Wavelength of a particle
What would be the associated wavelength of the particle if its velocity is zero?
The "Select your next badge" dialog box is not displaying correctly. It looks like this:    Freehand circles, as requested:    It seems to be an issue with box-sizing, because when it's content-box, it looks fine. I think the width and height rules for .popup-badges .all-badge-progress .badge-progress should be increased a little, for example:  .popup-badges .all-badge-progress .badge-progress {   width: 214px;   height: 96px; }   Tested on the latest Chrome and Firefox on Linux Mint. How to make equally sized windows in corners of the screen? Persistent Network Configuration using KVM and libvirt Calculate which day of the week a date falls in using modular arithmetic In  the main character (he is a mathematician) calculates the day of the week of someone's birthday (19/07/1992 is Sunday). I know (very) basic modular arithmetic but I can't figure out how to do it. Can someone point me to the right direction? It seems fun to do. Fish vs Fishes for plural use Now, I encountered a sentence in a text book, saying     Many fish are specially adapted to live only in certain places.   I know that plural of the word fish can be fish as Merriam says    But wouldn't it someway or somewhat sound unusual or "too unique"?  Is it only to me? Updates for a private plugin? If I write a private plugin, is there any way to use the WordPress auto-update mechanism to update it?  I want to encapsulate the functionality, but it's specific to my own 5 or so blogs, so it's not a good candidate for the public plugins resource. But I love the easy-updating mechanism.  Is there a way to do this? How to replace ${} placeholders in a text file? What animal is a “weefil”? What animal is depicted in this image labelled “weefil”? Gaussian/Normal plots from a data distribution in scientific notation I am new to Tex and trying to plot a gaussian distribution from a set of values. I have the following set of values and would like to plot a normal distribution for them.  2.9954E-09  3.1314E-09  3.1155E-09  3.0940E-09  2.8861E-09  3.0875E-09  2.9685E-09  3.0532E-09  2.9003E-09  3.0931E-09  I have tried using the sample code but can't figue out where to input my values.   \begin{tikzpicture} \begin{axis}[   no markers,    domain=0:6,    samples=10,   ymin=0,   axis lines*=left,    xlabel=$x$,   every axis y label/.style={at=(current axis.above origin),anchor=south},   every axis x label/.style={at=(current axis.right of origin),anchor=west},   height=5cm,    width=11cm,   xtick=\empty,    ytick=\empty,   enlargelimits=false,    clip=false,    axis on top,   grid = major,   hide y axis   ]   \addplot [very thick,cyan!50!black] {gauss(x, 3, 1)};  \pgfmathsetmacro\valueA{gauss(1,3,1)} \pgfmathsetmacro\valueB{gauss(2,3,1)} \draw [gray] (axis cs:1,0) -- (axis cs:1,\valueA)     (axis cs:5,0) -- (axis cs:5,\valueA); \draw [gray] (axis cs:2,0) -- (axis cs:2,\valueB)     (axis cs:4,0) -- (axis cs:4,\valueB); \draw [yshift=1.4cm, latex-latex](axis cs:2, 0) -- node [fill=white] {$0.683$} (axis cs:4, 0); \draw [yshift=0.3cm, latex-latex](axis cs:1, 0) -- node [fill=white] {$0.954$} (axis cs:5, 0);  \node[below] at (axis cs:1, 0)  {$\mu - 2\sigma$};  \node[below] at (axis cs:2, 0)  {$\mu - \sigma$};  \node[below] at (axis cs:3, 0)  {$\mu$};  \end{axis}  \end{tikzpicture}   Your assistance will be highly appreciated. Thanks! Height of Water 'Splashing' Suppose from a height $H$, I throw a ball of mass $M$ and radius $R$ with initial velocity $u$ into a pool of depth $x$ having a liquid with density $\rho$ and coefficient of viscosity $\eta$.  Upto what height will the Water Splash?   This may be a silly question! (Source : my brain) Assume every condition to be identical with no air resistance. Feel free to assume any other parameters if needed.  P.S. $\rightarrow$ I've see similar questions but some of them want an exact answer and some are not so direct while some are incomplete questions...  Small Note : We do not have to consider the highest 'single' drop... Just assuming almost every water droplet jumped upto a height $h$. Ideal conditions...  Feel free to assume the liquid as WATER if required! Metric $d(x,y)=\frac{|x-y|}{\sqrt{1+x^2}\sqrt{1+y^2}}$ on $\mathbb{R}$ How to run an executable on boot and keep it running? I have an executable build from a ndk-build program. I want to run it on a rooted Android device. How much is the possibility that Android will kill my executable?  Using adb shell, I am able to execute my executable using following commands:  adb push executable /sdcard adb shell device:/ $ su device:/ # cd /system device:/system # mount -o rw,remount /system device:/system # mv /sdcard/executable . device:/system # ./executable   My requirement is to run this executable on device boot.  I have tried following:   Write ./executable in init.rc.   On reboot init.rc reset to its original contents. I figured out that Magisk done this.  Write commands in /system/etc/init/bootstat.rc   ./executable service custom /system/executable on boot  ./system/dhandler/diag_revealer    None of the above thing is working. When can I use a forward declaration? What is the process for a moderator to request reinstatement or appeal a removal? "need + verb-ing" vs "need + [to be] + verb-ed" 1 That sofa needs cleaning again. 2 That sofa needs to be cleaned again.  Which of the above senteces sounds more natural? And, is &quot;to be&quot; always needed in structures like 2, as, for example, in:  2/a You need your head examined. 2/b You need your head to be examined. I understand the proof that  $$Var(aX+bY) = a^2Var(X) +b^2Var(Y) + 2abCov(X,Y), $$  but I don't understand how to prove the generalization to arbitrary linear combinations.  Let $a_i$ be scalars for $i\in {1,\dots ,n}$ so we have a vector $\underline a$, and $\underline X = X_i,\dots ,X_n$ be a vector of correlated random variables. Then $$ Var(a_1X_1 + \dots a_nX_n) = \sum_{i=1}^n a_i^2 \sigma_i^2 + 2 \sum_{i=1}^n \sum_{j&gt;i}^n a_i a_j \text{ Cov}(X_i,X_j)$$  How do we prove this? I imagine there are proofs in the summation notation and in vector notation? Wizard sickness I remember in an interview, or during a Q&amp;A, Rowling stating that Wizards live longer than Muggles. This got me thinking about Wizard deaths in general, and then deaths being attributed to illness.  So, I ask, has there ever been a Wizard, that has died from something like cancer? Is there anything, even briefly mentioning a Wizard becoming ill?  And finally, are there any illnesses that are exclusive to Wizards? Why would a JavaScript variable start with a dollar sign? I quite often see JavaScript with variables that start with a dollar sign. When/why would you choose to prefix a variable in this way?  (I'm not asking about $('p.foo') syntax that you see in jQuery and others, but normal variables like $name and $order) Intuitive proof of $\sum_{k=1}^{n} \binom{n}{k} k^{k-1} (n-k)^{n-k} = n^n$ Is there an intuitive way, though I am not sure how to find a conceptual proof either, to establish the following identity: $$\sum_{k=1}^{n} \binom{n}{k} k^{k-1} (n-k)^{n-k} = n^n$$ for all natural numbers.  I am thinking about binomial formula $$\sum_{k=0}^n\binom nk x^{n-k}y^k=(x+y)^n$$ but I'm not sure how to use it.  I find this problem tantalizing because it looks as if there should be some sort of intuitive way so that is why I share it here. I am looking for an answer like  if possible. Can you find one? How to install TP-LINK Archer T4U driver? I bought the wireless adapter to use with a computer without internet access but I can't figure out how to install it with just a USB with the driver on it. I've read a few articles on how to install the driver but they all require me to have internet access and I don't have internet. I'm completely new to Ubuntu. If you can help that would be great. Thanks!  Ps: I have the latest version of Ubuntu as of 7-5-16.