Few months before when I was using Ubuntu 12.04 then I found some errors while starting my computer.   Due to this problem I had given my CPU to a shop to repair it I don't know what he has done to my CPU but I only know that finally I got my CPU with Ubuntu 13.04.   The technician was unable to make any partition and I also think that he had installed 13.04 over 12.04 and so now my computer is showing some error when I'm starting my computer the error is as follows:     error: attempt to read or write outside of the disk 'hd0'.      grub rescue > _   Before showing this error, few times my computer was working very slow.  So kindly someone tell me that is there any way by which I can start my computer.  Please also tell me that what things I have to keep in mind while using Ubuntu so that in future I find no difficulties(errors) while using Ubuntu.
I tried to install Xubuntu 13.10 on an older computer. I noticed some difficulties during installation that may be relevant to my problems. Notably:   The screen resolution was extremely low. The windows were much larger than the screen and I had to move them around to get to the "Next" button. The mouse cursor was a blur of colours that was flashing all the time.   The installation finished and I tried to reboot the computer. Immediately I got:  error: attempt to read or write outside of disk 'hd0'.  Entering rescue mode...  grub rescue&gt;   I made a  USB disk, booted it and chose the default repair. The application told me that the problem is repaired and that If this does not solve my problem I should show  to someone who can help me.  What should I do next? I already tried to install Ubuntu and Xubuntu, both with no success.  EDIT:  I found a workaround.   Insert the Xubuntu live USB Select "try Xubuntu" In the settings menu select "install Xubuntu"   This fixed the problem for me. Since it is solved I cannot test the answer.
How to sort a Google Sheets Query by a custom ordering I have a table of choir members with a “name” and a “voice type” column. How can I write a query that orders them by decreasing pitch level of the voice type (i.e. soprano > contralto > tenor > bass)?  Is there in the  something similar to ?  I also tried the , but it does not seem to have an option for custom ordering, either. Issues Doing a String Comparison in LINQ Why can you see virtual images? Install Windows 7 with Bootcamp on OS X Yosemite with USB Key I have an iMac (bought in 2011) and I recently upgraded it with Yosemite. I am trying to install Windows 7 on it via Bootcamp.  However, its optical drive does not work, so I chose the USB key solution using the trick of modifying the file info.plist of Bootcamp (type 'usb bootcamp youtube' in google to see a video of this trick).  So I follow the process religiously and end up with the classic and famous boring screen 'No bootable device -- insert boot disk and press any key'.  So I tried to use Unetbootin (  ) to make my USB Key bootable, and tried to boot on it through the screen that appears when you maintain the Option key (Alt button) while starting the mac. Result: I never managed to have my Unetbootin-formatted USB key appear on this screen :(  I read some stuff about reFit (  ) and GParted, but I just don't know how to use them...  If someone managed to install Windows 7 on his/her iMac with Yosemite using a USB Key, please help me understand why I can't see the USB as a boot option. Curved mesh topology 2 I am trying to model a violin belly and I am intrigued, how is it possible to make faces with soft / rounded edges?    The edges I do are totally straight (see the blue amoeba).  Also, do you have some idea on how to avoid the edge loops getting too "compressed" in the middle of the model (see the red amoeba) ?    I know the Subdivision surface modifier, but I want curved edges after applying the modifier... like in this picture :  Any help will be very appreciated. Thank you in advance!  Marcos  2nd part  In fact, I've tryied to model using nurbs and bezier curves, but I wasn't able to find any tool similar to loft that works with curves, then I was forced to convert it in meshes, the results were not terrific and I've started to move the vertices manually, a real pain... Unlike a guitar, each edge loop is on a diferente elevation on z axis and I have to keep the original dimensions, So I have to be extremely careful when using the subdivision suface modifier. I've already modeled this think on three different CAD softwares, but the meshes are far from good... I want to improve the edge loops, but it will be a long path... Thank you again. Sometimes a suggested edit is  because of a concurrent direct edit that takes precedence.  Since this is no fault of the edit suggestor, such rejections should not count against the suggestor when counting .  Here are some examples where it happened: This poor creature is taken aboard the spaceship and the humans do not know that it is intelligent.  The alien can repeat what it hears, e,g, "pass the sugar".  It is able to escape at night and it communicates messages to its fellow aliens.  It directs that they turn up the heat of the atmosphere (somehow they can do this) so as to force the humans to leave.  The alien protagonist states that it will die w/ the humans or leave with them. What's the difference between Fermi Energy and Fermi Level? I'm a bit confused about the difference between these two concepts. According to Wikipedia the  and  are closely related concepts. From my understanding, the Fermi energy is the highest occupied energy level of a system in absolute zero? Is that correct? Then what's the difference between Fermi energy and Fermi level? I want to uninstall and completely remove QGIS installation from my computer(windows vista). I have uninstalled it and when i try to reinstall it says it is already installed on the system. Let $G = \mathbb{R} / \mathbb{Q}$. Is this an interesting group to study?  Is it isomorphic to any more natural mathematical objects? Delay in approval leads to missing out on being awarded an "Explainer" badge I am not sure if this is a bug or a design error, but I came across this issue on Robotics. I assume that the same code is employed across the various SE sites, so I am posting my question here. I submitted an answer to  at 16:26.    I then suggested an edit to the question at 17:03. However, it was not until 20 hours later, at 13:03, that the edit was approved, so I appear to have missed out on the &quot;Explainer&quot; badge, as the edit should be done within 12 hours.    I don't know the reason for the delay, as I do not have a low approval rating:    I'm not bothered about missing out on the badge, nor am I criticising the reviewers - after all, we all do this in our free time. However, it does seem that the algorithm for the badge relies on the approval time, in lieu of the submit time, which does not seem to be correct, as the badge then becomes dependant upon the reviewer's availability/responsiveness, rather than upon the actions of the answerer/editor.  TL;DR Should the badge also check if the edit was caused by a suggested edit and, in those cases, look at the time it was suggested rather than the time it was eventually approved? How do I install Ubuntu to a USB key? (without using Startup Disk Creator) Adding a citation after paper is accepted I am a junior researcher in mathematics. I worked simultaneously on proving Theorem A and Theorem B. They both generalize Theorem X in two different directions. Theorem X was proved several years ago (not by me). The proofs of Theorem A and Theorem B use very different techniques, and so I decided ahead of time to write one paper for each.  I finished proving Theorem A before I finished proving Theorem B. Then, I submitted Paper A to a journal (and the arXiv) proving Theorem A. Paper A includes a survey of related problems in the introduction. After a short while, I managed to prove Theorem B, and two months after the submission of Paper A, I submitted Paper B (to a different journal, and also to the arXiv). Now, six months after the submission of Paper A, it is accepted with requests for minor corrections. There is no response yet regarding Paper B.     In this situation, is it a reasonable/common to add one/two sentences to the survey in introduction of Paper A, explaining and citing the arXiv prepreint of Paper B, in addition to the minor corrections the referees asked for? (and letting the editor and referees know that I did that in my answer to their reports which comes along with the corrected manuscript).   Note that I am not asking if it is ok to cite a preprint. This is something I do, and so do other people, at least in math. My question is about making a change, after acceptance, which was not asked by the referees and the editor. How to choose a specific weight from a font family using fontspec and XeLaTeX Human & Alien captured, observed by higher beings From a collection of short stories I read at least 30 years ago. :/  This is going to be incredibly vague, so apologies in advance.  A human and alien (blob/octopus-like...I think) from warring races are captured by an unidentified higher intelligence and put in an enclosure (more like a zoo habitat rather than a prison cell). They are separated by an invisible barrier and can see each other.  I think they were both trying to escape or trying to figure out how they could kill the other first. There was a bulldozer/loader type vehicle they could use at one point to build a shelter (or something).  I believe they were crafting makeshift weapons as well. There was no communication between the two as far as I remember.  The main tension in the story seemed to be was the race to get to the other first.  This has been stuck in my head forever. I know its a very common theme.  The short stories may have included Asimov. Trace of a commutator is zero - but what about the commutator of $x$ and $p$? Operators can be cyclically interchanged inside a trace: $${\rm Tr} (AB)~=~{\rm Tr} (BA).$$ This means the trace of a commutator of any two operators is zero: $${\rm Tr} ([A,B])~=~0.$$ But what about the commutator of the position and momentum operators for a quantum particle? On the one hand: $${\rm Tr}([x,p])~=~0,$$ while on the other hand: $$[x,p]~=~i\hbar.$$ How does this work out? Why are there gaps in my IDENTITY column values? How to use regex in String.contains() method in Java BASH script to set environment variables not working I've written the following script to set some environment variables when needed.  #!/bin/sh export BASE=/home/develop/trees echo $BASE export PATH=$PATH:$BASE echo $PATH   Below the command and the results I can see on my terminal: the script runs, but the variables are not set at the end.  ~$: ./script.sh /home/develop/trees /bin:......:/home/develop/trees ~$: echo $BASE  ~$:    What's wrong? Thanks in advance. Mirko $\mathbb{Q}[x,y]/\langle x^2+y^2-1 \rangle$ is an integral domain, and its field of fractions is isomorphic to $\mathbb Q(t)$