How to Align bottom footer element after my text ends
How do you get the footer to stay at the bottom of a Web page?
Is there a way to access QGIS plugins in Python?   I'd like to write a script to do some geoprocessing, and I'd like to use the clip, regular points and convex hull tools in fTools, as well as the Road graph plugin. The latter is probably a different can of worms because it is a C++ rather than Python plugin. I have been reading about the new Salesforce async triggers. Currently, I tend to handle these sort of needs with a trigger that passes data to a 'Handler class' that would evaluate if a certain change has occurred. If it has then we pass those Ids to a queueable class for further processing.   What advantage do CDC and async triggers offer over using queueable or batch apex? When an object is moving in a circle, won't the frictional force oppose it's motion? And if the velocity is always tangential to the path, there is no component of it towards the center, so there is no component of friction towards the center (since the frictional force is antiparallel). So how can friction be a centripetal force, like in the case of a car rounding a corner? Suppose you have a physical . It is true that as amplitude increases, the period increases. Can we demonstrate this fact without explicitly finding the period (which is pretty involved and pretty messy) in:    an intuitive fashion,  rigorously? I understand the proof that  $$Var(aX+bY) = a^2Var(X) +b^2Var(Y) + 2abCov(X,Y), $$  but I don't understand how to prove the generalization to arbitrary linear combinations.  Let $a_i$ be scalars for $i\in {1,\dots ,n}$ so we have a vector $\underline a$, and $\underline X = X_i,\dots ,X_n$ be a vector of correlated random variables. Then $$ Var(a_1X_1 + \dots a_nX_n) = \sum_{i=1}^n a_i^2 \sigma_i^2 + 2 \sum_{i=1}^n \sum_{j&gt;i}^n a_i a_j \text{ Cov}(X_i,X_j)$$  How do we prove this? I imagine there are proofs in the summation notation and in vector notation? Identity involving Euler's totient function: $\sum \limits_{k=1}^n \left\lfloor \frac{n}{k} \right\rfloor \varphi(k) = \frac{n(n+1)}{2}$ Let $\varphi(n)$ be Euler's totient function, the number of positive integers less than or equal to $n$ and relatively prime to $n$.    Challenge: Prove  $$\sum_{k=1}^n \left\lfloor \frac{n}{k} \right\rfloor \varphi(k) = \frac{n(n+1)}{2}.$$   I have two proofs, one of which is partially combinatorial.    I'm posing this problem partly because I think some folks on this site would be interested in working on it and partly because I would like to see a purely combinatorial proof.  (But please post any proofs; I would be interested in noncombinatorial ones, too.  I've learned a lot on this site by reading alternative proofs of results I already know.)  I'll wait a few days to give others a chance to respond before posting my proofs.  EDIT: The two proofs in full are now given among the answers. SOQL query for Multiselect picklist How to: Unlimited Bash/shell history? Is there a way to define an unlimited history in Bash ? Let's say we have one black hole that formed through the collapse of hydrogen gas and another that formed through the collapse of anti-hydrogen gas. What happens when they collide? Do they (1) coalesce into a single black hole or do they (2) "annihilate" into radiation?  One would expect (1) to be the case if the No Hair Theorem were to hold. So I guess what I'm really asking for is a modern understanding of this theorem and its applicability given what we know today. Can the program counter on Intel CPUs can be read directly (that is without 'tricks') in kernel mode or some other mode? Limit of $\lim_{n\rightarrow \infty} \sum^{n}_{i=1} \frac{1}{\sqrt {n^2 +i} }$ Why is the application of probability in  (QM) fundamentally different from its application in other areas? QM applies probability according to the same  as in other areas of physics, engineering, etc.  Why is there a difference?  Naively one would assume one of these possibilities:   It is not the same probability (theory?) It is a matter of interpretation (of the formalism?) Something else?   Many answers (which I am still studying) focus on the fact that the combined probability of two mutually-exclusive events in QM is not equal to the sum of the probabilities of each event (which holds classically by definition). This fact (appears to) makes the formulation of another probability (a quantum one) a necessity.   Yet this again breaks down to assumed independent, if this is not so, the "classic probability" is applicable (as indeed in other areas). This is one of the main points of the question. Tell rate-limited users how long they have to wait before asking a new question New users are limited to one question per an hour, but once they'll hit this limit, all they see is You can only post once every 60 minutes. I think it would be very appreciate to change / extend this message, adding You need to wait next xx minutes. I saw similar solutions on many forums.  Would it be hard to implement something like that?  EDIT: It could be either added as extension to above mentioned warning message or as red-colored reminder above Title field. Or even as an explanation message, preventing user from clicking on a Ask Question button? Anything would be good, to not let user write the question (can be time consuming) only to hit the wall of limit. This can be a little bit annoying or frustrating, don't you think? Convert a preprocessor token to a string I'm looking for a way to convert a preprocessor token to a string.  Specifically, I've somewhere got:  #define MAX_LEN 16   and I want to use it to prevent buffer overrun:  char val[MAX_LEN+1]; // room for \0 sscanf(buf, "%"MAX_LEN"s", val);   I'm open to other ways to accomplish the same thing, but standard library only. Theorem environment with hanging indentation I would like to define a theorem environment with custom layout. In particular, I want the body of the theorem to be indented, like this  Text body. Text body. Text body.  Theorem 1 (Pythagoras).     Let a,b,c the sides of a rectangular triangle.     Without loss of generality, we assume that  a&lt;b&lt;c .     Then, the following equality holds:            a^2 + b^2 = c^2  More text. And even more text.   This is similar to the quote environment, I believe.  How can I do this?  Preferably, I would like to use the existing \newtheorem command, but that's not mandatory. comment.sty and UTF8 encoding I noted that if I use comment.sty and a there is a block of text containing UTF8 characters inside a comment environment, the compilation aborts!  Minimal Example  \documentclass{article} \usepackage[T1]{fontenc} \RequirePackage[utf8]{inputenc}%this file is stored as UTF8 file! \RequirePackage{comment} \specialcomment{privateSolution}     {\begingroup\itshape\noindent\textbf{Solution}\\}     {\endgroup} %\excludecomment{privateSolution}%Use it to remove solutions!  \begin{document} \title{Comment.sty and UTF8 test file} \maketitle \section{UTF8 character test} In which alphabet characters àìùòè are common? \begin{privateSolution}     The Italian alphabet contains àìùòè. \end{privateSolution}  \begin{comment}     The Italian one! It contains àìùòè. \end{comment} \end{document}   Has anyone the same problem? Any workaround?  Thanks in advance. What is a terminal and how do I open and use it? By conservation of energy, the solid is left in a lower energy state following emission of a photon.  Clearly absorption and emission balance at thermal equilibrium, however, thermodynamic equilibrium is a statement of the mean behaviour of the system, not a statement that the internal energy is constant on arbitrarily short timescales.  The energy has to come from somewhere during emission, and go somewhere during absorption.  Energy in a solid can be stored as kinetic and potential energy of electrons and nuclei, either individually or in collective modes such as phonons and plasmons.  In thermal equilibrium energy will be stored more or less in various forms depending on the temperature and material.  However, even if most of the thermal energy in a particular solid at temperature $T$ is stored in the form of phonons, it could be that phonons primarily interact with light indirectly via electrons, e.g. a phonon excites an electron in a phonon-electron interaction, which can interact with light via the EM field.  Given that light is an EM field, it makes sense to me that it is emitted and absorbed by charged particles.  The electron-photon interaction is probably dominant for visible and ultraviolet light, given that metals are opaque, while semiconductors and insulators are transparent to (visible and UV) light with energy lower than their bandgap. However, once you get into energies in the IR and below, or X-rays and above, other mechanisms apparently take over.  For example, on the high-energy end of the spectrum I've heard that gamma rays can interact directly with nuclear degrees of freedom, which is reasonable considering that gamma rays are emitted during a lot of nuclear reactions.  A review of  might give clues to important light-matter interactions over a broad range of wavelengths.  Whether all of the these processes are involved in blackbody emission is a somewhat different question.  What physical processes mediate energy transfer during blackbody emission, and in which energy ranges are the various processes dominant? ceiling fan from a switch with only black and red wires? The current switch controls an outlet in the corner of the room for a lamp. I pulled it out and noticed three sets of individual wires: two set of wires coming up into the box from the bottom, and one set with a red wire coming down into box.  All the white and grounding wires are capped.  Also all the black wires are capped; one set I’m assuming is the hot since I see it contains a red wire. On the back of the switch, the top two ports have black wires and the bottom right has the one red wire.  There are two black pigtail wires coming off the black capped wires. I tried to connect a separate switch to control a ceiling fan with remote. I ran new wire making the old switch box into a two switch. I ran 14/2 gauge wire to ceiling for fan / light remote combo. Fan didn’t work after multiple re-wiring  combinations. The breaker did pop and half click when it popped. Then I thought to re-wire the ceiling fan wires as if I was going to make it into outlet only and use a tester to indicate an open ground, or a wiring error but the two light on tester are both orange indicating correct wiring. I heard that sometimes the ceiling fan remote transformer goes bad. Should I check batteries and/or unit placement? I’m really confused at this point why the light is not working at least with remote after follow wiring installation instructions that were included with the fan. I think it’s my wiring with the switch. The way I left the wiring is that it has constant power. As if we’re a outlet the current switch does not turn it off. Gollum had his life largely extended because he possessed the One Ring. He appeared to be an old, deformed, and twisted creature.  According to , he had the Ring for 478 years. His loss of the Ring and the events of The Lord of the Rings are separated by around 77 years.  Did the Ring continue to extend his life after he lost it?