Fred and George seem to have created a wide range of gag gifts and practical joke items, both while at Hogwarts and then as owners of their "Wizard Wheezes" emporium.   What are all the known "jokes items" that Fred &amp; George created throughout HP History and what were their side-effects?
Fred and George Weasley are known for their trouble-making and general &quot;solemnly swearing they are up to no good&quot;. Their antics/adventures give something to smile about and show us not all wizards are as serious as Professor McGonagall and Hermione. This gives them a reputation of being less intelligent and indeed they only achieved three OWLs. However, we also see the twins have quite a brilliant side! Being able to open and successfully run a shop in Diagon Alley without having completed their Hogwarts education is no easy take (IMO, anyway). Their creations helped students get out of class, our heroes out of tight spot, and even stop our enemies execute an evil plot. Ginny may have said it best:  &quot;We’ve been hearing explosions out of their room for ages, but we never thought they were actually making things,&quot; said Ginny. &quot;We thought they just liked the noise.&quot; Harry Potter and the Goblet of Fire  Do we know how many things Fred and George invented?
Can you make a non-polar electrolytic capacitor out of two regular electrolytic capacitors? How to design partitions for SSHD? Top Bar background does not persist when scrolling horizontally Update  A month Several months later, a new top bar, and the bug still exists. An answer has already been posted that would fix the bug, so is this something that the dev team plans on fixing?  There are also a host of other problems caused by this, especially on the  and . Again, this would be fixed with  html{min-width:1000px;}   There is a slight bug with small windows on both the new meta and main site(s)?, shown here. The problem is that the top bar coloring doesn't stretch across when you resize and scroll left or right.        On Meta, when a horizontal scroll bar is needed, the black background will only be as wide as the width of the viewport, but when you scroll the coloring will not shift.  To reproduce:   Make screen as large as possible, or wait until the menu bar starts expanding Make it smaller and smaller until horizontal scrollbar appears, then scroll left and right. How do I do this? I created a user without a home directory and now I want to create one. Not just a folder called new_user, I want the default home directory with all it's folders and hidden files, etc. Function in Table I extracted simple example:  require 'pp' x = 1..3 pp x.map do |i| {:value =&gt; i, :double =&gt; (i*2)} end pp x.map { |i| {:value =&gt; i, :double =&gt; (i*2)} }  pp(x.map do |i| {:value =&gt; i, :double =&gt; (i*2)} end) pp(x.map { |i| {:value =&gt; i, :double =&gt; (i*2)} })   I am wondering why first pp produces:  [1, 2, 3]   While all the oders are giving:  [{:value=&gt;1, :double=&gt;2}, {:value=&gt;2, :double=&gt;4}, {:value=&gt;3, :double=&gt;6}]   I assume it has something to do with operator precedence. Where can I find good explanation? I have got a specific folder located in "/home/.../reboot/".  I have a series of users that require read-only access to the ever changing files within.  My problem is that the same users are not authorized to view any of the parent directory files.  Right now, the only thing I have in place is that their starting folder is at "/home/.../reboot/" by changing the etc/passwd file; and I need to block all access to other folders.  How could I only give them access to this directory? When should I use a unique constraint instead of a unique index? When I want a column to have distinct values, I can either use a constraint  create table t1( id int primary key, code varchar(10) unique NULL ); go   or I can use a unique index  create table t2( id int primary key, code varchar(10) NULL ); go  create unique index I_t2 on t2(code);   Columns with unique constraints seem to be good candidates for unique indexes.  Are there any known reasons to use unique constraints and not to use unique indexes instead? Does quantum spin contribute to the angular momentum of a black hole? What are the best methods to show a data table in mobile / tablet view? Xcode free space requirement I am trying to update Xcode to 8.0. My OS is 10.11.6 El Capitan. However I am getting:     We could not complete your update   There is not enough disk space available to install the product.   I have got 14.22 GB free space. How much do I need?  UPDATE: I do not know the exact figure, though I did manage to update with 17.21 GB free space later on. In episode 10 of Full Metal Alchemist: Brotherhood, during the events in the Research Lab 5, Edward Elric is severely hurt. Later in the hospital, he writes down everything he had come to know, and he discusses with Alphonse, Hughes, and Armstrong about what to do with the information to continue the investigation.  At this point, King Bradley arrives with lemon into the room. He finds out what they are doing but acts very calm and chilled out and allows them to continue investigation while being careful.  Why did he not get Hughes and Armstrong killed at that point? Or at least tell them to not investigate at all? Test model coefficient (regression slope) against some value In R, when I have a (generalized) linear model (lm, glm, gls, glmm, ...), how can I test the coefficient (regression slope) against any other value than 0? In the summary of the model, t-test results of the coefficient are automatically reported, but only for comparison with 0. I want to compare it with another value.  I know I can use a trick with reparametrizing y ~ x as y - T*x ~ x, where T is the tested value, and run this reparametrized model, but I seek simpler solution, that would possibly work on the original model. what is PGP public key block? There's PGP public key block posted on some websites (eg. ).  It's not hex code. it uses much more alphabet characters. What is it?  Why is this information posted? how can i use it? Galois group of the product of two fields being the product of Galois groups? I'm just wondering if the following theorem is reasonable and whether the proof is makes sense or not? Also I have an application of it which I was trying to do earlier but I made a lot of mistakes so I would be very grateful if anyone would give some comments on this in case I have some very strong misunderstandings about Galois theory.    Theorem Let $E_1$ and $E_2$ be Galois field extensions of $F$ with trivial intersection ($E_1 \cap E_2 = F$), then $E_1 E_2$ has Galois group $\text{Gal}(E_1/F) \times \text{Gal}(E_2/F)$.  Proof   $E_1$ and $E_2$ are splitting fields (over $F$) of some polynomials $f_1$ and $f_2$ so $E_1 E_2$ is the splitting field of $f_1 f_2$ over $F$ and therefore it is Galois and we are justified using the "Gal" notation. Let $\sigma_1 \in \text{Gal}(E_1/F)$ and $\sigma_2 \in \text{Gal}(E_2/F)$ then by the fundamental theorem of Galois theory we can lift these both into elements of $\text{Gal}(E_1 E_2/F)$. The claim is that $\sigma_1 \sigma_2 = \sigma_2 \sigma_1$, to see this consider an element $\alpha \in E_1$, we have both $\sigma_2 \alpha = \alpha$ and $\sigma_2 \sigma_1 \alpha = \sigma_1 \alpha$ because it is invariant with respect to $\sigma_2$, but we can combine these equalities to get $\sigma_1 \sigma_2 \alpha = \sigma_2 \sigma_1 \alpha$. Both groups $\text{Gal}(E_i/F)$ ($i = 1,2$) are included in $\text{Gal}(E_1 E_2/F)$ and the degrees say there are no more elements, furthermore since they commute we can conclude $\text{Gal}(E_1 E_2/F) = \text{Gal}(E_1/F) \times \text{Gal}(E_2/F)$.     So hopefully that theorem is, if not correct, fixable.. and can be used to prove that $\mathbb Q (\sqrt{a_1},\sqrt{a_2},\cdots,\sqrt{a_n})$ has Galois group $C_2^m$ ($m \le n$) over $\mathbb Q$? How to "grep" for line length in a given range? This is a  about DoS and DDoS mitigation.   I found a massive traffic spike on a website that I host today; I am getting thousands of connections a second and I see I'm using all 100Mbps of my available bandwidth.  Nobody can access my site because all the requests time out, and I can't even log into the server because SSH times out too!  This has happened a couple times before, and each time it's lasted a couple hours and gone away on its own.  Occasionally, my website has another distinct but related problem: my server's load average (which is usually around .25) rockets up to 20 or more and nobody can access my site just the same as the other case.  It also goes away after a few hours.  Restarting my server doesn't help; what can I do to make my site accessible again, and what is happening?  Relatedly, I found once that for a day or two, every time I started my service, it got a connection from a particular IP address and then crashed.  As soon as I started it up again, this happened again and it crashed again.  How is that similar, and what can I do about it? Sequence Limit Problem: If $0 \leq x_{m+n} \leq x_n + x_m$ then limit of $x_n/n$ exists align xticks in PGFPlots The text xticks are not placed on the same line, rather the same height counting from the highest letter (zero is much higher than high and low).    How can you fix this?  MWE:  \documentclass[class=scrartcl,14pt]{standalone} \usepackage{fontspec} \usepackage{luatex85} \usepackage{unicode-math} \usepackage{tikz} \usepackage{pgfplots,pgfplotstable} \usepackage{calc} \usepgfplotslibrary{groupplots} \pgfplotsset{compat=newest}  \begin{document}  \begin{tikzpicture} \begin{groupplot}[group style={group size=1 by 1, horizontal sep=2cm, xlabels at=edge bottom }, %~ yticklabel style={/pgf/number format/fixed}, %~ xticklabel style={/pgf/number format/fixed}, scaled y ticks = false, scaled x ticks = false, xtick pos=left, ytick pos=left, %xlabel=time (week) ] \nextgroupplot[xmin=0.5,xmax=3.5,xtick={1,2,3},ymin=2.43,ymax=3.05,xticklabels={zero, low , high}, xlabel={label}]  \end{groupplot}  \end{tikzpicture}  \end{document} I gave a quick answer to part of  which had not been covered by previous answers, trying to clarify the reason you would say time of decoding but not decoding’s time. I said it was ’s usually indicates possession, but of course there were several counterexamples that would have occurred to me after a moment’s consideration, and these where helpfully supplied:   Britain’s climate two days’ time  a day’s work  the sun’s rays   I am still of a mind to say that possession of some sort is what allows the ’s. Even though the sun does not have title to its rays, they do belong to the sun. Now, at the risk of duplicating the original question and/or being pigheaded, I am curious as to why time of decoding but not decoding’s time is correct, if not for the reason I gave.