Strange output of typeset C++ code
Tabs in output file written by xelatex and pdflatex are different
Ubuntu Software (Software Center) Crash - Ubuntu 16.04 Two electrons, or an electron and a proton, interact with each other because of the Coulomb potential, which can also be seen in the Schrödinger equation (which is the equation that describes the motion for elementary particles).  But how do an electron and a photon interact? Why can a photon kick up an electron to a higher atomic orbital, or why is a photon emitted when an electron jumps down to a lower orbital? A photon do not have any charge, so the interaction cannot be caused by the Coulomb potential. So what is it that causes the interaction, and how does that affect the Schrödinger equation? (Or well, the relativistic version of the Schrödinger equation, since we're dealing with photons.) Vertically align text next to an image? Why won't vertical-align: middle work?  And yet, vertical-align: top does work.   span{   vertical-align: middle; } &lt;div&gt;   &lt;img src="https://via.placeholder.com/30" alt="small img" /&gt;   &lt;span&gt;Doesn't work.&lt;/span&gt; &lt;/div&gt; Why does my wife's skin buzz when she's using her laptop? When my wife uses her laptop, if I touch her skin, I can feel a buzz.  She doesn't feel the buzz, but she can hear it if I touch her ear.  So I'm guessing it's a faulty laptop, and she's conducting an electrical current.  But why would she not feel anything, and what would it be that she would be hearing when I touch her ear?    More info:  The effect is only intermitent - it's pretty reliable in a single session on the laptop, but some sessions it won't happen and others it will.  I had the same sensation with a desk lamp that I had several years ago, with no moving parts (as far as I could tell)  The effect only occurs when I move my finger - if I'm stationary, I don't notice anything.   I was playing with my son, and noticed the same buzz.  First I thought he was touching the laptop.  Then I realised he had skin-to-skin contact with my wife who was using the laptop. How to acknowledge a deceased advisor’s contributions to a paper? I'm trying to install wifi drivers for a particular mini wifi card i bought. The output of lsusb is:  0bda:f179 Realtek Semiconductor Corp   I've searched everywhere for drivers, but could not find anything. Any help?  Thanks popping to root view in navigation controller Why did Tony Stark leave his armor to explore the castle in Sokovia? In Avengers: Age Of Ultron, Tony Stark is the first member of the Avengers to get inside Baron von Strucker's castle, where he takes down a room full of soldiers before stepping out of his suit and travelling down a secret passage.  Why does he take off his suit in the middle of an enemy base when it might have protected him against Scarlet Witch's magic, or at the very least helped him better search the passageway with Jarvis' HUD? $$Rad(I)=\{a \in R | \exists n \in \mathbb{N} \text{ such that } a^n \in I\}$$   R is a commutative ring, I is an ideal.   To show that $Rad(I)$ is an ideal of $I$, we have to show that for $a,b \in Rad(I)$ it stands that $a-b \in Rad(I)$ and for $r\in R$ it stands that $a\cdot r\in Rad(I)$, right??   When $a,b \in Rad(I)$ we have that $a,b \in R$ and $a^n, b^m \in I$.   $a-b \in R$.   But how can we show that $(a-b)^x \in I, x \in \mathbb{N}$ ?? Where is the cron / crontab log? Length of generator output Python provides a nice method for getting length of an eager iterable, len(x) that is. But I couldn't find anything similar for lazy iterables represented by generator comprehensions and functions. Of course, it is not hard to write something like:  def iterlen(x):   n = 0   try:     while True:       next(x)       n += 1   except StopIteration: pass   return n   But I can't get rid of a feeling that I'm reimplementing a bicycle.  (While I was typing the function, a thought struck my mind: maybe there really is no such function, because it "destroys" its argument. Not an issue for my case, though).  P.S.: concerning the first answers - yes, something like len(list(x)) would work too, but that drastically increases the usage of memory.  P.P.S.: re-checked... Disregard the P.S., seems I made a mistake while trying that, it works fine. Sorry for the trouble. I'm an android developer and have laptop with 4GB RAM. When I compile my project the RAM is used at 100%.    If I add more RAM will it solve the problem? What is the minimum RAM required for Pokemon GO? While poking around on Pokemon Go's , it lists some specs required for Android and iOS devices. I'm particularly interested in Android devices, but I do not see a minimum/recommended RAM listed on their site.        Android 4.4 to Android 6.0.1  (Android N will not supported until the   official Android release)    Preferred resolution of 720x1280 pixels   (Not optimized for tablet)    Strong internet connection (Wi-Fi, 3G, or   4G)    GPS and Location Services    Intel CPUs are not supported      My device is a , which has a 1.5GB RAM and Quad-Core processor. It runs fine for the most part, but a majority of the features heavily lags and are sluggish while I've seen the same features run smooth on other devices.  What is the minimum/recommended RAM for Pokemon Go to run more smoothly? Evaluate $\lim_{n\to \infty} \sum_{r=1}^n \frac {1}{2^r}\tan \left(\frac {1}{2^r}\right)$ Evaluate $$\lim_{n\to \infty} \sum_{r=1}^n \frac {1}{2^r}\tan \left(\frac {1}{2^r}\right)$$   I tried to create a telescoping sum but I couldn't. The last step I could reach was turning the limit into $$\lim_{n\to \infty} \sum_{r=1}^n \left(\frac {1}{2^r(1-\tan (2^{-r+1})} -\frac {1}{2^r(1+\tan (2^{-r+1})}\right) $$  But couldn't proceed further. Also I thought about Riemann sums but it was a pure dead end.  Any help would be greatly appreciated Mass dropped on a spring I thought this would be a particularly simple problem but it is turning out to be quite the opposite. I am sure I am doing a very simple mistake.   The problem statement is that there is a mass which is just barely kept on the spring (help by the force equal to the weight of the spring) such that the spring is uncompressed. As soon as I let the object go, it will compress the spring and come to rest at some height. The energy stored in the spring will be equal to the difference in the potential energy at the two height of the spring (compressed and uncompressed),  $$mgh_i -mgh_f= 1/2 kx^2$$ Furthermore, the compression of the spring would just be the difference in the $h_f -h_i$. This gives me two roots for compression,  $$ x=0 $$ And the second would be, $$ mg=1/2kx $$ But then by this, $kx=2mg$ and $kx$ is force by Hooks law, but then does it means that the force compressing the spring is twice the weight of the object? That sounds odd. I was expecting I would just recover Hooks law but I guess I am doing something wrong here. But I am not sure what that is.   Any help will be much appreciated.  P.S. This is not a homework problem. We are designing a project for our school.  Thanks for your time. Show an Ideal is the principal ideal for some polynomial. Let $F$ be a ﬁeld and $R = F[X]$. Suppose $I$ is an ideal of $R$. Show that $I = (p(X))$ for some $p(X)$ in $F[X]$. (Hint: consider a polynomial $p(X)$ of least degree in $I$.)  I'm trying to do this question but can't seem to start. if anyone could give me a hint that would be appreciated.  My instinct was to take a monic polynomial (which exists since we are in a field) of degree $1$ and divide given the first two parts of the question were about polynomial division.  Thanks. How can I execute an equivalent of `head -z` when I don't have the `-z` option available? I'm using python\pyodbc and would like to access the second result set of a stored procedure. As near as I can tell, pyodbc does not support multiple result sets. Additionally, I can't modify the stored procedure. Are there any options to access the second result set using SQL or some other work-around? Perhaps create a second stored procedure that only returns the second result set of the first? Subgroups of $U(n)$ isomorphic to a direct sum of cyclic groups Let $U(n)$ to be the set of all positive integers less then $n$ and relatively prime to $n$. Then $U(n)$ is a group under multiplication modulo $n$.  A. Find integer $n$ such that $U(n)$ contains subgroup isomorphic to $Z_5\oplus Z_5$.  B. Show that there is an $U(n)$ containing a subgroup isomorphic to $Z_3 \oplus  Z_3$, but not isomorphic to $Z_4 \oplus  Z_4$. I have configured my MySQL Database to require passwords on all users, even root from the machine itself.  Now I discovered that there are empty Users in my Database  Reproduce: mysql -u root -p and then use mysql; &amp; select * from user;  It gives me 2 entries, one with "localhost" and user &lt;empty&gt; and one with the machine's hostname and &lt;empty&gt;.  Now I tried to access the account with mysql -u ' ' (yes it's correct, leave a space between the ' things) and I log in without a password. The user can "only" see information_schema and test, the two databases created by default. He does not has access to mysql or any other custom created databases.  I already changed the Password of this user to something I won't tell you  mysql -u root -p use mysql; UPDATE mysql.user SET Password=PASSWORD('thisisasecretpassword') WHERE USER='root'; FLUSH PRIVILEGES;   Now my Questions:   Is any MySQL Server vulnerable for an attack with this entry? Could an attacker break out of this account or the two default databases? Should I password-protect those Users or can I delete them? Are They required for some MySQL-internal things?