This question follows one I posted earlier this week .  I'm having trouble using chemnum, for replacement of temporary labels (TMP1, TMP2, TMP3) in a scheme made with chemdraw. It indeed affects the labels, as they disappear, but they are not replaced at all.   Here is the code I use:   \documentclass[a4paper,12pt,notitlepage]{book}   %Packages \RequirePackage{etex} \usepackage[utf8]{inputenc} \usepackage[francais]{babel} \usepackage[T1]{fontenc} \usepackage{graphicx} \usepackage[crop=off]{auto-pst-pdf} \usepackage{psfrag}  %chemistry packages \usepackage{chemstyle} \usepackage{chemnum} \usepackage{chemscheme} \usepackage{titling}  \usepackage{titlesec}    %to correct spacing of chapters         \titleformat{\chapter}[display] {\normalfont\huge\bfseries}{\chaptertitlename\ \thechapter}{20pt}{\Huge} \titlespacing*{\chapter}{0pt}{-50pt}{20pt}     \titleformat{\chapter}[hang] {\normalfont\huge\bfseries}{\chaptertitlename\ \thechapter:}{1em}{}    %Title \title{Partie expérimentale} \author{Me}   \begin{document}  \chapter{Partie Expérimentale} \section{Synthèse du thiéno[3,2-b]thiophène-2,5-diylbis((3-bromothiophèn-2-yl)méthanol)}   \cmpd*{a} \cmpd*{b} \cmpd*{c}  \begin{scheme}[ht]    \replacecmpd{a}     \replacecmpd{b}     \replacecmpd{c}          \includegraphics[scale=0.7]{Schema_Synthese_3.eps}                   \caption{Schéma réactionnel 1}  \end{scheme}   \end{document}   Here is the result:   And here is the  if needed.  Any piece of advice on how to get the labels I want?

If I use the fontenc package, I do not see compound numbers in the scheme:   \documentclass{report} \usepackage[T1]{fontenc} \usepackage{graphicx} \usepackage[crop=off]{auto-pst-pdf} \usepackage{chemnum} %\setchemnum{replace-style=,format=}  \begin{document} \replacecmpd{a} \replacecmpd{b} \includegraphics{test.eps}  See compound \cmpd{a} and \cmpd{b}. \end{document}   Output:    If I comment out the fontenc package, it seems to work:


I understand that $1/\pi$ is the pdf for uniform probability on the unit disk (with suitable constraints on $x^2 + y^2 =1$), because the area for radius 1 is just $\pi$. However, how is the double integral set up to get a value of 1 when integrating? I have worked with various combinations of 0,1, $\sqrt{1-x^2}$, etc. as the limits of integration and haven't been able to get a combination that works yet so that the calculation of the double integral comes to 1.

I was referring to this lecture . However, I didn't get how the pi value was calculated. Here is a screenshot    As far as I know the integral gives the area under the curve. So I didn't get how the double integral is giving the value of pi using P(x,y).  Also how did it convert to mean in the octave. I am just a beginner. So please some guidance is required


I've been trying for so long to apply an image texture to a specific part of an object in Blender for a while and I really need an opinion of an expert here. So, my object looks like below (front, side and back):    What I want is to apply an image texture only to these specific parts of the object. I've tried so far:  to do it by using nodes (Material properties) - didn't worked as it apply the image texture to the whole object; importing the texture paint, select the specific parts (using "Texture Paint" as object interaction mode), selected as "Mask Mapping" the option "Stencil" and applied - it worked somehow, however the image texture applied it's not the same on both faces (has different axes positions). Also, the above part of the object (the middle part between front and back) it stays always black.  Is there any way of doing this?

How do you add more than one material to a mesh?   I have tried adding two materials to the object, and then assigning one of the materials to a vertex-group, but I could not find a place to assign it.  I am making a striped bouncy ball that I want to deform, so adding a different material by separating the mesh into different objects would not be ideal.


I have a problem that my disk is filling up but I cant find the files that fill it. When I run df -h I get:  Filesystem      Size  Used Avail Use% Mounted on /dev/root        53G   51G  2.0G  97% / devtmpfs        2.0G  4.0K  2.0G   1% /dev none            395M  204K  395M   1% /run none            5.0M     0  5.0M   0% /run/lock none            2.0G     0  2.0G   0% /run/shm none            100M     0  100M   0% /run/user   I cleared all caches, logs and auto remove files. When I read this command du -h /var | sort -nr | head -n 10 I get:  1016K   /var/www/soFit/cache/class_folder-242/soinfitcom/cl 1016K   /var/www/landing/PHPMailer/vendor 1008K   /var/www/dating/libs/vendor 988K    /var/www/libs/mPDF/ttfontdata 968K    /var/www/landing/PHPMailer/vendor/phpmailer 964K    /var/www/landing/PHPMailer/vendor/phpmailer/phpmailer 960K    /var/www/soFitTest/groupChats/vendor/symfony/http-foundation 960K    /var/www/soFitTest/chat/vendor/symfony/http-foundation 960K    /var/www/soFit/groupChats/vendor/symfony/http-foundation 960K    /var/www/soFit/chat/vendor/symfony/http-foundation   Using du -x / | sort -rn | head -n 10  2471828 / 1592004 /var 1091532 /var/lib 929776  /var/lib/mysql 776620  /usr 715092  /var/lib/mysql/soFit 306064  /var/www 291376  /usr/lib 269176  /usr/share 180868  /var/www/libs   My mysql db size is ~500MB, not that big.  Where is all the 51G of space are gone to?  My linux is:  Debian GNU/Linux 7.11 (wheezy)  du -h --max-depth=1 / 4.0K    /dev 6.4M    /etc 4.0K    /mnt 759M    /usr 4.0K    /selinux 5.5M    /root 20K     /home 24K     /srv 4.0K    /opt 0       /sys 8.0K    /tigo 8.0K    /media 16K     /lost+found 1.6G    /var 6.5M    /sbin 4.0K    /lib64 7.0M    /bin 4.0K    /.ssh 204K    /run 15M     /lib 4.0K    /boot 12K     /tmp du: cannot access `/proc/4557/task/19375/fdinfo/312': No such file or directory du: cannot access `/proc/13067/task/13067/fd/4': No such file or directory du: cannot access `/proc/13067/task/13067/fdinfo/4': No such file or directory du: cannot access `/proc/13067/fd/5': No such file or directory du: cannot access `/proc/13067/fdinfo/5': No such file or directory 0       /proc 61M     /backups   2.4G    /  The answer was to find the files using: lsof | grep -i deleted and to delete this files.  Shutdown the machine completely  not only reboot  var/libs/mysql delete (none).log

When I sum up the sizes of my files, I get one figure. If I run du, I get another figure. If I run du on all the files on my partition, it doesn't match what df claims is used. Why are there so many different figures for the total size of my files? Can't computers add?  Speaking of adding: when I add the “Used” and “Available” columns of df, I don't get the total figure. And that total figure is smaller than the size of my partition. And if I add up my partition sizes I don't get my disk size! What gives?


Show that: $$ \lim_{n\to\infty}\sum_{k=1}^{n}\frac{n}{n^2+k^2}= \frac{\pi}{4}$$ My idea: I thought that this could be rewritten as an integral, then use trig substitution (perhaps tangent) and then solve to get the answer, but I keep getting stuck. I think I am not setting the problem up correctly. Help would be appreciated. Thanks! :)

Show that $$\lim_{n\to\infty} \sum\limits_{k=1}^{n} \frac{n}{n^2+k^2}=\frac{\pi}{4}$$   Using real analysis techniques.


I have a dynamic PHP table (tableData.php) that I need to import onto my main page (index.php). I'm using jQuery .load() to import the data, and that's working fine. The table is appended to the div that I want it in.  $(document).ready(function () {    $("#newTable").load("tableData.php");   Once tableData.php is rendered on my main page, I then need to then do things with that table. So if a user clicks on a < TD >, certain functions fire.   $('td').on('click', (this), function() { var time = $(this).closest("table").attr("id");   The problem is that .load() isn't sending the HTML elements to my main page so jQuery isn't recognizing that a < TD > has been clicked. Viewing the page source, it just shows an empty div where the new table sits. If I use      < ? php include 'tableData.php'; ?> it works great, but I want this table to render after the page has loaded.   My question is, is there a way to copy the actual HTML of one page into another page? Right now it seems that I just have a shallow copy, when I need a deep copy.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Suppose that $f:X \rightarrow Y$ is a function.  Then an injection can be defined as:  $$\forall x_1,x_2 \in X, f(x_1) = f(x_2) \Rightarrow x_1=x_2$$  Why isn't it defined instead as follows?  $$\forall x_1,x_2 \in X, f(x_1) = f(x_2) \Leftrightarrow x_1=x_2$$  I think the above statement also captures the situation described by the definition of an injection in words, which is:     If no element of $Y$ is assigned to more than one elementof $X$, i.e. the function takes a different value for each point of the domain.   I can see that the definition is missing the phrase "if and only if". So is that the only reason we don't write "$\Leftrightarrow$"?

From wikipedia I obtain the following definition of an injective function :     Let $f$ be a function whose domain is a set $A$. The function $f$ is injective if for all $a$ and $b$ in $A$, if $f(a) = f(b)$, then $a = b$; that is, $f(a) = f(b)$ implies $a = b$.    From this I conclude that a function $f$ is injective if the below statement is true for all $a,b \in A$:  $$f(a)=f(b) \implies a=b$$  My question is: Can I re-formulate the above statement as $f(a)=f(b) \iff a=b$ ?


For the Lebesgue measure let F $ \subset L^2( [0,1], \mathbb{R} ) $ be a closed linear subspace of $ L^2 $ and also $ F \subset (\mathcal{C} [0,1]) $.   With the Banach isomorphism theorem i proved that $ (F, \| \|_{ L^2} )  \cong   (F, \| \|_{ \infty} )  $  and so both norms are equivalent on F.   3) Suppose that $ ( \varphi_n)_{1 \leq n \leq N} $ is a orthonormal subset in $ (F, \| \|_{ L^2} ). $ For all $ y \in [0,1] $ we consider ,  $ f_y : x \in [0,1] \mapsto \sum_{n=1}^N \varphi_n(x) \varphi_n(y) $  a) for $ y \in [0,1] $ compute $ \| f_y \|_{ L^2} . $  b) for $ y \in [0,1] $ find a lower bound to $ \| f_y \|_{ \infty} . $  4) Conclude that F is finite dimensional.  So i found  $ \| f_y \|_{ L^2} = (\sum_{n=1}^N \varphi_n^2(y))^{1/2}  $  And $ \varphi_i (y) \leq   \| f_y \|_{ L^2}   \leq \| f_y \|_{ \infty} .  \forall i $     How do i conclude that F is finite dimensional ?  I tried using the Riesz Lemma (compactness of unit ball thus finite dimensional) without any success. I know that $ L^2 $ is a separable Hilbert Space hence it has a countable Hilbert basis but i'm not sure if that helps here.  Thanks in advance for any help on the matter.

Let linear $S$ be a subspace of $C([0,1])$, i.e., the continuous real-valued   functions on $[0,1]$. Assume that there exists $c>0$, such that   $\|\,f\|_\infty\leq c \|\,f\|_2$, for all $f\in S$. Then show that $S$ is finite-dimensional.   This is equivalent to proving that the closed unit ball in $(S,\|\|_\infty)$ or in $(S,\|\|_2)$ is compact, but I can't derive this.   Another thought is that the $L^2$ closure of $S$ is a subset of $C([0,1])$. Indeed, if $f_n\to f\in L^2$, then the given relation $\|f_n-f\|_\infty \leq c\|f_n-f\|_2$ implies that $f_n\to f$ in $L^\infty$, so $f$ is continuous. Therefore we have the inclusion $$S\subset \overline{S}^{L^2}\subset C([0,1])\subset L^2$$ If $S$ was infinite dimensional, then $\overline{S}$ would be an infinite dimensional hilbert space, proper subset of $L^2$.   Another thought is that all the $L^p$ norms on $S$ are equivalent (by Holder). If ALL norms are equivalent, then $S$ has to be finite dimensional.


I bought a used frame without a derailer.  What type will I be able to use?  I would like to switch to trigger shifters and a good quality derailer.  See photos.enter image description here

I have acquired an older Pegasus, model unknown. Guessing by the decaying decals it might be something like Atlas. Bike is in poor neglected condition, but I will try to put in on the road to see how it rides and then decide if I dump it or do some more work on it. It came with a Suntour AR II rear derailleur. The frame has simple dropout and bike came with some sort of generic deraillur hanger. The problem is that when I release the quick release the hanger with derailleur comes loose along with the wheel. Below are some pictures. As you can see the derailleur has no clear way of mounting to the frame. The frame does not have any hole that aligns with small the in the hanger. The hanger has on the backside a little edge that aligns it with a dropout as seen on the picture.  Options I considered were:  1. Drilling a hole in the frame and then cut a thread for the bolt. Which thread should I cut in that case to be "universal" or compatible with bolts that are used for that purpose?  2. Puting a bolt through the small hole in the hanger and through the dropout. Use a big washer and a nut on the backside to fix the hanger in a dropout semi permanently. I would then fix wheel axle with quick release as usual. Down side of it is, that the axle would be moved forward in dropout by about 14mm.  3. Try to find a suitable hanger. No luck so far. Through Google I have found a picture of a hanger that might do the job.  What would my best or simplest option to mount that hanger?


I know hashes can be used to construct symmetric encryption schemes (HMAC running in counter mode), signature schemes (SPHINCS), pseudorandom generators, etc.  One thing that's missing is public key encryption. Is it possible to create a hash based public-key encryption scheme?  My intuition says no. But it would be nice if there is a proof that it can't be done.

In the  or  there's a plenty of information about hash-based signatures. But where are hash-based ecryption with pubkey?     But, over the long-term, it's generally confidentiality (i.e. encryption) that you need to maintain and I haven't talked about post-quantum encryption at all in this post. (Maybe in the future.)   Why articles about hash-based asymmetric encryption are more hard to come by?  Possible reasons:   It is impossible and the proof is basic enough that it not deserves an article (or a question here) It is even more impractical than hash-based signatures It is secret and classified It is somehow not interesting and nobody cared to research it It is called by some other term, using which articles get found easily. Linked articles actually do speak about them, but I don't read attentively and missed it.


I'm confused after reading the  and the first reply. The asker asks,     I'm becoming more interested in landscape photography and want to add   to my Nikon DSLR a wide angle lens, but I dont really understand what   this means. According to Wikipedia (not the most reliable source I   know!) common wide angle focal lengths are 35, 28, 24, 21, 18 and   14mm.      So this does this mean that the kit lens that comes with the Nikon   (18-55) is considered to be wide angle at the shorter focal length?      Also, what is the difference between ultra-wide and normal wide angle?   And would an ultrawide be useful for landscape photography?   The first reply says,     On a crop sensor body (DX) that lens has a focal length of 27-82mm   The question doesn't mention about the type of camera body (DX/FX) or lens (DX/FX). To my knowledge, for the explanation to be true, it has be an 18-55 FX lens mounted on a DX camera body. Can't then only the crop factor (1.5X) kick in? But, 18-55 FX lens does not exist in Nikon lineup.  The way I understand crop-factor is that a 12mm lens mounted on an FX body will provide the same field of view of an 18mm lens mounted on a DX body, provided the distance between camera and subject remains unchanged. Going by the logic, the reverse should also be true, i.e. an 18-55 DX lens on a DX body should be equivalent to 12-35 FX lens on a FX body.

I have a Canon 7D, which has a crop factor of 1.6x.  When using a Canon EF-S lens I get the focal length stated on the lens, when using a Canon EF lens I get the focal length times 1.6 when used on the APS-C body. At least that's what I thought.  I just compared two lenses:   Canon EF-S 15-85mm f3.5-5.6 Canon EF 70-200mm f4   .  The top photo is shot with the 15-85, the bottom photo with the 70-200 - both lenses are set to 70mm. Now why do they look the same?  I thought I would get 112-320mm (70mm*1.6 crop factor). What did I misunderstand about the crop factor calculation? Lightroom also displays the photos as having "70mm" and not 112mm.


The help icon only leads to a general Markdown reference.   The way to enter formulas should be mentioned, preferably in a separate section and with a link to a Tex reference.

As the title says, I could use an exhaustive list of all Stack Exchange sites that use MathJax.  If the list included any site-specific customizations made to the MathJax configuration on each site, that would be even better.


Why does putting baby oil on construction paper give the color a translucent effect?

When I smear oil onto a scrap of paper and rub it in, the paper becomes quite translucent; but when I attempt the same with water it doesn't as much. Why?


What are the easy and possible ways to upgrade the operating system from 12.04 to 13.04? Are there  any option except booting the system with 13.04?

I am currently using Ubuntu 10.04. I know there is a 10.10 release, but can I upgrade directly to 11.04? Could you walk me through the steps please?


If a visitor stays less than 90 days in France, the visitor plans to stay 77 days, how soon can this visitor return to France?? Is it the required 90 day time frame, then the visitor can return, or is it 77 days, etc???

Some destinations have a "90/180 rule" which says you can come and go but you must not spend over 90 days out of any 180 days in the area.  concerns this rule.  At least Schengen and Turkey have this rule, probably depending on where the traveller is from and what kind of visa they apply for.  Maybe I'm a dummy but I've always had a lot of trouble trying to add up how many days I've spent in such places when I've entered and left several times over recent months.  Is there an easy way to do this I'm missing or is it difficult for everybody? I'm guessing something based on counting backwards from the end date might be the trick?  Maybe you know of an app or website that can do this for you.


I'm new to D&D and not played before. I don't have friends who play the game and am wanting a way to start off on my own to learn the basics.  Does anybody know of any way to play online solo?   Thank you in advance!

I'm no gamer at all, so this could be like a very silly, basic question for you guys. The thing is that I always read about "Dungeons and Dragons" game (not the video game, but the normal game to play with friends that are actually gathered together). And I would like to know how to play it.  I've read that it is a book (or several ones, which is more confusing for me to understand), but I've read somewhere that it can be played as a normal "table" game, with a board, and pieces, and somewhat weird dice (or sets of dice).  Is it like a normal game, where you pull the stuff out of a box and start to play?  I don't know if any of you watch the show "The Big Bang Theory", but I think they have played the game in a recent episode, and it looks just like a regular game.  I've Googled it for more information, but I haven't found anything as basic as I need, because I've never played a role game (except in a video game).  I just want to learn how to play, so I can get my friends into it to play it each time we get together.


As the title says, I'm trying to find out which fonts are used in Riehl and Verity's .

Is it possible to identify the font used in a specific document/picture?  Answers to this question should identify:   Possible methods to do this (perhaps one answer per method) and adequately describe how to use it (as opposed to merely stating it); Ways of finding the identified fonts, if possible (free or not); and Any prerequisites associated with the method used, if required (for example, "In order to use method X, your document has to be in format Y").   This question is meant as an FAQ, based on an . Its aim is to facilitate the community with the general procedures involved in font identification. Similar cases are solved on a per-usage basis on 's  tag.


I'm primitive in integrals and derivatives and I'm trying to solve the integral $\int \frac{1}{e^x}\,dx$, but especially this integral was hard to me to solve it.  So I tried:  $$\begin{align} \int\frac{1}{e^x}\,dx&=\int \frac{1}{\color{Red}{e^x}}\color{Blue}{e^x\,dx}\\&=\int \frac{1}{\color{Red}{u}}\,\color{Blue}{du}\\&=\ln\left(|u|\right)\\&=\ln \left(|e^x|\right)+C \end{align}$$  But my solution is wrong while I used the integration by substitution method ?!    Correct answer:  $$\begin{align} \int\frac{1}{e^x}\,dx&=\left(-e^{-x}\right)+C \end{align}$$

I'm trying to find the value of the integral $\int_{-4}^{-2}e^{-x}\,dx$ but I just couldn't solve it.  Actually I found in a  that $\int e^x\,dx=e^x+C$ so I concluded:  $$ \int e^{-x}\,dx=\int\frac{1}{e^x}\,dx=\ln|e^x|$$  $$\int\limits_{-4}^{-2}e^{-x}\,dx=\left(\ln|e^{-2}|\right)-\left(\ln|e^{-4}|\right)=-2+4=2$$  I know the solution is wrong, but how can I solve this integral or any another integral like this?


I'm trying to implement sharepoint pagination in a way that you send how many items to skip and retrieve the next n number of items. Is there a way to go about it?    https://sharepoint.com/_api/web/lists/getbytitle('List')/items?$select=Id,Title&$filter=substringof(%27a%27,Title)   I need an implementation like skip and top for this url Edit:Can't use $skiptoken since ID's are not in sync and might cause variable amount of responses

Can anyone confirm that they are able to page against a SharePoint Online List Items query? Either I'm not understanding how this query is supposed to work or it just doesn't work.   tenant.sharepoint.com/conversations/_api/web/lists/getbytitle('Posts')/items?$skiptoken=Paged=TRUE&amp;P_ID=2   I'm leveraging the documentation  but when using Postman, all items are returned in the same query response. For example, according to the $skiptoken P_ID=2 above, I'm expecting a response without item ID 1. However, I still get ID 1, 2, and 3 in the response.


I have a json file that it has more than 30k lines, and I need to replace all instances of }{ in the file with },{ by using script shell or just a text editor like less or vim.

How can I find and replace specific words in a text file using command line?


How can I return my view window back to the original location?  Specifically, I want to have options panel to the right of the view window.  Thank you!

I accidentally opened too many menus (or windows) and I want to reset them to default.  It is really annoying, and effecting my animation.  Thanks


I am making an creature simulator where the creatures have a neural net for a brain.  One of the inputs to the net is the angle it has to travel to go to be facing the nearest piece of food. I can get the nearest piece of food, but I need a way of getting the angle it needs to travel to be facing the piece of food.   For example, if it was facing the food, it would be zero, and if it was facing away it would be 180. I got the creatures angle, if it is facing up it would be 0 degrees, and if its facing right its 90 degrees.

I am having some trouble understanding Math.tan() and Math.atan() and Math.atan2().  I have basic knowledge of trigonmetry but the usage of SIN, COS, and TAN etc for game development is very new to me.  I am reading on some tutorials and I see that by using tangent we can get the angle in which one object needs to be rotated by how much to face another object for example my mouse. So why do we still need to use atan or atan2?


How can I draw this spiral (with vertical sides) in tikz?  The only way I would know how, would be to copy and paste code to draw semicircles of different radius, followed by connecting the semicircles one at a time, which would take a very long time.

I feel intimidated in learning TikZ. I was wondering if there are some nice materials (or just your replies) at different level:   for providing big picture, which is important to beginners to not lose direction during learning. for comprehensive reference.   Examples are important, but only examples are not always clear for understanding the big picture and organization.


Let $a$ be any positive integer. If $x$ and $y$ are positive integers such that $max(x, y) = a$, then we know that $x = y$. I'm pretty sure this is a false claim, and I need to find what is wrong with the induction proof. For the base case, we let $a = 1$. Here, if $x$ and $y$ are positive integers such that $max(x, y) = 1$, then $x$ and $y$ must both be $1$. In the inductive case, we let $k$ be some arbitrary positive integer. The induction hypothesis assumes that if $x$ and $y$ are positive integers such that $max(x, y) = k$, then $x = y$ for some positive integer $k$. Consider the case where $a = k + 1$ and let $x'$ and $y'$ be two positive integers such that $max(x', y') = k + 1$. Now we have $max(x' - 1, y' - 1) = k$, which, by the induction hypothesis, implies that $x' - 1 = y' - 1$, and therefore that $x' = y'$. Thus, we have proven the claim. I can identify just one counterexample: if $a = 20, x = 10, y = 20$. Then, $max(10, 20) = 20$, but $20 \neq 10$.

Suppose that we are trying to prove that for every positive integer n, if x and y are positive integers with max(x, y) = n, then x = y. For the base case, we suppose n = 1. If max(x, y) = 1 and x and y are positive integers, we have x = y = 1. Now we let k be a positive integer, and assume that whenever max(x, y) = k and x and y are positive integers, then x = y. Let max(x, y) = k + 1, where x and y are positive integers. Then max(x - 1, y - 1) = k, so by the inductive hypothesis, x - 1 = y - 1, so x = y. What is wrong with this ``proof''?


Am applying for visiting visa to Canada with my wife and three kids, what is the range of funds require to be in my statement of account?

I am a Romanian citizen.  Our co-national friends who are established in Canada will provide me and another person free accommodation and food. We are both EU citizens and we will stay in Canada 1 month.  These days we are gathering documents for our online visa application and we need to prove that we have enough money to spend there.   How much money is generally required in order to be sure we are eligible? We don't plan to spend more than 1000 EUR, but I intend to bring at least 2000 CAD. Is it enough?


I have my new laptop :   Lenovo ideapad 330 15AST Processor is AMD A6 With Windows preinstalled   Questions :   Now I want to use Ubuntu and Windows also. I tried to dual boot my pc. While dual booting, my pc displays a message that, there is no os installed on selected USB drive. How can I solve it? I contact to Lenovo adviser and they told me that, if you run Linux on this laptop, it can corrupt your pc or Windows too. Is this right?

I would like to see a full how-to guide on how to install Ubuntu.


im a linux beginner and used google & Co. by installing the requirements (  ) for Qt:  sudo apt-get install build-essential libgl1-mesa-dev   i get the following error:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  libcheese-gtk23 : Depends: libclutter-gtk-1.0-0 (>= 0.91.8) but it is not going to be installed                    Depends: libcogl15 (>= 1.15.8) but it is not going to be installed  libcheese7 : Depends: libclutter-gst-2.0-0 (>= 0.10.0) but it is not going to be installed               Depends: gstreamer1.0-clutter but it is not going to be installed  libclutter-1.0-0 : Depends: libcogl-pango15 (>= 1.15.8) but it is not going to be installed                     Depends: libcogl15 (>= 1.15.8) but it is not going to be installed E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.   i solved the problem by removing libcheese-gtk23, libcheese7 and libclutter-1.0-0, but killed my Linux with this (i could install and use Qt, but after rebooting, the gui was dead).   if i dont install build-essential and libgl1-mesa-dev the Qt tells me, "cannot find -lGL".  My system: Zenbook 303LN, i7-4500u with HD4000, NVIDIA Gforce 840M, 256GB SSD, 8GB RAM, 64bit Ubuntu 14.04  Thanks for help

Occasionally, when I'm installing stuff, I get an error like the following:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  package1 : Depends: package2 (>= 1.8) but 1.7.5-1ubuntu1 is to be installed E: Unable to correct problems, you have held broken packages.   How can I resolve this?


I reallllly want to get rid of the taskbar. It takes useful screen space. Auto-hide won't cut it as it keeps popping up because of notifications and such.   Any ideas? :)  Edit: No luck, taskbar is intrinsic to explorer.exe, Taskbar Eliminator works on Windows 7, only option is to replace explorer.exe with some other shell.   thanks

I've installed Taskbar eliminator, while it works most of the time, alerts being the taskbar back.  I've also installed object dock which can disable the taskbar, object dock appears during window changes.   Has anyone had any luck permanently removing, hiding the taskbar in Windows 7?  Update  I found an application that seems to be working here:    Second update  I took the leap and installed a shell replacement (). So far so good.


I am trying to propagate an array along a curve. The mesh that is being replicated as an array is an iconosphere. Attached is an image of the array and the curve. You can see that almost all the iconospheres are distended to various degrees. There are probably just 2 that are uniform in size. I am guessing the distortion is due to the intricate curve and number of vertices along the path. Is there anyway around this?

I have a chain object. And i have a curve it follows. I got it to work for following curve, but chain object is not circles but both parts are more like stretched circles (ovals). Object i made with 2 toruses one rotated 90 degrees and then joined them together. I tried single torus too. But same issue. on a curve it just looks stretched oval. What can be the issue?   Thanks


I understand that there have been several fixes to this exact problem in the past, but I have tried them all and nothing has worked. The external speakers output sound just fine but the headphones do not. Interestingly enough, they do play a bit of static when I plug them in. That's about all that I can tell you except that I'm running Ubuntu 14.04 off of a flash drive (dual booting Windows) and I have a Dell machine.   I've tried the solutions listed here:   and a few from other random sources around the internet. I've made sure to completely shut down my machine after each attempted fix. I made sure to unplug and replug the headphones after Ubuntu booted up.   Should I just try and update Ubuntu?  I'm a bit new to Linux in general so I'm sorry for being such a noob. Any help is greatly appreciated. Thanks

I have a Dell Studio XPS 1647 and headphones do not work (though , internal speakers work like a charm) , I have dual boot Windows 7 and headphones work perfectly fine ...     I also tried -adding in options snd-hda-intel model=eapd probe_mask=1 position_fix=1.  I've experienced this with Oneric Ocelot and the latest Precise Pangolin (LTS).


I have entered the US with an ESTA 40 days ago. Now I staying in Mexico for two weeks, after that I am planning to go  back to the US and stay for 1 night only to then take a plane back to Europe. Will I need a new ESTA for my reentry? I will not violate the 90 days mark, everything will happen within that interval. I have heard several opinions now and I am really confused. I hope that you guys can help me. Thanks in advance

I applied for an ESTA because of my recent US flight to San Francisco. For my next flight, though, I will stop in the US because that's where my connecting flight will depart.  When I applied for an ESTA, I was requested to specify whether that was a connecting flight or not; it wasn't in that case. This time, it is. Do I have to apply for a new ESTA, so I can specify this is a connecting flight?


I downloaded Ubuntu 15.10 and created a startup disk with two different programs (xboot and pendrive...) The result in both cases is a startup disk that cannot start up/boot in Windows. And no .exe file also to start it from Windows. Only startup disks with older versions, e.g. 14.10 can be created in a proper way. Why is that?

Is there any Windows installer (wubi) for Ubuntu 14.04 LTS?  When I mount the .iso file with Daemon Tools and run wubi.exe, it just asks me if I want to reboot (I think that's useful only when the .iso  is burned on CD), so is there no "real" installation?


Running Ubuntu 14.04. Recently my sound for Youtube, Spotify, VLC etc. stopped working. However, changing the sound makes a little "bleep" noise and going into the test sound from settings works fine, with or without headphones. So all SFX noises are working fine but sound from a program isn't.  I've checked mute buttons, program sound levels in settings, rebooting, and obviously tried many different programs. The problem may have started after using an HDMI hookup. Any ideas and suggestions would be appreciated, thanks!   Worked it out, using "PulseAudio Volume Control" (sudo apt-get install pavucontrol) and changing the output sources from HDMI to internal analog. Not sure why these weren't showing up in system settings...

I have my PC hooked up to speakers and a monitor. In addition, it is hooked up to my Vizio 37' LCD Television. When I was on Windows 7, I could choose to output sound via HDMI. I have the choice in Ubuntu but no sound is outputted. Any Ideas? I don't know how to get system specs on Ubuntu so if you need them please tell me how to get them.   aplay -l output:  **** List of PLAYBACK Hardware Devices ****  card 0: Intel [HDA Intel],  device 0: ALC887 Analog [ALC887 Analog]  Subdevices: 0/1  Subdevice #0:  subdevice #0 card 0: Intel [HDA Intel], device 3: ALC887 Digital [ALC887 Digital] Subdevices: 1/1  Subdevice #0: subdevice #0 card 1: HDMI [HDA ATI HDMI], device 3: HDMI 0 [HDMI 0] Subdevices: 1/1 Subdevice #0: subdevice #0


Is there a case where $f$ is differentiable at $0$ but not any other point?

While studying complex variables, I could learn that $f(z)=|z|^{2}$ has only one point which is $z=0$ that $f$ being differentiable and $f$ being not differentiable at any other points.  Then, I was wondering if there is a function $f: \mathbb R \to \mathbb R$ that has only one point differentiable and not on any other points.  In intuition, it seems there are no such point! However, I have no idea how I can prove this...  Additional question is that would there be any function $f: \mathbb R \to \mathbb R$ that has only one point continuous and not on any other points.  I think this is pretty interesting things to think about! :-)


I managed to quite easily show the reverse direction $\Leftarrow$, but the following direction is giving me a lot of problems:     no strictly decreasing sequence of elements in linear order $A$ $\Rightarrow$ $A$ is well ordered   Any help would be appreciated!

I tried to do the following exercise from a book I'm reading, can you tell me if my solution is correct? Thanks!  Theorem 2: Let $R$ be a binary relation on a set $X$. Then $R$ is strictly well-founded iff there is no sequence $(x_n)_{n \in \mathbb N}$ of elements of $X$ such that $(x_{n+1}, x_n) \in R$ for all $n \in \mathbb N$.  Exercise:  (i) Formulate an analogue of Theorem 2 for  well-founded relations.   (ii) Prove Theorem 2.    (i) Theorem 2': Let $R$ be a binary relation on a set $X$. Then $R$ is well-founded iff there is no sequence $(x_n)_{n \in \mathbb N}$ of elements of $X$ such that $(x_{n+1}, x_n) \in R$ and $x_n \neq x_{n+1}$ for all $n \in \mathbb N$.  (ii)   $\implies$: Assume there is a sequence $x_n$ with $(x_{n+1},x_n) \in R$ for all $n \in \mathbb N$. Then the set $Y = \{x_n \mid n \in \mathbb N\}$ and hence $R$ is not well-founded since for every element $x_n$ there is $x_{n+1} \in Y$ with $(x_{n+1},x_n) \in R$.  $\Longleftarrow$: Let $R$ be strictly well-founded. Assume we have a sequence $x_n$ with $(x_{n+1},x_n) \in R$ for all $n \in \mathbb N$. Then by the same argument as above $R$ is not well-founded, hence there cannot be such a sequence.   I must be missing something but I can't seem to figure out what.


Let $f : \mathbb{R}^3 \rightarrow \mathbb{R}$. How can i show that       If $f(x,y,z)=0$ then $$\frac{∂x}{∂y}\frac{∂y}{∂z}\frac{∂z}{∂x}=-1 $$   Any help will be appreciated.

Ok guys, continuing my passage through edwards... here is the question... thanks for hints/solutions in advance:  Suppose $f(x,y,z)=0$ can be solved for each of the three variables $x,y,z$ as a differentiable function of the other two. Then prove that  $\displaystyle \frac{\partial x}{\partial y} \frac{\partial y}{\partial z} \frac{\partial z}{\partial x} = -1$  Verify this is the case for the ideal gas equation $pv =RT$ where (where $p,v,T$ are the three variables and $R$ is the constant).


I have a paper in TeX that has the \thebibliography section. I need to convert it into a BIB file.   I realize that it cannot be done automatically, but are there tools that at least partially help, with post-editing? Preferably online tools where I could paste the whole list, not pasting things one by one.  The domain is computer science and specifically natural language processing, so mathematics bibliography tools most probably will not help here.

I have the following list of publications in a text plain file:  [1] Heikki Ailisto, Petteri Alahuhta, Ville Haataja, Vesa Kyllönen, and Mikko Lindholm. Structuring context aware applications: Five-layer model and example case. In Proceedings of the Workshop on Concepts and Models for Ubiquitous Computing, pages 1–5, Goteborg, Sweden, 2002.  [2] Chris Allan, Pavel Avgustinov, Aske Simon Christensen, Laurie Hendren, Sascha Kuzins, Ondrej Lhoták, Oege de Moor, Damien Sereni, Ganesh Sittampalam, and Julian Tibble. Adding trace matching with free variables to AspectJ. In Proceedings of the 20th ACM SIGPLAN Conference on Object-Oriented Programming Systems, Languages and Applications (OOPSLA 2005), pages 345–364, San Diego, California, USA, October 2005. ACM Press. ACM SIGPLAN Notices, 40(11).  [3] Malte Appeltauer, Robert Hirschfeld, Michael Haupt, and Hidehiko Masuhara. ContextJ: Context-oriented programming with Java. Information and Media Technologies, 6(2):399–419, 2011.   and I need to generate a bib file (or any other kind of reference database).  To sum up, I need to generate a reference database from a text plain file. Is it possible?  Best,


On Linux file manager, I think Dolphin (not sure right now, sorry) I can open Konsole just hitting F4. I would like to have the same on MacOS/Finder, openning Terminal instead. Is it possible?  I'm on El Captain.

I am using Alfred and hence I don't have any use for the Cmd+Space keyboard shortcut. I want to invoke terminal using that shortcut. Just like in Ubuntu, when you press Ctrl+Alt+T I don't want to use Alfred to start the terminal. I just want to press Cmd+Space and I want the terminal to appear just like it would in Ubuntu. Is there a way to start terminal like that in OS X Mavericks?


I've been trying to learn some algebraic geometry (level of generality: working over an algebraically closed ground field but not afraid of using the language of sheaves and cohomology etc.)  The problem I'm having with it is that most of the references I'm using (Milne's notes on AG, Perrin's Algebraic Geometry, Mumford's Red Book etc.) just seem like endless streams of technical results and whilst I can appreciate most of the concrete examples ("oh look - that's a singularity"...), I'm not really sure what I'm supposed to be doing. On the other hand, books like Reid's Undergraduate AG makes me feel like I'm not sure what the definitions are (if that makes sense to someone!).  At the minute my approach is to check everything line by line (if I can!) and try to build up a picture of how the technicalities fit together into a bigger picture. I've also tried to do the exercises in Chapter 1 of Hartshorne but a lot of them seem too difficult for me at the moment (there feels a big gap between the technicalities of the chapters in the books and the concrete nature of the examples).  Does anyone have some magical book recommendation that I've missed or some other approach that helped them learn the subject?  Many thanks!

Lifted from :  I think (almost) everyone agrees that Hartshorne's Algebraic Geometry is still the best. Then what might be the 2nd best? It can be a book, preprint, online lecture note, webpage, etc.  One suggestion per answer please. Also, please include an explanation of why you like the book, or what makes it unique or useful.


I have an array of arrays. I want to append an element to a[0]  a = [[]]*26 a[0].append(1)   When i'm trying to do that, i get:  [[1],[1], ... , [1]] 26 times   But i want to get:  [[1], [], ..., []]   Why does it work so?

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


When I run sudo apt-get update to update the system I get this error on the bottom of the console:  W: GPG error: https://repo.skype.com/deb stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 1F3045A5DF7587C3 W: The repository 'https://repo.skype.com/deb stable InRelease' is not signed. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details.   What's going wrong with Skype? Is there any risk since the error says that the Skype repo is dangerous to use?   I use Ubuntu 16.04.

I added some extra repositories with the Software Sources program. But when I reload the package database, I get an error like the following:     W: GPG error:  trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8BAF9A6F   I know I can fix it using apt-key in a terminal, according to the official Ubuntu documentation. But I would have liked to do it graphically. Is there a way to do this without using a terminal?


I want to login to drupal through JSON,  I read  issue, but non of the proposed solutions helped me do that using Postman on drupal 8.2.5. specially when I send this specification :  POST: http://example.com/user/login?_format=json Content-type: application/json Data: { "name": "admin", "pass": "myPassword" }   Response is: 200 OK,  But the result is in HTML foramt and just shows the login page of drupal website!

Do anyone have a working REST Login on Drupal 8? This is what I tried. POST /user/login HTTP/1.1 Host: 8.d8.local Content-Type: application/x-www-form-urlencoded Accept-Encoding: http://nikhilmohan.in Cache-Control: no-cache  name=test&pass=password&form_id=user_login_form  It returns me HTML instead of JSON.


I have toggle the front view and other sides but i cant see any of my imports pictures in the background.

I try to set up an image as background for a basic blender tutorial, but it isn't visible.  This is the image I try to have as background:


I need to prove that $$\sum_{i=0}^{n-1}  {2^i} = 2^n -1.$$ I tried induction but something didn't work.

I was hoping someone could help me come up with a combinatorial proof, one with an easy to understand 'story' for $\sum_{k=0}^{n-1} 2^{k} = 2^n - 1$. For instance I understand that $2^n$ is the number of possibilities when creating subsets of size $n$. For example, if you're given a choice of any topping on a pizza, and you can only have said topping once (decide to include or exclude) then you have $2^n$ choices. But I'm not sure how the $-1 $ would be incorporated, or why the LHS would be $1+2+4+8+...+2^{n-1}$


We have submitted an article in a finance journal ( ABDC rank A) more than one year ago. After around 6 months they sent us the review of two reviewers where one reviewer reject the paper with few correction suggestions and another gave relatively good comments with additional correction suggestions. Hence the editor asked for revise and resubmission and also mention that if we comply with the reviewer's comments, he will personally read that article. Accordingly, we revise and resubmit that paper. It has been 7 months since our resubmission and they still do not give any feedback. Since I am a Ph.D. student, such a long review process is hurting my Ph.D. process. Can anyone suggest me what should be my action in this regard? Should I send the editor an email? If the editor does not respond even after that email, should I withdraw that paper from that journal?

I have submitted an article for a journal in which it was stated that the review time was from 80 to 120 days, that is approximately 4 months at most. The submission of my article was approximately 13 months ago and I did not get any answer in the allotted time they mentioned. I sent an email to the editor after 8 months and I was told that the review process has suffered a delay, but that they soon will fix that issue.  I waited until September and sent another email and again I got another reply of an apology and nothing more. I believe that it has passed too much time, until now it is almost like one year, so I do not what to do.  Would there be any problem if I submit my article to another journal or should I send another email to the editor of this journal? Or rather just wait until I get a response?


Suppose we have a measure $\mu$ and a space $X$ such that $\mu(X)=1$, and a function $f \in L^r$ for some $r > 0$, where $L^r$ is defined in the usual way even for numbers less than $1$.   Show that $lim_{p \to 0} ||f||_p =$ exp$(\int $log$|f|d\mu)$, where we note that exp(-$\infty)=0$ by convention.  Stuck on this one. Trying to use Holder's! Thoughts?

Let ($\Omega$, $\cal{F}$, $\mu$) be a probability space and $f\in L^1(\Omega)$. Prove that  $$\displaystyle\lim_{p\to 0} \left[ \int_{\Omega}|f|^pd\mu \right]^{\frac{1}{p}}=\exp \left[ \int_{\Omega}\log|f| d\mu  \right],$$  where $\exp[-\infty]=0$. To simplify the problem, we may assume $\log|f|\in L^1(\Omega).$


Since a recent Ubuntu update, I have the problem that no icons show up in the desktop (no possibility for me to launch any program / software centre from the desktop...  How could I solve this? Would installing "vanilla Ubuntu 13.04" work?   How to do this from terminal?  I tried typing sudo apt-get vanilla Ubuntu 13.04  but does not work.

I've upgraded to Raring last night. The upgrade itself went okay, no errors. But when I rebooted the computer afterwards and logged in to my Unity session, all I could see was the Desktop background (together with Desktop icons), and no Unity interface. The Super button shortcut wasn't showing the Dash, there was no top panel etc. Please see the screenshot.    As a hint, I'm suspecting it's got something to do with my switchable graphics. I'm running Ubuntu on Acer Aspire AS5830TG with nVidia GT540M and an Intel integrated card. In 12.10 I was using Bumblebee to manage the graphic card switching. During the upgrade I saw something related to nvidia had to be uninstalled, but didn't pay much attention to it. I can't be sure if it has anything to do with my problem though.  What could possibly go wrong?


I am getting the latest OTA update(5.0.1) on my nexus 5, but when the phone restarts and goes to the recovery for the installation of the downloaded file, just 25% into the installation it gives me a error. I do not know what is going wrong. please help

I updated to 5.0.1 via OTA sometime ago, and it worked fine. Now I got a notification that 5.0.2 is ready but when Android shuts down to install update it returns error (with no other message. My Nexus 7 is rooted but has the stock recovery.  Is there an easy fix that doesn't require factory reset or installing recovery?


I have built a multiclass perceptron, which predicts the values of the Iris dataset. To more accurately classify the data points of the Iris Dataset, I used a Kernel to define a non-linear manifold learning technique. Specifically, I created a non-linear version of PCA to project the data onto a high-dimensional subspace. After that, I used grid-search to find the best combination of the hyper-parameters. First question: How do I exactly find the best combination? Is it the smallest number of Principal Components and highest accuracy attained? Second question: Is the data linearly separable? I am getting good results (high 90s) when I'm predicting with Principal Components in the range 1-60, and all gammas. Here is a heatmap:  So is the data linearly separable or not? And why? (I have seen , and it does not answer my question)

The data has many features (e.g. 100) and the number of instances is like 100,000. The data is sparse. I want to fit the data using logistic regression or svm. How do I know whether features are linear or non-linear so that I can use kernel trick if non-linear?


Is it correct to say, the team that will be attending with me is listed below: or should I say the team that will be attending with me are listed below

I'd say Microsoft have a way of bending the rules and I know that McLaren have won the championship. While this sounds strange, I believe it is correct English (sorry, I'm not native).   But when it's a small company, would you still use it this way? Is a company always plural, or are small companies singular? I.e., would you say Bakery Johnson makes fine bread or Bakery Johnson make fine bread? Is it My book seller, Woody's, have moved or is it has moved?


I ran this commands in Terminal and I didnt get any error:  sudo passwd root   and after setting password I ran this command:  sudo passwd -u root   but when I log off or reboot there is no root account!! please somebody tell me how can I login as root in ubuntu 12.04!

I have installed 12.04 LTS but surprisingly not able to login as root. I have unlock and set the password for root but while login i can not see 'other' option in GUI login where i can put root id and password.  please help me.


I am trying to use UnixTree (www.unixtree.org) on Ubuntu 16.04 LTS via the Ubuntu Terminal.  If I run the application "xt" I get the following error:  $ xt No term file or database entry found for term "xterm-256color" xt: cannot initialize terminal.   I got around this error by setting:  $ export TERM=xterm $ xt   And the application starts. However, it starts in the same color scheme as the terminal itself, which makes the application unusable since the color highlighting of selection is critical to its use as seen in image .  Screenshot of my view:   I tried launching the application using the following option according to the UnixTree manual:  $ xt +w   Which should launch UnixTree in a new window, with full color and mouse functionality but it does not work, the application still opens in the same window without color.  I also tried launching the application from xterm itself, but it appears black/white as well, same as xterm itself.  However, I prefer to use Ubuntu Terminal at this time.  Anyone have any suggestions? Thanks!

I am using Xilinx' petalinux tools to build and use embedded linux. My host development machine is a VM running Ubuntu 14.04.1 LTS. My board is a Xilinx ZC706 with a Xilinx Z7045 Zynq SoC.  When issuing a certain command (petalinux-boot --JTAG -- Whatever/option/I/use), I get a warning back that says   rlwrap: $TERM is xterm but rlwrap can't find it in the terminfo database.  Expect some problems. Inappropriate IOCTL for device   I have googled and researched enough to know that rlwrap is a readline wrapper which is just wrapping up commands. I understand that $TERM is the environment variable that tells applications what kind of terminal (or more specifically, the terminal interface specifications) with which it must interact, and that terminfo is a database that contains the actual interface specs (/r /n color or not, whatever).  When I run ls /usr/share/terminfo/x there are probably 20 or 30 variants of xterm-XXXXX or xtermX, but there is not a file named xterm. I am currently of the opinion that this is probably the cause for the above warning.  When I get the above warning it is during the process of either downloading a bitstream to the FPGA part of the device or when using the Xilinx' XMD (xilinx microprocessor debugger) to download the linux image to the Processor side. These processes use an embedded JTAG module that is connected to my host via a USB cable.  How do I get/install a plain xterm entry into the terminfo database?


I made a bullet physics simulation in blender game where a bullet moves by use of key framing and collides with cell fractured objects.   The objects are two rectangles and I used game logic bricks to stop the simulation of the objects until the bullet reaches them. The simulation works fine when I press P, and it appears to be recording correctly, but when I try to press the play button underneath the timeline after I end the game it doesn't play what I just recorded.   It usually plays back the simulation as if the logic bricks were not being used (the cell fractured objects fall before the bullet reaches them). My goal is recording the animation and rendering it using Cycles.  My simulation is very similar to the .

I am having trouble getting the Record Animation setting to work in the BGE. Is it possible to record animated characters that are controlled using BGE's logic bricks with some script? In my script I change the positions of the characters bones.


The question is the title. But I'm quite doubtful if this question is meaningful or not. Since this constant is obtained by experiment, we can  never know its exact value, unlike $π$ or $e$. Is it correct?

Just as circumference of circle will remain $\pi$ for unit diameter, no matter what standard unit we take, are the speeds of light and sound irrational or rational in nature ?   I'm talking about theoretical speeds and not empirical, which of course are rational numbers.


If I had a Lagrangian of the form  $$ \mathcal{L} = (\partial_{\mu}\phi,\partial^\mu \phi)-U[(\phi,\phi)]$$  where $\phi = (\phi_1,\phi_2,\ldots,\phi_n)$ is an $n$-dimensional vector of complex fields, and $(u,v)=v^\dagger u$ is the usual  inner product, how do I know what the symmetry group is? At first glance I would say $SU(n)$ as it will preseve the inner products, but surely an $n$-dimensional unitary representation of ANY group would preserve the inner products too?

I'd like to know whether, given a system, there's a way to obtain all the conserved quantities. For instance if the system consists of electric and magnetic fields, the fields must satisfy Maxwell's equations. These equations are invariant under many transformations (Lorentz transformation, rotations, spatial and temporal translations, etc. By the way is there a way, maybe from group theory, to find all the possible transformations that leaves the equation(s) invariant?) which imply as many conserved quantities thanks to Noether's theorem. In wikipedia I can see an equation that seems to give all the conserved quantities () but it involves the Lagrangian and I'm not sure whether the formula is valid for all systems whose Lagrangian is possible to obtain.


I've been trying to find this series. I remember it came up as a possible solution to a different Identification question on this Stack, but I can't find it now.  Edit:  It was a book, and it was pulp fiction style if memory serves.  Someone below suggested The Number of The Beast, and I believe that to be correct.

I remember a thread here in the SciFi Stack Exchange about the longest sci-fi series. Someone mention a standalone Heinlein book that seemed to somehow include all other books ever written in its story. Does anybody know which book is that?


I'm trying to install KDE 5 on my Ubuntu 16.04 system as per the instructions in , but I'm getting the below error message when running sudo apt-get install kubuntu-desktop.  Is there something I can do to resolve this?  Need to get 682 kB/326 MB of archives. After this operation, 1,272 MB of additional disk space will be used. Do you want to continue? [Y/n] y Err:1 http://ir.archive.ubuntu.com/ubuntu xenial/universe amd64              gtk2-engines-oxygen amd64 1.4.6-1ubuntu1   Temporary failure resolving 'ir.archive.ubuntu.com' Get:2 http://ir.archive.ubuntu.com/ubuntu xenial/universe amd64              libkf5sendlater5 amd64 4:15.12.3-0ubuntu1 [45.2 kB] Get:3 http://ir.archive.ubuntu.com/ubuntu xenial/universe amd64              libthreadweaver4 amd64 4:4.14.16-0ubuntu3 [46.6 kB] Get:4 http://ir.archive.ubuntu.com/ubuntu xenial/universe amd64              libfarstream-0.2-5 amd64 0.2.7-0ubuntu1 [192 kB] Fetched 284 kB in 1min 9s (4,093 B/s)         E: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/pool/universe/g/             gtk2-engines-oxygen/gtk2-engines-oxygen_1.4.6-1ubuntu1_amd64.deb               Temporary failure resolving 'ir.archive.ubuntu.com'  E: Unable to fetch some archives, maybe run apt-get update or              try with --fix-missing?

Err http://archive.canonical.com natty InRelease     Err http://security.ubuntu.com oneiric-security InRelease                Err http://extras.ubuntu.com natty InRelease                             Err http://security.ubuntu.com oneiric-security Release.gpg   Temporary failure resolving ‘security.ubuntu.com’ Err http://archive.canonical.com natty Release.gpg   Temporary failure resolving ‘archive.canonical.com’ Err http://extras.ubuntu.com natty Release.gpg   Temporary failure resolving ‘extras.ubuntu.com’ Err http://gb.archive.ubuntu.com oneiric InRelease Err http://gb.archive.ubuntu.com oneiric-updates InRelease Err http://gb.archive.ubuntu.com natty-backports InRelease Err http://gb.archive.ubuntu.com oneiric Release.gpg   Temporary failure resolving ‘gb.archive.ubuntu.com’ Err http://gb.archive.ubuntu.com oneiric-updates Release.gpg   Temporary failure resolving ‘gb.archive.ubuntu.com’ Err http://gb.archive.ubuntu.com natty-backports Release.gpg   Temporary failure resolving ‘gb.archive.ubuntu.com’  Reading package lists... Done W: Failed to fetch http://gb.archive.ubuntu.com/ubuntu/dists/oneiric/InRelease       W: Failed to fetch http://gb.archive.ubuntu.com/ubuntu/dists/oneiric-updates/InRelease   W: Failed to fetch http://gb.archive.ubuntu.com/ubuntu/dists/natty-backports/InRelease   W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/oneiric-security/InRelease   W: Failed to fetch http://archive.canonical.com/ubuntu/dists/natty/InRelease   W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/InRelease   W: Failed to fetch http://archive.canonical.com/ubuntu/dists/natty/Release.gpg  Temporary failure resolving ‘archive.canonical.com’ W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/oneiric-security/Release.gpg  Temporary failure resolving ‘security.ubuntu.com’ W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/Release.gpg  Temporary failure resolving ‘extras.ubuntu.com’ W: Failed to fetch http://gb.archive.ubuntu.com/ubuntu/dists/oneiric/Release.gpg  Temporary failure resolving ‘gb.archive.ubuntu.com’ W: Failed to fetch http://gb.archive.ubuntu.com/ubuntu/dists/oneiric-updates/Release.gpg  Temporary failure resolving ‘gb.archive.ubuntu.com’ W: Failed to fetch http://gb.archive.ubuntu.com/ubuntu/dists/natty-backports/Release.gpg  Temporary failure resolving ‘gb.archive.ubuntu.com’ W: Some index files failed to download. They have been ignored, or old ones used instead.   This is what I'm seeing when I try to run sudo apt-get update. I did an update on my instance yesterday and am now experiencing this.


I am stuck on a problem in Fulton's Representation Theory: A First Course. Exercise 3.39 states:  Let $V_0$ be a real vector space on which $G$ acts irreducibly, $V=V_0 \otimes \Bbb C$ the corresponding real representation of $G$. Show that if $V$ is not irreducible, then it has exactly two irreducible factors, and they are conjugate complex representations of $G$.  I had originally misread the problem and taken $V_0$ to be not only a real $G$-invariant vector space, but a representation of $G$ itself. Proceeding from there, I showed that $V= V_0 \oplus iV_0$, but this is clearly wrong, as these $V_0$ is not complex and these two representations are not conjugate. However, given that $V_0$ is only a real $G$-invariant vector space, I'm not sure how to proceed.

I would like some help with exercise 3.39 from Fulton & Harris' 'Representation Theory A First Course':  Let $V_0$ be a real vector space on which $G$ acts irreducibly, $V=V_0 \otimes \mathbb{C}$ is a complex representation of $G$. Show that if $V$ is not irreducible, then it has two irreducible factors, and they are conjugate complex representations of $G$.  First of all I would like to remark that conjugate complex representations were not covered before in the book, but after a bit of research I believe the statement in the exercise is equivalent to: $V=W \oplus W^*$ for some (complex) irreducible sub-representation $W \subset V$. If I am mistaken please do correct me!  This question was asked here: , but the post got bogged down with notations and since it was so old I decided to ask it again here. It was suggested in the comments of that post that we consider a irreducible (proper) sub-representation $W \subset V$, let $V=W \oplus U$, and show that $U=W^*$, but I don't really see how we can go on...  The only way I have learnt to compute the amount of irreducible factors inside a representation $V$ is by computing $(\chi_V,\chi_V)=\frac{1}{|G|} \sum_{g \in G} |\chi_V(g)|^2$, but since we don't have a corresponding formula (not one that I am aware of) in the real case, I'm not sure how we can prove there are 2 irreducible factors in $V$ here. I am also failing to see how the second statement about the relation between the two factors can follow from the first part.  Any help is appreciated!


I am looking for a method to Enable and Disable the                                           div id="dcalc" and Its children.

   I want to Disable them at loading the page and then by a click i can enable them ?  This is what i have tried   document.getElementById("dcalc").disabled = true;

I was under the assumption that if I disabled a div, all content got disabled too.  However, the content is grayed but I can still interact with it.  Is there a way to do that? (disable a div and get all content disabled also)


Every time I start my computer I need to go to each different virtual desktop that I have and start the applications that I usually use on that virtual desktop, this is specially cumbersome for me because I use two monitors and I need to start two applications per virtual desktop for each monitor and then drag them to the correct monitor.   Is there any way I can automate this task?

I've created an environment where I use 3 different desktop configurations, but every time I reboot, I have to manually open each program in that target desktop to make it look like it did before.   So, I'd like to write a .bat file that can get all my programs running in their appropriate desktops. I'm wondering if something like this is possible:  "C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -desktop:2 "C:\Program Files\My\Other\Software.exe" -desktop:3 ...etc.   Obviously, this example is not real, but I hope there's something similar. I don't care if it's hacky :)


I am getting an error     Attempt to invoke virtual method 'void com.google.android.gms.maps.SupportMapFragment.getMapAsync(com.google.android.gms.maps.OnMapReadyCallback)' on a null object reference     but i have done everything as per site i dont know whats the error please help I have done things in OnViewCreated and used child fragment also still the error is coming  fragment contact us   package com.example.tanis.myapplication;       import android.os.Bundle;     import android.support.annotation.NonNull;     import android.support.annotation.Nullable;     import android.support.v4.app.Fragment;     import android.view.LayoutInflater;     import android.view.View;     import android.view.ViewGroup;      import com.google.android.gms.maps.CameraUpdateFactory;     import com.google.android.gms.maps.GoogleMap;     import com.google.android.gms.maps.OnMapReadyCallback;     import com.google.android.gms.maps.SupportMapFragment;     import com.google.android.gms.maps.model.LatLng;     import com.google.android.gms.maps.model.MarkerOptions;       /**      * A simple {@link Fragment} subclass.      */     public class ContactUs extends Fragment implements OnMapReadyCallback {          GoogleMap map;         public ContactUs() {             // Required empty public constructor         }           @Override         public View onCreateView(LayoutInflater inflater, ViewGroup container,                                  Bundle savedInstanceState) {             // Inflate the layout for this fragment             View v = inflater.inflate( R.layout.fragment_contact_us, container, false );                return v ;         }          @Override         public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {             super.onViewCreated( view, savedInstanceState );             SupportMapFragment mapFragment = (SupportMapFragment)getChildFragmentManager().findFragmentById( R.id.map1 );             mapFragment.getMapAsync( this );          }          @Override         public void onMapReady(GoogleMap googleMap) {             map = googleMap;             LatLng pp = new LatLng(  28.6403159,77.376114);             MarkerOptions options = new MarkerOptions();             options.position( pp ).title( "WebTechniq" );             map.addMarker( options );             map.moveCamera( CameraUpdateFactory.newLatLng( pp ) );          }     }   XML  <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:id="@+id/frameLayout"     android:layout_width="match_parent"     android:layout_height="match_parent"     tools:context="com.example.tanis.myapplication.ContactUs">      <!-- TODO: Update blank fragment layout -->      <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"         xmlns:tools="http://schemas.android.com/tools"         android:layout_width="match_parent"         android:layout_height="match_parent"         android:id="@+id/map1"         tools:context=".MapsActivity"         class="com.google.android.gms.maps.SupportMapFragment" />  </android.support.constraint.ConstraintLayout>

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I'm using a tool called  that creates special Firefox profiles for web apps (like Twitter or WhatsApp) to have them run in Firefox windows resembling Firefox' former site-specific browser feature. Now when I click links in those web apps running in special Firefox profiles, they open as a new tab in the web app window (where the tabs are invisible) - so I would like to have all links open in my default browser (or the default profile of Firefox for that matter) instead. There is an about:config option named browser.link.open_newwindow which supports the following values :  1: Open links, that would normally open in a new window, in the current tab/window. 2: Open links, that would normally open in a new window, in a new window. 3: Open links, that would normally open in a new window, in a new tab in the current window.  Ideally, there would be an option to open those links using the system's default (like using xdg-open on Linux), which would open the link using my default browser / Firefox' default profile. Is there some config item that I'm missing - or an add-on for Firefox that does just that (letting the system handle opening the link)? Does anyone have another idea? Edit:@harrymc linked me this question (thanks!):  (they asked for pretty much the same thing, so my question is a duplicate). The answer was to use an extension named  - and it's almost what I need! Now I can right-click any page or link to open it with another browser (or profile) - but it doesn't automatically open all links with that – Problem not fully solved.

I'd like to have Firefox open Links in another Profile. Preferrably in way that I can set some URLs to open in the same Profile.     My use case:  I've set up a Firefox profile without navigation bar, which holds all my messenger web apps, which is started automatically on startup.  If someone sends me a link via messenger, it is opened in this profile though, which isn't practical without the navbar and in terms of workflow. I'd like to have a setup, where all the internal messenger links(say *) are opened in the messenger profile and all external links are opened in my default Firefox profile.  Is there a way to accomplish this?


event keyword creates two methods add_* and remove_* (its working like property).  what is the difference   public event MyDelegate event1; public MyDelegate event2 { get; set; }   why should use event keyowrd?

What are the differences between delegates and an events? Don't both hold references to functions that can be executed?


Since yesterday I have a problem on my computer. If I open a torrent the download starts and speed gets up to about 300kb/s and then it goes back to 0. Then I lose all connectivity, Windows says there's no Internet connection and the only way to get it back is have to reboot the computer. Once I do that everything works fine unless i start downloading a torrent.  I've been using torrents for 10 years and never experienced anything like this.  What I tested:   It's not the client, it happens with old and new utorrent clients and deluga. It's not the router, all other computers on the network have Internet normally, while I go offline.   This is not a case of low speed because the torrent suck up the connection. Both the torrent and navigation stops and Windows 7 network center says no internet connection, disabling/reenabling the network card has no effect, only reboot fixes it.  Any ideas?

The situation  I download happily torrents with uTorrent for a long time, maybe 12 hours.  Suddenly, I notice my connection stopped working.  When I check uTorrent is still downloading stuff.  When I check other computers in the same network their internet connection works properly.  I can ping other computers in the network, but I cannot ping any remote IP.  What I tried  When I close uTorrent and open it again, it is unable to generate new connections.  Once I disable and enable my network card again connection works again, yay!  Once I open uTorrent again the same problem comes back, buh!  It's only when I restart my computer when the problem is solved and I can happily download torrents again, yay!  I also tried using a cable instead of WiFi, and the problem also happened.  My guess  The problem seems to be generating new connections, since uTorrent keeps downloading once the whole computer cannot use the Internet. And after I restart it, it cannot start downloading anything.   Since it happens with 2 different network cards, the problem doesn't seems to be the network card. Since I restarted uTorrent tons of times, I don't think is that either. So what is between uTorrent and the network cards? Network services, so my guess is that the problem is caused by one of those.   I already restarted my computer this time, but what I'll try next time is to restart all the running network services, and check what happens if I change between LAN/WAN on the fly.  Any help is very welcome ^^


I have finally encountered an exciting TeX-related problem to post here: Using beamer slides with notes, certain parts of my slides disappear in the main slide when the option \setbeameroption{show notes on second screen=right} in combination with the pgfpages package is used.  When i disable the option / only compile the slides without notes, the output is fine. However, using the option, the main slide view is missing text inbetween two itemize-environments as well as an equation.  This is my MWE:  \documentclass{beamer}  \usepackage{pgfpages}  \setbeameroption{show notes on second screen=right}  \begin{document}  \begin{frame} \begin{itemize} \item content \item more content \end{itemize} \note{a note} \pause aaaand \begin{itemize} \item content \item more content \end{itemize} \begin{equation} A \mathbf{x} = \mathbf{b} \end{equation} \end{frame}  \end{document}   My question is: How can I make the annoted slides show the content that disappears when the notes are shown?    What I find exciting about his problem in particular is that for the preview above the nodes, the content missing from the slide is shown!

I have a Beamer presentation with note pages, in which everything renders just fine with pdflatex.   However, when the file is compiled using xelatex (I need to use fontspec), texts in frames after a note page are not visible -- they are rendered in white colour. This problem is reproducible when using Beamer v3.33.  %% Compile with xelatex \documentclass[handout]{beamer}  \mode<handout> { \setbeameroption{show notes} \RequirePackage{pgfpages} \pgfpagesuselayout{2 on 1}[a4paper,border shrink=5mm] }  \begin{document} \begin{frame} A test, A test! \note{ } \end{frame}      \begin{frame} This text does not appear! \note{ } \end{frame} \end{document}   While this problem can be solved by compiling with lualatex, I'm wondering if there's any thing one can do to make it work for xelatex?


I am currently writing an assignment about the Enigma machine, and im wondering how it makes sense that the highest possible ammount of settings is 158,962,555,217,826,360,000, with 10 wires plugged in the plugboard. When i calculate the ammount of settings with 11 wires plugged in, i get 216,767,120,751,581,400,000. This is the calculations i have done: 1054560*((26!)/(4!11!))(((1)/(2)))

I'm trying to calculate the amount of settings the enigma machine has. I have found several sites regarding this topic, but it seems like there are two answers to my question. The first answer is 158,962,555,217,826,360,000 and the second is 107,458,687,327,250,619,360,000. Where the difference is that in the second answer, it has been taken into account that the notched rings on the enigma could be set as well, giving 26 * 26 = 676 more settings than the first answer.   But which answer is the right one, and why? How many possible different Enigma machine settings are there and how can one determine this number?


I'd like to know how can I create a menu like so:   Menu X which appears when a Member X performs a login, for example when a simple user login, a Menu with 4 sections appears but when a Member Y (for example a user as manager) performs a login, instead of Menu X (= simple user menu), this time a Menu Y (menu manager with 7 sections) appears.   any suggestions?

How can I add a Login link to the "Main navigation" menu?  When a user clicks on the link, it should take them to the /user/login page. Once they login, the link should change to say "Logout" instead of "Login".  Is there any way to add such a link?


I downloaded Ubuntu 13.10 iso file. I mounted it and it asked for reboot. After reboot windows started normally. Every time its just asks for reboot and does nothing.

I would like to see a full how-to guide on how to install Ubuntu.


I am having some hard time understanding the concept of field.   I understand the 6 axioms:   Associativity Distributivity Computability Closure Inverses Identities   The exercise I am trying to solve is the following:  Given F is a field, prove for any x belongs to F, x multiply -1 = -x.  P.S. Can anyone give me some tips regarding how to prove this type of questions that involves proofs in a field?

As the title reveals, I want to prove (based on the axioms of field) that $$-a=(-1)\cdot a$$ I've been trying for a while now, but couldn't think of a way to do it and it got me thinking that maybe its does not require a proof, but it doesn't feel right. Any ideas?


Next week I'll be returning a rental car near LAX and waiting for a night flight with Air New Zealand. I expect to be returning the car by 2pm at the latest but checking for my flight doesn't even open until 6pm. I'd like to be free to go around the city and shop, particularly Glendale mall 26 miles away. I want to return the car with as little city driving as possible. I don't fancy lugging my suitcase across town or through a mall so is there some where I can store a bag for a few hours?

I'm traveling to LA for the day and want to do some sightseeing before taking a cruise.  What can I do with my luggage?


I need to rotate of 90 degrees a table of image:   \begin{figure} \begin{tabular}{cccc} \subfloat[caption]{\includegraphics[width = 4.5in]{K2E250ellisse.png}} & \subfloat[caption]{\includegraphics[width = 4.5in]{K2E600ellisse.png}} \\ \subfloat[caption]{\includegraphics[width = 4.5in]{K4E250ellisse.png}}& \subfloat[caption]{\includegraphics[width = 4.5in]{K4E600ellisse.png}}   \end{tabular} \caption{4 x 4} \end{figure}   I tried with adjustbox but it gives me the error :  \begin{adjustbox}{angle=90}     \begin{figure}     \begin{tabular}{cccc}     \subfloat[caption]{\includegraphics[width = 4.5in]{K2E250ellisse.png}} &     \subfloat[caption]{\includegraphics[width = 4.5in]{K2E600ellisse.png}} \\     \subfloat[caption]{\includegraphics[width = 4.5in]{K4E250ellisse.png}}&     \subfloat[caption]{\includegraphics[width = 4.5in]{K4E600ellisse.png}}       \end{tabular}     \caption{4 x 4}     \end{figure}     \end{adjustbox}       ! LaTeX Error: Not in outer par mode.

How can I rotate both a picture and its title in TeX?  Parameter in \includegraphics allows to rotate only a picture.


I'm looping through a counter, finding elements based on the counter value, and binding events to that set that matches the counter.  psuedo code:  for index in counter     find elements of data attribute matching counter     attach click event to that matched query set   js:  var groups = [];  $('.match-me').each(function(){     var group_id = $(this).data('instance');     if(groups.indexOf(group_id) < 0){         groups.push(group_id);     } });  for(var i of groups ){     window['test'+i] = $('*[data-instance=' + i + ']');     window['test'+i].each(function(){         $(this).on('click',function(){               //CONSOLE.LOG OF window['test'+i] OUTPUTS THE LAST MATCHED SET               window['test'+i].css('color','red');         });     }); }   The issue is inside where I am binding the event listening, the variable for the matched set of elements is always the last matched set of elements. I thought that by creating dynamic global variables in window I would escape this problem, but I'm not sure what I'm doing wrong.

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


How to use the batch to send more than 10 emails using callout. I've done a class batch that contains a start that has the query, an execute that has the sendEmail and a finish that has nothing but this is due to that does not work.  global Database.QueryLocator start(Database.BatchableContext BC) {          return   Database.getQueryLocator(query)}        global void execute(Database.BatchableContext BC, List<Contact> scope) {              SES sesEmail = new SES(as3.key,as3.secret);               for(sObject s: scope){                  sesEmail.sendEmail(subRecipients,sender,subject,newBody);          }    //update scope; }

I have been watching how to implement the batch for sending more than 10 email but I get errors. When I send emails I have a limit 5 and also are sent several times to the same user email  global class SendBatchClass implements Database.Batchable<sObject>, Database.AllowsCallouts{     String query = '';      global Batchname(){     }     global SendBatchClass(String newBodyBatch,...){        this.body = newBodyBatch;        try{...}        catch(){...}     }     global Database.QueryLocator start(Database.BatchableContext BC) {          return Database.getQueryLocator(query);     }     global void execute(Database.BatchableContext BC, List<Contact> scope) {         SES sesEmail = new SES(as3.key,as3.secret);         for(sObject s: scope){             sesEmail.sendEmail(subRecipients,sender,subject,newBody);         }     }     global void finish(Database.BatchableContext BC) {      } }


I am just wondering is there Hawking radiation for any object (that has mass) due to its gravity. Base on the Unruh effect and equivalence principle, any object should emit Black-body radiation or Hawking radiation. So you can boil a pot of water by putting it close by a massive object.

It is known that any accelerated observer is subject to a heat bath due to Unruh radiation. The principle of equivalence suggests that any stationary observer on the surface of a massive body should also experience heat bath. Indeed by substituting surface gravity g into the formula for Unruh radiation one can find the black body temperature for a hypothetical hyper-cool planet:  $$T = \frac{\hbar g}{2\pi c k}$$  which is $3.9766×10^{-20}\,\rm{K}$ for Earth  one even can find the time which it will take for Earth to evaporate: $5.69×10^{50}$ years.  Since the heat in the super-cold Earth cannot come out of nothing one should assume that it will come from decay of particles due to a certain mechanism.  Sometimes I heared an argument that an event horizon is needed for Hawking radiation to exist. But this can be countered by assumption of possibility of decay due to quantum virtual black holes (which inevitably should appear due to uncertainty principle, and the more massive and dense body is the greather concentration of virtual black holes inside it will be, eventually becoming similar to the concentration of bobbles inside a body of boiling water). Or just suggest that any massive body due to uncertainty principle can quantum tunnel into a black hole state so to emit Hawking radiation.  So what is the conclusion here?    Can we say that all massive bodies are surrounded by the atmosphere of heated vacuum?   This is a weaker preposition: thermal state of surrounding vacuum does not mean energy transfer if the system is in thermodynamic equilibrium.    Any body gradually evaporates, i.e. transfers its energy to the surrounding vacuum until completely vanishes?   This is a stronger preposition and suggests emission of radiation al loss of mass.


I have a lot of necessary files and documents on USB Drive. when i connect it to other PC it gets to as hidden and .EXE. Are there any way to make  them un hidden and cleaned?

A friend's computer was recently infected with a virus.  I hope the virus has been removed successfully. But, it appears that the virus set the "Hidden" flag on most directories and files on the system.   What's the most convenient way to clear this flag from selected directories and their contents?


Given a model with a closed-form likelihood, what are reasons to use Bayesian parameter estimation instead of maximum likelihood? In other words, what are additional estimation results that you can get with Bayesian parameter estimation but not with maximum likelihood estimation? I am NOT looking for a discussion of the different underlying paradigms but rather something more "tangible". For example, something along the lines of more accurate intervals for predictions or observation-specific parameter estimates for exogenous covariates or handling of missing values or...

If the interest is merely estimating the parameters of a model (pointwise and/or interval estimation) and the prior information is not reliable, weak, (I know this is a bit vague but I am trying to establish an scenario where the choice of a prior is difficult) ... Why would someone choose to use the Bayesian approach with 'noninformative' improper priors instead of the classical approach?


Give all groups of cardinality 12.  What I did:  let G be such a group.  $12 = 2^2.3$ so G has a 2-Sylows $S_2$ and a 3-Sylows $S_3$.  I proved that either $S_2$ or $S_3$ is normal and $S_3\cap S_2=\{e\}$. Therefore:  $G\cong S_2\rtimes S_3$ or $G\cong S_3\rtimes S_2$.  We have $S_2\cong \Bbb Z/4\Bbb Z$ or $S_2 \cong (\Bbb Z/2\Bbb Z)^2$ and $Aut(S_3) = Aut(\Bbb Z/4\Bbb Z)=\Bbb Z/2\Bbb Z$.   Using Chinese lemma, I found the following direct products, $\Bbb Z/4\Bbb Z \times \Bbb Z/3\Bbb Z\cong \Bbb Z/12\Bbb Z,\ \Bbb Z/2\Bbb Z \times \Bbb Z/6\Bbb Z,\ \Bbb Z/2\Bbb Z \times \Bbb Z/2\Bbb Z \times \Bbb Z/3\Bbb Z$. I don't know how to compute $Aut((\Bbb Z/2\Bbb Z)^2)$ in order to find  non trivial morphisms $S_3 \to Aut((\Bbb Z/2\Bbb Z)^2)$ and I have trouble finding non trivial morphisms $S3 \to Aut(S_2)$ and $S_2 \to Aut(S_3)$ in order to find the semidirect products.    Thank you for your help and comments

I have a lot of difficulty understanding this proof we went over in class about classification of groups of order 12.  Let $G$ be a finite group of order $n=p^rm$ where $m \nshortmid p$.  Denote $Syl_p(G)$ as the set of all sylow p-subgroups, and $n_p(G)$ as the cardinality of $Syl_p(G)$.  (1) G has subgroups of order $p^r$. (How do we know this??)  (2) We know all sylow p-groups are conjugate and their number $n_p(G) | m$, by the 2nd and 3rd Sylow Theorems.  (3) We have that $n_p(G) \equiv 1(p). $  Then $n=12=2^2*3^1$ so $n_2(G)|3$ gives $n_2(G) \in \{1,3\}$ and $n_3(G)|4$ so $n_3(G) \in \{1,4\}$ since $2 \not\equiv 1(3)$.  Case 1: $n_3(G) = 4.$ Then the action of G by conjugation on $Syl_3(G)$ gives a homomorphism $f: G \rightarrow S_{Syl_3(G)} \simeq S_4$. $Ker(f)$ consists of $g \in G$ that normalizes all 3-Sylow subgroups. (Why?). Let $P_3$ be a 3-Sylow subgroup. Then the order of $P_3$ is 3. (I don't get that either), and $[G:N_G(P_3)] = 4.$ Thus $P_3 \subset N_G(P_3)$ gives $P_3 = N_G(P_3)$. (I'm lost here...) So $Ker(f) = \cap Syl_3(G) = \{e\}$ (the intersection of the sylow 3-subgroups is trivial. (How did we arrive here...) Thus we conclude that $G$ is isomorphic to a subgroup of $S_4$ of order 12.  To show $G$ is isomorphic to $A_4$, we have that $G$ has 8 elements of order 3: 4 3-sylow subgroups each has 3-1=2 elements of order 3. And $S_4$ has 8 3-cycles meaning f(G) contains all 3-cycles and hence the group they generate, which is $A_4$, so $A_4 \subset f(G)$. But since $|A_4| = 12 = |f(G)$ then $f(G) = A_4$ and $G \simeq A_4$. (Not understanding the first half of the proof, I do not get this part either).  Case 2: $n_3(G) = 1.$ The scope of the question is too large, I will need to post separately to understand the second half, unless the organizational rules of math.stackexchange would require that I post here. In that case, I'll edit the question.  I basically cannot follow the proof because it seems to skip too many steps; it would be helpful if anyone could elaborate case 1 with more reasoning so that I can follow it. Any help would be appreciated; I've spent hours trying to look up and decipher the proof but without any success.


I was working on a bug in some code that I wrote, and the culprit turned out to be this snippet (simplified for the sake of the question):  var a = [1, 2, 3, 5, 4]; // later... function f(arr) {     var sorted = arr.sort();     // other stuff } // later... console.log(a); // logs [1, 2, 3, 4, 5]!   My question is, why does a stay sorted after the function is done? Surely in JS all variables are passed by value as opposed to reference?

The primitive types (number, string, etc.) are passed by value, but objects are unknown, because they can be both passed-by-value (in case we consider that a variable holding an object is in fact a reference to the object) and passed-by-reference (when we consider that the variable to the object holds the object itself).  Although it doesn't really matter at the end, I want to know what is the correct way to present the arguments passing conventions. Is there an excerpt from JavaScript specification, which defines what should be the semantics regarding this?


I put a pokemon in a gym and the gym later on got defeated and replace with another colour. I didn't get any defender bonus from the gym. This happen two times so far.

I understand that in order to receive a reward from a gym, I have to leave a Pokemon there. However, the exact requirements to collect a reward are elusive to me.  I left a Pokemon at a gym earlier after defeating the current team, but it was removed shortly afterwards and I have not received any rewards.  Does the Pokemon have to fend off a certain amount of challengers, or be there for a certain amount of time?  I live in a very populated area and the gyms have a turnover time of minutes, sometimes hours. Nobody holds a gym for very long as far as I can tell.


sudo chmod -R 777 / was entered in an attempt to regain access to directories that were previously accessible, but this caused the SSH connection to be closed and now can no longer be reconnected.  A "Login failed." error is displayed.  The Pi can still be accessed directly.  Any use of sudo returns sudo: /usr/bin/sudo must be owned by uid 0 and have the setuid bit set  How can this be reversed?  What did the permission changes do to cause this?

I was trying to run chmod -R 777 ./ but ended up typing chmod -R 777 / and set 777 on my entire machine. What can go wrong? How can I fix it?


I have been sent a collection of PNG and SVG images with which I should symbolize my points in ArcGIS 10.0. Unfortunately ArcGIS 10.0 doesn´t support PNG when symbolizing points, so I have converted them to EMF files. The background transparency of the images are now lost and are displayed black. How can I make the background of these emf images transparent in ArcGIS?

What open source tools allow for the creation of EMFs that conserve transparency in ArcMap?  I tried VeryPDF and Any DWG to Image Converter, neither on actually gave me a vector file that provided transparency.  Adobe Illustrator is a bit pricey when all I want to do is convert CAD blocks to vector symbols to use as ArcMap markers.  Anyone know of a good software for this purpose?


I'm using a concept in part of my thesis that is not very well-known, so it's good to give an explanation before going through the rest of the thesis. I'm wondering if I can simply give a Wikipedia page reference for it, so that readers who are not familiar with it can have a look at the given page. For example, let's say I'm using some stuff about Quaternions, can I just add a footnote to the page \footnote{} instead of repeating the same material in my thesis?

For example, suppose you're writing an article about triangles, and you want to include a short proof of Pythagoras' theorem, but you can't quite remember how to derive it, so you pop over to:  and check the proof there. It works mathematically, makes sense and is as far as you can tell, correct, so you include it. Now the proof on Wikipedia doesn't have a citation because probably someone has been taught it and copied it over to Wikipedia, but it's still correct. The only thing you could cite for the proof would be Wikipedia, would a citation be ok or should it just be copied down without a citation?  Edit: Ok, there have been many responses. Most with a firm "no", but some giving the reason: "Just get the proof from a book" since it's so common, but suppose then it wasn't a common proof of something. Maybe it's not very well known or something but suppose there is a small Wikipedia page with the correct mathematical proof. How much effort are people going to go to to find a proof in a book when there's a (correct (which we know, becuase it's maths and we can check it)) proof on Wikipedia? Why is it so bad to say: "I found this proof on Wikipedia, and the maths checks out so it doesn't matter who wrote it, it is correct, but that's where I found it." Or if you do find it somewhere else why not say: "Proof taken from Wikipedia and verified by the proof shown in "Triangles and their properties, Nature, 2014, p113 etc..."


How many ways are there to put $50$ unlabeled balls into $100$ labeled boxes? If empty boxes are allowed and you're also allowed to put as many balls as you want into a single box, would the answer be $\displaystyle\binom{149}{50}$?

So the question is how many ways are there to put N unlabelled balls in M labeled buckets.  One way (I think) I figured it out is $M^N$ ways to put each ball, divided by $N!$ permutations of ball ordering we don't care about:  $$M^N \over N!$$  First, is this correct?  Second, is there another way to approach it without using division?  I need to calculate it in a non-prime modulo space so division isn't available.  I really need a recurrence.


When I'm reviewing items I sometimes come across answers like this:     Here's what you are looking for: www.domain.com/resource.aspx   How should one handle these? By adding a comment?

I have often wondered at the practice on Stack Overflow, Server Fault, and the other sites where someone will ask a question and an answer will come in that says Look here: http://link elsewhere. Rarely will the link have exactly the answer necessary -- often it's an entire article -- yet these answers get voted up.  Why is that, exactly? I realize this is subjective, but my own thoughts are that one should try and give the answer (even if the answer is 'no, it can't be done' or 'no, I don't think it can be done' -- very different answers) and then if you have a link that explains it, go ahead and post it within the answer.  What does the community think about this?     For more information, see  in the .


I am using a function to open a first file and to copy the content to another one with some changes. First I look for a symbole that I want to do some changes before it, my problem is that the function is looking for all the same symbole and make changes before all of them. I want from the function to only look for the first occurance of the symbole and to make changes. here is the code:  public static void Trouver(String theInputFileName, String theOutputFileName, String theSymbol, String theExpression ){      int m_IndexDebut = -1;     String m_TmpStr  = null;     String m_OutputString   = "";     boolean m_found = false;      RandomAccessFile m_InputFile = null;     RandomAccessFile m_OutputFile = null;     String m_Ligne = null;     String m_xref = "xref";     try{         // Ouverture du fichier         m_InputFile = new RandomAccessFile(theInputFileName, "r");         m_OutputFile = new RandomAccessFile(theOutputFileName, "rw");          // Lecture Ligne par Ligne         while (  (m_Ligne = m_InputFile.readLine() ) != m_xref ){              // Initialisation de l'index pour une nouvelle ligne             m_IndexDebut = -1;             m_found = false;             m_OutputString = "";             m_TmpStr = m_Ligne;              // On Cherche le "symbole" et on ajoute ce qu'on à ajouter             while ( m_TmpStr != theSymbol && (m_IndexDebut = m_TmpStr.indexOf(theSymbol)) != -1 ){                  m_found = true;                 m_OutputString = m_TmpStr.substring(0, m_IndexDebut).concat(theExpression).concat("\n").concat( theSymbol );                 m_TmpStr = m_TmpStr.substring(m_IndexDebut + theSymbol.length() );              }              // Ajout de la fin de la ligne               if ( m_found )                 m_OutputString = m_OutputString.concat("\n");             else                 // Si aucun symbole trouvé ,Réecriture de la ligne                 m_OutputString = m_Ligne.concat("\n");              // Ajout de cette ligne au fichier sortant             m_OutputFile.write( m_OutputString.getBytes());         }      }catch (IOException e){         System.err.println("IOException : "+e.getMessage());     }finally {         // Fermeture des fichiers         try{             m_InputFile.close();             m_OutputFile.close();         }catch ( Exception e ){          }     } }

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?