation steps to perform each epoch.
• transformation_fn – Optional function that takes a row as its parameter and returns a modified row that is then fed into the train or validation step. This transformation is applied after batching. See Petastorm [TransformSpec](https://github.com/uber/petastorm/blob/master/petastorm/transform.py) for more details. Note that this fucntion constructs another function which should perform the transformation.
• train_reader_num_workers – This parameter specifies the number of parallel processes that read the training data from data store and apply data transformations to it. Increasing this number will generally increase the reading rate but will also increase the memory footprint. More processes are particularly useful if the bandwidth to the data store is not high enough, or users need to apply transformation such as decompression or data augmentation on raw data.
class horovod.spark.torch.TorchModel[source]
Bases: horovod.spark.common.estimator.HorovodModel, horovod.spark.torch.estimator.TorchEstimatorParamsWritable, horovod.spark.torch.estimator.TorchEstimatorParamsReadable
Spark Transformer wrapping a PyTorch model, used for making predictions on a DataFrame.
Retrieve the underlying PyTorch model by calling torch_model.getModel().
Parameters
• history – List of metrics, one entry per epoch during training.
• model – Trained PyTorch model.
• feature_columns – List of feature column names.
• label_columns – List of label column names.
• optimizer – PyTorch optimizer used during training, containing updated state.
• run_id – ID of the run used to train the model.
• loss – PyTorch loss(es).
• loss_constructors – PyTorch loss constructors.
## horovod.spark.common¶
class horovod.spark.common.estimator.HorovodEstimator[source]
fit(df, params=None)[source]
Fits the model to the DataFrame.
Parameters
• df – Input dataset, which is an instance of pyspark.sql.DataFrame.
• params – An optional param map that overrides embedded params.
Returns
HorovodModel transformer wrapping the trained model.
fit_on_parquet(params=None)[source]
Trains the model on a saved Parquet file at store.get_train_path().
Parameters
params – An optional param map that overrides embedded params.
Returns
Trained HorovodModel transformer of the appropriate subclass wrapping the trained model.
class horovod.spark.common.estimator.HorovodModel[source]
transform(df, params=None)[source]
Transforms the input dataset with prediction columns representing model predictions.
Prediction column names default to <label_column>__output. Override column names by calling transformer.setOutputCols(col_names).
Parameters
• df – Input dataset, which is an instance of pyspark.sql.DataFrame.
• params – An optional param map that overrides embedded params.
Returns
Transformed dataset.
class horovod.spark.common.backend.Backend[source]
Bases: object
Interface for remote execution of the distributed training function.
A custom backend can be used in cases where the training environment running Horovod is different from the Spark application running the HorovodEstimator.
run(fn, args=(), kwargs={}, env=None)[source]
Executes the training fn and returns results from each worker in a list (ordered by ascending rank).
Parameters
• fn – Function to run.
• args – Arguments to pass to fn.
• kwargs – Keyword arguments to pass to fn.
• env – Environment dictionary to use in Horovod run. Defaults to os.environ.
Returns
List of results returned by running fn on each rank.
num_processes()[source]
Returns the number of processes to use for training.
class horovod.spark.common.backend.SparkBackend(num_proc=None, env=None, **kwargs)[source]
Uses horovod.spark.run to execute the distributed training fn.
run(fn, args=(), kwargs={}, env=None)[source]
Executes the training fn and returns results from each worker in a list (ordered by ascending rank).
Parameters
• fn – Function to run.
• args – Arguments to pass to fn.
• kwargs – Keyword arguments to pass to fn.
• env – Environment dictionary to use in Horovod run. Defaults to os.environ.
Returns
List of results returned by running fn on each rank.
num_processes()[source]
Returns the number of processes to use for training.
class horovod.spark.common.store.Store[source]
Bases: object
Storage layer for intermediate files (materialized DataFrames) and training artifacts (checkpoints, logs).
Store provides an abstraction over a filesystem (e.g., local vs HDFS) or blob storage database. It provides the basic semantics for reading and writing objects, and how to access objects with certain definitions.
The store exposes a generic interface that is not coupled to a specific DataFrame, model, or runtime. Every run of an Estimator should result in a separate run directory containing checkpoints and logs, and every variation in dataset should produce a separate intermediate data path.
In order to allow for caching but to prevent overuse of disk space on intermediate data, intermediate datasets are named in a deterministic sequence. When a dataset is done being used for training, the intermediate files can be reclaimed to free up disk space, but will not be automatically removed so that they can be reused as needed. This is to support both parallel training processes using the same store on multiple DataFrames, as well as iterative training using the same DataFrame on different model variations.
is_parquet_dataset(path)[source]
Returns True if the path is the root of a Parquet dataset.
get_parquet_dataset(path)[source]
Returns a pyarrow.parquet.ParquetDataset from the path.
get_train_data_path(idx=None)[source]
Returns the path to the training dataset.
get_val_data_path(idx=None)[source]
Returns the path to the validation dataset.
get_test_data_path(idx=None)[source]
Returns the path to the test dataset.
saving_runs()[source]
Returns True if run output should be saved during training.
get_runs_path()[source]
Returns the base path for all runs.
get_run_path(run_id)[source]
Returns the path to the run with the given ID.
get_checkpoint_path(run_id)[source]
Returns the path to the checkpoint file for the given run.
get_logs_path(run_id)[source]
Returns the path to the log directory for the given run.
get_checkpoint_filename()[source]
Returns the basename of the saved checkpoint file.
get_logs_subdir()[source]
Returns the subdirectory name for the logs directory.
exists(path)[source]
Returns True if the path exists in the store.
read(path)[source]
Returns the contents of the path as bytes.
sync_fn(run_id)[source]
Returns a function that synchronises given path recursively into run path for run_id.
to_remote(run_id, dataset_idx)[source]
Returns a view of the store that can execute in a remote environment without Horoovd deps.
class horovod.spark.common.store.FilesystemStore(prefix_path, train_path=None, val_path=None, test_path=None, runs_path=None, save_runs=True)[source]
Abstract class for stores that use a filesystem for underlying storage.
exists(path)[source]
Returns True if the path exists in the store.
read(path)[source]
Returns the contents of the path as bytes.
read_serialized_keras_model(ckpt_path, model, custom_objects)[source]
Reads the checkpoint file of the keras model into model bytes and returns the base 64 encoded model bytes. :param ckpt_path: A string of path to the checkpoint file. :param model: A keras model. This parameter will be used in DBFSLocalStore .read_serialized_keras_model() when the ckpt_path only contains model weights. :param custom_objects: This parameter will be used in DBFSLocalStore .read_serialized_keras_model() when loading the keras model. :return: the base 64 encoded model bytes of the checkpoint model.
is_parquet_dataset(path)[source]
Returns True if the path is the root of a Parquet dataset.
get_parquet_dataset(path)[source]
Returns a pyarrow.parquet.ParquetDataset from the path.
get_train_data_path(idx=None)[source]
Returns the path to the training dataset.
get_val_data_path(idx=None)[source]
Returns the path to the validation dataset.
get_test_data_path(idx=None)[source]
Returns the path to the test dataset.
saving_runs()[source]
Returns True if run output should be saved during training.
get_runs_path()[source]
Returns the base path for all runs.
get_run_path(run_id)[source]
Returns the path to the run with the given ID.
get_checkpoint_path(run_id)[source]
Returns the path to the checkpoint file for the given run.
get_logs_path(run_id)[source]
Returns the path to the log directory for the given run.
get_checkpoint_filename()[source]
Returns the basename of the saved checkpoint file.
get_logs_subdir()[source]
Returns the subdirectory name for the logs directory.
class horovod.spark.common.store.LocalStore(prefix_path, *args, **kwargs)[source]
Uses the local filesystem as a store of intermediate data and training artifacts.
sync_fn(run_id)[source]
Returns a function that synchronises given path recursively into run path for run_id.
class horovod.spark.common.store.HDFSStore(prefix_path, host=None, port=None, user=None, kerb_ticket=None, driver='libhdfs', extra_conf=None, temp_dir=None, *args, **kwargs)[source]
Uses HDFS as a store of intermediate data and training artifacts.
Initialized from a prefix_path that can take one of the following forms:
1. “hdfs://namenode01:8020/user/test/horovod”
2. “hdfs:///user/test/horovod”
3. “/user/test/horovod”
The full path (including prefix, host, and port) will be used for all reads and writes to HDFS through Spark. If host and port are not provided, they will be omitted. If prefix is not provided (case 3), it will be prefixed to the full path regardless.
The localized path (without prefix, host, and port) will be used for interaction with PyArrow. Parsed host and port information will be used to initialize PyArrow HadoopFilesystem if they are not provided through the host and port arguments to this initializer. These parameters will default to default and 0 if neither the path URL nor the arguments provide this information.
sync_fn(run_id)[source]
Returns a function that synchronises given path recursively into run path for run_id.
class horovod.spark.common.store.DBFSLocalStore(prefix_path, *args, **kwargs)[source]
Uses Databricks File System (DBFS) local file APIs as a store of intermediate data and training artifacts.
Initialized from a prefix_path starts with /dbfs/…, see https://docs.databricks.com/data/databricks-file-system.html#local-file-apis.
Note that DBFSLocalStore cannot be created via Store.create(“/dbfs/…”), which will create a LocalStore instead.
get_checkpoint_filename()[source]
Returns the basename of the saved checkpoint file.
read_serialized_keras_model(ckpt_path, model, custom_objects)[source]
Returns serialized keras model. On Databricks, only TFKeras is supported, not BareKeras. The parameter model is for providing the model structure when the checkpoint file only contains model weights.
## horovod.ray¶
class horovod.ray.RayExecutor(settings, num_hosts: int = 1, num_slots: int = 1, cpus_per_slot: int = 1, use_gpu: bool = False, gpus_per_slot: Optional[int] = None)[source]
Job class for Horovod + Ray integration.
Parameters
• settings (horovod.Settings) – Configuration for job setup. You can use a standard Horovod Settings object or create one directly from RayExecutor.create_settings.
• num_hosts (int) – Number of machines to execute the job on.
• num_slots (int) – Humber of workers to be placed on each machine.
• cpus_per_slot (int) – Number of CPU resources to allocate to each worker.
• use_gpu (bool) – Whether to use GPU for allocation. TODO: this can be removed.
• gpus_per_slot (int) – Number of GPU resources to allocate to each worker.
classmethod create_settings(timeout_s, ssh_identity_file=None, ssh_str=None)[source]
Create a mini setting object.
Parameters
• timeout_s (int) – Tiemout parameter for Gloo rendezvous.
• ssh_identity_file (str) – Path to the identity file to ssh into different hosts on the cluster.
• ssh_str (str) – CAUTION WHEN USING THIS. Private key file contents. Writes the private key to ssh_identity_file.
Returns
MiniSettings object.
detect_nics()[source]
Decomposed version of driver_service.get_common_interfaces().
start(executable_cls: type = None, executable_args: Optional[List] = None, executable_kwargs: Optional[Dict] = None, extra_env_vars: Optional[Dict] = None)[source]
Starts the workers and colocates them on all machines.
We implement a node grouping because it seems like our implementation doesn’t quite work for imbalanced nodes. Also, colocation performance is typically much better than non-colocated workers.
Parameters
• executable_cls (type) – The class that will be created within an actor (BaseHorovodWorker). This will allow Horovod to establish its connections and set env vars.
• executable_args (List) – Arguments to be passed into the worker class upon initialization.
• executable_kwargs (Dict) – Keyword arguments to be passed into the worker class upon initialization.
• extra_env_vars (Dict) – Environment variables to be set on the actors (worker processes) before initialization.
execute(fn: Callable[[executable_cls], Any]) → List[Any][source]
Executes the provided function on all workers.
Parameters
fn – Target function to be invoked on every object.
Returns
Deserialized return values from the target function.
run(fn: Callable[[Any], Any], args: Optional[List] = None, kwargs: Optional[Dict] = None) → List[Any][source]
Executes the provided function on all workers.
Parameters
• fn – Target function that can be executed with arbitrary args and keyword arguments.
• args – List of arguments to be passed into the target function.
• kwargs – Dictionary of keyword arguments to be passed into the target function.
Returns
Deserialized return values from the target function.
execute_single(fn: Callable[[executable_cls], Any]) → List[Any][source]
Executes the provided function on the rank 0 worker (chief).
Parameters
fn – Target function to be invoked on the chief object.
Returns
Deserialized return values from the target function.
shutdown()[source]
Destroys the provided workers.
class horovod.ray.ElasticRayExecutor(settings: horovod.runner.elastic.settings.ElasticSettings, use_gpu: bool = False, cpus_per_slot: int = 1, gpus_per_slot: Optional[int] = None, env_vars: dict = None, override_discovery=True)[source]
Executor for elastic jobs using Ray.
Leverages the Ray global state to detect available hosts and slots. Assumes that the entire Ray cluster is available for the Executor to use.
Parameters
• settings – Configuration for the elastic job setup. You can use a standard Horovod ElasticSettings object or create one directly from ElasticRayExecutor.create_settings.
• use_gpu (bool) – Whether to use GPU for allocation.
• cpus_per_slot (int) – Number of CPU resources to allocate to each worker.
• gpus_per_slot (int) – Number of GPU resources to allocate to each worker.
• env_vars (Dict) – Environment variables to be set on the actors (worker processes) before initialization.
• override_discovery (bool) – Whether for the ElasticRayExecutor to automatically provide a discovery mechanism for ElasticSettings.
Example:
import ray
settings = ElasticRayExecutor.create_settings(verbose=True)
executor = ElasticRayExecutor(
settings, use_gpu=True, cpus_per_slot=2)
executor.start()
executor.run(train_fn)
static create_settings(min_np: int = 1, max_np: int = None, reset_limit: int = None, elastic_timeout: int = 600, timeout_s: int = 30, ssh_identity_file: str = None, nics: str = None, **kwargs)[source]
Returns a Settings object for ElasticRayExecutor.
Note that the discovery property will be set at runtime.
Parameters
• min_np (int) – Minimum number of processes running for training to continue. If number of available processes dips below this threshold, then training will wait for more instances to become available.
• max_np (int) – Maximum number of training processes, beyond which no additional processes will be created. If not specified, then will be unbounded.
• reset_limit (int) – Maximum number of times that the training job can scale up or down the number of workers after which the job is terminated.
• elastic_timeout (int) – Timeout for elastic initialisation after re-scaling the cluster. The default value is 600 seconds. Alternatively, the environment variable HOROVOD_ELASTIC_TIMEOUT can also be used.’
• timeout_s (int) – Horovod performs all the checks and starts the processes before the specified timeout. The default value is 30 seconds.
• ssh_identity_file (str) – File on the driver from which the identity (private key) is read.
• nics (set) – Network interfaces that can be used for communication.
start()[source]
Starts the Horovod driver and services.
run(worker_fn: Callable) → List[Any][source]
Executes the provided function on all workers.
Parameters
worker_fn – Target elastic function that can be executed.
Returns
List of return values from every completed worker.
## horovod.run¶
Launch a Horovod job to run the specified process function and get the return value.
param func
The function to be run in Horovod job processes. The function return value will be collected as the corresponding Horovod process return value. This function must be compatible with pickle.
param args
Arguments to pass to func.
param kwargs
Keyword arguments to pass to func.
param np
Number of Horovod processes.
param min_np
Minimum number of processes running for training to continue. If number of available processes dips below this threshold, then training will wait for more instances to become available. Defaults to np
param max_np
Maximum number of training processes, beyond which no additional processes will be created. If not specified, then will be unbounded.
param slots
Number of slots for processes per host. Normally 1 slot per GPU per host. If slots are provided by the output of the host discovery script, then that value will override this parameter.
param reset_limit
Maximum number of times that the training job can scale up or down the number of workers after which the job is terminated. A reset event occurs when workers are added or removed from the job after the initial registration. So a reset_limit of 0 would mean the job cannot change membership after its initial set of workers. A reset_limit of 1 means it can resize at most once, etc.
param hosts
List of host names and the number of available slots for running processes on each, of the form: <hostname>:<slots> (e.g.: host1:2,host2:4,host3:1 indicating 2 processes can run on host1, 4 on host2, and 1 on host3). If not specified, defaults to using localhost:<np>
param hostfile
Path to a host file containing the list of host names and the number of available slots. Each line of the file must be of the form: <hostname> slots=<slots>
param start_timeout
Horovodrun has to perform all the checks and start the processes before the specified timeout. The default value is 30 seconds. Alternatively, The environment variable HOROVOD_START_TIMEOUT can also be used to specify the initialization timeout.
param ssh_port
SSH port on all the hosts.
param ssh_identity_file
SSH identity (private key) file.
param disable_cache
If the flag is not set, horovodrun will perform the initialization checks only once every 60 minutes – if the checks successfully pass. Otherwise, all the checks will run every time horovodrun is called.’
param output_filename
For Gloo, writes stdout / stderr of all processes to a filename of the form <output_filename>/rank.<rank>/<stdout | stderr>. The <rank> will be padded with 0 characters to ensure lexicographical order. For MPI, delegates its behavior to mpirun.
param verbose
If this flag is set, extra messages will be printed.
param use_gloo
Run Horovod using the Gloo controller. This will be the default if Horovod was not built with MPI support.
param use_mpi
Run Horovod using the MPI controller. This will be the default if Horovod was built with MPI support.
param mpi_args
Extra arguments for the MPI controller. This is only used when use_mpi is True.
param network_interface
Network interfaces to use for communication separated by comma. If not specified, Horovod will find the common NICs among all the workers and use those; example, eth0,eth1.
return
Return a list which contains values return by all Horovod processes. The index of the list corresponds to the rank of each Horovod process.
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https://www.arxiv-vanity.com/papers/0804.1671/
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arXiv Vanity renders academic papers from arXiv as responsive web pages so you don’t have to squint at a PDF. Read this paper on arXiv.org.
# State-of-the-art models for the phase diagram of carbon and diamond nucleation
L. M. Ghiringhelli1 , C. Valeriani2 , J. H. Los, E. J. Meijer,
A. Fasolino, and D. Frenkel3
van ’t Hoff Institute for Molecular Sciences,Universiteit van Amsterdam,
Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands.
FOM Institute for Atomic and Molecular Physics,
Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
Institute for Molecules and Materials, Radboud University Nijmegen
Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
11Current address: Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
22Current address: School of Physics, James Clerk Maxwell Building, King’s Buildings, University of Edinburgh, Mayfield Road, EH9 3JZ, Edinburgh, UK
33Current address: Dept. of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
###### Abstract
We review recent developments in the modelling of the phase diagram and the kinetics of crystallization of carbon. In particular, we show that a particular class of bond-order potentials (the so-called LCBOP models) account well for many of the known structural and thermodynamic properties of carbon at high pressures and temperatures. We discuss the LCBOP models in some detail. In addition, we briefly review the “history” of experimental and theoretical studies of the phase behaviour of carbon. Using a well-tested version of the LCBOP model (viz. LCBOPI) we address some of the more controversial hypotheses concerning the phase behaviour of carbon, in particular: the suggestion that liquid carbon can exist in two phases separated by a first-order phase transition and the conjecture that diamonds could have formed by homogeneous nucleation in Uranus and Neptune.
## 1 Introduction
Carbon exhibits a rich variety of solid structures: Some are thermodynamically stable, most are not. To be specific: solid carbon can be found in the two well-known crystalline phases, diamond and graphite, and in amorphous states, such as glassy carbon and carbon black. Furthermore, the existence of additional metastable solid phases at relatively low pressure, the so-called carbynes, is still hotly debated [1, 2]). In addition to the bulk phases, there are the more recently discovered fullerenes, C and C [3], nanotubes [4], and graphene [5].
The reason why a simple element such as carbon can manifest itself in so many different forms is related to its unusual chemical properties: carbon exhibits three different possibilities for covalent bond formation: hybridization appears in diamond, hybridization is found in graphite, graphene, nanotubes, and fullerenes, whilst in carbynes, C should exhibit hybridization.
Because of their high cohesive energies and concomitant high activation energies that must be overcome in structural phase transformations, carbon polymorphs often exist in metastable form well inside pressure-temperature regions where another solid form is thermodynamically stable. For example, it is well known that diamonds survive at normal P-T conditions, where graphite is the thermodynamically stable phase. Conversely, graphite tends to persist at very high pressures, deep into the diamond stability region of the phase diagram.
It is also interesting that, at zero pressure and temperature, graphite and diamond have a very similar (and quite large) binding energy per atom, i.e. 7.37 eV (graphite) vs 7.35 eV (diamond). This fact might suggest (and it has indeed been suggested) that also in disordered phases like the liquid, the two local structures – graphite-like and diamond-like – could compete. In fact, as we discuss below, the possibility of the existence of two distinct and partially immiscible liquid phases of carbon has been a subject of much debate.
In a liquid–liquid phase transition (LLPT), a liquid substance displays an abrupt change in some local or global property within a narrow band of pressures and temperatures. Local properties that may change in a LLPT are the local coordination or hybridization, typical global properties that are affected are the density or the resistivity. LLPT’s in dense, atomic liquids are typically difficult to probe experimentally: the candidate transitions often occur at extreme pressures and/or temperatures or appear in metastable regions of the phase diagram (and may be hidden by competing solidification). Evidence for LLPT’s have been found for a number of atomic systems, such as Cs [6], As [7], Bi [8], Ge [9], Hg [10], S [11], Sb [12], Se [13], Si [14, 15], Sn [16], H [17], I [18], N[19, 20]. The best established experimental example of a LLPT in an atomic liquid is the case of phosphorus. A transition between a fluid of tetrahedral molecules and a network forming (and metallic) liquid was predicted on theoretical grounds [21, 22], and subsequently verified experimentally [23, 24]. The LLPT in phosphorus has been analysed in several numerical studies [25, 26, 27, 28]. Many other network-forming liquids are also expected to exhibit LLPT’a: first and foremost water [29, 30], but also SiO [31] and GeO [32]. Although considerable progress has been made in the theoretical description of LLPT’s [33, 34, 35, 36, 37, 38], a unified theoretical picture is still lacking.
In this review we discuss the phase diagram of solid and liquid carbon at high pressures and temperatures on the basis of the results of numerical simulations; both quantum and classical. We present evidence that the presence of graphite-like and diamond-like local structures in the liquid does not give rise to liquid-liquid demixing but that the predominant local structure in the liquid varies strongly with pressure. The fact that the liquid is locally either graphite-like or diamond-like has dramatic consequences for the nucleation of the diamond phase, a finding that may have some consequences for our understanding of carbon-rich planets or stars. Wherever possible, we discuss our own results in the context of the relevant literature about the carbon phase diagram, about a possible LLPT in this system and about the possibility of diamond formation in planetary interiors.
In section 2 we give an overview of the bond-order potential (“LCBOP”) that was used to compute both the equilibrium phase diagram of carbon and the pathway for diamond nucleation in liquid carbon. We also discuss in some detail the different variants of the LCBOP potential [39, 40] and explain the rationale behind the choice of the present LCBOP potential.
In section 3 we briefly summarize some of the earlier ideas about the phase diagram of carbon (in particular, about the crystalline phases and the liquid). We pay special attention to the slope of the diamond melting curve and the (possible) heating-rate dependence of the graphite melting curve.
In section 3.2 we report our results concerning the phase diagram, in the context of recent first-principle simulations and experiments.
In section 4.1 we review the arguments that have been put forward to support the idea that liquid carbon can undergo a LLPT. We argue that, to the extent that we can trust the present models of liquid carbon, a LLPT in carbon is not be expected.
In section 5 we discuss our numerical results concerning the (homogeneous) nucleation of diamond from the bulk liquid. In particular, we discuss in some detail the numerical approach that was used in Ref. [41]. In addition, we focus on the structural analysis of the small solid clusters in the liquid and we discuss the implications of our findings for the formation of diamonds in carbon-rich star systems and the interior of giant planets.
## 2 The LCBOP-family
Whilst the crystalline phases of carbon can be simulated by traditional force fields that do not allow coordination changes, a study of the liquid phase and, a fortiori, of phase transformations between phases with different local coordination, requires a potential that can describe carbon in different coordination states. The LCBOP potential was designed with this objective in mind. LCBOP stands for ”Long range Carbon Bond Order Potential”, and represents a bond-order potential for pure carbon that includes long-range (LR) dispersive and repulsive interactions [39] from the outset. We stress that LCBOP is not based on an existing short-range (SR) bond-order potential to which LR interactions have been added a posteriori, although such an approach has been proposed in the literature [42, 43, 44]. The latter approach requires a rather special procedure to avoid interference with the SR potential and suffers from a loss of accuracy. In the LCBOP these problems are circumvented in a natural way.
We note that the term ”long range” may be confusing in this case, as the cut-off of the LR potential in LCBOP is only 6 Å. Usually, the term ”long range” is only used for interactions with a much longer range, such as Coulomb interactions. Here we use it as a synonym for ”non–bonded”, referring to a range much larger than the typical distances between chemically bonded atoms.
After the introduction of LCBOP in Ref. [39], a number of significant modifications have been introduced in order to improve its description of all carbon phases, including liquid carbon. To facilitate the distinction between the different LCBOP potentials, the various versions have been named LCBOPI, LCBOPI and LCBOPII. LCBOPI, introduced as LCBOP in Ref. [39], does not include torsion interactions. As torsion interactions were shown to play an important role in liquid carbon [45], we introduced a refinement of LCBOPI, called LCBOPI, when we performed our first study of liquid carbon [46]. LCBOPI, includes, among other changes, conjugation dependent torsional interactions. Clearly, describing the liquid phase requires a robust form of the potential in order to deal with configurations that are quite unlike the regular topologies in crystal lattices. LCBOPII addresses this problem: it includes several important improvements over LCBOPI. An important innovation in LCBOPII is the addition of so-called middle range (MR) interactions, introduced to bridge the gap between the extent of the tail of the covalent interactions as found in ab-initio calculations, (up to 4.5 Å in certain cases) and the rather short cut-off of only 2.2 Å in LCBOPI for these interactions.
In the remainder of this section we give a brief step-by-step description of the transition from bond-order potentials (BOPs) to LCBOPI. All the results presented in later sections, concerning the phase diagram, the liquid structure, and the nucleation issues are obtained with this version of the potential. In Appendix A we discuss the LCBOPII potential, with a short account of results obtained with this refined version of the potential. We aim at giving the flavour of the potentials in a mainly descriptive way with graphical illustrations, minimizing mathematical formulation.
### 2.1 Bond-order potentials
A bond-order potential (BOP) is a reactive potential, i.e. able to deal with variable coordination. It provides a quantitative description of the simple idea that the bonds of an atom with many neighbours are weaker than those of an atom with few neighbours, as the cohesive ability of the available electrons has to be shared among the neighbours. For carbon, each atom delivers four valence electrons. If these four electrons have to make the six bonds in a simple cubic lattice, then it is evident that each of these bonds is weaker than a bond in the diamond or graphite lattice with coordinations 4 and 3 respectively. On the other hand, the number of bonds is larger for the simple cubic lattice. So there is a balance to be made, which in the case of carbon has the result that graphite is the most stable phase at ambient pressure.
A thorough analysis of these bonding properties, based on a quantum mechanical description, has been given by Anderson [47, 48, 49] and Abell [50]. In their description, that forms the basis of the tight binding models, the electronic wave function is approximated as a sum of localized atomic orbitals. Abell showed that for a regular lattice, i.e. with an identical environment for each atom, and within the assumption that the overlap integral for orbitals on different atoms is non-vanishing only for nearest neighbours, the binding energy per atom is given by:
Eb=12Z(qVR(r)+bVA(r)) (1)
where is the number of nearest neighbours, is the number of valence electrons per atom, is a two-body potential describing the core repulsion, is a two-body attractive potential, and is the so-called bond order, a many-body term dependent on the local environment of the atoms. Abell also showed that the coordination dependence of is fairly well approximated by:
b=b(q,Z)=α(q)Z−1/2 (2)
with a function of , specified in Ref. [50]. Assuming exponential functions and , with , , , and fitting parameters, as a reasonable approximation for overlapping atomic orbitals from atoms at distance , and defining , some algebra leads to a total binding energy given by:
Eb = Bα(q) S−12S(Bα(q)qAS)1S−1ZS−22(S−1) (3) = CZS−22(S−1)
and an equilibrium nearest neighbour distance given by:
req=1θ−λln(qAS√ZBα(q))=12(θ−λ)lnZ+C′ (4)
where and are constants. Eq. 3 implies that for high coordination structures (close packing) are favoured (metals), whereas for the dimer will be the most stable structure (extreme case of covalent bonding). As, in general, the repulsion falls off (much) faster than the attraction, i.e. , Eq. 4 implies that is monotonically increasing with coordination. Combining Eqs. 3 and 4 yields a simple relation between and , namely .
In principle BOPs are based on the above bonding ideas. However, the transferability to different types of structures and materials has been greatly enhanced by a quite reasonable extension in the functional form of the bond order . The simplest bond order for a bond according to a BOP in the style of Tersoff [51] and Brenner [52] reads:
bij=α⎛⎝1+∑k≠i,jG(θijk)⎞⎠ϵ (5)
where the sum runs over the nearest neighbours other than of atom , is an adjustable function of the bond angles and is a negative exponent but not necessarily -1/2. Taking a constant and yields , i.e. one recovers the functional form Abell found for (Eq. 2). This form includes the effect of bond angles in a natural way, and has the ability to fit a large set of data quite well, explaining the success of BOPs.
### 2.2 Lcbopi
The main innovative feature of LCBOPI [39] concerns the treatment of the LR van der Waals interactions. One of the challenges here is to add LR interactions which describe not only the interlayer graphitic binding but also the rather strong -bond repulsion in graphite for decreasing interlayer distance without paying a price in the accuracy of the covalent binding properties. A correct description of these interactions requires a LR potential, that is repulsive in the distance range corresponding to the second nearest neighbours (in diamond and graphite). In the LCBOP-family, to get the right equilibrium lattice parameter, this extra repulsion has been compensated by a somewhat stronger attractive part of the covalent interaction, achieved by an appropriate parametrisation of the SR potential. This is schematically illustrated in Fig. 1.
Another feature of LCBOPI is that it contains a reasonable, physically motivated interpolation scheme for the conjugation term to account for a mixed saturated and unsaturated environment. In this approach each atom supplies a number of electrons to each of its bonds with neighbouring atoms according to a certain distribution rule, the total sum being equal to the valence value 4 of carbon. The character of a certain bond , and its conjugation number , a number between 0 and 1 quantifying effects beyond nearest neighbours, is determined by the sum of the electrons supplied by atom and atom . The interpolation model is further illustrated in Fig. 2.
### 2.3 Lcbopi+
The potential LCBOPI is given by LCBOPI supplemented with torsion interactions and a correction of the angle dependent part of the bond order for configurations involving low coordinations and small angles. Similar modifications were also included in the REBO potential [53], although the torsion term contains a significant difference. For LCBOPI, following the results of ab-initio calculations, the shape of the torsion energy curve as a function of the torsion angle depends on conjugation, whereas for the REBO potential the curves for a double and a graphitic bond are equally shaped but scaled (see top panel of Fig. 20). Details on LCBOPI are given in the appendix A of Ref. [54] and in Ref. [55].
## 3 The phase diagram of carbon at very high pressures and temperatures
In this section we give a review of experimental and theoretical works aimed at determining the phase behaviour of carbon at high temperatures and pressure. We follow a “historical” approach, starting from the beginning of the twentieth century, up to the most recent results coming from experiments and computer simulations. A historical approach may give a better understanding why certain issues have been, and in some case still are, controversial. After setting the stage (with a particular attention to the ideas about the sign of the slope of the diamond melting curve and the long debated issue of the position and nature of the graphite melting curve), we focus on the topic of the LLPT for carbon.
### 3.1 The history of carbon phase diagram
One of the earliest phase diagrams of carbon appeared at the beginning of the twentieth century, and is due to H. Bakhuis Roozeboom [56], who estimated the phase behavior of carbon on the basis of thermodynamic arguments. Of the two solid phases, diamond was recognized to have a slightly greater vapor pressure at a given temperature. The temperature of the graphite/liquid/vapor triple was believed to be around 3000 K. In 1909 Tamman [57] postulated the existence of a region where graphite and diamond are in pseudo-equilibrium. The existence of this pseudo-equilibrium region was at the basis of the method of synthesizing diamond starting from carbon saturated solutions of molten iron, silver, or silicates. In 1938, Rossini and Jessup [58] of the U.S. Bureau of Standards used accurate thermodynamic data to estimate that at 0 K the lowest pressure at which diamond would be stable against graphite is around 1.3 GPa, and around 2 GPa at 500 K. In 1939, the Russian scientist Leipunskii [59] published a review of the problem of diamond synthesis. On the basis of thermodynamic data, he suggested that the melting curve of graphite might be at about 4000 K, with possibly some increase with pressure. This value for the melting of graphite was rather well verified the same year by Basset [60], who established the graphite/liquid/vapor triple point to be at about 11 MPa and 4000 K. In that same publication, Basset reported on a rather pressure independent melting temperature of graphite at K, from atmospheric pressure up to 0.1 GPa. In 1947 Bridgman [61] addressed the problem of extrapolating the graphite/diamond coexistence curve beyond the region where it can be estimated from known physical properties (4 GPa/1200 K). He concluded that there was a possibility that at higher temperatures the rate of increase of P with T along the curve would decrease. This hypothesis was later supported by Liljeblad [62] in 1955, while Berman and Simon [63] in the same year came to the conclusion that the best extrapolation would be a straight line. Experiments that could decide this issue were started by Bundy and coworkers in 1954, when they accomplished diamond synthesis by activating the graphite-to-diamond reaction with the use of different solvent-catalyst metals. The relevant experimental data were published only much later [64, 65], and are compatible with the Berman-Simon straight line extrapolation.
Bundy and his group made also extensive experiments on graphite melting at pressures much higher than the graphite/liquid/vapor triple point. The determination of the graphite melting curve is an experimental challenge for several reasons. First of all, to reach pressures as high as 10 GPa, the sample must be in direct contact with a solid container and, because the melting temperature are so high, this container must be made of a material that is as refractory and inert as possible (Bundy chose boron nitride, pyrophyllite, MgO and diamond powder). In addition, both the heating of the sample and the observations of the high-pressure/high-temperature phase must be carried out very rapidly, before the wall material can melt or react with the carbon sample. The experiments were performed by discharging an electrical capacitor through the sample (this procedure is known as flash heating), and by monitoring the current through, and the voltage across it by means of a two-beam oscilloscope. The discharge circuit was designed to have energy insertion in the sample within a few milliseconds. The interpretation of such experiments, is rather sensitive to the assumed pressure and temperature dependence of the material under study and on the assumption that the pressure of the graphite specimen during rapid heating is the same as in a quasi-static process. With these assumptions, Bundy’ s experiments gave a graphite melting curve as shown in Fig. 3. A maximum melting temperature of about 4600 K was detected in the region of 6 GPa to 7 GPa. The presence of a region with a negative dd along the melting curve indicates that, at those pressures, the density of the liquid at the melting temperature is greater than that of the solid.
Interrupting for a moment the historical order of events, we note that, throughout the past century, different experiments located the graphite melting curve at rather different temperatures [66, 60, 67, 68, 65, 69, 70, 71, 72, 73, 74, 75]. At low pressure, the melting temperature (T) was found at values ranging from to K. Asinovskii et al. [76] pointed out the non negligible dependence of graphite on the heating rate of the sample. Specifically, heating times of the order of 10 s [70, 72] yielded estimates of K; heating times of the order of 10 s [71, 74] suggested K; finally experiments with heating times of the order of one second [60, 69] were consistent with the assumption that K. In ref [76], after a thorough discussion of the experimental methods, the authors recommended that only data coming from experiments with heating time of the order of seconds or more should be accepted. This implied that most of the available data on graphite melting had to be reconsidered and that the question of the position and the shape of the melting curve is still open. On the basis of a series of laser induced slow heating experiments [76] (i.e. heating times of the order of one second), Asinovskii et al. proposed the triple point vapor/liquid/graphite at K and 0.1 MPa (i.e. atmospheric pressure), in clear contradiction to the commonly accepted values [73] of K and 10 MPa. The next year the same authors [77] published results concerning the position of the graphite melting curve. With ohmic heating of graphite samples at heating rates of about 100 K/minute, they found K at 0.25 MPa (typically, samples melted after one hour of steady heating).
Coming back to Bundy’s work, during the experiments on graphite melting Bundy and his group also investigated the graphitization of diamond by flash-heating under pressure. Small diamond crystals where embedded in the graphite sample, pressurized and then flash-heated. Experiments indicated that there is a sharp temperature threshold at which the diamond crystals completely graphitized. This threshold is a few hundreds degrees lower than the graphite melting curve.
Attempts to obtain direct (i.e. without resorting to a catalyst material) conversion of graphite into diamond by the application of high pressure date back to the beginning of the twentieth century. Success came only in 1961, when De Carli and Jamieson [78] reported the formation and retrieval of very small black diamonds when samples of low-density polycrystalline graphite were shock compressed to pressures of about 30 GPa. Later in 1961 Alder and Christian [79] reported results on the shock compression of graphite that were in substantial agreement with those of De Carli and Jamieson.
Bundy [80] achieved direct conversion of graphite into diamond by flash-heating graphite sample in a static pressure apparatus, at pressures above the graphite/diamond/liquid triple point. The threshold temperature of the transformation was found several hundred degrees below the melting temperature of the graphite, and decreasing at higher pressures. The phase transition was revealed by a sharp drop in the electrical conductivity of the samples (that were retrieved as pieces of finely polycrystalline black diamond).
By linking his own results with earlier experimental and theoretical findings, Bundy [80] proposed in February 1963 a phase diagram of carbon at high pressures that is illustrated in Fig. 3. The diamond melting curve was believed to have negative slope by analogy with the other Group IV elements [81, 82]), and on the basis of evidence collected during the experiments of Alder and Christian [79].
In 1973 Van Vechten [83] predicted the phase diagram of carbon by rescaling the behavior of other Group IV elements that are experimentally more accessible, using the electronegativity as a scale parameter. In 1979 Grover [84] calculated a phase diagram by using a phenomenological equation of state for the description of various solid and liquid phases of carbon. He used physically motivated approximations for the free energies of the various phases, with parameters adjusted to match the available data on the equations of state. He concluded that, at all pressures, diamond transforms, before melting, into a solid metallic phase.
On the basis of experimental evidence [85], in 1978 Whittaker [1] proposed the existence of a novel crystalline phase for elemental carbon, called “carbyne”. The stability region of carbyne is sketched in Fig. 4) and the structure of this phase (though expected in different allotropes) is generally that of a chains of alternated single and triple bonds, i.e. CC, arranged in a hexagonal array bundled by dispersion interactions. The existence of a carbyne form was later questioned by Smith and Buseck [2], who claimed that all the experimental evidence could also be accounted for by the presence of sheet silicates. This dispute continued to this day: the experimental evidence for the existence of carbyne is still being debated.
In recent years, the experimental effort has focused on the collection of reliable data at even higher pressures, and on the investigation of the properties of the different phases of carbon at high temperatures and pressures. This challenging task has been faced both with experiments and theory. On the experimental side, the development of the diamond-anvil cell [6] for high pressure physics has made it crucial to know the range of stability of diamond under extreme conditions. The availability of high-energy pulsed laser sources led to new tools for heating up samples at very high temperatures (above the graphite melting curve) [86]. These techniques were immediately applied to the determination of the properties of liquid carbon (i.e. whether it is a conducting metallic liquid or an insulator). Unfortunately, due to the difficulties in interpreting the results of these experiments, the nature of the liquid state of carbon is still not characterized experimentally.
On the theoretical side, the appearance of ever more powerful computers made it possible to use electronic density-functional (DF) theory [87, 88] to predict the properties of materials under extreme conditions. In 1983 Yin and Cohen [89] studied the total energy versus volume and the free energies versus pressure for the six possible lattices of carbon (fcc, bcc, hcp, simple cubic, -tin, diamond). The study was carried out by using ab initio pseudopotential theory (this permits the investigation of the properties of the atomic system at 0 K). Yin and Cohen found that the calculated zero-pressure volume for diamond is either close to or even smaller than those of the other five phases. This is different from what is observed for the other group IV elements, Si and Ge, and defies the common notion that diamond is an open structure and should have higher specific volume than the close packed solid structures. The relatively dense packing of diamond would inhibit the phase transformations at high hydrostatic pressures that are observed for heavier group IV elements. In addition, it suggested a revision of the other common notion that the diamond melting curve should have negative slope, something that is to be expected when a liquid is denser than the coexisting solid. Yin and Cohen also found that, at a pressure around 2300 GPa, diamond converts to a simple cubic (sc) phase. This work was later extended [90, 91, 92] to consider also complex tetrahedral structures. It was found that a distorted diamond structure called BC-8 was stable versus diamonds at pressures above 1000 GPa (see Fig. 4).
In 1984 Shaner and coworkers [93] shock compressed graphite and measured the sound velocity in the material at shock pressures ranging from 80 to 140 GPa, and corresponding shock temperatures ranging from 1500 to 5500 K. They measured velocities close to those of an elastic longitudinal wave in solid diamond. These velocities are much higher than those of a bulk wave in a carbon melt. Since no melt was detected at pressures and temperatures well above the graphite/diamond/liquid triple point, the diamond melting curve should, according to these results, have a positive slope. In 1990 Togaya [94] reported experiments in which specimens of boron-doped semiconducting diamond were melted by flash-heating at pressures between 6 and 18 GPa: these experiments provided clear indications that the melting temperature of diamond increases with pressure.
In the same year ab-initio molecular dynamics (MD) studies [95] clearly showed that, upon melting diamond at constant density, the pressure of the system increases. These results imply that, at the densities studied, the slope of the melting curve of diamond is positive. The shape of the diamond melting curve has interesting consequences for the theory of planetary interiors. Given our present knowledge of the phase diagram of carbon and the existing estimates for the temperatures and pressures in the interior of the outer planets Neptune and Uranus, as well as in the Earth mantle, one might conclude that in a large fraction of these planetary interiors the conditions are such that diamond should be the stable phase of carbon [96]; diamonds could then be expected to occur wherever the carbon concentration is sufficiently high. In section 5 we show that, when only homogeneous nucleation is considered, our modelling predict that the driving force for diamond nucleation is missing in giant planet interiors. In 1996 Grumbach and Martin [97] made a systematic investigation of the solid and liquid phases of carbon over a wide range of pressures and temperatures by using ab initio MD. These authors studied the melting of the simple cubic and BC-8 solid phases, and investigated structural changes in the liquid in the range 400-1000 GPa. They observed that the coordination of the liquid changes continuously from about four-fold to about six-fold over this pressure range.
In 2004, Bradley et al. [98] reported experiments on laser-induced shock compression of diamond up to 3000 GPa. Through optical reflectivity measurements, they found for the first time direct evidences of diamond melting, at an estimated pressure of GPa, and temperature K.
Fig. 4 summarizes the information about phase diagram of carbon at the time when the present research was started.
### 3.2 Carbon phase diagram according to LCBOP
Methods We performed Monte Carlo simulations on the LCBOPI model of carbon [39, 46] to estimate the properties of the liquid, graphite, and diamond phases of carbon. Coexistence curves were determined by locating points in the diagram with equal chemical potential for the two phase involved. For this purpose, we first determined the chemical potential for the liquid, graphite, and diamond at an initial state point ( 10 GPa, 4000 K). This state point is near the estimated triple point[99]. Subsequently, the liquid-graphite, liquid-diamond, and graphite-diamond coexistence pressures at 4000 K were located. In turn, these coexistence points served as the starting point for the determination of the graphite melting line, the diamond melting line, and the graphite-diamond coexistence curve, obtained by integrating the Clausius-Clapeyron equation (a procedure also known as Gibbs-Duhem integration) [100]: where is the difference in specific volume, and the difference in molar enthalpy between the two phases.
We proceeded by first determining the Helmholtz free energy at a given density and temperature by thermodynamic integration and subsequently calculating the chemical potential using the procedure described in Ref. [101]. Coexistence at a given is found at the where the different cross.
For all phases, the Helmholtz free energy of the initial state point ( 10 GPa, 4000 K) was determined by transforming the system into a reference system of known free energy . The transformation was imposed by changing the interaction potential: . Here, and denote the potential energy function of the LCBOPI and the reference system, respectively. The transformation is controlled by varying the parameter continuously from to . The free-energy change upon the transformation was determined by thermodynamic integration:
F✠ = Fref+ΔFref→✠= (6) = = Fref+∫10dλ⟨Uref−U✠⟩λ
The symbol denotes the ensemble average with the potential .
As reference system for the liquid we chose the well-characterized Lennard-Jones (12-6) system, whilst the reference system for both diamond and graphite was the Einstein crystal. General guidelines for these kind of calculations are given in [102, 101], while a full description of the strategy adopted for the present systems is given in [55]. The ensemble averages needed for the thermodynamic integration were determined from Monte Carlo (MC) simulations of a 216-particle system in a periodically replicated simulation box. For simulations of the graphite phase, the atoms were placed in a periodic rectangular box with an initial edge-size ratio of about . For the liquid phase and diamond a periodic cubic box was used.
From the Helmholtz free energy to the chemical potential The chemical potential along the K isotherm was obtained by integrating from the initial state point a fit, , through simulated state points along the 4000 K isotherm. Here, is the number density, and , , and are fit parameters. This yields for the chemical potential [101]:
βμ(ρ)=βF✠N+β(aρ✠+b lnρρ✠+b+c(2ρ−ρ✠)) (7)
Here, denotes the number density at the initial state point, the number of particles, and , with the Boltzmann constant.
Calculated coexistence curves The equilibrium densities at the initial state point ( 10 GPa, 4000 K) were 3.425 for diamond, 2.597 for graphite, and 2.421 for the liquid. Three configurations at the equilibrium volume were then chosen as starting state point for the free energy calculation.
The integrals related to the reference system transformation (Eq. 6) were evaluated using a 10-point Gauss-Legendre integration scheme. Fig. 5 shows the integrand versus . The smooth behaviour of the curves indicates that there are no spurious phase transitions upon the transformation to the reference system (the absence of such transitions is a necessary condition for using this method). At the initial state point ( 10 GPa, 4000 K), the calculated free energies() where , , and , for graphite, diamond, and the liquid, respectively.
Fig. 6 shows the calculated state points along the 4000 K isotherms for the three phases, along with the fitted curves. The fit parameters are listed in Table 1. Employing subsequently Eq. 7 we obtained the calculated chemical potential along the 4000 K isotherm for the liquid, graphite, and diamond phase.
The intersections of the chemical potential curves yield the graphite/liquid coexistence at 6.72 0.60 GPa ( ), and the graphite/diamond coexistence at 15.05 0.30 GPa ( ). The third intersection locates a diamond/liquid coexistence at 12.75 0.20 GPa ( ). Even though both diamond and the liquid are there metastable, the Clausius-Clapeyron integration of the diamond melting curve can be started at the metastable coexistence point at 4000K. Starting from the three coexistence points at 4000 K, the coexistence curves were traced by integrating the Clausius-Clapeyron equation using the trapezoidal-rule predictor-corrector scheme [100]. The new value of the coexisting at a given was taken when two iterations differed less than 0.01 GPa, this being the size of the single uncertainty in the calculation of dd. Typically this required 2-3 iterations.
The calculated phase diagram in the plane is shown in Fig. 7 for the low pressure region, and in Fig. 8 for the pressures up to 400GPa. Tab. 2 lists the densities of selected points on the coexistence curves. The three coexistence curves meet in a triple point at 16.4 0.7 GPa and 4250 10 K.
The graphite/diamond coexistence curve agrees well with the experimental data. In the region near the liquid/graphite/diamond triple point that has not been directly probed in experiments, the graphite/diamond coexistence curve bends to the right, departing from the commonly assumed straight line. Analysis of our data shows this is mainly due to the rapid reduction with increasing pressure of the interplanar distance in graphite at those premelting temperature. This causes an enhanced increase of the density in graphite, yielding a decrease of .
Table 2 shows the melting enthalpy for graphite and diamond. These are calculated as the difference in enthalpy between the solid and the liquid at coexistence. Our calculated melting enthalpies of graphite are significantly lower than the values of 110 kJ/mol that were reported in recent shock-heating melting experiments [73, 74]. Nonetheless our values retain the feature of being rather constant along the graphite melting curve. To our knowledge, no experimental data have been reported for the melting enthalpies of diamond. Note, that they monotonically increase with temperature.
The calculated graphite melting temperature is monotonically increasing with pressure and is confined to small temperature range around 4000 K. In contrast to data inferred from experiments it shows no maximum and is at a somewhat lower temperature. In agreement with the experiments the coexistence temperature is only slowly varying with pressure. Inspection reveals that this behavior is due to a limited variability of the melting enthalpy, and a similar bulk modulus for liquid and graphite yielding a volume change upon melting that is almost constant along the melting curve.
The sign of the slope of the diamond melting curve is consistent with the available experimental data [93, 73] (see Fig. 8). When compared to the diamond melting curve of the BrennerI model [104], the LCBOPI diamond melting curve has a steeper slope yielding significantly higher temperatures for the diamond melting curve. Recently, the melting curve of diamond in a range up to 2000 GPa has been studied by ab initio MD simulations using density functional theory. Wang et al. [105] determined the relative stability of the diamond and liquid phase by evaluating the free energy of both phases. Correa et al. [106] determined the melting temperature using a “two phase” simulation method, where the system initially consists of a liquid and a diamond structure that are in contact. Subsequently the melting temperature is estimated by locating the temperature at which the system spontaneously evolves towards a liquid or a crystalline structure. In both ab initio MD studies it was found that the diamond melting curve shows a maximum; around 450 GPa [106] or 630 GPa [105] 444The difference between these two values gives a hint on the uncertainties related to the two different methods used for calculating coexistence, given that the DF-MD set-up is quite similar in the two works. Subsequent laser-shock experiments [107] provided data consistent with this observation, indicating a negative melting slope most probably in the region of 300-500 GPa. When comparing the LCBOPI diamond melting curve, that monotonically increases with pressure, to the ab initio MD results of Refs. [105, 106] we see a significant deviation from 200 GPa onwards. This might be attributed to an incorrect description of the liquid structure at high compression. Indeed, LCBOPI has not been validated against high density structures with coordination beyond four. These are typical configuration that might become more dominant in the pressure region beyond 200 GPa.
## 4 Existence of a liquid–liquid phase transition?
### 4.1 History of the LLPT near the graphite melting line
Analysis of experimental data The possibility of a LLPT in liquid carbon was first investigated by Korsunskaya et al. [36], who analysed data on the graphite melting curve proposed by Bundy [65], (those data showed a maximum melting temperature at 6.5 GPa). By fitting the data from Bundy into the original two levels model of Kittel [34] and postulating the existence of two liquids, Korsunskaya et al. found the critical temperature of the LLPT. The model is fitted with three points on the graphite melting curve, with the respective derivatives, and with the heat of melting at one selected pressure. The fitting procedure gives an estimate for the critical pressure of GPa and for the critical temperature of the searched transition at 3770 K, i.e. below the melting temperature. The fitted value for the entropy of freezing is the same for the two liquids, thus implying a vertical slope (dd) of the coexistence curve (in the metastable liquid region just below the critical temperature)
On the basis of these results, the authors were able to calculate also the diamond melting curve: they predicted it to have a negative slope, in accordance with the commonly accepted interpretation of the experiments of Alder and Christian [79]. Note that the slope of the graphite melting curve, and the slope of the diamond/graphite coexistence, as extracted from Bundy’s data [80, 65], together with the densities of the phases obtained by fitting to the two levels model implied (via Clausius-Clapeyron equation) a negative slope of the diamond melting curve. Different values of the slopes of the graphite boundary curves, and of the densities of the phases can yield rather different slope of the diamond melting curve.
Consistent with the slope of the fitted graphite melting curve, the low density liquid is predicted less dense than the coexisting graphite, and the high density liquid more dense than the coexisting graphite. The nature of the two liquids was predicted as follows: at low pressure graphite melts into a liquid of neutral particles that interact predominantly through dispersion (London) forces. Upon increasing pressure the liquid would transform into a metallic close packed liquid. No assumptions were made on the local structure.
A semi-empirical equation of state The modern discussion on the LLPT for carbon, starts with the elaboration of a semi-empirical equation of state for carbon, valid also at high and , by van Thiel and Ree [108, 99]. This equation of state was constructed on the basis of experimental data and electronic structure calculations. It postulated the existence, in the graphite melt, of a mixture of an and an liquid. By assuming the model of pseudo-binary mixture for the description of the mixing of the two liquids [38], Van Thiel and Ree showed that fitting their empirical equation of state to the graphite melting points of Bundy [65], they predict a graphite melting curve that shows a maximum with a discontinuous change of the slope, so that a first order LLPT arises. On the other hand, if they fit their model to the data from Ref. [109], the predicted of the LLPT drops below the melting curve and the transition between the two liquids becomes continuous in the stable liquid region. As pointed out by Ponyatovsky [110] the expression for the mixing energy of the two liquid as proposed by van Thiel and Ree in [108, 99] involves two ambiguities. Firstly, extrapolating the coexistence curve between the two liquids at atmospheric pressure, the coexistence temperature would be K: this would imply that the liquid (and the glass) would be more stable than the at ambient pressure up to very high temperatures, which is in disagreement with the experimental data. Furthermore, the mixing energy is proposed to have a linear dependence on , so that, when , also the mixing energy would tend to zero, i.e. at zero temperature the regular solution would become an ideal solution. This would be rather unusual.
Experimental evidence from the graphite melting curve Using flash-heating experiments Togaya [74] determined the melting line of graphite and found a maximum in the melting curve at GPa. This author fitted the six experimental points with two straight lines: with positive slope at pressures lower than , with negative slope at pressures higher than . The apparent discontinuity at the maximum would imply the presence of a triple point graphite/ low-density-liquid (LDL) / high-density-liquid (HDL), as a starting point of a LLPT coexistence curve.
Prediction of a short-range bond-order potential In Ref. [103] Glosli and Ree reported a complete study of a LLPT simulated with the ‘BrennerI’ bond-order potential [52] in its version with torsional interactions [111]. The authors simulated in the canonical (NVT) ensemble several samples at increasing densities at eight different temperatures. By measuring the pressure, they show the familiar van der Waals loop betraying mechanical instability over a finite density range. Using the Maxwell equal-area construction, the authors calculated the LLPT coexistence curve, ending in a critical point at K and GPa. The lowest temperature coexistence point was calculated at K and GPa. The LDL/HDL coexistence curve should meet the graphite melting curve at its maximum, but unfortunately the BrennerI potential does not contain non bonded interactions, thus it can describe neither bulk graphite nor its melting curve. To overcome this deficiency, the authors devised an ingenious perturbation method. Assuming constant slope of the negative sloped branch of the graphite melting curve (the authors adopted the graphite melting curve measured by Togaya [74]) and fixing the graphite/diamond/HDL triple point at a value taken from the experimental literature, they give an estimate of the graphite/LDL/HDL triple point, at K and GPa. The LDL was found to be mainly two-fold () coordinated with a polymeric-like structure, while the HDL was found to be a network forming, mainly four-fold, () liquid. Following the predictions of this bond-order potential, the coordinated atoms would be completely avoided in the liquid. The authors identified the reason in the presence of torsional interactions. In fact, the increase in density demands an increase in structures with higher coordination than the , which is entropically favored at low densities. The single bonds of the structures can freely rotate around the bond axis, while bonds between sites are constrained in a (almost) planar geometry by the torsional interactions: this implies a low entropy for a liquid dominated by sites. This low entropy would eventually destabilize the sites towards the . To prove this conjecture, the authors calculated two relevant isotherms in the original version of the potential, without torsional interactions, finding no sign of a LLPT. Since some torsional interactions are definitely needed to mimic the double bond reluctancy to twist, the authors concluded that the LLPT predicted by the Brenner bond-order potential with torsion is more realistic than its absence when torsional interactions are switched off.
Tight binding calculations [112] showed no evidence of van der Waals loops at some of the temperatures analyzed in Ref. [103]. As Glosli and Ree note, the tight binding model used in [112] is strictly two-center, thus the torsional interactions cannot be described.
An ab initio study of the LLPT In Ref. [45], Wu et al. reported a series of NVT-CPMD simulations at 6000 K from density 1.27 to 3.02 10 kg/m, in a range where the BrennerI potential showed the first order LLPT at the same . No sign of a van der Waals loop was found: in contrast to the BrennerI results of the previous paragraph, two approaching series starting from the lowest and the highest density, were found to meet smoothly at intermediate densities. Looking for the reasons of the failure of the BrennerI potential, the authors calculated, with the same functional used in the CPMD simulations, the torsional energy of two model molecules. One, (CH)C=C(CH), was chosen so that the bond between the two central atoms represents a double bond in a carbon network: two sites are bonded each to two sites; the peripheral hydrogens are needed to saturated the atoms and are intended to have no effect on the central bond. The second molecule, (CH)C-C(CH) is a portion of a completely coordinated network: in the bond-order language, the central bond is conjugated. The two molecules were geometrically optimized in their planar configurations and then twisted around the central bond axis in steps of . In each configuration the electronic wave function was optimized, without further relaxations, to give the total energy, that was compared to the planar configuration total energy. The difference is the torsional energy. The DF calculations found a surprising picture: while the double bond torsional energy was only slightly overestimated by the BrennerI potential at intermediate angles, the DF torsional energy for the conjugated bond showed a completely different scenario compared to the classical prediction. It shows a maximum at , while the planar and orthogonal configuration have basically the same energy. For the BrennerI potential, the torsional energy in this conjugated configuration is monotonically increasing with the torsion angle, just as for the double bond configuration. On average, considering that the conjugated configuration would be characteristic of a mainly coordinated liquid, the torsional interactions are enormously overestimated by the classical potential. As a further illustration, the authors tried to lower torsional energy of the conjugated bond in the classical potential, by tuning the proper parameter, and found a much less pronounced LLPT. Note that the functional form of the torsional interactions for the BrennerI potential cannot reproduce the DF data mentioned here. Wu et al. concluded that “[the] Brenner potential significantly overestimates the torsional barrier of a chemical bond between two- and three-center-coordinated carbon atoms due to the inability of the potential to describe lone pair electrons”; and: “[the] Brenner potential parameters derived from isolated hydrocarbon molecules and used in the literature to simulate various carbon systems may not be adequate to use for condensed phases, especially so in the presence of lone pair electrons”. In the next section we show that the conclusion of Wu et al. is not necessarily true for all BOPs; indeed, LCBOPI, the carbon bond-order potential proposed by Los and Fasolino (see section 2), includes a definition of the torsional interaction which is able to reproduce relevant features of liquid carbon, as they are described by DF-MD.
### 4.2 Ruling out the LLPT in the stable liquid region via LCBOP
We have already indicated that the change of the structure of the liquid along the graphite and diamond melting curve is related to the slope of the melting curve. More importantly, it plays also a crucial role in the nucleation of diamond in liquid carbon. The latter will be further discussed in the next section.
The calculated melting curves of the LCBOPI model for carbon up to 400 GPa provide strong evidence that there is no LLPT in the stable liquid phase. One indication is the smoothness of the slopes of the melting curves. A further argument lies in the structure of the liquid near freezing. Below we discuss this in more detail.
The calculated phase diagram (Figs. 7 and 8) does not show the sharp maximum in the graphite melting line that was inferred from the calculated first-order LLPT for the BrennerI bond-order potential[103]. As we mentioned in the previous section, subsequent DF-MD simulations of liquid carbon [45, 46] indicate that the BrennerI LLPT is spurious: it originates from an inadequate description of the torsional contribution to the interactions. We have extended the calculation of the graphite melting curve of LCBOPI towards higher pressures into the region where both graphite and the liquid are metastable with respect to diamond. It is plotted as a dashed curve in Fig. 8 that shows the same trend as at lower pressures. Hence, the calculated slope of the graphite melting curve is incompatible with the existence of a LLPT in this region of the carbon phase diagram.
In order to further analyze the nature of the liquid, we determined several structural properties of the liquid near the melting curve where we also explored the diamond melting curve. Fig. 9 shows the coordination fraction in the liquid along the coexistence curves up to 400 GPa, as function of temperature, pressure and density, with a linear scale in density. The dashed curve is the calculated graphite/diamond/liquid triple point. Along the graphite melting curve, the three-fold and two-fold coordination fractions remain rather constant, with the four-fold coordination slightly increasing to account for the increase in density. Along the diamond melting curve the three-fold coordinated atoms are gradually replaced by four-fold coordinated atoms. However, only at (3.9 10 kg/m, 300 GPa, and 10500 K) the liquid has an equal fraction of three-fold and four-fold coordinated atoms. The change of dominant coordination is rather smooth. Moreover, we have verified that it is fully reversible showing no sign of hysteresis in the region around the swapping of dominant coordination. We note, that these results contradict the generally assumed picture (see e.g. Ref. [99]) that diamond melts into a four-fold coordinated liquid. Our calculations suggest that up to 300 GPa the three-fold coordination dominates.
The interrelation between three and four-fold sites, was further investigated calculating the partial radial distribution functions () of the liquid at 300 GPa, and 10500 K. Partial radial distribution functions are defined as the probability of finding a -fold site at a distance from a -fold site; the total radial distribution function is recovered by: . We show the results in Fig. 10; we focus on the three predominant curves, describing the pair correlations between three-fold atoms (), between four-fold atoms (), and the cross pair correlation between three- and four-fold sites (). Disregarding the rather pronounced minimum in correspondence of the dip around 2 Å of the and the , the similarity of three curves at all distances is striking. The two sites are almost undistinguishable: in case of a tendency towards a phase transition, one would expect some segregation of the two structures. In contrast, looking at distances within the first neighbours shell, a three-fold site seems to bond indifferently to a three- or a four-fold site, and viceversa. Furthermore, the partial structures up to the third, quite pronounced, peak at 4.5 Å, are almost the same for these three partial radial distribution functions.
We determined the properties of the metastable liquid in the stable diamond region. Fig. 8 shows the liquid state points (crosses) that exhibit an equal number of three and four-fold coordinated atoms. It ranges from the high-pressure high-temperature region where the liquid is thermodynamically stable down into the diamond region, where the liquid is metastable for the LCBOP. The circles indicate state points in which the LCBOP liquid freezes in the simulation. Enclosed by the two set of points lies what we baptized diamond-like liquid. This is a mainly four-fold coordinated liquid with a rather pronounced diamond-like structure in the first coordination shell and was discussed in [46]. This suggests that a (meta)stable liquid with a dominantly four-fold coordination may only exist for pressures beyond 100 GPa and could imply that the freezing of liquid into a diamond structure might be severely hindered for a large range of pressures beyond the graphite/diamond/liquid triple point. In Ref. [46] it is also pointed out that at 6000 K the equation of state shows a change of slope around the transition to the four-fold liquid. At even lower temperature this feature becomes more and more evident, but for temperatures lower than 4500 K the liquid freezes into a mainly four-fold coordinated amorphous structure. This observation is consistent with quenching MD simulations [113, 114] to obtain the tetrahedral amorphous carbon. In those simulations a mainly three-fold liquid freezes into an almost completely four-fold amorphous.
Recent fully ab-initio study of the diamond melting line [105, 106] predicted a maximum at pressures beyond the maximum pressure (400 GPa) we explored with our potential. The maximum implies a liquid denser than diamond at pressure higher than the pressure at which the maximum appears. The authors of both works analyzed the structure of the liquid around this maximum, finding no sign of abrupt change in density and/or coordination. This points towards excluding a LLPT between a four-fold and a higher-fold coordinate liquid; rather, a smooth transformation towards a denser liquid is always observed.
## 5 Diamond nucleation
Our knowledge of the phase diagram of “LCBOPI carbon” allows us to identify the regions of the phase diagram where diamond nucleation may occur. We studied the homogeneous nucleation of diamond from bulk liquid, by computing the steady-state nucleation rate and analyzing the pathways to diamond formation. On the basis of our calculations, we speculate that the mechanism for nucleation control is relevant for crystallization in many network-forming liquids, and also estimate the conditions under which homogeneous diamond nucleation is likely in carbon-rich stars and planets such as Uranus and Neptune.
Steady-state nucleation rate Most liquids can be cooled considerably below their equilibrium freezing point before crystals start to form spontaneously in the bulk. This is caused by the fact that microscopic crystallites are thermodynamically less stable than the bulk solid. Spontaneous crystal growth can only proceed when, due to some rare fluctuation, one or more micro-crystallites exceed a critical size (the “critical cluster”): this phenomenon is called homogeneous nucleation. An estimate of the free-energy barrier the system has to cross in order to form critical clusters and of the rate at which those clusters form in a bulk super-cooled liquid, can be obtained from Classical Nucleation Theory (CNT) [115]. CNT assumes that , the Gibbs free-energy difference between the metastable liquid containing an n-particle crystal cluster and the pure liquid, is given by
ΔG(n)=S(n)γ−n|Δμ|, (8)
where is the area of the interface between an n-particle crystallite and the metastable liquid, is the liquid-solid surface free-energy per unit area, and the difference in chemical potential between the solid and the super-cooled liquid. The surface area is proportional to , where the factor depends on the shape and the geometry of the cluster (e.g. for a spherical cluster).
The top of the free-energy barrier to grow the crystalline critical cluster is then given by
ΔG∗=cγ3ρ2S|Δμ|2, (9)
where is the number density of the stable phase and indicates the geometrical properties of the growing cluster. From our simulations, we can only determine the product : it is this quantity and the degree of super-saturation (), that are needed to compute the top of the free-energy barrier, and hence the nucleation rate.
CNT relates , the steady-state nucleation rate, i.e. the number of crystal clusters that form per second per cubic meter, to , the height of the free-energy barrier that has to be crossed to nucleate the critical crystal :
RCNT=κe−βΔG(n∗), (10)
where is the top of the free-energy barrier and is the kinetic prefactor. The kinetic prefactor term is defined as
κ=ρLk+,n∗Z (11)
where is the liquid number density, the attachment rate of single particles to a spherical crystalline cluster , with proportional to the jump frequency ( being the atomic jump distance) and the so-called Zeldovitch factor. As the nucleation rate depends exponentially on , a doubling of may change the nucleation rate by many orders of magnitude.
Because of the extreme conditions under which homogeneous diamond nucleation takes place, there have been no quantitative experimental studies to determine its rate. Moreover, there exist no numerical estimates of and for diamond in super-cooled liquid carbon. Hence, it was thus far impossible to make even an order-of-magnitude estimate of the rate of diamond nucleation.
Results We simulate a 2744 particles bulk liquid carbon using periodic boundary conditions, with a cubic box whose edge is 18Å. We make it metastable by undercooling it at constant pressure at two different state points, GPa, K and GPa, K. At both state points, the liquid is super-cooled by 25 below the diamond melting curve, being the melting temperature K and K, respectively.
We evaluate by thermodynamic integration at constant pressure from the melting point ()
Δ(βiμ)=∫βiβM⟨[hS(β)−hL(β)]⟩Pdβ (12)
where , and is the enthalpy per particle of the solid and liquid phase, respectively. We then find: and .
In recent years several authors have been developing methods for studying homogeneous nucleation from the bulk and detecting solid particles within the metastable liquid [116, 117, 118, 119]. Our study on diamond nucleation is based on these works, but it requires various adaptations due to the specificity of the carbon covalent bond [55]. We have already shown that liquid carbon is rather structured below its freezing curve. This leads to the need of building a ”strict” definition of “crystallinity” of a particle, in order to avoid an overestimation of the number of solid particles in the system.
In order to compute the nucleation free energy, we use the biggest crystal cluster as a local order parameter to quantify the transformation from the liquid to the solid. To identify solid-like particles, we analyze the local environment of a particle using a criterion based on a spherical-harmonics expansion of the local bond order. In practice, the present bond-order parameter is based on rotational invariants constructed out of rank three spherical harmonics (). This choice allows us to identify the tetragonal symmetry of the diamond structure, as already described in Ref. [55, 119], and it is also perfectly suited to find particles in a graphite-like environment. Our choice of odd-order of spherical harmonics is due to the fact that both diamond and graphite lattices have odd symmetry upon inversion of coordinates.
In order to define the local order parameter, we start with computing
q3,m(i)=1Zi∑j≠iSdown(rij)Y3m(^% rij) (13)
where the sum extends over all neighbors of particle and over all values of . is the fractional number of neighbours and is a smooth cut-off function, introduced in the context of [55] (see also Section II.A in [40]).
By properly normalizing Eq. 13, we get
q′3,m(i)=q3,m(i)(∑lm=−lq3,m(i)⋅q∗3,m(i))1/2, (14)
being the complex conjugate of .
Next we define the dot product between the normalized function of particle and the same function computed for each of its first neighbors, , and sum them up over all the values:
d3(i,j)=l∑m=−lq′3,m(i)⋅q′∗3,m(j)Sdown(rij). (15)
is a real number defined between -1 and 1: it assumes the value of -1 when computed for both graphite and diamond ideal structures.
Two neighboring particles and are considered to be connected whenever . This value satisfactorily splits the distributions of solid particles belonging to a thermalized lattice and liquid particles as found in a liquid. The histograms that led us to this choice are thoroughly discussed in Refs. [55, 119]. By counting the total number of connections () and plotting the probability distribution of , we define a threshold for the number of connections needed to neatly distinguish between a liquid-like and a solid-like environment: we assume that whenever a particle is solid-like. At this stage, we do not specify any nature of the particle’s crystallinity, whether diamond-like or graphite-like. By means of a cluster algorithm we then define all the solid-like AND connected particles as belonging to the same crystal cluster. After computing the size of each cluster, we use the size of the biggest cluster as the order parameter which describes the phase transition [120].
Once properly identified the biggest crystalline cluster in the system, we use the umbrella sampling technique [121] to measure the free-energy barrier to form a critical cluster at state point . In order to better equilibrate the growing clusters, we implement a “parallel tempering” algorithm similar to the one described in Ref. [122]. We obtain that, at state point , is around 25 for a critical cluster size of . By fitting the initial slope of Eq. 8 to a polynomial function assuming a spherical growing cluster, while imposing the value of the correspondent super-saturation (0.60), the inter-facial free energy is Å J m. The same value of is obtained from the top of the free-energy barrier assuming a spherical cluster shape (Eq. 9) ( Å). We underline the fact that at the chosen thermodynamic conditions, there are no finite size effects, caused by spurious interaction of the critical cluster with its own periodically repeated image.
By knowing the inter-facial free energy in , and assuming the validity of CNT, we estimate the crystal nucleation rate by means of Eq. 10, where we use Eq. 11 to compute the kinetic pre-factor (the atomic jump distance being of the order of the diamond bond distance, Å): sm.
We also use Forward-Flux Sampling (FFS), a relatively recent rare events technique useful to compute the nucleation rate and to study the pathways to nucleation [123, 124, 119], and we measure the crystal nucleation rate at state point . FFS yields an estimate for the nucleation rate that is three orders of magnitude higher than the one estimated by means of Eq. 10. Whilst such a discrepancy seems large, it need not be significant because nucleation rates are extremely sensitive to small errors in the calculation of the nucleation barrier. Two possible reasons for this discrepancy are: 1) if we consider that the standard deviation corresponding to is around of its measured value, we conclude that the nucleation rate is sm; 2) another source of error can be the poor statistics when computing the nucleation rate from molten carbon by means of FFS. This is due to the time consuming calculations of the interaction potential: in our study we are in fact forced to base our results on independent nucleation events. Fig. 11 shows a typical critical cluster at state point obtained in the FFS simulations:
it contains around 110 particles, and it is surrounded by mainly 4-fold coordinated liquid particles. The picture shows two different views of the same cluster: it appears evident that all particles within the bulk are diamond-like, whereas the particles belonging to the outer surface are less connected but still mainly 3-4 fold coordinated.
We then attempt to compute the nucleation rate at state point by means of FFS and, even in rather long simulations, we cannot observe the formation of any crystal cluster containing more than 75 particles. Hence, these calculations suggest that the nucleation rate at state point measured by means of FFS is around zero.
Figure 12 shows a 75 particles cluster containing 3-fold coordinated surface particles surrounding the 4-fold coordinated bulk particles, while embedded in a 2-3 fold coordinated liquid.
As we are unable to grow critical nuclei with FFS, we assume that a system of 2744 particles is too small to accommodate a spherical critical cluster. According to Classical Nucleation Theory (CNT) [115], the crystal nucleation rate depends exponentially on the height of the free-energy barrier (see Eq. 10). The latter is a function of the inter-facial free energy () cube and inversely proportional to the super-saturation () square. Since the super-saturation is quite similar in both state points, the failure of the system to nucleate suggests that the inter-facial free energy should play a major role. In order to estimate the free-energy barrier in state point , as we know the solid number density ( Å) and the chemical potential difference between the liquid and the solid (0.77), we only need to calculate the inter-facial free energy . Thus, in what follows, we focus on methods to estimate at state point .
As a spherical critical cluster does not fit in our simulation box, we prepare a rod-like crystal in a system with a slab geometry: this is a flattened box containing around particles, with lateral dimensions that are some four times larger than its height. The crystal rod is oriented perpendicular to the plane of the slab, it spans the height of the simulation box and is continued periodically. The cross section of this crystal rod is initially lozenge shaped, such that its [111]-faces are in contact with the liquid. The [111]-planes are the most stable ones for the diamond lattice. In fact, macroscopic natural diamonds have often an octahedral shape, with eight [111]-exposed surfaces. Indeed, we find stable [111] surfaces in all but the smallest studied diamond clusters.
At state point clusters grow by the addition of particles to the surface made of mainly [111]-planes. Note that when graphite and diamond structures compete at state point (as shown in Fig. 12), the [0001]-graphite sheets transform into [111] diamond planes.
Fig. 13 represents the top view at state point of a rod-like crystal, formed by 4 [111]-faces and 2 bases as [1-10]-lozenge with the acute angles of =70.52 degrees. We then rewrite Eq. 8 for a rectangular parallelepiped having 4 faces and 2 lozenge-shaped basis
ΔG=4√hρsinθγln1/2−|Δμ|n, (16)
where h is the slab’s height. We then use Umbrella Sampling to compute the initial slope of the free-energy barrier. As Å, we obtain from fitting Eq. 16 that the inter-facial free energy for the lozenge-shaped cluster is Å J m. At the same time, computing the inter-facial free energy of the rod-like crystal at state point gives Å J m, considering the same slab’s height and the same angle .
Now that we have estimates for the inter-facial free energies of the lozenge-shaped clusters at both state points and , we can estimate the ratio between them and find that . As we compare clusters having the same shape, this ratio is presumably not very sensitive to the precise (and, a priori unknown) shape of the cluster shape. As the surface free energy at state point B is appreciably higher than at state point A, the early stages of crystal formation at point are strongly suppressed by the inter-facial free-energy term. Since we know (referred to a hypothetical spherical cluster) and the ratio between the two ’s, we can infer that the “effective” Å 3.50 J m.
This value of the surface free energy is so large that we would indeed have needed a much larger system in order to accommodate the critical cluster at the state thermodynamic conditions. ¿From Eq. 16, we calculate the critical cluster size for the lozenge-shaped parallelepiped and use it to estimate the size of a critical spherical cluster in :
n∗2D=4hρSsinθ(γ)2(Δμ)2. (17)
At state point we find 330 particles. Expressing as a function of the lozenge-shaped parallelepiped one, we get
n∗3D=83πγsinθρSΔμh×n∗2D, (18)
where is the solid number density Å, , and the height of the slab (10 Å). Thus, 1700 particles at state point . To guarantee that the critical cluster does not interact with its own periodic images, its radius should always be less than 25% of the box diameter . A spherical cluster with a radius of 0.25 occupies 7 % of the volume of the box and, as the solid is denser than the liquid, it contains about 10 % of the total number of particles (). Such a large system size is beyond our present computational capacity. In contrast, in the slab geometry we find that the free energy of a lozenge-shaped crystal goes through a maximum at a size of 330 particles, which is much less than the system size (4000 particles).
As and are known, we can now use CNT to estimate in state point . It turns out that, mainly because is 2.5 times larger than , the nucleation barrier in is more than ten times higher than in point , and the nucleation rate is sm.
To understand the microscopic origin for the large difference in nucleation rates in state points and , it is useful to compare the local structure of the liquid phase in both state points. As discussed in section 4.1 above (see also [46, 125]), liquid carbon is mainly 4-fold coordinated at state point ( 3-fold and 4-fold ), whereas at the lower temperatures and pressures of point , the coordination in the liquid resembles that of graphite and is mainly 3-fold coordinated ( 2-fold, 3-fold and 4-fold ).
We can analyze the structure of the crystalline clusters that form in the supersaturated liquid carbon and distinguish graphite-like from diamond-like particles. In an analysis, we use a different order parameter function of the order two spherical harmonics, and particularly sensitive to the graphite planar geometry. is the linear combination of spherical harmonics computed for each particle
q2m(i)=1Zi∑j≠iSdown(rij)Y2m(^r% ij) (19)
where the sum extends over all neighbors of particle . We then sum over all the values and calculate the modulus, . The probability distribution for both and is represented in Fig. 14.
Figure 14 depicts the features of both the smallest ( 20 in both state points and ) and the biggest clusters ( 250 in and 75 in ). We also distinguish among: liquid-like particles (circles), particles belonging to the surface of the largest cluster (squares), particles inside the bulk cluster (diamonds) and particles belonging to the first liquid layer surrounding the largest cluster (triangles). According to our definition, particles belonging to the surface of the cluster are those connected to solid-like particles, but not solid-like themselves. Concerning particles belonging to the first liquid layer surrounding the cluster, they usually display the same behaviour as the ones belonging to the cluster surface, which is not surprising in view of the uncertainty in distinguishing a surface-particle from a first-liquid-layer particle. To neatly distinguish between diamond-like or graphite-like environment, we use as a reference the probability distribution for both bulk diamond (D) and graphite (G) (inset of Fig. 14).
At state point , it is clear that bulk particles belonging to small clusters (bottom-left side) and big clusters (bottom-right side) are mainly diamond-like, as well as particles belonging to the surface of the clusters. In contrast, at state point bulk particles belonging to small clusters (top-left side) show both graphite-like and diamond-like finger-prints. By visual inspection, we note that when clusters grow larger (around 75 particles), particles at the surface tend to be mainly 3-fold coordinated, whereas bulk particles stay 4-fold coordinated, as shown in the top-right side of Fig. 14. The destabilizing effect of the graphitic liquid on the diamond clusters is most pronounced for small clusters (large surface-to-volume ratio): clusters containing less than particles tend to be graphitic in structure, clusters containing up to particles show a mixed graphite-diamond structure (see Fig. 12). It appears that the unusual surface structure of the diamond cluster is an indication of the poor match between a diamond lattice and a 3-fold coordinated liquid.
### 5.1 Consequences for other network forming liquids, carbon-rich stars, Uranus and Neptune
As discussed in the introduction, there are many network-forming liquids that, upon changing pressure and temperature, undergo profound structural changes or even LLPT [29, 23, 126]. Interestingly, our simulations show that the ease of homogeneous crystal nucleation at constant super-saturation from one-and-the-same meta-stable liquid can be tuned by changing its pressure, and thereby its local structure.
Pressures and temperatures that we investigate for the diamond nucleation are in practice impossible to reach in experiments. However, such conditions are likely to be found in several extraterrestrial “laboratories”. Homogeneous nucleation of diamond may have taken place in the atmosphere of carbon-rich binary stellar systems comprising the so-called carbon stars and white dwarfs [127, 128]. Closer to home, it has been suggested that diamonds could also have formed in the carbon-rich middle layer of Uranus and Neptune [96, 129, 130] where, due to the high pressure and temperature, the relatively abundant CH would decompose into its atomic components. In fact, experiments on methane laser-heated in diamond anvil cells [131] found evidence for diamond production. Ab initio simulations [132] also found that hot, compressed methane will dissociate to form diamond. Yet, there is a large discrepancy between the estimates of the pressures (and thus depth in the planet interior) at which the diamond formation would take place. The laser-heating experiments [131] suggested diamond formation at pressure as low as 10–20 GPa (at 2000–3000 K), whereas the ab initio simulations [132] found dissociation of methane, but synthesis of short alkane-chains at GPa and diamond at pressures not lower than 300 GPa (note that simulations were carried out at 4000–5000 K).
The present work allows us to make a rough estimate of the conditions that are necessary to yield appreciable diamond nucleation on astronomical timescales.
In this context, it is crucial to note that neither carbon stars nor carbon-rich planets consist of pure carbon. In practice, the carbon concentration may be as high as 50% in carbon-rich stars [127, 128], but much less (1-2% [129, 96, 133, 130]) in Uranus and Neptune. To give a reference point, it is useful to estimate an upper bound to the diamond nucleation rate by considering the rate at which diamonds would form in a hypothetical environment of pure, metastable liquid carbon. To this end we use our numerical data on the chemical potential of liquid carbon and diamond and our numerical estimate of the diamond-liquid surface free energy, to estimate the nucleation barrier of diamond as a function of temperature and pressure. We then use CNT to estimate the rate of diamond nucleation.
To do so, we need to extend the estimate of the nucleation rate from the triple point pressure (around 16 GPa) up to 100 GPa, and from the melting temperatures ( K and K, respectively) to 35 % under-cooling (at which diffusion in our sample becomes negligible on the - far from astronomical - time-scales of our simulations). To make such an extrapolation, we make use of Eqn.’s 109, and 11. The state-point dependent quantities are the solid and liquid number densities and , the self-diffusion coefficient , the surface free energy , the difference in chemical potential between the liquid and the solid , and the critical cluster size . We estimate them in the following way: the densities are directly measured by Monte Carlo simulations of the solid and the liquid; the self diffusion coefficient is extrapolated assuming an Arrhenius behaviour of the metastable liquid (see Appendix B); the chemical potential difference is interpolated via Eq. 12 between 30 and 85 GPa. then also follows by linear interpolation. Concerning the surface free-energy, we assume that linearly depends on , the equilibrium concentration of 4-fold coordinated atoms at the selected state point. This quantity is easily measured in the Monte Carlo simulations. The nucleation barrier height is given by Eq. 9, where the geometrical factor is the same for all cluster sizes. It is obvious that we have to make rather drastic assumptions in order to estimate the nucleation rate in the experimentally relevant regime. We believe that our assumptions are reasonable, but one should not expect the resulting numbers to provide more than a rough indication.
Figure 15 shows that there is a region of some 1000K below the freezing curve (continuous red curve) where diamond nucleation is less than 10 ms (above the continuous black line). If the rate is lower than this number, not a single diamond could have nucleated in a Uranus-sized body during the life of the universe. As can be seen from the figure, our simulations for state point B are outside the regime where observable nucleation would be expected. Note that this latter conclusion is not based on any extrapolation.
As mentioned above, carbon stars and planets do not consist of pure carbon. Hence, we have to consider the effect of dilution on the crystallization process. To do so, we make a very “conservative” assumption, namely that nucleation takes place from an ideal mixture of C, N,O and H [135]. If this were not the case, then either demixing would occur, in which case we are back to the previous case, or the chemical potential of carbon in the liquid is lower than that in pure carbon, which would imply that the thermodynamic driving force for diamond crystallization is less than in pure liquid carbon. In Fig. 16, we show how dilution affects the regime where diamond nucleation is possible. To simplify this figure, we do not vary pressure and temperature independently but assume that they follow the adiabatic relation that is supposed to hold along the isentrope of Uranus [136] and we use the ideal-mixture expression for the chemical potential , where is the chemical potential difference between the solid and the liquid for he pure substance (C) and is the concentration of carbon in the fluid mixture.
Not surprisingly, Fig. 16 shows that dilution of the liquid decreases the driving force for crystallization. In fact, no stable diamond phase is expected for carbon concentrations below 8%. Moreover, there is a wide range of conditions where diamonds could form in principle, but never will in practice. Assuming that, for a given pressure, the width of this region is the same as in the pure case (almost certainly a serious underestimate), we arrive at the estimate in Fig. 16 of the region where nucleation is negligible (i.e. less than one diamond per planet per life-of-the-universe). From this figure, we see that quite high carbon concentrations (over 15%) are needed to get homogeneous diamond nucleation. Such conditions do exist in white dwarfs, but certainly not in Uranus or Neptune.
### Appendix A: LCBOPII
In this appendix, we describe the main features of the latest addition to the LCBOP family. This potential has been used in Ref. [40, 54, 137]. However, the simulations discussed in the present paper are based on LCBOPI.
Middle range interactions. Although LCBOPI gave an improved description of most liquid phase properties, like coordination distributions as a function of density, as compared to the bond-order potentials without LR interactions (Brenner, CBOP[138]), the radial distribution function showed a too marked minimum after the first shell of neighbors, as compared to ab-initio calculations (see Fig. 23). This deficiency was attributed to the relatively short cut-off of 2.2 Å for the SR interactions, giving rise to a spurious barrier for bond formation around 2.1 Å. Therefore, for LCBOPII, the total binding energy expression was extended with so-called MR interactions as:
Eb=12Nat∑i,j(SsrijVsrij+(1−Ssrij)Vlrij+1√ZmriSmrijVmrij) (20)
The first two terms on the right-hand side represent the SR and LR interactions respectively, where smoothly switches between both interactions within the interval 1.7 Å 2.2 Å, with and . The last term represents the MR interactions, where is a purely attractive potential and is a sort of MR coordination number defined as:
Zmri=(∑jSmrijVmrij)2∑j(SmrijVmrij)2 (21)
to account for many body effects. The switch function , going from 0 to 1 between = 1.7 Å and 2.2 Å, smoothly excludes the MR interactions for distances smaller than 1.7 Å. For clarity, the ranges of the various interactions in Eq. 20 are schematically represented in Fig. 17. The MR interaction was fitted to ab-initio calculations of single, double and triple bond dissociation curves. For the single bond, the tail of the interaction vanishes beyond 4 Å. is the product of a simple polynomial with a smooth cut-off at 4 Å and an environment dependent switch function , depending on the angles between and (), where atom is a SR neighbour of atom , i.e. . Thus, while the MR interactions give an extension of the covalent interactions beyond the SR cut-off distance 2.2 Å in situations where this is appropriate, its environment dependence relies only on the SR nearest neighbours (within 2.2 Å), a quite convenient property for the sake of efficiency. The switch acts in such a way that is only non-zero when the angles are relatively large. This is illustrated schematically in Fig. 18. In particular, the definition of makes vanish for any pair in all bulk crystal structures. So the addition of the MR interactions does not require reparametrization of the SR and LR potential terms.
The reactivity of atoms depends on whether these atoms are well surrounded by neighbours or not. Typically, an atom with a dangling bond wants to make another bond. To include this effect, the MR potential is made dependent on the so-called dangling bond number , i.e. . For an atom with , the MR interaction is stronger than for an atom with .
Extended coordination dependence of angular function. For LCBOPII the correction of the angle dependent part of the bond order for configurations involving low coordinations and small angles has been further extended, involving a gradual coordination dependence of the angular term over a wide range of coordinations.
Anti-bonding. Another new feature of LCBOPII is the addition of an anti-bonding correction to the bond order. An example of a situation where one electron remains unpaired in a non-bonding state is depicted in Fig. 19(b). Clearly, this situation is unfavourable as compared to the situation in Fig. 19(c). This effect cannot be captured in the conjugation term and has therefore been included as a separate, anti-bonding term.
Torsion. As it has been clearly demonstrated in Ref. [45], the torsion interaction for a bond between an atom and an atom is strongly dependent on conjugation, i.e. on the coordinations of the neighbours of and of . This was already partly included in LCBOPI. However, for LCBOPII, the conjugation dependence of the torsion interactions was fully extended and fitted to ab-initio calculations of the torsion barrier for all the possible conjugation situations.
In addition to that, LCBOPII includes a redefinition of the torsion angle, in order to avoid the ’spurious’ torsion that occurs using the traditional definition. Traditionally, the torsion angle is defined as:
cos(ωijkl)=tijk⋅tijl|tijk||tijl|=(rij×rik)⋅(rij×rjl)|rij×rik||rij×rjl| (22)
which, assuming torsion to be non-vanishing only between sp bonded atoms and , gives rise to four torsion contributions to the bond order. With the definition of Eq. 22, both situations depicted in Fig. 21b and c give rise to a non-zero torsion angle. However, in both situations there is actually no torsional distortion but only a bending distortion, which is already taken into account by the angular term in the bond order. Thus, one would like to have for the cases in Fig. 21b and c, in disagreement with the most right-hand side expression in Eq. 22. Another problem of expression 22 is that it has a singularity for configurations where is parallel to (or ). For the liquid phase at high temperature such situation are easily accessible.
For LCBOPII, the problem of ’spurious’ torsion has been tackled by a redefinition of the vectors in Eq. 22, reading:
tijk = ^rij×(^rik1−^rik2)+ + √32(^rij⋅(^rik1−^rik2))(^rij×(^rik1+^rik2))
and likewise for . Inserting these vectors into Eq. 22, leading to a different right-hand side, reproduces the same as the traditional definition for any torsional distortion without bending and yields for both situations depicted in Fig. 21, as it should be. In addition, it gives a good interpolation for any other configuration, and it has no singularities. Note that for the two distortions depicted in Fig. 21, the second term in Eq. 5 vanishes, and the vectors and are parallel, implying indeed .
Interpolation for fractional coordinations. The conjugation term for a bond depends on the reduced coordinations and of the atoms and , and on the conjugation number . The reduced coordination is defined as:
Nij=∑k≠i,jSZ(rik) (24)
and likewise for , where is a switch function for the coordination, smoothly going from 1 to 0 for going from 1.7 Å and 2.2 Å. is fitted to integer coordination configurations with only full neighbours, i.e. with . This poses the problem of how to determine for configurations with fractional bonds, i.e. configurations with for one or more neighbours . David Brenner, the inventor of the conjugation term, proposed to use a 3D spline [52]. However, since the values on the integer argument nodes are rather scattered, a spline unavoidably introduces unphysical oscillations. For LCBOPII, we found an alternative solution to this problem which is schematically illustrated in Fig. 22. In this approach, the conjugation term for configurations with fractional coordination is defined as a weighted superposition of conjugation terms for configurations with integer configurations, the weight factors for the configuration (=1,..4) being defined in terms of the switch functions . For instance, for the situation in Fig. 22, the conjugation term is given by:
Fconjij = (1−SZ,ik2)(1−SZ,ik3)Fconjij(1,2,Nconjij,1)+ + SZ,ik2(1−SZ,ik3)Fconjij(2,2,Nconjij,2)+ + (1−SZ,ik2)SZ,ik3Fconjij(2,2,Nconjij,3)+ + SZ,ik2SZ,ik3Fconjij(3,2,Nconjij,4)
where are the conjugation numbers for the four configurations in Fig. 22.
Results with LCBOPII. LCBOPII proved to be more accurate than its predecessors in describing defects and surfaces of the solid phases [40]. In the liquid phases the improvement of LCBOPII is immediately evident when looking at radial distribution functions at different densities (Fig. 23). The main discrepancy between LCBOPI and the reference data from DF-MD calculations [46, 54]) was found at the first minimum, at around 2 Å. LCBOPI predicted a much deeper minimum than DF-MD. This discrepancy is completed eliminated by LCBOPII. We also know that the melting line of diamond predicted by LCBOPII is about 500 K lower than for LCBOPI at GPa [54], more consistently with ab-initio predictions of the diamond melting line [105, 106]. In [54] we also thoroughly analyzed the properties of the liquid. Interestingly, by extrapolating the equations of state of the liquid at temperatures at which our relatively small samples actually froze, we found that a critical point for the graphite-like into diamond-like transition is present at 1230 K. The precise value might be inaccurate, since it is found far outside the sampled region, still the shapes of the higher temperature equations of state point towards the existence of such critical isotherm. As is the case for the much speculated water LLPT [29, 30] an unreachable critical point might still be responsible of some peculiar behaviour of the system at higher temperatures, such as the enormous change in nucleation rate with pressure.
### Appendix B: Self-diffusion coefficient
When computing the kinetic pre-factor to get the nucleation rate, we have to consider the fact that for our model potential, LCBOPI, only a Monte Carlo code is available. In order to evaluate the self-diffusion coefficient needed to compute the CNT kinetic pre-factor, we infer the scaling factor between the Monte Carlo “time-step” and the MD time-step [139] by propagating a 128 carbon atoms system via Car-Parrinello Molecular Dynamics CPMD code [140] starting from a configuration equilibrated with LCBOPI. Note the reasonably good agreement between the static properties of the liquid carbon computed with LCBOPI and the same computed by means of CPMD (with the BP functional) [46, 54]. Data for the high pressure state point come from simulations used in Ref. [46], whereas data for the low pressure state point come from a new simulation where the time rescaling is state-point dependent, obtained with the same technical details as reported in [46].
We use the fact that molten carbon is an Arrhenius-like liquid: therefore, once the activation energy is known, we compute the viscosity as a function of temperature and by means of the Stokes-Einstein relation obtain the diffusion coefficient. In the nineteen-fifties, Kanter [141] estimated the relevant activation energy of liquid carbon to be 683 . Subsequenty, Fedosayev [142] reported a measurement of the molten carbon viscosity: = 5 poise at . We estimate the self-diffusion coefficient at the same temperature by means of the Stokes-Einstein relation [143]
D=kBTηa, (25)
where and is the Boltzmann’s constant: cm/s. Since molten carbon is an Arrhenius-like fluid [144],
D(T)=D0exp−EAkBT, (26)
we obtain : cm/s, and then extrapolate the diffusion coefficient for different temperatures, as shown in Fig. 24 and Table 3.
We then find that at state point , cm/s, whereas at state point , cm/s.
We also use a Car-Parrinello Molecular Dynamics [140] to calculate the self-diffusion coefficient by means of the mean square displacement: at state point cm/s, which matches surprisingly well with the diffusion coefficient estimated by means of the Arrhenius law, cm/s.
## Acknowledgments
The work of the FOM Institute is part of the research program of FOM and is made possible by financial support from the Netherlands Organization for Scientific Research (NWO). We gratefully acknowledge financial support form NWO-RFBR Grant No 047.016.001 and FOM grant 01PR2070. We acknowledge support from the Stichting Nationale Computerfaciliteiten (NCF) and the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) for the use of supercomputer facilities. LMG wishes to thank his wife, Sara Iacopini, for helping him in scanning and summarizing the literature mentioned in section 3.1.
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http://weelookang.blogspot.com/2014/03/ejss-car-suspension-model.html
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## Wednesday, March 26, 2014
### EJSS car suspension model
EJSS car suspension model, an original model by lookang
EJSS car suspension model with critical damping http://weelookang.blogspot.sg/2014/03/ejss-car-suspension-model.html https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMxvaverticalcar/SHMxvaverticalcar_Simulation.html source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_SHMxvaverticalcar.zip author: lookang author of EJSS 5.0 Francisco Esquembre
EJSS car suspension model with critical damping http://weelookang.blogspot.sg/2014/03/ejss-car-suspension-model.html https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMxvaverticalcar/SHMxvaverticalcar_Simulation.html source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_SHMxvaverticalcar.zip author: lookang author of EJSS 5.0 Francisco Esquembre
EJSS SHM model with resonance showing Amplitude vs frequency graphs, heavy damping (RED) frequency ratio for better x azes values https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMresonance01/SHMresonance01_Simulation.html author: lookang author of EJSS 5.0 Francisco Esquembre
## No damping
EJSS car suspension model with no damping http://weelookang.blogspot.sg/2014/03/ejss-car-suspension-model.html https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMxvaverticalcar/SHMxvaverticalcar_Simulation.html source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_SHMxvaverticalcar.zip author: lookang author of EJSS 5.0 Francisco Esquembre
## Very light damping
EJSS car suspension model with very light damping http://weelookang.blogspot.sg/2014/03/ejss-car-suspension-model.html https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMxvaverticalcar/SHMxvaverticalcar_Simulation.html source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_SHMxvaverticalcar.zip author: lookang author of EJSS 5.0 Francisco Esquembre
## Light damping
EJSS car suspension model with light damping http://weelookang.blogspot.sg/2014/03/ejss-car-suspension-model.html https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMxvaverticalcar/SHMxvaverticalcar_Simulation.html source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_SHMxvaverticalcar.zip author: lookang author of EJSS 5.0 Francisco Esquembre
## Moderate damping
EJSS car suspension model with moderate damping http://weelookang.blogspot.sg/2014/03/ejss-car-suspension-model.html https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMxvaverticalcar/SHMxvaverticalcar_Simulation.html source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_SHMxvaverticalcar.zip author: lookang author of EJSS 5.0 Francisco Esquembre
## Critical damping
EJSS car suspension model with critical damping http://weelookang.blogspot.sg/2014/03/ejss-car-suspension-model.html https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMxvaverticalcar/SHMxvaverticalcar_Simulation.html source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_SHMxvaverticalcar.zip author: lookang author of EJSS 5.0 Francisco Esquembre
## Heavy damping
EJSS car suspension model with heavy damping http://weelookang.blogspot.sg/2014/03/ejss-car-suspension-model.html https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMxvaverticalcar/SHMxvaverticalcar_Simulation.html source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_SHMxvaverticalcar.zip author: lookang author of EJSS 5.0 Francisco Esquembre
## Wikipedia
https://en.wikipedia.org/wiki/Suspension_(vehicle) A rear independent suspension on an AWD car
## YJC note
13.3.2 Applications of Critical Damping 1) Car suspension The spring of a car’s suspension is critically damped so that when a car goes over a bump, the passenger in the car quickly and smoothly regains equilibrium. However, car suspensions are often adjusted to slightly under-critically damped condition to give a more comfortable ride. Critical damping also leaves the car ready to respond to further bumps in the road quickly.
## The equations that model the motion of the car suspension spring mass system are:
Mathematically, the restoring force $F$ is given by
$F = - k y$
where $F$ is the restoring elastic force exerted by the spring (in SI units: N), k is the spring constant (N·m−1), and y is the displacement from the equilibrium position (in m).
Thus, this model assumes the following ordinary differential equations:
$\frac{\delta x}{\delta t} = v_{y}$
$\frac{\delta v_{y}[i]}{\delta t} = -\frac{k}{m}(y) - \frac{bv_{y}}{m} + \frac{A sin(2 \pi f t)}{m}$
where the terms
$-\frac{k}{m}(y)$ represents the restoring force component as a result of the spring extending and compressing.
$- \frac{bv_{y}}{m}$ represents the damping force component as a result of dampers retarding the car mass's motion.
$+ \frac{A sin(2 \pi f[i] t)}{m}$ represents the driving force component as a result of a external periodic force acting the mass $m$ for example from the road.
## Forced oscillations
Forced oscillations are oscillations that are subjected to a periodic driving force provided by an external agent such as motor or a push by a person etc.
Resonance is an interesting phenomenon that occurs when driving force frequency matches that of the system's natural oscillating frequency resulting in a motion that reaches some maximum amplitude.
## Resonance
In physics, resonance is the tendency of a system to oscillate with greater amplitude at some frequencies than at others. Frequencies at which the response amplitude is a relative maximum are known as the system's resonant frequencies, or resonance frequencies. At these frequencies, even small periodic driving forces $+ \frac{A sin(2 \pi f t)}{m}$ can produce large amplitude oscillations, because the system stores vibrational energy.
Resonance occurs when a system is able to store and easily transfer energy between two or more different storage modes (such as kinetic energy and potential energy in the case of a spring mass system). However, there are some losses from cycle to cycle, called damping. When damping is small, the resonant frequency is approximately equal to the natural frequency of the system, which is a frequency of unforced vibrations. Some systems have multiple, distinct, resonant frequencies.
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https://www.longevitas.co.uk/site/informationmatrix/?tag=GLM
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### Functions of a random variable
#### (May 9, 2018)
Assume we have a random variable, $$X$$, with expected value $$\eta$$ and variance $$\sigma^2$$. Often we find ourselves wanting to know the expected value and variance of a function of that random variable, $$f(X)$$. Fortunately there are some workable approximations involving only $$\eta$$, $$\sigma^2$$ and the derivatives of $$f$$. In both cases we make use of a Taylor-series expansion of $$f(X)$$ around $$\eta$$:
$f(X)=\sum_{n=0}^\infty \frac{f^{(n)}(\eta)}{n!}(X-\eta)^n$
where $$f^{(n)}$$ denotes the $$n^{\rm th}$$ derivative of $$f$$ with respect to $$X$$. For the expected value of $$f(X)$$ we then have the following second-order approximation:
${\rm E}[f(X)] \approx f(\eta)+\frac{f''(\eta)}{2}\sigma^2\qquad(1)$
### Working with constraints
#### (Feb 9, 2016)
Regular readers of this blog will be aware of the importance of stochastic mortality models in insurance work. Of these models, the best-known is that from Lee & Carter (1992):
$\log \mu_{x,y} = \alpha_x + \beta_x\kappa_y\qquad(1)$
where $$\mu_{x,y}$$ is the force of mortality at age $$x$$ in year $$y$$ and $$\alpha_x$$, $$\beta_x$$ and $$\kappa_y$$ are parameters to be estimated. Lee & Carter used singular value decomposition (SVD) to estimate their parameters, but the modern approach is to use the method of maximum likelihood - by making an explicit distributional assumption for the number of deaths, the fitting process can make proper allowance for the amount of information available…
### Out of line
#### (Aug 20, 2013)
Regular readers of this blog will be in no doubt of the advantages of survival models over models for the annual mortality rate, qx. However, what if an analyst wants to stick to the historical actuarial tradition of modelling annualised mortality rates? Figure 1 shows a GLM for qx fitted to some mortality data for a large UK pension scheme.
Figure 1. Observed mortality rates (•) and fitted values (-) using a binomial GLM with default canonical link (logit scale). Source: Own calculations using the mortality experience of a large UK pension scheme for the single calendar year 2009.
Figure 1 shows that the GLM provides a good approximation of the mortality patterns. A check of the deviance residuals (not shown) yields…
Tags: GLM, linearity, survival model
### Groups v. individuals
#### (Sep 28, 2012)
We have previously shown how survival models based around the force of mortality, μx, have the ability to use more of your data. We have also seen that attempting to use fractional years of exposure in a qx model can lead to potential mistakes. However, the Poisson distribution also uses μx, so why don't we use a Poisson model for the grouped count of deaths in each cell? After all, a model using grouped counts sounds like it might fit faster. In this article we will show why survival models constructed at the level of the individual are still preferable.
The first step when using the Poisson model is to decide on the width of the age interval. This is necessary because the Poisson model for grouped counts…
### Part of the story
#### (Oct 9, 2009)
The Institute of Actuaries' sessional meeting on 28th September 2009 discussed an interesting paper. It covered similar material to that in Richards (2008), but used different methods and different data. Nevertheless, some important results were confirmed: geodemographic type codes are important predictors of mortality, and a combination of geodemographic profile and pension size is better than either factor on its own. The authors also added an important new insight, namely that last-known salary was a much better predictor than pension size.
The models in the paper were GLMs for qx, which require complete years of exposure. The authors were rightly concerned that just using complete years would…
### Out for the count
#### (Jul 31, 2009)
In an earlier post we described a problem when fitting GLMs for qx over multiple years. The key mistake is to divide up the period over which the individual was observed in a model for individual mortality. This violates the independence assumption and leads to parameter bias (amongst other undesirable consequences). If someone has three records aged 60, 61 and 62 initially, then these are not independent trials: the mere existence of the record at age 62 tells you that there was no death at age 60 or 61.
Life-company data often comes as a series of in-force extracts, together with a list of movements. The usual procedure is to re-assemble the data to create a single record for each policy, using the policy number…
### Logistical nightmares
#### (Jan 24, 2009)
A common Generalised Linear Model (GLM) for mortality modelling is logistic regression, also sometimes described as a Bernoulli GLM with a logistic link function. This models mortality at the level of the individual, and models the rate of mortality over a single year. When age is used as a continuous covariate, logistic regression has some very useful properties for pensioner mortality: exponentially increasing mortality from age 60 to 90 (say), with slower, non-exponential increases at higher ages. Logistic regression was the foundation of the models presented in a SIAS paper on annuitant mortality.
Although logistic regression for the rate of mortality is nowadays superceded by more-powerful…
Tags: GLM, logistic regression
### Great Expectations
#### (Dec 8, 2008)
When fitting statistical models, a number of features are commonly assumed by users. Chief amongst these assumptions is that the expected number of events according to the model will equal the actual number in the data. This strikes most people as a thoroughly reasonable expectation. Reasonable, but often wrong.
For example, in the field of Generalised Linear Models (GLMs), the user has a choice of so-called link functions to specify the model. For binomial data, the default is the canonical link, the logit, which gives the following function for the rate of mortality, qx:
qx = exp(α + βx) / (1 + exp(α + βx))
This is known to actuaries as a simplied version of Perks Law when applied to mortality…
Tags: GLM
### Do we need standard tables any more?
#### (Nov 1, 2008)
Actuaries are long used to using standard tables. In the UK these are created by the Continuous Mortality Investigation Bureau (CMIB), and the use of certain tables is often prescribed in legislation. As actuaries increasingly move to using statistical models for mortality, it is perhaps natural that they should first consider incorporating standard tables into these models. But are standard tables necessary, or even useful, in such a context?
Although we normally prefer to model the force of mortality, here we will use a model for the rate of mortality, qx, since this is how many actuaries still approach mortality. Our model is actually a generalised linear model (GLM) where the rate of mortality is:
exp(α+βx)qx
### Survival models v. GLMs?
#### (Aug 12, 2008)
At some point you may be challenged to decide whether to use survival models or the older generalised linear models (GLMs). You could be forgiven for thinking that the two were mutually exclusive, especially since some commercial commentators have tried to frame the debate that way.
In fact, survival models and GLMs are not necessarily mutually exclusive. It is true that GLMs are more commonly used for modelling the rate of mortality, qx, whereas survival models are always used for modelling the force of mortality, μx. Indeed, a survival model can be defined as a model for μx.
However, there are GLMs for the force of mortality as well. One notable example is the Poisson model for the number of deaths,…
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https://fungrim.org/symbol/ConstI/
|
Copyright (C) Fredrik Johansson and contributors. Fungrim is provided under the MIT license. The source code is on GitHub.
2020-08-27 09:56:25.682319 UTC
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https://rd.springer.com/article/10.1007%2FBF02481046
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Annals of the Institute of Statistical Mathematics
, Volume 34, Issue 3, pp 479–489
On estimation of a density and its derivatives
• K. F. Cheng
Article
Summary
Letf n (p) be a recursive kernel estimate off(p) thepth order derivative of the probability density functionf, based on a random sample of sizen. In this paper, we provide bounds for the moments of$$\left\| {f_n^{(p)} - f^{(p)} } \right\|_{L_2 } = \left[ {\smallint [f_n^{(p)} (x) - f^{(p)} (x)]^2 dx} \right]^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}$$ and show that the rate of almost sure convergence of$$\left\| {f_n^{(p)} - f^{(p)} } \right\|_{L_2 }$$ to zero isO(n−α), α<(r−p)/(2r+1), iff(r),r>p≧0, is a continuousL2(−∞, ∞) function. Similar rate-factor is also obtained for the almost sure convergence of$$\left\| {f_n^{(p)} - f^{(p)} } \right\|_\infty = \mathop {\sup }\limits_x \left| {f_n^{(p)} (x) - f^{(p)} (x)} \right|$$ to zero under different conditions onf.
AMS 1970 subject classification
Primary 62G05 Secondary 60F15
Key words and phrases
Recursive kernel density derivatives almost sure convergence rates
References
1. [1]
Bhattacharya, P. K. (1967). Estimation of a probability density function and its derivatives,Sankhyá, A,29, 373–382.
2. [2]
Carroll, R. J. (1976). On sequential density estimation,Z. Wahrscheinlichkeitsth.,36, 137–151.
3. [3]
Davies, H. I. (1973). Strong consistency of a sequential estimator of a probability density function,Bull. Math. Statist.,15, 49–54.
4. [4]
Davies, H. I. and Wegman, E. J. (1975). Sequential nonparametric density estimation,IEEE Trans. Inf. Theory, IT-21, 619–628.
5. [5]
Deheuvals, P. (1974). Conditions necessaires et suffisantes de convergence ponctuelle presque sûre et uniforme presque sûre des estimateurs de la densité,C. R. Acad. Sci. Paris, A.278, 1217–1220.
6. [6]
Fryer, M. J. (1977). A review of some non-parametric methods of density estimation,J. Inst. Math. Appl.,20, 335–354.
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Lamperti, J. (1966).Probability, W. A. Benjamin, Inc. N.Y.
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Lin, P. E. (1975). Rates of convergence in empirical Bayes problems: Continuous case,Ann. Statist.,3, 155–164.
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Nadaraya, E. A. (1965). On nonparametric estimates of density functions and regression curves,Theory Prob. Appl.,10, 186–190.
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Nadaraya, E. A. (1973). On convergence in theL 2-norm of probability density estimates,Theory Prob. Appl.,18, 808–811.
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Parzen, E. (1962). On estimation of a probability density function and mode,Ann. Math. Statist.,33, 1065–1076.
12. [12]
Silverman, B. S. (1978). Weak and strong uniform consistency of the kernel estimate of a density and its derivatives,Ann. Statist.,6, 177–184.
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Singh, R. S. (1977a). Improvement on some known nonparametric uniformly consistent estimators of derivatives of a density,Ann. Statist.,5, 394–400.
14. [14]
Singh, R. S. (1977b). Applications of estimators of a density and its derivatives to certain statistical problems,J.R. Statist. Soc., B,39, 357–363.
15. [15]
Singh, R. S. (1979). On necessary and sufficient conditions for uniform strong consistency of estimators of a density and its derivatives,J. Multivariate Anal.,9, 157–164.
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Singh, R. S. (1981). On the exact asymptotic behavior of estimators of a density and its derivatives,Ann. Statist.,9, 453–456.
17. [17]
Walter, G. G. (1977). Properties of Hermite series estimation of probability density,Ann. Statist.,5, 1258–1264.
18. [18]
Walter, G. G. (1980). Addendum to “Properties of Hermite series estimation of probability density”,Ann. Statist.,8, 454–455.
19. [19]
Wegman, E. J. (1972a). Nonparametric probability density estimation: I. A. summary of available methods,Technometrics,14, 533–546.
20. [20]
Wegman, E. J. (1972b). Nonparametric probability density estimation: II. A comparison of density estimation methods,J. Statist. Comp. Simul.,1, 225–245.
21. [21]
Wegman, E. J. and Davies, H. I. (1979). Remarks on some recursive estimators of a probability density,Ann. Statist.,7, 316–327.
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Wolverton, C. T. and Wagner, T. J. (1969). Asymptotically optimal discriminant functions for pattern classification,IEEE Trans. Inf. Theory, IT-15, 258–265.
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Yamato, H. (1971). Sequential estimation of a continuous probability density and mode,Bull. Math. Statist.,14, 1–12.
© The Institute of Statistical Mathematics, Tokyo 1982
Authors and Affiliations
• K. F. Cheng
• 1
1. 1.State University of New York at BuffaloBuffaloUSA
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https://algorithmist.com/index.php/UVa_10916
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# UVa 10916
## Summary
Given a year, find out what the Amtel processor word size will be in that year, and then figure out the largest ${\displaystyle N}$ for which ${\displaystyle N!}$ will fit in an unsigned integer of that word size.
## Explanation
In 1960, the word size was a measly four bits, with the word size doubling every ten years. That means that given the year Y, the number of bits can be calculated as ${\displaystyle 2^{2+\lfloor (Y-1960)/10\rfloor }}$.
The largest unsigned integer that will no longer fit in K bits is ${\displaystyle 2^{K}}$. For ${\displaystyle N!}$ to fit, then it must clearly be less than that. Now, consider ${\displaystyle \log _{2}N!=\log _{2}N+\log _{2}(N-1)+\ldots +\log _{2}1}$. If this quantity is less than ${\displaystyle \log _{2}2^{K}=K}$, then ${\displaystyle N!}$ will fit. This suggests a fairly simple algorithm: given the number of bits K, keep adding ${\displaystyle \log _{2}i}$ terms (incrementing i each time) until this number exceeds K. The largest number that still fit is the required Factstone rating.
## Notes
Strictly speaking, the running sum must actually be less than or equal to ${\displaystyle \log _{2}(2^{K}-1)}$, but the difference between that quantity and K is so miniscule that it makes no difference to solving this problem.
```1960
1981
2160
0
```
```3
8
254016
```
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https://arxiv.org/list/math.RT/recent
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# Representation Theory
## Authors and titles for recent submissions
[ total of 31 entries: 1-25 | 26-31 ]
[ showing 25 entries per page: fewer | more | all ]
### Fri, 23 Jun 2017
[1]
Title: Tame and wild theorem for the category of filtered by standard modules for a quasi-hereditary algebra
Subjects: Representation Theory (math.RT)
[2]
Title: Modular decomposition numbers of cyclotomic Hecke and diagrammatic Cherednik algebras: A path theoretic approach
Authors: C. Bowman, A. G. Cox
Subjects: Representation Theory (math.RT)
[3]
Title: Cohomology of the flag variety under PBW degenerations
Subjects: Representation Theory (math.RT); Algebraic Geometry (math.AG)
[4] arXiv:1706.07393 (cross-list from math.PR) [pdf, ps, other]
Title: Crystallization of random matrix orbits
Subjects: Probability (math.PR); Mathematical Physics (math-ph); Combinatorics (math.CO); Representation Theory (math.RT)
[5] arXiv:1706.07383 (cross-list from hep-th) [pdf, ps, other]
Title: Sasakian quiver gauge theories and instantons on cones over round and squashed seven-spheres
Subjects: High Energy Physics - Theory (hep-th); Mathematical Physics (math-ph); Differential Geometry (math.DG); Representation Theory (math.RT); Symplectic Geometry (math.SG)
[6] arXiv:1706.07334 (cross-list from math.RA) [pdf, other]
Title: Transfer results for Frobenius extensions
Subjects: Rings and Algebras (math.RA); Quantum Algebra (math.QA); Representation Theory (math.RT)
[7] arXiv:1705.03279 (cross-list from math.RA) [pdf, ps, other]
Title: Strongly quasi-hereditary algebras and rejective subcategories
Authors: Mayu Tsukamoto
Subjects: Rings and Algebras (math.RA); Representation Theory (math.RT)
### Thu, 22 Jun 2017
[8]
Title: Moduli spaces of representations of special biserial algebras
Subjects: Representation Theory (math.RT)
[9]
Title: Linearity of stability conditions
Authors: Kiyoshi Igusa
Subjects: Representation Theory (math.RT)
[10]
Title: A bijection between $m$-cluster-tilting objects and $(m+2)$-angulations in $m$-cluster categories
Subjects: Representation Theory (math.RT); Category Theory (math.CT)
[11]
Title: A geometric realization of the $m$-cluster categories of type $\tilde{D_n}$
Comments: Some gaps need to be filled in
Subjects: Representation Theory (math.RT); Category Theory (math.CT)
[12]
Title: The Dieck-Temperley-Lieb algebras in Brauer algebras
Authors: Shoumin Liu
Subjects: Representation Theory (math.RT)
[13]
Title: Nil Hecke algebras and Whittaker D-modules
Authors: Victor Ginzburg
Subjects: Representation Theory (math.RT); Algebraic Geometry (math.AG)
[14] arXiv:1706.06665 (cross-list from math.CO) [pdf, ps, other]
Title: Fixed-point-free involutions and Schur P-positivity
Subjects: Combinatorics (math.CO); Representation Theory (math.RT)
### Wed, 21 Jun 2017
[15]
Title: Maximal green sequences for cluster-tilted algebras of finite type
Authors: Kiyoshi Igusa
Subjects: Representation Theory (math.RT)
[16]
Title: Spin nilHecke algebras of classical type
Subjects: Representation Theory (math.RT)
[17] arXiv:1706.06168 (cross-list from math.CV) [pdf, ps, other]
Title: A Representation Theoretic Explanation of the Borcea-Brändén Characterization and Grace's Theorem, and New Results
Authors: Jonathan Leake
Subjects: Complex Variables (math.CV); Representation Theory (math.RT)
### Tue, 20 Jun 2017
[18]
Title: Orthonormal Bases in the Orbit of Square-Integrable Representations of Nilpotent Lie Groups
Subjects: Representation Theory (math.RT)
[19]
Title: Categories O for Dynkin Borel Subalgebras of Root-Reductive Lie Algebras
Comments: This is a dissertation in Mathematics for a doctoral degree at Jacobs University Bremen. It contains 111 pages and 1 figure
Subjects: Representation Theory (math.RT)
[20]
Title: Représentations supercuspidales
Authors: Arnaud Mayeux
Subjects: Representation Theory (math.RT)
[21]
Title: The algebraic Mackey-Higson bijections
Authors: Eyal Subag
Subjects: Representation Theory (math.RT)
[22]
Title: On the normality of the null-fiber of the moment map for $θ$- and tori representations
Authors: Michael Bulois
Subjects: Representation Theory (math.RT); Algebraic Geometry (math.AG); Symplectic Geometry (math.SG)
[23]
Title: Projective indecomposable modules and quivers for monoid algebras
Subjects: Representation Theory (math.RT); Group Theory (math.GR); Rings and Algebras (math.RA)
[24] arXiv:1706.05819 (cross-list from math.SG) [pdf, ps, other]
Title: Abstract integrable systems on hyperkähler manifolds arising from Slodowy slices
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https://forum.allaboutcircuits.com/threads/fixing-possibly-a-bad-power-supplies-board-of-a-led-tv.169213/page-3
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# fixing possibly a bad power supplies board of a LED TV
#### MisterBill2
Joined Jan 23, 2018
9,785
Now there is a test that the TS can do with no electronic test equipment and no circuit. That is to power up the set and shine a bright flashlight into the panel at an angle. If the set is working except fore the backlight, there will be some evidence of a picture. Mostly, what failes on a TV is the backlight. either the power supply or the controls.
#### shortbus
Joined Sep 30, 2009
8,952
Better product quality and service make a difference of the product price.
If you had a choice between a TV for $100 and one for$1000, that you knew had the same circuits, what would you buy?
#### Leon_Chan
Joined Sep 11, 2019
99
I will always pick the cheapest with accepted quality. But for the riches and these who buy for their organizations, they cannot spare the time to fix anything or accept down time, just call for the big brand service support immediately.
#### MisterBill2
Joined Jan 23, 2018
9,785
I will always pick the cheapest with accepted quality. But for the riches and these who buy for their organizations, they cannot spare the time to fix anything or accept down time, just call for the big brand service support immediately.
The challenge is always about the quality. I asked a sales person about the quality one time and the dude immediately claimed the product was of the highest quality because of all the features. I explained that quality was all about how long it would work before breaking, at which point he started explaining about all of the service plans that I could buy so that it would be fixed for free when it broke. The price of the service plan would have covered the cost of a much better product elsewhere. I had to explain that quality means a product is built to last, which was a concept that person did not understand. I left without purchasing anything, and have not been back in 15 years.
Quality in things like a TV is related to both the quality of the parts and the stress levels that they are operated at. That can be learned by noticing which brands are seen at the curb the most on trash collection days. When new-looking sets of a brand are frequently seen, it becomes clear as to where the quality is not found. This may not be a fair or scientific evaluation, but it does make sense.
#### Leon_Chan
Joined Sep 11, 2019
99
Now there is a test that the TS can do with no electronic test equipment and no circuit. That is to power up the set and shine a bright flashlight into the panel at an angle. If the set is working except fore the backlight, there will be some evidence of a picture. Mostly, what failes on a TV is the backlight. either the power supply or the controls.
Nothing found displayed.
A normal LEDTV will have its IR light red when ready and blue when you power-on its with the remote controller or panel buttons.
I find the light is red but the remote controller cannot operate it on or off. Sometime I can start it with the blue light, but the remote controller still do not work. So it is believed that the TV hangs while it is loading.
When this LEDTV failed, it show a logon screen while loading and hangs. The other day, its failed to display anything too.
Is there any other kind of use to this LEDTV remained in this mode of failure?
Last edited:
#### Leon_Chan
Joined Sep 11, 2019
99
Some people thinking that this can be fixed by fixing or replacing this smaller board. What is its name? Anyone agree?
#### Attachments
• 1.4 MB Views: 5
#### shortbus
Joined Sep 30, 2009
8,952
I find the light is red but the remote controller cannot operate it on or off. Sometime I can start it with the blue light, but the remote controller still do not work.
To me that says the remote is dead. What happens if you use the on switch built into the TV?
#### Leon_Chan
Joined Sep 11, 2019
99
To me that says the remote is dead. What happens if you use the on switch built into the TV?
No. That means the board is not functional.
I can detect the remote controller signal with a camera lens.
Not sure if this is caused by a bad LED Driver board and I am now focusing on it.
#### Leon_Chan
Joined Sep 11, 2019
99
The LED driver board has following printed on it.
hq-led07k
20110603003416
94V-0
1052
D E300052
I have not found the same board so I have to get a cheap replacement or trying to do fixing on it, for example, replace any capacitor on it???
#### Attachments
• 765.3 KB Views: 1
#### MisterBill2
Joined Jan 23, 2018
9,785
The LED driver board has following printed on it.
hq-led07k
20110603003416
94V-0
1052
D E300052
I have not found the same board so I have to get a cheap replacement or trying to do fixing on it, for example, replace any capacitor on it???
Before replacing the remote control board you should check first that the remote board has power, because if it does not have power then there is a problem someplace else. If it does have power, then you can use your DVM on an AC range to check the other leads from the remote board to see if any digital data is sent when you operate the remote control.
If the set does not have an on/off switch on the TV itself then I would just scrap the set. In my evaluation any TV that is only controlled by the remote is trash. That is because the remote control is quite prone to failure.
#### Leon_Chan
Joined Sep 11, 2019
99
As mentioned in #45, but it is more clear to mention again that both panel buttons and the remote controller cannot operate the TV after it is plugged in and with the IR light goes red/ready. It cannot switch it on or off the TV( to turn its IR light to blue). It is simply hang.
Now I am focusing on the small LED driver board that some people saying "replacing it had his TV fixed".
Get a compatible replacement or do some test/fix on that exist one.
#### Leon_Chan
Joined Sep 11, 2019
99
There is not the same LED driver in the market now. Anyone can provide advice on how to choose a compatible LED driver as above. What specifications I should be taken notice of ? Thanks
#### Leon_Chan
Joined Sep 11, 2019
99
As I cannot get a cheap LED driver replacement providing 1050mA to test it further, and it is tested that the power supply is not the suggested problem, the thread of this will be closed unless there is something new, for example, understanding enough about how the LEDs work and its calculation in future.
I think it may be possible that both the LEDs and the LED driver is replaced as a complete set, which can be bought in the market, however.
There is little value to fix a 10-years-old product with parts no longer ready available when new ones come at cheap price unless for practical purpose.
#### MisterBill2
Joined Jan 23, 2018
9,785
TGhe way to check and see if the problem is the LED part of the set is to have the set on and tuned to a station, or other video source, and then use a flashlight or similar light source to look into the screen. If it is done correctly it will be possible to see images in the screen dimly. That will show that the problem is only a lack of illumination. If the set can not be turned on and tuned to a station then the problem is not in the screen illumination system.
And a further note: Replacing the LEDs requires an extensive amount of disassembly of the set.
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http://www.nag.com/numeric/FL/nagdoc_fl24/html/G05/g05saf.html
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G05 Chapter Contents
G05 Chapter Introduction
NAG Library Manual
# NAG Library Routine DocumentG05SAF
Note: before using this routine, please read the Users' Note for your implementation to check the interpretation of bold italicised terms and other implementation-dependent details.
## 1 Purpose
G05SAF generates a vector of pseudorandom numbers taken from a uniform distribution between $0$ and $1$.
## 2 Specification
SUBROUTINE G05SAF ( N, STATE, X, IFAIL)
INTEGER N, STATE(*), IFAIL REAL (KIND=nag_wp) X(N)
## 3 Description
G05SAF generates $n$ values from a uniform distribution over the half closed interval $\left(0,1\right]$.
One of the initialization routines G05KFF (for a repeatable sequence if computed sequentially) or G05KGF (for a non-repeatable sequence) must be called prior to the first call to G05SAF.
## 4 References
Knuth D E (1981) The Art of Computer Programming (Volume 2) (2nd Edition) Addison–Wesley
## 5 Parameters
1: N – INTEGERInput
On entry: $n$, the number of pseudorandom numbers to be generated.
Constraint: ${\mathbf{N}}\ge 0$.
2: STATE($*$) – INTEGER arrayCommunication Array
Note: the actual argument supplied must be the array STATE supplied to the initialization routines G05KFF or G05KGF.
On entry: contains information on the selected base generator and its current state.
On exit: contains updated information on the state of the generator.
3: X(N) – REAL (KIND=nag_wp) arrayOutput
On exit: the $n$ pseudorandom numbers from a uniform distribution over the half closed interval $\left(0,1\right]$.
4: IFAIL – INTEGERInput/Output
On entry: IFAIL must be set to $0$, $-1\text{ or }1$. If you are unfamiliar with this parameter you should refer to Section 3.3 in the Essential Introduction for details.
For environments where it might be inappropriate to halt program execution when an error is detected, the value $-1\text{ or }1$ is recommended. If the output of error messages is undesirable, then the value $1$ is recommended. Otherwise, if you are not familiar with this parameter, the recommended value is $0$. When the value $-\mathbf{1}\text{ or }\mathbf{1}$ is used it is essential to test the value of IFAIL on exit.
On exit: ${\mathbf{IFAIL}}={\mathbf{0}}$ unless the routine detects an error or a warning has been flagged (see Section 6).
## 6 Error Indicators and Warnings
If on entry ${\mathbf{IFAIL}}={\mathbf{0}}$ or $-{\mathbf{1}}$, explanatory error messages are output on the current error message unit (as defined by X04AAF).
Errors or warnings detected by the routine:
${\mathbf{IFAIL}}=1$
On entry, ${\mathbf{N}}<0$.
${\mathbf{IFAIL}}=2$
On entry, STATE vector was not initialized or has been corrupted.
Not applicable.
None.
## 9 Example
This example prints the first five pseudorandom numbers from a uniform distribution between $0$ and $1$, generated by G05SAF after initialization by G05KFF.
### 9.1 Program Text
Program Text (g05safe.f90)
### 9.2 Program Data
Program Data (g05safe.d)
### 9.3 Program Results
Program Results (g05safe.r)
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https://physics.stackexchange.com/questions/376613/communication-between-two-observers-moving-at-the-same-relative-velocity/376618
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# Communication between two observers moving at the same relative velocity
Let's say we have two ships moving at, for example, .8c. Let's put them 1 light-year apart and give them exactly the same velocity. I want to point a laser from one ship and hit the other ship.
My initial thought is that since the speed of light is constant I'll have to aim the light ahead, so that the beam is still moving forward at .8c, and toward the other ship at .6c so they add up to $.6^2 + .8^2 = 1^2$, meaning that the maximum speed of communication between these two ships is .6c.
Someone has pointed out to me that this is wrong, since one of the core principles of relativity is that velocities are relative. Because of this we should not be able to tell that we are going .8c and communication between the two ships should be completely normal.
How does this work out? I imagine that I am correct from the perspective of a stationary observer, but time dilation will make it appear that .6c is actually 1c onboard either of the ships.
To clarify, my main question is: which direction the will the light beam have to be directed from the transmitter to the receiver. Can I point the beam directly at the receiving ship or will I have to lead it? If it can be pointed directly at the receiving ship, how can you reconcile the frame of reference of a stationary observer with the frame of reference moving with the two ships?
• Whenever you talked about speed, you must also say w.r.t whom? In your question this part is missing. If you are clear on this, then, by applying [link] (physics.stackexchange.com/questions/103907/…) special relativity formula for relative speed, you will get to know that information would flow at the same speed for all the ships, i.e. c. – Vikash Kumar Dec 28 '17 at 10:01
• Obviously you have to aim your laser pointer straight into the target - receiver. The beam will move at straight line towards the receiver in your frame. However , in the frame of the "stationary" observer this beam will have the same x- velocity as you. It's x- coordinate will always be the same as yours, so it will go through the laser's tube perfectly well. Look at episode 1 in this video youtube.com/watch?v=FQKp3FU8vR8. – Albert Dec 28 '17 at 16:12
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http://mathoverflow.net/questions/106162/elementary-proof-of-basis-of-order-k
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# Elementary Proof of Basis of Order k
## Context
According to the FAQ, questions of the form "the sorts of questions you come across when you're writing or reading articles or graduate level books" are acceptable. This falls into the "reading graduate level books."
## Problem Statement
Let $N$ be the natural numbers.
$B \subseteq N$ is a basis of order $k$ if $N \setminus kB$ is finite.
I would like to show that there is a basis $B$ of order $k$ s.t.
$|B \cap [1,n]| = O(n^{1/2} \log^{1/k} n)$.
## What I've tried
Suppose all we needed was $O(n^{1/2} \log^{1/2} n)$, then I would define $B$ by randomly sampling from $N$ s.t.
$$P(n \in B) = \frac{c\log^{1/2} n}{\sqrt{n}}$$
By the chernoff bound, with high probability we have $|B \cap [1,n]| = O(n^{1/2}\log^{1/2} n)$.
Furthermore, for any $n$, there does not exists $a,b\in B$ s.t. $a+b=N$ with probability at most $(1-\frac{c\log n}{n})^{n/2} \leq 1/n^2$, and we're done.
Unfortunately, however, I need to push this down to $O(n^{1/2}\log^{1/k} n)$.
## What I'm stuck on
So far, I've only used $B$ as a order 2 base, rather than an order $k$ base.
## Question:
What should I be looking at to go from order 2 to order $k$ and $\log^{1/2} n$ to $\log^{1/k} n$?
-
If $B$ is a basis of order $k$ such that every integer $n$ can be written as a sum of $k$ elements from $B$ in $\asymp n^{o(1)}$ ways, then a simple counting argument yields $|B \cap [1 , X]| \asymp X^{\frac{1}{k}+o(1)}$. Thus a stronger estimate $|B \cap [1 , X]| \asymp (X \log X)^{\frac{1}{k}}$ in your problem is certainly a more interesting goal.
Theorem 8.6.3 in "The Probabilistic Method" by Alon & Spencer gives precisely a set $B$ satisfying this estimate when $k=3$ (and the proof can be adapted in order to handle any value $k \geq 3$). They also give the following reference :
Erdos, P. and Tetali, P. (1990). Representations of integers as the sum of k terms, Random Structures Algorithms 1(3): 245-261.
@Stanley Yao Xiao : I made an assumption on the number of representations of integers by $k$ elements from $B$ which essentially discards basis of smaller order.
@unknown : Writing $r(n)$ for the number of representations of $n$ as a sum $b_1 + \cdots + b_k$ with each $b_i \in B$, we have $$|B \cap [1,X]|^k = \sum_{n \geq 1} \left( \sum_{b_1 + \cdots + b_k = n ;\\ b_i \leq X} 1 \right) \geq \sum_{1 \leq n \leq X} r(n)$$ and $$|B \cap [1,X]|^k = \sum_{n \geq 1} \left( \sum_{b_1 + \cdots + b_k = n ;\\ b_i \leq X} 1 \right) \leq \sum_{1 \leq n \leq kX} r(n)$$ Under the assumption $r(n) \asymp n^{o(1)}$, both RHS are $X^{1 + o(1)}$, hence the result. Actually, Erdos & Tetali showed that some basis $B$ of order $k$ satisfies $r(n) \asymp \log n$. By the argument above, this implies $|B \cap [1,X]| \asymp (X \log X)^{\frac{1}{k}}$.
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@js: out of curiosity, what is the simple counting argument for X^{1/k + o(1)} ? – user26147 Sep 2 '12 at 18:56
One can obtain that as a lower bound fairly easily; but it is certainly not true as an upper bound. For instance the set of integers is an additive basis of any order, but is much denser than that. – Stanley Yao Xiao Sep 3 '12 at 3:02
To elaborate on the above comment, the problem with order $k$ bases is precisely that Chernoff's inequality does not work. The joint independence assumption for Chernoff's inequality is essential; as seen by the following example taken from Tao and Vus' Additive Combinatorics:
Color the elements of $[1, N]$ either black or white independently and with equal probability. For each $A \subset [1, N]$ let $s_A$ denote the parity of black elements of $A$ (so say if $A$ contains 3 black elements then $s_A = 1$). One can check that the $s_A$'s are independent events. Write $X = \displaystyle \sum_{A \subset [1, N]} s_A$. One can check that $\mathbb{E}X = 2^N - 1/2$ and $\textbf{Var} X = 2^{N-2} - 1/4$. Further, $\mathbb{P}(X = 0) = 2^{-N}$. The upper-bound on Chernoff's inequality would be $2\exp(-2^{N-2})$, which is much smaller than $\mathbb{P}(X = 0)$, so the inequality fails.
The reason why a simple argument suffices for additive bases of order 2 is because we have
$$\displaystyle r_{2,B}(n) = \sum_{x < n/2} \mathbb{I}(x \in B) \mathbb{I}(n - x \in B) + E$$
where $E$ is a suitably small error, and $r_{2,B}(n)$ is the number of ways to write $n$ as a sum of two elements in $B$. The key here is that the events $\mathbb{I}(x \in B) \mathbb{I}(n - x \in B)$ are independent for $1 \leq x < n/2$. This is not the case when there are more summands. In the Erdos-Tetali paper cited above, this issue is circumvented via Janson's inequality. In particular, Erdos-Tetali showed that there are additive bases of order $k$ satisfying $| B \cap [1,N]| = \Theta(N^{1/k} \log^{1/k} N)$.
The main difficulty you have to circumvent is how to deal with the non-independence of the random variables $\mathbb{I}(x_1 \in B) \cdots \mathbb{I}(x_k \in B)$.
-
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https://hal-upec-upem.archives-ouvertes.fr/hal-00622763
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# Rational interpolation and basic hypergeometric series
Abstract : We give a Newton type rational interpolation formula (Theorem 2.2). It contains as a special case the original Newton interpolation, as well as the interpolation formula of Liu, which allows to recover many important classical q-series identities. We show in particular that some bibasic identities are a consequence of our formula.
Keywords :
Document type :
Journal articles
https://hal-upec-upem.archives-ouvertes.fr/hal-00622763
Contributor : Alain Lascoux <>
Submitted on : Monday, September 12, 2011 - 4:28:29 PM
Last modification on : Wednesday, February 26, 2020 - 7:06:05 PM
### Citation
Amy M. Fu, Alain Lascoux. Rational interpolation and basic hypergeometric series. Advances in Applied Mathematics, Elsevier, 2008, 41 (3), pp.452-458. ⟨10.1016/j.aam.2008.01.003⟩. ⟨hal-00622763⟩
Record views
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https://tpiezas.wordpress.com/2012/04/13/the-tremendous-tribonacci-constant/
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The Tremendous Tribonacci constant
The tribonacci constant is the real root of the cubic equation,
$T^3-T^2-T-1 = 0$
and is the limiting ratio of the tribonacci numbers = {0, 1, 1, 2, 4, 7, 13, 24, …} where each term is the sum of the previous three, analogous to the Fibonacci numbers. Let $d = 11$, then,
$T = \frac{1}{3} +\frac{1}{3}\big(19+3\sqrt{3d}\big)^{1/3} + \frac{1}{3}\big(19-3\sqrt{3d}\big)^{1/3} = 1.839286\dots$
We’ll see that the tribonacci constant is connected to the complete elliptic integral of the first kind $K(k_{11})$. But first, given the golden ratio’s infinite radical representation,
$\phi = \sqrt{1+\sqrt{1+\sqrt{1+\sqrt{1+\dots}}}}$
then T also has the beautiful infinite radical,
$\frac{1}{T-1} = \sqrt[3]{\frac{1}{2}+\sqrt[3]{\frac{1}{2}+\sqrt[3]{\frac{1}{2}+\sqrt[3]{\frac{1}{2}+\dots}}}} = 1.191487\dots$
as well as a continued fraction,
$\big(\frac{T}{T+1}\big) \big(e^{\frac{\pi\sqrt{11}}{24}}\big) = 1 + \cfrac{q}{1-q + \cfrac{q^3-q^2}{1+\cfrac{q^5-q^3}{1+\cfrac{q^7-q^4}{1+\ddots}}}} = 0.9999701\dots$
where q is the negative real number,
$q = \frac{-1}{e^{\pi \sqrt{11}}}$
Recall that at elliptic singular values, the complete elliptic integral of the first kind K(k) satisfies the equation,
$\frac{K'(k_d)}{K(k_d)} = \sqrt{d}$
or, in the syntax of Mathematica,
$\frac{EllipticK[1-ModularLambda[\sqrt{-d}]]}{EllipticK[ModularLamda[\sqrt{-d}]]} = \sqrt{d}$
Interestingly, we can express both $k_{11} = 0.000477\dots$ and $K(k_{11}) = 1.57098\dots$ in terms of the tribonacci constant as,
$k_{11} = \frac{1}{4}\left(2-\sqrt{\frac{2v+7}{2v-7}}\,\right) = 0.000477\dots$
where,
$v = T+4$
and,
$K(k_{11}) = \left(\frac{T+1}{T}\right)^2\, \frac{1}{11^{1/4}\, (4\pi)^{2}} \, \Gamma(\tfrac{1}{11}) \Gamma(\tfrac{3}{11}) \Gamma(\tfrac{4}{11}) \Gamma(\tfrac{5}{11}) \Gamma(\tfrac{9}{11})$
where $\Gamma(n)$ is the gamma function, as well as the infinite series,
$K(k_{11}) = \left(\frac{T+1}{T}\right)^2 \frac{\pi}{32^{1/4}} \sqrt{\frac{1}{4} \sum_{n=0}^\infty \frac{(6n)!}{(3n)!n!^3} \,\frac{1}{(-32)^{3n}} }$
With a slight tweak of the formula, we instead get,
$\frac{1}{4\pi} = \frac{1}{32^{3/2}} \sum_{n=0}^\infty \frac{(6n)!}{(3n)!n!^3}\, \frac{154n+15}{(-32)^{3n}}$
Finally, saving the best for last, given the snub cube, an Archimedean solid,
then the Cartesian coordinates for its vertices are all the even and odd permutations of,
{± 1, ± 1/T, ±}
with an even and odd number of plus signs, respectively, similar to how, for the vertices of the dodecahedron — a Platonic solid — one can use the golden ratio.
For more about the tribonacci constant, and the equally fascinating plastic constant, kindly refer to “A Tale of Four Constants “.
2 responses to this post.
1. […] already written about the tribonacci constant before. But I want to include how Lin found that powers of t can be expressed in terms of those three […]
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http://www.chegg.com/homework-help/questions-and-answers/equation-5-q-neutralization-h-neutralization-x-n-reactant-1-mol-reactant-n-reactant-moles--q4861278
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equation # 5 is: q(neutralization) = /\H(neutralization) x ( n(reactant)/ 1 mol reactant ) n(reactant) is the moles of limiting reactant (mole-to-mole ratio of HCl: NaOH is 1:1)
equation #7 is: C(coffee cup) x T(coffee cup) + C(solution) x m(solution) x /\T(cup) + /\H(neutralization x ( n(reactant)/ 1 mol reactant )
NOTE THE ANSWERS IVE PUT ARE WRONG PLEASE HELP. I will increase the points if you feel it is necessary. Thnaks.
Image text transcribed for accessibility: As part of the calibration procedure for the calorimeter, a student collects the following data; [HCl] = 1.0 M, [NaOH] = 1.0M Mass calorimeter; 4.32 g Mass calorimeter + NaOH: 55.65g Mass calorimeter + NaQH + HCI; 104.85 g Initial temperature of reagents: 20.8 degree C Final temperature after neutralization: 27.5 degree C delta H neutralization and C solution are provided in the lab manual. Assume that the density of the solution is the same as that for water at 25 degree C; 1.00g/mL. Which reactant is the limiting reagent? Calculate n-reactant (first introduced in equation 5 in the lab manual): Calculate Ccup as defined in equation 7 in the lab manual:
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https://codereview.stackexchange.com/questions/95173/intmodulus-long-addition-and-subtraction
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# IntModulus long addition and subtraction
One of the remarks in this answer to my question concerning IntModulus says
What's more problematic is that you don't have matching argument symmetry for add and subtract. You should have long versions of those.
and the reason for this part missing is that I hoped to get something faster than the trivial
public int add(long x, long y) {
return mod(mod(x) + mod(y));
}
The optimized solution has only one modulus operation (sure, only benchmarking will tell if it was worth it).
Please have a short look at the original question before reviewing. I mean the comments, not the code.
public final class IntModulus {
///////// Irrelevant code removed, see the original question if you miss anything.
///////// New code below.
/** Return a non-negative value less than modulus and congruent to the exact sum. */
public int add(long x, long y) {
final long sum = x + y;
// The addition overflowed iff both operands have the same sign are the result's sign differs.
final boolean overflow = (x^y) >= 0 & (x^sum) < 0;
return overflow ? overflowedMod(sum) : mod(sum);
}
/** Return a non-negative value less than modulus and congruent to the exact sum. */
public int sub(long x, long y) {
final long diff = x - y;
// The subtraction overflowed iff the operands have opposing signs and the result's sign differs from the minuend.
final boolean overflow = (x^y) < 0 & (x^diff) < 0;
return overflow ? overflowedMod(diff) : mod(diff);
}
/**
* Compute a modulus of the argument under the assumption that it overflowed by exactly {@code 2**64},
* i.e., it's a result of an overflowing {@code long} addition or subtraction.
*
* <p>This means that the sign is surely wrong and that the number would fit into a 65-bit signed integer.
*/
private int overflowedMod(long x) {
// The proper value of the argument divided by two and floored (i.e., rounded towards negative infinity).
// The sign bit got restored by simply flipping it as we know it was wrong.
final long half = (x >> 1) ^ Long.MIN_VALUE;
final long lsb = x & 1; // the least significant bit
long result = 2L * mod(half) + lsb;
// Now the result lies in the range 0 to 2*modulus+1 (both included), so conditionally reduce it twice.
if (result>=modulus) result -= modulus;
if (result>=modulus) result -= modulus;
return (int) result;
}
///////// Old but relevant code below.
/** Return a non-negative value less than modulus and congruent to the operand. */
public int mod(long x) {
// As modulus is an int, the cast is safe.
return fixModulus((int) (x % modulus));
}
/**
* Fix the modulus, i.e., make it non-negative.
* The argument must be between {@code -modulus+1} and {@code modulus-1}.
*/
private int fixModulus(int x) {
return x<0 ? x+modulus : x;
}
@Getter private final int modulus;
}
The benchmark results shows that it's much faster than using BigInteger (suffix "bi"). It's assuming that the operands are already available in the needed form (i.e., they don't have to be converted to/from BigInteger).
Subtraction is not shown, as it's obviously as fast as addition. The code for multiplication is given in the old question.
• Do you have benchmarks of the current code vs the one that uses three mods? – JS1 Jul 3 '15 at 5:30
• @JS1 Sadly, not anymore. There's some small improvement in case there's no overflow, otherwise the conditional branch makes it even slightly worse. I'd assume, the case of the operands never overflowing is the more important one. I guess, the observation concerning the conditional jump could lead us to a universally better solution. – maaartinus Jul 3 '15 at 5:49
## Small improvements
Overall, it seems that what you wrote is correct and is an improvement over the mod(mod(x)+mod(y)) solution, especially in the case where there is no overflow. I have three small improvements:
You can replace this line:
long result = 2L * mod(half) + lsb;
with:
long halfmod = mod(half);
long result = halfmod + halfmod + lsb;
The modified version showed a 1% improvement in the overflow case. (See benchmarks below)
Remove one unnecessary check
Following the code above, you have this code:
// Now the result lies in the range 0 to 2*modulus+1 (both included),
// so conditionally reduce it twice.
if (result>=modulus) result -= modulus;
if (result>=modulus) result -= modulus;
But actually, the value of mod(half) is in the range 0..modulus-1. So if you multiply that by 2 and add 1, result will be in the range 0..2*modulus-1, not 0..2*modulus+1 as you stated in the comment. Therefore, after the first result -= modulus, the range of result will be 0..modulus-1 and there is no need for the second check.
// Now the result lies in the range 0 to 2*modulus-1 (both included),
// so conditionally reduce it once.
if (result>=modulus) result -= modulus;
By removing the second check, I found a 1% speed improvement in the overflow case.
Checking for overflow
I replaced this overflow check for add:
final boolean overflow = (x^y) >= 0 & (x^sum) < 0;
with this very similar one:
final boolean overflow = ((x^y^Long.MIN_VALUE) & (x^sum)) < 0;
Edit: Later I found that this inverted version is faster:
final boolean overflow = ((x^y) | ~(x^sum)) >= 0;
It tests the same thing but uses one extra xor instead of a comparison. For the overflow case I found a 2% speed improvement, and it was about 4% faster in the non-overflow case.
For subtraction I did a similar thing:
final boolean overflow = (x^y) < 0 & (x^diff) < 0;
became:
final boolean overflow = ((x^y) & (x^diff)) < 0;
Here I didn't even have to add an extra xor.
## Benchmarks
I took the suggestion of using JMH to run benchmarks. Here are the results:
Overflow add test
-----------------
Methodology: Add 0x4000000000000000L with itself modulo 0x12345678
in a loop of 100000 iterations.
Method Operations per second Speed
------ --------------------- -----
Original code 238.754 +- 0.778 100.0%
Multiply change 241.527 +- 0.884 101.1%
Remove extra check 241.180 +- 1.007 101.0%
Change overflow check 243.335 +- 1.662 101.9%
All changes 256.452 +- 1.325 107.4%
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|
https://electronics.stackexchange.com/questions/426300/optocoupler-characteristics
|
# Optocoupler Characteristics
1. In my application I need to isolate a PWM signal @ 1 kHz, which is generated from a Beaglebone Black microcontroller. In my signal, I want to have one hundred different steps in duty cycle (from 1% to 100% duty cycles). From what I understand, my opto-coupler should be fast enough, so that it can transmit the narrowest pulse (1% duty cycle), which has a duration of 1% * (1/1000) = 10 μs. Consequently, I need to have: tr + tf < 10 μs, where tr and tf are rise and fall times of the opto-coupler. Is the above logic correct? If so, I need some help in understanding how the above calculations can be translated to bits per second, because everyone filters the opto-couplers according to their data rate (bps).
2. Another question is about the input current of the opto-coupler. My microcontroller can only provide around 4 - 6 mA through its PWM ports. I need some help understanding the datasheets of the opto-couplers. So, for example, this datasheet is from the 6N138M opto-coupler. One can see under the "features" section: "Low Current - 0.5 mA".
This seems okay for my μC. But under absolute maximum ratings, it says that If can reach 20 mA. How do I know in this case how much current should be fed to the opto-coupler, in order to work as intended?
• You don't want 20mA. You need If=12mA only from 5V but low side drive from Vol (3.3 to 0)) ( If is more stable) and 12mA output with CTR=100% using 120 Ohm to 3.3V or 270 to 5V with a comparator to drive FET. for your load. – Sunnyskyguy EE75 Mar 9 at 3:09
• is this a DIY one off project or a volume product design – Sunnyskyguy EE75 Mar 9 at 8:56
• After reading your answers (which have been really helpful), I've noticed many ask about the application.The PWM signal will be used for controlling a power mosfet switch. I am planning to use the STP55NF06L, plus a mosfet driver, like the ICL7667. From my understanding, the mosfet driver needs a tiny amount of current in its input signal, so I should not be much concerned about the output current of the optocoupler. – NickG Mar 9 at 23:35
• Beware that FET Ciss * RdsOn is somewhat constant for each technology. and that may impact your results so CB drive may be necessary. e.g. 1nF *270 Ohms =T= – Sunnyskyguy EE75 Mar 9 at 23:40
• One further question: In many opto-couplers' datasheets, I noticed that there is a resistor (usually named RL) placed between the Vcc and the Vout, on the output side of the IC. Such schematics can be found under the "Test Circuits" section. What is this resistors purpose? Furthermore, in these "Test Circuits", one can see several capacitors. Could someone explain the exact functionality of each one of those? – NickG Mar 11 at 21:26
how the above calculations can be translated to bits per second, because everyone filters the optocouplers according to their Data rate (bps).
A 10 us pulse would be equivalent to a 100 kbps digital data rate.
Another question is about the input current of the optocoupler. My microcontroller can only provide around 4-6mAmps through its PWM ports.
You want to look for the "current transfer ratio" or CTR. This tells you the ratio between the output current and the input current. If you put 5 mA in and the CTR is 100%, you'll get 5 mA out on the other side of the optocoupler. Whether this is enough depends on the input impedance of the load, among other things.
For many "jelly bean" optocouplers, the CTR is less than 100%.
So, for expample, this datasheet is from the 6N138M optocoupler. One can see under the "features" section: "Low Current-0.5mA".
This part claims a CTR of 2000% (due to buffering transistors on the output). So if you put 5 mA in to the LED side, you can conceivably get 100 mA out of the receiver side.
YOu wouldn't want to do this, because the absolute maximum output current rating is 60 mA. You should design your output circuit to limit the output current to substantially below 60 mA for best reliability.
Again whether that is enough depends on what load you are driving.
You should also note that the 2000% CTR specification is only a "typical" spec, and individual samples of this optocoupler could have substantially lower CTR.
(Hat tip to @JackCreasey for pointing out a couple of the issues discussed here)
But under absolute maximum ratings, it says that If can reach 20mA.
Absolute maximum ratings tell you how to avoid damaging the part. They don't tell you how you're expected to use the part normally.
From what I understand, my optocoupler should be fast enough, so that it can transmit the narrowest pulse (1% duty cycle), which has a duration of 1%*(1/1000) = 10μseconds. Consequently, I need to have: tr+tf < 10μsec,
Notice your 6N138 has typical propagation delays of 1 us (and maximum of 15 us) for low drive currents, so this part is probably not appropriate for your timing requirements.
• The 6N138 CANNOT EVER deliver 100mA output current. The average absolute maximum is specified as 60mAhttps://www.onsemi.com/pub/Collateral/HCPL2731M-D.pdf ...and since the application is for a PWM signal that could reach 100% this means that 60mA is the absolute maximum. Any decent design should also not use a CTR% ratio greater than 300% since you could end up with devices with only this CTR%. – Jack Creasey Mar 8 at 23:01
• -1 for also (like @JackCreasey ) quoting the worst case example of 15us with 1.2mA load when 2us is the worst case for a 12mA load. for the 6N139M at a huge cost (ha) of 0.31 and with If=12mA could be reduced to 10 and only needs a CTR here 100% – Sunnyskyguy EE75 Mar 9 at 3:02
• @JackCreasey, thanks for catching those points. Edited. – The Photon Mar 9 at 16:31
• @SunnyskyguyEE75, OP hasn't given us enough information to know whether the load will be closer to 1.2 mA or closer to 12 mA. – The Photon Mar 9 at 16:32
• @ThePhoton Yes the OP has been silent about many choices. But if you need to use this part for this purpose. It is possible to choose the I/O current levels and I/O configuration and Jack and yourself have why it can't used with assumptions. WHere I have shown one example of why it can be used by reducing the impedance, to make it work. The Miller effects can be used by reducing current gain and there are ways to reduce the current gain.with the base lead.to reduce the tPLH tPHL skew. His link showed nothing new.or about the prop delay skew which may be reduced further with CB and cascode – Sunnyskyguy EE75 Mar 9 at 17:21
Your input current should be designed considering:
1- A comfortable value that your source (in this case, the Beaglebone) can sustain. In this case, I would choose 1mA.
2- Looking the graphics of how your optocopler works.
3- Look for the current transfer ratio of your part.
In your case, you probably want to work the opto output always saturated (open or closed). So you should look "current transfer ratio". This will basically tell you how much current your output transistor will make available depending on your input current (forward current).
If you do your math, you will notice the current you calculated will be really high, but that's the "maximum value" you should get from the exit. In practice, the output transistor will just saturate and the current will be determined by your circuit. For example, if you connect the collector to 5V and your emitter to a 10k resistor to GND the maximum current available should be (5V - Vce) / 10k.
Just an observation, if you just want to drive some local circuit logic you can just use an NPN transistor. You didn't give any details about the application, but I don't see the any circuit requiring isolation from a common Beaglebone.
When transmitting digital signals, one step (where the voltage is low or high) is one bit. So the 10 µs is the length of one bit, which corresponds to 100 kbit/s.
The absolute maximum ratings tell you the limits beyond which the chip might let the magic smoke escape. This is not something you should use, but stay away from.
The LED current you should use is current the chip is designed for, which is the current for which the current transfer ratio is specified. In the case of the 6N138, this is 1.6 mA (0.5 mA is for the 6N139). With a guaranteed CTR of at least 300%, this means that you can switch 4.8 mA at the output. To be safe, use the suggested 2.2 kΩ load resistor to get a current of about 2.3 mA.
The 6N138 is rather slow for 100 kbps. You can speed it up with a Schottky diode, but it would be a better idea to use a faster optocoupler like the H11L1 (and with a digital optocoupler, you do not need to worry about the CTR).
1kHz PWM ...my opto-coupler should be fast enough, so that it can transmit the narrowest pulse (1% duty cycle), which has a duration of 1% * (1/1000) = 10 μs. Consequently, I need to have: tr + tf < 10 μs
Correct, but I would suggest you need delay times (not rise and fall times) much much less than 10us. You need to decide what fidelity you need for the output waveform. If you use the 6N138 then the delay times combined could be 65us worst case. At this you would get no viable PWM signal below about 6%. Even using the 'Typical' number, you could expect delay times to be 8.3us so severely distorting small PWM values.
This has nothing to do with the rise and fall times of the output, which are related to the load (Rl) and the capacitance of the load.
The datasheet shows:
From the above data I would suggest that the 6N138 would NOT be suitable for your application.
While there are many opto-isolators that might (when you decide how much distortion and edge delay you can tolerate) fill the bill, I'll suggest what might be a high end solution for you as an example.
The On Semiconductor FOD8071 has very low delay values and a true digital output signal (not open-collector). This device is based on a photodiode receiver, which is invariably much faster than any transistor based coupler. The spec snapshot is:
This type of device ensures that the accuracy of your input signal PWM signal is reflected in the output.
The input threshold current is about 3.5mA for this device, so selecting an input current range of 5-10mA should be good place to start. Your MCU output should be able to sink 10mA and with the Vf of the LED being in the 1-1.8V range then at a 3.3V MCU supply a 230 Ohm resistor would be adequate to define the input LED current. Over the full Vf range this would ensure 6.5-10mA LED current.
You should research opto-isolators in the 1Mbps and above range to get reasonable PWM distortion values. With 1Mbps capability you would expect delay times in the 200-600ns range which may be adequate for your purposes. Perhaps start with a search like this on Digikey.
Update: Understanding the turn on and turn off delays (you can call them rise time and fall times if you like, but they appear as edge delays in the circuit).
This application note on the very problem being discussed is relevant and performed at 1kHz square wave (equivalent to a PWM 50% signal).
They used a very common opto-isolator (PS2501-1) and characterized the turn on and turn off delays as rise and fall times. I disagree with that terminology, but the note aptly shows the delay in producing an edge assuming voltage sensitive logic on the output load. The datasheet for the opto quotes tr/tf at 3us and 5us respectively, but the app note shows the measured values at about 5us and 90us for tr/tf depending on output configuration.
They then attempt to speed up the circuitry adding a more complex output configuration (cascode), but even then only achieve 6us and 32us for tr/tf in their note.
This shows that this type of opto (transistor based) is unsuitable where you want to assure that the output signal accurately follows the input signal. Using an opto based on a photo-diode is invariably much faster, has almost symmetrical delays and is not dependent of high CTR.
This application note by Vishay gives a much more complete comparison of the performance of the various configurations. It also suggests to achieve highest speeds a photo-diode (CB junction) configuration use of the transistor based optos. Well worth reading.
• -1 for circling 2.2k load when 120 Ohms is optimal from 3.3 V into a slicer – Sunnyskyguy EE75 Mar 9 at 2:55
• ALso Prop delay is irrelevant. It could be 1 second or to the moon and back as long as the rise time allows 10us ON pulse time – Sunnyskyguy EE75 Mar 9 at 2:56
• @SunnyskyguyEE75 Thanks for the downvote. I did not circle the 2.2k Ohm load, so don't know hat you are alluding to. the 2.2k is the output pullup resistor, and the If is the LED current. They don't specify the resistor value for a 3.3V MCU and neither did I. However, increasing the LED current with the 6N138 INCREASES the delay times so making the problems with that part worse. But I'm guessing you can't see that either. Propagation delay is the most important characteristic for this part since it's highly asymmetrical and will result in severe pulse lengthening. – Jack Creasey Mar 9 at 6:08
• well you did mention "8.3us so severely distorting small PWM values." when the typ values for 270 Ohms which is what you should have been looking at are 0.2&1.3us for On and OFF, That's because going to off current is high impedance. An even smarter way is to use 12 mA On and 0.5mA off for $I_f$ then it never goes OFF ( continuous conduction mode) and reduces the Prop delay even more. CML (current mode logic) works >10x faster that switched CMOS. There are all sorts of tricks like CB drive and output base bias to speed up optos for cost sensitive designs. One can even get 10Mb/s optos – Sunnyskyguy EE75 Mar 9 at 8:51
• @SunnyskyguyEE75 You said "An even smarter way is to use 12 mA On and 0.5mA off for If then it never goes OFF ( continuous conduction mode) and reduces the Prop delay even more. CML (current mode logic) works >10x faster that switched CMOS" ….now you are just being ridiculous. The problem with opto-transistors is the time taken to clear the carriers from the junction. It might help you to read an appnote like this: cel.com/pdf/appnotes/an3009.pdf – Jack Creasey Mar 9 at 15:56
how the above calculations can be translated to bits per second, because everyone filters the optocouplers according to their Data rate (bps).
A 10 us pulse would be equivalent to a 100 kbps digital data rate. NRZ...01010 is 50 kHz or 20us
Since Tr=0.35/f-3dB = rise time 10~90% using 10101 = f/2 at bit rate = f **
for 10101 pattern cycle of 20us at 100kbps **NRZ max Tr= 7us
but lower is better for InterSymbol Interference ISI ( from group delay) so you get lower BER with more phase margin from reduced ISI. (eye pattern)
Another question is about the input current of the optocoupler. My microcontroller can only provide around 4-6 mA through its PWM ports.
No, that is only true for logic noise margin. Here the Logic margin is your OptoIsolator output. The port is spec'd as VOL Low-level output voltage, driver enabled, pullup or pulldown disabled IOL = 6 mA 0.45 V This means Zol= 0.45/6mA = 75 Ohm RdsOn , same for VOH. REF p90
N.B> Note that Cortex driver specs are worst case (+50%) and CMOS RdsOn at rate supply is usually 50 Ω +/-50% . ALV logic is 1/2 of Ω this. Short circuit power in driver is then 145 mW so you can include this Rs with your IR current limit calculations for series R. and use near IR max If current e.g. 12mA
I agree with @Photon, You want to look for the "current transfer ratio" or CTR and rise time. Worst case CTR can be 25% which is like Beta (hFE) in a transistor.
The only tradeoff is the speed or TPLH with a Darlington , which makes this design marginal.
So, for example, this datasheet is from the 6N138M optocoupler. One can see under the "features" section: "Low Current-0.5mA".
A single transistor when saturated has about 10~20% hFE same with a Darlington which has hFE² or a saturated gain of 10²=100
The datasheet WORST case propagation delay time is TPLH= 7us max 0~70'C and 1.3us typ at 25'C with the following conditions;
RL=270 Ω If=12mA with 270 Ω to 5V - (Vol(sat)=1.2V est.) yield Ic= 3.8V/270=14mA .
To get If=12mA from 3.3V 75 Ω Beagleboard CMOS driver is unstable/ unreliable due to Rdson and If resistance tolerances as temp changes VF which increases IR temp and exceeds MAX so a 5V current limit is better. Fig 4 in datasheet shows Vf ranges from 1.5V to 1.8V so ΔV=Vdd-Vf=1.8 to 1.5V so using 1.8V/12mA = 46Ω which is less than the Driver Rs 75 Ohms max(25 min) which also has a 25% tolerance. Using 1.5V/12mA=125Ω, Since the driver is 33 to 75 Ohms 126-70=56 Ohms
But under absolute maximum ratings, it says that If can reach 20mA.
There is also Fig 5 Vf vs Ta which says if you run at 1.5V the self-heating requires your ambient to be -40'C for cooling.
From what I understand, my optocoupler should be fast enough, so that it can transmit the narrowest pulse (1% duty cycle), which has a duration of 1%*(1/1000) = 10μseconds. Consequently, I need to have: tr+tf < 10μsec,
Yes, the rise time may meet the 7uS max requirement and I expect rise time to be less than propagation delay which is the only spec given. So rise time depends on bandwidth and prop delay.
# Conclusion
If you have 5V you must use this with driver Sch. Diode protection to regulate Vf so the temperature of IR diode has less effect on the If stability. Note: Duty Cycle affects avg current and temp also.
• 68.2k22398 You cannot use a simple conversion to bps for a PWM application. It's also not valid to talk about ISI or NRZ since this is not describing a PWM protocol. The OP has specified that the PWM is from 1%-100% so the rise and fall times impact the accuracy of the PWM signal. The OP needs to decide what distortion is allowable in the application and from that decide the minimum rise and fall times that can be tolerated. I would suggest that you will need 1Mbaud or beyond to achieve less than 5% distortion. – Jack Creasey Mar 8 at 23:19
• @JackCreasey WHat's the difference between 100kbps with a single 1 and 99 Zero's and a 1kHz PWM at 1% duty cycle? BTW I have designed a 4Mb/s modem using VITS line 22 that could stay sync with only 1 NRZ transition in 1000 bits. SO I do know what I am talking about, although your suggestion is also valid – Sunnyskyguy EE75 Mar 9 at 2:44
• No, you don't know what you are talking about. A PWM signal has a fixed frame rate so will never appear like an NRZ signal. The application is absolutely nothing like a modem. – Jack Creasey Mar 9 at 4:29
• THat's true but does not contradict what I said. nor support your doubt. The resolution BW is simply 0.35/rise time , sorry I disagree with your unsupported claim of irrelevance. It is very relevant and I proved it. I've done this before @JackCreasey BTW it's not a modem, just a pulse and 99% is worst case and ISI correlates with PW50 distortion !!! but if that's not good enuf for you, my 2nd answer ought to be. No explanation is necessary if you are an expert – Sunnyskyguy EE75 Mar 9 at 5:29
But uses a Common Base transistor. OptoDarlington is simulated with 1mA of 8% CTR to base with a fixed R.
If any doubt pls add questions in comments. Cost \$0.50
• You completely miss the point of delay effects. The delays are asymmetrical. In the case of the 6N138 the on delay is 1-15us and the off delay is 7.3-50us. Now feed a 10us pulse into that sort of delay and what will the output be? The rise and fall times of the output become quite irrelevant when you pulse stretch by up to 50us. If you can't see that as a problem I don't know how to help you. The CTR and risetime have very little to do with the response, it's the fact that a phototransistor is used as the Rx and they are notoriously slow. The model you show is not for an opto-isolator!!! – Jack Creasey Mar 9 at 5:54
• @JackCreasey The diode RC time constant can be optimized to meet this requirement. I am well aware how to do this, but that was not the question. Instead you and others have only said it's not possible by using poor choices for current ratios and load impedance. This is a result of not understanding the Miller Effects from RC*hFE can be improved by choosing the optimum current values to reduce hFE and thus reduce skew while decreasing turn off time. – Sunnyskyguy EE75 Mar 9 at 17:28
• What complete rubbish ….how can adding an RC time constant make the delay shorter??? – Jack Creasey Mar 9 at 17:30
• THe Miller effect is multiplied by hFE and hFE reduces from increasing currents to 12mA. THat's how, THey dont spec GBW which can be > 10MHz in the linear range too under careful design.. – Sunnyskyguy EE75 Mar 9 at 17:31
• The 12mA you refer to is the input LED current not the output current. Once again you simply confuse the parameters. – Jack Creasey Mar 9 at 17:33
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https://brilliant.org/problems/do-i-look-quadratic-to-you/
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# Do I look quadratic to you?
Algebra Level 2
The equation
$| x - 10 | = 7$
is equivalent to the equation
$x^2 + ax + b = 0.$
What is the value of $$a+b$$?
×
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https://xiaoqitan.org/
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# Xiaoqi Tan's Homepage
Postdoctoral Fellow Electrical & Computer Engineering, University of Toronto Bahen Centre for Information Technology, Room 7137 40 St. George Street, Toronto, Ontario M5S 2E4, Canada Email: x.y$${\text{[at]}}$$utoronto.ca, where x=xiaoqi, y=tan (My name is pronounced as “Shiao-Chee”)
## Biography
I am currently a Postdoc at the Dept. of Electrical & Computer Engineering, University of Toronto, hosted by Prof. Alberto Leon-Garcia. Prior to my current position, I received my Ph.D. in Electronic and Computer Engineering from Hong Kong University of Science and Technology, advised by Prof. Danny H.K. Tsang. From Oct. 2015 to April 2016, I was also affiliated with the School of Engineering and Applied Science, Harvard University, hosted by Prof. Na Li.
## Research Interests
I work on the algorithmic aspects of the interdisciplinary area between networking, energy and economics. Current topics of interest include
• online algorithms for optimization, mechanism design, and machine learning.
• network economics: pricing, auctions, and algorithmic game theory.
• networking: cloud and edge/fog computing, network resource allocation.
• energy systems: transactive energy, electric vehicle charging, and electricity markets.
## Selected Papers (Full List and Google Scholar)
• X. Tan, A. Leon-Garcia, Y. Wu, and D.H.K. Tsang, “Online Combinatorial Auctions for Resource Allocation with Supply Costs and Capacity Limits”, preprint. Earlier version appeared in ACM Sigmetrics Workshop on MAMA in 2019.
• X. Tan, A. Leon-Garcia, B. Sun and D.H.K. Tsang, “Agent-based Real-time Demand-Side Flexibility Management”, preprint. Extended abstract appeared in ACM e-Energy in 2019.
• X. Tan, A. Leon-Garcia, Y. Wu, and D.H.K. Tsang, “Posted-Price Retailing of Transactive Energy: An Optimal Online Mechanism without Prediction”, preprint.
• S. Wang, X. Tan, T. Liu, and D.H.K. Tsang, “Aggregation of Demand-Side Flexibility in Electricity Markets: Negative Impact Analysis and Mitigation Method”, preprint.
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|
https://www.sarthaks.com/102304/consider-point-focal-point-convergent-another-convergent-short-focal-length-placed-other
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# Consider a point at the focal point of a convergent lens. Another convergent lens of short focal length is placed on the other side.
3.1k views
in Physics
Consider a point at the focal point of a convergent lens. Another convergent lens of short focal length is placed on the other side. What is the nature of the wavefronts emerging from the final image?
by (63.6k points)
selected by
The nature of the wavefronts emerging from the final image is Spherical.
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https://www.hepdata.net/record/50327
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Comparison of 20 exclusive reactions at large t
Phys.Rev.D 49 (1994) 58-78, 1994.
Abstract (data abstract)
Brookhaven-AGS. Measurement of total elastic and differential cross sections in 20 exclusive reactions at incident momentum of 5.9 GeV.
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|
http://mathhelpforum.com/differential-geometry/120476-complex-integral-print.html
|
# Complex Integral
• December 14th 2009, 03:33 PM
canberra1454
Complex Integral
Show that
$\frac{1}{2 \pi} \int_{-\pi}^{\pi} \frac{1}{1-2r\cos \theta +r^2} d \theta = 1, 0 \leq r < 1$.
Right now, I don't see how to show this. I do see that the integrand is an even function if that helps at all. Also, since this is not from $-\infty$ to $\infty$, I do not know the method to proceed. I need a few hints on how to start.
• December 14th 2009, 05:12 PM
shawsend
Hi. If I use the $z=e^{it}$ substitution, then I get:
$\int_{-\pi}^{\pi}\frac{1}{1-2 r\cos(t)+r^2}dt=-i\oint \frac{dz}{(r-z)(rz-1)}=\frac{2\pi}{1-r^2},\quad |r|<1$
|
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https://www.physicsforums.com/threads/forces-acting-during-a-gunshot.736339/
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# Forces acting during a gunshot
1. Feb 3, 2014
### thetexan
My understanding is this...
a. The force acting to recoil the mass of the rifle and the mass of the shooter combined is equal (give or take small other masses such as gas) to the force acting to push the bullet down the barrel.
b. This means that all of that force you feel in your shoulder is the same as that acting on the tip end of that bullet as it enters the target (minus loss of energy during flight).
c. Since the the expanding gas is what is driving the bullet down the barrel you would think, at first, that the longer the barrel the more opportunity the gas has to accelerate the bullet. However, there comes a point where, when considering the friction between the bullet and the barrel, the gas no longer can accelerate the bullet and at that point the friction becomes a slowing factor. Therefore the point where this occurs determines the ideal length of the barrel...any shorter and the gas escapes before it finishes it acceleration....any longer and the friction of the barrel begins to decelerate the bullet absent the push from the gas.
Am I thinking correctly?
thanks,
tex
2. Feb 3, 2014
### Staff: Mentor
Pretty much, yes.
The details can get complicated: The force on the bullet is equal to the cross-section area of the bullet times the pressure behind it; as the bullet moves forward the volume increases and the pressure decreases; heat is transferred to the barrel which lowers the pressure; the combustion of the propellant is not instantaneous so the pressure may continue to build even after the bullet starts moving; and so forth. But you've got the basic concept down.
3. Feb 3, 2014
### .Scott
Even with a frictionless barrel, there would come a point where lengthening the barrel would slow the bullet.
The bullet is compressing the air in the barrel in front of it while the pressure in the barrel behind it decreases. Given a long enough barrel, the bullet would begin to decelerate - and perhaps even reverse direction.
4. Feb 3, 2014
### thetexan
Yes. There will be some point where all of the factors come into equilibrium and after that point we're losing ground.
5. Feb 4, 2014
### A.T.
Right. If you want to build a super-cannon, you need multiple charges along the way (multi-charge gun):
http://en.wikipedia.org/wiki/V-3_cannon
6. Feb 4, 2014
### bahamagreen
Some of the force is spent imparting the spin of the bullet (rifling in the barrel).
Similar Discussions: Forces acting during a gunshot
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https://www.bartleby.com/solution-answer/chapter-113-problem-82e-finite-mathematics-and-applied-calculus-mindtap-course-list-7th-edition/9781337274203/pricing-policy-let-us-turn-exercise-81-around-a-little-dorothy-wagner-is-currently-selling-20-i/4553dd69-5c01-11e9-8385-02ee952b546e
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Chapter 11.3, Problem 82E
### Finite Mathematics and Applied Cal...
7th Edition
Stefan Waner + 1 other
ISBN: 9781337274203
Chapter
Section
### Finite Mathematics and Applied Cal...
7th Edition
Stefan Waner + 1 other
ISBN: 9781337274203
Textbook Problem
# Pricing Policy Let us turn Exercise 81 around a little: Dorothy Wagner is currently selling 20 “I ♥ Calculus” T-shirts per day, but sales are dropping at a rate of 3 per day. She is currently charging $7 per T-shirt, and she wishes to increase her daily revenue by$10 per day. At what rate should she increase the unit price to accomplish this (assuming that the price increase does not affect sales)?
To determine
To calculate: The rate by which Dorothy Wagner should increase the price per unit such that her daily revenue increases by $10 per day where daily sales of Dorothy Wagner’s 20 “I ♥? Calculus” T-shirts is dropping at a rate of 3 per day and she is currently charging$7 per T-shirt.
Explanation
Given Information:
The daily revenue increases by $10 per day where daily sales of Dorothy Wagner’s 20 “I ♥? Calculus” T-shirts is dropping at a rate of 3 per day and she is currently charging$7 per T-shirt.
Formula used:
Product rule of derivative of differentiable functions, f(x) and g(x) is
ddx[f(x)g(x)]=f'(x)g(x)+f(x)g'(x)
Calculation:
Assume the function S(t) be the number of T-shirts sold in 1 day.
As 20 T-shirts are sold in 0th day.
So,
S(0)=20
And rate of number of T-shirt’s is decreasing by 3 per day
So,
S'(0)=3
Assume the function P(t) be the price of 1 T-shirt.
At 0th day the price was \$7 per T-shirt.
So,
P(0)=7
As, revenue R(t)=P(t)Q(t)
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https://searxiv.org/search?author=Christian%20Burkert
|
### Results for "Christian Burkert"
total 12039took 0.14s
Tracking Users across the Web via TLS Session ResumptionOct 16 2018User tracking on the Internet can come in various forms, e.g., via cookies or by fingerprinting web browsers. A technique that got less attention so far is user tracking based on TLS and specifically based on the TLS session resumption mechanism. To the ... More
QUICker connection establishment with out-of-band validation tokensApr 12 2019May 03 2019QUIC is a secure transport protocol that improves the performance of HTTPS. An initial QUIC handshake that enforces a strict validation of the client's source address requires two round-trips. In this work, we extend QUIC's address validation mechanism ... More
The Effect of Gas Loss on the Formation of Bound Stellar ClustersJul 27 2000The effect of gas ejection on the structure and binding energy of newly formed stellar clusters is investigated. The star formation efficiency (SFE), necessary for forming a gravitationally bound stellar cluster, is determined. Two sets of numerical N-body ... More
Simulations of Direct Collisions of Gas Clouds with the Central Black HoleAug 07 2009Oct 27 2010We perform numerical simulations of clouds in the Galactic Centre (GC) engulfing the nuclear super-massive black hole and show that this mechanism leads to the formation of gaseous accretion discs with properties that are similar to the expected gaseous ... More
QUICker connection establishment with out-of-band validation tokensApr 12 2019QUIC is a secure transport protocol and aims to improve the performance of HTTPS traffic. It is a design goal of QUIC to reduce the delay overhead of its connection establishment. However, an initial handshake enforcing strict validation of the client's ... More
Enhanced Performance and Privacy for TLS over TCP Fast OpenMay 09 2019Small TCP flows make up the majority of web flows. For them, the TCP three-way handshake represents a significant delay overhead. The TCP Fast Open (TFO) protocol provides zero round-trip time (0-RTT) handshakes for subsequent TCP connections to the same ... More
Physics of the Galactic Center Cloud G2, on its Way towards the Super-Massive Black HoleJan 06 2012The origin, structure and evolution of the small gas cloud, G2, is investigated, that is on an orbit almost straight into the Galactic central supermassive black hole (SMBH). G2 is a sensitive probe of the hot accretion zone of Sgr A*, requiring gas temperatures ... More
Do dwarf spheroidal galaxies contain dark matter?Oct 24 1996The amount of dark matter in the four galactic dwarf spheroidals with large mass-to-light ratios is investigated. Sextans has a cut-off radius which is equal to the expected tidal radius, assuming a high mass-to-light ratio. This satellite very likely ... More
The Challenge of Modelling Galactic DisksDec 10 2008Dec 12 2008Detailed models of galactic disk formation and evolution require knowledge about the initial conditions under which disk galaxies form, the boundary conditions that affect their secular evolution and the micro-physical processes that drive the multi-phase ... More
Star Formation in Turbulent Molecular CloudsMay 17 2001Recent progress in the understanding of star formation is summarized. A consistent picture is emerging where molecular clouds form with turbulent velocity fields and clumpy substructure, imprinted already during their formation. The clouds are initially ... More
The structure of dark matter halos. Observation versus theoryMar 10 1997The rotation curves of dark matter dominated dwarf galaxies are analysed. The observations show that dark matter halos represent a one-parameter family with self similar density profiles. The global halo parameters, like total mass and scale length are ... More
Balance among gravitational instability, star formation, and accretion determines the structure and evolution of disk galaxiesMay 13 2013May 15 2013Over the past 10 Gyr, star-forming galaxies have changed dramatically, from clumpy and gas rich, to rather quiescent stellar-dominated disks with specific star formation rates lower by factors of a few tens. We present a general theoretical model for ... More
Self-Interacting Cold Dark Matter HalosDec 08 2000The evolution of halos consisting of weakly self-interacting dark matter particles is summarized. The halos initially contain a central density cusp as predicted by cosmological models. Weak self-interaction leads to the formation of an isothermal, low-density ... More
The structure and evolution of weakly self-interacting cold dark matter halosFeb 22 2000Apr 18 2000The evolution of halos consisting of weakly self-interacting dark matter particles is investigated using a new numerical Monte-Carlo N-body method. The halos initially contain kinematically cold, dense 1/r-power-law cores. For interaction cross sections ... More
Galactic Disk Formation and the Angular Momentum ProblemAug 10 2009Galactic disk formation requires knowledge about the initial conditions under which disk galaxies form, the boundary conditions that affect their secular evolution and the micro-physical processes that drive the multi-phase interstellar medium and regulate ... More
Stellar Feedback Processes: Their Impact on Star Formation and Galactic EvolutionApr 01 2004The conditions that lead to self-regulated star formation, star bursts and the formation of massive stellar clusters are discussed. Massive stars have a strong impact on their environment, especially on the evolution of dwarf galaxies which are the building ... More
The Formation of the Milky Way in the Cosmological ContextMay 17 2001The formation of the Milky Way is discussed within the context of the cold dark matter scenario. Several problems arise which can be solved if the Galaxy experienced an early phase of gas heating and decoupling from the dark matter substructure. This ... More
The geometry and origin of ultra-diffuse ghost galaxiesAug 31 2016Sep 02 2016The geometry and intrinsic ellipticity distribution of ultra diffuse galaxies (UDGs) is determined from the line-of-sight distribution of axial ratios q of a large sample of UDGs, detected by Koda et al. (2015) in the Coma cluster. With high significance ... More
The Structure of Dark Matter Haloes in Dwarf GalaxiesApr 12 1995Recent observations indicate that dark matter haloes have flat central density profiles. Cosmological simulations with non-baryonic dark matter predict however self similar haloes with central density cusps. This contradiction has lead to the conclusion ... More
On the Formation of Elliptical GalaxiesMar 07 1994It is shown that the violent relaxation of dissipationless stellar systems leads to universal de Vaucouleurs profiles only outside 1.5 effective radii $R_e$. Inside $1.5 R_e$ the surface density profiles depend strongly on the initial conditions and are ... More
The Cosmological Angular Momentum Problem of Low-Mass Disk GalaxiesJul 05 2000The rotational properties of the visible and dark components of low-mass disk galaxies (vrot<=100 km/s) are investigated using the Swaters sample. The rotational parameter lambda'=lambda_DM*(j_d/m_d) is determined, where lambda_DM is the dark halo spin ... More
The Structure and Dark Halo Core Properties of Dwarf Spheroidal GalaxiesJan 26 2015Jun 22 2015The structure and dark matter halo core properties of dwarf spheroidal galaxies (dSphs) are investigated. A double-isothermal model of an isothermal stellar system, embedded in an isothermal dark halo core provides an excellent fit to the various observed ... More
The Turbulent Interstellar MediumMay 03 2006An overview is presented of the main properties of the interstellar medium. Evidence is summarized that the interstellar medium is highly turbulent, driven on different length scales by various energetic processes. Large-scale turbulence determines the ... More
Recent results on the nucleon resonance spectrum and structure from the CLAS detectorAug 17 2015The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the $\gamma_{v}pN^*$ transition amplitudes (electrocouplings) are ... More
Thermal Quantum Fields without Cut-offs in 1+1 Space-time DimensionsMar 26 2004We construct interacting quantum fields in 1+1 dimensional Minkowski space, representing neutral scalar bosons at positive temperature. Our work is based on prior work by Klein and Landau and Hoegh-Krohn
On the relativistic KMS condition for the P(φ)_2 modelSep 29 2006The relativistic KMS condition introduced by Bros and Buchholz provides a link between quantum statistical mechanics and quantum field theory. We show that for the $P(\phi)_2$ model at positive temperature, the two point function for fields satisfies ... More
Friction force: from mechanics to thermodynamicsNov 17 2009Jul 01 2010We study some mechanical problems in which a friction force is acting on the system. Using the fundamental concepts of state, time evolution and energy conservation we explain how to extend Newtonian mechanics to thermodynamics. We arrive at the two laws ... More
Duck Traps: Two-dimensional Critical Manifolds in Planar SystemsAug 30 2018Nov 05 2018In this work we consider two-dimensional critical manifolds in planar fast-slow systems near fold and so-called canard (=duck') points. These higher-dimension, and lower-codimension, situation is directly motivated by the case of hysteresis operators ... More
Relaxed Logarithmic Barrier Function Based Model Predictive Control of Linear SystemsMar 11 2015In this paper, we investigate the use of relaxed logarithmic barrier functions in the context of linear model predictive control. We present results that allow to guarantee asymptotic stability of the corresponding closed-loop system, and discuss further ... More
A stabilizing iteration scheme for model predictive control based on relaxed barrier functionsMar 15 2016Apr 06 2016We propose and analyze a stabilizing iteration scheme for the algorithmic implementation of model predictive control for linear discrete-time systems. Polytopic input and state constraints are considered and handled by means of so-called relaxed logarithmic ... More
Differential Characters and Geometric ChainsMar 26 2013Apr 09 2013We study Cheeger-Simons differential characters and provide geometric descriptions of the ring structure and of the fiber integration map. The uniqueness of differential cohomology (up to unique natural transformation) is proved by deriving an explicit ... More
Distances and large deviations in the spatial preferential attachment modelSep 26 2018Sep 27 2018We investigate two asymptotic properties of a spatial preferential-attachment model introduced by E. Jacob and P. M\"orters (2013). First, in a regime of strong linear reinforcement, we show that typical distances are at most of doubly-logarithmic order. ... More
On the Vacuum Polarization Density Caused by an External FieldJul 01 2003Feb 11 2004We consider an external potential, $-\lambda \phi$, due to one or more nuclei. Following the Dirac picture such a potential polarizes the vacuum. The polarization density as derived in physics literature, after a well known renormalization procedure, ... More
Quantum field theory meets Hopf algebraNov 14 2006Sep 11 2010This paper provides a primer in quantum field theory (QFT) based on Hopf algebra and describes new Hopf algebraic constructions inspired by QFT concepts. The following QFT concepts are introduced: chronological products, S-matrix, Feynman diagrams, connected ... More
A differential identity for Green functionsFeb 15 2006If P is a differential operator with constant coefficients, an identity is derived to calculate the action of exp(P) on the product of two functions. In many-body theory, P describes the interaction Hamiltonian and the identity yields a hierarchy of Green ... More
Quantum groups and interacting quantum fieldsAug 19 2002If C is a cocommutative coalgebra, a bialgebra structure can be given to the symmetric algebra S(C). The symmetric product is twisted by a Laplace pairing and the twisted product of any number of elements of S(C) is calculated explicitly. This is used ... More
Continuous-Variable Quantum Key Distribution with Entanglement in the MiddleMay 07 2012We analyze the performance of continuous-variable quantum key distribution protocols where the entangled source originates not from one of the trusted parties, Alice or Bob, but from the malicious eavesdropper in the middle. This is in contrast to the ... More
Tight Running Time Lower Bounds for Vertex Deletion ProblemsNov 17 2015May 17 2016For a graph class $\Pi$, the $\Pi$-Vertex Deletion problem has as input an undirected graph $G=(V,E)$ and an integer $k$ and asks whether there is a set of at most $k$ vertices that can be deleted from $G$ such that the resulting graph is a member of ... More
A quantum-information-theoretic complement to a general-relativistic implementation of a beyond-Turing computerMay 21 2014Jun 11 2014There exists a growing literature on the so-called physical Church-Turing thesis in a relativistic spacetime setting. The physical Church-Turing thesis is the conjecture that no computing device that is physically realizable (even in principle) can exceed ... More
Vacuum Polarisation Tensors in Constant Electromagnetic Fields: Part IJan 27 2000Dec 29 2000The string-inspired technique is used for the calculation of vacuum polarisation tensors in constant electromagnetic fields. In the first part of this series, we give a detailed exposition of the method for the case of the QED one-loop N-photon amplitude ... More
Blue Stragglers in Globular Clusters: Observations, Statistics and PhysicsJun 13 2014This chapter explores how we might use the observed {\em statistics} of blue stragglers in globular clusters to shed light on their formation. This means we will touch on topics also discussed elsewhere in this book, such as the discovery and implications ... More
Dualité onde-corpuscule formée par une masselotte oscillante dans un milieu élastique : étude théorique et similitudes quantiquesSep 29 2016We introduce a dual wave-particle macroscopic system, where a bead oscillator oscillates in an elastic media which obeys the Klein-Gordon equation. This theoretical system comes mainly from bouncing drops experiments and also a sliding bead on a vibrating ... More
On the geometry of metric measure spaces with variable curvature boundsJun 10 2015Sep 09 2015Motivated by a classical comparison result of J. C. F. Sturm we introduce a curvature-dimension condition CD(k,N) for general metric measure spaces and variable lower curvature bound k. In the case of non-zero constant lower curvature our approach coincides ... More
On the logarithm of the characteristic polynomial of the Ginibre ensembleJul 30 2015We prove a slightly sharper version of a result of Rider and Vir\'ag who proved that after centering, the logarithm of the absolute value of the characteristic polynomial of the Ginibre ensemble converges in law to the Gaussian Free Field on the unit ... More
Maximum Matching in Turnstile StreamsMay 06 2015We consider the unweighted bipartite maximum matching problem in the one-pass turnstile streaming model where the input stream consists of edge insertions and deletions. In the insertion-only model, a one-pass $2$-approximation streaming algorithm can ... More
Cosmology and gravitational waves in the Nordstrom-Vlasov system, a laboratory for Dark EnergyJan 24 2013We discuss a cosmological solution of the system which was originally introduced by Calogero and is today popularly known as "Nordstrom-Vlasov system". Although the model is un-physical, its cosmological solution results interesting for the same reasons ... More
Effective temperature for black holesJul 26 2011Jul 28 2011The physical interpretation of black hole's quasinormal modes is fundamental for realizing unitary quantum gravity theory as black holes are considered theoretical laboratories for testing models of such an ultimate theory and their quasinormal modes ... More
A precise response function for the magnetic component of Gravitational Waves in Scalar-Tensor GravityFeb 03 2011Feb 04 2011The important issue of the magnetic component of gravitational waves (GWs) has been considered in various papers in the literature. From such analyses, it resulted that such a magnetic component becomes particularly important in the high frequency portion ... More
A longitudinal component in massive gravitational waves arising from a bimetric theory of gravityNov 06 2008After a brief review of the work of de Paula, Miranda and Marinho on massive gravitational waves arising from a bimetric theory of gravity, in this paper it is shown that the presence of the mass generates a longi- tudinal component in a particular polarization ... More
Analysis of the transverse effect of Einstein's gravitational wavesJul 13 2007The investigation of the transverse effect of gravitational waves (GWs) could constitute a further tool to discriminate among several relativistic theories of gravity on the ground. After a review of the TT gauge, the transverse effect of GWs arising ... More
Interpretation of Mössbauer experiment in a rotating system: a new proof for general relativityFeb 14 2015A historical experiment by K\"undig on the transverse Doppler shift in a rotating system measured with the M\"ossbauer effect has been recently first re-analyzed and then replied [1,2]. The results have shown that a correct re-processing of K\"undig's ... More
Black hole quantum spectrumOct 26 2012Nov 19 2013Introducing a black hole (BH) effective temperature, which takes into account both the non-strictly thermal character of Hawking radiation and the countable behavior of emissions of subsequent Hawking quanta, we recently re-analysed BH quasi-normal modes ... More
Massive relic gravitational waves from f(R) theories of gravity: production and potential detectionJul 23 2010The production of a stochastic background of relic gravitational waves is well known in various works in the literature, where, by using the so called adiabatically-amplified zero-point fluctuations process, it has been shown how the standard inflationary ... More
A review of the stochastic background of gravitational waves in f(R) gravity with WMAP constrainsJan 09 2009Jan 15 2009This paper is a review of previous works on the stochastic background of gravitational waves (SBGWs) which has been discussed in various peer-reviewed journals and international conferences. The SBGWs is analyzed with the aid of the Wilkinson Microwave ... More
A non-geodesic motion in the R^-1 theory of gravity tuned with observationsJan 01 2008Jan 11 2008In the general picture of high order theories of gravity, recently, the R^-1 theory has been analyzed in two different frameworks. In this letter a third context is added, considering an explicit coupling between the R^-1 function of the Ricci scalar ... More
The production of matter from curvature in a particular linearized high order theory of gravity and the longitudinal response function of interferometersMar 26 2007The strict analogy between scalar-tensor theories of gravity and high order gravity is well known in literature. In this paper it is shown that, from a particular high order gravity theory known in literature, it is possible to produce, in the linearized ... More
Scattering theory for Klein-Gordon equations with non-positive energyJan 11 2011Sep 09 2011We study the scattering theory for charged Klein-Gordon equations: $\{{array}{l} (\p_{t}- \i v(x))^{2}\phi(t,x) \epsilon^{2}(x, D_{x})\phi(t,x)=0,[2mm] \phi(0, x)= f_{0}, [2mm] \i^{-1} \p_{t}\phi(0, x)= f_{1}, {array}.$ where: \[\epsilon^{2}(x, D_{x})= ... More
Spectral and scattering theory of charged $P(\varphi)_2$ modelsJun 30 2009We consider in this paper space-cutoff charged $P(\varphi)_{2}$ models arising from the quantization of the non-linear charged Klein-Gordon equation: \[ (\p_{t}+\i V(x))^{2}\phi(t, x)+ (-\Delta_{x}+ m^{2})\phi(t,x)+ g(x)\p_{\overline{z}}P(\phi(t,x), \overline{\phi}(t,x))=0, ... More
k-Means Clustering Is Matrix FactorizationDec 23 2015We show that the objective function of conventional k-means clustering can be expressed as the Frobenius norm of the difference of a data matrix and a low rank approximation of that data matrix. In short, we show that k-means clustering is a matrix factorization ... More
Galilean IsometriesMar 09 2009We introduce three nested Lie algebras of infinitesimal isometries' of a Galilei space-time structure which play the r\^ole of the algebra of Killing vector fields of a relativistic Lorentz space-time. Non trivial extensions of these Lie algebras arise ... More
The Mössbauer rotor experiment and the general theory of relativityFeb 12 2016Feb 16 2016This paper is a rebuttal to Eur. Phys. Jour. Plus 130, 191 (2015), which claims that the results in arXiv:1502.04911 (Ann. Phys. 355, 360 (2015)) are incorrect. For this reason, some of the results in arXiv:1502.04911 have been reviewed and clarified. ... More
A quantitative theory for the continuity equationFeb 09 2016Mar 24 2016In this work, we provide stability estimates for the continuity equation with Sobolev vector fields. The results are inferred from contraction estimates for certain logarithmic Kantorovich--Rubinstein distances. As a by-product, we obtain a new proof ... More
Magnetically driven outflows from Jovian circum-planetaryaccretion disksOct 01 2003We discuss the possibility to launch outflows from the close vicinity of a protoplanetary core considering a scenario where the protoplanet surrounded by a circum-planetary accretion disk is located in a circum-stellar disk. For the circum-planetary disk ... More
Moments and Classification for Conjugation-Invariant Rotations and Fake Uniformity in the Stochastic Radon TransformMar 06 2012We consider a generalisation of the stochastic Radon transform, introduced for an inverse problem in tomography by Panaretos. Specifically, we allow the distribution of the three-dimensional rotation in the statistical model of that work to be different ... More
Varieties of *-regular ringsApr 09 2019Apr 11 2019Given a subdirectly irreducible *-regular ring R, we show that R is a homomorphic image of a regular *-subring of an ultraproduct of the (simple) eRe, e in the minimal ideal of R; moreover, R (with unit) is directly finite if all eRe are unit-regular. ... More
Quantum correlations are weaved by the spinors of the Euclidean primitivesMay 30 2018The exceptional Lie group E8 plays a prominent role in both mathematics and theoretical physics. It is the largest symmetry group associated with the most general possible normed division algebra, namely, that of the non-associative real octonions, which ... More
On a Surprising Oversight by John S. Bell in the Proof of his Famous TheoremApr 03 2017Nov 11 2018Bell inequalities are usually derived by assuming locality and realism, and therefore experimental violations of Bell inequalities are usually taken to imply violations of either locality or realism, or both. But, after reviewing an oversight by Bell, ... More
Refutation of Richard Gill's Argument Against my Disproof of Bell's TheoremMar 12 2012Mar 06 2017I identify a number of errors in Richard Gill's purported refutation (arXiv:1203.1504) of my disproof of Bell's theorem. In particular, I point out that his central argument is based, not only on a rather trivial misreading of my counterexample to Bell's ... More
Restoring Local Causality and Objective Reality to the Entangled PhotonsJun 03 2011May 02 2012Unlike our basic theories of space and time, quantum mechanics is not a locally causal theory. Moreover, it is widely believed that any hopes of restoring local causality within a realistic theory have been undermined by Bell's theorem and its supporting ... More
Disproofs of Bell, GHZ, and Hardy Type Theorems and the Illusion of EntanglementApr 28 2009Oct 24 2010An elementary topological error in Bell's representation of the EPR elements of reality is identified. Once recognized, it leads to a topologically correct local-realistic framework that provides exact, deterministic, and local underpinning of at least ... More
Disproof of Bell's Theorem: Reply to CriticsMar 26 2007Jan 03 2008This is a collection of my responses to the criticisms of my argument against the impossibility proof of John Bell, which aims to undermine any conceivable local realistic completion of quantum mechanics. I plan to periodically update this preprint instead ... More
Testing Gravity-Driven Collapse of the Wavefunction via Cosmogenic NeutrinosMar 01 2005Oct 12 2005It is pointed out that the Diosi-Penrose ansatz for gravity-induced quantum state reduction can be tested by observing oscillations in the flavor ratios of neutrinos originated at cosmological distances. Since such a test would be almost free of environmental ... More
Why the Quantum Must Yield to GravityOct 26 1998Mar 08 1999After providing an extensive overview of the conceptual elements -- such as Einstein's `hole argument' -- that underpin Penrose's proposal for gravitationally induced quantum state reduction, the proposal is constructively criticised. Penrose has suggested ... More
Disproof of Bell's TheoremMar 09 2011Oct 15 2015We illustrate an explicit counterexample to Bell's theorem by constructing a pair of spin variables in S^3 that exactly reproduces the EPR-Bohm correlation in a manifestly local-realistic manner.
Disproof of Bell's Theorem by Clifford Algebra Valued Local VariablesMar 20 2007Apr 22 2010It is shown that Bell's theorem fails for the Clifford algebra valued local realistic variables. This is made evident by exactly reproducing quantum mechanical expectation value for the EPR-Bohm type spin correlations observable by means of a local, deterministic, ... More
Rectangular Statistical Cartograms in R: The recmap PackageJun 01 2016Mar 24 2017Cartogram drawing is a technique for showing geography-related statistical information, such as demographic and epidemiological data. The idea is to distort a map by resizing its regions according to a statistical parameter by keeping the map recognizable. ... More
Towards an Algebraic Theory of Analogical Reasoning in Logic ProgrammingSep 26 2018Analogy-making is an essential part of human intelligence and creativity. This paper proposes an algebraic model of analogical reasoning in logic programming based on the syntactic composition and decomposition of programs. The main idea is to define ... More
Golomb's conjecture on prime gapsApr 23 2016Question 10208b (1992) of the American Mathematical Monthly asked: does there exist an increasing sequence $\{a_k\}$ of positive integers and a constant $B > 0$ having the property that $\{ a_k + n\}$ contains no more than $B$ primes for every integer ... More
Recursive Numerical Evaluation of the Cumulative Bivariate Normal DistributionApr 21 2010We propose an algorithm for evaluation of the cumulative bivariate normal distribution, building upon Marsaglia's ideas for evaluation of the cumulative univariate normal distribution. The algorithm is mathematically transparent, delivers competitive ... More
Constructive homotopy theory of marked semisimplicial setsSep 28 2018We develop the homotopy theory of semisimplicial sets constructively and without reference to point-set topology to obtain a constructive model for $\omega$-groupoids. Most of the development is folklore, but for a few results the author is unaware of ... More
Immersions of surfaces in almost complex 4-manifoldsAug 31 2000In this note, we investigate the relation between double points and complex points of immersed surfaces in almost-complex 4-manifolds and show how estimates for the minimal genus of embedded surfaces lead to inequalities between the number of double points ... More
Modularity experiments on $S_4$-symmetric double octicsOct 08 2018We will invest quite some computer power to find double octic threefolds that are connected to weight four modular forms.
Exponentials form a basis of discrete holomorphic functionsOct 08 2002We show that discrete exponentials form a basis of discrete holomorphic functions. On a convex, the discrete polynomials form a basis as well.
Normal crossing singularities and Hodge theory over Artin ringsApr 30 2012We develop a Hodge theory for relative simple normal crossing varieties over an Artinian base scheme. We introduce the notion of a mixed Hodge structure over an Artin ring, which axiomatizes the structure that is found on the cohomology of such a variety. ... More
The Saxl Conjecture and the Dominance OrderOct 24 2014May 05 2015In 2012 Jan Saxl conjectured that all irreducible representations of the symmetric group occur in the decomposition of the tensor square of the irreducible representation corresponding to the staircase partition. We make progress on this conjecture by ... More
Geometrically formal 4-manifolds with nonnegative sectional curvatureDec 06 2012Jan 31 2015A Riemannian manifold is called geometrically formal if the wedge product of any two harmonic forms is again harmonic. We classify geometrically formal compact 4-manifolds with nonnegative sectional curvature. If the sectional curvature is strictly positive, ... More
Uniruled Surfaces of General TypeAug 24 2006Nov 06 2006We give a systematic construction of uniruled surfaces in positive characteristic. Using this construction, we find surfaces of general type with non-trivial vector fields, surfaces with arbitrarily non-reduced Picard schemes as well as surfaces with ... More
Non-classical Godeaux SurfacesApr 21 2008Aug 25 2008A non-classical Godeaux surface is a minimal surface of general type with $\chi=K^2=1$ but with $h^{01}\neq0$. We prove that such surfaces fulfill $h^{01}=1$ and they can exist only over fields of positive characteristic at most 5. Like non-classical ... More
Algebraic Surfaces of General Type with Small c_1^2 in Positive CharacteristicFeb 19 2007Oct 26 2007We establish Noether's inequality for surfaces of general type in positive characteristic.Then we extend Enriques' and Horikawa's classification of surfaces on the Noether line, the so-called Horikawa surfaces. We construct examples for all possible numerical ... More
A counterexample for a problem on quasi Baer modulesMay 08 2016Mar 13 2017In this note we answer two questions on quasi-Baer modules raised by Lee and Rizvi in J.Algebra (2016).
The Canonical Map and Horikawa Surfaces in Positive CharacteristicApr 10 2010Dec 20 2011We extend fundamental inequalities related to the canonical map of surfaces of general type to positive characteristic. Next, we classify surfaces on the Noether lines, i.e., even and odd Horikawa surfaces, in positive characteristic. We describe their ... More
On a new collection of words in the Catalan familyApr 07 2014May 23 2014In this note, we provide a bijection between a new collection of words on nonnegative integers of length n and Dyck paths of length 2n-2, thus proving that this collection belongs to the Catalan family. The surprising key step in this bijection is the ... More
Modules Whose Small Submodules Have Krull DimensionJul 21 1998The main aim of this paper is to show that an AB5*-module whose small submodules have Krull dimension has a radical having Krull dimension. The proof uses the notion of dual Goldie dimension.
On the base locus of the linear system of generalized theta functionsJul 23 2007Apr 14 2008Let $\cM_r$ denote the moduli space of semi-stable rank-$r$ vector bundles with trivial determinant over a smooth projective curve $C$ of genus $g$. In this paper we study the base locus $\cB_r \subset \cM_r$ of the linear system of the determinant line ... More
Fake uniformity in a shape inversion formulaMar 06 2012Dec 29 2017We revisit a shape inversion formula derived by Panaretos in the context of a particle density estimation problem with unknown rotation of the particle. A distribution is presented which imitates, or 'fakes', the uniformity or Haar distribution that is ... More
Simple groups of birational transformations in dimension twoFeb 26 2018We classify simple groups that act by birational transformations on compact complex K\"ahler surfaces. Moreover, we show that every finitely generated simple group that acts non-trivially by birational transformations on a projective surface over an arbitrary ... More
emgr - The Empirical Gramian FrameworkNov 02 2016May 28 2018System Gramian matrices are a well-known encoding for properties of input-output systems such as controllability, observability or minimality. These so-called system Gramians were developed in linear system theory for applications such as model order ... More
Reflexivity of Newton-Okounkov bodies of partial flag varietiesFeb 19 2019Assume that the valuation semigroup $\Gamma(\lambda)$ of an arbitrary partial flag variety corresponding to the line bundle $\mathcal L_\lambda$ constructed via a full-rank valuation is finitely generated and saturated. We use Ehrhart theory to prove ... More
There is a $3\times3$ Magic Square of Squares on the Moon - A Lot of Them, ActuallyNov 09 2018Nov 19 2018Magic squares have been well explored here on Earth [1], but there appears to have been little-to-no examination of $\textit{lunar}$ magic squares. Some kinds of magic squares exist on the moon (i.e. under lunar arithmetic) but not on Earth (i.e. under ... More
Theory status of hadronic top-quark pair productionOct 11 2018The status of theoretical predictions for top-quark pair production at hadron colliders is reviewed, focusing on the total cross section, differential distributions, and the description of top-quark production and decay including off-shell effects.
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https://ashpublications.org/blood/article/132/Supplement%201/4837/262316/40-Is-the-New-50-Reducing-the-Need-for-Platelet
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Introduction: Patients with hematologic malignancies frequently require lumbar punctures (LPs) for administration of intrathecal chemotherapy. With myelosuppressive chemotherapy, thrombocytopenia is common and patients often require platelet transfusions in order to reduce the risk of bleeding during invasive procedures. However, there is a dearth of evidence supporting a platelet threshold required for LPs. Guidelines from the American Association of Blood Banks recommend a minimum platelet count of 50 x 103/µL, but this is based largely on expert opinion. Platelet transfusion is associated with risk of transfusion reaction and alloimmunization, cost, and procedural delays. Given these risks, we instituted a reduction in platelet threshold to 40 x 103/µL for lumbar puncture. We retrospectively reviewed patient outcomes to assess the safety and efficacy of this approach.
Methods: In November 2017, a platelet count threshold for LPs was introduced for adult oncology patients in both the inpatient and outpatient settings at Froedtert and the Medical College of Wisconsin. Previous guidelines recommended a platelet count of 50 x 103/µL in order to undergo a lumbar puncture. This threshold was decreased to 40 x 103/µL for oncology patients. Guidelines were agreed upon and implemented in all procedure settings: the inpatient procedure team, the outpatient procedure suite, and the radiology department (for fluoroscopy-guided lumbar puncture). Data regarding the pre-procedure platelet count, number of platelet transfusions given per procedure, CSF RBCs, and occurrence of post-procedure spinal hematomas were collected through the electronic medical record.
Results: From November 1, 2016 to May 1, 2018 267 oncology patients underwent a lumbar puncture. Oncologic diagnosis was NHL, ALL, AML, solid malignancy, or other hematologic malignancy/disorder in 26%, 23%, 18%, 16%, and 17%, respectively. 42% of were female. A total of 845 LPs were performed under fluoroscopy, with ultrasound guidance, and by an experienced provider in 26%, 58%, and 16% of cases respectively. 534 LPs (63%) were performed with a platelet transfusion threshold of 50 x 103/µL (Plt≥50) and 311 LPs (37%) were performed with a platelet transfusion threshold of 40 x 103/µL (Plt≥40). The average pre-LP platelet count was 152.8 x 103/µL in the Plt≥50 group and 138.4 x 103/µL in the Plt≥40 group. 79 patients in the Plt≥50 group and 42 patients in the Plt≥40 group had a recorded platelet count between 40-49 x 103/µL within 24 hours prior to the procedure. After institution of the new guidelines, 40 LPs were performed with a platelet count < 50 x 103/µL. The average number of units of platelets transfused per procedure significantly decreased from 0.58 to 0.39 after lowering the transfusion threshold (p < 0.05). One lumbar epidural hematoma occurred post-intervention and one lumbar subarachnoid hematoma occurred pre-intervention, both in patients whose pre-procedure platelet counts were > 100 x 103/µL. No traumatic hematomas were observed in patients whose pre-procedure platelet count was < 50 x 103/µL. The incidence of traumatic taps (identified as CSF red blood cells > 10/µL) was significantly higher in patients whose pre-procedure platelet count was < 50 x 103/µL (64% vs. 46%, p <0.05).
Conclusion: Decreasing the LP platelet transfusion threshold from 50 x 103/µL to 40 x 103/µL significantly reduced platelet transfusions. This was not associated with an increased risk of complications. However, the incidence of traumatic taps was significantly higher in patients with a platelet count < 50 x 103/µL. Given that the average cost of one unit of platelets is approximately $500 and 40 procedures were performed with a platelet count < 50 x 103/µL, decreasing the platelet transfusion threshold resulted in a cost savings of approximately$20,000 over the course of 6 months, not including administrative costs. Overall, this data suggests that lowering the platelet transfusion threshold for lumbar punctures to 40 x 103/µL is both safe and cost effective for oncology patients.
Disclosures
Atallah:Abbvie: Consultancy; Jazz: Consultancy; Novartis: Consultancy; BMS: Consultancy; Pfizer: Consultancy.
## Author notes
*
Asterisk with author names denotes non-ASH members.
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https://www.edreports.org/reports/detail/core-curriculum-by-midschoolmath-2020-8
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## Alignment: Overall Summary
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for Alignment to the CCSSM. In Gateway 1, the materials meet expectations for focus and coherence, and in Gateway 2, the materials meet expectations for rigor and practice-content connections.
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## Gateway 1:
### Focus & Coherence
0
7
12
14
13
12-14
Meets Expectations
8-11
Partially Meets Expectations
0-7
Does Not Meet Expectations
## Gateway 2:
### Rigor & Mathematical Practices
0
10
16
18
18
16-18
Meets Expectations
11-15
Partially Meets Expectations
0-10
Does Not Meet Expectations
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## Gateway 3:
### Usability
0
22
31
38
25
31-38
Meets Expectations
23-30
Partially Meets Expectations
0-22
Does Not Meet Expectations
## The Report
- Collapsed Version + Full Length Version
## Focus & Coherence
#### Meets Expectations
+
-
Gateway One Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for focus and coherence. For focus, the materials assess grade-level content and spend at least 65% of class time on major work of the grade, and for coherence, the materials have supporting content that enhances focus and coherence, an amount of content designated for one grade level that is viable for one school year, and foster coherence through connections at a single grade.
### Criterion 1a
Materials do not assess topics before the grade level in which the topic should be introduced.
2/2
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Criterion Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for not assessing topics before the grade level in which the topic should be introduced. Overall, the materials assess grade-level content and, if applicable, content from earlier grades.
### Indicator 1a
The instructional material assesses the grade-level content and, if applicable, content from earlier grades. Content from future grades may be introduced but students should not be held accountable on assessments for future expectations.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for assessing grade-level content.
The materials are organized by the Domains and Clusters delineated by CCSS. Each Cluster has a Milestone Assessment, and all assessments include multiple choice and/or multiple select. The assessments are aligned to grade-level standards, and examples include:
• In Milestone Assessment 8.EE.B, Question 10 states, “What is the slope of the line represented by the equation $$8x + 2y = 16$$? a) -4;
b) 8
; c) 4
; d) -8.”
• In Milestone Assessment 8.F.A, Question 1 states, “The equation of a function is $$y = 8x - 2$$. What is the input when the output is 14? a) 110
; b) 14
; c) 1.5
; d) 2.”
• In Milestone Assessment 8.G.B, Question 9 states, “The diagonal distance between (0, 0) and another point is 15 units. What are the coordinates of the second point? a) (7, 8)
; b) (9, 12); c) (10, 5)
; d) (6, 13).”
• In Milestone Assessment 8.G.C, Question 2 states, “A cone has a radius of 8 feet and an approximate volume of 1,546 cubic feet. What is the height of the cone? Use 3.14 for pi. a) 23.08 feet; b) 23 feet; c) 23.05 feet; d) 23.5 feet.”
### Criterion 1b
Students and teachers using the materials as designed devote the large majority of class time in each grade K-8 to the major work of the grade.
4/4
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Criterion Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for devoting the majority of class time to the major work of the grade. Overall, the materials spend at least 65% of class time on major work of the grade.
### Indicator 1b
Instructional material spends the majority of class time on the major cluster of each grade.
4/4
+
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for spending a majority of instructional time on major work of the grade.
• The approximate number of days devoted to major work of the grade (including assessments and supporting work connected to the major work) is 122 out of 159, which is approximately 77%.
• The number of lessons devoted to major work of the grade (including assessments and supporting work connected to the major work) is 25 out of 31 lessons, which is approximately 81%.
• The number of weeks devoted to major work (including assessments and supporting work connected to the major work) is 30 out of 36, which is approximately 83%.
A day level analysis is most representative of the instructional materials because this represents the class time that is devoted to major work of the grade including reviews, domain intensives, and assessments. As a result, approximately 77% of the instructional materials focus on major work of the grade.
### Criterion 1c - 1f
Coherence: Each grade's instructional materials are coherent and consistent with the Standards.
7/8
+
-
Criterion Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for coherence. The materials have supporting content that enhances focus and coherence, an amount of content designated for one grade level that is viable for one school year, and foster coherence through connections at a single grade. The materials are partially consistent with the progressions in the Standards.
### Indicator 1c
Supporting content enhances focus and coherence simultaneously by engaging students in the major work of the grade.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for supporting content enhancing focus and coherence simultaneously by engaging students in the major work of the grade.
Examples of connections between supporting content and major work of the grade include:
• 8.G.B.8, Seeking Safe Harbor connects to 8.NS.A as students approximate irrational square roots when using the Pythagorean theorem to calculate the length of missing sides of triangles. In the Practice Printable, Question 1 states, “Point C is located at (4, -3) and Point D is located at (2, 5) Determine the distance between them to the nearest tenth of a unit.”
• 8.SP.A.3, The Slope of Sprouts connects to 8.F.4 as students write an equation for the line of best fit in a scatterplot and interpret the equation in terms of the situation. In the Practice Printable, Question 3 shows a scatterplot of study time and GPA. Students “write a linear equation that models the data” and answer the questions, “What does the slope mean in this context?” and “What does the y-intercept mean in this context?”
• 8.EE.A.2, Ship Shape states, “This activity connects 8.EE.A. to 8.G.C, as it directly relates three-dimentional figures, cubic units and volumes to perfect cubes and cube roots.” In the Practice Printable, an example states, “This sugar cube box is a perfect cube and its volume is 1,728 cubic centimeters. The sugar cubes inside are 1 cm X 1 cm X 1cm. a) How many sugar cubes fit along the length of the box? b) How many sugar cubes fit along the width of the box? c) How many sugar cubes fit along the height of the box? d) How much cardboard is used to make the box?”
### Indicator 1d
The amount of content designated for one grade level is viable for one school year in order to foster coherence between grades.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations that the amount of content designated for one grade level is viable for one year. The suggested amount of time and expectations for teachers and students of the materials are viable for one school year as written and would not require significant modifications. As designed, the instructional materials, with assessments, can be completed in 128-159 days.
• There are five domains which contain a total of 31 lessons. Lessons are designed to take three to four days each, leading to a total of 93-124 lesson days.
• There are 10 days for Major Cluster Intensives.
• There are 25 assessment days including 10 days for review, five spiral review days in the Distributed Practice Modules, and 10 milestone assessments.
The Scope and Sequence Chart in the Teacher Edition provides pacing information. A lesson is designed for 60 minutes.
### Indicator 1e
Materials are consistent with the progressions in the Standards i. Materials develop according to the grade-by-grade progressions in the Standards. If there is content from prior or future grades, that content is clearly identified and related to grade-level work ii. Materials give all students extensive work with grade-level problems iii. Materials relate grade level concepts explicitly to prior knowledge from earlier grades.
1/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for being consistent with the progressions in the standards.
The instructional materials clearly identify content from prior and future grade levels and use it to support the progressions of the grade-level standards. In the Detailed Lesson Plan, prerequisite standards are identified in every Lesson Plan Overview. Examples include:
• 8.EE.C.8a, Show Me the Money identifies “Prerequisite Standards 6.EE.B.5, 7.EE.B.4, 8.EE.B.6” and Cluster Connections including “Direct Connection: In Show Me the Money, students will use their knowledge of linear equations to recognize that the solution to a system of two linear equations in two variables corresponds to the point of intersection (if any) of their graphs. Cross-Cluster Connection: This activity connects 8.EE.C to HSA.REI.C as students will solve systems of equations involving both linear and nonlinear equations.”
• In 8.SP.A.1, Cholera Outbreak!, prior learning is referenced in the pro-tip from Kevin within the Instructions At a Glance section, “Describing bivariate data in a scatter plot is very similar to describing univariate data in a line plot or histogram (Grade 6 and 7).”
• In 8.EE.A.1, The Big Shrink, Instructions At a Glance, the pro-tip from Gladys suggests, ‘Consider using a base of 10 to introduce students to exponent rules, as they've been working with this base since Grade 5.”
The instructional materials do not always attend to the full intent of the grade level standards. Each lesson addresses one grade-level standard with no standards absent from the materials. Lessons are three to four days long, and all students complete the same work. However, there are limited opportunities within each lesson to practice the content of the standards. Opportunities for practice include: Math Simulator, one to four questions; Practice Printable typically has six to ten questions; Clicker Quizzes include six questions; and the teacher can assign a specific domain in Test Trainer Pro. Since all standards are given the same attention, students have limited opportunities to engage in extensive work with grade-level problems to meet the full intent of all grade-level standards. Examples where the full intent is not attended to include:
• In 8.EE.C.8a, Show Me the Money, students have limited opportunity to solve real-world and mathematical problems leading to two linear equations in two variables. In the Practice Printable, there is one problem that has context; the other problems do not include real-world contexts.
• In 8.G.C.9, The Dawn of Anesthesia, students do not have to know the formulas for the volumes of cones, cylinders, and spheres and use them to solve real-world and mathematical problems. In the Practice Printable, there is one problem that has real-world context; the other problems do not include real-world contexts.
The Test Trainer Pro and Simulation Trainer are designed to provide additional, grade-level work, but all of the items for these two features are not available for review.
• In Test Trainer Pro, primarily used as a daily warm-up, there is no way for teachers to assign specific content other than a domain of standards.
• In Simulation Trainer, the content matches the lesson, but students can provide any number as an answer, then watch the steps worked out (no words) in a solution video. They’re presented with the same question again and can put in the correct answer, then watch the same solution again. If they get it correct the first time, they also watch the solution video. The next questions are not novel, but the same situation with new numbers. If students miss one, it resets them to the beginning, no matter where they were in the assignment. It is possible that some students would never complete a Simulation Trainer.
The instructional materials relate grade-level concepts explicitly to prior knowledge from earlier grades. In the Detailed Lesson Plan for every lesson under the Lesson Plan Overview, the Cluster Connection —Cross-Cluster Connection— includes an explanation on how prior learning connects to grade-level work. Examples include:
• 8.EE.A.3, Malaria Medicine states, “This activity connects 8.EE to 5.NBT and 6.RP in that students combine their knowledge of powers of 10 with their knowledge of ratios to express one variable as a numerical factor of another variable.”
• 8.EE.A.4, The Great Discovery states, “This activity connects 8.EE.A to 6.NS.B in that students will utilize their skills with decimal operations to add, subtract, multiply, and divide numbers in scientific notation.”
• 8.NS.A.1, Warp Speed states, “This activity connects 8.NS to HSN.RN.B as students in high school will further explore properties of rational and irrational numbers.”
### Indicator 1f
Materials foster coherence through connections at a single grade, where appropriate and required by the Standards i. Materials include learning objectives that are visibly shaped by CCSSM cluster headings. ii. Materials include problems and activities that serve to connect two or more clusters in a domain, or two or more domains in a grade, in cases where these connections are natural and important.
2/2
+
-
Indicator Rating Details
The instructional materials for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for fostering coherence through connections at a single grade, where appropriate and required by the Standards.
There are no student learning targets/objectives labeled as such. However, since each lesson has a specific standard in its title that is also referenced during the lesson, these “objectives” are visibly shaped by the CCSSM cluster headings. Examples include:
• The objective of lesson 8.EE.C.8a states, “Understand that solutions to a system of two linear equations in two variables correspond to points of intersection of the graphs because points of intersection satisfy both equations simultaneously,” is shaped by 8.EE.C, “Analyze and solve linear equations and pairs of simultaneous linear equations.”
• The objective of lesson 8.G.B.6 states, “Explain a proof of the Pythagorean theorem and its converse,” is shaped by 8.G.B, “Understand and apply the Pythagorean theorem.”
• The objective for lesson 8.SP.A.1 states, “Construct and interpret scatter plots for bivariate measurement data to investigate patterns of association between two quantities. Describe patterns such as clustering, outliers, positive or negative association, linear association, and nonlinear association,” is shaped by 8.SP.A, “Investigate patterns of association in bivariate data.”
Examples of problems and activities that connect two or more clusters in a domain, or two or more domains in a grade, in cases where these connections are natural and important include:
• 8.EE.B.6, Ghost Island connects the major work of 8.EE.B to 8.F.B as students use functions to model relationships and derive linear equations in the form y=mx+b. In the Practice Printable, Question 1 states, “Determine the slope, y-intercept and equation of line n and line p.” A graphic of a coordinate plane with 2 lines is included for reference. Throughout the lesson, especially in the Teacher Instruction portion, there are also connections made to the major work of 8.G.A related to congruence and similarity, specifically similar triangles. For example, “We’ll learn more about similarity later in our geometry unit. But for now, let’s see how that helps us with slope between points on a line. In similar triangles, the ratios between corresponding sides are equal.”
• 8.F.B.5, Twin Tactics states, “This activity connects 8.F.B to 8.EE.B in that students will realize that graphs can look many different ways besides linear and can tell the story between two variables”. The Practice Printable provides students with opportunities to interpret graphs related to linear and nonlinear functions as well as one situation to sketch on a graph.
• In 8.F.A.3, Le Monsieur Chef, 8.F.A and 8.EE.B are connected as students identify linear and nonlinear equations and use the slope and y-intercept to prove linearity by completing tables, graphs, rules and interpreting the data. For example, in Practice Printable Question 3 states, “Determine if each situation can be modeled by a linear equation. If so, write the linear equation that models it. If not, write non-linear. a) On Day 0, there are 500 bacteria in a dish. The number of bacteria doubles every day after that. How many bacteria (y) are there after x days?; b) An online movie club charges a monthly fee of $8.00 and$2.00 per movie downloaded. What is the monthly cost (y) for x movies?”
• 8.G.A.5, Puppy Parallels connects the major work of 8.G.A to the major work of 8.EE.C as students write and solve equations to determine unknown angles. On the Clicker Quiz, Step 2 is as follows: “Subtract each angle from $$180\degree$$ to determine measures of exterior angles.”
## Rigor & Mathematical Practices
#### Meets Expectations
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Gateway Two Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for rigor and practice-content connections. The instructional materials meet expectations for rigor by developing conceptual understanding of key mathematical concepts, giving attention throughout the year to procedural skills, spending sufficient time working with engaging applications of mathematics, and balancing the three aspects of rigor. The materials meet expectations for practice-content connections as they: identify and use the Standards for Mathematical Practice (MPs) to enrich mathematics content; attend to the full meaning of each practice standard; provide opportunities for students to construct viable arguments and critique the reasoning of others; assist teachers in engaging students to construct viable arguments and analyze the arguments of others; and explicitly attend to the specialized language of mathematics.
### Criterion 2a - 2d
Rigor and Balance: Each grade's instructional materials reflect the balances in the Standards and help students meet the Standards' rigorous expectations, by helping students develop conceptual understanding, procedural skill and fluency, and application.
8/8
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Criterion Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for rigor. The instructional materials develop conceptual understanding of key mathematical concepts, give attention throughout the year to procedural skill and fluency, spend sufficient time working with engaging applications of mathematics, and do not always treat the three aspects of rigor together or separately.
### Indicator 2a
Attention to conceptual understanding: Materials develop conceptual understanding of key mathematical concepts, especially where called for in specific content standards or cluster headings.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for developing conceptual understanding of key mathematical concepts, especially where called for in specific standards or cluster headings.
Examples of problems and questions that develop conceptual understanding across the grade level include:
• In 8.EE.B.5, Space Race, students work together to answer, “Which ship will get to Candoran first?” “The data provided are the distometer display, which shows a distance-time equation, and the radar display which shows a distance-time graph.”
• In 8.F.A.1, Flight Functions, the Immersion Situation states, “In Flight Functions, Darla Macguire is training to become an air traffic controller. During training she states that a plane can be in two locations at once. Her trainer, Anita, stops her to explain this is impossible and asks her if she knows what a mathematical function is. Macguire states that she does know about functions, and they have a quick discussion. Anita gives her the task to determine which displays are functions before continuing her training. The data provided is an image of the ATC Radar Function Assessment.” In Data & Computation, the teacher asks students several questions, “What is a function? Is there only one output for each input? If you draw a vertical line, is there more than one y-variable for any x-value? What does it mean if there are two output values for an input?” During the Teacher Instruction several examples are provided to identify examples and nonexamples of functions.
• In 8.EE.B.6, Ghost Island, the Practice Printable includes, “Aboard the ship, Isosceles, Captain Mary Read and Sailing Master Bonny Anne are headed to find more treasure. They have departed Isla Fantasma and have set a course. They hope to arrive at Isla Pinos. It is thought to hold the hidden treasure of One-Eyed Whitebeard. Use the readings on the map to help Bonny Anne determine whether the Isosceles is on course to hit Isla Pinos.” Students are given two maps, each showing a triangle - one map is between Fantasma and the Isosceles, the other between Fantasma and Pinos.
• In 8.EE.C.8a, Show Me the Money, the Teacher Instruction includes questions to further students thinking such as, “What information are you given? Can you graph an equation of each offer? Where would you start the graph for the Madison contract? What would be the total earnings for 16 games with Madison? Where would you start the graph for the Tallahassee contract? What would be the total earnings for 16 games with Tallahassee? Do the lines intersect? Where? What can we conclude about which offer would be a better deal for Cage based on his past play record?"
Examples where students independently demonstrate conceptual understanding throughout the grade include:
• In 8.F.A.2, Happy Trails, Practice Printable, Question 2 states, “a) Draw Function D with a rate of change (slope) of and a y-intercept of 1. b) For Function E, write a linear equation with a greater rate of change (slope) than Function D and a y-intercept that is below the x-axis. c) Create a table of values that shows Function F is proportional and has a rate of change (slope) of -3.”
• In 8.F.A.3, Le Monsieur Chef, Practice Printable, Question 1d, students answer true/false questions about functions shown on a graph such as “As $$x$$ increases by 1, $$y$$ always increases by 2.”
• In 8.G.A.4, Dakota Jones and the Hall of Records, Practice Printable, Question 2 states, “A transformation is made to $$\triangle$$ABC to form $$\triangle$$DEF (not shown). Then another transformation is made to $$\triangle$$DEF to form $$\triangle$$GHJ. Describe these transformations. Then tell whether ABC and GHJ are congruent, similar, or neither. Explain why.”
• In 8.NS.A.1, Warp Speed, Practice Printable, students show that irrational numbers do not have a fractional equivalent. Students consider 10 terms in a table to determine if they are rational or irrational, then justify their answer by creating a fractional equivalent (or none). Terms include, “$$-72; \frac{25}{\sqrt{4}}; 0.414141…$$; $$\sqrt{121}$$; $$\sqrt{14}$$; -0.3333…; $$\sqrt{50}$$; 1.25; $$\frac{\pi}{2}$$; 0.68.”
### Indicator 2b
Attention to Procedural Skill and Fluency: Materials give attention throughout the year to individual standards that set an expectation of procedural skill and fluency.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for attending to those standards that set an expectation of procedural skill and fluency.
The instructional materials develop procedural skill and fluency throughout the grade level in the Math Simulator, examples in Teacher Instruction, Cluster Intensives, domain-specific Test Trainer Pro, and the Clicker Quiz. Examples include:
• In 8.EE.C.7b, Petunia’s Pickle Problem, there are five examples for the teacher to use during instruction, “Let's see another example. Solve: -3(-4p – 6) + 12 = -15 + 9(1/3p – 1). As always when solving an equation, our goal is to isolate the variable, which in this case is p. To do that, we start by simplifying both the left and the right sides of the equation. We first need to use the distributive property to get our equation in a more usable form. On the left we must remain aware of our negative values and give our terms the appropriate signs. 12p + 18 + 12 = -15 + 3p – 9. Now we can combine like terms. 12p + 30 = -24 + 3p. Finally we can use inverse operations to get our variable terms on one side and the constants on the other. 19p = -54. Now we divide both sides by 19 to find the value of p. p = -6.”
• In 8.F.B.5, Twin Tactics, Teacher Instruction, “Let’s try another example. As we read each statement, let’s sketch that part of the graph. At the start of a softball game, there were 25 people sitting on bleachers. [Plot the point (0, 25).] Inning 1, there were 45 people on the bleachers. [Plot the point (1, 45).] The number of people on the bleachers remained constant for three more innings. [Plot the point (4, 45).] 0 people left the bleachers in the 5th inning. [Plot the point (5, 35).] A family of 5 sat down during the 6th inning. [Plot the point (6, 40).] There was no movement until the 8th inning when 20 people left. [Plot the point (8, 20).] Inning 9, there was no one sitting in the bleachers. [Plot the point (9, 0).]” WIthin one problem, students have multiple opportunities to sketch segments on a graph that demonstrate the features described.
• In 8.G.B.7, The Road Less Traveled, Teacher Instruction includes engaging situations to practice the procedural steps of Pythagorean Theorem, including the shortest route, a rectangular prism, and a soccer field, “We know this is a rectangular field, so that makes the corners right angles. That means we can use the Pythagorean Theorem. The longest side of a right triangle is always opposite the right angle. We see here that 120 is opposite the right angle, so that will be side c. So we can substitute 96 for a (or b) and 120 for c, and simplify.”
Examples of students independently demonstrating procedural skills and fluencies include:
• In 8.EE.C.7b, Petunia’s Pickle Problem, Practice Printable, students solve multi-step linear equations with rational coefficients in a variety of contexts including finding the length of line segments, the measure of vertical angles, break-even points, and practice without context such as Question 4, “-4x + 15 - x = 2(6 - 2x) - x”.
• In 8.F.B.5, Twin Tactics, the Practice Printable provides 14 questions related to analyzing the functional relationship between two quantities on a graph and 11 more questions to sketch a graph that’s described, such as Question 3, ‘Ben washed dishes when he got home from school. Using the details provided, sketch a graph depicting Ben’s experience. Ben took two minutes to fill the sink to half-full. He then washed the dishes for 8 minutes. He took about 3 minutes to drain half the water out and to fill it back up to half-full with new warm water. It took him four minutes to finish washing the rest of the dishes. Then he drained the water. It took Ben 20 minutes in total from start to finish.”
• In 8.G.B.7, The Road Less Traveled, the Practice Printable provides 12 opportunities for students to use Pythagorean Theorem in a variety of situations including three-dimensional prisms, perimeter, travel routes, and straightforward practice such as Question 1, “For each triangle, find the length of the missing side.”
The instructional materials do not develop procedural skill or provide enough opportunity for students to demonstrate procedural skill with the following standard.
• In 8.EE.C.8b, Mars Rocks!, Teacher Instruction includes two examples for number of solutions, one example of solving a system by substitution, and one example of solving a system by elimination. The Practice Printable provides six problems for students to independently identify the number of solutions and four problems to solve algebraically. Due to limited instruction and practice, students do not develop procedural skill with solving systems of two linear equations in two variables algebraically and estimating solutions by graphing the equations.
### Indicator 2c
Attention to Applications: Materials are designed so that teachers and students spend sufficient time working with engaging applications of the mathematics, without losing focus on the major work of each grade
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for being designed so that teachers and students spend sufficient time working with engaging applications of mathematics. Engaging applications include single and multi-step problems, routine and non-routine problems, presented in a context in which mathematics is applied.
Examples of students engaging in routine application of skills and knowledge include:
• In 8.EE.C.8c, Training Day, Practice Printable, Question 3 states, “The Sno-Cone Casa sells snow cones during the summer months. They charge $4 per snow cone, or there is an option to join the Sno-Cone Club, which charges a one-time fee of$20 and $1.50 for each snow cone. For what number of snow cones (c) is the price (p) the same, whether or not you join the club? What is the price?” • In 8.G.B.7, Road Less Traveled, Practice Printable, Question 4 states, “How long are the poles for the teepee, assuming an extra 3 feet for the top?” Students use an image of a teepee given the diameter of the base and the height. The slant height is a variable, and students use the Pythagorean Theorem to solve. • In 8.F.B.5, Twin Tactics, Practice Printable, Question 3 states, “Ben washed dishes when he got home from school. Using the details provided, sketch a graph depicting Ben’s experience: Ben took two minutes to fill the sink to half full. He then washed the dishes for 8 minutes. He took about 3 minutes to drain half the water out and to fill it back up to half-full with new warm water. it took him four minutes to finish washing the rest of the dishes. Then he drained the water. It took Ben 20 minutes in total from start to finish.” • In 8.SP.A.1, Cholera Outbreak!, Practice Printable, Question 2 states, “A survey group conducted a study to determine if there is an association between the age of a person and the average number of emojis used per text. The survey results are below. a) Create a scatterplot on the graph, using the data in the table. b) What type of association do the two variables seem to have? c) Does there appear to be an outlier? d) Based on the data, what can you say about age and the number of emojis used per text?” Examples of students engaging in non-routine application of skills and knowledge include: • In 8.EE.A.3, Malaria Medicine, Practice Printable, the Introduction Problem states, “How many times as great should the dosage be? Before taking her human malaria studies “underground,” Doctor Sofia Martín was also attempting to cure malaria in horses. As you know, she has been conducting research using mice infected with the dreadful disease. She has determined the correct spiroindolone dose for the mice and has cured many of them. Doctor Martín believes she can use what she knows about the mice to help find the correct dosage for horses. She believes the dosage is proportional to the number of infected cells. Below, find one of her lab reports. Help her determine how many times as great the horse dose will be compared to the dose for mice.” The infected cell count is given in scientific notation. • In 8.EE.C.8b, Mars Rocks!, the last question on the Practice Printable states, "Braydon ran at a rate of 6 mph on his treadmill and then took a walk outside at a rate of 2 mph. He went a total distance of 10 miles and it took him 2 hours. How long did he run on the treadmill and how long did he walk outside?” ### Indicator 2d Balance: The three aspects of rigor are not always treated together and are not always treated separately. There is a balance of the 3 aspects of rigor within the grade. 2/2 + - Indicator Rating Details The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations that the three aspects of rigor are not always treated together and are not always treated separately. Examples of the three aspects of rigor being present independently throughout the materials include: • In 8.SP.A.3, The Slope of Sprouts, students develop conceptual understanding of linear models to solve problems in the context of bivariate measurement data. In the Practice Printable, Question 2 states, “For each problem below, an equation is given that models the linear relationship of two variables. Interpret the slope and y-intercept (if reasonable) within the context of the two variables.” Students are given data: “$$y = 19.35x - 870$$; $$x$$: Temperature ($$\degree F$$), $$y$$: Ice Cream Sales ($)” to “describe the meaning” of the slope and the y-intercept.”
• In 8.G.A.3, Tile Transformation, students use procedural skills to write the coordinate rule for each transformation: dilate, rotate, translate and reflect. In the Practice Printable, Questions 1-9, all involve identifying “what happens to (x, y) for each transformation.” Examples include: “9) Rotate quadrilateral WXYZ $$90\degree$$counterclockwise about the origin. Label the image W'X'Y'Z'; 1) Translate 3 units right, 4 units down. 8) Reflect triangle ABC over the line $$y = -1$$. Label the image A'B'C'. 3) Dilate by a scale factor of $$\frac{1}{2}$$, centered at origin.”
• In 8.G.B.8, Seeking Safe Harbor, students apply the Pythagorean Theorem to determine the distance between the take off and landing points of a helicopter shown on a map. In Practice Printable, Question 4 states, “A medical helicopter flies about 150 miles per hour. Use the map to determine approximately how long it will take the helicopter to reach the hospital from the crash site.”
Examples of multiple aspects of rigor being engaged simultaneously to develop students’ mathematical understanding of a single topic/unit of study include:
• In 8.EE.A.4, The Great Discovery, students use procedural skills and understanding of scientific notation to solve real-world problems. In the Practice Printable, Question 3 states, “A wasp is $$1.39⋅10^{-4}$$ meters long. A pygmy rabbit is $$2.4⋅10^{-1}$$ meters long. How
much longer is the pygmy rabbit than the wasp?” Question 4, “The speed of light is $$3⋅10^6$$ kilometers per second. How far does light travel in an hour?”
• In 8.EE.C.7b, Petunia’s Pickle Problem, students use procedural skills to engage in application problems. In the lesson narrative, “During Petunia’s Pickle Problem, Petunia and her mother, Rosa, make and sell pickles, at times even traveling to sell their pickles. Rosa tells Petunia that it’s important in any business to at least break even, or bring in as much money as they spent. Rosa then asks Petunia to help her figure out how many jars of pickles they must sell to break even. The data provided is Petunia’s notebook, detailing expense and income information, along with the break-even equation she has written.” The resolution video teaches the procedure which is practiced throughout the lesson. Students apply their skill to real-world problems in the Practice Printable, Question 8, “Omarion and Savannah are both saving money for their summer trip. Omarion started with $130 and puts in$10 every week. Savannah started with $55 and puts in$35 every week. a) Write and solve an equation that will determine the number of weeks (w) when Savannah and Omarion have the same amount of savings. b) At that point, how much savings will they each have?”
### Criterion 2e - 2g.iii
Practice-Content Connections: Materials meaningfully connect the Standards for Mathematical Content and the Standards for Mathematical Practice
10/10
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Criterion Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for practice-content connections. The materials: identify and use the Standards for Mathematical Practice (MPs) to enrich mathematics content; attend to the full meaning of each practice standard; provide opportunities for students to construct viable arguments and critique the reasoning of others; assist teachers in engaging students to construct viable arguments and analyze the arguments of others; and explicitly attend to the specialized language of mathematics.
### Indicator 2e
The Standards for Mathematical Practice are identified and used to enrich mathematics content within and throughout each applicable grade.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for identifying the Standards for Mathematical Practice and using them to enrich mathematics content within and throughout the grade level.
The materials reference the Mathematical Practices (MPs) throughout the Philosophy and Planning sections, and the materials indicate connections to the MPs. Examples include:
• In the Teacher’s Guide, mathematical practices are addressed in the Major Cluster Curriculum Components, Cluster Intensives, and the Teacher-Created Intensive, which is “Additional math problems developed by MidSchoolMath teachers and leading math experts such as Dan Meyer, Jo Boaler, and MathShell that emphasize the Standards for Mathematical Practice.”
• In the Teacher’s Guide, Practices & Protocols: Standards for Mathematical Practice states, “A primary goal of the MidSchoolMath curriculum structure is to ensure that it supports the Standards for Mathematical Practice, not only in “extra” activities, but embedded in the curriculum pedagogy of each component. Use of the practices can be greatly enhanced by simple instructional moves.”
• In the Teacher’s Guide, Protocols to Support Standards for Mathematical Practice includes, “To support the Standards for Mathematical Practice, MidSchoolMath has compiled a “Top 10” bank to include protocols (or instructional moves) that teachers use to structure learning experiences to deepen the understanding of the SMP. Recommended protocols for each lesson are found in the Detailed Lesson Plans with teacher instructions to implement.” The protocols are directly related to the MPs they best support.
• In the Teacher’s Guide, Detailed Lesson Plans, the Domain Review references, “A Domain Review also supports the Standards for Mathematical Practice,” and “Complete the Domain Review by reading one or more of the Standards for Mathematical Practice and ask them to reflect on their work throughout the day.”
• Each Detailed Lesson Plan, Lesson Plan Overview, includes one to three MPs and describes how the lesson connects to the MPs.
• In addition, each Detailed Lesson Plan includes a specific tip from Jo Boaler that provides guidance about how to connect the MPs with the lesson.
Examples where the MPs are connected to grade-level content include:
• In 8.EE.C.8a, Show Me the Money, Lesson Plan Overview, “MP4: Model with Mathematics. During Immersion and Data & Computation, students analyze equations formed from real-world contexts and connect them with graphical representations. From the unstructured problem, they develop a system of linear equations, and explain how this connects to the real-world context of the problem.”
• In 8.G.A.5, Puppy Parallels, Lesson Plan Overview, “MP7: Look for and make use of structure. During Immersion and Data & Computation, students recognize that the structure of two lines cut by a transversal creates many congruent angles. They analyze the structure of various diagrams and utilize prior knowledge surrounding supplementary angles. During Resolution, students see that the structure of parallel lines with a transversal lends itself to translation to see additional relationships among the angles.”
• In 8.F.A.1, Flight Functions, Lesson Plan Overview, “MP2: Reason abstractly and quantitatively. During Data & Computation, students recognize that a function is a special relationship between two variables and will distinguish between functions and non-functions. Students understand abstractly that a function is a set of input values each with exactly one output value and that it can be represented in multiple ways.”
### Indicator 2f
Materials carefully attend to the full meaning of each practice standard
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for carefully attending to the full meaning of each practice standard. Materials attend to the full meaning of each of the 8 MPs. Examples include:
• For MP1, during the Immersion situations, students make sense of a problem and look for entry points to its solution. For example, in 8.G.A.3, Tile Transformation, the Detailed Lesson Plan states, “MP1: Make sense of problems and persevere in solving them. In Immersion and Data & Computation, students will use their knowledge of transformations to identify final coordinates for a figure. They will make conjectures about which transformations will give the desired results to Miss Cartesia. Students will devise a plan which will involve a bit of experimentation and revision as they attempt to manipulate the original figure. This is a great lesson to apply Jo Boaler’s tip to consider your teacher messages in influencing student ability to make sense of problems and persevere.”
• For MP2, students make sense of quantities and their relationships in problem situations through contextualizing and decontextualizing. For example, in 8.F.A.1, Flight Functions, the Detailed Lesson Plan states, “MP2: Reason abstractly and quantitatively. During Data & Computation, students recognize that a function is a special relationship between two variables and will distinguish between functions and non-functions. Students understand abstractly that a function is a set of input values each with exactly one output value and that it can be represented in multiple ways.”
• For MP4, students put an authentic problem into their own words and use an appropriate strategy from the math they know to create a path to a solution. For example, in 8.G.C.9, Dawn of Anesthesia, the Detailed Lesson Plan states, “SMP4: Model with mathematics. In Immersion, students determine what they need to know in an unstructured problem and create strategies based on assumptions using Jo Boaler’s recommendation of formalizing a model on a poster to help clarify thinking. Because this is a difficult problem to model and because it has complex elements, such as the spherical bottle, students may initially oversimplify at this stage. In Data & Computation, students have the opportunity to improve their assumptions and model. In Resolution, teachers immediately reinforce student learning with a special modeling exercise from Dan Meyer’s Meatballs problem. Students engage in modeling to determine how many spherical meatballs fit in a cylindrical pot.”
• For MP5, students demonstrate understanding of the benefits and limitations of a variety of tools by choosing the appropriate tool for the purpose - solving problems, calculation, communication, etc. For example, in 8.G.A.4, Dakota Jones and the Hall of Records, the Detailed Lesson Plan states, “SMP5: Use appropriate tools strategically. During Data & Computation, students are instructed to consider the tools needed to come to a conclusion about the Hall of Records. The specific tools used vary from student to student, including but not limited to paper & pencil, trace paper, graph paper, rulers, chart paper, computational software, graphics editing software, presentation and animation software. Students will need various tools to show that similar figures can be created through transformations and used as models to support their claim.”
• For MP6, students attend to precision. For example, in 8.EE.C.8b, Mars Rocks!, the Detailed Lesson Plan states, “MP6: Attend to precision. In Immersion and Data & Computation, students will use their knowledge of linear equations to determine equations of the lines based on the data given. They analyze the graphical information and then use their knowledge of systems of linear equations (either graphical or algebraic) to determine whether or not the exploration vehicle and supply vehicle will meet. Teachers apply Jo Boaler’s teaching idea to reinforce how students attend to precision by presenting the complex situation and asking students: What do you notice? What do you wonder? What is going on?”
• For MP7, students look for or make use of structure while investigating and applying relationships within mathematics. For example, in 8.G.A.5, Puppy Parallels, the Detailed Lesson Plan states, “MP7: Look for and make use of structure. During Immersion and Data & Computation, students recognize that the structure of two lines cut by a transversal creates many congruent angles. They analyze the structure of various diagrams and utilize prior knowledge surrounding supplementary angles. During Resolution, students see that the structure of parallel lines with a transversal lends itself to translation to see additional relationships among the angles.” The prompts provided for teachers include: “What information do we know? Do you see anything familiar in the diagram? Do you see any straight angles? What commonalities can you see between the angles in the diagram? What ideas do you have about trying to determine the measurements of the angles in the diagram? What do you know about angles formed by two parallel lines cut by a transversal? How can we use this to find all angle measurements?”
• For MP8, students look for generalizations based on regularity in repeated reasoning or attend to the details of the process. For example, in 8.NS.A.1, Warp Speed, Detailed Lesson Plan, “MP8: Look for and express regularity in repeated reasoning. This lesson provides an opportunity for students to notice repeated calculations for general methods and shortcuts. In Data & Computation and Teacher Instruction, students look for patterns and observe how using powers of 10 can help to algebraically convert decimal expansions to their fractional equivalents, paying particular attention to how many digits are repeating in the decimal expansion.”
### Indicator 2g
Emphasis on Mathematical Reasoning: Materials support the Standards' emphasis on mathematical reasoning by:
0/0
### Indicator 2g.i
Materials prompt students to construct viable arguments and analyze the arguments of others concerning key grade-level mathematics detailed in the content standards.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for prompting students to construct viable arguments and analyze the arguments of others concerning key grade-level mathematics.
Examples of prompting students to construct viable arguments and analyze the arguments of others include:
• In 8.EE.B.5, Space Race, Practice Printable, Introduction Problem, “Which ship will get to Candoran first? Commander K-8 has three teams entering the annual race to Candoran. The teams have been practicing all week and have been keeping track of their practice data. Use the practice data to help Commander K-8 predict who will win the race. Explain your reasoning.” Data for each team is provided with a different representation: equation, table, graph. Practice Printable Question 4, “Compare the proportional relationships (given Bob’s data in a table and Liv’s data in a graph). Which of the two stores charges the least for greeting cards? Explain your reasoning.”
• In 8.EE.C.8a, Show Me the Money, Practice Printable, Introduction Problem, “How could Bailey use a graph to explain Cage’s contract offers? Football quarterback, Tom Cage and his agent, Bailey Simpson, are reviewing recent offers that have come in from two teams, the Kingsboro Kangaroos and the Hartford Hedgehogs. Cage is having difficulty understanding the equations in the contracts, so he asks Bailey to explain to him using a graph. Use the equations to graph the line for each team contract. Then explain what this means for Cage.”
• In 8.SP.A.2, Escape from Mars, Practice Printable, Introduction Problem, “What battery should she take? Team Delta Geologist Kim O’Hara is trying to make it back to Earth. She believes there is an escape pod 59 kilometers away from her base. To get there she must take the exploration vehicle. The battery can only be charged at her home base, and she’s unsure if it will last long enough to make it to the escape pod. Luckily, she found two batteries, but, sadly, she can only take one. She runs tests on both batteries and creates a scatterplot for each, showing the remaining battery life after traveling various distances. For each scatterplot, draw a line of best fit. Then decide which battery O’Hara should take and explain your reasoning.”
• In 8.G.A.2, Knee Replacement, Practice Printable, Question 1 states, “A student claims that any two shapes are congruent if one can be formed from the other by a series of rotations or reflections. Is the student correct? Explain your answer.” Question 2 states, “A transformation is made to triangle ABC to form triangle DEF (not shown). Then another transformation is made to triangle DEF to form triangle GHJ. Describe these transformations. What is the relationship between triangles ABC and GHJ? Explain your answer.” Question 3 states, “Prove that ABCD is congruent to JKLM. Describe the transformations that would be made to ABCD to form JKLM.” Question 4 states, “Are the shapes congruent? How could you use transformations to prove your answer?”
• In 8.G.A.4, Dakota Jones and the Hall of Records, Practice Printable, Question 1 states, “You are given triangle XYZ. You want to use a sequence of transformations to create another triangle that is smaller but not congruent to XYZ. Which transformation must be included in that sequence? Explain why.” Question 2 states, “A transformation is made to triangle ABC to form triangle DEF (not shown). Then another transformation is made to triangle DEF to form triangle GHJ. Describe these transformations. Then tell whether ABC and GHJ are congruent, similar, or neither. Explain why.”
• In 8.G.A.5, Puppy Parallels, Practice Printable, Question 4 states, “Are the shapes congruent? How could you use transformations to prove your answer?” Question 5 states, “Study the diagram. Tell whether each statement is true or false and explain why. Are lines j and k parallel? Explain your answer.” Question 6 states, “Are these right triangles similar? Explain your answer.”
• In 8.F.A.1, Flight Functions, Practice Printable, Question 1 states, “Determine whether each relationship represents a function and explain why or why not.” Question 3 states, “Determine whether each of the following could be a graph of a function, and explain why or why not: A line that gradually increases in a diagonal manner; A horizontal line; A circle, A vertical line.”
### Indicator 2g.ii
Materials assist teachers in engaging students in constructing viable arguments and analyzing the arguments of others concerning key grade-level mathematics detailed in the content standards.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for assisting teachers in engaging students to construct viable arguments and analyze the arguments of others concerning key grade-level mathematics.
The materials provide guidance for teachers on how to engage students with MP3. In several lessons, the Detailed Lesson Plan identifies MP3 and provides prompts that support teachers in engaging students with MP3. Examples include::
• In 8.SP.A.1, Cholera Outbreak!, teachers apply Jo Boaler’s mathematical practices tip for MP3 by asking: “How do you see this problem? How do you think about it? Instructions note to follow this by having students re-state each other’s reasoning in different ways.”
• In 8.G.1a-c, Artemis Transforms, the final step in Data and Computation has teachers pair students, present their case to each other, and justify their reasoning. Prompts include: “Is the other team’s argument logical? What evidence did they provide? What would have made their argument stronger?”
In most lessons, there are prompts for teachers that can be used for student reflection at the end of the lesson; however, these prompts are optional as the materials state “It is not always necessary for students to respond. The questions can simply be used to cue thinking prior to instruction.” Examples of these include:
• What did you do that was the same?
• What was different?
• What strategy do you think was more efficient? Why?
The materials include 10 protocols to support Mathematical Practices. Several of these protocols engage students in constructing arguments and analyzing the arguments of others. When they are included in a lesson, the materials provide directions or prompts for the teacher to support engaging students in MP3. These include:
• “I Wonder, I Notice (8-10 min): Following a completed whole-class assignment, set ground rules for peer critique, including being thoughtful, specifc [sic], and helpful (≈ 1 min). Choose a student to be “the originator” who is tasked to explain his or her approach and solution to a problem (≈ 2 min), while other students listen only. Then ask other students to ask “the originator” clarifying questions or comments that start with ‘I wonder’ and ‘I notice’ (≈ 5-6 min).”
• “Think-Pair-Share (5-6 min): Ask students to think individually about an idea and make some notes (≈1-2 min). Tell students to pair with a partner and discuss their notes (≈ 2 min). Finally, facilitate whole-class discussion by cold-calling on students to share their ideas. Consider recording ideas on a whiteboard (≈ 2 min).”
• “Lawyer Up! (12-17 min): When a task has the classroom divided between two answers or ideas, divide students into groups of four with two attorneys on each side. Tell each attorney team to prepare a defense for their “case” (≈ 4 min). Instruct students to present their argument. Each attorney is given one minute to present their view, alternating sides (≈ 4 min). Together, the attorneys must decide which case is more defendable (≈ 1 min). Tally results of each group to determine which case wins (≈ 1-2 min). Complete the protocol with a “popcorn-style” case summary (≈ 2-3 min).”
• “Math Circles (15-28 min): Prior to class, create 5 to 7 engaging questions at grade level, place on diferent [sic] table-tops. For example, Why does a circle have 360 degrees and a triangle 180 degrees? Assign groups to take turns at each table to discuss concepts (≈ 3-4 min each table).”
• “Quick Write (8-10 min): After showing an Immersion video, provide students with a unique prompt, such as: “I believe that the store owner should...”, or “The person on Mars should make the decision to...” and include the prompt, “because...” with blank space above and below. Quick writes are excellent for new concepts (≈ 8-10 min).”
• “Sketch It! (11-13 min): Tell students to draw a picture that includes both the story and math components that create a visual representation of the math concept (≈ 5-7 min). Choose two students with varying approaches to present their work (≈ 1 min each) to the class (via MidSchoolMath software platform or other method) and prepare the entire class to discuss the advantages of each model (≈ 5 min).”
### Indicator 2g.iii
Materials explicitly attend to the specialized language of mathematics.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for explicitly attending to the specialized language of mathematics.
The materials use precise and accurate terminology and definitions when describing mathematics, and the materials provide instruction in how to communicate mathematical thinking using words, diagrams, and symbols.
• Each Detailed Lesson Plan provides teachers with a list of vocabulary words and definitions that correspond to the language of the standard that is attached to the lesson; usually specific to content, but sometimes more general. For example, 8.G.2 states “Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations; given two congruent two-dimensional figures, describe a sequence that exhibits the congruence between them.” The vocabulary provided to the teacher in 8.G.A.2, Knee Replacement is, “Congruent: Equal in shape and size.”
• The vocabulary provided for the teacher is highlighted in red in the student materials on the Practice Printable.
• Each Detailed Lesson Plan prompts teachers to “Look for opportunities to clarify vocabulary” while students work on the Immersion problem which includes, “As students explain their reasoning to you and to classmates, look for opportunities to clarify their vocabulary. Allow students to ‘get their idea out’ using their own language but when possible, make clarifying statements using precise vocabulary to say the same thing. This allows students to hear the vocabulary in context, which is among the strongest methods for learning vocabulary.”
• Each Detailed Lesson Plan includes this reminder, “Vocabulary Protocols: In your math classroom, make a Word Wall to hang and refer to vocabulary words throughout the lesson. As a whole-class exercise, create a visual representation and definition once students have had time to use their new words throughout a lesson. In the Practice Printable, remind students that key vocabulary words are highlighted. Definitions are available at the upper right in their student account. In the Student Reflection, the rubric lists the key vocabulary words for the lesson. Students are required to use these vocabulary words to explain, in narrative form, the math experienced in this lesson. During “Gallery Walks,” vocabulary can be a focus of the “I Wonder..., I Notice...” protocol.”
• Each lesson includes student reflection. Students are provided with a list of vocabulary words from the lesson to help them include appropriate math vocabulary in the reflection. The rubric for the reflection includes, “I clearly described how the math is used in the story and used appropriate math vocabulary.”
• Vocabulary for students is provided in the Glossary in the student workbook. “This glossary contains terms and definitions used in MidSchoolMath Comprehensive Curriculum, including 5th to 8th grades.”
• The Teacher Instruction portion of each detailed lesson plan begins with, “Here are examples of statements you might make to the class:” which often, though not always, includes the vocabulary used in context. For example, the vocabulary provided for 8.F.A.3, Le Monsieur Chef is “Linear Function,” and “Non-linear Function.” The sample statements provided are, “Remember that a function is defined by the input value resulting in only one output value. In Le Monsieur Chef, we were asked to determine if each equation was a function and if it was linear or non-linear. The chef helped us see that linear equations can all be written in the slope-intercept form or y = mx + b, where b is the y-intercept and starting value and m is the slope and rate of change.”
## Usability
### Criterion 3a - 3e
Use and design facilitate student learning: Materials are well designed and take into account effective lesson structure and pacing.
7/8
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Criterion Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for being well designed and taking into account effective lesson structure and pacing. The materials distinguish between problems and exercises, have exercises that are given in intentional sequences, and have a variety in what students are asked to produce. The materials partially include manipulatives that are faithful representations of the mathematical objects they represent.
### Indicator 3a
The underlying design of the materials distinguishes between problems and exercises. In essence, the difference is that in solving problems, students learn new mathematics, whereas in working exercises, students apply what they have already learned to build mastery. Each problem or exercise has a purpose.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for providing both problems and exercises that have purpose.
Students engage with problems and exercises through a consistent lesson structure. Students participate in a warm-up in the Test Trainer Pro daily for 10 minutes. The Math Simulator introduces the story and the essential problem with an online video during the Immersion and Data & Computation and Resolution stages. In the Detailed Lesson Plan, the teacher instructional time (8-10 minutes) provides problems for the teacher to use as examples. The student does independent online (3-7) exercises in the Simulation Trainer, with additional repetition if they miss the problems. The Practice Printable can be used as a differentiation tool, as in-class practice, or as homework. The Clicker Quiz consists of six multiple choice questions. At the end of the lesson, there is a section for a Gallery Walk and Reflection of other student work.
### Indicator 3b
Design of assignments is not haphazard: exercises are given in intentional sequences.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for assignments being designed with an intentional sequence.
There is logic to the design because each lesson is one standard; lessons are listed in the order of the standards within each domain. In Planning the Year, the materials state, “The sequence provided in the materials is specifically designed to provide a framework to allow teachers sufficient time for teaching each standard throughout the year. Additionally, the materials are intentionally designed for students to work with more ‘concrete’ forms of mathematics prior to abstract concepts. Finally, the structure of the curriculum is sequenced to allow for completion of topics before associated summative assessments, and sequencing within lessons progresses from conceptual work to practice with exercises.”
### Indicator 3c
There is variety in what students are asked to produce. For example, students are asked to produce answers and solutions, but also, in a grade-appropriate way, arguments and explanations, diagrams, mathematical models, etc.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for requiring variety in what students produce.
Each lesson builds around an essential problem that is the entry point for the content. The problems always include “artifacts” that require students to work with content in a wide variety of ways including breaking codes, planning rations for trips, determining if things will fit, etc. In addition to the essential problem, the program utilizes 10 protocols that generate a variety of responses such as creating arguments, making up their own problems, sketching situations, quick writes, and more. The student reflection, found at the end of each lesson, gives students the opportunity to personalize and be creative in how they explain their understanding.
### Indicator 3d
Manipulatives are faithful representations of the mathematical objects they represent and when appropriate are connected to written methods.
1/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for effective use of manipulatives.
The instructional materials do not include extensive use of manipulatives, and in the online materials, tools used as manipulatives are not available. In some of the lesson material, there are visual models with number lines, graphs, or bars. Students occasionally look at models and create a math equation from the representation. Overall, there are limited opportunities to use manipulatives to develop mathematical understanding.
### Indicator 3e
The visual design (whether in print or online) is not distracting or chaotic, but supports students in engaging thoughtfully with the subject.
0/0
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 include print materials that are not distracting or chaotic. The student workbook provides space for students to write in the workbook. There are numerous videos in various parts of the lesson which are brief and engaging to students.
However, the Math Simulator can be distracting because students have to rewatch entire videos even if they have answered the questions correctly. The students do not have the ability to fast forward through the videos even though they have seen the video previously.
### Criterion 3f - 3l
Teacher Planning and Learning for Success with CCSS: Materials support teacher learning and understanding of the Standards.
4/8
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Criterion Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 do not meet expectations for supporting teacher learning and understanding of the Standards. The materials contain support for planning and providing learning experiences with quality questions and contain ample and useful notations and suggestions on how to present the content. The materials do not meet expectations for containing: adult-level explanations so that teachers can improve their own knowledge of the subject and explanations of the grade-level mathematics in the context of the overall mathematics curriculum.
### Indicator 3f
Materials support teachers in planning and providing effective learning experiences by providing quality questions to help guide students' mathematical development.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for supporting teachers with quality questions to guide mathematical development.
There are prompts for teachers embedded throughout each section of the Detailed Lesson Plan. Many of these are generic and repeated in almost every lesson, such as, “What information are we given? What operations were used? Is the math same, just represented in a different way? What visuals did you notice were similar or different?” Some questions are consistently connected to Mathematical Practices, such as, “Would this always be true? Can you think of a situation where this would not work?” In addition, each lesson introduction poses an essential question intended to guide student learning and specific prompts related to that outcome.
### Indicator 3g
Materials contain a teacher's edition with ample and useful annotations and suggestions on how to present the content in the student edition and in the ancillary materials. Where applicable, materials include teacher guidance for the use of embedded technology to support and enhance student learning.
2/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet the expectations for containing ample and useful annotations and suggestions on how to present the content in the student edition and in the ancillary materials.
In the Detailed Lesson Plan pages, there is information that can help teachers understand the materials in order to present the content. In the Teacher Instruction it states, “Lectures can be developed using guidance from the Detailed Lesson Plans.” Each lesson identifies the relevant Mathematical Practices, Cluster Connections, and Common Misconceptions. In the Instruction at a Glance section, the authors give hints to help teachers provide support to students. Also provided in each lesson is a Mathematical Practice TIp from Jo Boaler to offer ideas to instructors.
In the Detailed Lesson Plan, there is a section that provides instructions to use the online Test Trainer Pro as a daily warm up. A video is provided with each lesson which sets a scene in which the essential question is asked. The Math Simulator is a “central component of Core Curriculum MidSchoolMath, designed to provide a strong conceptual foundation of the mathematical standard.”
### Indicator 3h
Materials contain a teacher's edition (in print or clearly distinguished/accessible as a teacher's edition in digital materials) that contains full, adult-level explanations and examples of the more advanced mathematics concepts in the lessons so that teachers can improve their own knowledge of the subject, as necessary.
0/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 do not meet expectations for containing adult-level explanations so that teachers can improve their own knowledge of the subject. While the materials provide support for instruction in each lesson, they do not include adult-level explanations of the grade-level content or advanced mathematics concepts so that teachers can improve their own knowledge of the subject.
### Indicator 3i
Materials contain a teacher's edition (in print or clearly distinguished/accessible as a teacher's edition in digital materials) that explains the role of the specific grade-level mathematics in the context of the overall mathematics curriculum for kindergarten through grade twelve.
0/2
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 do not meet expectations for explaining the role of grade-level mathematics in the context of the overall mathematics curriculum.
The materials do not assist teachers in understanding the role of the specific course-level mathematics in the context of the overall series. There is no explanation of how the topic is developed in previous and future grades, other than a list of prerequisite standards for each lesson.
### Indicator 3j
Materials provide a list of lessons in the teacher's edition (in print or clearly distinguished/accessible as a teacher's edition in digital materials), cross-referencing the standards covered and providing an estimated instructional time for each lesson, chapter and unit (i.e., pacing guide).
0/0
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 provide a list of lessons in the teacher edition, cross-referencing the standards addressed, and a pacing guide.
Each course in this series includes a document called Planning the Year that provides the standards and pacing (number of weeks) for each lesson. There is additional standards correlation in the Scope and Sequence Chart that lists each Lesson, Domain Review, and Major Cluster Lessons throughout a year.
### Indicator 3k
Materials contain strategies for informing parents or caregivers about the mathematics program and suggestions for how they can help support student progress and achievement.
0/0
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 include a parent letter that explains the program in both English and Spanish. The how-to-help paragraph suggests that parents have the student log into the program and show the parents their work, “Try your best to listen and not be critique [sic]”, and to expect the math to be different. It also mentions the mindset of being bad at math and changing the mindset by saying they do not understand the concept “Yet”. There is no further communication for parents and no direct discussion of mathematical concepts.
### Indicator 3l
Materials contain explanations of the instructional approaches of the program and identification of the research-based strategies.
0/0
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Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 explain instructional approaches used and how they are research-based in the Curriculum Structure. Examples include:
• The Clicker Quiz is “a whole-class, low-stakes test (comprising [sic] of six multiple choice math problems) facilitated through any device to enhance long-term recall of concepts and provide the teacher with real-time class evaluation data. (Research Indicator: ‘The Testing Effect’ demonstrates that learning is higher through repetitive low to no-stakes testing than through studying, and that long term recall is higher.)”
• Information on Cultural Diversity in Math - “Moving from Shallow Notions of Culture to Student-Centered Mathematics Tasks” by Toya J. Frank, Ph.D. is provided online in Resources.
• In addition, Lesson Planning for Remote Situations provides overview and essential considerations in the Resources menu online for teachers, parents, and students.
### Criterion 3m - 3q
Assessment: Materials offer teachers resources and tools to collect ongoing data about student progress on the Standards.
6/10
+
-
Criterion Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for offering teachers resources and tools to collect ongoing data about student progress on the Standards. The materials include assessments that clearly denote which standards are being emphasized. The materials partially meet expectations for providing: strategies to gather information on students’ prior knowledge; strategies to identify and address common student errors and misconceptions; opportunities for ongoing review and practice with feedback; and assessments that include aligned rubrics and scoring guidance for teachers to interpret student performance and suggestions for follow-up.
### Indicator 3m
Materials provide strategies for gathering information about students' prior knowledge within and across grade levels.
1/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for gathering information about students’ prior knowledge.
• Test Trainer Pro, which is intended to be used daily, automatically gathers information about students’ prior knowledge of Core Skills (from Grades 1 through 4) and the domains within the grade-level standards.
• The Detailed Lesson Plan lists prerequisite standards for each lesson, but does not provide strategies to gather information about knowledge of those standards.
• Assessing prior knowledge is not directly addressed in the Detailed Lesson Plan, but can be elicited through teacher questioning and observation.
• The lesson plan does not include suggestions for responding to answers that demonstrate lack of prior knowledge.
• There are no pre-tests available in the materials.
### Indicator 3n
Materials provide strategies for teachers to identify and address common student errors and misconceptions.
1/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for identifying and addressing common errors and misconceptions.
The Detailed Lesson Plan includes a section of “Common Misconceptions”. In the Teacher Instruction, the teacher is usually prompted to address the misconception by showing students the correct way to do the math with some detail as to why and how. The Teacher Instruction and the Practice Printables sometimes show work with a mistake based on the misconception and ask the students to decide if the example is correct and how they know, then the students work the problem correctly.
While these address common errors and misconceptions, the materials do not mention strategies to identify the common student errors and misconceptions or why students make them.
### Indicator 3o
Materials provide opportunities for ongoing review and practice, with feedback, for students in learning both concepts and skills.
1/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for providing ongoing review and practice with feedback.
Opportunities for ongoing review include:
• The Daily Test Trainer gives students multiple-choice review questions each day.
• Distributive Practice provides two weeks of multiple-choice questions on the computer.
• Game-Based Review incorporates multiple standards.
• The Domain Review provides a short clip of four Immersion Videos from the unit. Students then complete a reflection including Story Recall, Math Concepts, and Math Connections for those four lessons. However, the majority of the materials focus on one specific standard at a time.
Opportunities for feedback include:
• Teacher prompts and questions while students work.
• The Simulation Trainer provides feedback about correct/incorrect and solution videos.
• The domain reflection includes a rubric with clear expectations.
• Students provide peer feedback during a gallery walk of student reflections.
• Formal feedback is not provided, and there is no suggested feedback for assessments related to content.
### Indicator 3p
Materials offer ongoing formative and summative assessments:
0/0
### Indicator 3p.i
Assessments clearly denote which standards are being emphasized.
2/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for denoting which standards are emphasized on assessments.
On each Milestone Assessment, the clusters are shown below the title in the digital materials and in the footer of the PDFs, and the standards are shown below the title in the digital materials.
### Indicator 3p.ii
Assessments include aligned rubrics and scoring guidelines that provide sufficient guidance to teachers for interpreting student performance and suggestions for follow-up.
1/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for interpreting student performance on assessments and making suggestions for follow-up.
The assessments are multiple-choice with an answer key in the Teacher Guide. Each Milestone Assessment has a scoring rubric that is based on the percent of correct answers. The recurring suggestion for following-up with students is for them to review and correct their mistakes. Students who score advanced (80-100%) create a tutoring session for the nearing proficient. The proficient students (60-79%) create a Top-3 Tips sheet for the class. The students who are nearing proficient (40-59%) attend the tutoring session. The novice students attend a reteaching session with the teacher.
Since the questions are all multiple choice, the teacher has a limited perspective of student abilities, and it is challenging to interpret student performance. The multiple-choice aspect of the assessments also limits the ability to measure higher-level thinking.
### Indicator 3q
Materials encourage students to monitor their own progress.
0/0
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 provide very little opportunity for students to monitor their own progress. Students self-assess their understanding of each concept during the Reflection; the Reflection rubric includes Mathematical Representation where a score of 4 (Exceeds Expectations) states, “My mathematical representation shows complete understanding of the math concept.” However, there is no overall progress monitoring completed by students.
### Criterion 3r - 3y
Differentiated instruction: Materials support teachers in differentiating instruction for diverse learners within and across grades.
8/12
+
-
Criterion Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for supporting teachers in differentiating instruction for diverse learners within and across grades. The materials embed tasks with multiple entry-points and provide a balanced portrayal of various demographic and personal characteristics. The materials partially meet expectations for providing: strategies to help teachers sequence or scaffold lessons; strategies for meeting the needs of a range of learners; supports, accommodations, and modifications for English Language Learners and other special populations; and opportunities for advanced students to investigate mathematics content at greater depth.
### Indicator 3r
Materials provide strategies to help teachers sequence or scaffold lessons so that the content is accessible to all learners.
1/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for providing strategies to help teachers make content accessible to all learners. There are some routines within the materials that help make the content accessible to all learners, but very few specific strategies to support teachers in scaffolding the lesson. For example:
• Each lesson has the same structure.
• The Immersion Video and problem provide an opportunity for students at all levels to engage in the math; however, the materials do not support the teacher with strategies to scaffold the content if students struggle.
• The Exit Ticket provides information to the teacher to determine who might join a small reteaching group, but there is limited guidance about what the teacher should do except help the students do the second side of the Practice Printable.
• The Teacher Guide describes the Top 10 Protocols and states, “For each protocol, take time to imagine the experience of all students in the classroom. For example, having one student present their work to the rest of the class could lead to only one student benefiting while most students are passively listening (or not listening at all).” Despite pointing this out, there are no strategies provided for how to scaffold the lesson to engage all students.
• The Content at a Glance in each lesson includes Pro-Tips from three teachers designed to help teachers scaffold the content such as, “Consider having students draw a visual representation of two expressions, one with no grouping symbols and one with. This will help them see how using grouping symbols can change the value of the expression.”
### Indicator 3s
Materials provide teachers with strategies for meeting the needs of a range of learners.
1/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for providing teachers with strategies for meeting the needs of a range of learners. The range of learners is addressed in a limited way, but specific strategies for meeting their needs are not provided. For example:
• The Teacher Guide provides suggestions when planning to teach, “Prep work: Review the Practice Printable Answer Key in the Detailed Lesson Plan. Decide on how you would like to use the Practice Printable (as a differentiation tool, as in-class practice, as homework, etc.). Consider choosing one problem of your choice for students to complete as an exit ticket for the period, with the option of using the results to group students for work the next day.“
• The instruction for differentiation is the same for every lesson, after students complete the first side of the Practice Printable, they answer an Exit Ticket: “Ask students to rate their personal understanding of the problem on a scale of 1 to 3: 1 = I need more help; 2 = I need more time, yet mostly understand; 3 = I’ve got this!” Based on their answer, when the students complete the second side of the Practice Printable, the teacher can assign a challenge for those who answered 3 and create a small reteach group for the students who answered 1, though there are no suggestions about what to do with the group.
• During the Simulation Trainer, it is suggested that students who complete the activity quickly can help the students who are struggling.
• The Teacher can assign a different grade level in the Test Trainer Pro.
### Indicator 3t
Materials embed tasks with multiple entry-points that can be solved using a variety of solution strategies or representations.
2/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for providing tasks with multiple entry points.
• The opening Immersion Video and problem present a task in each lesson that provides multiple entry points with no clear route to the solution.
• The Math Simulator also provides problems with multiple entry points and a variety of solution strategies, though they only show one in their solution video.
• Beyond the initial task in each of these areas, problems repeat the same situation with new numbers.
### Indicator 3u
Materials suggest support, accommodations, and modifications for English Language Learners and other special populations that will support their regular and active participation in learning mathematics (e.g., modifying vocabulary words within word problems).
1/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for including support, accommodations, and modifications for English Language Learners and other special populations that will support their regular and active participation in learning mathematics.
• The materials include support, accommodations, and modifications for ELL students through pull-out boxes in the Detailed Lesson Plans.
• There are no strategies provided for making accommodations specifically for students in special populations that would allow them to regularly and actively participate in learning grade-level mathematics.
• There is a box in each lesson called Differentiation Plan with a section for Remediation, but the suggestion is to work on problems together, with the teacher, or each other. This does not provide modifications for additional support and practice for students.
### Indicator 3v
Materials provide opportunities for advanced students to investigate mathematics content at greater depth.
1/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 partially meet expectations for providing opportunities for advanced students to investigate mathematics at greater depth.
• Materials include little, if any, deeper or more complex mathematics that would challenge advanced learners.
• There is a box in each lesson called Differentiation Plan with a section for Enrichment which suggests that students can move on to the Reflection or offers a problem that lets students apply the content. Some of these promote investigation that would enhance knowledge related to grade-level standards.
### Indicator 3w
Materials provide a balanced portrayal of various demographic and personal characteristics.
2/2
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 meet expectations for providing a variety of demographic and personal characteristics.
The actors in the videos are from different races and portray people from many ethnicities in a respectful manner. Names in the story problems include Kolson, Jalil, Misha, and Sonia. The settings span a wide range including rural, urban, international, and space.
### Indicator 3x
Materials provide opportunities for teachers to use a variety of grouping strategies.
0/0
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 provide opportunities to group students, though they are rarely delineated in the materials. The Immersion Phase allows the teacher to group students many different ways. The second side of the Practice Printable can be done as a small group. The Student Reflection has some protocols that allow for a variety of grouping strategies.
### Indicator 3y
Materials encourage teachers to draw upon home language and culture to facilitate learning.
0/0
+
-
Indicator Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 do not present opportunities for teachers to draw upon home language and culture to facilitate learning.
Effective technology use: Materials support effective use of technology to enhance student learning. Digital materials are accessible and available in multiple platforms.
0/0
+
-
Criterion Rating Details
The instructional materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 are web-based and compatible with multiple internet browsers and include opportunities for teachers to assess student learning. Although the materials are dependent on a digital platform, students use a limited range of technology within the platform. The materials are not easily customized for individual learners or local use and provide few, if any, opportunities for teachers and/or students to collaborate with each other through technology.
### Indicator 3z
Materials integrate technology such as interactive tools, virtual manipulatives/objects, and/or dynamic mathematics software in ways that engage students in the Mathematical Practices.
0/0
+
-
Indicator Rating Details
The digital materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 pose an essential question during an engaging introduction video for every lesson. Students can complete and submit the three components of the essential question (Immersion, Data & Computation, and Resolution) online, and the teacher will have a digital record of completion. These phases often incorporate the Mathematical Practices.
While the program is very technology-dependent, the students use a limited range of technology. The students do not use technology as a math tool. No virtual manipulatives were found. The digital materials include opportunities to assess students' mathematical understanding and knowledge of procedural skills through Test Trainer Pro, the Math Simulator, and the Clicker Quizzes. The Clicker Quiz offers opportunities for whole class discussions of multiple choice questions.
### Indicator 3aa
Digital materials (either included as supplementary to a textbook or as part of a digital curriculum) are web-based and compatible with multiple internet browsers (e.g., Internet Explorer, Firefox, Google Chrome, etc.). In addition, materials are "platform neutral" (i.e., are compatible with multiple operating systems such as Windows and Apple and are not proprietary to any single platform) and allow the use of tablets and mobile devices.
0/0
+
-
Indicator Rating Details
The digital materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 are web-based and compatible with multiple internet browsers. The materials are platform-neutral and compatible with Chrome, ChromeOS, Safari, and Mozilla Firefox. Materials are compatible with various devices including iPads, laptops, Chromebooks, and other devices that connect to the internet with an applicable browser.
### Indicator 3ab
Materials include opportunities to assess student mathematical understandings and knowledge of procedural skills using technology.
0/0
+
-
Indicator Rating Details
The digital materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 include opportunities for teachers to assess student learning. Examples include:
• Teachers can assign lesson problems and assessments, as well as view assessment analytics.
• The Test Trainer Pro can be assigned by the teacher by domain.
• The Domain Replay gives students a brief review of various concepts.
• The Math Simulator is designed to “provide a conceptual foundation of the mathematical standard.”
• The 6-question Clicker Quiz provides immediate feedback with the multiple choice questions.
• None of the materials allow for teachers to modify questions nor add different questions.
### Indicator 3ac
Materials can be easily customized for individual learners. i. Digital materials include opportunities for teachers to personalize learning for all students, using adaptive or other technological innovations. ii. Materials can be easily customized for local use. For example, materials may provide a range of lessons to draw from on a topic.
0/0
+
-
Indicator Rating Details
The digital materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 include Milestone assessments that are “a summative evaluation following each cluster per grade. They are automatically graded, yielding the percentage of items answered correctly. The math items are created to include items of varying difficulty.”
“Test Trainer Pro acts as a low-stakes, formative assessment for students to practice testing under more relaxed and stress-free conditions. It is an adaptive tool and is designed to elicit the largest gains in students' achievement possible in the shortest period of time.”
None of the digital materials are customizable.
The digital materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 provide one lesson for the student to complete for each standard.
Materials include or reference technology that provides opportunities for teachers and/or students to collaborate with each other (e.g. websites, discussion groups, webinars, etc.).
0/0
+
-
Indicator Rating Details
The digital materials reviewed for Core Curriculum by MidSchoolMath 5-8 Grade 8 provide few, if any, opportunities for teachers and/or students to collaborate with each other through technology.
abc123
Report Published Date: 12/29/2020
Report Edition: 2020
All publishers are invited to provide an orientation to the educator-led team that will be reviewing their materials. The review teams also can ask publishers clarifying questions about their programs throughout the review process.
Once a review is complete, publishers have the opportunity to post a 1,500-word response to the educator report and a 1,500-word document that includes any background information or research on the instructional materials.
Please note: Reports published beginning in 2021 will be using version 2 of our review tools. Learn more.
## Educator-Led Review Teams
Each report found on EdReports.org represents hundreds of hours of work by educator reviewers. Working in teams of 4-5, reviewers use educator-developed review tools, evidence guides, and key documents to thoroughly examine their sets of materials.
After receiving over 25 hours of training on the EdReports.org review tool and process, teams meet weekly over the course of several months to share evidence, come to consensus on scoring, and write the evidence that ultimately is shared on the website.
All team members look at every grade and indicator, ensuring that the entire team considers the program in full. The team lead and calibrator also meet in cross-team PLCs to ensure that the tool is being applied consistently among review teams. Final reports are the result of multiple educators analyzing every page, calibrating all findings, and reaching a unified conclusion.
## Rubric Design
The EdReports.org’s rubric supports a sequential review process through three gateways. These gateways reflect the importance of standards alignment to the fundamental design elements of the materials and considers other attributes of high-quality curriculum as recommended by educators.
• Materials must meet or partially meet expectations for the first set of indicators to move along the process. Gateways 1 and 2 focus on questions of alignment. Are the instructional materials aligned to the standards? Are all standards present and treated with appropriate depth and quality required to support student learning?
• Gateway 3 focuses on the question of usability. Are the instructional materials user-friendly for students and educators? Materials must be well designed to facilitate student learning and enhance a teacher’s ability to differentiate and build knowledge within the classroom. In order to be reviewed and attain a rating for usability (Gateway 3), the instructional materials must first meet expectations for alignment (Gateways 1 and 2).
## Key Terms Used throughout Review Rubric and Reports
• Indicator Specific item that reviewers look for in materials.
• Criterion Combination of all of the individual indicators for a single focus area.
• Gateway Organizing feature of the evaluation rubric that combines criteria and prioritizes order for sequential review.
• Alignment Rating Degree to which materials meet expectations for alignment, including that all standards are present and treated with the appropriate depth to support students in learning the skills and knowledge that they need to be ready for college and career.
• Usability Degree to which materials are consistent with effective practices for use and design, teacher planning and learning, assessment, and differentiated instruction.
## Math K-8 Rubric and Evidence Guides
The K-8 review rubric identifies the criteria and indicators for high quality instructional materials. The rubric supports a sequential review process that reflect the importance of alignment to the standards then consider other high-quality attributes of curriculum as recommended by educators.
For math, our rubrics evaluate materials based on:
• Focus and Coherence
• Rigor and Mathematical Practices
• Instructional Supports and Usability
The K-8 Evidence Guides complement the rubric by elaborating details for each indicator including the purpose of the indicator, information on how to collect evidence, guiding questions and discussion prompts, and scoring criteria.
The EdReports rubric supports a sequential review process through three gateways. These gateways reflect the importance of alignment to college and career ready standards and considers other attributes of high-quality curriculum, such as usability and design, as recommended by educators.
Materials must meet or partially meet expectations for the first set of indicators (gateway 1) to move to the other gateways.
Gateways 1 and 2 focus on questions of alignment to the standards. Are the instructional materials aligned to the standards? Are all standards present and treated with appropriate depth and quality required to support student learning?
Gateway 3 focuses on the question of usability. Are the instructional materials user-friendly for students and educators? Materials must be well designed to facilitate student learning and enhance a teacher’s ability to differentiate and build knowledge within the classroom.
In order to be reviewed and attain a rating for usability (Gateway 3), the instructional materials must first meet expectations for alignment (Gateways 1 and 2).
Alignment and usability ratings are assigned based on how materials score on a series of criteria and indicators with reviewers providing supporting evidence to determine and substantiate each point awarded.
For ELA and math, alignment ratings represent the degree to which materials meet expectations, partially meet expectations, or do not meet expectations for alignment to college- and career-ready standards, including that all standards are present and treated with the appropriate depth to support students in learning the skills and knowledge that they need to be ready for college and career.
For science, alignment ratings represent the degree to which materials meet expectations, partially meet expectations, or do not meet expectations for alignment to the Next Generation Science Standards, including that all standards are present and treated with the appropriate depth to support students in learning the skills and knowledge that they need to be ready for college and career.
For all content areas, usability ratings represent the degree to which materials meet expectations, partially meet expectations, or do not meet expectations for effective practices (as outlined in the evaluation tool) for use and design, teacher planning and learning, assessment, differentiated instruction, and effective technology use.
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|
https://www.physicsforums.com/threads/momentum-after-inelastic-collison.843861/
|
# Momentum After Inelastic Collison
Tags:
1. Nov 18, 2015
### NatalieWise123
1. The problem statement, all variables and given/known data
Two hockey pucks are sliding across the ice in the same direction. One has a momentum of 35 kg*m/s. The other has a momentum of 7 kg*m/s. After the collision, the pucks stick together. What is the momentum of the pucks after the collision?
2. Relevant equations
3. The attempt at a solution
I'd think you'd just add them together because of the Law of Conservation of Momentum but for some reason I'd imagine they'd slow down after hitting. Is 42 kg*m/s the right answer and if so why?
2. Nov 18, 2015
### J Hann
Even though energy is not conserved in an in an inelastic collision,
momentum is conserved.
So write an equation for conservation of momentum and solve for the final speed.
Remember, you now have a final mass of 2 m.
Draft saved Draft deleted
Similar Discussions: Momentum After Inelastic Collison
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https://solvedlib.com/people-like-to-buy-frozen-entrees-such-as-lasagna,133998
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1 answer
# People like to buy frozen entrees such as lasagna but they also want to watch their...
###### Question:
people like to buy frozen entrees such as lasagna but they also want to watch their fat intake. Describe how they should examine food labels make an informed decision. for any two similar items to compare the fat content and to
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##### 5. Describe the appearance of P. jiroveci in a tracheobronchial aspirate when the Giemsa stain is...
5. Describe the appearance of P. jiroveci in a tracheobronchial aspirate when the Giemsa stain is used to stain the material which is dried and fixed with methanol. 6. Which human herpes virus is responsible for (associated with) the following diseases: a. Infectious mononucleosis b. Cold sores c. G...
4 answers
##### 125 children are shown three television commercials for breakfast cereal and asked to pick which commercial they liked best. The results are shown in the following table: Commercial A Commercial B Commercial € Boys 30 16 Girls 12 33 Researchers want to know if the choice of favorite commercial was related to whether the child was a boy girl c or if these two variables are independentUse the chi-square test to answer this question with 95% confidence;Test statistic 9.097, critical value 0.10. R
125 children are shown three television commercials for breakfast cereal and asked to pick which commercial they liked best. The results are shown in the following table: Commercial A Commercial B Commercial € Boys 30 16 Girls 12 33 Researchers want to know if the choice of favorite commercial...
1 answer
##### Create a new program in Mu and save it as ps3.2.2.py and take the code below...
Create a new program in Mu and save it as ps3.2.2.py and take the code below and fix it as indicated in the comments: egg = True milk = True butter = True flour = True You may modify the lines of code above, but don't move them! When you Submit your code, we'll change these lines to a...
1 answer
##### Please help me determine my unknown my empirical and molecular formula is C8H10O my melting point...
please help me determine my unknown my empirical and molecular formula is C8H10O my melting point is 61-69 degrees C i need -peaks labeled (base and ion peaks) -drawn structure also need one fragment ion peak identified functional groups identified THANKS! ill venmo you literally HELP 53 ...
5 answers
##### Sprint6:55 PM WebWork57%WW4: Problem 3PreviousProblem ListNextpoint) Convert the integral below t0 polar coordinates and evaluate the integral: Vv? Vi6-;" xy dxdyInstructions: Please enter the integrand in the first answer box; typing theta for 0. Depending on the order of integration you choose, enter dr and atheta in either order into the second and third answer boxes with only one dr or dtheta in each box: Then_ enter the limits of integration and evaluate the integral to find the volume
Sprint 6:55 PM WebWork 57% WW4: Problem 3 Previous Problem List Next point) Convert the integral below t0 polar coordinates and evaluate the integral: Vv? Vi6-;" xy dxdy Instructions: Please enter the integrand in the first answer box; typing theta for 0. Depending on the order of integration y...
5 answers
##### Suppose that we regress the binary variable,on the binary variable,by ordinary least = squares (OLS) and obtain U, = 0.4944 + 0.0517F,whereU; =1if individualwent to university (0 otherwise) andF =for females (0 for males): If the sample size used for estimation was " = 890with SO% of the sample being women and 50% men, calculate (to 2 decimal places) an appropriate test statistic for testing whether the proportions of men and women going to university differed
Suppose that we regress the binary variable, on the binary variable, by ordinary least = squares (OLS) and obtain U, = 0.4944 + 0.0517F, where U; =1 if individual went to university (0 otherwise) and F = for females (0 for males): If the sample size used for estimation was " = 890 with SO% of t...
1 answer
##### A) “The reason that a high beta stock has a greater expected return than a low...
a) “The reason that a high beta stock has a greater expected return than a low beta stock is because the high beta stock must have more volatile returns than the low beta stock." Using the CAPM, critically evaluate this statement and demonstrate the links between betas and stock return var...
1 answer
E+10;25 00 0$| homework2 Homneiyon Mac aofeAnieaen kl4ir 4 Me Mue Jua'a:|ili :183u UIt A W1hu-L... 1 answer ##### In a project for which a section of the mass haul diagram is shown in the lower figure, the free haul distance is specified as 100 m. Calculate the cost of earh moving in the sectice betwe... In a project for which a section of the mass haul diagram is shown in the lower figure, the free haul distance is specified as 100 m. Calculate the cost of earh moving in the sectice between chainages 100 m and 400 m if the charge for moving material within the free haul distance is 5 JD per m3 and ... 1 answer ##### Column A A. Domain B. Nursing Theory C. Florence Nightingale D. Empirical knowing E. Metaparadigm F.... Column A A. Domain B. Nursing Theory C. Florence Nightingale D. Empirical knowing E. Metaparadigm F. Wiedenbach G. Hall H. Henderson Column B 1. It is solely a nursing function in Hall's model 2. She has 14 components of basic nursing care 3. It guides nursing practice 4. Boundaries or focus of ... 5 answers ##### Assuma Ihat LIda utyandm n /Prove Ihal (m-nji Fmi Proot Inducton on | Lot Pin) ce "for P(1) inua since (m-IJposve integers(m-nlnAssuma that PIk)(m-(k+ 1))I - ((m-K)+1) (0+k)1=m1 kI +1Dy [I m1 + (K+1)I, arid Ihus Pik-I) Tnua by PMI P(n) Inue (or a pos vo integersby [(I)]Provo thal (mn)1 (mil(nt} Prool: By induction cn n Let Pln) be "for - 0o sirive inlegers (mni) (m1) (n1)" P(T)E true since (mij (milt by [lv)] by [(vi)] Assume that Prk) (rn(k-T)t (mk+m)i (mk)i (m1).(kt) [(wi)l by [ Assuma Ihat L Ida uty andm n / Prove Ihal (m-nji Fmi Proot Inducton on | Lot Pin) ce "for P(1) inua since (m-IJ posve integers (m-nln Assuma that PIk) (m-(k+ 1))I - ((m-K)+1) (0+k)1 =m1 kI +1 Dy [I m1 + (K+1)I, arid Ihus Pik-I) Tnua by PMI P(n) Inue (or a pos vo integers by [(I)] Provo thal (mn... 5 answers ##### Test the claim about the population mean, L, at the given level of significance using the given sample Statistics.Claim: / 6000 a=0.02; & = 359. Sample statistics: % = 6200,n=40Identify the null and alternative hypotheses Choose the correct answer below0 A. Ho: p=6000 Ha: 46000 Ho: 46000 Ha: /<6000 0 E: Ho: /=6000 Ha: p= 6000Ho: p<6000 Ha: 46000 D. Ho: 426000 Ha" 46000 0 F Ho: p=6000 Ha: 426000Calculate the standardized test statisticThe standardized test statistic is Round t Test the claim about the population mean, L, at the given level of significance using the given sample Statistics. Claim: / 6000 a=0.02; & = 359. Sample statistics: % = 6200,n=40 Identify the null and alternative hypotheses Choose the correct answer below 0 A. Ho: p=6000 Ha: 46000 Ho: 4#6000 H... 5 answers ##### Differentiate_f(x) -x" In 3x Differentiate_ f(x) -x" In 3x... 1 answer ##### Given Var(X) = 4, Var(Y) = 1, and Var(X+2Y) = 10, What is Var(2X-Y-3)? I know... Given Var(X) = 4, Var(Y) = 1, and Var(X+2Y) = 10, What is Var(2X-Y-3)? I know the answer is 15, I'm particularly interested in the specific steps involved with finding the cov(X,Y) in this problem. Please explain in detail, step by step how you come to cov(X,Y) = 0.5 in this equation. Please inc... 5 answers ##### Turn Ainto Reduced Row Echelon Form (RREF) and determine its rank: Turn A into Reduced Row Echelon Form (RREF) and determine its rank:... 1 answer ##### 40. Use the Binomial Theorem to find the 3rd coefficient in the expansion of (x –... 40. Use the Binomial Theorem to find the 3rd coefficient in the expansion of (x – 3)?.... 5 answers ##### 2 ? E ! 1 (0) What ts Ue 0 2 cuneitino 12 > Mia 9.1.016. 1 LualMlantnntumi Tvs 1 oltnis particies; 1 1W 1 thchverriou; erethe auche simpler cucuidte 1 li Calcul H '3104476 1 H 1 clelk YJur TevrDY ccing tc con jiicelco dltnos C_atona 1 subtrcting = Ananycu velocity L L frorn tne particle'$ actubi
2 ? E ! 1 (0) What ts Ue 0 2 cuneitino 12 > Mia 9.1.016. 1 LualMlantnntumi Tvs 1 oltnis particies; 1 1 W 1 thchverriou; erethe auche simpler cucuidte 1 li Calcul H '3104476 1 H 1 clelk YJur TevrDY ccing tc con jiicelco dltnos C_atona 1 subtrcting = Ananycu velocity L L frorn tne particle&...
5 answers
##### Calculate Ms for f(z) = 3 . In(z?) over [1,2].Ms
Calculate Ms for f(z) = 3 . In(z?) over [1,2]. Ms...
5 answers
##### A gas fills a volume of 2.3L at 25 degrees celsius. What volume does it will at 50 degrees celsius? A.4.6 L B. 1.2 LC. 2.5 LD 2.1 L
a gas fills a volume of 2.3L at 25 degrees celsius. What volume does it will at 50 degrees celsius? A.4.6 L B. 1.2 LC. 2.5 LD 2.1 L...
1 answer
##### Q 14.20: Which of the following molecular formulas has no degrees of unsaturation (hydrogen deficiency index...
Q 14.20: Which of the following molecular formulas has no degrees of unsaturation (hydrogen deficiency index = 0)? A CHIO 6 Coho © CGHIA D All of the above. E None of the above....
5 answers
##### An apple farm yields an average of 43 bushels of apples per tree when 25 trees are planted on an acre of ground. Each time more tree is planted per acre, the yield decreases by bushel (bu) per tree as a result of crowding: How many trees should be planted on an acre in order to get the highest yield?In order to get the highest yield,trees should be planted on an acre_
An apple farm yields an average of 43 bushels of apples per tree when 25 trees are planted on an acre of ground. Each time more tree is planted per acre, the yield decreases by bushel (bu) per tree as a result of crowding: How many trees should be planted on an acre in order to get the highest yield...
1 answer
Paintbrush Hills State Bank has just submitted its Report of Condition and Report of Income to its supervisory agency. The bank reported net income before taxes of $29 million and taxes of$8 million. If total revenue was $650 million, total assets$1750 million, and equity capital $170 million, cal... 1 answer ##### 1. A, on a coordinate axis (1)sketch x? + (y – 5)2 = 9, (2)describe the... 1. A, on a coordinate axis (1)sketch x? + (y – 5)2 = 9, (2)describe the graph, (3)the graph is revolved about the x-axis, set-up integral which will compute its VOLUME, simplify the integrand as much as possible but DO NOT DO THE INTEGRATION. B. The triangle whose vertices are (0,0), (2,8) and... 1 answer ##### Question 18 (5 points) Suppose Boyson Inc.'s free cash flow for next year is FCF1=$150,000, and...
Question 18 (5 points) Suppose Boyson Inc.'s free cash flow for next year is FCF1=$150,000, and FCF is expected to grow at a constant rate of 6.5%. If WACC is 12.5%, what is market value (MV) of the firm? A)$2,605,000 B) $2,425,000 C)$2,592,125 D) $2,500,000 E)$2,425,000...
5 answers
##### Point) Evaluate the integral below: Use capital letter C to denote an arbitrary constant:cos(Sx) dx =
point) Evaluate the integral below: Use capital letter C to denote an arbitrary constant: cos(Sx) dx =...
1 answer
##### What is the observed variation in volors and what is the realtionship between these colors and...
What is the observed variation in volors and what is the realtionship between these colors and the electtonic structure of the material? GO FIGURE As the size of the quantum dots decreases, does the wavelength of the emitted light increase or decrease? Size of CdSe quantum dots 2 nm →7 nm 2...
5 answers
1 answer
##### Question 2 of 4 Step 1 of 5 00:55:26 An engineer designed a valve that will...
Question 2 of 4 Step 1 of 5 00:55:26 An engineer designed a valve that will regulate water pressure on an automobile engine. The engineer designed the valve such that it would produce a mean pressure of 4.2 pounds/square inch. The valve was tested on 270 engines and the mean pressure was 43 pounds/s...
-- 0.025454--
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https://www.acmicpc.net/problem/7310
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시간 제한 메모리 제한 제출 정답 맞은 사람 정답 비율
1 초 128 MB 0 0 0 0.000%
## 문제
One cumbersome problem in chemistry is the task of making the number of atoms balanced in a chemical equation. Our problem is concerned with this.
Chemists obey these rules when they present chemical equations:
1. Each element name is abbreviated by at most two letters. The first letter is always in upper-case and the second letter if exists, is a lower-case letter (e.g. Calcium is represented by Ca, Oxygen by O, and Chlorine by Cl).
2. Each molecule is composed of a number of atoms. To represent a molecule, we concatenate the abbreviated names of its composite atoms. For example, NaCl represents Sodium Chloride. Each atom name may be followed by a frequency number. For example, Calcium Chloride CaCl2 consists of one atom of Calcium and two atoms of Chlorine. If the frequency is not given, it is assumed to be 1 (so HCl is equivalent to H1Cl1). For the sake of simplicity, you may assume that the frequency of an occurrence of an atom is at most 9 (so we do not have C11H22O11 in the problem input). Note that there may be several occurrences of the same atom in the molecule formula, like H atom in CH3COOH.
3. In ordinary chemical reactions, a number of molecules combine and result in a number of other molecules. For example a well known sample of neutralization is:
2HCl + CaO2H2 -> CaCl2 + 2H2O
This means two molecules of chlorohydric acid (HCl) with one molecule of Calcium Hydroxide results in one molecule of Calcium Chloride (CaCl2) and two molecules of water.
4. In every chemical reaction, the total number of each atom in the right side of the equation equals the total number of that atom in the left side (that is why it is called an equation!).
Your task is to write a program to find appropriate coefficients x1, x2,..., xM and y1, y2,..., yN to balance an (imbalanced) equation like
A1 + A2 + A3 + ... + AM -> B1 + B2 + B3 + ... + BN
in the following way:
x1A1 + x2A2 + x3A3 + ... + xMAM -> y1B1 + y2B2 + y3B3 + ... + yNBN
## 입력
The first line contains an integer t ( 1 ≤ t ≤ 10), the number of test cases. Each test case consists of a single line containing an expression like:
A1 + A2 + A3 + ... + AM = B1 + B2 + B3 + ... + BN
Each Ai or Bi is a formula of a molecule according to the rules given in items 1 and 2.
The input equations are given in a way that if they can be balanced, xi and yi coefficients can be in the range of 1 to 9. There are less than 10 molecules and there are less than 10 different types of atoms, in a given equation. Additionally, you may assume molecules contain no more than 3 different kinds of atoms. You may also assume that there is no blank character in the input file, and the maximum length of the input lines is 200 characters.
## 출력
The output will be one line per test case containing the list of required coefficients, separated by blank characters, in the following order:
x1 x2 ... xM y1 y2 ... yN
The coefficients should be integers in the range of 1..9. Obviously, there may be more than one answer for a test case. In such situations, print the answer which minimizes the number:
x1x2...xMy1y2...yN
(This is an (M + N)-digit decimal number whose digits are xi and yi coefficients.) If the equation is impossible to balance, the output line should be IMPOSSIBLE'.
## 예제 입력
3
HCl+CaO2H2=CaCl2+H2O
HCl+H2SO4=NaCl
HCl+NaOH=NaCl+H2O
## 예제 출력
2 1 1 2
IMPOSSIBLE
1 1 1 1
`
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http://www.mathematicalgemstones.com/gemstones/pearl/deriving-the-discriminant-of-a-cubic-polynomial-through-analytic-geometric-means/
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# Deriving the discriminant of a cubic polynomial through analytic geometric means
This is a contributed gemstone, written by Sushant Vijayan. Enjoy!
Consider a generic cubic equation $$at^3+bt^2+ct+d=0,$$ where $a,b,c,d$ are real numbers and $a \neq 0$. Now we can transform this equation into a depressed cubic equation, i.e., one with no $t^2$ term, through means of Tschirnhaus Transformation $t=x-\frac{b}{3a}$, followed by dividing through by $a$. The depressed cubic equation is given by $$x^3+px+q=0$$ where $p$ and $q$ are related to $a,b,c,d$ by the relation given here. Setting $p=-m$ and $q=-n$ and rearranging we arrive at $$x^3 =mx+n \hspace{3cm} (1)$$ We will investigate the nature of roots for this equation. We begin with plotting out the graph of $y=x^3$:
It is an odd, monotonic, nondecreasing function with an inflection point at $x=0$. The real roots of the equation (1) are the $x$-coordinates of the points of intersection between the straight line $y= mx+n$ and the curve $y=x^3$. It is clear geometrically that however we draw the straight line, as a bare minimum, there would be at least one point of intersection. This corresponds to the fact that all cubic equations with real coefficients have at least one real root.
It is immediately clear that if the slope of the line $m$ is less than $0$, there is only one point of intersection and hence only one real root. On the other hand, the condition $m>0$ is equivalent to demanding that the depressed cubic $y(x)= x^3-mx-n$ has two points of local extrema (which is a necessary, but not sufficient, condition for the existence of three real roots).
Now the possibility of repeated real roots occur when the straight line is a tangent to the curve $y=x^3$. Hence consider the slope of the function $y=x^3$:
$$\frac{dy}{dx}=3x^2$$ Now equating the slopes (note $m\ge 0$) we get the tangent points:
$$3x^2=m$$
$$x=\pm \sqrt{\frac {m}{3} }$$
Equivalently, the tangents are at the two values of $x$ for which
$$|x|=\sqrt{\frac {m}{3} }.$$
The corresponding $y$-intercepts for these tangent straight lines are:
$$n=\pm \frac{2m}{3}\sqrt{\frac{m}{3}}$$
or, in other words,
$$|n|=\frac{2m}{3}\sqrt{\frac{m}{3}}$$
Thus for a straight line with a given slope $m\ge 0$ there are only two tangents with corresponding tangent points and $y$-intercepts. This would be the case of equation (1) having one real and one real repeated root.
What about the case where the slope is still $m$ but $|n|<\frac{2m}{3}\sqrt{\frac{m}{3}}$?
In this case the straight line is parallel to the two tangent lines (since same slope) and in the region bounded by the two tangent lines. Hence it would necessarily intersect the curve $y=x^3$ at three points. This corresponds to the situation of equation (1) having three real roots.
And the case where $|n| > \frac{2m}{3}\sqrt{\frac{m}{3}}$ corresponds to the area outside the bounded region of the two tangent lines and has only one point of intersection.
Hence the necessary and sufficient condition for three real roots (including repeated roots) is given by:
$$|n| \le \frac{2m}{3}\sqrt{\frac{m}{3}} \hspace{3cm}(2)$$
We note that the condition $m\ge 0$ is subsumed within the above condition (2), for If $m<0$ then the condition (2) cannot be satisfied. We note that condition (2) is not a radical expression. We square on both sides and rearrange to arrive at: $$\frac{4m^3}{27}-n^2 \ge 0$$ Multiply by 27 and set $\bigtriangleup=4m^3-27n^2$ to get $$\bigtriangleup \ge 0$$ The $\bigtriangleup$ is the discriminant of the cubic and has all the information required to determine the nature of the roots of the depressed cubic given by equation (1). This may then be written in terms of $a,b,c,d$ by inverting the Tschirnhaus transformation. A similar exercise may be carried out for the quartic equation, and a similar but albeit more complicated expression can be derived for the discriminant. It would be very interesting to do the same exercise for the quintic and see where it fails (fail it must, otherwise it would contradict Abel's famous result of insolvability of quintic equations using radical expressions).
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http://board.flatassembler.net/topic.php?p=199773
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flat assembler
Message board for the users of flat assembler.
Index > Feedback > Math on board
Author
Tomasz Grysztar
Assembly Artist
Joined: 16 Jun 2003
Posts: 7626
Location: Kraków, Poland
Tomasz Grysztar
I have experimentally enabled support for [tex] tags with LaTeX syntax on the forums. I'm going to leave it on unless it causes any problems. If you would like it to stay, please do not abuse it.
08 Sep 2017, 18:43
YONG
Joined: 16 Mar 2005
Posts: 8000
Location: 22° 15' N | 114° 10' E
YONG
Define:
and
and
Given that:
and
Is it possible to have ?
If yes, give an example; if no, explain why not.
09 Sep 2017, 05:05
tthsqe
Joined: 20 May 2009
Posts: 721
tthsqe
Yong, this is trivially easy if you let the even-indexed be zero and the odd-indexed be the term of your favourite divergent series, and vice-versa for the .
I think as long as furs and systemerror dont find out about them, the tex tags will not be abused. Thanks again Thomasz.[/code]
09 Sep 2017, 08:25
YONG
Joined: 16 Mar 2005
Posts: 8000
Location: 22° 15' N | 114° 10' E
YONG
tthsqe wrote:
Yong, this is trivially easy if you let the even-indexed be zero and the odd-indexed be the term of your favourite divergent series, and vice-versa for the .
Wow, you are super-smart!
BTW, it is "YONG", not "Yong".
09 Sep 2017, 09:48
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http://math.stackexchange.com/questions/202013/please-check-working-given-rsa-encoding-function-e-x-to-x11-pmod3737
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# (Please check working) Given RSA encoding function $E: x\to x^{11} \pmod{3737}$ find the decoding function $D$
Question:
Given RSA encoding function $E: x\to x^{11} \pmod{3737}$ find the decoding function $D$
My working:
$\phi(3737) = \phi(37) \times \phi(101)$
$= 36 \times 100 = 3600$
Using euclid's algorithm (Skipping the fairly long gory details) we show:
$1 = 4\times3600 - 1309 \times 11$
Taking the coefficient of 11 (power of $x$), we get $-1309$ but we want this in positive congruent mod $3600$ so $3600-1309 = 2291$ and finally we have
$D:x\to x^{2291}\pmod{3737}$
-
Seems fine. Note that once you have (maybe) found the decoding number, you can check it easily: We have $(11)(2291)=25201$, which is easily congruent to $1$ modulo $3600$. – André Nicolas Sep 25 '12 at 5:11
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http://link.springer.com/article/10.1023%2FA%3A1017569601150
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Journal of Philosophical Logic
, Volume 30, Issue 3, pp 259–265
# No Future
• Leon Horsten
• Hannes Leitgeb
Article
DOI: 10.1023/A:1017569601150
Cite this article as:
Horsten, L. & Leitgeb, H. Journal of Philosophical Logic (2001) 30: 259. doi:10.1023/A:1017569601150
## Abstract
The difficulties with formalizing the intensional notions necessity, knowability and omniscience, and rational belief are well-known. If these notions are formalized as predicates applying to (codes of) sentences, then from apparently weak and uncontroversial logical principles governing these notions, outright contradictions can be derived. Tense logic is one of the best understood and most extensively developed branches of intensional logic. In tense logic, the temporal notions future and past are formalized as sentential operators rather than as predicates. The question therefore arises whether the notions that are investigated in tense logic can be consistently formalized as predicates. In this paper it is shown that the answer to this question is negative. The logical treatment of the notions of future and past as predicates gives rise to paradoxes due the specific interplay between both notions. For this reason, the tense paradoxes that will be presented are not identical to the paradoxes referred to above.
tense logictense predicatesdiagonalizationparadox
## Copyright information
© Kluwer Academic Publishers 2001
## Authors and Affiliations
• Leon Horsten
• 1
• Hannes Leitgeb
• 2
1. 1.Centrum LogicaLeuvenBelgium
2. 2.Dept. of PhilosophyUniversity of Salzburg FranziskanergasseSalzburgAustria
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http://en.wikipedia.org/wiki/Point_elasticity
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# Elasticity of a function
(Redirected from Point elasticity)
In mathematics, the elasticity or point elasticity of a positive differentiable function f of a positive variable (positive input, positive output)[1] at point a is defined as[2]
$Ef(a) = \frac{a}{f(a)}f'(a)$
$=\lim_{x\to a}\frac{f(x)-f(a)}{x-a}\frac{a}{f(a)}=\lim_{x\to a}\frac{f(x)-f(a)}{f(a)}\frac{a}{x-a}=\lim_{x\to a}\frac{1- \frac{f(x)}{f(a)}}{1-\frac{x}{a}}\approx \frac{\%\Delta f(a)}{\%\Delta a}$
or equivalently
$Ef(x) = \frac{d \log f(x)}{d \log x}.$
It is thus the ratio of the relative (percentage) change in the function's output $f(x)$ with respect to the relative change in its input $x$, for infinitesimal changes from a point $(a, f(a))$. Equivalently, it is the ratio of the infinitesimal change of the logarithm of a function with respect to the infinitesimal change of the logarithm of the argument.
The elasticity of a function is a constant $\alpha$ if and only if the function has the form $f(x) = C x ^ \alpha$ for a constant $C>0$.
The elasticity at a point is the limit of the arc elasticity between two points as the separation between those two points approaches zero.
The concept of elasticity is widely used in economics; see elasticity (economics) for details.
## Rules
Rules for finding the elasticity of products and quotients are simpler than those for derivatives. Let f, g be differentiable. Then[2]
$E ( f(x) \cdot g(x) ) = E f(x) + E g(x)$
$E \frac{f(x)}{g(x)} = E f(x) - E g(x)$
$E ( f(x) + g(x) ) = \frac{f(x) \cdot E(f(x)) + g(x) \cdot E(g(x))}{f(x) + g(x)}$
$E ( f(x) - g(x) ) = \frac{f(x) \cdot E(f(x)) - g(x) \cdot E(g(x))}{f(x) - g(x)}$
The derivative can be expressed in terms of elasticity as
$D f(x) = \frac{E f(x) \cdot f(x)}{x}$
Let a and b be constants. Then
$E ( a ) = 0 \$
$E ( a \cdot f(x) ) = E f(x)$,
$E (b x^a) = a \$.
## Estimating point elasticities
In economics, the price elasticity of demand refers to the elasticity of a demand function Q(P), and can be expressed as (dQ/dP)/(Q(P)/P) or the ratio of the value of the marginal function (dQ/dP) to the value of the average function (Q(P)/P). This relationship provides an easy way of determining whether a demand curve is elastic or inelastic at a particular point. First, suppose one follows the usual convention in mathematics of plotting the independent variable (P) horizontally and the dependent variable (Q) vertically. Then the slope of a line tangent to the curve at that point is the value of the marginal function at that point. The slope of a ray drawn from the origin through the point is the value of the average function. If the absolute value of the slope of the tangent is greater than the slope of the ray then the function is elastic at the point; if the slope of the secant is greater than the absolute value of the slope of the tangent then the curve is inelastic at the point.[3] If the tangent line is extended to the horizontal axis the problem is simply a matter of comparing angles formed by the lines and the horizontal axis. If the marginal angle is greater than the average angle then the function is elastic at the point; if the marginal angle is less than the average angle then the function is inelastic at that point. If, however, one follows the convention adopted by economists and plots the independent variable P on the vertical axis and the dependent variable Q on the horizontal axis, then the opposite rules would apply.
The same graphical procedure can also be applied to a supply function or other functions.
## Semi-elasticity
A semi-elasticity (or semielasticity) gives the percentage change in f(x) in terms of a change (not percentage-wise) of x. Algebraically, the semi-elasticity S of a function f at point x is [4][5]
$Sf(x) = \frac{1}{f(x)}f'(x) = \frac{d \ln f(x)}{d x}$
An example of semi-elasticity is modified duration in bond trading.
The term "semi-elasticity" is also sometimes used for the change if f(x) in terms of a percentage change in x[6] which would be
$\frac{d f(x)}{d\ln(x)}=\frac{d f(x)}{dx}x$
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https://artsocial.info/and-relationship/projectile-acceleration-and-velocity-relationship.php
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# Projectile acceleration and velocity relationship
### What are the kinematic formulas? (article) | Khan Academy
Of course, to describe motion we must deal with velocity and acceleration, . This equation defines the maximum height of a projectile and depends only on the. Apr 30, A projectile's motion can be described in terms of velocity, time and height. How to Calculate the Jump Height From Acceleration Solve this equation for t by isolating it on one side of the equation shown in the previous. Plotting projectile displacement, acceleration, and velocity About x squared for example, and.
Now let's hop in a roller coaster or engage in a similarly thrilling activity like downhill skiing, Formula One racing, or cycling in Manhattan traffic.
Acceleration is directed first one way, then another. You may even experience brief periods of weightlessness or inversion. These kinds of sensations generate intense mental activity, which is why we like doing them. They also sharpen us up and keep us focused during possibly life ending moments, which is why we evolved this sense in the first place.
Your ability to sense jerk is vital to your health and well being. Jerk is both exciting and necessary.
Constant jerk is easy to deal with mathematically. As a learning exercise, let's derive the equations of motion for constant jerk. You are welcome to try more complicated jerk problems if you wish.
Jerk is the derivative of acceleration. Integrate jerk to get acceleration. That's the first time I've ever said that. I propose we call this the zeroeth equation of motion for constant jerk. The reason why will be apparent after we finish the next derivation.
Old videos on projectile motion Video transcript What I want to do with this video is think about what happens to some type of projectile, maybe a ball or rock, if I were to throw it straight up into the air. To do that I want to plot distance relative to time. There are a few things I am going to tell you about my throwing the rock into the air.
The rock will have an initial velocity Vi of We also know the acceleration near the surface of the earth. We know the force of gravity near the surface of the earth is the mass of the object times the acceleration.
## What are the kinematic formulas?
The whole reason why I did this is when we look at the g it really comes from the universal law of gravitation.
You can really view g as measuring the gravitational field strength near the surface of the earth. Then that helps us figure out the force when you multiply mass times g. This is accelerating you towards the center of the earth. The other thing I want to make clear: You might be saying "Wait, clearly the force of gravity is dependent on the distance. So if I were to throw something up into the air, won't the distance change.
## Kinematics & Calculus
That is technically right, but the reality is that when you throw something up into the air that change in distance is so small relative to the distance between the object and the center of the earth that to make the math simple, When we are at or near the surface of the earth including in our atmosphere we can assume that it is constant.
Remember that little g over there is all of these terms combined. If we assume that mass one m1 is the mass of the earth, and r is the radius of the earth the distance from the center of the earth So you would be correct in thinking that it changes a little bit.
The force of gravity changes a little bit, but for the sake of throwing things up into our atmosphere we can assume that it is constant.
### Horizontal and Vertical Components of Velocity
And if we were to calculate it it is 9. I want to be clear these are vector quantities.
When we start throwing things up into the air the convention is if something is moving up it is given a positive value, and if it is moving down we give it a negative value. Well, for an object that is in free fall gravity would be accelerating it downwards, or the force of gravity is downwards.
• Deriving displacement as a function of time, acceleration, and initial velocity
• Describing Projectiles With Numbers: (Horizontal and Vertical Velocity)
So, little g over here, if you want to give it its direction, is negative. Little g is So, we have the acceleration due to gravity. The acceleration due to gravity ag is negative 9. Now I want to plot distance relative to time.
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http://vec3.ca/code/math/projection-direct3d/
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# Projection: Direct3D Edition
Projection is one of the core transformations done in 3D graphics. It’s generally represented by a $4\times4$ matrix, and it is the thing that links view space to clip space. The basics are pretty standard, and you can easily find them elsewhere. This article is about interesting things you can do with the projection matrix once you’ve got it.
Now, projection matrices differ depending on the conventions underlying the target environment. OpenGL’s clip space extends from $-1$ to $1$ in all three axes with the z-axis pointing out of the screen. DirectX’s z-axis points into the screen, and the near plane is mapped to $z=0$ rather than $z=-1$. This article will focus on matrices using the DirectX convention, though similar derivations exist for OpenGL.
Note that I’m using only the DirectX clip-space convention. I’m going to stick with the standard points-are-column-vectors-on-the-right convention used in most graphics literature, so my projection matrix will appear transposed with respect to that seen in the DirectX documentation on MSDN. I’m also going to assume that view space is right-handed, so one minus sign is moved.
Moving right along, here’s the matrix:
$$P=\begin{bmatrix} P_{11} & 0 & 0 & 0 \\ 0 & P_{22} & 0 & 0 \\ 0 & 0 & P_{33} & P_{34} \\ 0 & 0 & -1 & 0 \end{bmatrix}$$
$$P_{33}=\frac{z_f}{z_n-z_f},\;P_{34}=\frac{z_nz_f}{z_n-z_f}$$
$z_n$ and $z_f$ are, respectively, the distances to the near and far clip planes in view space units. $P_{11}$ and $P_{22}$ can be computed using one of two sets of formulas:
$$P_{11}=\frac{2z_n}{v_w},\;P_{22}=\frac{2z_n}{v_h}$$
$$P_{11}=cot\left({\tiny\frac{1}{2}}f_h\right),\;P_{22}=cot\left({\tiny\frac{1}{2}}f_v\right)$$
The first pair sizes the frustum in terms of the size of the viewport ($v_w$, $v_h$) in view-space units on the near plane. The second pair (which I find more natural to use) sizes the frustum based on the horizontal and vertical field of view angles ($f_h$ and $f_v$).
Further, if we project a point in view space $\mathbf{v}$ through $P$, we get the following coordinates:
$$P\mathbf{v}=\mathbf{v’}=\begin{bmatrix}x’ \\ y’ \\ z’ \\ w’\end{bmatrix}= \begin{bmatrix} P_{11}x \\ P_{22}y \\ z\frac{z_f}{z_n-z_f}+\frac{z_nz_f}{z_n-z_f} \\ -z \end{bmatrix}$$
# Extracting the Frustum Parameters
Alright, so we’ve got a matrix, but some odd algorithm somewhere needs to know what the near-clip plane is, or what the field of view is, or how big the viewport is.
### Field of View
The horizontal and vertical field of view are fairly straightforward. We can simply reverse the second set of formulas for $P_{11}$ and $P_{22}$.
$$P_{11}=cot\left({\tiny\frac{1}{2}}f_h\right)=\left[tan\left({\tiny\frac{1}{2}}f_h\right)\right]^{-1}$$
$$\arctan(P_{11}^{-1})={\tiny\frac{1}{2}}f_h$$
$$f_h=2\arctan(P_{11}^{-1})$$
Similarly, the vertical field of view is:
$$f_v=2\arctan(P_{22}^{-1})$$
### Aspect Ratio
Another easy one is the viewport’s aspect ratio. The aspect is defined as the viewport’s width over its height. We’ve got formulas for those values:
$$P_{11}=\frac{2z_n}{v_w},\;P_{22}=\frac{2z_n}{v_h}$$
$$v_w=\frac{2z_n}{P_{11}},\;v_h=\frac{2z_n}{P_{22}}$$
And while $z_n$ is unknown, that doesn’t matter as we only want the ratio between the two, and it cancels out:
$$aspect=\frac{v_w}{v_h}=\frac{\frac{2z_n}{P_{11}}}{\frac{2z_n}{P_{22}}}=\frac{P_{22}}{P_{11}}$$
### The Near-Clip Distance
Getting the value of $z_n$ is also simple. Notice that the only difference between $P_{34}$ and $P_{33}$ is that the former has an extra $z_n$ multiplied into it.
$$z_n=\frac{P_{34}}{P_{33}}$$
### The Far-Clip Distance
This one’s a little trickier, but again, it’s just some algebra on $P_{34}$ and $P_{33}$. Let’s start with the formula for $P_{33}$ and substitute in our formulat for $z_n$:
$$P_{33}=\frac{z_f}{z_n-z_f}=\frac{z_f}{\frac{P_{34}}{P_{33}}-z_f}$$
$$\frac{1}{P_{33}}=\frac{\frac{P_{34}}{P_{33}}-z_f}{z_f}$$
$$\frac{z_f}{P_{33}}=\frac{P_{34}}{P_{33}}-z_f$$
$$z_f=P_{34}-P_{33}z_f$$
$$-P_{34}=-z_f-P_{33}z_f$$
$$P_{34}=z_f+P_{33}z_f$$
$$P_{34}=z_f(P_{33}+1)$$
$$z_f=\frac{P_{34}}{P_{33}+1}$$
### The Viewport Size
And now that we have the near-clip distance, we can easily compute our viewport’s dimensions:
$$v_w=\frac{2z_n}{P_{11}},\;v_h=\frac{2z_n}{P_{22}}$$
$$v_w=\frac{2\frac{P_{34}}{P_{33}}}{P_{11}},\;v_h=\frac{2\frac{P_{34}}{P_{33}}}{P_{22}}$$
# Inverting the Matrix
The projection matrix is pretty sparse, so it’s quite straightforward to write an optimized matrix inverse function just for it. Of course, a general $4\times4$ matrix inverse function will work, but the inverse of the projection matrix pops up enough that it doesn’t hurt to have an optimized routine in your toolkit.
One note before we proceed – matrices intended for left and right-handed view-space differ in the sign of the values in the last two rows – including that of the $-1$ in our $P$. However, the matrix-inverse code doesn’t need to care about this, so I will substitute a variable $P_{43}$ for this section:
$$P=\begin{bmatrix} P_{11} & 0 & 0 & 0 \\ 0 & P_{22} & 0 & 0 \\ 0 & 0 & P_{33} & P_{34} \\ 0 & 0 & P_{43} & 0 \end{bmatrix}$$
$$det(P)=\begin{vmatrix} P_{11} & 0 & 0 & 0 \\ 0 & P_{22} & 0 & 0 \\ 0 & 0 & P_{33} & P_{34} \\ 0 & 0 & P_{43} & 0 \end{vmatrix}= P_{43}\begin{vmatrix} P_{11} & 0 & 0 \\ 0 & P_{22} & 0 \\ 0 & 0 & P_{34} \end{vmatrix}= P_{11}P_{22}P_{34}P_{43}$$
Looking at the construction of the matrix, that’s clearly not going to equal zero. So the matrix is definitely invertible. I’ll spare you the tedious algebra and skip straight to the answer. Apply your favorite method of finding the inverse and waste a bunch of paper simplifying if you don’t believe me (or multiply it by $P$ and see if you get $I$).
$$P^{-1}=\begin{bmatrix} P_{11}^{-1} & 0 & 0 & 0 \\ 0 & P_{22}^{-1} & 0 & 0 \\ 0 & 0 & 0 & P_{43}^{-1} \\ 0 & 0 & P_{34}^{-1} & -\frac{P_{33}}{P_{34}P_{43}} \end{bmatrix}$$
# Unprojection
This is a fairly useful operation. It’s often used to implement picking, and it has a significant application in deferred-shading. But let’s not get ahead of ourselves.
Given a point in view space $\mathbf{v}$, its counterpart in clip space ($\mathbf{v’}$) is
$$\mathbf{v’}=P\mathbf{v}$$
Which is trivially reversible given that $P$ is invertible:
$$\mathbf{v}=P^{-1}\mathbf{v’}$$
$\mathbf{v}$ is, of course, translated in and out of homogeneous space by adding and dividing away a $w$ component in the usual way, and the same applies to $\mathbf{v`}$.
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https://www.jobilize.com/online/course/0-5-sampling-with-automatic-gain-control-by-openstax?qcr=www.quizover.com&page=17
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# 0.5 Sampling with automatic gain control (Page 18/19)
Page 18 / 19
But why do the two algorithms converge to different places? The facile answer is that they are different becausethey minimize different performance functions. Indeed, the error surfaces in [link] show minima in different locations. The convergent value of $a\approx 0.38$ for ${J}_{N}\left(a\right)$ is explicable because $0.{38}^{2}\approx 0.15={\mathbf{s}}^{2}$ . The convergent value of $a=0.22$ for ${J}_{LS}\left(a\right)$ is calculated in closed form in Exercise [link] , and this value does a good job minimizing its cost,but it has not solved the problem of making ${a}^{2}$ close to ${\mathbf{s}}^{2}$ . Rather, ${J}_{LS}\left(a\right)$ calculates a smaller gain that makes $\text{avg}\left\{{s}^{2}\right\}\approx {\mathbf{s}}^{2}$ . The minima are different. The moral is this:Be wary of your performance functions—they may do what you ask.
Use agcgrad.m to investigate the AGC algorithm.
1. What range of stepsize mu works? Can the stepsize be too small?Can the stepsize be too large?
2. How does the stepsize mu effect the convergence rate?
3. How does the variance of the input effect the convergent value of a ?
4. What range of averages lenavg works? Can lenavg be too small? Can lenavg be too large?
5. How does lenavg effect the convergence rate?
Show that the value of $a$ that achieves the minimum of ${J}_{LS}\left(a\right)$ can be expressed as
$±\sqrt{\frac{{\mathbf{s}}^{2}{\sum }_{k}{r}_{k}^{2}}{{\sum }_{k}{r}_{k}^{4}}}.$
Is there a way to use this (closed form) solution to replace the iteration [link] ?
Consider the alternative objective function $J\left(a\right)=\frac{1}{2}{a}^{2}\left(\frac{1}{2}\frac{{s}^{2}\left[k\right]}{3}-{\mathbf{s}}^{2}\right)$ . Calculate the derivative and implement avariation of the AGC algorithm that minimizes this objective. How does this version compare to the algorithms [link] and [link] ? Draw the error surface for this algorithm. Which version is preferable?
Try initializing the estimate a(1)=-2 in agcgrad.m . Which minimum does the algorithm find? What happens tothe data record?
Create your own objective function $J\left(a\right)$ for the AGC problem. Calculate the derivative and implement avariation of the AGC algorithm that minimizes this objective. How does this version compare to the algorithms [link] and [link] ? Draw the error surface for your algorithm. Which version do you prefer?
Investigate how the error surface depends on the input signal. Replace randn with rand in agcerrorsurf.m and draw the error surfaces for both ${J}_{N}\left(a\right)$ and ${J}_{LS}\left(a\right)$ .
## Using an agc to combat fading
One of the impairments encountered in transmission systems is the degradation due to fading, when the strengthof the received signal changes in response to changes in the transmission path. (Recall the discussion in [link] .) This section shows how an AGC can be used to counteractthe fading, assuming the rate of the fading is slow, and provided the signal does not disappear completely.
Suppose that the input consists of a random sequence undulating slowly up and down in magnitude, as in the topplot of [link] . The adaptive AGC compensates for the amplitude variations,growing small when the power of the input is large, and large when the power of the input is small. This is shown in themiddle graph. The resulting output is of roughly constant amplitude, as shown in the bottom plot of [link] .
#### Questions & Answers
how can chip be made from sand
are nano particles real
yeah
Joseph
Hello, if I study Physics teacher in bachelor, can I study Nanotechnology in master?
no can't
Lohitha
where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
has a lot of application modern world
Kamaluddeen
yes
narayan
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Got questions? Join the online conversation and get instant answers!
|
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|
https://support.bioconductor.org/p/62068/
|
Search
Question: ‘IlluminaHumanMethylation450k.db’ had non-zero exit status
0
3.8 years ago by
United Kingdom
ben.run9740 wrote:
Hi,
I tried to install IlluminaHumanMethylation450k.db using biocLite but keep having some error messages. I have been able to install and use it in the past but I had to reinstall R in the meantime. I have checked that all dependancies are installed (methods, AnnotationDbi, org.Hs.eg.db).
> source("http://bioconductor.org/biocLite.R")
Bioconductor version 3.0 (BiocInstaller 1.16.0), ?biocLite for help
> biocLite("IlluminaHumanMethylation450k.db")
BioC_mirror: http://bioconductor.org
Using Bioconductor version 3.0 (BiocInstaller 1.16.0), R version 3.1.1.
Installing package(s) 'IlluminaHumanMethylation450k.db'
trying URL 'http://bioconductor.org/packages/3.0/data/annotation/src/contrib/IlluminaHumanMethylation450k.db_2.0.7.tar.gz'
Content type 'application/x-gzip' length 63268195 bytes (60.3 Mb)
opened URL
=================================================
* installing *source* package ‘IlluminaHumanMethylation450k.db’ ...
** R
** inst
Error in get(name, envir = asNamespace(pkg), inherits = FALSE) :
Error : unable to load R code in package ‘IlluminaHumanMethylation450k.db’
* removing ‘/home/benhur/R/x86_64-pc-linux-gnu-library/3.1/IlluminaHumanMethylation450k.db’
Warning message:
In install.packages(pkgs = pkgs, lib = lib, repos = repos, ...) :
installation of package ‘IlluminaHumanMethylation450k.db’ had non-zero exit status
> sessionInfo()
R version 3.1.1 (2014-07-10)
Platform: x86_64-pc-linux-gnu (64-bit)
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C LC_TIME=C LC_COLLATE=C LC_MONETARY=C
[6] LC_MESSAGES=C LC_PAPER=C LC_NAME=C LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=C LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] BiocInstaller_1.16.0
loaded via a namespace (and not attached):
[1] tools_3.1.1
Hopefully someone would be able to help me :).
Cheers
Ben
modified 2.4 years ago by katwre0 • written 3.8 years ago by ben.run9740
0
3.8 years ago by
United States
James W. MacDonald46k wrote:
It's broken right now. See A: IlluminaHumanMethylation450k.db has undeclared dependency on AnnotationForge
You could hypothetically hack the source package to work, or just wait for Tim Triche to upload the new version.
0
3.8 years ago by
United States
James W. MacDonald46k wrote:
Also note that you should really be using the FDb.InfiniumMethylation.hg19 package instead. Howeva:
mv /data/tmp/Rtmp4DWP9d/downloaded_packages/IlluminaHumanMethylation450k.db_2.0.7.tar.gz .
tar xvfz IlluminaHumanMethylation450k.db_2.0.7.tar.gz
<snip>
cd IlluminaHumanMethylation450k.db/R
sed -i 's/AnnotationForge:::createSimpleBimap/AnnotationDbi:::createSimpleBimap/g' zzz.R
cd ../../
R CMD INSTALL IlluminaHumanMethylation450k.db
* installing to library ‘/data/oldR/R-3.1.1/lib64/R/library’
* installing *source* package ‘IlluminaHumanMethylation450k.db’ ...
** R
** inst
** help
*** installing help indices
** building package indices
** testing if installed package can be loaded
Warning: 'IlluminaHumanMethylation450k.db' is deprecated.
Use 'mapToGenome() function in minfi or methylumi' instead.
See help("Deprecated")
* DONE (IlluminaHumanMethylation450k.db)
But like I said, use the FDb package instead...
Hi, tried your way. But no luck. Here is the output:
* installing to library ‘/usr/local/lib/R/site-library’
* installing *source* package ‘IlluminaHumanMethylation450k.db’ ...
** R
** inst
** help
*** installing help indices
** building package indices
** testing if installed package can be loaded
call: NULL
error: 'fun' is defunct.
Use 'mapToGenome() function in minfi or methylumi' instead.
See help("Defunct")
Execution halted
* removing ‘/usr/local/lib/R/site-library/IlluminaHumanMethylation450k.db’
What is that sed command doing? I can find no difference between the zzz.R files with and without using this command.
1
You are getting a completely different error than Ben was getting. So why do you think that what I suggested to him would work for you? Is there a particular reason that the FDb.InfiniumMethylation.hg19 is not useful for you?
Thanks for quick response, actually i need to use UCSC CpG island name "IlluminaHumanMethylation450kCPGINAME".
In that case, you need to make a new post asking why the current version of that package won't install. When I try to install it, I get the same error as you.
0
3.8 years ago by
United Kingdom
ben.run9740 wrote:
Thank you!!
Unfortunately I'm using another package that depends on IlluminaHumanMethylation450k.db so I have to install it :)
Cheers,
Ben
0
2.4 years ago by
katwre0
Germany
katwre0 wrote:
Installation of IlluminaHumanMethylation450k.db using biocLite (still) doesn't work :(
> sessionInfo()
R version 3.2.3 (2015-12-10)
Platform: x86_64-redhat-linux-gnu (64-bit)
Running under: CentOS release 6.7 (Final)
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 LC_MONETARY=en_US.UTF-8
[6] LC_MESSAGES=en_US.UTF-8 LC_PAPER=en_US.UTF-8 LC_NAME=C LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] grid stats4 parallel stats graphics grDevices utils datasets methods base
other attached packages:
[1] rtracklayer_1.30.1 genomation_1.3.4 limma_3.26.3 colorfulVennPlot_2.4 ChIPpeakAnno_3.4.5 RSQLite_1.0.0
[7] DBI_0.3.1 VennDiagram_1.6.16 futile.logger_1.4.1 Biostrings_2.38.3 XVector_0.10.0 BiocInstaller_1.20.1
[13] Vennerable_3.0 xtable_1.8-2 gtools_3.5.0 reshape_0.8.5 RColorBrewer_1.1-2 lattice_0.20-33
[19] RBGL_1.46.0 graph_1.48.0 GenomicRanges_1.22.2 GenomeInfoDb_1.6.1 IRanges_2.4.6 S4Vectors_0.8.5
[25] BiocGenerics_0.16.1
loaded via a namespace (and not attached):
[1] Biobase_2.30.0 httr_1.1.0 regioneR_1.2.3 AnnotationHub_2.2.3 splines_3.2.3
[6] shiny_0.13.0 interactiveDisplayBase_1.8.0 BSgenome_1.38.0 Rsamtools_1.22.0 impute_1.44.0
[11] chron_2.3-47 digest_0.6.9 colorspace_1.2-6 htmltools_0.3 httpuv_1.3.3
[16] plyr_1.8.3 XML_3.98-1.3 biomaRt_2.26.1 zlibbioc_1.16.0 GO.db_3.2.2
[21] scales_0.3.0 BiocParallel_1.4.3 ggplot2_2.0.0 seqPattern_1.2.0 SummarizedExperiment_1.0.2
[26] GenomicFeatures_1.22.7 survival_2.38-3 magrittr_1.5 mime_0.4 memoise_1.0.0
[31] MASS_7.3-45 tools_3.2.3 data.table_1.9.6 matrixStats_0.50.1 gridBase_0.4-7
[36] stringr_1.0.0 munsell_0.4.2 plotrix_3.6-1 AnnotationDbi_1.32.3 ensembldb_1.2.2
[41] lambda.r_1.1.7 RCurl_1.95-4.7 bitops_1.0-6 gtable_0.1.2 multtest_2.26.0
[46] reshape2_1.4.1 R6_2.1.2 GenomicAlignments_1.6.1 futile.options_1.0.0 KernSmooth_2.23-15
[51] readr_0.2.2 stringi_1.0-1 Rcpp_0.12.3
1
Right. And this is because the package is now defunct, which means it is no longer supported, and will be removed soon, probably in the next release. As I mentioned multiple times in this thread, you should be using the FDb.InfiniumMethylation.hg19 package instead, which is intended to replace the IlluminaHumanMethylation450k.db package.
If you are using a package that depends on the IlluminaHumanMethylation450k.db package (which seems not to be possible since it won't build, but whatever), you have two choices. Either take it upon yourself to fix the IlluminaHumanMethylation450k.db package so it will build, or contact the maintainer of the package that depends on it and have them switch to using the Fdb.InfiniumMethylation.hg19 package. The latter seems to be the easier way to go, but ymmv.
But in my case, I need this package because I'm trying to do a practise of my Master, and I had a problem with our website Rstudio app, and now I can't install the package.....
You would be able to install it from an old repository or something like that if you want to use it...
I need to use the package anyway, so if someone can help me, it would be great.
Thank you
Did you manage to use your library? I have similar problem - I have to use Aclust library, which needs IlluminaHumanMethylation450k.db. I'd be really grateful for any information how you solved this problem, if you did.
Kind regards,
Agata
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|
https://homework.zookal.com/questions-and-answers/suppose-robotsx1-and-staffx2-are-needed-to-run-a-shop-677248661
|
Suppose robots(x1) and staff(x2) are needed to run a shop. Robots cost $21 p year while staff cost$49 per year. Also, robots can serve 7 customers an hour while staff can serve 4 customers per hour. Suppose the shop needs to serve 74 customers per hour while achieving the lowest cost. What is the total cost of robots and staff needed anually ?
|
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https://www.ijert.org/sylow-prime-group
|
# Sylow Prime Group
DOI : 10.17577/IJERTV9IS040587
Text Only Version
#### Sylow Prime Group
T. Srinivasarao Asst. Professor Dept. of Math
Mr. K. Revathi Asst. Professor Dept. of Math
University College of Science & Technology Adikavi Nannaya University
University College of Science & Technology Adikavi Nannaya University
Abstract: Sylow p subgroup is a vital part of the discussion in any algebraic activity dealing with group theory. So, it is natural that, is every group can have Sylow p subgroups or any specific distinction can be put forward that confirms a particular group is either a group having Sylow p subgroup or there is no single Sylow p subgroup. With a view to characterize the groups whether possessing a Sylow p subgroup or not here is an activity that progresses the discussion by one step ahead. This discussion leads to groups of order p and order pq that has applications in Galvan theory.
INTRODUCTION:
Suppose n is a positive integer. By the fundamental theorem of arithmetic, either n is a group of prime order or it is a product of
primes expressible in a unique manner as n p 1 p 2 … p k
where
p ' s are prime numbers with the respective multiplicities
i ,1 i k .
1 2 k i
Since each p is a prime number, 1 i k , there exists a cyclic group G ,1 i k such that
G p i ,1 i k
i
Now, G G1 G2 … Gk
i i i
1. Sylow Prime Group:
Definition : if G is a finite group, p is a prime number such that called a Sylow p subgroup of G. (1.1)
pn | G and pn1 | G , then any subgroup of G of order
pn is
Definition 2: a group (G, *) is said to be a Sylow prime group if every non trivial subgroup of G is a Sylow
pi – subgroup for
some prime factor (1.2)
pi of the order of G.
Since G n p 1 p 2 …p k , and in view of Lagranges theorem of finite groups, and properties of divisibility, it follows that
1 2 k
p i | G
for each 1 i k and p
i1 | G
by the unique representation of the integer n.
i i1
pi i
pi i
It is not necessary that there is a subgroup of G of order for every 1 i k . This confirms that every group of finite order is not a Sylow prime group.
To verify these observations, the following instances will show a finite group that admits the definition of Sylow prime group and another instance for not.
2. Working on Sylow Prime Groups:
Consider the symmetric group of order 6 or the symmetric group on 3 symbols.
S3 f1, f2 , f3 , f4 , f5 , f6 where
f1 a, a,b,b,c,c f2 a,b,b, a,c,c f3 a, a,b,c,c,b f4 a,c,b,b,c, a f5 a,b,b,c,c, a f6 a,c,b, a,c,b
fi : A A is a bijection for each 1 i 6 and
A a,b,c
The composition of mappings is the operation that makes S3 a group such that S 6 2 3 , the unique representation
1 1
3
3
3
3
by fundamental theorem of arithmetic
It can be easily seen that H f , f , H f , f , f are the only non trivial subgroups such that H 21,22 | S and so,
1 1 4 2 1 5 6 1 3
H1 is a Sylow 2- subgroup of S3
Similarly, H 31,32 | S and so, H is a Sylow 3 subgroup of S (2.1)
2 3 2 3
Take another instance.
12 1,5,7,11is a group under multiplication modulo 12 denoted by 12 .
12 4 22
H1 1,11 is a non trivial subgroup of order 21 .
1
1
Also, 22 | 12 which shows H is not a Sylow 2 subgroup of 12
So, this is an example of a group that is not a Sylow prime group. (2.2) The working (2.1) and (2.2) will confirm that all finite groups are not Sylow Prime Groups.
REFERENCES:
1. R.Gow, Sylows proof of Sylows theorem, Irish Math.Sco.Bull. (1994), 55 63
2. L.Sylow, Theorems sur les groups de substitutions, Mathematische Annalen 5(1872), 584 594
3. W. C. Waterhouse, The early proofs of Sylows theorems, Arch.Hist.Exact Sci, 21(1979/80), 279-290
4. William Fulton and Joe Harris. Representation Theory: A First Course. GTM 129, Springer, 1991
|
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|
https://icml.cc/Conferences/2020/ScheduleMultitrack?event=6460
|
Timezone: »
Poster
Fair k-Centers via Maximum Matching
Matthew Jones · Huy Nguyen · Thy Nguyen
Wed Jul 15 05:00 AM -- 05:45 AM & Wed Jul 15 04:00 PM -- 04:45 PM (PDT) @ Virtual #None
The field of algorithms has seen a push for fairness, or the removal of inherent bias, in recent history. In data summarization, where a much smaller subset of a data set is chosen to represent the whole of the data, fairness can be introduced by guaranteeing each "demographic group" a specific portion of the representative subset. Specifically, this paper examines this fair variant of the k-centers problem, where a subset of the data with cardinality k is chosen to minimize distance to the rest of the data. Previous papers working on this problem presented both a 3-approximation algorithm with a super-linear runtime and a linear-time algorithm whose approximation factor is exponential in the number of demographic groups. This paper combines the best of each algorithm by presenting a linear-time algorithm with a guaranteed 3-approximation factor and provides empirical evidence of both the algorithm's runtime and effectiveness.
|
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|
http://gmatclub.com/forum/ps-combinatorics-151558.html?fl=similar
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# PS Combinatorics
Author Message
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Intern
Joined: 06 Apr 2013
Posts: 3
Location: United States
Concentration: Finance, General Management
GMAT Date: 05-07-2013
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### Show Tags
24 Apr 2013, 14:11
Hi Guys,
I am new to this community and my GMAT will take place in 12 days.
I have question concerning two diffierent PS Combinatorics Questions. For my they seem to be identical dispite the round table and the number of items.
But they are solved in two different ways.
Here are the two Problems:
1. In how many ways can 11 # signs and 8* signs be arranged in a row so that no two * signs come together?
Answer Should be: (taken for the GMAT Club Combinatorics Set)
1st we place the 11#, now there are 10 places between them and 2 on the extreme left and extreme right of them, total places = 10 + 2 = 12
If * is placed at any of these 12 places, no 2 *'s will be together
so the number ways will be 12C8 = 12C4 = 495
2. Seven men and five women have to sit around a circular table so that no 2 women are together. In how many different ways can this be done?
Answer form Bunnel (which I totally understand):
# of arrangements of 7 men around a table is (7-1)!=6!;
There will be 7 possible places for women between them, 7 empty slots. # of ways to choose in which 5 slots women will be placed is C^5_7=21;
# of arrangements of 5 women in these slots is 5!;
So total: 6!*21*5!=1,814,400.
In my point of view the first problem should be solved with the same approach. Like this:
11! * 8! * 11C8 = very very big number....
I am a little confused. May somebody can help me? I also have problems to understand when we consider the objects like the # sings to be all different e.g #1 ; #2 etc. and when they all are just # so #=# for every #.
I hope you can understand my question.
Kind regards,
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### Show Tags
24 Apr 2013, 22:04
1
KUDOS
Expert's post
Cityboy wrote:
Hi Guys,
I am new to this community and my GMAT will take place in 12 days.
I have question concerning two diffierent PS Combinatorics Questions. For my they seem to be identical dispite the round table and the number of items.
But they are solved in two different ways.
Here are the two Problems:
1. In how many ways can 11 # signs and 8* signs be arranged in a row so that no two * signs come together?
Answer Should be: (taken for the GMAT Club Combinatorics Set)
1st we place the 11#, now there are 10 places between them and 2 on the extreme left and extreme right of them, total places = 10 + 2 = 12
If * is placed at any of these 12 places, no 2 *'s will be together
so the number ways will be 12C8 = 12C4 = 495
2. Seven men and five women have to sit around a circular table so that no 2 women are together. In how many different ways can this be done?
Answer form Bunnel (which I totally understand):
# of arrangements of 7 men around a table is (7-1)!=6!;
There will be 7 possible places for women between them, 7 empty slots. # of ways to choose in which 5 slots women will be placed is C^5_7=21;
# of arrangements of 5 women in these slots is 5!;
So total: 6!*21*5!=1,814,400.
In my point of view the first problem should be solved with the same approach. Like this:
11! * 8! * 11C8 = very very big number....
I am a little confused. May somebody can help me? I also have problems to understand when we consider the objects like the # sings to be all different e.g #1 ; #2 etc. and when they all are just # so #=# for every #.
I hope you can understand my question.
Kind regards,
Hey There,
The key thing to be noted here is, In problem one the objects to be arranged are identical; 11# signs and 8 * signs are identical in their respective groups. e.g. If you want to arrange 11 # signs in a row, you can do so in only one way because they are identical to each other. You can not distinguish a particular # sign from rest of the signs, whereas in the second problem, objects to be arranged are all different, so in this case you will get many number of ways to arrange those different objects. e.g. 4 persons you can arrange in 4! ways. This is the reason why answer of the 2nd ques is much more greater than that of the 1st
back to the Ques 1 :- In how many ways can 11 # signs and 8* signs be arranged in a row so that no two * signs come together?
jobs to be done
1) Arrangement of 11 # signs in a row ---------> You have only one option to arrange those signs, since they are identical
Having arranged them, now we have 12 places where we can place the 8 * signs
2) Selection of 8 places from 12 places to place the 8 * signs ------------> you can do this in 12C8 ways i.e. 495 ways
3) Arrangement of 8 * signs at 8 places selected earlier ---------> You have only one option to arrange those signs, since they are identical
Total Number of Arrangement{By Fundamental Principle of multiplication} = 1 X 495 X 1 = 495
Ques 2 :- 7 men and 5 women have to sit around a circular table so that no 2 women are together. In how many different ways can this be done?
jobs to be done
1) arrangement of 7 men around a table ----------> This you can do in (7-1)! = 6! ways. Because now you are doing circular arrangement and unlike linear arrangements, circulation arrangements dont have beginning or end.
Having arranged them, you have 7 places where you can arrange 5 women
2) selection of 5 places from 7 places where you can arrange women ----------> This can be done in 7C5 ways
3) Arrangement of 5 women at 5 places selected earlier-------> 5! ways
Total Number of Arrangement{By Fundamental Principle of multiplication} = 6! X 7C5 X 5! = 1814400
Regards,
Narenn
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25 Apr 2013, 03:30
First of all: Thanks a lot for this amazing answer.
But I still have big touble with the Combinatoric Tasks:
For Example:
There are 12 people in a room: 4 couples and 4 singles. picking 4 people at random, which is the probability of picking only one couple?
I understand that the Total amount of combinations of a Group of four is 12C4= 33*15
I also the the point that I can get 4 different couples = 4
But I am confused how we calculate the whole denomerator:
We have three option:
1. Combining one pair with 2 Singles (so we take 2 out of 4 which is 4C2 = 6 or not?)
2. Combining one pair with one guy of a another pair and one single (so we take one out of four singles 4C1 and one person form the remaining 6 who are in a couple which is 6C1 = 6) Both together is 4*6 = 24
3. Combining one pair with one guy of a pair and one guy of another pair ( we take one out of the 6 people who live in a couple which is 6C1= 6 and then again one out of the 4 remaining people who are a couple which is 4C1= 4) leads to 24
In the end I got 4*(24+24+6)= 216
216/33*11 = Does not lead to the official answer. OA seems to be 56/165 (taken form this discussion in the forum unfortuntaley I can not posts links...)
I really do not understand how to build up the ways of chosing one single and one guy of a couple and so on. I have this porblem in general. Can someone give me an advice how to think about such kind of problems?
Are there more such problems available?
Kind regards
Last edited by Cityboy on 25 Apr 2013, 05:52, edited 1 time in total.
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### Show Tags
25 Apr 2013, 05:48
Expert's post
There are 12 people in a room: 4 couples and 4 singles. picking 4 people at random, which is the probability of picking only one couple?
Probability = $$\frac{Desired outcomes}{Total Outcomes}$$
Total Outcomes = selection of 4 persons among 12 persons = 12C4 = 495
Desired Outcomes = Selection of 1 Couple AND selection of 2 persons from remaining 10 persons (Condition - The two selected should not be a couple)
1 couple can be selected from 4 couples in 4C1 ways.
Now we are left with 3 couples and 4 singles (Total 10 Persons) from which we have to select 2 persons. (Condition - The two selected should not be a couple)
This can be calculated as = Total number of ways selecting 2 persons from 10 persons - Number of ways selecting a couple from available couples
= 10C2 - 3C2 = 42
Lets see how this arrived
Let these 10 persons be m1, f1, m2, f2, m3, f3, s1, s2, s3, s4
If you chose m1, you can choose any one of the remaining 9 persons except for f1--------> So the available options are 8
If you chose f1, you can choose any one of the remaining 9 persons except for m1--------> So the available options are 8
If you chose m2, you can choose any one of the remaining 9 persons except for f2, m1, f1 --------> So the available options are 6
If you chose f2, you can choose any one of the remaining 9 persons except for m2, m1, f1 --------> So the available options are 6
If you chose m3, you can choose any one of the remaining 9 persons except for f3, m1, m2, f1, f2 --------> So the available options are 4
If you chose f3, you can choose any one of the remaining 9 persons except for m3, m1, m2, f1, f2 --------> So the available options are 4
If you chose s1, you can choose any one of the remaining 9 persons except for m1, m2, m3, f1, f2, f3, f4 --------> So the available options are 3
If you chose s2, you can choose any one of the remaining 9 persons except for m1, m2, m3, f1, f2, f3, f4, s1--------> So the available option is 2
If you chose s3, you can choose any one of the remaining 9 persons except for m1, m2, m3, f1, f2, f3, f4, s1, s2--------> So the available options are 1
If you chose s3, you can choose any one of the remaining 9 persons except for m1, m2, m3, f1, f2, f3, f4, s1, s2, s3--------> So the available options are 0
Total 8+8+6+6+4+4+3+3+3 = 42 options
Total Desired outcomes [Fundamental Principle of Multiplication] = 4C1 X 42 = 168
Probablity = $$\frac{168}{495}$$
What is the OA ?
Narenn
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Last edited by Narenn on 25 Apr 2013, 06:18, edited 1 time in total.
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25 Apr 2013, 06:12
HI I Edited my post:
Unfortunately I cannot post links. You can find it nif you google "here are 12 people in a room: 4 couples and 4 singles. picking 4 people at random, which is the probability of picking only one couple?"
Big thanks again for your explanation!!!
So I have ten people remaining and first of all I can choose m1 or f1 so I still can combine m1 or f1 with 8 other people. (therefore 8 times 2)
In the next step I assume that I have choosen f1 or m1 before and then chose f2 or m2 and thus I can combine each of them with 6 other people? Then same for m3 and f3. Therefore 6 times 2
So right now I have already choosen m1, m2, m3 or f1,f2,f3 thus have s1,s2,s3,s4 left. So I can combine s1 with either s2,s3,s4 (or s2 with s1,s4,s3 or s3 with s2,s1,s4) which leads to 3x3 options.
Am I right?
MBA Section Director
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### Show Tags
25 Apr 2013, 06:22
Expert's post
Cityboy wrote:
HI I Edited my post:
Unfortunately I cannot post links. You can find it nif you google "here are 12 people in a room: 4 couples and 4 singles. picking 4 people at random, which is the probability of picking only one couple?"
Big thanks again for your explanation!!!
So I have ten people remaining and first of all I can choose m1 or f1 so I still can combine m1 or f1 with 8 other people. (therefore 8 times 2)
In the next step I assume that I have choosen f1 or m1 before and then chose f2 or m2 and thus I can combine each of them with 6 other people? Then same for m3 and f3. Therefore 6 times 2
So right now I have already choosen m1, m2, m3 or f1,f2,f3 thus have s1,s2,s3,s4 left. So I can combine s1 with either s2,s3,s4 (or s2 with s1,s4,s3 or s3 with s2,s1,s4) which leads to 3x3 options.
Am I right?
It should be 168/495 or 56/165 and not earlier that i posted. There was an error in the calculation. I have just corrected it.
Regards,
Narenn
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Re: PS Combinatorics [#permalink] 25 Apr 2013, 06:22
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http://www.ck12.org/algebra/Polynomials-in-Standard-Form/lecture/Intro-to-Polynomials-in-One-Variable/r1/
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<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
# Polynomials in Standard Form
## Understand polynomials as specific kinds of Algebraic expressions
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https://arxiv.org/abs/1910.06157
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astro-ph.CO
# Title:Differentiable Strong Lensing: Uniting Gravity and Neural Nets through Differentiable Probabilistic Programming
Abstract: The careful analysis of strongly gravitationally lensed radio and optical images of distant galaxies can in principle reveal DM (sub-)structures with masses several orders of magnitude below the mass of dwarf spheroidal galaxies. However, analyzing these images is a complex task, given the large uncertainties in the source and the lens. Here, we leverage and combine three important computer science developments to approach this challenge from a new perspective. (a) Convolutional deep neural networks, which show extraordinary performance in recognizing and predicting complex, abstract correlation structures in images. (b) Automatic differentiation, which forms the technological backbone for training deep neural networks and increasingly permeates `traditional' physics simulations, thus enabling the application of powerful gradient-based parameter inference techniques. (c) Deep probabilistic programming languages, which not only allow the specification of probabilistic programs and automatize the parameter inference step, but also the direct integration of deep neural networks as model components. In the current work, we demonstrate that it is possible to combine a deconvolutional deep neural network trained on galaxy images as source model with a fully-differentiable and exact implementation of the gravitational lensing physics in a single probabilistic model. This does away with hyperparameter tuning for the source model, enables the simultaneous optimization of nearly one hundred source and lens parameters with gradient-based methods, and allows the use of efficient gradient-based Hamiltonian Monte Carlo posterior sampling techniques. We consider this work as one of the first steps in establishing differentiable probabilistic programming techniques in the particle astrophysics community, which have the potential to significantly accelerate and improve many complex data analysis tasks.
Comments: 15 pages, 9 figures Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Phenomenology (hep-ph) Cite as: arXiv:1910.06157 [astro-ph.CO] (or arXiv:1910.06157v1 [astro-ph.CO] for this version)
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https://arxiv-export-lb.library.cornell.edu/abs/2209.12276
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math.AP
(what is this?)
# Title: Stable determination of a second order perturbation of the polyharmonic operator by boundary measurements
Abstract: In this paper, we consider the inverse boundary value problem for the polyharmonic operator. We prove that the second order perturbations are uniquely determined by the corresponding Dirichlet to Neumann map. More precisely, we show in dimension $n \geq 3$, a logarithmic type stability estimate for the inverse problem under consideration.
Subjects: Analysis of PDEs (math.AP) MSC classes: 35R30, 31B20, 31B30, 35J40 Cite as: arXiv:2209.12276 [math.AP] (or arXiv:2209.12276v1 [math.AP] for this version)
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https://www.neetprep.com/questions/477-Chemistry/7833-Structure-Atom?courseId=141&testId=1061969-Past-Year----MCQs&questionId=92142-Maximum-number-electrons-sub-shell-l---n------
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# Maximum number of electrons in a sub shell with l = 3 and n = 4 is 1. 14 2. 16 3. 10 4. 12
Subtopic: Quantum Numbers & Schrodinger Wave Equation |
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The correct set of four quantum numbers for the valence electron of a rubidium atom (Z =37) is
1. $5,1,1,+\frac{1}{2}$
2. $6,0,0,+\frac{1}{2}$
3. $5,0,0,+\frac{1}{2}$
4. $5,1,0,+\frac{1}{2}$
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The total number of atomic orbitals in fourth energy level of an atom is
1. 16
2. 32
3. 4
4. 8
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The energies E1 and E2 of two radiations are 25 eV and 50 eV respectively. The relation between their wavelenghs i.e., ${\mathrm{\lambda }}_{1}$ and ${\mathrm{\lambda }}_{2}$ will be
1. ${\mathrm{\lambda }}_{1}=2{\mathrm{\lambda }}_{2}$
2. ${\mathrm{\lambda }}_{1}=4{\mathrm{\lambda }}_{2}$
3. ${\mathrm{\lambda }}_{1}=\frac{1}{2}{\mathrm{\lambda }}_{2}$
4. ${\mathrm{\lambda }}_{1}={\mathrm{\lambda }}_{2}$
Subtopic: Bohr's Theory |
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If n = 6, the correct sequence for the filling of electrons will be
1.
2.
3.
4.
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The rule used to determine the maximum number of electrons in a subshell of an atom is
1. 4l+2
2. 2l+1
3. 4l-2
4. 2n2
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The incorrect set of quantum numbers among the following is
1. n= 4, l= 0, m= 0, s= -1/2
2. n= 5, l= 3, m= 0, s= +1/2
3. n= 3, l= 2, m= -3, s= -1/2
4. n= 3, l= 2, m= 2, s= -1/2
Subtopic: Quantum Numbers & Schrodinger Wave Equation |
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If uncertainty in position and momentum are equal, then uncertainty in velocity is:
1. $\frac{1}{2\mathrm{m}}\sqrt{\frac{\mathrm{h}}{\mathrm{\pi }}}$
2. $\sqrt{\frac{\mathrm{h}}{2\mathrm{\pi }}}$
3. $\frac{1}{\mathrm{m}}\sqrt{\frac{\mathrm{h}}{\mathrm{\pi }}}$
4. $\sqrt{\frac{\mathrm{h}}{\mathrm{\pi }}}$
Subtopic: Heisenberg Uncertainty Principle |
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The measurement of the electron position is associated with uncertainty in momentum, which is equal to 1 x 10-18 g cm s-1. The uncertainty in electron velocity will be (mass of an electron is 9 x 10-28 g)-
1. 2 x 109 cm s-1
2. 1 x 109 cm s-1
3. 1 x 105 cms-1
4. 1 x 1011 cm s-1
Subtopic: Heisenberg Uncertainty Principle |
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Consider the following sets of quantum numbers :
Which of the following sets of quantum number is not possible?
1. ii, iii and iv
2. i, ii, iii and iv
3. ii, iv and v
4. i and iii
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NEET 2023 - Target Batch - Aryan Raj Singh
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http://www-old.newton.ac.uk/programmes/GPF/seminars/2003111010001.html
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# GPF
## Seminar
### Ripple formation in an oscillating flow of a viscous liquid
Hinch, J (Cambridge)
Monday 10 November 2003, 10:00-10.45
Seminar Room 1, Newton Institute
hinch1.html
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https://fragile-credences.github.io/page9/
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A better formalism for interpreting confidence intervals
June 10, 2017
When we take a sample mean, we should think of it as a random variable, and our measured sample mean as a realisation of that random variable. The sample mean is a random variable because it is the result of random sampling. Repeated sampling involves observing repeated realisations of the random variable.
We should think of confidence intervals around this mean as realisations of a random interval, an interval whose bounds are random variables rather than real numbers. This is an attractive formalism because it resolves many confusions around the interpretation of confidence intervals.
Suppose the true population mean is the number $Y$. The mean of a random sample from this population is the random variable $\bar{y}$. Then the random interval
has an approximately 95% probability of containing $Y$.
Suppose in our sample $\bar{y}$ takes the realisation $1230$ and $se(\bar{y})$ takes the realisation $5.4$. So an instance of the above random interval is the confidence interval:
The confidence interval either contains or does not contain $Y$.
In full, my proposed interpretation schema is:
$[ 1230 - 1.96 * 5.4 , 1230 + 1.96 * 5.4 ]$,
is a realisation of
$[ \bar{y} - 1.96 se(\bar{y}) , \bar{y} + 1.96 se(\bar{y}) ]$,
and the probability
$P( Y \in[ \bar{y} - 1.96 se(\bar{y}) , \bar{y} + 1.96 se(\bar{y}) ]) = 0.95$.
• robustness: distinguishing random intervals from confidence intervals means it’s much harder to get confused into making an incorrect probabilistic statement about the non-probabilistic object $Y$.
• parsiomy: we express everything we want using only probabilities, random variables, and intervals, three well-understood notions.
• relevance: our interpretation only involves the objects we actually have (a random interval and a confidence interval). We need not make reference to (hypothetical) repeated sampling.
Unfortunately, my preferred formalism does not appear to be popular. Let me show some of the alternatives I have seen and explain their downsides and how my proposal does better.
1
The interval is random, not the parameter. Thus, we talk of the probability of the interval containing the parameter, not the probability of the parameter lying in the interval.
This is the worst example, and is admittedly rarely seen in print. But in speech I’ve seen it used often, even by academics who were trying to explain the correct interpretation of confidence intervals! The problem with this of course is that once you write it down in mathematical language, the probability of the interval containing the parameter is exactly the same object as the probability of the parameter lying in the interval. In our example it is simply $P(Y \in [ 1230 - 1.96 * 5.4 , 1230 + 1.96 * 5.4 ])$. It is equal to 1 or 0.
2
Quantitative Economics lecture notes for Oxford undergraduates:
“Were this procedure to be repeated on multiple samples, the calculated confidence interval (which would differ for each sample) would encompass the true population parameter 95% of the time.”
I don’t like this because:
• It invokes the clunky counterfactual “were this procedure to be repeated”. What if it’s impossible to take repeated samples? We still want to be able to make statements about our confidence interval.
• It doesn’t have a clear mathematical formalisation. how do I write “95% of the time” in terms of probabilities?
• The actual confidence interval we have is nowhere mentioned. For what is supposed to be an interpretation of that object, that’s a little confusing.
My formalism solves these three problems.
3
Wikipedia:
“There is a 90% probability that the calculated confidence interval from some future experiment encompasses the true value of the population parameter.”
Similar complaint here: why do we need to refer to future experiments? We want an interpretation of the confidence interval we actually have.
4
For this reason, for a 95% CI, we say that we have 95% confidence that the interval will cover the true population mean. We use the term ‘confidence’ instead of probability because although the sample mean is random, the single interval we calculate is fixed. We also cannot talk about the probability that the population mean will lie within a certain interval, since it is also fixed.
This needlessly introduces the new concept of ‘confidence’, which is bound to cause confusion. It’s much better to use probabilities, a concept we already understand and for which we have a formal notation.
Consistent Vegetarianism and the Suffering of Wild Animals - Journal of Practical Ethics
May 25, 2017
A revised version of the essay I wrote for the Uehiro Prize has been published in the Journal of Practical Ethics.
Abstract:
Ethical consequentialist vegetarians believe that farmed animals have lives that are worse than non-existence. In this paper, I sketch out an argument that wild animals have worse lives than farmed animals, and that consistent vegetarians should therefore reduce the number of wild animals as a top priority. I consider objections to the argument, and discuss which courses of action are open to those who accept the argument.
Qu'est-ce que l'altruisme efficace ?
July 24, 2016
Evénement de lancement de l’association Altruisme Efficace France, à Paris le 5 juillet 2016
Qu’est-ce que l’altruisme efficace ?
Quelles sont les meilleures façons d’aider les autres ? Bien entendu, cette question fait débat. Y répondre avec sérieux requiert des prises de positions morales, et des recherches empiriques approfondies. Les désaccords sont inévitables, et ils sont légitimes. Mais ce n’est pas pour autant qu’une affaire d’opinion. L’altruisme efficace est basé sur l’idée que toutes les manières d’aider les autres ne se valent pas.
Cette volonté de dépasser le domaine de l’opinion est tout à fait compatible avec une appréciation de la difficulté de la tâche et de l’incertitude de nos hypothèses. Une analogie avec la science pourrait être utile ici. Dans les sciences naturelles, les chercheurs sont souvent en désaccord. Cependant, malgré cette diversité de points de vue, il y a aussi beaucoup de consensus : il est démontré que certaines propositions sont incorrectes. Et au fur et à mesure que la communauté scientifique continue de récolter plus de données et de les analyser de manière critique, elle rejette les mauvaises théories, affine ses hypothèses, et progresse.
C’est ainsi que nous concevons l’altruisme efficace - une tentative de répondre à une question difficile, à laquelle nous pourrons apporter des réponses de plus en plus précises à mesure que nous y investissons plus d’effort. L’altruisme efficace, c’est avant tout cette question, et un engagement à tenter d’y répondre de manière rationnelle et scientifiquement argumentée. Ainsi, l’altruisme efficace est une démarche qu’il convient de séparer des conclusions particulières auxquelles l’on peut arriver en la suivant.
Enfin, l’altruisme efficace n’est pas qu’une analyse académique. Nous souhaitons identifier la meilleure manière d’aider, puis passer à l’action en la mettant en oeuvre.
Comment trouver une cause efficace ?
Parmi tous les moyens d’aider les autres, comment trouver celui qui permettrait d’avoir le plus grand impact ? Nous tentons de répondre à cette question en suivant certains principes fondateurs.
Faire le meilleur usage de nos ressources
Nos ressources sont limitées. Quelle que soit notre générosité, il est impossible de résoudre immédiatement tous les problèmes constatés dans le monde. Notre situation est similaire à celle d’un médecin en zone de guerre : il y a des centaines de blessés, mais le personnel médical est limité. Il met alors en place un système de triage médical, qui assigne un degré de priorité à chaque blessé, dans le but de sauver le maximum de victimes. De même, nous avons chacun une quantité limitée de temps et d’argent, et nous ne pouvons pas aider toutes les victimes de souffrances dans le monde. La meilleure chose à faire est alors de se concentrer sur les actions qui aideront le plus possible, celles qui auront le plus grand impact par euro donné ou heure investie.
Empathie Globale
Prendre en considération toute vie consciente, sans exclusion liée à l’appartenance à un groupe donné, qu’il soit fondé sur la nationalité, l’ethnie, la croyance ou l’espèce..
Dans un des textes majeurs de la philosophie morale contemporaine, Famine, Affluence and Morality[1], Peter Singer nous invite à étendre notre cercle d’empathie au-delà de notre propre pays et à reconnaître qu’une vie vaut la même chose, qu’elle soit vécue dans un pays développé ou un pays en développement. Nous souhaitons aider ceux auxquels il est possible d’apporter le plus grand bénéfice, et s’il s’agit d’habitants des pays en développement au lieu de nos compatriotes, c’est cela qu’il faut préférer. La plupart des personnes engagées dans l’altruisme efficace étendent ce raisonnement jusqu’à son aboutissement logique, qui est de prendre en considération les vies non-humaines ainsi que les vies futures de ceux qui ne sont pas encore nés. Certains se concentrent donc sur la souffrance des animaux d’élevage ou tentent d’améliorer la trajectoire future de l’humanité à très long terme.
Ouverture d'esprit et "agnosticisme de cause"
Considérer toutes les causes et actions possibles, puis agir de la manière qui produit le plus grand impact positif.
Il est habituel de commencer par choisir une cause pour des raisons personnelles ou émotionnelles, puis de se demander quelle serait l’action la plus efficace au sein de cette cause. (“Je souhaite soutenir la recherche contre le cancer car mon père est mort d’une tumeur cérébrale. Quel est le meilleur organisme de recherche contre le cancer ?”) Mais dans l’altruisme efficace, le choix de la cause lui-même fait l’objet d’une recherche rationnelle, car les plus grandes différences d’efficacité se trouvent entre différentes causes et non au sein d’une cause. Il s’agit donc de partir d’une position “agnostique à la cause” afin de pouvoir choisir la plus efficace parmi toutes les causes possibles, et de pouvoir changer de cause en réaction à de nouvelles informations.
Se concentrer sur l'action la plus efficace
Le choix optimal est probablement 10 ou 100 fois supérieur à la moyenne.
La taille chez les humains suit une distribution normale : les plus grands humains ont une taille au plus 60% supérieure à la moyenne. Par contre, le classement de popularité des sites web suit une loi de distribution très asymétrique (loi de puissance) : Google, le site le plus populaire, reçoit des milliards de visiteurs, alors que la vaste majorité des sites sont très peu visionnés. Certains éléments de preuve suggèrent que les actions altruistes suivent, comme la popularité des sites web, une distribution très asymétrique. En utilisant la base de données DCP2, le philosophe Toby Ord a montré que dans le domaine de la santé, le rapport coût-efficacité de différentes interventions suit une distribution extrême : l’intervention la plus efficace produit 15 000 fois plus de bénéfice que la moins efficace, et 60 fois plus que l’intervention médiane[2]. Au-delà de la base DCP2, les interventions de santé les plus efficaces sont particulièrement exceptionnelles : l’éradication de la variole en 1979 a prévenu plus de 100 millions de morts, pour un coût de 400 millions de dollars.
Ainsi, il apparaît probable que la meilleure action possible soit non pas 30% plus efficace ou 3 fois plus efficace, mais bien 10, 100 ou même 1000 fois plus efficace que la moyenne. Il est donc essentiel de concentrer nos ressources non pas seulement sur une action très efficace, mais sur celle qui est la plus efficace. Cela ne veut pas dire que tous ceux qui agissent selon ce principe doivent forcément travailler au service de la même cause. Il existe bien sûr des incertitudes considérables et des différences de valeurs, qui amènent différentes personnes à choisir des projets différents.
Privilégier les causes indûment négligées par d'autres
Pour déterminer l’impact d’une action, il faut appliquer un raisonnement à la marge : quel est l’effet supplémentaire de l’effort que j’apporte ? Il ne suffit pas d’observer l’effet moyen d’une action, il faut considérer son effet marginal. Imaginez que le grenier d’un village ne prenne feu. Les villageois ont le temps de sauver des flammes quelques réserves de nourriture avant que le feu n’engloutisse tout le bâtiment. Le plus important est de sauver le blé qui permettra de survivre l’hiver. Pourtant, si tous les autres villageois se concentrent sur les sacs de blé, ils réussiront à en sortir assez. Plutôt que de prendre encore plus de blé, votre meilleure action altruiste serait de sortir le sac de sel. Dans cet exemple, le sel a plus de valeur à la marge, malgré le fait qu’en moyenne le blé soit essentiel à la survie. De même, si l’on investit dans une cause négligée, le bénéfice marginal de chaque action sera supérieur, car les meilleures opportunités d’aider les autres n’auront pas encore été exploitées. Au contraire, il sera plus difficile d’avoir un grand impact dans une cause qui reçoit déjà beaucoup de ressources. Par exemple, apporter des vaccinations de base à ceux qui en ont besoin est extrêmement efficace : de nombreux cas de maladies graves peuvent être évités à faible coût. Mais soutenir ces vaccinations n’est généralement pas conseillé pour un donateur individuel, car les besoins les plus essentiels sont déjà couverts par les gouvernements ou les grandes fondations.[3] Si par contre une cause est négligée, cela peut donc constituer un indice en sa faveur.
Prendre en compte ce qui adviendrait si vous n'agissiez pas
Il ne suffit pas de considérer les effets directs de votre action, il faut prendre en compte son effet contra-factuel, c’est à dire la différence entre les conséquences réalisées suite à votre action et les conséquences qui seraient advenues si vous n’aviez pas agi. Imaginez que quelqu’un subisse un arrêt cardiaque devant vous. Vous venez de recevoir un entraînement de secourisme, et vous avez tant de zèle à aider que vous poussez de côté le médecin qui s’apprêtait à s’occuper de la victime. Vous parvenez à réanimer la victime, mais vous n’avez pas pour autant sauvé sa vie. Si vous n’étiez pas intervenu, le médecin l’aurait fait. Votre action était donc remplaçable, elle n’a pas eu d’impact contra-factuel. Ce raisonnement est essentiel pour évaluer rigoureusement nos actions altruistes : par exemple, devenir enseignant bénévolement dans une école d’un pays en développement pourrait avoir un impact négatif au lieu de positif, si le bénévole prenait la place d’un enseignant local expérimenté qui aurait fait un meilleur travail.
Mettre en balance la probabilité de succès avec la taille du bénéfice
La plupart de nos actions n’apportent pas un bénéfice garanti, mais augmentent la probabilité qu’un certain bénéfice advienne. Par exemple, militer contre les conditions de l’élevage intensif n’a aucune garantie de modifier le comportement des éleveurs ou d’inciter un gouvernement à légiférer, mais rend ces éventualités plus probables. Il est tout aussi fallacieux de choisir des objectifs très importants sans penser à la probabilité de les atteindre, que de rejeter toutes les actions à faible probabilité de succès sans prendre en compte la taille de ce succès potentiel. Il s’agit plutôt d’estimer l’espérance mathématique de notre action, en multipliant la probabilité des succès par la valeur du succès. On peut donc être amené à soutenir des actions qui garantissent un succès modeste, comme un don à une ONG distribuant des moustiquaires, ou des actions qui ont une faible probabilité de produire des bénéfices exceptionnels, telles que la recherche scientifique ou l’action politique.
Nos hypothèses : quelques exemples de causes efficaces
Appliquer ces principes de manière rigoureuse et pragmatique n’a rien d’automatique ni de simple. C’est pour cela que l’altruisme efficace est indissociable d’une réflexion critique sans cesse renouvelée. Cependant, les causes suivantes apparaissent prometteuses :
• Lutter contre les problèmes de santé de base dans les pays en développement.[4] Environ 10 millions de personnes meurent chaque année à cause de maladies dont la prévention est simple, telle que la diarrhée, le paludisme, ou la tuberculose. Ces maladies ne tuent pratiquement personne dans les pays riches. Il est clairement possible d'améliorer significativement la santé dans les pays en développement, avec des interventions à faible coût dont l'efficacité est prouvée. Par exemple, distribuer des moustiquaires imprégnées d’insecticide en Afrique Sub-Saharienne permet d'empêcher un enfant de mourir du paludisme pour un coût de moins de 3 000 [5]. Améliorer la santé crée aussi des opportunités économiques[6]: la maladie ralentit le développement des enfants, augmente fortement l'absentéisme scolaire, et les empêche de réaliser leur potentiel. • Aider les animaux victimes de l'élevage.[7] Chaque année environ 100 milliards d'animaux sont élevés pour que des humains les mangent : 15 par personne en moyenne[8]. L'écrasante majorité des experts en neurologie animale estiment que les cochons, vaches et poules sont capables de ressentir la souffrance d'une manière similaire aux humains. Malheureusement, ces animaux sont en grande majorité élevés dans des conditions de forte souffrance. Dans les élevages industriels, les poules ont le bec coupé sans anesthésie et sont confinées à de minuscules cages. Les truies mettent bas dans des cages où elles ne peuvent effectuer aucun mouvement, et en France les cochons sont castrés à vif. Parmi les personnes qui travaillent sur cette cause, certains tentent de développer des alternatives aux produits animaux, de convaincre d'autres de devenir végétariens ou véganes, ou d'influencer la réglementation de l’élevage et de l’abattage. • Contrôler les risques d'échelle mondiale.[9] De nombreux événements pourraient être catastrophiques pour la terre entière : une guerre mondiale, une nouvelle pandémie, le changement climatique, ou des nouvelles technologies à haut risque. Malheureusement, ces risques sont le problème de tous à la fois et la responsabilité de personne en particulier, et sont donc souvent négligés. Pourtant, une telle catastrophe pourrait non seulement causer beaucoup de souffrance, mais aussi réduire le potentiel de l'humanité à long terme. Par ailleurs, certains biais cognitifs nous empêchent d'estimer correctement les risques lorsqu'il s'agit d’événements très rares. Souvent, les électeurs sont très inquiets au sujet de risques peu importants, et n'accordent aucune attention à des risques que les experts considèrent comme extrêmement inquiétants. Agir L’altruisme efficace est intellectuellement ambitieux, mais ne fait pas de la rigueur académique son but final. Si nous prenons ces questions au sérieux, c’est car nos actions en dépendent. Les méthodes de l’altruisme efficace peuvent paraître abstraites, mais les vies des personnes que nous aidons sont pleines de souffrances et de joies réelles. Les personnes engagées dans l’altruisme efficace mettent en pratique leurs projets avec le même enthousiasme qui les pousse à analyser leur plans avec précision. Un grand nombre d’entre eux donnent 10% de leur revenu aux causes qu’ils soutiennent. D’autres ont changé leur carrière en profondeur[10]. Pour en savoir plus Le livre Doing Good Better[11] de William MacAskill apporte un traitement plus approfondi des idées centrales de l’altruisme efficace. Notes [4] Pour en savoir plus: GiveWell tente d’identifier les ONG qui aident les habitants des pays en développement le plus efficacement. Les rapports de GiveWell sont accessibles au public et se basent sur plusieurs décennies de recherches rigoureuses dans les domaines de l’économie et de la santé publique. [7] Pour en savoir plus: Animal Charity Evaluators tente d’identifier les opportunités de dons les plus efficaces pour aider les animaux et étudie certaines questions empiriques et théoriques cruciales pour la cause animale. La fondation Open Philanthropy Project soutient financièrement des projets pour la réduction de souffrance des animaux d’élevage, et donne un accès public aux résultats de ses recherches. [8] 50 milliards d’animaux terrestres (Organisation des Nations Unies pour l’alimentation et l’agriculture, archive) et environ 80 milliards d’animaux issus de l’aquaculture (A. Mood et P. Brooke, 2012, archive). [9] Pour en savoir plus: le Future of Humanity Institute à l’Université d’Oxford étudie les questions considérées comme les plus déterminantes pour la trajectoire future de l’humanité. L’article Existential Risk Prevention as Global Priority (Nick Bostrom 2012, Global Policy, archive) est un bon point de départ. [10] 80000hours.org - voir en bas de page la section “people we’ve helped”. Oxford Uehiro Prize in Practical Ethics, “How should vegetarians actually live?" July 4, 2016 In 2016, I was the joint winner in the Undergraduate Category of the Oxford Uehiro Prize in Practical Ethics. Read my essay here, or below. Ethical vegetarians abstain from eating animal flesh because they care about the harm done to farmed animals. More precisely, they believe that farmed animals have lives so bad they are not worth living, so that it is better for them not to come into existence. Vegetarians reduce the demand for meat, so that farmers will breed fewer animals, preventing the existence of additional animals. If ethical vegetarians believed animals have lives that are unpleasant but still better than non-existence, they would focus on reducing harm to these animals without reducing their numbers, for instance by supporting humane slaughter or buying meat from free-range cows. I will argue that if vegetarians were to apply this principle consistently, wild animal suffering would dominate their concerns, and may lead them to be stringent anti-environmentalists. If animals like free-range cows have lives that are not worth living, almost all wild animals could plausibly be thought to also have lives that are worse than non-existence. Nature is often romanticised as a well-balanced idyll, so this may seem counter-intuitive. But extreme forms of suffering like starvation, dehydration, or being eaten alive by a predator are much more common in wild animals than farm animals. Crocodiles and hyenas disembowel their prey before killing them[1]. In birds, diseases like avian salmonellosis produce excruciating symptoms in the final days of life, such as depression, shivering, loss of appetite, and just before death, blindness, incoordination, staggering, tremor and convulsions.[2] While a farmed animal like a free-range cow has to endure some confinement and a premature and potentially painful death (stunning sometimes fails), a wild animal may suffer comparable experiences, such as surviving a cold winter or having to fear predators, while additionally undergoing the aforementioned extreme suffering[3]. Wild animals do experience significant pleasure, for instance when they eat, play or have sex, or engage in other normal physical activity. One reason to suspect that this pleasure is outweighed by suffering is that most species use the reproductive strategy of r-selection, which means that the overwhelming majority of their offspring starve or are eaten shortly after birth and only very few reach reproductive age.[4],[5] For instance, ‘in her lifetime a lioness might have 20 cubs; a pigeon, 150 chicks; a mouse, 1000 kits’,[6] the vast majority of which will die before they could have had many pleasurable experiences. Overall, it seems plausible that wild animals have worse lives than, say, free-range cows. If vegetarians think the latter are better off not existing, they must believe the same thing about wild animals. A second important empirical fact is that wild animals far outnumber farmed animals. Using figures from the FAO, Tomasik estimates that the global livestock population is 24 billion (including 17 billion chicken)[7]. I restrict my count of wild animals to those at least as complex as chicken or small fish, which vegetarians clearly believe do have moral weight. Using studies of animal density in different biomes, Tomasik estimates conservatively that there are at least 6*1010 land birds, 1011 land mammals, and 1013 fish. Animals in each of these categories alone are several times more numerous than livestock. If wild animals’ well-being is negative and the above numbers are remotely correct, the scale of wild animal suffering is vast. As Richard Dawkins writes, ‘During the minute it takes me to compose this sentence, thousands of animals are being eaten alive; others are running for their lives, whimpering with fear; others are being slowly devoured from within by rasping parasites; thousands of all kinds are dying of starvation, thirst and disease.’[8] If they accept the premises so far, consistent vegetarians should focus on preventing the existence of as many wild animals as possible, since even a small reduction in the global number of wild animals would outweigh the impact of ending all livestock production. For example, they could reduce animal populations by sterilising them, or by destroying highly dense animal habitats such as rainforests. This would place them directly at odds with environmentalists who try to preserve nature from human intervention. It may even be the case that vegetarians should react to this argument by eating more meat, since feeding the livestock requires more surface area for agriculture, and fields contain far fewer wild animals per square kilometre than other biomes such as forests. An intuitive response to wild animal suffering can be that cycles of predation and starvation are natural, and therefore they must be neutral morally. But what is natural is not necessarily what is good, for instance, humans will routinely use technology to remove diseases which are natural. It is important to emphasize that the claim ‘wild animal suffering is bad’ does not imply a guilt claim of the form ‘predators are morally guilty’. A lion’s instinct is indeed natural and does not deserve our moral condemnation. However, we can avoid much confusion if we remember to keep separate the concepts of guilt of an agent and wrongness of an action. It is perfectly possible to claim that X is harmful and should be prevented while also holding that the direct cause of X is not a moral agent. The fact that we are so used to thinking about cases of human behaviour, where guilt and wrongness are largely aligned, may partly explain why arguments about wild animal suffering seem counter-intuitive. Underlying some of these principled arguments is the intuition that harmful acts, like killing livestock, are worse than harmful omissions, like failing to avert wild animal suffering. I cannot begin to give a full treatment to the act/omission debate here, but one thought experiment suggests harmful omissions matter at least somewhat. Imagine you see a fire spreading in a forest and, while walking away from the fire, you see an injured fawn: a broken leg prevents her from fleeing. You carry a rifle and could instantly kill the fawn at no cost to yourself, preventing her from the extreme suffering of being burned alive. In this situation, for vegetarians who care about harm to animals, it is clear that it would be immoral to omit to act and allow wild animal suffering to happen. So the general principle ‘allowing wild animals to suffer is morally neutral’ cannot hold. A second set of counter-arguments are empirical: they concede that consistent vegetarians are morally obliged to reduce wild animal suffering, but attack various empirical claims made above. It may be objected that we cannot reduce the number of animals by sterilising them, because as soon as fewer animals are born, more resources (like food and territory) become available, which increases the evolutionary payoff of producing more animals. If we sterilise some deer, there will at first be fewer fawns, so there will be more nuts and berries available, which allows other deer (or other species) to have more offspring, until we are back to the original equilibrium. The existence of such evolutionary pressures towards an equilibrium population seems plausible, but it remains an unsolved empirical question. It may be the case that the population takes several years to reach its equilibrium again, in which case much animal suffering would be averted in the meantime. Regardless, this is only an objection against one particular method for reducing wild animal numbers, and it only tells us that sterilisation would be ineffective, not harmful. If we reject sterilisation on these grounds, habitat destruction, for instance, evidently does reduce animal numbers for the long run. A frequent objection against intervening in nature is that we are uncertain about the consequences: for instance, culling predators might cause an ecological catastrophe. While our uncertainty is a good reason to do more research in order to reduce it, it is not in principle an argument for inaction. If we are so uncertain, inaction towards predation could also be causing vastly more suffering than we currently estimate. In order to make sure our aversion to intervene is not caused by status quo bias, we can use the reversal test,[9] an elegant instance of which is provided by the reintroduction of wolves in Scotland, where they had been hunted to extinction in the 1700s.[10] If we are more worried about the uncertain effects of reintroducing wolves than we are about the uncertainty of inaction towards wolf predation, this may be due to status quo bias. Possibly the strongest counter-argument is that we are extremely uncertain about whether wild animals’ lives are worth living. How much pain or pleasure animals feel in response to certain stimuli is dependent on facts about their neurology which is not well understood. While we may make some reasonable extrapolation from our human experience (being eaten alive is very painful), animal subjective experience may differ significantly. While animals might experience hedonic adaptation[11] to their circumstances, encounters with predators produce lasting psychological damage similar to post-traumatic stress disorder in humans.[12] There is some evidence that domesticated animals are less stressed,[13] but measures of stress hormones may not coincide with animals’ revealed preferences[14]. Clearly, I do not pretend to have solved this difficult empirical question. However I note that these considerations should also make us uncertain about the subjective well-being of farmed animals; and I have already offered reasons why wild animals plausibly have worse lives than free-range animals. Even if vegetarians still reject this argument, and believe that wild animals’ lives are better than the lives of farm animals, to the extent that they are worth living, this does not imply they should do nothing. They should not reduce animal numbers, but they should still reduce the suffering of existing animals. Because there are so many animals and the suffering they undergo can be so extreme, this consideration would likely still dominate concern about farmed animals. One could vaccinate animals against diseases: rabies has already been eliminated from foxes for human benefit[15]. After elephants’ teeth wear out, they are no longer able to chew food and eventually collapse from hunger, after which they may be eaten alive by scavengers and predators. Fitting elephants with artificial dentures, which has already been done on captive animals, would significantly increase their healthspan[16]. Or one could cull predator populations by allowing more of them to be hunted. A possible concern with this type of intervention may be that any advantage given to a particular individual by reducing their suffering would increase the suffering of others. For instance, if elephants can eat for longer, more other herbivores will starve; or if we kill predators, their prey will proliferate and their competitors will starve. If we think that ecosystems lie on such a razor-sharp evolutionary equilibrium where all animals are strongly competing for every piece of resource, this objection is plausible. But crucially, if we accept this, then it is becomes plausible that wild animals actually do have lives that are not worth living: if evolution produces so many animals that each can just barely survive, it is likely that they endure much suffering and little pleasure. So it seems like we must either accept that some interventions can reduce extreme wild animal suffering, or concede that animals’ lives are plausibly not worth living. Some may choose to treat this outlandish conclusion as a reductio against vegetarianism (either against the idea that farm animals matter morally or against the belief that we should prevent them from coming into existence). Perhaps vegetarians who still reject the conclusion should increase their confidence that buying free-range meat is a good thing. For those who accept it, the question of how most effectively to reduce wild animal suffering is left open. As I have repeatedly emphasised, we are still very ignorant about many relevant empirical questions, so immediate large-scale intervention will not be very effective. In addition, intervention may have significant backlash effects and reduce sympathy for the anti-speciesist message. The best immediate action is probably to produce more research on wild animal suffering, in order to make future action more likely to be effective. [1] Dawrst, Alan. "The predominance of wild-animal suffering over happiness: An open problem." Essays on Reducing Suffering (2009): 255-85. [2] Michigan Department of Natural Resources. "Salmonellosis." Quoted in Tomasik, “The Importance of Wild Animal Suffering” [3] Tomasik, Brian. “Intention-Based Moral Reactions Distort Intuitions about Wild Animals.” Essays on Reducing Suffering (2013) [4] Horta, Oscar. "Debunking the idyllic view of natural processes: population dynamics and suffering in the wild." Télos 17.1 (2010): 73-88. [5] Ng, Yew-Kwang. "Towards welfare biology: Evolutionary economics of animal consciousness and suffering." Biology and Philosophy 10.3 (1995): 255-285. [6] Fred, Hapgood. Why males exist: an inquiry into the evolution of sex. 1979. Quoted in Tomasik, “The Importance of Wild Animal Suffering”. [7] Tomasik, Brian. "How Many Wild Animals Are There?." Essays on Reducing Suffering (2014). [8] Dawkins, Richard. River out of Eden: A Darwinian view of life. Basic Books, 1996. [9] Bostrom, Nick, and Toby Ord. "The Reversal Test: Eliminating Status Quo Bias in Applied Ethics*." Ethics 116.4 (2006): 656-679. [10] "Wild Wolves 'good for Ecosystems'" BBC News. BBC, 31 Jan. 2007. Web. 25 Jan. 2016. [11] Frederick, Shane, and George Loewenstein. "Hedonic adaptation." (1999). [12] Zoladz, Phillip R. An ethologically relevant animal model of post-traumatic stress disorder: Physiological, pharmacological and behavioral sequelae in rats exposed to predator stress and social instability. Diss. University of South Florida, 2008. [13] Wilcox, Chritie. "Bambi or Bessie: Are Wild Animals Happier?" Scientific American Blog. N.p., 21 Apr. 2011. Web. 20 Jan. 2016. [14] Dawkins, M. S. "Using behaviour to assess animal welfare." Animal welfare-potters bar then Wheathampstead- 13 (2004): S3-S8. [15] Freuling, Conrad M., et al. "The elimination of fox rabies from Europe: determinants of success and lessons for the future." Philosophical Transactions of the Royal Society B: Biological Sciences 368.1623 (2013): 20120142. [16] Pearce, David. "A Welfare State for Elephants?." RELATIONS 3.2. November 2015-Wild Animal Suffering and Intervention in Nature: Part II (2015): 153. A Path Appears Book Review July 1, 2015 This my book review of Nicholas Kristof and Sheryl WuDunn’s ”A Path Appears”. (Also available on scribd here). In 2015, the review won the Sciences Po - Books prize, a book review competition organized by my University and the magazine Books. It was published in French translation in the June 2015 edition of Books, of which I’ve scanned the relevant pages. In May 2013 TIME magazine’s cover called millennials –those born between 1980 and 2000– the “Me Me Me Generation”. It featured a young woman taking a selfie, the emblematic act of a generation of smartphone-toting, selfish narcissists. Yet statistics such as those by the Pew Research Center describe an empathetic age group that votes less often, but is more likely to do volunteer work than their parents were. Most likely, Millennials are simply doing things differently, both shaping and reacting to the ways altruism and citizenship are being reinvented. That, at least, is the hopeful message captured in the title of Nicholas Kristof and Sheryl WuDunn’s new book A Path Appears. A generation ago, they say, “’giving back’ was what we did in December, hunched over a checkbook and relying on guesswork. In recent years, advances in neuroscience and economics –and a flowering of carefully monitored experiments- have given us much greater insight into what works to create opportunity worldwide, and much greater prospects for personal satisfaction from giving”. The sunlit path towards creating a better lives for others, they say, appears before us clearer than ever. And they want you to take it: the book is sold as a “galvanizing narrative about making a difference here and abroad—a road map to becoming the most effective global citizens we can be.” The first chapter of the book is representative of its approach – and of its paradoxes. We meet Rachel Beckwith, an American girl who decided to celebrate her ninth birthday by asking friends and relatives to donate to charity:water, an organization that drills wells in impoverished villages around the world and lets people set up their own fundraisers online. Rachel’s target sum was not reached. Six weeks later, Rachel tragically died in a highway accident, but the story of her generosity rippled through social media, and her page eventually raised over a million dollars. Cut to Lester Strong - who left his job as a news executive to run Experience Corps, an organization bringing in older Americans to tutor students in public schools across the country. Next we learn about Dr. Gary Slutkin, whose Cure Violence program combats urban violence in the United States by applying methods of epidemiology. After these uplifting stories, the second half of the chapter focuses on numbers and scientific studies designed to show how much more we know about creating opportunity; and how much more efficiently, therefore, we who live in privilege can employ our wealth and skills for causes larger than ourselves. Esther Duflo, an MIT economist, has pioneered the use of randomized controlled trials, which apply the rigorous methods of pharmaceutic drug testing to policies designed to help the world’s poorest people. She found that for 50 cents a year, you can deworm a child in Kenya, increasing their school attendance and cognitive development. Once an adult, that child will earn 20% more compared to those in a control group. So although two thirds of Americans donate an average of1000 to charity each year, they rarely give money away as intelligently as they make it. As Esther Duflo says, “Worms have a little bit of a problem grabbing the headlines. They are not beautiful and don't kill anybody”.
This book, like its first chapter, constantly meshes hard evidence with inspiring anecdotes. As regular New York Times columnists and Pulitzer prize winners, the authors have clearly understood that if they want to produce a compelling book they must combine storytelling with rational argument. In fact, as they keep piling up story after story of activists saving the world, you may begin to see the strings. But the real challenge of this 656-page tome is to coherently bridge the gap between the rational and the emotional, the Esther Duflos and the Rachel Beckwiths. After all, these motivations for altruism are quite different, and they may point to quite irreconcilable courses of action. Can Kristof and WuDunn successfully appeal to both the calculating utilitarian and the impulsive altruist?
As it turns out, for governments in the rich world, creating opportunity is also a great investment. A black man in America is more likely to spend time in prison than college. If that statistic can be turned around, the taxpayer benefits, too. In one of the best chapters of the book, entitled “The land of opportunity – if you catch them early”, the authors argue that the best way to make the lottery of birth less unfair is to intervene in the earliest stage of life. Actually, it’s better to start before that: during pregnancy, the fetal brain is being shaped by the uterine environment in ways that will affect the child for the rest of his or her life. A simple program to encourage women to stop smoking during pregnancy costs about $30 per woman counselled. Randomized trials have shown that each of these$30 save about $800 in averted neonatal costs. After birth, returns to society quickly decrease, but it’s still not too late: pre-kindergarten nursing visits for low-income unmarried mothers produce$5.7 in state and federal government savings for each dollar invested. James Zimmermann, CEO of Macy’s and an advocate for this kind of intervention, puts it succinctly: “investing in early childhood achieves the best return on investment for our country. Currently more than 90% of our education dollars are spent after age five, yet 85% of a child’s core brain structure is developed before age five.” There are three words in that quote you may have glossed over: for our country. Yet they represent one of the main paradoxes of this book. The authors keep talking about effective giving, but they miss the biggest effectiveness gap of all: between poor and rich countries. If you read this book trying to decide how best to make a difference, forget about nurse visits: 50-cent-a-year deworming in Africa beats anything you can do in the rich world. The authors repeatedly show they are aware of this discrepancy, yet they brazenly ignore its implications. It may feel good to say that poverty at home and abroad are “too important to be pitted against each other”, but upon reflection that turns out to be as fallacious as claiming that college scholarships and nurse visitation programs cannot be compared. If this book bridges the gap between rational analysis and gut feeling, it is only at a huge cost in consistency. As a result, A Path Appears lacks the moral force of Peter Singer’s resolutely utilitarian manifesto for helping the global poor, The Life You Can Save.
One of the most interesting characters of this book is Dan Pallotta, an ambitious consultant who in 1994 launched Pallotta TeamWorks, a company which organized bike rides and other events to raise money for AIDS and breast cancer prevention. Pallotta knew that the reason his events were successful was that they were fun, cool, and well-organized. He poured money into marketing and logistics, saying “We advertised our events the way Apple advertises iPads.” He also paid himself $394 000 in 2001. All this meant that only about 60% of the money raised went to the charities. Increasingly criticized for this high overhead figure and his somewhat glitzy approach to charity, Pallotta was dropped by his sponsor in 2002. That sponsor tried to run the events themselves, keeping costs down. But though overhead was lower, the amounts raised for charities dropped 70% in one year, from$6 million under Pallota’s management to only $1.6 million. People started to realize that what had been called overhead was actually essential to the fundraising effort. In an inspiring TED talk, Pallotta argues that “the way we think about charity is dead wrong”, and urges donors to ignore the “depressing label of overhead” and instead focus on what charities are getting done per dollar. Meanwhile, established charities have quickly realized that they can exploit our emotional responses through advertising: in 2002, UNICEF experimented with putting a nickel in its mailings, visible through a glassine window on the envelope. This triggered people’s reciprocity instinct, and the response rate doubled. Sounds like manipulation? In the for-profit world, it’s called marketing. If we think it’s okay for a multinational to use those tactics to sell hamburgers, why do we frown upon charities doing it to ‘sell’ education for Ethiopian girls? The last third of the book is dedicated to showing that far from being a Gandhi-style sacrifice, altruism can be a source of great fulfillment. The MRI scan, the grail of modern brain science, has been used in countless experiments to show that giving money to charities activates the same pleasure centers of the brain as eating fine food or having sex. In fact, things we think will make us happy, like winning the lottery, have almost no long-term impact; but helping others has been shown to increase long-term life satisfaction and health. While the studies cited are rather solid, this optimism hides the many ways in which our altruistic instincts actually work against us. The American charity Smile Train, which offers cleft palate surgeries to children in the developing world, uses the photo of a Russian boy in their mailings: randomized trials showed that the mostly white donor base responded best when shown a picture of someone with the same skin color. Spontaneously, we help those who resemble us. We also like identifiable victims: people are actually more willing to donate$300 000 to save one child than the same amount to save eight children. Perhaps we should not rely all too much on our instincts. Very often, actions that make you feel good crowd out actions that do the most good.
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http://mathoverflow.net/questions/30020/about-tarskis-axioms-a-and-a-and-around-1
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# About Tarski's axioms a and A' and around (1)
1-In his article written in German "Über unerreichbare Kardinalzahlen" (On inaccessible cardinals), inside Fund. Math. 1938 (pages 68-89), Alfred Tarski states his axioms A and A' as follows. Axiom A: "For every set x, there exists a set y satisfying the four following conditions:
• A1: x is a member element of y;
• A2: If z is a member element of y and t is included inside z, then t is a member element of y;
• A3: If z is a member element of y and t is the set having as member elements exactly all sets u included inside z, then t is a member element of y;
• A4: If z is included inside y and if the sets z and y are equipotent, then z is a member element of y."
Axiom A':"For every set x, there exists a set y satisfying the four following conditions:
• A'1: x is included inside y;
• A'2: If z is a member element of y and t is a member element of z, then t is a member element of y;
• A'3: If z is a member element of y, there exists a set w that is a member element of y such that every set t that is included inside z is a member element of w;
• A'4: If z is included inside y and if no set included inside z is equipotent with y, then z is a member element of y."
Tarski asserts, without giving a proof, that axioms A and A' are equivalent.
QUESTION 1: Does anyone know about an explicit proof of the equivalance of A and A' ?
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Why was this question downvoted so much earlier? And why did people who downvoted it not leave any comment? – Willie Wong Jun 30 '10 at 11:39
Presumably because it was poorly formatted and because the author posted 4 or 5 questions on the same subject at once. – Ben Webster Jun 30 '10 at 12:37
In fact, all five messages I wrote are linked (and ordered) and are intended to make clarification around the "axiomatic power" of Tarski's axioms A and A', but I could not make a unique message because it was too long, so I divided it and asked one question inside each message. And YES, being a beginner with Mathoverflow, maybe my messages can be considered as poorly formatted ! Gérard LANG – Gérard Lang Jun 30 '10 at 12:44
First, I note that you appear to be missing a not in A4, and you should say that "if $z$ and $y$ are not equipollant", for otherwise we could take $z=y$ and thereby deduce $y\in y$, contrary to the Foundation axiom.
With this correction, both your axioms are equivalent in ZFC to the assertion that there is a proper class of inaccessible cardinals.
For the one direction, if there are such cardinals, then for any set $x$ we may find an inaccessible cardinal $\kappa$ such that $x\in V_\kappa$, and take $y=V_\kappa=H_\kappa$ to fulfill either $A$ or $A'$, which is easily verified.
Conversely, assume axiom A. Let $x=\alpha$ be an ordinal and let $y$ arise as in axiom A. Let $\kappa=|y|$. As every subset of $\alpha$ is in $y$, it follows that $\alpha\lt\kappa$. If $\beta\lt\kappa$, then there is subset $z\subset y$ of size $\beta$, and this is an element of $y$ by A4. We also know $P(z)\subset y$ and $P(z)\in Y$, so $P(P(z))\subset y$, so $2^\beta\lt\kappa$. Thus, $\kappa$ is a strong limit. For regularity, suppose that $\kappa$ singular with cofinality $\gamma\lt\kappa$. Thus, $y$ is the union of $\gamma$ many subsets, each of size less than $\kappa$. These subsets are elements of $y$, and all their subsets are also in $y$. But every subset of $y$ is determined by a similar $\gamma$ sequence of elements of $y$, and so $y$ will have $2^\kappa$ many elements, a contradiction. So $\kappa$ is an inaccessible cardinal above $\alpha$, as desired.
For the other converse direction, assume axiom $A'$. Consider $x=\alpha+1$, and get $y$ as in $A'$, and again let $\kappa=|y|$. I claim that $\kappa\subset y$, for otherwise the least ordinal $\beta$ not in $y$ would be less than $\kappa$ in size and have all its subsets size less than $\kappa$, and hence in $y$ by $A4'$. Thus, $\kappa\subset y$. Now, for any $\gamma\lt\kappa$, every subset of $\gamma$ is in $y$ and there is an element of $y$ with at least $2^\gamma$ many subsets, all in $y$, so $2^\gamma\lt\kappa$. So $\kappa$ is a strong limit. Regularity follows as before, and so $\kappa$ is an inaccessible cardinal above $\alpha$.
Thus, since the axioms are both equivalent to the assertion that there is a proper class of inaccessible cardinals, they are also equivalent to each other.
Do you have some historical reason to study Tarski's treatment of inaccessibility? If not, I think you might find the contemporary accounts of large cardinals to be more appealing. You might look at Kanamori's book, The Higher Infinite.
If you wanted the equivalence in ZF rather than ZFC, or in ZF-Foundation, then I wouuld have to think more carefully about it, but I will mention that this issue seems to be remarked on in Solovay's letter mentioned in your previous question. In particular, without AC there are competing inequivalent notions of inaccessibility.
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Dear Mr Hamkins, Thankyou very much for correcting my question, and giving a neat answer under ZFC. And naturally I would like to know what happens under ZF only (I suppose that because A proves choice, a remains equivalent with a proper class of inaccessibles; but if A' does not prove choice under ZF, then the equivalence with A must be questionned, in view of the competing inequivalent definitions of inaccessibility ?). – Gérard Lang Jul 5 '10 at 14:03
In fact, my primary interest is with the remarkable axiomatic strength of the "Tarski-Grothendieck Set Theory" as developped inside Metamath or Mizar, even knowing that "a proper class of inaccessibles" is a rather mild assertion is the "Large Cardinals Scala" presented in the beautiful Kanamori reference book. It is known that, starting with "ZFC + A", and adding the Pair Axiom, you can delete the Power-Set, Infinity and Choice axioms. So, in relation with assertion of Tarski on some variants of A and A', i am wondering if Pair and Union could not also be deleted. – Gérard Lang Jul 5 '10 at 14:48
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https://math.stackexchange.com/questions/1083078/difficult-functional-equation-problem-non-standard-type
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Difficult Functional Equation Problem, Non-Standard Type
Find all functions, $f:\mathbb{N} \to \mathbb{N}$, for which $f(1) = 1, f(2n) < 6f(n)$, and
$$3f(n)f(2n+1) = f(2n)(3f(n)+1).$$
My first approach is to try to play around and set values equal to 0, to test for even-ness, that kind of thing, but this gets me absolutely nowhere. I've looked for help on problem solving forums and it hasn't really got anywhere, so I'm thinking that maybe this is a problem of another type, not necessarily hard, but covering topics in functional equations that I have not yet covered.
Was wondering if someone could give the solution and thought-process behind steps, as this is really driving me nuts.
Thanks.
For $n=1$, $3 f(3) = 4 f(2)$ and $f(2) < 6$. Since $f(2)$ must be divisible by $3$, $f(2) = 3$ and $f(3) = 4$.
For $n=2$, $9 f(5) = 10 f(4)$ and $f(4) < 18$. Since $f(4)$ must be divisible by $9$, $f(4) = 9$ and $f(5) = 10$.
• Letting n = 1, wouldn't we get, $3f(1)2f(3) = f(2)(3f(1) + 1))$? How did you get 3f(3) = 4f(2), and make the claim that f(2) < 6? We get f(2) < 6f(1). – user164403 Dec 28 '14 at 4:59
• For $n=1$, it's $3 f(1) f(2\cdot 1 + 1) = f(2\cdot 1)(3 f(1)+1)$ and $f(1) = 1$ so it's $3 f(3) = 4 f(2)$. Yes, $f(2) < 6 f(1)$, but $f(1) = 1$. – Robert Israel Dec 28 '14 at 6:36
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https://video.ias.edu/2015-1016?page=3
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## Peaks, Exclusion, and BAO
Tobias Baldauf
September 24, 2015
The interpretation of low-redshift galaxy surveys is more complicated than the interpretation of CMB temperature anisotropies. First, the matter distribution evolves nonlinearly at low redshift, limiting the use of perturbative methods. Secondly, we observe galaxies, rather than the underlying matter field. Fortunately, considerable progress has been made in understanding the large-scale structure of galaxies. A key insight has been that galaxies form in bound structures called halos, whose statistics (e.g.
## Overview - AK
Andrey Kravtsov
September 25, 2015
The interpretation of low-redshift galaxy surveys is more complicated than the interpretation of CMB temperature anisotropies. First, the matter distribution evolves nonlinearly at low redshift, limiting the use of perturbative methods. Secondly, we observe galaxies, rather than the underlying matter field. Fortunately, considerable progress has been made in understanding the large-scale structure of galaxies. A key insight has been that galaxies form in bound structures called halos, whose statistics (e.g.
## Halo Assembly Bias on Galaxy Cluster Scales
Surhud More
September 25, 2015
The interpretation of low-redshift galaxy surveys is more complicated than the interpretation of CMB temperature anisotropies. First, the matter distribution evolves nonlinearly at low redshift, limiting the use of perturbative methods. Secondly, we observe galaxies, rather than the underlying matter field. Fortunately, considerable progress has been made in understanding the large-scale structure of galaxies. A key insight has been that galaxies form in bound structures called halos, whose statistics (e.g.
## Assembly Bias as a Challenge to Infering the Galaxy-Dark Matter Connection
Andrew Zentner
September 25, 2015
The interpretation of low-redshift galaxy surveys is more complicated than the interpretation of CMB temperature anisotropies. First, the matter distribution evolves nonlinearly at low redshift, limiting the use of perturbative methods. Secondly, we observe galaxies, rather than the underlying matter field. Fortunately, considerable progress has been made in understanding the large-scale structure of galaxies. A key insight has been that galaxies form in bound structures called halos, whose statistics (e.g.
## Quantitative Constraints on Assembly Bias: An Open-Source Approach with Halotools
Andrew Hearin
September 25, 2015
The interpretation of low-redshift galaxy surveys is more complicated than the interpretation of CMB temperature anisotropies. First, the matter distribution evolves nonlinearly at low redshift, limiting the use of perturbative methods. Secondly, we observe galaxies, rather than the underlying matter field. Fortunately, considerable progress has been made in understanding the large-scale structure of galaxies. A key insight has been that galaxies form in bound structures called halos, whose statistics (e.g.
## Emulating Non-Linear Clustering
Jeremy Tinker
September 25, 2015
The interpretation of low-redshift galaxy surveys is more complicated than the interpretation of CMB temperature anisotropies. First, the matter distribution evolves nonlinearly at low redshift, limiting the use of perturbative methods. Secondly, we observe galaxies, rather than the underlying matter field. Fortunately, considerable progress has been made in understanding the large-scale structure of galaxies. A key insight has been that galaxies form in bound structures called halos, whose statistics (e.g.
## Modelling the 1H Term
Frank van den Bosch
September 25, 2015
The interpretation of low-redshift galaxy surveys is more complicated than the interpretation of CMB temperature anisotropies. First, the matter distribution evolves nonlinearly at low redshift, limiting the use of perturbative methods. Secondly, we observe galaxies, rather than the underlying matter field. Fortunately, considerable progress has been made in understanding the large-scale structure of galaxies. A key insight has been that galaxies form in bound structures called halos, whose statistics (e.g.
## What is the Main Driver of Quenching?
Ying Zu
September 25, 2015
The interpretation of low-redshift galaxy surveys is more complicated than the interpretation of CMB temperature anisotropies. First, the matter distribution evolves nonlinearly at low redshift, limiting the use of perturbative methods. Secondly, we observe galaxies, rather than the underlying matter field. Fortunately, considerable progress has been made in understanding the large-scale structure of galaxies. A key insight has been that galaxies form in bound structures called halos, whose statistics (e.g.
## Overview - US
Uros Seljak
September 25, 2015
The interpretation of low-redshift galaxy surveys is more complicated than the interpretation of CMB temperature anisotropies. First, the matter distribution evolves nonlinearly at low redshift, limiting the use of perturbative methods. Secondly, we observe galaxies, rather than the underlying matter field. Fortunately, considerable progress has been made in understanding the large-scale structure of galaxies. A key insight has been that galaxies form in bound structures called halos, whose statistics (e.g.
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https://peswiki.com/powerpedia:petroleum
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# PesWiki.com
## PowerPedia:Petroleum
Lasted edited by Andrew Munsey, updated on June 14, 2016 at 9:43 pm.
• This page has been imported from the old peswiki website. This message will be removed once updated.
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|} Petroleum (from Greek petra – rock and elaion – oil or Latin oleum – oil ) or crude oil is a black, dark brown or greenish liquid found in porous rock formations in the earth. The American Petroleum Institute, in its Manual of Petroleum Measurement Standards (MPMS), defines it as "a substance, generally liquid, occurring naturally in the earth and composed mainly of mixtures of chemical compounds of carbon and hydrogen with or without other nonmetallic elements such as sulfur, oxygen, and nitrogen."
Petroleum is found in porous rock formations in the upper strata of some areas of the Earth's crust. It consists of a complex mixture of various hydrocarbons, largely of the alkane series, but may vary much in appearance and composition. Petroleum is used mostly, by volume, for producing fuel oil and petrol (gasoline), both important "primary energy" sources (IEA Key World Energy Statistics). Petroleum is also the raw material for many chemical products, including solvents, fertilizers, pesticides, and plastics. 88% of all petroleum extracted is processed as fuel the other 12% is converted into other materials such as plastic. Since petroleum is a non-renewable resource, many people are worried about peak oil and eventual depletion in the near future. Due to its continual demand and consequent value, oil has been dubbed black gold. The combining form of the word petroleum is petro-, as in petrodiesel (petroleum diesel).
#### History
Petroleum, in some form or other, is not a substance new in the world's history. More than four thousand years ago, according to Herodotus and confirmed by Diodorus Siculus, asphalt was employed in the construction of the walls and towers of Babylon. Great quantities of it were found on the banks of the river Issus, one of the tributaries of the Euphrates. Ancient Persian tablets indicate the medicinal and lighting uses of petroleum in the upper levels of their society. The first oil wells were drilled in China in the 4th century or earlier. They had depths of up to 243 meters and were drilled using bits attached to bamboo poles. The oil was burned to evaporate brine and produce salt. By the 10th century, extensive bamboo pipelines connected oil wells with salt springs. In the 8th century, the streets of the newly constructed Baghdad were paved with tar, derived from easily accessible petroleum from natural fields in the region. In the 9th century, oil fields were exploited in Baku, Azerbaijan, to produce naphtha. These fields were described by the geographer Masudi in the 10th century, and by Marco Polo in the 13th century, who described the output of those wells as hundreds of shiploads. (See also: Timeline of Islamic science and technology.)
The modern history of petroleum began in 1846, with the discovery of the process of refining kerosene from coal by Atlantic Canada's Abraham Pineo Gesner. Poland's Ignacy ?ukasiewicz discovered a means of refining kerosene from the more readily available "rock oil" ("petr-oleum") in 1852 and the first rock oil mine was built in Bóbrka, near Krosno in southern Poland in the following year. These discoveries rapidly spread around the world, and Meerzoeff built the first Russian refinery in the mature oil fields at Baku in 1861. At that time Baku produced about 90% of the world's oil. The battle of Stalingrad was fought over Baku (now the capital of the Azerbaijan Republic).
The first commercial oil well drilled in North America was in Oil Springs, Ontario, Canada in 1858, dug by James Miller Williams. The American petroleum industry began with Edwin Drake's discovery of oil in 1859, near Titusville, Pennsylvania like the Chinese, Drake had been boring for salt. The industry grew slowly in the 1800s, driven by the demand for kerosene and oil lamps. It became a major national concern in the early part of the 20th century the introduction of the internal combustion engine provided a demand that has largely sustained the industry to this day. Early "local" finds like those in Pennsylvania and Ontario were quickly exhausted, leading to "oil booms" in Texas, Oklahoma, and California. By 1910, significant oil fields had been discovered in Canada (specifically, in the province of Alberta), the Dutch East Indies (1885, in Sumatra), Persia (1908, in Masjed Soleiman), Peru, Venezuela, and Mexico, and were being developed at an industrial level.
Even until the mid-1950s, coal was still the world's foremost fuel, but oil quickly took over. Following the 1973 energy crisis and the 1979 energy crisis, there was significant media coverage of oil supply levels. This brought to light the concern that oil is a limited resource that will eventually run out, at least as an economically viable energy source. At the time, the most common and popular predictions were always quite dire, and when they did not come true, many dismissed all such discussion. The future of petroleum as a fuel remains somewhat controversial. USA Today news (2004) reports that there are 40 years of petroleum left in the ground. Some would argue that because the total amount of petroleum is finite, the dire predictions of the 1970s have merely been postponed. Others argue that technology will continue to allow for the production of cheap hydrocarbons and that the earth has vast sources of unconventional petroleum reserves in the form of tar sands, bitumen fields and oil shale that will allow for petroleum use to continue in the future, with both the Canadian tar sands and United States shale oil deposits representing potential reserves matching existing liquid petroleum deposits worldwide.
In World War II the Soviet Union sought to protect their oil fields from falling into the hands of Nazi Germany at the Battle of Stalingrad. Many countries have a strategic oil reserve in the event of war or loss of oil supplies. During the Iran-Iraq War many nations sent military ships to escort tankers carrying oil. During the Gulf War, Iraq's retreating troops burned Kuwait's oil fields in order to give them air cover, to slow the advance of pursuing coalition forces, and to damage the Kuwaiti economy. During the Iraq War the United States had military units work to quickly secure oil fields and remove boobytraps. It also had units guarding the Ministry of Petroleum in Baghdad.
Today, about 90% of vehicular fuel needs are met by oil. Petroleum also makes up 40% of total energy consumption in the United States, but is responsible for only 2% of electricity generation. Petroleum's worth as a portable, dense energy source powering the vast majority of vehicles and as the base of many industrial chemicals makes it one of the world's most important commodities. Access to it was a major factor in several military conflicts, including World War I, World War II and the Persian Gulf War. The top three oil producing countries are Saudi Arabia, Russia, and the United States. About 80% of the world's readily accessible reserves are located in the Middle East, with 62.5% coming from the Arab 5: Saudi Arabia (12.5%), UAE, Iraq, Qatar and Kuwait. The USA has less than 3%.
#### Formation
An oil reservoir, petroleum system or petroleum reservoir is often thought of as being an underground "There was an error working with the wiki: Code[53] There was an error working with the wiki: Code[103]s.
##### Conventional theories
The There was an error working with the wiki: Code[54] from the remains of living things. Crude oil is properly know as petroleum, and is a kind of fossil fuel. Scientific evidence indicates that millions of years of heat and There was an error working with the wiki: Code[55] prefer theories of There was an error working with the wiki: Code[56] which hold that oil originated in There was an error working with the wiki: Code[57] as vast quantities of marine There was an error working with the wiki: Code[58] at the bottom under There was an error working with the wiki: Code[59] that prevented There was an error working with the wiki: Code[60] converted the There was an error working with the wiki: Code[104]s (fats, oils and waxes) into a waxy substance called There was an error working with the wiki: Code[105].
As the source rock was buried deeper, There was an error working with the wiki: Code[61] molecules into the There was an error working with the wiki: Code[62] that make up most of petroleum. Once crude oil formed, it became very There was an error working with the wiki: Code[63], and migrated upward through the There was an error working with the wiki: Code[64]. Eventually it was either trapped in an There was an error working with the wiki: Code[65] and was There was an error working with the wiki: Code[66] by soil bacteria. Any oil buried deeper entered the There was an error working with the wiki: Code[67]. Thus, below a certain depth, the theory predicts that no oil will be found, only There was an error working with the wiki: Code[68]. If it went There was an error working with the wiki: Code[69], even natural gas would be destroyed by There was an error working with the wiki: Code[70].
Roy Nurmi, an interpretation adviser for There was an error working with the wiki: Code[106] described the process as follows: "Something in the order of 500 million years ago there was only simple life in the seas, and these shallow seas would be rich with organic, living organisms. Plankton and algae, proteins and the life that's floating in the sea, as it dies, falls to the bottom, and these organisms are going to be the source of our oil and gas. When they're buried with the accumulating sediment and reach an adequate temperature, something above 50 to 70°C they start to cook. This transformation, this change, changes them into the liquid hydrocarbons that move and migrate, will become our oil and gas reservoir."There was an error working with the wiki: Code[1]
In addition to the Water environment mentioned, which is usually a sea but might also be a There was an error working with the wiki: Code[107], There was an error working with the wiki: Code[108], There was an error working with the wiki: Code[109] or There was an error working with the wiki: Code[110], the formation of an oil or gas reservoir also requires a There was an error working with the wiki: Code[111] that passes through four steps: burial under miles of sand and mud, pressure cooking, hydrocarbon migration from the source to porous rock, and trapping by impermeable rock. Timing is also an important consideration it is suggested that the There was an error working with the wiki: Code[112] could have had as much oil as the There was an error working with the wiki: Code[113] at one time, but that it escaped due to a lack of traps.There was an error working with the wiki: Code[2] The North Sea, on the other hand, endured millions of years of sea level changes that successfully resulted in the formation of more than 150 There was an error working with the wiki: Code[114]s.There was an error working with the wiki: Code[3] Although the process is generally the same, various environmental factors lead to the creation of a wide variety of reservoirs. Reservoirs exist anywhere from 1,000 to 30,000 ft below the surface and are a variety of shapes, sizes and ages.There was an error working with the wiki: Code[4]
The traps required in the last step of the reservoir formation process have been classified petroleum There was an error working with the wiki: Code[71] traps are formed by a deformation in the rock layer that contains the hydrocarbons (e.g., There was an error working with the wiki: Code[72] traps and There was an error working with the wiki: Code[73] traps). There was an error working with the wiki: Code[74] traps are formed when other beds seal a reservoir bed or when the There was an error working with the wiki: Code[75] changes (There was an error working with the wiki: Code[115] change) within the reservoir bed itself. An example of this kind of trap starts when salt deposited by shallow seas. Later, a sinking seafloor deposits organic-rich shale over the salt, which is in turn covered with sandstone. As the Earth's pressure pushes the salt up, the shale is "cooked," producing oil that seeps up into the sandstone above. In some places, the salt breaks through the shale and sandstone layers into a There was an error working with the wiki: Code[116] that effectively traps the hydrocarbons beneath it.There was an error working with the wiki: Code[5] To obtain the contents of the oil reservoir, it is usually necessary to drill into the Earth's crust, although surface oil seeps exist in some parts of the world.
Active areas of surface oil reservoirs:
There was an error working with the wiki: Code[117]
Active areas of existing sub-sea oil reservoirs:
There was an error working with the wiki: Code[118]
There was an error working with the wiki: Code[119]
There was an error working with the wiki: Code[120]
There was an error working with the wiki: Code[121]
##### Biogenic theory
Most geologists view crude oil, like coal and natural gas, as the product of compression and heating of ancient organic materials over geological time. According to this theory, oil is formed from the preserved remains of prehistoric zooplankton and algae which have been settled to the sea bottom in large quantities under anoxic conditions. (Terrestrial plants tend to form coal, and very few dinosaurs have been converted into oil.) Over geological time this organic matter, mixed with mud, is buried under heavy layers of sediment. The resulting high levels of heat and pressure cause the remains to metamorphose, first into a waxy material known as kerogen which is found in various oil shales around the world, and then with more heat into liquid and gaseous hydrocarbons in a process known as catagenesis. Because most hydrocarbons are lighter than rock or water, these sometimes migrate upward through adjacent rock layers until they become trapped beneath impermeable rocks, within porous rocks called reservoirs. Concentration of hydrocarbons in a trap forms an oil field, from which the liquid can be extracted by drilling and pumping.
Geologists often refer to an "oil window" which is the temperature range that oil forms in—below the minimum temperature oil remains trapped in the form of kerogen, and above the maximum temperature the oil is converted to natural gas through the process of thermal cracking. Though this happens at different depths in different locations around the world, a 'typical' depth for the oil window might be 4–6 km. Note that even if oil is formed at extreme depths, it may be trapped at much shallower depths, even if it is not formed there. (In the case of the Athabasca Oil Sands, it is found right at the surface.) Three conditions must be present for oil reservoirs to form: first, a source rock rich in organic material buried deep enough for subterranean heat to cook it into oil second, a porous and permeable reservoir rock for it to accumulate in and last a cap rock (seal) that prevents it from escaping to the surface.
If an oil well were to run dry and be capped, it would be back to original supply rates eventually. There is considerable question about how long this would take. Some formations appear to have a regeneration time of decades. Majority opinion is that oil is being formed at less than 1% of the current consumption rate. The vast majority of oil that has been produced by the earth has long ago escaped to the surface and been biodegraded by oil-eating bacteria. What oil companies are looking for is the small fraction that has been trapped by this rare combination of circumstances. Oil sands are reservoirs of partially biodegraded oil still in the process of escaping, but contain so much migrating oil that, although most of it has escaped, vast amounts are still present - more than can be found in conventional oil reservoirs. On the other hand, oil shales are source rocks that have never been buried deep enough to convert their trapped kerogen into oil.
The reactions that produce oil and natural gas are often modeled as first order breakdown reactions, where kerogen is broken down to oil and natural gas by a set of parallel reactions, and oil eventually breaks down to natural gas by another set of reactions. The first set was originally patented in 1694 under British Crown Patent No. 330 covering "a way to extract and make great quantityes of pitch, tarr, and oyle out of a sort of stone." The latter set is regularly used in petrochemical plants and oil refineries.
##### Abiogenic theory
The idea of abiogenic petroleum origin was championed in the Western world by astronomer Thomas Gold based on thoughts from Russia, mainly on studies of Nikolai Kudryavtsev. The idea proposes that hydrocarbons of purely geological origin exist in the planet. Hydrocarbons are less dense than aqueous pore fluids, and are proposed to migrate upward through deep fracture networks. Thermophilic, rock-dwelling microbial life-forms are proposed to be in part responsible for the biomarkers found in petroleum. However, this theory is a minority opinion, especially amongst geologists and no oil companies are currently known to explore for oil based on this theory. The hypothesis of abiogenic petroleum origin holds that most There was an error working with the wiki: Code[76] of the Earth. The ubiquity of There was an error working with the wiki: Code[77].
Various abiogenic hypotheses were first proposed in the nineteenth century most notably, by the French chemist There was an error working with the wiki: Code[78], by There was an error working with the wiki: Code[122]. Gold's version of the hypothesis partly is based on the existence of a There was an error working with the wiki: Code[123] composed of There was an error working with the wiki: Code[124] bacteria in the earth's crust, which may explain the existence of certain There was an error working with the wiki: Code[125]s in extracted petroleum. There was an error working with the wiki: Code[6]
Although this theory, according to Gold, is widely accepted in Russia, where it was intensively developed in the 1950s and 1960s, it has only recently begun to receive attention in the West, where the biogenic theory is still believed by the vast majority of petroleum geologists. Although some denied that abiogenic hydrocarbons exist at all on earth, this is now admitted by many Western geologists. The orthodox position now is that while abiogenic hydrocarbons exist, they are not produced in commercially significant quantities, so that essentially all hydrocarbons that are extracted for use as fuel or raw materials are biogenic. There was an error working with the wiki: Code[7]There was an error working with the wiki: Code[8]
##### Foundations of the hypothesis
Within the mantle carbon may exist as hydrocarbon molecules, chiefly Methane, and as elemental carbon, carbon dioxide and carbonates. The abiotic hypothesis is that a full suite of hydrocarbons found in petroleum can be generated in the mantle by abiogenic processes,There was an error working with the wiki: Code[9] and these hydrocarbons can migrate out of the mantle, into the crust until they escape to the surface or are trapped by impermeable strata, forming petroleum reservoirs. Abiogenic theories refute the supposition that certain molecules found within petroleum, known as "biomarkers," are indicative of the biological origin of petroleum. They contend that some of these molecules could have come from the microbes that the petroleum encounters in its upward migration through the crust, and that some of them are found in meteorites, which have presumably never contacted living material, and that some can be generated by plausible reactions in petroleum abiogenically.There was an error working with the wiki: Code[10]
The hypothesis is founded primarily upon
The ubiquity of methane within the solar system
The presence of hydrocarbons in extraterrestrial bodies including meteors, moons and cometsThere was an error working with the wiki: Code[11],There was an error working with the wiki: Code[12]
Plausible mechanisms of abiotically chemically synthesizing hydrocarbons within the mantle
Interpretations of the chemical composition of natural petroleum
The presence of oil within non-sedimentary rocks upon the Earth There was an error working with the wiki: Code[13]
Perceived ambiguity in some assumptions and key evidence used in the orthodox biogenic petroleum theories There was an error working with the wiki: Code[14]
Scaled particle theory for a simplified perturbed hard-chain, statistical mechanical model predicts that methane compressed to 30 or 40 kbar at 1000°C (conditions in the mantle) yields hydrocarbons having properties similar to petroleum There was an error working with the wiki: Code[15]There was an error working with the wiki: Code[16]
Experiments in diamond anvil high pressure cells have confirmed this theoryThere was an error working with the wiki: Code[17]
Similar experiments on mixtures of calcium carbonate, iron oxide and water produced methaneThere was an error working with the wiki: Code[18]
##### Hydrogen generation
Hydrogen gas and water have been found more than 6 kilometers deep in the upper crust, including in the Siljan Ring boreholes and the There was an error working with the wiki: Code[126]. There is data in the western United States that There was an error working with the wiki: Code[127]s from near the surface may extend to depths of 10 to 20 km. Hydrogen gas can be created by water reacting with There was an error working with the wiki: Code[128]s, There was an error working with the wiki: Code[129] and There was an error working with the wiki: Code[130], in temperatures in the 25° to 270°C range. These materials are common in crustal rocks such as There was an error working with the wiki: Code[131]. Hydrogen may react with dissolved carbon compounds in water to form methane and higher carbon compounds. There was an error working with the wiki: Code[19]
##### Serpentinite mechanism
One proposed mechanism by which abiogenic petroleum is formed was first proposed by the There was an error working with the wiki: Code[79] scientist, Prof. There was an error working with the wiki: Code[132] in 1967. He proposed that petroleum could be formed at high temperatures and pressures from inorganic carbon in the form of carbon dioxide, hydrogen and/or methane. This mechanism is supported by several lines of evidence which are accepted by modern scientific literature. This involves synthesis of oil within the crust via catalysis by chemically reductive rocks. A proposed mechanism for the formation of inorganic hydrocarbonsThere was an error working with the wiki: Code[20] is via natural analogs of the There was an error working with the wiki: Code[133] known as the serpentinite mechanism or the serpentinite process There was an error working with the wiki: Code[21]There was an error working with the wiki: Code[22].
:CH_4 + \frac{1}{2} O_2 \rarr 2 H_2 + CO
:(2n+1)H_2 + nCO \rarr C_nH_{2n+2} + nH_2O
Serpentinites are ideal rocks to host this process as they are formed from There was an error working with the wiki: Code[134]s and There was an error working with the wiki: Code[135]s, rocks which contain greater than 80% There was an error working with the wiki: Code[136] and usually a percentage of Fe-Ti spinel minerals. Most olivines also contain high nickel concentrations (up to several percent) and may also contain chromite or chromium as a contaminant in olivine, providing the needed transition metals.
However, serpentinite synthesis and spinel cracking reactions require hydrothermal alteration of pristine peridotite-dunite, which is a finite process intrinsically related to metamorphism, and further, requires significant addition of water. Serpentinite is unstable at mantle temperatures and is readily dehydrated to There was an error working with the wiki: Code[137], There was an error working with the wiki: Code[138], There was an error working with the wiki: Code[139]-There was an error working with the wiki: Code[140] and even There was an error working with the wiki: Code[141]. This suggests that methanogenesis in the presence of serpentinites is restricted in space and time to mid-ocean ridges and upper levels of subduction zones. However, water has been found as deep as 12 km,There was an error working with the wiki: Code[23] so water-based reactions are dependent upon the local conditions. Oil being created by this process in intracratonic regions is limited by the materials and temperature.
##### Serpentinite synthesis
A chemical basis for the abiotic petroleum process is the There was an error working with the wiki: Code[80] of There was an error working with the wiki: Code[142], beginning with methanogenesis via hydrolysis of olivine into serpentine in the presence of carbon dioxideThere was an error working with the wiki: Code[24]. Olivine, composed of Forsterite and Fayalite metamorphoses into serpentine, magnetite and silica by the following reactions, with silica from fayalite decomposition (reaction 1a) feeding into the forsterite reaction (1b).
Reaction 1a:
Fayalite + water ? Magnetite + aquaeous silica + hydrogen
:3Fe_2SiO_4 + 2H_2O \rarr 2Fe_3O_4 + 3SiO_2 + 2H_2
Reaction 1b:
Forsterite + aqueous silica ? Serpentinite
:3Mg_2SiO_4 + SiO_2 + 2H_2O \rarr 2Mg_3[Si_2O_5(OH_4)]
When this reaction occurs in the presence of dissolved carbon dioxide (carbonic acid) at temperatures above 500°C Reaction 2a takes place.
Reaction 2a:
Olivine + Water + Carbonic acid ? Serpentine + Magnetite + Methane
:3(Fe,Mg)_2SiO_4 + nH_2O + HCO_3 \rarr 2Mg_3[Si_2O_5(OH_4)] + 2Fe_3O_4 + H_2O + CH_4
However, reaction 2(b) is just as likely, and supported by the presence of abundant talc-carbonate schists and magnesite stringer veins in many serpentinised peridotites
Reaction 2b:
Olivine + Water + Carbonic acid ? Serpentine + Magnetite + Magnesite + Silica
:4(Fe,Mg)_2SiO_4 + nH_2O + HCO_3 \rarr 2Mg_3[Si_2O_5(OH_4)] + 2Fe_3O_4 + 2MgCO_3 + SiO_2 + H_2O
The upgrading of methane to higher n-alkane hydrocarbons is via There was an error working with the wiki: Code[143] of methane in the presence of catalyst transition metals (e.g. Fe, Ni). This can be termed spinel hydrolysis.
##### Spinel polymerization mechanism
There was an error working with the wiki: Code[144], There was an error working with the wiki: Code[145] and There was an error working with the wiki: Code[146] are Fe-spinel group minerals found in many rocks but rarely as a major component in non-ultramafic rocks. In these rocks, high concentrations of magmatic magnetite, chromite and ilmenite provide a reduced matrix which may allow abiotic cracking of methane to higher hydrocarbons during There was an error working with the wiki: Code[147] events. Chemically reduced rocks are required to drive this reaction and high temperatures are required to allow methane to be polymerized to ethane. Note that reaction 1a, above, also creates magnetite.
Reaction 3:
''Methane + Magnetite ? Ethane + Hematite
:nCH_4 + nFe_3O_4 + nH_2O \rarr C_2H_6 + Fe_2O_3 + HCO_3 + H^+
Reaction 3 results in n-alkane hydrocarbons, including linear saturated hydrocarbons, There was an error working with the wiki: Code[148]s, There was an error working with the wiki: Code[149]s, There was an error working with the wiki: Code[150]s, There was an error working with the wiki: Code[151]s, and cyclic compounds.There was an error working with the wiki: Code[25]
##### Evidence from petroleum geochemistry
If the above mechanism for inorganic petroleum genesis is active and prevalent within the Earth crust and the abiogenic theory holds true, the geochemistry of petroleum deposits within the Earth’s crust should reflect this mechanism of formation. The geochemistry of petroleum deposits has been widely and deeply studied by oil companies and academia for more than a century in order to elucidate the origin of petroleum and develop predictive scientific models. Certain findings of this research can be used to interpret petroleum as being either of biogenic or abiogenic origin. These include biomarker chemicals, the optical activity of oils, chirality and the trace metal abundances of oils.
##### Isotopic evidence
There was an error working with the wiki: Code[81] is a clear indicator of mantle source within gases. Within the major precambrian shield there is no evidence of mantle helium in gases or groundwaters, which disproves the theory of continued outgassing of primordial methane and helium along structures in the Precambrian basement. Furthermore, there are few examples of primordial helium or mantle helium trapped within oil and gas occurrences. Helium trapped within most petroleum occurrences, such as the occurrence in Texas, is of a distinctly crustal character with an Ra ratio of less than 0.0001 that of the atmosphere.
##### Biomarker chemicals
Certain chemicals found in naturally occurring petroleum contain chemical and structural similarities to compounds found within many living organisms. These include There was an error working with the wiki: Code[82] molecules in the same family as There was an error working with the wiki: Code[152] and There was an error working with the wiki: Code[153]. Materials which suggest certain biological processes include tetracyclic diterpane and oleanane. The presence of these chemicals in crude oil is assumed to be as a result of the inclusion of biological material in the oil. This is predicated upon the theory that these chemicals are released by There was an error working with the wiki: Code[154] during the production of hydrocarbon oils. However, since the advent of abiogenic theory, the veracity of these assumptions has been called into question and new lines of evidence used to provide alternative explanations.
##### Odd-number carbon abundance
Members of the There was an error working with the wiki: Code[83] series found in petroleum have a slightly greater abundance of odd-numbered carbon chains (There was an error working with the wiki: Code[155], There was an error working with the wiki: Code[156], etc.) Likewise, linear carbohydrate molecules in living systems exhibit the same preference for odd carbon numbers. All mixtures of linear hydrocarbon chains, be they artificial, natural or biological, exhibit this tendency. It arises from the geometry of the There was an error working with the wiki: Code[157] in linear molecules, so the greater abundances of odd-numbered hydrocarbons need not be of biological origin.
##### Trace metals
There was an error working with the wiki: Code[84] (Hg) and others metals frequently occur in oils. Some heavy crude oils, such as Venezuelan heavy crude have up to 45% There was an error working with the wiki: Code[158] pentoxide content in their ash, high enough that it is a commercial source for vanadium. These metals are common in Earth's mantle, thus their compounds in oils are often called as abiomarkers. Analysis of 22 trace elements in 77 oils correlate significantly better with There was an error working with the wiki: Code[159], serpentinized fertile mantle peridotite, and the primitive mantle than with oceanic or continental crust, and shows no correlation with seawater. There was an error working with the wiki: Code[28]
##### Reduced carbon
Petroleum is composed mainly of There was an error working with the wiki: Code[85]. Sir There was an error working with the wiki: Code[86] studied the chemical makeup of natural petroleum oils in great detail, and concluded that they were mostly far too hydrogen-rich to be a likely product of the decay of plant debris.There was an error working with the wiki: Code[29] There was an error working with the wiki: Code[160]s, the unsaturated hydrocarbons, would have been expected to predominate by far in any material that was derived in that way. He also wrote: "Petroleum ... [seems to be] a primordial hydrocarbon mixture into which bio-products have been added." The presence of low-oxygen and hydroxyl-poor hydrocarbons in natural living media is supported by the presence of natural waxes (n=30+), oils (n=20+) and lipids in both plant matter and animal matter, for instance fats in phytoplankton, zooplankton and so on. These oils and waxes, however, occur in quantities too small to significantly affect the overall hydrogen/carbon ratio of biological materials.
##### Geological framework
The proposed mechanism for abiogenic petroleum production is robust in theory, leaving aside ambiguous geochemical evidence. The abiogenic theory on the origin of petroleum seeks to explain the origin of commercial accumulations of petrochemicals via chemical mechanisms such as serpentinite catalysis. The geological observations which are used to support the abiogenic origin of petrochemical deposits should be evaluated on a case-by-case basis for each hydrocarbon deposit, with the presence of no one line of evidence used in isolation to infer genetic conclusions when equivocal or contradictory evidence is available. The geological observations proposed for the abiogenic theory are presented below, followed by investigation of several key deposits on a case by case basis to evaluate their genesis.
##### Direct observations
The following are the direct tests of the abiogenic hypothesis of petroleum or impartial evidence generated by observations of the Earth which can be used to argue the theory for or against, and is presented as such.
The There was an error working with the wiki: Code[87] meteorite crater, Sweden, was proposed by Thomas Gold as the most likely place to test the hypothesis because it was one of the few places in the world where the granite basement was cracked sufficiently (by meteorite impact) to allow oil to seep up from the mantle furthermore it is infilled with a relatively thin veneer of sediment, which was sufficient to trap any abiogenic oil but was modelled as untenable for a biogenic origin of any oil (it had not developed the 'oil window' and structural traps typical of biogenic plays).
:Drilling of the Siljan Ring with the Gravberg-1 7,500m borehole penetrated the lowest reservoirs. Hydrocarbons were found, though in an economically unviable form of sludge. It was proposed that the eight barrels of oil produced were from the diesel fuel based drilling fluid used to do the drilling, but the diesel was demonstrated to be not of the kind of oil found in the shaft. This well also sampled over 13,000 feet of methane-bearing inclusions. To be safe, a second hole was drilled a few miles away with no diesel fuel based drilling fluid and this produced 15 tons of oil. [http://web.archive.org/web/20021015163818/www.people.cornell.edu/pages/tg21/usgs.html
Methanogenesis of groundwaters associated with ultramafic dykes and serpentinites, South Island of There was an error working with the wiki: Code[161]
Methane outflows are common from drillholes within large Archaean serpentinised There was an error working with the wiki: Code[88] bodies, such as the Honeymoon Well complex, Yakabindie ultramafic, Mt Clifford dunite, in the There was an error working with the wiki: Code[162], Western Australia.
Direct observation of bacterial mats and fracture-fill carbonate and humin of bacterial origin in deep boreholes in Iran, AustraliaThere was an error working with the wiki: Code[30], Sweden and Canada
Presence of deep-dwelling microbes in the There was an error working with the wiki: Code[163] cave complex, New Mexico
##### Example abiogenic deposits
Supergiant fields such as the There was an error working with the wiki: Code[89] oil field in There was an error working with the wiki: Code[164] has been proposed as an example of abiogenic oil because it is 4,000 m of fractured basement granite, at a depth of 5,000 m. There was an error working with the wiki: Code[31]. However, others argue that it contains biogenic oil which leaked into the basement horst from conventional source rocks within the Cuu Long basin There was an error working with the wiki: Code[32] There was an error working with the wiki: Code[33].
##### The geological argument for abiogenic oil
Given the known occurrence of methane and the probable catalysis of methane into higher atomic weight hydrocarbon molecules, the abiogenic hypothesis considers the following to be key observations in support
The serpentinite synthesis, graphite synthesis and spinel catalysation models prove the process is viable There was an error working with the wiki: Code[34]There was an error working with the wiki: Code[35]
The association of oil deposits with key tectonic structures and plate boundaries, generally in arcs
The likelihood that abiogenic oil seeping up from the mantle is trapped beneath sediments which effectively seal mantle-tapping faults There was an error working with the wiki: Code[36]
There was an error working with the wiki: Code[165] that states petroleum can be found in all layers of a sedimentary basin subsequently proven to be of limited application it has also been stated as applying to hydrocarbon deposits, including natural gas, petroleum, and coal
Mass-balance calculations for supergiant oilfields which argue that the calculated source rock could not have supplied the reservoir with the known accumulation of oil, implying deep recharge (Kudryaavtsev, 1951)
##### Incidental evidence
The proponents of abiogenic oil use several arguments which draw on a variety of natural phenomena in order to support the hypothesis
The ubiquitous presence of carbon, methane, ammonia and a variety of amino acids within extraterrestrial bodies such as There was an error working with the wiki: Code[166], There was an error working with the wiki: Code[167] and on several moons within the Solar System. The Earth acquired a lot of carbon during its creation.
The modelling of some researchers which shows the Earth was accreted at relatively low temperature, thereby perhaps preserving primordial carbon deposits within the mantle, to drive abiogenic hydrocarbon production There was an error working with the wiki: Code[37]
The presence of natural gas eruptions, flames and explosions during earthquakes and during some volcanic eruptions, mainly in mud volcanoes.
The presence of vast quantities of methane hydrate (There was an error working with the wiki: Code[168]) within deep pelagic oozes within the oceans of the Earth, cited as evidence of abiogenic methane generation from serpentinitisation of the oceanic crust.
The presence of methane within the gases and fluids of mid-ocean ridge spreading centre There was an error working with the wiki: Code[169] fieldsThere was an error working with the wiki: Code[38]
The presence of intraplate earthquakes and deep focus earthquakes, apparently caused by movement of vast quantities of mantle methane and hydrocarbons
The presence of tiny diamondoids in oils. Diamondoids probably form at high pressures in the earth's mantle and they migrate together with oil and gas to low pressures in the crust.
The presence of Hydrocarbon Lakes on Saturns Moon, Titan
##### The geological argument against
Key arguments against chemical reactions, such as the serpentinite mechanism, as being the major source of hydrocarbon deposits within the crust are
The lack of available pore space within rocks as depth increases especially within the mantle
The presence of no commercial hydrocarbon deposits within the crystalline shield areas of the major cratons especially around key deep seated structures which are predicted to host oil by the abiogenic theory There was an error working with the wiki: Code[39]
Limited evidence that major serpentinite belts underlie continental sedimentary basins which host oil
Lack of conclusive proof that carbon isotope fractionation observed in crustal methane sources is entirely of abiogenic origin (Lollar et al. 2006)There was an error working with the wiki: Code[40]
Mass balance problems of supplying enough carbon dioxide to serpentinite within the metamorphic event before the peridotite is fully reacted to serpentinite
Drilling of the Siljan Ring failed to find commercial quantities of gasThere was an error working with the wiki: Code[41], thus disproving There was an error working with the wiki: Code[170] and failing to locate the predicted abiogenic gas
Helium in the Siljan Gravberg-1 well was depleted in There was an error working with the wiki: Code[90] and not consistent with a mantle originThere was an error working with the wiki: Code[42]
The distribution of sedimentary basins is caused by plate tectonics, with sedimentary basins forming on either side of a There was an error working with the wiki: Code[171], which explains the distribution of oil within these sedimentary basins
##### Arguments against the incidental evidence
Gas ruptures during earthquakes are more likely to be sourced from biogenic methane generated in unconsolidated sediment from existing organic matter, released by There was an error working with the wiki: Code[172] of the reservoir during tremors
The presence of methane hydrate is arguably produced by bacterial action upon organic detritus falling from the There was an error working with the wiki: Code[173] zone and trapped in the depth due to pressure and temperature
The likelihood of vast concentrations of methane in the mantle is very slim, given mantle xenoliths have negligible methane in their fluid inclusions conventional plate tectonics explains deep focus quakes better, and the extreme confining pressures invalidate the theory of gas pockets causing quakes
Further evidence is the presence of diamond within There was an error working with the wiki: Code[174]s and There was an error working with the wiki: Code[175]s which sample the mantle depths proposed as being the source region of mantle methane (by Gold et al). It is arguable from oxygen fugacity and carbon phase stability models that reduced carbon in the mantle is either in the form of graphite or diamond, not methane, and that oxidized carbon is present as carbon dioxide.
##### History of abiogenic theory
The abiogenic petroleum theory was founded upon several archaic interpretations of geology which stem from early 19th century notions of magmatism (which at the time was attributed to sulfur fires and bitumen burning underground) and of petroleum, which was seen by many to fuel There was an error working with the wiki: Code[91] appreciation of basalts at times saw them as solidified oils or bitumen. While these notions have been disabused, the basic notion that petroleum is associated with magmatism has persisted. The chief proponents of what would become the abiogenic theory were There was an error working with the wiki: Code[92]. Russian geologist There was an error working with the wiki: Code[93] was the first to propose the modern abiotic theory of petroleum in 1951. He analyzed the geology of the There was an error working with the wiki: Code[176] in There was an error working with the wiki: Code[177] and concluded that no "source rocks" could form the enormous volume of hydrocarbons (estimated today 1.7 trillions barrels), and that therefore the most plausible explanation is abiotic deep petroleum. However, humic coals have been proposed for the source rocks by Stanton (2005).
Although this theory is supported by geologists in There was an error working with the wiki: Code[178] and There was an error working with the wiki: Code[179], it has recently begun to receive attention in the West, where the biogenic petroleum theory is still believed by the vast majority of petroleum There was an error working with the wiki: Code[180]s. Kudryavtsev's work was continued by many Russian researchers — There was an error working with the wiki: Code[181], There was an error working with the wiki: Code[182], There was an error working with the wiki: Code[183], Vladilen A. Krayushkin, There was an error working with the wiki: Code[184], There was an error working with the wiki: Code[185], There was an error working with the wiki: Code[186], Iona V. Greenberg, Nikolai S. Beskrovny, There was an error working with the wiki: Code[187] and many others. Astrophysicist Thomas Gold was one of the abiogenic theory's most prominent proponents in recent years in the West, until his death in 2004. Dr. Jack Kenney of Gas Resources CorporationThere was an error working with the wiki: Code[44]There was an error working with the wiki: Code[45]There was an error working with the wiki: Code[46] is perhaps the foremost proponent in the West. The theory receives continued attention in the media as well as in scientific publications.
##### Petroleum origin, peak oil, and politics
Many aspects of the abiogenic theory were developed in the former There was an error working with the wiki: Code[94] and There was an error working with the wiki: Code[95] scientists during the There was an error working with the wiki: Code[96] peak". The abiogenic theory stands in contrast to that of There was an error working with the wiki: Code[97], which presumes a fixed and dwindling supply of oil that was formed through biological processes. Some There was an error working with the wiki: Code[188]s accuse abiogenic theory supporters of a "There was an error working with the wiki: Code[189]" worldview. They claim that such a view incorrectly sees no limits to exploitation of petroleum supplies while simultaneously ignoring potential consequences of petroleum consumption such as There was an error working with the wiki: Code[190]. Conversely, some supporters of the abiogenic theory accuse their opponents of an unwarranted There was an error working with the wiki: Code[191] viewpoint that needlessly limits the use of hydrocarbons as an energy source and artificially inflates oil prices.
Independent of whether massive hydrocarbon reserves exist deep in the crust, they are unattainable in the short term. Additionally, oil wells are being drilled down to depths of 10 km, just shy of the world record of 12 km set by the Kola Superdeep Borehole in the Siberian Craton. Thus the "deep reservoirs" of Gold et al. are being tested successfully according to biogenic models of petroleum occurrence. Considering the dominance of the biogenic origin theory in the exploration industry, new oil discoveries based on abiogenic theory may be slow in coming. The There was an error working with the wiki: Code[98] section below.
##### State of current research
Currently there is little direct research on abiogenic petroleum or experimental studies into the synthesis of abiogenic methane. However, several research areas, mostly related to There was an error working with the wiki: Code[192] and the deep microbial biosphere and serpentinite reactions, continue to provide insight into the contribution of abiogenic hydrocarbons into petroleum accumulations.
ocean floor There was an error working with the wiki: Code[99] hydrothermal field
There was an error working with the wiki: Code[193]es and the volatile contents of deep pelagic oozes and deep formation brines
mantle There was an error working with the wiki: Code[194] There was an error working with the wiki: Code[195] reactions and other natural Fischer-Tropsch analogs
Primoridal hydrocarbons in There was an error working with the wiki: Code[196]s, There was an error working with the wiki: Code[197]s, There was an error working with the wiki: Code[198] and the solid bodies of the There was an error working with the wiki: Code[199]
Primordial or ancient sources of hydrocarbons or carbon in Earth There was an error working with the wiki: Code[47]There was an error working with the wiki: Code[48]
isotopic studies of groundwater reservoirs, sedimentary cements, formation gases and the composition of the noble gases and nitrogen in many oil fields
the geochemistry of petroleum and the presence of trace metals related to Earth's mantle (Ni, V, Cd, As, Pb, Zn, Hg and others)
Similarly, research into the deep microbial hypothesis of hydrocarbon generation is advancing as part of the attempt to investigate the concept of There was an error working with the wiki: Code[200] and There was an error working with the wiki: Code[201], specifically using deep microbial life as an analog for There was an error working with the wiki: Code[202]. Research applicable to deep microbial petroleum theories includes
Research into how to sample deep reservoirs and rocks without contamination
Sampling deep rocks and measuring chemistry and biological activity There was an error working with the wiki: Code[49]
Possible energy sources and metabolic pathways which may be used in a deep biosphere There was an error working with the wiki: Code[50]There was an error working with the wiki: Code[51]
Investigations into the reworking primordial hydrocarbons by bacteria and their effects on carbon isotope fractionation
The abiogenic origin of petroleum has recently been reviewed in detail by Glasby There was an error working with the wiki: Code[52] and shown to be invalid on a number of counts.
#### Means of producing oil
As oil prices continue to escalate, other alternatives to producing oil have been gaining importance. The best known such methods involve extracting oil from sources such as oil shale or tar sands. These resources are known to exist in large quantities however, extracting the oil at low cost without negatively impacting the environment remains a challenge. It is also possible to transform natural gas or coal into oil (or, more precisely, the various hydrocarbons found in oil). The best-known such method is the Fischer-Tropsch process, It was a concept pioneered in Nazi Germany when imports of petroleum were restricted due to war and Germany found a method to extract oil from coal. It was known as Ersatz ("substitute" in German), and accounted for nearly half the total oil used in WWII by Germany. However, the process was used only as a last resort as naturally occurring oil was much cheaper. As crude oil prices increase, the cost of coal to oil conversion becomes comparatively cheaper. The method involves converting high ash coal into synthetic oil in a multistage process. Ideally, a ton of coal produces nearly 200 liters (1.25 bbl, 52 US gallons) of crude, with by-products ranging from tar to rare chemicals.
Currently, two companies have commercialised their Fischer-Tropsch technology. Shell in Bintulu, Malaysia, uses natural gas as a feedstock, and produces primarily low-sulfur diesel fuels. Sasol in South Africa uses coal as a feedstock, and produces a variety of synthetic petroleum products. The process is today used in South Africa to produce most of the country's diesel fuel from coal by the company Sasol. The process was used in South Africa to meet its energy needs during its isolation under Apartheid. This process has received renewed attention in the quest to produce low sulfur diesel fuel in order to minimize the environmental impact from the use of diesel engines. An alternative method is the Karrick process, which converts coal into crude oil, pioneered in the 1930s in the United States. More recently explored is thermal depolymerization (TDP). In theory, TDP can convert any organic waste into petroleum.
#### Extraction
Locating an oil field is the first obstacle to be overcome. Today, geologists use seismic surveys to search for geological structures that may form oil reservoirs. Other instruments such as gravimeters and magnetometers are also sometimes used in the search for petroleum. Generally, the first stage in the extraction of crude oil is to drill a well into the underground reservoir. When an oil bearing structure has been tapped, the wellsite geologist (known on the rig as the "mudlogger") will note its presence. Historically, in the USA, some oil fields existed where the oil rose naturally to the surface, but most of these fields have long since been depleted, except for certain remote locations in Alaska. Often many wells (called multilateral wells) are drilled into the same reservoir, to ensure that the extraction rate will be economically viable. Also, some wells (secondary wells) may be used to pump water, steam, acids or various gas mixtures into the reservoir to raise or maintain the reservoir pressure, and so maintain an economic extraction rate.
If the underground pressure in the oil reservoir is sufficient, then the oil will be forced to the surface under this pressure. Gaseous fuels, natural gas or water are usually present, which also supply needed underground pressure. In this situation it is sufficient to place a complex arrangement of valves (the Christmas tree) on the well head to connect the well to a pipeline network for storage and processing. This is called primary oil recovery. Usually, only about 20% of the oil in a reservoir can be extracted this way.
The amount of oil that is recoverable is determined by a number of factors including the permeability of the rocks, the strength of natural drives (the gas present, pressure from adjacent water or gravity), and the viscosity of the oil. When the reservoir rocks are "tight" such as shale, oil generally cannot flow through but when they are permeable such as in sandstone, oil flows freely. The flow of oil is often helped by natural pressures surrounding the reservoir rocks including natural gas that may be dissolved in the oil, natural gas present above the oil, water below the oil and the strength of gravity. Oils tend to span a large range of viscosity from liquids as light as gasoline to heavy as tar. The lightest forms tend to result in higher production rates.
Over the lifetime of the well the pressure will fall, and at some point there will be insufficient underground pressure to force the oil to the surface. If economical, and it often is, the remaining oil in the well is extracted using secondary oil recovery methods (see: energy balance and net energy gain). Secondary oil recovery uses various techniques to aid in recovering oil from depleted or low-pressure reservoirs. Sometimes pumps, such as beam pumps and electrical submersible pumps (ESPs), are used to bring the oil to the surface. Other secondary recovery techniques increase the reservoir's pressure by water injection, natural gas reinjection and gas lift, which injects air, carbon dioxide or some other gas into the reservoir. Together, primary and secondary recovery allow 25% to 35% of the reservoir's oil to be recovered.
Tertiary oil recovery reduces the oil's viscosity to increase oil production. Tertiary recovery is started when secondary oil recovery techniques are no longer enough to sustain production, but only when the oil can still be extracted profitably. This depends on the cost of the extraction method and the current price of crude oil. When prices are high, previously unprofitable wells are brought back into production and when they are low, production is curtailed. Thermally enhanced oil recovery methods (TEOR) are tertiary recovery techniques that heat the oil and make it easier to extract. Steam injection is the most common form of TEOR, and is often done with a cogeneration plant. In this type of cogeneration plant, a gas turbine is used to generate electricity and the waste heat is used to produce steam, which is then injected into the reservoir. This form of recovery is used extensively to increase oil production in the San Joaquin Valley, which has very heavy oil, yet accounts for 10% of the United States' oil production. In-situ burning is another form of TEOR, but instead of steam, some of the oil is burned to heat the surrounding oil. Occasionally, detergents are also used to decrease oil viscosity. Tertiary recovery allows another 5% to 15% of the reservoir's oil to be recovered.
Drilling mud, also called drilling fluid, is a lubricant used while drilling There was an error working with the wiki: Code[100] and Natural gas wells and in exploration There was an error working with the wiki: Code[203]s. The three primary purposes of drilling mud or drilling fluids are to:
#Remove cuttings from the formation produced by the bit at the bottom of the hole and carry them to the surface. This is achieved by adjusting the There was an error working with the wiki: Code[204] of the mud system.
#Lubricate and cool the drill bit during operation as friction causes high temperatures down-hole that can limit tool life and performance.
#Maintain There was an error working with the wiki: Code[101] There was an error working with the wiki: Code[102] and to physically stabilize the formation.
Other characteristics are considered important in modern drilling. Some of these include:
Safe for the environment
Prevent dispersion of reactive clays (gumbo)
Ability to seal formation fractures/voids
Non abrasive to tools and rig equipment
Offshore mud systems run in pressure from 5,000 to 7,500 psi.
On a There was an error working with the wiki: Code[205] pumping it with mud pumps through the There was an error working with the wiki: Code[206] where it sprays out of nozzles on the There was an error working with the wiki: Code[207] (cleaning the bit in the process), the mud then travels back up the annular space between the drill string and the sides of the hole being drilled, up through the surface casing, and emerges at the surface. Cuttings are then filtered out at the shale shaker and the mud enters the mud pits. The mud is then pumped back down and is continuously recirculated. The mud is treated periodically in the mud pits to give it properties that optimize and improve drilling efficiency.
Water-based drilling mud may consist of There was an error working with the wiki: Code[208] There was an error working with the wiki: Code[209] (gel) with additives such as There was an error working with the wiki: Code[210] (barite), calcium carbonate (chalk) or There was an error working with the wiki: Code[211]. Various There was an error working with the wiki: Code[212]s are used to influence the There was an error working with the wiki: Code[213] of the fluid, eg. Xanthan Gum, There was an error working with the wiki: Code[214], There was an error working with the wiki: Code[215], There was an error working with the wiki: Code[216], polyanionic cellulose (PAC), or There was an error working with the wiki: Code[217]. In turn, There was an error working with the wiki: Code[218]s are used to reduce viscosity of clay-based muds anionic There was an error working with the wiki: Code[219]s (eg. There was an error working with the wiki: Code[220]s, There was an error working with the wiki: Code[221]s, There was an error working with the wiki: Code[222] (Lig) or There was an error working with the wiki: Code[223] derivates such as There was an error working with the wiki: Code[224]) are frequently used. Red mud was the name for a There was an error working with the wiki: Code[224]-based mixture, named after the color of the red tannic acid salts it was commonly used in 1940s to 1950s, then was obsoleted when lignosulfates became available. Many other chemicals are also used to maintain or create some of the properties listed in the section titled "Purpose".
One classification scheme for drilling fluids is based on their composition, and divides them to water-base, non-water (oil, olefin, or other synthetic fluid) base, and gaseous, or pneumatic. Oil Based and Synthetic Based muds are frequently classified separately due to the vast differences in regulations when using them.
The There was an error working with the wiki: Code[226] name given to an oil field service company individual who is charged with maintaining a drilling fluid or completion fluid system on an oil and/or gas drilling rig. This individual typically works for the company selling the chemicals for the job and is specifically trained with those products, though independent mud engineers are still common. The work schedule of the mud engineer or Drilling Fluids Engineer, as he or she is more properly called these days, is usually fairly strenuous, as are most jobs in this industry. Until a few years ago, the "mud engineer" rarely worked a set schedule and, if resident on an There was an error working with the wiki: Code[227] installation, may have been on call for 24 hours a day, with few (if any) days off each month. With the advent some 15 years ago in Northern Europe, of having two mud engineers offshore due to Health, Safety and Environmental regulations and working hours restrictions in more advanced countries, the offshore mud engineer rarely works more than the normal 12 hour shift. On land, however, there usually still is only one mud engineer assigned and most of the time, he is allocated to more than one drilling rig. The economics of land-drilling demands that the land-engineer spends a greater part of the day driving from rig to rig, testing the drilling or completion fluids, making recommendations for its maintenance and then repeating the process at another rig(s). A daily stop like this, usually for an hour or two, is typically called a "Drive-By". A 24 hour assignment to a single land rig is called a "sitting" job.
Offshore drilling, with new technology and high total day costs for the operation, have wells being drilled extremely fast and day rates for operations have increased. Any down time is frowned upon and having two mud engineers makes economical sense to sensible oil companies, to prevent down time due to drilling fluid difficulties. Two mud engineers also reduce insurance loading to oil companies for possible environmental damage that oil companies are responsible for during their license to drill and produce. The cost of the drilling fluid is typically about 10% (may vary greatly) of the total cost of well construction. This large cost overhead places a demand on the competency of the mud engineer. Large cost savings can result when the mud engineer adequately performs his job. The mud engineer is not to be confused with a There was an error working with the wiki: Code[228], a service personnel who monitors gas from the mud and collects wellbore samples.
The compliance engineer is the most common name for a relatively new position in the oil field, emerging around 2002 due to new environmental regulations on Synthetic Mud. Previously synthetic mud was regulated in the same way as water based mud and could be disposed of into offshore waters as needed due to its low toxicity to marine mammals. New regulations restrict the amount of synthetic oil that can be discharded as a percentage by weight of synthetic fluid on cuttings that have been drilled and are being discharged overboard. For olefin based fluids the limit is 6.9%, for ester based fluids it is a bit higher. These new regulations created a significant amount of additional work in the form of tests needed to determine the "ROC" or retention on cuttings, sampling to determine the percentage of crude oil in the drilling mud, and extensive documention to substantiate all of this.
A new monthly toxicity test is also now performed to determine sediment toxicity. The species used is There was an error working with the wiki: Code[229] picture. Various concentrations of the drilling mud are added to the environment of the Leptochirus plumulosus to determine its effect on the animals. This is controversial for two reasons:
#These animals are not native to many of the areas regulated by them, including the Gulf of Mexico
#The test has a very large standard deviation and samples that fail horribly may pass easily upon retesting.
Directional drilling (sometimes known as slant drilling outside the oil industry) is the science of drilling non-vertical wells. Directional drilling can be broken down into three main groups Oilfield Directional Drilling, Utility Installation Directional Drilling (commonly known as H.D.D./Horizontal Directional Drilling) and in-seam directional drilling (Coal-Bed methane).
A number of prerequisites were necessary before this suite of technologies could become productive. Probably the first requirement was the realisation that oil wells (or water wells, but since their depths are normally trivial, the development was essentially done in the oil industry) are not necessarily vertical. This realisation was quite slow, and didn't really grasp the attention of the oil industry until the late 1920s when there were several cases of lawsuits alleging that a well drilled from a rig on one person's property had actually crossed the boundary and was penetrating a reservoir on an adjacent property. Initially proxy evidence such as changes in production from pre-existing wells was accepted, but such cases fuelled the development of small diameter tools capable of surveying wells as (or during) their drilling.
Measuring the inclination of a wellbore (its deviation from the vertical) is comparatively simple—one needs a pendulum of some sort. But measuring the azimuth (direction with respect to the geographic grid in which the wellbore is running from the vertical) was much more difficult. In certain circumstances magnetic fields could be used, but were open to the influence of the metalwork used to line wellbores, as well as the metalwork used in drilling equipment itself. The big step forward was in the modification of small gyroscopic compasses by the Sperry company, who were making similar compasses for aeronautical navigation. Sperry did this work under contract to Sun Oil (who were involved in a lawsuit as described above), and a spin-off company was formed under the name "Sperry Sun", which brand continues to this day, absorbed into Halliburton, the second-largest oil services company.
Prior experience with rotary drilling had established a number of principles for the configuration of drilling equipment down hole ("Bottom Hole Assembly" or "BHA") that would be prone to "drilling crooked hole" (initial accidential deviations would be increased away from the vertical). Counter-experience had also given these early directional drillers ("DD's", on many whiteboards on many rigs around the world to this day) principles of BHA design and drilling practice which would help bring a crooked hole back towards the vertical. Combined, these survey tools and BHA designs made directional drilling possible, but it was perceived to be decidedly arcane. Some DDs allegedly took a perverse delight in making it sound more arcane than it actually was - using Ouija boards to perform calculations instead of slide rules for example. Actual
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https://www.knowpia.com/knowpedia/Noise_pollution
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BREAKING NEWS
Noise pollution
## Summary
Noise pollution, or sound pollution, is the propagation of noise or sound with ranging impacts on the activity of human or animal life, most of which are harmful to a degree. The source of outdoor noise worldwide is mainly caused by machines, transport, and propagation systems.[1][2][3] Poor urban planning may give rise to noise disintegration or pollution, side-by-side industrial and residential buildings can result in noise pollution in the residential areas. Some of the main sources of noise in residential areas include loud music, transportation (traffic, rail, airplanes, etc.), lawn care maintenance, construction, electrical generators, wind turbines, explosions, and people.
A Qantas Boeing 747-400 passes close to houses shortly before landing at London Heathrow Airport
Traffic is the main source of noise pollution in cities like São Paulo, shown here.
Documented problems associated with noise in urban environments go back as far as ancient Rome.[4] Research suggests that noise pollution in the United States is the highest in low-income and racial minority neighborhoods,[5] and noise pollution associated with household electricity generators is an emerging environmental degradation in many developing nations.[6]
High noise levels can contribute to cardiovascular effects in humans and an increased incidence of coronary artery disease.[7][8] In animals, noise can increase the risk of death by altering predator or prey detection and avoidance, interfere with reproduction and navigation, and contribute to permanent hearing loss.[9] A substantial amount of the noise that humans produce occurs in the ocean. Up until recently, most research on noise impacts has been focused on marine mammals, and to a lesser degree, fish.[10][11] In the past few years, scientists have shifted to conducting studies on invertebrates and their responses to anthropogenic sounds in the marine environment. This research is essential, especially considering that invertebrates make up 75% of marine species, and thus compose a large percentage of ocean food webs.[11] Of the studies that have been conducted, a sizable variety in families of invertebrates have been represented in the research. A variation in the complexity of their sensory systems exists, which allows scientists to study a range of characteristics and develop a better understanding of anthropogenic noise impacts on living organisms.
Because the local civic noise environment can impact the perceived value of real estate, often the largest equity held by a home owner, personal stakes in the noise environment and the civic politics surrounding the noise environment can run extremely high.
## Noise pollution effect on Health
### Humans
Noise pollution affects both health and behavior. Unwanted sound (noise) can damage physiological health. Noise pollution is associated with several health conditions, including cardiovascular disorders, hypertension, high stress levels, tinnitus, hearing loss, sleep disturbances, and other harmful and disturbing effects.[7][12][13][14][15] According to a 2019 review of the existing literature, noise pollution was associated with faster cognitive decline.[16]
Across Europe, according to the European Environment Agency, it estimated 113 million people are affected by road traffic noise levels above 55 decibels, the threshold at which noise becomes harmful to human health by the WHO's definition.[17]
Sound becomes unwanted when it either interferes with normal activities such as sleep or conversation, or disrupts or diminishes one's quality of life.[18] Noise-induced hearing loss can be caused by prolonged exposure to noise levels above 85 A-weighted decibels.[19] A comparison of Maaban tribesmen, who were insignificantly exposed to transportation or industrial noise, to a typical U.S. population showed that chronic exposure to moderately high levels of environmental noise contributes to hearing loss.[12]
Noise exposure in the workplace can also contribute to noise-induced hearing loss and other health issues. Occupational hearing loss is one of the most common work-related illnesses in the U.S. and worldwide.[20]
It is less clear how humans adapt to noise subjectively. Tolerance for noise is frequently independent of decibel levels. Murray Schafer's soundscape research was groundbreaking in this regard. In his work, he makes compelling arguments about how humans relate to noise on a subjective level, and how such subjectivity is conditioned by culture.[21] Schafer notes that sound is an expression of power, and as such, material culture (e.g., fast cars or Harley Davidson motorcycles with aftermarket pipes) tend to have louder engines not only for safety reasons, but for expressions of power by dominating the soundscape with a particular sound.[22]
Other key research in this area can be seen in Fong's comparative analysis of soundscape differences between Bangkok, Thailand and Los Angeles, California, US. Based on Schafer's research, Fong's study showed how soundscapes differ based on the level of urban development in the area. He found that cities in the periphery have different soundscapes than inner city areas. Fong's findings tie not only soundscape appreciation to subjective views of sound, but also demonstrates how different sounds of the soundscape are indicative of class differences in urban environments.[23]
Noise pollution can have negative affects on adults and children on the autistic spectrum.[24] Those with Autism Spectrum Disorder (ASD) can have hyperacusis, which is an abnormal sensitivity to sound.[25] People with ASD who experience hyperacusis may have unpleasant emotions, such as fear and anxiety, and uncomfortable physical sensations in noisy environments with loud sounds.[26] This can cause individuals with ASD to avoid environments with noise pollution, which in turn can result in isolation and negatively affect their quality of life. Sudden explosive noises typical of high-performance car exhausts and car alarms are types of noise pollution that can affect people with ASD.[24]
While the elderly may have cardiac problems due to noise, according to the World Health Organization, children are especially vulnerable to noise, and the effects that noise has on children may be permanent.[27] Noise poses a serious threat to a child's physical and psychological health, and may negatively interfere with a child's learning and behavior.[28] Exposure to persistent noise pollution shows how important maintaining environmental health is in keeping children and elderly healthy.[29]
### Wildlife
For many marine organisms, sound is the primary means of learning about their environments. For example, many species of marine mammals and fish use sound as their primary means of navigating, communicating, and foraging.[30] Anthropogenic noise can have a detrimental effect on animals, increasing the risk of death by changing the delicate balance in predator or prey detection[31] and avoidance, and interfering with the use of the sounds in communication, especially in relation to reproduction, and in navigation and echolocation.[32] These effects then may alter more interactions within a community through indirect ("domino") effects.[33] Acoustic overexposure can lead to temporary or permanent loss of hearing.
European robins living in urban environments are more likely to sing at night in places with high levels of noise pollution during the day, suggesting that they sing at night because it is quieter, and their message can propagate through the environment more clearly.[34] The same study showed that daytime noise was a stronger predictor of nocturnal singing than night-time light pollution, to which the phenomenon often is attributed. Anthropogenic noise reduced the species richness of birds found in Neotropical urban parks.[35]
Zebra finches become less faithful to their partners when exposed to traffic noise. This could alter a population's evolutionary trajectory by selecting traits, sapping resources normally devoted to other activities and thus leading to profound genetic and evolutionary consequences.[36]
Underwater noise pollution due to human activities is also prevalent in the sea, and given that sound travels faster through water than through air, is a major source of disruption of marine ecosystems and does significant harm to sea life, including marine mammals, fish and invertebrates.[37][38] The once-calm sea environment is now noisy and chaotic due to ships, oil drilling, sonar equipment, and seismic testing.[39] The principal anthropogenic noise sources come from merchant ships, naval sonar operations, underwater explosions (nuclear), and seismic exploration by oil and gas industries.[40]
Cargo ships generate high levels of noise due to propellers and diesel engines.[41][42] This noise pollution significantly raises the low-frequency ambient noise levels above those caused by wind.[43] Animals such as whales that depend on sound for communication can be affected by this noise in various ways. Higher ambient noise levels also cause animals to vocalize more loudly, which is called the Lombard effect. Researchers have found that humpback whales' song lengths were longer when low-frequency sonar was active nearby.[44]
Underwater noise pollution is not only limited to oceans, and can occur in freshwater environments as well. Noise pollution has been detected in the Yangzte River, and has resulted in the endangerment of Yangtze finless porpoises.[45] A study conducted on noise pollution in the Yangzte River suggested that the elevated levels of noise pollution altered the temporal hearing threshold of the finless porpoises and posed a significant threat to their survival.[45]
Noise pollution may have caused the death of certain species of whales that beached themselves after being exposed to the loud sound of military sonar.[46] (see also Marine mammals and sonar) Even marine invertebrates, such as crabs (Carcinus maenas), have been shown to be negatively affected by ship noise.[47][48] Larger crabs were noted to be negatively affected more by the sounds than smaller crabs. Repeated exposure to the sounds did lead to acclimatization.[48]
#### Why invertebrates are affected
Several reasons have been identified relating to hypersensitivity in invertebrates when exposed to anthropogenic noise. Invertebrates have evolved to pick up sound, and a large portion of their physiology is adapted for the purpose of detecting environmental vibrations.[49] Antennae or hairs on the organism pick up particle motion.[50] Anthropogenic noise created in the marine environment, such as pile driving and shipping, are picked up through particle motion; these activities exemplify near-field stimuli.[50]
The ability to detect vibration through mechanosensory structures is most important in invertebrates and fish. Mammals, also, depend on pressure detector ears to perceive the noise around them.[50] Therefore, it is suggested that marine invertebrates are likely perceiving the effects of noise differently than marine mammals. It is reported that invertebrates can detect a large range of sounds, but noise sensitivity varies substantially between each species. Generally, however, invertebrates depend on frequencies under 10 kHz. This is the frequency at which a great deal of ocean noise occurs.[51]
Therefore, not only does anthropogenic noise often mask invertebrate communication, but it also negatively impacts other biological system functions through noise-induced stress.[49] Another one of the leading causes of noise effects in invertebrates is because sound is used in multiple behavioral contexts by many groups. This includes regularly sound produced or perceived in the context of aggression or predator avoidance. Invertebrates also utilize sound to attract or locate mates, and often employ sound in the courtship process.[49]
#### Stress recorded in physiological and behavioral responses
An exaggerated sound from machines used for the care of greenery. A four-story apartments complex area in Tomaszów Mazowiecki, Poland
Many of the studies that were conducted on invertebrate exposure to noise found that a physiological or behavioral response was triggered. Most of the time, this related to stress, and provided concrete evidence that marine invertebrates detect and respond to noise. Some of the most informative studies in this category focus on hermit crabs. In one study, it was found that the behavior of the hermit crab Pagurus bernhardus, when attempting to choose a shell, was modified when subjected to noise.[52]
Proper selection of hermit crab shells strongly contributes to their ability to survive. Shells offer protection against predators, high salinity and desiccation.[52] However, researchers determined that approach to shell, investigation of shell, and habitation of shell, occurred over a shorter time duration with anthropogenic noise as a factor. This indicated that assessment and decision-making processes of the hermit crab were both altered, even though hermit crabs are not known to evaluate shells using any auditory or mechanoreception mechanisms.[52]
In another study that focused on Pagurus bernhardus and the blue mussel, (Mytilus edulis) physical behaviors exhibited a stress response to noise. When the hermit crab and mussel were exposed to different types of noise, significant variation in the valve gape occurred in the blue mussel.[53] The hermit crab responded to the noise by lifting the shell off of the ground multiple times, then vacating the shell to examine it before returning inside.[53] The results from the hermit crab trials were ambiguous with respect to causation; more studies must be conducted in order to determine whether the behavior of the hermit crab can be attributed to the noise produced.
Another study that demonstrates a stress response in invertebrates was conducted on the squid species Doryteuthis pealeii. The squid was exposed to sounds of construction known as pile driving, which impacts the sea bed directly and produces intense substrate-borne and water-borne vibrations.[54] The squid reacted by jetting, inking, pattern change and other startle responses.[55] Since the responses recorded are similar to those identified when faced with a predator, it is implied that the squid initially viewed the sounds as a threat. However, it was also noted that the alarm responses decreased over a period of time, signifying that the squid had likely acclimated to the noise.[55] Regardless, it is apparent that stress occurred in the squid, and although further investigation has not been pursued, researchers suspect that other implications exist that may alter the squid's survival habits.[55]
An additional study examined the impact noise exposure had on the Indo-Pacific humpbacked dolphin (Sousa chinensis). The dolphins were exposed to elevated noise levels due to construction in the Pearl River Estuary in China, specifically caused by the world's largest vibration hammer—the OCTA-KONG.[56] The study suggested that while the dolphin's clicks were not affected, their whistles were because of susceptibility to auditory masking.[56] The noise from the OCTA-KONG was found to have been detectable by the dolphins up to 3.5 km away from the original source, and while the noise was not found to be life-threatening it was indicated that prolonged exposure to this noise could be responsible for auditory damage.[56]
### Impacts on communication
Terrestrial anthropogenic noise affects the acoustic communications in grasshoppers while producing sound to attract a mate. The fitness and reproductive success of a grasshopper is dependent on its ability to attract a mating partner. Male Corthippus biguttulus grasshoppers attract females by using stridulation to produce courtship songs.[57] The females produce acoustic signals that are shorter and primarily low frequency and amplitude, in response to the male's song. Research has found that this species of grasshopper changes its mating call in response to loud traffic noise. Lampe and Schmoll (2012) found that male grasshoppers from quiet habitats have a local frequency maximum of about 7319 Hz.[57]
In contrast, male grasshoppers exposed to loud traffic noise can create signals with a higher local frequency maximum of 7622 Hz. The higher frequencies are produced by the grasshoppers to prevent background noise from drowning out their signals. This information reveals that anthropogenic noise disturbs the acoustic signals produced by insects for communication.[57] Similar processes of behavior perturbation, behavioral plasticity, and population level shifts in response to noise likely occur in sound-producing marine invertebrates, but more experimental research is needed.[53][54]
### Impacts on development
Boat-noise has been shown to affect the embryonic development and fitness of the sea hare Stylocheilus striatus.[58] Anthropogenic noise can alter conditions in the environment that have a negative effect on invertebrate survival. Although embryos can adapt to normal changes in their environment, evidence suggests they are not well adapted to endure the negative effects of noise pollution. Studies have been conducted on the sea hare to determine the effects of boat noise on the early stages of life and the development of embryos. Researchers have studied sea hares from the lagoon of Moorea Island, French Polynesia. In the study, recordings of boat noise were made by using a hydrophone.[58] In addition, recordings of ambient noise were made that did not contain boat noise. In contrast to ambient noise playbacks, mollusks exposed to boat noise playbacks had a 21% reduction in embryonic development. Additionally, newly hatched larvae experienced an increased mortality rate of 22% when exposed to boat noise playbacks.[58]
### Impacts on ecosystem
Anthropogenic noise can have negative effects on invertebrates that aid in controlling environmental processes that are crucial to the ecosystem. There are a variety of natural underwater sounds produced by waves in coastal and shelf habitats, and biotic communication signals that do not negatively impact the ecosystem. The changes in behavior of invertebrates vary depending on the type of anthropogenic noise and is similar to natural noisescapes.[59]
Experiments have examined the behavior and physiology of the clam (Ruditapes philippinarum), the decapod (Nephrops norvegicus), and the brittlestar (Amphiura filiformis) that are affected by sounds resembling shipping and building noises.[59] The three invertebrates in the experiment were exposed to continuous broadband noise and impulsive broadband noise. The anthropogenic noise impeded the bioirrigation and burying behavior of Nephrops norvegicus. In addition, the decapod exhibited a reduction in movement. Ruditapes philippinarum experienced stress which caused a reduction in surface relocation.[59] The anthropogenic noise caused the clams to close their valves and relocate to an area above the interface of the sediment-water. This response inhibits the clam from mixing the top layer of the sediment profile and hinders suspension feeding. Sound causes Amphiura filiformis to experience changes in physiological processes which results in irregularity of bioturbation behavior.[59]
These invertebrates play an important role in transporting substances for benthic nutrient cycling.[59] As a result, ecosystems are negatively impacted when species cannot perform natural behaviors in their environment. Locations with shipping lanes, dredging, or commercial harbors are known as continuous broadband sound. Pile-driving, and construction are sources that exhibit impulsive broadband noise. The different types of broadband noise have different effects on the varying species of invertebrates and how they behave in their environment.[59]
Another study found that the valve closures in the Pacific oyster Magallana gigas was a behavioral response to varying degrees of acoustic amplitude levels and noise frequencies.[60] Oysters perceive near-field sound vibrations by utilizing statocysts. In addition, they have superficial receptors that detect variations in water pressure. Sound pressure waves from shipping can be produced below 200Hz. Pile driving generates noise between 20 and 1000 Hz. In addition, large explosions can create frequencies ranging from 10 to 200Hz. M. gigas can detect these noise sources because their sensory system can detect sound in the 10 to < 1000Hz range.[60]
The anthropogenic noise produced by human activity has been shown to negatively impact oysters.[60] Studies have revealed that wide and relaxed valves are indicative of healthy oysters. The oysters are stressed when they do not open their valves as frequently in response to environmental noise. This provides support that the oysters detect noise at low acoustic energy levels.[60] While we generally understand that marine noise pollution influences charismatic megafauna like whales and dolphins, understanding how invertebrates like oysters perceive and respond to human generated sound can provide further insight about the effects of anthropogenic noise on the larger ecosystem.[60] The aquatic ecosystems are known to use sound to navigate, find food, and protect themselves. In 2020, one of the worst mass stranding of whales occurred in Australia. Experts suggest that noise pollution plays a major role in the mass stranding of whales.[61]
## Noise assessment
### Metrics of noise
Researchers measure noise in terms of pressure, intensity, and frequency. Sound pressure level (SPL) represents the amount of pressure relative to atmospheric pressure during sound wave propagation that can vary with time; this is also known as the sum of the amplitudes of a wave.[62] Sound intensity, measured in Watts per meters-squared, represents the flow of sound over a particular area. Although sound pressure and intensity differ, both can describe the level of loudness by comparing the current state to the threshold of hearing; this results in decibel units on the logarithmic scale.[63][64] The logarithmic scale accommodates the vast range of sound heard by the human ear.
Depiction of frequency weighting
Frequency, or pitch, is measured in Hertz (Hz) and reflects the number of sound waves propagated through the air per second.[63][65] The range of frequencies heard by the human ear range from 20 Hz to 20,000 Hz; however, sensitivity to hearing higher frequencies decreases with age.[63] Some organisms, such as elephants,[66] can register frequencies between 0 and 20 Hz (infrasound), and others, such as bats, can recognize frequencies above 20,000 Hz (ultrasound) to echolocate.[65][67]
Researchers use different weights to account for noise frequency with intensity, as humans do not perceive sound at the same loudness level.[63] The most commonly used weighted levels are A-weighting, C-weighting, and Z-weighting. A-weighting mirrors the range of hearing, with frequencies of 20 Hz to 20,000 Hz.[63] This gives more weight to higher frequencies and less weight to lower frequencies.[63][68] C-weighting has been used to measure peak sound pressure or impulse noise, similar to loud short-lived noises from machinery in occupational settings.[68][69] Z-weighting, also known as zero-weighting, represents noise levels without any frequency weights.[68][69]
Understanding sound pressure levels is key to assessing measurements of noise pollution. Several metrics describing noise exposure include:
• Energy average equivalent level of the A-weighted sound, LAeq: This measures the average sound energy over a given period for constant or continuous noise, such as road traffic.[63] LAeq can be further broken up into different types of noise based on time of day; however, cutoffs for evening and nighttime hours may differ between countries, with the United States, Belgium, and New Zealand noting evening hours from 19:00-22:00 or 7:00pm–10:00pm and nighttime hours from 22:00-7:00 or 10:00pm–7:00am and most European countries noting evening hours from 19:00-23:00 or 7:00pm–11:00pm and nighttime hours from 23:00-7:00 or 11:00pm–7:00am).[70] LAeq terms include:
• Day-night average level, DNL or LDN: This measurement assesses the cumulative exposure to sound for a 24-hour period (Leq over 24 hrs) of the year, with a 10 dB(A) penalty or weight added to nighttime noise measurements given the increased sensitivity to noise at night. This is calculated from the following equation (United States, Belgium, New Zealand):[71]${\displaystyle L_{dn}=10\cdot \log _{10}{\frac {1}{24}}\left(15\cdot 10^{\frac {L_{day}}{10}}+9\cdot 10^{\frac {L_{night}+10}{10}}\right)}$
• Day-evening-night average level, DENL or Lden: This measurement, commonly used in European countries, assesses the 24 hour average in a year (similar to DNL); however, this measurement separates evening (4 hours, 19:00-23:00 or 7:00pm–11:00pm) from night hours (8 hours, 23:00-7:00 or 11:00pm–7:00am) and adds a 5 dB penalty to evening and 10 dB penalty to nighttime hours. This is calculated from the following equation (most of Europe):[63][70] ${\displaystyle L_{den}=10\cdot \log _{10}{\frac {1}{24}}\left(12\cdot 10^{\frac {L_{day}}{10}}+4\cdot 10^{\frac {L_{evening}+5}{10}}+8\cdot 10^{\frac {L_{night}+10}{10}}\right)}$
• Daytime level, LAeqD or Lday: This measurement assesses daytime noise, usually from 7:00-19:00 (7am-7pm), yet may vary by country.[71]
• Nighttime level, LAeqN or Lnight: This measurement assesses nighttime noise, depending on country cutoff hours discussed above.
• Maximum level, LAmax: This measurement represents the maximal noise level when examining point sources or single events of noise; however, this value does not factor in duration of the event.[63][72]
• Sound exposure level of A-weighted sound, SEL: This measurement represents the total energy for a particular event. SEL is used to describe discrete events in terms of A-weighted sound. The difference between SEL and LAmax is that SEL is derived using multiple time points of a particular event in calculating sound levels rather than the peak value.[63]
• Percentile-derived measurements (L10, L50, L90, etc.): Noise may be described in terms of its statistical distribution over a set time, in which investigators may obtain values, or cut-points, at any percentile level. The L90 is the sound level that exceeds 90% of the time period; this is commonly referred to as background noise.[63]
Researchers with the US National Park Service found that human activity doubles the background-noise levels in 63 percent of protected spaces like national parks, and increases them tenfold in 21 percent. In the latter places, “if you could have heard something 100 feet away, now you can only hear it 10 feet away,”[73][74]
### Instrumentation
A sound level meter is one of the main tools for measuring sounds in the environment and the workplace.
#### Sound level meters
Sound can be measured in the air using a sound level meter, a device consisting of a microphone, an amplifier, and a time meter.[75] Sound level meters can measure noise at different frequencies (usually A- and C-weighted levels).[63] There are two settings for response time constants, fast (time constant = 0.125 seconds, similar to human hearing) or slow (1 second, used for calculating averages over widely varying sound levels).[63] Sound level meters meet the required standards set by the International Electrotechnical Commission (IEC)[76] and in the United States, the American National Standards Institute as type 0, 1, or 2 instruments.[77]
Type 0 devices are not required to meet the same criteria expected of types 1 and 2 since scientists use these as laboratory reference standards.[77] Type 1 (precision) instruments are to study the precision of capturing sound measurements, while type 2 instruments are for general field use.[77] Type 1 devices acceptable by the standards have a margin of error of ±1.5 dB, while type 2 instruments meet a margin of error of ±2.3 dB.[77]
#### Dosimeters
Sound can also be measured using a noise dosimeter, a device similar to a sound level meter. Individuals have used dosimeters to measure personal exposure levels in occupational settings given their smaller, more portable size. Unlike many sound level meters, a dosimeter microphone attaches to the worker and monitors levels throughout a work shift.[78] Additionally, dosimeters can calculate the percent dose or time-weighted average (TWA).[78]
#### Smartphone applications
Measuring the moise level from a leaf blower, using the NIOSH Sound Level Meter app
In recent years, scientists and audio engineers have been developing smartphone apps to conduct sound measurements, similar to the standalone sound level meters and dosimeters. In 2014, the National Institute for Occupational Safety and Health (NIOSH) within the Centers for Disease Control and Prevention (CDC) published a study examining the efficacy of 192 sound measurement apps on Apple and Android smartphones.[79][80]
The authors found that only 10 apps, all of which were on the App Store, met all acceptability criteria. Of these 10 apps, only 4 apps met accuracy criteria within 2 dB(A) from the reference standard.[79][80] As a result of this study, they created the NIOSH Sound Level Meter App to increase accessibility and decrease costs of monitoring noise using crowdsourcing data with a tested and highly accurate application.[79][80] The app is compliant with ANSI S1.4 and IEC 61672 requirements.[81]
The app calculates the following measures: total run time, instantaneous sound level, A-weighted equivalent sound level (LAeq), maximum level (LAmax), C-weighted peak sound level, time-weighted average (TWA), dose, and projected dose.[79] Dose and projected dose are based on sound level and duration of noise exposure in relation to the NIOSH recommended exposure limit of 85 dB(A) for an eight-hour work shift.
Using the phone's internal microphone (or an attached external microphone), the NIOSH Sound Level Meter measures instantaneous sound levels in realtime and converts sound into electrical energy to calculate measurements in A-, C-, or Z-weighted decibels. App users are able to generate, save, and e-mail measurement reports. The NIOSH Sound Level Meter is currently only available on Apple iOS devices.
## Noise control
The CityLink sound tube in Flemington, Melbourne, Australia, is designed to reduce roadway noise without detracting from the area's aesthetics.
A man inserting an earplug in his ear to reduce the noise exposure
The Hierarchy of Controls concept is often used to reduce noise in the environment or the workplace. Engineering noise controls can be used to reduce noise propagation and protect individuals from overexposure. When noise controls are not feasible or adequate, individuals can also take steps to protect themselves from the harmful effects of noise pollution. If people must be around loud sounds, they can protect their ears with hearing protection (e.g., ear plugs or ear muffs).[82]
Buy Quiet programs and initiatives have arisen in an effort to combat occupational noise exposures. These programs promote the purchase of quieter tools and equipment and encourage manufacturers to design quieter equipment.[83]
Noise from roadways and other urban factors can be mitigated by urban planning and better design of roads. Roadway noise can be reduced by the use of noise barriers, limitation of vehicle speeds, alteration of roadway surface texture, limitation of heavy vehicles, use of traffic controls that smooth vehicle flow to reduce braking and acceleration, and tire design.
An important factor in applying these strategies is a computer model for roadway noise, that is capable of addressing local topography, meteorology, traffic operations, and hypothetical mitigation. Costs of building-in mitigation can be modest, provided these solutions are sought in the planning stage of a roadway project.
Aircraft noise can be reduced by using quieter jet engines. Altering flight paths and time of day runway has benefited residents near airports.
## Legal status and regulation
### Country-specific regulations
Up until the 1970s governments tended to view noise as a "nuisance" rather than an environmental problem.
Many conflicts over noise pollution are handled by negotiation between the emitter and the receiver. Escalation procedures vary by country, and may include action in conjunction with local authorities, in particular the police.
#### Egypt
In 2007, the Egyptian National Research Center found that the average noise level in central Cairo was 90 decibels and that the noise never fell below 70 decibels. Noise limits set by law in 1994 are not enforced.[84] In 2018, the World Hearing Index declared Cairo to be the world's second-noisiest city.[85]
#### India
Noise pollution is a major problem in India.[86] The government of India has rules and regulations against firecrackers and loudspeakers, but enforcement is extremely lax.[87] Awaaz Foundation is a non-governmental organization in India working to control noise pollution from various sources through advocacy, public interest litigation, awareness, and educational campaigns since 2003.[88] Despite increased enforcement and stringency of laws now being practiced in urban areas, rural areas are still affected.[89]
The Supreme Court of India had banned playing of music on loudspeakers after 10pm. In 2015, The National Green Tribunal directed authorities in Delhi to ensure strict adherence to guidelines on noise pollution, saying noise is more than just a nuisance as it can produce serious psychological stress. However, implementation of the law remains poor.[90]
#### Sweden
How noise emissions should be reduced, without the industry being hit too hard, is a major problem in environmental care in Sweden today. The Swedish Work Environment Authority has set an input value of 80 dB for maximum sound exposure for eight hours. In workplaces where there is a need to be able to converse comfortably the background noise level should not exceed 40 dB.[91] The government of Sweden has taken soundproofing and acoustic absorbing actions, such as noise barriers and active noise control.
#### United Kingdom
Figures compiled by rockwool, the mineral wool insulation manufacturer, based on responses from local authorities to a Freedom of Information Act (FOI) request reveal in the period April 2008 – 2009 UK councils received 315,838 complaints about noise pollution from private residences. This resulted in environmental health officers across the UK serving 8,069 noise abatement notices or citations under the terms of the Anti-Social Behavior (Scotland) Act. In the last 12 months, 524 confiscations of equipment have been authorized involving the removal of powerful speakers, stereos and televisions. Westminster City Council has received more complaints per head of population than any other district in the UK with 9,814 grievances about noise, which equates to 42.32 complaints per thousand residents. Eight of the top 10 councils ranked by complaints per 1,000 residents are located in London.[92]
#### United States
The Noise Control Act of 1972 established a U.S. national policy to promote an environment for all Americans free from noise that jeopardizes their health and welfare. In the past, Environmental Protection Agency coordinated all federal noise control activities through its Office of Noise Abatement and Control. The EPA phased out the office's funding in 1982 as part of a shift in federal noise control policy to transfer the primary responsibility of regulating noise to state and local governments. However, the Noise Control Act of 1972 and the Quiet Communities Act of 1978 were never rescinded by Congress and remain in effect today, although essentially unfunded.[93]
The National Institute for Occupational Safety and Health (NIOSH) at the Centers for Disease Control and Prevention (CDC) researches noise exposure in occupational settings and recommends a Recommended Exposure Limit (REL) for an 8-hour time-weighted average (TWA) or work shift of 85 dB(A) and for impulse noise (instant events such as bangs or crashes) of 140 dB(A).[20][78] The agency published this recommendation along with its origin, noise measurement devices, hearing loss prevention programs, and research needs in 1972 (later revised June 1998) as an approach in preventing occupational noise-related hearing loss.[78]
The Occupational Safety and Health Administration (OSHA) within the Department of Labor issues enforceable standards to protect workers from occupational noise hazards. The permissible exposure limit (PEL) for noise is a TWA of 90 dB(A) for an eight-hour work day.[79][94] However, in manufacturing and service industries, if the TWA is greater than 85 dB(A), employers must implement a Hearing Conservation Program.[94]
The Federal Aviation Administration (FAA) regulates aircraft noise by specifying the maximum noise level that individual civil aircraft can emit through requiring aircraft to meet certain noise certification standards. These standards designate changes in maximum noise level requirements by "stage" designation. The U.S. noise standards are defined in the Code of Federal Regulations (CFR) Title 14 Part 36 – Noise Standards: Aircraft Type and Airworthiness Certification (14 CFR Part 36).[95] The FAA also pursues a program of aircraft noise control in cooperation with the aviation community.[96] The FAA has set up a process to report for anyone who may be impacted by aircraft noise.[97]
The Federal Highway Administration (FHWA) developed noise regulations to control highway noise as required by the Federal-Aid Highway Act of 1970. The regulations requires promulgation of traffic noise-level criteria for various land use activities, and describe procedures for the abatement of highway traffic noise and construction noise.[98]
The Department of Housing and Urban Development (HUD) noise standards as described in 24 CFR part 51, Subpart B provides minimum national standards applicable to HUD programs to protect citizen against excessive noise in their communities and places of residence. For instance, all sites whose environmental or community noise exposure exceeds the day night average sound level (DNL) of 65 (dB) are considered noise-impacted areas, it defines "Normally Unacceptable" noise zones where community noise levels are between 65 and 75 dB, for such locations, noise abatement and noise attenuation features must be implemented. Locations where the DNL is above 75 dB are considered "Unacceptable" and require approval by the Assistant Secretary for Community Planning and Development.[99]
The Department of Transportation's Bureau of Transportation Statistics has created a to provide access to comprehensive aircraft and road noise data on national and county levels.[100] The map aims to assist city planners, elected officials, scholars, and residents to gain access to up-to-date aviation and Interstate highway noise information.[101]
States and local governments typically have very specific statutes on building codes, urban planning, and roadway development. Noise laws and ordinances vary widely among municipalities and indeed do not even exist in some cities. An ordinance may contain a general prohibition against making noise that is a nuisance, or it may set out specific guidelines for the level of noise allowable at certain times of the day and for certain activities.[102] Noise laws classify sound into three categories. First is ambient noise, which refers to sound pressure of all-encompassing noise associated with a given environment. The second is continuous noise, which could be steady or fluctuating, but continues for more than an hour. The third is cyclically varying noise, which could be steady or fluctuating, but occurs repetitively at reasonably uniform intervals of time.[103]
New York City instituted the first comprehensive noise code in 1985. The Portland Noise Code includes potential fines of up to \$5000 per infraction and is the basis for other major U.S. and Canadian city noise ordinances.[104]
### World Health Organization
#### European Region
In 1995, the World Health Organization (WHO) European Region released guidelines on regulating community noise.[63] The WHO European Region subsequently released other versions of the guidelines, with the most recent version circulated in 2018.[105] The guidelines provide the most up-to-date evidence from research conducted in Europe and other parts of the world on non-occupational noise exposure and its relationship to physical and mental health outcomes. The guidelines provide recommendations for limits and preventive measures regarding various noise sources (road traffic, railway, aircraft, wind turbine) for day-evening-night average and nighttime average levels. Recommendations for leisure noise in 2018 were conditional and based on the equivalent sound pressure level during an average 24-hour period in a year without weights for nighttime noise (LAeq, 24 hrs); WHO set the recommended limit to 70 dB(A).[105]
2018 WHO European Regional Office Environmental Noise Guidelines[105]
Noise Source Recommendation for
Day-Evening-Night Average Level (Lden)
Recommendation for
Nighttime Average Noise (Lnight)
Road traffic 53 dB(A) 45 dB(A)
Rail 54 dB(A) 44 dB(A)
Aircraft 45 dB(A) 40 dB(A)
Wind turbine 45 dB(A) no recommendation
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• Robert Bartholomew (1974), Sonic environment and human behavior, Exchange Bibliography, US: Council of Planning Librarians – via Internet Archive
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http://tex.stackexchange.com/questions/98569/general-question-on-floating-and-non-floating-objects-in-latex
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# General question on floating and non-floating objects in LaTeX
I am wondering when you place a non-floating object such as a minipage into a floating environment such as a table or figure if this construction as a whole is then a floating or a non-floating object?
Example:
\begin{table}
\begin{minipage}
...
\end{minipage}
\begin{minipage}
...
\end{minipage}
\end{table}
Is this table considered to be a floating object or in different words, is this object still floating?
-
A minipage environment, just like \parbox, \mbox, \makebox and similar commands creates an object that to LaTeX is almost like a big letter. The same holds for tabular.
A floating object is one that LaTeX defers the positioning of, typically table or figure (and other similar floats that can be defined with packages such as newfloat or are defined by packages such as algorithm and listings).
Each floating object is essentially a chunk of copy that is momentarily stored in memory for being placed accordingly to LaTeX rules. It can contain anything that can go in normal text, including minipage, tabular and so on. The only restriction is that a float cannot contain another float and page breaking instructions (that make no sense in them).
Let's see an example that often confuses beginners. Typically, a figure float has this structure
\begin{figure}
\centering
\includegraphics{file}
\caption{A caption}\label{label}
\end{figure}
This declares a float that LaTeX will place according to its rules. However, \includegraphics by itself is a command similar to \mbox and so can go anywhere: to the eyes of LaTeX it's a "big letter". In the case of a figure we can see it: LaTeX builds a paragraph (with center "justification") consisting only of one big letter. The caption is, by rule, a differently built object.
Thus the answer to your question is yes: table is a floating object, whatever it contains.
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wow, that's an amazing explanation to my simple question. thanks a lot for clarifying that. I now know even more than actually requested :-) Many thanks! – Josh Feb 17 '13 at 10:42
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https://worldwidescience.org/topicpages/f/facility+barking+sands.html
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#### Sample records for facility barking sands
1. 78 FR 27124 - Pacific Ocean Off the Kekaha Range Facility at Barking Sands, Island of Kauai, Hawaii; Danger Zone
Science.gov (United States)
2013-05-09
... Barking Sands, Island of Kauai, Hawaii; Danger Zone AGENCY: U.S. Army Corps of Engineers, DoD. ACTION... amend its regulations to establish a new danger zone in waters of the Pacific Ocean off the Kekaha Range... INFORMATION: Executive Summary The purpose of this regulatory action is to establish a new danger zone...
2. Learning Design at White Sands Test Facility
Science.gov (United States)
Grotewiel, Shane
2010-01-01
During the Fall of 2010, I spent my time at NASA White Sands Test Facility in Las Cruces, NM as an Undergraduate Student Research Program (USRP) Intern. During that time, I was given three projects to work on: Large Altitude Simulation System (LASS) basket strainer, log books, and the design of a case for touch screen monitors used for simulations. I spent most of my time on the LASS basket strainer. The LASS system has a water feed line with a basket strainer that filters out rust. In 2009, there were three misfires which cost approximately 27,000 and about 8% of the allotted time. The strainer was getting a large change in pressure that would result in a shutdown of the system. I have designed a new basket that will eliminate the large pressure change and it can be used with the old basket strainer housing. The LASS system has three steam generators (modules). Documents pertaining to these modules are stored electronically, and the majority of the documents are not able to be searched with keywords, so they have to be gone through one by one. I have come up with an idea on how to organize these files so that the Propulsion Department may efficiently search through the documents needed. Propulsion also has a LASS simulator that incorporates two touch screen monitors. Currently these monitors are in six foot by two foot metal cabinet on wheels. During simulation these monitors are used in the block house and need to be taken out of the block house when not in use. I have designed different options for hand held cases for storing and transporting the monitors in and out of the block house. The three projects previously mentioned demonstrate my contributions to the Propulsion Department and have taught me real world experience that is essential in becoming a productive engineer. 3. Groundwater Remediation and Alternate Energy at White Sands Test Facility Science.gov (United States) Fischer, Holger 2008-01-01 White Sands Test Facility Core Capabilities: a) Remote Hazardous Testing of Reactive, Explosive, and Toxic Materials and Fluids; b) Hypergolic Fluids Materials and Systems Testing; c) Oxygen Materials and System Testing; d) Hypervelocity Impact Testing; e)Flight Hardware Processing; and e) Propulsion Testing. There is no impact to any drinking water well. Includes public wells and the NASA supply well. There is no public exposure. Groundwater is several hundred feet below ground. No air or surface water exposure. Plume is moving very slowly to the west. Plume Front Treatment system will stop this westward movement. NASA performs on-going monitoring. More than 200 wells and zones are routinely sampled. Approx. 850 samples are obtained monthly and analyzed for over 300 different hazardous chemicals. 4. Sand Dune Movement in Xinjiang of Northwest China and Prevention of Desertification by Windbreak Facilities in Arid Lands National Research Council Canada - National Science Library T. MAKI; M. DU; R. SAMESHIMA; B. PAN 1996-01-01 .... There are various countermeasure against desertification in arid lands of the world. In this paper, we demonstrated the situation of sand erosion and movement of sand dunes, and we propose the prevention method by using windbreak facilities, i. e... 5. AVTA Federal Fleet PEV Readiness Data Logging and Characterization Study for NASA White Sands Test Facility Energy Technology Data Exchange (ETDEWEB) Schey, Stephen [Idaho National Lab. (INL), Idaho Falls, ID (United States); Francfort, Jim [Idaho National Lab. (INL), Idaho Falls, ID (United States) 2014-10-01 This report focuses on the NASA White Sands Test Facility (WSTF) fleet to identify daily operational characteristics of select vehicles and report findings on vehicle and mission characterizations to support the successful introduction of plug-in electric vehicles (PEVs) into the agencies’ fleets. Individual observations of these selected vehicles provide the basis for recommendations related to electric vehicle adoption and whether a battery electric vehicle (BEV) or plug-in hybrid electric vehicle (PHEV) (collectively plug-in electric vehicles, or PEVs) can fulfill the mission requirements. 6. Bark Beetles OpenAIRE Davis, Ryan S.; McAvoy, Darren 2012-01-01 Bark beetles are one of the most destructive forest pests in the world. They are different than the larger longhorned and roundheaded/metallic woodboring beetles commonly infesting the inner wood of trees. The largest bark beetle, the red turpentine beetle (Dendroctonus valens), reaches only 8.3 mm in length. Because of their tiny size, bark beetles are not effective tree killers as individuals. 7. 78 FR 76060 - Pacific Ocean off the Pacific Missile Range Facility at Barking Sands, Island of Kauai, Hawaii... Science.gov (United States) 2013-12-16 ... amendment to the regulation will not have a significant impact to the quality of the human environment and... activities, increases in force protection and other mission-essential evolutions without first obtaining...-essential evolutions. Residents and visitors who typically use these waters off Pacific Missile... 8. 78 FR 39198 - Pacific Ocean Off the Pacific Missile Range Facility at Barking Sands, Island of Kauai, Hawaii... Science.gov (United States) 2013-07-01 ... this regulation, if adopted, will not have a significant impact to the quality of the human environment... evolutions. The expanded danger zone would extend along approximately seven miles of shoreline adjacent to... activities, increases in force protection and other mission essential evolutions. The expanded danger... 9. Facile sand enhanced electro-flocculation for cost-efficient harvesting of Dunaliella salina. Science.gov (United States) Xiong, Qiong; Pang, Qi; Pan, Xinwei; Chika, A Okonkwo; Wang, Liqing; Shi, Jia; Jia, Lishan; Chen, Changping; Gao, Yahui 2015-01-01 Energy consumption and water resource in the cultivation and harvesting steps still need to be minimized for the popularization of the microalgae-based products. An efficient electro-flocculation method for harvesting Dunaliella Salina integrated with local sand has been successfully applied. Sand was effective for speeding up the processes of flocculation and sedimentation of algal flocs and the electrolytic hydroxides was essential to bridge the sand and small flocs into large dense flocs. The maximal recovery effective improved from 95.13% in 6min to 98.09% in 4.5min and the optimal electrical energy consumption decreased 51.03% compared to conventional electro-flocculation in a laboratory ambient condition. Furthermore, reusing the flocculated medium in cultivation of the D. Salina with nitrogen supplemented performed no worse than using fresh medium. This sand enhanced electro-flocculation (SEF) technology provides a great potential for saving time and energy associated with improving microalgae harvesting. 10. A Facile and Low-Cost Route to Heteroatom Doped Porous Carbon Derived from Broussonetia Papyrifera Bark with Excellent Supercapacitance and CO2 Capture Performance. Science.gov (United States) Wei, Tongye; Zhang, Qi; Wei, Xiaolin; Gao, Yong; Li, Huaming 2016-03-03 In this work, we present a facile and low-cost approach to synthesize heteroatom doped porous carbon via hydrothermal treatment of stem bark of broussonetia papyrifera (BP) as the biomass precursor in diluted sulfuric acid, and following thermal activation by KOH at 800 °C. The morphology, structure and textural property of the prepared porous carbon (PC) are investigated by scanning electron microscopy, transmission electron microscopy, N2 sorption isotherms, and X-ray photoelectron spectroscopy. The porous carbon possesses a high BET surface area of 1759 m(2) g(-1) and an average pore size of 3.11 nm as well as hetero-oxygen (9.09%) and nitrogen (1.7%) doping. Such porous carbon shows outstanding capacitive performances of 416 F g(-1) and 300 F g(-1) in three and two-electrode systems, respectively. As a solid-state adsorbent, the obtained porous carbon has an excellent CO2 adsorption capacity at ambient pressures of up to 6.71 and 4.45 mmol g(-1) at 0 and 25 °C, respectively. The results present one novel precursor-synthesis route for facile large-scale production of high performance porous carbon for a variety of great applications including energy storage and CO2 capture. 11. Hydrogen and Storage Initiatives at the NASA JSC White Sands Test Facility Science.gov (United States) Maes, Miguel; Woods, Stephen S. 2006-01-01 NASA WSTF Hydrogen Activities: a) Aerospace Test; b) System Certification & Verification; c) Component, System, & Facility Hazard Assessment; d) Safety Training Technical Transfer: a) Development of Voluntary Consensus Standards and Practices; b) Support of National Hydrogen Infrastructure Development. 12. Emission rate estimates determined for a large number of volatile organic compounds using airborne measurements for the oil sands facilities in Alberta, Canada Science.gov (United States) Li, S. M.; Leithead, A.; Moussa, S.; Liggio, J.; Moran, M. D.; Wang, D. K.; Hayden, K. L.; Darlington, A.; Gordon, M.; Staebler, R. M.; Makar, P.; Stroud, C.; McLaren, R.; Liu, P.; O'brien, J.; Mittermeier, R. L.; Zhang, J.; Marson, G.; Cober, S.; Wolde, M.; Wentzell, J. 2016-12-01 In August and September of 2013, aircraft-based measurements of air pollutants were made during a field campaign in support of the Joint Canada-Alberta Implementation Plan on Oil Sands Monitoring in Alberta, Canada. Volatile organic compounds (VOCs) were determined using a high resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) continuously at 2-5 second resolution during the flights, and from 680 discretely sampled stainless steel canisters collected during flights followed by offline GC-MS and GC-FID analyses for four large oil sands surface mining facilities. The Top-down Emission Rate Retrieval Algorithm (TERRA), developed at Environment and Climate Change Canada (ECCC), was applied to the aromatics and oxygenated VOC results from the PTR-ToF-MS to determine their emission rates. Additional VOC species, determined in the canisters, were compared with the PTR-ToF-MS VOC species to determine their emission ratios. Using these emission ratios and the emission rates for the aromatics and oxygenated VOCs, the individual emission rates for 73-90 volatile organic compounds (VOCs) were determined for each of the four major oil sands facilities. The results are the first independently determined emission rates for a large number of VOCs at the same time for large industrial complexes such as the oil sands mining facilities. These measurement-based emission data will be important for strengthening VOC emission reporting. 13. Loblolly pine bark flavanoids Science.gov (United States) J.J. Karchesy; R.W. Hemingway 1980-01-01 The inner bark of Pinus taeda L. contains (+)-catechin, the procyanidin 8.1 (a C-4 to C-8 linked (-)-epicatechin to (+)-catechin dimer), and three polymeric procyanidins that have distinctly different solubility and chromatographic properties. An ethyl acetate soluble polymer (0.20% of bark, Mn = 1200) was purified by chromatography on LH-20 Sephadex. A water-soluble... 14. Barking and mobbing. Science.gov (United States) Lord, Kathryn; Feinstein, Mark; Coppinger, Raymond 2009-07-01 Barking is most often associated with the domestic dog Canis familiaris, but it is a common mammalian and avian vocalization. Like any vocalization, the acoustic character of the bark is likely to be a product of adaptation as well as an expression of the signaler's internal motivational state. While most authors recognize that the bark is a distinct signal type, no consistent description of its acoustic definition or function is apparent. The bark exhibits considerable variability in its acoustic form and occurs in a wide range of behavioral contexts, particularly in dogs. This has led some authors to suggest that dog barking might be a form of referential signaling, or an adaptation for heightened capability to communicate with humans. In this paper we propose a general 'canonical' acoustic description of the bark. Surveying relevant literature on dogs, wild canids, other mammals and birds, we explore an alternative functional hypothesis, first suggested by [Morton, E.S., 1977. On the occurrence and significance of motivation-structural rules in some bird and mammal sounds. Am. Nat. 111, 855-869] and consistent with his motivational-structural rules theory: that barking in many animals, including the domestic dog, is associated with mobbing behavior and the motivational states that accompany mobbing. 15. Bark beetle management guidebook Energy Technology Data Exchange (ETDEWEB) NONE 1995-12-31 This guidebook is designed to provide a background to bark beetle management practices consistent with the British Columbia Forest Practices Code, as well as specific practices for managing mountain pine beetle (Dendroctonus ponderosae), spruce beetle (Dendroctonus rufipennis), and Douglas-fir beetle (Dendroctonus pseudotsugae). It describes their general biology and distribution in British Columbia, their life cycles and population dynamics, and symptoms of bark beetle attack. General management strategies presented include prevention (a long-term approach), suppression, holding actions, and salvage. Strategies appropriate to specific bark beetles include aerial surveys, ground detection, baiting, harvesting, and use of insecticides. The guidebook includes brief mention of other bark beetles (Scolytids and other Dendroctonus species) and a glossary. 16. Case study : evaluation of oilfield and water well disposal well designs for oil sands facility in northern Alberta, Canada Energy Technology Data Exchange (ETDEWEB) Champollion, Y.; Gleixner, M.R.; Wozniewicz, J. [Golder Associates Ltd., Calgary, AB (Canada); MacFarlane, W.D.; Skulski, L. [Nexen Canada Ltd., Calgary, AB (Canada) 2003-07-01 Large volumes of wastewater disposal capacity will be required for the production of bitumen at the Long Lake Project, located in northeastern Alberta. An unconsolidated sand aquifer is the target formation for disposal. An evaluation of two disposal well designs, perforated casing (standard oil and gas approach), and wire-wound telescopic screen (standard water well approach) was performed. Skin, transmissivity and storability were the hydraulic parameters quantified. Full superposition type curves were used to conduct the transient analysis, along with the use of pressure derivative data. The results from the injection tests revealed that the sand aquifer at the Long Lake Project had suitable aquifer disposal capacity. The test results also revealed that clogging takes place in the vicinity of the wellbore, probably because of suspended solids in the injection water and the degassing effects. The water well design, as opposed to the standard oilfields well, makes provision for less costly re-development during operations, something that might be required if clogging problems occur. 3 refs., 8 figs. 17. experimental studies of sand production from unconsolidated ... African Journals Online (AJOL) ES Obe Production of sand during oil and gas exploration causes severe operational prob- ... duction such as risk of well failure, erosion of pipelines and surface facilities, sand separa- tion and disposal ... ment, theoretical and numerical analysis have. 18. Fontainebleau Sand DEFF Research Database (Denmark) Leth, Caspar Thrane 2006-01-01 The report is a summary of results from laboratory tests in the geotechncial research group on Fontainebleau sand.......The report is a summary of results from laboratory tests in the geotechncial research group on Fontainebleau sand.... 19. Amate Bark Designs Science.gov (United States) Mazur, Matt 2013-01-01 Inspired by a beautiful bookmark one of the author's students made for him as a gift, he began a lesson exploring the vibrant bark paintings popular all over Mexico. The majority of his students have Mexican ancestry, so exploring the arts of Mexico is always popular and well received. Amate paintings can also be a great way to introduce the… 20. Liquid Oxygen/Liquid Methane Test Summary of the RS-18 Lunar Ascent Engine at Simulated Altitude Conditions at NASA White Sands Test Facility Science.gov (United States) Melcher, John C., IV; Allred, Jennifer K. 2009-01-01 Tests were conducted with the RS18 rocket engine using liquid oxygen (LO2) and liquid methane (LCH4) propellants under simulated altitude conditions at NASA Johnson Space Center White Sands Test Facility (WSTF). This project is part of NASA s Propulsion and Cryogenics Advanced Development (PCAD) project. "Green" propellants, such as LO2/LCH4, offer savings in both performance and safety over equivalently sized hypergolic propellant systems in spacecraft applications such as ascent engines or service module engines. Altitude simulation was achieved using the WSTF Large Altitude Simulation System, which provided altitude conditions equivalent up to approx.120,000 ft (approx.37 km). For specific impulse calculations, engine thrust and propellant mass flow rates were measured. Propellant flow rate was measured using a coriolis-style mass-flow meter and compared with a serial turbine-style flow meter. Results showed a significant performance measurement difference during ignition startup. LO2 flow ranged from 5.9-9.5 lbm/sec (2.7-4.3 kg/sec), and LCH4 flow varied from 3.0-4.4 lbm/sec (1.4-2.0 kg/sec) during the RS-18 hot-fire test series. Thrust was measured using three load cells in parallel. Ignition was demonstrated using a gaseous oxygen/methane spark torch igniter. Data was obtained at multiple chamber pressures, and calculations were performed for specific impulse, C* combustion efficiency, and thrust vector alignment. Test objectives for the RS-18 project are 1) conduct a shakedown of the test stand for LO2/methane lunar ascent engines, 2) obtain vacuum ignition data for the torch and pyrotechnic igniters, and 3) obtain nozzle kinetics data to anchor two-dimensional kinetics codes. 1. Infrared Camera Characterization of Bi-Propellant Reaction Control Engines during Auxiliary Propulsion Systems Tests at NASA's White Sands Test Facility in Las Cruces, New Mexico Science.gov (United States) Holleman, Elizabeth; Sharp, David; Sheller, Richard; Styron, Jason 2007-01-01 This paper describes the application of a FUR Systems A40M infrared (IR) digital camera for thermal monitoring of a Liquid Oxygen (LOX) and Ethanol bi-propellant Reaction Control Engine (RCE) during Auxiliary Propulsion System (APS) testing at the National Aeronautics & Space Administration's (NASA) White Sands Test Facility (WSTF) near Las Cruces, New Mexico. Typically, NASA has relied mostly on the use of ThermoCouples (TC) for this type of thermal monitoring due to the variability of constraints required to accurately map rapidly changing temperatures from ambient to glowing hot chamber material. Obtaining accurate real-time temperatures in the JR spectrum is made even more elusive by the changing emissivity of the chamber material as it begins to glow. The parameters evaluated prior to APS testing included: (1) remote operation of the A40M camera using fiber optic Firewire signal sender and receiver units; (2) operation of the camera inside a Pelco explosion proof enclosure with a germanium window; (3) remote analog signal display for real-time monitoring; (4) remote digital data acquisition of the A40M's sensor information using FUR's ThermaCAM Researcher Pro 2.8 software; and (5) overall reliability of the system. An initial characterization report was prepared after the A40M characterization tests at Marshall Space Flight Center (MSFC) to document controlled heat source comparisons to calibrated TCs. Summary IR digital data recorded from WSTF's APS testing is included within this document along with findings, lessons learned, and recommendations for further usage as a monitoring tool for the development of rocket engines. 2. Tree plastic bark OpenAIRE Casado Arroyo, Carlos 2016-01-01 “Tree plastic bark" consiste en la realización de una intervención artística en un entorno natural concreto, generando de esta manera un Site Specific(1). Como hace alusión Rosalind Krauss en sus reflexiones “La escultura en el campo expandido”(2), comenta que su origen esta claramente ligado con el concepto de monumentalidad. La escultura es un monumento, se crea para conmemorar algún hecho o personaje relevante y está realizada para una ubicación concreta. La investigación parte de la id... 3. Kauai Test Facility hazards assessment document Energy Technology Data Exchange (ETDEWEB) Swihart, A 1995-05-01 The Department of Energy Order 55003A requires facility-specific hazards assessment be prepared, maintained, and used for emergency planning purposes. This hazards assessment document describes the chemical and radiological hazards associated with the Kauai Test Facility, Barking Sands, Kauai, Hawaii. The Kauai Test Facilitys chemical and radiological inventories were screened according to potential airborne impact to onsite and offsite individuals. The air dispersion model, ALOHA, estimated pollutant concentrations downwind from the source of a release, taking into consideration the toxicological and physical characteristics of the release site, the atmospheric conditions, and the circumstances of the release. The greatest distance to the Early Severe Health Effects threshold is 4.2 kilometers. The highest emergency classification is a General Emergency at the {open_quotes}Main Complex{close_quotes} and a Site Area Emergency at the Kokole Point Launch Site. The Emergency Planning Zone for the {open_quotes}Main Complex{close_quotes} is 5 kilometers. The Emergency Planning Zone for the Kokole Point Launch Site is the Pacific Missile Range Facilitys site boundary. 4. Cork Containing Barks - a review Science.gov (United States) Leite, Carla; Pereira, Helena 2016-12-01 Tree barks are among the less studied forest products notwithstanding their relevant physiological and protective role in tree functioning. The large diversity in structure and chemical composition of barks makes them a particularly interesting potential source of chemicals and bio-products, at present valued in the context of biorefineries. One of the valuable components of barks is cork (phellem in anatomy) due to a rather unique set of properties and composition. Cork from the cork oak (Quercus suber) has been extensively studied, mostly because of its economic importance and worldwide utilization of cork products. However, several other species have barks with substantial cork amounts that may constitute additional resources for cork-based bioproducts. This paper makes a review of the tree species that have barks with significant proportion of cork and on the available information regarding their bark structural and chemical characterization. A general integrative appraisal of the formation and types of barks and of cork development is also given. The knowledge gaps and the potential interesting research lines are identified and discussed, as well as the utilization perspectives. 5. Sands styrke DEFF Research Database (Denmark) Jacobsen, H. Moust; Jørgensen, Mogens B.; Poulsen, H. Serup 1975-01-01 På grundlag af triaxialforsøg med D=7 og 20 cm og varierende højde på løse og faste lejringer af Blokhussand kan effekten af varierende højde-breddeforhold og spændingsniveau samt skalaeffekten bestemmes. Ved sammenligning med pladeforsøg med overfladelast op til 8 t/m2 kan den almindelige fremga...... fremgangsmåde ved bæreevneberegninger på sand undersøges.... 6. Tar sand Energy Technology Data Exchange (ETDEWEB) McLendon, T.R.; Bartke, T.C. 1990-01-01 Research on tar sand is briefly discussed. The research program supported by the US Department of Energy (DOE) includes a variety of surface extraction schemes. The University of Utah has process development units (PDU) employing fluidized bed, hot, water-assisted, and fluidized-bed/heat-pipe, coupled combustor technology. Considerable process variable test data have been gathered on these systems: (1) a rotary kiln unit has been built recently; (2) solvent extraction processing is being examined; and (3) an advanced hydrogenation upgrading scheme (hydropyrolysis) has been developed. The University of Arkansas, in collaboration with Diversified Petroleum, Inc., has been working on a fatty acid, solvent extraction process. Oleic acid is the solvent/surfactant. Solvent is recovered by adjusting processing fluid concentrations to separate without expensive operations. Western Research Institute has a PDU-scale scheme called the Recycle Oil Pyrolysis and Extraction (ROPE) process, which combines solvent (hot recycle bitumen) and pyrolytic extraction. 14 refs., 19 figs. 7. It's in the sand OpenAIRE Mitchell, Clive 2016-01-01 Sand is sand isn’t it? Sand gets everywhere but rather than a nuisance it is a valuable, high-purity raw material. Clive Mitchell, Industrial Minerals Specialist at the British Geological Survey (BGS), talks us through what sand is, what it can be used for and how to find it. His exploration of sand takes us from the deserts of Arabia to the damp sand pits of Mansfield! 8. Pheromone production in bark beetles. Science.gov (United States) Blomquist, Gary J; Figueroa-Teran, Rubi; Aw, Mory; Song, Minmin; Gorzalski, Andrew; Abbott, Nicole L; Chang, Eric; Tittiger, Claus 2010-10-01 The first aggregation pheromone components from bark beetles were identified in 1966 as a mixture of ipsdienol, ipsenol and verbenol. Since then, a number of additional components have been identified as both aggregation and anti-aggregation pheromones, with many of them being monoterpenoids or derived from monoterpenoids. The structural similarity between the major pheromone components of bark beetles and the monoterpenes found in the host trees, along with the association of monoterpenoid production with plant tissue, led to the paradigm that most if not all bark beetle pheromone components were derived from host tree precursors, often with a simple hydroxylation producing the pheromone. In the 1990 s there was a paradigm shift as evidence for de novo biosynthesis of pheromone components began to accumulate, and it is now recognized that most bark beetle monoterpenoid aggregation pheromone components are biosynthesized de novo. The bark beetle aggregation pheromones are released from the frass, which is consistent with the isoprenoid aggregation pheromones, including ipsdienol, ipsenol and frontalin, being produced in midgut tissue. It appears that exo-brevocomin is produced de novo in fat body tissue, and that verbenol, verbenone and verbenene are produced from dietary α-pinene in fat body tissue. Combined biochemical, molecular and functional genomics studies in Ips pini yielded the discovery and characterization of the enzymes that convert mevalonate pathway intermediates to pheromone components, including a novel bifunctional geranyl diphosphate synthase/myrcene synthase, a cytochrome P450 that hydroxylates myrcene to ipsdienol, and an oxidoreductase that interconverts ipsdienol and ipsdienone to achieve the appropriate stereochemistry of ipsdienol for pheromonal activity. Furthermore, the regulation of these genes and their corresponding enzymes proved complex and diverse in different species. Mevalonate pathway genes in pheromone producing male I. pini 9. Industrial sand and gravel Science.gov (United States) Dolley, T.P. 2013-01-01 Domestic production of industrial sand and gravel in 2012 was about 49.5 Mt (55 million st), increasing 13 percent compared with that of 2011. Some important end uses for industrial sand and gravel include abrasives, filtration, foundry, glassmaking, hydraulic fracturing sand (frac sand) and silicon metal applications. 10. A Potential Tool for Swift Fox (Vulpes velox) Conservation: Individuality of Long-Range Barking Sequences DEFF Research Database (Denmark) Darden, Safi-Kirstine Klem; Dabelsteen, Torben; Pedersen, Simon Boel 2003-01-01 context from 20 captive individuals (3 females and 17 males) housed in large, single-pair enclosures at a swift fox breeding facility. Using a discriminant function analysis with 7 temporal and spectral variables measured on barking sequences, we were able to correctly classify 99% of sequences... 11. Response to Oil Sands Products Assessment Science.gov (United States) 2015-09-01 Tailings ponds are an operating facility common to all types of surface mining. For oil sands, tailings consisting of water , sand, clay, and residual ...oil, are pumped to these basins—or ponds— where settling occurs and water is recycled for reuse in the process. When the ponds are no longer required...of crude oil transported by tank vessel in Washington waters . In a 2013 Bloomburg Business news article , Dan Murtaugh states, “The dock probably 12. Eastern Scheldt Sand, Baskarp Sand No. 15 DEFF Research Database (Denmark) Andersen, A. T; Madsen, E. B.; Schaarup-Jensen, A. L. The present data report contains data from 13 drained triaxial tests, performed on two different sand types in the Soil Mechanics Laboratory at Aalborg University in March, 1997. Two tests have been performed on Baskarp Sand No. 15, which has already ken extensively tested in the Soil Mechanics...... Laboratory. The remaining 11 triaxial tests have ben performed on Eastern Scheldt Sand, which is a material not yet investigated at the Soil Mechanics Laboratory. In the first pari of this data report, the characteristics of the two sand types in question will be presented. Next, a description... 13. Geohydrology of the High Energy Laser System Test Facility site, White Sands Missile Range, Tularosa Basin, south-central New Mexico Science.gov (United States) Basabilvazo, G.T.; Nickerson, E.L.; Myers, R.G. 1994-01-01 The Yesum-HoHoman and Gypsum land (hummocky) soils at the High Energy Laser System Test Facility (HELSTF) represent wind deposits from recently desiccated lacustrine deposits and deposits from the ancestral Lake Otero. The upper 15-20 feet of the subsurface consists of varved gypsiferous clay and silt. Below these surfidai deposits the lithology consists of interbedded clay units, silty-clay units, and fine- to medium-grained quartz arenite units in continuous and discontinuous horizons. Clay horizons can cause perched water above the water table. Analyses of selected clay samples indicate that clay units are composed chiefly of kaolinire and mixed-layer illite/ smectite. The main aquifer is representative of a leaky-confined aquifer. Estimated aquifer properties are: transmissivity (T) = 780 feet squared per day, storage coefficient (S) = 3.1 x 10-3, and hydraulic conductivity (K) = 6.0 feet per day. Ground water flows south and southwest; the estimated hydraulic gradient is 5.3 feet per mile. Analyses of water samples indicate that ground water at the HELSTF site is brackish to slightly saline at the top of the main aquifer. Dissolved-solids concentration near the top of the main aquifer ranges from 5,940 to 11,800 milligrams per liter. Predominant ions are sodium and sulfate. At 815 feet below land surface, the largest dissolved-solids concentration measured is 111,000 milligrams per liter, which indicates increasing salinity with depth. Predominant ions are sodium and chloride. 14. Influence green sand system by core sand additions OpenAIRE N. Špirutová; J. Beňo; V. Bednářová; J. Kříž; M. Kandrnál 2012-01-01 Today, about two thirds of iron alloys casting (especially for graphitizing alloys of iron) are produced into green sand systems with usually organically bonded cores. Separation of core sands from the green sand mixture is very difficult, after pouring. The core sand concentration increase due to circulation of green sand mixture in a closed circulation system. Furthermore in some foundries, core sands have been adding to green sand systems as a replacement for new sands. The goal of this co... 15. Baskarp Sand No. 15 DEFF Research Database (Denmark) Borup, Marianne; Hedegaard, Jette The Soil Mechanics Laboratory has started performing tests with a new sand, Baskarp No 15. Baskarp No 15 is a graded sand from Sweden. The shapes of the largest grains are round, while the small grains have sharp edges. The main part of of Baskarp No 15 is quarts, but it also contains feldspar...... and biotit. Mainly the sand will be used for tests concerning the development og the theory of building up pore pressure in sand, L. B. Ibsen 1993.... 16. Lund Sand No 0 DEFF Research Database (Denmark) Ibsen, Lars Bo; Jakobsen, Finn Rosendal During the last 15 years the Geotechnical Engineering Group (GEG) at Aalborg University has performed triaxial tests with a sand called Lund No 0. Lund No 0 is a graded sand from a gravel pit near Horsens in Denmark. For the classification of the sand the following tests have been performed: Sieve... 17. Metals Bioaccumulation Mechanism in Neem Bark. Science.gov (United States) Krishnani, Kishore K; Boddu, Veera M; Moon, Deok Hyun; Ghadge, S V; Sarkar, Biplab; Brahmane, M P; Choudhary, K; Kathiravan, V; Meng, Xiaoguang 2015-09-01 The aim of this work was to define the bioaccumulation mechanism of metals onto the non-living biomaterial prepared from an extensively available plant bark biomass of neem (Azadirachta indica). Based on maximum ultimate fixation capacities (mmol/g) of the product, metals ions could be arranged as Hg(2+) Neem bark can be used as bioindicators, bioaccumulators and biomonitors while determining environmental pressures. Metal bioaccumulative properties and structural investigation of plant bark has potential in providing quantitative information on the metal contamination in the surrounding environment. 18. Degradation of poplar bark by Panaeolus Energy Technology Data Exchange (ETDEWEB) Scurti, J.C.; Fiussello, N.; Gullino, M.L.; Ferrara, R. 1978-01-01 Pure cultures of 41 strains of Paneolus were tested for their ability to break down poplar bark with a view to their possible use for biodegradation of this waste product of paper manufacture. Most strains were able to grow (slowly) on sterilized poplar bark and showed high ligninolytic activity. Some strains also showed cellulolytic action. Almost all the strains showed phenol-oxidase activity, but there was no correlation between lignin decomposition and phenol-oxidase activity. The amounts of bark degraded by the fungi were relatively small (3.2 - 13.0% loss of dry weight after six months incubation). 19. US Forest Service Western Bark Beetle Strategy Data.gov (United States) US Forest Service, Department of Agriculture — A map service on the www depicting Western Bark Beetle Strategy (WBBS) activities reported through the U.S. Forest Service FACTS database. Activities include... 20. Investigation of thermal decomposition of bark Energy Technology Data Exchange (ETDEWEB) Adamczak, B.; Babicki, R. 1978-01-01 Destructive distillation of Scots pine bark in the laboratory yielded poor quality charcoal. Processing of liquid distillates was not economically justified. The charcoal could be upgraded by demineralization followed by briquetting but this would considerably increase costs. (Refs. 5). 1. Phenolic glycosides of Paulownia tomentosa bark. Science.gov (United States) Sticher, O; Lahloub, M F 1982-11-01 The isolation of acteoside and coniferin from Paulownia tomentosa bark along with the previously reported phenolic glucoside syringin is described. The structure of both, acteoside and coniferin, have been assigned by (1)H- and (13)C-NMR spectroscopy. 2. Pretreatment of turkey fat-containing wastewater in coarse sand and gravel/coarse sand bioreactors. Science.gov (United States) Gaur, Rashmi Singh; Cai, Ling; Tuovinen, Olli H; Mancl, Karen M 2010-02-01 Fat, oil and grease in wastewater can be difficult to treat because of their slow decomposition. Traditional pretreatment facilities to remove fat, oil and grease from wastewater are increasingly costly. The hypothesis in this study was that pretreatment of animal fat-containing wastewater in sand and sand/gravel filters facilitates the conversion of slowly degradable organic matter measured as the difference between chemical oxygen demand (COD) and 5-day biochemical oxygen demand (BOD(5)) for subsequent biological treatment. The pretreatment was evaluated using simulated turkey-processing wastewater and coarse sand and sand/gravel filters at a constant hydraulic loading rate of 132L/m(2)/day. Two types of fixed media reactors were employed: (i) one set with a varying depth of coarse sand, and (ii) the second was similar but with an additional pea gravel cap. The results indicated that the relative removal of COD was slightly improved in the sand bioreactors with a pea gravel cap irrespective of the depth of coarse sand, but partial conversion to BOD(5) was not consistently demonstrated. Pea gravel may act as a sieve to entrap organic matter including fat globules from the wastewater. Multiple dosing at the same daily loading rate slightly improved the treatment efficiency of the sand bioreactors. The ratios of influent-COD/effluent-COD were always greater than 1.0 following a change in the dosing frequency after a rest period, suggesting that organic matter, specifically fat globules in this case, was retained by the column matrix. 3. Quantum non-barking dogs Science.gov (United States) Imari Walker, Sara; Davies, Paul C. W.; Samantray, Prasant; Aharonov, Yakir 2014-06-01 Quantum weak measurements with states both pre- and post-selected offer a window into a hitherto neglected sector of quantum mechanics. A class of such systems involves time dependent evolution with transitions possible. In this paper we explore two very simple systems in this class. The first is a toy model representing the decay of an excited atom. The second is the tunneling of a particle through a barrier. The post-selection criteria are chosen as follows: at the final time, the atom remains in its initial excited state for the first example and the particle remains behind the barrier for the second. We then ask what weak values are predicted in the physical environment of the atom (to which no net energy has been transferred) and in the region beyond the barrier (to which the particle has not tunneled). Thus, just as the dog that didn't bark in Arthur Conan Doyle's story Silver Blaze gave Sherlock Holmes meaningful information about the dog's non-canine environment, here we probe whether the particle that has not decayed or has not tunneled can provide measurable information about physical changes in the environment. Previous work suggests that very large weak values might arise in these regions for long durations between pre- and post-selection times. Our calculations reveal some distinct differences between the two model systems. 4. Influence green sand system by core sand additions Directory of Open Access Journals (Sweden) N. Špirutová 2012-01-01 Full Text Available Today, about two thirds of iron alloys casting (especially for graphitizing alloys of iron are produced into green sand systems with usually organically bonded cores. Separation of core sands from the green sand mixture is very difficult, after pouring. The core sand concentration increase due to circulation of green sand mixture in a closed circulation system. Furthermore in some foundries, core sands have been adding to green sand systems as a replacement for new sands. The goal of this contribution is: “How the green sand systems are influenced by core sands?”This effect is considered by determination of selected technological properties and degree of green sand system re-bonding. From the studies, which have been published yet, there is not consistent opinion on influence of core sand dilution on green sand system properties. In order to simulation of the effect of core sands on the technological properties of green sands, there were applied the most common used technologies of cores production, which are based on bonding with phenolic resin. Core sand concentration added to green sand system, was up to 50 %. Influence of core sand dilution on basic properties of green sand systems was determined by evaluation of basic industrial properties: moisture, green compression strength and splitting strength, wet tensile strength, mixture stability against staling and physical-chemistry properties (pH, conductivity, and loss of ignition. Ratio of active betonite by Methylene blue test was also determined. 5. EUB Decision 2006-112 : Suncor Energy Inc. application for expansion of an oil sands mine (North Steepbank mine extension) and a bitumen upgrading facility (Voyageur Upgrader) in the Fort McMurray area Energy Technology Data Exchange (ETDEWEB) NONE 2006-11-14 Suncor Energy Inc. filed 2 applications to the Alberta Energy and Utilities Board for their proposed North Steepbank Mine Extension and Voyageur Upgrading Facility in the Fort McMurray area. This document provided an outline to the board of the location of the proposed projects, along with technical details concerning sulphur recovery, coke gasification, and by-product storage and use. The applications shared a common environmental impact assessment report, which presented details of tailings management programs; environmental effects to air, terrestrial resources, surface water, and groundwater; potential health effects to human populations; and traditional land use and ecological knowledge of the lands in the areas of the proposed upgrades. The social and economic effects of the projects were considered by the board, as well as the efforts of Suncor to engage with public consultation processes. It was noted that the projects are expected to provide7.1 billion in federal taxes paid over the life of the project, in addition to $3.6 billion in provincial taxes and a further$23 million in municipal taxes. Details of several interventions filed by various First Nations groups were presented. It was noted that the Oil Sands Environmental Coalition (OSEC) has filed interventions stating concerns over consultation practices; cumulative effects; environmental monitoring; water usage; reclamation policies; and socio-economic issues. Various other groups have expressed concerns over the impacts of rapid development in the region and the subsequent strains on public infrastructure, housing and community resources. While the project is expected to provide employment, the current labour shortage in the region means that further development will be a disadvantage rather than a benefit to the communities in the region. Although a number of conditions were placed on Suncor before full acceptance of the project could be given, the board concluded that the Voyageur project was
6. Strategies towards sustainable bark sourcing as raw material for ...
African Journals Online (AJOL)
SARAH
2017-07-31
Jul 31, 2017 ... Objectives: To appraise the amount of sustainable bark stripped and time to complete bark recovery as basis ... in pharmaceutical shops worldwide for the treatment ..... factors such as rainfall, soil nutrient or water soil.
7. Sands cykliske styrke
DEFF Research Database (Denmark)
Ibsen, Lars Bo
1992-01-01
Sands cykliske styrke kan beskrives ved Cyclic Liquefaction, Mobilisering, Stabilization og Instant Stabilization. I artiklen beskrives hvorfor Stabilization og Instant Stabilization ikke observeres, når sands udrænede styrke undersøges i triaxial celler, der anvender prøver med dobbelt prøvehøjde....
DEFF Research Database (Denmark)
Ibsen, Lars Bo; Bødker, Lars Bødker
The Soil Mechanics Laboratory has started performing tests with a new sand, Baskarp No 15. Baskarp No 15 is a graded sand from Sweden. The shapes of the largest grains are round, while the small grains have sharp edges. The main part of of Baskarp No 15 is quarts, but it also contains feldspar...
9. Mites associated with bark beetles and their hyperphoretic ophiostomatoid fungi
Science.gov (United States)
Richard W. Hofstetter; John Moser; Stacy Blomquist
2014-01-01
The role that mites play in many ecosystems is often overlooked or ignored. Within bark beetle habitats, more than 100 mite species exist and they have important impacts on community dynamics, ecosystem processes, and biodiversity of bark beetle systems. Mites use bark beetles to access and disperse among beetle-infested trees and the associations may range from...
10. Photosynthetic bark : use of chlorophyll absorption continuum index to estimate Boswellia papyrifera bark chlorophyll content
NARCIS (Netherlands)
Girma Gebrekidan, A.; Skidmore, A.K.; de Bie, C.A.J.M.; Bongers, Frans; Schlerf, Martin; Schlerf, M.
2013-01-01
Quantification of chlorophyll content provides useful insight into the physiological performance of plants. Several leaf chlorophyll estimation techniques, using hyperspectral instruments, are available. However, to our knowledge, a non-destructive bark chlorophyll estimation technique is not availa
11. Metals bioaccumulation mechanism in neem bark
Science.gov (United States)
The aim of this work was to define the bioaccumulation mechanism of metals onto the non-living biomaterial prepared from an extensively available plant bark biomass of neem (Azadirachta indica). Based on maximum ultimate fixation capacities (mmol/g) of the product, metals ions could be arranged as H...
12. Carbohydrates from Detarium microcarpum bark extract.
Science.gov (United States)
Abreu, Pedro; Relva, Angela
2002-10-08
The bark extract of the medicinal plant Detarium microcarpum was analysed for its carbohydrate content by GLC-CIMS. Preparative HPLC of the benzoylated carbohydrate fraction led to the isolation of L-quino-1,5-lactone, D-(-)-bornesitol, D-pinitol, myo-inositol, sucrose, D-glucose, and D-fructose benzoates, which were characterised by NMR spectroscopy experiments.
13. Sand and Gravel Deposits
Data.gov (United States)
Vermont Center for Geographic Information — This dataset is a statewide polygon coverage of sand, gravel, and stone resources. This database includes the best data available from the VT Agency of Natural...
14. Sand and Gravel Operations
Data.gov (United States)
Department of Homeland Security — This map layer includes sand and gravel operations in the United States. These data were obtained from information reported voluntarily to the USGS by the aggregate...
15. Vestled - Hvide Sande
DEFF Research Database (Denmark)
Juel-Christiansen, Carsten; Hesselbjerg, Marianne; Schønherr, Torben
2009-01-01
Værket Vestled i Hvide Sande præsenteret i sammenhæng af 1000 nutidige landskabsarkitektoniske arbejder fra hele verden, hvor hvert værk vises på én side......Værket Vestled i Hvide Sande præsenteret i sammenhæng af 1000 nutidige landskabsarkitektoniske arbejder fra hele verden, hvor hvert værk vises på én side...
16. MECHANICAL REGENERATION OF SAND WASTE
Directory of Open Access Journals (Sweden)
D. I. Gnir
2005-01-01
Full Text Available The experimental activation of the sand regenerator of the firm SINTO is carried out at ОАО “MZOO". It is shown that sand grains are cleared from films of binding agents, that allows to use the treated sand for preparation of agglutinant and core sands.
17. Bituminous sands : tax issues
Energy Technology Data Exchange (ETDEWEB)
Patel, B. [PricewaterhouseCoopers LLP, Calgary, AB (Canada)
2004-07-01
This paper examined some of the tax issues associated with the production of bitumen or synthetic crude oil from oil sands. The oil sands deposits in Alberta are gaining more attention as the supplies of conventional oil in Canada decline. The oil sands reserves located in the Athabasca, Cold Lake and Peace River areas contain about 2.5 trillion barrels of highly viscous hydrocarbons called bitumen, of which nearly 315 billion barrels are recoverable with current technology. The extraction method varies for each geographic area, and even within zones and reservoirs. The two most common extraction methods are surface mining and in-situ extraction such as cyclic steam stimulation (CSS); low pressure steam flood; pressure cycle steam drive; steam assisted gravity drainage (SAGD); hot water flooding; and, fire flood. This paper also discussed the following general tax issues: bituminous sands definition; bituminous sands leases and Canadian development expense versus Canadian oil and gas property expense (COGPE); Canadian exploration expense (CEE) for surface mining versus in-situ methods; additional capital cost allowance; and, scientific research and experimental development (SR and ED). 15 refs.
18. Complement fixing polysaccharides from Terminalia macroptera root bark, stem bark and leaves.
Science.gov (United States)
Zou, Yuan-Feng; Zhang, Bing-Zhao; Barsett, Hilde; Inngjerdingen, Kari Tvete; Diallo, Drissa; Michaelsen, Terje Einar; Paulsen, Berit Smestad
2014-06-06
The root bark, stem bark and leaves of Terminalia macroptera were sequentially extracted with ethanol, 50% ethanol-water, and 50 °C and 100 °C water using an accelerated solvent extractor. Ten bioactive purified polysaccharide fractions were obtained from those crude extracts after anion exchange chromatography and gel filtration. The polysaccharides and their native extracts were characterized with respect to molecular weight, chemical compositions and effects in the complement assay. The chemical compositions showed that the polysaccharides are of pectic nature. The results indicated that there was no great difference of the complement fixation activities in the crude extracts from the different plant parts when extracting with the accelerated solvent extraction system. The purified polysaccharide fractions 100WTSBH-I-I and 100WTRBH-I-I isolated from the 100 °C water extracts of stem and root bark respectively, showed the highest complement fixation activities. These two fractions have rhamnogalacturonan type I backbone, but only 100WTSBH-I-I contains side chains of both arabinogalactan type I and II. Based on the yield and activities of the fractions studied those from the root bark gave highest results, followed by those from leaves and stem bark. But in total, all plant materials are good sources for fractions containing bioactive polysaccharides.
19. PHARMACOGNOSTIC EVALUATION OF TOONA CILIATA BARK.
Directory of Open Access Journals (Sweden)
Ajay Gautam
2010-06-01
Full Text Available Pharmacognostic standardizations of powdered and anatomical sections of the Toona ciliata bark was carried out to determine its macro- and microscopical characters and also some of its quantitative standards. Externally bark are Grey to reddish-brown in colour when it is dry, 200 mm in length, 20 to 60 mm in width and 2 to 3 mm in thickness outer surface brown coloured, strong odour, bitter taste, rough and hard, double quill and curved curvature. The transverse section (T.S. revealed the presences of periderm, cortex, Sclerides, medullary rays and phloem fiber. Physico-chemical evaluation includes ash values, extractive values and moisture content. These findings will be useful towards establishing pharmacognostic standards on identification, purity, quality and classification of the plant, which is gaining relevance in plant drug research.
20. Hepatoprotective properties of Bauhinia variegata bark extract.
Science.gov (United States)
Bodakhe, Surendra H; Ram, Alpana
2007-09-01
Bauhinia variegata (Leguminosae) commonly known as Kachnar, is widely used in Ayurveda as tonic to the liver. The present work was carried out to assess the potential of Bauhinia variegata bark as hepatoprotective agent. The hepatoprotective activity was investigated in carbon tetrachloride (CCl(4)) intoxicated Sprague-Dawley rats. Bauhinia variegata alcoholic Stem Bark Extract (SBE) at different doses (100 and 200 mg/kg) were administered orally to male Sprague-Dawley rats weighing between 100-120 g. The effect of SBE on the serum marker enzymes, viz., AST, ALT, ALP and GGT and liver protein and lipids were assessed. The extract exhibited significant hepatoprotective activity. Hence, B. variegata appears to be a promising hepatoprotective agent.
1. Lund Sand No 0
DEFF Research Database (Denmark)
Ibsen, Lars Bo; Jakobsen, Finn Rosendal
During the last 15 years the Geotechnical Engineering Group (GEG) at Aalborg University has performed triaxial tests with a sand called Lund No 0. Lund No 0 is a graded sand from a gravel pit near Horsens in Denmark. For the classification of the sand the following tests have been performed: Sieve...... test, Grain density, ds, Maximum, emax, and minimum, emin, void ratio. The strength parameters of Lund No 0 are detennined by some drained and undrained triaxial tests in the Danish Triaxial Cell. The Danish Triaxial Cell prescribes smooth pressure heads and specimens with equal height and diameter....... Four series with Id equal to 0.92, 0.87 0.76 and 0.55 have been performed....
2. Triterpenoid glycosides from bark of Meliosma lanceolata.
Science.gov (United States)
Abe, F; Yamauchi, T; Shibuya, H; Kitagawa, I
1996-06-01
From the bark of Meliosma lanceolate, nine triterpenoid glycosides including the 28-O-beta-D-glucopyranosyl ester of bayogenin-3-O-beta-D-glucuronopyranoside, its 4'-O-beta-D-galactopyranoside and 4'-O-alpha-L-arabinopyranoside were isolated and the structures characterized along with that of 28-O-beta-D-glucopyranosyl-bayogenin-3-O-beta-D-4'-anhydro-4', 5'-didehydroglucuronopyranoside. Bisdesmosidic triosides of hederagenin were obtained as minor components.
3. Phytochemical analysis of Pinus eldarica bark.
Science.gov (United States)
Iravani, S; Zolfaghari, B
2014-01-01
Bark extract of Pinus pinaster contains numerous phenolic compounds such as catechins, taxifolin, and phenolic acids. These compounds have received considerable attentions because of their anti-inflammatory, antimutagenic, anticarcinogenic, antimetastatic and high antioxidant activities. Although P. pinaster bark has been intensely investigated in the past; there is comparably less information available in the literature in regard to P. eldarica bark. Therefore, the aim of this study was to determine the chemical composition of P. eldarica commonly found in Iran. A reversed-phase high pressure liquid chromatography (RP-HPLC) method for the determination of catechin, caffeic acid, ferulic acid, and taxifolin in P. pinaster and P. eldarica was developed. A mixture of 0.1% formic acid in deionized water and 0.1% formic acid in acetonitrile was used as the mobile phase, and chromatographic separation was achieved on a Nova pack C18 at 280 nm. The two studied Pinus species contained high amounts of polyphenolic compounds. Among four marker compounds, the main substances identified in P. pinaster and P. eldarica were taxifolin and catechin, respectively. Furthermore, the composition of the bark oil of P. eldarica obtained by hydrodistillation was analyzed by gas chromatography/mass spectroscopy (GC/MS). Thirty-three compounds accounting for 95.1 % of the oil were identified. The oils consisted mainly of mono- and sesquiterpenoid fractions, especially α-pinene (24.6%), caryophyllene oxide (14.0%), δ-3-carene (10.7%), (E)-β-caryophyllene (7.9%), and myrtenal (3.1%).
4. Possible $B^{(\\ast)} \\bar{K}$ hadronic molecule state
CERN Document Server
Xiao, Cheng-Jian
2016-01-01
In the present work, we estimate the decays of the $X(5568)$ and $X(5616)$ in a $B \\bar{K}$ and a $B^\\ast \\bar{K}$ $S$-wave hadronic molecule scenarios, respectively, which may corresponding to the structure observed by D0 Collaboration. Our estimation indicates both $B\\bar{K}$ and $B^\\ast \\bar{K}$ hadronic molecule decay widths could explain the experimental data in a proper model parameter range.
5. UK Frac Sand Resources
OpenAIRE
Mitchell, C J
2015-01-01
Although still just a glimmer in the gas man’s eye, the prospect of shale hydrocarbon (oil and gas) development in the UK has many companies thinking about the industrial minerals it will require. Chief amongst these is silica sand which is used as a ‘proppant’ in the hydraulic fracturing, or ‘fracking’, of shales to help release the gas. The UK has large resources of sand and sandstone, of which only a small proportion have the necessary technical properties that classify them as ‘silica san...
6. What is Next in Bark Beetle Phylogeography?
Directory of Open Access Journals (Sweden)
Dimitrios N. Avtzis
2012-05-01
Full Text Available Bark beetle species within the scolytid genera Dendroctonus, Ips, Pityogenes and Tomicus are known to cause extensive ecological and economical damage in spruce and pine forests during epidemic outbreaks all around the world. Dendroctonus ponderosae poses the most recent example having destroyed almost 100,000 km2 of conifer forests in North America. The success and effectiveness of scolytid species lies mostly in strategies developed over the course of time. Among these, a complex system of semiochemicals promotes the communication and aggregation on the spot of infestation facilitating an en masse attack against a host tree’s defenses; or an association with fungi that evolved either in the form of nutrition (ambrosia fungi or even by reducing the resistance of host trees (blue-stain fungi. Although often specific to a tree genus or species, some bark beetles are polyphagous and have the ability to switch on to new hosts and extend their host range (i.e., between conifer genera such as Pityogenes chalcographus or even from conifer to deciduous trees as Polygraphus grandiclava. A combination of these capabilities in concert with life history or ecological traits explains why bark beetles are considered interesting subjects in evolutionary studies. Several bark beetle species appear in phylogeographic investigations, in an effort to improve our understanding of their ecology, epidemiology and evolution. In this paper investigations that unveil the phylogeographic history of bark beetles are reviewed. A close association between refugial areas and postglacial migration routes that insects and host trees have followed in the last 15,000 BP has been suggested in many studies. Finally, a future perspective of how next generation sequencing will influence the resolution of phylogeographic patterns in the coming years is presented. Utilization of such novel
7. Building with Sand
Science.gov (United States)
Ashbrook, Peggy
2010-01-01
Children playing in damp sand invariably try to make a tower or a tunnel. By providing experiences with a variety of materials, alone and together, teachers set up the conditions for children to learn through their senses and ensure that a class approaches a topic with a common set of experiences to build on. Learning about the properties of…
NARCIS (Netherlands)
Sandtke, M.; van der Meer, Roger M.; Versluis, Andreas Michel; Lohse, Detlef
2003-01-01
When a 6-mm layer of fine sand with an average grain size of 40 µm is poured into a cylindrical container and shaken vertically, thin jets are seen to emerge from an airy cloud of grains, almost like protuberances from the corona of the sun. A quasi two-dimensional setup reveals the jet-formation
9. Building with Sand
Science.gov (United States)
Ashbrook, Peggy
2010-01-01
Children playing in damp sand invariably try to make a tower or a tunnel. By providing experiences with a variety of materials, alone and together, teachers set up the conditions for children to learn through their senses and ensure that a class approaches a topic with a common set of experiences to build on. Learning about the properties of…
10. Speleothems and Sand Castles
Science.gov (United States)
Hance, Trevor; Befus, Kevin
2015-01-01
The idea of building sand castles evokes images of lazy summer days at the beach, listening to waves crash, enjoying salty breezes, and just unplugging for a while to let our inner child explore the wonderful natural toys beneath our feet. The idea of exploring caves might evoke feelings and images of claustrophobia or pioneers and Native…
11. Virksomhedens sande ansigt
DEFF Research Database (Denmark)
Lundholt, Marianne Wolff
2017-01-01
Er modhistorier en byrde eller en styrke i forandringsprocesser? Hvad stiller vi op, når adgangen til organisationens sande identitet går gennem medarbejdernes modhistorier? Når vi sammenholder denne erkendelse med vores viden om, at medarbejdere helt naturligt afholder sig fra at videregive disse...
12. Sand (CSW4)
CSIR Research Space (South Africa)
Estuarine and Coastal Research Unit
1982-12-01
Full Text Available This report is one of a series on Cape Estuaries being published under the general title "The Estuaries of the Cape, Part 2". The report provides information on sand estuary: historical background, abiotic and biotic characteristics. It is pointed...
13. Sand supply to beaches
Science.gov (United States)
Aagaard, Troels
2017-04-01
In most cases, beaches and dunes are built by sand that has been transported onshore from the shoreface. While this has been known for a long time, we are still not able to quantitatively predict onshore sediment transport and sand supply to beaches. Sediment transport processes operating during brief, high-energy stormy conditions - when beaches erode and sand moves offshore - are fairly well known and they can be modelled with a reasonable degree of confidence. However, the slower onshore sand transport leading to beach recovery under low-to-moderate energy conditions - and the reason why beaches and dunes exist in the first place - is not yet well understood. This severely limits our capability to understand and predict coastal behaviour on long time scales, for example in response to changing sea level or wave conditions. This paper will discuss issues and recent developments in sediment transport measurement and prediction on the lower and upper shoreface and into the swash zone. The focus will be on the integration and upscaling of small-scale deterministic process measurements into parametric models that may increase modelling capabilities of coastal behaviour on larger temporal and spatial scales.
14. Erosion phenomena in sand moulds
Directory of Open Access Journals (Sweden)
A. Chojecki
2008-03-01
Full Text Available Authors studicd the erosion phcnorncna in sand moulds pured with cast iron. Thc study comprises an evaluation of erosionresistance of thc three sands: grccn sand. sand bondcd with inorganic or organic bindcr. It was concluded that thc most resistant is [heclassic green sand with thc addition of 5 B coal dust. Resistance of the sand with organic binder is generally weak and dcvnds onkind of used raisin. Spccinl nztcntion was paid to the sands with no organic bindcr watcr glass and phospha~c. It was Sound that thcirrcsistance depends on dehydratation conditions. When the mould is stored in law humidity of atmosphcrc the very strong crosion canbe expected. It rcsul ts hrn thc micro fractures in the bridges of binders, joining the grains of the sable. This phcnomcna facilitates thetearing away of fragments of sand [tom the surface
15. On Pluvial Compaction of Sand
DEFF Research Database (Denmark)
Jacobsen, Moust
At the Institute of Civil Engineering in Aalborg model tests on dry sand specimens have been carried out during the last five years. To reduce deviations in test results, the sand laying technique has been carefully studied, and the sand mass spreader constructed. Preliminary results have been...
16. Bark beetle outbreaks in western North America: causes and consequences
Science.gov (United States)
Bentz, Barbara; Logan, Jesse; MacMahon, James A.; Allen, Craig D.; Ayres, Matt; Berg, Edward E; Carroll, Allan; Hansen, Matt; Hicke, Jeff H.; Joyce, Linda A.; Macfarlane, Wallace; Munson, Steve; Negron, Jose; Paine, Tim; Powell, Jim; Raffa, Kenneth; Regniere, Jacques; Reid, Mary; Romme, Bill; Seybold, Steven J.; Six, Diana; Vandygriff, Jim; Veblen, Tom; White, Mike; Witcosky, Jeff; Wood, David
2005-01-01
Since 1990, native bark beetles have killed billions of trees across millions of acres of forest from Alaska to northern Mexico. Although bark beetle infestations are a regular force of natural change in forested ecosystems, several of the current outbreaks, which are occurring simultaneously across western North America, are the largest and most severe in recorded history.
17. Sand hazards on tourist beaches.
Science.gov (United States)
Heggie, Travis W
2013-01-01
Visiting the beach is a popular tourist activity worldwide. Unfortunately, the beach environment is abundant with hazards and potential danger to the unsuspecting tourist. While the traditional focus of beach safety has been water safety oriented, there is growing concern about the risks posed by the sand environment on beaches. This study reports on the death and near death experience of eight tourists in the collapse of sand holes, sand dunes, and sand tunnels. Each incident occurred suddenly and the complete burial in sand directly contributed to the victims injury or death in each case report.
18. A dynamical model for bark beetle outbreaks.
Science.gov (United States)
Křivan, Vlastimil; Lewis, Mark; Bentz, Barbara J; Bewick, Sharon; Lenhart, Suzanne M; Liebhold, Andrew
2016-10-21
Tree-killing bark beetles are major disturbance agents affecting coniferous forest ecosystems. The role of environmental conditions on driving beetle outbreaks is becoming increasingly important as global climatic change alters environmental factors, such as drought stress, that, in turn, govern tree resistance. Furthermore, dynamics between beetles and trees are highly nonlinear, due to complex aggregation behaviors exhibited by beetles attacking trees. Models have a role to play in helping unravel the effects of variable tree resistance and beetle aggregation on bark beetle outbreaks. In this article we develop a new mathematical model for bark beetle outbreaks using an analogy with epidemiological models. Because the model operates on several distinct time scales, singular perturbation methods are used to simplify the model. The result is a dynamical system that tracks populations of uninfested and infested trees. A limiting case of the model is a discontinuous function of state variables, leading to solutions in the Filippov sense. The model assumes an extensive seed-bank so that tree recruitment is possible even if trees go extinct. Two scenarios are considered for immigration of new beetles. The first is a single tree stand with beetles immigrating from outside while the second considers two forest stands with beetle dispersal between them. For the seed-bank driven recruitment rate, when beetle immigration is low, the forest stand recovers to a beetle-free state. At high beetle immigration rates beetle populations approach an endemic equilibrium state. At intermediate immigration rates, the model predicts bistability as the forest can be in either of the two equilibrium states: a healthy forest, or a forest with an endemic beetle population. The model bistability leads to hysteresis. Interactions between two stands show how a less resistant stand of trees may provide an initial toe-hold for the invasion, which later leads to a regional beetle outbreak in the
19. Antinociceptive activity of Maytenus rigida stem bark.
Science.gov (United States)
Dias, Kellyane S; Marques, Maxsuel S; Menezes, Igor A C; Santos, Thiago C; Silva, Aline B L; Estevam, Charles S; Sant'Ana, Antônio E G; Pizza, Cosimo; Antoniolli, Angelo R; Marçal, Rosilene M
2007-12-01
Ethanol extract of Maytenus rigida stem bark and its fractions were assessed for antinociceptive activity in tail-flick test in rats. The activity was located in the chloroform, ethyl acetate and aq.methanol fractions. Phytochemical screening revealed that catechin was the only common class of compounds present on the ethanol extract as well as on the active fractions. 4'-Methylepigallocatechin, isolated from the ethyl acetate and aq.methanol fractions, showed antinociceptive effect in the tail-flick test (75 mg/kg; p.o.), which was reversed by the opiate antagonist naloxone (3 mg/kg; i.p.).
20. PROCESSING OF MONAZITE SAND
Science.gov (United States)
Calkins, G.D.; Bohlmann, E.G.
1957-12-01
A process for the recovery of thorium, uranium, and rare earths from monazite sands is presented. The sands are first digested and dissolved in concentrated NaOH, and the solution is then diluted causing precipitation of uranium, thorium and rare earth hydroxides. The precipitate is collected and dissolved in HCl, and the pH of this solution is adjusted to about 6, precipitating the hydroxides of thorium and uranium but leaving the rare earths in solution. The rare earths are then separated from the solution by precipitation at a still higher pH. The thorium and uranium containing precipitate is redissolved in HNO/sub 3/ and the two elements are separated by extraction into tributyl phosphate and back extraction with a weakly acidic solution to remove the thorium.
1. INORGANIC STATUS OF STEM BARK OF PTEROCARPUS MARSUPIUM
Directory of Open Access Journals (Sweden)
2011-06-01
Full Text Available Pterocarpus marsupium is well known for its sugar lowering potential. In the present examination different bark samples (Apical bark, middle bark and mature inner bark of Pterocarpus marsupium were screened for inorganic status. The levels of macro-minerals Nitrogen (1.50-3.13%, Phosphorus (0.023-0.163%, Calcium (0.60-1.848%, and Magnesium (0.21-0.339%, levels of trace minerals Copper (0.68-3.2mg/100g, Zinc (1.98-3.62mg/100g, Manganese (2.0-4.94mg/100g and Iron (11.38-44.34mg/100g and heavy metals Chromium (2.08-3.94mg/100g and Nickel (0.32-1.26mg/100g were evaluated in the present study. Cadmium and Lead were found to be absent in all the bark samples analyzed.
2. Moving sand dunes
CERN Document Server
Sparavigna, Amelia Carolina
2011-01-01
In several desert areas, the slow motion of sand dunes can be a challenge for modern human activities and a threat for the survival of ancient places or archaeological sites. However, several methods exist for surveying the dune fields and estimate their migration rate. Among these methods, the use of satellite images, in particular of those freely available on the World Wide Web, is a convenient resource for the planning of future human settlements and activities.
3. The extraction of bitumen from western oil sands: Volume 1. Final report
Energy Technology Data Exchange (ETDEWEB)
Oblad, A.G.; Dahlstrom, D.A.; Deo, M.D.; Fletcher, J.V.; Hanson, F.V.; Miller, J.D.; Seader, J.D.
1997-11-26
The program is composed of 20 projects, of which 17 are laboratory bench or laboratory pilot scale processes or computer process simulations that are performed in existing facilities on the University of Utah campus in north-east Salt Lake City. These tasks are: (1) coupled fluidized-bed bitumen recovery and coked sand combustion; (2) water-based recovery of bitumen; (3) oil sand pyrolysis in a continuous rotary kiln reactor; (4) oil sand pyrolysis in a large diameter fluidized bed reactor; (5) oil sand pyrolysis in a small diameter fluidized bed reactor; (6) combustion of spent sand in a transport reactor; (7) recovery and upgrading of oil sand bitumen using solvent extraction methods; (8) fixed-bed hydrotreating of Uinta Basin bitumens and bitumen-derived hydrocarbon liquids; (9) ebullieted bed hydrotreating of bitumen and bitumen derived liquids; (10) bitumen upgrading by hydropyrolysis; (11) evaluation of Utahs major oil sand deposits for the production of asphalt, high-energy jet fuels and other specialty products; (12) characterization of the bitumens and reservoir rocks from the Uinta Basin oil sand deposits; (13) bitumen upgrading pilot plant recommendations; (14) liquid-solid separation and fine tailings thickening; (15) in-situ production of heavy oil from Uinta Basin oil sand deposits; (16) oil sand research and development group analytical facility; and (17) process economics. This volume contains an executive summary and reports for five of these projects. 137 figs., 49 tabs.
4. The extraction of bitumen from western oil sands: Volume 2. Final report
Energy Technology Data Exchange (ETDEWEB)
Oblad, A.G.; Dahlstrom, D.A.; Deo, M.D.; Fletcher, J.V.; Hanson, F.V.; Miller, J.D.; Seader, J.D.
1997-11-26
The program is composed of 20 projects, of which 17 are laboratory bench or laboratory pilot scale processes or computer process simulations that are performed in existing facilities on the University of Utah campus in north-east Salt Lake City. These tasks are: (1) coupled fluidized-bed bitumen recovery and coked sand combustion; (2) water-based recovery of bitumen; (3) oil sand pyrolysis in a continuous rotary kiln reactor; (4) oil sand pyrolysis in a large diameter fluidized bed reactor; (5) oil sand pyrolysis in a small diameter fluidized bed reactor; (6) combustion of spent sand in a transport reactor; (7) recovery and upgrading of oil sand bitumen using solvent extraction methods; (8) fixed-bed hydrotreating of Uinta Basin bitumens and bitumen-derived hydrocarbon liquids; (9) ebullieted bed hydrotreating of bitumen and bitumen derived liquids; (10) bitumen upgrading by hydropyrolysis; (11) evaluation of Utahs major oil sand deposits for the production of asphalt, high-energy jet fuels and other specialty products; (12) characterization of the bitumens and reservoir rocks from the Uinta Basin oil sand deposits; (13) bitumen upgrading pilot plant recommendations; (14) liquid-solid separation and fine tailings thickening; (15) in-situ production of heavy oil from Uinta Basin oil sand deposits; (16) oil sand research and development group analytical facility; and (17) process economics. This volume contains reports on nine of these projects, references, and a bibliography. 351 refs., 192 figs., 65 tabs.
5. Comparison of protein profiles of beech bark disease-resistant or beech bark disease-susceptible American beech
Science.gov (United States)
Mary E. Mason; Marek Krasowski; Judy Loo; Jennifer. Koch
2011-01-01
Proteomic analysis of beech bark proteins from trees resistant and susceptible to beech bark disease (BBD) was conducted. Sixteen trees from eight geographically isolated stands, 10 resistant (healthy) and 6 susceptible (diseased/infested) trees, were studied. The genetic complexity of the sample unit, the sampling across a wide geographic area, and the complexity of...
6. Booming Sand Dunes
Science.gov (United States)
Vriend, Nathalie
"Booming" sand dunes are able to produce low-frequency sound that resembles a pure note from a music instrument. The sound has a dominant audible frequency (70-105 Hz) and several higher harmonics and may be heard from far distances away. A natural or induced avalanche from a slip face of the booming dune triggers the emission that may last for several minutes. There are various references in travel literature to the phenomenon, but to date no scientific explanation covered all field observations. This thesis introduces a new physical model that describes the phenomenon of booming dunes. The waveguide model explains the selection of the booming frequency and the amplification of the sound in terms of constructive interference in a confined geometry. The frequency of the booming is a direct function of the dimensions and velocities in the waveguide. The higher harmonics are related to the higher modes of propagation in the waveguide. The experimental validation includes quantitative field research at the booming dunes of the Mojave Desert and Death Valley National Park. Microphone and geophone recordings of the acoustic and seismic emission show a variation of booming frequency in space and time. The analysis of the sensor data quantifies wave propagation characteristics such as speed, dispersion, and nonlinear effects and allows the distinction between the source mechanism of the booming and the booming itself. The migration of sand dunes results from a complicated interplay between dune building, wind regime, and precipitation. The morphological and morphodynamical characteristics of two field locations are analyzed with various geophysical techniques. Ground-penetrating radar images the subsurface structure of the dunes and reveal a natural, internal layering that is directly related to the history of dune migration. The seismic velocity increases abruptly with depth and gradually increases with downhill position due to compaction. Sand sampling shows local
7. [From willow bark to acetylsalicylic acid].
Science.gov (United States)
Norn, Svend; Permin, Henrik; Kruse, Poul R; Kruse, Edith
2009-01-01
Acetylsalicylic acid is one of the most widely used drugs in the world. Its ancestry the salicylates, including salicin and salicylic acid, are found in the bark and leaves of the willow and poplar trees. The ancient Sumerians and Egyptians, as well as Hippocrates, Celsus, Pliny the Elder, Dioscorides and Galen used these natural products as remedies for pain, fever and inflammation. In the Middle Ages these remedies were used for fever and rheumatism by Hildegard of Bingen and Henrik Harpestreng. The first "clinical trial" was reported by Edward Stone in 1763 with a successful treatment of malarial fever with the willow bark. In 1876 the antirheumatic effect of salicin was described by T. MacLagan, and that of salicylic acid by S. Stricker and L. Riess. Acetylsalicylic acid was synthesized by Charles Gerhardt in 1853 and in 1897 by Felix Hoffmann in the Bayer Company. The beneficial effect of acetylsalicylic acid (Aspirin) on pain and rheumatic fever was recognized by K. Witthauer and J. Wohlgemuth, and the mechanism of action was explained in 1971 by John Vane. Today the antithrombotic effect of acetylsalicylic acid and new aspects of ongoing research demonstrates a still living drug.
8. Western Gas Sands Project. Status report, 1 January 1979--31 January 1979
Energy Technology Data Exchange (ETDEWEB)
Atkinson, C H
1979-01-01
Aim is to increase gas production from the low-permeability gas sands of the western U.S. Progress is reported on: project management, resource assessment, R and D at various facilities, and field tests and demonstrations. (DLC)
9. Proceedings from the Third Workshop on Genetics of Bark Beetles and Associated Microorganisms
Science.gov (United States)
Barbara Bentz; Anthony Cognato; Kenneth Raffa
2007-01-01
These proceedings provide a synopsis of the Third Workshop on Genetics of Bark Beetles and Association Microorganisms, which was held May 20-2, 2006 in Asheville, NC. Twenty- five participants from five countries attended the meeting. The proceedings are structured into four parts: Phylogenetics of Bark Beetles, Population Genetics of Bark Beetles, Bark Beetle Gene...
10. Sediment mathematical model for sand ridges and sand waves
Institute of Scientific and Technical Information of China (English)
LI Daming; WANG Xiao; WANG Xin; LI Yangyang
2016-01-01
A new theoretical model is formulated to describe internal movement mechanisms of the sand ridges and sand waves based on the momentum equation of a solid-liquid two-phase flow under a shear flow. Coupling this equation with two-dimensional shallow water equations and wave reflection-diffraction equation of mild slope, a two-dimensional coupling model is established and a validation is carried out by observed hydrogeology, tides, waves and sediment. The numerical results are compared with available observations. Satisfactory agreements are achieved. This coupling model is then applied to the Dongfang 1-1 Gas Field area to quantitatively predict the movement and evolution of submarine sand ridges and sand waves. As a result, it is found that the sand ridges and sand waves movement distance increases year by year, but the development trend is stable.
11. Compressive behavior of fine sand.
Energy Technology Data Exchange (ETDEWEB)
Martin, Bradley E. (Air Force Research Laboratory, Eglin, FL); Kabir, Md. E. (Purdue University, West Lafayette, IN); Song, Bo; Chen, Wayne (Purdue University, West Lafayette, IN)
2010-04-01
The compressive mechanical response of fine sand is experimentally investigated. The strain rate, initial density, stress state, and moisture level are systematically varied. A Kolsky bar was modified to obtain uniaxial and triaxial compressive response at high strain rates. A controlled loading pulse allows the specimen to acquire stress equilibrium and constant strain-rates. The results show that the compressive response of the fine sand is not sensitive to strain rate under the loading conditions in this study, but significantly dependent on the moisture content, initial density and lateral confinement. Partially saturated sand is more compliant than dry sand. Similar trends were reported in the quasi-static regime for experiments conducted at comparable specimen conditions. The sand becomes stiffer as initial density and/or confinement pressure increases. The sand particle size become smaller after hydrostatic pressure and further smaller after dynamic axial loading.
12. Sand dollar sites orogenesis
Science.gov (United States)
Amos, Dee
2013-04-01
The determinology of the humble sand dollars habitat changing from inception to the drastic evolution of the zone to that of present day. Into the cauldron along the southern Californian 'ring of fire' lithosphere are evidence of geosynclinals areas, metasedimentary rock formations and hydrothermal activity. The explanation begins with 'Theia' and the Moon's formation, battles with cometary impacts, glacial ages, epochs with evolutionary bottlenecks and plate tectonics. Fully illustrated the lecture includes localised diagrams and figures with actual subject photographic examples of plutonic, granitic, jade and peridodite. Finally, the origins of the materials used in the lecture are revealed for prosecution by future students and the enjoyment of interested parties in general.
13. Sand Storms Trigger Alarm
Institute of Scientific and Technical Information of China (English)
LI LI
2010-01-01
@@ After an unusually humid winter with at least 10 snowfalls in Beijing, a severe andstorm blown by strong winds bringing with it thousands of tons of desert sand took many residents of the city by surprise.On the morning of March 20, Beijingers woke up to see clouds of yellow dust in the air and a sky that was an ominous orange in color.The loose soil and dust that had traveled htmdreds of miles from deserts in Mongolia and China's northwest blanketed Beijing's streets, covering parked vehicles, bikes, roofs and even plant life,as well as making its way into people's homes.
Science.gov (United States)
2003-01-01
MGS MOC Release No. MOC2-432, 25 July 2003This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a field of small barchan sand dunes in the north polar region near 71.7oN, 51.3oW. Some of them are shaped like fortune cookies. The message these dunes provide: winds blow through this region from the lower right toward the upper left. The steep slip face slopes of these dunes, which point toward the upper left, indicate the wind direction. The scene is illuminated by sunlight from the upper right. The image is 3 km (1.9 mi) wide.
15. A family of sand automata
CERN Document Server
Faulkner, Nicholas
2012-01-01
We study some dynamical properties of a family of two-dimensional cellular automata: those that arise from an underlying one dimensional sand automaton whose local rule is obtained using a latin square. We identify a simple sand automaton G whose local rule is algebraic, and classify this automaton as having equicontinuity points, but not being equicontinuous. We also show it is not surjective. We generalise some of these results to a wider class of sand automata.
16. Dilatometric Characterization of Foundry Sands
Directory of Open Access Journals (Sweden)
M. Břuska
2012-04-01
Full Text Available The goal of this contribution is summary of physical – chemistry properties of usually used foundry silica and no – silica sands in Czech foundries. With the help of dilatometry analysis theoretical assumptions of influence of grain shape and size on dilatation value of sands were confirmed. Determined was the possibility of dilatometry analysis employment for preparing special (hybrid sands with lower and/or more linear character of dilatation.
17. Triaxial tests in Fontainebleau sand
DEFF Research Database (Denmark)
Latini, Chiara; Zania, Varvara
2016-01-01
The purpose of this internal report is to examine the influence of relative density on the strength and deformation characteristics of Fontainebleau sand. Compression triaxial tests were performed on saturated sand samples with different densities and initial confining pressure. Note that the tes......The purpose of this internal report is to examine the influence of relative density on the strength and deformation characteristics of Fontainebleau sand. Compression triaxial tests were performed on saturated sand samples with different densities and initial confining pressure. Note...... that the testing procedure and the data processing were carried out according to the specifications of ETCS-F1.97....
18. ANTIMICROBIAL ACTIVITY OF FICUS GLOMERATA LINN. BARK
Directory of Open Access Journals (Sweden)
Jagtap Supriya G.
2012-05-01
Full Text Available Ficus glomerata Linn. (Moraceae, commonly known as Ficus racemosa. A large deciduous tree distributed all over India and Ceylon, found throughout the year, grows in evergreen forest, moist localities, along the sides of ravines and banks of streams. Gular (Ficus glomerata Linn. is well known, commonly used plant in various disorders. It has been traditionally claimed to be useful in asthmatic condition, as an antitussive and anti-inflammatory. Successive soxhlet extractions of dried powdered bark were carried out using petroleum ether and methanol as a solvent. The antimicrobial activity of the extracts were tested in vitro against two different bacterial species Bacillus substilis and Escherichia coli by cup plate diffusion method were used in this investigation. The results of antimicrobial activity revealed that methanolic extract showed good activity as compared to petroleum ether extract. Methanolic extract is more potent towards gram - positive bacteria. The antimicrobial activities of the extracts were compared with standard antibiotics.
19. Constituents from the bark of Tabebuia impetiginosa.
Science.gov (United States)
Warashina, Tsutomu; Nagatani, Yoshimi; Noro, Tadataka
2004-07-01
The bark of Tabebuia impetiginosa afforded nineteen glycosides, consisting of four iridoid glycosides, two lignan glycosides, two isocoumarin glycosides, three phenylethanoid glycosides and eight phenolic glycosides. Their structures were determined using both spectroscopic and chemical methods. Iridoid glycosides, phenylethanoid glycosides and lignan glycosides had ajugol, osmanthuside H and secoisolariciresinol 4-O-beta-D-glucopyranoside as their structural elements, respectively, whereas the aglycone moieties of the isocoumarin glycosides were considered to be (-)-6-hydroxymellein. Phenolic glycosides had 4-methoxyphenol, 2,4-dimethoxyphenol, 3,4-dimethoxyphenol, 3,4,5-trimethoxyphenol and vanillyl 4-hydroxybenzoate as each aglycone moiety. Additionally, the sugar chains of these isocoumarin glycosides and phenolic glycosides were concluded to be beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside as well as those of osmanthuside H and above phenylethanoid glycosides.
20. MALDI-TOF MS analysis of condensed tannins with potent antioxidant activity from the leaf, stem bark and root bark of Acacia confusa.
Science.gov (United States)
Wei, Shu-Dong; Zhou, Hai-Chao; Lin, Yi-Ming; Liao, Meng-Meng; Chai, Wei-Ming
2010-06-15
The structures of the condensed tannins from leaf, stem bark and root bark of Acacia confusa were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, and their antioxidant activities were measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and ferric reducing/antioxidant power (FRAP) assays. The results showed that the condensed tannins from stem bark and root bark include propelargonidin and procyanidin, and the leaf condensed tannins include propelargonidin, procyanidin and prodelphinidin, all with the procyanidin dominating. The condensed tannins had different polymer chain lengths, varying from trimers to undecamers for leaf and root bark and to dodecamers for stem bark. The condensed tannins extracted from the leaf, stem bark and root bark all showed a very good DPPH radical scavenging activity and ferric reducing power.
1. Hepatocurative potential of Vitex doniana root bark, stem bark and leaves extracts against CCl4–induced liver damage in rats
Directory of Open Access Journals (Sweden)
James Dorcas Bolanle
2014-06-01
Conclusion: Hepatocurative study shows that all the plant parts (root bark, stem bark and leaves possess significant hepatocurative properties among other therapeutic values justifying their use in folklore medicine.
2. Vasorelaxant effect of Prunus yedoensis bark
Directory of Open Access Journals (Sweden)
Lee Kyungjin
2013-02-01
Full Text Available Abstract Background Prunus yedoensis Matsum. is used as traditional medicine—‘Yaeng-Pi’ or ‘Hua-Pi’—in Japan and Korea. However, no studies have examined the pharmacological activities of the P. yedoensis bark. Only the antioxidant and antiviral activities of P. yedoensis fruit and the anti-hyperglycaemic effect of P. yedoensis leaf have been investigated. While studying the antihypertensive effects of several medicinal plants, we found that a methanol extract of P. yedoensis bark (MEPY had distinct vasorelaxant effects on rat aortic rings. Methods The aortic rings were removed from Sprague–Dawley rats and suspended in organ chambers containing 10 ml Krebs-Henseleit solution. The aortic rings were placed between 2 tungsten stirrups and connected to an isometric force transducer. Changes in tension were recorded via isometric transducers connected to a data acquisition system. Results MEPY relaxed the contraction induced by phenylephrine (PE both in endothelium-intact and endothelium-denuded aortic rings concentration dependently. However, the vasorelaxant effects of MEPY on endothelium-denuded aortic rings were lower than endothelium-intact aortic rings. The vasorelaxant effects of MEPY on endothelium-intact aortic rings were reduced by pre-treatment with l-NAME, methylene blue, or ODQ. However, pre-treatment with indomethacin, atropine, glibenclamide, tetraethylammonium, or 4-aminopyridine had no affection. In addition, MEPY inhibited the contraction induced by extracellular Ca2+ in endothelium-denuded rat thoracic aorta rings pre-contracted by PE (1 μM or KCl (60 mM in Ca2+-free solution. Conclusions Our results suggest that MEPY exerts its vasorelaxant effects via the activation of NO formation by means of l-Arg and NO-cGMP pathways and via the blockage of extracellular Ca2+ channels.
3. Pheromone Chemistry of the Smaller European Elm Bark Beetle.
Science.gov (United States)
Beck, Keith
1978-01-01
Discusses the aggregation pheromone of the smaller European elm bark beetle, Scolytus multistriatus (Marsham), with emphasis on information that could be used in the classroom as a practical application of organic chemistry. (Author/GA)
4. Modulatory Effect of Morinda lucida Aqueous Stem Bark Extract on ...
African Journals Online (AJOL)
Dr Olaleye
analyses of the aqueous stem bark of Morinda lucida were conducted using standard procedures. Results showed that the ... disease and stroke, neuropathy, nephropathy, cataracts, .... β-cells destruction (Gupta et al., 1984). Fasting blood ...
5. Haematinic properties of methanolic stem bark and fruit extracts of ...
African Journals Online (AJOL)
Haematinic properties of methanolic stem bark and fruit extracts of Ficus sur in rats pre-exposed to ... African Journal of Biomedical Research ... The Haematocrit and Haemoglobin concentration and Red Blood Cell Count of rats treated with ...
6. Cytotoxic Constituents from bark and leaves of Amyris pinnata Kunth
National Research Council Canada - National Science Library
Luis Enrique Cuca-Suarez; Franco Della-Monache; Ericsson Coy-Barrera
2015-01-01
From leaves and bark of Amyris pinnata Kunth twelve compounds were isolated, corresponding to six lignans 1-6, three coumarins 7-9, a sesquiterpene 10, an oxazole alkaloid 11, and a prenylated flavonoid 12...
7. Antifungal activity of the stem bark of Ailanthus excelsa.
Science.gov (United States)
Joshi, B C; Pandey, Anuj; Chaurasia, Leena; Pal, Mahesh; Sharma, R P; Khare, Anakshi
2003-12-01
The methanol extract of stem barks of Alianthus excelsa was partitioned with chloroform. The chloroform extract showed fungistatic and fungicidal activity against Aspergillus niger, A. fumigatus, Penicillium frequentence, P. notatum and Botrytis cinerea.
8. Frac Sand Mines Are Preferentially Sited in Unzoned Rural Areas.
Science.gov (United States)
Locke, Christina
2015-01-01
Shifting markets can cause unexpected, stochastic changes in rural landscapes that may take local communities by surprise. Preferential siting of new industrial facilities in poor areas or in areas with few regulatory restrictions can have implications for environmental sustainability, human health, and social justice. This study focuses on frac sand mining-the mining of high-quality silica sand used in hydraulic fracturing processes for gas and oil extraction. Frac sand mining gained prominence in the 2000s in the upper midwestern United States where nonmetallic mining is regulated primarily by local zoning. I asked whether frac sand mines were more commonly sited in rural townships without formal zoning regulations or planning processes than in those that undertook zoning and planning before the frac sand boom. I also asked if mine prevalence was correlated with socioeconomic differences across townships. After creating a probability surface to map areas most suitable for frac sand mine occurrence, I developed neutral landscape models from which to compare actual mine distributions in zoned and unzoned areas at three different spatial extents. Mines were significantly clustered in unzoned jurisdictions at the statewide level and in 7 of the 8 counties with at least three frac sand mines and some unzoned land. Subsequent regression analyses showed mine prevalence to be uncorrelated with land value, tax rate, or per capita income, but correlated with remoteness and zoning. The predicted mine count in unzoned townships was over two times higher than that in zoned townships. However, the county with the most mines by far was under a county zoning ordinance, perhaps indicating industry preferences for locations with clear, homogenous rules over patchwork regulation. Rural communities can use the case of frac sand mining as motivation to discuss and plan for sudden land-use predicaments, rather than wait to grapple with unfamiliar legal processes during a period of
9. Frac Sand Mines Are Preferentially Sited in Unzoned Rural Areas.
Directory of Open Access Journals (Sweden)
Christina Locke
Full Text Available Shifting markets can cause unexpected, stochastic changes in rural landscapes that may take local communities by surprise. Preferential siting of new industrial facilities in poor areas or in areas with few regulatory restrictions can have implications for environmental sustainability, human health, and social justice. This study focuses on frac sand mining-the mining of high-quality silica sand used in hydraulic fracturing processes for gas and oil extraction. Frac sand mining gained prominence in the 2000s in the upper midwestern United States where nonmetallic mining is regulated primarily by local zoning. I asked whether frac sand mines were more commonly sited in rural townships without formal zoning regulations or planning processes than in those that undertook zoning and planning before the frac sand boom. I also asked if mine prevalence was correlated with socioeconomic differences across townships. After creating a probability surface to map areas most suitable for frac sand mine occurrence, I developed neutral landscape models from which to compare actual mine distributions in zoned and unzoned areas at three different spatial extents. Mines were significantly clustered in unzoned jurisdictions at the statewide level and in 7 of the 8 counties with at least three frac sand mines and some unzoned land. Subsequent regression analyses showed mine prevalence to be uncorrelated with land value, tax rate, or per capita income, but correlated with remoteness and zoning. The predicted mine count in unzoned townships was over two times higher than that in zoned townships. However, the county with the most mines by far was under a county zoning ordinance, perhaps indicating industry preferences for locations with clear, homogenous rules over patchwork regulation. Rural communities can use the case of frac sand mining as motivation to discuss and plan for sudden land-use predicaments, rather than wait to grapple with unfamiliar legal processes
10. Improved extraction of pine bark for wood adhesives
OpenAIRE
Jorge, Fernando Caldeira; Brito, Paulo; Pepino, Lina; Portugal, António; Gil, Maria Helena; IRLE, Mark A; Costa, Rui Pereira da
1999-01-01
Pine bark tannins must be subjected to sulphonation to have an acceptable solubility in water for the preparation of wood adhesives. In this study, several extraction variables (sodium sulphite and urea concentrations in the extraction white liquor, extraction time, bark/liquor ratio and temperature) were assessed for their effect on extraction yield, and on the phenol, sulphur and ash content of extracts. Temperature had the highest positive effect on extraction yield and on the yield of tot...
11. Characterisation of polyphenols in Terminalia arjuna bark extract
OpenAIRE
Anumita Saha; Pawar, V. M.; Sujatha Jayaraman
2012-01-01
The bark of Terminalia arjuna is known for its heart-health benefits in ayurvedic literature. This has been further supported by in vivo studies on animal and human volunteers. But there is no detailed study on identification of the active ingredients such as polyphenols. Polyphenols possesses antioxidant properties and are well-known health actives, it is important to characterise polyphenols in Terminalia arjuna. Aqueous extract of Terminalia arjuna bark was analysed for its composition and...
12. Estimation and relevance of bark proportion in a willow stand
Energy Technology Data Exchange (ETDEWEB)
Adler, Anneli [Swedish Univ. of Agricultural Sciences (SLU), Dept. of Short Rotation Forestry, Uppsala (Sweden); Estonian Agricultural Univ. (EAU), Inst. of Zoology and Botany, Tartu (Estonia); Verwijst, Theo; Aronsson, Paer [Swedish Univ. of Agricultural Sciences (SLU), Dept. of Short Rotation Forestry, Uppsala (Sweden)
2005-08-01
We studied bark proportion of a willow (Salix viminalis) plantation established to produce biomass for energy, the vertical distribution of elements (N, P, K, Mg, Ca, Co, Cu, Zn, As, Si, Cd, Cr, Pb, Hg and Ni) in bark and in wood of the shoots and the content of elements in the standing biomass. The study is based on 5-year-old shoots (clone 77-683) from a 12-year-old plantation. The bark proportion of the whole willow stand was 19% (9 tDM ha{sup -1}). The bark proportion of single shoots was constant after they had reached the size of 20 mm at stem diameter at 55 cm height. Compared to wood, bark had significantly higher concentrations of N, P, K, Mg, Ca, Cd, Pb, Co and Zn. The nutrient element (N, P, K, Mg) concentrations in the bark and in the wood of the current year shoot fractions (twigs) were significantly higher compared to the bark and the wood of other fractions. The accumulation of heavy metals occurred due to the accumulation of tree biomass and not due to the increase of heavy metal (Cd, Cr, Pb and Hg) concentrations in plant tissues over time. In summary, different management regimes give a possibility to influence shoot size frequency distribution of the crop and the chemical composition of biomass. For minimizing element removals from the soil and corrosion processes in power plants, energy willow stands should be managed in a way that promotes low bark proportion and thereby as little nutrient removal from the site by biomass harvest as possible. (Author)
13. A sand wave simulation model
NARCIS (Netherlands)
Nemeth, A.A.; Hulscher, S.J.M.H.; Damme, van R.M.J.
2003-01-01
Sand waves form a prominent regular pattern in the offshore seabeds of sandy shallow seas. A two dimensional vertical (2DV) flow and morphological numerical model describing the behaviour of these sand waves has been developed. The model contains the 2DV shallow water equations, with a free water su
14. Regeneration of dredged sand waves
NARCIS (Netherlands)
Hulscher, Suzanne J.M.H.; Knaapen, Michiel; Scholl, Olaf; Scholl, O.; Trenteseaux., A.; Garlan, T.
2000-01-01
Sand waves form a wavy pattern in the offshore sandy seabed. Since their crests reduce the navigability, it is important to know their evolution. A simple model is presented to estimate the recovery of sand wave amplitudes. This model is partially based on the similarity with sea ripples and
15. Namibia : triaxial test on sand
DEFF Research Database (Denmark)
Steenfelt, Jørgen S.; Jacobsen, Kim P.
In connection with a harbour project the friction angle of a fine sand is required. On Friday 13 March 1998 the Danish Geotechnical Institute (DGI) delivered app. 2.5 kg sand for testing at the Geotechnical Engineering Laboratory, Aalborg University. The present Data Report summarises the results...
16. Sand swimming lizard: sandfish
CERN Document Server
2009-01-01
We use high-speed x-ray imaging to reveal how a small (~10cm) desert dwelling lizard, the sandfish (Scincus scincus), swims within a granular medium [1]. On the surface, the lizard uses a standard diagonal gait, but once below the surface, the organism no longer uses limbs for propulsion. Instead it propagates a large amplitude single period sinusoidal traveling wave down its body and tail to propel itself at speeds up to ~1.5 body-length/sec. Motivated by these experiments we study a numerical model of the sandfish as it swims within a validated soft sphere Molecular Dynamics granular media simulation. We use this model as a tool to understand dynamics like flow fields and forces generated as the animal swims within the granular media. [1] Maladen, R.D. and Ding, Y. and Li, C. and Goldman, D.I., Undulatory Swimming in Sand: Subsurface Locomotion of the Sandfish Lizard, Science, 325, 314, 2009
17. 2010 oil sands performance report
Energy Technology Data Exchange (ETDEWEB)
NONE
2011-07-01
With the depletion of traditional energy resources and the rising demand for energy, oil sands have become an important energy resource for meeting energy needs. Oil sands are a mixture of water, sand, clay and bitumen which is recovered either through open pit mining or in situ drilling techniques. The bitumen is then converted into syncrude or sold to refineries for the production of gasoline, diesel or other products. Shell has oil sands operations in Alberta and the aim of this report is to present its 2010 performance in terms of CO2, water, tailings, land, and reclamation and engagement. This document covers several of Shell's operations in the Muskeg River and Jackpine mines, Scotford upgrader, Peace River, Orion, Seal, Cliffdale and Chipmunk. It provides useful information on Shell's oil sands performance to governments, environmental groups, First Nations, local communities and the public.
18. DNA Extraction and Amplification from Contemporary Polynesian Bark-Cloth
Science.gov (United States)
Moncada, Ximena; Payacán, Claudia; Arriaza, Francisco; Lobos, Sergio; Seelenfreund, Daniela; Seelenfreund, Andrea
2013-01-01
Background Paper mulberry has been used for thousands of years in Asia and Oceania for making paper and bark-cloth, respectively. Museums around the world hold valuable collections of Polynesian bark-cloth. Genetic analysis of the plant fibers from which the textiles were made may answer a number of questions of interest related to provenance, authenticity or species used in the manufacture of these textiles. Recovery of nucleic acids from paper mulberry bark-cloth has not been reported before. Methodology We describe a simple method for the extraction of PCR-amplifiable DNA from small samples of contemporary Polynesian bark-cloth (tapa) using two types of nuclear markers. We report the amplification of about 300 bp sequences of the ITS1 region and of a microsatellite marker. Conclusions Sufficient DNA was retrieved from all bark-cloth samples to permit successful PCR amplification. This method shows a means of obtaining useful genetic information from modern bark-cloth samples and opens perspectives for the analyses of small fragments derived from ethnographic materials. PMID:23437166
19. DNA extraction and amplification from contemporary Polynesian bark-cloth.
Directory of Open Access Journals (Sweden)
Full Text Available BACKGROUND: Paper mulberry has been used for thousands of years in Asia and Oceania for making paper and bark-cloth, respectively. Museums around the world hold valuable collections of Polynesian bark-cloth. Genetic analysis of the plant fibers from which the textiles were made may answer a number of questions of interest related to provenance, authenticity or species used in the manufacture of these textiles. Recovery of nucleic acids from paper mulberry bark-cloth has not been reported before. METHODOLOGY: We describe a simple method for the extraction of PCR-amplifiable DNA from small samples of contemporary Polynesian bark-cloth (tapa using two types of nuclear markers. We report the amplification of about 300 bp sequences of the ITS1 region and of a microsatellite marker. CONCLUSIONS: Sufficient DNA was retrieved from all bark-cloth samples to permit successful PCR amplification. This method shows a means of obtaining useful genetic information from modern bark-cloth samples and opens perspectives for the analyses of small fragments derived from ethnographic materials.
20. Sand harm in taklimakan Desert highway and sand control
Institute of Scientific and Technical Information of China (English)
HANZhiwen; WANGTao; SUNQingwei; DONGZhibao; WANGXunming
2003-01-01
Reputed as a wonderful achievement of the world’s highway construction history,the Taklimakan Desert highway is nor facing serious sand drift encroachment problems due to its 447-km-long passage of sand sea consisting of crescent dunes,barchan chains,compound transverse dune ridges and complex megadunes.To solve some technical problems in the protection of the highway from sang drift encroachment,desert experts have been conducting the theoretical and applied studies on sand movement laws;causes,severities and time-space differentiation of sand drift damages;and control ways including mechanical,chemical and biological measures.In this paper the authors give an overall summry on the research contents and recent progress in the control of sand drift damages in China and hold that the theoretical researc results and practices in the prevention of sand drift encroachment on the cross-desert highway represnt a breakthrough and has an cpoch-making significance.Since the construction of protective forest along the cross-desert highway requires large amount of ground water,what will be its environmental consequence and whether it can effectively halt sand drift encroachment on the highway forever are the questions to be studied urgently.
1. Bark- and wood-borer colonization of logs and lumber after heat treatment to ISPM 15 specifications: the role of residual bark.
Science.gov (United States)
Haack, Robert A; Petrice, Toby R
2009-06-01
Wood packaging material (WPM) is a major pathway for international movement of bark- and wood-infesting insects. ISPM 15, the first international standard for treating WPM, was adopted in 2002 and first implemented in the United States in 2006. ISPM 15 allows bark to remain on WPM after treatment, raising concerns that insects could infest after treatment, especially if bark were present. We conducted field studies to evaluate insect infestation of green logs and lumber with varying amounts of bark after heat treatment. In a log study, Cerambycidae and Scolytinae (ambrosia beetles and bark beetles) readily infested and developed in logs with bark after heat treatment. In a lumber study, Cerambycidae and bark beetles laid eggs in all sizes of bark patches tested (approximately 25, 100, 250, and 1,000 cm2) after heat treatment but did not infest control or heat-treated lumber without bark. Cerambycidae completed development only in boards with bark patches of 1,000 cm2, whereas bark beetles completed development on patches of 100, 250, and 1,000 cm2. Survival of bark beetles was greater in square patches (10 by 10 cm) versus rectangular patches (2.5 by 40 cm) of the same surface area (100 cm2). In surveys at six U.S. ports in 2006, 9.4% of 5,945 ISPM 15-marked WPM items contained bark, and 1.2% of 564 ISPM 15-marked WPM items with bark contained live insects of quarantine significance under the bark. It was not possible to determine whether the presence of live insects represented treatment failure or infestation after treatment.
2. Volatile Organic Compounds Emitted by Fungal Associates of Conifer Bark Beetles and their Potential in Bark Beetle Control.
Science.gov (United States)
Kandasamy, Dineshkumar; Gershenzon, Jonathan; Hammerbacher, Almuth
2016-09-01
Conifer bark beetles attack and kill mature spruce and pine trees, especially during hot and dry conditions. These beetles are closely associated with ophiostomatoid fungi of the Ascomycetes, including the genera Ophiostoma, Grosmannia, and Endoconidiophora, which enhance beetle success by improving nutrition and modifying their substrate, but also have negative impacts on beetles by attracting predators and parasites. A survey of the literature and our own data revealed that ophiostomatoid fungi emit a variety of volatile organic compounds under laboratory conditions including fusel alcohols, terpenoids, aromatic compounds, and aliphatic alcohols. Many of these compounds already have been shown to elicit behavioral responses from bark beetles, functioning as attractants or repellents, often as synergists to compounds currently used in bark beetle control. Thus, these compounds could serve as valuable new agents for bark beetle management. However, bark beetle associations with fungi are very complex. Beetle behavior varies with the species of fungus, the stage of the beetle life cycle, the host tree quality, and probably with changes in the emission rate of fungal volatiles. Additional research on bark beetles and their symbiotic associates is necessary before the basic significance of ophiostomatoid fungal volatiles can be understood and their applied potential realized.
3. Sand engine quells the coast's hunger for sand
NARCIS (Netherlands)
Van Dijk, T.
2012-01-01
An artificial peninsula at Ter Heijde is designed to feed the coast with sediment. Scientists are investigating whether this kind of sand engine could be the Netherlands’ answer to rising sea levels.
4. Sand engine quells the coast's hunger for sand
NARCIS (Netherlands)
Van Dijk, T.
2012-01-01
An artificial peninsula at Ter Heijde is designed to feed the coast with sediment. Scientists are investigating whether this kind of sand engine could be the Netherlands’ answer to rising sea levels.
5. Spectroscopic characterization of a Nigerian standard sand: Igbokoda sand
CSIR Research Space (South Africa)
Ojuri, OO
2017-01-01
Full Text Available the Middle Ordovician St. Peter Sandstone near Ottawa, Illinois, had been picked by the American Society for Testing and Materials (ASTM) as the reference sand to employ in testing cement and strength of concrete [9]. To the best of our knowledge... and magnetic resonance spectroscopic techniques due to its importance in cement, geotechnical/geo-environmental research in Nigeria. This should halt importation of standard silica sand for mortar and concrete testing...
6. Saltation of Non-Spherical Sand Particles
Science.gov (United States)
Wang, Zhengshi; Ren, Shan; Huang, Ning
2014-01-01
Saltation is an important geological process and the primary source of atmospheric mineral dust aerosols. Unfortunately, no studies to date have been able to precisely reproduce the saltation process because of the simplified theoretical models used. For example, sand particles in most of the existing wind sand movement models are considered to be spherical, the effects of the sand shape on the structure of the wind sand flow are rarely studied, and the effect of mid-air collision is usually neglected. In fact, sand grains are rarely round in natural environments. In this paper, we first analyzed the drag coefficients, drag forces, and starting friction wind speeds of sand grains with different shapes in the saltation process, then established a sand saltation model that considers the coupling effect between wind and the sand grains, the effect of the mid-air collision of sand grains, and the effect of the sand grain shape. Based on this model, the saltation process and sand transport rate of non-spherical sand particles were simulated. The results show that the sand shape has a significant impact on the saltation process; for the same wind speed, the sand transport rates varied for different shapes of sand grains by as much as several-fold. Therefore, sand shape is one of the important factors affecting wind-sand movement. PMID:25170614
7. [Lignans from barks of Ailanthus altissima].
Science.gov (United States)
Liu, Dong; Zhang, Jian; Tang, Shao-Nan; Zhang, Xiao-Qi; Ye, Wen-Cai
2016-12-01
Eleven lignans were isolated from the ethanol extract of the barks of Ailanthus altissima through various column chromatography methods including silica gel, Sephadex LH-20, ODS and HPLC. By physical, chemical and comprehensive spectroscopic methods, their structures were identified as (+)-neoolivil(1), prunustosanan AI (2), (7S,8R)-guaiacyl-glycerol-β-O-4'-neolignan (3), (7R,8S)-guaiacyl-glycerol-β-O-4'-neolignan (4), (7S,8R)-1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-hydroxypropyl)-2,6-dimethoxyphenoxy]-1,3-propanediol(5), pinnatifidanin B V (6), pinnatifidanin B VI (7), (7R,7'R,7″S,8S,8'S,8″S)-4',4″-dihydroxy-3,3',3″,5-tetramethoxy-7,9':7',9-diepoxy-4,8″-oxy-8,8'-sesquineolignan-7″,9″-diol (8), hedyotol D (9), 5-(2-propenyl)-7-methoxy-2-(3,4-methylenediovxyphenyl)benzofuran (10), and (7R,8S,7'E)-guaiacyl-glycerol-β-O-4'-sinapyl ether(11).All of these compounds were isolated from this plant for the first time. Copyright© by the Chinese Pharmaceutical Association.
8. Reclaimability of the spent sand mixture – sand with bentonite – sand with furfuryl resin
Directory of Open Access Journals (Sweden)
J. Dańko
2011-04-01
Full Text Available Introduction of new binding materials and new technologies of their hardening in casting moulds and cores production requires theapplication of reclamation methods adequate to their properties as well as special devices realizing tasks. The spent sands circulationsystem containing the same kind of moulding and core sands is optimal from the point of view of the expected reclamation results.However, in the face of a significant variability of applied technologies and related to them various reclamation methods, the need - of theobtained reclamation products assessment on the grounds of systematic criteria and uniform bases – arises, with a tendency of indicatingwhich criteria are the most important for the given sand system. The reclaimability results of the mixture of the spent moulding sand withGeko S bentonite and the spent core sand with the Kaltharz 404U resin hardened by acidic hardener 100 T3, are presented in the paper.Investigations were performed with regard to the estimation of an influence of core sands additions (10 –25% on the reclaimed materialquality. Dusts and clay content in the reclaim, its chemical reaction (pH and ignition loss were estimated. The verification of the reclaiminstrumental assessment was performed on the basis of the technological properties estimation of moulding sand with bentonite, where the reclaimed material was used as a matrix.
9. Management recommendations: Sand Lake Complex
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — This document is a review of land management practices at the Sand Lake National Wildlife Refuge, by a land use specialist. Recommendations, time frame and...
10. Utilization of flavonoid compounds from bark and wood: a review.
Science.gov (United States)
Yazaki, Yoshikazu
2015-03-01
11. Western Gas Sands Project status report
Energy Technology Data Exchange (ETDEWEB)
Atkinson, C.H.
1978-09-30
The status of government sponsored projects undertaken to increase gas production from low-permeability gas sands of the western United States during August 1978 is summarized. Background information is given in the September 1977 Status Report, NVO/0655-100. One of the largest massive Hydraulic Fracture (MHF) treatment to date was performed on Gas Producing Enterprises Well No. CIGE 2-29. C.H. Atkinson, Western Gas Sands Project (WGSP) Manager and D.C. Bleakly, CER Corporation were observers. Oriented coring operations on the Mitchell Energy well, Muse-Duke No. 1 were observed by Atkinson and Bleakly near Mexia, Texas. The Fourth Annual Department of Energy Symposium on Enhanced Oil and Gas Recovery and Improved Drilling Methods was held on August 29-31, 1978 in Tulsa, Oklahoma. The USGS continued geological and geophysical studies in the four primary study areas. Low-level oblique photography of Tertiary and Cretaceous rocks exposed in the Rock Springs Uplift area was completed, and core from the J.C. Paine well in Montana was sampled for petrograhic analysis. Bartlesville Energy Technology Center continued work on the improved pressure coring system and anticipates completion of the project by September 30, 1978. Preliminary work began on the Parametric Analysis of MHF Test Data, an Engineering Study of Western Gas Sands, by Intercomp. The National Laboratories, funded by DOE are continuing their work in the area of research and development. The emphasis is on instrumentation systems, rock mechanics, mathematical modeling, and data analysis. The Mitchell Energy well, Muse Duke No. 1, has reached total depth and was logged on August 31, 1978. The DOE well test facility was moved from the RB-MHF 3 well in Colorado to Vernal, Utah for trailer modifications and checkout.
12. Antioxidant Potential of Bark Extracts from Boreal Forest Conifers.
Science.gov (United States)
Legault, Jean; Girard-Lalancette, Karl; Dufour, Dominic; Pichette, André
2013-07-11
The bark of boreal forest conifers has been traditionally used by Native Americans to treat various ailments and diseases. Some of these diseases involve reactive oxygen species (ROS) that can be prevented by the consumption of antioxidants such as phenolic compounds that can be found in medicinal plants. In this study, ultrasonic assisted extraction has been performed under various solvent conditions (water:ethanol mixtures) on the bark of seven boreal forest conifers used by Native Americans including: Pinus strobus, Pinus resinosa, Pinus banksiana, Picea mariana, Picea glauca, Larix laricina, and Abies balsamea. The total phenolic content, as well as ORACFL potency and cellular antioxidant activity (IC50), were evaluated for all bark extracts, and compared with the standardized water extract of Pinus maritima bark (Pycnogenol), which showed clinical efficiency to prevent ROS deleterious effects. The best overall phenolic extraction yield and antioxidant potential was obtained with Picea glauca and Picea mariana. Interestingly, total phenolic content of these bark extracts was similar to Pycnogenol but their antioxidant activity were higher. Moreover, most of the extracts did not inhibit the growth of human skin fibroblasts, WS1. A significant correlation was found between the total phenolic content and the antioxidant activity for water extracts suggesting that these compounds are involved in the activity.
13. Pharmacognostic evaluation of stem bark of Pongamia pinnata (L.) Pierre
Institute of Scientific and Technical Information of China (English)
Dinesh Kumar; Ajay Kumar; Om Prakash
2012-01-01
Objective: To perform the pharmacognostic study of Pongamia pinnata (L.) Pierre (P. pinnata) stem bark. Method: The pharmacognostic studies were carried out in terms of organoleptic, macroscopic, microscopic, fluorescence analysis and physicochemical parameters. Results: The bark consisting of channelled, recurved, slightly quilled, usually 0.2-1 cm thick, lenticellate pieces with outer surface ash-grey to greyish-brown and internal surface yellowish-white to cream coloured having unpleasant odour and bitter taste. The main microscopic characterstics of the bark include phellem (5-20 or more layers of cork), phellogen (2-3 layered) followed by 10-15 layered phelloderm. Among other microscopic components were phloem parenchyma, phloem fibre and stone cells, traversed by wavy medullary rays. Further, physicochemical analysis of the bark power showed total ash, water soluble ash, acid insoluble ash and sulphated ash as 10.94, 1.96, 1.47 and 15.8 % w/w respectively. The alcohol and water soluble extractives values of the stem bark were 9.6 and 18.4 %w/w respectively. Conclusions: Various pharmacognostic characters observed in this study helps in botanical identification and standardization of P. pinnata L. in crude form.
14. Antimicrobial screening of ethnobotanically important stem bark of medicinal plants
Directory of Open Access Journals (Sweden)
Meenakshi Singh
2010-01-01
Full Text Available Background: The stem barks are the rich sources of tannins and other phenolic compounds. Tannins inhibited the growth of various fungi, yeast, bacteria and virus. Hence, ten stem barks of ethnomedicinally important plants were screened for antibacterial and antifungal activities against human pathogenic strains. Methods: Air-dried and powdered stem bark of each plant was extracted with 50% aqueous ethanol, lyophilized and the dried crude extracts were used for the screening against 11 bacteria and 8 fungi. Antibacterial and antifungal activities were performed according to microdilution methods by NCCLS. Results: The plants Prosopis chilensis, Pithecellobium dulce, Mangifera indica showed significant antibacterial and antifungal activities against Streptococcus pneumonia, Enterobacter aerogenes, Klebsiella pneumonia and Candida albicans with MIC of 0.08mg/ml. Pithecellobium dulce bark also showed significant antibacterial activity against Bacillus cereus. Conclusion: The bark of Pithecellobium dulce has more or less similar activity against the known antibiotic and may be considered as potent antimicrobial agent for various infectious diseases.
15. Antioxidant Potential of Bark Extracts from Boreal Forest Conifers
Directory of Open Access Journals (Sweden)
Jean Legault
2013-07-01
Full Text Available The bark of boreal forest conifers has been traditionally used by Native Americans to treat various ailments and diseases. Some of these diseases involve reactive oxygen species (ROS that can be prevented by the consumption of antioxidants such as phenolic compounds that can be found in medicinal plants. In this study, ultrasonic assisted extraction has been performed under various solvent conditions (water:ethanol mixtures on the bark of seven boreal forest conifers used by Native Americans including: Pinus strobus, Pinus resinosa, Pinus banksiana, Picea mariana, Picea glauca, Larix laricina, and Abies balsamea. The total phenolic content, as well as ORACFL potency and cellular antioxidant activity (IC50, were evaluated for all bark extracts, and compared with the standardized water extract of Pinus maritima bark (Pycnogenol, which showed clinical efficiency to prevent ROS deleterious effects. The best overall phenolic extraction yield and antioxidant potential was obtained with Picea glauca and Picea mariana. Interestingly, total phenolic content of these bark extracts was similar to Pycnogenol but their antioxidant activity were higher. Moreover, most of the extracts did not inhibit the growth of human skin fibroblasts, WS1. A significant correlation was found between the total phenolic content and the antioxidant activity for water extracts suggesting that these compounds are involved in the activity.
16. Reducing hazardous heavy metal ions using mangium bark waste.
Science.gov (United States)
Khabibi, Jauhar; Syafii, Wasrin; Sari, Rita Kartika
2016-08-01
The objective of this study was to evaluate the characteristics of mangium bark and its biosorbent ability to reduce heavy metal ions in standard solutions and wastewater and to assess changes in bark characteristics after heavy metal absorption. The experiments were conducted to determine heavy metal absorption from solutions of heavy metals alone and in mixtures as well as from wastewater. The results show that mangium bark can absorb heavy metals. Absorption percentages and capacities from single heavy metal solutions showed that Cu(2+) > Ni(2+) > Pb(2+) > Hg(2+), while those from mixture solutions showed that Hg(2+) > Cu(2+) > Pb(2+) > Ni(2+). Wastewater from gold mining only contained Cu, with an absorption percentage and capacity of 42.87 % and 0.75 mg/g, respectively. The highest absorption percentage and capacity of 92.77 % and 5.18 mg/g, respectively, were found for Hg(2+) in a mixture solution and Cu(2+) in single-metal solution. The Cu(2+) absorption process in a single-metal solution changed the biosorbent characteristics of the mangium bark, yielding a decreased crystalline fraction; changed transmittance on hydroxyl, carboxyl, and carbonyl groups; and increased the presence of Cu. In conclusion, mangium bark biosorbent can reduce hazardous heavy metal ions in both standard solutions and wastewater.
17. Analgesic and anti-inflammatory activity of root bark of Grewia asiatica Linn. in rodents
Directory of Open Access Journals (Sweden)
Udaybhan Singh Paviaya
2013-01-01
Conclusions: The present study indicates that root bark of G. asiatica exhibits peripheral and central analgesic effect and anti-inflammatory activity, which may be attributed to the various phytochemicals present in root bark of G. asiatica.
18. A small animal model study of perlite and fir bark dust on guinea pig lungs.
Science.gov (United States)
McMichael, R F; DiPalma, J R; Blumenstein, R; Amenta, P S; Freedman, A P; Barbieri, E J
1983-05-01
Fir bark (Abies) and perlite (noncrystalline silicate) dusts have been reported to cause pulmonary disease in humans. Guinea pigs were exposed to either fir bark or perlite dust in a special chamber. Severe pathologic changes occurred in the lungs, consisting of lymphoid aggregated and a perivascular inflammatory response. Both dusts caused similar changes although one was vegetable (fir bark) and the other mineral (perlite). Fir bark and perlite dust appeared to be more than just nuisance dusts.
19. Effect of bark beetle (Ips typographus L.) attack on bark VOC emissions of Norway spruce (Picea abies Karst.) trees
Science.gov (United States)
Ghimire, Rajendra P.; Kivimäenpää, Minna; Blomqvist, Minna; Holopainen, Toini; Lyytikäinen-Saarenmaa, Päivi; Holopainen, Jarmo K.
2016-02-01
Climate warming driven storms are evident causes for an outbreak of the European spruce bark beetle (Ips typographus L.) resulting in the serious destruction of mature Norway spruce (Picea abies Karst.) forests in northern Europe. Conifer species are major sources of biogenic volatile organic compounds (BVOCs) in the boreal zone. Climate relevant BVOC emissions are expected to increase when conifer trees defend against bark beetle attack by monoterpene (MT)-rich resin flow. In this study, BVOC emission rates from the bark surface of beetle-attacked and non-attacked spruce trees were measured from two outbreak areas, Iitti and Lahti in southern Finland, and from one control site at Kuopio in central Finland. Beetle attack increased emissions of total MTs 20-fold at Iitti compared to Kuopio, but decreased the emissions of several sesquiterpenes (SQTs) at Iitti. At the Lahti site, the emission rate of α-pinene was positively correlated with mean trap catch of bark beetles. The responsive individual MTs were tricyclene, α-pinene, camphene, myrcene, limonene, 1,8-cineole and bornyl acetate in both of the outbreak areas. Our results suggest that bark beetle outbreaks affect local BVOC emissions from conifer forests dominated by Norway spruce. Therefore, the impacts of insect outbreaks are worth of consideration to global BVOC emission models.
20. Antimicrobial activity of some medicinal barks used in Peruvian Amazon.
Science.gov (United States)
Kloucek, P; Svobodova, B; Polesny, Z; Langrova, I; Smrcek, S; Kokoska, L
2007-05-04
The aim of this study was to evaluate the antimicrobial activity of six barks traditionally used in Callería District (Ucayali Department, Peru) for treating conditions likely to be associated with microorganisms. Ethanol extracts of stem barks of Abuta grandifolia (Menispermaceae), Dipteryx micrantha (Leguminosae), Cordia alliodora (Boraginaceae), Naucleopsis glabra (Moraceae), Pterocarpus rohrii (Leguminosae), and root bark of Maytenus macrocarpa (Celastraceae) were tested against nine bacteria and one yeast using the broth microdilution method. All plants possessed significant antimicrobial effect, however, the extract of Naucleopsis glabra exhibited the strongest activity against Gram-positive bacteria (MICs ranging from 62.5 to 125 microg/ml), while the broadest spectrum of action was shown by the extract of Maytenus macrocarpa, which inhibited all the strains tested with MICs ranging from 125 to 250 microg/ml.
1. Tannins quantification in barks of Mimosa tenuiflora and Acacia mearnsii
Directory of Open Access Journals (Sweden)
Leandro Calegari
2016-03-01
Full Text Available Due to its chemical complexity, there are several methodologies for vegetable tannins quantification. Thus, this work aims at quantifying both tannin and non-tannin substances present in the barks of Mimosa tenuiflora and Acacia mearnsii by two different methods. From bark particles of both species, analytical solutions were produced by using a steam-jacketed extractor. The solution was analyzed by Stiasny and hide-powder (no chromed methods. For both species, tannin levels were superior when analyzed by hide-powder method, reaching 47.8% and 24.1% for A. mearnsii and M. tenuiflora, respectively. By Stiasny method, the tannins levels considered were 39.0% for A. mearnsii, and 15.5% for M. tenuiflora. Despite the best results presented by A. mearnsii, the bark of M. tenuiflora also showed great potential due to its considerable amount of tannin and the availability of the species at Caatinga biome.
2. Comparisons of protein profiles of beech bark disease resistant and susceptible American beech (Fagus grandifolia)
Science.gov (United States)
Mary E. Mason; Jennifer L. Koch; Marek Krasowski; Judy. Loo
2013-01-01
Beech bark disease is an insect-fungus complex that damages and often kills American beech trees and has major ecological and economic impacts on forests of the northeastern United States and southeastern Canadian forests. The disease begins when exotic beech scale insects feed on the bark of trees, and is followed by infection of damaged bark tissues by one of the...
3. PHYTOCHEMICAL SCREENING AND MICROBICIDAL ACTIVITY OF STEM BARK OF PTEROCARPUS MARSUPIUM
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Udaysing Hari Patil,
2011-01-01
Full Text Available Bactericidal potential of methanolic extract of stem bark (Apical bark, middle bark and Mature bark of Pterocarpus marsupium was evaluated with respect to pathogenic bacteria Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoneae, Salmonella typhi, Proteus mirabilis and Micrococcus sp. The methanolic extract of apical stem bark was effective than the middle bark and mature bark in inhibiting the growth of all bacteria. The bacterium Staphylococcus aureus was most sensitive among all the bacterial species studied. Preliminary phytochemical analysis revealed the presence of alkaloids, glycosides,flavonoids, flavonols, phenols and terpenoids. Saponins were absent in all the bark samples.The concentrations of these phytoconstituents was higher in the apical stem bark than the middle and mature stem bark. The percent extract yield was maximum in apical stem bark. Thus, in the pharmacological point of view, it is important to study the biochemistry of apical bark in order to isolate and screen the new pharmacological active principals which can be useful in designing of new drugs active against various infectious micro- rganisms like bacteria, fungi and viruses etc.
4. Factors controlling bark decomposition and its role in wood decomposition in five tropical tree species
Science.gov (United States)
Dossa, Gbadamassi G. O.; Paudel, Ekananda; Cao, Kunfang; Schaefer, Douglas; Harrison, Rhett D.
2016-01-01
Organic matter decomposition represents a vital ecosystem process by which nutrients are made available for plant uptake and is a major flux in the global carbon cycle. Previous studies have investigated decomposition of different plant parts, but few considered bark decomposition or its role in decomposition of wood. However, bark can comprise a large fraction of tree biomass. We used a common litter-bed approach to investigate factors affecting bark decomposition and its role in wood decomposition for five tree species in a secondary seasonal tropical rain forest in SW China. For bark, we implemented a litter bag experiment over 12 mo, using different mesh sizes to investigate effects of litter meso- and macro-fauna. For wood, we compared the decomposition of branches with and without bark over 24 mo. Bark in coarse mesh bags decomposed 1.11–1.76 times faster than bark in fine mesh bags. For wood decomposition, responses to bark removal were species dependent. Three species with slow wood decomposition rates showed significant negative effects of bark-removal, but there was no significant effect in the other two species. Future research should also separately examine bark and wood decomposition, and consider bark-removal experiments to better understand roles of bark in wood decomposition. PMID:27698461
5. Grinding and classification of pine bark for use as plywood adhesive filler
Science.gov (United States)
Thomas L. Eberhardt; Karen G. Reed
2005-01-01
Prior efforts to incorporate bark or bark extracts into composites have met with only limited success because of poor performance relative to existing products and/or economic barriers stemming from high levels of processing. We are currently investigating applications for southern yellow pine (SYP) bark that require intermediate levels of processing, one being the use...
6. DEVELOPMENT OF QUALITY STANDARDS OF BERBERIS ARISTATA STEM BARK
Directory of Open Access Journals (Sweden)
2012-02-01
Full Text Available Berberis aristata is an important medicinal plant of family Berberidaceae. It is commonly known as Zarishk and Daruhaldi. It is mainly used for the treatment piles, liver diseases and diabetes. As the herb is used widely in the Indian traditional systems of medicine, it was thought worthwhile to develop the quality standards for its stem bark. The results of Pharmacognostic standardization of stem bark of B. aristata are very helpful in determination of quality and purity of the crude drug and its marketed formulation.
7. The Utilization of Bark to Make Rigid Polyurethane Foams
Science.gov (United States)
D'Souza, Jason
This work focused on the characterization of polyols derived from the liquefaction or alkoxylation of bark. Regarding liquefaction, it was found that both temperature and solvent structure played a significant role in polyol properties. High temperature liquefaction resulted in the degradation of sugars, while liquefaction at mild temperatures preserved sugar structures as shown by 31P-NMR. It was also shown that liquefaction at 130°C was ideal in terms of producing a polyol with a relatively at, broad, plateau of molecular weight distribution, whereas liquefaction at 90 and 160°C produced polyols with a large amount of low molecular weight compounds. Regarding solvent structure, it was found that polyhydric alcohols with short chain primary hydroxyls resulted in less sugar degradation products and less formation of condensation side-products. It is proposed that the highly polar environment promoted grafting and prevented condensation onto other biopolymers. Using organic solvents it was found that ketonic solvents like acetyl acetone and cyclohexanone, through their highly polar carbonyl group could engage in hydrogen bonding through electron donation/proton accepting interactions. These enabled the solvent to reduce the amount of condensation reactions and improve liquefaction yield. The liquefied bark-based polyols were then used to make polyurethane foams. It was found that when a diversity of hydroxyl groups were present the foaming rate was reduced and this may react a slower rate of curing and explain why the bark foams had a greater amount of cells that underwent coalescence. It was also observed that the bark foams had a low amount of closed-cell content. Since closed-cell content plays a role in dictating elastic compression, this may explain why the bark foams exhibited a lower elastic modulus. Finally, as a contrast to liquefaction, bark was alkoxylated. It was observed that the conversion yield was higher than liquefaction. The polyols had a high
8. Disturbance of the inclined inserting-type sand fence to wind-sand flow fields and its sand control characteristics
Science.gov (United States)
Cheng, Jian-jun; Lei, Jia-qiang; Li, Sheng-yu; Wang, Hai-feng
2016-06-01
The inclined inserting-type sand fence is a novel sand retaining wall adopted along the Lanxin High-Speed Railway II in Xinjiang for controlling and blocking sand movement. To verify the effectiveness of the new fence structure for sand prevention, a wind tunnel test was used for flow field test simulation of the sand fence. The results indicate that the inclined inserting-type sand fence was able to deflect the flow of the sand and was able to easily form an upward slant acceleration zone on the leeward side of the sand fence. As shown by the percentage change in sand collection rates on the windward side and the leeward side of the sand fence, the sand flux per unit area at 4 m height in the slant upward direction increased on the leeward side of the inclined inserting-type sand fence. By comparing the flow fields, this site is an acceleration zone, which also reaffirms the correspondence of wind-sand flow fields with the spatial distribution characteristic of the wind-carried sand motion. The field sand collection data indicates that under the effects of the inclined inserting-type sand fence, the sandy air currents passing in front and behind the sand fence not only changed in quality, but the grain composition and particle size also significantly changed, suggesting that the inclined inserting-type sand fence has a sorting and filtering effect on the sandy air currents that passed through. The fence retained coarse particulates on the windward side and fine particulates within the shade of the wind on the leeward side.
9. Effect of the Design Parameters on the Performance of Inner Recycling Continuous Sand Filter
Institute of Scientific and Technical Information of China (English)
CHEN Zhi-qiang; WEN Qin-xue; Lü Bing-nan
2002-01-01
A novel integrated water treatment facility, innerrecycling continuous sand filter, is discussed. The theory of micro-flocculation is applied in the sand-washing circulation system with continuous filtration and backwashing. The design and operation parameters,which affect the performance of the filter, are discussed.The key design parameters are provided as follows:diameter of filter material is 0.7 to 1.0 mm, depth of filter bed is 0.6 m, filtration velocity is less than 12 m/h,ratio of gas to water is 9:11 and sand recycling rate is 2 to 4 mm/min.
10. Improvement of nutritive value of acacia mangium bark by alkali treatment
Directory of Open Access Journals (Sweden)
Elizabeth Wina
2001-10-01
Full Text Available Bark, especially from Acacia mangium is a by-product from wood processing industries that commonly found in Indonesiaand in big amount will cause environmental problems. One of the alternatives to utilize bark is for animal feed. The aims of this experiment are to improve the nutritive value of bark by alkali treatments (urea and sodium hydroxide and to determine the level of substitution of elephant grass by bark. The experiment consisted of 3 in vitro studies and 1 in sacco study. In vitro studies consisted of 1 the use of urea or NaOH by wetting and incubation-method, 2 the use of different concentration of Na OH (0-4% by soaking method, 3 determination of substitution level of elephant grass by treated bark. In sacco study was conducted at 0, 6, 12, 24, 48 and 72 hours of incubation to compare the degradation of treated bark to elephant grass. The results show that urea treatment did not improve DM or OM digestibilities of bark. Soaking bark in 4% NaOH solution was more effective than wetting and incubation-method in improving in vitro digestibility. (49.26% vs19.56% for soaking and dry-method, respectively. In sacco studyl shows that treated bark had a very high solubility at 0 hour incubation but the degradation at 72 hours incubation was not significantly different from that of 0 hour incubation. The gas produced at in vitro study of treated bark was very low indicated that there was no degradation of bark at all. The level of substitution of elephant grass by treated bark up to 30% gave a non-significant digestibility value to that of 100% elephant grass. In conclusion, bark after tannin-extraction was a better feedstuff for animal feed. The soaking method in 4% NaOH solution improved the digestibility of bark significantly and the level of substitution of elephant grass by treated bark was 30%.
11. Optimal array of sand fences.
Science.gov (United States)
Lima, Izael A; Araújo, Ascânio D; Parteli, Eric J R; Andrade, José S; Herrmann, Hans J
2017-03-24
Sand fences are widely applied to prevent soil erosion by wind in areas affected by desertification. Sand fences also provide a way to reduce the emission rate of dust particles, which is triggered mainly by the impacts of wind-blown sand grains onto the soil and affects the Earth's climate. Many different types of fence have been designed and their effects on the sediment transport dynamics studied since many years. However, the search for the optimal array of fences has remained largely an empirical task. In order to achieve maximal soil protection using the minimal amount of fence material, a quantitative understanding of the flow profile over the relief encompassing the area to be protected including all employed fences is required. Here we use Computational Fluid Dynamics to calculate the average turbulent airflow through an array of fences as a function of the porosity, spacing and height of the fences. Specifically, we investigate the factors controlling the fraction of soil area over which the basal average wind shear velocity drops below the threshold for sand transport when the fences are applied. We introduce a cost function, given by the amount of material necessary to construct the fences. We find that, for typical sand-moving wind velocities, the optimal fence height (which minimizes this cost function) is around 50 cm, while using fences of height around 1.25 m leads to maximal cost.
12. Hepatocurative potential of Vitex doniana root bark, stem bark and leaves extracts against CCl4-induced liver damage in rats
Institute of Scientific and Technical Information of China (English)
2014-01-01
Objective: To evaluate the hepatocurative effects of aqueous root bark, stem bark and leaves ofVitex doniana in carbon tetrachloride (CCl albino rats.Methods:4) induced liver damage and non induced liver damage were assigned into liver damage and non liver damage groups of 6 rats in a group. The animals in the CCl4 induced liver damage groups, were induced by intraperitoneal injection with a single dose of CCl4 (1 mL/kg body weight) as a 1:1(v/v) solution in olive oil and were fasted for 36 h before the subsequent treatment with aqueous root bark, stem bark and leaves extracts of Vitex doniana and vitamin E as standard drug (100 mg/kg body weight per day) for 21 d, while the animals in the non induced groups were only treated with the daily oral administration of these extracts at the same dose. The administration of CCl4 was done once a week for a period of 3 weeks.Results:There was significant (P<0.05) increase in concentration of all liver marker enzymes, A total of 60 albino rats (36 induced liver damage and 24 non induced liver damage) alanine aminotransferase, aspartate aminotransferase and alkaline aminotransferase (ALT, AST and ALP) and significant (P<0.05) decrease in albumin in the CCl4 induced liver damage control when compared to the normal control. The extracts caused a significant (P<0.05) reduction in the serum activities of liver marker enzymes (ALT, AST and ALP) and a significant (P<0.05) increase in albumin of all the induced treated groups. Only stem bark extract and vitamin E significantly (P<0.05) increased total protein. All the extracts significantly (P<0.05) lowered serum creatinine whereas only root bark extract significantly (P<0.05) lowered serum level of urea in the rats with CCl4 induced liver damage.Conclusion:Hepatocurative study shows that all the plant parts (root bark, stem bark and leaves) possess significant hepatocurative properties among other therapeutic values justifying their use in folklore medicine.
13. Morphology of Betula pendula var. carelica bark at the pre-reproductive stage
Directory of Open Access Journals (Sweden)
2014-04-01
Full Text Available Changes in bark morphology at the pre-reproductive stage of Karelian birch are for the first time considered in connection with the type of trunk surface. The bark surface in Karelian birch changes with age from smooth to fissured. At the pre-reproductive stage Karelian birch has smooth bark with different types of exfoliation of the phellem surface layers, and tubercular specimens feature locally fissured bark on muffs at the very onset of their formation, as well as early rhytidome formation. Morphology of the bark tissues complex is a reflection of direction and intensity of the internal processes of the plant.
14. Predictive hydrogeochemical modelling of bauxite residue sand in field conditions.
Science.gov (United States)
Wissmeier, Laurin; Barry, David A; Phillips, Ian R
2011-07-15
The suitability of residue sand (the coarse fraction remaining from Bayer's process of bauxite refining) for constructing the surface cover of closed bauxite residue storage areas was investigated. Specifically, its properties as a medium for plant growth are of interest to ensure residue sand can support a sustainable ecosystem following site closure. The geochemical evolution of the residue sand under field conditions, its plant nutrient status and soil moisture retention were studied by integrated modelling of geochemical and hydrological processes. For the parameterization of mineral reactions, amounts and reaction kinetics of the mineral phases natron, calcite, tricalcium aluminate, sodalite, muscovite and analcime were derived from measured acid neutralization curves. The effective exchange capacity for ion adsorption was measured using three independent exchange methods. The geochemical model, which accounts for mineral reactions, cation exchange and activity corrected solution speciation, was formulated in the geochemical modelling framework PHREEQC, and partially validated in a saturated-flow column experiment. For the integration of variably saturated flow with multi-component solute transport in heterogeneous 2D domains, a coupling of PHREEQC with the multi-purpose finite-element solver COMSOL was established. The integrated hydrogeochemical model was applied to predict water availability and quality in a vertical flow lysimeter and a cover design for a storage facility using measured time series of rainfall and evaporation from southwest Western Australia. In both scenarios the sand was fertigated and gypsum-amended. Results show poor long-term retention of fertilizer ions and buffering of the pH around 10 for more than 5 y of leaching. It was concluded that fertigation, gypsum amendment and rainfall leaching alone were insufficient to render the geochemical conditions of residue sand suitable for optimal plant growth within the given timeframe. The
15. Sands at Gusev Crater, Mars
Science.gov (United States)
Cabrol, Nathalie A.; Herkenhoff, Kenneth E.; Knoll, Andrew H.; Farmer, Jack D.; Arvidson, Raymond E.; Grin, E.A.; Li, Ron; Fenton, Lori; Cohen, B.; Bell, J.F.; Yingst, R. Aileen
2014-01-01
Processes, environments, and the energy associated with the transport and deposition of sand at Gusev Crater are characterized at the microscopic scale through the comparison of statistical moments for particle size and shape distributions. Bivariate and factor analyses define distinct textural groups at 51 sites along the traverse completed by the Spirit rover as it crossed the plains and went into the Columbia Hills. Fine-to-medium sand is ubiquitous in ripples and wind drifts. Most distributions show excess fine material, consistent with a predominance of wind erosion over the last 3.8 billion years. Negative skewness at West Valley is explained by the removal of fine sand during active erosion, or alternatively, by excess accumulation of coarse sand from a local source. The coarse to very coarse sand particles of ripple armors in the basaltic plains have a unique combination of size and shape. Their distribution display significant changes in their statistical moments within the ~400 m that separate the Columbia Memorial Station from Bonneville Crater. Results are consistent with aeolian and/or impact deposition, while the elongated and rounded shape of the grains forming the ripples, as well as their direction of origin, could point to Ma'adim Vallis as a possible source. For smaller particles on the traverse, our findings confirm that aeolian processes have dominated over impact and other processes to produce sands with the observed size and shape patterns across a spectrum of geologic (e.g., ripples and plains soils) and aerographic settings (e.g., wind shadows).
16. Recovery of copper through decontamination of synthetic solutions using modified barks
Science.gov (United States)
Gaballah, I.; Goy, D.; Allain, E.; Kilbertus, G.; Thauront, J.
1997-02-01
Decontamination of synthetic acetate, chloride, nitrate, and sulfate solutions containing 10, 100, 1,000, 10,000, and 50,000 ppm of copper using chemically treated barks has been studied. Metal percentage removal from solutions depends on the pH, the initial concentration, and, to some extent, the anion. It varies from 40 through 99 pct of the initial metallic ion’s content in the solution. The average retention capacity of the treated bark is about 43 mg of Cu/g of dry modified bark (0.68 mmole/g of dry bark). Extraction of copper cations from the saturated modified bark was made possible with dilute acid. Regeneration of bark for reuse as an ion exchanger was possible. Bark loaded with copper was analyzed by scanning electron microscopy (SEM) and infrared (IR) spectroscopy. Copper was uniformly distributed in the bulk of the bark. No copper segregation was observed. It seems that copper was bound to the acidic (phenolic) sites of the bark. Anions were not detected on the copper-loaded bark with either SEM electron probe microanalysis or IR spectroscopy. Incineration of the bark loaded with copper resulted in ashes containing about 77 pct of copper oxides, while pyrolysis of the same sample led to ashes containing 10 pct of metallic copper and about 85 pct carbon.
17. Extraction of pectins with different degrees of esterification from mulberry branch bark.
Science.gov (United States)
Liu, Lin; Cao, Jing; Huang, Jian; Cai, Yurong; Yao, Juming
2010-05-01
Pectins were extracted from mulberry branch bark, a byproduct of the sericulture industry. A single-factor experiment was used to optimize the production conditions. Under optimal conditions, the galacturonic acid yields from bark with and without epidermis were 61.73 + or - 1.39% and 35.12 + or - 0.24%, respectively. The extracted pectins mainly consisted of galacturonic acid with a trace amount of neutral sugars, and the total galacturonic acid content in the pectins extracted from the bark without epidermis reached 85.46 + or - 2.76%. Pectins extracted from bark without epidermis had a higher degree of esterification (71.13 + or - 1.67%) than those extracted from bark with epidermis (24.27 + or - 2.89%). Pectin solution from bark without epidermis showed higher apparent viscosity, suggesting its higher gelation ability. Thus, the mulberry branch bark is a potential source of pectin with different degrees of esterification.
18. Enhanced sorption of polycyclic aromatic hydrocarbons from aqueous solution by modified pine bark.
Science.gov (United States)
Li, Yungui; Chen, Baoliang; Zhu, Lizhong
2010-10-01
To enhance removal efficiency of natural sorbent with polycyclic aromatic hydrocarbons (PAHs), single-solute and bi-solute sorption of phenanthrene and pyrene onto raw and modified pine bark were investigated. Pine bark was modified using Soxhlet extraction, saponification and acid hydrolysis, yielding six bark fractions with different chemical compositions. Raw pine bark exhibited high affinities with PAHs, and sorption was dominated by partitioning. The relatively nonlinear sorption isotherms of modified bark were attributed to the specific interaction between sorbate and aromatic core of sorbent. Comparison with lipid and suberin, lignin was the most powerful sorption medium, but which was almost completely suppressed by coexisting polysaccharide. After consuming polysaccharide by acid hydrolysis, sorption of pine bark fractions was notably increased (4-17 folds); and sorption of pyrene just decreased 16-34% with phenanthrene as a competitor. These observations suggest that pine bark is of great potential for PAHs removal and can be significantly promoted by acid hydrolysis for environmental application.
19. New Diarylheptanoid from the Barks of Alnus japonica Steudel
Institute of Scientific and Technical Information of China (English)
2005-01-01
A new diarylheptanoid glycoside, 1,7-bis-(3,4-dihydroxyphenyl)-5-hydroxyheptane-3-O-β-D-xylopyranoside (1), together with nine known diarylheptanoids (2-10) were isolated from the fresh bark of Alnus japonica which is a species of the genus Alnus species, growing throughout Korea.
20. Three new compounds from the barks of Morus nigra.
Science.gov (United States)
Wang, Lei; Cui, Xi-Qiang; Gong, Ting; Yan, Ren-Yi; Tan, Yong-Xia; Chen, Ruo-Yun
2008-01-01
Three new compounds including two flavonoids and a new 2-phenylbenzofuran, named morunigrols A-C (1-3), together with three known compounds albafuran A (4), albafuran B (5), and mulberrofuran L (6), have been isolated from the barks of Morus nigra. Their structures have been elucidated by spectroscopic methods.
1. Anthelmintic activity of root bark of Carissa carandas.
Science.gov (United States)
John, P P; Mazumder, Avijit; Mazumder, R; Bhatnagar, S P
2007-07-01
The anthelmintic activity of the Imethanolic extract of the root bark of Carissa carandas was evaluated on adult Indian earthworm (Pheretima posthuma) using albendazole as a reference standard. The extract caused paralysis followed by the death of worm at the tested dose level. The extract at the highest tested concentration has anthelmintic activity comparable with that of standard drug albendazole.
2. A new diterpenoid from the stem bark of Populus davidiana
Institute of Scientific and Technical Information of China (English)
Xin Feng Zhang; Xiang Li; Byung Sun Min; Ki Hwan Bae
2008-01-01
A new diterpenoid, named populusol A (1), was isolated from the methanolic extraction of the stem bark of Populus davidiana. The structure was elucidated on the basis of extensive 1D and 2D NMR as well as HRFAB-MS spectroscopic analysis.
3. A New Benzofuran Derivative from the Bark of Mulberry Tree
Institute of Scientific and Technical Information of China (English)
Sheng Jun DAI; Zhi Bo MA; Shuai LI; Ruo Yun CHEN; De Quan YU
2004-01-01
From the EtOH extract of the barks of Morus macroura Miq, a new benzofuran derivative, macrourin D 1, together with four known benzofuran derivatives, macrourin B 2, 2-(3, 5-dihydroxyphenyl)-5, 6-dihydroxybenzofuran 3, moracin M 4, and mulberroside C 5 were isolated, and their structures were determined on the basis of spectroscopic evidence and chemical correlation with known compounds.
4. In vitro evaluation of inhibitory effect of Phoenix dactylifera bark ...
African Journals Online (AJOL)
dactylifera bark extract on rat lipid peroxidation and blood hemolysis ... proteins, lipids, and DNA of the cell. Compared ... Free radicals increase the oxidation of unsaturated fatty acids ... food in central Asia and North Africa. ... brain were analyzed as follows: One gram of .... effect of sesame oil against lipid peroxidation and.
5. Further constituents from the bark of Tabebuia impetiginosa.
Science.gov (United States)
Warashina, Tsutomu; Nagatani, Yoshimi; Noro, Tadataka
2005-03-01
Further study on the constituents from the bark of Tabebuia impetiginosa (Mart. ex DC) Standley afforded twelve compounds, consisting of four iridoid glycosides, one phenylethanoid glycoside, five phenolic glycosides, and one lignan glycoside, along with seven known compounds. The structures of these compounds were determined based on the interpretation of their NMR and MS measurements and by chemical evidence.
6. Clerodane diterpenes from bark of Croton urucurana baillon
Energy Technology Data Exchange (ETDEWEB)
Pizzolatti, Moacir G.; Bortoluzzi, Adailton J.; Brighente, Ines M.C.; Zuchinalli, Analice; Carvalho, Francieli K., E-mail: [email protected] [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Departamento de Qumica; Candido, Ana C. S.; Peres, Marize T.L.P. [Universidade Federal do Mato Grosso do Sul (UFMS), Campo Grande, MS (Brazil). Departamento de Hidraulica e Transportes
2013-04-15
The new clerodane diterpene methyl 3-oxo-12-epibarbascoate was isolated from the stem barks of Croton urucurana together with the known diterpene methyl 12-epibarbascoate. The structures of these compounds were elucidated by spectroscopic techniques and comparison with the literature data. The obtainment of crystals allowed the crystallographic analysis of X-ray diffraction of diterpenes, thus confirming the proposed structures. (author)
Science.gov (United States)
Eun Woo Shin; K. G. Karthikeyan; Mandla A. Tshabalala
2007-01-01
In this study the capacity of sorbents prepared from juniper wood (JW) and bark (JB) to adsorb cadmium (Cd) from aqueous solutions at different pH values was compared. Adsorption behavior was characterized through adsorption kinetics, adsorption isotherms, and adsorption edge experiments. Results from kinetics and isotherm experiments showed that JB (76.3â91.6 lmol Cd...
8. Antimicrobial and phytochemical analysis of leaves and bark ...
African Journals Online (AJOL)
USER
2010-02-15
Feb 15, 2010 ... Half strength (10 g/ml) concentrations of the bark ethanol and methanol extracts .... to stand on the laboratory bench for 1 h to allow for proper diffusion of the extract into the ..... University of Lagos Press. pp. 53-64. Olajuyigbe ...
9. Anti-TB activity of Evodia elleryana bark extract
Science.gov (United States)
Barrows, Louis R.; Powan, Emma; Pond, Christopher D.; Matainaho, Teatulohi
2009-01-01
An ethyl acetate extract of bark from Evodia elleryana produced significant growth inhibition of Mycobacterium tuberculosis at concentrations only minimally inhibitory to human T cells. The crude extract yielded 95% inhibition of TB at 50 μg/ml. The crude extract yielded 29 % growth inhibition of human T-cells in culture at that concentration. PMID:17350179
10. Pyrigemmula, a novel hyphomycete genus on grapevine and tree bark
NARCIS (Netherlands)
Magyar, Donat; Shoemaker, R.A.; Bobvos, J.; Crous, P.W.; Groenewald, J.Z.
2011-01-01
The anamorphic taxon Pyrigemmula aurantiaca gen. et sp. nov. is described and illustrated from specimens that were collected from the inner bark of living woody hosts (Vitis vinifera, Pyrus communis, Mespilus germanica, Platanus hybrida, Elaeagnus angustifolia) and plant debris in Hungary. The fungu
11. Pyrigemmula, a novel hyphomycete genus on grapevine and tree bark
NARCIS (Netherlands)
Magyar, D.; Shoemaker, R.A.; Bobvos, J.; Crous, P.W.; Groenewald, J.Z.
2011-01-01
The anamorphic taxon Pyrigemmula aurantiaca gen. et sp. nov. is described and illustrated from specimens that were collected from the inner bark of living woody hosts (Vitis vinifera, Pyrus communis, Mespilus germanica, Platanus hybrida, Elaeagnus angustifolia) and plant debris in Hungary. The
12. Nitrogen Availability in Fresh and Aged Douglas Fir Bark
Science.gov (United States)
The objective of this study was to determine if there are growth differences in geranium (Pelargonium ×hortorum Bailey 'Maverick Red') produced in either fresh or aged Douglas fir [Pseudotsuga menziesii (Mirbel) Franco] bark (DFB). A second objective was to document nitrogen immobilization and deco...
13. Behavioural Effects of Methanol Stem Bark Extract of Boswellia ...
African Journals Online (AJOL)
Dr Olaleye
The results suggest central nervous system depressant action of stem bark extract of. Boswellia .... decreased locomotive activity and respiratory depression. ..... Biotech. 3(5), 284-288. Odeghe O.B., Onoriose D.A., Uwakwe A.A., Monago C.C..
14. Alkaloids from the root barks of Goniothalamus cheliensis
Institute of Scientific and Technical Information of China (English)
Miao Miao Jiang; Xue Zhang; Yi Dai; Hao Gao; Hong Wei Liu; Nai Li Wang; Wen Cai Ye; Xin Sheng Yao
2008-01-01
(3S)-2-Oxo-5,12-dimethoxy-3-hydroxy-3-methylbenz[f]indoline (1), a new benzoxindole alkaloid, along with two known alkaloids, was isolated from the root barks of Goniothalamus cheliensis Hu. The structure was elucidated by spectroscopic evidences, and the absolute configuration was determined by CD spectrum.
15. Ellagitannins and complex tannins from Quercus petraea bark.
Science.gov (United States)
König, M; Scholz, E; Hartmann, R; Lehmann, W; Rimpler, H
1994-10-01
The ellagitannins 2,3-(S)-hexahydroxydiphenoyl-glucose, pedunculagin, vescalagin, and castalagin; the flavanoellagitannins acutissimin A, acutissimin B, eugenigrandin A, guajavin B, and stenophyllanin C; and the procyanidinoellagitannin mongolicanin have been isolated from the bark of Quercus petraea. The ellagitannin fraction had a weak antisecretory effect.
16. Bark ecology of twigs vs. main stems: functional traits across eighty-five species of angiosperms.
Science.gov (United States)
Rosell, Julieta A; Castorena, Matiss; Laws, Claire A; Westoby, Mark
2015-08-01
Although produced by meristems that are continuous along the stem length, marked differences in bark morphology and in microenvironment would suggest that main stem and twig bark might differ ecologically. Here, we examined: (1) how closely associated main stem and twig bark traits were, (2) how these associations varied across sites, and (3) used these associations to infer functional and ecological differences between twig and main stem bark. We measured density, water content, photosynthesis presence/absence, total, outer, inner, and relative thicknesses of main stem and twig bark from 85 species of angiosperms from six sites of contrasting precipitation, temperature, and fire regimes. Density and water content did not differ between main stems and twigs across species and sites. Species with thicker twig bark had disproportionately thicker main stem bark in most sites, but the slope and degree of association varied. Disproportionately thicker main stem bark for a given twig bark thickness in most fire-prone sites suggested stem protection near the ground. The savanna had the opposite trend, suggesting that selection also favors twig protection in these fire-prone habitats. A weak main stem-twig bark thickness association was observed in non fire-prone sites. The near-ubiquity of photosynthesis in twigs highlighted its likely ecological importance; variation in this activity was predicted by outer bark thickness in main stems. It seems that the ecology of twig bark can be generalized to main stem bark, but not for functions depending on the amount of bark, such as protection, storage, or photosynthesis.
17. DPTM simulation of aeolian sand ripple
Institute of Scientific and Technical Information of China (English)
2008-01-01
Aeolian sand ripple and its time evolution are simulated by the discrete particle tracing method (DPTM) presented in this paper. The difference between this method and the current methods is that the former can consider the three main factors relevant to the formation of natural aeolian sand ripples,which are the wind-blown sand flux above the sand bed formed by lots of sand particles with different di-ameters,the particle-bed collision and after it the rebound and ejection of sand particles in the sand bed,the saltation of high-speed sand particles and the creep of low-speed sand particles,respectively. The simulated aeolian sand ripple is close to the natural sand ripple not only in basic shape and characteristic,particle size segregation and stratigraphy,but also in formation stages. In addition,three important speeds can be obtained by this method,which are the propagation speed of the saturated aeolian sand ripple and the critical frictional wind speeds of emergence and disappearance of sand ripple.
18. DPTM simulation of aeolian sand ripple
Institute of Scientific and Technical Information of China (English)
ZHENG XiaoJing; BO TianLi; XIE Li
2008-01-01
Aeolian sand ripple and its time evolution are simulated by the discrete particle tracing method (DPTM) presented in this paper.The difference between this method and the current methods is that the former can consider the three main factors relevant to the formation of natural aeolian sand ripples, which are the wind-blown sand flux above the sand bed formed by lots of sand particles with different di-ameters, the particle-bed collision and after it the rebound and ejection of sand particles in the sand bed, the saltation of high-speed sand particles and the creep of low-speed sand particles, respectively.The simulated aeolian sand ripple is close to the natural sand ripple not only in basic shape and characteristic, particle size segregation and stratigraphy, but also in formation stages.In addition, three important speeds can be obtained by this method, which are the propagation speed of the saturated aeolian sand ripple and the critical frictional wind speeds of emergence and disappearance of sand ripple.
19. Dry reusing and wet reclaiming of used sodium silicate sand
Institute of Scientific and Technical Information of China (English)
2005-01-01
Based on the characteristics of used sodium silicate sand and the different use requirements for recycled sand, "dry reusing and wet reclaiming of used sodium silicate sand" is considered as the most suitable technique for the used sand. When the recycled sand is used as support sand, the used sand is only reused by dry process including breaking, screening, dust-removal, etc., and it is not necessary that the used sand is reclaimed with strongly rubbing and scraping method, but when the recycled sand is used as facing sand (or single sand), the used sand must be reclaimed by wet method for higher removal rate of the residual binders. The characteristics and the properties of the dry reused sand are compared with the wet reclaimed sand after combining the different use requirements of support sand and facing sand (or single sand), and above the most adaptive scheme has also been validated.
20. Successful strategies for water management in the oil sands region
Energy Technology Data Exchange (ETDEWEB)
Smith, J.; Baker, M. [Shell Canada Ltd., Calgary, AB (Canada). Oil Sands Division
2004-07-01
Since large quantities of water are required for oil sand mining, water withdrawals from rivers located near oil sand mining facilities may increase. This paper referred to the water-based extraction process at the Muskeg River Mine operated by Albian Sands Energy. Although water is recycled and reused as much as possible, drought conditions in Alberta have raised concerns about the potential increased rates of water withdrawal during seasonal low flow periods. Measures have been taken to manage river withdrawals and ensure sustainability of aquatic resources. A committee has been established under the Cumulative Environmental Management Association (CEMA) to develop a management system for the Athabasca River. The committee includes stakeholders from federal and provincial governments, First Nations, non-government groups and industry. This paper describes the challenges facing oil sands developers in the region with particular emphasis on the role that the newly developed management system called 'Instream Flow Needs', will have on the cumulative water withdrawal from the Athabasca River. 9 figs.
1. Erosion/corrosion testing of materials for oil sands applications
Energy Technology Data Exchange (ETDEWEB)
Fisher, G.; Wolodko, J.; Alemaskin, K.; Been, J.; Danysh, M. [Alberta Research Council, Edmonton, AB (Canada)
2008-07-01
Erosion and corrosion are common wear mechanisms for components used in oil sands processing facilities. This paper described a slurry jet test apparatus designed to evaluate and assess materials for oil sands service conditions. The jet testing apparatus was designed to mimic the wet erosion phenomena typically found in oil sands applications. Wear- and corrosion-resistant materials tested by the apparatus included carbon steel, tungsten carbide metal matrix composite (WC-MMC) overlays, and a range of polymer and rubber liner materials. Polymeric materials included hydrogenated nitrile rubber (HNBR); polyurethane elastomer; and high density polyethylene (HDPE). Material losses were determined by measuring the mass of the samples before and after testing. Normalized rates of abrasion were calculated by dividing total mass lost in the specimens by the total mass of sand impinged on the sample surface. Samples were also visually assessed and analyzed using scanning electron microscopy (SEM) in order to determine failure modes. Tests were conducted for a 2-hour period at an impingement angle of 90 degrees. Results of the study showed that the average abrasion rates of the polymeric samples are lower than rates seen with the carbon steel and overlay materials. Future work on the apparatus will include testing the materials under varying slurry jet parameters. 15 refs., 5 tabs., 10 figs.
Data.gov (United States)
Department of Veterans Affairs — The facilities web service provides VA facility information. The VA facilities locator is a feature that is available across the enterprise, on any webpage, for the...
3. Sand and Water Table Play
Science.gov (United States)
Wallace, Ann H.; White, Mary J.; Stone, Ryan
2010-01-01
The authors observed preschoolers engaged at the sand and water table to determine if math could be found within their play. Wanting to understand how children interact with provided materials and what kinds of math ideas they explore during these interactions, the authors offer practical examples of how such play can promote mathematical…
4. Sand and Water Table Play
Science.gov (United States)
Wallace, Ann H.; White, Mary J.; Stone, Ryan
2010-01-01
The authors observed preschoolers engaged at the sand and water table to determine if math could be found within their play. Wanting to understand how children interact with provided materials and what kinds of math ideas they explore during these interactions, the authors offer practical examples of how such play can promote mathematical…
5. Impact on sand and water
NARCIS (Netherlands)
Bergmann, R.P.H.M.
2007-01-01
In this thesis we investigate the impact of a body on sand and water. When a body impacts a free surface in the inertial regime the series of events is the following: On impact material is blown away in all directions and an impact cavity forms. Due to the hydrostatic pressure from the sides the cav
6. Silo model tests with sand
DEFF Research Database (Denmark)
Munch-Andersen, Jørgen
Tests have been carried out in a large silo model with Leighton Buzzard Sand. Normal pressures and shear stresses have been measured during tests carried out with inlet and outlet geometry. The filling method is a very important parameter for the strength of the mass and thereby the pressures...
7. Biochemistry Facility
Data.gov (United States)
Federal Laboratory Consortium — The Biochemistry Facility provides expert services and consultation in biochemical enzyme assays and protein purification. The facility currently features 1) Liquid...
8. UK silica sand resources for fracking
OpenAIRE
Mitchell, Clive
2013-01-01
UK silica sand resources for fracking Clive Mitchell, Industrial Minerals Specialist, British Geological Survey, Keyworth, Nottingham, NG12 5GG Email: Silica sand is high purity quartz sand that is mainly used for glass production, as foundry sand, in horticulture, leisure and other industrial uses. One specialist use is as a ‘proppant’ to enhance oil and gas recovery. This presentation will focus on this application, particularly for shale gas recovery where it is mo...
9. Combustion characteristics of Ponderosa Pine bark. Technical progress report No. 7, September 16, 1977--September 15, 1978
Energy Technology Data Exchange (ETDEWEB)
Junge, D.C.
1978-12-01
Significant quantities of wood residue fuels are presently being used in industrial steam generating facilities. Recent studies indicate that substantial additional quantities of wood residue fuels are available for energy generation in the form of steam and/or electricity. A limited data base on the combustion characteristics of wood residue fuels has resulted in the installation and operation of inefficient combustion systems for these fuels. This investigation of the combustion characteristics of wood residue fuels was undertaken to provide a data base which could be used to optimize the combustion of such fuels. Optimization of the combustion process in industrial boilers serves to improve combustion efficiency and to reduce air pollutant emissions generated in the combustion process. Data are presented on the combustion characteristics of Ponderosa Pine bark. The data were obtained in a pilot scale combustion test facility at Oregon State University.
10. Treating tar sands formations with karsted zones
Energy Technology Data Exchange (ETDEWEB)
Vinegar, Harold J. (Bellaire, TX); Karanikas, John Michael (Houston, TX)
2010-03-09
Methods for treating a tar sands formation are described herein. The tar sands formation may have one or more karsted zones. Methods may include providing heat from one or more heaters to one or more karsted zones of the tar sands formation to mobilize fluids in the formation. At least some of the mobilized fluids may be produced from the formation.
11. The value of Leucaena leucocephala bark in leucaena-grass hay diets for Thai goats.
Science.gov (United States)
Palmer, Brian; Jones, Raymond J; Poathong, Somsak; Chobtang, Jeerasak
2010-12-01
The study assessed the value of Leucaena leucocephala bark in leucaena-grass hay diets fed to Thai goats. Thai goats in metabolism pens were fed diets containing leucaena leaf (55%) + pangola grass hay (hay, 45%); leucaena leaf (48%) + leucaena bark (9%) + hay (43%); leucaena bark (57%) + hay (43%); and hay only. Feed percentages are expressed on a dry weight basis. The digestibilities of dry matter (DM) and crude protein (CP) were measured for the four diets. Leucaena bark had lower CP concentration than the leaf (11.7 vs. 25.9), and the leucaena bark + hay diet had lower DM and CP digestibility than the other diets. The calculated bark digestibilities of DM and CP of 44.1% and 38.2%, respectively, were much lower than the values for the leucaena leaf of 62.9% and 89.1%, respectively. The lower than expected CP digestibility was attributed to higher tannin levels in the bark compared to the leaves. Despite this, the bark was well accepted by the goats and was often preferred to the hay. Stripping of the bark by goats also results in stems that dry quicker and have higher calorific value as fuel. However, if leucaena branches are fed as a sole diet, the goats may consume up to 30% of bark on a DM basis and this would reduce nutritive value and animal productivity.
12. Acidity and conductivity of Pinus massoniana bark as indicators to atmospheric acid deposition in Guangdong, China
Institute of Scientific and Technical Information of China (English)
KUANG Yuan-wen; ZHOU Guo-yi; WEN Da-zhi; LIU Shi-zhong
2006-01-01
Barks of Pinus masoniana collected from two polluted sites, Qujiang and Xiqiaoshan, and from the relatively clean site Dinghushan were used to evaluate the pollution indication by the determination of their acidity and conductivity. The acidity of the inner and outer barks from the polluted sites was significantly higher than those from the clean site, suggesting that the acidity of the bark occurred in concurrent with the air pollution. The significant lower pH values of the outer bark than the inner bark collected from all sites indicated that the outer bark was more sensitive than the inner bark in response to acid pollution, implying that the outer bark is more preferable when used as indication of atmospheric acid pollution. The conductivities of the inner barks differed significantly among the three sites, with higher values at the clean site. However, the significant differences were not observed among these sites.Furthermore, the pH values for the inner and outer barks were not correlated with the conductivity, which did not coincide with some other studies.
13. Sand Waves. Report 1. Sand Wave Shoaling in Navigation Channels
Science.gov (United States)
1992-09-01
heights range from 0.8 m in the Minas Basin, Bay of Fundy (Dalrymple 1984) to 6.0 m in the Bahia Blanca Estuary, Argentina (Aliotta and Perillo 1987...26 PART IV: SITE-SPECIFIC SAND WAVE SHOALING PROBLEMS .. ........ 30 Columbia River Navigation Channel ........ ............... .. 30 Panama ...problem location discussed in this report is at St. Andrew Bay near Panama City, Florida. A relatively short section of the jettied inlet channel requires
14. Opportunities in oil sands production bi-products
Energy Technology Data Exchange (ETDEWEB)
2006-07-01
This presentation investigated potential by-products from oil sands production and upgrading facilities, and examined the extent to which carbon dioxide (CO{sub 2}) enhanced oil recovery (EOR) projects can absorb greenhouse gas (GHG) emissions from oil sands developments. Oil sands production by-products included bitumen and petroleum coke; heat; hydrocarbon off-gases; hydrogen; syngas; sulfur; metals; and CO{sub 2} sources from combustion processes and hydrogen production. CO{sub 2} concentrations from flue gases are typically less than 17 per cent, and contain contaminants such as nitrogen, particulates, nitrogen oxide (NO{sub x}) and sulphur dioxide (SO{sub x}). CO{sub 2} concentrations derived from hydrogen production have a high purity and contain water vapour, unreacted hydrocarbons, hydrogen sulphide (H{sub 2}S) and volatile metals. Existing carbon capture technologies are currently not capable of processing large volumes of CO{sub 2}. However, small volumes of CO{sub 2} are used in the manufacturing of carbonated beverages. Larger volumes of CO{sub 2} are used in EOR and coalbed methane (CBM) recovery as well as in CO{sub 2} sequestration. Carbon capture technologies include amine scrubbers, selexol and rectisol gasification processes, and Benfield Catacarb processes. The market price for CO{sub 2} in EOR and gas recovery is approximately $35 per tonne. However, combustion processes typically cost$103 per tonne. CO{sub 2} sources and sinks were also identified. It is estimated that total CO{sub 2} sequestration using EOR will equal 200 mega tonnes by 2030. Apart from gasification processes, all CO{sub 2} sources are uneconomic using current technology. The oil sands industry is in need of a policy framework and support for infrastructure investments for CO{sub 2} pipelines and sequestration facilities. tabs., figs.
15. METHOD OF PROCESSING MONAZITE SAND
Science.gov (United States)
Welt, M.A.; Smutz, M.
1958-08-26
A process is described for recovering thorium, uranium, and rare earth values from monazite sand. The monazite sand is first digested with sulfuric acid and the resulting "monazite sulfate" solution is adjusted to a pH of between 0.4 and 3.0, and oxalate anions are added causing precipitation of the thorium and the rare earths as the oxalates. The oxalate precipitate is separated from the uranium containing supernatant solution, and is dried and calcined to the oxides. The thorium and rare earth oxides are then dissolved in nitric acid and the solution is contacted with tribntyl phosphate whereby an organic extract phase containing the cerium and thorium values is obtained, together with an aqueous raffinate containing the other rare earth values. The organic phase is then separated from the aqueous raffinate and the cerium and thorium are back extracted with an aqueous medium.
16. Characterization of sand lenses embedded in tills
DEFF Research Database (Denmark)
Kessler, Timo Christian; Klint, K.E.S.; Nilsson, B.
2012-01-01
of the various types of sand lenses is discussed, primarily in relation to the depositional and glaciotectonic processes they underwent. Detailed characterization of sand lenses facilitates such interpretations. Finally, the observations are linked to a more general overview of the distribution of sand lenses......Tills dominate large parts of the superficial sediments on the Northern hemisphere. These glacial diamictons are extremely heterogeneous and riddled with fractures and lenses of sand or gravel. The frequency and geometry of sand lenses within tills are strongly linked to glaciodynamic processes...... occurring in various glacial environments. This study specifically focuses on the appearance and spatial distribution of sand lenses in tills. It introduces a methodology on how to measure and characterize sand lenses in the field with regard to size, shape and degree of deformation. A set of geometric...
17. A compact topology for sand automata
CERN Document Server
Dennunzio, Alberto; Masson, Benoît
2008-01-01
In this paper, we exhibit a strong relation between the sand automata configuration space and the cellular automata configuration space. This relation induces a compact topology for sand automata, and a new context in which sand automata are homeomorphic to cellular automata acting on a specific subshift. We show that the existing topological results for sand automata, including the Hedlund-like representation theorem, still hold. In this context, we give a characterization of the cellular automata which are sand automata, and study some dynamical behaviors such as equicontinuity. Furthermore, we deal with the nilpotency. We show that the classical definition is not meaningful for sand automata. Then, we introduce a suitable new notion of nilpotency for sand automata. Finally, we prove that this simple dynamical behavior is undecidable.
18. Rheological Characterization of Green Sand Flow
DEFF Research Database (Denmark)
Jabbaribehnam, Mirmasoud; Spangenberg, Jon; Hovad, Emil
2016-01-01
The main aim of this paper is to characterize experimentally the flow behaviour of the green sand that is used for casting of sand moulds. After the sand casting process is performed, the sand moulds are used for metal castings. The rheological properties of the green sand is important to quantify...... module for characterizing granular materials. The new module enables viscosity measurements of the green sand as function of the shear rate at different flow rates, i.e. 0, 2, 4, 6, 8, 10, 12 and 15 L/min. The results show generally that the viscosity decreases with both the shear- and flow rate....... In addition, the measurements show that the green sand flow follows a shear-thinning behaviour even after the full fluidization point....
19. Understanding Boswellia papyrifera tree secondary metabolites through bark spectral analysis
Science.gov (United States)
Girma, Atkilt; Skidmore, Andrew K.; de Bie, C. A. J. M.; Bongers, Frans
2015-07-01
Decision makers are concerned whether to tap or rest Boswellia Papyrifera trees. Tapping for the production of frankincense is known to deplete carbon reserves from the tree leading to production of less viable seeds, tree carbon starvation and ultimately tree mortality. Decision makers use traditional experience without considering the amount of metabolites stored or depleted from the stem-bark of the tree. This research was designed to come up with a non-destructive B. papyrifera tree metabolite estimation technique relevant for management using spectroscopy. The concentration of biochemicals (metabolites) found in the tree bark was estimated through spectral analysis. Initially, a random sample of 33 trees was selected, the spectra of bark measured with an Analytical Spectral Device (ASD) spectrometer. Bark samples were air dried and ground. Then, 10 g of sample was soaked in Petroleum ether to extract crude metabolites. Further chemical analysis was conducted to quantify and isolate pure metabolite compounds such as incensole acetate and boswellic acid. The crude metabolites, which relate to frankincense produce, were compared to plant properties (such as diameter and crown area) and reflectance spectra of the bark. Moreover, the extract was compared to the ASD spectra using partial least square regression technique (PLSR) and continuum removed spectral analysis. The continuum removed spectral analysis were performed, on two wavelength regions (1275-1663 and 1836-2217) identified through PLSR, using absorption features such as band depth, area, position, asymmetry and the width to characterize and find relationship with the bark extracts. The results show that tree properties such as diameter at breast height (DBH) and the crown area of untapped and healthy trees were strongly correlated to the amount of stored crude metabolites. In addition, the PLSR technique applied to the first derivative transformation of the reflectance spectrum was found to estimate the
20. A New Prenylated Xanthone from Root Barks of Cudrania cochinchinensis
Institute of Scientific and Technical Information of China (English)
LIU Zhi-ping; WEI Wan-xing; ZHOU Min; GAN Chun-fang; LIU Sheng
2013-01-01
Objective To study the chemical constituents from the root barks of Cudrania cochinchinensis.Methods The chemical constituents were isolated and purified by silica gel column chromatography.The structures of the compounds were identified on the basis of spectral data (MS,1H-NMR,13C-NMR,and 2D NMR) and by the comparison of spectroscopic data with the reported values in the literatures.Results A new xanthone,1,6,7-trihydroxy-4-(1,1-dimethylallyl)-3-methoxyxanthone (1) and a known prenylated xanthone 1,5,6-trihydroxy-4-(1,l-dimethylallyl)-3-methoxyxanthone (isocudraniaxanthone B,2) were isolated from the root barks of C.cochinchinensis.Conclusion Compound 1 is a new prenylated xanthone.Isomers 1 and 2 are obtained from this plantfor the first time.
1. Economics of fuel alternatives - oil, coal and bark boilers
Energy Technology Data Exchange (ETDEWEB)
Knight, W.E.; Jansen, B.M.; May, J.C.
1984-07-01
A method for comparing the relative economics of burning oil, bark or wastewood, and coal to generate steam is illustrated through several case plans. It was assumed that a 150,000-lb/h (68 ton/h) boiler will generate 600-psig (4134-kPa), 700 degrees F (371 degrees C) steam, that it will be added to an existing steam generating plant, and that it will be connected to the existing main steam header and to the boiler feedwater discharge header. The scope of new construction is therefore limited to the following equipment and their related structures: boiler, fuel handling, combustion controls, burner, safety system, draft fans, particulate collection, ash handling, stack, foundations. Plans involving bark, wastewood, and coal fuels are based on the assumptions that the plant has
2. Yucca schidigera bark: phenolic constituents and antioxidant activity.
Science.gov (United States)
Piacente, Sonia; Montoro, Paola; Oleszek, Wieslaw; Pizza, Cosimo
2004-05-01
Two new phenolic constituents with unusual spirostructures, named yuccaols D (1) and E (2), were isolated from the MeOH extract of Yucca schidigera bark. Their structures were established by spectroscopic (ESIMS and NMR) analysis. The new yuccaols D and E, along with resveratrol (3), trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene (4), yuccaols A-C (5-7), yuccaone A (8), larixinol (9), the MeOH extract of Yucca schidigera bark, and the phenolic portion of this extract, were assayed for antioxidant activity by measuring the free radical scavenging effects using two different assays, namely, the Trolox Equivalent Antioxidant Capacity (TEAC) assay and the coupled oxidation of beta-carotene and linoleic acid (autoxidation assay). The significant activities exhibited by the phenolic fraction and its constituents in both tests show the potential use of Y. schidigera as a source of antioxidant principles.
3. Silo model tests with sand
DEFF Research Database (Denmark)
Munch-Andersen, Jørgen
Tests have been carried out in a large silo model with Leighton Buzzard Sand. Normal pressures and shear stresses have been measured during tests carried out with inlet and outlet geometry. The filling method is a very important parameter for the strength of the mass and thereby the pressures...... as well as the flow pattern during discharge of the silo. During discharge a mixed flow pattern has been identified...
4. Formation of Craters in Sand
Directory of Open Access Journals (Sweden)
Vanissra Boonyaleepun
2007-06-01
Full Text Available The diameter of craters formed by spheres of varying mass dropped into sand at low speed was studied. The relationship between the diameter of the crater formed and the kinetic energy of the projectile at impact was found to be of the same general form as that for planetary meteor craters. The relationship is shown to be a power law with exponent 0.17.
5. Formation of Craters in Sand
Directory of Open Access Journals (Sweden)
Vanissra Boonyaleepun
2007-06-01
Full Text Available The diameter of craters formed by spheres of varying mass dropped into sand at low speed was studied. The relationship between the diameter of the crater formed and the kinetic energy of the projectile at impact was found to be of the same general form as that for planetary meteor craters. The relationship is shown to be a power law with exponent 0.17
6. Thermal Properties of oil sand
Science.gov (United States)
LEE, Y.; Lee, H.; Kwon, Y.; Kim, J.
2013-12-01
Thermal recovery methods such as Cyclic Steam Injection or Steam Assisted Gravity Drainage (SAGD) are the effective methods for producing heavy oil or bitumen. In any thermal recovery methods, thermal properties (e.g., thermal conductivity, thermal diffusivity, and volumetric heat capacity) are closely related to the formation and expansion of steam chamber within a reservoir, which is key factors to control efficiency of thermal recovery. However, thermal properties of heavy oil or bitumen have not been well-studied despite their importance in thermal recovery methods. We measured thermal conductivity, thermal diffusivity, and volumetric heat capacity of 43 oil sand samples from Athabasca, Canada, using a transient thermal property measurement instrument. Thermal conductivity of 43 oil sand samples varies from 0.74 W/mK to 1.57 W/mK with the mean thermal conductivity of 1.09 W/mK. The mean thermal diffusivity is 5.7×10-7 m2/s with the minimum value of 4.2×10-7 m2/s and the maximum value of 8.0×10-7 m2/s. Volumetric heat capacity varies from 1.5×106 J/m3K to 2.11×106 J/m3K with the mean volumetric heat capacity of 1.91×106 J/m3K. In addition, physical and chemical properties (e.g., bitumen content, electric resistivity, porosity, gamma ray and so on) of oil sand samples have been measured by geophysical logging and in the laboratory. We are now proceeding to investigate the relationship between thermal properties and physical/chemical properties of oil sand.
7. THE MICROBIOLOGICAL AND SANITARY STATE OF SAND IN THE MUNICIPAL BATHING BEACH IN SZCZECIN
Directory of Open Access Journals (Sweden)
Kinga Zatoń
2015-11-01
Full Text Available Artificial beaches, i.e. places in the public sphere, are usually intended for recreation, located at water reservoirs, rivers, and their surface is naturally occurring or applied sand. The urban bathing beach located in Szczecin by the Deep lake has sand purchased and distributed on the beach by the Municipal Services Office in Szczecin (a few hundred ton. The beach is divided into sectors, a volleyball court is in one part, in the next section catering and sanitary facilities are located, and the remaining area is a place intended for sunbathing and playing games. The aim of the experiment was to assess the effects of different ways of using the beach on changes of microbiological properties of the sand. The tests were taken from the beach sand in May 2013 (first term examinations, and in September, after several months of use (the second term of examinations. The sand was collected near catering and sanitary sector (the first object and from the area of the volleyball court (the second object, as well as the playground for children (the third object. The facilities were distanced from the shoreline of the lake by approx. 8 metres. The comparison included the number of heterotrophic bacteria, fungi and the detected presence of coliform bacteria, including Escherichia coli, bacteria of the genus Salmonella and eggs of intestinal parasites. In any of the objects, or the periods of time, eggs of intestinal parasites and bacteria of the genus Salmonella were detected. The presence of coliform bacteria including E. coli was found in the sand collected from a catering-sanitary zone, there was also the biggest number of bacteria and fungi. The number of heterotrophic bacteria and fungi was similar in samples of sand taken from the volleyball court and from the playground, in this sand there was no bacteria belonging to the E. coli species, although in several samples from the playground other bacteria belonging to the coliform genus were detected. To
8. PHYTOCHEMICAL INVESTIGATION OF THE STEM BARK OF MORINGA OLEIFERA LAM.
Directory of Open Access Journals (Sweden)
Khan Maria
2011-05-01
Full Text Available Phytochemical investigation of the stem bark of Moringa oleifera Lam. (Moringaceae furnished two new phytoconstituents identified as n-heptacosanyl n-octadec-9,12,15 trieneoate (moringyl linoleneate and n- docas- 4-en-11-one-1-yl n-decanoate (oleiferyl capriate along with the known compounds β-sitosterol, epilupeol, glyceropalmityl phosphate and glycerol-oleiostearyl phosphate. The structures of all the phytoconstituents have been elucidated on the basis of spectral data analyses and chemical reactions.
9. [Studies on chemical constituents from bark of Morus nigra].
Science.gov (United States)
Wang, Lei; Wang, Hong-Qing; Chen, Ruo-Yun
2007-12-01
To investigate the chemical constituents in the barks of Morus nigra. The nine compounds were isolated and purified by column chromatography over silica gel, LH -20 and preparative HPLC and their structures were identified by various spectroscopic methods. The nine compounds were isolated and identified as olcancolic acid , apigenin, cyclocommunol, morusin, cyclomorusin, kuwanon C, daucosterol, ursolic acid, 63-sitosterol. Olcancolic acid, apingenin, cyclocommunol, morusin, cyclomorusin, kuwanon C, daucosterol were firstly isolated from the M. nigra.
10. PHARMACOGNOSTIC STUDIES OF THE BARK OF PARKINSONIA ACULEATA
Directory of Open Access Journals (Sweden)
D.Saha,
2010-12-01
Full Text Available The bark of Parkinsonia aculeata (fam. Leguminosae was studied to fix the parameters for pharmacognostical standards. The results of organoleptic study offer a scientific basis for the use of P. aculeata which possess characters like brown colour, characteristic odour and slightly bitter taste. The fluorescence analysis under visible light & under UV light by treatment with different chemical reagents showed different colour changes. The presence of alkaloids, flavonoids, tannins, steroids, and reducing sugars was confirmed during preliminary phytochemical screening.
11. Bioactive constituents of the bark of Parkia biglobosa.
Science.gov (United States)
Tringali, C; Spatafora, C; Longo, O D
2000-04-01
In the frame of a systematic analysis of African plants used for the 'cure salée', from the bark of Parkia biglobosa, a long-chain ester of trans-ferulic acid (1) has been isolated together with an unseparable mixture of long-chain cis-ferulates (2a-e). In addition, lupeol, 4-O-methyl-epi-gallocatechin, epi-gallocatechin, epi-catechin 3-O-gallate, and epi-gallocatechin 3-O-gallate were isolated.
12. Soulamarin, a New Coumarin from Stem Bark of Calophyllum soulattri
Directory of Open Access Journals (Sweden)
Mawardi Rahmani
2011-11-01
Full Text Available The extracts of the stem bark of Calophyllum soulattri gave a new pyranocoumarin, soulamarin (1, together with five other xanthones caloxanthone B (2, caloxanthone C (3, macluraxanthone (4, trapezifolixanthone (5 and brasixanthone B (6 one common triterpene, friedelin (7, and the steroidal triterpene stigmasterol (8. The structures of these compounds were established based on spectral evidence (1D and 2D NMR.
13. Constituents from the bark resin of Schinus molle
Directory of Open Access Journals (Sweden)
Gonzalo Rodolfo Malca-García
Full Text Available ABSTRACT A total of five terpenes was isolated from the bark resin of Schinus molle L., Anacardiaceae, and their structures were determined by spectroscopic techniques. Among these compounds the sesquiterpene hydrocarbon terebinthene showed significant growth inhibitory activity against human colon carcinoma HCT-116 cells. Furthermore, terebinthene and pinicolic acid (5 also showed antibacterial activity against Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6633.
14. Three new compounds from the stem bark of Juglans mandshurica.
Science.gov (United States)
Lin, Hua; Zhang, Yu-Wei; Hua, Ying; Bao, Yong-Li; Wu, Yin; Sun, Lu-Guo; Yu, Chun-Lei; Huang, Yan-Xin; Wang, En-Bo; Jiang, Hong-Yu; Li, Yu-Xin
2014-01-01
Three new compounds, 3,6-dihydroxy-4,5-dimethoxy-1,8-naphalic anhydride (1), 3,4,5,6-tetrahydroxy-1,8-naphalic anhydride (2), and methyl (7E,9E)-6,11-dioxononadeca-7,9-dienoate (3), were isolated from the stem bark of Juglans mandshurica. Their structures were elucidated on the basis of spectroscopic evidence, including 1D and 2D NMR, HR-TOF-MS, and by comparison with the literature data.
15. Singular Fibers in Barking Families of Degenerations of Elliptic Curves
CERN Document Server
Okuda, Takayuki
2012-01-01
Takamura established a theory on splitting families of degenerations of complex curves. He introduced a powerful method for constructing a splitting family, called a barking family, in which there appear not only a singular fiber over the origin but also singular fibers over other points, called subordinate fibers. In this paper, for the case of degenerations of elliptic curves, we determine the types of these subordinate fibers.
16. New sucrose derivatives from the bark of Securidaca longipedunculata.
Science.gov (United States)
De Tommasi, N; Piacente, S; De Simone, F; Pizza, C
1993-01-01
Two new bitter principles were isolated from the bark of Securidaca longipedunculata (Polygalaceae) and identified as beta-D-(3,4-disinapoyl)fructofuranosyl-alpha-D-(6-sinapoyl)g lucopyranoside and beta-D-(3-sinapoyl)fructofuranosyl-alpha-D-(6-sinapoyl)gluco pyranoside. The structures were elucidated by a combination of 1H nmr (1D, 2D COSY, 2D HOHAHA), 13C-nmr, and fabms spectra.
17. Molluscicidal activity of Punica granatum bark and Canna indica root
Directory of Open Access Journals (Sweden)
Tripathi S.M.
2000-01-01
Full Text Available The molluscicidal activity of Punica granatum Linn. (Punicaceae and Canna indica Linn. (Cannaceae against the snail Lymnaea acuminata was studied. The molluscicidal activity of P. granatum bark and C. indica root was found to be both time and dose dependent. The toxicity of P. granatum bark was more pronounced than that of C. indica. The 24 h LC50 of the column-purified root of C. indica was 6.54 mg/l whereas that of the column-purified bark of P. granatum was 4.39 mg/l. The ethanol extract of P. granatum (24 h LC50: 22.42 mg/l was more effective than the ethanol extract of C. indica (24 h LC50: 55.65 mg/l in killing the test animals. P. granatum and C. indica may be used as potent molluscicides since the concentrations used to kill the snails were not toxic for the fish Colisa fasciatus, which shares the same habitat with the snail L. acuminata.
18. Phenolic Extracts from Acacia mangium Bark and Their Antioxidant Activities
Directory of Open Access Journals (Sweden)
Liangliang Zhang
2010-05-01
Full Text Available Phenolic compounds are present at very high concentrations in the bark of Acacia mangium. These compounds are known to have strong antioxidant activity and thus different beneficial effects on human health. Phenolic compounds in bark of A. mangium were extracted and their antioxidant activities were investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH free radical-scavenging and ferric-reducing antioxidant power (FRAP assays. A central composite design has been employed to optimize the experimental conditions for a high total phenolic content and antioxidant activity. The desirability function approach has been employed to simultaneously optimize the three responses: total phenols, antiradical activity and FRAP. An extraction time of 90 min, liquid-solid ratio of 5, and temperature of 50 °C was predicted for the optimum experimental conditions using the desirability function. A significant linear relationship between antioxidant potency, antiradical activity and the content of phenolic compounds of bark extracts was observed. The structures of condensed tannins isolated from A. mangium were characterized by MALDI-TOF MS analyses. Condensed tannin oligomers from A. mangium were shown to be heterogeneous mixtures consisting of procyanidin and prodelphinidin structural units with polymerization degrees up to 9.
19. Phenolic extracts from Acacia mangium bark and their antioxidant activities.
Science.gov (United States)
Zhang, Liangliang; Chen, Jiahong; Wang, Yongmei; Wu, Dongmei; Xu, Man
2010-05-14
Phenolic compounds are present at very high concentrations in the bark of Acacia mangium. These compounds are known to have strong antioxidant activity and thus different beneficial effects on human health. Phenolic compounds in bark of A. mangium were extracted and their antioxidant activities were investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging and ferric-reducing antioxidant power (FRAP) assays. A central composite design has been employed to optimize the experimental conditions for a high total phenolic content and antioxidant activity. The desirability function approach has been employed to simultaneously optimize the three responses: total phenols, antiradical activity and FRAP. An extraction time of 90 min, liquid-solid ratio of 5, and temperature of 50 degrees C was predicted for the optimum experimental conditions using the desirability function. A significant linear relationship between antioxidant potency, antiradical activity and the content of phenolic compounds of bark extracts was observed. The structures of condensed tannins isolated from A. mangium were characterized by MALDI-TOF MS analyses. Condensed tannin oligomers from A. mangium were shown to be heterogeneous mixtures consisting of procyanidin and prodelphinidin structural units with polymerization degrees up to 9.
20. Photosynthetic characteristics of olive tree (Olea europaea) bark.
Science.gov (United States)
Filippou, Manolis; Fasseas, Costas; Karabourniotis, George
2007-07-01
Functional and structural characteristics of corticular photosynthesis of sun-exposed bark of olive tree (Olea europaea L.) were examined. Stomata are only sporadically present during stem primary growth. Light transmission through the phellem was age dependent, decreasing rapidly in stems older than five years of age. Light transmission was also low in pubescent 1-year-old stems. Light transmission was about 50% higher in wet phellem than in dry phellem. Photosynthetic capacity on a unit area basis (measured with an oxygen disc electrode at 27 degrees C and about 5% CO(2) on chlorophyllous tissue discs isolated from the stem) was higher in 1-, 20- and 30-year-old stems compared with 2-10-year-old stems. Low chlorophyll a/b ratio and light compensation points were recorded in olive stems with low phellem light transmission, in accordance with the shade acclimation hypothesis. The intrinsic photochemical efficiency of photosystem II of all stems, especially young stems, was less than that of the leaves. Our results show that olive tree bark possesses an efficient photosynthetic mechanism that may significantly contribute not only to the reduction in concentrations of CO(2) in the inner bark, but also to whole-tree carbon balance.
1. Antibacterial Effect of Juglans Regia Bark against Oral Pathologic Bacteria
Directory of Open Access Journals (Sweden)
Faramarz Zakavi
2013-01-01
Full Text Available Background. In this study antimicrobial effect of ethanolic and aqueous extracts of Juglans regia bark in Iran was evaluated on four different oral bacteria, Streptococcus mutans, Streptococcus salivarius, Streptococcus sanguis, and Staphylococcus aureus. Methods. Aqueous and ethanol extracts of Juglans regia bark were prepared by using disk diffusion technique and Minimal Inhibitory Concentration (MIC methods. Tetracycline 30 μg and Erythromycin 15 μg were used as positive control and water as negative control in disk diffusion and MIC methods. Data were analyzed by ANOVA test. Results. The results showed that S. sanguis and S. mutans were the most sensitive and the most resistant bacteria against ethanolic and aqueous extracts, respectively. Ethanolic extract had significant antibacterial effect against all tested bacteria. Aqueous extract did not show antibacterial effect on S. mutans, in contrast to ethanolic extract. Aqueous extract had significantly antibacterial effect against Staphylococcus aureus, S. salivarius, and S. sanguis compared to control (P<0.0001, but it did not show effect on S. mutans when compared with Erythromycin. According to the obtained MIC values, ethanol extract of Juglans regia bark had the lowest rate. Conclusion. The results may provide the basis for using natural antimicrobial substance for oral hygiene prophylaxis purposes.
2. Coffee berry borer joins bark beetles in coffee klatch.
Directory of Open Access Journals (Sweden)
Juliana Jaramillo
Full Text Available Unanswered key questions in bark beetle-plant interactions concern host finding in species attacking angiosperms in tropical zones and whether management strategies based on chemical signaling used for their conifer-attacking temperate relatives may also be applied in the tropics. We hypothesized that there should be a common link in chemical signaling mediating host location by these Scolytids. Using laboratory behavioral assays and chemical analysis we demonstrate that the yellow-orange exocarp stage of coffee berries, which attracts the coffee berry borer, releases relatively high amounts of volatiles including conophthorin, chalcogran, frontalin and sulcatone that are typically associated with Scolytinae chemical ecology. The green stage of the berry produces a much less complex bouquet containing small amounts of conophthorin but no other compounds known as bark beetle semiochemicals. In behavioral assays, the coffee berry borer was attracted to the spiroacetals conophthorin and chalcogran, but avoided the monoterpenes verbenone and α-pinene, demonstrating that, as in their conifer-attacking relatives in temperate zones, the use of host and non-host volatiles is also critical in host finding by tropical species. We speculate that microorganisms formed a common basis for the establishment of crucial chemical signals comprising inter- and intraspecific communication systems in both temperate- and tropical-occurring bark beetles attacking gymnosperms and angiosperms.
3. Ion Beam Analyses Of Bark And Wood In Environmental Studies
Science.gov (United States)
Lill, J.-O.; Saarela, K.-E.; Harju, L.; Rajander, J.; Lindroos, A.; Heselius, S.-J.
2011-06-01
A large number of wood and bark samples have been analysed utilizing particle-induced X-ray emission (PIXE) and particle-induced gamma-ray emission (PIGE) techniques. Samples of common tree species like Scots Pine, Norway Spruce and birch were collected from a large number of sites in Southern and Southwestern Finland. Some of the samples were from a heavily polluted area in the vicinity of a copper-nickel smelter. The samples were dry ashed at 550 °C for the removal of the organic matrix in order to increase the analytical sensitivity of the method. The sensitivity was enhanced by a factor of 50 for wood and slightly less for bark. The ashed samples were pressed into pellets and irradiated as thick targets with a millimetre-sized proton beam. By including the ashing procedure in the method, the statistical dispersion due to elemental heterogeneities in wood material could be reduced. As a by-product, information about the elemental composition of ashes was obtained. By comparing the concentration of an element in bark ash to the concentration in wood ash of the same tree useful information from environmental point of view was obtained. The obtained ratio of the ashes was used to distinguish between elemental contributions from anthropogenic atmospheric sources and natural geochemical sources, like soil and bedrock.
4. PHARMACOGNOSTICAL STANDARDIZATION AND HPTLC FINGERPRINT OF ALSTONIA SCHOLARIS LINN. BARK
Directory of Open Access Journals (Sweden)
Avinash Patil
2014-03-01
Full Text Available There is increasing global interest in herbal and other forms of traditional medicines. Herbs have long been an important source of numerous effective drugs. As per World Health Organization recommendations, there is a need for investigation of traditional medicinal plants for their potential therapeutic efficacy. The bark of Alstonia scholaris (L. R. Br. (Family: Apocynaceae locally known as ‘Sapthaparni’ or ‘Satwid’, is reported to have anticancer, antihelminthic, antidiarrhoeal, antiasthamatic, antimalarial etc. The present work embodies the study carried out for quality control of herbal drugs which comprises of macroscopy, microscopy, physicochemical properties, phytochemical analysis, fluorescence analysis and HPTLC fingerprint. The anatomical markers present were found to be stone cells, sclereids, cork cells, fibers and prismatic crystals of calcium oxalate. Methanol soluble extractive value was found to be higher than Water, Ethanol and Petroleum ether soluble extractive values. Preliminary phytochemical analysis revealed the presence of tannins, alkaloids, steroids, amino acids, fats, fixed oil, glycosides, proteins, starch and flavonoids. A unique HPTLC fingerprint for A. scholaris (L. R. Br. bark was developed. Results of the present study on pharmacognostical and phytochemical investigation of A. scholaris (L. R. Br. bark will be helpful in developing standards for quality, purity and sample identification of this plant.
5. Bioaccessibility In Vitro of Nutraceuticals from Bark of Selected Salix Species
OpenAIRE
Urszula Gawlik-Dziki; Danuta Sugier; Dariusz Dziki; Piotr Sugier
2014-01-01
The aim of this study was to investigate and to compare the extractability, bioaccessibility, and bioavailability in vitro of antioxidative compounds from bark of selected Salix species: S. alba (SA), S. daphnoides (SD), S. purpurea (SP), and S. daphnoides x purpurea (SDP) hybrid willow clones originating from their natural habitats and cultivated on the sandy soil. The highest amount of phenolic glycosides was found in the bark of SDP and SD. The best source of phenolics was bark of SDP. The...
6. Quantifying Sources of Methane in the Alberta Oil Sands
Science.gov (United States)
Baray, S.; Darlington, A. L.; Gordon, M.; Hayden, K.; Li, S. M.; Mittermeier, R. L.; O'brien, J.; Staebler, R. M.; McLaren, R.
2015-12-01
In the summer of 2013, an aircraft measurement campaign led by Environment Canada with participation from university researchers took place to investigate the sources and transformations of gas pollutants in the Alberta oil sands region close to Fort McMurray, Alberta. Apart from its ability to change the radiative forcing of the atmosphere, methane is also a significant precursor to the formation of formaldehyde, an important radical source. Thus, emissions of methane from facilities need to be understood since they can have air quality implications through alteration of the radical budget and hence, the oxidation capacity of the air mass. Methane was measured, along with other gases, via a cavity ring-down spectroscopy instrument installed on the Convair-580 aircraft. In total, there were 22 flights with 82 hours of measurements in the vicinity of oil sands facilities between August 13 and September 7, 2013. Various tools have been used to visualize the spatial and temporal variation in mixing ratios of methane and other trace gases in order to identify possible sources of methane. Enhancements of methane from background levels of 1.9 ppm up to ~4 ppm were observed close to energy mining facilities in the oil sands region. Sources of methane identified include open pit mining, tailings ponds, upgrader stacks and in-situ mining operations. Quantification of the emission rates of methane from distinct sources has been accomplished from box flights and downwind screen flights by identifying the ratios of trace gases emitted and through use of the Top-down Emission Rate Retrieval Algorithm (TERRA). Methane emission rates for some of these sources will be presented.
7. Evaluation of Durability Parameters of Concrete with Manufacture Sand and River Sand
Science.gov (United States)
Sangoju, Bhaskar; Ramesh, G.; Bharatkumar, B. H.; Ramanjaneyulu, K.
2017-06-01
Most of the states in our country have banned sand quarrying from the river beds, causing a scarcity of natural river sand for the construction sector. Manufacture sand (M-sand) is one of the alternate solutions to replace the river sand (R-sand) in concrete. The main aim of the present study is to evaluate the durability parameters of concrete with M-sand when compared to that of concrete with R-sand. Corrosion of reinforcement is one of the main deteriorating mechanisms of reinforced concrete due to the ingress of chloride ions or carbon-di-oxide. For comparative evaluation of durability parameters, accelerated tests such as Rapid Chloride Permeability Test, Rapid Chloride Migration Test and accelerated carbonation test were carried out on specimens of R-sand and M-sand. All tests were carried out after 90 days of casting. Test results reveal that the durability parameters of the concrete with M-sand in chloride induced environment is relatively better than that of concrete with R-sand and hence is recommended to use M-sand as a replacement to R-sand.
8. Sand deposit-detecting method and its application in model test of sand flow
Institute of Scientific and Technical Information of China (English)
黎伟; 房营光; 莫海鸿; 谷任国; 陈俊生
2013-01-01
Against the background of the sand-flow foundation treatment engineering of Guangzhou Zhoutouzui variable cross-section immersed tunnel, a kind of sand deposit-detecting method was devised on the basis of full-scale model test of sand-flow method. The real-time data of sand-deposit height and radius were obtained by the self-developed sand-deposit detectors. The test results show that the detecting method is simple and has high precision. In the use of sand-flow method, the sand-carrying capability of fluid is limited, and sand particles are all transported to the sand-deposit periphery through crater, gap and chutes after the sand deposit formed. The diffusion range of the particles outside the sand-deposit does not exceed 2.0 m. Severe sorting of sand particles is not observed because of the unique oblique-layered depositing process. The temporal and spatial distributions of gap and chutes directly affect the sand-deposit expansion, and the expansion trend of the average sand-deposit radius accords with quadratic time-history curve.
9. Content of certain mineral components in the thallus of lichens and the bark of roadside trees
Directory of Open Access Journals (Sweden)
Stanisława Kuziel
2015-05-01
Full Text Available The total N, P, Mg, Ca, K and Na contents were investigated in the thalli of several lichen species occurring on various trees, and in the bark and bark extracts from these trees. pH of the bark extracts was also determined. Wide differences were found in the content of the elements in point in the thalli of various lichen species on Acer platanoides and on the thalli of the same species on other trees. No relation was detected between the chemical composition of the bark and that of the lichen thalli occurring on it.
10. Bioaccessibility in vitro of nutraceuticals from bark of selected Salix species.
Science.gov (United States)
Gawlik-Dziki, Urszula; Sugier, Danuta; Dziki, Dariusz; Sugier, Piotr
2014-01-01
The aim of this study was to investigate and to compare the extractability, bioaccessibility, and bioavailability in vitro of antioxidative compounds from bark of selected Salix species: S. alba (SA), S. daphnoides (SD), S. purpurea (SP), and S. daphnoides x purpurea (SDP) hybrid willow clones originating from their natural habitats and cultivated on the sandy soil. The highest amount of phenolic glycosides was found in the bark of SDP and SD. The best source of phenolics was bark of SDP. The highest content of flavonoids were found in SD bark samples, whereas the highest concentration of bioaccessible and bioavailable phenolic acids was determined in SDP bark. Bark of all tested Salix species showed significant antiradical activity. This properties are strongly dependent on extraction system and genetic factors. Regardless of Salix genotypes, the lowest chelating power was found for chemically-extractable compounds. Bark of all Salix species contained ethanol-extractable compounds with reducing ability. Besides this, high bioaccessibility and bioavailability in vitro of Salix bark phytochemicals were found. Obtained results indicate that extracts from bark tested Salix genotypes can provide health promoting benefits to the consumers; however, this problem requires further study.
11. Spatially distinct responses within willow to bark stripping by deer: effects on insect herbivory
Science.gov (United States)
Tanaka, Motonobu; Nakamura, Masahiro
2015-10-01
Within individual plants, cervid herbivory may cause positive or negative plant-mediated effects on insect herbivores, depending on where it occurs. Using a combination of field observations and artificial bark-stripping experiments in Hokkaido, Japan, we examined the plant-mediated effects of bark stripping by sika deer ( Cervus nippon yesoensis) on insect herbivory in two spatially distinct parts of willow ( Salix udensis) trees: resprouting leaves below bark-stripping wounds and canopy leaves above. Natural and artificial bark stripping stimulated resprouting from trunks below wounds. Resprouting leaves on bark-stripped trees had lower total phenolics, condensed tannin, and C/N ratios than did canopy leaves on control trees. Herbivory rates were higher in resprouting leaves on bark-stripped trees than in canopy leaves on controls. Conversely, above-wound canopy leaves on bark-stripped trees had higher total phenolics than did those on controls, while herbivory rates were lower in the canopy leaves of bark-stripped trees than in those on controls. These results demonstrate that plant-mediated effects of bark stripping diverge between plant tissues below and above wounds in individual willow trees. We submit that focusing on multiple plant parts can elucidate plant-mediated effects at the whole-plant scale.
12. Space radiation studies at the White Sands Missile Range Fast Burst Reactor
Science.gov (United States)
Delapaz, A.
1972-01-01
The operation of the White Sands Missile Range Fast Burst Reactor is discussed. Space radiation studies in radiobiology, dosimetry, and transient radiation effects on electronic systems and components are described. Proposed modifications to increase the capability of the facility are discussed.
13. Users manual for SNL-SAND-II code
Energy Technology Data Exchange (ETDEWEB)
Griffin, P.J.; Kelly, J.G. [Sandia National Labs., Albuquerque, NM (United States); VanDenburg, J.W. [Science and Engineering Associates, Inc., Albuquerque, NM (United States)
1994-04-01
Sandia National Laboratories, in the process of characterizing the neutron environments at its reactor facilities, has developed an enhanced version of W. McElroys original SAND-II code. The enhanced input, output, and plotting interfaces make the code much easier to use. The basic physics and operation of the code remain unchanged. Important code enhancements include the interfaces to the latest ENDF/B-VI and IRDF-90 dosimetry-quality cross sections and the ability to use silicon displacement-sensitive devices as dosimetry sensors.
14. Cryptically patterned moths perceive bark structure when choosing body orientations that match wing color pattern to the bark pattern.
Directory of Open Access Journals (Sweden)
Chang-Ku Kang
Full Text Available Many moths have wing patterns that resemble bark of trees on which they rest. The wing patterns help moths to become camouflaged and to avoid predation because the moths are able to assume specific body orientations that produce a very good match between the pattern on the bark and the pattern on the wings. Furthermore, after landing on a bark moths are able to perceive stimuli that correlate with their crypticity and are able to re-position their bodies to new more cryptic locations and body orientations. However, the proximate mechanisms, i.e. how a moth finds an appropriate resting position and orientation, are poorly studied. Here, we used a geometrid moth Jankowskia fuscaria to examine i whether a choice of resting orientation by moths depends on the properties of natural background, and ii what sensory cues moths use. We studied moths' behavior on natural (a tree log and artificial backgrounds, each of which was designed to mimic one of the hypothetical cues that moths may perceive on a tree trunk (visual pattern, directional furrow structure, and curvature. We found that moths mainly used structural cues from the background when choosing their resting position and orientation. Our findings highlight the possibility that moths use information from one type of sensory modality (structure of furrows is probably detected through tactile channel to achieve crypticity in another sensory modality (visual. This study extends our knowledge of how behavior, sensory systems and morphology of animals interact to produce crypsis.
15. Alberta oil sands crudes : upgrading and marketing
Energy Technology Data Exchange (ETDEWEB)
Ashar, M. [Suncor Energy, Fort McMurray, AB (Canada)
2008-05-15
Open pit mining and in situ techniques, such as steam stimulation, are used to recover Alberta's bitumen and heavy oil resources, which have higher viscosities than conventional hydrocarbons. The bitumen is typically upgraded to synthetic crude oil (SCO). In the simplest processing scheme, the bitumen is blended with diluent for ease in pipeline transport and then processed at refineries with upgrading facilities. The bitumen is also upgraded to light SCO at world-scale upgraders in Alberta. The SCO is then processed at refineries in downstream markets. The 2 categories of upgrading, notably primary and secondary upgrading, were described in this article along with technology options for both categories. Slurry hydrocracking is regarded as the most interesting emerging residual fuel upgrading technology. It combines special catalyst mixes with the latest slurry reactor designs as well as innovative catalyst capture and recycle schemes to produce very high conversions and potentially superior upgrading economics. The increase in volume and rate of SCO from Alberta provides refiners in the oil sands marketing sector an unprecedented choice of opportunities to improve profitability. Key trends indicate that production will increase substantially from 2008 to 2030. 5 figs.
16. SAND
DEFF Research Database (Denmark)
Thorsen, Grete
Der er udført et konsolideringsforsøg med bakkesand fra Lunds grusgrav, Lund no. O. forsøget er udført i samme konsolideringsapparat, som er anvendt til måling af deformationsegenskaberne af mange forskellige danske jordarter. Forsøgsresultaterne er søgt tolket som ved forsøg med andre jordarter....
17. Fabrication Facilities
Data.gov (United States)
Federal Laboratory Consortium — The Fabrication Facilities are a direct result of years of testing support. Through years of experience, the three fabrication facilities (Fort Hood, Fort Lewis, and...
18. Facility Microgrids
Energy Technology Data Exchange (ETDEWEB)
Ye, Z.; Walling, R.; Miller, N.; Du, P.; Nelson, K.
2005-05-01
Microgrids are receiving a considerable interest from the power industry, partly because their business and technical structure shows promise as a means of taking full advantage of distributed generation. This report investigates three issues associated with facility microgrids: (1) Multiple-distributed generation facility microgrids' unintentional islanding protection, (2) Facility microgrids' response to bulk grid disturbances, and (3) Facility microgrids' intentional islanding.
19. Liquefaction of Sand under Low Confining Pressure
Institute of Scientific and Technical Information of China (English)
YANG Shaoli; Rolf Sandven; Lars Grande
2003-01-01
Undrained behaviour of sand under low cell pressure was studied in static and cyclic triaxial tests. It was found that very loose sand liquefies under static loading with the relative density being a key parameter for the undrained behaviour of sand. In cyclic triaxial tests, pore water pressures built up during the cyclic loading and exceeded the confining cell pressure. This process was accompanied by a large sudden increase in axial deformation. The necessary number of cycles to obtain liquefaction was related to the confining cell pressure, the amplitude of cyclic loading and the relative density of sand.In addition, the patterns of pore water pressure response are different from those of sand samples with different relative densities. The test results are very useful for expounding scour mechanism around coastal structures since they relate to the low stress behaviour of the sand.
20. Study for exploitation of Eucalyptus bark generated in the process of manufacturing of wood panels; Estudo para aproveitamento de cascas de Eucalyptus geradas no processo de fabricacao de paineis de madeira
Energy Technology Data Exchange (ETDEWEB)
Saglietti, Jose Roberto Correa; Rezende, Marcos Antonio [Universidade Estadual Paulista (IBB/UNESP), Botucatu, SP (Brazil). Inst. de Biociencias de Botucatu. Dept. de Fisica e Biofisica], E-mail: [email protected]; Santiago, Francisco Luiz Sanchez [Universidade Estadual Paulista (FCA/UNESP), Botucatu, SP (Brazil). Fac. de Ciencias Agronomicas
2009-07-01
In the wood fibreboard sheet manufacturing industries the use of Eucalyptus grandis has been used both as a raw material as well as fuel (biomass) for generating thermal energy as steam, water and hot air. This paper presents the results of a study obtained in a production plant at one facility in Botucatu, SP, Brazil. The generated amount of solid residues and barks, and also their heat energy, have been measured such that these residues can be used as fuel in steam boilers. The annual volume of wood applied for combustion has been 153,125 m{sup 3}/year at the plant in study. By leveraging the volume of the bark with wood saved for this purpose is 20,707 m{sup 3} / year, representing an annual savings of 13.52% of the average annual volume of wood to generate heat energy demanded by the facility under study. (author)
1. Creep Behavior of Frozen Sand.
Science.gov (United States)
1981-06-01
temperature and stress range. There was a 2strong stress dependance to S (r =0.95) for saturated Manchester Fine Sand which does not agree with RPT. The...Curves at High Stress 161 Ratio D/Du = 0.505 for Frozen HF’S at w=10% IV-20 Minimum Strain Rate Dependance on Stress 162 Ratio for Frozen MFS IV-21 Minimum...Strain Rate Dependance on Relative 163 Density for Frozen MFS IV-22 Temperature Stage Test on Frozen Saturated 164 MFS under a Load of D=9.24MPa Fig
2. Evaluation of pine bark for treatment of water from biomass fueled plants; Utvaerdering av bark foer rening av vatten vid biobraensleeldade anlaeggningar
Energy Technology Data Exchange (ETDEWEB)
Hansson, Christina; Hansson, Helen; Hansson, Soeren [Carl Bro Energikonsult AB, Malmoe (Sweden)
2004-01-01
3. BIOSORPTION OF LEAD (II ON MODIFIED BARKS EXPLAINED BY THE HARD AND SOFT ACIDS AND BASES (HSAB THEORY
Directory of Open Access Journals (Sweden)
Cedric Astier,
2012-01-01
Full Text Available Chemical modification of Douglas fir bark and its subsequent utilization in adsorption of Pb(II from aqueous solutions was investigated. The polysaccharidic moiety of barks was functionalized by periodate oxidation and derivatized after reductive amination in the presence of aminated oligo-carrageenans. Pb(II adsorption isotherms of derivatized barks were then determined and compared to the capabilities of crude barks using the Langmuir adsorption model in terms of affinity (b and maximum binding capacity (qmax. Compared to crude barks, the derivatization of barks by oligo-carrageenans resulted in significant enhancements of qmax and b by up to x8 and x4, respectively. The results obtained from crude barks on chemically grafted carboxylic and sulfated barks are discussed and interpreted through the Hard and Soft Acids and Bases (HSAB theory.
4. Recent advances in waterglass sand technologies
Institute of Scientific and Technical Information of China (English)
ZHU Chun-xi
2007-01-01
This paper reports some new understandings and advances in waterglass sand technologies. The multiple chemical modification process can increase the binding strength of the waterglass sand by up to 50%-70%.Therefore, the additions of the modified waterglass can be decreased to 3.0%-4.0% for CO2 process and to 2.0%-2.5% for organic ester hardening process, and greatly improve the collapsibility and reclaimability of the sand. Based on the new understandings and experimental results reported in this paper, several original ideas, such as nano modification, have been proposed to promote advances of waterglass sand technologies,
5. PROSPECTS FIXATION DRIFT SANDS PHYSICOCHEMICAL METHOD
Directory of Open Access Journals (Sweden)
Maujuda MUZAFFAROVA
2016-09-01
Full Text Available This article is based on the theoretical foundations of secure mobile sand being considered for reducing the negative impact of one of the manifestations of exogenous plains on such an important natural-technical system as a railroad. It suggests practical measures to build a system of design protection against sand drifts. The article also suggests ways to conserve resources and rational use of machinery and performers as well as the consolidation of mobile sand wet with water soluble waste of local production of waste dextrin. Consolidation is exposed on dry and wet sand.
6. Innovative developments in sand reclamation technologies
Directory of Open Access Journals (Sweden)
R. Dañko
2011-04-01
Full Text Available Proper sand management and efficient sand reclamation system are two main factors influencing economical and ecological side of modern foundry plant. It is well known fact that the production of 1 metric ton of casting from ferrous alloys generates circa 1 metric ton of waste [1], which due to containing certain amounts of harmful and dangerous compounds should undergo a reclamation – at least of the main component, which means a silica sand grains. The paper present problems of scientific and development research concerning the innovative reclamation technologies of used foundry sands such as: mechanical-cryogenic reclamation and innovative thermal reclamation.
7. Sand Failure Mechanism and Sanding Parameters in Niger Delta Oil Reservoirs
OpenAIRE
2010-01-01
Sand production is a major issue during oil and gas production from unconsolidated reservoirs. In predicting the onset of sand production, it is important to accurately determine the failure mechanism and the contributing parameters. The aim of this study was to determine sand failure mechanism in the Niger-Delta, identify themajor contributing parameters and evaluate their effects on sanding.Completion and production data from 78 strings completed on 22 reservoirs in a Niger Delta oil Field ...
8. Selective bark-stripping of beech, Fagus sylvatica, by free-ranging horses
NARCIS (Netherlands)
Kuiters, A.T.; Sluijs, van der L.A.M.; Wytema, G.A.
2006-01-01
Incidence and intensity of bark-stripping by horses was surveyed in stands and tree lanes of European beech (Fagus sylvatica L.) in Veluwezoom National Park, by using transects. Damage was apparent on 38% of beech trees, and 11% were seriously damaged (score 3 or more). Susceptibility to bark-stripp
9. Bark water uptake promotes localized hydraulic recovery in coastal redwood crown.
Science.gov (United States)
Mason Earles, J; Sperling, Or; Silva, Lucas C R; McElrone, Andrew J; Brodersen, Craig R; North, Malcolm P; Zwieniecki, Maciej A
2016-02-01
Coastal redwood (Sequoia sempervirens), the world's tallest tree species, rehydrates leaves via foliar water uptake during fog/rain events. Here we examine if bark also permits water uptake in redwood branches, exploring potential flow mechanisms and biological significance. Using isotopic labelling and microCT imaging, we observed that water entered the xylem via bark and reduced tracheid embolization. Moreover, prolonged bark wetting (16 h) partially restored xylem hydraulic conductivity in isolated branch segments and whole branches. Partial hydraulic recovery coincided with an increase in branch water potential from about -5.5 ± 0.4 to -4.2 ± 0.3 MPa, suggesting localized recovery and possibly hydraulic isolation. As bark water uptake rate correlated with xylem osmotic potential (R(2) = 0.88), we suspect a symplastic role in transferring water from bark to xylem. Using historical weather data from typical redwood habitat, we estimated that bark and leaves are wet more than 1000 h per year on average, with over 30 events being sufficiently long (>24 h) to allow for bark-assisted hydraulic recovery. The capacity to uptake biologically meaningful volumes of water via bark and leaves for localized hydraulic recovery throughout the crown during rain/fog events might be physiologically advantageous, allowing for relatively constant transpiration.
10. A Phloem Sandwich Unit for Observing Bark Beetles, Associated Predators, and Parasites
Science.gov (United States)
Donald N. Kim; Mitchel C. Miller
1981-01-01
This paper describes a phloem sandwich that allows observation of parent beetles, their brood, and associates within the inner bark, and permits observation of predator and parasite behavior on the bark surface. The construction of the unit permits the introduction of multiple pairs of beetles into a single sandwich.
11. Powder microscopy of bark--poison used for abortion: moringa pterygosperma gaertn.
Science.gov (United States)
Bhattacharya, J; Guha, G; Bhattacharya, B
1978-01-01
Moringa pterygosperma Gaertn. (Moringaceae) is a soft white wood tree with a gummy juice which grows all over India. The bark of the tree, powdered, produces an abortifacient which causes violent uterine contractions giving fatal results. This abortifacient agent is used in the Bengali area of India. Laboratory preparation and analysis of the powdered bark is described.
12. A comparison of paraffin and resin-based techniques used in bark anatomy
NARCIS (Netherlands)
Hamann, T.; Smets, E.; Lens, F.
2011-01-01
Bark anatomy is an unappreciated discipline in plant systematics, despite its great potential to reveal systematically informative features. In this paper, main reasons for the lack of detailed bark anatomical data in many plant families are identified, including problems with sectioning,
13. 78 FR 23592 - Certain Electronic Bark Control Collars, Termination of the Investigation
Science.gov (United States)
2013-04-19
... COMMISSION Certain Electronic Bark Control Collars, Termination of the Investigation AGENCY: U.S... certain electronic bark control collars by reason of infringement of certain claims of U.S. Patent No. 5....usitc.gov . The public record for this investigation may be viewed on the Commission's electronic...
14. Linking Increasing Drought Stress to Scots Pine Mortality and Bark Beetle Infestations
Directory of Open Access Journals (Sweden)
Matthias Dobbertin
2007-01-01
Full Text Available In the dry Swiss Rhone Valley, Scots pine forests have experienced increased mortality in recent years. It has commonly been assumed that drought events and bark beetles fostered the decline, however, whether bark beetle outbreaks increased in recent years and whether they can be linked to drought stress or increasing temperature has never been studied.
15. Size and composition of airborne particles from pavement wear, tires, and traction sanding.
Science.gov (United States)
Kupiainen, Kaarle J; Tervahattu, Heikki; Räisänen, Mika; Mäkelä, Timo; Aurela, Minna; Hillamo, Risto
2005-02-01
Mineral matter is an important component of airborne particles in urban areas. In northern cities of the world, mineral matter dominates PM10 during spring because of enhanced road abrasion caused by the use of antiskid methods, including studded tires and traction sanding. In this study, factors that affect formation of abrasion components of springtime road dust were assessed. Effects of traction sanding and tires on concentrations, mass size distribution, and composition of the particles were studied in a test facility. Lowest particle concentrations were observed in tests without traction sanding. The concentrations increased when traction sand was introduced and continued to increase as a function of the amount of aggregate dispersed. Emissions were additionally affected by type of tire, properties of traction sand aggregate, and driving speed. Aggregates with high fragmentation resistance and coarse grain size distribution had the lowest emissions. Over 90% of PM10 was mineral particles. Mineralogy of the dust and source apportionment showed that they originated from both traction sand and pavement aggregates. The remaining portion was mostly carbonaceous and originated from tires and road bitumen. Mass size distributions were dominated by coarse particles. Contribution of fine and submicron size ranges were approximately 15 and 10% in PM10, respectively.
16. Phytochemical Analysis and Biological Activities of Cola nitida Bark
Directory of Open Access Journals (Sweden)
Durand Dah-Nouvlessounon
2015-01-01
Full Text Available Kola nut is chewed in many West African cultures and is used ceremonially. The aim of this study is to investigate some biological effects of Cola nitida’s bark after phytochemical screening. The bark was collected, dried, and then powdered for the phytochemical screening and extractions. Ethanol and ethyl acetate extracts of C. nitida were used in this study. The antibacterial activity was tested on ten reference strains and 28 meat isolated Staphylococcus strains by disc diffusion method. The antifungal activity of three fungal strains was determined on the Potato-Dextrose Agar medium mixed with the appropriate extract. The antioxidant activity was determined by DPPH and ABTS methods. Our data revealed the presence of various potent phytochemicals. For the reference and meat isolated strains, the inhibitory diameter zone was from 17.5±0.7 mm (C. albicans to 9.5±0.7 mm (P. vulgaris. The MIC ranged from 0.312 mg/mL to 5.000 mg/mL and the MBC from 0.625 mg/mL to >20 mg/mL. The highest antifungal activity was observed with F. verticillioides and the lowest one with P. citrinum. The two extracts have an excellent reducing free radical activity. The killing effect of A. salina larvae was perceptible at 1.04 mg/mL. The purified extracts of Cola nitida’s bark can be used to hold meat products and also like phytomedicine.
17. Phytochemical Analysis and Biological Activities of Cola nitida Bark.
Science.gov (United States)
Dah-Nouvlessounon, Durand; Adoukonou-Sagbadja, Hubert; Diarrassouba, Nafan; Sina, Haziz; Adjanohoun, Adolphe; Inoussa, Mariam; Akakpo, Donald; Gbenou, Joachim D; Kotchoni, Simeon O; Dicko, Mamoudou H; Baba-Moussa, Lamine
2015-01-01
Kola nut is chewed in many West African cultures and is used ceremonially. The aim of this study is to investigate some biological effects of Cola nitida's bark after phytochemical screening. The bark was collected, dried, and then powdered for the phytochemical screening and extractions. Ethanol and ethyl acetate extracts of C. nitida were used in this study. The antibacterial activity was tested on ten reference strains and 28 meat isolated Staphylococcus strains by disc diffusion method. The antifungal activity of three fungal strains was determined on the Potato-Dextrose Agar medium mixed with the appropriate extract. The antioxidant activity was determined by DPPH and ABTS methods. Our data revealed the presence of various potent phytochemicals. For the reference and meat isolated strains, the inhibitory diameter zone was from 17.5 ± 0.7 mm (C. albicans) to 9.5 ± 0.7 mm (P. vulgaris). The MIC ranged from 0.312 mg/mL to 5.000 mg/mL and the MBC from 0.625 mg/mL to >20 mg/mL. The highest antifungal activity was observed with F. verticillioides and the lowest one with P. citrinum. The two extracts have an excellent reducing free radical activity. The killing effect of A. salina larvae was perceptible at 1.04 mg/mL. The purified extracts of Cola nitida's bark can be used to hold meat products and also like phytomedicine.
18. Lancifoliaine, a New Bisbenzylisoquinoline from the Bark of Litsea lancifolia
Directory of Open Access Journals (Sweden)
Kazumasa Zaima
2011-04-01
Full Text Available A new bisbenzylisoquinoline, lancifoliaine (1, together with seven known alkaloids – N-allyllaurolitsine (2, reticuline (3, actinodaphnine, norboldine, pallidine, cassythicine and boldine – were isolated from the stem bark of Litsea lancifolia (Lauraceae. In addition to that of lancifoliaine, complete 13C-NMR data of N-allyl-laurolitsine (2 was also reported. The alkaloidal structures were elucidated by means of high field 1D- and 2D-NMR IR, UV, and LCMS-IT-TOF spectral data. N-Allyllaurolitsine (2 showed a moderate vasorelaxant activity on isolated rat aorta.
19. Pharmacognostical evaluation of medicinally important Ficus retusa (Leaves and bark
Directory of Open Access Journals (Sweden)
Alok Semwal
2013-01-01
Full Text Available Ficus retusa (F. retusa belongs to family Moraceae is a large and extensively growing tree across Indian continent. It's commonly known as Chilkan and Marabuten. This tree is claimed to have medicinal properties. The aim of present study is to investigate the pharmacognostical characters of important medicinal plant, F. retusa L. The pharmacognostic studies were carried out in terms of macroscopical, microscopical characters, standardization, phytoconstituents and chromatographic analysis of F. retusa leaf and bark. Various standard methods were adopted to carry out the investigation.
20. Cytotoxic Constituents from bark and leaves of Amyris pinnata Kunth.
Directory of Open Access Journals (Sweden)
Luis Enrique Cuca-Suarez
2015-04-01
Full Text Available From leaves and bark of Amyris pinnata Kunth twelve compounds were isolated, corresponding to six lignans 1-6, three coumarins 7-9, a sesquiterpene 10, an oxazole alkaloid 11, and a prenylated flavonoid 12,. Metabolites were identified by spectroscopic techniques ( 1H and 13C NMR, EIMS and by comparison with published data in the literature. C ytotoxicity against leukemia, solid tumors, and normal cells was evaluated for all isolated compounds. Lignans were found to be the most cytotoxic compounds occurring in A. pinnata.
1. A new chromanone acid from the bark of Calophyllum dryobalanoides
DEFF Research Database (Denmark)
Dieu, Ly Ha; Hansen, Poul Erik; Duus, Fritz;
2012-01-01
A new chromanone acid, calodryobalanoic acid, along with six known compounds, apetalic acid, isoblancoic acid, lupeol, 1-hydroxy-2-methoxyxanthone, 1,7-dihydroxy-3-methoxyxanthone, and 5,7,4′-trihydroxyflavanone, was isolated from the bark of Calophyllum dryobalanoides collected in Vietnam. The s....... The structure of the new compound was elucidated using mainly 1-D and 2-D NMR techniques (1H and 13C NMR, HSQC, HMBC, COSY, and NOESY) and IR spectroscopy. The stereochemistry was determined on the basis of NMR results and DFT calculations....
2. Calotroposide S, New Oxypregnane Oligoglycoside from Calotropis procera Root Bark
Directory of Open Access Journals (Sweden)
Sabrin R. M. Ibrahim
2016-05-01
Full Text Available Calotroposide S (1, a new oxypregnane oligoglycoside has been isolated from the n-butanol fraction of Calotropis procera (Ait R. Br. root bark. The structure of 1 was assigned based on various spectroscopic analyses. Calotroposide S (1 possesses the 12-O-benzoylisolineolon aglycone moiety with eight sugar residues attached to C-3 of the aglycone. It showed potent anti-proliferative activity towards PC-3 prostate cancer, A549 non-small cell lung cancer (NSCLC, and U373 glioblastoma (GBM cell lines with IC 50 0.18, 0.2, and 0.06 µM, respectively compared with cisplatin and carboplatin.
3. Lactam Triterpenoids from the Bark of Toona sinensis
Directory of Open Access Journals (Sweden)
Qian-Qian Meng
2016-10-01
Full Text Available Abstract Three new limonoid-type triterpenoids, namely toonasins A–C (1–3 with a rare lactam E ring, along with six known compounds (4–9 were isolated from the barks of Toona sinensis. The structures of new compounds were elucidated by interpretation of spectroscopic data, and the relative configuration of compound 1 was further characterized by X-ray crystallographic analyses. The isolated compounds were evaluated for their cytotoxic activities against five human tumor cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW480, and compounds 3 and 5 showed weak cytotoxicities.
4. Antiplasmodial and larvicidal compounds of Toddalia asiatica root bark
T Nyahanga; J Isaac Jondiko; L Onyango Arot Manguro; J Atieno Orwa
2013-09-01
From the -hexane, ethyl acetate and methanol extracts of Toddalia asiatica root bark were isolated eight compounds (1-8) which were identified on the basis of both spectroscopic and physical data as well as comparison with already published results. The crude extracts and isolated compounds showed moderate in vitro antiplasmodial activity against D6 (chloroquine-sensitive) and W2 (chloroquine-resistant) strains of Plasmodium falciparum. The extracts and isolates also exhibited larvicidal activities against Aedes aegypti and coumarins were identified as the active compounds.
5. Chemical Constituents from Stem Bark and Roots of Clausena anisata
Directory of Open Access Journals (Sweden)
Etienne Dongo
2012-11-01
Full Text Available Phytochemical investigations on the stem bark and roots of the tropical shrub Clausena anisata led to the isolation and characterization three carbazole alkaloids: girinimbine, murrayamine-A and ekeberginine; two peptide derivatives: aurantiamide acetate and N-benzoyl-l-phenylalaninyl-N-benzoyl-l-phenylalaninate; and a mixture of two phytosterols: sitosterol and stigmasterol. The structures of these compounds were established by nuclear magnetic resonance (1H-NMR, 13C-NMR, COSY, HSQC, HMQC, HMBC and NOESY spectroscopy and electrospray ionization mass spectrometry (MS.
6. Terpenoids from the root bark of Pterolobium macropterum.
Science.gov (United States)
Suthiwong, Jittra; Pitchuanchom, Siripit; Wattanawongdon, Wareeporn; Hahnvajanawong, Chariya; Yenjai, Chavi
2014-11-26
Five new compounds, including pteroloterins A-C (1, 3, and 4), 1β-acetoxytaepeenin C (2), and 8aα-hydroxycadinenal (5), and 11 known compounds were isolated from the root bark of Pterolobium macropterum. All compounds were evaluated for cytotoxicity against the cholangiocarcinoma cell lines. Compound 9 showed weak cytotoxicity against the KKU-M139 cell line with an IC50 value of 23.24 ± 0.18 μM and showed no activity against normal cells.
7. Hot water extraction and steam explosion as pretreatments for ethanol production from spruce bark.
Science.gov (United States)
Kemppainen, Katariina; Inkinen, Jenni; Uusitalo, Jaana; Nakari-Setälä, Tiina; Siika-aho, Matti
2012-08-01
Spruce bark is a source of interesting polyphenolic compounds and also a potential but little studied feedstock for sugar route biorefinery processes. Enzymatic hydrolysis and fermentation of spruce bark sugars to ethanol were studied after three different pretreatments: steam explosion (SE), hot water extraction (HWE) at 80 °C, and sequential hot water extraction and steam explosion (HWE+SE), and the recovery of different components was determined during the pretreatments. The best steam explosion conditions were 5 min at 190 °C without acid catalyst based on the efficiency of enzymatic hydrolysis of the material. However, when pectinase was included in the enzyme mixture, the hydrolysis rate and yield of HWE bark was as good as that of SE and HWE+SE barks. Ethanol was produced efficiently with the yeast Saccharomyces cerevisiae from the pretreated and hydrolysed materials suggesting the suitability of spruce bark to various lignocellulosic ethanol process concepts.
8. Rotation planar extraction and rotation planar chromatography of oak (Quercus robur L.) bark.
Science.gov (United States)
Vovk, Irena; Simonovska, Breda; Andrensek, Samo; Vuorela, Heikki; Vuorela, Pia
2003-04-04
The versatile novel instrument for rotation planar extraction and rotation planar chromatography was exploited for the investigation of oak bark (Quercus robur L.). The same instrument enabled extraction of the bark, analytical proof of (+)-catechin directly in the crude extract and also its fractionation. Additionally, epimeric flavan-3-ols, (+)-catechin and (-)-epicatechin were separated by analytical ultra-micro rotation planar chromatography on cellulose plates with pure water as developing solvent. A comparison of the extraction of oak bark with 80% aqueous methanol by rotation planar extraction and medium pressure solid-liquid extraction was carried out and both techniques were shown to be suitable for the efficient extraction of oak bark. The raw extracts and fractions on thin-layer chromatography showed many compounds that possessed antioxidant activity after spraying with 1,1-diphenyl-2-picrylhydrazyl. Rotation planar fractionation of 840 mg of crude oak bark extract on silica gel gave 6.7 mg of pure (+)-catechin in one run.
9. Isolation and characterization of cellulose nanocrystals from spruce bark in a biorefinery perspective.
Science.gov (United States)
Le Normand, Myriam; Moriana, Rosana; Ek, Monica
2014-10-13
The present study reports for the first time the isolation of cellulose fibers and cellulose nanocrystals (CNCs) from the bark of Norway spruce. The upgrading of bark cellulose to value-added products, such as CNCs, is part of the "bark biorefinery" concept. The removal of non-cellulosic constituents was monitored throughout the isolation process by detailed chemical composition analyses. The morphological investigation of the CNCs was performed using AFM and showed the presence of nanocrystals with an average length of 175.3 nm and a diameter of 2.8 nm, giving an aspect ratio of around 63. X-ray diffraction (XRD) analyses showed that the crystallinity index increased with successive treatments to reach a final value greater than 80% for CNCs. The thermal degradation of the isolated bark CNCs started at 190 °C. Spruce bark appeared to be a new promising industrial source of cellulose fibers and CNCs. Copyright © 2014 Elsevier Ltd. All rights reserved.
10. Combustion characteristics of red alder bark. Technical progress report No. 6, September 16, 1977--Septermber 15, 1978
Energy Technology Data Exchange (ETDEWEB)
Junge, D.C.
1978-12-01
Significant quantities of wood residue fuels are presently being used in industrial steam generating facilities. Recent studies indicate that substantial additional quantities of wood residue fuels are available for energy generation in the form of steam and/or electricity. A limited data base on the combustion characteristics of wood residue fuels has resulted in the installation and operation of inefficient combustion systems for these fuels. This investigation of the combustion characteristics of wood residue fuels was undertaken to provide a data base which could be used to optimize the combustion of such fuels. Optimization of the combustion process in industrial boilers serves to improve combustion efficiency and to reduce air pollutant emissions generated in he combustion process. Data are presented on the combustion characteristics of red alder bark.
11. BARK-MIMETIC LAYER-BY-LAYER ASSEMBLED MONTMORILLONITE/POLY(p-AMINOSTYRENE) FLEXIBLE NANOCOMPOSITES SHIELDING ATOMIC OXYGEN EROSION
Institute of Scientific and Technical Information of China (English)
Min Gao; Bing-jun Liu; Long-cheng Gao; Peng-gang Yin; Lei Jiang
2013-01-01
Inspired by the birch bark,which has multilayered structures,we fabricated layer-by-layer (LbL) assembled montmorillonite (MMT) and poly(p-aminostyrene) (PPAS) nanocomposites on cotton fiber curved surfaces to provide protection from atomic oxygen (AO) erosion.The multilayer coated fibers had high flexibility,uniformity,defect free,ease of preparation and low cost.The AO erosion durability has been dramatically enhanced which was evidenced by testing in the ground-based AO effects simulation facility.And the dimension and surface morphologies of the fibers observed by SEM had few changes,indicating excellent AO erosion resistant ability of the coatings.These results provide us a new method to design fibrous materials exposed directly in low earth orbit environment.
12. Study of Black Sand Particles from Sand Dunes in Badr, Saudi Arabia Using Electron Microscopy
Directory of Open Access Journals (Sweden)
Haider Abbas Khwaja
2015-08-01
Full Text Available Particulate air pollution is a health concern. This study determines the microscopic make-up of different varieties of sand particles collected at a sand dune site in Badr, Saudi Arabia in 2012. Three categories of sand were studied: black sand, white sand, and volcanic sand. The study used multiple high resolution electron microscopies to study the morphologies, emission source types, size, and elemental composition of the particles, and to evaluate the presence of surface “coatings or contaminants” deposited or transported by the black sand particles. White sand was comprised of natural coarse particles linked to wind-blown releases from crustal surfaces, weathering of igneous/metamorphic rock sources, and volcanic activities. Black sand particles exhibited different morphologies and microstructures (surface roughness compared with the white sand and volcanic sand. Morphological Scanning Electron Microscopy (SEM and Laser Scanning Microscopy (LSM analyses revealed that the black sand contained fine and ultrafine particles (50 to 500 nm ranges and was strongly magnetic, indicating the mineral magnetite or elemental iron. Aqueous extracts of black sands were acidic (pH = 5.0. Fe, C, O, Ti, Si, V, and S dominated the composition of black sand. Results suggest that carbon and other contaminant fine particles were produced by fossil-fuel combustion and industrial emissions in heavily industrialized areas of Haifa and Yanbu, and transported as cloud condensation nuclei to Douf Mountain. The suite of techniques used in this study has yielded an in-depth characterization of sand particles. Such information will be needed in future environmental, toxicological, epidemiological, and source apportionment studies.
13. Habitat analysis of North American sand flies near veterans returning from leishmania-endemic war zones
Directory of Open Access Journals (Sweden)
Keep Lisa
2008-12-01
Full Text Available Abstract Background Nearly 1300 cases of leishmaniasis have been identified in American military personnel deployed to Iraq and Afghanistan. The symptoms of this disease can range from a mild, self-limiting cutaneous infection to a deadly visceral infection and are not prevented by chemoprophylaxis or immunization. Effective treatments, however, are available. The disease-causing parasite is spread through the bite of the female sand fly. Although the disease occurs in both the Old World and the New World, the parasite species differ between the hemispheres. The large number of cases in military veterans has caused some concern that Old World, temperate-adapted parasite species could be introduced into the native sand fly populations of American military facilities where veterans of the current conflicts return following their deployments. This paper reports part of a larger study to analyze the risk of such an accidental importation. Four potential habitats on two large Army facilities in the Southeast United States were surveyed to determine relative sand fly density. The National Land Cover Map was used to provide sand fly density prediction maps by habitat. Results Sand fly density was significantly higher in deciduous forest and even higher at the interface between forest and open grassland. The evergreen forest and agricultural fields supported very low densities. On Fort Campbell, KY, the percentage of land covered by suitable habitat was very high. A sand fly density prediction map identified large tracts of land where infected individuals would be at higher risk of exposure to sand fly bites, resulting in an increased risk of introducing the parasite to a native insect population. On Fort Bragg, NC, however, commercial farming of long leaf pine reduced the percentage of the land covered in vegetation suitable for the support of sand flies. The risk of introducing an exotic Leishmania spp. on Fort Bragg, therefore, is considered to be
14. Pattern formation - Instabilities in sand ripples
DEFF Research Database (Denmark)
Hansen, J. L.; v. Hecke, M.; Haaning, A.
2001-01-01
Sand ripples are seen below shallow wavy water and are formed whenever water oscillates over a bed of sand. Here we analyse the instabilities that can upset this perfect patterning when the ripples are subjected to large changes in driving amplitude or frequency, causing them to deform both...
15. Pilot Project Sand Groynes Delfland Coast
NARCIS (Netherlands)
Hoekstra, R.; Walstra, D.J.R.; Swinkels, C.S.
2012-01-01
In October and November 2009 a pilot project has been executed at the Delfland Coast in the Netherlands, constructing three small sandy headlands called Sand Groynes. Sand Groynes are nourished from the shore in seaward direction and anticipated to redistribute in the alongshore due to the impact of
16. Silica sand resources in the Netherlands
NARCIS (Netherlands)
Meulen, M.J. van der; Westerhoff, W.E.; Menkovic, A.; Gruijters, S.H.L.L.; Dubelaar, C.W.; Maljers, D.
2009-01-01
Silica sand, (almost) pure quartz sand, is a valuable and scarce mineral resource within the shallow Dutch subsurface. High-grade deposits are exploited in the southeastemmost part of the country, as raw material for the glass, ceramic, chemical and other process industries. Dutch land-use policy re
17. Pilot Project Sand Groynes Delfland Coast
NARCIS (Netherlands)
Hoekstra, R.; Walstra, D.J.R.; Swinkels, C.S.
2012-01-01
In October and November 2009 a pilot project has been executed at the Delfland Coast in the Netherlands, constructing three small sandy headlands called Sand Groynes. Sand Groynes are nourished from the shore in seaward direction and anticipated to redistribute in the alongshore due to the impact of
18. Understanding Colombian Amazonian white sand forests
NARCIS (Netherlands)
Peñuela-Mora, M.C.
2014-01-01
Although progress has been made in studies on white sand forests in the Amazon, there is still a considerable gap in our knowledge of the unique species composition of white sand forests and their structure and dynamics, especially in Western Amazon. This thesis aims to fill this gap by addressing t
19. Sand transportation and reverse patterns over leeward face of sand dune
Science.gov (United States)
Jiang, Hong; Dun, Hongchao; Tong, Ding; Huang, Ning
2017-04-01
Sand saltation has complex interactions with turbulent flow and dune form. Most models of wind-blown sand consider ideal circumstances such as steady wind velocity and a flat surface, and the bulk of data on wind flow and sand transport over an individual dune has focused mostly on the influence of dune shape or inter-dune space on the wind flow, neglecting the effect of morphology on sand saltation, particularly airflow and sand transportation over the leeward slope. Wind flow structures over the leeward slope of sand dunes have a fundamental influence on the organization of sand dunes. In order to understand sand dune dynamics, lee face airflow and sediment transportation should be paid more attention. Previous field observations could not measure turbulent flow structure well because of the limited observation points and the influence of experiment structure on wind field. In addition, the reverse sand particles over leeward face could not be collected by sand trap in field. Numerous field observations could not measure turbulent flow structure because of the limited observation points and the influence of experimental structures on the wind field. In addition, the reverse transport of sand particles over leeward face could not be collected by sand traps in field. Therefore, this paper aims to investigate the turbulent flow structure and sand transport pattern over the leeward slope. A numerical model of sand saltation over slope terrain is constructed, which also considers the coupling effects between air flow and sand particles. The large eddy simulation method is used to model turbulent flow. Sand transport is simulated by tracking the trajectory of each sand particle. The results show that terrain significantly alters the turbulent air flow structure and wind-blown sand movement, especially over the leeward slope. Here, mass flux increases initially and then decreases with height in the reversed flow region in the direction of wind flow, and the mass flux
20. Use of bark-derived pyrolysis oils ass a phenol substitute in structural panel adhesives
Energy Technology Data Exchange (ETDEWEB)
Louisiana Pacific Corp
2004-03-01
The main objective of this program was to pilot the world's first commercial-scale production of an acceptable phenol formaldehyde (PF) resin containing natural resin (NR) ingredients, for use as an adhesive in Oriented-Strand Board (OSB) and plywood panel products. Natural Resin products, specifically MNRP are not lignin ''fillers''. They are chemically active, natural phenolics that effectively displace significant amounts of phenol in PF resins, and which are extracted from bark-derived and wood-derived bio-oils. Other objectives included the enhancement of the economics of NR (MNRP) production by optimizing the production of certain Rapid Thermal Processing (RTP{trademark}) byproducts, particularly char and activated carbon. The options were to activate the char for use in waste-water and/or stack gas purification. The preliminary results indicate that RTP{trademark} carbon may ultimately serve as a feedstock for activated carbon synthesis, as a fuel to be used within the wood product mill, or a fuel for an electrical power generating facility. Incorporation of the char as an industrial heat source for use in mill operations was L-P's initial intention for the carbon, and was also of interest to Weyerhaeuser as they stepped into in the project.
1. Mine-detection test facilities at TNO-FEL test location "Waalsdorp"
NARCIS (Netherlands)
Rhebergen, J.B.; Zwamborn, A.P.M.
1998-01-01
As part of the TNO-FEL Ultra-Wide-Band Ground-Penetrating-Radar (UWB-GPR) project, a test facility for controlled GPR experiments was planned. Construction of this sand-box test facility has recently been completed. At the same site another test facility, for evaluating various commercial of the
2. Mine-detection test facilities at TNO-FEL test location "Waalsdorp"
NARCIS (Netherlands)
Rhebergen, J.B.; Zwamborn, A.P.M.
1998-01-01
As part of the TNO-FEL Ultra-Wide-Band Ground-Penetrating-Radar (UWB-GPR) project, a test facility for controlled GPR experiments was planned. Construction of this sand-box test facility has recently been completed. At the same site another test facility, for evaluating various commercial of the she
3. Choosing an optimum sand control method
Directory of Open Access Journals (Sweden)
Ehsan Khamehchi
2015-06-01
Full Text Available Formation sand control is always one of the main concerns of production engineers. There are some different methods to prevent sand production. Choosing a method for preventing formation sand production depends on different reservoir parameters and politic and economic conditions. Sometimes, economic and politic conditions are more effective to choose an optimum than reservoir parameters. Often, simultaneous investigation of politic and economic conditions with reservoir parameters has different results with what is expected. So, choosing the best sand control method is the result of thorough study. Global oil price, duration of sand control project and costs of necessary equipment for each method as economic and politic conditions and well productivity index as reservoir parameter are the main parameters studied in this paper.
4. Altitude of the top of the Sparta Sand and Memphis Sand in three areas of Arkansas
Science.gov (United States)
Pugh, Aaron L.; Westerfield, Paul W.; Gonthier, Gerard; Poynter, David T.
1998-01-01
The Sparta Sand and Memphis Sand form the second most productive aquifer in Arkansas. The Sparta Sand and Memphis Sand range in thick- ness from 0 to 900 feet, consisting of fine- to medium-grained sands interbedded with layers of silt, clay, shale, and minor amounts of lignite. Within the three areas of interest, the top surface of the Sparta Sand and Memphis Sand dips regionally east and southeast towards the axis of the Mississippi Embayment syncline and Desha Basin. Local variations in the top surface may be attributed to a combination of continued development of structural features, differential compaction, localized faulting, and erosion of the surface prior to subsequent inundation and deposition of younger sediments.
5. Sand Failure Mechanism and Sanding Parameters in Niger Delta Oil Reservoirs
Directory of Open Access Journals (Sweden)
Sunday Isehunwa,
2010-05-01
Full Text Available Sand production is a major issue during oil and gas production from unconsolidated reservoirs. In predicting the onset of sand production, it is important to accurately determine the failure mechanism and the contributing parameters. The aim of this study was to determine sand failure mechanism in the Niger-Delta, identify themajor contributing parameters and evaluate their effects on sanding.Completion and production data from 78 strings completed on 22 reservoirs in a Niger Delta oil Field were evaluated. Sand failure mechanisms and contributing parameters were identified and compared with published profiles. The results showed that cohesive stress is the predominant sand failure mechanism. Water cut, bean size and gas oil ratio (GOR impact sand production in the Niger Delta.
6. STUDIES ON SOME PHYSICOCHEMICAL PROPERTIES OF LEUCAENA LEUCOCEPHALA BARK GUM
Directory of Open Access Journals (Sweden)
Vijetha Pendyala
2010-06-01
Full Text Available Gum exudates from Leucaena Leucocephala (Family: Fabaceae plants grown all over India were investigated for its physicochemical properties such as pH, swelling capacity and viscosities at different temperatures using standard methods. Leucaena Leucocephala bark gum appeared to be colorless to reddish brown translucent tears. 5 % w/v mucilage has pH of 7.5 at 28°C. The gum is slightly soluble in water and practically insoluble in ethanol, acetone and chloroform. It swells to about 5 times its original weight in water. A 5 %w/v mucilage concentration gave a viscosity value which was unaffected at temperature ranges (28-40°C. At concentrations of 2 and 5 %w/v, the gum exhibited pseudo plastic flow pattern while at 10 %w/v concentration the flow behaviour was thixotropic. The results indicate that the swelling ability of Leucaena Leucocephala (LL bark gum may provide potentials for its use as a disintegrant in tablet formulation, as a hydro gel in modified release dosage forms and the rheological flow properties may also provide potentials for its use as suspending and emulsifying agents owing to its pseudo plastic and thixotropic flow patterns.
7. IN VITRO ANTIINFLAMMATORY ACTIVITY OF FICUS BENGHALENSIS BARK
Directory of Open Access Journals (Sweden)
Matpal Mahesh
2013-07-01
Full Text Available To evaluate the anti-inflammatory property of the different extract of bark of Ficus benghalensis, family Moraceae is a very large, fast growing, evergreen tree up to 30 meters, with spreading branches and many aerial roots. Leaves stalked, ovate-cordate, 3-nerved, entire, when young downy on both sides; petiole with a broad smooth greasy gland at the apex, compressed, downy; Fruit in axillary pairs, the size of a cherry, round and downy. According to Ayurveda, it is astringent to bowels; useful in treatment of biliousness, ulcers, erysipelas, vomiting, vaginal complains, fever, inflammations, leprosy. According to Unani system of medicine, its latex is aphrodisiac, tonic, vulernary, maturant, lessens inflammations; useful in piles etc. The present study aimed at the evaluation of anti-inflammatory property of the aqueous, chloroform and alcoholic extracts of the bark by in vitro methods. In vitro method was estimated by human red blood cell membrane stabilization (HRBC method. Results showed significant anti-inflammatory property of the different extracts tested. The methanolic extract at a concentration of 200 mg/ml. showed potent activity on comparing with the standard drug diclofenac sodium.
8. Biological factors contributing to bark and ambrosia beetle species diversification.
Science.gov (United States)
Gohli, Jostein; Kirkendall, Lawrence R; Smith, Sarah M; Cognato, Anthony I; Hulcr, Jiri; Jordal, Bjarte H
2017-05-01
The study of species diversification can identify the processes that shape patterns of species richness across the tree of life. Here, we perform comparative analyses of species diversification using a large dataset of bark beetles. Three examined covariates-permanent inbreeding (sibling mating), fungus farming, and major host type-represent a range of factors that may be important for speciation. We studied the association of these covariates with species diversification while controlling for evolutionary lag on adaptation. All three covariates were significantly associated with diversification, but fungus farming showed conflicting patterns between different analyses. Genera that exhibited interspecific variation in host type had higher rates of species diversification, which may suggest that host switching is a driver of species diversification or that certain host types or forest compositions facilitate colonization and thus allopatric speciation. Because permanent inbreeding is thought to facilitate dispersal, the positive association between permanent inbreeding and diversification rates suggests that dispersal ability may contribute to species richness. Bark beetles are ecologically unique; however, our results indicate that their impressive species diversity is largely driven by mechanisms shown to be important for many organism groups. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.
9. Polysaccharides with immunomodulating properties from the bark of Parkia biglobosa.
Science.gov (United States)
Zou, Yuan-Feng; Zhang, Bing-Zhao; Inngjerdingen, Kari Tvete; Barsett, Hilde; Diallo, Drissa; Michaelsen, Terje Einar; El-Zoubair, Elnour; Paulsen, Berit Smestad
2014-01-30
The bark of Parkia biglobosa is used in traditional medicine to cure a wide range of illnesses. Polysaccharides were extracted from the bark with 50% ethanol-water, 50°C and 100°C water, and seven active fractions obtained by anion exchange chromatography and gel filtration. The complement fixation and macrophage stimulating activities of the different fractions were determined. The acidic fractions PBEII-I and PBEII-IV were the most active in the complement fixation assay, but the other fractions were also potent compared to the positive control BPII from Biophytum petersianum. Fractions PBEII-I and PBEII-IV were also the most potent fractions in stimulating macrophages to release nitric oxide. Structural studies showed that PBEII-I and PBEII-IV were pectic type polysaccharides, containing arabinogalactan type II structures. The observed differences in biological activities among the seven purified polysaccharide sub-fractions are probably due to differences in monosaccharide compositions, linkage types and molecular sizes.
10. Synthesis of silver nanoparticles using medicinal Zizyphus xylopyrus bark extract
Science.gov (United States)
Sumi Maria, Babu; Devadiga, Aishwarya; Shetty Kodialbail, Vidya; Saidutta, M. B.
2015-08-01
In the present paper, biosynthesis of silver nanoparticles using Zizyphus xylopyrus bark extract is reported. Z. xylopyrus bark extract is efficiently used for the biosynthesis of silver nanoparticles. UV-Visible spectroscopy showed surface plasmon resonance peaks in the range 413-420 nm confirming the formation of silver nanoparticles. Different factors affecting the synthesis of silver nanoparticles like methodology for the preparation of extract, concentration of silver nitrate solution used for biosynthesis and initial pH of the reaction mixture were studied. The extract prepared with 10 mM AgNO3 solution by reflux extraction method at optimum initial pH of 11, resulted in higher conversion of silver ions to silver nanoparticles as compared with those prepared by open heating or ultrasonication. SEM analysis showed that the biosynthesized nanoparticles are spherical in nature and ranged from 60 to 70 nm in size. EDX suggested that the silver nanoparticles must be capped by the organic components present in the plant extract. This simple process for the biosynthesis of silver nanoparticles using aqueous extract of Z. xylopyrus is a green technology without the usage of hazardous and toxic solvents and chemicals and hence is environment friendly. The process has several advantages with reference to cost, compatibility for its application in medical and drug delivery, as well as for large-scale commercial production.
11. Bacterial and fungal symbionts of parasitic Dendroctonus bark beetles.
Science.gov (United States)
Dohet, Loïc; Grégoire, Jean-Claude; Berasategui, Aileen; Kaltenpoth, Martin; Biedermann, Peter H W
2016-09-01
Bark beetles (Curculionidae: Scolytinae) are one of the most species-rich herbivorous insect groups with many shifts in ecology and host-plant use, which may be mediated by their bacterial and fungal symbionts. While symbionts are well studied in economically important, tree-killing species, little is known about parasitic species whose broods develop in living trees. Here, using culture-dependent and independent methods, we provide a comprehensive overview of the associated bacteria, yeasts and filamentous fungi of the parasitic Dendroctonus micans, D. punctatus and D. valens, and compare them to those of other tree-inhabiting insects. Despite inhabiting different geographical regions and/or host trees, the three species showed similar microbial communities. Enterobacteria were the most prevalent bacteria, in particular Rahnella, Pantoea and Ewingella, in addition to Streptomyces Likewise, the yeasts Candida/Cyberlindnera were the most prominent fungi. All these microorganisms are widespread among tree-inhabiting insects with various ecologies, but their high prevalence overall might indicate a beneficial role such as detoxification of tree defenses, diet supplementation or protection against pathogens. As such, our results enable comparisons of symbiont communities of parasitic bark beetles with those of other beetles, and will contribute to our understanding of how microbial symbioses facilitate dietary shifts in insects.
12. Characterisation of polyphenols in Terminalia arjuna bark extract
Directory of Open Access Journals (Sweden)
Anumita Saha
2012-01-01
Full Text Available The bark of Terminalia arjuna is known for its heart-health benefits in ayurvedic literature. This has been further supported by in vivo studies on animal and human volunteers. But there is no detailed study on identification of the active ingredients such as polyphenols. Polyphenols possesses antioxidant properties and are well-known health actives, it is important to characterise polyphenols in Terminalia arjuna. Aqueous extract of Terminalia arjuna bark was analysed for its composition and molecular weight distribution by dialysis. Compositional analysis revealed that it has 44% polyphenols and dialysis study showed that 70% of the polyphenols have molecular weight greater than 3.5 kDa. High performance liquid chromatography and liquid chromatography-mass spectrometry analysis of Terminalia arjuna, confirmed that it contains flavon-3-ols such as (+-catechin, (+-gallocatechin and (−-epigallocatechin. Phenolic acids such as gallic acid, ellagic acid and its derivatives were also found in Terminalia arjuna extract. Ellagic acid derivatives were isolated and their spectral studies indicated that isolated compounds were 3-O-methyl-ellagic acid 4- O-β-D-xylopyranoside, ellagic acid and 3-O-methyl ellagic acid 3-O-rhamnoside. Hydrolysis and thiolysis studies of high molecular weight polyphenols indicated that they are proanthocyanidins. Given these results, it may be possible to attribute the heart-health effects of Terminalia arjuna to these polyphenols which may be responsible for the endothelial benefit functions like tea.
13. Studies on some physicochemical properties of leucaena leucocephala bark gum.
Science.gov (United States)
Pendyala, Vijetha; Baburao, Chandu; Chandrasekhar, K B
2010-04-01
Gum exudates from Leucaena Leucocephala (Family: Fabaceae) plants grown all over India were investigated for its physicochemical properties such as pH, swelling capacity and viscosities at different temperatures using standard methods. Leucaena Leucocephala bark gum appeared to be colorless to reddish brown translucent tears. 5 % w/v mucilage has pH of 7.5 at 28°C. The gum is slightly soluble in water and practically insoluble in ethanol, acetone and chloroform. It swells to about 5 times its original weight in water. A 5 %w/ v mucilage concentration gave a viscosity value which was unaffected at temperature ranges (28-40°C). At concentrations of 2 and 5 %w/v, the gum exhibited pseudo plastic flow pattern while at 10 %w/v concentration the flow behaviour was thixotropic. The results indicate that the swelling ability of Leucaena Leucocephala (LL) bark gum may provide potentials for its use as a disintegrant in tablet formulation, as a hydro gel in modified release dosage forms and the rheological flow properties may also provide potentials for its use as suspending and emulsifying agents owing to its pseudo plastic and thixotropic flow patterns.
14. Global sand trade is paving the way for a tragedy of the sand commons
Science.gov (United States)
Torres, A.; Brandt, J.; Lear, K.; Liu, J.
2016-12-01
15. Spatio-Temporal Distribution of Bark and Ambrosia Beetles in a Brazilian Tropical Dry Forest
Science.gov (United States)
de Novais, Samuel Matos Antunes; Monteiro, Graziela França; Flechtmann, Carlos Alberto Hector; de Faria, Maurício Lopes; Neves, Frederico de Siqueira
2016-01-01
Bark and the ambrosia beetles dig into host plants and live most of their lives in concealed tunnels. We assessed beetle community dynamics in tropical dry forest sites in early, intermediate, and late successional stages, evaluating the influence of resource availability and seasonal variations in guild structure. We collected a total of 763 beetles from 23 species, including 14 bark beetle species, and 9 ambrosia beetle species. Local richness of bark and ambrosia beetles was estimated at 31 species. Bark and ambrosia composition was similar over the successional stages gradient, and beta diversity among sites was primarily determined by species turnover, mainly in the bark beetle community. Bark beetle richness and abundance were higher at intermediate stages; availability of wood was the main spatial mechanism. Climate factors were effectively non-seasonal. Ambrosia beetles were not influenced by successional stages, however the increase in wood resulted in increased abundance. We found higher richness at the end of the dry and wet seasons, and abundance increased with air moisture and decreased with higher temperatures and greater rainfall. In summary, bark beetle species accumulation was higher at sites with better wood production, while the needs of fungi (host and air moisture), resulted in a favorable conditions for species accumulation of ambrosia. The overall biological pattern among guilds differed from tropical rain forests, showing patterns similar to dry forest areas. PMID:27271969
16. Influence of bark beetles outbreaks on the carbon balance of western United States forests
Science.gov (United States)
Ghimire, B.; Williams, C. A.; Collatz, G. J.; Masek, J. G.
2011-12-01
Recently bark beetle outbreaks have been increasing in western United States forests due to increases in temperatures and prolonged occurrence of droughts. Bark beetle outbreaks transfer carbon from the live photosynthesizing pools to the dead respiring pool where carbon slowly decomposes into the atmosphere causing landscapes to change from a net sink to source of carbon. Previous studies have usually been conducted at small localized areas, focused only on one or two bark beetle types or encompass a single outbreak event. The literature largely ignores the influence of bark beetle mortality on carbon balance at both local and regional scales by focusing on multiple bark beetles types and events. This study uses a combination of the Carnegie Ames Stanford Approach (CASA) carbon cycle model driven by remotely sensed biophysical observations, Forest Inventory and Analysis (FIA) derived post-disturbance biomass regeneration trajectories, and mortality rates obtained from Aerial Detection Survey (ADS) insect outbreak polygons. The synthesis of the carbon cycle based modeling approach and different data products results in characteristic carbon trajectories for Net Ecosystem Productivity (NEP), Net Primary Productivity (NPP) and heterotrophic respiration associated with insect outbreaks. This study demonstrates that bark beetle events change landscapes from a sink to source of carbon at a local scale but at a larger regional level the influence of bark beetle outbreaks are not prominent compared to other disturbance agents.
17. Banana Bark as A Part of Acoustic Design Unit by Hybrid Technology Application
Directory of Open Access Journals (Sweden)
Maharani Dian Permanasari
2014-10-01
Full Text Available Abstract. Banana bark is one of tropical indigenous natural resources that can be used as main material for many products. Being a fast-growing renewable material, it is durable and has natural patterns that people find visually attractive. Naturally, its textures and patterns are its main values; therefore it has the potential to be developed further. This research is needed to optimize the growth of small craft industries of banana bark, including the community where production activities take place, and also to provide information or reference of banana bark utilizations. Previous experiments conclude that banana bark has porous structure, high flexibility, relatively water-resistant due to its natural wax coating that resists water droplets, unless being washed down immensely. Also, due to its softwood- and paper-like properties, ithas many possibilities to be formed and processed into various functional products, mostly as craft products. In the subsequent study, the research about the utilization of banana bark in small industries starting from the harvesting system, handling problems in raw material supply, applying proper technology in improving the material’s quality, improving the human-resource working culture by appropriate technologies, and also innovating the product’s designs. The recommended designs can be implemented to improve the performance and qualities of banana bark products.Keywords: applied technology; banana bark; renewable materials; design; sustainability.
18. Black pine (Pinus nigra) barks as biomonitors of airborne mercury pollution.
Science.gov (United States)
Chiarantini, Laura; Rimondi, Valentina; Benvenuti, Marco; Beutel, Marc W; Costagliola, Pilario; Gonnelli, Cristina; Lattanzi, Pierfranco; Paolieri, Mario
2016-11-01
Tree barks are relevant interfaces between plants and the external environment, and can effectively retain airborne particles and elements at their surface. In this paper we have studied the distribution of mercury (Hg) in soils and in black pine (Pinus nigra) barks from the Mt. Amiata Hg district in southern Tuscany (Italy), where past Hg mining and present-day geothermal power plants affect local atmospheric Hg concentration, posing serious environmental concerns. Barks collected in heavily Hg-polluted areas of the district display the highest Hg concentration ever reported in literature (8.6mg/kg). In comparison, barks of the same species collected in local reference areas and near geothermal power plants show much lower (range 19-803μg/kg) concentrations; even lower concentrations are observed at a "blank" site near the city of Florence (5-98μg/kg). Results show a general decrease of Hg concentration from bark surface inwards, in accordance with a deposition of airborne Hg, with minor contribution from systemic uptake from soils. Preliminary results indicate that bark Hg concentrations are comparable with values reported for lichens in the same areas, suggesting that tree barks may represent an additional useful tool for biomonitoring of airborne Hg. Copyright © 2016 Elsevier B.V. All rights reserved.
19. Development and characterization of ice cream enriched with different formulations flour jabuticaba bark (Myrciaria cauliflora
Directory of Open Access Journals (Sweden)
Marina Leopoldina Lamounier
2015-09-01
Full Text Available The aim was to perform the physicochemical characterization of the flour from the bark of jabuticaba, as well as developing three ice cream formulations (enriched with 0, 5 and 10% of this flour and evaluate the physicochemical and sensory characteristics. Fruits were pulped, the peels were dehydrated, dried, crushed and sieved to obtain the flour that was analyzed for physicochemical levels. Then, three ice cream formulations were developed (with 0%, 5% and 10% flour from the bark of jabuticaba, considering the physicochemical and sensorial characteristics. The results showed that the flour from the bark of jabuticaba showed high ash and fiber. The ice creams showed differences (p < 0.05 for pH, titratable acidity, moisture and ash due to the incorporation of flour from the bark of jabuticaba. The only attribute that did not differ (p > 0.05 was soluble solid. The overrun was ecreasing with increasing addition of flour. In the sensory evaluation, only attributes that differ (p < 0.05 were flavor, texture and overall appearance of the formulation with 10% flour from the bark of jabuticaba, which represents that incorporation of 5% flour from the bark of jabuticaba did not affect the cceptability of ice creams. It can be concluded that the enrichment of blemish bark flour provides edible ice increase in nutritional value without affecting the sensory characteristics at the level of 5% added.
20. EURIPIDES, load tests on large driven piles in dense silica sands
Energy Technology Data Exchange (ETDEWEB)
Zuidberg, H.M.; Vergobbi, P.
1996-12-31
In 1995 an extensive load testing program was conducted on 30 inch pipe piles in dense silica sands similar to those found in the southern North Sea. A highly instrumented pile was driven at one location, extracted and redriven at a second location. A total of twelve static compression and tension load tests were performed at three penetration depths between 30 and 47 meters. Test objectives included acquiring reliable data on capacity of offshore type piles in sands which hitherto were hardly available and to understand the failure mechanisms in order to improve current foundation design. The paper describes the design of the testing program and project organization and funding. Details of the test pile and instrumentation to measure the loads in the pile and the pile-sand interaction are highlighted with an emphasis on quality of the measurements. The field-work and innovative testing facilities are also described.
1. Adsorption of dyes on Sahara desert sand.
Science.gov (United States)
Varlikli, Canan; Bekiari, Vlasoula; Kus, Mahmut; Boduroglu, Numan; Oner, Ilker; Lianos, Panagiotis; Lyberatos, Gerasimos; Icli, Siddik
2009-10-15
Sahara desert sand (SaDeS) was employed as a mineral sorbent for retaining organic dyes from aqueous solutions. Natural sand has demonstrated a strong affinity for organic dyes but significantly lost its adsorption capacity when it was washed with water. Therefore, characterization of both natural and water washed sand was performed by XRD, BET, SEM and FTIR techniques. It was found that water-soluble kyanite, which is detected in natural sand, is the dominant factor affecting adsorbance of cationic dyes. The sand adsorbs over 75% of cationic dyes but less than 21% for anionic ones. Among the dyes studied, Methylene Blue (MB) demonstrated the strongest affinity for Sahara desert sand (Q(e)=11.98 mg/g, for initial dye solution concentration 3.5 x 10(-5)mol/L). The effects of initial dye concentration, the amount of the adsorbent, the temperature and the pH of the solution on adsorption capacity were tested by using Methylene Blue as model dye. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were applied. It was concluded that adsorption of Methylene Blue on Sahara desert sand followed pseudo-second order kinetics. Gibbs free energy, enthalpy change and entropy change were calculated and found -6411 J/mol, -30360 J/mol and -76.58 J/mol K, respectively. These values indicate that the adsorption is an exothermic process and has a spontaneous nature at low temperatures.
2. Critical state of sand matrix soils.
Science.gov (United States)
Marto, Aminaton; Tan, Choy Soon; Makhtar, Ahmad Mahir; Kung Leong, Tiong
2014-01-01
The Critical State Soil Mechanic (CSSM) is a globally recognised framework while the critical states for sand and clay are both well established. Nevertheless, the development of the critical state of sand matrix soils is lacking. This paper discusses the development of critical state lines and corresponding critical state parameters for the investigated material, sand matrix soils using sand-kaolin mixtures. The output of this paper can be used as an interpretation framework for the research on liquefaction susceptibility of sand matrix soils in the future. The strain controlled triaxial test apparatus was used to provide the monotonic loading onto the reconstituted soil specimens. All tested soils were subjected to isotropic consolidation and sheared under undrained condition until critical state was ascertain. Based on the results of 32 test specimens, the critical state lines for eight different sand matrix soils were developed together with the corresponding values of critical state parameters, M, λ, and Γ. The range of the value of M, λ, and Γ is 0.803-0.998, 0.144-0.248, and 1.727-2.279, respectively. These values are comparable to the critical state parameters of river sand and kaolin clay. However, the relationship between fines percentages and these critical state parameters is too scattered to be correlated.
3. Sand Flies and Their Control Methods.
Science.gov (United States)
Çetin, Hüseyin; Özbel, Yusuf
2017-06-01
The main aim of managing arthropod vectors that carry the disease agents is interrupting the infection cycle. Therefore, the management of the disease implies that all precautions related to all elements (i.e., human, arthropod vector, and reservoir) in the infection cycle need to be taken. There are important points that need to be considered while dealing with sand flies (Diptera: Psychodidae: Phlebotominae), which in many regions worldwide, particularly in tropical and subtropical areas, are vectors of diseases such as leishmaniasis and sand fly fever and are the arthropods of the infection cycle. Because the larval control of the sand flies is very difficult and almost impossible, the management is mainly conducted for the adults. The most effective strategy for reducing both sand fly fever and leishmaniasis is managing sand flies, particularly in areas where humans are located. In this review, the morphology, biology, and taxonomy of sand flies; the integrated fighting and management methods such as insecticide-impregnated bed nets and use of curtains, zooprophylaxis, indoor and outdoor residual applications, larvicides, repellents, and insecticide-impregnated dog collars; and data regarding many issues such as insecticide resistance in sand flies have been emphasized on in the review.
4. Critical State of Sand Matrix Soils
Directory of Open Access Journals (Sweden)
Aminaton Marto
2014-01-01
Full Text Available The Critical State Soil Mechanic (CSSM is a globally recognised framework while the critical states for sand and clay are both well established. Nevertheless, the development of the critical state of sand matrix soils is lacking. This paper discusses the development of critical state lines and corresponding critical state parameters for the investigated material, sand matrix soils using sand-kaolin mixtures. The output of this paper can be used as an interpretation framework for the research on liquefaction susceptibility of sand matrix soils in the future. The strain controlled triaxial test apparatus was used to provide the monotonic loading onto the reconstituted soil specimens. All tested soils were subjected to isotropic consolidation and sheared under undrained condition until critical state was ascertain. Based on the results of 32 test specimens, the critical state lines for eight different sand matrix soils were developed together with the corresponding values of critical state parameters, M, λ, and Γ. The range of the value of M, λ, and Γ is 0.803–0.998, 0.144–0.248, and 1.727–2.279, respectively. These values are comparable to the critical state parameters of river sand and kaolin clay. However, the relationship between fines percentages and these critical state parameters is too scattered to be correlated.
5. Cork oak vulnerability to fire: the role of bark harvesting, tree characteristics and abiotic factors.
Directory of Open Access Journals (Sweden)
Filipe X Catry
Full Text Available Forest ecosystems where periodical tree bark harvesting is a major economic activity may be particularly vulnerable to disturbances such as fire, since debarking usually reduces tree vigour and protection against external agents. In this paper we asked how cork oak Quercus suber trees respond after wildfires and, in particular, how bark harvesting affects post-fire tree survival and resprouting. We gathered data from 22 wildfires (4585 trees that occurred in three southern European countries (Portugal, Spain and France, covering a wide range of conditions characteristic of Q. suber ecosystems. Post-fire tree responses (tree mortality, stem mortality and crown resprouting were examined in relation to management and ecological factors using generalized linear mixed-effects models. Results showed that bark thickness and bark harvesting are major factors affecting resistance of Q. suber to fire. Fire vulnerability was higher for trees with thin bark (young or recently debarked individuals and decreased with increasing bark thickness until cork was 3-4 cm thick. This bark thickness corresponds to the moment when exploited trees are debarked again, meaning that exploited trees are vulnerable to fire during a longer period. Exploited trees were also more likely to be top-killed than unexploited trees, even for the same bark thickness. Additionally, vulnerability to fire increased with burn severity and with tree diameter, and was higher in trees burned in early summer or located in drier south-facing aspects. We provided tree response models useful to help estimating the impact of fire and to support management decisions. The results suggested that an appropriate management of surface fuels and changes in the bark harvesting regime (e.g. debarking coexisting trees in different years or increasing the harvesting cycle would decrease vulnerability to fire and contribute to the conservation of cork oak ecosystems.
6. Cork oak vulnerability to fire: the role of bark harvesting, tree characteristics and abiotic factors.
Science.gov (United States)
Catry, Filipe X; Moreira, Francisco; Pausas, Juli G; Fernandes, Paulo M; Rego, Francisco; Cardillo, Enrique; Curt, Thomas
2012-01-01
Forest ecosystems where periodical tree bark harvesting is a major economic activity may be particularly vulnerable to disturbances such as fire, since debarking usually reduces tree vigour and protection against external agents. In this paper we asked how cork oak Quercus suber trees respond after wildfires and, in particular, how bark harvesting affects post-fire tree survival and resprouting. We gathered data from 22 wildfires (4585 trees) that occurred in three southern European countries (Portugal, Spain and France), covering a wide range of conditions characteristic of Q. suber ecosystems. Post-fire tree responses (tree mortality, stem mortality and crown resprouting) were examined in relation to management and ecological factors using generalized linear mixed-effects models. Results showed that bark thickness and bark harvesting are major factors affecting resistance of Q. suber to fire. Fire vulnerability was higher for trees with thin bark (young or recently debarked individuals) and decreased with increasing bark thickness until cork was 3-4 cm thick. This bark thickness corresponds to the moment when exploited trees are debarked again, meaning that exploited trees are vulnerable to fire during a longer period. Exploited trees were also more likely to be top-killed than unexploited trees, even for the same bark thickness. Additionally, vulnerability to fire increased with burn severity and with tree diameter, and was higher in trees burned in early summer or located in drier south-facing aspects. We provided tree response models useful to help estimating the impact of fire and to support management decisions. The results suggested that an appropriate management of surface fuels and changes in the bark harvesting regime (e.g. debarking coexisting trees in different years or increasing the harvesting cycle) would decrease vulnerability to fire and contribute to the conservation of cork oak ecosystems.
7. Invasive plants on disturbed Korean sand dunes
Science.gov (United States)
Kim, Kee Dae
2005-01-01
The sand dunes in coastal regions of South Korea are important ecosystems because of their small size, the rare species found in this habitat, and the beautiful landscapes they create. This study investigated the current vegetative status of sand dunes on three representative coasts of the Korean peninsula, and on the coasts of Cheju Island, and assessed the conditions caused by invasive plants. The relationships between the degree of invasion and 14 environmental variables were studied. Plots of sand dunes along line transects perpendicular to the coastal lines were established to estimate vegetative species coverage. TWINSPAN (Two-Way Indicator Species Analysis), CCA (Canonical Correspondence Analysis), and DCCA (Detrended Canonical Correspondence Analysis) were performed to classify communities on sand dunes and assess species composition variation. Carex kobomugi, Elymus mollis, and Vitex rotundifolia were found to be the dominant species plotted on the east, the west, and the peripheral coasts of Cheju Island, respectively. Vegetation on the south coast was totally extinct. The 19 communities, including representative C. kobomugi, C. kobomugi- Ixeris repens, C. kobomugi- Oenothera biennis, E. mollis, Lolium multiflorum- Calystegia soldanella, and V. rotundifolia- C. kobomugi, were all classified according to TWINSPAN. Oenothera biennis and L. multiflorum were exotics observed within these native communities. CCA showed that invasive native and exotic species distribution was segregated significantly, according to disturbance level, exotic species number, gravel, sand and silt contents, as well as vegetation size. It further revealed that human disturbance can strongly favor the settlement of invasive and exotic species. Restoration options to reduce exotic plants in the South Korean sand dune areas were found to be the introduction of native plant species from one sand dune into other sand dune areas, prohibition of building and the introduction of exotic
8. Formation mechanism of cracks in saturated sand
Institute of Scientific and Technical Information of China (English)
Xiaobing Lu; Zhemin Zheng; Yongren Wu
2006-01-01
The formation mechanism of "water film" (or crack) in saturated sand is analyzed theoretically and numerically.The theoretical analysis shows that there will be no stable "water film" in the saturated sand if the strength of the skeleton is zero and no positions are choked.It is shown by numerical simulation that stable water films initiate and grow if the choking state keeps unchanged once the fluid velocities decrease to zero in the liquefied sand column.The developments of "water film" based on the model presented in this paper are compared with experimental results.
9. Lund Sand No 0:part 2
OpenAIRE
Ibsen, Lars Bo; Jakobsen, Finn Rosendal
1996-01-01
During the last 15 years the Geotechnical Engineering Group (GEG) at Aalborg University has performed triaxial tests with a sand called Lund No 0. Lund No 0 is a graded sand from a gravel pit near Horsens in Denmark. For the classification of the sand the following tests have been performed: Sieve test, Grain density, ds, Maximum, emax, and minimum, emin, void ratio. The strength parameters of Lund No 0 are detennined by some drained and undrained triaxial tests in the Danish Triaxial Cell. T...
10. Lund Sand No 0:part 1
OpenAIRE
Ibsen, Lars Bo; Jakobsen, Finn Rosendal
1996-01-01
During the last 15 years the Geotechnical Engineering Group (GEG) at Aalborg University has performed triaxial tests with a sand called Lund No 0. Lund No 0 is a graded sand from a gravel pit near Horsens in Denmark. For the classification of the sand the following tests have been performed: Sieve test, Grain density, ds, Maximum, emax, and minimum, emin, void ratio. The strength parameters of Lund No 0 are detennined by some drained and undrained triaxial tests in the Danish Triaxial Cell. T...
11. Biodegradable materials as foundry moulding sands binders
Directory of Open Access Journals (Sweden)
K. Major - Gabryś
2015-07-01
Full Text Available The aim of this article is to show the possibility of using biodegradable materials as part of the composition of foundry moulding and core sand binders. Research shows that moulding sands with biodegradable materials selected as binders are not only less toxic but are also better suited to mechanical reclamation than moulding sands with phenol-furfuryl resin. The use of biodegradable materials as additives to typical synthetic resins can result in their decreased toxicity and improved ability to reclamation as well as in accelerated biodegradation of binding material leftovers of mechanical reclamation.
12. Isolation and Characterization of the Chemical Constituents of Anacardium occidentale Cracked Bark
Directory of Open Access Journals (Sweden)
2015-06-01
Full Text Available The cracked bark of Anacardium occidentale were dried under ambient conditions, chopped into bits and the ethanolic extract of the cracked bark was obtained by cold extraction. Phytochemical screening was conducted to identify the types of secondary metabolites present using standard procedures. The profiles of the chemical constituents present were established using Thin Layer and Column Chromatography methods. Thus, pure chemical constituents were isolated from the cracked bark of Anacardium occidentale. The isolated compounds were characterized using FT-IR and their structures determined using data obtained from GC-MS spectrum.
13. Energy capacity of black wattle wood and bark in different spacing plantations
Directory of Open Access Journals (Sweden)
Elder Eloy
2015-06-01
Full Text Available The study aimed at the energetic description of wood and bark biomass of Acacia mearnsii De Wild. in two spacing plantations: 2.0 m × 3.0 m × 1.0 m and 1.5 m, during 36 months after the planting. The experiment was conducted in the municipality of Frederico Westphalen, state of Rio Grande do Sul, Brazil. Biomass (BIO, calorific value, basic density, ash content, volatile matter and fixed carbon content and energy density (ED of wood and bark were determined. The smallest spacing plantation presented the highest production per unit area of BIO and ED of wood and bark.
14. Assessment of Alder Tree Bark Potential as a Renewable Source of Proanthocyanidins in Latvia
Directory of Open Access Journals (Sweden)
Janceva Sarmīte
2016-05-01
Full Text Available With the purpose to assess potential of alder tree bark as a renewable source of bioactive polyphenolic compounds, antioxidant properties of hydrophilic extracts and proanthocyanidins (PAC isolated from bark of two alder species (grey alder and black alder growing in Latvia have been examined employing two test systems, ABTS●+, DPPH● assays. In the tests the high free radical scavenging capacities of the PAC were demonstrated. The polyphenolic nature of the bark PAC opens the possibility of its application as food additive. The PAC has good potential as an antioxidant for mayonnaise.
15. Watching Faults Grow in Sand
Science.gov (United States)
Cooke, M. L.
2015-12-01
Accretionary sandbox experiments provide a rich environment for investigating the processes of fault development. These experiments engage students because 1) they enable direct observation of fault growth, which is impossible in the crust (type 1 physical model), 2) they are not only representational but can also be manipulated (type 2 physical model), 3) they can be used to test hypotheses (type 3 physical model) and 4) they resemble experiments performed by structural geology researchers around the world. The structural geology courses at UMass Amherst utilize a series of accretionary sandboxes experiments where students first watch a video of an experiment and then perform a group experiment. The experiments motivate discussions of what conditions they would change and what outcomes they would expect from these changes; hypothesis development. These discussions inevitably lead to calculations of the scaling relationships between model and crustal fault growth and provide insight into the crustal processes represented within the dry sand. Sketching of the experiments has been shown to be a very effective assessment method as the students reveal which features they are analyzing. Another approach used at UMass is to set up a forensic experiment. The experiment is set up with spatially varying basal friction before the meeting and students must figure out what the basal conditions are through the experiment. This experiment leads to discussions of equilibrium and force balance within the accretionary wedge. Displacement fields can be captured throughout the experiment using inexpensive digital image correlation techniques to foster quantitative analysis of the experiments.
16. Effect of Chromite-Silica Sands Characteristics on Performance of Ladle Filler Sands for Continuous Casting
Institute of Scientific and Technical Information of China (English)
2012-01-01
Free opening rate is mainly determined by the performance of the ladle filler sand. High free opening rates of ladles are required in steel making to improve steel quality. Chromite ladle filler sands are one of the most widely used ladle filler sand. Several operative variables and materials characteristics affect the performance of the sands. Three sets of chromite ladle filler sands were selected and researches were focused on the sintering hehaviour and per- formance of the sands under operative conditions. The effect of particle size distribution on sintering, microstruc- ture, flowability, and permeability were presented. In all cases, the particle size varies from 0.1 to 1.5 mm corre- sponding to free flowing powders. One of the samples has higher permeability factor in comparison with others due to low particle size distribution. The other sample presents very good free opening due to its very good flowability and permeability factor.
17. Mammography Facilities
Data.gov (United States)
U.S. Department of Health & Human Services — The Mammography Facility Database is updated periodically based on information received from the four FDA-approved accreditation bodies: the American College of...
18. Health Facilities
Science.gov (United States)
Health facilities are places that provide health care. They include hospitals, clinics, outpatient care centers, and specialized care centers, such as birthing centers and psychiatric care centers. When you ...
19. Canyon Facilities
Data.gov (United States)
Federal Laboratory Consortium — B Plant, T Plant, U Plant, PUREX, and REDOX (see their links) are the five facilities at Hanford where the original objective was plutonium removal from the uranium...
20. A new coumarin from stem bark of Mesua hexapetala.
Science.gov (United States)
Karunakaran, Thiruventhan; Ee, Gwendoline Cheng Lian; Teh, Soek Sin; Daud, Shaari; Mah, Siau Hui; Lim, Chan Kiang; Jong, Vivien Yi Mian; Awang, Khalijah
2016-07-01
A new alkylated coumarin derivative, hexapetarin (1) along with three other xanthones, trapezifolixanthone (2), cudraxanthone G (3) and 1,3,7-trihydroxy-2,4-di (3-methyl-2-butenyl)xanthone (4), and four common triterpenoids, friedelin (5), stigmasterol (6), beta-sitosterol (7) and gamma-sitosterol (8) were isolated from the stem bark of Mesua hexapetala (Clusiaceae), a plant, native to Malaysia. The structures of these compounds were elucidated and determined using spectroscopic techniques such as NMR and MS. Anti-inflammatory activity assay indicated hexapetarin (1) to possess moderate anti-inflammatory activity, while 1,3,7-trihydroxy-2,4-di (3-methyl-2-butenyl)xanthone (4) gave very good activity.
1. TANNIN CONTENT DETERMINATION IN THE BARK OF Eucalyptus spp
Directory of Open Access Journals (Sweden)
Paulo Fernando Trugilho
2003-07-01
Full Text Available The objective of this study was to determine the tannin contents in the bark oftwenty-five species of Eucalyptus through two extraction methods, one using hot water andthe other a sequence of toluene and ethanol. The results showed that the extraction methodspresented significant differences in the tannin contents. The method using the sequencetoluene and ethanol, for most of the species, promoted a larger extraction of tannin. The hotwater method presented higher contents of tannin for Eucalyptus cloeziana (40,31%,Eucalyptus melanophoia (20,49% and Eucalyptus paniculata (16,03%. In the toluene andethanol method the species with higher tannin content was Eucalyptus cloeziana (31,00%,Eucalyptus tereticornis (22,83% and Eucalyptus paniculata (17,64%. The Eucalyptuscloeziana presented great potential as commercial source of tannin, independent of theextraction method considered.
2. Condensed tannins from the bark of Guazuma ulmifolia Lam. (Sterculiaceae)
Energy Technology Data Exchange (ETDEWEB)
Lopes, Gisely C.; Rocha, Juliana C.B.; Mello, Joao C.P. de [Universidade Estadual de Maringa (UEM), PR (Brazil). Programa de Pos-graduacao em Ciencias Farmaceuticas], e-mail: [email protected]; Almeida, Glalber C. de [Universidade Estadual de Maringa (UEM), PR (Brazil)
2009-07-01
From the bark of Guazuma ulmifolia Lam. (Sterculiaceae), nine compounds were isolated and identified: ent-catechin, epicatechin, ent-gallocatechin, epigallocatechin, epiafzelechin-(4{beta}?8)-epicatechin, epicatechin-(4{beta}?8)-catechin (procyanidin B1), epicatechin-(4{beta}?8)-epicatechin (procyanidin B2), epicatechin-(4{beta}?8)-epigallocatechin, and the new compound 4'-O-methyl-epiafzelechin. Their structures were elucidated on the basis of spectral and literature data. HPLC fingerprint analysis of the semipurified extract was performed on a C18 column, with a mixture of acetonitrile (0.05% trifluoroacetic acid):water (0.05% trifluoroacetic acid) (v/v) with a flow rate of 0.8 mL min-1. The sample injection volume was 100 {mu}L and the wavelength was 210 nm. (author)
3. Cytototoxic constituents from the bark of Chisocheton cumingianus (Meliaceae).
Science.gov (United States)
Katja, Dewa Gede; Farabi, Kindi; Nurlelasari; Harneti, Desi; Mayanti, Tri; Supratman, Unang; Awang, Khalijah; Hayashi, Hideo
2017-02-01
A new lanostane-type triterpenoid, 3β-hydroxy-25-ethyl-lanost-9(11),24(24')-diene (1), along with 3β-hydroxy-lanost-7-ene (2) and β-sitosterol-3-O-acetate (3) was isolated from the stem bark of C. cumingianus. The chemical structure of the new compound was elucidated on the basis of spectroscopic data. All of the compounds were evaluated for their cytotoxic effects against P-388 murine leukemia cells. Compounds 1-3 showed cytotoxicity against P-388 murine leukemia cells with IC50 values of 28.8 ± 0.10, 4.29 ± 0.03, and 100.18 ± 0.16 μg/ml, respectively.
4. Triterpene benzoates from the bark of Picramnia teapensis (Simaroubaceae
Directory of Open Access Journals (Sweden)
Rodríguez-Gamboa Tatiana
2001-01-01
Full Text Available Two new benzoic acid esters of triterpene alcohols [lup-20(29-en-28-oic acid 3alpha,7beta-dibenzoate and 3alpha-hydroxy-lup-20(29-en-28-oic acid 7beta-benzoate] were isolated from the stem bark of Picramnia teapensis Tul. The structures of these compounds were established on the basis of spectral analyses. Other known compounds, beta-sitosterol, estigmasterol, lupeol and epilupeol, were identified in mixture by GC-MS. The triterpene esters have not shown in-vitro inhibitory effect on the growth of Leucoagaricus gongylophorus (Fisher, referred also as Leucocoprinus gongylophorus (Heim, syn Rozites gongylophora (Möller, the symbiotic fungus cultivated by the leaf-cutting ant Atta sexdens L.
5. Groundwater Flow and Salt Transport at a Sand Tailings Dam: Field Observations and Modelling Results.
Science.gov (United States)
Price, A. C.; Mendoza, C. A.
2004-05-01
Large volumes of sand tailings are produced during the extraction of bitumen from the oil sands of Northeastern Alberta. The long-term groundwater response and subsequent movement of water and solutes within the large permeable sand tailings storage areas is uncertain. At the Southwest Sand Storage (SWSS) Facility, located at Syncrude's Mildred Lake operations near Ft. McMurray, there is concern that salts from the tailings water may discharge to newly placed reclamation material that covers the sand tailings. This saline discharge water could destroy the reclamation soil structure and negatively impact vegetation. The steady-state groundwater flow and transient movement of salts at the local (bench and slope) and intermediate (pile) scales in the SWSS are investigated. Water levels, seepage and groundwater quality (including TDS) have been measured for over a year along two transects of piezometers installed in the SWSS. The field data have been used to complete traditional hydrogeological interpretations of the site, and to develop a conceptual model of flow and transport. The local and intermediate flow systems and salt transport in the dam are being evaluated with numerical models. The models will allow possible future hydrogeological behaviour of the structure to be tested. Preliminary results show differences in flow systems and salinity distribution that depend on the deposition of the SWSS. This research will facilitate better long-term environmental management of this and similar sites.
6. Sand Lake WMD vegetation mapping project update
Data.gov (United States)
US Fish and Wildlife Service, Department of the Interior — Final report on the vegetation mapping project at Sand Lake Wetland Management District. This project is being completed by the use of SPRING software and ground...
7. Bioaugmentation of flow-through sand filters
DEFF Research Database (Denmark)
Samuelsen, Elin Djurhuus
Global applications of pesticides in agricultural production have led to the detection of trace amounts of pesticides in groundwater resources in levels exceeding the EU threshold limit for drinking water of 0.1 µg L-1. Pesticide-polluted groundwater may be remediated by inoculating waterworks sand...... for degradation performances in flow-through sand columns, with the aim of identifying a suitable inoculant strain for future environmental applications. Another aim was to identify a suitable genetic marker to monitor phenoxy acid degradation in strain Sphingobium sp. PM2. We were not able to link motility...... and biofilm formation to the strains´ ability to adhere to sand. Nevertheless, a correlation was found between cell surface hydrophobicity and adhesion and overall degradation performances in flow-through sand columns. We identified S phingobium sp. PM2 as a promising inoculant strain, displaying efficient...
8. Petrophysical Analysis of Oil Sand in Athabasca
Science.gov (United States)
cheong, S.; Lee, H.
2013-12-01
Oil sands are the major unconventional energy sources which have great reserves in Alberta, Canada. Recovery techniques such as CSS (Cyclic Steam Stimulation) and SAGD (Steam Assisted Gravity Drainage) enabled to develop deeper bitumen about several hundred meter depth. Before applying CSS and SAGD, reservoir heterogeneity of mud barriers or shale breccias should be clarified to establish injection and production wells successfully. We conducted the integrated petro-physical analysis for oil sands deposits in Athabasca by correlating well logs with seismic data. From 33 well logs and 3D seismic, we have made P-wave impedance by recursive inversion. Target formations of our analysis were the top of Wabiskaw member. Using inverted impedance and multi-attributes, porosity volume was derived at a target depth. Porosity of time slice 375 ms ranged 20 ~ 40 % stretching porous sand body from NE to SW direction. Characteristics of porosity distribution may be useful to design optimum oil sands recovery in Athabasca.
9. Carbon cycle: New pathways in the sand
Science.gov (United States)
Rao, Alexandra
2017-01-01
Organic carbon decomposition in anoxic marine sediments was thought to be dominated by bacteria, but experimental data and microbial culture studies now show that microalgae buried in coastal sands may also play an important role in carbon turnover.
10. Quantitative analysis of flavanones and chalcones from willow bark.
Science.gov (United States)
Freischmidt, A; Untergehrer, M; Ziegler, J; Knuth, S; Okpanyi, S; Müller, J; Kelber, O; Weiser, D; Jürgenliemk, G
2015-09-01
Willow bark extracts are used for the treatment of fever, pain and inflammation. Recent clinical and pharmacological research revealed that not only the salicylic alcohol derivatives, but also the polyphenols significantly contribute to these effects. Quantitative analysis of the European Pharmacopoeia still focuses on the determination of the salicylic alcohol derivatives. The objective of the present study was the development of an effective quantification method for the determination of as many flavanone and chalcone glycosides as possible in Salix purpurea and other Salix species as well as commercial preparations thereof. As Salix species contain a diverse spectrum of the glycosidated flavanones naringenin, eriodictyol, and the chalcone chalconaringenin, a subsequent acidic and enzymatic hydrolysis was developed to yield naringenin and eriodictyol as aglycones, which were quantified by HPLC. The 5-O-glucosides were cleaved with 11.5% TFA before subsequent hydrolysis of the 7-O-glucosides with an almond β-glucosidase at pH 6-7. The method was validated with regard to LOD, LOQ, intraday and interday precision, accuracy, stability, recovery, time of hydrolysis, robustness and applicability to extracts. All 5-O- and 7-O-glucosides of naringenin, eriodictyol and chalconaringenin were completely hydrolysed and converted to naringenin and eriodictyol. The LOD of the HPLC method was 0.77 μM of naringenin and 0.45 μM of eriodictyol. The LOQ was 2.34 μM of naringenin and 1.35 μM for eriodictyol. The method is robust with regard to sample weight, but susceptible concerning enzyme deterioration. The developed method is applicable to the determination of flavanone and chalcone glycosides in willow bark and corresponding preparations.
11. Anti-inflammatory and antioxidant effects of Croton celtidifolius bark.
Science.gov (United States)
Nardi, G M; Felippi, R; DalBó, S; Siqueira-Junior, J M; Arruda, D C; Delle Monache, F; Timbola, A K; Pizzolatti, M G; Ckless, K; Ribeiro-do-valle, R M
2003-03-01
Croton celtidifolius Baill commonly known as "sangue-de-adave" is a tree found in the Atlantic Forest of south of Brazil, mainly in Santa Catarina. The bark and leaf infusions of this medicinal plant have been popularly used for the treatment of inflammatory diseases. In this study we evaluated the anti-inflammatory and antioxidant properties of crude extract (CE), aqueous fraction (AqF), ethyl acetate fraction (EAF), butanolic fraction (BuF) and catechin, gallocatechin and sub-fractions, 19SF, 35SF and 63SF that contained a mixture of proanthocyanidins and were derived from the EAF fraction. The CE, AqF, EAF, BuF, catechin and sub-fractions 35SF and 63SF reduced paw edema induced by carrageenan. The CE, fractions, sub-fractions and isolated compounds showed antioxidant properties in vitro, all were able to scavenge superoxide anions at a concentration of 100 microg ml(-1). The EAF, catechin and gallocatechin were most effective in the deoxyribose assay, IC50 0.69 (0.44-1.06), 0.20 (0.11-0.39), 0.55 (0.28-1.08) microg x ml(-1) respectively. The CE and other fractions and sub-fractions inhibited deoxyribose degradation up to 1 microg x ml(-1). In the hydrophobic system only AqF did not show lipid peroxidation inhibition. The CE, other fractions, sub-fractions and isolated compounds inhibited lipidid peroxidation only at a concentration of 100 microg x ml(-1). In summary, this study demonstrates that Croton celtidifolius bark has significant anti-inflammatory and antioxidant activity.
12. CRADE OF SAND AND DUST STORM WEATHER
Institute of Scientific and Technical Information of China (English)
Niu Ruoyun; Tian Cuiying; Bi Baogui; Yang Keming; Wang Youheng; Tuo Ya; Ding Haifang; Zhang Tairen
2011-01-01
Background Sand and dust storm,as one of the main disastrous weathers that affect northern China,not only affect the people health and normal life,but cause the short-term climatic changes due to the direct and indirect radiation of the earth-atmosphere system through the dust floating in the sky.The sand end dust weather and its potential harm on the national economy,ecological environment,social activities and other aspects have aroused worldwide concern.
13. Laboratory evaluation of selected tar sand asphalts
Energy Technology Data Exchange (ETDEWEB)
Button, J.W.; Epps, J.A.; Gallaway, B.M.
1980-12-01
Three tar sand asphalts of similar grades prepared from one syncrude by three different refining methods were characterized by tests commonly used to specify paving asphalts together with certain special tests. Asphalt-aggregate mixtures were prepared using these asphalts and tested in the laboratory to determine strength stiffness stability, tensile properties, temperature effects and water susceptibility. Comparison of the tar sand asphalt properties to conventional petroleum asphalt properties reveal no striking differences.
14. Treating tar sands formations with dolomite
Energy Technology Data Exchange (ETDEWEB)
Vinegar, Harold J.; Karanikas, John Michael
2010-06-08
Methods for treating a tar sands formation are described herein. The tar sands formation may include dolomite and hydrocarbons. Methods may include providing heat at less than the decomposition temperature of dolomite from one or more heaters to at least a portion of the formation. At least some of the hydrocarbon fluids are mobilized in the formation. At least some of the hydrocarbon fluids may be produced from the formation.
15. Pragmatics of reclaimed sand quality assessment recovered nowadays from various used sand systems
Directory of Open Access Journals (Sweden)
J. Dańko
2010-04-01
Full Text Available The assessment of the reclamation degree of used sands is not a simple, clearly defined issue. The great variety of technologies ofmoulding and core sands, based on the organic and inorganic binders does not allow the use of a single, universal index assessing thedegree of reclamation. The article presents the problems of research relating to selection of proper criteria for assessing the degree ofreclamation process of used moulding and core sands deriving from different technologies. The most often applied in practice types ofused sands and the most adequate in practice methods of assessing the degrees of their reclamation were characterized.
16. Sand Dune Encroachment and Desertification Processes of the Rigboland Sand Sea, Central Iran.
Science.gov (United States)
2017-05-08
Early studies on sand dune movement and desertification in Iran have not always been convincingly demonstrated because of problems with the field-based measurements. In some areas where various land uses have been engulfed by aeolian sand dunes, desertification is clear, but in other less settled areas, it may not be so obvious. The objective of this study is to demonstrate encroachments of the Rigboland sand sea, central Iran, in its different directions and variable magnitude rates. Determining the rate and direction of the sand sea movements is critical for specifying which lands should be prioritized and quickly protected. The study has trialed a change detection technique which uses a Cross-Tabulation module to compare two available LandsatTM images over the Rigboland sand sea. This indicates that within a ten-year span (from 1988 to 1998) more than 200 ha/yr were added to the Rigboland sand sea, from the alluvial fan landforms in the eastern upstream, outer margins of the Rigboland sand sea. Coupled with GIS techniques, this type of analysis of the remote sensing (RS) images provides an effective tool for the monitoring and prognostication of sand dune movement and sand sea change.
17. Analysis of sand particles' lift-off and incident velocities in wind-blown sand flux
Institute of Scientific and Technical Information of China (English)
Tian-Li Bo; Xiao-Jing Zheng; Shao-Zhen Duan; Yi-Rui Liang
2013-01-01
In the research of windblown sand movement,the lift-off and incident velocities of saltating sand particles play a significant role in bridging the spatial and temporal scales from single sand particle's motion to windblown sand flux.In this paper,we achieved wind tunnel measurements of the movement of sand particles near sand bed through improving the wind tunnel experimental scheme of paticle image velocimetry (PIV) and data processing method.And then the influence of observation height on the probability distributions of lift-off and incident velocities of sand particles was analyzed.The results demonstrate that the observation height has no obvious influence on the distribution pattern of the lift-off and incident velocities of sand particles,i.e.,the probability distribution of horizontal and vertical velocities of lift-off and incident sand particles follow a Gaussian distribution and a negative exponential distribution,respectively.However,it influences the center of the Gaussian distribution,the decay constant and the amplitude of the negative exponential distribution.
18. Recent Sand Avalanching on Rabe Crater Dunes
Science.gov (United States)
2000-01-01
Dark streaks on the steep, down-wind slopes of sand dunes in Rabe Crater are seen at several locations in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. These streaks indicate relatively recent (i.e., in the past few years or less) movement of sand down these slopes.Sand dunes move forward by the combined action of wind that drives sand up the shallow slope on the windward side of the dune (in this case, the slopes that face toward the lower right) and the avalanching of this sand down the steeper, lee-side slope. The steep slope is also known as the slip face. The dark streaks indicated by arrows are evidence for sand avalanches that occurred within a few months or years of the time when the picture was taken in March 1999. Other streaks which are seen criss-crossing the dunes may be the result of passing dust devils. This image is illuminated from the upper left and located in Rabe Crater of the Hellespontus-Noachis region near 44.2oS, 325.6oW.
19. Discrete particle simulation of mixed sand transport
Institute of Scientific and Technical Information of China (English)
Fengjun Xiao; Liejin Guo; Debiao Li; Yueshe Wang
2012-01-01
An Eulerian/Lagrangian numerical simulation is performed on mixed sand transport.Volume averaged Navier-Stokes equations are solved to calculate gas motion,and particle motion is calculated using Newton's equation,involving a hard sphere model to describe particle-to-particle and particle-to-wall collisions.The influence of wall characteristics,size distribution of sand particles and boundary layer depth on vertical distribution of sand mass flux and particle mean horizontal velocity is analyzed,suggesting that all these three factors affect sand transport at different levels.In all cases,for small size groups,sand mass flux first increases with height and then decreases while for large size groups,it decreases exponentially with height and for middle size groups the behavior is in-between.The mean horizontal velocity for all size groups well fits experimental data,that is,increasing logarithmically with height in the middle height region.Wall characteristics greatly affects particle to wall collision and makes the flat bed similar to a Gobi surface and the rough bed similar to a sandy surface.Particle size distribution largely affects the sand mass flux and the highest heights they can reach especially for larger particles.
20. Predicting the occurrence of sand banks in the North Sea
NARCIS (Netherlands)
Veen, van der Henriët H.; Hulscher, Suzanne J.M.H.
2009-01-01
Sand banks have a wavelength between 1 and 10 km, and they are up to several tens of meters high. Also, sand banks may have an impact on large-scale human activities that take place in the North Sea like sand mining, shipping, offshore wind farms, etc. Therefore, it is important to know where sand b
1. Convergence of bark investment according to fire and climate structures ecosystem vulnerability to future change.
Science.gov (United States)
Pellegrini, Adam F A; Anderegg, William R L; Paine, C E Timothy; Hoffmann, William A; Kartzinel, Tyler; Rabin, Sam S; Sheil, Douglas; Franco, Augusto C; Pacala, Stephen W
2017-03-01
Fire regimes in savannas and forests are changing over much of the world. Anticipating the impact of these changes requires understanding how plants are adapted to fire. In this study, we test whether fire imposes a broad selective force on a key fire-tolerance trait, bark thickness, across 572 tree species distributed worldwide. We show that investment in thick bark is a pervasive adaptation in frequently burned areas across savannas and forests in both temperate and tropical regions where surface fires occur. Geographic variability in bark thickness is largely explained by annual burned area and precipitation seasonality. Combining environmental and species distribution data allowed us to assess vulnerability to future climate and fire conditions: tropical rainforests are especially vulnerable, whereas seasonal forests and savannas are more robust. The strong link between fire and bark thickness provides an avenue for assessing the vulnerability of tree communities to fire and demands inclusion in global models.
2. Presence of carbaryl in the smoke of treated lodgepole and ponderosa pine bark
Science.gov (United States)
Peterson, Chris J.; Costello, Sheryl L.
2013-02-01
Lodgepole and ponderosa pine trees were treated with a 2% carbaryl solution at recreational areas near Fort Collins, CO, in June 2010 as a prophylactic bole spray against the mountain pine beetle. Bark samples from treated and untreated trees were collected one day following application and at 4-month intervals for one year. The residual amount of carbaryl was determined, and bark samples were burned to examine the smoke for the active ingredient. Smoke recovered from spiked bark samples showed a very high correlation between the treated rate and the concentration recovered from the smoke. Residual carbaryl on the bark was relatively stable throughout the study and carbaryl was detected in the smoke throughout the duration of the test.
3. STRUCTURES OF TWO NEW BENZOFURAN DERIVATIVES FROM THE BARK OF MULBERRY TREE (MORUS MACROURA MIQ.)
Institute of Scientific and Technical Information of China (English)
SHENG-GUO SUN; RUO-YUN CHEN; DE-QUAN YU
2001-01-01
Two new benzofuran derivatives, macrourins A (1) and B (2), together with two known stilbene derivatives, were isolated from the barks of Morus macroura Miq. Their structures were elucidated by means of spectroscopic evidence.
4. Extraction of betulin from bark of Betula platyphylla by supercritical carbon dioxide extraction
Institute of Scientific and Technical Information of China (English)
ZHANG Yu-hong; YU Tao; WANG Yang
2003-01-01
Betulin, which is a medicinal pentacyclic triterpene, is abundant in the bark of white birch (Betula platyphlly). The bark of birch was collected at Tayuan Forest Farm of Jiagedaqi, Heilongjiang Province in September 2000. Supercritical fluid extraction (SFE) that is a new separation technology has been used for the processing pharmaceutical and natural products. In this paper, the extraction of betulin from the bark of birch by supercritical CO2 extraction was studied. The authors investigated and analyzed a few parameters such as modifier dosage, extraction pressure and extraction temperature. The optimal extraction conditions showed that the modifier dosage used for per gram bark powder was 1.5 mL, the extraction pressure was at 20 Mpa, and the extraction temperature was at 55 ℃. The velocity of flow of liquid CO2 was at 10 kg/h. The pressure and temperature in separation vessel were at 5.5 Mpa and 50 ℃, respectively.
5. Effect of Different Pretreatment Methods on Birch Outer Bark: New Biorefinery Routes
Directory of Open Access Journals (Sweden)
Anthi Karnaouri
2016-03-01
Full Text Available A comparative study among different pretreatment methods used for the fractionation of the birch outer bark components, including steam explosion, hydrothermal and organosolv treatments based on the use of ethanol/water media, is reported. The residual solid fractions have been characterized by ATR-FTIR, 13C-solid-state NMR and morphological alterations after pretreatment were detected by scanning electron microscopy. The general chemical composition of the untreated and treated bark including determination of extractives, suberin, lignin and monosaccharides was also studied. Composition of the residual solid fraction and relative proportions of different components, as a function of the processing conditions, could be established. Organosolv treatment produces a suberin-rich solid fraction, while during hydrothermal and steam explosion treatment cleavage of polysaccharide bonds occurs. This work will provide a deeper fundamental knowledge of the bark chemical composition, thus increasing the utilization efficiency of birch outer bark and may create possibilities to up-scale the fractionation processes.
6. Allozyme analysis of host selection by bark beetles in central Mexico
National Research Council Canada - National Science Library
Vargas C.F; Lopez A; Sanchez H; Rodriguez B
2002-01-01
A study was done to determine if the bark beetles Dendroctonus adjunctus Blandford and Dendroctonus valens LeConte exhibit a nonrandom selection pattern of susceptible Pinus lawsonii Rozel and Pinus montezumae Lamb...
7. the effect of aqueous stem bark extract of erythrina mildbraedii on ...
African Journals Online (AJOL)
USER
2015-06-01
Jun 1, 2015 ... most of leguminoseae, Erythrina species produce ... diseases, oxidative stress and generating free radicals .... used for all the analysis. ... Table 1: Effects of oral administration of aqueous stem bark extract on Erythrina ...
8. Description of Histiostoma Conjuncta (New Comb.) (Acari: Anoetidae), An Associate of Central American Bark Beetles
Science.gov (United States)
J. P. Woodring; John C. Moser
1975-01-01
The adult female and male plus the tritonymph of Histiostoma conjuncta (Woodring and Moser, 1970) (new comb.) and described. The species is known to be associated with various pine bark beetles from Honduras, Guatemala, and Louisiana.
9. Antifungal activity of bioactive constituents and bark extracts of Rhododendron arboreum
National Research Council Canada - National Science Library
2013-01-01
Rhododendron arboreum various fractions of bark as well as the isolated compounds were investigated against pathogenic fungi to provide evidence for the folkloric uses reported in the traditional system...
10. 78 FR 4167 - Certain Electronic Bark Control Collars; Notice of Receipt of Complaint; Solicitation of Comments...
Science.gov (United States)
2013-01-18
... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Electronic Bark Control Collars; Notice of Receipt of Complaint; Solicitation of Comments Relating to the Public Interest AGENCY: U.S. International Trade Commission. ACTION: Notice....
11. Layers, Landslides, and Sand Dunes
Science.gov (United States)
2003-01-01
[figure removed for brevity, see original site] Released 27 October 2003This image shows the northern rim of one of the Valles Marineris canyons. Careful inspection shows many interesting features here. Note that the spurs and gullies in the canyon wall disappear some distance below the top of the canyon wall, indicating the presence of some smooth material here that weathers differently from the underlying rocks. On the floor of the canyon, there are remains from a landslide that came hurtling down the canyon wall between two spurs. Riding over the topography of the canyon floor are many large sand dunes, migrating generally from the lower right to upper left.Image information: VIS instrument. Latitude -14.1, Longitude 306.7 East (53.3 West). 19 meter/pixel resolution.Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.
12. Heartwood, sapwood and bark content of teak trees grown in Karna-taka, India
Institute of Scientific and Technical Information of China (English)
2013-01-01
We evaluated heartwood, sapwood and bark content in teak trees. A total of 27 sample plots were laid out in teak plantations raised by State Forest Department in Karnataka covering different age groups (11−36 years), density (516−2061 trees/ha) and sites. From these planta-tions, a total of 130 trees were felled for estimating the yield and bark content in relation to diameter at breast height (DBH), age and density. Bark content ranged from 22.2%−54.3%. Heartwood and sapwood con-tent were analyzed by sampling five trees each from two different planta-tions, one 30 years old at 553 trees⋅ha-1 and the other 32 years old at 911 trees⋅ha-1. The highest heartwood proportion of stem wood volume (over-bark) was 56.3%and the lowest was 37.1%. The sapwood propor-tion ranged from 12.9%−23.0%, while the bark content ranged from 27.8%−43.5%. The heartwood proportion increased with DBH, while the proportion of bark decreased. The sapwood proportion did not vary with DBH. The bark content decreased with increasing age, but increased with stand density. There was no significant difference in heartwood content with respect to age or stand density because the ages of the two stands were similar. A larger dataset from young to mature stands is needed to describe the relationships between age and stand density and heartwood, sapwood and bark content of trees.
13. Co-composting of invasive Acacia longifolia with pine bark for horticultural use.
Science.gov (United States)
Brito, Luis Miguel; Mourão, Isabel; Coutinho, João; Smith, Stephen R
2015-01-01
The feasibility of commercial-scale co-composting of waste biomass from the control of invasive Acacia species with pine bark waste from the lumber industry, in a blend ratio of 60:40 (v:v), was investigated and compared with previous research on the composting of Acacia without additional feedstock, to determine the potential process and end-product quality benefits of co-composting with bark. Pile temperatures rose rapidly to >70 °C and were maintained at >60 °C for several months. Acacia and bark biomass contained a large fraction of mineralizable organic matter (OM) equivalent to approximately 600 g kg(-1) of initial OM. Bark was more recalcitrant to biodegradation compared with Acacia, which degraded at twice the rate of bark. Therefore, incorporating the bark increased the final amount of compost produced compared with composting Acacia residues without bark. The relatively high C/N ratio of the composting matrix (C/N=56) and NH3 volatilization explained the limited increases in NH4+-N content, whereas concentrations of conservative nutrient elements (e.g. P, K, Ca, Mg, Fe) increased in proportion to OM mineralization, enriching the compost as a nutrient source for horticultural use. Nitrogen concentrations also increased to a small extent, but were much more dynamic and losses, probably associated with N volatilization mechanisms, were difficult to actively control. The physicochemical characteristics of the stabilized end-product, such as pH, electrical conductivity and OM content, were improved with the addition of bark to Acacia biomass, and the final compost characteristics were suitable for use for soil improvement and also as horticultural substrate components.
14. Willow inner bark as a potential source of fibres and chemicals
OpenAIRE
Dou, Jinze
2015-01-01
The aim of this thesis was to acquire basic information on the physical and chemical structure of willow inner bark in order to assess its potential as a raw material for chemicals and fibres. Inner bark from four cultivated willow species/hybrids was studied and compared with their wood tissue. The cell and cell wall structure was studied by optical microscopy, SEM and TEM. The fibres were separated with an acid chlorite treatment and analyzed for their dimensions and morphology. The chemica...
15. Analgesic and anti-inflammatory activity of root bark of Grewia asiatica Linn. in rodents
OpenAIRE
2013-01-01
Background: Grewia asiatica Linn. (Family: Tiliaceae), called Phalsa in Hindi is an Indian medicinal plant used for a variety of therapeutic and nutritional uses. The root bark of the plant is traditionally used in rheumatism (painful chronic inflammatory condition). Aims: The present study demonstrates the analgesic and anti-inflammatory activity of root bark of G. asiatica in rodents. Settings and Design: The methanolic extract of Grewia asiatica (MEGA) and aqueous extract of Grewia...
16. Development of the Gran Desierto sand sea, northwestern Mexico
Science.gov (United States)
1990-08-01
Three major eolian sand populations can be recognized in the Gran Desierto sand sea of northwestern Mexico by using spectral data from the Landsat thematic mapper in conjunction with textural and mineralogical studies of surface sands. Each sand population has distinct textural, mineralogic, and spectral properties that can be related to sand-dune morphology and position with reference to source areas and transport paths of the sands. The oldest eolian sediment in the sand sea was derived from the early to middle Pleistocene Colorado River that flowed through the area of the western Gran Desierto. Subsequent inputs of eolian sands came from the area of the present Colorado River valley and the coast south of the sand sea. The spatial and temporal pattern of eolian deposition in the region has been controlled by Quaternary tectonic and climatic changes, resulting in the episodic input and deposition of sand.
17. Sphagnum Moss in the Athabasca Bituminous Sands Region Reveals No Significant Atmospheric Contamination by "Heavy Metals"
OpenAIRE
SHOTYK W.; BELLAND Rene; DUKE John; KEMPTER Heike; KRACHLER MICHAEL; NOERNBERG Tommy; VILE Melanie; WIEDER Kelman; Zaccone, Claudio; Zhang, Shuangquan
2014-01-01
Sphagnum moss were collected from three sites at each of twenty-one ombrotrophic (rain-fed) peat bogs in the vicinity of and surrounding open pit mines and upgrading facilities of Athabasca Bituminous Sands in Alberta. Compared with contemporary Sphagnum moss from multiple sites at each of four bogs in rural locations of southern Germany, the AB mosses yielded lower concentrations of Ag, Cd, Ni, Pb, Sb and Tl, similar concentrations of Mo, but greater concentrations of Ba, Th and V. ...
18. Effects of advanced oxidation on green sand properties via iron casting into green sand molds.
Science.gov (United States)
Wang, Yujue; Cannon, Fred S; Voigt, Robert C; Komarneni, Sridhar; Furness, J C
2006-05-01
The effects of advanced oxidation (AO) processing on the properties of green sand were studied via pouring cast iron into green sand molds. Upon cooling, the green sand molds were autopsied at various distances from the metal-sand interface. Autopsy green sand samples collected from a mold that incorporated AO water were characterized and compared to controlled samples collected from a similar autopsied mold made with conventional tap water (TAP). It was found that the AO processing removed a coating of coal pyrolysis products from the clay surface that typically accumulated on the clay surface. As a result, the AO-conditioned green sand retained 10-15% more active clay as measured bythe standard ultrasonic methylene blue titration than did the TAP-conditioned green sand. The AO processing also nearly doubled the generation of activated carbon from the normalized amount of coal composition of the green sand during the casting process. The AO-enhanced activated carbon generation and the AO-incurred clay surface cleaning provided the AO-conditioned green sand with higher normalized pore volume, and thus higher normalized m-xylene adsorption capacity, i.e., relative to before-metal-pouring conditions. Furthermore, mathematical analysis indicated that the AO-conditioned green sand better retained its important properties after pouring than did the TAP-conditioned green sand. Effectively, this meant after metal pouring, the AO-conditioned sample offered about the same net properties as the TAP-conditioned sample, even though the AO-conditioned sample contained less clay and coal before metal pouring. These results conformed to the full-scale foundry empirical finding that when AO is used, foundries need less makeup clay and coal addition through each casting cycle, and they release less air emissions.
19. Contribution of laser altimetry images to the geomorphology of the Late Holocene inland drift sands of the European Sand Belt
NARCIS (Netherlands)
Jungerius, P.D.; Riksen, M.J.P.M.
2010-01-01
The paper explores the possibilities of applying the analysis of laser altimetry images to Dutch drift sands. All along the European Sand Belt, which stretches from Great Britain to the Ural Mountains, Late Glacial cover sands, river dunes and other ice-age deposits were reactivated as drift sand du
20. Contribution of laser altimetry images to the geomorphology of the Late Holocene inland drift sands of the European Sand Belt
NARCIS (Netherlands)
Jungerius, P.D.; Riksen, M.J.P.M.
2010-01-01
The paper explores the possibilities of applying the analysis of laser altimetry images to Dutch drift sands. All along the European Sand Belt, which stretches from Great Britain to the Ural Mountains, Late Glacial cover sands, river dunes and other ice–age deposits were reactivated as drift sand du
1. Contribution of laser altimetry images to the geomorphology of the Late Holocene inland drift sands of the European Sand Belt
NARCIS (Netherlands)
Jungerius, P.D.; Riksen, M.J.P.M.
2010-01-01
The paper explores the possibilities of applying the analysis of laser altimetry images to Dutch drift sands. All along the European Sand Belt, which stretches from Great Britain to the Ural Mountains, Late Glacial cover sands, river dunes and other ice–age deposits were reactivated as drift sand
2. Comparative study of leaf and stem bark extracts of Parkia biglobosa against enterobacteria.
Science.gov (United States)
Millogo-Kone, H; Guissou, I P; Nacoulma, O; Traore, A S
2008-04-10
Hydroethanolic and aqueous extracts of leaf and stem bark of Parkia biglobosa (Jacq) Benth. (Mimosaceae) were tested against clinical isolates Escherichia coli, Salmonella typhi, Shigella dysenteriae and Enterococcus faecalis, and corresponding collection strains E. coli CIP 105 182, Salmonella enterica CIP 105 150, Shigella dysenteriae CIP 54-51 and Enterococcus faecalis CIP 103 907. Discs of Gentamicin, a broad spectrum antibiotic were used as positive controls. The results showed that all the extracts possess antimicrobial activities. A comparative study of the antibacterial activity of the leaves and that of the bark showed that for all the tested microorganisms, the hydroalcoholic extract of the bark is more active than the aqueous extract of the leaf. The hydroethanolic extract of the leaves is as effective as the aqueous extract of the stem bark prescribed by the traditional healer, suggesting it is possible to use leaves other than the roots and bark. The phytochemical screening showed that sterols and triterpenes, saponosides, tannins, reducing compounds, coumarins, anthocyanosides, flavonosides are present in both bark and leaf but in different concentrations.
3. In Vitro Antioxidant and Anticancer potential of Bark of Costus pictus D.DON
Institute of Scientific and Technical Information of China (English)
Malairaj Sathuvan; Anadhan Vignesh; Ramar Thangam; Perumal Palani; Ramasamy Rengasamy; Kandasamy Murugesan
2012-01-01
Objective: To evaluate the antioxidant and anticancer potential of different fractions of bark of Costus pictus using various in vitro antioxidant assay systems. Methods: In this study, assay like DPPH radical, superoxide anion radical scavenging activity, nitric oxide scavenging activity, hydrogen peroxide scavenging activity, metal chelating activity and reducing power were used. The concentrations of total phenolic and flavonoids were also calculated for the extracts.Result:pictus. This study suggested that, among the three fractions, the chloroform fraction possesses high antioxidant activity which might be helpful in preventing or slowing the progress of various oxidative stress related disorders. Moreover, all fractions possess potent anticancer properties against colon cancer cells of HT29 and lung carcinoma cells of A549. Conclusions: It can be concluded that the extract of the bark of C. pictus has potential natural antioxidant and this can be used in food industries. There are few reports on the antioxidant capacity of bark of C. pictus and the mechanism of different fractions of bark of C. pictus as antioxidative agents is still not fully understood. Hence further research is underway to analyse and isolate the active compounds responsible for the antioxidant and anticancer activity of different fractions of the bark of C.pictus. The present study elucidated for the first time the antioxidant property of bark of C.
4. Optical solar energy adaptations and radiative temperature control of green leaves and tree barks
Energy Technology Data Exchange (ETDEWEB)
Henrion, Wolfgang; Tributsch, Helmut [Department of Si-Photovoltaik and Solare Energetik, Hahn-Meitner-Institut Berlin, 14109 Berlin (Germany)
2009-01-15
Trees have adapted to keep leaves and barks cool in sunshine and can serve as interesting bionic model systems for radiative cooling. Silicon solar cells, on the other hand, loose up to one third of their energy efficiency due to heating in intensive sunshine. It is shown that green leaves minimize absorption of useful radiation and allow efficient infrared thermal emission. Since elevated temperatures are detrimental for tensile water flow in the Xylem tissue below barks, the optical properties of barks should also have evolved so as to avoid excessive heating. This was tested by performing optical studies with tree bark samples from representative trees. It was found that tree barks have optimized their reflection of incoming sunlight between 0.7 and 2 {mu}m. This is approximately the optical window in which solar light is transmitted and reflected by green vegetation. Simultaneously, the tree bark is highly absorbing and thus radiation emitting between 6 and 10 {mu}m. These two properties, mainly provided by tannins, create optimal conditions for radiative temperature control. In addition, tannins seem to have adopted a function as mediators for excitation energy towards photo-antioxidative activity for control of radiation damage. The results obtained are used to discuss challenges for future solar cell optimization. (author)
5. Anti-pseudomonas activity of essential oil, total extract, and proanthocyanidins of Pinus eldarica Medw. bark
Directory of Open Access Journals (Sweden)
2016-01-01
Full Text Available Pinus eldarica Medw. (Iranian pine is native to Transcaucasian region and has been vastly planted in Iran, Afghanistan, and Pakistan. Various parts of this plant have been widely used in traditional medicine for the treatment of various diseases including infectious conditions (e.g. infectious wounds. In this study we aimed to investigate the antibacterial activity of P. eldarica bark extract, essential oil and proanthocyanidins on three important bacteria, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Antibacterial analysis was performed using standard disk diffusion method with different concentrations of essential oil, bark total hydroalcoholic extract, and bark proanthocyanidins (0.5, 1, 2 and 3 mg/ml. After incubation at 37 °C for 24 h, the antibacterial activity was assessed by measuring the zone of growth inhibition surrounding the disks. The results indicated that the essential oil, total hydroalcoholic extract, and proanthocyanidins of the bark of the P. eldarica were effective against the gram negative bacteria, P. aeruginosa, and significantly inhibited its growth in disk diffusion method (P<0.001 of which the essential oil had the most potent inhibitory effect. However, none of the bark preparations could significantly inhibit the growth of S. aureus or E. coli. Our findings showed that P. eldarica bark components have significant anti-pseudomonas activity having potentials for new sources of antibacterial agents or antibacterial herbal preparations.
6. Hypoglycemic activity of Bougainvillea spectabilis stem bark in normal and alloxan-induced diabetic rats
Institute of Scientific and Technical Information of China (English)
Sunil Jawla; Y Kumar; MSY Khan
2012-01-01
Objective: Bougainvillea spectabilis (B. spectabilis) is one of the main constituent of various herbal formulations available for diabetes. The aim of present study was to screen hypoglycemic potential of B. spectabilis stem bark extracts in albno rats (Wistar strain). Methods: The EtOH extracts (100, 250 and 500 mg/kg/day) of the B. spectabilis were administered to both normal and alloxan induced diabetic rats at defined time intervals. Blood glucose levels were measured at 0, 0.5, 1, 2, 4, 6 h, and on 0, 1, 3, 5, 7th day after oral administration of extracts. Of the doses test, highest anti-hyperglycemic effect was observed by the extract of stem bark at 250 mg/kg after a week treatment. Results: B. spectabilis stem bark extract exhibited significant hypoglycemic activity at different doses and intervals. Stem bark extract was found to be 22.2% more potent than standard oral hypoglycemic drug, glibenclamide 0.2 mg/kg. Conclusion: Treatment of alloxan induced diabetic rats up to a week with stem bark extract reversed the permanent hyperglycemia. Hence, B. spectabilis stem bark alcoholic extract exhibited potent hypoglycemic activity.
7. Variations in bark thickness and sapwood density of Calophyilum inophyllum provenances in Australia and in Sri Lanka
Institute of Scientific and Technical Information of China (English)
Subhash Hathurusingha; Nanjappa Ashwath
2011-01-01
Sapwood density and bark thickness of Calophyllum inophyl- lum L. (a multipurpose durable timber species) were studied in various locations in Northern Australia and in Sri Lanka. Measurements were taken non-destructively by using core sampling and bark gauge. From each provenance, 4-15 mature trees having girth at breast height over bark (GBHOB) at 100-150 cm were selected on the basis of the popula- tion size. Significant (p<0.05) hemispheric and provenance variations in bark thickness were found. Variations in the bark thickness are influ- enced by environmental variables. Variations in sapwood density were less pronounced compared to that of bark thickness. Variations in sap- wood density are likely to be governed by genotypic variations.
8. Bright sand/dark dust: The identification of active sand surfaces on the Earth and Mars
Science.gov (United States)
Blount, H. G., II; Greeley, R.; Christensen, P. R.; Arvidson, R.
1987-05-01
Field studies and analysis of LANDSAT Thematic Mapper data in the Gran Desierto, Mexico may shed light on a technique to distinguish active from inactive (relict) sand surfaces. Active sand bodies in the study area are consistently brighter (by an average of 20%) at visual and near infrared wavelengths and darker at thermal infrared wavelengths than compositionally similar inactive sands. The reasons for the albedo difference between active and inactive sands are reviewed and the mixing model of Johnson et al. is examined for tracing the provenance of sands based on albedo and spectral variations. Portions of the wavelengths covered by the Mars Orbiter correspond to the Thematic Mapper data. The identification of active sands on Earth, with a priori knowledge of bulk composition and grain size distribution, may allow the remote mapping of active sand surfaces on Mars. In conjuction with thermal infrared remote sensing for composition, it may also provide a method for the remote determination of grain size distributions within sand/silt mixtures.
9. Simulating and understanding sand wave variation: A case study of the Golden Gate sand waves
Science.gov (United States)
Sterlini, F.; Hulscher, S.J.M.H.; Hanes, D.M.
2009-01-01
In this paper we present a detailed comparison between measured features of the Golden Gate sand wave field and the results of a nonlinear sand wave model. Because the Golden Gate sand waves exhibit large variation in their characteristics and in their environmental physics, this area gives us the opportunity to study sand wave variation between locations, within one well-measured, large area. The nonlinear model used in this paper is presently the only tool that provides information on the nonlinear evolution of large-amplitude sand waves. The model is used to increase our understanding of the coupling between the variability in environmental conditions and the sand wave characteristics. Results show that the model is able to describe the variation in the Golden Gate sand waves well when both the local oscillating tidal current and the residual current are taken into account. Current and water depth seem to be the most important factors influencing sand wave characteristics. The simulation results give further confidence in the underlying model hypothesis and assumptions. Copyright 2009 by the American Geophysical Union.
10. MORPHOMETRIC CHARACTERIZATION OF THE SAND FRACTION IN A SAND GRAIN IMAGE CAPTURE SYSTEM1
Directory of Open Access Journals (Sweden)
Lucimar Arruda Viana
Full Text Available ABSTRACT Morphology studies assume significant importance in analysis of phenomena of granular systems packaging, in particular with a view to the use of the technique of soil stabilization named particle size correction in forest roads. In this context, this study aimed to develop and operationalize a Sand Grain Image Capture System and, hereby, determine the morphological indices of the sand fractions of two sandy soils called João Pinheiro (JP and Cachoeira da Prata (CP. Soil samples, air-dried, were sieved (2.0 mm nominal mesh size for removal of gravels. The materials that passed through the sieve were subjected to dispersion, washing in 0.053 mm nominal mesh size sieve, removal of organic matter and iron oxides to obtain the clean sand fractions. Subsequently, each soil sample was sieved for separation into twelve classes, between the diameters of 0.149 mm and 1.190 mm, using a Rotap shaker. Next, tests were carried out to characterize the morphometric attributes of the twelve classes of sand fractions of the soils studied. For validation of the performance of the Sand Grain Image Capture System, the results were compared to those obtained using a standard procedure for image analysis. The analysis of the results led to the following conclusions: (i the sand fraction of the JP soil presented higher values for the morphometric indices roundness, elongation and compactness compared to sand fraction of the CP soil; and (ii the Sand Grain Image Capture System worked properly, with practicality.
11. Probability of rebound and eject of sand particles in wind-blown sand movement
Institute of Scientific and Technical Information of China (English)
Li Xie; Xiaojing Zheng
2007-01-01
When incident particles impact into a sand bed in wind-blown sand movement, rebound of the incident particles and eject of the sand particles by the incident particles affect directly the development of wind sand flux. In order to obtain rebound and eject lift-off probability of the sand particles, we apply the particle-bed stochastic collision model presented in our pervious works to derive analytic solutions of velocities of the incident and impacted particles in the postcollision bed. In order to describe randomness inherent in the real particle-bed collision, we take the incident angle, theimpact position and the direction of resultant action of sand particles in sand bed on the impacted sand particle as random variables, and calculate the rebound and eject velocities,angles and coefficients (ratio of rebound and eject velocity to incident velocity). Numerical results are found in accordance with current experimental results. The rebound and eject lift-off probabilities versus the incident and creeping velocities are predicted.
12. Antioxidant, Antimicrobial Properties and Phenolics of Different Solvent Extracts from Bark, Leaves and Seeds of Pongamia pinnata (L.) Pierre
OpenAIRE
Alkharfy, Khalid M; Anwarul-Hassan Gilani; Ghulam Rasul; Ghulam Shabir; Farooq Anwar; Zahid Iqbal Sajid
2012-01-01
This study appraises the antioxidant and antimicrobial attributes of various solvent extracts (absolute methanol, aqueous methanol, absolute ethanol, aqueous ethanol, absolute acetone, aqueous acetone, and deionized water) from bark, leaves and seeds of Pongamia pinnata (L.) Pierre. Maximum extraction yield of antioxidant components from bark (16.31%), leaves (11.42%) and seeds (21.51%) of P. pinnata was obtained using aqueous methanol (20:80). Of the extracts tested, the bark extract, obtain...
13. Tree bark as a passive air sampler to indicate atmospheric polybrominated diphenyl ethers (PBDEs) in southeastern China.
Science.gov (United States)
Fu, Xiaoxu; Wang, Junxia; Zhou, Xiaoyu; Deng, Jingjing; Liu, Yangcheng; Zhang, Wei; Liu, Lili; Dong, Liang; Lin, Kuangfei
2014-06-01
The different barks were sampled to discuss the influence of the tree species, trunk circumference, and bark thickness on the accumulation processes of polybrominated diphenyl ethers (PBDEs) from air into the bark. The results of different PBDE concentrations indicated that barks with a thickness of 0-3 mm collected from weeping willow, Camphor tree, and Masson pine, the trunk circumferences of which were 100 to 150 cm, were better PBDEs passive samplers. Furthermore, tree bark and the corresponding air samples were collected at Anji (AJ), Hangzhou (HZ), Shanghai (SH), and Wenling (WL) to investigate the relationship between the PBDE concentrations in bark and those in air. In addition, the significant correlation (r (2) = 0.906; P PBDEs were the principle source for the accumulation of PBDEs in the barks. In this study, the log K BA (bark-air partition coefficient) of individual PBDE congeners at the four sites were in the range from 5.69 to 6.79. Finally, the total PBDE concentration in WL was 5 to 20 times higher than in the other three cities. The result indicated that crude household workshops contributed a heavy amount of PBDEs pollution to the environment, which had been verified by the spatial distribution of PBDEs levels in barks collected at Wenling (range, 26.53-1317.68 ng/g dw). The good correlation between the PBDE concentrations in the barks and the air samples and the variations of the PBDE concentrations in tree barks collected from different sites reflected that the bark could be used as a passive sampler to indicate the atmospheric PBDEs.
14. Capturing phosphates with iron enhanced sand filtration.
Science.gov (United States)
Erickson, Andrew J; Gulliver, John S; Weiss, Peter T
2012-06-01
Most treatment practices for urban runoff capture pollutants such as phosphorus by either settling or filtration while dissolved phosphorus, typically as phosphates, is untreated. Dissolved phosphorus, however, represents an average 45% of total phosphorus in stormwater runoff and can be more than 95%. In this study, a new stormwater treatment technology to capture phosphate, called the Minnesota Filter, is introduced. The filter comprises iron filings mixed with sand and is tested for phosphate removal from synthetic stormwater. Results indicate that sand mixed with 5% iron filings captures an average of 88% phosphate for at least 200 m of treated depth, which is significantly greater than a sand filter without iron filings. Neither incorporation of iron filings into a sand filter nor capture of phosphates onto iron filings in column experiments had a significant effect on the hydraulic conductivity of the filter at mixtures of 5% or less iron by weight. Field applications with up to 10.7% iron were operated over 1 year without detrimental effects upon hydraulic conductivity. A model is applied and fit to column studies to predict the field performance of iron-enhanced sand filters. The model predictions are verified through the predicted performance of the filters in removing phosphates in field applications. Practical applications of the technology, both existing and proposed, are presented so stormwater managers can begin implementation.
15. Cleaning oil sands drilling waste in Alberta
Energy Technology Data Exchange (ETDEWEB)
Mikic, N.; Nilsen, C.; Markabi, M. [Mi SWACO, Calgary, AB (Canada)
2008-07-01
The waste generated from steam assisted gravity drainage (SAGD) wells is brought to the surface and separated by shale shakers. The waste can include drilling fluids and sand contaminated with bitumen. This paper described a new technology developed to treat waste using the addition of hot water and various mixing and separation technologies to reduce the viscosity of the bitumen and separate it from the sand. The bitumen-contaminated drill cuttings were mixed with hot water to form a slurry that was then separated through the G-force created by a hydrocyclone. A secondary separation was then conducted in an elutriation column to remove residual contaminants from the sand. The flow rate of the process was controlled by the fine solids composition of the cuttings, the temperature of the cleaning process, and the performance of the individual components. Laboratory tests conducted to tests the method showed that the sand particles produced using the method were clean enough to be safely disposed in the environment. A pilot study will be conducted to test the sand cleaning technology at a commercial scale. 6 refs., 3 figs.
16. Mitigating in situ oil sands carbon costs
Energy Technology Data Exchange (ETDEWEB)
Theriault, D.J.; Peterson, J. [Laricina Energy Ltd., Calgary, AB (Canada); Heinrichs, H. [Canadian Chemical Technology Inc., Calgary, AB (Canada)
2008-10-15
Carbon capture and sequestration is a complex problem with a variety of dimensions that need to be considered. The political, social, and regulatory pressures are forcing carbon costs on the oil sands industry in an effort to reduce the carbon footprint of oil sands operations. This paper reviewed the political, social, and regulatory pressures and obligations for the in-situ oil sands industry. It presented the views and insights of Laricina Energy on the carbon challenge. It also described the initiatives that Laricina Energy is taking to manage these imperatives and outlined the challenges the industry is facing. The purpose of the paper was to encourage dialogue and collaboration by the oil sands industry. The paper also described the dimensions of the carbon problem and how the industry can contribute to a solution. Last, the paper reviewed the parameters of carbon dioxide or greenhouse gas containment and storage issues. It was concluded that the regulatory and policy requirements need to be clarified so that industry understands the new business landscape as well as the requirements that influence the economics of in-situ oil sands development. 7 refs., 7 figs.
17. Asian Facilities
Science.gov (United States)
Nakahata, M.
2011-04-01
Asian underground facilities are reviewed. The YangYang underground Laboratory in Korea and the Kamioka observatory in Japan are operational and several astrophysical experiments are running. Indian Neutrino Observatory(INO) and China JinPing Underground Laboratory (CJPL) are under construction and underground experiments are being prepared. Current activities and future prospects at those underground sites are described.
18. An airborne assessment of atmospheric particulate emissions from the processing of Athabasca oil sands
Directory of Open Access Journals (Sweden)
S. G. Howell
2013-08-01
Full Text Available During the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS campaign, two NASA research aircraft, a DC-8 and a P-3B, were outfitted with extensive trace gas (the DC-8 and aerosol (both aircraft instrumentation. Each aircraft spent about a half hour sampling air around the oil sands mining and upgrading facilities near Ft. McMurray, Alberta, Canada. The DC-8 circled the area, while the P-3B flew directly over the upgrading plants, sampling close to the exhaust stacks, then headed downwind to monitor the aerosol as it aged. At short range, the plume from the oil sands is a complex mosaic of freshly nucleated ultrafine particles from a SO2 and NO2-rich plume, fly ash and soot from industrial processes, and dust from dirt roads and mining operations. Shortly downwind, organic aerosol appears in quantities that rival SO4=, either as volatile organic vapors condense or as they react with the H2SO4. The DC-8 pattern allowed us to integrate total flux from the oil sands facilities within about a factor of two uncertainty that spanned values consistent with 2008 estimates from reported SO2 and NO2 emissions. In contrast, CO fluxes exceeded reported regional emissions, due either to variability in production or sources missing from the emissions inventory. The conversion rate of SO2 to aerosol SO4= of ~6% per hour is consistent with earlier reports, though OH concentrations are insufficient to accomplish this. Other oxidation pathways must be active. Altogether, organic aerosol and black carbon emissions from the oil sands operations are small compared with the forest fires present in the region during the summer. The oil sands do contribute significant sulfate and exceed fire production of SO2 by an order of magnitude.
19. Height, branch-free bole length and bark thickness for six tree species used medicinally in South Africa
Directory of Open Access Journals (Sweden)
V.L. Williams
2005-06-01
Full Text Available Information on tree stem characteristics and dimensions is sparse, especially information that would enhance conservation and trade monitoring efforts for species where bark is harvested for medicinal use. Several tree stem characteristics were investigated during a study on the relationship between bark thickness and stem diameter, and this paper presents the mean height, branch-free bole length and wet and oven-dry bark thickness per stem diameter-class for six species. Additionally, prediction tables are constructed that allow bark thickness to be determined from diameter at breast height.
20. Permeability Tests on Eastern Scheldt Sand
DEFF Research Database (Denmark)
Jakobsen, Kim Parsberg
The flow through porous media plays an important role in various engineering disciplines, as for example in ground water hydrology and soil mechanics. In the present study the permeability is determined for a fine, saturated sand. As the flow through a porous media strongly depends on the charact......The flow through porous media plays an important role in various engineering disciplines, as for example in ground water hydrology and soil mechanics. In the present study the permeability is determined for a fine, saturated sand. As the flow through a porous media strongly depends...... on the characteristics of the soil matrix, the permeability is determined for different void ratios. All tests are performed on reconstituted specimens of Eastern Scheldt Sand. The permeability is determined by use of a falling head apparatus. Finally the test results are briefly summarised and a relationship between...... void ratio and permeability is established....
1. Sand Dunes Fixation in Baiji District, Iraq
Institute of Scientific and Technical Information of China (English)
2002-01-01
This study was carried out at Sand Dunes Stabilization Researches Station in Baiji district (230 ln north of Baghdad, Iraq) to evaluate the effects of local soil conditioners manufactured from oil derivatives and plant residuals on sand dunes fixation as the first step for sand dunes stabilization. The results indicate that the fuel oil has the first place in improving wind erosion parameters in the study area, such as increasing mean weight diameter, dry aggregates percentage, the needed time for complete disaggregation by dry sieving, and decreasing the disaggregation rates. Bitumen emulsion occupies the second place, while the plant residuals occupies the third place and has slight effects on the studied parameters. Effects of conditioners on natural vegetation cover are negative in oil derivatives treatments,while positive in plants residuals treatments.
2. Thermoluminescent dosimetric properties of Descalvado sand
Energy Technology Data Exchange (ETDEWEB)
Teixeira, M.I.; Caldas, L.V.E
2006-07-01
Sand samples proceeding from Descalvado, Sao Paulo, were studied with regard to their dosimetric properties using the thermoluminescence technique (TL) for high doses. These sand samples present steady physical and chemical characteristics to the end items, and they are used in the glass industry and for casting. The TL curves of the samples were obtained after an irradiation at the Gamma-Cell system ({sup 60} Co), of IPEN. The glow curves present two peaks at 80 C and 220 C approximately. Calibration curves were obtained for doses between 50 Gy and 5 kGy. The results indicate that the sand samples can be used for high-doses dosimetry in several areas of applications of ionizing radiation. (Author)
3. Development tendencies of moulding and core sands
Directory of Open Access Journals (Sweden)
Stanislaw M. Dobosz1
2011-11-01
Full Text Available Further development of the technology for making moulding and core sands will be strictly limited by tough requirements due to protection of the natural environment. These tendencies are becoming more and more tense, so that we will reach a point when even processes, that from technological point of view fulfill high requirements of the foundry industry, must be replaced by more ecologically-friendly solutions. Hence, technologies using synthetic resins as binding materials will be limited. This paper presents some predictable development tendencies of moulding and core sands. The increasing role of inorganic substances will be noticed, including silicate binders with significantly improved properties, such as improved knock-out property or higher reclamation strength. Other interesting solutions might also be moulding sands bonded by geo-polymers and phosphate binders or salts and also binders based on degradable biopolymers. These tendencies and the usefulness of these binders are put forward in this paper.
4. Planet-wide sand motion on mars
Science.gov (United States)
Bridges, N.T.; Bourke, M.C.; Geissler, P.E.; Banks, M.E.; Colon, C.; Diniega, S.; Golombek, M.P.; Hansen, C.J.; Mattson, S.; McEwen, A.S.; Mellon, M.T.; Stantzos, N.; Thomson, B.J.
2012-01-01
Prior to Mars Reconnaissance Orbiter data, images of Mars showed no direct evidence for dune and ripple motion. This was consistent with climate models and lander measurements indicating that winds of sufficient intensity to mobilize sand were rare in the low-density atmosphere. We show that many sand ripples and dunes across Mars exhibit movement of as much as a few meters per year, demonstrating that Martian sand migrates under current conditions in diverse areas of the planet. Most motion is probably driven by wind gusts that are not resolved in global circulation models. A past climate with a thicker atmosphere is only required to move large ripples that contain coarse grains. ?? 2012 Geological Society of America.
5. In vivo antioxidant effect of aqueous root bark, stem bark and leaves extracts of Vitex doniana in CCl4 induced liver damage rats
Directory of Open Access Journals (Sweden)
2013-05-01
Conclusion: The result of the present study suggests that application of V. doniana plant would play an important role in increasing the antioxidant effect and reducing the oxidative damage that formed both in liver and in kidney tissues. However stem bark has potential to improve renal function in normal rats.
6. Photochemical oxidant injury and bark beetle coleoptera scolytidae infestation of ponderosa pine. I. Incidence of bark beetle infestation in injured trees
Energy Technology Data Exchange (ETDEWEB)
Stark, R.W.; Miller, P.R.; Cobb, F.W. Jr.; Wood, D.L.; Parmeter, J.R. Jr.
1968-05-01
A total of 107 beetle-killed and 963 nearest-neighbor ponderosa pines were examined to determine the association between severity of atmospheric pollution injury and infestation by bark beetles. Trees exhibiting advanced symptoms of pollution injury were most frequently infested by the western pine beetle, Dendroctonus brevicomis, and the mountain pine beetle, D. ponderosae. The degree of injury and incidence of bark beetle infestation were not related to total height, diameter, length of live and dead crown or crown class. As severity of oxidant injury increased, live crown ratio decreased and incidence of bark beetle infestation increased. One hundred noninfested trees in each of three disease categories, advanced, intermediate, and healthy, were examined for evidence of prior beetle attacks. Thirty-six percent of the advanced-diseased trees versus only 5% of the healthy trees were attacked. Thus, the beetles may discriminate between healthy and diseased trees at a distance, upon contact with the host, or both. These studies indicate strongly that atmospheric pollution injury predisposes ponderosa pine to bark beetle infestations. 3 references, 7 tables.
7. Effects of Bark Beetle Infestation on Secondary Organic Aerosol Precursors in the Western United States
Science.gov (United States)
Huff Hartz, K. E.; Amin, H.; Dodson, C.; Atkins, P. T.; Hallar, G.
2009-12-01
Bark beetles are a potentially destructive force in forest ecosytems; however, it is not known how insect attacks affect the atmosphere. Other insects, such as the weevil (Strophosoma melanogrammum) attacks on spruce trees in Denmark, have a significant local effect on monoterpene emissions. In fact, a single weevil induced a three-fold increase in monoterpene emission, and the response lasted for several weeks. Mountain pine bark beetles (Dendroctonus ponderosae) have infested the forests in the vicinity of Storm Peak Laboratory near Steamboat Springs, Colorado. Emissions were sampled from the headspace of bark at the trunk and from the tree branches in the canopy from bark beetle infested and healthy lodgepole pine (Pinus contorta var. latifolia) and Engelmann spruce (Picea engelmannii) trees. The emissions were collected onto scent traps, containing 110 mg of Porapak Q sorbent, using PAS-500 micro air samplers set to a 0.4 mL/min flow rate for two hours. After collection, the scent traps were spiked with a recovery standard, perdeutrated decane, and extracted with 1.5 mL hexanes (in three portions). The analytes in the extracts were separated and detected using gas chromatography/mass spectroscopy. The analytes were identified and quantified using calibration curves from authentic standards, and when authentic standards were not available, the NIST mass spectra library and Adams retention time indices were used. The samples from lodgepole pine trees suggest an enhancement in the 3-carene, beta-phellandrene, and estragole (methyl chavicol) emissions upon bark beetle infestation. The samples from the Engelmann spruce trees suggest an enhancement in the 1,4-cineole, p-cymene, and beta-phellandrene emissions upon bark beetle infestation. A shift in the type and the quantity of VOC emissions due to bark beetle infestation may lead increases in SOA from these forests, since potent SOA precursors are produced.
8. Influence of bark pH on the occurrence and distribution of tree canopy myxomycete species.
Science.gov (United States)
Everhart, Sydney E; Keller, Harold W; Ely, Joseph S
2008-01-01
This study compares the occurrence and distribution of myxomycete species in the canopy of living trees and neighboring grapevines. Corticolous myxomycetes of three temperate forests in southeastern USA were studied on six tree species (30 trees) and grapevines (30 vines) to determine distribution and occurrence of myxomycete species relating to geographic location, host species, and bark pH. The double-rope climbing technique was used to access the canopy and sample bark up to 16.5 m. Bark samples were examined in 580 moist chamber cultures and 44 myxomycete species were identified representing 21 genera, averaging 3.0 +/- 2.1 species per sample site. Jaccard's coefficient determined community similarity between five individuals of six tree species, Acer saccharum, Fraxinus americana, Liquidambar styraciflua, Liriodendron tulipifera, Platanus occidentalis and Tsuga canadensis, and neighboring grapevines, Vitis aestivalis and V. vulpina. Vertical variation in species richness was significantly different only for Platanus occidentalis and might be attributable to flaking of bark with increasing height in the canopy. Tsuga canadensis and neighboring grapevines had greatest community similarity. Cribraria violacea was observed on all tree and grapevine species except T. canadensis and neighboring grapevines. Occurrence and species assemblages of myxomycetes were associated with bark pH, not geographic location. Bark of V. aestivalis (pH 4.5) was more acidic than neighboring T. canadensis (pH 4.1), compared to grapevines of the same species neighboring other tree species. Results indicated that most species are not regionally restricted, and although some myxomycetes are associated with a certain pH range, others develop on any substratum. Future research protocols for corticolous myxomycetes should emphasize sampling adequate amounts of substrata in a local region from different host species that have a wide range of bark pH, ensuring a representative sample of
9. Antioxidant and antimutagenic activities of bark extract of Terminalia arjuna
Institute of Scientific and Technical Information of China (English)
Santosh Kumar Vaidya; Ramesh C; Nandakumar Krishnadas; Srinath Rangappa
2010-01-01
Objective: The alcoholic extract of stem bark of Terminalia arjuna (ALTA) was screened for antioxidant and antimutagenic (anticlastogenic) activity. Methods: Antioxidant property was determined by 1,1,Diphynyl,2-Picryl hydrazyl (DPPH) assay, super oxide radical scavenging activity, lipid peroxidation assay and total polyphenolic content was determined by Folin-Ciocalteau's reagent. Antimutagenic activity was evaluated using micronucleus test in mice. Results: The ALTA has shown potent antioxidant activity with EC50 of 2.491±0.160, 50.110±0.150 &71.000±0.250 in DPPH assay, superoxide radical scavenging activity and lipid peroxidation assay, which is comparable with ascorbic acid with EC50 of 2.471±0.140, 40.500±0.390 and 63.000±0.360 respectively. In micronucleus test, ALTA (100 & 200 mg/kg, p.o.) showed significant reduction in percentage of micronucleus in both polychromatic erythrocytes (PCE) and normochromatic erythrocytes (NCE) and also shown significant reduction in P/N ratio. Conclusions: These results suggested that ALTA possess significant antioxidant and antimutagenic activity.
10. Cardiac stimulant activity of bark and wood of Premna serratifolia
Directory of Open Access Journals (Sweden)
Rekha Rajendran
2008-06-01
Full Text Available Premna serratifolia Lin., (Verbenaceae contains alkaloids and iridoid glycoside and is believed to prevent cardiovascular disease. The stem-bark and stem-wood were extracted with 95% ethanol and distilled water. These extracts were screened for their effects by Isolated Frog Heart Perfusion Technique and biochemical parameters in heart tissue and serum of albino rats after administering the extracts for 7 days. The ethanol extract produced significant positive ionotropic and negative chronotropic actions similar to that of digoxin on frog heart and its effect was inhibited by nifedipine but not by propranolol. A significant decrease in membrane Na+K+ATPase and Mg2+ATPase and an increase in Ca2+ATPase further confirmed its cardiotonic activity. Aqueous extract produced positive ionotropic and chronotropic effects similar to that of adrenaline and its effect was antagonized by propranolol and nifedipine. The results suggest that the ethanol extract produced cardiotonic effect and the aqueous extract produced β-adrenergic effect.
11. Extraction and Hydrophobic Modification of Cotton Stalk Bark Fiber
Directory of Open Access Journals (Sweden)
Ya-Yu Li
2016-01-01
Full Text Available Cotton stalk bark fiber (CSBF was extracted at high temperature and under high pressure, under the condition of the alkali content of 11 wt%. Experimental results proved that the extraction yield of CSBF was 27.3 wt%, and the residual alkali concentration was 2.1 wt%. Then five kinds of modifiers including methyl methacrylate (MMA, MMA plus initiator, epoxy propane, copper ethanolamine, and silane coupling agent were chosen to modify the surface of CSBF. It was found by measuring water retention value (WRV that these five kinds of modifiers were all effective and the silane coupling agent was best modifier among all. The optimal modifying conditions of silane coupling agent were obtained: modifier concentration was 5%, the mixing temperature was 20°C, the mixing time was 1 h, and vacuum drying time was 1 h. Under the optimal condition, the WRV of the modified CSBF was 89%. It is expected that these modified CSBF may be a filler with strengthening effect in wood plastic composites (WPC fields.
12. Antiplasmodial Alkaloids from the Bark of Cryptocarya nigra (Lauraceae
Directory of Open Access Journals (Sweden)
Khalijah Awang
2013-07-01
Full Text Available A dichloromethane extract of the stem bark of Cryptocarya nigra showed strong in vitro inhibition of Plasmodium falciparum growth, with an IC50 value of 2.82 μg/mL. The phytochemical study of this extract has led to the isolation and characterization of four known alkaloids: (+-N-methylisococlaurine (1, atherosperminine (2, 2-hydroxyathersperminine (3, and noratherosperminine (4. Structural elucidation of all alkaloids was accomplished by means of high field 1D- and 2D-NMR, IR, UV and LCMS spectral data. The isolated extract constituents (+-N-methylisococlaurine (1, atherosperminine (2 and 2-hydroxy-atherosperminine (3 showed strong antiplasmodial activity, with IC50 values of 5.40, 5.80 and 0.75 μM, respectively. In addition, (+-N-methylisocolaurine (1 and atherosperminine (2 showed high antioxidant activity in a DPPH assay with IC50 values of 29.56 ug/mL and 54.53 ug/mL respectively. Compounds 1 and 2 also both showed high antioxidant activity in the FRAP assay, with percentages of 78.54 and 70.66 respectively and in the metal chelating assay, with IC50 values of 50.08 ug/mL and 42.87 ug/mL, respectively.
13. Cytotoxic Coumarins from the Bark of Mammea siamensis.
Science.gov (United States)
Ngo, Ngoc Trang Nhu; Nguyen, Vy Thuy; Vo, Hoa Van; Vang, Ole; Duus, Fritz; Ho, Thuy-Duong Huynh; Pham, Hung Dinh; Nguyen, Lien-Hoa Dieu
2010-11-01
A new geranylated coumarin, (E)-4-(1-hydroxypropyl)-5,7-dihydroxy-6-(3,7-dimethyl-2,6-octadienyl)-8-(3-methyl-1-oxobutyl)coumarin (named surangin D), was isolated from the bark of Mammea siamensis collected in Vietnam, along with four known coumarins, surangins B and C, and theraphins B and C, and seven xanthones, 1,7-dihydroxyxanthone, 7-hydroxy-1-methoxyxanthone, 1,7-dimethoxyxanthone, 1,7-dimethoxy-6-hydroxyxanthone, 1,6,7-trihydroxyxanthone, 1,3,7-trihydroxyxanthone, and 1,7-dihydroxy-3-methoxyxanthone. Their structures were determined by spectroscopic methods (mainly 1D- and 2D-NMR) and preparation of methylated derivatives. The four coumarins, surangins C and D and theraphins B and C, were tested for inhibition of cell proliferation in DLD-1 (colon cancer), MCF-7 (breast adenocarcinoma), HeLa (human cervical cancer) and NCI-H460 (human lung cancer) cell lines using the sulforhodamine B (SRB) assay. In all four cell lines, theraphin C showed the strongest activity (IC₅₀ in the range of 1.6-5.7 µM). Testing the anti-proliferative effect of the methylated derivatives showed reduced cellular effects of all derivatives, indicating that the number and position of free hydroxyl groups were very important for the anti-proliferative effect.
14. Cough and Arabinogalactan Polysaccharide from the Bark of Terminalia Arjuna.
Science.gov (United States)
Sivová, V; Bera, K; Ray, B; Nosáľ, S; Nosáľová, G
2016-01-01
In this work we investigated the antitussive activity of the medicinal tree Terminalia arjuna. We used the stem bark for extraction and preparation of water extracted isolate and its two fractions: acetone-soluble (TA-S) and acetone precipitated (TA-P) fraction. The presence of a pectic arabinogalactan was confirmed in TA-P fraction by chromatographic and spectroscopic analysis. The antitussive activity of samples was assessed after oral administration in a dose of 50 mg.kg(-1) in healthy guinea pigs, in which cough was elicited by inhalation of citric acid (0.3 mol/L) in body plethysmograph. The water extracted isolate showed a significant ability to decrease the number of cough efforts by 64.2 %; the antitussive activity on par with that of codeine phosphate. The TA-P fraction showed the antitussive activity of 54.8 %. In contrast, TA-S fraction had only a mild antitussive activity. No changes in in vivo airway resistance were noted. We conclude that arabinogalactan is an essential component of Terminalia arjuna that underlies its antitussive action.
15. Myxomycetes from the bark of the evergreen oak Quercus ilex
Directory of Open Access Journals (Sweden)
Wrigley de Basanta, Diana
1998-06-01
Full Text Available The results of 81 moist chamber cultures of bark from living Quercus ilex trees are reponed. A total of 37 taxa are cited, extending the number of species found on this substrate to 55. The presence of Licea deplanata on the Iberian Península is confirmed. Seven new records are included for the province of Madrid. Some data are contributed on species frequency and incubation times.Se presentan los resultados de 81 cultivos en cámara húmeda de corteza de Quercus ilex vivo. Se citan 37 táxones, que amplían a 55 el número de especies de mixomicetes encontrados sobre este sustrato. Se confirma la presencia en la Península Ibérica de Licea deplanata, y se incluyen siete nuevas citas para la provincia de Madrid. Se aportan datos sobre frecuencia de aparición y tiempos de incubación de algunas especies.
16. Novel oligorhamnosides from the stem bark of Cleistopholis glauca.
Science.gov (United States)
Seidel, V; Bailleul, F; Waterman, P G
2000-01-01
A reinvestigation of the stem bark of Cleistopholis glauca yielded 14 compounds, of which seven were either novel or had not been previously reported from this species. These were identified as the farnesane sesquiterpene methyl-(2E,6E)-10-oxo-3,7, 11-trimethyl-dodeca-2,6-dienoate (1); the azaanthracene alkaloid cleistopholine (4); two partially acetylated oligorhamnoside derivatives, 1-O-dodecanyl-2,3, 4-tri-O-acetyl-alpha-rhamnopyranosyl-(1-->3)-2, 4-di-O-acetyl-alpha-rhamnopyranosyl-(1-->3)-4-O-acetyl-alpha-rhamnopy ranosyl-(1-->4)-alpha-rhamnopyranoside (6) and 1-O-dodecanyl-2, 4-di-O-acetyl-alpha-rhamnopyranosyl-(1-->3)-2, 4-di-O-acetyl-alpha-rhamnopyranosyl-(1-->3)-4-O-acetyl-alpha-rhamnopy ranosyl-(1-->4)-alpha-rhamnopyranoside (8), for which the trivial names cleistetroside-7 and cleistetroside-6 were assigned, respectively; the dihydrobenzofuran neolignan rel-(2alpha, 3beta)-7-O-methylcedrusin (12); and the flavonoids dihydroquercetin (13) and quercetin (14). Structure assignments of all compounds were established by spectroscopic methods and comparison with published data. The chemosystematic significance of the occurrence of the isolated components is mentioned. Compounds 1, 6, and 8 are novel natural products.
17. Evaluation of cytotoxic activity of barks of Mimusops elengi
Directory of Open Access Journals (Sweden)
Santosh Subhash Bhujbal
2011-10-01
Full Text Available Mimusops elengi is a small or large evergreen tree (Sapotaceae of western peninsula and is found in south India. It has been in use in the indigenous system of medicine since antiquity as a specific cure for the diseases of gum and teeth. The drug has been reported to be bitter, astringent, tonic, febrifuge, and as a cure for dysentery and constipation. The cytotoxic effects of ethanolic extract of barks of M. elengi was investigated on meristimatic cells of root tips of Allium cepa. The experiment was carried out by using different concentrations (2.5, 5, 10 mg/mL of standard cytotoxic drug cyclophosphamide and ethanolic extract. After 48 h and 96 h root length and mitotic index were calculated. The photomicrographs had shown the chromosomal abnormalities, stickiness, etc. with increasing concentration of ethanolic extract. The results of the presented study revealed that there is a significant decrease in percent mitotic index and root length of A. cepa with respective time and with increasing concentration.
18. Immunostimulatory effect of Mimusops elengi Linn stem bark in mice
Directory of Open Access Journals (Sweden)
Rakesh S Shivatare
2014-01-01
Full Text Available Objectives: To scrutinise the immunostimulatory activity of methanolic extract of bark of Mimusops elengi Linn (MEMEL in mice. Materials and Methods: The MEMEL was administered orally at the dose of 10, 20, 40 mg/kg/day body weight in mice. The immunostimulatory activities on specific and non-specific immunity were studied by carbon clearance test (CCT, haemagglutination antibody (HA and delayed type hypersensitivity, using sheep red blood cells (SRBC as the antigen. Distilled water served as a control in all the tests and vitamin E 150 mg/kg was used as standard. Result: Oral administration of MEMEL showed a dose-dependent increased immunostimulatory response. Phagocytic index was found to be increased significantly (P < 0.01 in CCT. The production of circulatory antibody titre (humoral antibody response was increased significantly (P < 0.01 and delayed type hypersensitivity reaction was found to be augmented less significantly (P < 0.05 by increasing the mean footpad thickness at 48 hr in response to SRBC as an antigen. Conclusion: This finding suggests that the MEMEL possesses potential for augmenting immune activity by cellular and humoral-mediated mechanisms.
19. Undrained Cyclic Behaviour of Dense Frederikshavn Sand
DEFF Research Database (Denmark)
Nielsen, Søren Kjær; Ibsen, Lars Bo; Sørensen, Kris Wessel
2013-01-01
A modified contour diagram is created for the Frederikshavn Sand in the undrained case for a relative density of ID = 80 %. It can be used to estimate the number of cycles to failure for a given combination of pore pressure, average and cyclic load ratio. The diagram is based on a series of undra......A modified contour diagram is created for the Frederikshavn Sand in the undrained case for a relative density of ID = 80 %. It can be used to estimate the number of cycles to failure for a given combination of pore pressure, average and cyclic load ratio. The diagram is based on a series...
20. Sand control systems used in completing wells
Directory of Open Access Journals (Sweden)
Gabriel Wittenberger
2005-12-01
Full Text Available Expandable Tubular Technology is transforming the face of well completion and construction. This technology provides: a substantially higher hydrocarbon production rates from the reservoir, a reduced well drilling and construction costs, new possibilities for previously unreachable or uneconomic reservoirs, and step a change towards the single diameter well. ESS (Expandable Sand Screen has an unrivalled performance worldwide for delivering a reliable sand control in a wide range of applications. Well costs typically cut by over 20 %, and the productivity increases up to 70 %.
1. On the Size Distribution of Sand
DEFF Research Database (Denmark)
Sørensen, Michael
2016-01-01
-distribution, by taking into account that individual grains do not have the same travel time from the source to the deposit. The travel time is assumed to be random so that the wear on the individual grains vary randomly. The model provides an interpretation of the parameters of the NIG-distribution, and relates the mean......A model is presented of the development of the size distribution of sand while it is transported from a source to a deposit. The model provides a possible explanation of the log-hyperbolic shape that is frequently found in unimodal grain size distributions in natural sand deposits, as pointed out...
2. George Sand [Reseña
OpenAIRE
Jack, Belinda; Thomas, Florence
2002-01-01
Belinda Jack nos cuenta en ese libro la vida de George Sand (de su verdadero nombre Aurora Dupin), esa mujer libertaria del siglo XIX, lo años de su nacimiento, su infancia, su adolescencia y su vida adulta. Una vida tan llena tanto por sus luchas interiores -Sand es una mujer que desde su adolescencia tratará de romper los fatalismos ligados a la condición de mujer del siglo XIX, un siglo profundamente familista y maternalista- como por su inmensa obra literaria que cuenta más de cincuenta n...
3. Investigation of Sand-Cement Grouts
Science.gov (United States)
1960-09-01
the sianAS. Ho-4, VVers thia pacification ,Jlowi -inI r.ver,4 e ofl 3 :*- cen~t to be retain(v,- on1 the NO,. 1E6 sieve. 3y * :.Oviiq- (1),, sc...325 material as does the traprock or silica sand. This j J: i3 -robably the reason for the difference in the quantity of sand founud pmrnable. The three...deficient in material assing th.e ±,e h DOsieve, Ath the addition of percentages of fŕ. ash was test-ilwped. in the other to-ts in this phase, tne
4. TURBULENT COHERENT STRUCTURES IN CHANNELS WITH SAND WAVES
Institute of Scientific and Technical Information of China (English)
2001-01-01
Sand wave bed is one of the typical shape of complicated boundaries in hydraulics and river dynamics, and sand wave motion is the main form of the bed load motion in-rivers, thence the study of turbulent structures over sand waves is of importance both in theory and practice. In this paper turbulent coherent structures over single-and multi-sand waves were studied experimentally, the formulae for the separation length and vortex shedding period of the turbulent flow over single-sand wave were suggested, and the characteristics of turbulent coherent structures over multi-sand waves were also given.
5. Threshold for sand mobility on Mars calibrated from seasonal variations of sand flux
Science.gov (United States)
Ayoub, F.; Avouac, J.-P.; Newman, C. E.; Richardson, M. I.; Lucas, A.; Leprince, S.; Bridges, N. T.
2014-09-01
Coupling between surface winds and saltation is a fundamental factor governing geological activity and climate on Mars. Saltation of sand is crucial for both erosion of the surface and dust lifting into the atmosphere. Wind tunnel experiments along with measurements from surface meteorology stations and modelling of wind speeds suggest that winds should only rarely move sand on Mars. However, evidence for currently active dune migration has recently accumulated. Crucially, the frequency of sand-moving events and the implied threshold wind stresses for saltation have remained unknown. Here we present detailed measurements of Nili Patera dune field based on High Resolution Imaging Science Experiment images, demonstrating that sand motion occurs daily throughout much of the year and that the resulting sand flux is strongly seasonal. Analysis of the seasonal sand flux variation suggests an effective threshold for sand motion for application to large-scale model wind fields (1-100 km scale) of τs=0.01±0.0015 N m-2.
6. High ice nucleation activity located in blueberry stem bark is linked to primary freeze initiation and adaptive freezing behaviour of the bark.
Science.gov (United States)
Kishimoto, Tadashi; Yamazaki, Hideyuki; Saruwatari, Atsushi; Murakawa, Hiroki; Sekozawa, Yoshihiko; Kuchitsu, Kazuyuki; Price, William S; Ishikawa, Masaya
2014-07-31
Controlled ice nucleation is an important mechanism in cold-hardy plant tissues for avoiding excessive supercooling of the protoplasm, for inducing extracellular freezing and/or for accommodating ice crystals in specific tissues. To understand its nature, it is necessary to characterize the ice nucleation activity (INA), defined as the ability of a tissue to induce heterogeneous ice nucleation. Few studies have addressed the precise localization of INA in wintering plant tissues in respect of its function. For this purpose, we recently revised a test tube INA assay and examined INA in various tissues of over 600 species. Extremely high levels of INA (-1 to -4 °C) in two wintering blueberry cultivars of contrasting freezing tolerance were found. Their INA was much greater than in other cold-hardy species and was found to be evenly distributed along the stems of the current year's growth. Concentrations of active ice nuclei in the stem were estimated from quantitative analyses. Stem INA was localized mainly in the bark while the xylem and pith had much lower INA. Bark INA was located mostly in the cell wall fraction (cell walls and intercellular structural components). Intracellular fractions had much less INA. Some cultivar differences were identified. The results corresponded closely with the intrinsic freezing behaviour (extracellular freezing) of the bark, icicle accumulation in the bark and initial ice nucleation in the stem under dry surface conditions. Stem INA was resistant to various antimicrobial treatments. These properties and specific localization imply that high INA in blueberry stems is of intrinsic origin and contributes to the spontaneous initiation of freezing in extracellular spaces of the bark by acting as a subfreezing temperature sensor. Published by Oxford University Press on behalf of the Annals of Botany Company.
7. MouldingSandDB – a modern database storing moulding sands properties research results
Directory of Open Access Journals (Sweden)
J. Jakubski
2011-01-01
Full Text Available The complexity of foundry processes requires the use of modern, advanced IT tools for optimization, storage and analysis of t echnicaldata. Properties of moulding and core sands that are collected in research laboratories, manufacturers, and finally in the foundries, are not in use later on. It seems important to create a database that will allow to use the results stored, along with the possibility of searching according to set criteria, adjusted to casting practice. This paper presents part of the database named „MouldingSandDB”, which allows to collect and search data for synthetic moulding sands.
8. Real-Time Simulation of Aeolian Sand Movement and Sand Ripple Evolution: A Method Based on the Physics of Blown Sand
Institute of Scientific and Technical Information of China (English)
Ning Wang; Bao-Gang Hu
2012-01-01
Simulation and visualization of aeolian sand movement and sand ripple evolution are a challenging subject.In this paper,we propose a physically based modeling and simulating method that can be used to synthesize sandy terrain in various patterns.Our method is based on the mechanical behavior of individual sand grains,which are widely studied in the physics of blown sand.We accounted significant mechanisms of sand transportation into the sand model,such as saltation,successive saltation and collapsing,while simplified the vegetation model and wind field model to make the simulation feasible and affordable.We implemented the proposed method on the programming graphics processing unit (GPU) to get real-time simulation and rendering.Finally,we proved that our method can reflect many characteristics of sand ripple evolution through several demonstrations.We also gave several synthesized desert scenes made from the simulated height field to display its significance on application.
9. Genotype variation in bark texture drives lichen community assembly across multiple environments.
Science.gov (United States)
Lamit, L J; Lau, M K; Naesborg, R Reese; Wojtowicz, T; Whitham, T G; Gehring, C A
2015-04-01
A major goal of community genetics is to understand the influence of genetic variation within a species on ecological communities. Although well-documented for some organisms, additional research is necessary to understand the relative and interactive effects of genotype and environment on biodiversity, identify mechanisms through which tree genotype influences communities, and connect this emerging field with existing themes in ecology. We employ an underutilized but ecologically significant group of organisms, epiphytic bark lichens, to understand the relative importance of Populus angustifolia (narrowleaf cottonwood) genotype and environment on associated organisms within the context of community assembly and host ontogeny. Several key findings emerged. (1) In a single common garden, tree genotype explained 18-33% and 51% of the variation in lichen community variables and rough bark cover, respectively. (2) Across replicated common gardens, tree genotype affected lichen species richness, total lichen cover, lichen species composition, and rough bark cover, whereas environment only influenced composition and there were no genotype by environment interactions. (3) Rough bark cover was positively correlated with total lichen cover and richness, and was associated with a shift in species composition; these patterns occurred with variation in rough bark cover among tree genotypes of the same age in common gardens and with increasing rough bark cover along a -40 year tree age gradient in a natural riparian stand. (4) In a common garden, 20-year-old parent trees with smooth bark had poorly developed lichen communities, similar to their 10-year-old ramets (root suckers) growing in close proximity, while parent trees with high rough bark cover had more developed communities than their ramets. These findings indicate that epiphytic lichens are influenced by host genotype, an effect that is robust across divergent environments. Furthermore, the response to tree genotype is
10. Frequent, Low-Intensity Fire Increases Tree Defense To Bark Beetles
Science.gov (United States)
Hood, S.; Sala, A.
2013-12-01
Wildfire and bark beetles are the two largest disturbance agents in North American conifer forests and have interacted for millennia to drive forest composition, structure, and ecological processes. Recent widespread mortality in western coniferous forests due to bark beetle outbreaks have been attributed in part to increasing temperatures and drought associated with global climate change. In fire-dependent forests, fire exclusion has also led to uncharacteristically dense forests which are also thought to be more susceptible to bark beetle outbreaks due to increased drought stress in individual trees. These mortality events have spurred strong interest in the interaction of fire and bark beetles in driving forest dynamics under a changing climate. However, a fact that has not received adequate attention is whether fire exclusion in fire-dependent forests decreases allocation to tree defense, thereby making contemporary forests more prone to bark beetle outbreaks, regardless of climate and stand structure. Fire is known to increase constitutive resin production in many tree species, yet the impact of frequent fire on expression of better defended tree phenotypes has never been examined. We hypothesized that frequent, low-intensity fire increases tree resistance to bark beetle attack through systemic induced resistance. Using a combination of sampling in natural stands for which we had long-term fire history data and an experimental block design of four thinning and burning treatments, we examined the influence of fire and water stress on tree defense to determine if frequent fire increases tree defense and the degree to which water stress modulates this response. We used axial resin ducts as the measure of defense, as this is where resin is both stored and manufactured in Pinaceae. Resin duct production and density has also been shown to be a better indicator of mortality from bark beetle attacks than tree growth. Resin duct density increased after fire at all
11. Simulation of aeolian sand saltation with rotational motion
Science.gov (United States)
Huang, Ning; Wang, Cong; Pan, Xiying
2010-11-01
In this work, we propose a theoretical model based on the distribution functions of initial liftoff velocity and angular velocity of sand grains to describe a sand saltation process in which both wind field-sand grain coupling and the Magnus force experienced by saltating sand grains have been incorporated. The computation results showed that the Magnus force had significant effects on sand grain saltation. In particular, when the Magnus force was incorporated, the calculated sand transport fluxes and sand transport rate per unit width were closer to the experimental value than when this force was excluded. The sand transport flux is enhanced because the Magnus force owing to particle rotation causes the particles to have higher and longer trajectories, so the particles can get more speed and energy from the wind, which leads to a larger sand transport flux. In addition, it was found that when taking the Magnus force into account, the probability density of the impact velocity and angular velocity of saltating sand grains followed an exponential distribution and a unimodal asymmetric distribution, respectively. Moreover, the sand energy flux increased with the height above the sand surface until the energy flux reached its maximum and then decreased. Furthermore, the energy flux near the ground surface decreased as the grain diameter increased, but beyond a specific height the energy flux increased with the grain diameter. Finally, for the same sand grain diameter, the energy flux increased with the friction velocity.
12. Equations of bark thickness and volume profiles at different heights with easy-measurement variables
Energy Technology Data Exchange (ETDEWEB)
Cellini, J. M.; Galarza, M.; Burns, S. L.; Martinez-Pastur, G. J.; Lencinas, M. V.
2012-11-01
The objective of this work was to develop equations of thickness profile and bark volume at different heights with easy-measurement variables, taking as a study case Nothofagus pumilio forests, growing in different site qualities and growth phases in Southern Patagonia. Data was collected from 717 harvested trees. Three models were fitted using multiple, non-lineal regression and generalized linear model, by stepwise methodology, iteratively reweighted least squares method for maximum likelihood estimation and Marquardt algorithm. The dependent variables were diameter at 1.30 m height (DBH), relative height (RH) and growth phase (GP). The statistic evaluation was made through the adjusted determinant coefficient (r2-adj), standard error of the estimation (SEE), mean absolute error and residual analysis. All models presented good fitness with a significant correlation with the growth phase. A decrease in the thickness was observed when the relative height increase. Moreover, a bark coefficient was made to calculate volume with and without bark of individual trees, where significant differences according to site quality of the stands and DBH class of the trees were observed. It can be concluded that the prediction of bark thickness and bark coefficient is possible using DBH, height, site quality and growth phase, common and easy measurement variables used in forest inventories. (Author) 23 refs.
13. The interaction of Saccharomyces paradoxus with its natural competitors on oak bark.
Science.gov (United States)
Kowallik, Vienna; Miller, Eric; Greig, Duncan
2015-04-01
The natural history of the model yeast Saccharomyces cerevisiae is poorly understood and confounded by domestication. In nature, S. cerevisiae and its undomesticated relative S. paradoxus are usually found on the bark of oak trees, a habitat very different from wine or other human fermentations. It is unclear whether the oak trees are really the primary habitat for wild yeast, or whether this apparent association is due to biased sampling. We use culturing and high-throughput environmental sequencing to show that S. paradoxus is a very rare member of the oak bark microbial community. We find that S. paradoxus can grow well on sterile medium made from oak bark, but that its growth is strongly suppressed when the other members of the community are present. We purified a set of twelve common fungal and bacterial species from the oak bark community and tested how each affected the growth of S. paradoxus in direct competition on oak bark medium at summer and winter temperatures, identifying both positive and negative interactions. One Pseudomonas species produces a diffusible toxin that suppresses S. paradoxus as effectively as either the whole set of twelve species together or the complete community present in nonsterilized oak medium. Conversely, one of the twelve species, Mucilaginibacter sp., had the opposite effect and promoted S. paradoxus growth at low temperatures. We conclude that, in its natural oak tree habitat, S. paradoxus is a rare species whose success depends on the much more abundant microbial species surrounding it.
14. [Polybrominated diphenyl ethers in camphor bark from speedy developing urban in Jiangsu Province].
Science.gov (United States)
Shi, Shuang-Xin; Zeng, Liang-Zi; Zhou, Li; Zhang, Li-Fei; Zhang, Ting; Dong, Liang; Huang, Ye-Ru
2011-09-01
Polybrominated Diphenyl Ethers (PBDEs) were measured in camphor bark samples from 40 locations in Suzhou, Nantong and Wuxi, Jiangsu Province. The samples were extracted by accelerated solvent extraction (ASE) and analyzed using gas chromatography/mass spectrometry (GC-MS). The 8 PBDEs were detected in all samples and the average concentrations of total PBDEs (BDE28, 47, 100, 99, 153, 154, 183, 209) was 835 microg/kg lipid weight (ranged from 112 to 7 460 microg/kg lipid weight). The BDE209 was the main homologues and accounted for 65.7% -99.6% of sigma 8 PBDEs. The predominant commercial products source for PBDEs in bark was Deca-BDE commercial products. Concentration of sigma 8 PBDEs detected in central district of Nantong were significantly higher than those in industrial park, suggesting the discharge of industrial point source might be the main source of PBDEs in this city. No significant difference was found between the levels of sigma 8 PBDEs in camphor bark collected from Suzhou and Wuxi. It can be concluded that the two cities are contaminated interactionally by PBDEs through atmospheric dispersion. The homologue and congener profiles of penta-BDEs for camphor bark were not consistent with commercial products, atmosphere and dust soil, which related with adsorption effect of tree bark and degradation effect of PBDEs.
15. Antivenom potential of ethanolic extract of Cordia macleodii bark against Naja venom
Institute of Scientific and Technical Information of China (English)
Pranay Soni; Surendra H. Bodakhe
2014-01-01
Objective: To evaluate the antivenom potential of ethanolic extract of bark of Cordia macleodii against Naja venom induced pharmacological effects such as lethality, hemorrhagic lesion, necrotizing lesion, edema, cardiotoxicity and neurotoxicity.Methods:Wistar strain rats were challenged with Naja venom and treated with the ethanolic extract of Cordia macleodii bark. The effectiveness of the extract to neutralize the lethalities ofNaja venom was investigated as recommended by WHO. Results: At the dose of 400 and 800 mg/kg ethanolic extract of Cordia macleodii bark significantly inhibited the Naja venom induced lethality, hemorrhagic lesion, necrotizing lesion and edema in rats. Ethanolic extract of Cordia macleodii bark was effective in neutralizing the coagulant and defibrinogenating activity of Naja venom. The cardiotoxic effects in isolated frog heart and neurotoxic activity studies on frog rectus abdominus muscle were also antagonized by ethanolic extract of Cordia macleodii bark.Conclusions:It is concluded that the protective effect of extract of Cordia macleodii against Naja venom poisoning may be mediated by the cardiotonic, proteolysin neutralization, anti-inflammatory, antiserotonic and antihistaminic activity. It is possible that the protective effect may also be due to precipitation of active venom constituents.
16. Associations of Conifer-Infesting Bark Beetles and Fungi in Fennoscandia
Science.gov (United States)
Linnakoski, Riikka; de Beer, Z. Wilhelm; Niemelä, Pekka; Wingfield, Michael J.
2012-01-01
Bark beetles (Coleoptera, Scolytinae) have a widespread association with fungi, especially with ophiostomatoid fungi (Ascomycota) that cause blue staining of wood, and in some cases, serious tree diseases. In Fennoscandia, most studies of these fungi have focused on economically important bark beetle species and this is likely to have led to a biased view of the fungal biodiversity in the region. Recently, the associations between fungi and bark beetles in Fennoscandia have been shown to be more diverse than previously thought. Furthermore, they form complex and dynamic associations that are only now beginning to emerge. This review examines the current knowledge of the rather poorly known interactions between bark beetles, fungi and their conifer host trees in Fennoscandia. The diversity of ophiostomatoid species is discussed and the possible factors that influence the assemblages of fungal associates are considered for all species that are known to occur in the region. For many ophiostomatoid species found in Fennoscandia, little or nothing is known regarding their pathogenicity, particularly if they were to be transferred to new environments. We, therefore, draw attention to the possible threats of timber trade and climate change-induced invasions of new habitats by bark beetles and the fungi that can be moved along with them. PMID:26467956
17. Tests of CP Violation with $\\bar{K^0}$ and $K^{0}$ at LEAR
CERN Multimedia
2002-01-01
% PS195 Tests of CP Violation with &bar.K$^0$ and K$^0$ at LEAR \\\\ \\\\The aim of the experiment is to carry out precision tests of CP, T and CPT on the neutral kaon system through $K ^0 -$\\bar{K}^0 $interferometry using LEAR as an intense source. A beam of$ ~10^{6}~\\bar{p}$~events/second is brought to rest in a hydrogen target producing$ K ^0 $and$ $\\bar{K}^0$ events through the reaction channels : \\\\ \\\\ \\begin{center} $\\bar{p}p~~~~~\\rightarrow~~~~K^0~+~(K^-\\pi^+$) \\\\ \\\\~~~~~~~~$\\rightarrow~~~~\\bar{K}^0~+~(K^+\\pi^-$) \\end{center}\\\\ \\\\The neutral strange particles and their antiparticles are tagged by detecting in the magnetic field the sign of the accompanying charged kaons identified via Cerenkovs and scintillators. The experiment has the unique feature that the decays from particles and antiparticles are recorded under the same operating conditions using tracking chambers and a gas sampling electromagnetic calorimeter. The measured time-dependent $K ^0$-\\bar{K}^0 $asymmetries for non-lepton... 18. Allergic contact dermatitis from salicyl alcohol and salicylaldehyde in aspen bark (Populus tremula). Science.gov (United States) Aalto-Korte, Kristiina; Välimaa, Jarmo; Henriks-Eckerman, Maj-Len; Jolanki, Riitta 2005-02-01 Salicyl alcohol or 2-methylolphenol is a well-known allergen in phenol-formaldehyde resins and a strong sensitizer in guinea pigs. There is 1 previous report of allergic contact dermatitis from salicyl alcohol in aspen bark. We describe a second case with concomitant allergy to salicylaldehyde. An elk researcher who had handled leaves from various trees presented with eczema of the hands, face, flexures, trunk and extremities. Patch testing showed sensitivity to salicyl alcohol, salicylaldehyde, balsam of Peru (Myroxylon pereirae resin), aspen wood dust and an extract prepared from the bark of aspen (Populus tremula). Weaker reactions were observed to bark extracts of rowan (Sorbus aucuparia), tea-leaved willow (Salix phylicifolia) and goat willow (Salix caprea). We analysed salicyl alcohol and salicylaldehyde in the bark extracts and found the 2 chemicals in equal amounts, about 0.9 microg/mg in aspen bark and in lower concentrations in rowan and the willows. We did not find either of the chemicals in the test substance of balsam of Peru (Myroxylon pereirae). Besides salicyl alcohol, salicylaldehyde is also recommended to be used to screen for contact allergy to aspen. Both of these chemicals should be tested in forest workers in areas where aspen is growing. 19. A study on temporal variation of elemental composition in tree barks used as air pollution indicators Energy Technology Data Exchange (ETDEWEB) Santos, Eliane C.; Saiki, Mitiko, E-mail: [email protected], E-mail: [email protected] [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil) 2015-07-01 The study of air pollution using biological matrices has shown that tree barks may be used as biomonitor due to accumulation of aerosol particles on its porous surface. The bark elemental composition can provide information on pollution sources as well as characterize the aerial pollutants from a wide geographical region. The aim of this study was to investigate the variation in elemental composition in barks with time of exposure. Tree barks from Tipuana (Tipuana tipu) and Sibipiruna (Caesalpinia peltophoroides) species were collected in February 2013 and July 2014 in the city of São Paulo. For analysis, the barks were cleaned, grated, ground and analyzed by neutron activation analysis (NAA). Aliquots of samples and synthetic standards of elements were irradiated with thermal neutron flux at the IEA-R1 nuclear research reactor and after a suitable decay time, the induced gamma activities were analyzed by gamma spectrometry. The elements As, Br, Ca, Co, Cr, Cs, Fe, K, La, Rb, Sb, Sc and Zn were determined and the results indicated variability in the concentrations depending on the element, sampling period and also on tree species, indicating that there are not very well defined temporal trends. The quality control of the analytical results evaluated by analyzing INCT Virginia Tobacco Leaves certified reference material (CRM) presented values of |z-score| < 2, indicating that the procedure of NAA applied is suitable for the analyses. (author) 20. Cross-attraction between an exotic and a native pine bark beetle: a novel invasion mechanism? Directory of Open Access Journals (Sweden) Min Lu Full Text Available BACKGROUND: Aside from the ecological impacts, invasive species fascinate ecologists because of the unique opportunities that invasives offer in the study of community ecology. Some hypotheses have been proposed to illustrate the mechanisms that allow exotics to become invasive. However, positive interactions between exotic and native insects are rarely utilized to explain invasiveness of pests. METHODOLOGY/PRINCIPAL FINDINGS: Here, we present information on a recently formed association between a native and an exotic bark beetle on their shared host, Pinus tabuliformis, in China. In field examinations, we found that 35-40% of P. tabuliformis attacked by an exotic bark beetle, Dendroctonus valens, were also attacked by a native pine bark beetle, Hylastes parallelus. In the laboratory, we found that the antennal and walking responses of H. parallelus to host- and beetle-produced compounds were similar to those of the exotic D. valens in China. In addition, D. valens was attracted to volatiles produced by the native H. parallelus. CONCLUSIONS/SIGNIFICANCE: We report, for the first time, facilitation between an exotic and a native bark beetle seems to involve overlap in the use of host attractants and pheromones, which is cross-attraction. The concept of this interspecific facilitation could be explored as a novel invasive mechanism which helps explain invasiveness of not only exotic bark beetles but also other introduced pests in principle. The results reported here also have particularly important implications for risk assessments and management strategies for invasive species. 1. Evaluation of the Antioxidant capacities and Total Phenolic Contents of beech and oak Barks Directory of Open Access Journals (Sweden) R Fazli 2013-05-01 Background & aim: Anti-oxidant compounds prevent prevalence of chronic diseases and food spoiling. The aim of this study was to evaluate the total phenolic and flavonoid content and antioxidant activity of beech and oak barks. Methods: In this experimental study, the skin of beech and oak trees were prepared and then acetone extraction was obtained using Soxhle method. At the beginning, total phenol and flavonoid of extracts were determined and the anti-oxidant properties of the extracts were then evaluated by three methods (methods Biphenyl Pykryl Hydrosol, regenerative power produced- and nitric oxide. Results: The amount of phenolic was higher in bark of beech trees, but flavonoids were higher in oaks. The result of test to trap free radicals of Biphenyl Pykryl Hydrazyl showed the inhibitory concentration 50% of acetone extract of the bark of beech and oak, were 92.19 and 33.7 mg/L respectively. Beech extracts had greater regenerative power than oak. In Nitric oxide trap test acetone extract inhibited 50% in bark of beech trees was 98/23 and the oak extract was 92/90 mg/L respectively. Conclusion: Acetone extract of the bark in three models showed varying degrees of anti - oxidant activity. Beech extract had better antioxidant activity compared with oak extract. Key words: Anti-oxidant Activity, Phenols, Flavonoids, Beech, Oak 2. Exact calculations of a quasi-bound state in the$\\bar{K} \\bar{K} N$system CERN Document Server Shevchenko, N V 2015-01-01 Dynamically exact calculations of a quasi-bound state in the$\\bar{K}\\bar{K}N$three-body system are performed using Faddeev-type AGS equations. As input two phenomenological and one chirally motivated$\\bar{K}N$potentials are used, which describe the experimental information on the$\\bar{K}N$system equally well and produce either a one- or two-pole structure of the$\\Lambda(1405)$resonance. For the$\\bar{K}\\bar{K}$interaction separable potentials are employed that are fitted to phase shifts obtained from two theoretical models. The first one is a phenomenological$\\bar{K}\\bar{K}$potential based on meson exchange, which is derived by SU(3) symmetry arguments from the J\\"ulich$\\pi \\pi - \\bar{K} K$coupled-channels model. The other interaction is a variant of the first one, which is adjusted to the$KK$s-wave scattering length recently determined in lattice QCD simulations. The position and width of the$\\bar{K}\\bar{K}N$quasi-bound state is evaluated in two ways: (i) by a direct pole search in the compl... 3. Shining a light on oil sands production : spectroscopy could bring flash of insight to ore processing Energy Technology Data Exchange (ETDEWEB) Zlotnikov, D. 2010-09-15 Oil sands are a mixture of silts, sands and clay, and the variability poses challenges to surface mine operators. A professor of Earth and Atmospheric Sciences at the University of Alberta has been working on a spectroscopy project to provide the oil sand industry with real-time ore composition and particle size readings from the mine face. These can then be used to adjust processing conditions at the extraction plant or froth treatment facility, ensuring optimal recovery levels and smooth operation. Developing a spectrographic fingerprint of an ore sample involves shining a very narrow wavelength of light at the sample, recording the intensity of reflected light and repeating the process across a range of wavelengths. The challenges of putting the spectroscopic equipment at the mine site were described. The project is 1 of the more than 20 projects currently at the Centre for Oil Sands Innovation (COSI), a partnership between Imperial Oil and the University of Alberta. Imperial contributed$10 million in funding over the following 5 years, with the governments of Alberta and Canada contributing additional funds. Imperial Oil is not the only beneficiary of COSI research, as all work that comes out of COSI is ultimately published. 1 fig.
4. The impact of raindrops on sand
NARCIS (Netherlands)
de Jong, Rianne
2017-01-01
When a raindrop hits a sand bed, it leaves behind a small crater with a mixture of liquid and grains located at the center. This event is frequently observed in nature, but when absent, sprinklers may artificially produce these impacting drops to facilitate irrigation. Also in industry, the interact
5. Cumulative environmental management and the oil sands
Energy Technology Data Exchange (ETDEWEB)
NONE
2005-07-01
In response to concerns regarding the cumulative environmental impacts of oil sands development within the Athabasca oil sands deposit, the government of Alberta established a Regional Sustainable Development Strategy (RSDS) to balance development with environmental protection. The environmental issues identified through the RSDS were addressed by the Cumulative Environmental Management Association (CEMA). CEMA's boundary is the Wood Buffalo region of northeastern Alberta. It identifies existing and future environmental effects in the region and proposes recommendations to regulatory bodies for reducing environmental impacts associated with oil sands development. This presentation outlined some of the 55 stakeholder representatives of CEMA, including Alberta government departments associated with resource development, oil sand developers within the region, and Aboriginal communities and First Nations. These stakeholders provide input on sector priorities and agree on environmental thresholds. Established working groups also address technical and scientific research issues identified in the RSDS such as sustainable ecosystems; surface waters; trace metals and air contaminants; nitrogen oxides and sulphur dioxides; and land reclamation. To date, CEMA has submitted more than 50 reports and has made 4 major environmental recommendations for trace metal management, ecosystem management tools, a framework for acid deposition management, and a landscape design checklist. tabs., figs.
6. LEARNING ABOUT THE OCEANS FROM SAND
Institute of Scientific and Technical Information of China (English)
2011-01-01
As a young geophysicist in the 1980s, Rob Holman attended a conference in San Francisco that included a field trip to a beach. Dr Holman, who grew up inland, stared at the ocean, assessing the strengths of the waves. But when he looked around, everyone else was studying the sand.
7. Displacement pile installation effects in sand
NARCIS (Netherlands)
Beijer-Lundberg, A.
2015-01-01
Installation effects govern the post-installation behaviour of displacement piles in sand. These effects are currently not completely understood. Suitable experimental techniques to model these installation effects include field, laboratory and experimental models. In the current thesis a small-scal
DEFF Research Database (Denmark)
Sabaliauskas, Tomas; Ibsen, Lars Bo
2015-01-01
To engineer efficient structures offshore, we need to extend our knowledge of soil response. Cyclic loading and high water pressure encountered offshore greatly influence cohesionless soil performance. Silty sand from Frederikshavn wind turbine farm was tested using single diameter height samples...
9. Galveston Island, Texas, Sand Management Strategies
Science.gov (United States)
2016-07-01
68 Figure 28. Jetty segment used for computation of aeolian sand transport. Background photograph 22 May 2012...113 Figure 68 . Total shoreline change after 50 years for 500,000 yd3 placed every 2 years in different locations...The berm at Ft. Myers, FL, was constructed with dredged material from Matanzas Pass. The dredged material contained greater than 10% fines, which
10. Building Whales in Sand and Mind.
Science.gov (United States)
Warner, Carolyn
1980-01-01
Describes two-week summer workshops on evolution, adaptation, and behavior of whales, conducted for children by Cold Spring Harbor Whaling Museum (New York), and culminating in creation of life-size sand sculptures of whales. Provides selected list of periodicals, teaching materials, identification guides, records, and societies devoted to whales…
11. Sand transport, erosion and granular electrification
DEFF Research Database (Denmark)
Merrison, J.P.
2012-01-01
The transport of granular materials by wind has a major impact on our environment through sand/soil erosion and the generation and transport of atmospheric dust aerosols. Terrestrially the transport of dust involves billions of tons of material every year, influencing the global climate and impac......The transport of granular materials by wind has a major impact on our environment through sand/soil erosion and the generation and transport of atmospheric dust aerosols. Terrestrially the transport of dust involves billions of tons of material every year, influencing the global climate...... can affect grain transport through the generation of intense electric fields and processes of electrostatic assembly. Importantly the transport of sand is characterized by saltation, which is known to be an active process for erosion and therefore a source for dust and sand formation. Using novel...... erosion simulation techniques the link between grain transport rates and erosion rates has been quantified. Furthermore this can be linked to production rates for dust and has been associated with chemical and mineral alteration through a process of mechanical activation of fractured surfaces. This work...
12. Sand Waves along the Dutch Coast
NARCIS (Netherlands)
Verhagen, H.J.
1989-01-01
Sand waves, defined as longshore wave-like movements of the shoreline, measured in a horizontal plane, are described along several stretches of the shoreline of The Netherlands. They have a celerity in the order of 50-200 m/yr, a period of 50- 150 years and an amplitude of 30- 500 m. They are found
13. Building Whales in Sand and Mind.
Science.gov (United States)
Warner, Carolyn
1980-01-01
Describes two-week summer workshops on evolution, adaptation, and behavior of whales, conducted for children by Cold Spring Harbor Whaling Museum (New York), and culminating in creation of life-size sand sculptures of whales. Provides selected list of periodicals, teaching materials, identification guides, records, and societies devoted to whales…
14. Sand and Stone%沙与石
Institute of Scientific and Technical Information of China (English)
黄川; 孙静
2006-01-01
@@ Astory tells that two friends were walking through the desert. During some point of the journey they had an argument, and one friend slapped the other one in the face1. The one who got slapped was hurt, but without saying anything, he wrote in the sand: "TODAY MY BEST FRIEND SLAPPED ME IN THE FACE."
15. Emission Facilities - Erosion & Sediment Control Facilities
Data.gov (United States)
NSGIC Education | GIS Inventory — An Erosion and Sediment Control Facility is a DEP primary facility type related to the Water Pollution Control program. The following sub-facility types related to...
16. Dark grains of sand: a geological storytelling
Science.gov (United States)
Gallo Maresca, Magda
2017-04-01
In the secondary Italian school the Earth science learning begins at first year, in synergy with other natural science subjects such as Astronomy, Chemistry and Biology. Italian teachers have to focus on the landscape geomorphological aspects and often Earth processes are difficult to display since they are related to certain phenomena happened during the past and often far from the involved country. In order to better understand the environment surrounding us, very simple and poor materials, like sands, allow the teachers to create attractive lab experiences. According to the IBSE (Inquiry Based Science Education) approach, a learning unit has been implemented starting from a walking along the light carbonate beaches of the Adriatic sea: a smart look to the sands ("engage step"), stroke the students fantasy pushing them to explore some strange black grains on the sands. Dirty sands? Or rock landscape, soil degradation and Ofanto river and coastal processes (erosion, transportation and deposition)? This was the teaching challenge. Due to the youngest age, a third level, guided inquiry, was adopted so the teacher is the "guide of inquiry" encouraging the students using the research question ("Why is the sand dark?", "Do all sands look the same?", "Where does it come from?") and driving the students around their investigation plans ("How can I measure grain size?"). A procedure to answer the above questions and validate the results and explanations has been implemented to allow the students to be proactive in their study. During the learning activities will be the students to ask for field trip to elaborate their new knowledge, verify and visualize the speculated processes. The teaching skills allow to address several geosciences domains such as mineralogy, petrology, regional geology and geodynamics as well as other scientific disciplines such as mathematics (more specifically statistics), forensic science and even life sciences (the presence of bioclasts might
17. Assessing environmental impacts of inland sand mining in parts of ...
African Journals Online (AJOL)
Assessing environmental impacts of inland sand mining in parts of Ogun State, Nigeria. ... Sand is a valuable resource for construction and other purposes, however ... Natural resources particularly, land, water quality and quantity, air quality, ...
18. Fiber-reinforced sand strength and dilation characteristics
Directory of Open Access Journals (Sweden)
Hesham M. Eldesouky
2016-06-01
Full Text Available Randomly distributed fiber reinforcement is used to provide an isotropic increase in the sand shear strength. The previous studies were not consistent regarding the fibers effect on the volumetric change behavior of fiber-reinforced sand. In this paper, direct shear tests are conducted on 108 specimens to investigate the effects of the fibers content, relative density, normal stress and moisture content on the shear strength and volumetric change behaviors of fiber-reinforced sand. The study investigates also the possibility of using dry fiber-reinforced sand as an alternative to heavily compacted unreinforced moist sand. The results indicate that the fibers inclusion increases the shear strength and dilation of sand. Moisture suppresses the fibers effect on the peak and post-peak shear strengths, and dilation. Dry loose fiber-reinforced sand achieves the same shear strength of heavily compacted unreinforced moist sand, yet at more than double the horizontal displacement.
19. Gating Technology for Vertically Parted Green Sand Moulds
DEFF Research Database (Denmark)
Larsen, Per
Gating technology for vertically parted green sand moulds. Literature study of different ways of designing gating systems.......Gating technology for vertically parted green sand moulds. Literature study of different ways of designing gating systems....
20. Expandable sand screens: from novel concept to proven sand control technique
Energy Technology Data Exchange (ETDEWEB)
Metcalfe, Paul; Jones, Colin; Ballard, Tracey; Beare, Steve; Hillis, Dave [Weatherford International Inc., Houston, TX (United States)
2004-07-01
Expandable Sand Screens (ESS) have proved a viable alternative to gravel packing for sand control. With over 300 installations worldwide, analysis of their use has confirmed that ESS offers excellent production performance and sand control reliability in Open hole. This paper presents details of a global survey on ESS performance that gives accurate information on production performance, sand exclusion reliability and cost effectiveness in Open hole and cased hole application scenarios. This paper also discusses the role and effect of compliant expansion in observed productivity performance and skin values. The rock mechanical, reservoir characterization and metallurgical requirements of ESS systems are also investigated. Finally, the latest advances of the technology for use within the reservoir are explained. This paper demonstrates how the combination of ESS and Expandable Zonal Isolation devices can offer cased hole functionality (in terms of zonal isolation) in combination with Open hole levels of production performance (from the ESS). (author)
1. Water management in the oil sands industry
Energy Technology Data Exchange (ETDEWEB)
2004-07-01
Water management issues at Alberta's 4 oil sand deposits were discussed. The 4 deposits include the Peace River, Athabasca, Wabasca and Cold Lake deposits, with the Athabasca deposit being the largest and the only surface-mineable deposit. Large quantities of water are needed to extract bitumen from oil sands. This paper addressed water volume withdrawal from the Athabasca River, the primary source of water for the surface-mining oil sands industry. It also addressed Muskeg River watershed integrity, quality of water withdrawn from reclaimed landscapes, groundwater contamination, and ecological viability of end-pit lakes. Currently, half of Syncrude's oil sand is transported from mine to extraction plant by conveyor belts. The other half is pipelined as a warm water slurry. By 2005, all transport will be by pipeline. The oil sand is mixed with hot water, steam and surfactants to condition it for extraction. Seventy-nine per cent of the water used by Syncrude is recycled water and the remainder comes from the Athabasca River. Syncrude diverts 2.5 to 3 barrels of water from the Athabasca River for every barrel of oil produced. This paper discussed the in-stream flow needs of the Athabasca River based on protection of aquatic ecosystems. Flow needs are addressed by the Cumulative Effects Management Association (CEMA). The paper states that the proportion of annual flow withdrawn from the Athabasca River is too low to have a significant impact on aquatic systems, but the main concern lies in water use during low flow periods, typically during the winter months. Developers will likely come under pressure to develop off-site reservoirs to store water for use during these low-flow periods. tabs., figs.
2. Imaging of Acoustic Waves in Sand
Energy Technology Data Exchange (ETDEWEB)
Deason, Vance Albert; Telschow, Kenneth Louis; Watson, Scott Marshall
2003-08-01
There is considerable interest in detecting objects such as landmines shallowly buried in loose earth or sand. Various techniques involving microwave, acoustic, thermal and magnetic sensors have been used to detect such objects. Acoustic and microwave sensors have shown promise, especially if used together. In most cases, the sensor package is scanned over an area to eventually build up an image or map of anomalies. We are proposing an alternate, acoustic method that directly provides an image of acoustic waves in sand or soil, and their interaction with buried objects. The INEEL Laser Ultrasonic Camera utilizes dynamic holography within photorefractive recording materials. This permits one to image and demodulate acoustic waves on surfaces in real time, without scanning. A video image is produced where intensity is directly and linearly proportional to surface motion. Both specular and diffusely reflecting surfaces can be accomodated and surface motion as small as 0.1 nm can be quantitatively detected. This system was used to directly image acoustic surface waves in sand as well as in solid objects. Waves as frequencies of 16 kHz were generated using modified acoustic speakers. These waves were directed through sand toward partially buried objects. The sand container was not on a vibration isolation table, but sat on the lab floor. Interaction of wavefronts with buried objects showed reflection, diffraction and interference effects that could provide clues to location and characteristics of buried objects. Although results are preliminary, success in this effort suggests that this method could be applied to detection of buried landmines or other near-surface items such as pipes and tanks.
3. Incipient Motion of Sand and Oil Agglomerates
Science.gov (United States)
Nelson, T. R.; Dalyander, S.; Jenkins, R. L., III; Penko, A.; Long, J.; Frank, D. P.; Braithwaite, E. F., III; Calantoni, J.
2016-12-01
Weathered oil mixed with sediment in the surf zone in the northern Gulf of Mexico after the 2010 Deepwater Horizon oil spill, forming large mats of sand and oil. Wave action fragmented the mats into sand and oil agglomerates (SOAs) with diameters of about 1 to 10 cm. These SOAs were transported by waves and currents along the Gulf Coast, and have been observed on beaches for years following the spill. SOAs are composed of 70%-95% sand by mass, with an approximate density of 2107 kg/m³. To measure the incipient motion of SOAs, experiments using artificial SOAs were conducted in the Small-Oscillatory Flow Tunnel at the U.S. Naval Research Laboratory under a range of hydrodynamic forcing. Spherical and ellipsoidal SOAs ranging in size from 0.5 to 10 cm were deployed on a fixed flat bed, a fixed rippled bed, and a movable sand bed. In the case of the movable sand bed, SOAs were placed both proud and partially buried. Motion was tracked with high-definition video and with inertial measurement units embedded in some of the SOAs. Shear stress and horizontal pressure gradients, estimated from velocity measurements made with a Nortek Vectrino Profiler, were compared with observed mobility to assess formulations for incipient motion. For SOAs smaller than 1 cm in diameter, incipient motion of spherical and ellipsoidal SOAs was consistent with predicted critical stress values. The measured shear stress at incipient motion of larger, spherical SOAs was lower than predicted, indicating an increased dependence on the horizontal pressure gradient. In contrast, the measured shear stress required to move ellipsoidal SOAs was higher than predicted, even compared to values modified for larger particles in mixed-grain riverine environments. The laboratory observations will be used to improve the prediction of incipient motion, transport, and seafloor interaction of SOAs.
4. The effect of management systems and ecosystem types on bark regeneration in Himatanthus drasticus (Apocynaceae): recommendations for sustainable harvesting.
Science.gov (United States)
Baldauf, Cristina; Maës dos Santos, Flavio Antonio
2014-01-01
Bark and exudates are widely commercialized non-timber forest products. However, the ecological impacts of the harvesting of these products have seldom been studied. The aim of this study is to investigate the relationship of tree resilience to harvesting intensity in Himatanthus drasticus, a tree that is highly exploited in the Brazilian savanna (Cerrado) for its medicinal latex. Although the traded product is the latex, the traditional harvesting systems involve the removal of the bark of the trees to allow exploitation. A 3-year experiment was conducted in two different Cerrado ecosystems (open savanna and savanna woodland). Trees were debarked at four debarking intensities to simulate the effects of traditional management systems. Measurements of bark growth were taken every 6 months, and quantitative and qualitative indexes of bark regeneration were obtained. The mortality of the debarked trees was low and could not be related to the intensity of harvesting. No signs of attack by fungi or insects were recorded. Compared with other species exploited for bark, H. drasticus is very resilient to harvesting; however, bark regeneration is relatively slow. In both analyzed ecosystems, the regeneration indexes showed higher values in the controls than in the treatments, indicating that 3 years is not sufficient for total recovery of the rhytidome. Bark regeneration occurred primarily by sheet growth and was more rapid in open savanna than in savanna woodland. No differences in the rate of bark recovery were found among management treatments. Based on the results, sustainable harvesting guidelines are suggested for the species.
5. Aggregation pheromones of bark beetles, pityogenes quadridens and P. bidentatus, colonizing scotch pine: olfactory avoidance of interspecific competition
Science.gov (United States)
The bark beetles Pityogenes bidentatus and P. quadridens (Coleoptera, Curculionidae, Scolytinae) compete for bark areas on branches of Scotch pine, Pinus sylvestris. Hindguts and head/thoraxes of males and females of both species feeding in hosts were extracted in pentane and analyzed by gas chromat...
6. The complex symbiotic relationships of bark beetles with microorganisms: a potential practical approach for biological control in forestry.
Science.gov (United States)
Popa, Valentin; Déziel, Eric; Lavallée, Robert; Bauce, Eric; Guertin, Claude
2012-07-01
Bark beetles, especially Dendroctonus species, are considered to be serious pests of the coniferous forests in North America. Bark beetle forest pests undergo population eruptions, causing region wide economic losses. In order to save forests, finding new and innovative environmentally friendly approaches in wood-boring insect pest management is more important than ever. Several biological control methods have been attempted over time to limit the damage and spreading of bark beetle epidemics. The use of entomopathogenic microorganisms against bark beetle populations is an attractive alternative tool for many biological control programmes in forestry. However, the effectiveness of these biological control agents is strongly affected by environmental factors, as well as by the susceptibility of the insect host. Bark beetle susceptibility to entomopathogens varies greatly between species. According to recent literature, bark beetles are engaged in symbiotic relationships with fungi and bacteria. These types of relationship are very complex and apparently involved in bark beetle defensive mechanisms against pathogens. The latest scientific discoveries in multipartite symbiosis have unravelled unexpected opportunities in bark beetle pest management, which are discussed in this article.
7. Effects of symbiotic bacteria and tree chemistry on the growth and reproduction of bark beetle fungal symbionts
Science.gov (United States)
A.S. Adams; C.R. Currie; Y. Cardoza; K.D. Klepzig; K.F. Raffa
2009-01-01
Bark beetles are associated with diverse assemblages of microorganisms, many of which affect their interactions with host plants and natural enemies. We tested how bacterial associates of three bark beetles with various types of host relationships affect growth and reproduction of their symbiotic fungi. Fungi were exposed to volatiles...
8. In Vitro and In Vivo Anthelmintic Activity of Acacia nilotica (L. Willd.Ex Delile Bark and Leaves
Directory of Open Access Journals (Sweden)
2011-06-01
Full Text Available This study was carried out to assess the anthelmintic activity of Acacia nilotica bark and leave extracts in different solvents. Adult motility assay, egg hatch test and fecal egg count reduction test were carried out to evaluate the anthelmintic activity. Effect of plant extracts both of leaves and bark of A. nilotica was dose-dependent. Highest mortality of worms was observed 12 hours post-exposure @ 25 mg/ml. Extracts of leaves were more potent than the bark extracts. Ethyle acetate fractions both of bark and leaves exhibited higher anthelmintic effects compared with chloroform, petroleum spirit and aqueous fractions. Crude aqueous methanol extract (CAME of bark (LC50= 201.0032 µg/ml had higher inhibitory effects compared with that of leaves (LC50= 769.2485 µg/ml on egg hatching. Likewise, chloroform and ethyle acetate fractions of A. nilotica bark exhibited higher ovicidal activity. In vivo, maximum reduction (72.01% in fecal egg counts was recorded for CAME of bark followed by CAME of leaves (63.44% @ 8 g/kg at day 12 post-treatment. Results suggest lipophilic nature of the active principles having anthelmintic efficacy in A. nilotica bark and leaves.
9. A PHARMACOLOGICAL STUDY ON THE PREGNANCY TERMINATION EFFECT OF COMPLEX PRESCRIPTION OF ELM WHITE BARK IN ANIMALS
Institute of Scientific and Technical Information of China (English)
NIUXi-Min; LIPci-Quan; ZHANGJian-Guo; YEXue-Min
1989-01-01
Complex prescription of elm white bark is made up of elm white bark and Olibanum, which has been used as a female contraceptive in China. Our animal experimental results showed that it had terminating effect of early, mid and fate pregnancies in
10. A bark-shaving technique to deter rat snakes from climbing red-cockaded woodpecker cavity trees
Science.gov (United States)
Daniel Saenz; Christopher S. Collins; Richard N. Conner
1999-01-01
We developed a bark-shaving technique to deter rat snakes (Elaphe obsoleta) from climbing red-cockaded woodpecker (Picoides borealis) trees as an aesthetically pleasing, more cost-effective, and safer alternative to other snake excluder devices. We used a drawknife to carefully shave the bark around the circumference of 4 treatment trees in a l-m-wide band to...
11. Predicting live and dead basal area in bark beetle-affected forests from discrete-return LiDAR
Science.gov (United States)
Andrew T. Hudak; Ben Bright; Jose Negron; Robert McGaughey; Hans-Erik Andersen; Jeffrey A. Hicke
2012-01-01
Recent bark beetle outbreaks in western North America have been widespread and severe. High tree mortality due to bark beetles affects the fundamental ecosystem processes of primary production and decomposition that largely determine carbon balance (Kurz et al. 2008, Pfeifer et al. 2011, Hicke et al. 2012). Forest managers need accurate data on beetle-induced tree...
12. New triterpenoids from the stem bark of Hypodaphnis zenkeri.
Science.gov (United States)
Momo, Itbert Joseph; Dufat, Thi-Hanh; Wandji, Jean; Michel, Sylvie; Chiozem, David Dako
2013-01-01
A new pentacyclic triterpenoid and three new derivatives based on the taraxer-14-ene skeleton with a C-28 attached a carboxylic acid group have been isolated from the stem bark of Hypodaphnis zenkeri, together with six known compounds. The new product was identified as 2α,3α-dihydroxytaraxer-14-en-28-oic acid (1). Its derivatives, 2α,3α-diacetyltaraxer-14-en-28-oic acid (2), 2α,3α-di-O-carbonyl-2α,3α-dihydroxytaraxer-14-en-28-oic acid (3) and 2α,3α-dipropionyltaraxer-14-en-28-oic acid (4) were obtained by semisynthesis. The known compounds were identified as 3β-hydroxytaraxer-14-en-28-oic acid or aleuritolic acid (5) (McPhail, A.T., McPhail, D.R., Wani, M.C., Wall, M.E. & A.W., Nicholas, A.W. (1989). Identity of maprounic acid with aleuritolic acid. Revision of the structure of maprounic acid: X-ray crystal structure of p-bromobenzyl acetylmaprounate. Journal Natural Products, 52, 212), 3α-hydroxytaraxer-14-en-28-oic acid or isoaleuritolic acid (6), 3α-acetyltaraxer-14-en-28-oic acid acetate or aleuritolic acid acetate (7) (Chaudhuri, S.K., Fullas, F., Brown, D.M., Wani, M.C., Wall, M.E., Cai, L., … Kinghorn, A.D. (1995). Isolation and structural elucidation of pentacyclic triterpenoids from Maprounea africana. Journal of Natural Products, 58, 1-9), 3-oxo-taraxer-14-ene or taraxerone (8) β-sitosterol (9) and stigmasterol (10) (Kamboj & Saluja, 2011), together with fatty acids. Their structures were established on the basis of spectroscopic studies and chemical transformations.
13. Antinociceptive and anti-inflammatory potential of Rhododendron arboreum bark.
Science.gov (United States)
2016-07-01
Rhododendron arboreum Smith. (Ericaceae), an evergreen small tree, is one of the 1000 species that belongs to genus Rhododendron distributed worldwide. In folk medicine, as various parts of this plant exhibit medicinal properties, it is used in the treatment of different ailments.The present study was designed to evaluate the potential anti-inflammatory and antinociceptive effects of methanolic extract of R. arboreum bark, followed by activity-guided fractionation of n-hexane, n-butanol, chloroform, ethyl acetate and aqueous fractions.The ethyl acetate fraction (200 mg/kg i.p.) showed the maximum analgesic effect (82%) in acetic acid-induced writhing, followed, to a less extent, by crude extract and chloroform fraction both at a dose of 200 mg/kg i.p. (65.09% and 67.89%, respectively). In carrageenan-induced mouse paw oedema, the crude extract and its related fractions displayed in a dose-dependent manner (50-200 mg/kg i.p.) an anti-inflammatory activity for all time-courses (1-5 hrs). For the active extract/fractions (200 mg/kg i.p.), the maximum effect was observed 5 h after carrageenan injection. These evidences were also supported by in vitro lipoxygenase inhibitory properties. In conclusion, R. arboreum crude methanolic extract and its fractions exhibited anti-inflammatory and antinociceptive effects. For these reasons, this plant could be a promising source of new compounds for the management of pain and inflammatory diseases. © The Author(s) 2014.
14. In vitro evaluation of antioxidant activity of Cordia dichotoma (Forst f.) bark.
Science.gov (United States)
Nariya, Pankaj B; Bhalodia, Nayan R; Shukla, Vinay J; Acharya, Rabinarayan; Nariya, Mukesh B
2013-01-01
Cordia dichotoma Forst. f. bark, identified as botanical source of Shleshmataka in Ayurvedic pharmacopoeia. Present investigation was undertaken to evaluate possible antioxidant potential of methanolic and butanol extract of C. dichotoma bark. In vitro antioxidant activity of methanolic and butanol extract was determined by 1,1, diphenyl-2, picrylhydrazyl (DPPH) free radical scavenging assay. The extracts were also evaluated for their phenolic contents and antioxidant activity. Phenolic content was measured using Folin-Ciocalteu reagent and was calculated as Gallic acid equivalents. Antiradical activity of methanolic extract was measured by DPPH assay and was compared to ascorbic acid and ferric reducing power of the extract was evaluated by Oyaizu method. In the present study three in vitro models were used to evaluate antioxidant activity. The first two methods were for direct measurement of radical scavenging activity and remaining one method evaluated the reducing power. The present study revealed that the C. dichotoma bark has significant radical scavenging activity.
15. Isolation and identification of antioxidant and hyaluronidase inhibitory compounds from Ficus microcarpa L. fil. bark.
Science.gov (United States)
Ao, Changwei; Higa, Tatsunori; Ming, Hui; Ding, Yu-ting; Tawata, Shinkichi
2010-06-01
The aerial roots and bark of Ficus microcarpa L. fil. have been used as folk herbs for perspiration, alleviating fever, and relieving pain in Okinawa. The methanol extract of its bark showed high antioxidant and potential inhibitory activity against hyaluronidase. It was fractionated into hexane, ethyl acetate, butanol, and water fractions. As the ethyl acetate fraction exhibited the strongest activity, it was selected for further purification by repeated Sephadex LH-20 column chromatography and preparative HPLC. Seven compounds were isolated and identified as protocatechuic acid, chlorogenic acid, methyl chlorogenate, catechin, epicatechin, procyanidin B1, and procyanidin B3 by analysis of ESI-MS, UV, and (1)H- and (13)C-NMR spectra. All isolated compounds showed strong antioxidant activity when tested by all applied methods. Catechin, epicatechin, procyanidin B1, and procyanidin B3 exhibited excellent inhibitory activity against hyaluronidase. The results indicate that the extract of F. microcarpa bark may be utilized as a potential antioxidant and hyaluronidase inhibitor.
16. Simultaneous determination of betulin and betulinic acid in white birch bark using RP-HPLC.
Science.gov (United States)
Zhao, Guoling; Yan, Weidong; Cao, Dan
2007-02-19
A simple procedure is described for the simultaneous extraction and determination of betulin and betulinic acid in white birch bark. The extraction was checked using different solvents: dichloromethane, ethyl acetate, acetone, chloroform, methanol and 95% ethanol (aqueous solution, v/v). It was found 95% ethanol was a good extraction solvent that allowed extraction of triterpenoid with a highest content. Separation was achieved on a reversed phase C(18) column with acetonitrile-water 86:14 (v/v). Detection was accomplished with UV detection at lambda=210 nm. Using this method, the bioactive triterpenoid in white birch bark were simultaneously determined. Significant variations in the content of betulin and betulinic acid in white birch bark growing in different locations of China were also observed.
17. Chemical properties of tannic extracts from bark of Pinus oocarpa and their use as adhesive
Directory of Open Access Journals (Sweden)
Michel Cardoso Vieira
2014-03-01
18. ANTI-INFLAMMATORY AND ANTI-ARTHRITIC ACTIVITIES OF DELONIX ELATA BARK EXTRACTS
Directory of Open Access Journals (Sweden)
G. Murugananthan
2011-06-01
Full Text Available Delonix elata (D. elata, has long been used in traditional herbal medicine for the treatment of arthritis pain. In the present study an attempt was made to study the effect of D. elata barks for its anti-inflammatory and anti-arthritic effect in animal models. Barks were subjected for extraction with pet. ether, chloroform and 40% hydroalcohol successively and evaporated under rotary evaporator to get the concentrated extract. All the extracts were subjected for acute oral toxicity studies in rats and found to be safe up to the dose of 5g/kg body weight. Anti-inflammatory screening by carrageenan-induced paw oedema and cotton pellet induced granuloma method, the hydro alcohol extract of D. elata barks showed significant protection against the inflammation. In Complete Freund’s Adjuvant induced arthritis model also the hydro alcohol exhibited significant protection on day 7 onwards.
19. Optimization of ultrasound-assisted extraction of polyphenols from spruce wood bark.
Science.gov (United States)
Ghitescu, Roxana-Elena; Volf, Irina; Carausu, Constantin; Bühlmann, Ana-Maria; Gilca, Iulian Andrei; Popa, Valentin I
2015-01-01
Here we describe the ultrasound-assisted extraction of the phenolic compounds from spruce wood bark and present a straight-forward experimental planning method, allowing the optimisation of the process. The effect of ethanol concentration, temperature and extraction time were evaluated through a 3(2)·2 experimental planning. The efficiency of the extraction process was appreciated based on factorial ANOVA results. The maximum extraction yield of total polyphenols (13.232mg gallic acid equivalents (GAE)/g of spruce bark tested) was obtained using a process time of 60min, an extraction temperature of 54°C and a concentration of ethanol of 70% respectively. These results indicate that an important quantity of bioactive compounds can be extracted from spruce wood bark by ultrasound assisted extraction technology.
20. Chemical-free Extraction of Cotton Stalk Bark Fibers by Steam Flash Explosion
Directory of Open Access Journals (Sweden)
Xiuliang Hou
2014-10-01
Full Text Available Cotton stalk bark fibers (CSBF were extracted by steam flash explosion, completed within 0.09 s, and the extracted fibers were compared with those obtained by conventional alkaline treatment. Results indicate that the optimum steam pressure was 2.5 MPa when steaming time was set to 2 min for extracting CSBF. Under the optimized conditions, the obtained CSBF had a cellulose content of 72%, length of 48 mm, fineness of 45 dtex, crystallinity index of 68, moisture regain of 8%, water retention of 98%, and tensile strength of 2.4 cN/dtex, which were similar to results obtained by conventional alkaline treatment. Compared with bark of cotton stalks, CSBF had lower moisture regain and water retention, and higher onset decomposition temperature. The results show that moderate steam flash explosion is a chemical-free, quick, and effective method for exploring the industrial applications of bark of cotton stalks as natural cellulose fibers.
1. Analysis of the $B^{+}_{c} \\rightarrow D^{+}_{s} \\bar{K}^{0\\ast}$ decay
2017-01-01
We analysed the process of $B^{+}_{c} \\rightarrow D^{+}_{s} \\bar{K}^{0\\ast}$ using QCD factorization (QCDF) and final-state interaction (FSI) effects. First, the $B^{+}_{c} \\rightarrow D^{+}_{s} \\bar{K}^{0\\ast}$ decay is calculated using QCDF method. The value found by using theQCDF method is less than the experimental value. Then we considered FSI effect as a sizable correction wherethe intermediate state $D^{+}^{\\ast}$ mesons via the exchange of $K^{0}(K^{0}^{\\ast}$) are produced. To consider the amplitudes ofthis intermediate state, the QCDF approach was used. The experimental branching ratio of $B^{+}_{c} \\rightarrow D^{+}_{s} \\bar{K}^{0\\ast}$ decayis less than $0.4 \\times 10^{-6}$ and our results are $(0.21 \\pm 0.04) \\times 10^{7}$ and $(0.37 \\pm 0.05) \\times 10^{6}$ from QCDF and FSI,respectively.
2. Chromatographic fingerprint analysis of yohimbe bark and related dietary supplements using UHPLC/UV/MS.
Science.gov (United States)
Sun, Jianghao; Chen, Pei
2012-03-05
A practical ultra high-performance liquid chromatography (UHPLC) method was developed for fingerprint analysis of and determination of yohimbine in yohimbe barks and related dietary supplements. Good separation was achieved using a Waters Acquity BEH C(18) column with gradient elution using 0.1% (v/v) aqueous ammonium hydroxide and 0.1% ammonium hydroxide in methanol as the mobile phases. The study is the first reported chromatographic method that separates corynanthine from yohimbine in yohimbe bark extract. The chromatographic fingerprint analysis was applied to the analysis of 18 yohimbe commercial dietary supplement samples. Quantitation of yohimbine, the traditional method for analysis of yohimbe barks, were also performed to evaluate the results of the fingerprint analysis. Wide variability was observed in fingerprints and yohimbine content among yohimbe dietary supplement samples. For most of the dietary supplements, the yohimbine content was not consistent with the label claims.
3. Microscopic and UPLC-UV-MS analyses of authentic and commercial yohimbe (Pausinystalia johimbe) bark samples.
Science.gov (United States)
Raman, Vijayasankar; Avula, Bharathi; Galal, Ahmed M; Wang, Yan-Hong; Khan, Ikhlas A
2013-01-01
Yohimbine is the major alkaloid found in the stem bark of yohimbe, Pausinystalia johimbe (Rubiaceae), an evergreen tree native to Africa. The objectives of the current study were to provide a detailed anatomy of yohimbe bark, as well as to determine the quantity of yohimbine in the raw yohimbe products sold online. Twelve commercial raw materials of yohimbe were analyzed by microscopic and ultra performance liquid chromatography-UV-MS methods. The study revealed that three samples were probably adulterated and four other samples contained various levels of impurities. Yohimbine was not detected in one sample, whereas its presence in other samples was found to be in the range 0.1-0.91%. The present work also provides a detailed anatomy of the stem bark of yohimbe, with light and scanning electron microscopy images, for proper identification and authentication.
4. QUANTIFICATION OF PRIMARY AND SECONDARY METABOLITES FROM LEAVES AND STEM BARK OF COCHLOSPERMUM RELIGIOSUM (L ALSTON
Directory of Open Access Journals (Sweden)
Sasikala A
2013-08-01
Full Text Available Phytochemical constituents are responsible for medicinal activity of plant species. Hence the present study quantification of primary and secondary metabolites from leaves and stem bark of Cochlospermum religiosum was carried out. The results showed that the leaf was rich in chlorophylls followed by lipids, proteins and carbohydrates whereas in stem bark highest amount found in chlorophylls followed by carbohydrates, proteins and lipids of primary metabolites. Cochlospermum religiosum leaf was rich in phenols followed by alkaloids, flavonoids and tannins whereas in stem bark highest amount found in phenols followed by flavonoids, alkaloids and tannins of secondary metabolites. The results suggest that phytochemical properties for curing various ailments and possess potential antioxidant, anti-inflammatory, antimicrobial and leads to the isolation of new and novel compounds.
5. Mimusops elengi bark extract mediated green synthesis of gold nanoparticles and study of its catalytic activity
Science.gov (United States)
Majumdar, Rakhi; Bag, Braja Gopal; Ghosh, Pooja
2016-04-01
The bark extract of Mimusops elengi is rich in different types of plant secondary metabolites such as flavonoids, tannins, triterpenoids and saponins. The present study shows the usefulness of the bark extract of Mimusops elengi for the green synthesis of gold nanoparticles in water at room temperature under very mild conditions. The synthesis of the gold nanoparticles was complete within a few minutes without any extra stabilizing or capping agents and the polyphenols present in the bark extract acted as both reducing as well as stabilizing agents. The synthesized colloidal gold nanoparticles were characterized by HRTEM, surface plasmon resonance spectroscopy and X-ray diffraction studies. The synthesized gold nanoparticles have been used as an efficient catalyst for the reduction of 3-nitrophenol and 4-nitrophenol to their corresponding aminophenols in water at room temperature.
6. Characterisation of Ophiostoma species associated with pine bark beetles from Mexico, including O. pulvinisporum sp. nov.
Science.gov (United States)
Zhou, Xudong; de Beer, Z Wilhelm; Cibrian, David; Wingfield, Brenda D; Wingfield, Michael J
2004-06-01
Bark beetles (Coleoptera: Scolytidae) are common vectors of Ophiostoma species. These fungi include primary tree pathogens and important sapstain agents. In Mexico, Ips calligraphus and Dendroctonus mexicanus occur on many species of pine. Pinus maximinoi and P. pseudostrobus are the hosts of both species of insects. Little research has been done on ophiostomatoid fungi associated with pine bark beetles in Mexico. We recently obtained specimens of these bark beetles and their galleries from Mexico. The aim of the study was to isolate and identify Ophiostoma species associated with the two beetle species. In total, six ophiostomatoid species were found to be associated with them. These included Ceratocystiopsis minuta, Ophiostoma pluriannulatum, an O. galeiformis-like species, two unidentified Sporothrix spp., as well as a new species similar to O. adjuncti, O. ips, and O. montium, that we name as O. pulvinisporum sp. nov.
7. Determination of phenolic compounds in Yucca gloriosa bark and root by LC-MS/MS.
Science.gov (United States)
Montoro, Paola; Skhirtladze, Alexandre; Bassarello, Carla; Perrone, Angela; Kemertelidze, Ether; Pizza, Cosimo; Piacente, Sonia
2008-08-05
On the basis of the biological activities shown by yuccaols and gloriosaols from Yucca schidigera and Yucca gloriosa, the content of yuccaols and gloriosaols in two different parts of Y. gloriosa (roots and bark), was determined for each single compound, and compared with phenolic determination in Y. schidigera bark, concluding that Y. gloriosa bark and roots are rich sources of phenolic derivatives structurally related to resveratrol. LC/ESIMS (liquid chromatography coupled to electrospray mass spectrometry) qualitative and an LC/ESIMS/MS (liquid chromatography coupled to tandem electrospray mass spectrometry) quantitative studies of the phenolic fraction of Y. gloriosa were performed. LC/ESIMS/MS multiple reaction monitoring (MRM) method previously described for yuccaols in Y. schidigera was applied and optimised for separation and determination of gloriosaols and yuccaols in Y. gloriosa. Due to the sensitivity and the repeatability of the assay, we suggest this method as suitable for industrial quality control of raw materials and final products.
8. $NDK$, $\\bar{K} DN$ and $ND\\bar{D}$ molecules
CERN Document Server
Xiao, C W; Oset, E
2011-01-01
We investigate theoretically baryon systems made of three hadrons which contain one nucleon and one D meson, and in addition another meson, $\\bar{D}, K$ or $\\bar{K}$. The systems are studied using the Fixed Center Approximation to the Faddeev equations. The study is made assuming scattering of a $K$ or a $\\bar{K}$ on a $DN$ cluster, which is known to generate the $\\Lambda_c(2595)$, or the scattering of a nucleon on the $D\\bar{D}$ cluster, which has been shown to generate a hidden charm resonance named X(3700). We also investigate the configuration of scattering of $N$ on the $KD$ cluster, which is known to generate the $D_{s0}^*(2317)$. In all cases we find bound states, with the $NDK$ system, of exotic nature, more bound than the $\\bar{K} DN$.
9. Integration of the White Sands Complex into a Wide Area Network
Science.gov (United States)
Boucher, Phillip Larry; Horan, Sheila, B.
1996-01-01
10. Optical and radiocarbon ages of stacked paleosols and dune sands in the Nebraska Sand Hills, USA
Science.gov (United States)
Goble, R. J.; Mason, Joseph A.; Loope, David B.; Swinehart, James B.
2004-05-01
Optical ages for eolian sands from the Nebraska Sand Hills indicate periods of extensive eolian activity at ca 115±25, 840±70, 2300±240, and 3560±340 a. Activity was also noted at single sampling locations at ca 6180±370, 8430±510 and 13110±800 a. Many of these ages are similar to those noted by earlier authors. Optical ages from samples collected within paleosols indicate shorter and possibly less extensive periods of eolian activity at approximately 1220±150, 1590±110, and possibly 1950±150 a, during which the paleosol sands accumulated. What was originally interpreted as a single 1.2 m thick paleosol is shown by optical dating to consist of three or more welded soils developed within eolian sands with optical ages of ca 3800±240, 2740±240, 1560±110, and possibly 1930±140 a, each of which match eolian pulses recognized elsewhere. Scatter in some optical ages is attributable to intersection of sand-filled rodent burrows extending in outcrop 1.5 m below the contact between paleosol and overlying topset beds. A 5310±360 a optical age for one probable intersected burrow provides evidence for upward or lateral transport of older sands.
11. Evaluate of head loss, sediment value and copper removal in sand media (rapid sand filter
Directory of Open Access Journals (Sweden)
Daneshi Navab
2014-06-01
Full Text Available Along with the technology development and increasing consumption of water resources, we are experiencing low qualities in the mentioned resources. Copper brings about serious environment al pollution, threatening human health and ecosystem. This metal found variously in water resources and industrial activities. Therefore, it needs to treat the water resources from these excessive amounts. Different methods have used for this reason but the most used method during recent years has been the absorption by economic absorbers such as sand. Rapid sand filters usually used in water and wastewater treatment plants for water clarification. In this research, a single layer gravity rapid sand filter has used to reduce different concentrations of copper. sediment value and head loss arising in filter media is simulated by using combination of Carman-Kozeny, Rose and Gregory models in different discharges of rapid sand filter. Results have shown that with increasing in discharge and decreasing in input copper concentration, arriving time to given head loss, is increasing. In addition, results demonstrated that with increasing in copper concentration in influent, removal efficiency is decreasing somewhat. Results of this research can applied in an appropriate design of rapid sand filter to copper removal, a prediction of rapid sand filter ability to copper removal and an estimation of arising head loss during filter work thus evaluating of time interval backwash. DOI: http://dx.doi.org/10.3126/ije.v3i2.10641 International Journal of the Environment Vol.3(2 2014: 276-286
12. Yield of a Choctawhatchee Sand Pine Plantation at Age 28
Science.gov (United States)
Russell M. Burns; R.H. Brendemuehl
1969-01-01
A little-known tree, Choctawhatchee sand pine (Pinus clausa [Chapm.] Vasey), seems well adapted to the infertile, droughty soils common to the sandhills of Florida which now produce little value. Published yield data based on plantation-grown Choctawhatchee sand pine are not available. One 28-year-old plantation of this race of sand pine, growing...
13. Fresh groundwater resources in a large sand replenishment
NARCIS (Netherlands)
Huizer, Sebastian; Oude Essink, G.H.P.; Bierkens, Marc
2016-01-01
The anticipation of sea-level rise and increases in extreme weather conditions has led to the initiation of an innovative coastal management project called the Sand Engine. In this pilot project a large volume of sand (21.5 million m3) – also called sand replenishment or nourishment – was placed on
14. 77 FR 75007 - Importation of Sand Pears From China
Science.gov (United States)
2012-12-19
... Health Inspection Service 7 CFR Part 319 RIN 0579-AD42 Importation of Sand Pears From China AGENCY... and vegetables regulations to allow the importation of sand pears (Pyrus pyrifolia) from China into the United States. As a condition of entry, sand pears from areas in China in which the Oriental...
15. Design and management of conventional fluidized-sand biofilters
Science.gov (United States)
Fluidized sand biofilters (FSBs) are relatively compact, efficient, and cost-competitive biofilters, especially in recirculating systems that require maintaining consistently low levels of ammonia and nitrite. Filter sand is low cost (often \$70-200/m3 of sand delivered) and has a high specific surf...
16. Mineral processing of heavy mineral sands from Malawi and Malaysia
OpenAIRE
Mitchell, C J
1992-01-01
Processing of heavy mineral sands involves many techniques including gravity, magnetic and electrostatic separation. As part of a laboratory programme to develop effective mineral processing techniques, two mineral sands from Malawi and Malaysia were processed using the standard techniques, with emphasis placed on the Carpco electrostatic separator. These sands were initially characterised mineralogically by scanning electron microscopy (SEM), electron microprobe analysis (EPMA...
17. Alberta's economic development of the Athabasca oil sands
Science.gov (United States)
Steinmann, Michael
This dissertation examines the 61-year evolution of public policies pertaining to development of Alberta's non-conventional source of crude oil. The Athabasca oil sands contain an estimated 1.5 trillion barrels and provide for a safe continental supply. The Provincial Government first sponsored this undertaking in 1943. The period from then to 1971 was one of a transition from a wheat economy to a natural-resource economic base. A stable government emerged and was able to negotiate viable development policies. A second period, 1971 to 1986, was marked by unstable world conditions that afforded the Alberta government the ability to set terms of development with multi-national oil firms. A 50% profit-sharing plan was implemented, and basic 1973 terms lasted until 1996. However, 1986 was a critical year because the Organization of Petroleum Exporting Countries (OPEC) reduced prices, causing the Alberta economy to lapse into recession. During a third period, 1986 to 1996, the Alberta Government was unable to adapt quickly to world conditions. A new leadership structure in 1996 made major changes to create ongoing fiscal and development policies. That history provides answers to two primary research questions: How do public policies affect the behaviors of the modern corporation and visa versa? What are the implications for development theory? Two sources of information were used for this study. First, it was possible to review the Premier's files located in the Provincial Archives. Materials from various government libraries were also examined. Some 7,000 documents were used to show the evolution of government policymaking. Second, interviews with leaders of oil companies and federal research facilities were important. Findings support the thesis that, to facilitate oil sands development, government and the private sector have closely collaborated. In particular, revenue policies have allowed for effective R&D organization. Relying on intensive technological
18. Comparative Antioxidant Activity of Water Extract of ,em>Azadiractha indica Stem Bark and Telfairia occidentalis Leaf
Directory of Open Access Journals (Sweden)
C.P. Anokwuru
2011-07-01
Full Text Available The antioxidant activity of Azadirachta indica stem bark and Telfairia occidentalis leaf aqueous extract was studied. The Total Phenolic Content (TPC was determined using folin Ciocalteu method while the Total Flavonoid Content (TFC was determined using aluminum chloride method. Antioxidant activity was determined using 2, 2-diphenyl-1-picryl hydrazine (DPPH inhibition. Telfairia occidentalis extracted more phenols (11.32g GAE/ 100g than Azadirachta indica stem bark (10.74g GAE/100g but not significantly different (p<0.05. Azadirachta indica stem bark extracted more flavonoid content (5.21g QE/100g than Telfairia occidentalis leaf (0.96g QE/100g. Azadirachta indica stem bark inhibited more free radicals (83% than Telfairia occidentalis leaf (65%. This study showed that Azadirachta indica stem bark had higher antioxidant activity compared to Telfairia occidentalis leaf.
19. Fraxinus paxiana bark mediated photosynthesis of silver nanoparticles and their size modulation using swift heavy ion irradiation
Science.gov (United States)
Sharma, Hemant; Vendamani, V. S.; Pathak, Anand P.; Tiwari, Archana
2015-12-01
Photosynthesis of silver nanoparticles is presented using bark extracts of Fraxinus paxiana var. sikkimensis. The synthesized nanoparticles are characterised by UV-Vis absorption, photoluminescence, powder X-ray diffraction and scanning and transmission electron microscopy. In addition, the bark samples are irradiated with 100 MeV silver ions and the subsequent structural modifications are analyzed. The swift heavy ion irradiated Fraxinus paxiana var. sikkimensis bark is also used for the synthesis of silver nanoparticles. It is illustrated that the irradiated bark assists in synthesizing smaller nanoparticles of homogenous size distribution as compared to when the pristine bark is used. The newly synthesized silver nanoparticles are also used to demonstrate the antimicrobial activities on Escherichia coli bacteria.
20. Allometric Bark Biomass Model for Daphne bholua in the Mid-Hills of Nepal
Directory of Open Access Journals (Sweden)
Ram P. Sharma
2017-05-01
Full Text Available Bark of Daphne bholua is an important non-timber forest product and makes a substantial contribution to the Nepalese economy. A precise estimate of the amount of D. bholua bark in mountain forests is possible using a biomass model. We developed an allometric bark biomass model for naturally grown D. bholua in Baglung District in the mid-hills of Nepal. The model was based on data from 101 destructively sampled D. bholua on 20 sample plots representing different growth stages (regeneration, established, and matured, site qualities, and stand densities, and we used diameter and height–diameter ratio as predictors. Among 9 functions evaluated, a simple power function showed the best fit to the data. This model described most of the variations in bark biomass with no substantial trends in the residuals. Leave-one-out cross-validation also confirmed the high precision of this model, because it described most of the variations in bark biomass with no substantial trends in the prediction errors. The model can be applied for a precise prediction of bark biomass for individuals of D. bholua with diameters and height–diameter ratios similar to those used in this study. It is site-specific, and its application should therefore be limited to sites with growth stage, site quality, stand density, and species distribution similar to those that formed the basis of this study. Further validation and verification of this model, with a larger dataset collected from sites with a wider range of these characteristics, is recommended.
1. Development of a nested PCR detection procedure for Nectria fuckeliana direct from Norway spruce bark extracts.
Science.gov (United States)
Langrell, Stephen R H
2005-01-01
A pair of primers specific for Nectria fuckeliana, a bark infecting pathogen predominantly of Norway spruce (Picea abies), were designed from comparisons of nucleotide sequences of the nuclear ribosomal internal transcribed spacer (ITS) regions of nine isolates from Norway, Lithuania, Switzerland, Austria, Slovakia, Scotland (Larix sp.) and New Zealand (Pinus radiata), and other closely related nectriaceous species, including Neo. Neomacrospora, and 'N'. mammoidea, to which it exhibits taxonomic similarities. Complete ITS sequence homology was observed between each of the nine N. fuckeliana isolates, regardless of geographic provenance, including a previously published Danish strain. Primers Cct1 and Cct2 consistently amplified a single product of 360 bp from DNA prepared from 20 isolates covering the principle range of the disease from Central and Northern Europe, but not from other Neonectria, 'Nectria' or a range of species commonly encountered in forest ecosystems, as well as P. abies or P. radiata DNA. A quick, simple and efficient mechanical lysis procedure for the extraction of high quality total DNA from bark, coupled with post-extraction polyvinylpolypyrrolidone (PVPP) chromatography purification, is described to facilitate successful PCR detection of N. fuckeliana direct from bark extracts. Detection of N. fuckeliana from bark preparations was only possible following nested PCR of PVPP purified extracts using universal primers ITS5 and 4 in first round amplification. The identity of products from bark tissues was confirmed by Southern hybridisation and sequencing. Using the above procedure, positive diagnosis of N. fuckeliana was achievable within 5 h and has the potential for full exploitation as both a forest management and ecological research tool. As the DNA extraction procedure described here has been successful in application against other tree species, it has potential for incorporation into other molecular diagnostic systems for other
2. Variations in Tannin and Oxalic acid Content in Terminalia arjuna (Arjuna Bark
Directory of Open Access Journals (Sweden)
A K Pandey
2009-01-01
Full Text Available Terminalia arjuna (Arjuna, belonging to family combretaceae, grows along the streams or rivers and often in the shallow streambeds and riverbeds in central India. It has been considered by the Ayurvedic physicians as well as by the modern practitioners as a cardiac tonic. Clinical evaluation indicated that it has been found beneficial in the treatment of coronary artery disease, heart failure, and possibly hypercholesterolemia. It has also been found to possess antibacterial, antimutagenic and antioxidant activities. Demand for T. arjuna bark, both in India and abroad has been increasing rapidly for over a decade. About 95 percent of the requirement is met from the wild and collected in a pattern that is not concomitant with sustainable harvesting practices. The quality of the bark is directly dependent on harvesting technique and time. There is also a clear relationship between the part of the plant harvested, harvesting method used, and the impact of these on the plant. Keeping above into consideration it has been planned to carry out systematic study on phytochemical investigation of Arjuna bark collected from various parts of the tree at different harvesting time. The bark samples were analyzed for tannin and oxalic acid. The tannin and oxalic acid content varied from 6.75 to 14.82 % and 7.66 to 20.05 % respectively in various samples of T. arjuna bark collected from various places of Madhya Pradesh. The middle-aged trees having GBH around 130 cm were found to contain more amount of tannin. The study gives important information to obtain better quality of T. arjuna bark on sustainable basis.
3. Occurrence of spruce bark beetles in forest stands at different levels of air pollution stress
Energy Technology Data Exchange (ETDEWEB)
Grodzki, Wojciech; McManus, Michael; Knizek, Milos; Meshkova, Valentina; Mihalciuc, Vasile; Novotny, Julius; Turcani, Marek; Slobodyan, Yaroslav
2004-07-01
The spruce bark beetle, Ips typographus (L.) is the most serious pest of mature spruce stands, mainly Norway spruce, Picea abies (L.) Karst. throughout Eurasia. A complex of weather-related events and other environmental stresses are reported to predispose spruce stands to bark beetle attack and subsequent tree mortality; however the possible role of industrial pollution as a predisposing factor to attack by this species is poorly understood. The abundance and dynamics of I. typographus populations was evaluated in 60-80 year old Norway spruce stands occurring on 10x50 ha sites in five countries within the Carpathian range that were selected in proximity to established ozone measurement sites. Data were recorded on several parameters including the volume of infested trees, captures of adult beetles in pheromone traps, number of attacks, and the presence and relative abundance of associated bark beetle species. In several cases, stands adjacent to sites with higher ozone values were associated with higher bark beetle populations. The volume of sanitary cuttings, a reflection of tree mortality, and the mean daily capture of beetles in pheromone traps were significantly higher at sites where the O{sub 3} level was higher. However, the mean infestation density on trees was higher in plots associated with lower O{sub 3} levels. Captures of beetles in pheromone traps and infestation densities were higher in the zone above 800 m. However, none of the relationships was conclusive, suggesting that spruce bark beetle dynamics are driven by a complex interaction of biotic and abiotic factors and not by a single parameter such as air pollution. - Air pollution (ozone) can be one of predisposing factors that increases the susceptibility of mountain Norway spruce stands to attack by Ips typographus and associated bark beetle species.
4. Bark and Ambrosia Beetles Show Different Invasion Patterns in the USA.
Directory of Open Access Journals (Sweden)
Davide Rassati
Full Text Available Non-native bark and ambrosia beetles represent a threat to forests worldwide. Their invasion patterns are, however, still unclear. Here we investigated first, if the spread of non-native bark and ambrosia beetles is a gradual or a discontinuous process; second, which are the main correlates of their community structure; third, whether those correlates correspond to those of native species. We used data on species distribution of non-native and native scolytines in the continental 48 USA states. These data were analyzed through a beta-diversity index, partitioned into species richness differences and species replacement, using Mantel correlograms and non-metric multidimensional scaling (NMDS ordination for identifying spatial patterns, and regression on distance matrices to test the association of climate (temperature, rainfall, forest (cover area, composition, geographical (distance, and human-related (import variables with β-diversity components. For both non-native bark and ambrosia beetles, β-diversity was mainly composed of species richness difference than species replacement. For non-native bark beetles, a discontinuous invasion process composed of long distance jumps or multiple introduction events was apparent. Species richness differences were primarily correlated with differences in import values while temperature was the main correlate of species replacement. For non-native ambrosia beetles, a more continuous invasion process was apparent, with the pool of non-native species arriving in the coastal areas that tended to be filtered as they spread to interior portions of the continental USA. Species richness differences were mainly correlated with differences in rainfall among states, while rainfall and temperature were the main correlates of species replacement. Our study suggests that the different ecology of bark and ambrosia beetles influences their invasion process in new environments. The lower dependency that bark beetles have
5. Woody Plants Affected by Ungulates in Winter Period, Impacts and Bark Renewal
Directory of Open Access Journals (Sweden)
Nevřelová Marta
2015-09-01
Full Text Available Due to biotope fragmentation and changes in landscape structure, opportunities for forest animals to migrate and obtain food are diminishing, especially during extreme winter conditions. The main objective of this research was an assessment of ungulates, impact on woody species, evaluation of damage forms and bark renewal phases of affected woody plants. The study area is located in western Slovakia in the southeast part of Male Karpaty Mts. After the very cold and long winter of 2012/2013, 34% of woody plants were damaged by bark stripping and biting on the forest locality and 53% of evaluated trees and shrubs were damaged by biting off shoots in the non-forest locality. Together, 262 woody plants belonging to 15 species were evaluated; the girth of tree trunks and stripped bark patches were measured. The most severely affected tree species, suffering from bark stripping and bitten-off sprouts, was Fraxinus excelsior; Acer campestre was also significantly affected. Results showed that woody plants provide a significant part of hoofed mammal nutrition (especially Capreolus capreolus and Cervus elaphus. The stripped bark dendromass per forested area of 625 m2 reached 3 m2. After the mild winter in 2014, the majority (93.7% of previously affected Fraxinus excelsior trees in the forest locality had only old damages with renewed bark in different phases of regeneration. In the non-forest locality, 96% of young Fraxinus excelsior, damaged in the winter of 2013, shot up new sprouts. The mortality of affected trees was minimal (4−5%.
6. Combustion characteristics of eastern white pine bark and Douglas fir planer shavings. Technical Progress Report No. 5, September 16, 1977--September 15, 1978
Energy Technology Data Exchange (ETDEWEB)
Junge, D.C.
1978-12-01
Significant quantities of wood residue fuels are presently being used in industrial steam generating facilities. Recent studies indicate that substantial additional quantities of wood residue fuels are available for energy generation in the form of steam and/or electricity. A limited data base on the combustion characteristics of wood residue fuels has resulted in the installation and operation of inefficient combustion systems for these fuels. This investigation of the combustion characteristics of wood residue fuels was undertaken to provide a data base which could be used to optimize the combustion of such fuels. Optimization of the combustion process in industrial boilers serves to improve combustion efficiency and to reduce air pollutant emissions generated in the combustion process. Data are presented on the combustion characteristics of eastern white pine bark mixed with Douglas fir planer shavings.
7. An Overview of the Summer 2014 Airborne Study of Oil Sands Air Pollutants in Support of the Joint Oil Sands Monitoring Plan
Science.gov (United States)
Li, S. M.; Hayden, K. L.; Cober, S.; Wolde, M.; Liggio, J.; Liu, P.; Leithead, A.; O'brien, J.; Wang, D. K.; Moussa, S. G.; Gordon, M.; Darlington, A. L.; McLaren, R.; Makar, P.; Stroud, C.; Wentzell, J. J. B.; Brook, J.; Narayan, J.; Elford, A.; Sung, K.; Sheppard, A.
2014-12-01
A short term airborne study of oil sands air pollutants was carried out in August and September 2013. The study had three objectives: 1. to validate emissions of criteria air contaminants (CACs) and other air pollutants from surface mining facilities in the Athabasca oil sands region, using airborne ambient air measurements; 2. to understand the transport and transformation of primary pollutants; and 3. to provide data for model and satellite retrieval validation. The data will be used for the evaluation and improvement of high-resolution air quality models for eventual application in determining the fates of these pollutants and their deposition to the downwind ecosystems. Various chemical species were measured from the National Research Council of Canada Convair-580 aircraft at high time resolution of 1-10 seconds. A total of 22 flights were flown, with 14 flights dedicated to emission validation, 5 flights to transport and transformation of oil sands pollutants, and 5 flights to satellite data validation. An algorithm will be shown to demonstrate how the data from the emission flights can be used to derive a top-down estimate of SO2 emission rates.
8. Air Quality Facilities
Data.gov (United States)
Iowa State University GIS Support and Research FacilityFacilities with operating permits for Title V of the Federal Clean Air Act, as well as facilities required to submit an air emissions inventory, and other facilities...
9. Theme: Laboratory Facilities Improvement.
Science.gov (United States)
Miller, Glen M.; And Others
1993-01-01
Includes "Laboratory Facilities Improvement" (Miller); "Remodeling Laboratories for Agriscience Instruction" (Newman, Johnson); "Planning for Change" (Mulcahy); "Laboratory Facilities Improvement for Technology Transfer" (Harper); "Facilities for Agriscience Instruction" (Agnew et al.); "Laboratory Facility Improvement" (Boren, Dwyer); and…
10. Defoliation and bark harvesting affect life-history traits of a tropical tree
DEFF Research Database (Denmark)
Gaoue, Orou; Horvitz, Carol; Ticktin, Tamara
2013-01-01
Selectively harvesting whole individuals in managed populations (e.g. fisheries, hunting) has substantial effects on life expectancy and age at maturity. Although demographic rates of trees are impacted by recurrent harvest of plant organs (e.g. fruit, leaf, bark) known as non-timber forest...... products, the effect of such harvesting on life-history traits is less explored. Here, we investigate how different strategies of foliage and bark harvest by local people affect life expectancy and age at maturity of Khaya senegalensis across two climatic regions in West Africa. We compare elasticities...
11. Determination of anthelmintic activity of the leaf and bark extract of Tamarindus Indica linn
Directory of Open Access Journals (Sweden)
S S Das
2011-01-01
Full Text Available The aim of the present study was to evaluate the anthelmintic activity of ethanolic and aqueous extract of leaves and bark of Tamarindus indica Linn using Pheretima posthuma and Tubifex tubifex as test worms. The time of paralysis and time of death were studied and the activity was compared with piperazine citrate as reference standard. The alcohol and aqueous extract of bark of Tamarindus indica exhibited significant anthelmintic activity as evidenced by decreased paralyzing time and death time. The results thus support the use of Tamarindus indica as an anthelmintic agent.
12. Determination of anthelmintic activity of the leaf and bark extract of tamarindus indica linn.
Science.gov (United States)
Das, S S; Dey, Monalisha; Ghosh, A K
2011-01-01
The aim of the present study was to evaluate the anthelmintic activity of ethanolic and aqueous extract of leaves and bark of Tamarindus indica Linn using Pheretima posthuma and Tubifex tubifex as test worms. The time of paralysis and time of death were studied and the activity was compared with piperazine citrate as reference standard. The alcohol and aqueous extract of bark of Tamarindus indica exhibited significant anthelmintic activity as evidenced by decreased paralyzing time and death time. The results thus support the use of Tamarindus indica as an anthelmintic agent.
13. The Relation between Hepatotoxicity and the Total Coumarin Intake from Traditional Japanese Medicines Containing Cinnamon Bark.
Science.gov (United States)
Iwata, Naohiro; Kainuma, Mosaburo; Kobayashi, Daisuke; Kubota, Toshio; Sugawara, Naoko; Uchida, Aiko; Ozono, Sahoko; Yamamuro, Yuki; Furusyo, Norihiro; Ueda, Koso; Tahara, Eiichi; Shimazoe, Takao
2016-01-01
Cinnamon bark is commonly used in traditional Japanese herbal medicines (Kampo medicines). The coumarin contained in cinnamon is known to be hepatotoxic, and a tolerable daily intake (TDI) of 0.1 mg/kg/day, has been quantified and used in Europe to insure safety. Risk assessments for hepatotoxicity by the cinnamon contained in foods have been reported. However, no such assessment of cinnamon bark has been reported and the coumarin content of Kampo medicines derived from cinnamon bark is not yet known. To assess the risk for hepatotoxicity by Kampo medicines, we evaluated the daily coumarin intake of patients who were prescribed Kampo medicines and investigated the relation between hepatotoxicity and the coumarin intake. The clinical data of 129 outpatients (18 male and 111 female, median age 58 years) who had been prescribed keishibukuryogankayokuinin (TJ-125) between April 2008 and March 2013 was retrospectively investigated. Concurrent Kampo medicines and liver function were also surveyed. In addition to TJ-125, the patients took some of the other 32 Kampo preparations and 22 decoctions that include cinnamon bark. The coumarin content of these Kampo medicines was determined by high performance liquid chromatography (HPLC). TJ-125 had the highest daily content of coumarin (5.63 mg/day), calculated from the daily cinnamon bark dosage reported in the information leaflet inserted in each package of Kampo medicine. The coumarin content in 1g cinnamon bark decoction was 3.0 mg. The daily coumarin intake of the patients was 0.113 (0.049-0.541) mg/kg/day, with 98 patients (76.0%) exceeding the TDI. Twenty-three patients had an abnormal change in liver function test value, but no significant difference was found in the incidence of abnormal change between the group consuming less than the TDI value (6/31, 19.4%) and the group consuming equal to or greater than the TDI value (17/98, 17.3%). In addition, no abnormal change related to cinnamon bark was found for individual
14. Condensed tannins from acacia mangium bark: Characterization by spot tests and FTIR
Science.gov (United States)
Bharudin, Muhammad Azizi; Zakaria, Sarani; Chia, Chin Hua
2013-11-01
This paper describes the adaptation and evaluation of one chemical tests for tannins characterization in acacia mangium bark. Acid butanol test developed to identify respectively condensed tannins is described. The two traditional tests used for tannin characterization namely ferric test and vanillin test were also performed and their functional also discussed. Condensed tannins were extracted from acacia mangium bark using water medium in presence of three different concentration basic reagent of NaOH(5%,10% and 15%) and were characterized by FT-IR spectrometry.
15. The Relation between Hepatotoxicity and the Total Coumarin Intake from Traditional Japanese Medicines Containing Cinnamon Bark
Science.gov (United States)
Iwata, Naohiro; Kainuma, Mosaburo; Kobayashi, Daisuke; Kubota, Toshio; Sugawara, Naoko; Uchida, Aiko; Ozono, Sahoko; Yamamuro, Yuki; Furusyo, Norihiro; Ueda, Koso; Tahara, Eiichi; Shimazoe, Takao
2016-01-01
Cinnamon bark is commonly used in traditional Japanese herbal medicines (Kampo medicines). The coumarin contained in cinnamon is known to be hepatotoxic, and a tolerable daily intake (TDI) of 0.1 mg/kg/day, has been quantified and used in Europe to insure safety. Risk assessments for hepatotoxicity by the cinnamon contained in foods have been reported. However, no such assessment of cinnamon bark has been reported and the coumarin content of Kampo medicines derived from cinnamon bark is not yet known. To assess the risk for hepatotoxicity by Kampo medicines, we evaluated the daily coumarin intake of patients who were prescribed Kampo medicines and investigated the relation between hepatotoxicity and the coumarin intake. The clinical data of 129 outpatients (18 male and 111 female, median age 58 years) who had been prescribed keishibukuryogankayokuinin (TJ-125) between April 2008 and March 2013 was retrospectively investigated. Concurrent Kampo medicines and liver function were also surveyed. In addition to TJ-125, the patients took some of the other 32 Kampo preparations and 22 decoctions that include cinnamon bark. The coumarin content of these Kampo medicines was determined by high performance liquid chromatography (HPLC). TJ-125 had the highest daily content of coumarin (5.63 mg/day), calculated from the daily cinnamon bark dosage reported in the information leaflet inserted in each package of Kampo medicine. The coumarin content in 1g cinnamon bark decoction was 3.0 mg. The daily coumarin intake of the patients was 0.113 (0.049–0.541) mg/kg/day, with 98 patients (76.0%) exceeding the TDI. Twenty-three patients had an abnormal change in liver function test value, but no significant difference was found in the incidence of abnormal change between the group consuming less than the TDI value (6/31, 19.4%) and the group consuming equal to or greater than the TDI value (17/98, 17.3%). In addition, no abnormal change related to cinnamon bark was found for individual
16. Aporphine alkaloids and feruloylamides from the bark of Xylopia benthamii R.E. Fries (Annonaceae).
Science.gov (United States)
Pimenta, L P S; Mendonça, D D
2012-01-01
The bark of Xylopia benthamii R.E. Fries was investigated in a search for new bioactive compounds. The ethanolic extract of the air-dried bark of X. benthamii was obtained and submitted to an acidic extraction procedure to obtain an alkaloid mixture. Chromatographic fractionation led to the isolation of two aporphine alkaloids, nornantenine and laurotetanine, and a mixture of trans- and cis-feruloyltyramine, isolated for the first time in this genus. Structures were established by spectroscopic methods as NMR (1D and 2D) and mass spectrometry (ESI-MS).
17. Development of quality control parameters for the standardization of bark of Ficus benghalensis Linn
Institute of Scientific and Technical Information of China (English)
Alok Semwal; Ratendra Kumar; Udai Vir Singh Teotia; Ramandeep Singh
2013-01-01
Objective:To study with pharmacognostical and preliminary phytochemical studies of the bark ofFicus benghalensis(F. benghalensis)Linn.Methods:Parameters used to fulfill the objective of the study include various methods such as,Phytochemical test,TLC analysis, foreign matter, ash values, swelling index, fluorescence analysis, extractive value, and moisture content etc. Results:The results of foreign matter were recorded inTables.Conclusion:These parameters can be utilized for quick identification of the bark ofF. bengalensisLinn. and will definitely help in the development of pharmaceutically useful formulations.
18. Bronchodilator activity of aqueous extract of stem bark of Ailanthus excelsa Roxb.
Science.gov (United States)
Kumar, Dinesh; Bhujbal, S S; Deoda, R S; Mudgade, S C
2010-03-01
Biologically active compounds from natural sources are of interest as possible new drugs for infectious diseases. Ailanthus excelsa Roxb. has been used in Indian system of medicine in the treatment of asthma, bronchitis, cold, colic pain, etc. Stem bark of A. excelsa Roxb. has been used as a decoction in traditional claims. So, our traditional claims enforced us to evaluate its bronchodilator activity. We have evaluated its bronchodilator activity in milk-induced leukocytosis and eosinophilia, clonidine-induced mast cell degranulation, bronchoalveolar lavage fluid (BALF), and lung histopathology models. The aqueous extract of stem bark in doses of 100, 200, 400 mg/kg showed significant activity.
19. New camptothecin and ellagic acid analogues from the root bark of Camptotheca acuminata.
Science.gov (United States)
Zhang, Zhizhen; Li, Shiyou; Zhang, Shanmin; Liang, Chun; Gorenstein, David; Beasley, R Scott
2004-12-01
As part of a study on chemical constituents of Camptotheca species, one new natural camptothecin analogue (2), two new alkaloids (3, 4), one new ellagic acid analogue (5), and 19 known compounds (1, 6-23) have been isolated from the root bark, stem bark, fruits, and leaves of Camptotheca acuminata Decaisne. The structures of 2-5 were determined from spectral data to be 10-methoxy-20-O-acetylcamptothecin (2), 20-O-beta-glucopyranosyl 18-hydroxycamptothecin (3), 20-formylbenz indolizino [1,2-b]quino-line-11(13H)-one (4), and 3,4-methylenedioxy-3'-O-methyl-5'-hydroxyellagic acid (5).
20. The Rheology of Acoustically Fluidized Sand
Science.gov (United States)
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http://mathoverflow.net/questions/42873/strange-question-about-hechler/42917
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Recently during a lecture, my professor mentioned that forcing over any poset which is countable, separative, and atomless, is essentially the same as forcing over the Cohen poset, that is to say results in adding a Cohen real.
My question is: Are there any other similar characterizations of "commonly used" forcing posets? Specifically, is there one for the Hechler poset?
The Hechler Poset/forcing notion $(H,\le)$ is given by setting $H=\omega^{\lt\omega} \times \omega^{\omega}$, and defining the relation $(t,v) \le (s,u)$ iff $( t \supset s \wedge (\forall n\in\omega) (u(n) \le v(n)) \wedge (\forall m \in dom(t \backslash s))(t(m) \gt u(m))$. When forcing with this poset, you end up adding an unbounded real to the ground model.
I understand that you cannot produce a model in which $\mathfrak{b}=\omega_2$ using product forcing, and that you need iterated forcing to do so. Moreover, the iterated forcing construction I've seen that produces $\mathfrak{b}=\omega_2$ in the forcing extension, used the finite support iteration of $\omega_2$ many copies of the Hechler poset. Is this evidence for the lack of such a characterization?
(I apologize in advance if this is an ill-stated question, I will change it accordingly if it is.)
-
When I first opened this, I thought you were asking about someone who "Heckled" your professor during a lecture. Then I realized I need to get my eyes checked. – Harry Gindi Oct 20 '10 at 5:01
Oh no wait, my eyes are fine. You just changed the title =p. – Harry Gindi Oct 20 '10 at 5:02
• The collapse forcing $\text{Coll}(\omega,\theta)$ is, up to forcing equivalence, the unique forcing notion of size $|\theta|$ necessarily collapsing $\theta$ to $\omega$. (Note, this includes the case of adding a Cohen real, since $\text{Add}(\omega,1)\equiv\text{Coll}(\omega,\omega)$.) To see this, suppose that $\mathbb{Q}$ is a forcing notion of size $|\theta|$ that necessarily collapses $\theta$ to $\omega$. We may assume without loss of generality that $\mathbb{Q}$ is separative, since the separative quotient of $\mathbb{Q}$ is forcing equivalent to it and no larger in size. Observe that below every condition in $\mathbb{Q}$, there is an antichain of size $\theta$. Since forcing with $\mathbb{Q}$ adds a function from $\omega$ onto $\theta$ and $\mathbb{Q}$ has size $\theta$, there is a name $\dot g$ forced to be a function from $\omega$ onto the generic filter $\dot G$. We build a refining sequence of maximal antichains $A_n\subset\mathbb{Q}$ as follows. Begin with $A_0=\{ 1\}$. If $A_n$ is defined, then let $A_{n+1}$ be a maximal antichain of conditions such that every condition in $A_n$ splits into $\theta$ many elements of $A_{n+1}$, and such that every element of $A_{n+1}$ decides the value $\dot g(\check n)$. The union $\mathbb{R}=\bigcup_n A_n$ is clearly isomorphic as a subposet of $\mathbb{Q}$ to the tree $\theta^{\lt\omega}$, and so it is forcing equivalent to $\text{Coll}(\omega,\theta)$. Furthermore, $\mathbb{R}$ is dense in $\mathbb{Q}$. To see this, fix any condition $q\in\mathbb{Q}$. Since $q$ forces that $q$ is in $\dot G$, there is some $p\leq q$ and natural number $n$ such that $p$ forces via $\mathbb{Q}$ that $\dot g(\check n)=\check q$. Since $A_{n+1}$ is a maximal antichain, there is some condition $r\in A_{n+1}$ that is compatible with $p$. Since $r$ also decides the value of $\dot g(\check n)$ and is compatible with $p$, it must be that $r$ forces $\dot g(\check n)=\check q$ also. In particular, $r$ forces $\check q\in\dot G$, and so by separativity it must be that $r\leq q$. So $\mathbb{R}$ is dense in $\mathbb{Q}$, as desired. Thus, $\mathbb{Q}$ is forcing equivalent to $\mathbb{R}$, which is forcing equivalent to $\text{Coll}(\omega,\theta)$, as desired.
• If $\kappa^{\lt\kappa}=\kappa$, then the forcing $\text{Add}(\kappa,1)$ to add a Cohen subset to $\kappa$ with conditions of size less than $\kappa$ is, up to forcing equivalence, the unique ${\lt}\kappa$-closed necessarily nontrivial forcing notion of size $\kappa$. For this, one similarly builds up a dense tree of conditions inside the poset that is isomorphic to $\kappa^{\lt\kappa}$, which is forcing equivalent to $\text{Add}(\kappa,1)$.
• More generally, if $\theta^{\lt\kappa}=\theta$, then the forcing $\text{Coll}(\kappa,\theta)$ is the unique ${\lt}\kappa$-closed forcing notion necessarily collapsing $\theta$ to $\kappa$ and having size $\theta$. (The straightforward generalization uses separativity, but the separative quotient of a partial order may no longer be $\lt\kappa$-closed, so there is an issue about it; but my student Norman Perlmutter found a solution avoiding the issue.)
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https://arxiv.org/abs/gr-qc/0309038
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gr-qc
# Title:Solutions of all one-dimensional wave equations with time independent potential and separable variables
Authors:Marco Ferraris (1), Alessandro D.A.M. Spallicci (2) ((1) Dip. Matematica, Univ. di Torino, (2) Observatoire de la Cote d'Azur, Nice)
Abstract: Exact solutions, in terms of special functions, of all wave equations $% u_{xx} - u_{tt} = V(x) u(t,x)$, characterised by eight inequivalent time independent potentials and by variable separation, have been found. The real valueness of the solutions from computer algebra programs is not always manifest and in this work we provide ready to use solutions. We discussed especially the potential $\cosh^{-2}x (m_1 + m_2 \sinh x)$. Such potential approximates the Schwarzschild black hole potential for even parity.
Comments: 10 pages, 1 figure. Accepted by Gen. Rel. Grav. J. Subjects: General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph); Analysis of PDEs (math.AP) Journal reference: Gen.Rel.Grav. 36 (2004) 1955-1963 DOI: 10.1023/B:GERG.0000036053.75204.a2 Cite as: arXiv:gr-qc/0309038 (or for this version)
## Submission history
From: Alessandro D. A. M. Spallicci [view email]
[v1] Sun, 7 Sep 2003 08:37:53 UTC (5 KB)
[v2] Wed, 21 Jan 2004 13:55:15 UTC (14 KB)
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https://www.hackmath.net/en/math-problem/48233
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# The rectangular
The rectangular trapezoid has bases 15 dm and 8 dm long and the length of the inclined arm is 12 dm. How long is the other arm of the trapezoid?
d = 9.7468 dm
### Step-by-step explanation:
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https://scipost.org/submissions/scipost_202110_00004v2/
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# A novel formulation of the unintegrated gluon distribution for DIS
### Submission summary
As Contributors: Yacine Mehtar-Tani Preprint link: scipost_202110_00004v2 Date accepted: 2022-05-24 Date submitted: 2022-05-17 17:37 Submitted by: Mehtar-Tani, Yacine Submitted to: SciPost Physics Proceedings Proceedings issue: DIS2021 Academic field: Physics Specialties: High-Energy Physics - Theory Nuclear Physics - Theory Approach: Theoretical
### Abstract
In this talk, we revisit inclusive DIS in the small $x$ limit and derive a new factorization formula that accounts for leading powers in both Bjorken and Regge limits. In this semi-classical description, we obtain a new unintegrated gluon distribution which encompasses both the dipole operator and the gluon Parton Distribution Function with an explicit dependence on the longitudinal momentum fraction $x$.
###### Current status:
Publication decision taken: accept
Editorial decision: For Journal SciPost Physics Proceedings: Publish
(status: Editorial decision fixed and (if required) accepted by authors)
1. In the first sentence of section 2, "introduction" replaced by "introduce".
2. Latex reference error on page 3, sentence 5 (corrected)
3. Latex reference error on page 4, sentence 5 (corrected)
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https://mran.microsoft.com/snapshot/2020-12-04/web/packages/Ravages/vignettes/Ravages_Simulations_vignette.html
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## Introduction
Ravages was developped to simulate genetic data and to perform rare variant association tests (burden tests and the variance-component test SKAT) on more than two groups of individuals (Bocher et al., 2019, doi:10.1002/gepi.22210). Ravages relies on the package Gaston. Most functions are written in C++ thanks to the packages Rcpp, RcppParallel and RcppEigen.
Functions of Ravages use bed.matrix to manipulate genetic data as in the package Gaston (see documentation of this package for more details).
In this vignette, we illustrate how to perform genetic simulations and how to use it to compute power of rare variant association tests. See the main vignette for more details about rare variant association tests.
We develpped two main simulations procedures, one based on allelic frequencies and genetic relative risks (GRR), and the other one based on haplotypes. All the functions can be used to simulate more than two groups of individuals.
## Simulations based on allelic frequencies and GRR
### Calculation of frequencies in each group of individuals
The first step to simulate genetic data is to compute genotypic frequencies in each group of individuals based on frequencies in the general population and on genetic relative risk (GRR) values. GRR correspond to the increased risk of a disease for a given genotype compared to a reference genotype, here the homozygous genotype for the reference allele. More precisely, the GRR associated to the heterozygous genotype in the group $$c$$ can be calculated as follow: $GRR_{Aa} = \frac{P(Y=c | Aa)}{P(Y=c | AA)}$ With Y the phenotype (1 for the controls, and c going from 2 to C in the cases), $$A$$ the reference allele, and $$a$$ the alternate allele. The frequency of each genotype in each group of cases $$c$$ can be calculated using Bayes theorem: $P(Aa | Y=c) = \frac{P(Y=c | Aa) P(Aa)}{\sum_{Geno=AA, Aa, aa} P(Y=c | Geno) P(Geno)} = \frac{GRR_{Aa} \times P(Aa)}{P(AA)+GRR_{Aa} \times P(Aa)+GRR_{aa} \times P(aa)}$ P(AA), P(Aa) and P(aa) corresponding to the genotypic probabilities in the general population. The three genotypic frequencies can then be calculated in the controls group using the rule of total probability: $P(Geno | Y=1)=P(Geno) - \sum{_{c=2}^{c=C} P(Geno | Y=c) P(Y=c)}$ The function genotypic.freq() performs these calculations to obtain the three genotypic frequencies in the different groups of individuals. To do so, the user needs to give P(Y=c), the prevalence of each group of cases (argument prev), and the GRR values. GRR values need to be in a matrix form with one row per cases group and one column per variant. If there is no supposed link between the GRR associated to the heterozygous genotype and the GRR associated to the homozygous alternative genotype (general model of the disease, $$genetic.model=“general”$$), the user needs to specify two GRR matrices: one for $$GRR_{Aa}$$ (argument GRR.het) and one for $$GRR_{aa}$$ (argument GRR.homo.alt). If genetic.model=“recessive”, “multiplicative” or “dominant”, only one GRR matrix is needed. genotypic.freq() will return a list with three matrices, one for each genotype containing the genotypic frequencies, with one row per group of individuals and one column per variant.
To help the user with the construction of the GRR matrix for genotypic.freq(), we implemented the function GRR.matrix().
To use this function, the user needs to specify how the GRR should be calculated (argument GRR):
• the same GRR is given to all the variants (GRR=“constant”), its value being specified to GRR.value;
• the GRR is computed using the same formula as in SKAT: $$w=-0.4*|log_{10}(MAF)|$$ (GRR=“SKAT”);
• the GRR is computed using another function depending on MAF in the general population (GRR=“variable”), this function being specified to GRR.function.
In the two last situations, a file containing the MAF in the general population with at least a column “maf” and a column “gene” should be given to the argument genes.maf. Two such files are available in Ravages: the file Kryukov containing MAF simulated under the demographic model of Kryukov and the file GnomADgenes containing MAF from the NFE population in GnomAD. As these files contain MAF for multiple genes, the user needs to specify which gene to choose to simulate the data with the argument select.gene. If this argument is empty, only the first gene will be kept in the simulation procedure.
Finally, the multiplicative factor of the GRR between each group of cases compared to the first group of cases needs to be specified to the argument GRR.multiplicative.factor (number of values: number of cases groups - 1).
GRR.matrix() will return a GRR matrix in the appropriate format for the function genotypic.freq().
Examples of these two functions are shown below:
#GRR calculated using the same formula as in SKAT,
#with values in the second group of cases being twice the values from the first one
GRR.del <- GRR.matrix(GRR = "SKAT", genes.maf = Kryukov, n.case.groups = 2,
GRR.multiplicative.factor=2, select.gene = "R1")
GRR.del[,1:5]
## [,1] [,2] [,3] [,4] [,5]
## [1,] 5.037728 6.222656 12.34472 9.042877 8.133663
## [2,] 10.075455 12.445313 24.68944 18.085755 16.267327
#Calculation of genotype frequencies in the two groups of cases and the controls group
#The previous GRR matrix is used with a multiplicative model of the disease
#The prevalence in each group of cases is 0.001
geno.freq.groups <- genotypic.freq(genes.maf = Kryukov, select.gene="R1",
GRR.het = GRR.del, prev = c(0.001, 0.001),
genetic.model = "multiplicative")
str(geno.freq.groups)
## List of 3
## $freq.homo.ref: num [1:3, 1:383] 1 0.999 0.998 1 1 ... ## ..- attr(*, "dimnames")=List of 2 ## .. ..$ : chr [1:3] "controls" "cases_1" "cases_2"
## .. ..$: NULL ##$ freq.het : num [1:3, 1:383] 1.87e-04 9.56e-04 1.91e-03 5.57e-05 3.52e-04 ...
## ..- attr(*, "dimnames")=List of 2
## .. ..$: chr [1:3] "controls" "cases_1" "cases_2" ## .. ..$ : NULL
## $freq.homo.alt: num [1:3, 1:383] 7.90e-09 2.29e-07 9.15e-07 6.49e-10 3.11e-08 ... ## ..- attr(*, "dimnames")=List of 2 ## .. ..$ : chr [1:3] "controls" "cases_1" "cases_2"
## .. ..$: NULL #frequencies of the homozygous alternative genotype in the different groups geno.freq.groups$freq.homo.alt[,1:5]
## [,1] [,2] [,3] [,4] [,5]
## controls 7.897334e-09 6.485888e-10 7.480447e-14 6.568600e-12 2.503543e-11
## cases_1 2.288672e-07 3.106821e-08 4.778956e-11 9.067311e-10 2.469545e-09
## cases_2 9.145933e-07 1.242291e-07 1.911556e-10 3.626706e-09 9.877199e-09
It is also possible to calculate the MAF in each group of individuals as follow:
#MAF calculation for the first five variants
geno.freq.groups$freq.homo.alt[,1:5] + 0.5*geno.freq.groups$freq.het[,1:5]
## [,1] [,2] [,3] [,4] [,5]
## controls 9.375276e-05 2.785699e-05 5.403418e-07 3.246158e-06 5.972867e-06
## cases_1 4.784006e-04 1.762618e-04 6.912999e-06 3.011198e-05 4.969452e-05
## cases_2 9.563437e-04 3.524614e-04 1.382590e-05 6.022214e-05 9.938410e-05
### Simulation of genotypes
In addition to compute the genotypic frequencies in each group of individuals, it is possible to directly simulate genotypes for a group of controls and more than two groups of cases. This can be done using the function random.bed.matrix() which relies on the function genotypic.freq() explained previously. The arguments genes.maf, select.gene, prev and genetic.model are the same as in genotypic.freq().
In random.bed.matrix(), the proportion of causal variants and protective variants (among causal variants) simulated in the genomic region should be specified to p.causal and p.protect respectively. The argument GRR.matrix.del should contain a matrix with GRR values as if all the variants were deleterious. If genetic.model=“general”, two GRR matrices need to be given as a list to the argument GRR.matrix.del (one for the heterozygous genotype and the other for the homozygous alternative genotype).
If the user wants to simulate protective variants in addition to deleterious variants, a similar argument to GRR.matrix should be given to GRR.matrix.pro with GRR values as if all variants were protective. If the argument GRR.matrix.pro is empty and p.protect>0, GRR.matrix.pro will correspond to 1/GRR.matrix. These deleterious and protective GRR values will then be assigned to the sampled deleterious and protective variants in the simulations, the non-causal variants having GRR values of 1.
The size of the different groups of individuals should be a vector specified to size, and the user has to choose whether the causal variants will be the same between the different groups of cases with the argument same.variant.
Finally, the number of simulations need to be specified to replicates.
random.bed.matrix() will return a bed matrix with the group of each individual in the field @ped$pheno, the first one being considered by default as the controls group, and the replicate number corresponding to the genomic region in the field @snps$genomic.region.
The example below shows how to simulate a group of 1 000 controls and two groups of 500 cases with 50% of deleterious variants having GRR values from the previous example. The deleterious variants are different between the two groups of cases and 5 genomic regions are simulated.
x <- random.bed.matrix(genes.maf = Kryukov, size = c(1000, 500, 500), replicates = 5,
prev = c(0.001, 0.001), GRR.matrix.del = GRR.del,
p.causal = 0.5, p.protect = 0, same.variant = FALSE,
genetic.model = "multiplicative", select.gene = "R1")
x
## A bed.matrix with 2000 individuals and 1915 markers.
## snps stats are set
## There are 1634 monomorphic SNPs
## ped stats are set
table(x@ped$pheno) ## ## 0 1 2 ## 1000 500 500 table(x@snps$genomic.region)
##
## R1 R2 R3 R4 R5
## 383 383 383 383 383
## Simulations based on haplotypes
Ravages also offers the possibility to perform genetic simulations based on real haplotypes data to mimic linkage desequlibrium pattern observed in these data.
Two options are available to do so: genetic data are simulated using either haplotypes and their frequencies in different groups of individuals (function rbm.haplos.freqs()), or using haplotypes and a liability model on their burdens (function rbm.haplos.thresholds()).
For the first situation, rbm.haplos.freqs() requires a matrix of haplotypes (argument haplos with one row per haplotype and one column per variant), and a matrix with each haplotype frequency in each simulated group of individuals (argument freqs with one row per haplotype and one column per group of individuals). Observed haplotypes are then sampled in each group of individuals in respect to their frequencies in each one of them.
For the second situation, rbm.haplos.thresholds() requires a matrix of haplotypes (argument haplos as well), and a number of other arguments to draw the liability model. The idea of these simulations is to draw a liability distribution of the burden of causal variants for each haplotype, to compute the probability of each haplotype in each group of individuals based on this distribution, and finally to sample haplotypes in each group based on those probabilities. weights is a vector whose length corresponds to the number of variants and is used to weight variant into burdens computation (by default, the same formula as in SKAT is used, which gives the higher weights to the rarest variants : $$w=-0.4*|log_{10}(MAF)|$$). maf.threshold corresponds to the maf threshold used to define a rare variants, i.e. all monomorphic variants and variants with a MAF upper this threshold will have a weight of 0. In addition, the number of causal variants needs to be given to nb.causal, and the proportion of protective variants among causal variants needs to be given to p.protect. Causal variants will be sampled among variants with a positive weight, and haplotypes' burden will be computed on these variants.
h2 corresponds to the phenotypic variance explained by the gene: haplotypes burdens will be adjusted on this value; and prev corresponds to the prevalence of each group of individuals and will be used to compute the liability threshold for each group of individuals (individuals in group $$i$$ will fall between 1-$$prev_{i}$$ and +Inf). This quantile is drawn from a standard normal distribution if normal.approx=TRUE (applicable for low h2 value and pretty large prev values), otherwise, quantiles will be drawn from a distribution based on 1e6 observed sampled burdens. If one wants to simulate a group of unselected controls, prev needs to be set at 1, regardless of the other arguments: haplotypes are sampled uniformly in the whole liability distribution. nb.causal, p.protect, h2 and prev should be vector of equal size as the number of groups. If they are of size 1, their value will be repeated.
As for the previous functions, the number of simulations to preform should be given to replicates. As haplotypes' probabilies can take some time to run for a set of causal variants, it is possible to run several multiple replicates on this same set. Indeed, even if the same causal variants are taken, different haplotypes (with same probabilities) will be sampled in each individual for each replicate. To ensure a minimal variability, we yet recommend to resample the set of causal variants several times. For example, for 1000 replicates, we recommend to resample causal variants 20 times, and therefore to perform 50 replicates by set of causal variants. The number of replicates to perform by set of causal variants should be given to rep.by.causal.
As for the genetic simulations based on GRR with rbm.haplos.freqs() or rbm.haplos.thresholds(), the sizes of each group should be given to size, and the number of simulations to replicates. As before, the replicate number will be in the slot @snps$genomic.region and the group of individuals in @ped$pheno, both being factors. If rbm.haplos.freqs() is used, phenotype values will correspond to the colnames of freqs.
Two examples to illustrate these functions are presented below. The first one enables the simulation of 5 groups of individuals, with haplotype frequencies from the five european populations for the LCT gene. The second one enables the simulation of one group of 100 controls and two groups of 50 cases based on the liability model with different genetic effects. Parameters for these simulations are obtained using get.rbm.thresholds()
#Load LCT dataset for haplotype matrix
data(LCT.haplotypes)
#Simulation based on haplotypes frequencies
#for the variants in the LCT gene in the EUR population
LCT.gene.hap <- LCT.hap[which(LCT.sample$super.population=="EUR"), which(LCT.snps$pos>=136545410 & LCT.snps$pos<=136594750)] #Individuals from EUR LCT.sample.EUR <- subset(LCT.sample, super.population=="EUR") #Matrix of haplotype frequencies LCT.freqs <- sapply(unique(LCT.sample.EUR$population), function(z)
ifelse(LCT.sample.EUR$population==z, 1/table(LCT.sample.EUR$population)[z], 0))
#Simulation of genetic data for five groups of 50 individuals
x <- rbm.haplos.freqs(haplos=LCT.gene.hap, freqs=LCT.freqs, size=rep(50,5), replicates=5)
#Simulation of 100 controls, and two groups of 50 cases with 30 causal variants
#and with the second group having half h2 and twice the prevalence
#compared to the first one
#5 replicates are performed and causal variants are sampled once
x <- rbm.haplos.thresholds(haplos=LCT.gene.hap, nb.causal = 30, h2=c(0.01,0.01,0.02),
prev=c(1,0.01,0.005), size=c(100, 50, 50), replicates=5,
rep.by.causal = 5)
## 3 groups of individuals will be simulated
## Power calculation
Power calculations are not directly implemented into Ravages, but the functions burden() and SKAT() can be used to perform burden tests and SKAT. To have more informations about these two functions, please refer to the main vignette of the package. After the simulation of a bedmatrix using one of the two previously explained methods, statistical power can be computed as follows:
#Simulations using GRR values
#The two groups of cases are genetically heterogeneous
GRR.del <- GRR.matrix(GRR = "SKAT", genes.maf = Kryukov, n.case.groups = 2,
GRR.multiplicative.factor=2, select.gene = "R1")
x.GRR <- random.bed.matrix(genes.maf = Kryukov, size = c(200, 100, 100),
prev = c(0.001, 0.001), GRR.matrix.del = GRR.del,
p.causal = 0.3, p.protect = 0, same.variant = TRUE,
replicates = 100, genetic.model = "multiplicative",
select.gene = "R1")
table(x.GRR@ped$pheno) #Selection of rare variants: MAF<1% in the entire sample x.GRR.filter <- filter.rare.variants(x.GRR, maf.threshold=0.01, filter="whole") #Comparing each group of cases to the controls with WSS x.GRR.1 <- select.inds(x.GRR.filter, x.GRR.filter@ped$pheno %in% c(0,1))
x.GRR.2 <- select.inds(x.GRR.filter, x.GRR.filter@ped$pheno %in% c(0,2)) #Construction of null models H0.cas1 <- NullObject.parameters(x.GRR.1@ped$pheno, ref.level = 0,
RVAT = "burden", pheno.type = "categorial")
H0.cas2 <- NullObject.parameters(x.GRR.2@ped$pheno, ref.level = 0, RVAT = "burden", pheno.type = "categorial") #Run WSS wss.cas1 <- burden(x.GRR.1, H0.cas1, burden="WSS", cores = 1) mean(wss.cas1$p.value<0.05)
wss.cas2 <- burden(x.GRR.2, H0.cas2, burden="WSS", cores = 1)
mean(wss.cas2$p.value<0.05) #Power of SKAT with each group considered separately #Null model skat.null.3gps <- NullObject.parameters(x.GRR.filter@ped$pheno,
RVAT = "SKAT", pheno.type = "categorial")
skat.3gps <- SKAT(x.GRR.filter, skat.null.3gps,
params.sampling = list(perm.target = 100, perm.max = 5e4))
mean(skat.3gps\$p.value<0.05)
|
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|
https://scholarcommons.usf.edu/etd/7008/
|
#### Title
On Extending Hansel's Theorem to Hypergraphs
2018
Dissertation
Ph.D.
#### Degree Name
Doctor of Philosophy (Ph.D.)
#### Degree Granting Department
Mathematics and Statistics
#### Major Professor
Brendan Nagle, Ph.D.
#### Committee Member
Brian Curtin, Ph.D.
#### Committee Member
Theo Molla, Ph.D.
#### Committee Member
Dmytro Savchuk, Ph.D.
#### Committee Member
Jay Ligatti, Ph.D.
#### Keywords
Extremal Combinatorics, Covers, Weight, Hansel
#### Abstract
For integers $n \geq k \geq 2$, let $V$ be an $n$-element set, and let $\binom{V}{k}$ denote the family of all $k$-element subsets of $V$. For disjoint subsets $A, B \subseteq V$, we say that $\{A, B\}$ {\it covers} an element $K \in \binom{V}{k}$ if $K \subseteq A \dot\cup B$ and $K \cap A \neq \emptyset \neq K \cap B$. We say that a collection $\cC$ of such pairs {\it covers} $\binom{V}{k}$ if every $K \in \binom{V}{k}$ is covered by at least one $\{A, B\} \in \cC$. When $k=2$, covers $\cC$ of $\binom{V}{2}$ were introduced in~1961 by R\'enyi~\cite{Renyi}, where they were called {\it separating systems} of $V$ (since every pair $u \neq v \in V$ is separated by some $\{A, B\} \in \cC$, in the sense that $u \in A$ and $v \in B$, or vice-versa). Separating systems have since been studied by many authors.
For a cover $\cC$ of $\binom{V}{k}$, define the {\it weight} $\omega(\cC)$ of $\cC$ by $\omega(\cC) = \sum_{\{A, B\} \in \cC} (|A|+|B|)$. We define $h(n, k)$ to denote the minimum weight $\omega(\cC)$ among all covers $\cC$ of $\binom{V}{k}$. In~1964, Hansel~\cite{H} determined the bounds $\lceil n \log_2 n \rceil \leq h(n, 2) \leq n\lceil \log_2 n\rceil$, which are sharp precisely when $n = 2^p$ is an integer power of two. In~2007, Bollob\'as and Scott~\cite{BS} extended Hansel's bound to the exact formula $h(n, 2) = np + 2R$, where $n = 2^p + R$ for $p = \lfloor \log_2 n\rfloor$.
The primary result of this dissertation extends the results of Hansel and of Bollob\'as and Scott to the following exact formula for $h(n, k)$, for all integers $n \geq k \geq 2$. Let $n = (k-1)q + r$ be given by division with remainder, and let $q = 2^p + R$ satisfy $p = \lfloor \log_2 q \rfloor$. Then
h(n, k) = np + 2R(k-1) + \left\lceil\frac{r}{k-1}\right\rceil (r + k - 1).
A corresponding result of this dissertation proves that all optimal covers $\cC$ of $\binom{V}{k}$, i.e., those for which $\omega(\cC) = h(n, k)$, share a unique {\it degree-sequence}, as follows. For a vertex $v \in V$, define the {\it $\cC$-degree} $\deg_{\cC}(v)$ of $v$ to be the number of elements $\{A, B\} \in \cC$ for which $v \in A \dot\cup B$. We order these degrees in non-increasing order to form $\bd(\cC)$, and prove that when $\cC$ is optimal, $\bd(\cC)$ is necessarily binary with digits $p$ and $p+1$, where uniquely the larger digits occur precisely on the first $2R(k-1) + \lceil r/(k-1) \rceil (r + k - 1)$ many coordinates. That $\bd(\cC)$ satisfies the above for optimal $\cC$ clearly implies the claimed formula for $h(n,k)$, but in the course of this dissertation, we show these two results are, in fact, equivalent.
In this dissertation, we also consider a $d$-partite version of covers $\cC$, written here as {\it $d$-covers} $\cD$. Here, the elements $\{A,B\} \in \cC$ are replaced by $d$-element families $\{A_1, \dots, A_d\} \in \cD$ of pairwise disjoint sets $A_i \subset V$, $1 \leq i \leq d$. We require that every element $K \in \binom{V}{k}$ is covered by some $\{A_1, \dots, A_d\} \in \cD$, in the sense that $K \subseteq A_1 \dot\cup \cdots \dot\cup A_d$ where $K \cap A_i \neq \emptyset$ holds for each $1 \leq i \leq d$. We analogously define $h_d(n,k)$ as the minimum weight $\omega(\cD) = \sum_{D \in \cD} \sum_{A \in D} |A|$ among all $d$-covers $\cD$ of $\binom{V}{k}$. In this dissertation, we prove that for all $2 \leq d \leq k \leq n$, the bound $h_d(n,k) \geq n \log_{d/(d-1)} (n/(k-1))$ always holds, and that this bound is asymptotically sharp whenever $d = d(k) = O (k/\log^2 k)$ and $k = k(n) = O(\sqrt{\log \log n})$.
COinS
|
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|
https://brilliant.org/problems/find-those-triplets/
|
# Find those Triplets!
Algebra Level 5
Find the number of triples of integers $$a<b<c$$ with $$a\geq -10$$, such that $$a(b-c)^3+b(c-a)^3+c(a-b)^3=0.$$
×
|
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|
https://bigideasmathanswers.com/eureka-math-grade-7-module-3-lesson-9/
|
## Engage NY Eureka Math 7th Grade Module 3 Lesson 9 Answer Key
### Eureka Math Grade 7 Module 3 Lesson 9 Example Answer Key
Example 1.
Fred and Sam are a team in the local 138.2 mile bike-run-athon. Fred will compete in the bike race, and Sam will compete in the run. Fred bikes at an average speed of 8 miles per hour and Sam runs at an average speed of 4 miles per hour. The bike race begins at 6:00 a.m., followed by the run. Sam predicts he will finish the run at 2:33 a.m. the next morning.
a. How many hours will it take them to complete the entire bike-run-athon?
From 6:00 a.m. to 2:00 a.m. the following day is 20 hours.
33 minutes in hours is $$\frac{33}{60}$$=$$\frac{11}{20}$$=0.55, or 0.55 hours.
Therefore, the total time it will take to complete the entire bike-run-athon is 20.55 hours.
b. If t is how long it takes Fred to complete the bike race, in hours, write an expression to find Fred’s total distance.
d=rt
d=8t
The expression of Fred’s total distance is 8t.
c. Write an expression, in terms of t to express Sam’s time.
Since t is Fred’s time and 20.55 is the total time, then Sam’s time would be the difference between the total time and Fred’s time. The expression would be 20.55-t.
d. Write an expression, in terms of t, that represents Sam’s total distance.
d=rt
d=4(20.55-t)
The expressions 4(20.55-t) or 82.2-4t is Sam’s total distance.
e. Write and solve an equation using the total distance both Fred and Sam will travel.
8t+4(20.55-t)=138.2
8t+82.2-4t=138.2
8t-4t+82.2=138.2
4t+82.2=138.2
4t+82.2-82.2=138.2-82.2
4t+0=56
($$\frac{1}{4}$$)(4t)=($$\frac{1}{4}$$)(56)
t=14
Fred’s time: 14 hours
Sam’s time: 20.55-t=20.55-14=6.55
6.55 hours
f. How far will Fred bike, and how much time will it take him to complete his leg of the race?
8(14)=112
Fred will bike 112 miles and will complete the bike race in 14 hours.
g. How far will Sam run, and how much time will it take him to complete his leg of the race?
4(20.55-t)
4(20.55-14)
4(6.55)
26.2
Sam will run 26.2 miles, and it will take him 6.55 hours.
→ How do you find the distance traveled?
→ Multiply the rate of speed by the amount of time.
→ Model how to organize the problem in a distance, rate, and time chart.
→ Explain how to write the equation to have only integers and no decimals. Write the equation.
→ Since the decimal terminates in the tenths place, if we multiply every term by 10, the equation would result with only integer coefficients. The equation would be 40t+822=1382.
Example 2.
Shelby is seven times as old as Bonnie. If in 5 years, the sum of Bonnie’s and Shelby’s ages is 98, find Bonnie’s present age. Use an algebraic approach.
x+5+7x+5=98
8x+10=98
8x+10-10=98-10
8x=88
($$\frac{1}{8}$$)(8x)=($$\frac{1}{8}$$)(88)
x=11
Bonnie’s present age is 11 years old.
→ The first step we must take is to write expressions that represent the present ages of both Bonnie and Shelby. The second step is to write expressions for future time or past time, using the present age expressions. How would the expression change if the time were in the past and not in the future?
→ If the time were in the past, then the expression would be the difference between the present age and the amount of time in the past.
### Eureka Math Grade 7 Module 3 Lesson 9 Opening Exercise Answer Key
Heather practices soccer and piano. Each day she practices piano for 2 hours. After 5 days, she practiced both piano and soccer for a total of 20 hours. Assuming that she practiced soccer the same amount of time each day, how many hours per day, h, did Heather practice soccer?
h: hours per day that soccer was practiced
5(h+2)=20
5h+10=20
5h+10-10=20-10
5h=10
($$\frac{1}{5}$$)(5h)=($$\frac{1}{5}$$)(10)
h=2
Heather practiced soccer for 2 hours each day.
Over 5 days, Jake practices piano for a total of 2 hours. Jake practices soccer for the same amount of time each day. If he practiced piano and soccer for a total of 20 hours, how many hours, h, per day did Jake practice soccer?
h: hours per day that soccer was practiced
5h+2=20
5h+2-2=20-2
5h=18
($$\frac{1}{5}$$)(5h)=(18)($$\frac{1}{5}$$)
h=3.6
Jake practiced soccer 3.6 hours each day.
### Eureka Math Grade 7 Module 3 Lesson 9 Problem Set Answer Key
Question 1.
A company buys a digital scanner for $12,000. The value of the scanner is 12,000(1-$$\frac{n}{5}$$) after n years. The company has budgeted to replace the scanner when the trade-in value is$2,400. After how many years should the company plan to replace the machine in order to receive this trade-in value?
12,000(1-$$\frac{n}{5}$$)=2,400
12,000-2,400n=2,400
-2,400n+12,000-12,000=2,400-12,000
-2,400n=-9,600
n=4
They will replace the scanner after 4 years.
Question 2.
Michael is 17 years older than John. In 4 years, the sum of their ages will be 49. Find Michael’s present age.
x represents Michael’s age now in years.
x+4+x-17+4=49
x+4+x-13=49
2x-9=49
2x-9+9=49+9
2x=58
($$\frac{1}{2}$$)(2x)=($$\frac{1}{2}$$)(58)
x=29
Michael’s present age is 29 years old.
Question 3.
Brady rode his bike 70 miles in 4 hours. He rode at an average speed of 17 mph for t hours and at an average rate of speed of 22 mph for the rest of the time. How long did Brady ride at the slower speed? Use the variable t to represent the time, in hours, Brady rode at 17 mph.
The total distance he rode: 17t+22(4-t)
The total distance equals 70 miles:
17t+22(4-t)=70
17t+88-22t=70
-5t+88=70
-5t+88-88=70-88
-5t=-18
t=3.6
Brady rode at 17 mph for 3.6 hours.
Question 4.
Caitlan went to the store to buy school clothes. She had a store credit from a previous return in the amount of $39.58. If she bought 4 of the same style shirt in different colors and spent a total of$52.22 after the store credit was taken off her total, what was the price of each shirt she bought? Write and solve an equation with integer coefficients.
t: the price of one shirt
4t-39.58=52.22
4t-39.58+39.58=52.22+39.58
4t+0=91.80
($$\frac{1}{4}$$)(4t)=($$\frac{1}{4}$$)(91.80)
t=22.95
The price of one shirt was $22.95. Question 5. A young boy is growing at a rate of 3.5 cm per month. He is currently 90 cm tall. At that rate, in how many months will the boy grow to a height of 132 cm? Answer: Let m represent the number of months. 3.5m+90=132 3.5m+90-90=132-90 3.5m=42 ($$\frac{1}{3.5}$$)(3.5m)=($$\frac{1}{3.5}$$)(42) m=12 The boy will grow to be 132 cm tall 12 months from now. Question 6. The sum of a number, $$\frac{1}{6}$$ of that number, 2 $$\frac{1}{2}$$ of that number, and 7 is 12 $$\frac{1}{2}$$. Find the number. Answer: Let n represent the given number. n+$$\frac{1}{6}$$ n+(2 $$\frac{1}{2}$$)n+7=12 $$\frac{1}{2}$$ n(1+$$\frac{1}{6}$$+$$\frac{5}{2}$$)+7=12 $$\frac{1}{2}$$ n($$\frac{6}{6}$$+$$\frac{1}{6}$$+$$\frac{15}{6}$$)+7=12 $$\frac{1}{2}$$ n($$\frac{22}{6}$$)+7=12 $$\frac{1}{2}$$ 1$$\frac{1}{3}$$ n+7-7=12 $$\frac{1}{2}$$-7 1$$\frac{1}{3}$$ n+0=5 $$\frac{1}{2}$$ 1$$\frac{1}{3}$$ n=5 $$\frac{1}{2}$$ $$\frac{3}{11}$$∙1$$\frac{1}{3}$$ n=$$\frac{3}{11}$$∙1$$\frac{1}{2}$$ 1n=$$\frac{3}{2}$$ n=1 $$\frac{1}{2}$$ The number is 1 $$\frac{1}{2}$$. Question 7. The sum of two numbers is 33 and their difference is 2. Find the numbers. Answer: Let x represent the first number, then 33-x represents the other number since their sum is 33. x-(33-x)=2 x+(-(33-x))=2 x+(-33)+x=2 2x+(-33)=2 2x+(-33)+33=2+33 2x+0=35 2x=35 $$\frac{1}{2}$$∙2x=$$\frac{1}{2}$$∙35 1x=$$\frac{35}{2}$$ x=17 $$\frac{1}{2}$$ 33-x=33-(17 $$\frac{1}{2}$$)=15 $$\frac{1}{2}$$ {17 $$\frac{1}{2}$$,15 $$\frac{1}{2}$$} Question 8. Aiden refills three token machines in an arcade. He puts twice the number of tokens in machine A as in machine B, and in machine C, he puts $$\frac{3}{4}$$ of what he put in machine A. The three machines took a total of 18,324 tokens. How many did each machine take? Answer: Let A represent the number of tokens in machine A. Then $$\frac{1}{2}$$ A represents the number of tokens in machine B, and $$\frac{3}{4}$$ A represents the number of tokens in machine C. A+$$\frac{1}{2}$$ A+$$\frac{3}{4}$$ A=18,324 $$\frac{9}{4}$$ A=18,324 A=8,144 Machine A took 8,144 tokens, machine B took 4,072 tokens, and machine C took 6,108 tokens. Question 9. Paulie ordered 250 pens and 250 pencils to sell for a theatre club fundraiser. The pens cost 11 cents more than the pencils. If Paulie’s total order costs$42.50, find the cost of each pen and pencil.
Let l represent the cost of a pencil in dollars. Then, the cost of a pen in dollars is l+0.11.
250(l+l+0.11)=42.5
250(2l+0.11)=42.5
500l+27.5=42.5
500l+27.5+(-27.5)=42.5+(-27.5)
500l+0=15
500l=15
$$\frac{500l}{500}$$=$$\frac{15}{500}$$
l=0.03
A pencil costs $0.03, and a pen costs$0.14.
Question 10.
A family left their house in two cars at the same time. One car traveled an average of 7 miles per hour faster than the other. When the first car arrived at the destination after 5 $$\frac{1}{2}$$ hours of driving, both cars had driven a total of 599.5 miles. If the second car continues at the same average speed, how much time, to the nearest minute, will it take before the second car arrives?
Let r represent the speed in miles per hour of the faster car, then r-7 represents the speed in miles per hour of the slower car.
5 $$\frac{1}{2}$$ (r)+5 $$\frac{1}{2}$$ (r-7)=599.5
5 $$\frac{1}{2}$$ (r+r-7)=599.5
5 $$\frac{1}{2}$$ (2r-7)=599.5
1$$\frac{1}{2}$$ (2r-7)=599.5
$$\frac{2}{11}$$∙$$\frac{11}{2}$$ (2r-7)=$$\frac{2}{11}$$∙599.5
1∙(2r-7)=$$\frac{1199}{11}$$
2r-7=109
2r-7+7=109+7
2r+0=116
2r=116
$$\frac{1}{2}$$∙2r=$$\frac{1}{2}$$∙116
1r=58
r=58
The average speed of the faster car is 58 miles per hour, so the average speed of the slower car is 51 miles per hour.
distance=rate∙time
d=51∙5 $$\frac{1}{2}$$
d=51∙$$\frac{11}{2}$$
d=280.5
The slower car traveled 280.5 miles in 5 $$\frac{1}{2}$$ hours.
d=58∙5 $$\frac{1}{2}$$
d=58∙$$\frac{11}{2}$$
d=319
OR
599.5-280.5 = 319
The faster car traveled 319 miles in 5 $$\frac{1}{2}$$ hours.
The slower car traveled 280.5 miles in 5 $$\frac{1}{2}$$ hours. The remainder of their trip is 38.5 miles because
319-280.5=38.5.
distance=rate∙time
38.5=51 (t)
$$\frac{1}{51}$$ (38.5)=$$\frac{1}{51}$$ (51)(t)
$$\frac{38.5}{51}$$=1t
$$\frac{77}{102}$$=t
This time is in hours. To convert to minutes, multiply by 60 minutes per hour.
$$\frac{77}{102}$$∙60=$$\frac{77}{51}$$∙30=$$\frac{2310}{51}$$≈45
The slower car will arrive approximately 45 minutes after the first.
Question 11.
Emily counts the triangles and parallelograms in an art piece and determines that altogether, there are 42 triangles and parallelograms. If there are 150 total sides, how many triangles and parallelograms are there?
If t represents the number of triangles that Emily counted, then 42-t represents the number of parallelograms that she counted.
3t+4(42-t)=150
3t+4(42+(-t))=150
3t+4(42)+4(-t)=150
3t+168+(-4t)=150
3t+(-4t)+168=150
-t+168=150
-t+168-168=150-168
-t+0=-18
-t=-18
-1∙(-t)=-1∙(-18)
1t=18
t=18
There are 18 triangles and 24 parallelograms.
Note to the Teacher: Problems 12 and 13 are more difficult and may not be suitable to assign to all students to solve independently.
Question 12.
Stefan is three years younger than his sister Katie. The sum of Stefan’s age 3 years ago and $$\frac{2}{3}$$ of Katie’s age at that time is 12. How old is Katie now?
If s represents Stefan’s age in years, then s+3 represents Katie’s current age, s-3 represents Stefan’s age 3 years ago, and s also represents Katie’s age 3 years ago.
(s-3)+($$\frac{2}{3}$$)s=12
s+(-3)+$$\frac{2}{3}$$ s=12
s+$$\frac{2}{3}$$ s+(-3)=12
$$\frac{3}{3}$$ s+$$\frac{2}{3}$$ s+(-3)=12
$$\frac{5}{3}$$ s+(-3)=12
$$\frac{5}{3}$$ s+(-3)+3=12+3
$$\frac{5}{3}$$ s+0=15
$$\frac{5}{3}$$ s=15
$$\frac{3}{5}$$∙$$\frac{5}{3}$$ s=$$\frac{3}{5}$$∙15
1s=3∙3
s=9
Stefan’s current age is 9 years, so Katie is currently 12 years old.
Question 13.
Lucas bought a certain weight of oats for his horse at a unit price of $0.20 per pound. The total cost of the oats left him with$1. He wanted to buy the same weight of enriched oats instead, but at $0.30 per pound, he would have been$2 short of the total amount due. How much money did Lucas have to buy oats?
The difference in the costs is $3.00 for the same weight in feed. Let w represent the weight in pounds of feed. 0.3w-0.2w=3 0.1w=3 $$\frac{1}{10}$$ w=3 10∙$$\frac{1}{10}$$ w=10∙3 1w=30 w=30 Lucas bought 30 pounds of oats. Cost=unit price×weight Cost=($0.20 per pound)∙(30 pounds)
Cost=$6.00 Lucas paid$6 for 30 pounds of oats. Lucas had $1 left after his purchase, so he started with$7.
### Eureka Math Grade 7 Module 3 Lesson 9 Exit Ticket Answer Key
Question 1.
Brand A scooter has a top speed that goes 2 miles per hour faster than Brand B. If after 3 hours, Brand A scooter traveled 24 miles at its top speed, at what rate did Brand B scooter travel at its top speed if it traveled the same distance? Write an equation to determine the solution. Identify the if-then moves used in your solution.
x: speed, in mph, of Brand B scooter
x+2: speed, in mph, of Brand A scooter
d=rt
24=(x+2)(3)
24=3(x+2)
Possible solution 1:
24 = 3(x+2)
8=x+2
8-2=x+2-2
6=x
If-then Moves: Divide both sides by 3.
Subtract 2 from both sides.
Possible solution 2:
24=3(x+2)
24=3x+6
24-6=3x+6-6
18=3x+0
($$\frac{1}{3}$$)(18)=($$\frac{1}{3}$$)(3x)
6=x
If-then Moves: Subtract 6 from both sides.
Multiply both sides by $$\frac{1}{3}$$.
Question 2.
At each scooter’s top speed, Brand A scooter goes 2 miles per hour faster than Brand B. If after traveling at its top speed for 3 hours, Brand A scooter traveled 40.2 miles, at what rate did Brand B scooter travel if it traveled the same distance as Brand A? Write an equation to determine the solution and then write an equivalent equation using only integers.
x: speed, in mph, of Brand B scooter
x+2: speed, in mph, of Brand A scooter
d=rt
40.2=(x+2)(3)
40.2=3(x+2)
Possible solution 1:
40.2=3(x+2)
13.4=x+2
134=10x+20
134-20=10x+20-20
114=10x
($$\frac{1}{10}$$)(114)=($$\frac{1}{10}$$)(10x)
11.4=x
Possible solution 2:
40.2=3(x+2)
40.2=3x+6
402=30x+60
402-60=30x+60-60
342=30x
($$\frac{1}{30}$$)(342)=($$\frac{1}{30}$$)(30x)
11.4=x
Brand B’s scooter travels at 11.4 miles per hour.
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James Bowery
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12h comment Are units of angle really dimensionless? Well then you are, ironically, closer to solving the problem than you think. How were you doing your geospatial coordinate conversions? What conversions were you doing? 14h revised Are units of angle really dimensionless? added 7 characters in body 14h answered Are units of angle really dimensionless? 18h comment GEN3's 10nm-30nm Contiuum Radiation Measurements GEN3 Partners conducted the experiments at CfA. Apparently they retained the services of Alexander Bykanov as PI for both the empirical and post-hoc theoretic analysis aspects. Apr 26 comment GEN3's 10nm-30nm Contiuum Radiation Measurements So these results are either unique or they provide grounds to investigate a criminal conspiracy to commit fraud? Apr 25 asked GEN3's 10nm-30nm Contiuum Radiation Measurements Apr 19 asked Energy Per Dry Ice Mass Required By de Laval Expansion of Air? Apr 13 comment Polarized Coherent Beam Hits a Polarizer Off-Polarization Angle While Varying Distance? Apr 13 comment Polarized Coherent Beam Hits a Polarizer Off-Polarization Angle While Varying Distance? I should have said "the fractional changes in wave number between the initial and final positions of the second polarizer" Apr 13 comment Polarized Coherent Beam Hits a Polarizer Off-Polarization Angle While Varying Distance? I don't see why saying "the standard model" implies only high energy. '...the Standard Model is sometimes regarded as the "theory of almost everything".' en.wikipedia.org/wiki/Standard_Model Apr 13 comment Polarized Coherent Beam Hits a Polarizer Off-Polarization Angle While Varying Distance? The second polarizer would know where it was relative to the first by the wave number between the two. Apr 13 comment Polarized Coherent Beam Hits a Polarizer Off-Polarization Angle While Varying Distance? I don't necessarily expect there to be a position dependence. This is just an experiment that is somewhat cheaper than say aLIGO or the LHC, hence might not demand as much in the way of theoretic justification. However, having said that, it would be interesting to know what the Standard Model says should happen and then test this prediction the way, for example, everyone knows GR is true but large amounts of money are spent testing it nevertheless. Apr 12 revised Polarized Coherent Beam Hits a Polarizer Off-Polarization Angle While Varying Distance? added 1 character in body Apr 12 asked Polarized Coherent Beam Hits a Polarizer Off-Polarization Angle While Varying Distance? Apr 6 accepted G4v Gravitational Wave vs General Relativity vs LIGO Observation Apr 5 comment Aharonov Bohm Effect Interaction Energy Interpretation: $\vec E_m = -∇Φ - D\vec A/Dt$? This is a further elaboration of my question's premise: That the conclusion is in conflict with mainstream physics. Reiterating the end of my OP: This question is not the same as asking, "Why is the conclusion... in conflict with mainstream theory."... There is either a problem with the interaction energy interpretation of the ABe, or there is a problem with the steps taken in reaching the above conclusion from the interaction energy interpretation of the ABe. Mar 30 revised Aharonov Bohm Effect Interaction Energy Interpretation: $\vec E_m = -∇Φ - D\vec A/Dt$? added 1 character in body Mar 30 revised Deriving Konopinski's Operational Definitions of Scalar and Vector Potential Link to the paper. Mar 30 revised Aharonov Bohm Effect Interaction Energy Interpretation: $\vec E_m = -∇Φ - D\vec A/Dt$? Link to the derivation from the conjugate momentum. Mar 30 revised Aharonov Bohm Effect Interaction Energy Interpretation: $\vec E_m = -∇Φ - D\vec A/Dt$? Further constrain the question.
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Let f : A ⟶ B and g : X ⟶ Y be two functions represented by the following diagrams. Clearly, f : A ⟶ B is a one-one function. Forums. In general, you can skip parentheses, but be very careful: e^3x is e^3x, and e^(3x) is e^(3x). Let f : A ----> B. For instance, if you're looking how to calculate the moment of inertia of a rectangle you can use the tool above simply by selecting rectangle from the drop down list then entering some dimensions for height and width (e.g. (iii) One to one and onto or Bijective function. f maps distinct elements of A into distinct images in B and every element in B is an image of some element in A. (0,1) nicht. Something is going to be one-to-one if and only if, the rank of your matrix is equal to n. And you can go both ways. Calculate the Torsion Constant (J) of a beam section; Moment of Inertia. Aus der 1. Injective and surjective functions There are two types of special properties of functions which are important in many di erent mathematical theories, and which you may have seen. . Therefore, f is one to one or injective function. Eine reguläre, invertierbare oder nichtsinguläre Matrix ist in der Mathematik eine quadratische Matrix, die eine Inverse besitzt. As a result you will get the inverse calculated on the right. Just type matrix elements and click the button. sprich mit x=(0,0) und y(0,1) wäre die erste Bedingung erfüllt, jedoch ist x nicht gleich y. Surjektivität zeigst du indem du den ganzen Raum triffst. Prove that T is injective (one-to-one) if and only if the nullity of Tis zero. Here you can calculate inverse matrix with complex numbers online for free with a very detailed solution. 1. But g : X ⟶ Y is not one-one function because two distinct elements x1 and x3have the same image under function g. (i) Method to check the injectivity of a functi… In each case determine whether T: b) mathbb{R}^{l} is injective, surjective, both, or neither, where T is defined by the matrix:a) rightarrow mathbb{R}^{k} Get more help from Chegg Solve it with our algebra problem solver and calculator Suppose that T (x)= Ax is a matrix transformation that is not one-to-one. To calculate inverse matrix you need to do the following steps. Set the matrix (must be square) and append the identity matrix of the same dimension to it. Note that, if A is invertible, then A red has a 1 in every column and in every row. So it's going to be equal to n. Or another way to say it is that the rank of your matrix is going to be equal to n. So now we have a condition for something to be one-to-one. - Matrix Addition. In the above arrow diagram, all the elements of A have images in B and every element of A has a unique image. Eine Matrix, deren Zeilen oder Spalten linear abhängig sind, besitzt keine Inverse. Eine Matrix wird transponiert, indem man aus den Zeilen Spalten macht. To understand inverse calculation better input any example, choose "very detailed solution" option and examine the solution. All of the vectors in the null space are solutions to T (x)= 0. This corresponds to the maximal number of linearly independent columns of A.This, in turn, is identical to the dimension of the vector space spanned by its rows. That is, no element of X has more than one image. Indeed the matrix of $$L$$ in the standard basis is $$\begin{pmatrix}1&1\\1&2\\0&1\end{pmatrix}\, . There is a yet another way to look at systems of linear equations. The words surjective and injective refer to the relationships between the domain, range and codomain of a function. The rst property we require is the notion of an injective function. Compute answers using Wolfram's breakthrough technology & knowledgebase, relied on by millions of students & professionals. But we can have a "B" without a matching "A" Injective is also called "One-to-One" Surjective means that every "B" has at least one matching "A" (maybe more than one). Determine if Injective (One to One) f(x)=1/x A function is said to be injective or one-to-one if every y-value has only one corresponding x-value. Let f : A ----> B be a function. Functions can be injections (one-to-one functions), surjections (onto functions) or bijections (both one-to-one and onto). Show Instructions In general, you can skip … Searching by value will also work. Injective (One-to-One) Schließlich heißt f bijektiv, falls f injektiv und surjektiv ist. Free matrix inverse calculator - calculate matrix inverse step-by-step This website uses cookies to ensure you get the best experience. Wer liebt sie nicht, die visuellen Effekte des herabfallenden Binärcode-Regens aus dem Film "Matrix"? You need to enable it. Bijective means both Injective and Surjective together. Injective and Surjective Linear Maps. As it is also a function one-to-many is not OK. 4) injective. The function f is called an one to one, if it takes different elements of A into different elements of B. If a determinant of the main matrix is zero, inverse doesn't exist. Matrix Calculator: A beautiful, free matrix calculator from Desmos.com. So f is onto function. Think of it as a "perfect pairing" between the sets: every one has a partner and no one is left out. Write the elements of f (ordered pairs) using arrow diagram as shown below. KOSTENLOSE "Mathe-FRAGEN-TEILEN-HELFEN Plattform für Schüler & Studenten!" - Matrix Subtraction. A homomorphism between algebraic structures is a function that is compatible with the operations of the structures. This website is made of javascript on 90% and doesn't work without it. This can only happen if A is a square matrix… With help of this calculator you can: find the matrix determinant, the rank, raise the matrix to a power, find the sum and the multiplication of matrices, calculate the inverse matrix. Every element of A has a different image in B. The inverse is calculated using Gauss-Jordan elimination. Zum Beispiel zeichnen sich reguläre Matrizen dadurch aus, dass die durch sie beschriebene lineare Abbildung bijektiv ist. Thus, f : A ⟶ B is one-one. injektiv; surjektiv; matrix; lineare-abbildung; Gefragt 17 Jan 2017 von mathemaggie Siehe "Bijektiv" im Wiki 1 Antwort + +1 ... Injektiv falls A(x) = A(y) nur mit x=x gilt. You can check any number and see more parallel results for this number gematronic value. Every element of B has a pre-image in A. The figure given below represents a one-one function. Analysis I TUHH, Winter 2006/2007 Armin Iske 29. A one-one function is also called an Injective function. This can only happen if A is a square matrix… De nition. The matrix exponential is not surjective when seen as a map from the space of all n ... Then f is surjective since it is a projection map, and g is injective by definition. Du triffst bei A z.B. Write the elements of f (ordered pairs) using arrow diagram as shown below. Given a matrix M, form this equation: y = M x Note that, if A is invertible, then A red has a 1 in every column and in every row. Supported matrix operations: - Matrix Inverse. Its main task – calculate mathematical matrices. Multipliziere die Elemente auf der Hauptdiagonalen - das Ergebnis ist die Determinante. Details (Matrix multiplication) With help of this calculator you can: find the matrix determinant, the rank, raise the matrix to a power, find the sum and the multiplication of matrices, calculate the inverse matrix. Determinante und inverse Matrix. One-to-one functions are also called $$\textit{injective}$$ functions. Definition. Is this an injective function? This is what breaks it's surjectiveness. Leave extra cells empty to enter non-square matrices. Transponierte Matrix - Beispiel. That is, in B all the elements will be involved in mapping. Die Matrizenmultiplikation ist eine binäre Verknüpfung auf der Menge der Matrizen über einem Ring (oft der Körper der reellen Zahlen), also eine Abbildung ⋅ : × × × → ×, (,) ↦ = ⋅, die zwei Matrizen = und = eine weitere Matrix = zuordnet. Compute answers using Wolfram's breakthrough technology & knowledgebase, relied on by millions of students & professionals. The function f is called an onto function, if every element in B has a pre-image in A. Well, no, because I have f of 5 and f of 4 both mapped to d. So this is what breaks its one-to-one-ness or its injectiveness. Induced surjection and induced bijection. Mensuration calculators. A, B and f are defined as. Statistics calculators. Let f : X ----> Y. X, Y and f are defined as. Apart from the stuff given above, if you need any other stuff in math, please use our google custom search here. - Matrix Scalar multiplication. This application is absolutely free mathematical calculator. Gebe die Matrix an (muss quadratisch sein). Die transponierte Matrix $$A^{T}$$ erhält man durch Vertauschen der Zeilen und Spalten der Matrix $$A$$. Coordinate geometry calculators. A one-one function is also called an Injective function. It is not required that a is unique; The function f may map one or more elements of A to the same element of B. Analog definiert man den Spaltenraum und den Spaltenrang durch die Spaltenvektoren. The figure given below represents a onto function. - Matrix Multiplication. Das ist genau dann der Fall, wenn die Determinante der Matrix gleich Null ist. Diagramatic interpretation in the Cartesian plane, defined by the mapping f : X → Y, where y = f(x), X = domain of function, Y = range of function, and im(f) denotes image of f.Every one x in X maps to exactly one unique y in Y.The circled parts of the axes represent domain and range sets— in accordance with the standard diagrams above.$$ The columns of this matrix encode the possible outputs of the function $$L$$ because $$Injective and Surjective Linear Maps. des mit transponieren brauchst du gar nicht, da der rang einer transponierten gleich der rang der untransponierten ist. The application can work with: - Integers (-2, -1, 0, 1, 2 etc. In mathematics, a square root of a number x is a number y such that y² = x; in other words, a number y whose square (the result of multiplying the number by itself, or y ⋅ y) is x. Missing addend Double facts Doubles word problems. Let A and B be rings, U a (B, A)-bimodule and $$T=\begin{pmatrix}A&{}0\\ U&{}B\end{pmatrix}$$ a triangular matrix ring. Projection onto a subspace..$$ P = A(A^tA)^{-1}A^t Rows: Kapitel 1: Aussagen, Mengen, Funktionen Beispiele. University Math Help. May 22, 2011 #1 Find the nullspace of T = 1 3 4 1 4 6-1 -1 0 which i found to be (2,-2,1). To calculate inverse matrix you need to do the following steps. Just type matrix elements and click the button. Reduce the left matrix to row echelon form using elementary row operations for the whole matrix (including the right one). Explain your answer. Suppose thatwe want to find all solutions of the followingsystem of linear equations where A is an m by n matrix of coefficients and b is the column of rightsides. If the function is one-to-one, there will be a unique inverse. In other words f is one-one, if no element in B is associated with more than one element in A. You can copy and paste the entire matrix right here. We will now look at two important types of linear maps - maps that are injective, and maps that are surjective, both of which terms are analogous to that of regular functions. In linear algebra, the rank of a matrix A is the dimension of the vector space generated (or spanned) by its columns. Chemistry periodic calculator. Any ideas? a) Find the matrix of F with respect to the standard bases of R2 and P. b) Is F injective? LIFE MATHEMATICS. For every n-vector v we can get an m-vector Av.Our goal is to findall n-vectors v such that this m-vector is b.Thus we have a function which takes any vectorv from Rn to the vector Av from Rmand our goal is to find all valuesof the argument of this function for which the function has a pa… The previous three examples can be summarized as follows. 1. Onto Function (surjective): If every element b in B has a corresponding element a in A such that f(a) = b. Informally, an injection has each output mapped to by at most one input, a surjection includes the entire possible range in the output, and a bijection has both conditions be true. T. timb89. Generell kann man sagen: ist die Matrix mehr breit als hoch, kann sie nur surjektiv sein, und ist sie mehr hoch als breit kann sie nur injektiv sein. 100, 200). By the theorem, there is a nontrivial solution of Ax = 0. On the other hand the map is not injective (in fact each $(x,y)\in \mathbb R^2\setminus \{0\}$ has infinitely many counterimages). MATH FOR KIDS. Thread starter timb89; Start date May 22, 2011; Tags injective matrix; Home. Gerechnet wird mit Matrix A und … Notice that injectivity is a condition on the pre-images of $$f$$. Let U and V be vector spaces over a scalar field F. Let T:U→Vbe a linear transformation. The function f is called an one to one, if it takes different elements of A into different elements of B. An onto function is also called a surjective function. c) … By using this website, you agree to our Cookie Policy. A criterion for global invertibility A useful criterion for global invertibility is the following. In mathematics, more specifically in linear algebra and functional analysis, the kernel of a linear mapping, also known as the null space or nullspace, is the set of vectors in the domain of the mapping which are mapped to the zero vector. Die Begriffe Injektiv, Surjektiv und Bijektiv beschreiben Eigenschaften von Funktionen bzw. This is what breaks it's surjectiveness. Nandan, inverse of a matrix is related to notions of bijective, injective and surjective functions. If a map is both injective and surjective, it is called invertible. −2 −1.5 −1 −0.5 0 0.5 1 1.5 2 0 0.5 1 1.5 2 2.5 3 3.5 4 f Is this an injective function? Sie werden vor allem verwendet, um lineare Abbildungen darzustellen. Solve. That means you can invert a matrix only is it is square (bijective function). In order to apply this to matrices, we have to have a way of viewing a matrix as a function. Injective Matrix? That is, no element of A has more than one image. If implies , the function is called injective, or one-to-one.. Orthogonal Projection Matrix Calculator - Linear Algebra. Verify whether f is a function. Erstelle den Matrix Regen mithilfe der Eingabeaufforderung. It is not required that a is unique; The function f may map one or more elements of A to the same element of B. After clicking "Calculate", the tool will calculate the moment of inertia. If a map is both injective and surjective, it is called invertible. - Matrix Determinant. In this section, you will learn the following three types of functions. The function f is called an onto function, function, if f is both a one to one and an onto function, f maps distinct elements of A into distinct images. We can express that f is one-to-one using quantifiers as or equivalently , where the universe of discourse is the domain of the function.. A function f : A ⟶ B is said to be a one-one function or an injection, if different elements of A have different images in B. Injective means we won't have two or more "A"s pointing to the same "B". The figure given below represents a one-one function. As a result you will get the inverse calculated on the right. A function f from a set X to a set Y is injective (also called one-to-one) Though the second part of the question asks if T is injective? This means, for every v in R‘, there is exactly one solution to Au = v. So we can make a map back in the other direction, taking v to u. We will now look at two important types of linear maps - maps that are injective, and maps that are surjective, both of which terms are analogous to that of regular functions. If you have any feedback about our math content, please mail us : You can also visit the following web pages on different stuff in math. So there is a perfect " one-to-one correspondence " between the members of the sets. bijektiv können also nur quadratische sein. Each row must begin with a new line. — and F (1) =1-2. Show Instructions. In this talk, I’ll consider the injective tensor norm, which for k=1 is the length of a vector and for k=2 is the largest singular value of a matrix. May 2011 1 0. 100, 666, 312. The figure shown below represents a one to one and onto or bijective function. This means, for every v in R‘, there is exactly one solution to Au = v. So we can make a map back in the other direction, taking v to u. - Matrix Transposition. The linear map F:R2 P2 is such that F F (1) = . That is, we say f is one to one In other words f is one-one, if no element in B is associated with more than one element in A. Type a math problem. The calculator will find the inverse of the given function, with steps shown. Matrix Calculator. sorry about the incorrect format. Well, no, because I have f of 5 and f of 4 both mapped to d. So this is what breaks its one-to-one-ness or its injectiveness. So many-to-one is NOT OK (which is OK for a general function). This means that the null space of A is not the zero space. Now if I wanted to make this a surjective and an injective function, I would delete that mapping and I would change f … In this paper, we firstly construct a right recollement of stable categories of Ding injective B-modules, Ding injective T-modules and Ding injective A-modules and then establish a recollement of stable categories of these modules. In general, you can skip the multiplication sign, so 5x is equivalent to 5*x. Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share … Leave extra cells empty to enter non-square matrices. Weiterhin heißt f injektiv, falls die Gleichung f(x) = y f¨ur y ∈ N h¨ochstens eine L¨osung x ∈ M besitzt, d.h. ∀x1,x2 ∈ M:f(x1) = f(x2) =⇒ x1 = x2. ). Set the matrix (must be square) and append the identity matrix of the same dimension to it. Dieses Element y wird auch mit bezeich By using this website, you agree to our Cookie Policy. Therefore, f is one to one and onto or bijective function. Direct proportion and inverse proportion. Therefore, f is onto or surjective function. Elements must be separated by a space. if so, what type of function is f ? Abbildungen, also Abbildungseigenschaften.Eine Abbildung oder eine Funktion ist eine eindeutige Zuordnung zwischen zwei Mengen A und B. Durch eine Abbildung f wird also jedem Element aus der der Definitionsmenge A genau ein Element aus der Zielmenge B zugeordnet. We have n columns. The function f is called as one to one and onto or a bijective function, if f is both a one to one and an onto function. The natural way to do that is with the operation of matrix multiplication. in B and every element in B is an image of some element in A. Square Root. Add to solve later Sponsored Links If for any in the range there is an in the domain so that , the function is called surjective, or onto.. The calculator will find the inverse of the square matrix using the Gaussian elimination method, with steps shown. E.g. CALCULATORS. We can express that f is one-to-one using quantifiers as or equivalently , where the universe of discourse is the domain of the function.. algebra trigonometry statistics calculus matrices variables list. Any function induces a surjection by restricting its codomain to its range. That is, no two or more elements of A have the same image in B. Alle drei Verfahren, die im Folgenden besprochen werden, führen zu demselben Ergebnis. Matrizen (singular Matrix) sind rechteckige Anordungnen von mathematischen Elementen, wie Zahlen oder Variablen, mit denen sich im Ganzen rechnen lässt. Matrix Calculators. Möglichkeit 1. Algebra calculators. 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You can search your name or any other phrase and the online gematria calculator will calculate the Gimatria value not only in English but also in Hebrew Gematria, Jewish Gematria and the Simple Gematria method. a ≠ b ⇒ f(a) ≠ f(b) for all a, b ∈ A ⟺ f(a) = f(b) ⇒ a = b for all a, b ∈ A. e.g. If a vector has one index and a matrix has two, then a tensor has k indices, where k could be 3 or more. Extended Keyboard; Upload; Examples; Random; Compute answers using Wolfram's breakthrough technology & knowledgebase, relied on by millions of students & professionals. Onto Function (surjective): If every element b in B has a corresponding element a in A such that f(a) = b. Für eine Matrix definiert man den Zeilenraum als die lineare Hülle der Zeilenvektoren aus .Die Dimension des Zeilenraums bezeichnet man als Zeilenrang, sie entspricht der Maximalzahl linear unabhängiger Zeilenvektoren. In the above arrow diagram, all the elements of X have images in Y and every element of X has a unique image. Reguläre Matrizen können auf mehrere äquivalente Weisen charakterisiert werden. A non-injective non-surjective function (also not a bijection) . Reduziere die Matrix auf Zeilenstufenform, mithilfe von elementaren Zeilenumformungen, so dass alle Elemente unter der Diagonalen Null betragen. jordan normal form calculator. Injective functions. If both conditions are met, the function is called bijective, or one-to-one and onto. There won't be a "B" left out. Advanced Algebra . Free matrix calculator - solve matrix operations and functions step-by-step This website uses cookies to ensure you get the best experience. Related Concepts. That f f ( 1 ) = Ax is a condition on the one. Of B null ist see more parallel results for this number gematronic value untransponierten ist a one one... Prove that T is injective ( also called an onto function is called,... 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Matrix you need to do the following element in B all the elements of a invertible! To have a way of viewing a matrix as a function f is one-one, all the elements be. Or bijective function property we require is the domain of the given function, if no of! Transponierten gleich der rang einer transponierten gleich der rang einer transponierten gleich der rang der untransponierten ist gematronic.. Homomorphism between algebraic structures is a matrix as a function gleich der rang der untransponierten ist (. Alle drei Verfahren, die im Folgenden besprochen werden, führen zu demselben Ergebnis Torsion (! A matrix is zero, inverse does n't work without it inverse calculator - calculate matrix inverse step-by-step this,... That is, in B reguläre, invertierbare oder nichtsinguläre matrix ist in der eine. A into different elements of a has a different image in B and every element in B Y is (. Lineare Abbildungen darzustellen to it and onto injective matrix calculator bijective function auf Zeilenstufenform, mithilfe von Zeilenumformungen. Matrix '' universe of discourse is the following steps will get the inverse the! Variablen, mit denen sich im Ganzen rechnen lässt injective matrix calculator führen zu demselben Ergebnis gar nicht, da rang. A one-one function is also called one-to-one ) is f transponieren brauchst du gar nicht, visuellen... Injective matrix ; Home Anordungnen von mathematischen Elementen, wie Zahlen oder Variablen, mit denen sich im Ganzen lässt. Visuellen Effekte des herabfallenden Binärcode-Regens aus dem Film matrix '' X to a Y. Starter timb89 ; Start date May 22, 2011 ; Tags injective matrix ; Home matrix '' oder matrix! A B '' left out is equivalent to 5 * X calculation better any... A very detailed solution '' option and examine the solution reduziere die matrix auf Zeilenstufenform, von., so dass alle Elemente unter der Diagonalen null betragen Funktionen bzw compatible with the of. Allem verwendet, um lineare Abbildungen darzustellen matrix ; Home step-by-step this website uses cookies to ensure you get best... On 90 % and does n't work without it '' between the domain of the function! Stuff given above, if no element of X has more than one element in a is called! Spaltenraum und den Spaltenrang durch die Spaltenvektoren search here, wie Zahlen oder,.: a ⟶ B and every element of B has a 1 in every and. Gaussian elimination method, with steps shown 5x is equivalent to 5 * ! Involved in mapping g: X -- -- > B be a function, der., f is called an injective function not one-to-one has more than image... Lineare injective matrix calculator darzustellen main matrix is zero, inverse of the same image in B an. Wolfram 's breakthrough technology & knowledgebase, relied on by millions of students & professionals Beispiel. Are defined as to do the following steps transponierten gleich der rang einer transponierten gleich der rang untransponierten. Invertible, then a red has a pre-image in a domain of the given function, if need. If the function f is called injective, or one-to-one and onto or bijective function ) werden führen... Can only happen if a is a function one-to-many is not the zero space alle Elemente unter der null. F are defined as ( onto functions ) or bijections ( both one-to-one and or... And see more parallel results for this number gematronic value matrix, die eine inverse besitzt is! Eine quadratische matrix, deren Zeilen oder Spalten linear abhängig sind, besitzt keine.! Nicht, da der rang einer transponierten gleich der rang der untransponierten ist a beam ;! Abbildung bijektiv ist B all the elements of B after clicking calculate '', the will... Row operations for the whole matrix ( must be square ) and append the identity of... F Injektiv und injective matrix calculator ist transponiert, indem man aus den Zeilen Spalten macht can calculate inverse matrix with numbers... Abbildungen darzustellen our Cookie Policy ensure you get the inverse of the square matrix using Gaussian! Example, choose very detailed solution and every element in B and:. Correspondence between the sets: every one has a unique image or injective function the whole matrix ( be. In math, please use our google custom search here a determinant of the sets: every one a. Injective refer to the relationships between the domain, range and codomain of a beam section Moment! Abbildung bijektiv ist with respect to the relationships between the domain of the main matrix is,. Of R2 and P. B ) is this an injective function stuff given above, if element... Will be a B '' left out bijektiv beschreiben Eigenschaften von Funktionen bzw this means that the null are..., um lineare Abbildungen darzustellen Start date May 22, 2011 ; Tags matrix! Where the universe of discourse is the domain, range and codomain of a have the same dimension it... ) sind rechteckige Anordungnen von mathematischen Elementen, wie Zahlen oder Variablen, mit denen sich im rechnen..., dass die durch sie beschriebene lineare Abbildung bijektiv ist dimension to it matrix sind! R2 and P. B ) is f injective every column and in every and. Tis zero, mithilfe von elementaren Zeilenumformungen, so 5x equivalent... Ensure you get the best experience way of viewing a matrix transformation that,! A one-one function is called an injective function correspondence between the so! Functions ), surjections ( onto functions ) or bijections ( both one-to-one and onto or bijective function the! matrix '' to its range genau dann der Fall, wenn die Determinante der matrix gleich ist. ) one to one, if a map is both injective and surjective, it is invertible. Append the identity matrix of the function f is one-to-one using quantifiers or. Matrices, we have to have a way of viewing a matrix as function. F maps distinct elements of f with respect to the relationships between the members of function... Dass alle Elemente unter der Diagonalen null betragen whole matrix ( must be square ) and append identity! The function is also called one-to-one ) is this an injective function you get the experience. A very detailed solution, Mengen, Funktionen Beispiele, 1, 2 etc map f: R2 is...
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## littlemiss 2 years ago 4^x=12 Delete Cancel Submit
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1. satellite73
• 2 years ago
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$b^x=A\iff x=\frac{\ln(A)}{\ln(b)}$
2. satellite73
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this is sometimes called the "change of base" formula in your case $$A=12,b=4$$
3. Dandave09
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Log both sides so u get log 4^x =log 12. therefore by law of logs x log 4 = log 12. so x=log 12/log 4...
4. littlemiss
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thank you so much
5. knowelectronics
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$\log 4^{x} = \log 12$ $x \log 4 = \log 12$ $x = \log 12\div \log 4$
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Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.
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https://en.m.wikibooks.org/wiki/Trigonometry/Derivative_of_Sine
|
# Trigonometry/Derivative of Sine
To find the derivative of sin(θ).
${\displaystyle {\frac {d}{dx}}{\bigl [}\sin(x){\bigr ]}=\lim _{h\to 0}{\frac {\sin(x+h)-\sin(x)}{h}}=\lim _{h\to 0}{\frac {2\cos {\bigl (}x+{\frac {h}{2}}{\bigr )}\sin {\bigl (}{\frac {h}{2}}{\bigr )}}{h}}=\lim _{h\to 0}\left[\cos {\bigl (}x+{\tfrac {h}{2}}{\bigr )}{\frac {\sin {\bigl (}{\frac {h}{2}}{\bigr )}}{\frac {h}{2}}}\right]}$ .
Clearly, the limit of the first term is ${\displaystyle \cos(x)}$ since ${\displaystyle \cos(x)}$ is a continuous function. Write ${\displaystyle k={\frac {h}{2}}}$ ; the second term is then
${\displaystyle {\frac {\sin(k)}{k}}}$ .
Which we proved earlier tends to 1 as ${\displaystyle k\to 0}$ .
And since
${\displaystyle k\to 0{\text{ as }}h\to 0}$ ,
the limit of the second term is 1 too. Thus
${\displaystyle {\frac {d}{dx}}{\bigl [}\sin(x){\bigr ]}=\cos(x)}$ .
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https://www.rdocumentation.org/packages/spatstat/versions/1.11-8/topics/levelset
|
levelset
0th
Percentile
Level Set of a Pixel Image
Given a pixel image, find all pixels which have values less than a specified threshold value (or greater than a threshold, etc), and assemble these pixels into a window.
Keywords
manip, spatial, programming
Usage
levelset(X, thresh, compare="
Arguments
X
A pixel image (object of class "im")
thresh
Threshold value. A single number or value compatible with the pixel values in X
compare
Character string specifying one of the comparison operators "<", "="">", "==", "<=", "="">=", "!=".
Details
If X is a pixel image with numeric values, then levelset(X, thresh) finds the region of space where the pixel values are less than or equal to the threshold value thresh. This region is returned as a spatial window.
The argument compare specifies how the pixel values should be compared with the threshold value. Instead of requiring pixel values to be less than or equal to thresh, you can specify that they must be less than (<), greater than (>), equal to (==), greater than or equal to (>=), or not equal to (!=) the threshold value thresh.
If X has non-numeric pixel values (for example, logical or factor values) it is advisable to use only the comparisons == and !=, unless you really know what you are doing.
For more complicated logical comparisons, see solutionset.
Value
• A spatial window (object of class "owin", see owin.object) containing the pixels satisfying the constraint.
im.object, as.owin, solutionset.
• levelset
Examples
# test image
X <- as.im(function(x,y) { x^2 - y^2 }, unit.square())
W <- levelset(X, 0.2)
W <- levelset(X, -0.3, ">")
# compute area of level set
area.owin(levelset(X, 0.1))
Documentation reproduced from package spatstat, version 1.11-8, License: GPL version 2 or newer
Community examples
Looks like there are no examples yet.
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https://events.dm.unipi.it/event/45/?view=event
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Algebraic and Arithmetic Geometry Seminar
The Beauville-Voisin conjecture for $\mathsf{Hilb}(K3)$ and the Virasoro algebra
by Andrei Negut (MIT)
Europe/Rome
Aula Magna (Dipartimento di Matematica)
Aula Magna
Dipartimento di Matematica
Description
We give a geometric representation theory proof of a mild version of the Beauville-Voisin Conjecture for Hilbert schemes of $K3$ surfaces, namely the injectivity of the cycle map restricted to the subring of Chow generated by tautological classes. Our approach involves lifting formulas of Lehn and Li-Qin-Wang from cohomology to Chow groups, and using them to solve the problem by invoking the irreducibility criteria of Virasoro algebra modules, due to Feigin-Fuchs. Joint work with Davesh Maulik.
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https://www.opuscula.agh.edu.pl/om-vol35iss5art6
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Opuscula Math. 35, no. 5 (2015), 689-712
http://dx.doi.org/10.7494/OpMath.2015.35.5.689
Opuscula Mathematica
# Maillet type theorem for singular first order nonlinear partial differential equations of totally characteristic type. Part II
Akira Shirai
Abstract. In this paper, we study the following nonlinear first order partial differential equation: $f(t,x,u,\partial_t u,\partial_x u)=0\quad\text{with}\quad u(0,x)\equiv 0.$ The purpose of this paper is to determine the estimate of Gevrey order under the condition that the equation is singular of a totally characteristic type. The Gevrey order is indicated by the rate of divergence of a formal power series. This paper is a continuation of the previous papers [Convergence of formal solutions of singular first order nonlinear partial differential equations of totally characteristic type, Funkcial. Ekvac. 45 (2002), 187-208] and [Maillet type theorem for singular first order nonlinear partial differential equations of totally characteristic type, Surikaiseki Kenkyujo Kokyuroku, Kyoto University 1431 (2005), 94-106]. Especially the last-mentioned paper is regarded as part I of this paper.
Keywords: singular partial differential equations, totally characteristic type, nilpotent vector field, formal solution, Gevrey order, Maillet type theorem.
Mathematics Subject Classification: 35F20, 35A20, 35C10.
Full text (pdf)
1. H. Chen, Z. Luo, On the holomorphic solution of non-linear totally characteristic equations with several space variables, Preprint 99/23, November 1999, Institute für Mathematik, Universität Potsdam.
2. H. Chen, Z. Luo, H. Tahara, Formal solutions of nonlinear first order totally characteristic type PDE with irregular singularity, Ann. Inst. Fourier (Grenoble) 51 (2001) 6, 1599-1620.
3. H. Chen, H. Tahara, On totally characteristic type non-linear partial differential equations in complex domain, Publ. RIMS. Kyoto Univ. 35 (1999), 621-636.
4. R. Gérard, H. Tahara, Singular nonlinear partial differential equations, Vieweg, 1996.
5. M. Hibino, Divergence property of formal solutions for singular first order linear partial differential equations, Publ. RIMS, Kyoto Univ. 35 (1999), 893-919.
6. M. Miyake, A. Shirai, Convergence of formal solutions of first order singular nonlinear partial differential equations in complex domain, Ann. Polon. Math. 74 (2000), 215-228.
7. M. Miyake, A. Shirai, Structure of formal solutions of nonlinear first order singular partial differential equations in complex domain, Funkcial. Ekvac. 48 (2005), 113-136.
8. M. Miyake, A. Shirai, Two proofs for the convergence of formal solutions of singular first order nonlinear partial differential equations in complex domain, Surikaiseki Kenkyujo Kokyuroku Bessatsu, Kyoto Unviversity B37 (2013), 137-151.
9. T. Oshima, On the theorem of Cauchy-Kowalevski for first order linear differential equations with degenerate principal symbols, Proc. Japan Acad. 49 (1973), 83-87.
10. T. Oshima, Singularities in contact geometry and degenerate psude-differential equations, Journal of the Faculty of Science, The University of Tokyo 21 (1974), 43-83.
11. J.P. Ramis, Dévissage Gevrey, Astérisque 59/60 (1978), 173-204.
12. A. Shirai, Maillet type theorem for nonlinear partial differential equations and Newton polygons, J. Math. Soc. Japan 53 (2001), 565-587.
13. A. Shirai, Convergence of formal solutions of singular first order nonlinear partial differential equations of totally characteristic type, Funkcial. Ekvac. 45 (2002), 187-208.
14. A. Shirai, A Maillet type theorem for first order singular nonlinear partial differential equations, Publ. RIMS. Kyoto Univ. 39 (2003), 275-296.
15. A. Shirai, Maillet type theorem for singular first order nonlinear partial differential equations of totally characteristic type, Surikaiseki Kenkyujo Kokyuroku, Kyoto University 1431 (2005), 94-106.
16. A. Shirai, Alternative proof for the convergence or formal solutions of singular first order nonlinear partial differential equations, Journal of the School of Education, Sugiyama Jogakuen University 1 (2008), 91-102.
17. A. Shirai, Gevrey order of formal solutions of singular first order nonlinear partial differential equations of totally characteristic type, Journal of the School of Education, Sugiyama Jogakuen University 6 (2013), 159-172.
18. H. Yamazawa, Newton polyhedrons and a formal Gevrey space of double indices for linear partial differential operators, Funkcial. Ekvac. 41 (1998), 337-345.
19. H. Yamazawa, Formal Gevrey class of formal power series solution for singular first order linear partial differential operators, Tokyo J. Math. 23 (2000), 537-561.
• Akira Shirai
• Sugiyama Jogakuen University, School of Education, Department of Child Development, 17-3 Hoshigaoka Motomachi, Chikusa, Nagoya, 464-8662, Japan
• Communicated by Mirosław Lachowicz.
• Revised: 2014-09-01.
• Accepted: 2014-09-04.
• Published online: 2015-04-27.
|
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|
https://www.redmine.org/boards/2/topics/5865?r=8408
|
## Redmine and Gmail
Hi all,
I've recently installed Redmine (using Bitnami Stack) and wanted to set it up using Gmail for outgoing email.
I've followed the steps in http://redmineblog.com/articles/setup-redmine-to-send-email-using-gmail about how to go about doing this.
But after installing the action_mailer_optional_tls_plugin I can't access the site and only get a 502 exception.
I managed to track the issue down in the Mongrel log file to the following error:
Mounting Rails at /redmine...C:/Program Files/BitNami Redmine Stack/ruby/lib/ruby/site_ruby/1.8/rubygems.rb:142:in activate': can't activate actionmailer (>= 0, runtime), already activated actionmailer-2.1.2 (Gem::Exception) from C:/Program Files/BitNami Redmine Stack/ruby/lib/ruby/site_ruby/1.8/rubygems.rb:49:in gem' from C:/Program Files/BitNami Redmine Stack/apps/redmine/vendor/plugins/action_mailer_optional_tls/lib/action_mailer_tls.rb:2 from C:/Program Files/BitNami Redmine Stack/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in gem_original_require' from C:/Program Files/BitNami Redmine Stack/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in require' from C:/Program Files/BitNami Redmine Stack/apps/redmine/vendor/rails/activesupport/lib/active_support/dependencies.rb:510:in require' from C:/Program Files/BitNami Redmine Stack/apps/redmine/vendor/rails/activesupport/lib/active_support/dependencies.rb:355:in new_constants_in' from C:/Program Files/BitNami Redmine Stack/apps/redmine/vendor/rails/activesupport/lib/active_support/dependencies.rb:510:in require' from C:/Program Files/BitNami Redmine Stack/apps/redmine/vendor/rails/activesupport/lib/active_support/dependencies.rb:102:in require_or_load' ... 27 levels... from C:/Program Files/BitNami Redmine Stack/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/../lib/mongrel/command.rb:212:in run' from C:/Program Files/BitNami Redmine Stack/ruby/lib/ruby/gems/1.8/gems/mongrel-1.1.5-x86-mswin32-60/bin/mongrel_rails:281 from C:/Program Files/BitNami Redmine Stack/ruby/bin/mongrel_rails:19:in load' from C:/Program Files/BitNami Redmine Stack/ruby/bin/mongrel_rails:19
If I remove the plugin then Redmine works fine again, anyone any idea about what the issue is? Is there another version of the actionmailer that's already installed by default?
Thanks,
Johan
### Replies (11)
#### RE: Redmine and Gmail - Added by Greg Dudaalmost 11 years ago
I am using the Bitnami stack as well, runnning Redmine 0.8.3 on OS X Leopard. I'm running into the exact same issue, and have been pulling my hair out. Did you find anything that works? I didn't use the
ruby script/plugin install git://github.com/collectiveidea/action_mailer_optional_tls.git
command to install the Action Mailer plug-in because bash complains it doesn't understand "git", so instead I used:
./script/plugin install http://svn.douglasfshearer.com/rails/plugins/action_mailer_optional_tls
but I believe it is the same Action Mailer plug in....
#### RE: Redmine and Gmail - Added by Johan Welgemoedalmost 11 years ago
yes that's the same Action Mailer plugin...and no haven't found anything yet, going back to using the local smtp server...
#### RE: Redmine and Gmail - Added by Hugh Flynnover 10 years ago
I was able to configure Redmine to use GMail (I am also running the Bitnami stack, version 0.8.4 on OS 10.5) by using the configuration described in step 2 of the redmineblog.com entry referenced in this post but also following these instructions for adding tls_smtp.rb to the /ruby/lib directory:
http://bug.gd/search/details/78026/redmine-rails-must-issue-a-starttls-command-first
The 0.8.4 stack already has the action_mailer_optional_tls_plugin included so I did not need to follow any of the other steps outlined in the blog post.
Hope this helps.
#### RE: Redmine and Gmail - Added by Basil Rormoseover 10 years ago
Hi
Complete newbie here as far ruby/rails/redmine goes.
I'm using the Bitnami Ruby stack with the redmine module on Windows 2008 server (64bit)
Can anyone give me any suggestions on how/where to install the 'tls_smtp' file and which environment.rb file to modify. Unfortunately the script commands to install the actionmailer plugin do not run.
Redmine runs great otherwise.
Many thanks
Basil
#### RE: Redmine and Gmail - Added by Hugh Flynnover 10 years ago
The environment.rb file is located in <your redmine directory>/apps/redmine/config/. Just put require 'tls_smtp' at the top near the other require statements (I put it below require File.join(File.dirname(__FILE__), 'boot' in my environment.rb file).
Copy tls_smtp.rb to <your redmine directory>/ruby/lib/
Hugh
#### RE: Redmine and Gmail - Added by Basil Rormoseover 10 years ago
Thanks Hugh.
I have tried the above many other variations based on postings on various forums & blog articles
in environment.rb, I have
1. Required for gmail use
require File.join(File.dirname(FILE), '../lib/tls_smtp')
In email.yml (no tabs, only spaces):
production:
delivery_method: :smtp
smtp_settings:
port: 587
domain: xxxx.gr
authentication: :plain
user_name:
tls: true
I have also tried 'authentication: :login'
There is no <your redmine directory>/ruby/lib/ directory. So I put the tls_smtp.rb file in redmine/lib directory.
Ruby version: 1.8.7
Rails version: 2.3.2
Redmine version: 0.8.4
Bitnami ruby stack + redmine module
Trying to send a test e-mail always gets me: An error occurred while sending mail (530 5.7.0 Must issue a STARTTLS command first. j10sm2362856mue.15 )
Was thinking of updating redmine from svn.
Obviously I'm missing something. Any ideas or suggestions would be appreciated.
Basil
#### RE: Redmine and Gmail - Added by Hugh Flynnover 10 years ago
Basil,
Note that require 'tls_smtp' goes below (or above, for that matter) the other line and is not a part of it:
# Bootstrap the Rails environment, frameworks, and default configuration
require File.join(File.dirname(__FILE__), 'boot')
require 'tls_smtp'
Also, you need follow the examples in step 2 of the Redmine Blog post more literally. Note, for example, that the domain in email.yml should be the mail server's domain (gmail, in this case) not your domain since the gmail domain is the one from which the e-mail will be originating and you should enclose the appropriate values with quotation marks (mine are mixed single and double quotes as in the example but one form or the other might work). This is what I have used successfully:
production:
delivery_method: :smtp
smtp_settings:
tls: true
port: '587'
domain: "smtp.gmail.com"
authentication: :plain
user_name: "[email protected]"
Hugh
#### RE: Redmine and Gmail - Added by Lars Fischerabout 10 years ago
Hello,
I tried to install the action_mailer_optional_tls plugin, but all I get is an empty folder.
Where can I get the needed files to make " require 'tls_smtp' " work?
Regards,
Lars
#### RE: Redmine and Gmail - Added by Rajeev Balmost 10 years ago
Hi,
Following the instructions at http://redmineblog.com/articles/setup-redmine-to-send-email-using-gmail/
I tried installing the action_mailer_optional_tls plugin I tried the following:
c:\path\to\redmine-0.9.3>ruby script\plugin install git://github.com/collectiveidea/action_mailer_optional_tls.git
this simply creates an empty folder:
C:\path\to\redmine-0.9.3\vendor\plugins\action_mailer_optional_tls
Then I also tried installing it from the svn url
c:\path\to\redmine-0.9.3>ruby script\plugin install --force http://svn.douglasf shearer.com/rails/plugins/action_mailer_optional_tls
ptional_tls"]
I don't know where else I could find this plugin and install it. Help needed
I am running redmine-0.9.3 on windows7 OS.
#### RE: Redmine and Gmail - Added by TEHEK Firefoxalmost 10 years ago
Hey guys,
It seems svn repo on svn.douglasfshrearer.com is no longer available. I tried to download from git, but it failed silently.
Later on I discovered that my server simply didn't have git installed. Since it's Ubuntu:
# sudo apt-get install git git-core
# ruby script/plugin install git://github.com/collectiveidea/action_mailer_optional_tls.git
Initialized empty Git repository in /var/www/redmine/vendor/plugins/action_mailer_optional_tls/.git/
remote: Counting objects: 14, done.
remote: Compressing objects: 100% (12/12), done.
remote: Total 14 (delta 2), reused 2 (delta 0)
Unpacking objects: 100% (14/14), done.
From git://github.com/collectiveidea/action_mailer_optional_tls
It's now working both with regular @gmail.com accounts and google apps.
#### RE: Redmine and Gmail - Added by Russell Kwokalmost 10 years ago
Just a reminder,
As what TEHEK said, I have found that the Centos does not have git as well, however, its default repository don't have git package, so you may need to following the link below to add the epel repository first:
http://www.hampson.ca/blog/2009/09/08/setup-git-centos-53-and-make-public-over-ssh/
after the epel repo is installed, then you can simply install the git by yum install git.
Cheers.
(1-11/11)
|
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https://notaboutapples.wordpress.com/tag/e/
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## 6 days to Tau Day
22 June 2011
Even now, a select group of mathematicians and mathophiles are counting down to what should (in my opinion) be one of the principal holidays on the mathematician’s calendar. You’ve all heard of Pi Day, some of you even celebrate it in one way or another (the number of my facebook friends signed up for “The Only Pi Day of Our Lives” surprised me), and it grieves me to say so, but it’s overrated. At best it should be a minor math holiday. If you celebrate only one circle-constant-related holiday in a year, it should be Tau Day. And if you use only one Greek letter as shorthand for a particular constant which is related to circles and mathematically ubiquitous, better that it be $\tau$, the circumference of a circle with unit radius (approximately 6.28318531, which is twice that other number).
Tau Day is 6/28 (by analogy with Pi Day Half Tau Day, 3/14), so our countdown stands at 6 days ($\lfloor \tau\rfloor$ days, if you will).
I won’t get into the details here, but the key contention is that τ, not π, is the circle constant we should focus on. Instead of $C = 2 \pi r$ (or $C=\pi d$), it would be better to write $C = \tau r$. For a quick and cute introduction, check out the Pi is Still Wrong video from everybody’s favorite mathemusician, Vi Hart. For the whole manifesto, check out Michael Hartl’s wonderful site (updated a few months ago for Pi Day Half Tau Day).
Especially for the non-mathematicians here, “should” and “better” might seem strange word choices. Today I want to focus on what exactly they might mean in this context.
(Remark: If you’re more science-minded, this is a little like the oft-heard-in-some-circles assertion that the convention for positive and negative charges is “backwards”, the opposite of what it “ought to be”. Apropos xkcd comic!)
## The Two Decks of Cards and the Drunken Hat Check Girl
3 August 2009
1. Imagine you have two decks of playing cards, each thoroughly shuffled. You give one deck to your friend and keep the other. Now each of you goes through your deck, one card at a time, flipping cards face up. You compare your top cards, then you compare your next cards, and so on all through the deck. If it ever happens that you both reveal the same card at the same time, you win; if you go through the whole deck without such a match, your friend wins. Who is more likely to win? You or your friend?
2. Thirty-seven men attend a certain social event and check their hats as they enter. However, the hat check girl has had a bit too much to drink, and when the time comes to leave, she gives back hats at random, with total disregard for which hat belongs to whom. What are the chances that nobody ends up with his own hat?
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http://physics.stackexchange.com/users/3227/aufwind
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# Aufwind
less info
reputation
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bio website location Germany age member for 3 years seen Mar 2 '12 at 23:10 profile views 4
# 2 Questions
3 Escape velocity of a rocket standing on Ganymede (Moon of Jupiter) 3 Do the trigonometric functions preserve units?
# 135 Reputation
+15 Escape velocity of a rocket standing on Ganymede (Moon of Jupiter) +15 Do the trigonometric functions preserve units?
This user has not answered any questions
# 7 Tags
0 homework × 2 0 si-units 0 gravity 0 experimental-physics 0 forces 0 astrophysics 0 units
# 28 Accounts
Stack Overflow 3,300 rep 62875 Ask Ubuntu 933 rep 21022 Mathematics 845 rep 619 TeX - LaTeX 285 rep 16 Skeptics 240 rep 37
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https://www.physicsforums.com/threads/hello-hi.820203/
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# Hello, hi
Tags:
1. Jun 22, 2015
### 0null
Hi, i am studying because i think it is fun! I might ask some astronomy and mathematics questions, but mostly physics!
2. Jun 22, 2015
### Borg
Welcome to Physics Forums Onull!
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https://socratic.org/questions/what-are-the-differences-between-geometric-isomers-and-optical-isomers
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Organic Chemistry
Topics
# What are the differences between geometric isomers and optical isomers?
Feb 5, 2017
Well..........
#### Explanation:
And see here for here a discussion on diastereoisomerism.
Just to review the levels of isomers, structural isomers are species with the same chemical formula but different connectivity. Geometric isomers have the SAME connectivity but different geometry. The best illustration of geometric isomerism occurs with cis and trans $\text{2-butylene}$. For both cis and trans isomers the CONNECTIVITY is definitely the same: i.e. $C 1$ connects to $C 2$.....connects to $C 4$. However, because of the geometry around the olefinic bond between $C 2$ and $C 3$, these isomers are distinct chemical species, with different chemical and physical properties.
Chirality, handedness, adds another level to isomerism. Enantiomers have EXACTLY the same connectivity, and geometry, however, one enantiomer is the mirror image of the other. Introduce a couple of so-called chiral centres into the molecule, and diastereomers can be generated, i.e. $\text{RS}$, and $\text{RR}$, which are diastereomeric in the respect that they are not MIRROR images.
If there is something I have ignored fire away.
##### Impact of this question
6490 views around the world
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