My beautiful enzyme avatar is hosted on Gravatar, and it doesn't load on , and generally SE pages I have open.  Can someone take a look? I have Chrome version Version 53.0.2785.143 m and it seems to throw a 502 error (Bad Gateway). Others are experiencing this issue as well.
It seems that with some profiles the Gravatar image is broken. I am not sure if this is an issue with SE or Gravatar, or both, so posting here.  As an example,  shows an error on , which shows a HTTP 500 on Gravatar.  Profile image on SO:        Image on Gravatar:        Switching to the MSE profile of the user, the image is working (but has a different hash).  Is this a bug on the SE side? Can anything be done to make Gravatar fix this?    Update 2016-10-04:  It happened to me again two times today. The last user profile was . Calling the service two or three times fixes the issue.
A Sequence converges to a limit $L \in \mathbb R$ if, and only if, an $N$-th tail of the sequences converges to $L$ for some $N \in \mathbb N$ Why wasn't Poe told about Holdo's plan? VBA array sort function? I'm looking for a decent sort implementation for arrays in VBA. A Quicksort would be preferred. Or any other  other than bubble or merge would suffice.  Please note that this is to work with MS Project 2003, so should avoid any of the Excel native functions and anything .net related. Why are the energy levels of a simple harmonic oscillator equally spaced? The energy level of a simple harmonic oscillator is $E_n=(n+\frac{1}{2})\hbar\omega$. Is there any physical explanation why these levels are equally spaced ($= \hbar\omega$)?  Maybe this  can be helpful. $$A=\begin{array}{ccc} 0 &amp; 1/2 &amp; 0 &amp; \cdots &amp; 0 \\ 1/2 &amp; 0 &amp; 1/2 &amp;\cdots&amp; 0\\ 0 &amp; 1/2 &amp; 0 &amp; \cdots &amp; 0\\ \vdots &amp; \vdots &amp; \vdots &amp;\ddots &amp; 1/2\\ 0 &amp; 0 &amp; 0 &amp; 1/2 &amp; 0 \end{array}$$  I need to know the spectral radius of $A$ in function of the dimension of the matrix $n$. I know only one way to know the spectral radius, using the definition I find all eigenvalues and then find the maximum. but it very hard if $n$ is changing. Some help please!  I did some iteration by   $$det(\lambda I-A)$$  $$n=2 \quad r=\frac{\sqrt{1}}{2}$$ $$n=3 \quad r=\frac{\sqrt{2}}{2}$$  for $n=2$ and $n=3$ are correct.  and if we take this rule, for   $$n=5\quad \quad r=\frac{\sqrt{4}}{2}$$  but this isn´t true since I know radius for this matrix should be $&lt; 1$ and if we take this rule  for $n=5$ we have  $$\frac{\sqrt4}{2}=1$$   Some hint? Why won't OS X trust GitHub's SSL certificate? Windows 7 / 8 tool for amplifying sound / equivalent to pavucontrol? I'm watching live streamed videos, but the volume sometimes is barely loud enough.  With Windows, I can only turn the system volume and the flash volume up to maximum, and then bad luck if that's still not loud enough.  On Linux, on the same notebook, I have the same problem, but I can use pavucontrol (pulseaudio volume control) to amplify the sound volume beyond 100%.  Unfortunately, I can't always work on Linux, since Visual Studio and SQL-Server only run on Windows.  Is there any tool or way to amplify volume on Windows 7 / 8 , without having to resort to run Linux in a virtual machine? Dual boot Ubuntu with Windows on Acer Aspire I've installed Ubuntu 16.04 LTS along side with Windows 10 (I shrinked my Disk using Windows Disk Management) on my Acer laptop (ES1-531-C13G), but when I restart/reboot my system no menu (Grub screen) appears from where I can select the operating system that I want to boot with, but instead, system takes me into Windows 10 everytime. I've tried several things from internet including :    Ran bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi from windows command prompt.  Reset  Bootorder i.e. first Ubuntu then Windows from Ubuntu terminal (after successful Ubuntu installation) etc, but nothing works for me so far. Please guide me ! Autoexpand UITextView height dynamically in ios Unable to locate package lib32bz2-1.0 I am trying to install Simplicity studio on Ubuntu 15.04 (64-bit) and I get this error  E: Unable to locate package lib32bz2-1.0 E: Couldn't find any package by regex 'lib32bz2-1.0'   I tried to install lib32bz2-1.0 package, again I get the same error. How to install package lib32bz2-1.0 on Ubuntu 15.04(64-bit) Today a student asked me $\int \ln (\sin x) \, dx.$ Calculate the integral $$\int \ln (\sin x) \, dx.$$ I want the very latest version of Python, but I don't want to bypass the apt package manager: I don't want to do an old-school source install because that can make it harder to uninstall when the official packages come out.  Python3.5 is not currently featured in any of Canonical's package repositories, which means I cannot just "apt-get install python3.5".  Is there a way to get Python3.5 installed on my PC in the meantime? A possible incorrect application of Law of Large numbers I have a question on Holder space.Is the space $C^2(\mathbb{R}^n)$ embedded in $C^{1,\alpha}(\mathbb{R}^n)$? I think in the bounded domain case, this should be true. But what if in the case where the domain is not bounded? Thanks for any hint! Travel duration from Earth to a star at 9.8 m/s² acceleration Why we can't implement AES 512 key size? I have a ListBox DataTemplate in WPF. I want one item to be tight against the left side of the ListBox and another item to be tight against the right side, but I can't figure out how to do this.  So far I have a Grid with three columns, the left and right ones have content and the center is a placeholder with it's width set to "*". Where am I going wrong?  Here is the code:  &lt;DataTemplate x:Key="SmallCustomerListItem"&gt;     &lt;Grid HorizontalAlignment="Stretch"&gt;         &lt;Grid.RowDefinitions&gt;             &lt;RowDefinition/&gt;         &lt;/Grid.RowDefinitions&gt;         &lt;Grid.ColumnDefinitions&gt;             &lt;ColumnDefinition/&gt;             &lt;ColumnDefinition Width="*"/&gt;             &lt;ColumnDefinition/&gt;         &lt;/Grid.ColumnDefinitions&gt;         &lt;WrapPanel HorizontalAlignment="Stretch" Margin="0"&gt;             &lt;!--Some content here--&gt;             &lt;TextBlock Text="{Binding Path=LastName}" TextWrapping="Wrap" FontSize="24"/&gt;             &lt;TextBlock Text=", " TextWrapping="Wrap" FontSize="24"/&gt;             &lt;TextBlock Text="{Binding Path=FirstName}" TextWrapping="Wrap" FontSize="24"/&gt;          &lt;/WrapPanel&gt;         &lt;ListBox ItemsSource="{Binding Path=PhoneNumbers}" Grid.Column="2" d:DesignWidth="100" d:DesignHeight="50"      Margin="8,0" Background="Transparent" BorderBrush="Transparent" IsHitTestVisible="False" HorizontalAlignment="Stretch"/&gt;     &lt;/Grid&gt; &lt;/DataTemplate&gt; How to change the font color of a disabled TextBox? Is time dilation an illusion? It is said that we can verify time dilation by flying a very accurate clock on a fast jet or spaceship and prove that it registers less time than the clocks on earth. However, the clocks on earth would be moving relative to the clock on the spaceship, and since time always dilates and never goes faster regardless of the direction of relative motion,  the clocks on earth should register less time than the clock on the spaceship.  Is this true? Whenever there is a fast-moving object such as a rocket do all clocks on earth really become slow?  If the rocket with the clock landed after moving at relativistic speed, would its clock and the earth's clock again show the same time since during its travel both appeared slow to each other?  Or is all this just an illusion, ie. the clocks just appear to be slow to each other but in actually run at normal speed, and neither is behind when the rocket actually lands? Spacing around \left and \right Why does the addition of a \left and \right introduces an extra space around the formula? Specifically, why do $\cos(\theta)$ and $\cos\left(\theta\right)$ render differently?  Is there a way to use resizable delimiters without introducing the spurious spaces?  Why did Knuth design it like this?  Edit: This occurs too, if \operatorname{MYOP} or some other operator, like \lim, \min etc. is used. (This edit is basically to make it easier to find this answer.)