Prefer fulfilling some requests over others
Best practice for Rails App to run a long task in the background?
The Ubuntu installer does not allow me to install on NTFS partitions, but certain circumstances requires me to do so. Is it possible? Proof of a formula involving Euler's totient function: $\varphi (mn) = \varphi (m) \varphi (n) \cdot \frac{d}{\varphi (d)}$ The third formula on the  states that $$\varphi (mn) = \varphi (m) \varphi (n) \cdot \dfrac{d}{\varphi (d)} $$ where $d = \gcd(m,n)$.  How is this claim justified?  Would we have to use the Chinese Remainder Theorem, as they suggest for proving that $\varphi$ is multiplicative? In the experiments for photoelectric emission, the light is incident on one face of the emitting plate, for example the anode, when determining the stopping potential. The electrons are emitted by this face of the plate. Why are the electrons emitted in the direction of the incident light, and not opposite to it?  I have read a little about photons (the key words being, a little), and from what i gather, they have an intrinsic momentum $p=h/\lambda$, which is transferred entirely to the particle that absorbs it (along with the energy $h\nu$). This should imply that the electrons try to move further into the cathode, and not escape it! What is the fault in the reasoning?  Thanks! How fast a (relatively) small black hole will consume the Earth? This question appeared quite a time ago and was inspired, of course, by all the fuss around "LHC will destroy the Earth".   Consider a small black hole, that is somehow got inside the Earth. Under "small" I mean small enough to not to destroy Earth instantaneously, but large enough to not to evaporate due to the . I need this because I want the black hole to "consume" the Earth. I think reasonable values for the mass would be $10^{15} - 10^{20}$ kilograms.   Also let us suppose that the black hole is at rest relative to the Earth.  The question is: How can one estimate the speed at which the matter would be consumed by the black hole in this circumstances? Why doesn't pressing enter return '\n' to getch()? #include &lt;stdio.h&gt; #include &lt;conio.h&gt; main() {     char ch,name[20];     int i=0;     clrscr();     printf("Enter a string:");     while((ch=getch())!='\n')     {         name[i]=ch;         i++;     }     name[i] = '\0';     printf("%s",name); }   When I give "abc" as input and if I press enter it's not working. Can anyone let me know why the condition ch=getch() != '\n' is not becoming false when I press enter? I have also observed that ch is taking \r instead of \n. Kindly let me know. Thanks Explaining Infinite Sets and The Fault in Our Stars In watching The Fault in Our Stars I could not help but cringe at a line that flew in the face of mathematics and subsequently ruined the movie for me:     "There are infinite numbers between 0 and 1. There's .1 and .12 and .112 and an infinite collection of others. Of course, there is a bigger infinite set of numbers between 0 and 2, or between 0 and a million. Some infinities are bigger than other infinities." - John Green   While walking out of the theater I tried to explain to my friends why there were, in fact, exactly the same amount of numbers between 0 and 1 as 0 and 2, but Cantor and bijective functions are not great learning tools to English majors.  Does anybody have an eloquent or elegant way to enumerate this phenomenon using an example accessible to those not familiar with advanced mathematics? If a normal subgroup $N$ of order $p$($p$ prime) is contained in a group $G$ of order $p^n$,then $N$ is in the center of $G$. If a normal subgroup $N$ of order $p$($p$ prime) is contained in a group $G$ of order $p^n$,then $N$ is in the center of $G$.   I want to use induction to prove this:  It is trivial when $G=p(n=1)$, assume $G=p^n$, $N$ is a normal subgroup in $G$ with order $p$. Since $G$ is p-subgroup, $G$ has a normal subgroup $H$ with order $p^{n-1}$,according to assumption, $N \subset C(H)$. But I don't know how to go on, is $C(H)=C(G)$?Can induction work in this case? How do I edit my profile? This is probably a noob question, but I forgot how to edit my profile.   Can anyone help me? There is no visible button for me. How to set mount point of boot partition to /boot/efi? Why do I get the same result with rand() every time I compile and run? This is my first question.   Let $a_1, a_2,\ldots, a_k$ be natural numbers $\leq n$ with $m$ prime factors.  Let $p_1, p_2, \ldots, p_r$ be the prime numbers $\leq n$.   Let $$C_{m,n} = \frac{\sum_{i=1}^{k}a_i}{\sum_{i=1}^{r}p_i}$$ Does the following limit exist when $m\geq 2$? Obviously, when $m=1$,  $C_{1,n}=1$.  $$\lim_{n\to \infty} C_{m,n}$$  I have some guesses but not defendable enough.  My best,  The FM. How can I change the Windows 7 Logon Screen wallpaper? Write a formula in an Excel Cell using VBA I'm trying to use VBA to write a formula into a cell in Excel. My problem is that when I use a semicolon (;) in my formula, I get an error:     Run-time error 1004   My macro is the following :   Sub Jours_ouvres()     Dim Feuille_Document As String     Feuille_Document = "DOCUMENT"             Application.Worksheets(Feuille_Document).Range("F2").Formula = "=SUM(D2;E2)"     End Sub Seeking Symbology for Interactive Mapping? When a user clicks on a map what should they expect to see?   I would say a symbol for where they clicked.  A pushpin seems to be the most accepted icon for generic data. Google has pushed the upside down tear drop.   What are other ideas/options and is there a place for finding professional gis oriented icon packs?  I ended up creating this,     This just popped up from the guys at map box. Clean word choice - realize notice find out figure out I am looking for an app that can monitor my C: (system) drive and find which program is creating a folder, with the rather generic name TEMP1\, on that drive.  I wouldn't mind if it could hook the creation of files too – as there a couple of files created as well (quite probably from another process). Google does not help me, as the names of those files are a bit generic too (not as TEMP1 though – dvmaccounts.ini and dvmexp.idx).   The problem is that every time I delete those, they are recreated on startup, so the utility I'm searching must start up on boot and also start fast. It should also be really clever, as my C: drive is huge. How can I create and extract zip archives from the command line? How do I make ditto marks? Constructing a continuous distribution to match $m$ moments What is a one-word synonym for "science lover"? I'm searching for a one-word synonym for "science lover". In my case, I love science and I self study it, but I never got a degree in Physics or Chemistry or any of these related subjects (except computer-science). But I enjoy experimenting stuff and see what's going on.  So, what would be a one-word good alternative for "science lover"?  The best one I found is learner, but that's more general I guess. Scientist is probably too much in my case. I saw sciencophile in another post, but I don't really like it–it sounds too complicated.