Photons speed limit
Why do universal constants have the values they do?
Solutions for INSERT OR UPDATE on SQL Server Assume a table structure of MyTable(KEY, datafield1, datafield2...).  Often I want to either update an existing record, or insert a new record if it doesn't exist.  Essentially:  IF (key exists)   run update command ELSE   run insert command   What's the best performing way to write this? How do I list the default installed packages? I am developing an offline installer for all versions of Ubuntu, and I need Ubuntu's default installed packages list. Is there a way to get this information from any server (web server)? Any script to fetch any Ubuntu version's default installed packages list.  I will give the Ubuntu version, and the script will fetch the packages list.  Note: I need at least a server address. I can write a script for this. optimality of the Carnot cycle At the end of the movie we are shown      a bowl with berries in it and Seneca Crane looked like he was locked in a room with them and was supposed to eat them. Did he eat them?   Why did that happen? iPhone 7 Plus takes days to turn on showing Apple logo or black screen I’ve had this issue for months but in the last couple of days it’s got very very bad.  When my phone runs out of battery it needs like 2–3 days to turn back on. At the beginning of this problem the phone would need about 1h. Every time when my phone goes off again the time to switching on goes up.  What does this all look like? Well, when my phone died I put it on the charger, then the logo appears and goes off. When it goes off, a black screen pops out with a little white line on in it, then it turns on back to Apple logo. It keeps doing this until it turns on which is 1 or 2 even now 3 days.  I tried to restore it and also update it but nothing happens, literally nothing happened. Bold brackets in equations I want to write an equation with bold extended brackets.  For instance in:   \left[ \frac{1}{2} \vec{\nabla} \times \vec{v} \right]   I want \left[ and \right] to be bold. I already tried  nothing is doing the trick. I almost remember it but not really Is there a word for the feeling/situation where we almost remember a thing/word/scene,etc. but are not able to exactly recall it. For example, the other day I was trying to recall the author of the book Contact (i.e. Carl Sagan). I wasn't able to exactly recall 'Carl Sagan' but was in that situation where I could feel I almost remember it. I could recall there was the letter 'C' in his name. Finally after some effort I could recall the exact name 'Carl Sagan'. Is there any word for such a feeling/situation? EDIT:  The feeling is not necessarily of trying to remember a single word(as in from vocabulary). It could be trying to remember a movie or an experience that you were a part of, etc. Eg: If say I was with friends and we were having a conversation. After few days I was able to recall a statement said by someone, but wasn't able to remember by whom; i.e. I had a clouded recollection and I could almost remember but not really. How can I transform the elliptic curve $E/\mathbb{C}$ of the form $$y^2=4(x-e_1)(x-e_2)(x-e_3)$$ with $e_1&gt;e_2&gt;e_3\in\mathbb{R}$ roots of $E$ into a Weierstrass-Form $y^2=x^3+ax+b$? limit of integral $n\int_{0}^{1} x^n f(x) \text{d}x$ as $n\rightarrow \infty$ I am trying to solve the following problem at the level of a senior undergrad analysis level. So, the problem is as follows: We are given a function $f$ which is continuous on the interval $\left [ 0,1 \right ]$, and the question is to find the limit: $$\lim_{n\rightarrow \infty}\int_{0}^{1}x^{n}f(x)dx\;.$$ The second part of the problem is to deduce the following limit: $$\lim_{n\rightarrow \infty}n\int_{0}^{1}x^{n}f(x)dx\;.$$  For the first part: I just did the following: For every $0\leq x&lt; 1$: $x\leq M$, where $0&lt; M&lt; 1$. Then: $$\int_{0}^{1}x^{n}f(x)dx\leq M^{n}\int_{0}^{1}f(x)dx\;.$$ Then: $$\lim_{n\rightarrow \infty }\int_{0}^{1}x^{n}f(x)dx\leq \lim_{n\rightarrow \infty }M^{n}\int_{0}^{1}f(x)dx= 0.\int_{0}^{1}f(x)dx=0\;,$$ so $$\lim_{n\rightarrow \infty }\int_{0}^{1}x^{n}f(x)dx=\lim_{n\rightarrow \infty }f(1)\int_{0}^{1}1dx=f(1)\;.$$ Does that make sense? If not, please show me the correct one.  As for the second part, I have no idea what to do. Any help? How to identify unused CSS definitions from multiple CSS files in a project A bunch of CSS files were pulled in and now I'm trying to clean things up a bit. How can I efficiently identify unused CSS definitions in a whole project? How to bypass "Verify your account" (Factory Reset Protection) How do I run a command before or after every command written in the console? Fitting an infinite collection of balls in an infinite dimensional unit ball Given an infinite dimensional normed linear space, how would one show that it is possible to fit an infinite collection of non-overlapping balls of radius $\frac{1}{4}$ in the unit ball?  I guess one can immediately reduce the problem to a normed linear space of countably infinite dimensions. The solution seems clear if the concept of orthogonality exists, but not every normed linear space has an inner product so it's not possible to apply something like Gram-Schmidt to produce an orthogonal basis. Is there any way around this, or there another approach that can be used? How do I fix "Error C1033: cannot open program database"? How does accepting an answer work? What does it mean to accept an answer? How do I accept an answer, and what are the rules? Can I accept my own self-answer? What are the reputation benefits? Which answer should I accept? Should I upvote the accepted answer? What should I do if none of the answers are suitable?      For more information, see "" in the . Pandemic, Global Epidemic, Epidemic, Endemic I really want to hear from the experts the definitions of all 4 terms especially whether global epidemic is equivalent to pandemic. Or should this question be directed to the epidemiologist?   Pandemic Global Epidemic Epidemic Endemic   I have Googled the terms and I understand the definition of 1), 3) and 4). In short the definition is based on geographical location and scale of outbreak, Pandemic is an outbreak of disease on a global scale (e.g. HIV). Epidemic is an outbreak of disease on a localised area. Endemic is a disease in a localised area. However, a definition for Global Epidemic is not available online.  Recently, WHO mentioned that "“It is important to put this on the table: this virus(Covid19) may become just another endemic virus in our communities, and this virus may never go away,” WHO emergencies expert Mike Ryan told an online briefing." Isn't covid19 considered a pandemic since it is on a global scale and is spreading rapidly?  Another term that I come across often is Global Epidemic. For example in the WHO website, HIV is listed as Global Epidemic. Does that mean Pandemic and Global Epidemic are the same? I thought the way to undo a \def was to define it to \relax, but that does not appear to work.  Also, am not sure why this produces no output if I try to use \def instead of \let in my attempt to do an undef.  \documentclass{article}  \begin{document}  \def\CaseA{}%  \ifdefined\CaseA%     \def\ProcessCaseA{}%     % Do stuff that uses \ProcessCaseA     %\def\ProcessCaseA\relax% no output if use this, and comment next line     \let\ProcessCaseA\relax% no output if comment this, and use above line \fi  % Now do stuff that requires \ProcessCaseA NOT be defined \ifdefined\ProcessCaseA     ERROR: \textbackslash ProcessCaseA is still defined \else     SUCCESS: \textbackslash ProcessCaseA is not defined \fi  \end{document} How do I download with youtube-dl to get video title as filename? I'm reading .     The graph of $f: A \rightarrow B$ is the subset of $A × B$ consisting   of all ordered pairs $(a, b)$ with $f (a) = b$. If $A$ happens to be   $B^n$ for some $n ∈ N$, then we say that $f$ is a function on $B$ and   $n$ is the arity of $f$.   I don't understand the notation for the exponent of a set, I'm aware of what  is, it's the number of arguments or operands the function takes. I'm just not so sure if I can assume that a set with an exponent such as in $B^n$ means that a function has two operands.  I know the question may be too naive and perhapes the answer is the one I suggested and it's right in front of my face, I'm just searching for a confirmation or the negation of it. Thanks. Globally disable "include online search results"