When I know my question is resolvable by a specific user, how should we notify him/her? I heard there is no direct interaction to the person. Why not?  Its not an personal message I'm asking about, just a notification to user who is very good at some tag.
There has been quite a few times that I wished I could send a message to another user on SO - not ask a question for everyone to see, but just a short message informing them of something or requesting them to do something.  Are there any plans to allow this to happen in the future?  Related:
Integration of $e^{ax}\cos bx$ and $e^{ax}\sin bx$ The locus of the intersection point of two perpendicular tangents to a given ellipse For a given ellipse, find the locus of all points P for which the two tangents are perpendicular.   I have a trigonometric proof that the locus is a circle, but I'd like a pure (synthetic) geometry proof. Are there any massless (zero invariant mass) particles carrying electric charge?  If not, why not? Do we expect to see any or are they a theoretical impossibility? According to the official sources, is the radioactive green crystal that serves as Superman's Achilles' heel actually composed of the noble gas krypton, or is it supposed to be made out of some other substance? If so, what is that substance? Frequency Detection Circuit Design I have been trying to achieve a true mesh displacement on meshes for quite some time, without ever getting it to work.  If I understand it correctly, this experimental feature would allow me to easily displace the vertices of a mesh - or to create new mesh vertexes where needed - to get a displaced mesh in the result, based off an image, but without using a bump map (simpler, faster?).   This all sounds very exciting in theory, but I am having a really hard time finding examples or tutorials that are both recent and whose links function. So I think there is the need for a question here which will call upon detailed and recent answers to bridge that gap.  I'll start with a simple ico sphere:    Then, , I will change the Feature Set to the Experimental one:    I then add a pink granite image to the mesh:    Mark Seams, Unwrap, add image in the UV Editor:      and finally, in the Object Data panel, change the Displacement method from Bump to True as explained :    no result yet:    if I click "Use Subdivision" this is what I get (so I won't click it right now):    Looking into the Node Editor, nothing seems to have changed with the Displacement of the mesh:    so I tried to replicate the node setup seen in  of  (Linear isn't an option, Clip, Single and Repeat are):    ... but the result is a white ICO Sphere, similar to Image 1.  So, can the "Experimental Feature Set" be used to create actual displacement, and modify a mesh?  This is what I'm trying to obtain - but with the image of the texture actually displaying on the mesh (image from ):    .blend file: I have the following recurrence that I've been pounding on:  $$ a(0)=1\\ a(1)=1\\ a(2)=2\\ a(2n)=a(n)+a(n+1)+n\ \ \ (\forall n&gt;1)\\ a(2n+1)=a(n)+a(n-1)+1\ \ \ (\forall n\ge 1) $$  I don't have much background in solving these things, so I've been googling around looking for different techniques. Unfortunately, I haven't been able to correctly apply them yet. So far I've tried:   Characteristic equations Generating functions Plugging it into Wolfram Alpha Telescoping Observation   I'm sure that one or more of these is the way to go, but my biggest problem right now is figuring out how to deal with the idea that there are different equations for odd and even values of $n$. I'm not necessarily looking for a solution (though it would be gratefully accepted), but any nudges in the right direction would be much appreciated.    To follow up, it turned out that the speed problem described in my comment, below was related to the Decimal implementation in Python 2.7. Switching to Python 3.3 (and Java) made everything many orders of magnitude better. Constrains relationship I have the following design. Each user has it's own contacts, it's own hosts and assign those to a domain which belongs only to him.   I want to insure that the host you assign to the domain belongs to the user that domain is assigned to.  Is it something that I have to insure in my application logic?  If I set domains.user_id foreign key to reference host.user_id and user_id.id does it eliminate my issue?    By the way can anyone suggest me a better design for my schema? tl;dr : For SEO, should I redirect from one to the other or list both on the DNS records?    It seems that most experts think that both www and non-www should exist. (Please correct me if I'm wrong.) And Google Webmasters Tools lets you choose which is the main one.  But: will a redirect give all SEO weight to one of them instead of splitting it? (There are other search engines after all, so setting the main one in Google Webmasters Tools might not be enough.) Will having both on the DNS records give them more importance? No difference? Any canon Shadowrun material related to NY/PA/NJ areas? I'm looking for specific, canon (i.e. official, published) references to material for the Shadowrun game-world setting. My game setting is based around the Philadelphia area; I've turned New Jersey into a radioactive swamp, then dropped a nuke in it; I've got some things established for the Philly area, and NYC.  What I want to know is whether anyone knows of specific references to published material dealing with this region. Any mention of the big apple in Shadowrun's history? Any famous names in the area, or megacorps that are mentioned? Anything at all that's part of the published SR work, that I can incorporate, or at least avoid contradicting.  If you have any home-brewed material for that area, I would love to see a link in comments, but please don't put it as an answer. Thanks! =) ASCII to Binary and Binary to ASCII conversion tools? Which is a good tool to convert ASCII to binary, and binary to ASCII?  I was hoping for something like:  $ echo --binary "This is a binary message" 01010100 01101000 01101001 01110011 00100000 01101001 01110011 00100000 01100001 00100000 01100010 01101001 01101110 01100001 01110010 01111001 00100000 01101101 01100101 01110011 01110011 01100001 01100111 01100101   Or, more realistic:  $ echo "This is a binary message" | ascii2bin 01010100 01101000 01101001 01110011 00100000 01101001 01110011 00100000 01100001 00100000 01100010 01101001 01101110 01100001 01110010 01111001 00100000 01101101 01100101 01110011 01110011 01100001 01100111 01100101   And also the reverse:  $ echo "01010100 01101000 01101001 01110011 00100000 01101001 01110011 00100000 01100001 00100000 01100010 01101001 01101110 01100001 01110010 01111001 00100000 01101101 01100101 01110011 01110011 01100001 01100111 01100101" | bin2ascii This is a binary message   PS: I'm using bash  PS2: I hope I didn't get the wrong binary Indefinite article in title of thesis Per the kernel documentation:  This control is used to define how aggressive the kernel will swap memory pages.  Higher values will increase aggressiveness, lower values decrease the amount of swap.   However this is kind of vague. I'm trying to figure out exactly what the parameter ultimately controls. I know it adjusts how aggressively the kernel tries to swap out pages, but what decision making process in the kernel code does it affect?  Does it adjust how long ago a page must have been accessed before the kernel swaps it out? If so what does the default value of 60 represent? And how much is changed by a increment/decrement of 1 (a formula would be nice)? Or does it swap out pages based on their access frequency? Or something else? I'm a bit confused about what Gstreamer does.   Does it come installed by default with Ubuntu ?  If so which version  is the default for 14.04?  Does it provide hardware accelerated video playback (decoding) ?   If so does it work with VA-API and VDPAU or is it an alternative to those?    Thanks for your help Cleaning ‘staining’ off bottom of MacBook screen A couple months ago, I started to see some very small stain spots on the bottom of my MacBook Pro early 2015 screen. It's very annoying to see while I'm using it. When the screen is turned off, I see it as in the picture below. But when it's turned on, I see it as very small water-ish drops. I tried to clean it using water, screen cleaner, and even alcohol, but it didn't go away.  Also that area doesn't feel as smooth as the unaffected area. So, I think it's on the outside of my screen not inside.  Have you ever seen this before? Any suggestions on how to remove it without the need of replacing the whole screen? $\mathbb{F}_p[X]/(X^2+X+1)$ is a field iff $p \equiv 2 \bmod 3$ Minimal and characteristic polynomial have same set of irreducible factors Let $V$ be a vector space over a field $F$ (not necessarily algebraically closed), and $T:V\rightarrow W$ be a $F$-linear map. If $c(T)$ and $m(T)$ denote the characteristic and minimal polynomial respectively, then I want to show that $c(T)$ and $m(T)$ have the same set of irreducible factors.  I know that the claim is true if $F$ is algebraically closed, because then the two polynomials have the same roots. The typical reasoning one gives when $F$ is not algebraically closed is: Take an algebraic closure of $F$, say $K$, and look at $m(T)$ and $c(T)$ in $K$ to conclude the proof. But as far as I know, the proof that any root of $c(T)$ is a root of $m(T)$ requires the fact that $V$ is a $K$-vector space. But we only know that $V$ is an $F$-vector space. I can't understand how to proceed after this. Prove that $\mathbb{Z}$ is not isomorphic to additive group of any vector space over any field.  Proof.  Surpose that: $\phi : (A, +) \rightarrow  \mathbb{Z} $ is an isomorphism. Then there is some $r∈A $ such that $ϕ(r)=1_\mathbb{Z}$. We have $$ 1_\mathbb{Z}=ϕ(r)=ϕ(2(r/2))=2ϕ(r/2)$$  or equivalently that $ϕ(r/2)=\frac{1}{2}$. But this is not in $ \mathbb{Z}$, so there can be no such morphism.  Is my proof above correct? Thanks I'm reading that a 50mm lens is recommended as a first prime lens for DSLR owners as it's supposed to give a 'natural' perspective, but when used on (most) DSLRs, the view is cropped, as if you were zoomed in by 1.5-1.6x, so it's more of a telephoto lens when used on a DSLR. I've also read however that the 50mm lens gives the same perspective on a DSLR and a 35mm, and shouldn't really be considered to be 'equivalent' to an 80mm lens as the crop factor isn't really a magic focal length changer.  Can someone explain how the image is different from (for example) a 50mm lens on a DSLR and an 80mm lens (assuming 1.6x crop factor) on a 35mm camera? How quickly does the Ultimate Meter fill up? The information on the :     Ultimate abilities are powerful abilities only available to a hero   once their Ultimate Meter has filled. Progress towards an Ultimate   persists through death. The Ultimate Meter fills by killing/dealing   damage to enemy heroes, though Mercy gradually fills hers through   healing with her Caduceus Staff, and Torbjörn's turret generates   Ultimate progress for him. The amount of Ultimate gained appears to   vary between heroes, and kills seem to grant less Ultimate than   dealing damage.   Nowhere does it explain how quickly the meter is gained, and what % of meter corresponds to damage.  I know that in addition to that, meter is also passively gained for all heroes, albeit very slowly. What is the rate of that passive Ultimate meter? How does damage correspond to ultimate meter %?