Why does the resistance to electric current increases in a conductor when the temperature is increased?
Why does resistivity increase with temperature?  The explanations I have heard so far are that increasing temperature increases vibrations in the lattice structure resulting in the number of collisions increasing.  But the vibrations from thermal energy are random, so around half of the vibrations would result in the atoms moving out of the electrons way and half would result in atoms moving into the way of the electrons.  And since half of the vibrations result in increasing the drift speed and half reduce it, shouldn't the average drift speed remain the same?
How to install "vanilla" TeXLive on Debian or Ubuntu? Debian and Ubuntu have very good texlive packaging. But I'd like to use tlmgr to have a more fine-grained control about upgrades and which packages I want to be installed.   So how do I install "vanilla" TeXLive on Debian/Ubuntu?   Also how do I make dpkg aware that I have TeXLive installed? General question I have an app X installed on my device in version Y. I don't want to update it to any newer version (Y+z) for some reason. Still, the Google Play Store app always lists updates for X, which keeps me from a simple &quot;update all&quot;. My question, put to a single sentence:  How to hide updates for X permanently from the &quot;available updates&quot; list?   Specific examples First, I know there are alternatives as e.g. the , which can handle this quite well (skip this update, skip all future updates). I prefer a &quot;generic solution&quot;, which does not depend on a 3rd party's market app. Second, I know that  includes a &quot;Market doctor&quot;, which can be used to disconnect an app from Google Play.1 However, in my specific case that only worked for a few hours: I disconnected GTalk, as I don't want it replaced by Hangouts. The update notification disappeared for a few hours, then it was back. No idea what restored the &quot;link&quot;. Third, just to make sure: I'm not talking about the &quot;auto update&quot; feature as discussed e.g. in . I was rather hoping for something close to , but without the need to &quot;freeze&quot; the app in question (which I still want to use, but in the version installed, not in a &quot;future version&quot; available). Fourth: No, uninstalling the app in question is no option here, though it would perfectly hide any future updates from being displayed :) Nor is &quot;freezing&quot;, as the app is used regularly. Fifth: There is a related question for my GTalk example:  However, I want the opposite: No update.  It might very well be that &quot;Google Apps&quot; (and other pre-installed apps) are handled in some specific way, and restore their &quot;market links&quot; themselves somehow. For this case, my question includes: How to prevent that from happening?  Update There's a  discussing the very same issue. Until recently, a work-around for &quot;user installed apps&quot; was to uninstall them and then sideload the .apk – but even that stopped working. Well, re-signing the .apk with a different key might work for user-apps. But both would fail for pre-installed apps (can't sideload them to override; different signature would refuse that install completely). Moreover, there's an  on this by some &quot;joel.bou..&quot;. Not hard to guess, though blanked out: that would be Joël Bourquard. If it's really him, then that's really an issue (for those who don't know: Joël is the dev behind Titanium Backup). Let me quote from the issue:  For the record: in the Android Market days it was possible to &quot;Attach&quot; or &quot;Detach&quot; apps (on rooted devices) with a system tool such as Titanium Backup. But nowadays (with the Google Play Store app) this has become nearly impossible to do, because the complete app list seems to sync from Google's servers and the user has no control over that.  Which explains why detaching with apps like Titanium Backup is no longer permanent. And I'm afraid I've asked the impossible. But I thought the same in the past with other questions, and surprisingly got solutions here. So I do not yet give up hope on this one!  1: what that does is explained by eldarerathis  (thanks to  for digging that up!) How to get a function name as a string? In Python, how do I get a function name as a string, without calling the function?  def my_function():     pass  print get_function_name_as_string(my_function) # my_function is not in quotes   should output "my_function".  Is such function available in Python? If not, any ideas on how to implement get_function_name_as_string, in Python? JMeter : How to record HTTPS traffic? Bravo for allowing comment editing, but what's the explanation for enforcing a five-minute window?  I think this might be over-engineering. If I have a spelling mistake or an inaccuracy I'd like to fix, I don't think the fact that five minutes has elapsed should prevent me from fixing it.  Further, if you are worried people will edit their comments in a way that makes the comment thread nonsensical, they can already do this by deleting their comment. So, limiting the ability to edit isn't really helping much in that regard.  Update  If people don't like this idea, I'm definitely open to hearing your reasons. For now, it seems like an unnecessary limitation of a quite awesome feature.  Update 2  Regarding John's scenario...     Me: Obama is cool!   You: You are right, man!      My edit: Obama is an idiot!   You: You are right, man!   ...this problem can still occur with deletions...     user1: Obama is cool!   user2: No, McCain is cool!   you: You are right, man!        user1: Obama is cool!   ---- deleted -----   you: You are right, man!     So, yes, editing could be abused as you suggest, but discontinuities can occur already because of deletions (and as someone else mentioned, because upvoted comments get prioritized upward).  As for Jeff's argument about rate limiting, I agree that is important, but I don't understand why you can't just use a CAPTCHA to prevent too many edits in a short period of time. Maya is sister of dhara who is doctor. Maya is sister of dhara, who is doctor.   In both statements who is used for which person??? In what sense are Asgardians "immortal" in the MCU? I'm running Drush on a host that has multiple versions of PHP installed. By default, php --version would give you 5.2.x, but php53 and php54 are also available. So in my .bash_profile I have alias php='php53' (php --version = 5.3.13), which makes Drush work for some commands.  However, I still get "Your command line PHP installation is too old. Drush requires at least PHP 5.3.2" messages for some very useful commands.  A couple of really annoying instances:   drush pm-update will report that it has backed up and then updated all modules and core successfully, then return the PHP version error and restore all backups. In verbose mode, the command that comes before the error is: php /home/[username]/drush/drush.php  --backend=2 --verbose --root=/home/[username]/webapps/drup --uri=http://[domain name]  pm-updatecode-postupdate 2&gt;&amp;1 drush archive-dump will immediately return the PHP version error   The other commands I have tried so far work fine. I'm not sure why this would be, if Drush is sometimes using the php53 binary, and other times not, or if it just has trouble detecting the version correctly, but some very important features are broken for me. We have been asked to prove the above statement through the two sub-proofs:   Firstly we must prove that $e^x$ is increasing and then prove that $\log(x)$ is also an increasing function.   After we are asked to prove that using the delta-epsilion definition of a limit that $\lim_{x \to 0} e^x = 1$.   I have done all of this but still don't see where the instructor is going with this. Pipe sound output to file? How to download all files from Ubuntu One? I just installed Ubuntu 14.04, and Ubuntu One isn't installed by default and their download page says it comes pre installed, which doesn't help with anything.  I wanna move all my files from Ubuntu One to Dropbox, but downloading one file at a time from the browser and upload it again to dropbox will take way too long.  Is there any way to get Ubuntu One on Ubuntu 14.04? or somehow download all files from the Ubuntu One website?  I see they updated their site: Can we get wordpress.stackexchange.com added to the list of off-topic redirection sites? I'm noticing a lot of WordPress questions being asked on Stack Overflow lately. I can't flag these to be moved to wordpress.stackexchange.com because it's not in the list:    Can it be added? Are there any other Stack Exchange sites worth adding? What are Harry, Ginny, Ron and Hermione's professions? After the end of the Second Wizarding War Harry Potter later married Ginny Weasley, and the couple had three children of their own: two sons James Sirius, Albus Severus, and one daughter Lily Luna. What are Harry and Ginny's professions? I heard that Harry became an Auror, but what about Ginny, Ron, and Hermione? What can I do to increase passive HF RFID read range? I am working on a prototype, one function of which is to detect whether an object is "in range" by a few cm. Right now I'm just using an Arduino and a cheap  that operates at 13.56 MHz:    I've successfully gotten it to detect the tag, but only at a distance of about 3-4 cm when the tag is oriented parallel to the antenna.  According to my  , the HF band allows read ranges of between 10 cm and 1 m for passive tags, depending on factors like antenna size, tag size and orientation, and transceiver power.  I realize this inexpensive reader is not up to task as-is, but I'm interested in building something that achieves read ranges of 15-20 cm.  Some criteria:   No need to read multiple tags; only whether one tag is in range or not. No need to write to the tag. Cannot use an active tag.   I'm not experienced with RFID reader construction (yet) but am interested in knowing what I should pursue.  Here are some things I've considered:   Ditch the embedded antenna on the cheap RFID reader and construct my own, larger antenna. I'd need to see if the onboard  is up to the task of providing additional power. Look for a different IC around which to build a reader from scratch. Find a ready-made solution instead of trying to build one (more cost-effective?). Use something other than RFID for simple proximity detection.   I am experienced with microcontrollers and basic electronics, and have made audio and lighting projects, but this is a first with RFID. Since I don't need to read multiple tags, which RFID is suitable for, I've considered maybe some sort of magnet and hall-effect sensor, but the range does not seem adequate. I considered using an ultrasonic proximity detector, but the application calls for detecting the tagged object while ignoring untagged ones (ultrasonic would produce false positives on untagged objects). I've considered some sort of reflective surface placed on the object, and detecting reflected light, but the object orientation is not reliable enough to maintain alignment.  So, in a nutshell, What modifications can I make to my existing reader, or what alternate technology should I pursue to achieve 15-20 cm detection of a passively tagged object?  I plan on connecting whatever proximity detector is used to a microcontroller using SPI. My son is almost 3 (33 months) and for the past few months, he has been holding his poop in, to the point that he won't go for many days a time. When this started, the doctor advised us to give him Miralax to make his stool softer so it comes out more easily. Even with the Miralax, he still managed to hold it for two days at a time sometimes, but at least it was coming out at all, so we continued with it.  Anyway, we've been giving him the Miralax for months now, and now he's (supposed to be) going to preschool in September, which of course requires that he be potty trained. We don't want to hold him back since he's developmentally ready otherwise, so we started potty training a few weeks ago.  He picked up the potty training really quickly – for peeing – but he still holds his poop in no matter what. If he's sitting on the potty, as soon as he's about to do it, he stands up and just keeps holding it in (and once he starts to stand, if we even so much as ask him to sit back down, he screams and cries).  We have tried everything to convince him (or distract him enough) to sit and poop: reading books, singing songs, playing games, playing with toys, offering him snacks/treats (graham crackers), giving him stickers, etc. Nothing works.  As of today, it has been a week since the last time he pooped, with the exception of a little bit today and a little bit yesterday (both of which ended up all over the bathroom floor since he won't sit down). The doctor says now we should give him an enema to force it all to come out, but even so, that won't solve anything going forward since he still won't go in his diaper or on the potty in the first place (what are we going to do, give him an enema every week, indefinitely?).  The issue isn't that he's scared of the potty itself, since (a) he was holding it before we started potty training, and (b) he knows exactly what he's supposed to do, since he has no problem with peeing (he sits down himself, points it out afterward, knows that it gets emptied into the big potty, etc.).  It's that he just won't poop, ever – not in his diaper, not on the potty – and the only reason why anything comes out at all is because we've been giving him the Miralax every day (and even then, these aren't "full" poops, just whatever happens to come out because it's soft enough that he's unable to hold it all in).  I'm at a complete loss as to why this even started, and what if anything we can do that would actually help. Is it a behavioral problem? Medical? Both?? Help!    UPDATE: I just wanted to update this question since a lot has changed since I originally posted it. We discovered there was a specific situation where he would go in his diaper voluntarily: in our bedroom closet with the door closed. So we knew then that the withholding was intentional, since it was now established that he could go if he wanted to.  So we let him continue going in the closet and, over time, found that he usually went around the same time each day. Based on that, we then had him sit on the potty when we knew it was most likely he would need to go. We also managed to find two things that distracted him enough to sit (blowing bubbles and playing with his toy laptop).  By doing this, we were able to get him to go on the potty without really realizing it (so he didn't try to fight it), and then made a big deal out of it every time he did. Over time, that helped establish that that's what he was supposed to do, and now he does so voluntarily. He hasn't pooped in his diaper in probably 3 weeks by now.  I wouldn't say he's "fully" potty trained, in that an adult still needs to go with him and distract him (and occasionally remind him when he needs to go in general), but finally we made progress. How to format date and time in Android? Why is negative times negative = positive? Let's say I am missing my novel and I think that my friend might have taken it after I left the place.  1: By the time I left my apartment, my friend was still there, so he might have taken it. 2:When I left the apartment, my friend was still there, so he might have taken it.  I know what 2nd expression means, but not so sure about the first expression. Does it convey the same meaning as the 2nd expression? I have six upvotes for the one question with no intervening history. They have been summarised into two groups - one with 4 events and one with 2 events. However, when you expand either, both show all 6 events. Minor I know, just letting you know. Why did the First Order do this at the cantina? In The Force Awakens, after the First Order are alerted to BB-8, Rey, and Finn's presence at the cantina, an aerial bombardment of the compound begins. They also deploy ground troops.  Wouldn't it have been better to not have an aerial bombardment and simply have the troops surround the cantina, keeping as many people as possible bottled up inside it while they searched both the interior and surrounding area for BB-8?  Instead of a surgical extraction, the strategy that they chose seemed to create chaos and even risked destroying BB-8.  Perhaps this was a sign of the inexperience and emotionally-charged state of Kylo Ren, but General Hux seemed to have more direct authority over the deployment of troops and fighters.  So what was the strategy behind these tactics?