I've got a silly question, sorry for that. I know, that we probably have no the right answer and the current answer could be "that's evolution, external conditions". I'd like to speculate, why most of mammals (for ex.) and people especially are symmetric? I know, that we are not completely symmetrical, but anyway.  Thanks a lot.
Mammals, reptiles, arachnids, insects, etc are all as far as I am aware symmetrical in appearance.  Take a human for instance, make a line from the top of our head right down the middle. However, internally it is not the same. Our organs excluding the kidneys, lungs, reproductive organs, etc are not symmetrically placed in our body.   Why do we not have an even number of each organ so it can be placed symmetrically? If we have a single organ why is it not placed in the middle like the brain or bladder is for instance? Is there some evolutionary advantage that led to this setup?
I just failed these   in First Post, I read the question and thought it seemed reasonable but the user was deleted so to be on the safe side I clicked add comment and I failed the audit.  I'm not sure why adding a comment would be considered a negative action, is the correct option to click No Action Needed or edit?  What was I supposed to do in this situation?  Adding a comment should not be a review audit fail. Where can I get an Ubuntu Installation CD/DVD/USB? I need to upgrade my existing Ubuntu system, and I also want to install Ubuntu on a new laptop.  I would like to have an installation CD or DVD to do both of these.  Where exactly I can order or request an Ubuntu installation CD/DVD/USB? I am designing a hobby project that will run on a battery so I am trying to reduce power consumption. The SoC I am using has the ability to go into a deep sleep mode where it consumes very little power, and then can be interrupted by a falling edge on a pin.  I want to generate a high-low-high pulse when the state of a reed switch changes in either direction. I have been reading a lot and it seems that a one-shot monostable circuit can be built from a couple of transistors and an RC circuit to generate an output pulse when an edge is detected. I understand how that works. However, I can't figure out the best way to also pulse on the opposite edge.  One thought, was to just combine two one-shots that are configured to trigger on rising and falling edges respectively, and use the transistors at the output to pull the common pull-up low (kind of like a NOR gate).  Since I am a hobbyist, I am mostly using passive components. What is the "real" way of doing this in a low-power configuration using logic devices?  Edit: I figure I should mention something about the timing requirements. Normally the reed switch will be either open or closed for many seconds at minimum before changing states.  Edit: Here is an example of the circuit I was using for detecting only the falling edge:    And here is the ~20ms pulse it was producing for ~200ms button press simulating the reed switch (Channel 1 is Vbe for T1 and Channel 2 is measured at RST): What happens to the second Marty at the end of Back to the Future? In  (the original movie), Marty comes back from 1955 10 mins early to prevent Doc from being shot (which he fails at). He then rolls up to the Lone Pine Mall and sees himself hit 88 mph and shoot back to 1955 (again). Marty then carries on with this life as usual. What happens to the Marty that goes back to 1955 at the end of the film?  This obviously is a recursive problem where it would create another timeline and Marty would keep coming back 10 mins early to view another Marty zip back to 1955? Add year to question and answer dates How to allow Page Up in GNU Screen? I use Vim to edit text files on Linux. Commonly I connect to remote Linux machines using PuTTY from Windows.  I use GNU Screen commonly as well.  When using Vim inside Screen I am unable to use the Page Up key because Screen interprets it as a command to start copy mode.    I would like to use Page Up for its regular up-paging functionality.  How can I configure Screen to do this? No group of order 400 is simple I installed Redhat 6 x86_64. I am using the Network connection screen to set a static IP address like below (I want two PC's in my house to see each other: one Redhat PC and one Mac)   192.168.0.5   255.255.255.0   192.168.0.1     When I run ifconfig it displays only lo and virbr0 information. I don't know what these items are (I don't really know much about network settings).   When I try ifconfig -a it displays eth0, lo, sit0 and virbr0. The information for  eth0 is as follows:   Link encap : Ethernet HWaddr 90:2B:34:74:05:30 BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:192 errors:0 dropped:0 overruns:0 frame:0 TX packets:6 errors:0 dropped:0 overruns:0 frame:0 collisions:0 txqueuelen:1000 RX bytes 53811 (52.5 KiB) TX bytes:468 (468.0 b) Interrupt:29 Base address:0xc000   Could someone help me to point out if anything wrong with my setting or how to resolve this problem? Inspired by question :  When do I need to invoke \phantomsection?  In what condition is invoking \phantomsection necessary? Periodically, my MacBook Pro 17" stops recognizing my headphones. No amount of unplugging and replugging seems to help. The sound settings never show headphones as an output device. How can I fix this? The only thing I can find elsewhere on the Internet are people saying, "Reboot!" This works, but is impractical and annoying. Can an iOS user play with pc users? I have a Mac only, so I am not able to get Terraria through Steam. I was wondering if I can play Terraria on my iPad Mini with a friend who has it on his PC. I was wondering this, because I saw that Deepworld on iOS is compatible with the Mac version. How come unpolarized light does not undergo destructive interference? Sometimes I hear sentences that sound conditional to me, just because of the (unassertive) ordering of the words. I don't know if I can come up with a proper example. Consider this:          I'd be a lot better, had she stayed with me.        And I guess it's equivalent to this conditional form: If she had stayed with me, I would have been a lot better.  So, this is my question: In what ways can you make a sentence conditional without using conditional conjunctions (if, unless, etc)? And what are their equivalent conditional forms? Use biblatex and utf8 For my thesis, I use biblatex for the bibliography.  As seen , biblatex is not compatible, with \usepackage[utf8x]{inputenc}. It was reported as close but I still have the same problem with my version of bibtex (last one on archlinux ). I want to use the € symbol inside my report but it fails without utf8.  ! Package biblatex Error: Incompatible package 'ucs'.  See the biblatex package documentation for explanation. Type  H &lt;return&gt;  for immediate help.  ...                                                l.7 \begin{document}   Any idea idea how to fix ?  \documentclass{report}  \usepackage[utf8x]{inputenc} \usepackage{biblatex} \bibliography{includes/mybib}{}  \begin{document}  X said Y \cite{bib1}  \printbibliography  \end{document}   and the file mybib  @online { bib1,        title = {Refrence title},        author = {X},        url = {http://site.com/y}} Concrete Mathematics - The Josephus Problem I've been going through  and have a question on the inductive proof for the . Recurrent relation:  $J(1) = 1$ $J(2n) = 2J(n) - 1$ $J(2n+1) = 2J(n) + 1$  Closed form hypothesis:  $J(2^m + l) = 2l + 1$, for $m \ge 0$ and $0\le l&lt;2^m$  Inductive Proof (for the even case):  $J(1)=1$ $J(2^m+l)= 2J(2^{m-1}+l/2)-1=2(2l/2+1)-1=2l+1$  How do the authors get from $2J(2^{m-1}+l/2)-1$ to $2(2l/2+1)-1$? Can I use Minecraft PC textures and worlds in Pocket Edition? Now that I've discovered that I can host a , I'd like to know if is it possible to use the textures and maps of the PC version for the pocket version.  I'm planning to visit Peru and Machu Picchu. It would be really cool to entice them for the voyage by letting them play a  in their favourite video game. Unfortunately, this God of Deceit world looks really sophisticated. I don't believe the Pocket Edition would be able to play it. Ubuntu software not showing any software Missing abstract with amsart class I'm not very good at LaTeX but I've been using it to write my dissertation. Have just come to the end and trying to format everything correctly. Whenever I try to put my Abstract paragraph into the form \begin{abstract} (writing here) \end{abstract} and click play the whole abstract section just disappears. What am I doing wrong?  \documentclass[12pt]{amsart}  \begin{document}  \begin{abstract} (my abstract here) \end{abstract} \end{document} Proving $f' = - \frac{\partial{F}/\partial{x}}{\partial{F}/\partial{y}}$ I am trying to prove that, if $f:\mathbb{R}\rightarrow \mathbb{R}$ and $F:\mathbb{R}^2\rightarrow\mathbb{R}$ are differentiable, $F$ satisfying $F(x,f(x))=0$ and $\partial{F}/\partial{y}\ne 0$ then $$f'(x)=-\frac{\partial{F}/\partial{x}}{\partial{F}/\partial{y}}$$  This appears in a section on the chain rule for many-variables functions, but without knowing the details of $F$ I find it very hard to prove much about it.  To the best of my ability to reason about it, I suppose I could say  $$ \frac{\partial{F}}{\partial{x}}=\frac{\partial{F}}{\partial{x}}\frac{\partial{x}}{\partial{x}} + \frac{\partial{F}}{\partial{y}}\frac{\partial{y}}{\partial{x}}$$  but for more than one reason I doubt that what I have written is correct.  Yet I'm not exactly sure what's wrong about it, nor can I guess what else I could do.  I tried finding the partial with respect to $y$ but got nothing more useful looking than this.  I also tried writing out limit definitions and saw no useful path forward through that. Why do hard links exist?