I am working on a xamarin application where I have to download a PPT file and opened the downloded ppt file from PowerPoint app (if available on a device)
What is a simple way of downloading a file from a URL path?
Gravitational slingshot of light using a black hole/massive object Wikipedia has this page on  using planets. In some cases this effect was used to accelerate the spacecraft to a higher velocity. This diagram shows this in a very oversimplified manner.   That got me thinking that if light is affected by gravity, and if it slingshots around the black hole/massive object, can't it gain a higher speed than $c$? What limitations are stopping it from doing this?  Forgive me if the answer to this question is pretty straight-forward or staring-you-in-the-face kind. I haven't fully understood the mechanics of the gravitational slingshot fully yet, but I couldn't wait to ask this. Note: If it is possible (I highly doubt that!), could you provide an explanation using Newtonian mechanics, I'm not very familiar with general relativity because I'm in high school. Error with square bracket in table \begin{table}[ht] \makebox[\textwidth][c]{     \begin{tabular}{ccccc}         \hline         \hline         [] &amp; [] &amp; [] &amp; [] &amp; []\\         [] &amp; [] &amp; [] &amp; [] &amp; []\\         \hline         \hline     \end{tabular} } \caption{test} \end{table}   I cannot run the above code, latex returned an error about missing number, but I can't see anything I am missing.  And the weirdest thing is that  \begin{table}[ht] \makebox[\textwidth][c]{     \begin{tabular}{ccccc}         \hline         \hline         [] &amp; [] &amp; [] &amp; [] &amp; []\\         \hline         \hline     \end{tabular} } \caption{test} \end{table}   This code works.  Anyone have any idea? How do you performance test JavaScript code? Is there an alternative to string.Replace that is case-insensitive? I need to search a string and replace all occurrences of %FirstName% and %PolicyAmount% with a value pulled from a database. The problem is the capitalization of FirstName varies. That prevents me from using the String.Replace() method. I've seen web pages on the subject that suggest  Regex.Replace(strInput, strToken, strReplaceWith, RegexOptions.IgnoreCase);   However for some reason when I try and replace %PolicyAmount% with $0, the replacement never takes place. I assume that it has something to do with the dollar sign being a reserved character in regex.   Is there another method I can use that doesn't involve sanitizing the input to deal with regex special characters? Acount suspension reason is only shown on the main site profile not meta Disable chat migration notification if one of the users has insufficient rep? I shall assume that the sun is at rest, so before the half mass disappear, the orbit of earth is an ellipse. How to keep VLC player in minimized mode? I'm using VLC media player which can play almost all kinds of audio and video formats. While listening to audio, I keep VLC in minimized mode and can work on other windows. But when I select to listen video songs mixing with audio songs, VLC is maximizing itself to play every video song in the playing list, which is really annoying in the middle of work.  So how can I keep always VLC player in minimized mode while playing a list of songs mixed with audio and video songs? How to show that the commutator subgroup is a normal subgroup What's the starting wealth for higher levels? How to install Gnome 3 without breaking Unity? I tried installing gnome 3 , but it broke Unity and I had to reinstall Natty from scratch.  Does anyone know if there is a way to install Gnome 3 without breaking Unity? I'm having trouble finding something to clarify this. It's been mentioned in the Difficulty Class section of the DMG (238) that there should be a 50/50 chance that an average person can succeed at a DC 10 challenge, implying you have to beat it. However, I'd always thought that there's a 50/50 chance for an average person to hit another average person, but the chance is really 55/45, since you only have to equal their AC. Based  I'm trying to setup Tomcat Server, I have successfully installed it and tested it. Then I stopped it as recommended in the tutorial. I'm setting up "New Server Runtime Environment" as you can see under Tomcat Installation Directory is a windows directory, anyone knows the Ubuntu directory equivalent for this? Thanks. Can I update an early Airport Time Capsule? css vertical centering how could i vertically center a &lt;div&gt; within a &lt;div&gt; ?  my code so far:  &lt;div style="height:322px;overflow:auto;"&gt;     &lt;div style="border: Solid 1px #999999;padding:5px;"&gt;     &lt;/div&gt; &lt;/div&gt;   i have tried "top:50%;" and "vertical-align:middle;" without success  EDIT: okay so it's been discussed a lot. and i've maybe started another mini flame war. but for argument sake, how would i do it with a table then? i've used css for everything else so far so it's not like i'm not trying to employ "good practices".  EDIT: the inner div does not have a fixed height How can I set a dark theme in TeXstudio? After perusing , I'm considering switching from TeXmaker (in which I use the preset "dark theme") to its fork, TeXstudio.  What I mean by "dark theme" is a dark background with suitable text colours, which, in my experience, is easier on the eyes than a bright background is. Here is an example:    TeXstudio doesn't seem to offer any preset dark theme, though, which means I have to customise all the colours/syntax-highlighting settings from scratch to get a dark theme even remotely usable. This can prove very time-consuming.   I'm aware this might sound a bit cheeky but,   if you are a long-time TeXstudio user, and you have fine-tuned the editor colours to get a visually pleasant dark theme,   please consider posting the relevant lines from your settings (.txsprofile or .tmxprofile) file as an answer below.  TeXstudio users who would like to use a dark theme could then build on your settings to fine-tune their own. Determinant of a $2\times 2$ block matrix I would like to know the proof for:  The determinant of the block matrix $$\begin{pmatrix} A &amp; B\\ C&amp; D\end{pmatrix}$$ equals $$(D-1) \det(A) + \det(A-BC) = (D+1) \det(A) - \det(A+BC)$$ when $A$ is a square matrix, $D$ is a scalar, $C$ is a row vector and $B$ is a column vector.  I appreciate your help. Splitting all lines in layer at vertices using QGIS I want to automatically split all lines in a QGIS layer at their vertices (). I've done a Google search and found , which is quite close but the workflow is complicated. Because I'll have to train my co-workers (who are unfamiliar with GIS) to use this tool, I want something as simple as a plugin or something that doesn't require GRASS. Since it's been a long time from 2010 - the time of , I wonder if there is any better way to achieve the same result? Support showing image in original size in overlay Bring back review numbers to the top bar Though I never quite understood what those numbers were and they were quite ugly, they were the only reason I ever visited the reviews page.   Can we have similar functionality back on the top bar please?