Is stopping Ubuntu at HP Compaq PC by pressing shortly the computer power button OK?
Does Hard reboot damage my Ubuntu
How to ‘guess’ if a noun is countable or uncountable? It worked with the pre-installed Ubuntu, but after re-installing Ubuntu dual-boot with Windows 8.1, the WiFi is not working.  Is there a driver for this adapter that will work on Ubuntu 12.04? How do I run two isolated instances of firefox? I've added many PPAs using the add-apt-repository command. Is there a simple way to remove these PPAs? I've checked in /etc/apt/sources.list for the appropriate deb lines but they aren't there.   This is on a server system so a command line solution would be great! prevent user creating a duplicate node title how to prevent user creating a duplicate node title for a content type?  I already try uniqueness module () but it's only list out the duplicate content title but not return any error message when user save the new content. Any suggestion module or code? :) Get text from pressed button How to vertically align an image inside a div How do ability score improvements improve modifiers? First time player in a group figuring out things as we all go.  I just hit level four as a Ranger, and I get to improve one ability score of my choice by 2, or I can increase two ability scores of my choice by 1.  My first thought was Strength, as I've been rocking a score of 11 with a mod of +0 so far. But I read that Rangers use (wisdom mod + 10) for their spell casting modifier. Currently my wisdom is 13, with a mod of +1. If I increase either STR or WIS, will the modifier increase as well? How and why?  A Monk in our party went from 9 CON to 11 during their ability score improvement, and by doing so their modifier went from −1 to 0.  We're all pretty new, so between eight people we're currently sharing one book, and all trying to locate our own copies for later campaigns. That's making it… inefficient for us to learn these things quickly. Division rules for other number systems? How could we make the same division rules for other number systems, like in our decimal system: a number is divisible with 2 if it's last digit is 0,2,4,6,8, by 3 if the sum of digits is divisible with 3, and so on.  Can we do the same rules for g-based number systems too, where g is not 10, and greater than 1? Do not show the score for users during primaries I believe that showing the post score for nomination posts during primaries is a bad idea.  When I loaded the primaries page during the election, the first thing I saw was a post voted -1. This immediately colored my impression of the post. Reading his post didn't indeed make me wish he was a moderator, but at the same point I couldn't bring myself to click on the down arrow. He wasn't an awesome candidate, but he wasn't a -2 score candidate either. Actually, I kinda wanted to sympathy upvote instead.  I want to judge by myself whether a candidate is worth or not my +1. For some of those people I don't have an opinion already, and I want to form one on my own. I don't want game theory to kick in, I don't want to be tricked into sympathy upvotes.  Having those numbers in large print as the first thing I see about them honestly prevents me from doing so. I'd rather have their avatar there.     Some people on chat do not agree with me;  I imagine they'll post explaining why I want to be aware of their opinion while forming my own.      Regardless of the discussion here, if you do prefer to hide the scores as you vote, here's the jQuery oneliner that does just that:  $(".vote-count-post").hide() Completely uninstall an app on Lollipop I am having a problem with uninstalling apps on Android 5.0 (Nexus 5). I am developing an Android app, so I debug/run the app directly on my device. For production, I exported the same app with my keystore, uninstalled the debug APK that I ran earlier, tried to install the signed APK, and I got this error:      An existing package by the same name with a conflicting signature is already installed.   Is it because the bytecodes are still in the ART runtime? Anyone has any idea how to solve this? How can I reliably and accurately identify the passive voice in writing or speech? How can I reliably and accurately identify the passive voice in writing or speech? I'm not interested in advice about whether or not to use it yet... I just want to know for sure what it is, so that I don't look as stupid as . The disk that contains Ubuntu on my computer is 115GB in size.  When the disk was 114.7GBfull.  I started deleting some files here and there to free up around 5GB.  But I noticed the disk was 114GB filled again. I thought it was some cache or swap thingy so didn't give it much thought and went ahead and freed around 40GBby shifting some media files out of the disk.  I have a notification in an hour or so that the disk is full yet again!! 40GB!!! All gone!  So I debugged the problem down to the /var/log/syslog file which was initially definitely less than 20GB. I know this because /var folder was 17GB before I cleared the memory.  /var/log/syslog file is currently 55.9GB!  Could someone be so gracious to explain this anomaly? Is this a bug? Or am I affected with some malware or virus? Solenoid Driving Circuit I'm trying to drive a 12v (14W) solenoid and have problems figuring out the components for the driving circuit.  The solenoid draws about 1.166A and the MCU is being operated at 3.3V.  I've seen many driving circuits and they all look something like this:         &ndash; Schematic created using   My questions:   What datasheet parameters should I look for when designing this circuit? Is the IRF530PBF-ND a suitable MOSFET for driving this solenoid?    Also, how do I calculate R1's value?  I don't want to blindingly copy a circuit that may or may not work, I want to understand it.  Thank you so much in advance! Why are the rooting apps not working anymore? A couple years ago, it was easy to root any device: Install KingRoot, KingoRoot, or a similar app, hit the large ROOT button, and let it do the rest. After 5 minutes or so, a green "Root Succeeded!" prompt will pop up, and we can choose to keep the root app, or uninstall it and install a clean root manager app like SuperSU/Superuser.  How do they work? Why aren't they working anymore? And if they work, should I use them or not? Can a 64-bit OS run as a guest on a 64-bit VirtualBox host? Is it possible to run a 64-bit OS as a guest on a 64-bit machine with VirtualBox? I'm guessing it should be, but I'd like to make sure.  Do some virtualization technologies allow a single guest machine to use multiple cores? I guess it should be possible, but my VirtualBox open-source edition doesn't seem to do it. What I am working with: I am running my self-made Arduino board (in the sense that I use the Arduino bootloader and code editor) at 3.3V, and powered from a Lithium ion battery, which is USB-charged by a corresponding Microchip charger IC.  What I am trying to achieve: I want to measure battery capacity once every minute or so. I have an LCD attached, so the idea is that the overall setup lets me know how the battery is doing at a given moment. The datasheet of the battery has a voltage versus discharge-level curve, and so by measuring the voltage of the battery, I can estimate the remaining capacity (very roughly but enough for me!).  What I did:   (EDIT: Resistor values updated and P-MOSFET switch added based on @stevenvh and @Jonny's suggestions).  I connected a voltage divider from the battery V_plus, with the larger "portion" going to an analog-read-pin (i.e., ADC) on the Arduino/Atmega chip. The divider is 33 KOhm-to-10 KOhm, thus allowing measurement up to 4.1 Volts maximum of the Li-ion battery from my 3.3V level microcontroller. Also, using one of the I/O pins connected to an n-channel MOSFET, I can switch the current through the divider only when I need the measurement. Here is a rough schematic (updated for a 2nd time based on suggestions of @stevenvh and @Nick):     My question:   How is my current setup? My only constraints are: (1) I would like to make a rough measurement of the battery capacity based on the voltage reading, as described above. (2) I would like to prevent the voltage divider from interfering with my charging IC's reading of battery presence (in my original setup, the divider sometimes caused the IC to misread presence even when the battery was absent). Compute: $\lim_{x\to 0}\frac{\sqrt[m]{\cos(\alpha x)}-\sqrt[n]{\cos{(\beta x)}}}{x^2},\;m,n\in\mathbb N,\alpha,\beta\in\mathbb R$ Compute: $$\lim_{x\to 0}\frac{\sqrt[m]{\cos(\alpha  x)}-\sqrt[n]{\cos{(\beta x)}}}{x^2},\;m,n\in\mathbb N,\alpha,\beta\in\mathbb R$$   My attempt:  $$L=\lim_{x\to 0}\frac{\sqrt[m]{\cos(\alpha x)}-\sqrt[n]{\cos{(\beta x)}}}{x^2}=\lim_{x\to 0}\frac{\sqrt[m]{\cos(\alpha x)}-1+1-\sqrt[n]{\cos(\beta x)}}{x^2}\\\displaystyle=\lim_{x\to 0}\frac{\left(1+(\cos(\alpha x)-1)\right)^{\frac{1}{m}}-1-\left(\left(1+(\cos(\beta x)-1)\right)^{\frac{1}{n}}-1\right)}{x^2}$$  Transformed expression: $$-\frac{(1+(\cos(\alpha x)-1))^{\frac{1}{m}}-1}{\cos(\alpha x)-1}\cdot\frac{1-\cos(\alpha x)}{\alpha^2x^2}\alpha^2+\frac{(1+(\cos(\beta x)-1))^{\frac{1}{n}}-1}{\cos(\beta x)-1}\cdot\frac{1-\cos(\beta x)}{\beta^2x^2}\beta^2$$  I applied the standard limits from the table: $$\lim_{x\to 0}\frac{(1+x)^a-1}{x}=a\;\&amp;\;\lim_{x\to 0}\frac{1-\cos x}{x^2}=\frac{1}{2}$$ $$L=-\frac{1}{m}\cdot\frac{1}{2}\alpha^2+\frac{1}{n}\cdot\frac{1}{2}\beta^2=\frac{m\beta^2-n\alpha^2}{2mn}$$ Is this correct? Is it possible to decompose a hermitian and unitrary matrix $A$ into the sum of the Pauli matrix Kronecker products?   For example, I have a matrix 16x16 and want it to be decomposed into something like $$A =\sum_{i,j,k,l}h_{ijkl}\sigma_i\otimes\sigma_j\otimes\sigma_k\otimes\sigma_l$$ I can't find any clear explanation how it can be done. I found only this for two-dimentional case: Proving the Cauchy-Schwarz inequality by induction