Search is not available for this dataset
query
stringlengths 1
13.4k
| pos
stringlengths 1
61k
| neg
stringlengths 1
63.9k
| query_lang
stringclasses 147
values | __index_level_0__
int64 0
3.11M
|
|---|---|---|---|---|
Solving a differential equation with a stochastic force term with NDSolve | How to reformulate differential equation problem as OrnsteinUhlenbeckProcess | Boundary condition with spatial derivative is ignored by NDSolve | eng_Latn | 18,800 |
Euler equation with single state variables | Calculate Euler equations of fluid dynamics without division? | Unitarily evolving a separable state into an entangled one | eng_Latn | 18,801 |
Solve this equation using Bernoulli's equation | Solving of a seperable differential equation | Intuitive Bernoulli numbers | eng_Latn | 18,802 |
Solving Stefan's solidification problem - moving boundary issue | How to solve a system of PDEs with zip condition? | (Why) Has Kohonen-style SOM fallen out of favor? | eng_Latn | 18,803 |
what is the definition of a traveling wave solution for a system of PDE? | u may find it in calculus or in mechanics of wave test book | I'm certainly no expert, but from my high school physics days I recall something about Bode's law. You might be able to Google or Wikipedia it. It was an explanation, in Newtonian physics terms, of why the planets are where they are. | eng_Latn | 18,804 |
What is the statement of Bernoulli's equation? | What is Bernoulli's equation? | What is the significance of the Hill equation? | eng_Latn | 18,805 |
a fast iterative method for solving the eikonal equation on triangulated surfaces . | Dynamic Programming and Optimal Control | Computational Study of Fast Methods for the Eikonal Equation | eng_Latn | 18,806 |
How can I solve the ODE $2y'' + ty' -2y=10, y(0) =y’(0)=0 $ by Laplace transform? | Laplace transform of integral constant | $4x^2+1$ factors only into $4y+1$ primes | eng_Latn | 18,807 |
How do you solve $\dot{X} = UX$? | Systems of linear differential equations - eigenvectors | Empty intersection and empty union | eng_Latn | 18,808 |
Solve the initial value problem: $\frac{dy}{dx} = e^{x+y}$, given $y(0)=0$. | Find the general solution of $y'= a^{x + y}$ where y is the function | Show discontinuity of $\frac{xy}{x^2+y^2}$ | eng_Latn | 18,809 |
Given a function of two variables, how can I define a 2nd function that is the integral of the 1st w.r.t. one of the variables? | Efficient evaluation of functions defined by NIntegrate | Derivative of function with 2 variables | eng_Latn | 18,810 |
Reducing degrees of freedom of a system described by an equation | Procedure for reducing the degrees of freedom of an arbitrary system | Procedure for reducing the degrees of freedom of an arbitrary system | eng_Latn | 18,811 |
Why DSolve and NDSolve give different answer? | Boundary condition with spatial derivative is ignored by NDSolve | Plotting solutions to NDSolve | eng_Latn | 18,812 |
How to calculate E^At for differential equations using mathematica | Can I solve system of differential equation in a matrix form? | Proof of linear independence of $e^{at}$ | eng_Latn | 18,813 |
Is there a way to derive the second linearly independent solution to ODE whose characteristic quadratic has double roots? | Where does $xe^x$ solution come from when the characteristic polynomial is square? | Sufficient conditions for $x, Ax, A^2x, ...$ being linearly indepedent | eng_Latn | 18,814 |
Dirac delta function and well behaved function | Dirac Delta or Dirac delta function? | Boundary condition with spatial derivative is ignored by NDSolve | eng_Latn | 18,815 |
3 x 3 linear system organization | $3\times3$ linear system organization | solving third-order nonlinear ordinary differential equation | eng_Latn | 18,816 |
Taking the second derivative of a parametric curve | Explanation behind Second Derivative of a Parametric Equation Formula | Taking the second derivative of a parametric curve | eng_Latn | 18,817 |
Unable to solve the expontial equations | Error/warning when using NSolve for simple equation | Prove that $\exp(x)>0$ using only formal definition of exp | eng_Latn | 18,818 |
Error Propagation: Why using derivatives instead of the function | Why is propagation of uncertainties quadratic rather than linear? | Integral of periodic function over the length of the period is the same everywhere | eng_Latn | 18,819 |
Prove the 2nd part of the Diophantien equation theorem: That if Xo, Yo is on solution, then every solution is of the from: X=Xo+(b/d)t; Y=Yo-(a/d)t for t is an integer.\n\nMaybe if you knew that the first part of the equation is: ax+by=d which I already proved. | First do this for d=gcd(a,b)=1. Subtracting the equations for the solutions (x_0,y_0) and (x,y), get that a(x-x_0)+b(y-y_0)=0. If gcd(a,b)=1, this shows that a divides y-y_0, i.e. y=y_0+at. Conclude that x=x_0+bt.\n\nNow see what happens if gcd(a,b)=1 and d is not 1. Then do the general case. | Integrate using the method of substitution based on the fact that the derivative of log(y) + C = 1/y\n\nlet u = log(y) then du/dy = 1/y. So du = (1/y) dy\n\nUsing these substitutions we have:\n\nInt 1/y*log(y) dy = Int 1/log(y)*(1/y) dy\n\n= Int 1/u du = log(u)+C = log(logy)+C, since u = log(y)\n\nThis is correct since from the chain rule:\n\n d/dy log(logy)+C= 1/log(y)*d(logy)/dy= 1/(y*logy) | eng_Latn | 18,820 |
or it can be rewritten as (y ln y)^-1 dy | Integrate using the method of substitution based on the fact that the derivative of log(y) + C = 1/y\n\nlet u = log(y) then du/dy = 1/y. So du = (1/y) dy\n\nUsing these substitutions we have:\n\nInt 1/y*log(y) dy = Int 1/log(y)*(1/y) dy\n\n= Int 1/u du = log(u)+C = log(logy)+C, since u = log(y)\n\nThis is correct since from the chain rule:\n\n d/dy log(logy)+C= 1/log(y)*d(logy)/dy= 1/(y*logy) | Well hey, you need help, ask the teacher! I know how to do this, with help from my nerdy Calculus BC friend, but it's really not that hard once you think about it... | eng_Latn | 18,821 |
wat if assume y =(x^xdx) differentiate ,tak logarithm and again differentiate to form a second degree differential equation..can that be solved? | Expressions such as yours is called a power tower. They are differentiable by writing them as exponentials but they are not integrable in closed form. You can find the series form at the source link however. | Yes.\nThe closure relation on a function space produces a dirac delta function and the dirac delta function can be expanded in any basis set, in particular in a complete orthonormal family. This can be used to solve PDEs by using eigenfunction expansions.\n\nFor example, the dirac delta function has a representation in the sine basis functions, a representation in the cosine basis functions and also a representation in the fourier series basis functions. | eng_Latn | 18,822 |
i.e e to the minus x squared... | This integral does not have an indefinite closed form of elementary functions. It can be evaluated numerically by either integrating the series representation of e^(-x^2) or using integral approximation methods like Simpson's rule.\nIt also has an interesting value if evaluated over its entire domain; by changing coordinates to polar coordinates, one can easily show that the integral over the entire real line is equivalent to Sqrt[Pi].\nThis fact is used in statistics to normalize the Gaussian distribution to have area 1 under the curve. The integral of your expression on the interval [0,t] is then known as the error function. See the source for details. | Joe, i'm sorry but i have no idea! i have some sites that may help, though!\n\nwikipedia.org\nwww.webmath.com\nmathforum.org/dr.math/\n\nthat is where i usually go for help. sorry i couldn't be any more helpful! and good luck | eng_Latn | 18,823 |
this the rest of the problem; mol of gas, what is the maximum temperature in degress celsius to which the vessel can be subjected? The answer is 143 degress celsius. Am i supposed to use the ideal gas las PV=nRT? If i do, how do i solve for T? | Given the answer you are trying to work towards, the ideal gas law is sufficient. But beware, in reality, the ideal gas law is accurate only at low pressures (not far from 1 atm). That said, it is a simple matter of algebra at this point:\n\n T=(P*V)/(n*R) with R=0.0821 L*atm*mol^-1*K^-1\nNote that your answer is in degrees Kelvin and the required value in celcius would be degrees Kelvin minus 273.15 | I think the velocity expression is meant to be in terms of t (rather than x)\nv(t) = ln(t+3) -cost*e^(t/2 -1).\n\nIf the particle VELOCITY is decreasing, it means that the time derivative of v(t), which is the acceleration, a(t), is negative. But if the particle SPEED is decreasing, it means that the acceleration is the opposite sign of the velocity. So if you really mean speed, you are looking for times when a(t)*v(t) < 0.\n\nThe derivatives are as follows\nd/dt(ln(t+3)) = 1/(t+3)\nd/dt(e^((t/2)-1)) = 1/2*e^((t/2)-1)\nd/dt(cos(t)) = -sin(t)\nso\na(t) = 1/(t+3) -cos(t)*1/2*e^((t/2)-1) + sin(t)*e^((t/2)-1)\n\nThen find t, such that a(t) < 0 (velocity decreasing)\nor a(t)*v(t) < 0 (speed decreasing).\n\nHope this helps!\n\n(Note if the velocity really is given in terms of x (rather than t) you will be solving a second order differential equation, which is doable, but I don't think that was the point of the question). | eng_Latn | 18,824 |
Maths help needed here;\n(1) Determine the derivative of the function. Then determine an equation of the tangent to the graph of 3xsquared -5 over4x-5 at x=0.\n\n\n3x^2-5/ 4x-5 at X=0 (kind of looks like that)\n \nplease help | Put in parenthesis... Which of these do you want?\n3x^2 - 5 / ( 4x-5)\n\n3x^2 - 5/(4x) -5\n\n3x^2 - (5/4) x - 5\n\n? | a) volume can be found by integration, i.e. to sum up very thin discs from y=0 to y=h.\nEach thin discs is of radius x and thickness delta_y.\nThus, volume of a disc is pi x^2 delta_y.\nsumming many of these volume with small thickness delta_y for different values of y from 0 to h is\nintegrate pi x^2 w.r.t. y from 0 to h, where x^2 = y/a.\n\nb) surface of water = area of the circle of radius x when y = h, i.e. pi (h/a), because x^2 = h/a in this case.\n\nc) Given dV/dt = -k pi h/a, where V is found in a. Thus, implicit differentiating dV/dt will have some terms of dh/dt, and so you'll get the differential equation.\n\nd) Solve for your differential equation for h in terms of t. Find the difference between values of t for h = h0 and h=0.\n\n\nps: by the way, the bowl is not rotating! | eng_Latn | 18,825 |
Use convolution operator to determine the integral representation of the solution of the initial-value problem:\n\n(d^2y/dt^2) + 3y = t (1 - u1(t)), y(0) = 2; y'(0) = 0\n\nIntegrate, if you can, to find the solution explicitly. | To solve this it's a pretty straightforward application of Laplace transforms. You can do this question using convolutions as follows:\n\nFirst take the laplace transfom of the ODE:\n\nlet L{y(t)}(s) = Y(s) be the laplace transform of y(t). Then we have:\ns^2(Y(s)) - 2s + 3Y(s) = 1/s^2 - (e^-s)/s\n\nrearranging we have Y(s) = (1/s^2 - e^-s/s + 2s) (1/(s^2+3)) = G(s) H(s) where G(s) = (1/s^2 - (e^-s)/s) and H(s) = (1/(s^2+3)) \n\nnow using the inverse laplace formula for the convolution of two functions:\n\ny(t) = L(^-1){Y(s)} = integral from 0 to t of (h(t-x)g(x)dx) + 2cos(sqrt(3)t)\n\n where h(t) = 1/sqrt(3) sin(sqrt(3)t) and g(t) = (t - u1(t))\n\nand the integral can be evaluated. \n\nSorry for the readability but I don't think yahoo answers can render math text properly. Also, as a note, this question would be far easier to solve using a partial fraction method rather than unecesarily using convolutions. | I think the velocity expression is meant to be in terms of t (rather than x)\nv(t) = ln(t+3) -cost*e^(t/2 -1).\n\nIf the particle VELOCITY is decreasing, it means that the time derivative of v(t), which is the acceleration, a(t), is negative. But if the particle SPEED is decreasing, it means that the acceleration is the opposite sign of the velocity. So if you really mean speed, you are looking for times when a(t)*v(t) < 0.\n\nThe derivatives are as follows\nd/dt(ln(t+3)) = 1/(t+3)\nd/dt(e^((t/2)-1)) = 1/2*e^((t/2)-1)\nd/dt(cos(t)) = -sin(t)\nso\na(t) = 1/(t+3) -cos(t)*1/2*e^((t/2)-1) + sin(t)*e^((t/2)-1)\n\nThen find t, such that a(t) < 0 (velocity decreasing)\nor a(t)*v(t) < 0 (speed decreasing).\n\nHope this helps!\n\n(Note if the velocity really is given in terms of x (rather than t) you will be solving a second order differential equation, which is doable, but I don't think that was the point of the question). | eng_Latn | 18,826 |
A block of mass (13 kg) starts from rest and slides a distance of 9 metersdown an inclined plane making an angle of 40 degrees with the horizontal. The coefficient of sliding friction between the block and plane is 0.4. The acceleration of gravity is 9.8 m/s.\nWhat is the net force on the block along the incline? | 130sin40 is the normal force\n\n0.4 x 130sin40 = friction\n\nForces = ma\n\nForces = 13 x 9.8 = 130 (rounded) | I think the velocity expression is meant to be in terms of t (rather than x)\nv(t) = ln(t+3) -cost*e^(t/2 -1).\n\nIf the particle VELOCITY is decreasing, it means that the time derivative of v(t), which is the acceleration, a(t), is negative. But if the particle SPEED is decreasing, it means that the acceleration is the opposite sign of the velocity. So if you really mean speed, you are looking for times when a(t)*v(t) < 0.\n\nThe derivatives are as follows\nd/dt(ln(t+3)) = 1/(t+3)\nd/dt(e^((t/2)-1)) = 1/2*e^((t/2)-1)\nd/dt(cos(t)) = -sin(t)\nso\na(t) = 1/(t+3) -cos(t)*1/2*e^((t/2)-1) + sin(t)*e^((t/2)-1)\n\nThen find t, such that a(t) < 0 (velocity decreasing)\nor a(t)*v(t) < 0 (speed decreasing).\n\nHope this helps!\n\n(Note if the velocity really is given in terms of x (rather than t) you will be solving a second order differential equation, which is doable, but I don't think that was the point of the question). | eng_Latn | 18,827 |
hello! I was a fool this week and decided to skip class so I could study for my exams... one of which I have tomorrow! This assignment is due tomorrow morning, I haven't a clue what it's about because I missed this week's two lectures. Any help would be greatly appreciated!\nhttp://www.colorado.edu/chemistry/chem1111/Challenge2/CCCQ11_Nov10.pdf\n(The problems are on the 2nd page) | Hey, Blond fuss? Good luck if U can't find help @ this late hour. Keep working on it. Something from what U learned so far must b in your head - find it. No one else working on this problem awake?\n I'm tired (12:35 a.m. here @ UMAss Amherst). Had 1st-yr Chem 100 in 1978, not Chem 1111 !! Barely remember orbitals. U do have books there, don't U? Library maybe not open now as ours is. \n Aces 2 computer. So U have awhile 2 figure it out. Good luck. | Use the fact that PV/T = a constant, we find the constant by pluging in the values we have, T = 20C, but we must convert that to K first so 20C = (273 + 20) = 293K. And 1 atm should be converted to physicall units of Nt/m^2 for an easier solution. 1 Atm = 101325 Nt/m^2. So our constant is (101325)(4.5)/293 = 1.336 x 10^7 so now you have one equation as\n\nPV/T = 1.336 x 10^7 setting T = 260C or 533K gives\n1) PV = 7.121 x 10^10\n\nThe next equation that we need is the force on the cylinder end given the pressure, which would be\n\n2) .01P = F\n\nThe spring will stretch a distance 3) d = F / (2.00 x 10^3) \n\nThe volume changes by 4) V = 4.5 + d * .010 \n\nThis gives you 4 equations which you can now solve to find the solution for V, d, P and F | eng_Latn | 18,828 |
Please, exact time in years. (and days if you can) | The US has been over there off & on since the first World War. Lately, we've been over there since 9-11 happened back in 01. | To solve this it's a pretty straightforward application of Laplace transforms. You can do this question using convolutions as follows:\n\nFirst take the laplace transfom of the ODE:\n\nlet L{y(t)}(s) = Y(s) be the laplace transform of y(t). Then we have:\ns^2(Y(s)) - 2s + 3Y(s) = 1/s^2 - (e^-s)/s\n\nrearranging we have Y(s) = (1/s^2 - e^-s/s + 2s) (1/(s^2+3)) = G(s) H(s) where G(s) = (1/s^2 - (e^-s)/s) and H(s) = (1/(s^2+3)) \n\nnow using the inverse laplace formula for the convolution of two functions:\n\ny(t) = L(^-1){Y(s)} = integral from 0 to t of (h(t-x)g(x)dx) + 2cos(sqrt(3)t)\n\n where h(t) = 1/sqrt(3) sin(sqrt(3)t) and g(t) = (t - u1(t))\n\nand the integral can be evaluated. \n\nSorry for the readability but I don't think yahoo answers can render math text properly. Also, as a note, this question would be far easier to solve using a partial fraction method rather than unecesarily using convolutions. | eng_Latn | 18,829 |
A body oscillates with simple harmonic motion according to the equation:\n\nx = (6.0 m) cos [ ( 3 pi rad/s )t + pi/3 rad ]\n\nAt t = 2.0 s, what are (a) the displacement, (b) the velocity, (c) the acceleration, and (d) the phase of the motion?\n\nAlso, what are (e) the frequency and (f) the period of the motion?\n\nWhat equations did you use? Can you explain your answers? | Have you been given the standard formulas?\nx = a cos (nt + c), frequency = n, period = 2*pi/n, phase = c (Not sure of that -- it may be -c. Look it up.) This gives you the answers to (d), (e) and (f) immediately. [No, I'm not doing it for you: You can substitute values I'm sure.]\n\nx is the displacement, so just sub t = 2 in this equation. If you need touse your calculator (you shouldn't!), make sure it's set in radians.\n\nVelocity is dx/dt. You can do that I hope, and get\n\nv = - 18*pi*sin(3*pi*t + pi/3) Notice I omit units. I prefer to use equations relating to numbers only (though I know units are sometimes useful especially in a Physics context) and then state the correct units in presenting the answer -- which you are going to do!\nSub t = 2 to get v in m/s\n\nAcceleration is dv/dt, so differentiate and then sub t = 2\n\nAll the best | If a molecule of the water is moving at 2m/s through the hose, it is because of the nozzle, not despite it. That molecule travels through the nozzle at 2m/s. | eng_Latn | 18,830 |
A solid cylindrical disk has a radius of 0.16 m. It is mounted to an axle that is perpendicular to the circular end of the disk at its center. When a 40 N force is applied tangentially to the disk, perpendicular to the radius, the disk acquires an angular acceleration of 90 rad/s2. What is the mass of the disk? | The moment of inertia of a solid cylinder is 1/2 mr ^2..\nTorque is the product of moment of inertia and angular acceleration. It can also be expressed as the product of the force applied to the edge of the disk and the radius. Set the two products equal to each other and solve for m.\n\nT = I α = r F\n\n1/2 m r ^2 α = r F\n\nm = (r F) / (1/2 r ^2 α) = 2 F / r α\nm = 2 (40) / 0.16 (90)\n\nm = 5.56 kg | Have you been given the standard formulas?\nx = a cos (nt + c), frequency = n, period = 2*pi/n, phase = c (Not sure of that -- it may be -c. Look it up.) This gives you the answers to (d), (e) and (f) immediately. [No, I'm not doing it for you: You can substitute values I'm sure.]\n\nx is the displacement, so just sub t = 2 in this equation. If you need touse your calculator (you shouldn't!), make sure it's set in radians.\n\nVelocity is dx/dt. You can do that I hope, and get\n\nv = - 18*pi*sin(3*pi*t + pi/3) Notice I omit units. I prefer to use equations relating to numbers only (though I know units are sometimes useful especially in a Physics context) and then state the correct units in presenting the answer -- which you are going to do!\nSub t = 2 to get v in m/s\n\nAcceleration is dv/dt, so differentiate and then sub t = 2\n\nAll the best | eng_Latn | 18,831 |
What is the laplace transformation of...........? | Transform each term:\ny" => s^2*Y(s) - s*x(0) - x'(0)\ny' => s*Y(s) - x(0)\ny => Y(s)\ne(2x) => 5/(s-2) \nThen substitute back into the equation and that is the transform. To solve the equation, you collect terms and get an expression in terms of Y(s). This is the transform of y(x).\n\nThe algebra will undoubtedly involve a partial fractions expansion.\n\nIn any event the solution will look something like\n\ny(x) = A*e(-3x) + B*e(-2x) + C*e(2x) with A, B, C depending on any Initial conditions. | they're just time-consuming. it's the lectures that are difficult, not the labs. the labs don't really teach you a whole lot, they just kind of enforce what you were taught in lecture. | eng_Latn | 18,832 |
You are at a distance D of a wall. You approach the wall by D/2, you are at D1. Then again approach by D1/2 ,. | Interesting question and one asked in various forms for several centuries. The answer, of course, is "yes" because the logic in the way the question is framed is specious. The act of traveling does not divide into discrete units but is an on-going process tht will eventually terminate at the wall | Yes.\nThe closure relation on a function space produces a dirac delta function and the dirac delta function can be expanded in any basis set, in particular in a complete orthonormal family. This can be used to solve PDEs by using eigenfunction expansions.\n\nFor example, the dirac delta function has a representation in the sine basis functions, a representation in the cosine basis functions and also a representation in the fourier series basis functions. | eng_Latn | 18,833 |
A Comparison of Automatic Differentiation and Continuous Sensitivity Analysis for Derivatives of Differential Equation Solutions | FATODE: A Library for Forward, Adjoint, and Tangent Linear Integration of ODEs | Neu-Laxova syndrome: A terrible phenotypic appearance caused by an undefined genetic alteration | eng_Latn | 18,834 |
How do I solve differential equations easily? | How do I solve differential equations? | How can I solve the differential equation [math]x^2dy-y^2dx-xy^2(x-y)dy = 0[/math] ? | eng_Latn | 18,835 |
How to solve $\dot x(t) = x(2t)$ | What function satisfies $F'(x) = F(2x)$? | iPhone Apps section not showing up in iTunes | eng_Latn | 18,836 |
different modes to typest systems of equations | Systems of equations with a single number | Unable to solve equation for a variable by any method | eng_Latn | 18,837 |
Solve Exact Differential Equations | Exact differential equations are a subset of first-order ordinary differential equations. An equation of the form P ( x , y ) d x + Q ( x , y ) d y = 0 {\displaystyle P(x,y){\mathrm {d} }x+Q(x,y){\mathrm {d} }y=0} is considered to be exact if the following condition holds. | Google Maps support searching for and identifying a location by using its latitude and longitude coordinates. This gives you a more specific and exact location on the map. | eng_Latn | 18,838 |
Saving DSolve results | Assign the results from a Solve to variable(s) | Accessing Reduce from DSolve | eng_Latn | 18,839 |
How can I access numerical values of variables calculated with Solve? | What are the most common pitfalls awaiting new users? | Unable to solve equation for a variable by any method | eng_Latn | 18,840 |
Manipulate freezing on large calculations | Plotting heat equation in a Manipulate expression | Simple problem with Manipulate and Plot | eng_Latn | 18,841 |
Changing variables to obtain derivatives of new variables | Analogue for Maple's dchange - change of variables in differential expressions | Unable to solve equation for a variable by any method | eng_Latn | 18,842 |
Calculate the Laplace Transform of the Natural Logarithm | The Laplace transform is an integral transform widely used to solve differential equations with constant coefficients. The transforms are typically very straightforward, but there are functions whose Laplace transforms cannot easily be found using elementary methods. | The LaPerm cat descended from the American Shorthair: the first one was born in 1982. It has a mutation called the Rex gene which gives it a curly coat. | eng_Latn | 18,843 |
find the domain rational expression x+1 over x^2-9? | Division by zero is not allowed.\nSet the denominator equal to zero and solve for x.\nx^2 - 9 = 0\ngives x = -3 and x = 3.\nThus, the domain is\nAll real numbers except -3 and 3. | Yes.\nThe closure relation on a function space produces a dirac delta function and the dirac delta function can be expanded in any basis set, in particular in a complete orthonormal family. This can be used to solve PDEs by using eigenfunction expansions.\n\nFor example, the dirac delta function has a representation in the sine basis functions, a representation in the cosine basis functions and also a representation in the fourier series basis functions. | eng_Latn | 18,844 |
If a student is a senior and moves out of his current school district does he now have to pay tution? | Usually, the school district will want the students to start attending the other district you moved into. To avoid this, you can always get a Post office box (in the old district) and use that as your permanent address/mailing address. Start driving the kids to school if you want to keep them in the same district.\n\nAt the beginning of the year, my husband and I were staying with my parents for a couple months until our house was available to move into. Because of that, we were in a different school district but we still drove our daughter to school every morning (15 minutes away) so she wouldn't have to change schools or miss any school. We moved back into the district but to avoid any problems, we kept a mailing address in the old district even while we were gone. | Hello. Free-ed.net has a number of "free" college courses. I've explored the site, and I can't seem to find any catch to it...Free really seems to mean free in this case.\n\nThe trig class seems fairly thorough http://www.waybuilder.net/free-ed/Math/Trigonometry/trig02_SPK.asp\n\nThe calculus course is even cooler...a neat, video-based class\n\nhttp://www.waybuilder.net/free-ed/Math/Calculus/Calc01_NROC.asp\n\nI also once used the book "Forgotten Calculus" which is written exactly for the type of situation that you are speaking of.\n\nYou can pick up a used copy for $1 at half.com\n\nhttp://product.half.ebay.com/Forgotten-Calculus_W0QQprZ887877QQtgZinfo\n\nHope this helps!\n\nJason | eng_Latn | 18,845 |
the price of a certain commodity in dollars/units at time t is given by p=8+4e^-2t+te^-2t? | The average value of a function is given by\n\n(1/(b-a)) S f(x) dx, evaluated from a to b.\n\nSo for this question, the average will be given by\n\n(1/(4-0)) S 8+4e^-2t+te^-2t dt = (1/4)[8t - 2e^(-2t) + S te^-2t dt]\n\nLet u = e^(-t)\ndu = -e^(-t) dt\n\nSo, S te^-2t dt = - S u^2 du\n= (-u^3)/3\n= -e^(-3t)/3\n\nSo your answer then becomes\n\n(1/4)[8t - 2e^(-2t) - e^(-3t)/3] = 2t - (1/2)e^(-2t) - e^(-3t)/12\n\nEvaluating from 0 to 4,\n= 2(4) - (1/2)e^(-2(4)) - e^(-3(4))/12 - [2(0) - (1/2)e^(-2(0)) - e^(-3(0))/12]\n= 8 - (1/2)e^(-8) - e^(-12)/12 + 1/2 + 1/12\n= 8 5/12 - (1/2)e^(-8) - e^(-12)/12\n~ $8.42 | RS-274X is a superset of the EIA Standard RS-274D format. RS-274X supports some of the parameter data codes (G codes) and aperture codes (D codes) contained in RS-274D, as well as codes referred to as mass parameters. Mass parameters are plot parameters that define characteristics that can affect an entire plot, or only specific parts of the plot, called layers. Mass parameters extend the capabilities of Gerber Format. Their presence makes the Gerber data X data. | eng_Latn | 18,846 |
suppose the integral of..? | If ∫f(x)dx = y(x), then f(x) = d y(x) / dx; So to get the answer, take the derivative of the expression x^2 - 2x + 1. The value of the integral at limit 1 is a constant and will not appear in the derivative. | Wouldnt that just be Work=Work\n=> m x g x h = m x (lambda)\n=> gh=(lam) ? | eng_Latn | 18,847 |
what is the derivative of" r*x*cosx + r Ln r sinx " with respect to x as a variable? | (r*x)*(-sin(x))+(cos(x))*(r)+\n(0)*(lnrsin(x))+(r)*(cot(x)) \n\nfor the cot(x) you end up for the derivative of lnrsin(x) is (1/sin(x)) *cos(x)=cot(x)\n\nsorry it cut off on the top. hopefully this works | This is a very good question. What worked for me was playing loud, heavy metal music that kept me awake during much of calculus and at least 30% of linear algebra. It didn't work for differntial equations, however, but regular detonation of grenades, strategically spaced outside the classroom, worked pretty well for that class. | eng_Latn | 18,848 |
F^1(x) = (lim h->0) \nf(x+h)-f(x)\n-----------\n h\n\ncalculate f^1 where f(x)= x^2-3x+1 | lim h->0 (f(x+h)-f(x))/h\n\n[(x+h)^2-3(x+h)+1-(x^2-3x+1)]/h\n=(x^2+2xh+h^2-3x-3h+1\n -x^2+3x-1)/h\n=(2xh+h^2-3h)/h\n=(2x+h-3)\n\nThere should be a limit as h->0 in front of each line above, so let h=0 in the final line to give you 2x-3.\n\nThis is called a derivative by the way, and if you haven't learned them yet there are easy rules to follow for computing the derivative of polynomials like this one. | dP=[ aP^2 - bP ] dt\n\nintegrate from the initial point t0 to ant time t\n\nP=[ a/3 P^3 - b/2 P^2] {0 t}\nsubs B= aP^2 D=bP\nP=[1/3 * B * P - 1/2 D * P] {0 t}\n\nP - P0 = 1/3 * (B-B0)* (P-P0) - 1/2 (D-D0) * (P-P0)\n\ndivide by (P-P0)\n\n1 = 1/3 (B-B0) - 1/2 (D-D0)\n6 = 2B - 2B0 -3D + 3D0\n6 + 2B0 -3D0 = 2aP^2- 3bP\n\nM= 2*(3bP)*P/3*(2aP^2)=6b/^a= b/a\n\nThe RHS : D0P0/B0= (bP0*P0)/(aP0^2)= b/a\n\ntherefore M= RHS | eng_Latn | 18,849 |
how do you integrage 1/x^2 or 1/x^3 . \n\nAlso How would you solve for partial integrals? because there are partial integrals as well as there are partial derivatives right?\n\nwould anybody refer me to a basic webpage for integrals? I'm not talking about any of the other methods like substitution or integration by parts, just regular basic integration like for the equation above, I know basic integration but forgot what to do in some cases. | 1/x^2 = x^(-2)\nThe antiderivative is x^(-2+1)/(-2+1) + C\n= x^(-1)/-1 + C\n= -1/x + C\nIt is similar for 1/x^3\nYou do partial integrals the same way you do regular integrals. You need to know which one you are integrating with respect to and then pretend the other variable(s) are constants. | I do not know of a site that has complete instructions on how to build a catapult, but you should be able to most of what you need from the site below: | eng_Latn | 18,850 |
please help, im lost. \n\ni tried the multiplicity rule and ended up with (x)(ex)(e^(ex-1)) + (e^(ex))(1) for the 1st derivative, which i think is wrong. | I assume that the last ex you wrote is e^x too, right?\ny' = e^(e^x) + x [e^(e^x)] (e^x)\ny' = e^(e^x) [1+ x e^x]\n\nY''= e^(e^x)[ xe^x + e^x] + e^(e^x) e^x [1 + xe^x]\ny''= e^(e^x)[ xe^x + e^x + 1 + xe^x] | Expressions such as yours is called a power tower. They are differentiable by writing them as exponentials but they are not integrable in closed form. You can find the series form at the source link however. | eng_Latn | 18,851 |
d/dx [Si(x^2)]\n\nPlease tell me how to find this step by step | Si? Are you referring to the sine integral? If so, you need only remember two things:\nDifferentiation is the inverse of integration\nd/dx f(g(x)) = f'(g(x)) * g'(x)\n\nSo:\n\nd/dx (Si(x²)) = sin (x²)/(x²) * 2x | Well hey, you need help, ask the teacher! I know how to do this, with help from my nerdy Calculus BC friend, but it's really not that hard once you think about it... | eng_Latn | 18,852 |
How can i tell what the inside and outside functions are when using the chain rule to take derivatives? | Think about your order of operations. If you were evaluting the function for some number, what would you do first? That function is your *inside* function. | try sosmath.com they helped me before. if they don't have the answer you are looking for they have a list of links to tons of other math sites. \n\nand there probably is someone on your campus that can help as well. One on one help is always best...\n\nGood luck! | eng_Latn | 18,853 |
is there an equation ??? | I haven't worked with this in a long time and I'm not sure this will work, but try starting w/ this:\n1) Define an equation that describes the " ∞ " with polar coordinates (something like r = C1 - C2*theta);\n2) If L is lengh, delta.L = delta.theta / (2 pi) * r\nand dL = r/(2 pi) dtheta ;\n3) substitute for r and integrate from 0 to 2pi (or the necessary for one complete " ∞ ".\n \nProbably you'll find more than one mistakes here, but I think the general idea is correct. | Draw diagrams and put a fresh battery in your calculator. | eng_Latn | 18,854 |
A. (-∞, -2) U (4, ∞) \nB. (-∞, -4) U (2, ∞) \nC. (-2, 4) \nD. No solutions | x^2-2x-8 is factored as (x-4)(x+2).\n\nSo that means that +4 and -2 are your boundary points. \n\nWithout checking specific points it looks like your answer would be A, but you have to check points in each of the intervals. \n\nIf you pick -10 for x, (-10)^2 - 2(-10) - 8 > 0\n100 + 20 - 8 > 0\n112 > 0 True so that means that the interval from negative infinity to -2 works.\n\nIf you pick 0 for x, (0)^2 - 2(0) -8 >0\n0 - 0 - 8 > 0\n-8 > 0 False\n\nIf you pick +10 for x, (+10)^2 - 2(+10) - 8 > 0\n100 - 20 - 8 > 0\n72 > 0 True so that means the interval from 4 to positive infinity works.\n\nSo after all that work and checking answer A seems to be the correct one.\n\nHope this helps. Good Luck. :) | First put the first equation into slope-intercept form or:\n\ny = mx +b\n\nm = slope, and b = y-intercept\n\n-3x -3y = 2\n+3x +3x\n\n-3y = 3x + 2\n/-3 /-3\n\ny = -x + 2/3\n\nSo, your slope for the first equation is:\n\nm = -1\n\nTo have a line parallel to the first line, the slopes must equal.\n\n\n\nUse Point-Slope form.\n\ny - y1 = m ( x - x1)\n\nSince you are using the point (-3, -4)\n\ny1 = -4\n\nx1 = -3\n\nSo your new equation will be:\n\ny - -4 = -1 ( x - -3)\n\n(remember the slope must be the same)\n(a minus a negative = a positive)\ny + 4 = -1(x + 3)\n\ny +4 = -x -3\n -4 -4\n\ny = -x -7\n\nor you can put it back into standard form ( Ax + By = C)\n\nx + y = -7 | krc_Cyrl | 18,855 |
system of inqualities? | x + y = 2- - - - - - -Equation 1\ny - x = 2- - - - - - -Equation 2\n- - - - - - - -\n\nRearrange equation 2 to read\n\n-x + y = 2\n\n- - - - - - - -\n\nx + y = 2\n-x + y = 2\n- - - - - - - -\n\n2y = 4\n\n2y/2 = 4/2\n\ny = 2\n\nThe answer is y = 2\n\nInsert the y value into equation \n\n- - - - - - - - - - - - - - - - - - - - - \n\nx + y = 2\n\nx + 2 = 2\n\nx + 2 - 2 = 2 - 2\n\nx = 0\n\nThe answer is x = 0\n\nInsert the x value into equation 1\n\n- - - - - - - - - - - - - - - - - - - - - -\n\nCheck for equation 1\n\nx + y = 2\n\n0 + 2 = 2\n\n2 = 2\n\n- - - - - - - - -\n\nCheck for equation 2\n\ny - x = 2\n\n2 - 0 = 2\n\n2 = 2\n- - - - - - -\n\nThe solution set is { 0 , 2 }\n\n- - - - - - - -s- | What do you mean by the outlet temperature not being uniform. Do you mean not the same over time? Or are there multiple outlets and the temperature from each outlet is not the same?\n\nIf the inlet and outlet channels or headers are not designed carefully to allow for good fluid dynamics then there can certainly be portions of the exchanger that is not getting the same flow as other portions.\n\nWithout more information, I can not see how an energy balance will help solve the problem. | eng_Latn | 18,856 |
Help with Calculus problem please ! ? | I assume that's suppose to be an integral symbol.\n\nf(x) = [1/2 t²] from 2 to x, or 1/2 x² - 1\n\nThen f'(x) = x, and f''(x) = 1.\n\nDidn't really need to do the integration... | Just think about your Birthday party. f(x)= u and the value is ur guests. | eng_Latn | 18,857 |
For what do we use simultaneous equations for? | Why are simultaneous equations used? | Why we use a constant in integration? | eng_Latn | 18,858 |
what is finite math with applications | Finite Mathematics. an area of mathematics that studies the properties of structures of a finite nature that arise in mathematics and its applications. Such finite structures may include, for example, finite groups, finite graphs, and certain mathematical models of information converters, finite automata, Turing machines, and so forth. | Understand what the finite difference method is and how to use it to solve problems. What is the finite difference method? The finite difference method is used to solve ordinary differential equations that have. conditions imposed on the boundary rather than at the initial point. These problems are. called boundary-value problems. In this chapter, we solve second-order ordinary differential. equations of the form. f x y y a x b. dx. | eng_Latn | 18,859 |
define initial value in math | So we have an infinite number of solutions. An initial value problem is then a differential equation (ordinary or partial, or even a system) which, besides of stating the relation among the derivatives, also, by giving the initial conditions, specifies the values of the unknowns at some point. | So, in other words, initial conditions are values of the solution and/or its derivative(s) at specific points. As we will see eventually, solutions to ânice enoughâ differential equations are unique and hence only one solution will meet the given conditions. | eng_Latn | 18,860 |
what is the secant method | Secant Method Another Recursive Method Secant Method The secant method is a recursive method used to find the solution to an equation like Newtonâs Method. The idea for it is to follow the secant line to its x-intercept and use that as an approximation for the root.his is like Newtonâs Method (which follows the tangent line) but it requires two initial guesses for the root. The big advantage of the secant method over Newtonâs Method is that it does not require the given function f(x) to be a differential function or for the algorithm to have to compute a derivative. | As h approaches 0, the slope of the secant line approaches the slope of the line tangent to f(x) at x=a. The values a, b and/or h can be changed by simply typing a new value, such as 1.2345, pi/2, sqrt(5)+cos(3), etc. | eng_Latn | 18,861 |
how to calculate delta excel | Delta is different for call and put options. The formulas for delta are relatively simple and so is the calculation in Excel. I calculate call delta in cell V44, continuing in the example from the first part, where I have already calculated the two individual terms in cells M44 and S44: =M44*S44.The calculation of put delta is almost the same, using the same cells.amma in Excel. The formula for gamma is the same for calls and puts. It is slightly more complicated than the delta formulas above: Notice especially the second part of the formula: You will find this term in the calculation of theta and vega too. | 1 Find a value of epsilon for which there is no positive value of delta that works. ( 2 Epsilon needs to be small enough that the right hand limit and left hand limit are more than 2 epsilon apart.). 3 Use the applet to explore the function y = sin(1/x).4 Explain why the function has no limit as x approaches 0. Find a value of epsilon for which there is no positive value of delta that works. ( 2 Epsilon needs to be small enough that the right hand limit and left hand limit are more than 2 epsilon apart.). 3 Use the applet to explore the function y = sin(1/x). | eng_Latn | 18,862 |
How is the following differential equation solved? | How are second order nonlinear ordinary differential equations solved? | Prove $x^3 + 3 =4y(y+1)$ has no integer solutions | eng_Latn | 18,863 |
How to define the result of Solve as the variable | Assign the results from a Solve to variable(s) | Unable to solve equation for a variable by any method | eng_Latn | 18,864 |
Solution of Single Linear equation | How to find solutions of linear Diophantine ax + by = c? | Unable to solve equation for a variable by any method | eng_Latn | 18,865 |
Solving homogenous recurrence relation | Solving recurrence relation. Recurrence | (Why) Has Kohonen-style SOM fallen out of favor? | eng_Latn | 18,866 |
Two step method or two steps method | Pluralization rule for "five-year-old children", "20 pound note", "10 mile run" | Unable to solve equation for a variable by any method | eng_Latn | 18,867 |
how to pass a value to a variable that in a other variable | How to read value of variable, where the name of variable is the value of another variable | Unable to solve equation for a variable by any method | eng_Latn | 18,868 |
Align horizontally side by side equations | Numbering a set of horizontally distributed equations | When does a .com domain become available after it expires? (With status clientTransferProhibited) | eng_Latn | 18,869 |
which is solution to the wave equation | Since the wave equation is a linear second order PDE, given any two twice-differentiable. functions of a single variable (call them f1 and f2), the most general solution is. u(x, t) = f1(x + vt) + f2(x â vt). | The general solution to a differential equation must satisfy both the homogeneous and non-homogeneous equations. It is the nature of the homogeneous solution that the equation gives a zero value. | eng_Latn | 18,870 |
Impact of predation by greater flamingos Phoenicopterus ruber on the meiofauna, microflora, and sediment properties of two southern African lagoons | Flock distributions of Lesser Flamingos Phoeniconaias minor as potential responses to food abundance-predation risk trade-offs at Kamfers Dam, South Africa | High-affinity glucose uptake in Saccharomyces cerevisiae is not dependent on the presence of glucose-phosphorylating enzymes | eng_Latn | 18,871 |
Comparative physiological studies on the growth of cryptic species of Bostrychia intricata (Rhodomelaceae, Rhodophyta) in various salinity and temperature conditions | Cryptic diversity of the mangrove-associated alga Bostrychia (Rhodomelaceae, Rhodophyta) from Thailand | Cryptic diversity of the mangrove-associated alga Bostrychia (Rhodomelaceae, Rhodophyta) from Thailand | eng_Latn | 18,872 |
Occurrence and Activity of Slime Nets, Labyrinthula sp. Among Aquatic Plants in Cold and Oligohaline Baltic Sea Waters | Utilisation of seaweed carbon by three surface-associated heterotrophic protists, Stereomyxa ramosa, Nitzschia alba and Labyrinthula sp. | That's my story, and I'm sticking to it—an update on B. burgdorferi adhesins | eng_Latn | 18,873 |
Planktonic diatoms of the Zuari estuary, Goa (West coast of India) | Environmental characteristics of the Mandovi-Zuari estuarine system in Goa | Fungi isolated from the EEZ of Indian coast | eng_Latn | 18,874 |
Seasonal bryophyte productivity in the sub-Arctic: a comparison with vascular plants | Moss Functioning in Different Taiga Ecosystems in Interior Alaska I . Seasonal , Phenotypic , and Drought Effects on Photosynthesis and Response Patterns | Recent Literature on Bryophytes — 123(1) | eng_Latn | 18,875 |
Foliar epicuticular wax composition of mangrove species with natural distributions in West Africa and the Atlantic coast of South America, was studied by GC in order to investigate possible biogeographic variation. South American (Guyana) populations of Avicennia germinans were very much poorer in triterpenoids and in C 32 alkane and richer in C 28 alkane than populations from West Africa (Gabon). Shrub forms of A. germinans were richer in triterpenoids than trees. Dwarf forms of Conocarpus erectus were much poorer in triterpenoids, than shrub forms of this species. The pattern of alkane composition in Rhizophora from Guyana was unimodal, with unusually high amounts of C 28 , contrasting with a bimodal pattern, with modes at C 28 -C 29 and C 31 , in Rhizophora from Gabon. Foliar wax of Laguncularia racemosa from Guyana contained only trace amounts of triterpenoids and a broad range of alkanes with modes at C 29 and C 33 , whereas triterpenoids were present in significant amounts and most of the alkane fraction consisted of C 27 - C 29 in Gabon. These preliminary data suggest significant biogeographic variation within these taxa. | Mangroves belong to those ecosystems that are presently in danger of being extinguished or at best overexploited over most of their distribution range. They are used a.o. as sources of timber of wood for paper and pulp production or for coastal aquaculture. To fully assess their intrinsic value and to maintain their role in coastal protection as well as their high and at some taxonomic levels still largely unknown biodiversity it appears to be useful to look into other potential uses of mangroves. One of these might lie in the fact that they have been used traditionally as sources of non-wood forest products, food and pharmacological agents. In this presentation we combine ethnobotanical and ethnopharmacological aspects of New Guinean mangroves with information on the natural products chemistry of the same species. So far limited attempts have been made to chemically characterise mangroves in New Guinea. Hence most of the chemical data will be taken from other areas. | A minimal system of generators of the algebra of the centro-affine covariants for homogeneous planar cubic differential systems with linear part is known. With the help of the Gurevich theorem avoiding the Aronhold's identities based on the calculation of determinants, we describe the algebra of the centro-affne covariants for homogeneous planar cubic differential systems with free terms. | eng_Latn | 18,876 |
SUMMARY: The microcyst stage of Salmonella typhi, Proteus vulgaris, Bacterium coli and Pseudomonas fluorescens is non-motile and devoid of flagella. Observations by electron- and photomicroscopy indicate that the flagella grow outwards through the cell wall of the germinating microcyst. They commence to develop after about 2 hr. incubation. Alike in bacteria with peritrichous and polar flagelia a single, polar or sub-polar flagellum develops first. In the process of maturation the flagella are shed and the non-motile microeysts produced. Basal granules may occasionally be observed. | SUMMARY: The flagella of certain large spirilla appear to be compound structures composed of a large number of individual fibres. These arise in bundles from a single blepharoplast, whereas in other bacteria each flagellum arises separately. The flagella of spirilla are thus, in some respects, intermediate between those of other bacteria and of flagellates. | Purpose ::: The study aimed to characterise a fossil permafrost-affected (Stagnic Fluvisol Relictiturbic) soil, occurring in a cliff in the central part of the Polish Baltic coastal zone near Orzechowo (54° 35.664′ N, 16° 54.123′ E). | eng_Latn | 18,877 |
Several notable lichens were found in the South Slough area near Coos Bay, Oregon, on a foray sponsored by the Northwest Lichenologists. A new record for Bryoria bicolor extends its southern range on the Pacific coast of North America, and information is presented on several other species, including Scoliciosporum sp., a little-reported, undescribed epiphyllous lichen. | Lichens can be found in almost any natural habitat in the Pacific Northwest. In addition to contributing to biological diversity, lichens are ecologically important as food, shelter, and nesting material for wildlife. They play significant roles in hydrological and mineral cycles, notably nitrogen fixation. Lichens are also important as environmental indicators, especially of air quality. Because of their importance in ecosystems and their value in environmental assessment, there is a large and growing interest among natural historians, land managers, and foresters in these organisms. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 18,878 |
Streambed colmation by fine sediment, e.g. the deposition, accumulation and storage of fines in the substrate, is a major environmental concern throughout the world. Nevertheless, the ecological effects of streambed colmation on both benthic and hyporheic invertebrate assemblages have rarely been considered simultaneously. We studied a continuum of a naturally increasing percentage of fine sediment in three temperate rivers and hypothesized that the increasing percentage of fine sediment would decrease both benthic and hyporheic invertebrate densities and diversities, and reduce the similarities between them. To test these hypotheses, we first compared heavily, moderately and lightly clogged reaches located in downwelling areas and sampled invertebrates in the benthic zone and at 3 different depths (10, 30 and 50 cm) in the hyporheic zone. Secondly, we modified the sediment grain size distribution experimentally by increasing the percentage of fine sediment and using artificial substrates. The increasing colmation halved the hyporheic taxonomic richness and reduced benthic and hyporheic densities to a third. Some taxa were found in both zones, mainly in high colmation (e.g. Baetidae) or low colmation contexts (e.g. Orthocladiinae, Cyclopoida and Harpacticoida). The dissimilarity between benthic and hyporheic fauna (only at −50 cm) was significantly higher in heavily clogged reaches than in moderately and lightly clogged ones, suggesting reduced vertical exchange of invertebrates or differential impacts between zones. The total abundance, taxonomic richness, percentage of EPT taxa and densities of most organisms observed using the artificial substrates decreased linearly with the increasing percentage of fine sediment in the experiment. Only the Ephemeroptera Caenis spp. and Heptageniidae disappeared above 30 and 50 % of fine sediment, respectively, suggesting that the response to increasing colmation are strongly taxon-specific. High amount of fine sediments within the substrate significantly decreased habitat quality for benthic and hyporheic invertebrates and thus limit the production of streams and their capacity to recover after disturbance. Moreover, the use of hyporheic invertebrates seems more relevant than benthic invertebrates to assess the effect of colmation and thus could be tested in future research as indicators. | Understanding environmental factors that influence obligate groundwater dwelling (stygobiotic) fauna is crucial for groundwater ecosystem monitoring and management. Field studies have indicated geological factors are a major influence on the abundance and richness of stygofauna, however the precise mechanisms and true influence of the aquifer sediment matrix on biota is unclear. In this study we examined the habitat use and preferences, in terms of sediment particle sizes, of stygobiotic meiofauna (Harpacticoida and Cyclopoida Copepoda), and macroinvertebrates (Amphipoda and Syncarida) using laboratory microcosms. We first tested the ability of each taxon to use (move into) clay (< 0.06 mm), sand (0.3–0.7 mm) and gravel sediments (2–4 mm). Subsequently, the preference for each sediment was compared by examining the distribution of animals in microcosms containing two different sediment types. Both the harpacticoids and cyclopoids were able to use clay, whereas larger amphipods and syncarids mostly remained on the sediment surface. All taxa were able to use sand and gravel substrates. Amphipods preferred gravel over sand and clay. Both copepods and syncarids preferred sand and gravel over clay, but showed no preference between gravel and sand. This study demonstrates the general inability of some stygobiotic macroinvertebrates to use clay sediments and overall differences in sediment use among stygobiotic meio- and macrofauna. From these findings, the typically heterogenous distributions and diversity of stygofauna observed in field studies may be related to variability in sediment composition. | A 75-year-old woman suffered severe haemoptysis after insertion of a Swan-Ganz catheter in an intensive care unit. Control of the pulmonary artery haemorrhage was quickly and successfully achieved with stainless steel coils as the embolic material. | eng_Latn | 18,879 |
The present paper deals with thoracic cirripeds collected in the supralittoral, mediolittoral, and upper infralittoral zones of Antalya Bay (eastern Mediterranean, Turkey) between August 2009 and January 2010. A total 13477 specimens belonging to 7 species and 6 genera were found in the area. Among these, Chthamalus montagui and Lepas anatifera are new records for the Mediterranean coast of Turkey. Chthamalus stellatus is the dominant species in the supralittoral and mediolittoral zones, reaching a maximum density of 69600 ind.m-2 and a biomass of 3100 g.m-2. Perforatus perforatus was the dominant species in the infrallitoral zone, comprising 71% of the total number of individuals and 85% of the total biomass in this zone. Biometrical features of the shells of the dominant species were analysed and their length-weight relationships were estimated. In addition, a check-list of the thoracic cirripeds that have been reported from the coasts of Turkey up to date is provided. | Temporal and spatial variation in soft-bottom benthic communities following recovery from a pollution episode were studied between January and September 2004 in and around Alsancak Harbor, located in the polluted part of Izmir Bay (Aegean Sea, eastern Mediterranean). Samples were collected at seven stations by van Veen grab. Three additional stations were sampled by means of a beam trawl to take into account large mobile animals and for a better estimate of the local biodiversity. A total of 231 species belonging to 10 zoobenthic groups were found. Polychaetes contributed 90% of the total faunal populations and mollusks 87% of the total biomass in the area. Community parameters varied significantly among stations and sampling periods; number of species ranged from 2 to 79 per 0.1 m 2 grab sample; density from 20 to 81,720 indAEm )2 ; biomass from 0.1 to 4190 gAEm )2 ; Shannon‐Wiener diversity index (log2 base) from 0.4 to 4.4; and Pielou’s evenness index from 0.11 to 1.0. Collections indicate that a number of species, including those sensitive to pollution, have colonized the area where azoic conditions had been previously reported. A total of six exotic species, Streblospio gynobranchiata, Polydora cornuta, Hydroides dianthus, Hydroides elegans, Anadara demiri and Fulvia fragilis, probably transferred to the area via ballast water or hull fouling, dominated soft or hard substrata in and near Alsancak Harbor. The first two species accounted for more than 70% of the total population in the area, while A. demiri contributed the most to the biomass (93%, at station 7). | MLL1 regulates circadian promoters by depositing H3K4 trimethyl marks, whose levels are also modulated by the NAD+-dependent deacetylase SIRT1. SIRT1 is now shown to promote circadian deacetylation of MLL1, thus affecting MLL1's methyltransferase activity. | eng_Latn | 18,880 |
Zooplankton seasonality and its environmental drivers were studied at four coastal sites within the Northeast Atlantic Shelves Province (Bilbao35 (B35) and Urdaibai35 (U35) in the Bay of Biscay, Plymouth L4 (L4) in the English Channel and Stonehaven (SH) in the North Sea) using time series spanning 1999–2013. Seasonal community patterns were extracted at the level of broad zooplankton groups and copepod and cladoceran genera using redundancy analysis. Temperature was generally the environmental factor that explained most of the taxa seasonal variations at the four sites. However, between-site differences related to latitude and trophic status (i.e. from oligotrophic to mesotrophic) were observed in the seasonality of zooplankton community, mainly in the pattern of taxa that peaked in spring-summer as opposed to late autumn-winter zooplankton, which were linked primarily to differences in the seasonal pattern of phytoplankton. The percentage of taxa variations explained by environmental factors increased with latitude and trophic status likely related to the increase in the co-variation of temperature and chlorophyll a , as well as in the increase in regularity of the seasonal patterns of both temperature and chlorophyll a from south to north, and of chlorophyll a with trophic status. Cladocerans and cirripede larvae at B35 and U35, echinoderm larvae at L4 and decapod larvae at SH made the highest contribution to shape the main mode of seasonal pattern of zooplankton community, which showed a seasonal delay with latitude, as well as with the increase in trophic status. | Mesozooplankton communities in marine ecosystems are mainly influenced by both anthropogenic pollutants (e.g. nutrients and heavy metals) and natural variables (e.g. temperature, salinity and geographic distance). To achieve a deeper understanding of the effects of anthropogenic pollutants on mesozooplankton communities, we analyzed the community structure of mesozooplankton from 91 stations representing five typical estuarine regions in the Bohai Sea and assessed the relative importance of anthropogenic pollutants and natural variables by using multiple statistical approaches. Cd was identified as the leading pollutant for observed community variation among the five regions, followed by NH4-N and COD. Redundancy analysis (RDA) model demonstrated that mesozooplankton communities were largely determined by both anthropogenic pollutants and natural variables, and the indicator species of mesozooplankton also varied when responding to different factors. Variance partitioning analysis showed both anthropogenic pollutants and natural variables posed significant influences (ANOVA, P < 0.05) on the mesozooplankton community structure, but the explanatory power of anthropogenic pollutants overrode the natural variables. These observations highlighted the importance of anthropogenic pollutants in the shifts of zooplankton structures among different regions. Our results obtained in this study provided new insights into the mechanism of the influence of anthropogenic pollutants on mesozooplankton communities in estuarine areas. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 18,881 |
Macroinvertebrates (oligochaetes) as indicators of pollution: A review | Macroinvertebrates formed an important constituent of an aquatic ecosystem and had functional importance in assessing the trophic status as the abundance of benthic fauna mainly depends on physical and chemical properties of the substratum and thus the benthic communities respond to changes in the quality of water and available habitat. This review discussed the occurrence, composition and distribution of macroinvertebrates of lakes and wetlands, and some environmental factors which regulated their occurrence and distribution. Also, analysis of the benthic community helped in the determination of trophic status of lakes because of their sensitivity to pollution and is, therefore, an important criterion in the ecological classification of lakes. | *Corresponding author: Stephen J. Hawkins, Ocean and Earth Science, National Oceanography Centre Southampton, Waterfront Campus, University of Southampton, European Way, Southampton, SO14 3ZH, UK, Tel: (023) 8059 3596; E-mail: [email protected] January 24, 2013; Accepted January 25, 2013; Published January 28, 2013Citation: Hawkins SJ, Vale M, Firth LB, Burrows MT, Mieszkowska N, et al. (2013) Sustained Observation of Marine Biodiversity and Ecosystems. Oceanography 1: e101. doi:10.4172/ocn.1000e101Copyright: © 2013 Hawkins SJ, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. | kor_Hang | 18,882 |
Botryococcene–a tetramethylated acyclic triterpenoid of algal origin | Structure (3) is suggested on chemical and biosynthetic grounds for the major metabolite of the resting state of the alga Botryococcus braunii. | The microorganisms that account for 90% of the biomass in the upper layer of the open sea are so small they pass through a 10 µm porosity plankton net, but are so numerous that a 3 or 30 ml sample yields a statistically significant count of the bacteria and flagellates, respectively. The bacterial population contains not only the organotrophs responsible for organic matter decomposition and mineralization, but conspicuous and important populations of both phototrophic and chemotrophic autotrophs as well as an undetermined population of lysotrophic bacteria which prey upon other bacteria. These procaryotic cells lacking membrane-bound organelles interact with the eucaryotic (true) cells of the protists (unicellular microorganisms with organelles) that are equally divided between chloroplast-containing phototrophic flagellates and colorless phagotrophic (particle eating) flagellates. | eng_Latn | 18,883 |
Biogeography rather than association with cyanobacteria structures symbiotic microbial communities in the marine sponge Petrosia ficiformis | 16S rRNA Phylogeny of Sponge-Associated Cyanobacteria | Evaluating tropical phytoplankton phenology metrics using contemporary tools | eng_Latn | 18,884 |
Snows that persist late into the growing season become colonized with numerous metabolically active microorganisms, yet underlying mechanisms of community assembly and dispersal remain poorly known. We investigated (Illumina MiSeq) snow-borne bacterial, fungal, and algal communities across a latitudinal gradient in Fennoscandia and inter-continental distribution between northern Europe and North America. Our data indicate that bacterial communities are ubiquitous regionally (across Fennoscandia), whereas fungal communities are regionally heterogeneous. Both fungi and bacteria are biogeographically heterogeneous inter-continentally. Snow algae, generally thought to occur in colorful algae blooms (red, green, or yellow) on the snow surface, are molecularly described here as an important component of snows even in absence of visible algal growth. This suggests that snow algae are a previously underestimated major biological component of visually uncolonized snows. In contrast to fungi and bacteria, algae exhibit no discernible inter-continental or regional community structure and exhibit little endemism. These results indicate that global and regional snow microbial communities and their distributions may be dictated by a combination of size-limited propagule dispersal potential and restrictions (bacteria and fungi) and homogenization of ecologically specialized taxa (snow algae) across the globe. These results are among the first to compare inter-continental snow microbial communities and highlight how poorly understood microbial communities in these threatened ephemeral ecosystems are. | Snow algae (Chlorophyta) are reported from the Sierra Nevada mountains in southern Spain and the High Atlas mountains of Morocco. Populations of the snow algae Chlamydomonas sp., coloring the snow orange-red, were collected from Pico de Veleta, Spain, while snow samples from Mt. Neltner in the High Atlas mountains, contained resting spores of an orange-green colored Chloromonas sp. Other microbes observed in snow samples include bacteria, fungi, heterotrophic euglenids, diatoms, nematodes, and heterotrophic mastigotes (flagellated protists). This is the first report of snow algae from the Sierra Nevada mountains of Spain and from the Afro-alpine environment. | Silver nanomaterials have been integrated into industrial, biomedical and agricultural application, including biosensor, anti-microbial, anti-tumor, drug delivery, waste treatment, coated fabrics and nano fertilizer. Nanoparticle possesses unusual character due to their large surface area to volume ratio and an extraordinary catalytic activity, electronic properties, optical properties and anti-microbial activity while they are constructed in atomic level. The unique and major task in the synthesis of nanoparticle is choosing of an advanced and ecofriendly method. Nevertheless, physical and chemical methods of synthesis of nanoparticles are too expensive and environmentally unsound. In this study, the green synthesis of nanoparticle’s production methods was evaluated on the basis of variable literatures. Currently, there is a better possibility of using green synthesis of silver nanoparticles, especially a plant, bacterial and fungal production of nanoparticles which is emerging as a novel ecofriendly technique. The growth rate of bacterial culture, the extract of plant secondary metabolite and mycelial surface area of fungus are the main comprehensible mechanism in green synthesis of silver nanoparticles. The silver nanoparticles, which are produced through green biosynthesis is safe and hold a better possibility to be administered for medical and agricultural usages. Over all we found that the fungal green biosynthesis of silver nanoparticles is considered more preferable and is excellently chosen in it in industrial level production. | eng_Latn | 18,885 |
The epiphyton on 22 macrophyte species was studied in the hypertrophic stratified Lake Verevi mainly in the midsummer of 2000 and 2001. Some material from 1998 and 1999 was used as well. Chlorophyll a (Chl a) level was high: 330–360 μg g dw−1 on emergent plants, and an average of 117–200 μg on floating-leaved plants and 820–920 μg g dw−1 on submerged plants. Biomass was 15–23, 5–10 and 35–53 mg g dw−1, respectively. The richest in epiphyton were submerged plants with densely growing and fine branchlets such as Ranunculus, Ceratophyllum, Myriophyllum, Utricularia, Potamogeton pectinatus L. and P. friesii Rupr. The share of Chl a in biomass was higher in 2001 (2.3%) than in 2000 (1.7%), which can be associated with lower irradiance in summer 2001. Filiform chlorophytes were dominating on most plants; 60% of biomass on submerged, 69% on emergent and 80% on floating-leaved plants; in some cases, the share of filamentous species was 95%. Diatoms formed 29, 12 and 7%, cyanobacteria 8, 16 and 10% of the same ecotopes, respectively. As a rule, the epiphyton was quite sparse on large Potamogeton leaves. Cyanobacteria were more abundant on large Potamogeton and Nuphar leaves, Elodea, on stems of P. natans L., Nuphar and on some emergent plants with a smooth and soft stem surface, as Butomus and Typha. Diatoms played the most important role on some Potamogeton species and in single samples of Ceratophyllum and Ranunculus. The morphology of plant species appears to be the main factor of epiphyton richness in L. Verevi. | Article History: Received 5, February, 2015 Received in revised form 12, February, 2015 Accepted 6, March, 2015 Published online 28, March, 2015 Sahashradhara springs, a group of one thousand springs and one of the prominent tourist spot, is located in Doon Valley of Garhwal-Himalayas. The environmental monitoring of periphyton community of Sahashradhara springs was carried out for a period of one annual cycle (October 2011-September 2012). A total of 29 species belonging to three annual classes: Bacillariophyceae (14), Chlorophyceae (11) and Cyanophyceae (04) were recorded from different springs of Sahashradhara. Among the various periphyton community the dominance and density of Bacillariophyceae was found maximum followed by Chlorophyceae and Cyanophyceae. Members of Cyanophyceae were found absent during monsoon season. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 18,886 |
A seasonal quantitative study was conducted on the plankton of four Newfoundland ponds. There are indications that one pond received inputs of airborne pollutants emanating from a phosphorus plant. All ponds are characterized by high flushing rates. Highest numbers of both phytoplankton and zooplankton organisms tended to occur from late spring through summer, the period of greatest water retention. The phytoplankton was dominated for the most part by nano-plankton forms. Large blooms of Anabaena flos-aquae and Asterionella formosa occurred during summer in the pond located near the phosphorus plant. This did not occur in the other ponds. Dominant microcrustaceans encountered included Holopedium gibberum, Diaptomus minutus, and Epischura nordenskioldi. Of the rotifers encountered, collectively the most important forms were Polyarthra dolichoptera, Conochilus unicornis, Keratella cochlearis, Kellicottia longispina, Kellicottia bostoniensis, Pleosoma truncatum, Synchaeta sp., and Trichocerca sp. Aspects of the ecology of the phytoplankton and zooplankton are discussed in the context of water retention characteristics. A comparison is made with a pond subject to pollution from rural and urban sources. This pond also possesses a high flushing rate. | Phytoplankton biomass values in Tavropos Reservoir, ranging from 92 to 1071 mg m−3, are within a range characteristic of oligotrophic waters. The seasonal sequence of biomass shows three annual peaks, differing from the monoacmic pattern seen in oligotrophic lakes. This sequence was profoundly affected by changes in water withdrawal and inflow rates. Diatoms, cryptophytes, chrysophytes and dinoflagellates, in that order, were the major constituents of the reservoir phytoplankton. The succession, from diatoms and chrysophytes in late winter-spring, to centric diatoms in late spring-summer and again to diatom-chrysophytes in late autumn was similar to that in oligotrophic lakes. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 18,887 |
The relationship between bacteria and chlorophyll a was investigated for three months from July to September, 2008 during flood and ebb tide periods at two sites in the Cross River basin, southeastern Nigeria, to ascertain the reliance of bacteria on autochthonous organic matter. There was no significant difference between flood water and ebb water samples at both stations for the entire variable measured. Bacterial cell abundance showed a weak positive correlation with chlorophyll a concentration at Station 1 (r* = 0.132, P > 0.05) and a strong positive correlation at Station 2 (r* = 0.599, P > 0.5). The micronutrients at both stations showed a weak negative correlation with chlorophyll a concentration. Linear regression analysis together with standardized coefficient value revealed a high bacteria/chlorophyll a relationship at Station 2 and a weak bacteria/chlorophyll a relationship at Station 1. Principal Component Analysis was applied to the measured variable, and a high correlation was observed between bacterial cell abundance and chlorophyll a concentration at Station 2. A strong reliance of bacteria on chlorophyll a was established at Station 2 whereas Station 1 showed a weak correlation indicating the strong dependence of bacteria on allochthonous organic matter. This bacterial abundance could serve as a good source food for protozoans in transferring energy to classic food chain. | Bacterial community structure and metabolism are critical factors for ecosystem functioning since they affect remineralization of nutrients and carbon flow. We used Illumina sequencing of 16SrRNA V3-V4 regions to investigate whether bacterial assemblage composition differs between four samples from two lakes in the geographic region of Epirus (Greece) characterized by distinct oligotrophic to eutrophic/hypereutrophic conditions as revealed by chlorophyll-a values. We found high similarity (>60%) for bacterial assemblages recovered from the two lakes when eutrophic/hypereutrophic conditions prevailed. Distinct bacterial communities appeared in oligotrophic and mesotrophic waters. Low temperature was occasionally an important factor in shaping the bacterial community. In parallel, microcosm experiments were performed to estimate respiration rates of bacterioplankton at in situ temperature and under a 2 °C temperature increase scenario. Differently assembled communities were found to display similar rates except under hypereutrophic conditions when respiration increased significantly, leading to hypoxic conditions. Temperature increase did not affect respiration rates. Overall this study indicated a clear differentiation of bacterial communities between sites of different trophic state. However, different communities responded similarly under a specific range of chlorophyll-a values and resisted small scale temperature perturbations. Different results were found for hypereutrophic conditions and this has implications for ecosystems functioning, given the increasing occurrence of eutrophication events. | The primordial abundances of light elements produced in the standard theory of Big Bang nucleosynthesis (BBN) depend only on the cosmic ratio of baryons to photons, a quantity inferred from observations of the microwave background. The predicted primordial 7Li abundance is four times that measured in the atmospheres of Galactic halo stars. This discrepancy could be caused by modification of surface lithium abundances during the stars' lifetimes or by physics beyond the Standard Model that affects early nucleosynthesis. The lithium abundance of low-metallicity gas provides an alternative constraint on the primordial abundance and cosmic evolution of lithium that is not susceptible to the in situ modifications that may affect stellar atmospheres. Here we report observations of interstellar 7Li in the low-metallicity gas of the Small Magellanic Cloud, a nearby galaxy with a quarter the Sun's metallicity. The present-day 7Li abundance of the Small Magellanic Cloud is nearly equal to the BBN predictions, severely constraining the amount of possible subsequent enrichment of the gas by stellar and cosmic-ray nucleosynthesis. Our measurements can be reconciled with standard BBN with an extremely fine-tuned depletion of stellar Li with metallicity. They are also consistent with non-standard BBN. | eng_Latn | 18,888 |
The sediment contents of algal pigments and live planktonic diatoms were measured in cores sampled at 6 stations with aphotic sediments at depths between 27 and 55 m located in the transition zone between the Baltic Sea and the Skagerrak. Five of the stations were sampled before and after the spring phytoplankton bloom in 2001. Within the area, there was a highly significant increase after the bloom in the sediment content of viable planktonic diatoms, quantified by the dilution extinction method, and in the sediment content of the pigments chlorophyll a and fucoxanthin. The composition of algal pigments as well as the number of germinable diatoms suggested that live pelagic diatoms were the source of almost the entire pool of chlorophyll a in the sediment both before and after the spring bloom. In the northern Kattegat, Great Belt, Femer Belt and in the Arkona Sea, the pools of diatoms increased 10- to 100-fold during the spring bloom. In total, the sediment received between 0.3 and 4 million germinable units of pelagic diatoms cm -2 . In terms of organic nitrogen, the enrichment of live diatoms in the sediment corresponded to on average 202% of the total spring bloom production, calculated from the pool of nitrate consumed in the water column during the spring bloom. A similar calculation based on the enrichment of the pigments chlorophyll a and fucoxanthin indicated input corresponding to 24 and 64 % respectively of the potential production during the spring bloom. There was considerable variation among stations; in the central Kattegat there was no detectable sedimentation of diatoms or pigments. Here, the pools of pigments and diatoms decreased during the spring bloom and the shape of the pigment profiles also indicated that these pools did not originate from a recent input. Other stations received twice as much diatom biomass than could be produced from the pool of inorganic nitrogen in the mixed layer before the bloom. It is hypothesized that the unequal distribution of the spring bloom sedimentation is a result of episodic sedimentation events in combination with advection of the water masses. The potentials of using sediment profiles of pigments to quantify spring bloom sedimentation are discussed. | Diatom aggregate formation was analyzed using coagulation theory. Population dynamics models show that coagulation has an important impact on species succession during diatom blooms. When different species collide and form mixed aggregates this process causes interspecific interference competition within the diatom community. The outcome can be predicted by a set of simple differential equations. For a twospecies system the equations reduce to the Lotka-Volterra two-species competition model. The outcome of this interference competition depends on species-specific growth rates, cell sizes, stickiness and on the species composition of the seeding populations of a bloom. Due to mutual flocculation some species may disappear from the environment. Small and fast growing diatoms are favoured by high stickiness coefficients. The impact of stickiness on species succession was found to be most pronounced in eutrophic and hydrographically isolated environments. The sticking properties of the diatom Skeletonema costatum are discussed in an evolutionary context; we suggest that mutual coagulation increases the abundance of S. costatum relative to other diatom species in coastal areas. The model was tested on field data, and the predicted dynamics of a spring bloom was very similar to that observed. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 18,889 |
In shallow tropical waters, ultraviolet radiation (UVR) occurs at high intensity simultaneously with high water temperatures, and both stressors are predicted to increase in the future and to have a major impact on reef coral survival. The poor knowledge of the interactive effects of those two factors, however, prevents a good estimation of the coral resistance to climate change pressure. The results obtained in this study on two genetically distant scleractinian coral species, Pocillopora damicornis and Turbinaria reniformis, highlight an interaction of temperature and UVR on the corals' physiology as well as a species-specific response. Overall, increase in UVR level exacerbated the negative impact of thermal stress. Whereas stressors did not reduce the autotrophic capacity (symbiont density, net photosynthetic rates) of T. reniformis, they significantly lowered it in P. damicornis, which initially contained twice more symbionts in its tissue. Only grazing rates (heterotrophy) were significantly decreased in T. reniformis under thermal stress. For both corals, calcification was slowed by the combination of thermal and UVR stress. Calcification was impaired likely due to a decrease in autotrophic energy supply in P. damicornis, and in heterotrophic energy supply in T. reniformis. This study confirms that the response of corals to global change needs to be studied using multifactorial approaches and a combination of different environmental factors. | ABSTRACT Coral bleaching events are predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes depends on many factors, including the magnitude of thermal stress and irradiance. The interactions among these two factors, and in particular with ultra-violet radiation (UVR), the most harmful component of light, are more complex than assumed, and are not yet well understood. This paper explores the individual and combined effects of temperature and UVR on the metabolism of Acropora muricata , one of the most abundant coral species worldwide. Particulate and dissolved organic matter (POM/DOM) fluxes and organic matter (OM) degradation by the mucus-associated bacteria were also monitored in all conditions. The results show that UVR exposure exacerbated the temperature-induced bleaching, but did not affect OM fluxes, which were only altered by seawater warming. Temperature increase induced a shift from POM release and DOM uptake in healthy corals to POM uptake and DOM release in stressed ones. POM uptake was linked to a significant grazing of pico- and nanoplankton particles during the incubation, to fulfil the energetic requirements of A. muricata in the absence of autotrophy. Finally, OM degradation by mucus-associated bacterial activity was unaffected by UVR exposure, but significantly increased under high temperature. Altogether, our results demonstrate that seawater warming and UVR not only affect coral physiology, but also the way corals interact with the surrounding seawater, with potential consequences for coral reef biogeochemical cycles and food webs. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 18,890 |
Although recent research has indicated that bacteria may contribute an important fraction of biochemical residues in terrestrial and marine environments, it is difficult for geochemists to identify contributions from these ubiquitous and biochemically diverse organisms. Previous studies have suggested uronic acids and O -methyl sugars may be useful indicators of microbial abundance and activity, but have been limited primarily to analyses of a small number of isolated samples. We report here comparative distributions of O -methyl sugars, uronic acids, and aldoses in sediment trap material and sediments from Dabob Bay, WA and nearby Saanich Inlet, BC, where temporal and spatial trends may be used together with well-established patterns in other biochemicals to identify bacterial contributions against the background of other carbohydrate sources. O -methyl sugars and uronic acids were important contributors to the overall flux and burial of polysaccharide material in Dabob Bay and Saanich Inlet, composing ≤12 wt% of the total carbohydrate yields from sediment trap and sediment samples. O -methyl sugars accounted for an average of 5% of the carbohydrate yields from sediment trap materials and sediments, but were found rarely and only in low abundance in vascular plant tissues, phytoplankton, and kelp. In contrast, uronic acids were abundant products of sediment trap material and sediments, as well as vascular plant tissues, where in some cases they predominated among all carbohydrates. Uronic acid abundance in sediment trap material averaged 3% and ranged to >6% of total carbohydrate yields. The persistence of total minor sugar yields in water column collections from Dabob Bay throughout the seasonal cycle indicated they had a primary source that was not directly related to plankton bloom cycles nor pulsed inputs of vascular plant remains. Subsurface maxima in total minor sugar yields (and several individual components) within sediment cores from both sites indicate in situ sedimentary sources. Taken together, the observed environmental distributions strongly suggest that the minor sugar abundances in Dabob Bay and Saanich Inlet were controlled by in situ microbial production. | The fine grained carbonate mud sediments of central Florida Bay are resuspended quite easily. However, this disturbance is usually limited to the surficial (‘floc’) layer, as the underlying sediments appear to be stabilized by an hydrogelation involving the bulk organic matter. That gelation has occurred within these sediments is suggested from their physical behavior and an observed mathematical relationship between the percentages of organic carbon (Corg) and water. Specifically, when extruded from a core barrel, the sediment maintains its integrity and has the consistency of a fine spackling compound. However, upon homogenization, as with a stirring rod prior to sieving, these sediments break into two distinct phases, ½–⅔ milky water and ⅓–½ sediment grains, by volume. The relationship observed between Corg and water was modeled as both linear (% water = (0.0777) Corg + 0.2984, R2 = 0.8664) and logarithmic (% water = 0.2489 Ln Corg + 0.2842, R2 = 0.9455) functions. As this relationship tends t... | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 18,891 |
The photosynthetic properties of phytoplankton populations as related to physical–chemical variations on small temporal and spatial scales and to phytoplankton size structure and pigment spectra were investigated in the Northern Adriatic Sea off the Po River delta in late winter 1997. Large diatoms (fucoxanthin) dominated the phytoplankton in the coastal area whereas small phytoflagellates (mainly 19′-hexanoyloxyfucoxanthin, chlorophyll b , 19′-butanoyloxyfucoxanthin) occurred outside the front. The front was defined by the steep gradient in density in the surface layer separating low-salinity coastal waters from the offshore waters. Physical features of the area strongly influenced phytoplankton biomass distributions, composition and size structure. After high volumes of Po River discharge several gyres and meanders occurred in the area off the river delta in February. Decreasing river discharge and the subsequent disappearance of the gyres and the spreading dilution of the river plume was observed in March. The dynamic circulation of February resulted in high photosynthetic capacity of the abundant phytoplankton population (>3.40 mg m −3 ). In March, the slow circulation and an upper low-salinity water layer, segregated from the deeper layers, resulted in lack of renewal of this water mass. The huge phytoplankton biomass, up to 15.77 mg chl a m −3 , became nutrient depleted and showed low photosynthetic capacity. In February, an exceptionally high P max B , 20.11 mg C (mg chl a ) −1 h −1 was recorded in the Po River plume area and average P max B was three-fold in February as compared to the March recordings, 10.50 mg C (mg chl a ) −1 h −1 and 3.22 mg C (mg chl a ) −1 h −1 , respectively. The extreme variability and values of phytoplankton biomass in the innermost plume area was not always reflected in primary production. Modeling of circulation patterns and water mass resilience in the area will help to predict phytoplankton response and biomass distributions. In the frontal area, despite a considerable variability in environmental conditions, our findings have shown that the phytoplankton assemblages will compensate for nutrient depression and hydrographic constraints, by means of size and taxonomic composition and, as a result, the variability in the photosynthetic capacity was much less pronounced than that observed for other parameters. | The chain-forming diatom Chaetoceros vixvisibilis is one of the most abundant and frequent diatoms in the northeastern Adriatic Sea. This species had not been previously studied by electron microscopy. Its general morphology is similar to those species allocated in the subgenus Hyalochaete: cells and chains (straight, of variable length, usually 4-8 cells per chain, but can be longer) of delicate appearance, valves thinly silicified, with slightly eccentric annulus and costae radiating from it, a single rimoportula present only at terminal valves, long, thin and delicate setae perforated by tiny poroids with no spines, and one plate-like chloroplast per cell. Setae with no spines are not common among members of Hyalochaete (and the whole genus Chaetoceros), except C. socialis. The most characteristic feature is, however, the resting spores commonly found, which also show morphological variability, from solitary to paired, both valves convex to domed and surface smooth or with small granules, and one to four strong spines often branching dichotomically. Abundances of C. vixvisibilis are positively correlated to the Po River inflow. Maximum abundances (> 10 6 cells L -1 ) were found in the period April-July, in the temperature range between 12 and 16°C, salinity between 33 and 38, when total phosphorus concentration is higher than 0.4 μmol L -1 , but occasionally also in nitrogen limited conditions. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 18,892 |
Five strains that were morphologically identified as Planktolyngbya circumcreta were isolated from three geographical regions in China. The strains were phylogenetically and taxonomically characterised based on a polyphasic approach that merged morphological and genetic characteristics, as well as ultrastructure. The ultrastructure of these strains showed a similar arrangement of thylakoids, with four to eight parallel layers that were parietally distributed, suggesting that they belonged to the order Synechococcales, family Leptolyngbyaceae. As inferred from 16S rRNA gene sequence analysis, these pure cultures share ≥ 98.5% similarity and were grouped into a unique and robust cluster with high bootstrap values. This unique cluster was separated from a clade composed of two strains of Planktolyngbya limnetica, which belonged to the type species of the genus Planktolyngbya. Thus, we transferred these five P. circumcreta strains to the new genus Limnolyngbya. The species Limnolyngbya circumcreta n... | Some sponges have been shown to accumulate abundant phosphorus in the form of polyphosphate (polyP) granules even in waters where phosphorus is present at low concentrations. But the polyP accumulation occurring in sponges and their symbiotic bacteria have been little studied. The amounts of polyP exhibited significant differences in twelve sponges from marine environments with high or low dissolved inorganic phosphorus (DIP) concentrations which were quantified by spectral analysis, even though in the same sponge genus, e.g., Mycale sp. or Callyspongia sp. PolyP enrichment rates of sponges in oligotrophic environments were far higher than those in eutrophic environments. Massive polyP granules were observed under confocal microscopy in samples from very low DIP environments. The composition of sponge symbiotic microbes was analyzed by high-throughput sequencing and the corresponding polyphosphate kinase (ppk) genes were detected. Sequence analysis revealed that in the low DIP environment, those sponges with higher polyP content and enrichment rates had relatively higher abundances of cyanobacteria. Mantel tests and canonical correspondence analysis (CCA) examined that the polyP enrichment rate was most strongly correlated with the structure of microbial communities, including genera Synechococcus, Rhodopirellula, Blastopirellula, and Rubripirellula. About 50% of ppk genes obtained from the total DNA of sponge holobionts, had above 80% amino acid sequence similarities to those sequences from Synechococcus. In general, it suggested that sponges employed differentiated strategies towards the use of phosphorus in different nutrient environments and the symbiotic Synechococcus could play a key role in accumulating polyP. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 18,893 |
Seagrasses and associated macrophytes are important components of coastal systems as ecosystem engineers, habitat formers, and providers of food and shelter for other organisms. The positive impacts of seagrass vegetation on zoobenthic abundance and diversity (as compared to bare sands) are well documented, but only in surveys performed in summer, which is the season of maximum canopy development. Here we present the results of the first study of the relationship between the seasonal variability of seagrass vegetation and persistence and magnitude of contrasts in faunal communities between vegetated and bare sediments. The composition, abundance, biomass, and diversity of macrozoobenthos in both habitats were compared five times throughout the year in temperate eelgrass meadows in the southern Baltic Sea. Significant positive effects of macrophyte cover on invertebrate density and biomass were recorded only in June, July, and October when the seagrass canopy was relatively well developed. The effects of vegetation cover on faunal species richness, diversity, and composition persisted throughout the year, but the magnitude of these effects varied seasonally and followed changes in macrophyte biomass. The strongest effects were observed in July and coincided with maximums in seagrass biomass and the diversity and biomass of other macrophytes. These observations indicate that in temperate, clearly seasonal systems the assessment of macrophyte impact cannot be based solely on observations performed in just one season, especially when that season is the one in which macrophyte growth is at its maximum. The widely held belief that macrophyte cover strongly influences benthic fauna in marine coastal habitats, which is based on summer surveys, should be revisited and complemented with information obtained in other seasons. | This study presents the first report on bacterial communities in the sediments of eelgrass (Zostera marina) meadows in the shallow southern Baltic Sea (Puck Bay). Total bacterial cell numbers (TBNs) and bacteria biomass (BBM) assessed with the use of epifluorescence microscope and Norland’s formula were compared between bare and vegetated sediments at two localities and in two sampling summer months. Significantly higher TBNs and BBM (PERMANOVA tests, P < 0.05) were recorded at bottom covered by the seagrass meadows in both localities and in both sampling months. The relationships between bacteria characteristics and environmental factors (grain size, organic matter, photopigments in sediments), meiofauna and macrofauna densities, as well as macrophyte vegetation characteristics (shoot density, phytobenthos biomass) were tested using PERMANOVA distance-based linear model (DISTLM) procedures and showed that the main factors explaining bacteria characteristics are bottom type (vegetated vs. unvegetated) and meiofauna density. These two factors explained together 48.3 % of variability in TBN and 40.5 % in BBM, and their impacts did not overlap (as indicated by DISTLM sequential tests) demonstrating the different natures of these relationships. The effects of seagrass were most probably related to the increase of organic matter and providing habitat while higher numbers of meiofauna organisms may have stimulated the bacterial growth by increased grazing. | We report an unusual case of infective endocarditis (IE) in an 88-year-old woman, occurring on a prolapsing mitral valve and characterized by an atypical vegetation shape resembling a spiral-like appearance. After the patient refused surgical correction, persistent IE despite prolonged antibiotic therapy was observed, resulting in an ischemic stroke probably secondary to septic embolus. The importance of vegetation shape in the management of patients with IE was classically related to the increased risk of embolization associated with pedunculated, irregular, and multilobed masses. We hypothesize that the unusual spiral-like vegetation shape in our patient may have favored IE persistence by two mechanisms, namely, a decrease of the exposed vegetation surface with creation of an internal core where the penetration of antimicrobial agents was obstacled and the creation of blood turbulence within the vegetation preventing a prolonged contact with circulating antibiotics. These considerations suggest that vegetation shape might be considered of importance in patients with IE not only because of its classical association with embolization risk, but also because of its potential effect on the efficacy of antibiotic therapy. | eng_Latn | 18,894 |
Competitive outcome between the rotiferBrachionus calyciflorusand the cladoceranMoina macrocopadepends on algal density but not temperature | Competition between two planktonic rotifer species at different temperatures: an experimental test | Mdm2 promotes the rapid degradation of p53 | eng_Latn | 18,895 |
The mobility of methylmercury in biological systems. | Fine-Scale Tissue Distribution of Cadmium, Inorganic Mercury, and Methylmercury in Nymphs of the Burrowing Mayfly Hexagenia rigida Studied by Whole-Body Autoradiography | Methodological constraints in the molecular biodiversity study of a thermomineral spring cyanobacterial mat: a case study | eng_Latn | 18,896 |
Patterns of ammonium uptake within dense mats of the filamentous macroalga Chaetomorpha linum | Isotope dilution models of uptake and remineralization of ammonium by marine plankton1 | Mdm2 promotes the rapid degradation of p53 | eng_Latn | 18,897 |
The role of TEP (Transparent Exopolymer Particles) in the flocculation of a diatom bloom was studied under controlled conditions in a mesocosm. The concentration of TEP increased exponentially during growth, flocculation and senescence of the bloom. Aggregation began dominating the particle dynamics of TEP during the early growth phase of the bloom, several days prior to the appearance of large flocs and nutrient depletion. TEP aggregated with themselves and with phytoplankton due to the high stickiness of TEP, but phytoplankton was not observed to aggregrate with itself. The production of TEP, estimated from changes in concentration, did not increase after nutrients were depleted. The concentration of TEP was a linear function of chl a and particulate organic carbon (POC), indicating that production of TEP was linked to growth rather than standing stocks of phytoplankton. The ratio between TEP and phytoplankton appeared to be one of the factors determining the onset of the flocculation of the bloom. The concentration of TEP may have been decreased by bacterial degradation. Bacterial degradation of TEP may explain the low TEP to chl a values, the decrease in stickiness of particles as the bloom progressed, and the retarded onset of flocculation. | Direct interactions between phytoplankton and bacteria are hypothesized to impact bloom dynamics, community succession, and primary productivity. Such impacts may be depen- dent upon bacterial attachment to phytoplankton, but few studies have quantified this relation- ship in natural marine waters and little is known regarding factors regulating attachment. During a study of thin layer dynamics in Monterey Bay, California, USA, we collected over 18 000 phyto- plankton cells and analyzed them for attached bacteria. We focused our statistical analysis on abundant diatoms and dinoflagellates often associated with thin layers and surface slicks. More than 90% of phytoplankton cells analyzed did not harbor attached bacteria. When colonization had occurred, a single attached bacterium was the most common occurrence and few cells had multiple attached bacteria. Visually healthy phytoplankton were rarely colonized, but those col- lected outside of dense thin layers and surface slicks had higher incidences of colonization and were more likely to harbor multiple bacteria. Longer diatom chains had a higher probability of being colonized and of bacteria being selectively attached to specific regions within the chains. These results strongly suggest that phytoplankton abundance, health, and morphology regulate colonization by bacteria in the natural marine environment. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 18,898 |
The dumping of bauxite tailings into Batata Lake, an Amazonian clear-water lake, generated high levels of turbidity and caused a serious decrease in phytoplankton densities, which could possibly be the result of a photosynthetic limitation due to light attenuation together with an increase in algal sinking due to the adhesion of clay particles. This study aimed to investigate the sinking process through the addition of different suspended clay concentrations in columns containing Batata lake water. Since no effect of the suspended clays on Batata Lake phytoplankton sinking was observed, it was then evaluated, under laboratory conditions, whether the low conductivity of the Batata Lake water could interfere with the algae-clay aggregation process. Cultures of two algal species known to be capable to aggregate to Batata Lake suspended clays in algal culture medium: Staurodesmus convergens and Phormidium amoenum, were added to both the low conductivity Batata Lake water (14 μS cm−1) and the high conductivity algal culture media (WC – 300 μS cm−1 and Z8 – 560 μS cm−1) together with Batata lake suspended clays. In both algal culture media and Batata lake water the two species had their sinking accelerated due to clay adhesion. It is thus suggested that the decrease in phytoplankton densities recorded in Batata Lake may not be related to an increase in phytoplankton loss rates due to algal-clay aggregation, but rather are a consequence of decreasing growth rates because of light attenuation. | In recent decades, many perialpine lakes have been affected by oligotrophication due to efficient sewage treatment and by altered water turbidity due to upstream hydropower operations. Such simultaneous environmental changes often lead to public debate on the actual causes of observed productivity reductions. We evaluate the effects of those two changes by a combined approach of modeling and data interpretation for a case study on Lake Brienz ( Switzerland), a typical oligotrophic perialpine lake, located downstream of several hydropower reservoirs. A physical k-epsilon scheme and a biogeochemical advection-diffusion-reaction model were implemented and applied for several hypothetical scenarios with different nutrient loads and different particle input dynamics. The simulation results are compared to long-term biotic data collected from 1999 to 2004. The analysis shows that enhanced nutrient supply increases the nutritious value of algae, stimulating zooplankton growth, while phytoplankton growth is limited by stronger top-down control. Annually integrated productivity is only slightly influenced by altered turbidity, as phosphorous limitation prevails. Simulations indicate that the spring production peak is delayed because of increased turbidity in winter caused by upstream hydropower operation. As a consequence, the entire nutrient cycle is seasonally delayed, creating an additional stress for zooplankton and fish in the downstream lake. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 18,899 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.