It seems that &quot;reopen&quot; should be changed to &quot;leave open&quot; in Close Votes queue tips box:    since there's no option as &quot;Reopen&quot; but &quot;Leave open&quot; has.
The Public Platform team is continuing to work towards  and we’re here today to announce a new onboarding experience for the review queues. In the  (), we learned that each queues’ instructions could be easily misinterpreted and additional information was difficult to find. Without proper guidance or context, new reviewers would contribute inconsistent reviews and risk having their review privileges suspended. With this release, our goals were to 1) better highlight the review privilege and 2) provide upfront instruction and guidance for successful reviewing. New privilege announcements Community moderation is a significant aspect of Stack Overflow and the Stack Exchange sites. We want users to be aware and familiar with this newly earned privilege, but also celebrate the opportunity to contribute to the community in a unique way.  Many users were discovering the review queues by chance. Once the privilege is earned, a new review queue icon with a red alert would appear in the top-right part of the navigation. We are adding a popover to bring more attention to this easy-to-miss icon. We will also be adding notices for when users earn access to other, higher reputation queues. Additionally, new reviewers will also receive an email notification about the newly earned privilege. They will only get the email if they earn the privilege and don't perform a review within 24 hours (anyone who doesn't want to receive email notifications like this can visit their  and turn off &quot;Tips and Reminders&quot;). We are also showing a popover to users who earned access to review queues in the past, but have never done a review or haven't reviewed in the last 30 days. This popover is only appearing for the next 90 days. The goal is to engage users who may not have interacted with the queues since we made  and . Welcome banner  If a reviewer clicks “Learn more” on the on-page popover or goes to the review queue home page (/review), they’ll be greeted with an onboarding message with general information about the review queues. Informational modals  Queue-specific modals will appear upon page load as you visit each queue. They summarize and highlight important aspects and tips about reviewing in a particular queue. This information can be revisited at any time by clicking “Learn more” under the page header. Feedback As always, please leave your feedback and any bugs you may discover related to this release below this post. We will be monitoring this post for the next few weeks (May 4, 2021). After May 4th, please report any further issues as new questions.
During iPhone update to iOS 10.3.1, I was asked for my password using the correct machine name for my Mac mini. To be clear, the request was not for my iCloud password, my actual local user account password for macOS. This can also happen in the other direction - setting up a Mac may ask for verification for you to enter your iPhone / iPad passcode (and not your iCloud password)  I could not find any information about this kind of access. I was thinking it was security for iCloud and possibly related to two step authorization or two factor authorization. This is the first time I can think of that I entered a desktop password outside of that actual desktop.  I don't have a screen shot but I recall an implication that some files in my Mac are encrypted and need my password. '... need to enter the password for .'   Are there settings I can I control this assuming it's a legitimate part of iCloud setup process or iOS setup process? How did Draco apparate within Hogwarts? 32-bit vs. 64-bit systems What are the differences between 32-bit and 64-bit systems?  If you have used both of them, what kind of sharp differences have you experienced?   Would it be a problem to use 32-bit programs on 64-bit systems in some cases? Multivariable limit - perhaps a trickier problem I am stuck on. I am trying to solve the following limit:  $\lim_{(x,y) \to (0,0)} \frac{x^4y^4}{(x^2 + y^4)^3}$  (This is a more challenging problem from Folland Calculus, it seems).  I am pretty sure this limit does not exist (however, this is just a guess, and I am not 100% sure.)  I am trying to approach via the paths y = mx and x = my but... they don't seem to work. I have tried simpler cases such as x = 0 and y = 0.   Any help appreciate. If $\vec{a},\vec{b},\vec{c},\vec{d}$are unit vectors, $(\vec{a}\times\vec{b}).(\vec{c}\times\vec{d})=1$ and $\vec{a}.\vec{c}=\frac{1}{2}$,then If $\vec{a},\vec{b},\vec{c},\vec{d}$are unit vectors such that $(\vec{a}\times\vec{b}).(\vec{c}\times\vec{d})=1$ and $\vec{a}.\vec{c}=\frac{1}{2}$,then $(A)\vec{a},\vec{b},\vec{c}$ are non-coplanar $(B)\vec{a},\vec{b},\vec{d}$ are non-coplanar $(C)\vec{b},\vec{d}$ are non-parallel. $(D)\vec{a},\vec{d}$ are parallel and $\vec{b}$ and $\vec{c}$ are parallel.    My Attempt: $(\vec{a}\times\vec{b}).(\vec{c}\times\vec{d})=1$ $(\vec{a}.\vec{c})(\vec{b}.\vec{d})-(\vec{a}.\vec{d})(\vec{b}.\vec{c})=1$ $\frac{1}{2}(\vec{b}.\vec{d})-(\vec{a}.\vec{d})(\vec{b}.\vec{c})=1$    Book's Solution which i did not understand: $(\vec{a}\times\vec{b}).(\vec{c}\times\vec{d})=1$ is possible only when $|\vec{a}\times\vec{b}|=|\vec{c}\times\vec{d}|=0$ and $(\vec{a}\times\vec{b})$ is parallel to $(\vec{c}\times\vec{d})$ And the correct option given is $(C)$.  I could not solve this problem after some efforts.Please help me.Thanks. In his  Feynman calculates the field momentum of a moving charged sphere with charge $q$, radius $a$ and velocity $\mathbf{v}$. He finds that the total momentum in the electromagnetic field around the charged sphere is given by:  $$\mathbf{p} = \frac{2}{3} \frac{q^2}{4\pi \epsilon_0} \frac{\mathbf{v}}{ac^2}.$$  He calls the coefficient between the field momentum, $\mathbf{p}$, and the velocity, $\mathbf{v}$, the electromagnetic mass:  $$m_\textrm{elec}=\frac{2}{3} \frac{q^2}{4\pi \epsilon_0 a c^2}.$$  He claims that this electromagnetic mass $m_\textrm{elec}$ has to be added to the standard "mechanical mass" of the sphere to give the total observed mass of the object.  Would this view be accepted by most physicists today?  Have any experiments been performed that show the effect of the additional electromagnetic mass on the dynamics of a macroscopic charged object?  I guess the problem is that such an effect would only be large enough to be observable for charged particles like electrons. In that case it would be difficult to distinguish mechanical mass, presumably due to the Higgs field, from electromagnetic mass. Maybe one could perform a high energy/short length scale experiment on an electron that excluded the effect of the electromagnetic mass? How can I add a new user as sudoer using the command line? After I add a user using adduser, I can't see it via System > Administration > Users and Groups unless I log out and then log in again. Is that normal?  Also, can I set a newly added user as a sudoer or do I have to change that only after adding it? How can I do that via the shell?  Finally, can I delete the original user that was created upon initial installation of Ubuntu, or is this user somehow 'special'? I've read many years ago in books, that the brain has no nerves on it, and if someone was touching your brain, you couldn't feel a thing.  Just two days before now, I had a very bad migraine, due to a cold. It's become better now, but when I had it I felt my head was going to literally split in half, as the pain was literally coming from my brain.  So it lead me to the question: How come people can get headaches if the brain has no nerves? I am running Ubuntu GNOME 15.10 with GNOME 3.18, and I would like to know if I can do any of the following and if so how:   Make it so that a folder is not indexed but leave its contents indexable (so that if I search for that folder's name in my system nothing will come up, but if I search for its contents, that will come up) Make it so that a folder is not indexable and nor is any of its contents (and if it contains sub-folders within it then it should recursively not allow any contents in them to be indexed nor the contents of any sub-sub-folders in the sub-folders etc, nor any of those sub-folders themselves) Make it so that individual files in a folder are not indexable, though not having any impact on other contents nor the parent-folder   So, are any of these variants possible? I believe the indexing program is called Tracker which indexes files and folders and their contents and allows for one to search for them on the system. VMware Linux Server -- how can you tell if you are a vm or real hardware? An interesting question.  I have logged into a Linux (most likely SuSE) host.  Is there some way that I can tell programmatically that I am a VM host or not?    Also assume that the vmtools are not installed. Finite Sets, Equal Cardinality, Injective $\iff$ Surjective. Do I need to upgrade RAM from 4GB to 8GB for Android development? 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? Best way to clone an installation (copying to identical hardware) Kind-of like  but slightly different (I think), in that I have 6 identical Acer Aspire Revo R3610 machines. One is (almost) configured to my requirements - when I'm done preparing it I'd like to make the other 5 machines absolutely the same. I'm very new to Ubuntu, what's the most straightforward (easiest) way of doing this?  The machines are going to live on different networks if that might otherwise be a problem (eg with Windows you can clone disks but you then have to make registry changes afterwards if they're going to run on the same network etc). The hardware in all 6 machines is, I stress, the same!  How can I efficiently clone one source image on to these identical machines?  Please restrict one software/solution per answer The Borel-Cantelli Lemma in  seems to be a sort of "corollary" of the .  It says:  "Let $(E_k)_{k=1}^{\infty}$ be a countable collection of measurable sets for which $\sum_{k=1}^{\infty} m(E_k) &lt; \infty$. Then almost all x $\epsilon \ \mathbb{R}$ belong to at most finitely many of the $E_k$'s"  I don't get three things:   "Then almost all x $\in \ \mathbb{R}$ belong to at most finitely many of the $E_k$'s"   What does that mean? Since the Borel-Cantelli Lemma comes after the "almost everywhere" definition, I guess: $\exists \ Z \ \subset \mathbb{R}$ s.t. $m(Z) = 0$ and $\forall x \ \in \ \mathbb{R} \setminus Z$, x belongs to $(E_{j}, E_{j+1}, E_{l}, ..., E_{m})$.   In the proof, one can see the $m(\limsup \ E_k) = 0$ part, stated as $m(\cap_{n=1}^{\infty} [\cup_{k=n}^{\infty} E_k]) = 0$. For some reason, $m(\cap_{n=1}^{\infty} [\cup_{k=n}^{\infty} E_k]) = 0$ implies that "Therefore almost all x $\in \ \mathbb{R}$ fail to belong to $\cap_{n=1}^{\infty} [\cup_{k=n}^{\infty} E_k]$ and therefore belong to at most finitely many $E_k$'s"   Okay, why? What is the contradiction if almost all $x \epsilon \ \mathbb{R}$ belong to all the $E_k$'s? Or a countably infinite subcollection?   What is the significance of this? Why not just state the Borel-Cantelli Lemma as "Let $(E_k)_{k=1}^{\infty}$ be a countable collection of measurable sets for which $\sum_{k=1}^{\infty} m(E_k) &lt; \infty$. $m(\cap_{n=1}^{\infty} [\cup_{k=n}^{\infty} E_k]) = 0$"? Disable chat migration notification if one of the users has insufficient rep? Why is oil a better lubricant than water? How come mineral oil is a better lubricant than water, even though water has a lower viscosity?    When two surfaces slide over each other with a gap filled with a fluid, the different layers of the fluid are dragged at different speeds. The very top layer touching the top metal surface will have the same speed as the surface itself, while the bottommost layer is stationary. The speed in the layers between is distributed linearly and there exist friction forces between those layers that slow the movement. Those frictional forces should be reduces however, if a fluid with a lower viscosity is chosen.   How come this is not so?   Does it have to do with water's polarity, so that it sticks to surfaces in a different way than oil? Expected value of sums Suppose we draw cards out of a deck without replacement. How many cards do we expect to draw out before we get an ace? I assume that the multimeter should read 2A, why is it only 0.358A? If this is how it is supposed to be, why? If I add a load, how do I measure that this load is being drawn, does the multimeter need to be in series? Making adult decisions "is" or "are" really not fun: Which is correct? Remove HTML Tags from an NSString on the iPhone There are a couple of different ways to remove HTML tags from an NSString in Cocoa.   is to render the string into an NSAttributedString and then grab the rendered text.   is to use NSXMLDocument's -objectByApplyingXSLTString method to apply an XSLT transform that does it.  Unfortunately, the iPhone doesn't support NSAttributedString or NSXMLDocument. There are too many edge cases and malformed HTML documents for me to feel comfortable using regex or NSScanner. Does anyone have a solution to this?  One suggestion has been to simply look for opening and closing tag characters, this method won't work except for very trivial cases.   For example these cases (from the Perl Cookbook chapter on the same subject) would break this method:  &lt;IMG SRC = "foo.gif" ALT = "A &gt; B"&gt;  &lt;!-- &lt;A comment&gt; --&gt;  &lt;script&gt;if (a&lt;b &amp;&amp; a&gt;c)&lt;/script&gt;  &lt;![INCLUDE CDATA [ &gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt; ]]&gt;