Regardless of region, earth's tilt results in yearly seasonal changes, which organisms deal with through processes like migration/hibernation. Both seem like attempts to avoid the extreme fluctuations... so why haven't certain organisms developed environmentally-reactive bodies, changing with the seasons throughout the year (based on measures like temperature- I.E., additional fur growth during the winter), and why hasn't this continued as an evolutionary advantage to allow organisms to thrive in longer environmental ranges (like staying in place instead of migrating) or even go a step beyond and take advantage of the qualities specific to each season?
If a trait would be advantageous to an organism then why hasn't it evolved yet?  Conversely, if a trait is not advantageous or mildly disadvantageous, why does it exist?  In other words why does evolution not make the organism more "perfect"?    This is a general question that would be applicable for any kind of trait. Please keep the answers precise and scientific.   Read this meta post for more information:
If $q$ is coprime to $a$ then $a\mid nq-1,\,$ so $q$ is invertible mod $a$ I think the following is true:  If $q$ is coprime to $a$ then $a\mid (nq-1)$ for some $n\in\mathbb Z$.  I have started to first reducing $n\in\mathbb Z$ to $n\in\{1,\ldots,a-1\}$ and then considering all the cases $q = ka + j$ for $j=1,2,3,\ldots,a-1$. I stopped at $j=3$ and found that this is kinda messy. Does anyone have an elegant proof for this (maybe using some results from number theory)?  [Note: question has been generalized from prime $q\nmid a$ to $\,q$ coprime to $a$] Will hardware changes affect system? I want to return two objects from a Java method and was wondering what could be a good way of doing so?  The possible ways I can think of are: return a HashMap (since the two Objects are related) or return an ArrayList of Object objects.  To be more precise, the two objects I want to return are (a) List of objects and (b) comma separated names of the same.  I want to return these two Objects from one method because I dont want to iterate through the list of objects to get the comma separated names (which I can do in the same loop in this method).  Somehow, returning a HashMap does not look a very elegant way of doing so. Does Two-Face die at the end of The Dark Knight? I am doing an animation. The images I have attached show 2 different render layer view node results.    Image one shows a cube on layer 1, and 2 icosphere on layer 2. I have layer 2 set to fast blur. I have to use transparent film and therefore I use the Alpha over nodes in composition.  Image two shows a cube and 1 icosphere. Image 1 should not be showing 2 icospheres, as the left most one is behind the cube.    Image 2 is from the same render result, and is correcting showing only 1 icosphere. However, that icosphere should be blurred as it is on layer 2. It seems for whatever reason I can not have both the correct composition effect and also have every object's visibility render correctly. I can only either have everything work fine, with no composition, or composition with every emission object showing through every other object in the scene.   I am aware that masks would solve this problem, but because of the complicated setup of object materials and particles, masking produces these very strange and suddenly appearing artifacts. Material Indexing also produces odd artifacts and does not consistently effect the appropriate materials.   This is also a new problem, I did not have this issue in the last blender version. So, material indexing is out, masking is out, object indexing is out.       I want to use the compositor to blur certain layers, but every emission object in the scene shows through. It shows through as though it was on x-ray, regardless if it is behind another or inside another object. The first image is an example of this, the left icosphere is behind the cube, and should not be visible. That is the problem. Why is it visible when it shouldn't be? I've noticed this on occasion with a variety of applications. I've often thought it was because the output was cancelled early (ctrl+c, for example) or something similar, and zsh is filling in a new line character. But now curiosity has gotten the best of me, since it doesn't seem to do this in bash.   zsh    bash    The Sequence program is something I pulled from a book while reading on Java certifications and just wanted to see if it would compile and run. I did notice that it does not use the println() method from the System.out package/class. Instead it uses plain old print().  Is the lack of a new line character the reason I get this symbol? I keep reading about  ('PPAs') and people answer questions with a link to a PPA. What's the best way to use these?     There are multiple valid answers for this question spanning over several versions of Ubuntu. For your convenience, an index of each is below. How do I set environment variables from Java?  I see that I can do this for subprocesses using . I have several subprocesses to start, though, so I'd rather modify the current process's environment and let the subprocesses inherit it.  There's a System.getenv(String) for getting a single environment variable. I can also get a Map of the complete set of environment variables with System.getenv(). But, calling put() on that Map throws an UnsupportedOperationException -- apparently they mean for the environment to be read only. And, there's no System.setenv().  So, is there any way to set environment variables in the currently running process?  If so, how?  If not, what's the rationale?  (Is it because this is Java and therefore I shouldn't be doing evil nonportable obsolete things like touching my environment?)  And if not, any good suggestions for managing the environment variable changes that I'm going to need to be feeding to several subprocesses? Cooking steak in frying pan, problem with oil splatter I was using canola oil and put the stove top setting on "high - 9". I read plenty of guides suggesting there will infact be oil splatter, but it was pretty excessive and burning my arm with one drop getting near my eye before I stopped. I turned the heat setting down to "medium - 4", where the oil splatter seemed to drop substantially. Before I try to make steak again I'd like to get some clarification  So my questions are:   Which heat setting am I supposed to use? Is that type of oil splatter normal or should I try using a different oil, and if so, what oil? Should oiling the meat instead of the pan help the problem? Let $R$ be a commutative ring with finitely many maximal ideals $\mathfrak m_1,\ldots,\mathfrak m_n$. Let $M$ be a finitely generated module. Then there exists an element $x\in M$ such that $\frac{x}{1}\not\in\mathfrak m_iM_{{\mathfrak m}_i}$ for every $i=1,\dots,n$.    I cannot prove that such an element there exists. I was trying to prove it by induction on $n$. If $n=1$ it is true by Nakayama, so suppose it is true for $n-1$. Then for every $i$ I can find an $x_i\in M$ such that $\frac{x_i}{1}\not\in \mathfrak m_jM_{\mathfrak m_j}$ for every $j\neq i$. If $\frac{x_i}{1}\not\in \mathfrak m_iM_{\mathfrak m_i}$ for some $i$ we are done, so suppose $\frac{x_i}{1}\in\ m_iM_{m_i}$ for every $i$. I don't know how to go on, could you help me? What are the convergent sequences in the cofinite topology I consider the co-finite topology on $\mathbb{R}$ that is $$\{G\subset \mathbb{R}, card(\mathbb{R}\setminus G)&lt;+\infty\}\cup \{\emptyset\}$$  What are the convergent sequences in this space .  thank you I have had a question since childhood.  Why do we always get circular waves (ripples) in water even when we throw irregularly shaped object in it? Getting command-not-found working under zsh Solving Keplerian two-body problem numerically? I'm trying to solve the two-body problem numerically, setting up G, m1 and m2 =1.0.  The masses are placed at the positions -10 and 10 respectively along the x-axis and gave them both 0 on the y-axis. I am having some real issue with the initial conditions fitting for a keplerian orbit with a given eccentricity (e=0.9)! Also how would the initial condition change for different mass ratios? Why I can't edit "Your Communities" list in stackexchange.com and Area 51? I can edit &quot;YOUR COMMUNITIES&quot; in the upper left drop-down menu from any of my communities: (e.g. )    But in  portal there's no &quot;edit&quot; link:    Why is that and how can I edit the list in  portal? In this MWE, I want to obtain bold letter for the letter "H" (compare the two "H") :  \documentclass[10 pt]{beamer} \usetheme{default} \usepackage{lmodern} % load a font with all the characters \usepackage{fontspec} \usepackage{cmbright} \SetSymbolFont{largesymbols}{normal}{OMX}{iwona}{m}{n} \usepackage{amsmath}%loads amsmath that should go before unicode-math \usefonttheme{professionalfonts} \defaultfontfeatures{Mapping=tex-text}  % This seems to be important for mapping glyphs properly  \begin{document} \begin{frame} \[ \mbox{First bold H : }\|x\|_{\mathbf{H}},\; \mbox{Second bold H : }\mathbf{H}  \] \end{frame} \end{document}   but I don't know how doing it. THe "H" produced by this MWE is tiny but no bold effect. If I use      \SetSymbolFont{largesymbols}{normal}{OMX}{iwona}{m}{n}   I obtain bold tiny "H" but the font used still not the same. Ocean modifier and foam data export? It is there any way to export the foam data generated from ocean modifier to use it in other render engine, like LuxRender? The manual says that the foam data is stored as vertex color data, but there isn't a way to access the vertexColor data. I know that can be accessed from Cycles from attribute's node. LuxRender supports vertex color and I tried to bake the texture to vertexColor and an image but only get a plain black texture. For an affine connection $\nabla$, prove the curvature R  $R(X,Y,Z,\alpha)=\alpha(\nabla_X \nabla_Y Z - \nabla_Y \nabla_X Z -\nabla_{[X,Y]}Z)$  with $X,Y,Z$ vector fields and $\alpha$ a co-vector, is a tensor.  So I realise the aim is probably to show that each of the three terms in the expression for $R$ are tensors themselves as then the result will obviously follow. However, I'm not too sure how to show each of these terms are tensors. Do I need to expand out each covariant derivate to get a bunch of connection coefficients and then see some cancellations? Still though, I'm not too sure what I'll want to see after all of this so that I can say "…therefore $R$ is a tensor".  Also, very much related to the question, I'm a bit confused with the difference between  $\nabla_Y Z$ $\space \space $ and $\space \space $  $\nabla_{\mu}\omega$.  The second one I know as the covariant derivative of a 1-form, but what is meant by the covariant derivate of a vector $\textit{field}$? As in, what's the difference between the $\nabla_Y$ and $\nabla_{\mu}$?  Edit: In answering this last question, I have realised that $\nabla_YZ=Y^{\mu}\nabla_{\mu}Z^{\nu}$ and $\nabla_{\mu}\omega=\nabla_{\mu}\omega_{\nu}$. Let $f(z)=\frac{1}{(z-1)(z-2)}$ and $g(z)=\frac{z}{(z-1)(z-2)}$. Let $\gamma$ be the circle of radius 4 centered at the origin and traveled once in the counterclockwise direction. Let $A=\{ z \in \mathbb{C}: |z|&gt;3 \}$  1) I need to show there is no analytic function $G: A \to \mathbb{C}$ such that $G'(z)=g(z)$ for all $z$ in $A$.   2) I also need to show that there is an analytic function $F:A \to \mathbb{C}$ such that $F'(z)=f(z)$ for all $z$ in $A$.  Do I have to integrate to find such function? Use Objects.hash() or own hashCode() implementation?