After importing picture files from my Iphone, I copied the lot onto my external drive &amp; deleted these files from my Iphone &amp; Photos app. But unfortunately I lost the drive. Is there a way to recover those files on Mac, which were once imported?
I have a 32GB iPhone 4 version 4.0.1. I have many photos on my phone, but I have deleted an important photo from my iPhone. How can I get this photo back from my iPhone?
Eclipse issues warnings when a serialVersionUID is missing.       The serializable class Foo does not declare a static final   serialVersionUID field of type long   What is serialVersionUID and why is it important?  Please show an example where missing serialVersionUID will cause a problem. Packet Tracer 7 on Ubuntu 18.04 cannot launch I am having some issues with Packet Tracer 7 on Ubuntu 18.04: when I launch it with ./PacketTracer7 within the /opt/pt/bin directory, it opens but close immediately with a lot of:     "Warning: libpng warning: iCCP: known incorrect sRGB profile"   error msgs on the console.  The thing is, I installed PacketTracer7 on Ubuntu 16.04 and I remember that I had that issue with the libqt5multimedia.so.5 dependency, but I was able to find the solution (thanks to askubuntu and google) by installing the dependencies. So, everything perfect with 16.04.  But I'm a bit lost now. I can't realize where the issue come from, because I know the qt5 libs are installed on the system.  This is what I see when I run dpkg --get-selections:  libqt4-xmlpatterns:amd64            install libqt5concurrent5:amd64             install libqt5core5a:amd64              install libqt5dbus5:amd64               install libqt5gui5:amd64                install libqt5multimedia5:amd64             install libqt5multimediaquick-p5:amd64          install libqt5multimediawidgets5:amd64          install libqt5network5:amd64                install libqt5opengl5:amd64             install libqt5opengl5-dev:amd64             install libqt5positioning5:amd64            install libqt5printsupport5:amd64           install libqt5qml5:amd64                install libqt5quick5:amd64              install libqt5quickparticles5:amd64         install libqt5quicktest5:amd64              install libqt5quickwidgets5:amd64           install libqt5script5:amd64             install libqt5scripttools5:amd64            install libqt5sensors5:amd64                install libqt5sql5:amd64                install libqt5sql5-sqlite:amd64             install libqt5svg5:amd64                install libqt5test5:amd64               install libqt5webchannel5:amd64             install libqt5webkit5:amd64             install libqt5webkit5-dev:amd64             install libqt5widgets5:amd64                install libqt5x11extras5:amd64              install libqt5xml5:amd64       I've tried to uninstall pt and the qt5 libs and install everything again, but nothing... the same issue.  Did anybody install PacketTracer7 on Ubuntu 18.04?  I would be very happy to have your help for doing it!  Thanks and forgive me for my poor english :) Proving a sequence converges by defining the sequence recursively. Let $a &gt; 0$. Choose $x_1 &gt;$ $\sqrt a$. Define a sequence {$x_n$} recursively as $x_{n+1} = 1/2(x_n + a/x_n)$ for $n &gt; 1$.   Prove that lim$x_n = \sqrt a$.  I think I first want to prove that {$x_n$} is bounded below by $\sqrt a$. But, I am having trouble with this. Could someone help me out a little? Can anyone please give an example of why the following definition of $\displaystyle{\lim_{x \to a} f(x) =L}$ is NOT correct?:  $\forall$ $\delta &gt;0$ $\exists$ $\epsilon&gt;0$ such that if $0&lt;|x-a|&lt;\delta$ then $|f(x)-L|&lt;\epsilon$  I've been trying to solve this for a while, and I think it would give me a greater understanding of why the limit definition is what it is, because this alternative definition seems quite logical and similar to the real one, yet it supposedly shouldn't work. Isekai manga where the mc is reincarnated through his own magic The MC reincarnated himself through his own magic after his party defeated the demon king. Before he used his magic to do so, he took the daughter from the demon king and traveled with her over the world. After he used his reincarnation magic he was born in a noble family where the daughter of the demon king is now working as a maid in this family. He also has an older/younger (not sure) brother. Through his knowledge he starts his training of body, swordsmanship and magic as a baby. Years later his brother wants to play with him but he denies him every time. But one day he accepts it to play tag. His brother can't catch him. After that, he requests from the mc to teach him his magic. He denied again, but made an offer. Only when he can catch him, would he teach him his magic. I hope I'm not mixing up different mangas. Transformation issue with SVG to GeoJSON conversion I have a vector image in SVG format. (without georeferences)    I am trying to display it using OpenLayers to display properties of different polygons in it.  I tried converting it to GeoJSON but the resulting render appears to be stretched (ratios are not preserved).  Is there a transformation or a map projection that I am missing or recreating a GeoJSON from scratch the only relevant choice? Tuning PostGIS for production environments? What PostGIS documentation have you come across that has been helpful when tuning PostGIS for a production environment?  I would like to get together with my DBA to setup a Postgresql/PostGIS installation that is fit for production. I have read that there is some tweaking involved to achieve this, and I was hoping to find the answer on the .  So far I have found some documents on the OpenGeo site helpful, .  And this  is the kind of information I have found helpful, this is probably just basic DB stuff but to me its good stuff.  I would be interested to see what resources have helped others in achieving a stable production installation of PostGIS. How to collapse unused parameters in moderncv? I am writing my CV using the moderncv package. I already have adjusted the CV to meet my needs. Therefore I amplified the maximum number of parameters possible in the \cventry command. However, now I have some ugly spacing in case I do NOT use all parameters (see second \cventry in the MWE for illustration):  Any suggestions to make the spacing collapse in case not all parameters are occupied? As you can see from the MWE I already have adjusted for \ifthenelse command. I use texlive 2014.  \documentclass[11pt,a4paper,sans]{moderncv} \moderncvstyle{banking} \moderncvcolor{blue} \usepackage[scale=0.7]{geometry} \name{John}{Doe} \title{Resume title} \address{street and number}{postcode city}{country} \phone[mobile]{+1~(234)~567~890}  \renewcommand*{\cventry}[9][.4em]{%  \begin{tabular*}{\textwidth}{l@{\extracolsep{\fill}}r}%  \ifthenelse{\equal{\bfseries #4}{}}{}{{\bfseries #4}} &amp; \ifthenelse{\equal{\bfseries #5}{}}{}{{\bfseries #5}} \\%   \ifthenelse{\equal{\itshape #3}{}}{}{{\itshape #3\ifthenelse{\equal{#6}{}}{}{, #6}}} &amp; \ifthenelse{\equal{\itshape #2}{}}{}{{\itshape #2}}\\%  \ifthenelse{\equal{#7}{}}{}{{#7}} &amp; \ifthenelse{\equal{#8}{}}{}{\\ {#8} &amp; \\}% \end{tabular*}%  }  \begin{document} \makecvtitle \section{Education} \cventry{Grade}{Degree}{Institution}{year--year}{M.Sc.}{Majors}{Majors}{} \cventry{}{Degree}{Institution}{City}{}{}{}{} \cventry{year--year}{Degree}{Institution}{City}{Grade}{Majors}{Majors}{} \end{document} How to show that the commutator subgroup is a normal subgroup It is suggested as an exercise in Serge Lang's book "Algebra" to show that the commutator subgroup $G^c$ of a group $G$ is a normal subgroup.   I'd like to do that but I am afraid I need help,   I think the first thing I need to figure out is how a general element in the commutator subgroup looks like, so that I can check that the defining condition for normality is satisfied.  That is, supposing for a moment that a general element in $G^c$ is denoted by $g$, I need to show that $aga^{-1} \in G^c,$ for all $a \in G$.  But here I get stuck, first because I am unsure how to write a general element in $G^c$ - a simple product in $G^c$ is of the form $xyx^{-1}y^{-1}aba^{-1}b^{-1}$ where $a,b \in G$. I cannot see a way to simplify this - I am sure there is one, but somehow I am blind today.  The second thing then is, even if one tries out the conjugation of a simple element like $xyx^{-1}y^{-1}$ in $G^c$, again not simplification offers itself easily I think .. what am I missing ?  An alternative would be to find a homomorphism of $G$ whose kernel is precisely $G^c$ - here I tried to think of this as a map $G \times G \to G$ but whatever I cook up is not a homomorphism.  Thanks for your hints !! Prove that $\mathcal{P}(A)⊆ \mathcal{P}(B)$ if and only if $A⊆B$. Here is my proof, I would appreciate it if someone could critique it for me:  To prove this statement true, we must proof that the two conditional statements ("If $\mathcal{P}(A)⊆ \mathcal{P}(B)$, then $A⊆B$," and, If $A⊆B$, then $\mathcal{P}(A)⊆ \mathcal{P}(B)$) are true.    Contrapositive of the first statement: If $A \nsubseteq B$, then $\mathcal{P}(A) \nsubseteq \mathcal{P}(B)$  If $A \nsubseteq B$, then there must be some element in $A$, call it $x$, that is not in $B$: $x \in A$, and $x \notin B$. Since $x \in A$, then $\{x\} \in \mathcal{P}(A)$; moreover, since $x \notin B$, then $\{x\} \notin \mathcal{P}(B)$, which proves that, if $A \nsubseteq B$, then $\mathcal{P}(A) \nsubseteq \mathcal{P}(B)$. By proving the contrapositive true, the original proposition must be true.    To prove the second statement true, I would implement nearly the same argument, so that isn't necessary to write. So, does this proof seem correct? Also, was the contrapositive necessary? Or is there another way to prove the initial statement? What do you call a person who keeps talking about art; studies art, criticizes art, and thinks he'd be amazing with it. But he doesn't practice it How do i show that $w=z^2$ maps $|z-1|\leq 1$ onto the cardioid $R=2(1+\cos \theta)$? Given the following sentences:        I have even started using them in normal writing.   People can understand your writing better.      Are using and writing gerunds, verbs, or some other part of speech?  Context:  I am prefixing the words in some phrases with abbreviations. Some of the words are giving me trouble in classification. (The message is supposed to be an implicit proof of why adding prefixes to table names in a database is terrible. But I'd like to get it right.)  Here's the full set of sentences for your amusement. However, please restrict your comments to the stated question, for the most part.        com-Don't ver-Listen prep-To adj-Those adj-Other nou-People.    pro-You aux-Should adv-Always ver-Use nou-Prefixes prep-With pro-Your adj-Table nou-Names.    pro-I aux-Have adv-Even ver-Started ver-Using pro-Them prep-In adj-Normal nou-Writing.   com-See adv-How adj-Effective pr-It ver-Is?    nou-People aux-Can ver-Understand pro-Your nou-Writing adv-Better!      (where com means command verb)  This question is part of 3 related questions:     This question   It originally came from How to know the types of windowing system, window manager and desktop environment of a Unix-like OS Why does inductor current lag the applied voltage at its terminal by 90 degrees? I studied electromagnetism and I am currently working with Inductors.  I could not figure out the physical reason based on electromagnetics on why inductor current lags the applied voltage by 90 degrees?  Everywhere I find the Formula as the starting point of explanation which is partially satisfying.    Induced EMF =L di(t)/dt    From the above equation, I understood that when there is a change in current there will EMF induced in the coil terminals. But How this induced EMF makes the current to lag the supply voltage V(t) = Vm*sin(wt)? (Please don't just differentiate and say there is a lag, I am looking for a physical sense on why this happens)  Lets us consider the AC voltage is applied across the terminal at time t=0; At this time there is almost no current. From this transient state how the steady-state is reached where the current is delayed with respect to the voltage?  Can someone help me to figure out why the current lags the Supplied voltage by using electromagnetism, the motion of Charges or any other basic concepts? Three-columns text with figures of 2\columnwidth sed one-liner to delete everything between a pair of brackets? I am working with some text that is full of stuff between brackets [] that I don't want. Since I can delete the brackets myself, I don't need the one-liner to do that for me, but I do need a one-liner that will remove everything between them.  What about parentheses () instead of brackets? Do any queries exist that require RIGHT JOIN, or can they always be re-written with LEFT JOIN?  And more specifically, how do you re-write this one without the right join (and I guess implicitly without any subqueries or other fanciness):   SELECT * FROM t1 LEFT JOIN t2 ON t1.k2 = t2.k2 RIGHT JOIN t3 ON t3.k3 = t2.k3 Beamer continue block in next column I'm looking for several ways to prove that $$\int_{0}^{\infty }\sin(x)x^mdx=\cos\left(\frac{\pi m}{2}\right)\Gamma (m+1)$$  for $-2&lt; Re(m)&lt; 0$