Incorrect line spacing when text is in curly braces
Why do I have to use \par if I change font size withing a group scope?
Cleaning Circuits with Compressed Air I've been arguing with a colleague whether it is a sensible solution to clean dusty PCBs with compressed air. While I think this is the best solution (nothing touches the PCB), he claimed that spraying off the dust can cause ESD, because the charges that may have accumulated in the dust win't bleed off in the process (and it's better to leave everything as it is). I'm not really convinced by this argument and my (limited) knowledge of ESD production doesn't help getting peace of mind in this matter. What is your input? Find a closed form of the series $\sum_{n=0}^{\infty} n^2x^n$ The question I've been given is this:  Using both sides of this equation:  $$\frac{1}{1-x} = \sum_{n=0}^{\infty}x^n$$  Find an expression for $$\sum_{n=0}^{\infty} n^2x^n$$ Then use that to find an expression for $$\sum_{n=0}^{\infty}\frac{n^2}{2^n}$$  This is as close as I've gotten:  \begin{align*} \frac{1}{1-x} &amp; = \sum_{n=0}^{\infty} x^n \\ \frac{-2}{(x-1)^3} &amp; = \frac{d^2}{dx^2} \sum_{n=0}^{\infty} x^n \\ \frac{-2}{(x-1)^3} &amp; = \sum_{n=2}^{\infty} n(n-1)x^{n-2} \\ \frac{-2x(x+1)}{(x-1)^3} &amp; = \sum_{n=0}^{\infty} n(n-1)\frac{x^n}{x}(x+1) \\ \frac{-2x(x+1)}{(x-1)^3} &amp; = \sum_{n=0}^{\infty} (n^2x + n^2 - nx - n)\frac{x^n}{x} \\ \frac{-2x(x+1)}{(x-1)^3} &amp; = \sum_{n=0}^{\infty} n^2x^n + n^2\frac{x^n}{x} - nx^n - n\frac{x^n}{x} \\ \end{align*}  Any help is appreciated, thanks :) Proof that $A_n$ the only subgroup of $ S_n$ index $2$. I have what seems to me a very simple proof that $A_{n}$ is the only subgroup of $S_{n}$ of index 2.  Since I've seen other people prove it with what feel like really complicated methods (), I'm wondering if I've overlooked something.  Proof: Let $H$ be any subgroup of index 2 in $S_{n}$.  Then $H\cap A_{n}$ is a normal subgroup of $A_{n}$ and since $A_{n}$ is simple, $H$ is either the trivial or the improper subgroup of $A_{n}$.  If it's the trivial subgroup it doesn't have index 2 in $S_{n}$, and otherwise the theorem is proved. Can you make an opportunity attack against a moving object? Is there a simple command for the available height in a beamer slide? Do you capitalize both parts of a hyphenated word in a title? Do you capitalize both parts of a hyphenated word in a title?  "My Ex-Wife Hates Me"  or  "My Ex-wife Hates Me" C# Lambda expressions: Why should I use them? I have quickly read over the  documentation.  This kind of example has helped me to understand better, though:   delegate int del(int i); del myDelegate = x =&gt; x * x; int j = myDelegate(5); //j = 25   Still, I don't understand why it's such an innovation. It's just a method that dies when the "method variable" ends, right? Why should I use this instead of a real method? "I will appreciate your help" I encounter the phrase "I will appreciate your help" from time to time and it doesn't sound too honest to me. To be more specific, I don't have a problem with this phrase coming from a friend, because he will appreciate my help by "owing me one". But a stranger from the Internet, that's different, methinks.  "How will you appreciate it?" pops in my mind every time I see it, because to me, appreciation equals reward and, well, you can't reward people over the internet much. It is quite possible that I am just wrong and this is a perfectly fine figure of speech. Exclude TeX.SE question titles from MathJax parsing in Hot Network Questions Recently, the TeX.SE question  got onto the Hot Network Questions list.  Like many questions on TeX.SE, it contains some TeX markup in its title.  Unfortunately, on , this markup gets parsed and rendered as math:    I propose that either:   the entire Hot Network Questions sidebar should be excluded from MathJax parsing by styling it with the tex2jax_ignore class, or at least, any hot questions from TeX.SE should be so excluded from MathJax parsing.   Or I suppose we could always implement , which asks for all questions with TeX in the title to be excluded from Hot Network Questions entirely.  That might be throwing out the baby with the bathwater, though.    Ps. This issue is partially masked by , which causes MathJax not to be rendered in many elements that are hidden by default and revealed using jQuery .show(), such as all but the first five questions in the Hot Network Questions sidebar.  The  user script contains a generic fix for that bug, so users who have it installed will see this issue more frequently, but it occurs even without SOUP whenever a question with TeX markup in the title happens to show up among the top five hot questions that are always visible by default. How do I bypass restrictions on the length of the PATH variable I had some NEF files in a folder that I didn't do anything with. When importing them in Lightroom, no previews and a "file unsupported or damaged message" So I tried with Nikons ViewNX, nothing. Even not in DxO or PhotoMechanic.  I had a look with EXIFTool and the corrupt file prints me only this:  ExifTool Version Number         : 8.39 File Name                       : _DSC5559.NEF Directory                       : /Users/tunafish/Desktop File Size                       : 12 MB File Modification Date/Time     : 2010:11:29 12:46:56+01:00 File Permissions                : rwxrwxrwx Error                           : File format error   I saw another question on photo.stack  and tried to copy over the makernotes from a good file (_DSC5556.NEF) with  exiftool -tagsfromfile _DSC5556.NEF -makernotes _DSC5559.NEF   but EXIFTool gives me this error  Error: Not a valid TIFF - _DSC5559.NEF 0 image files updated 1 files weren't updated due to errors   I have uploaded 2 NEF's, with _DSC5559.NEF being the corrupt one here: Geometric interpretation of $\frac {\partial^2} {\partial x \partial y} f(x,y)$ I play on the DivineJourney modpack with a friend, but he wants to constantly spawn things in. Is there any way to allow him to be able to use the teleport command, but not be able to spawn in items?  I've already locked the NEI mode to Recipe.  I've looked around for a mod for plug-ins for Forge (as thats what the server is on) but I couldn't find anything thats up to date. I found Sponge, but thats for 1.8+, and I need 1.7.10. Integral of $\int \frac{dx}{\sqrt{x^2 -9}}$ I wish to display a map in QGIS (world country shapefiles) showing all countries but centered on the Pacific area.   I am not familiar with Proj4, so is there any way this can be done in QGIS? I am doing some forecasting in R using Rob Hyndman's forecast package. The paper belonging to the package can be found .  In the paper, after explaining the automatic forecasting algorithms, the authors implement the algorithms on the same data set. However, after estimating both an exponential smoothing and ARIMA model they make a statement I do no understand (on page 17):     Note that the information criteria are not comparable.    I thought that an advantage of using AIC for model selection is that we can compare AIC values from different models, as long as they are estimated using the same data set. Is this incorrect?  This matter is of particular interest to me, as I was planning on combining forecasts from different model classes (e.g. exponential smoothing and ARIMA) using so called Akaike weights (see Burnham and Anderson, 2002, for discussion on Akaike weights)  References   Burnham, K. P., &amp; Anderson, D. R. (2002). Model selection and multi-model inference: a practical information-theoretic approach. Springer Verlag. ToList()-- does it create a new list? Is a clean install better than upgrading? Update: Failed to lock /var/cache/apt/archives/lock I'm talking about the movie  Spoilers ahead.  Walter (Daniel Radcliffe) gave the task or blackmailed the Four Horsemen to steal a chip from a lab which can access any digital device. So they did steal the chip. And when they rescue Dylan Rhodes (Mark Ruffalo) from drowning in the water, Jack Wilder said that the chip is fake.     Jack: Wait something is not right.      Atlas: What's wrong?      Jack: It's fake.   Then they assumed that Walter did not know that the chip is fake. So they came with a plan to bluff. They pretended that they had the real chip. After they got caught by Walter, they gave the fake chip to Walter. Walter checked the chip and declared it as real. The Four Horsemen were surprised.     Walter: I'm sorry to interrupt. But I have to say congratulations and   thank you. It's real.      Lula: What? It's real!!!!!      Atlas: What? Is it real?      Jake: What is he talking about?   What happened? I didn't get it. What did I miss? Was the chip real? Was Walter pretending it to be real? If so, then why? If not, who switched the real chip with the fake one? Who had the real chip before?