No WiFi ubuntu 16.04 LTS won't connect to any network!
Atheros AR9485 wifi disconnects randomly
Live refresh shows "modified" on tagged questions even when unmodified I have a Samsung Galaxy S2, running the latest CM10.1.  I lost the app drawer icon on my Dock; I must have deleted it. The app drawer icon lets you go to the app list, and the widget list.  How do I get the app drawer icon back? The icon looks like a circle with 6 dots inside it. I am typing a command, I remember I have to check something, if I press Ctrl+U the command disappears and I can type something else, but then the command I was typing is not in the history.  Is there a way to recover that command, or a different shortcut that I can press to save somewhere the command? Is a hash a zero-knowledge proof? I’m trying to wrap my head around zero knowledge proofs, but I’m having trouble understanding it.  In my current understanding, zero-knowledge proofs prove to the recipient that the sender has a certain knowledge without disclosing it. Like trying to say your password without actually giving it.  Many sources go at it with a convoluted method like a tunnel where there’s a hidden gate, and Bob is trying to know if Alice can go through the hidden gate. But then it starts saying that Bob should not see Alice enter. Wouldn’t it be easier for Bob to just see Alice go in one tunnel and come out the other? That would not disclose the secret way of opening the tunnel, right?  In that line of thinking, given a one-way function like a hash, couldn’t the other person just hash their secret and let the other see that the hashes compare?  I must be missing something (as there’s a lot of research going into it and hashes are well-known), but I can’t wrap my head around it.  Can someone tell me what’s wrong with my understanding of zero knowledge proofs? Multi-OS Portable TeX system I'm looking to treat myself to a totally portable TeX system and was wondering: is it possible to devise an installation scheme that would run on Windows, Linux and MacOS at the "same" time?  I think TeXLive is the best choice here, but I'd much rather avoid having to maintain three separate TeXLive installations. I'd like the three installations to share the package databases for instance.  I'll be using a 32Gb USB stick, in case it matters.  PS: I think I'm onto something here... will post back when I have a working prototype.  Edit: after reading  I managed to format a USB stick with UDF and have it read and written in Linux and Windows (need to perform some tests on Mac yet). This is the first step towards interoperability.  Edit 2: well, as it turns out, the previous note was useless (the partition table breaks under Windows), I've found  and it works like a charm. The only remaining step is writing a couple of scripts to set the environmental variables and we're done ;) In ZFC, a good way of ordering sets by cardinality is by leveraging the notion of an injection. We define: $$X \lesssim Y \leftrightarrow \mbox{ there exists an injection } X \rightarrow Y.$$  Alternatively, we can leverage the notion of a partial surjection, by which I mean a partial function that hits every point of its codomain at least once.  $$Y \succsim X \leftrightarrow \mbox{ there exists a partial surjection } Y \rightarrow X.$$  Now in ZFC, these approaches are equivalent, in the sense that $$X \lesssim Y \iff Y \succsim X.$$  But if we just consider ZF (that is, we drop choice) then the equivalence breaks down. However, we've still got the forward implication, because the converse of an injection is always a partial surjection.  A specific question. Define that two sets are weakly equipotent iff $X \succsim Y$ and $Y \succsim X$. Question: does weak equipotence imply genuine equipotence? I'm guessing "no."  A general question: In broad terms, how would the structure of the cardinal numbers in ZF be altered by adopting $\succsim$ rather than $\lesssim$ as the fundamental order relation, and taking equality of cardinal numbers to correspond to weak equipotence of sets? I'm guessing this would hide a lot of the (usually very complicated) structure of the cardinal numbers in ZF.  Remark. The order symbols can be written \lesssim and \succsim. Is my Ubuntu vulnerable to SambaCry? I read these two threads:         And I got a little bit worried, is my Ubuntu machine safe? Or am I vulnerable to this vulnerability?  The second article mentioned that:     The flaw actually resided in the way Samba handled shared libraries.   The other thing that they say is all versions from versions 3.5.0 onwards since 2010 are vulnerable.     At that time, nearly 485,000 Samba-enabled computers were found to be exposed on the Internet, and researchers predicted that the SambaCry-based attacks also have potential to spread just like WannaCry ransomware widely.   .   I don't have a samba server however I've got samba-libs package installed.  What, if anything, should I do?  I'm running Ubuntu 16.04. Failed to save undefined: No COMPONENT named markup://svg found : Computing: $\int_0^1 \sqrt[3]{x\log{\frac{1}x}} \, \mathrm dx$ Puzzling Enumerable.Cast InvalidCastException The following throws an InvalidCastException.  IEnumerable&lt;int&gt; list = new List&lt;int&gt;() { 1 }; IEnumerable&lt;long&gt; castedList = list.Cast&lt;long&gt;(); Console.WriteLine(castedList.First());   Why?  I'm using Visual Studio 2008 SP1. $AB-BA=I$ having no solutions The following question is from Artin's Algebra.      If $A$ and $B$ are two square matrices with real entries, show that $AB-BA=I$ has no solutions.    I have no idea on how to tackle this question. I tried block multiplication, but it didn't appear to work. Can we theoretically balance a perfectly symmetrical pencil on its one-atom tip? I was asked by an undergrad student about this question. I think if we were to take away air molecules around the pencil and cool it to absolute zero, that pencil would theoretically balance.  Am I correct?  . As part of an early quest, my PCs are likely to face off against a wizard.  The problem here is that the stat block for Mage NPCs listed in the Basic Rules has a Challenge Rating of 6, while the PCs are going to be five Level 1s. So, instead of messing with the stat block and risk weakening it too much/too little, I'm choosing to create a Level 1 Wizard PC and use it as an NPC for this quest.  The problem with that is that, as far as I can tell, there aren't any designated rules for assigning either Challenge Ratings or XP values to a PC. So, should I just give the wizard a Challenge Rating equal to his level (and thus have him give 200 xp when killed), or is there a better way to do this?  (This is different from , because he's asking for a way to assign a level to an NPC, while I'm asking for a way to assign an XP value/Challenge Rating to a PC (for use as an NPC). Similar questions, but different.) Does this recording sound like the pulses emitted by bats? Out of curiosity, I recorded sounds in an area with lots of bats, hoping to be able to &quot;hear&quot; the bats communicating by lowering the ultrasound to a level down to the frequency which can be heard by a human. After a bit of post-processing, I actually hear interesting sounds, but I'm not sure about the origin. It seems that the frequency of the pulses is too low compared to bats. . Are those actual sounds emitted by bats? If not, what other animal could be the source of those sounds? About the audio The sound was recorded at 10 p.m. at  near a river, with more of a dozen bats flying in this zone. There is a bridge nearby, and the sides of the river are flat concrete, which means that there are a lot of opportunity for sound reflection (although high frequency sounds don't reflect well). Zoom H5 with the default XY directional microphone was used. The bitrate was set to 24-bit. Unfortunately, I used the sampling frequency of 48 kHz instead of the maximum 96 kHz. The following transformations were made to the original audio:  The pitch was shifted by -12 semi-tones, which means that the 20 kHz sound becomes 10 kHz, and 15 kHz becomes 7.5 kHz.   All sounds below 6 kHz were removed.  The sound was amplified.  Severe noise reduction was applied to eliminate everything but the actual sounds emitted by the bats.   The empty parts of the audio were removed.  The sound was amplified once again.   Frequency The frequency analysis of the transformed audio a peak around 9 kHz (18 kHz in the original audio), slowly fading to suddenly drop at 16 kHz (32 kHz in the original audio).   contains many sources with different indications about the frequency range of the sounds emitted by bats, only a few referencing the frequencies low enough to be heard by a human:  Frequency Produced 10kHz-120kHz Ramsey, Gabriel, McGuirk, Phillips, Watenpaugh. Holt Physical Science. New York: Holt, Rinehart and Winston Publishers, 1986.  while most agreeing on the fact that bats use frequencies higher than 20 kHz.  Most bats use frequencies in the range 20-80 kHz, only a few bats use frequencies less than 20 kHz. Long, M.R. &amp; Savage, J.G. Mammal Evolution. New York: Harper, 1976: 108.  The observed range of 18..32 kHz seems too low compared to the sources, but I have an impression that the frequencies vary a lot between different species of bats. Pattern When viewing the audio track (see below), each cry consists of several pulses in two to three sub-groups which are in turn in two groups. Each peak is a bit less than 1 ms. The second group occurs from 40 to 200 ms. after the end of the first one. Each sub-group is separated by 5 to 10 ms. The frequency of every pulse doesn't vary, except the very first pulse. The first cry starts by a more quiet pulse at 6 kHz (12 kHz in the original audio). The second and third cries don't follow this pattern.  indicates that there are three categories of sounds emitted by the bats:  Short clicks,  Frequency-swept pulses,  Constant frequency pulses.   It looks like it's still the third category which we are observing here, and the overall pattern looks similar to the one described for the bats. The gap between the left and the right track is mostly irrelevant: at higher frequencies, microphones become more and more directional, and the sound is reflected less, which leads to such difference.     Note: this question was considered to be on-topic at Biology.SE on . I used sculpting on a plane, and things looks great. However, when I press P to play, the whole ground become a mess. I can see through it in various places, and there are also nasty looking black edges everywhere.  another problem, I made a UV Sphere to display the sky, but when I press , P to play it disappears! What is the speed of sound in space? Given that space is not a perfect vacuum, what is the speed of sound therein? Google was not very helpful in this regard, as the only answer I found was $300\,{\rm km}\,{\rm s}^{-1}$, from , which is not a source I'd be willing to cite. 2 different bibliographies I'm writing my thesis and I would like to make 2 "bibliography" references: The first one would be for the publications I'm in and the second one for external references. I've made one *.bib file right now and it's working but I have no idea how I should work with 2 *.bib files.  Any suggestion will be appreciated. Java FileReader encoding issue I tried to use java.io.FileReader to read some text files and convert them into a string, but I found the result is wrongly encoded and not readable at all.  Here's my environment:   Windows 2003, OS encoding: CP1252 Java 5.0   My files are UTF-8 encoded or CP1252 encoded, and some of them (UTF-8 encoded files)  may contain Chinese (non-Latin) characters.  I use the following code to do my work:     private static String readFileAsString(String filePath)     throws java.io.IOException{         StringBuffer fileData = new StringBuffer(1000);         FileReader reader = new FileReader(filePath);         //System.out.println(reader.getEncoding());         BufferedReader reader = new BufferedReader(reader);         char[] buf = new char[1024];         int numRead=0;         while((numRead=reader.read(buf)) != -1){             String readData = String.valueOf(buf, 0, numRead);             fileData.append(readData);             buf = new char[1024];         }         reader.close();         return fileData.toString();     }   The above code doesn't work. I found the FileReader's encoding is CP1252 even if the text is UTF-8 encoded. But the JavaDoc of java.io.FileReader says that:     The constructors of this class assume   that the default character encoding   and the default byte-buffer size are   appropriate.   Does this mean that I am not required to set character encoding by myself if I am using FileReader? But I did get wrongly encoded data currently, what's the correct way to deal with my situtaion? Thanks. Writing ISO 19139 compliant XML metadata from spreadsheet? I am looking at a way to migrate the metadata from a spreadsheet into ISO 19139 compliant XML metadata documents for a collection of shapefiles. I can parse the data out of the spreadsheet into strings without issue however I am getting lost on how to take those strings and use them to populate the elements.   This example:  covers most of what I want to do, however I would need to generate the tree beforehand based on the ISO 19139 schema. PyXB seems to have schema bundles for OpenGIS but I would like some insight on how to connect everything. Finder search doesn't work properly after Yosemite update Ever since I upgraded to Yosemite, search no longer works properly in Finder. Spotlight works fine but Finder search just gives me a blank window with a spinning ball.  I've tried reindexing and I've also tried deleting Spotlight's .plist file. I restart my MacBook Pro after doing either. Finder search will work for one or two queries and stop again. I don't know what else I can do.