How to find out which file or folder is being locked by process in Windows OS?
How can I identify what application is using a given file?
"In" vs. "after" for future talk came in Low Quality Posts review which was  as "This is commentary on another post, not an answer" by *. But the comment was added 5 times automatically on behalf of that user.        First four comments' time is 2013-07-15 10:23:18Z while the last one's time is 2013-07-15 10:23:19Z. Those comments are still exist. 10K+ users can see that.  Is this a bug or something else?  * Because the comment is added on behalf of that user. How can I run ssh-add automatically, without a password prompt? I want to communicate between several computers on my network (static Ethernet), through SSH. In order to do that I need to run ssh-add every time I log in on a specific machine, how can I do it so that it's set up once and it doesn't ask me for the passphrase every time I log in or reboot my machine?  I know that there is a way that you should add some lines to the bash_profile file, but I still need to type the password every time I reboot/log in to a specific machine.  if [ -z "$SSH_AUTH_SOCK" ] ; then     eval `ssh-agent -s`     ssh-add fi Since the Earth has a magnetic field, can it, in theory, be run through a conductive metal coil to create electricity? How do you get the root namespace of an assembly? Given an instance of System.Reflection.Assembly. How do I fix a puncture? I got a flat/puncture on my bike tube, how can I fix it myself without going to the nearest bike shop? What kind of equipment would I need? Is better healthcare a bane to the long-term survival of the human race? The theory of natural selection has it that individuals with better genes tend to survive and reproduce, passing their genes to their offspring. This gradual process results in a population more adapted at survival. However, due to the advancement in medical science, humans with poorer genes tend to survive and reproduce just as well.  For example, in the past, many people, excluding those with natural immunity due to some genetic mutations, would have succumbed to illnesses such as malaria and typhoid. But with better hygiene and medical treatment, these patients tend to survive.  Now, imagine a future where all illnesses including cancer can be treated. How would it impact the survival of the human race? Would we become more and more vulnerable such that our survival hinges heavily on medical technology, analogous to how an astronaut's survival is dependent on his spacesuit? Are numbers in which all substrings are primes finite regardless of base? Why do I get a segmentation fault when writing to a "char *s" initialized with a string literal, but not "char s[]"? Question is :     Prove that the polynomial $p(x)=x^4-4x^2+8x+2$ is irreducible over the quadratic field $F=\mathbb{Q}(\sqrt{-2})$. [Hint : first use the method of proposition $11$ for the U.F.D $\mathbb{Z}[\sqrt{-2}]$(cf.Exercise $8$, Section $8.1$) to show that if $\alpha \in \mathbb{Z}[\sqrt{-2}]$ is a root of $p(x)$ then $\alpha$ is a divisor of $2$ in $\mathbb{Z}[\sqrt{-2}]$ . Conclude that $\alpha$ must be $\pm 1,\pm \sqrt{-2}$ or $\pm 2$ and hence show that $p(x)$ has no linear factor over $F$. Show similarly that $p(x)$ is not the product of quadratics with coefficients in $F$.]   What I have done so far is :  Suppose $\alpha \in\mathbb{Z}[\sqrt{-2}]$ is a root of $p(x)=x^4-4x^2+8x+2$ we would then have :  $p(\alpha)=\alpha^4-4\alpha^2+8\alpha+2=0\Rightarrow 2=\alpha(-\alpha^3+4\alpha-8)$  i.e., $\alpha$ is a divisor of $2$ in $\mathbb{Z}[\sqrt{-2}]$.  so, I have used the method of proposition $11$ for the U.F.D $\mathbb{Z}[\sqrt{-2}]$(cf.Exercise $8$, Section $8.1$) to show that if $\alpha \in \mathbb{Z}[\sqrt{-2}]$ is a root of $p(x)$ then $\alpha$ is a divisor of $2$ in $\mathbb{Z}[\sqrt{-2}]$  I do not understand why does he mentioned that $\mathbb{Z}[\sqrt{-2}]$ is U.F.D and all... I do not use that at all... It is unnecessarily confusing me or i am unnecessarily getting confused.. hint is actually misleading me :(  Now, I have to prove that $\alpha$ must be $\pm 1,\pm \sqrt{-2}$ or $\pm 2$  i.e., suppose I have $2=ab$ in $\mathbb{Z}[\sqrt{-2}]$ then, $N(2)=N(ab)\Rightarrow 4=N(a)N(b)$   i.e.,$N(a)=1\text{ or }2\text{ or } 4$ i.e., $p^2+2q^2=1\text{ or }2\text{ or } 4$ for $a=p+\sqrt{-2}q$   $p^2+2q^2=1\Rightarrow p=\pm 1 \Rightarrow a=\pm 1$ $p^2+2q^2=2\Rightarrow q=\pm 1\Rightarrow a=\pm\sqrt{-2}$  $p^2+2q^2=4\Rightarrow p=\pm 2\Rightarrow a=\pm 2$    Once I prove that those are the only divisors then I would consider :    $p(1)=(1)^4-4(1)^2+8(1)+2\neq 0$ $p(-1)=(-1)^4-4(-1)^2+8(-1)+2\neq 0$ $p(\sqrt{-2})=(\sqrt{-2})^4-4(\sqrt{-2})^2+8(\sqrt{-2})+2\neq 0$ $p(-\sqrt{-2})=(-\sqrt{-2})^4-4(-\sqrt{-2})^2+8(-\sqrt{-2})+2\neq 0$ $p(2)=(2)^4-4(2)^2+8(2)+2\neq 0$ $p(-2)=(-2)^4-4(-2)^2+8(-2)+2\neq 0$   So, no divisor of $2$ is a root..  Thus $p(x)$ do not have a root in $\mathbb{Z}[\sqrt{-2}]$  suppose I have something like :  $$x^4-4x^2+8x+2=(x^2+ax+b)(x^2+cx+d)=x^4+(a+c)x^3+(b+d+ac)x^2+(ad+bc)x+bd$$  But then, $bd=2\Rightarrow \text { b,d  are  a divisors of 2 in $\mathbb{Z}\sqrt{-2}$}$  But then we have seen that only divisors of $2$ in $\mathbb{Z}\sqrt{-2}$ are $\pm 1,\pm \sqrt{-2}$ or $\pm 2$  So, only possibilities are   $x^4-4x^2+8x+2=(x^2+ax\pm 1)(x^2+cx\mp 2)$ $x^4-4x^2+8x+2=(x^2+ax\pm \sqrt{-2})(x^2+cx\mp \sqrt{-2})$   But these are not possible...  This only tells that $p(x)$ is irreducible in $\mathbb{Z}[\sqrt{-2}]$ but then how do i show this is irreducible in $\mathbb{Q}(\sqrt{-2})$ I was expecting gauss lemma to help but it only works for integers and rationals...  So, please help me to clear this..  Thank you...   P.S : Proposition $11$ is Rational root theorem and Exercise $8$ is that ring of integers of $\mathbb{Q}(\sqrt{-2})$ is an Euclidean domain. Can someone explain how Kat experienced this part of Tenet from her perspective? What steps must an educational institution wanting to recruit good faculty take? There is a cycle in the academia:    Good doctorates from top universities invariably join other top universities as faculty members.  Good students aspire to study in top universities under excellent faculty members.   Suppose a new educational institution or department springs up and desires to set up a top-quality group, how does it break into this cycle? I suppose this could take some years, but is money-power the only thing that could be wielded by the institute to achieve its end? small limits in the pointed category of a category with all small limits In Hovey, Model Categories, he says that given a category $\mathcal{C}$ with a small limits and colimits, if we form the category of pointed objects ,i.e. the category with objects as morphisms $*\rightarrow A$ where * is the terminal object, then this category $\mathcal{C}_*$also has all small limits and colimits.  To prove this, for any Functor $F:J\rightarrow \mathcal{C}_* $ where $J$ is small we compose it with the forgetful functor $\mathcal{C}_* \rightarrow \mathcal{C}$ and take the limit here. My question is how will this give a limit in $\mathcal{C}_*$? we will get an object in the category, but how do we get the arrow from $*$ to that object? So the complex number z is given as   $z=1-cos(2\theta)-isin(2\theta)$  And the question is to find the argument of z in terms of $\theta$.   So, I used the formula for calculating the argument of a complex number:  $arg(z)=arctan (\frac{sin(2\theta)}{1-cos(2\theta)})$  $=arctan (\frac{2sin\theta cos\theta}{1-(1-2sin^2\theta)})$  $=arctan (\frac{2sin\theta cos\theta}{2sin^2\theta})$  $=arctan (\frac{cos\theta}{sin\theta})$  $=arctan (cot\theta)$  $=arctan (tan(\frac{\pi}{2}-\theta))$  $=\frac{\pi}{2}-\theta$  But apparently the answer is $\theta-\frac{\pi}{2}$.  Where might have I gone wrong?  Edit: the domain given in the question for $\theta$ was $0≤\theta≤\pi$ Why the statement "there exist at least one bound state for negative/attractive potential" doesn't hold for 3D case? Previously I thought this is a universal theorem, for one can prove it in the one dimensional case using variational principal.   However, today I'm doing a homework considering a potential like this:$$V(r)=-V_0\quad(r&lt;a)$$$$ V(r)=0\quad(r&gt;a)$$ and found that there is no bound state when $V_0a^2&lt;\pi^2\hbar^2/8m$.  So what's the condition that we have at least one bound state for 3D and 2D? How do I troubleshoot high 'svchost.exe' usage in Windows 7? I'm having a problem with Windows 7 64-bit. I thought it was slow and all, but then I saw that the CPU usage was always around 80% and started searching for a solution.  There are two svchost.exe's consuming around 30% each and in the resources monitor there's a system interrupts consuming 45% all the time. I tried closing the applications, but it makes no difference.  I tried some other things that I've found on Google, like disable system updates, but it didn't work.  I don't know if it will help but here's my specifications:  Core 2 Duo 4400 ATI Radeon 4850 4 GB DDR2 RAM     EDIT  I ran the suggested program and got this information; did I get it right?      EDIT  As you asked here it is, did I get it right now? The other TCP/IP there's nothing.    EDIT  I ran msconfig and took the services that one of the svchost.exe processes was using out of the startup and now my CPU is around 50%, but I still would like to improve it further. I can't lose that much CPU power just because of Windows...    EDIT  Yeah, there's nothing I can do here. I am going to reinstall Windows&nbsp;XP soon, it's really weird... Why is wine made 'from' grapes, but tables are made 'of' wood? (1) Wine is an alcoholic beverage made from fermented grapes or other fruits. (Wikipedia) (2) Tables were made of marble or wood and metal (typically bronze or silver alloys), sometimes with richly ornate legs. (Wikipedia)  Why is 'from' used in (1), whereas 'of' is used  in (2)? Is it a stylistic choice whether to use 'of' or 'from'? Or, in case of chemical changing, differently from changing in shape only, 'from' is preferable? I need to find algorithm that can calculate centroid A (aka gravity center, geometric center, center of mass) from the figure where circles T1,T2,T3,T4,T5,..,Tn intersect AND length of line R from centroid to farthest corner of mentioned figure   Following information is given:   T1   Latitude    =   56.999883   Longitude   =   24.144473   Radius  =   943 T2   Latitude    =   57.005352   Longitude   =   24.151168   Radius  =   857 T3   Latitude    =   57.005352   Longitude   =   24.163356   Radius  =   714 T4   Latitude    =   56.999042   Longitude   =   24.168506   Radius  =   714 T5   Latitude    =   56.994226   Longitude   =   24.15709    Radius  =   771   Result should look like this:  A Latitude = XX.XXXXXXX    Longitude = XX.XXXXXXX  Radius = XX    As you probably already figured out, I am working on software that can find device location by closest Wifi Access Points or Mobile Base stations, as number of access points or base stations might change, I need an algorithm that can adapt to uncertain amount of points.  There are some similar questions  and , but none of them exactly answers to my question. Photoshop: How to draw a guide with an exact distance from another guide Before drawing, I want to draw all guides for my layout. For example, I have a guide line named A already. After that, I want to have another guide named B  parallel with guide A and at 50px distance from it.   I have three solutions:   Draw line B and by "some way", I can see the current distance directly when I'm drawing, so I can make the distance exactly what I want it to be.  Draw line B. And then I use the Ruler tool to see the distance between the two guides. This method has disadvantages: maybe the ruler line that I draw isn't perpendicular with the guides and I'm not sure when the distance is enough. There are other clever ways, that help me get this job done fast and easily, but that I don't know yet. I think Photoshop should support this feature.   What is the best way to achieve this? Limit the post for differents custom post type in the same wp_query I have three custom post type:    books magazine videos   Now i want to limit the number of post for custom post type, for example:   books => 3 post magazine => 2 post videos => 1 post   I used a query post like this:  query_posts( array(     'post_type' =&gt; array(     'books',     'magazine',     'videos' ), 'paged' =&gt; $paged, 'posts_per_page' =&gt; 6,  )); $counter = 1; if (have_posts()) :     while (have_posts()) : the_post();   if (($counter == 2) || ($counter == 3) || ($counter == 4)) {         $div = 'alpha';     } elseif(($counter == 6)) {         $div = 'omega';     } else {         $div = '';     }   The problems is i cant limit the numbers by custom post type.  Any idea?  Thank you :)