JQuery - How to use the return value of an ajax call outside that ajax call
How do I return the response from an asynchronous call?
Looking for Space Exploration Book which is collection of different sub-stories The Book is about an earthship exploring the frontiers that I read as a kid (80's). All the stories are told by the same character but different encounters and events.    The first story is about the crew exploring the planet in a number of separate ships when one of them is taken over by a telepathic alien. As the ship returns however the surprise is sprung on the alien that the Mother ship is Computer controlled. Another is the ship shrinking and then finding after its shrunk beyond the atom that it comes back in as gigantic compared to the Universe in a closed loop.   Hopefully that's enough to trigger a memory. Probability of 3 people in a room of 30 having the same birthday I have been looking at the birthday problem (http://en.wikipedia.org/wiki/Birthday_problem) and I am trying to figure out what the probability of 3 people sharing a birthday in a room of 30 people is. (Instead of 2).  I thought I understood the problem but I guess not since I have no idea how to do it with 3. Direction of $d\mathbf{l}$ A solid sphere has charge $q$ and radius $R$. Find the potential at a point a distance $r$ from the center of the sphere where $r&gt;R$, using infinity as the reference point.  My attempt:  From Gauss' theorem we may deduce that $\displaystyle\mathbf{E}=\frac{1}{4\pi\epsilon_0}\frac{q}{r'^2}\hat{\mathbf{r}}$ where $r'$ is the distance of an arbitrary point from the center of the sphere provided $r'&gt;R$.  $V=-\int_\infty^\mathbf{r}\mathbf{E}\cdot d\mathbf{l}$  My question: What is $d\mathbf{l}$? Since we are traversing in the direction opposite to $\hat{\mathbf{r}}$, I think it should be $-dr'\hat{\mathbf{r}}$. But when I use it to find $V$, I get a sign error. Please help! Make all footnotes numbered subsequently, but one with a symbol Why is a conservative force defined as the negative gradient of a potential? I'm learning about work in my dynamics class right now. We have defined the work on a particle due to the force field from point A to point B as the curve Integral over the force field from point A to B. From math I know that if a vector field has a potential, we only need to evaluate the potential at point B minus the potential at point A to get the result of the curve Integral. In the text that I'm reading, it's explained that if the integral over a force-field is path-independent, then the force field $F = -{\rm grad}(V)$, where $V$ is the potential. Why is it defined as the negative gradient? Doesn't one determine the potential from $F$ mathematically. Why do we impose the sign on the potential? How can I visualize the file system usage on Windows? If gravity isn't a force, then why do we learn in school that it is? UK Visa has been refused for false document Lens upgrade paths (sub $1000) for the EF-S 18-55mm IS kit lens for Canon APS-C cameras [S]he has the ears of a ...? Often, when overheard from far away, I find myself saying/thinking:     [S]he has the ears of a hawk!   Which doesn't really make sense as hawks aren't particularly well known for their sense of hearing.  Is there a common saying, equivalent to "eyes of a hawk", relating to someone's sense of hearing? What is the fastest way to create a list of directories specified in a file? I have a text file, "foo.txt", that specifies a directory in each line:  data/bar/foo data/bar/foo/chum data/bar/chum/foo ...   There could be millions of directories and subdirectories What is the quickest way to create all the directories in bulk, using a terminal command ?  By quickest, I mean quickest to create all the directories. Since there are millions of directories there are many write operations.   I am using ubuntu 12.04.  EDIT: Keep in mind, the list may not fit in memory, since there are MILLIONS of lines, each representing a directory.  EDIT: My file has 4.5 million lines, each representing a directory, composed of alphanumeric characters, the path separator "/" , and possibly "../"  When I ran xargs -d '\n' mkdir -p &lt; foo.txt after a while it kept printing errors until i did ctrl + c:  mkdir: cannot create directory `../myData/data/a/m/e/d': No space left on device  But running df -h gives the following output:  Filesystem      Size  Used Avail Use% Mounted on /dev/xvda        48G   20G   28G  42% / devtmpfs        2.0G  4.0K  2.0G   1% /dev none            401M  164K  401M   1% /run none            5.0M     0  5.0M   0% /run/lock none            2.0G     0  2.0G   0% /run/shm   free -m   total       used       free     shared    buffers     cached Mem:          4002       3743        258          0       2870         13 -/+ buffers/cache:        859       3143 Swap:          255         26        229   EDIT: df -i  Filesystem      Inodes   IUsed  IFree IUse% Mounted on /dev/xvda      2872640 1878464 994176   66% / devtmpfs        512053    1388 510665    1% /dev none            512347     775 511572    1% /run none            512347       1 512346    1% /run/lock none            512347       1 512346    1% /run/shm   df -T  Filesystem     Type     1K-blocks     Used Available Use% Mounted on /dev/xvda      ext4      49315312 11447636  37350680  24% / devtmpfs       devtmpfs   2048212        4   2048208   1% /dev none           tmpfs       409880      164    409716   1% /run none           tmpfs         5120        0      5120   0% /run/lock none           tmpfs      2049388        0   2049388   0% /run/shm   EDIT: I increased the number of inodes, and reduced the depth of my directories, and it seemed to work. It took 2m16seconds this time round. Most incarnations of The Hulk I've seen or read about state that he is as strong as he needs, basically meaning that there is no limit to how strong he can get.  Is there any canon regarding this? Have we seen the upper limit of the Hulk's strength? Custom setting Setting type not visible Crossfading Video AND Audio with ffmpeg This Super User answer  has got me so far, but now that I have tried many solutions and seen every SO link out there, it's time to ask you all for help.  I am trying to crossfade 2 videos that are 10 seconds each in ts format with audio and video at the same time.   The steps are:   Add complex filter black screen Fade out video 1 after 9 seconds, with 1 second fade duration Fade in video 2 at 9 seconds, with 1 second fade duration Trim black filter output to 19 seconds   This works fine for just video alone, but when I attempt to add audio, I can't get past this error message:     Output pad "default" with type audio of the filter instance "Parsed_asetpts_4" of asetpts not connected to any destination   It appears I'm not connecting the audio output properly. I think I need to alter the [over] lines to include audio. But how do I do this?  `ffmpeg -i vid1.ts -i vid2.ts -f lavfi -i color=black -filter_complex \ "[0:v]format=pix_fmts=yuva420p,\ fade=t=out:st=9:d=1:alpha=1,setpts=PTS-STARTPTS[v0];\ [0:a]\ afade=t=out:st=9:d=1,asetpts=PTS-STARTPTS[a0];\ [1:v]format=pix_fmts=yuva420p,\ fade=t=in:st=0:d=1:alpha=1,setpts=PTS-STARTPTS+9/TB[v1];\ [1:a]\ afade=t=in:st=0:d=1,asetpts=PTS-STARTPTS+9/TB[a1];\ [a0][a1]amix=inputs=2;\  [2:v]scale=720x406,trim=duration=19[over];\ [over][v0]overlay[over1];\ [over1][v1]overlay=format=yuv420[outv]" -vcodec libx264 -y -map [outv] final.ts` I use the Stack Exchange sites very often to find solutions to problems and help me with decision-making.  In some sites I have asked question and received answers, and I have more than 15 reputation. On Stack Overflow I have always found answers to my questions and never needed to post a question (avoiding duplicate questions). However, I would like to vote for the answers that helped me but I do not have the ability to do that, due to low reputation.  Posting a question or answering an answer on each site seems like the only way to get enough reputation.  Since I have no input to give in these areas unless they will be counted as duplications, many answers that I have already used are missing my vote.  I suggest to take into account all of the reputations from all Stack Exchange sites for voting, or thinking about a different way to allow votes. My java code has an obvious error. Why does it compile and run? What is a field, really? There was a reason why I constantly failed physics at school and university, and that reason was, apart from the fact I was immensely lazy, that I mentally refused to &quot;believe&quot; more advanced stuff until I understand the fundamentals (which I, eventually, never did). As such, one of the most fundamental things in physics that I still don't understand (a year after dropping out from the university) is the concept of . No one cared to explain what a field actually is, they just used to throw in a bunch of formulas and everyone was content. The school textbook definition for a field (electromagnetic in this particular case, but they were similar), as I remember it, goes like:  An electromagnetic field is a special kind of substance by which charged moving particles or physical bodies with a magnetic moment interact.  A special kind of substance, are they for real? This sounds like the authors themselves didn't quite understand what a field is so they decided to throw in a bunch of buzzwords to make it sounds right. I'm fine with the second half but a special kind of substance really bugs me, so I'd like to focus on that. Is a field material? Apparently, it isn't. It doesn't consist of particles like my laptop or even the light. If it isn't material, is it real or is it just a concept that helps to explain our observations? While this is prone to speculations, I think we can agree that in scope of this discussion particles actually do exist and laws of physics don't (the latter are nothing but human ideas so I suspect Universe doesn't &quot;know&quot; a thing about them, at least if we're talking raw matter and don't take it on metalevel where human knowledge, being a part of the Universe, makes the Universe contain laws of physics). Any laws are only a product of human thinking while the stars are likely to exist without us homo sapiens messing around. Or am I wrong here too? I hope you already see why I hate physics. Is a field not material but still real? Can something &quot;not touchable&quot; by definition be considered part of our Universe by physicists? I used to imagine that a &quot;snapshot&quot; of our Universe in time would contain information about each particle and its position, and this would've been enough to &quot;de&quot; it but I guess my programmer metaphors are largely off the track. (Oh, and I know that the uncertainty principle makes such (de)serialization impossible — I only mean that I thought the Universe can be &quot;defined&quot; as the set of all material objects in it). Is such assumption false? At this point, if fields indeed are not material but are part of the Universe, I don't really see how they are different from  except for perhaps a more geeky flavor. When I talked about this with the teacher who helped me to prepare for the exams (which I did pass, by the way, it was before I dropped out), she said to me that, if I wanted hardcore definitions,  a field is a function that returns a value for a point in space.  Now this finally makes a hell lot of sense to me but I still don't understand how mathematical functions can be a part of the Universe and shape the reality. Are there good alternatives to "making the best of a bad situation?" Life is full of adversity, and people facing challenging life circumstances have to find a way to cope. I'm interested in single words, phrases, or idioms that capture coping strategies. For example:     Jane's job was absurdly repetitive and oppressive, but for her family, she tried to make the best of a bad situation.   Are there good alternatives to the coping strategy of making the best of bad situation?   Clarification: I am looking for alternatives, especially idioms, that don't involve words like good and bad. Can't we compute $\lim_{n \to \infty}\frac{1+ \cdots +n}{n^2}=\lim_{n\to\infty}\frac{1}{n^2}+\cdots +\lim_{n\to\infty}\frac{n}{n^2}=0$? I just learned the definition of limits, and I learned that if $\{a_n\}, \{b_n\} $ converges, then $$\lim_{n\to \infty} (a_n+b_n)=\lim_{n \to \infty} a_n+\lim_{n \to \infty}b_n$$ holds.  And my teacher said that $\lim_{n \to \infty}\frac{1+2+3+ \cdots +n}{n^2}=\lim_{n\to \infty}\frac{\frac{n(n+1)}{2}}{n^2}=\frac{1}{2}$.  But can't we compute like  $$\lim_{n \to \infty}\frac{1+2+3+ \cdots +n}{n^2}=\lim_{n\to\infty}\frac{1}{n^2}+\lim_{n\to\infty}\frac{2}{n^2}+\lim_{n\to\infty}\frac{3}{n^2}+\cdots +\lim_{n\to\infty}\frac{n}{n^2}=0+0+\cdots+0=0$$? Got ransomware and Shadow explorer doesn't work