I can't make bootable USB on 2008 iMac 2008 running El Capitan
How am I supposed to install El Capitan on a new SSD without recovery partition?
Electric shock - was I stupid, unlucky, or a combination of both? One of the double sockets in our garage needed replacing (damaged after a washing pole hit it) - a pretty trivial job that I'd done before. So I flipped the MCB for the ring main, used a non-contact voltage tester to check nothing was there, and set to work. I disconnected the old socket fine, and was lining the cables up to fit into the new socket when... ow.  My finger bridged the live and earth pins, and suffice to say the live wire was very much alive. Bar a few finger spasms I was fine fortunately, and believe me I realise I was very lucky in that respect (I'm in the UK, so that was 240V.) Before finishing the job I then shut off the entire property's electrics - I was taking no more chances.  Further inspection confirmed two things I immediately suspected at this point - the MCB in the garage (installed before we moved into the house) was shutting off power via the neutral, not the live, and the voltage tester was dodgy (I had tested it on the same socket earlier and it seemed fine, further testing showed it presumably had a loose connection internally and only worked sporadically.) Needless to say it's now in the bin, and an electrician has been called to sort the MCB and check the rest of the house for similar issues.  Unsurprisingly this has shaken me up a bit - I would say I'm a rather safety conscious person, and in this case thought I'd done all the checks properly (including taping over the relevant trip switch to ensure no-one flipped it back on while I was working.) In some ways I can't help feeling I was unlucky that the MCB was wired by a cowboy, in combination with the voltage tester failing in the way that it did, at the time that it did. However, I'm not one to solely blame tools - clearly some, if not most of the blame here lies with myself also.  So in short, what should I have done differently - and was I primarily being stupid, or really quite unlucky? We have some new hardware in our office which runs its own customized Linux OS.   How do I go about figuring which distro it's based on? Find the probability that a geometric random variable $X$ is an even number How to nest code within a list using Markdown Strange issue with the right side margin When I want to register an account with Gmail now, it says "Google will send a text message containing a verification code to your mobile phone."  I don't want to give Google my mobile phone number!!  How do I get around this? How to assign a function in Lua for a randomly generated numbers How to read a csv file and use the values as x and y points in blender? How can i use the value in column 'lon' and 'lat' as the position of my uv_sphere? For example,read the values from line 4, (116.4559081, 39.9139083), and make these 2 numbers as my uv_sphere x and y position in blender? and gives different colors for different mode, for example i have 4 modes in the csv , i want to make the uv sphere that represents the bus mode to be red, and subway to be green , rail to be blue and tram to be yellow., and use the row ['from'] and ['to'] to connect the nodes with a cylinder with x scale 0.5 , y scale 0.5 and the z scale with the value in ['length'] value. Eisenstein Criterion with a twist As opposed to the generic polynomial form for utilizing the Eisenstein Criterion ($a_nx^n+a_{n-1}x^{n-1}+\dots+a_0\in\mathbb{Z}[x]$ is irreducible in $\mathbb{Q}$) how do we prove that if $p$ is a prime, $x^{p-1}+x^{p-2}+\dots+x+1$ is irreducible over $\mathbb{Q}$? I want to fill a part of a picture with more or less evenly and randomly distributed circles which should not overlap. It would be okay if circles are only partly inside the shape.  The density should be like what you see on this page  with values 80-100. (But I do not need so many circles, 30 should be enough, I could repeat the pattern).   I cannot use a grid and "wobble" the circles a bit: The circles are too large and it simply does not look randomly.   Currently I am thinking about a random attempt: Get some random point, measure its distance to existing circles, either paint or throw the point away. Try 100 times and hope that you get the right number of circles (and that it does not take too long). But perhaps someone has a better idea.   The example draws the circles simply manually:  \documentclass{article} \usepackage{tikz} \usetikzlibrary{backgrounds} \begin{document}   \begin{tikzpicture}[framed,gridded,radius=0.5cm]  \draw[red](0,0) rectangle (5,5);   \draw (1,1) circle;   \draw (2.3,1.1) circle ;   \draw (4.5,0.8) circle ;   \draw (5.1,1.8) circle ;   \draw (0.4,3.3) circle ;   \draw (2.1,2.8) circle ;   \draw (3.8,3.5) circle ;   \draw (4.8,4.2) circle ;   \draw (0.8,4.9) circle ;   \draw (2.1,4.1) circle ;   \draw (3.8,2.0) circle ;   \draw (3.5,0.6) circle ;   \draw (3.0,5.0) circle ;      \draw (4.1,5.1) circle ;             \draw (0.9,2.1) circle ;  \end{tikzpicture}  \end{document} Fix SD card that cannot be formatted Relation between AB and BA Let $A$ and B be $n\times n$ matrices over a field $F$. Then prove or disprove  $(i)\, AB$ and $BA$ have same characteristic values.  $(ii)\, AB$ and $BA $ have same characteristic polynomial.  $(iii)\, AB$ and $BA $ have same minimal polynomial.  Proof of $(i)$   Let $c$ be an eigen value of AB and v be corresponding eigen vector. Then    AB(v)=cv,    B(ABv)=B(cv),    BA(Bv)=c(Bv),   this implies $Bv$ is an eigenvector of $BA$ corr. to eigen value $c$.  But this statement holds if $Bv$ is nonzero.  What if $Bv=0$?  $(ii)$ If $A$ is invertible then ($A$ inverse)$(AB)A= BA$, i.e. $AB $ and $BA$ are similar and hence have same charateristic polynomial.   Similar proof when $B$ is invertible.  But what if both $A$ and $B$ are not invertible?  I have no idea about $(iii)$.  Please help me to complete these proofs. Rotating image / marker image on Google map V3 Traveling with visa in my old passport My old passport in which an ECR was stamped,with passport expiry date in 2017.I got a Dubai visit visa on its passport number but later on as I was told that it'l be a problem for me to travel to Dubai so I got a new passport re-issued with ECNR with a new passport number.  So will it be a problem for me to travel or do I have to get my UAE visit visa details of my old passport number change to my new passport number? Does there exists an Isomorphism between $\mathbb{C}^* $ under multiplication with $\mathbb{C}$ under addition.  Attempt In my opinion It does not exists.  If there exists such an isomorphism say $\phi :\mathbb{C}^* \to \mathbb{C}$ then, from the fact that Isomorphism takes identity to identity we have $$\phi \left( 1 \right)=0$$  From the fact      Given $\phi:G \to H$ be an isomorphism, then For a fixed integer $k$ and a fixed group element $b$ in $G$, the   equation $x^k=b$ has the same number of solutions in $G$ as does   the equation $x^k=\phi\left(b\right)$ in $H$.   We have $x^4=1$ and $x^4=0$ must have same number of solutions, but the solutions to these equations are 4 and 1 only. I have read , but it was asked in the context of servers not desktops or notebooks.  If a good amount of RAM is installed on a notebook, say 8 GB, do we still need a swap space? The tablet functionality stops working after I wake my Lenovo Tablet from sleep mode (closing &amp; opening lit). The error message is "Tablet Serial Wacom Tablet (Lenovo X201) removed" (screenshot: ). In the system settings under input devices it states that "No tablet device is detected". Only a restart helps and the touch screen works again.  This error appeared only after upgrading from Kubuntu 12.04 to 14.04. In 12.04 the same error message appeared after waking from sleep mode, but then another followed that the tablet was activated again and it worked properly. Any ideas how this could be fixed? Could you help me finding some less colloquial equivalent to highlighted phrases of this speech Today I want to be able to give you some good tips on parallel parking. It's part of your road test. It's something you need to learn. For most new drivers it's real difficult, because they're not able to judge angles. And parallel parking is all about angles. I'll take you through a typical parking, I'll take you through how I teach it , and maybe that'll help you in passing your road test. The first thing you want to do is you want to pull over over and you want to stop alongside a parked car. Typically, an inspector will give you a command to pull over, stop next to the red or blue car. You're just going to pull over, put your blinker on to the right, and pull over even with that car.     taken from a series of videos teaching driving   Why did the man use  be able in his speech? What is the difference between be able and I would like to or I want ? I mean what the listener should make of  I want to be able to give you ...  . Why did not he say I want to give you... ?  When he says I'll take you through a typical parking , I get the meaning of take one through ,It means I am going to teach you , isn't it? But my real concern is what the second I'll take you through means, while saying I'll take you through how I teach it . Perhaps it doesn't mean I will teach you that how I teach it ! , does it? The man always says the first thing you want to do . Why does not he say the first thing you should do , the first thing you need to do ? What are the diffrences in meaning? Isn't it unnatural saying you want to do ? In the last sentence he says You're just going to pull over, is the use of going to just weakening would and will? I think here it means something else. I think it means you just want to or you just start I can enter U+0008 (backspace character) into a chat message I typed . I believe I tab-completed @rumtscho and fully typed @MarthaF (since she doesn't tab complete). However, other people tell me that a Unicode character was inserted into the message; I can't see it:  Originally, I abandoned this bug report for a lack of reproducibility. But on another machine, I can see the character and managed to reproduce it: press tab, then press backspace. It works anywhere in a message, not just in a @-ping. (Actually, it seems that you just need to un-focus the input box; clicking elsewhere then hitting backspace works, too)  First machine is Firefox 12 (Iceweasel) on Debian GNU/Linux AMD64, testing+unstable. No user scripts. Greasemonkey is installed, but disabled in the extension manager Second machine is Firefox 10 (Iceweasel) on Debian GNU/Linux AMD64, testing+unstable. No user scripts, Greasemonkey not even installed Third machine (just tested) is Firefox 11 (Iceweasel) on Debian GNU/Linux AMD64. Greasemonkey installed and enabled, and there is a global userscript. Does not happen on Chromium 18.0.1025.151, running on machine #3.  So far, that's all the machines I've tested on, and it happens on all of them. It only happens in chat. Easiest way to produce it is to click on the page background, somewhere outside the text box, to un-focus the text box. Then press backspace. Note that not all browsers will display the character, even if its there (check  to see if yours does) reflecting direct light on glossy surface in Cycles Working in Cycles.  Say I have a "disco ball" with a glossy shader. I'm pointing a spot light to it, and I'm trying to have the reflections of that light illuminate the diffuse material on the walls with the patterns from the ball.    I get this:    but I'd like to get something like:    For the illustration I placed a point light inside the ball an removed faces. But what I'd like to do is move the light around the ball so that the light reflected from it changes like it would do in real life.   Is that possible at this point?  EDIT:  Just for the record here's the image rendered in LuxRender (yet another program to learn...)