What lens is compatible with Nikon D90 for birding?
What Nikon lens to buy to make photos of birds?
How to use Redstone dust in Minecraft PE? I have Minecraft Pocket Edition and I have collected a lot of redstone dust. For some reason, I couldn't use it for things such as iron doors. Why? It would be nice to  for .  As it is, SE kind of stands out (in a not cool way): What's the difference between iterating over a file with foreach or while in Perl? Extreme Points of a Convex Hull We are all told at school water vapour and carbon dioxide are the top two greenhouse gases, and that they absorb thermal infra red radiation, trap heat and warm up the Earth. My question is how do they do that? Why can't Oxygen or Nitrogen or any other gas not absorb infra red radiation as well as water vapour or CO2? Status of B1/B2 visa after citizenship change? How can I retrieve mp3 metadata in Python? Using a java library from python I have a python app and java app. The python app generates input for the java app and invokes it on the command line.  I'm sure there must be a more elegant solution to this; just like using JNI to invoke C code from Java.  Any pointers? (FYI I'm v. new to Python)    Clarification (at the cost of a long question: apologies) The py app (which I don't own) takes user input in the form of a number of configuration files. It then interprits these and farms work off to a number of (hidden) tools via a plugin mechanism. I'm looking to add support for the functionality provided by the legacy Java app.  So it doesn't make sense to call the python app from the java app and I can't run the py app in a jython environment (on the JVM).  Since there is no obvious mechanism for this I think the simple CL invocation is the best solution. Where do I get a SIS mirage 672 vga driver? Linear regression with fixed point I have a data set to which I want to add a trend line. For my system, there will always be a fixed point on (2, 0). I have the line representing this system, but currently I do not account for the fixed point. Is there functionality to achieve this?  \begin{figure} \begin{tikzpicture} \begin{axis} [     ylabel={Some Time [ms]},     ]     \addplot[only marks, color=red, error bars/.cd,                        y dir=both, y explicit]         table [x=num_of_nodes, y=MyData, y error=stdev_delay_var] {MyData.dat};     \label{plot_one}     \addplot +[mark=none, dashed]          table[y={create col/linear regression={y=MyData}}]         {MyData.dat}; \end{axis} \end{tikzpicture} \caption{Test Results} \label{fig:test_results} \end{figure} Why can't enum's constructor access static fields? Why can't enum's constructor access static fields and methods? This is perfectly valid with a class, but is not allowed with an enum.  What I'm trying to do is store my enum instances in a static Map. Consider this example code which allows lookup by abbreivation:  public enum Day {     Sunday("Sun"), Monday("Mon"), Tuesday("Tue"), Wednesday("Wed"), Thursday("Thu"), Friday("Fri"), Saturday("Sat");      private final String abbreviation;      private static final Map&lt;String, Day&gt; ABBREV_MAP = new HashMap&lt;String, Day&gt;();      private Day(String abbreviation) {         this.abbreviation = abbreviation;         ABBREV_MAP.put(abbreviation, this);  // Not valid     }      public String getAbbreviation() {         return abbreviation;     }      public static Day getByAbbreviation(String abbreviation) {         return ABBREV_MAP.get(abbreviation);     } }   This will not work as enum doesn't allow static references in its constructor. It however works just find if implemented as a class:  public static final Day SUNDAY = new Day("Sunday", "Sun"); private Day(String name, String abbreviation) {     this.name = name;     this.abbreviation = abbreviation;     ABBREV_MAP.put(abbreviation, this);  // Valid } How come this is happening in java? Irreducibility of reciprocal polynomials Given that  $f(x)=\sum\limits_{k=0}^n a_kx^k$ is an irreducible polynomial, show that $g(x)=\sum\limits_{k=0}^n a_kx^{n-k}$ is irreducible too. I don't see how this specific coefficient exchange would preserve the irreducibility. Is there something else I should be looking at? I installed Ubuntu 12.04 a month ago and am using it till now. I failed to notice that all this time there was no sound at all while running Ubuntu, even while playing a game in Wine. The weird thing is that only the startup sound comes when I log in (Indian/African drum tone), then comes the utter silence.  I tested both Digital Output (S/PDIF) and the speakers in the sound settings but can hear nothing.  Any help? I cannot update my Kali Linux, when trying to execute apt-get update I get this error message:  # apt-get update  Get:1 http://kali.mirror.garr.it/mirrors/kali kali-rolling InRelease [30.5 kB] Err:1 http://kali.mirror.garr.it/mirrors/kali kali-rolling InRelease   The following signatures were invalid: EXPKEYSIG ED444FF07D8D0BF6 Kali Linux Repository &lt;devel@kali.org&gt; Reading package lists... Done W: GPG error: http://kali.mirror.garr.it/mirrors/kali kali-rolling InRelease: The following signatures were invalid: EXPKEYSIG ED444FF07D8D0BF6 Kali Linux Repository &lt;devel@kali.org&gt; E: The repository 'http://kali.mirror.garr.it/mirrors/kali kali-rolling InRelease' is not signed. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.   If you need my kernel version:  # uname -a 4.13.0-kali1-amd64 #1 SMP Debian 4.13.10-1kali2 (2017-11-08) x86_64 GNU/Linux   How can I fix this? Suffixes indicating people and language of country vary by country:  _an: American, German, Italian, Belgian, Australian, Russian, Ukrainian, Korean,  Mexican, Brazilian, Chilean, Argentinean, Indonesian, Malaysian, Iranian, Egyptian, Somalian, Palestinian  _sh: English, British, Polish, Danish, Swedish, Turkish,    _ch: French, Dutch  _ese: Chinese, Taiwanese, Japanese, Vietnamese, Portuguese  _no: Filipino, Latino  _i: Israeli  _: Thai  Among the above, _an seems to outnumber other suffixes.  Are there any simple rule to govern appropriation of suffix turning a country name into adjective, indicating people and language of countries in the world in terms of say, region, race, or cultural background? Or is it just discretional? I wanted to know how I could configure multi-touch gestures in Ubuntu. In windows I can do this using the synaptics driver software.  I have already used synclient to configure the taps, palmdetect, scroll, etc. But I'd also want gesture support. Is is even possible?  System-Info: Ubuntu 12.10, Synaptics clickpad Android app intermittently shows blank body in questions and answers (multiple sites) Note: the bug has returned in version 1.0.89 in a somewhat different form. See:      This possible bug report is similar to the bug in  that was deemed not-reproducible.  I can reproduce something similar with more recent app &amp; Android versions.   App Version: 1.0.34 (original report; is still present in 1.0.38, 1.0.42, 1.0.58) Android Version: 4.4 (up to 4.4.4) Device: Motorola Droid Maxx   In the examples below, you can see some blank answer bodies.  These are on different sites, and represent answers with both edited and non-edited text. In the first example, I clicked on the top answer tab to get to the answers, and in the second example I clicked on the bottom "View n Answers" button. (Trying to be a good little tester!)  Because I've seen this blank-answer-body intermittently over the past couple weeks (before the May 7 update), my process to test was just to go to the first site I frequent and then systematically click through the question list until I found a question with answers in which at least one answer was blank.  For all three sites shown below, it was within the first 5 or 7 questions sorted by newest.  Please note that I have seen many questions with several answers, none of which were blank. It is truly intermittent.  Example blank answer body at Workplace.SE:    Example blank answer body at Programmers.SE:    Example blank answer body at UX.SE:    And now here's the kicker, which makes me think this is some sort of content-loading latency issue rather than a rendering issue:  I returned to the left-side menu, selected the User Experience site, picked the same question as above, and then clicked the top answer tab to view answers again, and lo and behold the text is there:    I then went back to the other questions with blank answers, shown above, and the answer bodies were no longer blank.  I am happy to go through more tests/paths and do screenshots if it is helpful.  The same bug also appears in question bodies. SQL Server: Examples of PIVOTing String data Trying to find some simple SQL Server PIVOT examples.  Most of the examples that I have found involve counting or summing up numbers.  I just want to pivot some string data.  For example, I have a query returning the following.  Action1 VIEW   Action1 EDIT   Action2 VIEW   Action3 VIEW   Action3 EDIT     I would like to use PIVOT (if even possible) to make the results like so:  Action1 VIEW EDIT   Action2 VIEW NULL   Action3 VIEW EDIT     Is this even possible with the PIVOT functionality? How to protect website from bulk scraping /downloading?