Removing a black background to create a transparent image
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"inputenc Error: Unicode char \u8" error while trying to write a degree symbol (invisible character) No matter how I try to do it I always get the following error :      ! Package inputenc Error: Unicode char \u8:­ not set up for use with LaTeX.    I have tried using ­­­$^{\circ}$, \deg, \textdegree, pasting the ° symbol directly, to no avail.  Here is the header of my document, in case one of those could be causing the errors :  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{lmodern} \usepackage[francais]{babel} %\FrenchItemizeSpacingfalse \frenchbsetup{CompactItemize=false} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amsthm} I'm writing a script which shows the git log for a directory when I cd into it. Such a log can be overwhelming, containing hundreds of lines. So far I have been limiting that to a hard-coded 20 lines (... | head -n 20), which is fine on the screen at work, but too much on the smaller MacBook screen at home.  I would prefer the log to take up about half the (vertical) screen on either terminal. And "terminal" also changes: it's Gnome terminal at work, but iTerm2 at home. And I do not use screen or tmux.  How do I find the number of vertical lines available in a terminal from command line? Can ribosomes read ssDNA? My question is whether translation can be done, either naturally or artificially, through a ribosome reading (single-stranded) DNA directly. If not, I would like to know what allows ssRNA to be translated but not ssDNA. Evaluating the sum $\sum_{n=1}^{\infty}\dfrac{(-1)^{n}}{n^{2}}$ I am tasked to evaluate the sum  $$\sum_{n=1}^{\infty}\dfrac{(-1)^{n}}{n^{2}}$$ Using contour integration. This is what I've done so far.   Let $C_{N}$ be the square defined by the lines $x=\pm(N+\tfrac{1}{2})\pi$ and $y=\pm(N+\tfrac{1}{2})\pi$. Let $f=\tfrac{1}{z^{2}\sin(z)}$. I was able to prove that  $$\int_{C_{N}}\dfrac{1}{z^{2}\sin(z)}dz=2\pi i\left[\dfrac{1}{6}+2\sum_{n=1}^{N}\dfrac{(-1)^{n}}{\pi^{2}n^{2}} \right]. $$  By Cauchy's residue theorem. So now if I could prove that he integral converges to zero then I would be done. The problem is that I can't seem to get an upper bound on the integral. I've having trouble with the fact that $|f|$ is unbounded within $C_{N}$ so ML inequality doesn't help me. Any hints would be great. Thanks. Youtube says "This video is currently unavailable" I am in the last year of MSc. and would like to read string theory. I have the Zwiebach Book, but along with it what other advanced book can be followed, which can be a complimentary to Zwiebach. I would like a more mathematically rigorous book or lecture notes along with Zwiebach.   Specifically, mention whether the book discusses string theory   Rigorously? Intuitively?   What's the scope of the book? Does it cover the advanced materials, e.g. Matrix string theory, F-theory, string field theory, etc. Maybe even String Phenomenology? My textbook explains the proof, which I don't understand:  "Consider two bases $v_1...v_p$ and $w_1...w_q$ of V. Since the vectors $v$ are linearly independent and the vectors $w$ span V..."  How exactly does $w$ span V?   The book then says the same for vectors $v$, that $v$ spans V and hence $p=q$, but I don't really understand how you can assume that given two sets of vectors that are basis, one set must span V. Nexus 7 is stuck in reboot loop after full discharge I have a few day old Nexus 7 tablet, unrooted, bootloader still locked, and otherwise in factory condition. This morning, it ran its charge out. When I plugged in it, this happens:   Google Logo appears. Nexus Logo appears. Lock screen which shows charging: 0%. White screen, device powers off. Repeat.   What is happening? Thanks! How can a particle's position be random and uncertain in quantum mechanics if it is already pre-determined in relativity? How do I center the text horizontally and vertically in a TextView, so that it appears exactly in the middle of the TextView in Android? What can I do if my USB flash drive is write-protected or read-only? Putting a piece of code in between two html tags in Solaris Does it make any difference for SEO benefits to buy dropped and already available domains other than backorder domains that are expiring soon?  I heard somewhere that whois gets deleted after being dropped. But I didn't find any confirmation if it's true or not.  Anybody can tell me if there are benefits of one against the other, if yes what? What is the probability that a person is the second person to roll a 6 for the first time? Suppose $A$, $B$, and $C$ roll a die in turns. What is the probability that $A$ is the second person to roll a $6$ for the first time? which app triggers the "Windows features" dialog? I keep getting this window titles "Windows Features" It then says that:     An app on your PC needs the following Windows feature:      .NET Framework 3.5 (Includes .NET 2.0 and 3.0)   and I can choose to install or skip (being warned that my apps might not work correctly).  There is also a "telll me more about this feature" link but it explains about the .NET framework.  I want to know if there is a way for me to know which application is it that asks for this feature as the window just keeps popping out of the context of activating a new app...  This all started just a few days ago after some unattended update on my windows 10. Levels or First Differences, VECM or VAR for Ultimate Impulse Response Functions? How to get method parameter names? Given the Python function:  def a_method(arg1, arg2):     pass   How can I extract the number and names of the arguments. I.e., given that I have a reference to func, I want the func.[something] to return ("arg1", "arg2").  The usage scenario for this is that I have a decorator, and I wish to use the method arguments in the same order that they appear for the actual function as a key. I.e., how would the decorator look that printed "a,b" when I call a_method("a", "b")? Wilcox.test for testing count based data in R studio large W I'm doing a textmining project about a videogame review dataset. I divided de reviews into a positive (reviewgrade > 8) and negative (reviewgrade &lt; 3) and want to draw conclusions based on the frequency of different grading factors mentioned in the text. I now have a dataframe with counts of certain categories mentioned per review.  0    13249 1     1565 2      292 3       65 4       19 5        6 6        4 7        3 8        2 9        1 Name: positive: gameplay, dtype: int64   0    5043 1     348 2      66 3      18 4       8 5       3 Name: negative: gameplay, dtype: int64   For example this are the distributions of the amount of reviews which have a certain amount of mentions of gameplay related words. There are for example 1565 reviews with precisely 1 mention of a word related to the category gameplay.  Now I want to use this data to determine if on average gameplay gets mentioned more in negative context than in positive or vice versa. Because the data is not normal distributed, I assumed a t-test is not appropriate, and found online that a Mann–Whitney U test might be suitable.  &gt; wilcox.test(positive$gameplay, negative$gameplay, alternative = "two.sided", conf.int = TRUE)      Wilcoxon rank sum test with continuity correction  data:  positive$gameplay and negative$gameplay W = 43702925, p-value &lt; 2.2e-16 alternative hypothesis: true location shift is not equal to 0 95 percent confidence interval:  2.963844e-05 4.797412e-05 sample estimates: difference in location            4.995671e-05    I do however get a very high W value, which doesn't seem to be correct. Is this not the appropriate test, or am I interpreting this wrong? Get Edge / Vertex / Face from mouse position What is the difference between "till" and "until"? What is the difference between till and until?    When to use till or until? Please explain with examples.