how to recover data from drive which has data but not showing
How I can recover files when the folder shows empty but the files are not deleted?
Error when updating texlive 2015 When I want to update packages of texlive 2015 I get this error? what is the problem?  tlmgr update --list  The locale codeset (cp720) isn't one that perl can decode, stopped at   C:\texlive \2015\tlpkg\tlperl\lib/Encode/Locale.pm line 123. Compilation  failed in require at C:\texlive\2015\tlpkg\tlperl\lib/LWP/UserAgent. pm  line 1001. If nonnegative $f: [0,1] \rightarrow \mathbb{R}$ has a continuous $f''$, then $\int_0^1 \Big| \frac{f''(x)}{f(x)} \Big| \,dx >4$ Isomorphism $f$ preserves the order of an element? Let's say $f$ is an isomorphism $f:G  \rightarrow G'$, where $G$ and $G'$ are multiplicative groups.  Then for $x\in G$, if $f(x) = x' \in G'$. Do we have always have $\text{ord}(x) = \text{ord}(x')$? Why? Permission for snap applications I have some trouble with the Ubuntu notepadqq package. After opening a file from my apache webroot I cannot see any content. Saving the file is also not possible. I thougt this would be a classic permission issue. Therefore, I changed the group of the webroot from root to www-data and added my user to this group. Permissions are 775, so in theory it should now be possible for me to edit files in my webroot. But nevertheless, when I open a file of this directory with notepadqq, it still only shows an empty file.  When using gksudo notepadqq I get the following error message:  No protocol specified QXcbConnection: Could not connect to display :0   I figured out that notepadqq is a so called snap application and I wonder if this is the reason for my problems.  Can someone give me a hint how I could fix this issue (without using 777 permissions)? When do you use at the office? And when do you use in the office? What's the difference between the phrases? Homotopy equivalence of universal cover As part of am exam question (Q21F ), I'm trying to prove that if $X$ and $Y$ are path-connected, locally path-connected spaces with universal covers $\widetilde{X}$ and $\widetilde{Y}$, respectively, then if $X \simeq Y$ then $\widetilde{X} \simeq \widetilde{Y}$.  My attempt might be correct, but it seems too complicated and amongst the jumble I may have made some incorrect assumptions. So what I'm looking for is (a) verification or correction; and (b) ideas as to how I could simplify my argument.    My argument:  Let $p:\widetilde{X} \to X$ and $q:\widetilde{Y} \to Y$ be the covering maps, and let $X \overset{f}{\underset{g}{\leftrightarrows}} Y$ be a homotopy equivalence.  Fix a point $\widetilde{x} \in \widetilde{X}$, let $x=p(x) \in X$ and $y=f(x) \in Y$, and fix $\widetilde{y} \in q^{-1}(\{y\}) \subseteq \widetilde{Y}$. Also let $x' = g(y) \in X$ and fix $\widetilde{x'} \in p^{-1}(\{x'\}) \subseteq \widetilde{X}$.  Define a map $\widetilde{f} : \widetilde{X} \to \widetilde{Y}$ as follows. For $\widetilde{z} \in \widetilde{X}$ let $\widetilde{u}:[0,1] \to \widetilde{X}$ be a path from $\widetilde{x}$ to $\widetilde{z}$. Let $z=p(z)$ so that $u=p\widetilde{u}$ is a path in $X$ from $x$ to $z$. Let $v=fu$, so that $v$ is a path in $Y$ from $y$ to $f(z)$. Lift $v$ to a path $\widetilde{v}$ in $\widetilde{Y}$ with $\widetilde{v}(0) = \widetilde{y}$. Define $\widetilde{f}(\widetilde{z}) = \widetilde{v}(1)$.  Notice that $q\widetilde{v}=v$ so that $q\widetilde{f} = fp$.  Define $\widetilde{g}:Y \to X$ analogously: For $\widetilde{z} \in \widetilde{Y}$ let $\widetilde{a}:[0,1] \to \widetilde{Y}$ be a path from $\widetilde{y}$ to $\widetilde{z}$. Let $z=q(z)$ so that $a=q\widetilde{a}$ is a path in $Y$ from $y$ to $z$. Let $b=fa$, so that $b$ is a path in $X$ from $x'$ to $g(z)$. Lift $b$ to a path $\widetilde{b}$ in $\widetilde{X}$ with $\widetilde{b}(0) = \widetilde{x'}$. Define $\widetilde{g}(\widetilde{z}) = \widetilde{b}(1)$.  Likewise, notice that $p\widetilde{g}=gq$.  Claim: $\widetilde{X} \overset{\widetilde{f}}{\underset{\widetilde{g}}{\leftrightarrows}} \widetilde{Y}$ is a homotopy equivalence.  We have $p\widetilde{g}\widetilde{f} = gq\widetilde{f}=gfp \simeq p$ and $q\widetilde{f}\widetilde{g} = fp\widetilde{g} = fgq \simeq q$.  This shows that $\widetilde{g}\widetilde{f}$ and $\widetilde{f}\widetilde{g}$ are covering translations (deck transformations) and are therefore homotopic to the respective identity maps. So we have a homotopy equivalence.    Any comments would be appreciated. Expected number of times a set of 10 integers (selected from 1-100) is selected before all 100 are seen Suppose I have a set of 100 integers. I randomly choose 10 of those, make a note of which ones I selected, and repeat the process. What is the expected number of times this process must be repeated before I see all 100 integers?  I'm also greatly interested in how this is calculated as I'm trying to increase the expected number of times this process is repeated by changing the set sizes. Find the eigenvector associated with the smallest eigenvalue, not smallest in magnitude Solve congruence system $\ x\equiv m_i-1 \pmod{m_i}\,$ for $\,i = 1,\ldots, k$ Find natural number $x$ so that $$\begin{align}x&amp;\equiv 9\pmod{10}\\ x&amp;\equiv8\pmod9\\ &amp;\ \ \vdots\\ x&amp;\equiv 1\pmod2\end{align}$$ What is the difference between independent and mutually exclusive events? Where do the X-Men get all their money/funding? Charles Xavier's father was a "wealthy nuclear scientist". In the beginning, Charles personally bankrolled the Xavier Institute/X-Men using his family's money.   This included, but was not limited to things like upgrading the mansion to house the training levels, providing a helicopter (the predecessor to the Blackbird jet), providing and replacing uniforms, providing health care for injured students, and rebuilding/repairing the mansion and parts of the Danger Room  repeatedly.  These have all been recurring costs. The mansion has been damaged or outright destroyed a ridiculous number of times. X-Men can't get into a fight without someone's uniform getting damaged.   In one of the more recent stories (I believe it was an early issue of Wolverine &amp; The X-Men), a comment is made about how the X-Men are pretty much bankrupt.  Where has all this money come from over all these years?   Xavier may have had a large war chest to start with, but no other income has ever been mentioned to my knowledge. Student's tuition could account for some of it, but there's no way that's going to fund everything. ISP blocking port 25 My ISP has started blocking port 25 so I can not send email through my dedicated server any more.   I have several options:   Send email through the SMTP server provided by my ISP. Any problems with this? Setup mu server so that it receives email on another port instead of port 25     No one else sends email through my server so it should be OK. How do I do this on a Linux server? Buy a static client IP - these are not being blocked so far.   Which one is preferable? After removing any part the rest can be split evenly. Consequences? How do I convert old Pages documents to Pages '13? I have a document I created with an old Pages version. When I try to open it in Pages '13, I get the message :     This document is too old. Please open and save with Pages '09   I don't have Pages '09 and I don't know where that old version of Pages is and if it will run on Mac OS 10.9.   Is there an easy way to convert the document? If there is no easy way, is there a way to at least extract the text from the document? Two particles with initial positions and velocities $r_1,v_1$ and $r_2,v_2$ are interacting by the inverse square law (with G=1), so that  $$ {d^2r_1\over dt^2} = - { m_2(r_1-r_2)\over |r_1-r_2|^3} $$ $$ {d^2r_2\over dt^2} = - { m_1(r_2-r_1)\over |r_1-r_2|^3} $$  (the inverse square law along the line of separation). What is the complete solution of these differential equations? What is the position of the two objects as a function of time?  After reading a lot on Wikipedia, I've come to the definition of center of mass and relative coordinates:   $$R(t) ~=~ \frac{m_1 r_1 + m_2 r_2}{m_1+m_2}$$  $$\ddot{r}(t) r(t)^2 ~=~ (m_1+m_2)G$$  Where $R$ is the center of mass, and $r$ is the displacement between the particles... Is this correct? How do I proceed to solve the differential equation? Maximize the product of the partitions of an integer Find all integers  $a$,$b$ and $c$ that satisfy the following equations  $a^2=bc+1\tag{i}$  $b^2=ac+1\tag{ii}$    I tried solving came out with following results:  $(i)-(ii)$ gives $a+b+c=0$ which implies, $a^3+b^3+c^3=3abc$  Multiplying equation $(i)$ with $a$ and multiplying equation $(ii)$ with $b$ and then subtracting $(i)-(ii)$ we get  $a^2+b^2+ab=1$ which can be written as  $(a+b)^2-ab=1$ , which can be further written as $c^2-ab=1$. is there any extra latency using an amp sim on wine? I want to use AmpliTube amp sim on ubuntu studio but there isn't a linux version for it, can I just use wine and will it have any extra latency? if so how much latency? Why is the installer not showing any partitions? Why didn't mastery of the Elder Wand move on from Harry? There's a lot of emphasis on Harry becoming the master of the Elder Wand after he defeats Draco. But what constitutes a “defeat”?  It seems that Harry wins a wrestling match with Draco, so now he’s the master of the Elder Wand.  But lots of other stuff happens to Harry: Nagini almost kills him, and he escapes just in time, but his wand breaks. The Snatchers chase him through the forest. He and his friends practically surrender (and Hermione even tries to disguise Harry). Voldemort almost kills Harry in the Forbidden Forest (or actually does, depending on how you look at it).  Why are none of these considered to be “defeats”?