As you collect magazines/books/comics in the wastelands, they apparently give you perks for finding them.  Do the books need to remain in my inventory, or can I display them on a shelf in my settlements without penalty?
In Fallout 4 the Bobbleheads are back.  Once you pick them up they stay in your inventory with a weight of 0 and a value of 300. Will I need them later ? Do I lose the bonus if I sell them or drop them somewhere ? Same with the magazines.  Is there any disadvantage to selling them ?
PhD without previous academic degree: truth or myth? A geometric reason why the square of the focal length of a hyperbola is equal to the sum of the squares of the axes? When I teach conics, I give a simple geometric argument for the Pythagorean relation for ellipses. (By "Pythagorean relation" I mean the fact that the square of the focal length $c$ is the difference of the squares of the semimajor and semiminor axes, i.e. $c^2=|a^2-b^2|$ for the ellipse defined by $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$.) The picture argument goes as follows: just draw the obvious isosceles triangle from the two foci to one of the two points at the end of the minor axis. We see two right triangles; in each, one leg is the focal length $c$ and the other leg is the semiminor axis, while the hypotenuse is the semimajor axis. The result follows from the Pythagorean theorem applied to this right triangle.  But when it comes to the Pythagorean relation for hyperbolas, I can't think of an equally convincing picture to draw. Instead I have to give a rather inelegant algebraic argument for the relation $c^2=a^2+b^2$ (for the hyperbola defined by $\frac{x^2}{a^2}-\frac{y^2}{b^2}=1$, with focal length $c$), directly from the definition of the hyperbola. The messy details are below.*  Now, obviously there is an asymmetry between the argument for the ellipse and the argument for the hyperbola: the ellipse argument is almost trivial and doesn't involve working straight from the locus definition, but the hyperbola argument is tedious and does require working straight from the definition. So, my question:     Is there an equally persuasive picture I could draw to convince high   school students of the Pythagorean relation for hyperbolas -- without having to get technical with points at infinity, say?   The natural triangle to draw is the right triangle with legs from the center to a vertex and from that vertex to an asymptote, which has legs of length $a$ and $b$; but then the problem becomes why the length along the asymptote should be equal to $c$. I doubt there is a purely (Euclidean) geometrical reason because this triangle lies on the asymptote, not on the hyperbola itself; I suspect some sort of limiting procedure will be required.    [*] The tedious algebraic details:     The foci lie at $(\pm c,0)$.   Say $a&gt;b$. Then hyperbola is the locus of points $(x,y)$ such that       $$\left|\sqrt{(x+c)^2+y^2}-\sqrt{(x-c)^2+y^2}\right|=2a$$      Assume for simplicity the expression between the absolute value bars   is positive. (The algebra is even more tedious if we don't make such a   simplifying assumption.) Then moving the right root to the other side   and squaring gives      $$(x+c)^2+y^2=4a^2+(x-c)^2+y^2+4a\sqrt{(x-c)^2+y^2}$$      Simplifying gives      $$xc-a^2=a\sqrt{(x-c)^2+y^2}$$      and upon squaring again we have      $$x^2c^2-2xca^2+a^4=a^2(x^2-2xc+c^2+y^2)=a^2x^2-2xca^2+c^2a^2+a^2y^2$$      which reduces to      $$x^2(c^2-a^2)-y^2a^2=a^2(c^2-a^2)$$      Defining $b^2:=c^2-a^2$ brings the equation into the form   $x^2/a^2+y^2/b^2=1$, and the Pythagorean relation follows from the   definition of $b$. What happens to the energy when waves perfectly cancel each other? Electromagnetic black hole? So I was thinking about something for the past while  Consider a large spherical foam-ball with homogeneous density. Where a foam ball is defined as an object that can absorb matter with 0 friction (example: a gravitational well without an object inside). This is a purely theoretical construct.  If the foam-ball has a radius R and a charge Q. What charge must the foam-ball have, such that there is well defined sphere or horizon such that any object with a negative charge (even if it is the slightest bit) must travel faster than C in order to escape the field of the ball.  Aka what charge would turn this into a black-hole for all objects with opposite sign on their charge?  Once again I assume the foam-ball is a single particle, that doesn't repel itself... its just a very large homogenous 'thing' with charge. The timeout period elapsed prior to obtaining a connection from the pool I'm getting this error every few days. I won't see the error for a few days then I'll get a flurry of 20 or so all with in a minute or so.  I've been very thorough going throw my code so that I'm using this basic setup for my DB access.  try {   myConnection.Open();   mySqlDataAdapter.Fill(myDataTable);   myConnection.Close(); } Catch (Exception err) {   if (myConnection.State != ConnectionState.Closed) myConnection.Close();   throw err; }   The way I understand it this should execute my queries and immediately release the connection back to the pool but if something goes wrong with the query then I catch the excpetion close my connection then throw the error up, which eventually gets trapped at the application level and logs and emails me the error.  Even using this throughout my code I'm still running across the issue. What can I do to diagnose the root cause of the issue? Is the collection of all functions between two sets a set? Representative point of a cluster with L1 distance The representative point of a cluster or cluster center for the k-means algorithm is the component-wise mean of the points in its cluster. The mean is chosen because it helps to minimize the within cluster variances (which is to say that it is minimizing within cluster squared Euclidean distance, since its the same). Now, when I want to use a different distance metric, like L1 (Manhattan distance), I would be minimizing the within cluster absolute deviations (if I choose to). I was looking at what the centers calculation would be like, because the mean won't reduce the new objective function, and I found this on the Matlab documentation of their kmeans function for the distance parameter     cityblock - Sum of absolute differences, i.e., the L1 distance. Each centroid is the component-wise median of the points in that cluster.   Now, how did they come up with the component-wise median? How does a median minimize absolute deviations? SVN repository backup strategies I'm new to SVN and I'd like to know what methods are available for backing up repositories in a Windows environment? Is it legal to add your publications to ResearchGate? I recently created a profile on . And to add your publications list it requires you to upload the paper. Is it legal to upload published journal articles on public servers, where everyone can download it for free? Derivative of conjugate multivariate function if recursively find ext, then, else on unix This is what I normally use. But I need to recursively find an extension with, then, and else. The problem with this one is that it is not recursive.  if ls $HOME/Downloads/*.ext &gt;/dev/null 2&gt;&amp;1 then     : else     : fi Just a few questions about Hyper-V virtual machines and clustering I have been using Microsoft’s Hyper-V technology for a little while now, but I am just now dipping my toe into clustering.  In particular, I am trying to implement a fault-tolerant SQL DB. This involves setting up two VMs, clustering them via Failover Cluster, and then installing SQL Server in some fashion. I have two physical machines - one high-end and rather beefy “heavy lifter” to contain the majority of the VMs, and another “backup” (a repurposed desktop) to hold the essential “secondary” (or failover) AD-DC, SQL and FS VMs.  The main reason why I find the failover cluster at the VM level so attractive is that it presents a single IP and DNS entry to the network as a whole - if one machine (physical or virtual) goes down, you might loose some ping and the connections get reset, but the network applications (Microsoft RMS connection to backend SQL) can still connect to a viable DB without having to mess around with the settings at all.  My first question is in terms of SQL Server itself. If I have a cluster between two VMs, does it make more sense to install the SQL Server in Failover Cluster configuration or should I simply install it in a stand-alone config and mirror the DBs? For example,  suggests just mirroring the DBs, but do I just mirror standalone DBs on standalone VMs, or can I get the network and failover benefits of clustered VMs while still utilizing (on each clustered VM) standalone DBs that have been mirrored between each other?  As well, I have come across a lot of documentation about SQL clustering, but most assume a number (#>2) of physical machines to hold not only the actual SQL VMs but also the Quorum and Witness stores. I will not be able to muster more than two physical machines. As such, I will have to be satisfied with a VM cluster that does not exceed two VMs (one for each physical machine).  Another issue involves MSDTC - the Distributed Transaction Coordinator. When attempting to install the SQL Failover Cluster (I never completed it for this reason) it threw a hissy fit because MSDTC had not been clustered. Search as I might, I have not yet found a way to do so under Windows Server 2012 R2. I have found , but these instructions don’t align with 2012 R2 (at least, not in a way that allows me to successfully cluster MSDTC). Plus,  that I have found for SQL Server Failover Cluster installation suggest that a third “network device” - shared network storage (a SAN) - is required for the DB itself (and other functionality). I do not have this, and won’t be getting this. Most of my storage exists on the “heavy lifter” that was designed for all of the “primary” VMs. If that physical machine goes down, so does the storage. The secondary server does have enough resources for an AD-DC Server, an SQL server and a File Server, so it will handle the “secondary” failover versions of those VMs (clustered or not).  My final question involves file servers. If I cluster file servers between two VMs (one on my “heavy lifter” and another on my “backup”, how do I mirror the data between them? Clustering VMs only provides a single point of access on the network for a resource, it doesn’t exactly replicate data between the two - that is left to the services that serve up that data. I am unsure how I can ensure that file server data between two clustered file server VMs can be properly mirrored. Remember, I only have two devices to be used here - my primary machine and a backup secondary. There is no chance of me obtaining a SAN or any other type of network attached storage. What exists on the machines must act as the storage.  Thanks in advance for any suggestions. Router to router setup works fine with straight cable up to 2-3 meter it is not working for 45 meter why? Which homology groups of a closed orientable 6-manifold can be isomorphic to $\mathbb{Z}^3$? List all $i$ for which there is a closed orientable $6$-manifold $M$ with $H_i(M) =\mathbb{Z}\oplus\mathbb{Z}\oplus\mathbb{Z}$.   I am working on an old exam problem and this one stumped me. Progress so far:  I can take $Y=\mathbb{T}^3 \times \mathbb{S}^3$ and get the desired group for $i =1,5,2,4$ I think. But this construction I believe gives $H_3(Y)=\mathbb{Z}^2$. What to do in this case? How to vertically center content with variable height within a div? Problem applying L'Hopitals rule. How does an isolated body in deep space 'know' it's rotating? We can imagine an object floating in the known universe, maximally distant from any other large mass. Maybe it has been there since coalescing after the big bang.  What physical phenomena tell it whether it is rotating relative to the rest of the universe and therefore experiencing a centrifugal (?) force.  Is it the combined gravity of all other matter? Is it 'spooky action at a distance'?  Is it because it is rotating relative to 'empty space'? How do I clear Bash's cache of paths to executables? Is there an SE for Cell-phones? Where would I ask a question pertaining to an ordinary phone? Or just cell phones in general? I saw Windows Phone while browsing the SE database, nothing else really popped out at me. Google didn't bring up anything either. Is that just too small a community to cover with SE? prove that $\mathbb{Q}^n$is dense subset of $\mathbb{R^n}$