Why do I need an empty `content` property on an ::after pseudo-element?
Why do the :before and :after pseudo-elements require a 'content' property?
Serana disappeared during dawnguard questline. JavaScript editor within Eclipse How can I abort a running JDBC transaction? Is there a way to prematurely abort a transaction? Say, I have sent a command to the database which runs five minutes and after four, I want to abort it.  Does JDBC define a way to send a "stop whatever you are doing on this connection" signal to the DB? Why does Skynet take prisoners? In the Terminator franchise, extermination camps are often mentioned. But from a machine-logic POV, wouldn't it make more sense to just kill all humans on sight, period? Or herd them into small areas and nuke them? (even today's military electronics are hardened against EMPs and Skynet wouldn't care about the environment.)   IIRC, the reasoning behind ghettoization / concentration camps / extermination camps / gas "showers" is to misdirect or mislead people both inside and outside the country as to what was really going on. But Skynet doesn't have to worry about bad publicity, and can manufacture all the free labor it needs. Is there any in-universe explanation for keeping large groups prisoners? I remember reading this book back in late 90's. It is about a slave that gathers some friends and goes into a desert to find/fight a dragon. There is also a revolt/uprising in the slaves' home town. I can't remember if this is a single book or a trilogy.  I think the rulers were called Sorcerer-lords or Sorcerer-Kings. And I remember one character was called Boris or Borys. Sum of two co-prime integers I need some help in a proof: Prove that for any integer $n&gt;6$ can be written as a sum of two co-prime integers $a,b$ s.t. $\gcd(a,b)=1$.  I tried to go around with "Dirichlet's theorem on arithmetic progressions" but didn't had any luck to come to an actual proof. I mainly used arithmetic progression of $4$, $(4n,4n+1,4n+2,4n+3)$, but got not much, only to the extent of specific examples and even than sometimes $a,b$ weren't always co-prime (and $n$ was also playing a role so it wasn't $a+b$ it was $an+b$).  I would appriciate it a lot if someone could give a hand here. how to get full path from fileupload using Javascript Can I access constants in settings.py from templates in Django? I have some stuff in settings.py that I'd like to be able to access from a template, but I can't figure out how to do it. I already tried  {{CONSTANT_NAME}}   but that doesn't seem to work. Is this possible? Story about a utopian city that periodically destroys itself I was skimming through  by Cosma Shalizi (in particular, section 2.1.1 of the ), and was reminded that you can get very low $R^2$ even when you have a completely linear model.  To paraphrase Shalizi's example: suppose you have a model $Y = aX + \epsilon$, where $a$ is known. Then $\newcommand{\Var}{\mathrm{Var}}\Var[Y] = a^2 \Var[x] + \Var[\epsilon]$ and the amount of explained variance is $a^2 \Var[X]$, so $R^2 = \frac{a^2 \Var[x]}{a^2 \Var[X] + \Var[\epsilon]}$. This goes to 0 as $\Var[X] \rightarrow 0$ and to 1 as $\Var[X] \rightarrow \infty$.  Conversely, you can get high $R^2$ even when your model is noticeably non-linear. (Anyone have a good example offhand?)  So when is $R^2$ a useful statistic, and when should it be ignored? How do you disable anonymous login? How do I make a Villager Trade a Spawn Egg Why is this simple Excel calculation not netting Zero? Does $\sum_{k=1}^\infty\frac1{k^n}$ converge for $\Re(n)=1,\Im(n)\ne0$?  The ratio test is inconclusive.  It passes the term test for $\Re(n)=1$, but this is not sufficient to prove convergence.  Since we are dealing with so many complex numbers, I do not know of any convergence tests for this.  I know that if it is convergent, it is conditionally convergent. What would happen if every person in the world gathered at a minimum possible area and jumped all at once? Would that have any effect on Earth? What is the limit of this sequence? How does it relate to the exponential function? Find $$\lim_{n\to\infty} \left(1+\frac{x^2}{n^2}\right)^n$$   I particular, I am hoping to find the above to be $1+x^kg(x/n)$ where $g(\cdot)$ is a function with uniformly bounded derivatives.  Edit: I'm trying to prove a result that would be true if  $(1+x^2/n^2)^n -1 = x^kO(x/n).$ ls -la symbolics... what does that last symbol mean? Deriving curvature formula How do you derive the formula for unsigned curvature of a curve $\gamma (t) = (x(t), y(t)$ which is not necessarily parameterised by arc-length.   The formula given is $$|\kappa (t)| = \left|\frac{x'' y' - y'' x'}{((x')^2 + (y')^2)^{3/2}}\right|$$  All the definitions of curvature in my notes give it in terms for an arc-length parameterisation $T'(s) = \kappa(s) N(s)$. This is apparently meant to be 'easily derivable', am I missing something? Why does putting a 1/2 in front of the squared error make the math easier? How can I check dependency list for a deb package How can I check dependency list for a deb package. I am running Ubuntu 11.10 and I have backed up all deb packages from var/cache/apt/archives. I want to format my pc and re-install selected applications only. Also how can I get the list of installed packages and dependencies.