I am using Ubuntu 14.04 and it seems that these packages are not installed. How can I install them as I need them for an application ?  Err  trusty/main i386 Packages   404  Not Found
PPA seems to be constantly offline. Whenever I use sudo apt-get update, this error is shown:  W: Failed to fetch http://ppa.launchpad.net/ 404  Not Found   How do I fix these errors?
My Wi-Fi connection seems to be very weak and the range is very low. It drops by two bars if I just move to the next room and by two if just step outside.  The speed is also not fast as compared to what I get from the router on my desktop .  My laptop is a HP laptop with RTL8723de module. Can anyone help me in bumping up my Wi-Fi speed?  Result of lspci -nnk | grep 0280 -A3:  03:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. Device [10ec:d723] Subsystem: Hewlett-Packard Company Device [103c:8319] Kernel driver in use: rtl8723de Kernel modules: rtl8723de I understand that assuming light is quantized implies that if a lower energy interacts with  metal, it is possible that that quanta will not have enough energy to eject the electron. What prevents two quanta from interacting with the electron at the same time, though, and summing to have enough energy to release the particle. Indeed, what if two separate light rays of the same frequency impact the electron, why can't that free it? A common scenario we run into on Stack Overflow is that we have a troll, spammer, or obvious sock puppet of another user and moderators decide to delete this user. We go on about our business only to find out an hour or two later that the account we just deleted has been recreated, using the same credentials, and is now back to trolling, spamming, or committing voting fraud once again.  I've seen some people recreate an account like this using the same credentials four or five times (multiple times in the last week, in fact). The only thing that stops them is if we remember to suspend the account for right before we destroy it. Accounts recreated using the same credentials as an account that was suspended will be locked into the same suspension the old account was serving.  In particular, this becomes a real problem with sock puppet accounts that have a network association reputation bonus attached to them, because the recreated accounts keep getting that 100 point bonus and can immediately be used for voting fraud, to troll chat, or to spam comments. I've had to deal with quite a few puppet accounts like this by suspending them for a year before deletion.  I propose that all moderator-deleted accounts behave as if they were suspended for a year upon deletion, so that recreating these accounts using the same credentials will cause the new account to be locked in a one-year suspension. This would prevent the new accounts from being used to abuse the site in the same manner as their old account did.  This won't put an end to people creating new spam, troll, or puppet accounts after we delete them, but it will at least slow them down by forcing them to create new login credentials each time. It also would curb abuse of account association bonuses by puppets. Leverage browser caching for Facebook, Google+, or other 3rd party resource files I tested my website with Google PageSpeed Insights.  I did cache optimization in my .htaccess, but it didn't affect resource files that are from Facebook and Google+  Leverage browser caching      http://connect.facebook.net/fr_FR/all.js (20 minutes)      https://apis.google.com/js/plusone.js (30 minutes)      https://oauth.googleusercontent.com/…e:rpc:shindig.random:shindig.sha1.js?c=2 (60 minutes)   What can I do to solve this? Role of capacitors in amplifier What is the significance of a coupling capacitor in a common-emitter amplifier? What would happen if it is removed? What will be  the effect on AC amplifier gain on removing it? Can Java's NullPointerException be changed to report on which variable was null? Using a foreign driver's license in California when staying with a J-1 visa I'm planning to attend a Californian university as a visiting scholar (not paid by the university) on a J-1 visa, for a total of four weeks; a colleague of mine will do the same, but for 12 weeks. I've been told (personally, ie. no citable sources) that, if you're staying on a J-1, you're effectively a California resident for the time you're there, and, therefore, need a Californian driver's license.  I've read up on this and found  that states:     If you are a visitor in California over 18 and have a valid driver   license from your home state or country, you may drive in this state   without getting a California driver license as long as your home state   license remains valid.      If you become a California resident, you must get a California driver   license within 10 days. Residency is established by voting in a   California election, paying resident tuition, filing for a homeowner's   property tax exemption, or any other privilege or benefit not   ordinarily extended to nonresidents.   I'm not planning to vote in any elections, nor will I own a home there, but I'm not sure what would constitute "privileges or benefits not ordinarily extended to nonresidents".  Do we need to get driver's licenses in California, or can we use our foreign licenses? How about day trips to Arizona or Nevada?  Note: this seems to be related to , but my question is specifically about staying there on a J-1. How do I read an entire file into a std::string in C++? How do I read a file into a std::string, i.e., read the whole file at once?  Text or binary mode should be specified by the caller. The solution should be standard-compliant, portable and efficient. It should not needlessly copy the string's data, and it should avoid reallocations of memory while reading the string.  One way to do this would be to stat the filesize, resize the std::string and fread() into the std::string's const_cast&lt;char*&gt;()'ed data(). This requires the std::string's data to be contiguous which is not required by the standard, but it appears to be the case for all known implementations. What is worse, if the file is read in text mode, the std::string's size may not equal the file's size.  A fully correct, standard-compliant and portable solutions could be constructed using std::ifstream's rdbuf() into a std::ostringstream and from there into a std::string. However, this could copy the string data and/or needlessly reallocate memory.    Are all relevant standard library implementations smart enough to avoid all unnecessary overhead?  Is there another way to do it?  Did I miss some hidden Boost function that already provides the desired functionality?     void slurp(std::string&amp; data, bool is_binary) Schengen refusal formulae can be difficult to understand sometimes.  Sometimes an applicant receives a refusal with:       Justification for the purpose and conditions of the intended stay was not reliable.     often accompanied by:       Your intention to leave the territory of the Member States before the expiry of the visa applied for could not be ascertained.   What is meant by this refusal reason?  What are they trying to say? How to make a sound once a process is complete? I have started a long process through a terminal. Is it possible to make the Ubuntu terminal make a sound once the process is complete? This way, I don’t need to keep checking, but will instead be notified through a sound. Selecting pixels in raster using polygon selection tool? I want to reclassify landcover image manually with respect to online imagery. I am looking for a software/plugin/script to manually select raster pixels using polygon selection tool and could be able to enter new value.  I have Arcgis with spatial analyst license. I came across this problem and I believe Lagrange's theorem is the key to its solution.  The question is:     Let $p$ be an odd prime. Prove that there is some integer $x$ such that $x^2 \equiv −1 \pmod p$ if and only if $p \equiv 1 \pmod 4$.   I appreciate any help.  Thanks. These should work by adding spaces or removing spaces from the beginning of the current line or every line between the start and end of a text selection (inclusive).  (edited this question to supplement ) Why is it that Android still can't be installed as regular OS? Are there any technical or others reasons why Android is still a firmware and not an OS which can be just installed without a lot of hassle?  Why there is no universal image which could detect appropriate drivers (kernel modules), partition NAND in some standard way and configure boot loader to boot updated OS version?  What stops Google from making a real (less firmware-like) OS (an OS for small ARM, x86 etc. devices)? I'm in UV Editor and trying to snap the 2d cursor to the vertex ( while the vertices are visible). I turn ON snap and set it to 'vertex mode' , but the 2d cursor won't snap to any visible vertex at all. I can only make it snap to the grid (increment node). Is it a bug ? or did i miss something here ? i'm using 2.8. The following is a homework problem:  Prove that between two roots of the function $f(x) = \exp(x) \sin(x) -1$ there must be at least one root of the function $\exp(x)\cos(x) +1$.  I think it is possible to prove it by simply computing the signs of the functions at $\frac{\pi}{2}k, \pi k, \frac{3\pi}{2}k, 2\pi k$. However, I'm looking for a more elegant way. It is intuitively clear that the roots of $f$ are ˋˋconverging'' to the roots of $sin$ and the ones of $g$ to the ones of $cos$. Do you have any hint how to construct a nice argument based on this observation? What's a recommended alternative to Quickbooks pro? I've just installed Ubuntu to replace Windows. I can't seem to find a good alternative to  to run on Ubuntu. Any help would be appreciated. Layers with different directional drop shadows in Photoshop I am wondering how to have 2 different directional drop shadows in the one file with Photoshop. e.g. 2 different type layers — one has a drop shadow at 90 degrees, the other at -45 degrees.  Currently it seems Photoshop only lets me have 1 universal direction for the whole file, which I find really pointless.   I know how to apply different drop shadows and merge down layers to achieve the same thing, but its tedious and not exactly streamlined for making future changes to that layer.  How is this achieved? Does the Force wane as you age? @Valorum said     ...not to mention the sheer strain that comes from continually using the Force at an advanced age.   To my feeble mind, this doesn't make sense. Approaching 900 years old, Yoda is still as strong as any whippersnapper in terms of Force power and usage. Despite his old age, Obi Wan shouldn't have any problems with using his Force powers.  This got me to thinking, does the Force begin to leave you as you age? Is it a flow of Force power that goes down based on (I hate to say this) a decrease in midichlorian count as you approach your expiration date? Surjective morphism of affine varieties and dimension I'm trying to do the following exercise from the book An Invitation to Algebraic Geometry:     Show that if $X \to Y$ is a surjective morphism of affine algebraic varieties, then the dimension of $X$ is at least as large as the dimension of $Y$.   Could anyone give me a hint? I'm looking for a proof that avoids commutative algebra since it is not mentionned in the book at this point.