n1vux's Journal http://use.perl.org/~n1vux/journal/ n1vux's use Perl Journal en-us use Perl; is Copyright 1998-2006, Chris Nandor. Stories, comments, journals, and other submissions posted on use Perl; are Copyright their respective owners. 2012-01-25T02:09:35+00:00 pudge pudge@perl.org Technology hourly 1 1970-01-01T00:00+00:00 n1vux's Journal http://use.perl.org/images/topics/useperl.gif http://use.perl.org/~n1vux/journal/ dumping environment etc from batch perl script http://use.perl.org/~n1vux/journal/40205?from=rss <blockquote><div><p> <tt>use Data::Dumper;<br>print Dumper([&nbsp; &nbsp; &nbsp; &nbsp;# like<nobr> <wbr></nobr>...<br>&nbsp; &nbsp; &nbsp; &nbsp;{&nbsp; X=&gt;$^X},&nbsp; &nbsp;# which perl<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;# but not fooled by #!<br>&nbsp; &nbsp; &nbsp; &nbsp;{V0 =&gt;&nbsp; "$]", # perl -v , ditto<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;V =&gt; $^V lt v5.9.0<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ? q(v).(join(q(.),<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (map {ord}<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; split(//,$^V))))<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; : "$^V"}<nobr> <wbr></nobr>,<br>&nbsp; &nbsp; &nbsp; &nbsp;{ ENV =&gt; \%ENV} , # like env<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;#&nbsp; but in actual context<br>&nbsp; &nbsp; &nbsp; &nbsp;{ INC =&gt;\%INC}&nbsp; , # incomparable<br>&nbsp; &nbsp; &nbsp; ]);</tt></p></div> </blockquote><p>The ugly version of V for Version is to handle 5.6-5.9 v strings and 5.10+ version objects without knowing which, if you don't want <code>$]</code> to mess up your syntax highlighting and don't want <code>\005 </code> to trip a terminal echoback string when it vString doesn't print.</p> n1vux 2010-02-24T05:37:29+00:00 journal LinkedIn tips http://use.perl.org/~n1vux/journal/38593?from=rss I see <a href="http://www.linkedin.com/in/guykawasaki">Guy Kawasaki</a> the <a href="http://en.wikipedia.org/wiki/Guy_Kawasaki">Mac Marketing genius and original evangelist</a> has updated <a href="http://www.google.com/search?q=site%3Ablog.guykawasaki.com+LinkedIn">his LinkedIn tips recently</a> to include <a href="http://blog.guykawasaki.com/2009/02/10-ways-to-use.html">Ten Ways to Use LinkedIn to Find a Job</a>. <p>My own <a href="http://www.linkedin.com/">Linked-In</a> tips should be some place easy to reference and update instead of cut and paste, so - </p><ul> <li> A feature of LinkedIn is you can put all your email IDs on one account - anyone who knows any ONE of them can find and invite you to connect. One is primary, but even if you lose access to it, you can use password to reset another as primary. Vice versa, if you forget password, a reset url is mailed to primary. Just don't lose both at once<nobr> <wbr></nobr>:-) Do that NOW, and make a non-Work one primary.</li> <li> Re home email, do you have a "permanent" email forwarder like the @alum.*.edu or @club.org variety?</li> <li> You can upload your work Outlook (or whatever else if you're so lucky) address book without using the LinkedIn toolbar or exposing your password to their webservice by exporting contacts to CSV (File | Import+Export, CSV, Contacts) and uploading that file on the LinkedIn Contacts page.</li> <li> Adding "inside" folks you like or respect from Outlook Inbox to Contacts first will maximize benefit.</li> <li> After upload, it will tell you who is already on Linked In - quick invite to connect - and who isn't - proselytizing invite to join + connect.</li> <li> While you're at it, email the CSV to your other email addresses too, as a back-up.</li> <li> Same thing should work for your existing webmail or other personal email address books.</li> <li> It used to be if one wanted to start a consultancy, one started a newsletter - now it seems one starts a blog. Or a F/LOSS project (or adopts one). And asks/answer Questions on LinkedIn etc.</li> </ul><p> <b>Updates</b> </p><ul> <li> <a href="http://shine.yahoo.com/channel/life/7-deadly-sins-of-networking-and-how-to-avoid-them-443310/">7 deadly sins of networking, and how to avoid them</a> </li><li> <a href="http://lifehacker.com/5375461/tackle-out-of-bounds-interview-questions-by-rephrasing-them">Preparing for Interviews - out of bounds questions</a>. Also <a href="http://lifehacker.com/5283569/know-the-answers-to-these-questions-before-your-job-interview">Know your answers to these questions BEFORE the interview</a> and <a href="http://lifehacker.com/5312095/know-what-questions-to-ask-during-a-job-interview">What questions to ASK when being interviewed</a> </li><li> <a href="http://lifehacker.com/5371151/rsum-achievements-not-worth-the-ink">what to Leave Off Your Resume</a>. <br> both this and the previous refer to Yahoo HotJobs (login required) for more info but <a href="http://www.google.com/search?q='Leave+Off+Your+Resume'">many similar</a> </li></ul> n1vux 2009-03-05T00:44:35+00:00 journal Boston.PM tech meeting Tues Jan 13 (tonight) http://use.perl.org/~n1vux/journal/38278?from=rss Boston.pm meetings are free and open to the public. <p> <b>Boston PM Tech Meeting</b> </p><p>January 13, 2009 7:15 in <a href="http://boston.pm.org/kwiki/index.cgi?MITDirections">MIT room E51-376</a> one last time <br> <i>(changing to larger room next two months)</i> </p><p> <b>Table Driven Testing in Perl</b>, as seen in <a href="http://search.cpan.org/src/URI/Sort-Maker-0.06/t/common.pm">Sort::Maker</a> and <a href="http://www.opensubscriber.com/message/boston-pm@mail.pm.org/11224479.html">Template::Simple</a> - Uri Guttman (Yes, that Uri) http://boston.pm.org/kwiki/ </p><p>NOTE - Lately the lot has filled early, overflow is to Hayward lots (avoid MEDICAL RESERVED spaces!). See alternatives on <a href="http://boston.pm.org/kwiki/index.cgi?MITDirections">wiki </a>.</p> n1vux 2009-01-13T20:28:33+00:00 groups Boston.pm Tuesday June 10th @ MIT http://use.perl.org/~n1vux/journal/36639?from=rss <a href="http://boston.pm.orgkwiki/">Boston.pm</a> June Technical meeting - Uri Guttman will present a quiz exploring people's thoughts on programming <p> MIT E51-376 (or thereabouts), June 10th, 7:15pm ET. <a href="http://boston.pm.org/kwiki/index.cgi?MITDirections">directions</a> </p><p>refreshments courtesy of CIDC.com (who is recruiting perl mongers locally)</p> n1vux 2008-06-10T01:46:15+00:00 groups Boston.pm- Tech Meeting, Tuesday, February 12, at MIT http://use.perl.org/~n1vux/journal/35588?from=rss <p>Boston.pm will have a tech meeting on Tuesday, February 12, at MIT, in building E51, room 376 (directions below), starting at 7:15pm.</p><p>Martin Owens will be giving a presentation on one of his modules, Data::Validate::XSD.</p><p>http://search.cpan.org/~doctormo/Data-Validate-XSD-1.03/</p><p>This module allows the definition of complex data structures and allows validation against them. It is based on the W3C XSD definition, and does not use XML. Features include mirrored-errors (which describe failures in terms of their structural position and the effect on the parents) and minimal dependencies. Use cases include validation data sent to a webpage, validating data used in object creation, and validating XML parsed data.</p><p>RSVP to [Ronald] if you're planning to attend - rjk-bostonpm (at) tamias (d*t) net.</p><p>Pizza and soda for this meeting will be sponsored by Cambridge Interactive Development Corp. Thanks CIDC!</p><p>Ronald</p><p>[Forward by Bill / n1vux ]</p><p>For more information about Boston Perl Mongers, or to subscribe to one of<br>our mailing lists, visit our website at http://boston.pm.org/</p> n1vux 2008-02-05T23:53:14+00:00 groups InfoSec Writers : Using Perl, Postgres and ... http://use.perl.org/~n1vux/journal/35277?from=rss Found on <a href="http://www.infosecwriters.com/">InfoSec Writers</a> <p> <a href="http://www.infosecwriters.com/texts.php?op=display&amp;id=606"> <b>Using Perl, Postgres and SQL to build a Comprehensive, Searchable Database of Firewall Activity on a Checkpoint firewall on the Cheap</b> by Thomas Munn on 23/12/07</a> </p><p>One of the biggest problems in computer security is how to deal with logs. Firewall logs are especially difficult because they often run into the tens to hundreds of gigabytes, and searching them requires expensive, proprietary packages. The purpose of this paper is to help instruct the reader in how to use Postgres and Perl to have a queryable database using checkpoint log files. I do not cover other firewalls but the ideas herein could be applied to almost any firewall supporting output to text files. This paper will give the security practitioner to perform data mining on otherwise useless logfiles. Using the methods described in this document enabled the author to query for almost anything imaginable from a total of 450,000,000 records in under ten minutes. The cost: The cost of the hardware. </p><p> <a href="http://www.infosecwriters.com/texts.php?op=display&amp;id=606">Above reviewlet</a> <a href="http://www.infosecwriters.com/text_resources/pdf/TMunn_psqlcheckpoint.pdf">PDF</a></p> n1vux 2008-01-03T16:46:38+00:00 journal Perl Advent Calendar observes Perl 20th Birthday - twice http://use.perl.org/~n1vux/journal/35157?from=rss <a href="http://perladvent.pm.org/2007/">The Perl Advent Calendar</a> has joined in the Perl 20th Birthday blog-fest with both a classic <a href="http://perladvent.pm.org/2007/18/">birthday card</a> and <a href="http://perladvent.pm.org/2007/19/">a YAPAC-style sample Perl 5.10 program</a>. <p>(<i>Isn't something old, something new, for a different celebration</i>?)</p> n1vux 2007-12-20T05:17:58+00:00 journal BBC "Perl on Rails" http://use.perl.org/~n1vux/journal/35042?from=rss Noted with interest that the <a href="http://www.bbc.co.uk/blogs/radiolabs/2007/11/perl_on_rails.shtml">venerable BBC</a> ported the Rail functionality they liked to a bespoke perl 5.6 MVC. Comment thread says they might be able to open-source it, not yet decided. <p>They mention in passing I18N as a key feature for prefering Perl to say PHP -- multiple languages in one website.</p> n1vux 2007-12-04T13:17:08+00:00 journal Do you or don't you? http://use.perl.org/~n1vux/journal/34988?from=rss c/o <a href="http://blog.oup.com/2007/11/link_love_uk/">OUP Blog</a> "UK book blogger, <a href="http://dovegreyreader.typepad.com/dovegreyreader_scribbles/2007/11/do-you-or-dont.html">Dovegrey Reader, writes</a> in defense of writing in book margins." <p> <a href="http://dovegreyreader.typepad.com/dovegreyreader_scribbles/2007/11/do-you-or-dont.html#comment-91336674">My reply there</a></p> n1vux 2007-11-27T17:16:23+00:00 journal Standard Time - change the smoke detector batteries today http://use.perl.org/~n1vux/journal/34829?from=rss <p>Happy Standard Time! Don't forget to change the smoke detector batteries today too.</p><p>Public safety used to push the Change your Clock, Change your Batteries. The twice a year tweak everything ritual as a convenient reminder that it's best to change smoke/CO detector batteries 2x/year is good, but with DST extended into November (which gives extra daylight for Trick-or-Treat, good),connection of Fire Prevention Month (October) and DST-FireAlarm is more tenuous.</p><p>So if you did it in October, please ignore this message<nobr> <wbr></nobr>:-)</p><p>Otherwise, just consider today October 35th and the chore somewhat overdue.</p><p> &nbsp; I have a pricey LED flashlight that wilk run for months on the leftover power, so I can recycle the batts too. (Marked "U" for used with grease pencil when swapped out.) Which means one or the other is free<nobr> <wbr></nobr>:-) Fits in pocket. "Off" isn't, but only "very low" so you can find it when city power fails</p><p>I g0t mine, the old Elight model, from http://www.eventors-now.com/default.asp at local ham shows, but they new models are available mailorder too<br>http://flashlightsunlimited.com/safelight.htm is newest model with new lower price http://flashlightsunlimited.com/survival.htm like the original</p> n1vux 2007-11-04T16:27:56+00:00 journal Ubuntu Massachusetts InstallFest. http://use.perl.org/~n1vux/journal/34677?from=rss I had a nice chat with Andy Oram at the <a href="https://wiki.ubuntu.com/MassachusettsTeam/Events/InstallFests/2007-10-13">Ubuntu Massachusetts InstallFest</a> which he <a href="http://www.oreillynet.com/onlamp/blog/2007/10/mvc_frameworks_and_the_power_o.html">blogged </a>, and <a href="http://use.perl.org/~brian_d_foy/journal/34673">brian d foy answered</a>. Small world!<p> Thanks to Andy and O'Reilly for sponsoring the doorprizes for the installfest.</p> n1vux 2007-10-14T18:54:14+00:00 journal Happy Pi Day http://use.perl.org/~n1vux/journal/32686?from=rss Today is Einstein's Birthday and Pi Day (3.14 American), so at 1:59 it'll be, to the joy of math geeks everywhere. <p> Previously I've blogged a couple of Compute Pi in Perl items here --- <a href="http://use.perl.org/~n1vux/journal/28505">http://use.perl.org/~n1vux/journal/28505</a> and <a href="http://use.perl.org/~n1vux/journal/32292">http://use.perl.org/~n1vux/journal/32292</a>. </p><p>My use.perl.org user #1492 appears at the 19,915th position in Pi's decimal fraction <a href="http://www.angio.net/pi/bigpi.cgi">http://www.angio.net/pi/bigpi.cgi</a>. </p><p> There are Pi Day observances at Math Departments, schools, and science museums all over <a href="http://www.google.com/search?hl=en&amp;q=pi+day">http://www.google.com/search?hl=en&amp;q=pi+day</a>.</p> n1vux 2007-03-14T18:01:49+00:00 journal More fun with Perl and Pi http://use.perl.org/~n1vux/journal/32292?from=rss A year ago <a href="http://use.perl.org/~n1vux/journal/28505">#28505</a>, I answered a question on Perl Monks about calculating Pi with Math::BigFloat. Today the always funny <a href="http://xkcd.com/c217.html">XKCD</a> made me go back and look at that program, as I had two rather less useful approximations of Pi to calculate now. <p>I'm somewhat surprised that Math::BigFloat doesn't have an AntiLog function for Euler's base 'e' (natural exponent). Hard coding it as a constant isn't terrible, but not nice either. I suppose I could compute it too<nobr> <wbr></nobr>...</p><blockquote><div><p> <tt>#!/usr/local/bin/perl<br> <br>###<br># Adaptation of my prior program to test XKCD's formulas 2007-01-31<br># (9^2 + 19^2/22)^(1/4) = PI<br># (e^pi - pi) = 20 - delta<br># http://xkcd.com/c217.html<br>####<br> <br>use strict;<br>use warnings;<br>use Math::BigFloat;<br> <br>my $DIGS= ($ARGV[0]||10);<br>Math::BigFloat-&gt;div_scale($DIGS+5);<br> <br># (9^2 + 19^2/22) = PI<br>print "(9^2 + 19^2/22) = PI ? \n";<br>my $pi = new Math::BigFloat '9';<br>$pi-&gt;bpow(2);<br>$pi-&gt;bpow(2);<br> <br>my $term= new Math::BigFloat'19';<br>$pi-&gt;badd($term-&gt;bpow(2)-&gt;bdiv(22));<br> <br># $pi-&gt;bsqrt()-&gt;bsqrt();<br>$pi-&gt;broot(4);<br> <br># compare to known-good from bottom of file<br>my $PI=(new Math::BigFloat &lt;DATA&gt;);<br>my $good=$PI-&gt;copy()-&gt;round($DIGS+2);<br>print $good, "\n";<br>print $pi-&gt;round($DIGS+1), "\n";<br>print (&nbsp; &nbsp;($good - $pi), "\n");<br> <br>#####################<br># part 2<br># (e^pi - pi) = 20 - delta<br>print " (e^pi - pi) = 20 ?\n";<br>$pi=$PI-&gt;copy();<br># my $e = (new Math::BigFloat '10')-&gt;bpow((new Math::BigFloat 1)/(new Math::BigFloat $LOG_10));<br> my $E = new Math::BigFloat '2.71828_18284_59045_23536';<br>my $VENTE=new Math::BigFloat '20.0';<br>print "$VENTE \n";<br>my $diff = $E-&gt;copy()-&gt;bpow($PI)-&gt;bsub($PI);<br>print $diff-&gt;round($DIGS)," \n";<br>print " ",(($VENTE - $diff)-&gt;round(3)), "\n";<br> <br># some accurate pi to compare output to:<br>__DATA__<br>3.14159265358979323846264338327950288419716939937510582097494459<nobr>2<wbr></nobr> 30781640628621</tt></p></div> </blockquote> n1vux 2007-02-01T04:24:33+00:00 journal Daylight Saving Time and Perl - Issues http://use.perl.org/~n1vux/journal/32234?from=rss <p>General advice has been that if the OS is patched for the DST change, Perl will be OK between March 11 and Apr 4, when US DST starts 3 weeks early this year. e.g., <a href="http://www.perlmonks.com/?node=daylight+savings">http://www.perlmonks.com/?node=daylight+savings</a></p><p> However, RedHat Enterprise Linux 3's Perl 5.8.0 doesn't notice that the DST date for the OS changed. I grabbed <a href="http://www.google.com/search?q=site%3Ahp.com+dst.pl">a "dst.pl" test script from HP Support's forumsscript</a> and it's working fine everywhere else, but appears to report "unpatched" on the RHEL3 system that is patched according to ZDUMP(8) and release levels.</p><p> Is this perhaps GCC 2 =&gt; GCC 3 transistion legacy baggage? </p><p> That was my guess, and <code>nm(1)</code> seems to support - it reports built with GLIBC232 while RHEL3 is GLIBC323 (subtle, these two numbers). But NM also appears to say it's dyanmically linked and I don't see an older glibc on the box? </p><p>Anyone know for sure? </p><p>=====================</p><p> <strong>UPDATE #1</strong> </p><p>GLIBC2.0 seems to have been a red herring, perl -V says it was built with GCC323, and if I build a new HelloWorld0311.c that expands a time_t value between 2007-03-11 2AMEST and 04-04 2AMEST, it behaves identically. Report from a colleague with a RHEL2.1 system is that perl is correct there, but not on his RHEL3 with home-built Perl 5.8.8 too. This starts to make sense, since Red Hat notes on DST said they were issuing a LIBC patch for RHEL2.1 but only an Olson TZ (zoneinfo) file for RHEL3. </p><p>I think we need a RHEL3 LIBC patch to have Perl and C <code>localtime()</code> working. </p><p>=====================</p><p> <strong>UPDATE #2</strong> </p><p>See BLU.org discussion - <a href="http://lists.blu.org/pipermail/discuss/2007-January/052070.html">http://lists.blu.org/pipermail/discuss/2007-January/052070.html</a>. Either redeploying<nobr> <wbr></nobr><code>/etc/{.|locales?}/localtime</code> from<nobr> <wbr></nobr><code>/usr/share/{.|lib}/zoneinfo</code> after patching or applying <strong>all</strong> RHEL3/4 patches not just the suggested one seems to be the trick. Perhaps the patch failed to refresh because our RHEL3 install is missing the needed tzconfig utility, but it looks like <code>cp</code> would do the trick.</p><p>=====================</p><p> FYI, <a href="http://search.cpan.org/search?query=DateTime%3A%3ATimeZone&amp;mode=module"> <code>DateTime::TimeZone</code> </a> is another issue<nobr> <wbr></nobr>... it has it's own Olson TZ/zoneinfo, that's it's whole point, it's independent, so it <strong>needs</strong> to be updated instead of or in addition to the OS, that's a feature. <a href="http://www.perlmonks.com/?node_id=593399">http://www.perlmonks.com/?node_id=593399</a> <a href="http://beta.nntp.perl.org/group/perl.datetime/2007/01/msg6591.html">http://beta.nntp.perl.org/group/perl.datetime/2007/01/msg6591.html</a> <a href="http://beta.nntp.perl.org/group/perl.datetime/2007/01/msg6583.html">http://beta.nntp.perl.org/group/perl.datetime/2007/01/msg6583.html</a></p> n1vux 2007-01-23T03:25:25+00:00 journal &lt;XML2006&gt; http://use.perl.org/~n1vux/journal/31869?from=rss <p>My excuse for lack of <a href="http://use.perl.org/article.pl?sid=06/12/01/2230229">contributions</a> to the <a href="http://perladvent.pm.org/">Perl Advent Calendar</a> this last week was I was apparently one of the few attendees at <a href="http://2006.xmlconference.org/">&lt;XML2006&gt;</a> not <a href="http://www.technorati.com/search/xml2006">live-blogging</a>, including several folks from <a href="http://xml.com/">O'Reilly</a>. In spite of the O'Reilly presense, I didn't see or hear much Perl there. One speaker does much of his work in Perl; another has done a couple modules, but Java and Dot-Net appeared to be dominant platforms in discussion.</p><p>I returned not so much knowing more, but more aware of what more there is to learn. </p><p>My choice of note-taking being paper booklets and a <a href="http://wiki.43folders.com/index.php/Moleskine_Friendly_Fountain_Pens#Moleskine_Friendly_Fountain_Pens">fountain </a> <a href="http://board.43folders.com/showthread.php?t=538">pen</a> may be retro-tech, but my reasons for limiting online time to a bit of Zaurus email checking has more to do with laptops not having Ergo keyboards. Pleasantly, the hotel supplied note paper was in jacket-pocket shaped booklets. I filled an average of one a day with spider scribble.</p><p>Since I am dealing with WebService and Service Oriented Architecture issues at <tt>$DayJob</tt>, I spent much of my time in the <a href="http://2006.xmlconference.org/tracks/enterprise.html">Enterprise XML</a> track, but sampled <a href="http://2006.xmlconference.org/tracks/hands-on.html"> Hands-on XML</a> and <a href="http://2006.xmlconference.org/tracks/web.html"> XML on the Web</a> as appropriate, especially if "Lessons Learned" or "Best Practices" appeared in the short description. I missed all the good typography and layout talks in the <a href="http://2006.xmlconference.org/tracks/publishing.html">Documents &amp; Publishing</a> track since it's not related to <tt>$DayJob</tt>, although I'd have personally enjoyed lots of that and the Web2.0 mashups on the Web track.</p><p>Suddenly, I feel in a state of sin for typing this inside layout tags instead of semantic tags!</p><p>As I glean nuggets of interest from my notes, and my notes-to-self to google more details on many things heard in passing, I'll try to blog them here.</p> n1vux 2006-12-09T19:28:31+00:00 journal The geometry of 3-manifolds / Poincar&#233; conjecture http://use.perl.org/~n1vux/journal/31308?from=rss Earlier this week, I attended a public lecture in the Harvard "Research Lectures for Non-Specialsts" by Curtis McMullen (Harvard University): The geometry of 3-manifolds. <p>As I expected, this was a (relatively) elementary explication of the recent Poincar&#233; conjecture progress, for which Grigori Pereleman was awarded one of the <a href="http://www.fields.utoronto.ca/press/06-07/060822icm.html">2006 Fields Medals</a>, and is in line for a share of the <a href="http://www.claymath.org/prizeproblems/poincare.htm">Clay Millennium Prize</a> as well. As it happens, McMullen had <a href="http://www.ams.org/notices/199810/comm-fields.pdf">previously won the Fields Medal himself</a>, in part for cross-fertilizing techniques of chaotic-dynamics to the understanding of the larger Thurston's geometrization conjecture -- that Perelman solved (and declined the Medal). (Thurston had previously been awarded a Fields also.) </p><p>Thurston's conjecture seeks to categorize all finite, orientable, unbounded (hyper)surfaces (&#8220;manifolds&#8221;) according to their intrinsic geometries. Orientable leaves out the un-orientable M&#246;bius strips and Klein bottles and their higher-dimensional analogues. Unbounded leaves out sheets of paper, paper-towel tubes, and again the M&#246;bius strip. Finite leaves out an infinite plane, line, or space, or even a infinite spiral cylinder or library. </p><p>McMullen had both an inflated beach-ball and an inflated beach &#8220;inner tube&#8221;, both with marked equators, to demonstrate the topological difference of a sphere and a torus considered as 2-D manifolds. The Sphere passes the loop-test &#8211; any loop drawn on it's surface, including but not limited to all diameters, can be shrunk to a point and thus removed topologically from the sphere, but neither kind of diameter on a torus (slicing of bundt cake and of bagel) can be shrunk to a point and removed, only non-diameter loops can. This is an important distinction &#8211; of all the possible 2-dimensional surfaces (2-manifolds), the topologists' 2-sphere is the only one to pass the Loop test. </p><ul> <li>[Note on terminology - The topologists' 1-sphere (circle), 2-sphere (beachball surface), 3-sphere (hypersphere) are called by geometers the 2-sphere (closed line), 3-sphere (surface of a 3-ball), 4-sphere (hypersurface of a 4-ball). The Geometer's terminology was of course used in your high school geometry class. Why a difference? Geometers measure the embedding metric space. Topologists usually ignore embedding and look at the internal invariant metrics of the surface, such as it's own intrinsic dimension. Geometers would say hyper-surface explicitly if they meant a 3D hypersurface of a 4D-hyper-volume. <a href="http://mathworld.wolfram.com/Hypersphere.html">*</a>]</li> </ul><p>One of the key results of 2-D topology is there are only 3 potential geometries for a 2-D manifold. His illustration is of the three is <a href="http://www.math.harvard.edu/~ctm/gallery/fuchs/tris.gif">[here]</a>. &#8211; Spherical Geometry of course works on a sphere, amusingly the Euclidean geometry works on the torus, and the Hyperbolic geometry works for all higher genus 2-D manifolds (surfaces with more than one &#8220;handle&#8221;, places where a loop can be caught). Why does Hyperbolic work for all higher genus surfaces? All the extra room at the edges &#8211; see the huge number of angels and devils in the outer rings of the infinite regress in Escher's version, visible on his <a href="http://www.math.harvard.edu/~ctm/research.html">homepage</a> (The text their on his homepage includes a quick overview of his topics.) <a href="http://www.math.harvard.edu/~ctm/gallery/fuchs/ngon5.gif">Right-angle pentagons</a> are a key to the hyperbolic plane. </p><p>Jumping up to 3-D hyper-surfaces &#8211; again finite but boundless &#8211; he used Dante's Paradisio/Inferno as his model of the 3-sphere, a nest of spheres proceeding from a point to a large sphere, and down to a small sphere again. (This 3-manifold is embeddable only in 4-space, not 3-space, obviously. Another common model is two 3-balls, meeting at all points on their exterior such that orientability is maintained. This is the hyper-surface of a 4-ball hyper-volume in 4-space.) </p><p>He then used the stage doors of the lecture hall to model a 3-D hyper-torus "hyper-surface" as near cube with sides identified and demonstrate that it too would be loop-linked as was the torus. If we went out the back exits, we'd reappear behind the projection screen; if we exited stage left, we'd reenter stage right. Digging through the floor, we'd drop in the ceiling. He pulled a cord from the door stage right across the stage to the stage left door, saying, if this were a 3-torus, I could reach out this door, back in the other door, to tie this end of the cord to the other end (which he seemingly does), then pull the loop through the space like this<nobr> <wbr></nobr>... and the cord did pull through the door, and slack behind him disappeared out the stage-left door. He half convinced us we were indeed in a hyper-torus mini-universe and stuck there<nobr> <wbr></nobr>:-) , but he did demonstrate that there is no getting shrinking a loop on a 3-torus. </p><p>Original form of the Poincar&#233; Conjecture is basically that the 3-sphere is the only closed finite 3-manifold that passes the loop test. The special case of the geometrization conjecture for 3-D requires 8 geometries, and requires allowing segmenting a manifold piece-wise into those 8 architectures. This conjecture includes Poincar&#233;'s implicitly, since the spherical geometry will pass the loop test, and the others won't &#8211; so if there are no other manifolds, only the unique spherical manifold would pass the loop. The other 7 geometries do not admit a pseudo-sphere, and the spherical geometry has only one possible manifold. Again, the hyperbolic geometry's extra &#8220;space&#8221; provides the flexibility to rigidly geometricize the stranger manifolds. The lovely <a href="http://www.geom.uiuc.edu/graphics/pix/Special_Topics/Hyperbolic_Geometry/HSpace.html">"Hyperbolic Space tiled with Dodecahedra"</a> is locally Euclidean &#8211; all those 90-90-90 rectilinear girder-and-beam intersections &#8211; but globally it has negative curvature. This is the 3-D analog to the hyperbolic tiling with right-angle pentagons, of course. </p><p> <a href="http://math.berkeley.edu/~stall/">One of the many great mathematicians</a> to have thought they had proved the Poincar&#233; Conjecture said using Topological arguments was the way not to prove this topological conjecture; in retrospect, his self-criticism appears correct. </p><p>[I'm omitting the connection between Knot Theory and geometrization of their complement spaces, which is important in the history of the conjectures.] </p><p>Hamilton made great progress on the Poincar&#233;-Thurston problems using &#8220;Ricci Flows&#8221;, to morph a manifold into it's smooth equivalent, but was stymied by singularities in dimensions higher than 2. McMullen showed a movie of Ricci Flow in action [probably <a href="http://www.math.harvard.edu/~ctm/gallery/shrink/starfish.mov">this one</a>. Ricci Flow deforms a curve or surface locally to reduce local curvature &#8211; and this has an emergent global property to create symmetry, and in 1-D curves embedded in 2-D space, as in the movie, this will never cause self-intersection. </p><p>But with 3-manifolds embedded in 4-space, it can cause the singularities that stymied Hamilton and others, and if repeated, that could fragment the manifold into droplets, which didn't seem useful. Perelman's key insight, according to McMullen , is that these singularities are features not bugs &#8211; they're the &#8220;cut here&#8221; points of the necessary partitioning of a peculiar manifold into it's different constituent metric geometries. Perelman added an analogue of physic's &#8220;entropy&#8221; to demonstrate that patching the singularities and continuing the Ricci Flow on the resulting pieces was not an infinite shattering but eventually converged to obvious geometries. </p><p>[Omitting discussion of singularlary democratic on-line referreing of posted pre-prints without actual paper publication.] </p><p>======================== <br> <b>References</b> -- </p><p>In Mathematics, Wolfram's Mathworld is more authoritative than WikiPedia, which may be more readable by non-mathematicians. <a href="http://mathworld.wolfram.com/PoincareConjecture.html">http://mathworld.wolfram.com/PoincareConjecture.html</a> <a href="http://mathworld.wolfram.com/Hypersphere.html">http://mathworld.wolfram.com/Hypersphere.html</a> <a href="http://en.wikipedia.org/wiki/Ricci_flow">http://en.wikipedia.org/wiki/Ricci_flow</a> <a href="http://en.wikipedia.org/wiki/Poincar%C3%A9_conjecture">http://en.wikipedia.org/wiki/Poincar%C3%A9_conjecture</a> </p><p>Links for the Grigori Perelman Preprints at arXiv.org: </p><ul> <li> The entropy formula for the Ricci flow and its geometric applications, 2002 <a href="http://arxiv.org/abs/math.DG/0211159">http://arxiv.org/abs/math.DG/0211159</a></li> <li>Ricci flow with surgery on three-manifolds, 2003 <a href="http://arxiv.org/abs/math.DG/0303109">http://arxiv.org/abs/math.DG/0303109</a></li> <li>Finite extinction time for the solutions to the Ricci flow on certain three-manifolds, 2003 <a href="http://arxiv.org/abs/math.DG/0307245">http://arxiv.org/abs/math.DG/0307245</a></li> </ul><p>Image galleries used for his slides </p><ul> <li>His <a href="http://www.math.harvard.edu/~ctm/gallery/index.html">http://www.math.harvard.edu/~ctm/gallery/index.html</a></li> <li>Another <a href="http://www.geom.uiuc.edu/graphics/pix/Special_Topics/Hyperbolic_Geometry/">http://www.geom.uiuc.edu/graphics/pix/Special_Topics/Hyperbolic_Geometry/</a></li> </ul><p> AMS summary of state of the proof - <a href="http://www.ams.org/notices/200608/comm-perelman.pdf">http://www.ams.org/notices/200608/comm-perelman.pdf</a> </p><p>"Notes on Perelman's Papers", Bruce Kleiner, John Lott, <a href="http://arxiv.org/abs/math/0605667">http://arxiv.org/abs/math/0605667</a> </p><p> "Ricci Flow and the Poincare Conjecture" John W. Morgan, Gang Tian, 473 pages with over 30 figures <a href="http://arxiv.org/abs/math/0607607">http://arxiv.org/abs/math/0607607</a> </p><p>Yau's slides <a href="http://www.mcm.ac.cn/Active/yau_new.pdf">http://www.mcm.ac.cn/Active/yau_new.pdf</a> </p><p>Humor - <a href="http://geekz.co.uk/lovesraymond/archive/eric-buys-an-ipod">Perelman T-shirt</a></p> n1vux 2006-10-13T02:55:31+00:00 journal Knoppix rescue of Linux Laptop http://use.perl.org/~n1vux/journal/31103?from=rss <p>My Linux laptop (thinkpad) was NFG for 24 hours, with GRUB Error 17.<br> &nbsp; [Duration was unrelated to severity, just I had other things to do<br>after I noticed the issue. ]</p><p>Problem was caused by shutting down hard (power switch) during boot<br>(due to real life intervening). Apparently I powered down at exactly<br>the wrong moment during boot<nobr> <wbr></nobr>...</p><p>Error 17 means the MBR was read ok, but the<nobr> <wbr></nobr>/boot filesystem is NG,<br>format not recognized. Loosely translated, this means<nobr> <wbr></nobr>/boot<br>superblock was corrupted.</p><p>Why would shutdown write a superblock? Mis-calculated dirty-buffer<br>flush, maybe? Who knows what hardware does when power is removed? sigh</p><p>Wasn't really all that hard to fix, once I dug around<nobr> <wbr></nobr>... finding the<br>RIGHT args for the FSCK to not fsck-up, of course<nobr> <wbr></nobr>... but getting to<br>the point where I could FSCK at all was awkward.</p><p>Google for Error 17. (Of course I have alternate computers. This does help.)</p><p>Boot Knoppix 5 DVD from UK Linux (Pro) Magazine.</p><p>See that<nobr> <wbr></nobr>/dev/hda2 and<nobr> <wbr></nobr>/dev/hda4 are auto-detected, have icons on<br>Knoppix desktop.</p><p>HDA2 is clean. HDA3 is swap (/mnt/hda2/etc/fstab agrees it should be),<br>but where's<nobr> <wbr></nobr>/dev/hda1 =&gt;<nobr> <wbr></nobr>/boot ? FSTAB says it should be ext3 on<br>hda1.</p><p>Gpart can't guess, it's says everything is 0 size. That's helpful.<br>Just helpful. Can't gpart find and use default alt-superblocks in its<br>heuristics ???</p><p>Knoppix didn't even create a block device for hda1 since it wasn't<br>automountable. So I had to<br> &nbsp; # cd dev<br> &nbsp; # ls hda* # see hda hda2 hda4 all looking similar<br> &nbsp; # man mknod # haven't used this command in YEARS !!<br> &nbsp; # mknod b 3 1 hda1 # follow pattern<br> &nbsp; # chown root:disk hda1<br> &nbsp; # chmod g+w,o-r hda1<br>to match the others.</p><p>Once I did that, it still won't mount -r; it informs me it's got a bad<br>superblock (as I'd figured).</p><p>And FSCK refuses to do anything with bad superblock either.</p><p>I had to read the Man page to find out the default backup-superblock<br>position for a 1K block size, and then ask it "are you 1k blocksize"<br>by doing<br> &nbsp; # fsck.ext3 -b 8193 -B 1024 -n<nobr> <wbr></nobr>/dev/hda1<br>to see if it was a 1k blocksize<nobr> <wbr></nobr>/boot, in which case it would have<br>simple errors, or if (since<nobr> <wbr></nobr>/vmlinux is a big file) someone made it<br>2k or 4k block, that would die gloriously and I'd try the other<br>default -b's for -B 2024 and -B 4096. Since it was ok but for block 3<br>on 6+ pass, I ran it for real.<br> &nbsp; # fsck.ext3 -b 8193 -B 1024 -n<nobr> <wbr></nobr>/dev/hda1<br>It prompted to ignore a read error and prompted to re-write superblock.</p><p>So then I<br> &nbsp; # mount -t<nobr> <wbr></nobr>/dev/hda1<nobr> <wbr></nobr>/mnt/hda2/boot<br>and poke around to see that it looks good. Ok, time to try booting again.</p><p>Then I remembered to<br> &nbsp; # umount<nobr> <wbr></nobr>/mnt/hda2/boot<br>before<br> &nbsp; # umount<nobr> <wbr></nobr>/mnt/hda2<br>so we're clean, and before shutdown Knoppix for reboot and remove DVDrom<nobr> <wbr></nobr>... and see Grub choice menu come up.</p><p>Yeah! Knoppix wins again!</p><p>I'm glad that worked, since I'm still not sure how to mount the<br>several volumes in<nobr> <wbr></nobr>/dev/hda4 via LVM from Knoppix, if I'd had to<br>rescue my data. Knoppix 5 has an LVM command, but<nobr> <wbr></nobr>...</p> n1vux 2006-09-24T03:15:19+00:00 journal LWP::Simple, HEAD method, Firewalls and http_proxy http://use.perl.org/~n1vux/journal/29378?from=rss I decided I needed to try setting up CPAN::Mini at work. Not a problem, only missing File::HomeDir and Compress::Zlib on my development system which I should have anyway.<p> But the minicpan script failed with message <br> <br> <code>unable to contact the remote mirror</code></p><p>After verifying that it was attempting to use the <code>$ENV{http_proxy} standard</code> (by adding debug lines to the CPAN::Mini module), I guessed that I needed to comment out the lines in CPAN::Mini::new():</p><blockquote><div><p> <tt>&nbsp; # croak "unable to contact the remote mirror"<br>&nbsp; #&nbsp; unless LWP::Simple::head($self-&gt;{remote});</tt></p></div> </blockquote><p>since HEAD isn't always as well supported or tested<nobr> <wbr></nobr>... and voila, it works. Apparently LWP::Simple doesn't use UserAgent's env_proxy options for HEAD method.</p><p>I already have a <a href="http://rt.cpan.org/Public/Bug/Display.html?id=18790">bug report</a> submitted at rt.cpan<nobr> <wbr></nobr>... I'm recording the workaround here so folks googling for a solution have a chance to find the work-around.</p> n1vux 2006-04-19T21:28:08+00:00 journal Dan Bricklin's wikiCalc is Perl ! http://use.perl.org/~n1vux/journal/29000?from=rss Dan Bricklin, co-founder of VisiCalc and thus the spreadsheet revolution, is building his GPL2 dual-license collaborative "<a href="http://www.softwaregarden.com/wkcalpha/">wikiCalc</a>" tool <a href="http://www.softwaregarden.com/wkcalpha/installwikicalcperl.html">in Perl</a> with AJAX -- usuable locally, as CGI, or mod_perl. Imagine something with the collaborative advantages of a wiki but with WYSIWYG tables and embedded calculations. I'm going to be looking for some nails to pound with this hammer<nobr> <wbr></nobr>... n1vux 2006-03-15T16:22:42+00:00 journal Boston PM Tech+Social tonight 3/14 (Pi Day) http://use.perl.org/~n1vux/journal/28989?from=rss <a href="http://boston.pm.org/kwiki/">Boston.PM</a> will have a combined Tech/Social Meeting, Tuesday, March 14, 2006. <br> Duane Bronson will present some small scripts he has written [<a href="http://www.mail-archive.com/boston-pm%40mail.pm.org/msg03857.html">Details</a> and <a href="http://www.mail-archive.com/boston-pm%40mail.pm.org/msg03864.html">more detail</a>] <br> MIT E51-376, 7pm [<a href="http://boston.pm.org/kwiki/index.cgi?MITDirections">directions and map links</a>] <br> Then we'll adjourn to Cambridge Brewing Company around 8pm n1vux 2006-03-14T16:53:40+00:00 groups CPAN Purity Test [c/o Planet Debian] http://use.perl.org/~n1vux/journal/28988?from=rss One of the Debian Developers, Joey Hess, blogged about his Perl script to "<i>Test how much of a the guts of a program comes from sweet, delicious CPAN, and how much is nasty perl code you wrote.</i>" <p> <a href="http://kitenet.net/~joey/blog/entry/cpan_purity_tester-2006-03-12-22-29.html">http://kitenet.net/~joey/blog/entry/cpan_purity_tester-2006-03-12-22-29.html</a> via <a href="http://planet.debian.net/">http://planet.debian.net/</a> </p><p>I'm not sure that's a really useful reuse metric, but it's sure amusing.</p> n1vux 2006-03-14T16:48:23+00:00 journal Fun with Math::BigFloat and #perl http://use.perl.org/~n1vux/journal/28505?from=rss I'm not usually an irc-nik, but I had fun tonight thanks to trying #perl on freenode. Pete_I posted a query for help with a "borked" program to compute Pi, and was ignored by the folks busy debating VI vs Emacs. (Do they do that daily or only on weekends?) <p>Hoping to be helpful, and out of curiosity -- I have always loved math, or at least since 2nd grade -- I clicked on his paste link. It referenced a website by someone I vaguely knew and certainly knew of 20 years ago when our research areas overlapped and have seen in the math literature since then, David H. Bailey. I remember noting his breakthrough on direct computation of digits of pi (in HEX), and his website to search for your name (in ascii) in Pi, but I had <b>not</b> yet played with his new algorithm. I had played with searching for strings of DIGITS in a pre-computed Pi of a mere 10_000 decimal digits with Perl last year. Dave's 5-bit ascii search in Pi searches 4_000_000_000 bits, 5 orders longer. </p><p> So I asked Pete_I <b>what</b> was wrong, but the only reply was a punch-line <i>just the facts ma'am</i> from a sniper. So after a short break, I asked him by direct message. It seemed his coding of the algorithm was losing precision after 10-15 decimal places, even though it was using Math::BigFloat. </p><p>After several false starts -- and reading the academic paper three links into DBH's pages -- I found that, unless we used the modular arithmetic hacks DBH used to avoid using arbitrary precision packages, we needed to increase the default precision and use BigFloat for all numeric variables, not just <code>$pi</code>. In the process, I refactored the code to compute the sequence of the series first and then evaluate the polynomial by the classical add-and-divide technique. </p><p>My final code differs from Pete_I's code primarily in reading in, printing, and subtracting from the comparison value. (And commenting out Acme::Comment<nobr> <wbr></nobr>;-) </p><ul> <li> <a href="http://www.perlmonks.org/?node_id=526243">Pete_I's node "Pi Generation"</a></li> <li> <a href="http://crd.lbl.gov/~dhbailey/">DBH Home with short description of the new formual for Pi</a>,</li> <li> <a href="http://crd.lbl.gov/~dhbailey/pi/">DBH's pi pages</a></li> <li> <a href="http://pi.nersc.gov/">DBH's Search for your name in Pi page</a></li> </ul> n1vux 2006-01-29T04:51:52+00:00 journal Back from the Future - or - Fixing file dates retroactively http://use.perl.org/~n1vux/journal/28197?from=rss I had a problem<nobr> <wbr></nobr>... when we rebuilt my Linux server a year ago, the hardware Real Time Clock (RTC) got set to the wrong decade, probably due to a order-of-date issue, maybe a typo. So each time it rebooted, it reset the year to 2025, but otherwise correct. I usually fixed it fairly quickly, but took me quite a while to figure out that the RTC was the problem and how to re-write the RTC from commandline. <p>I looked at <code>Date::Calc</code> and <code>DateTime</code> modules, but neither made it easy to subtract 20 years from a file timestamp from <code>(stat)[9]</code> and reapply with <code>utime</code>. And DateTime.pm required 3 prerequisites, one of which required Module::Build. Eventually I'll hook up the CPANDebian magic, but not until after I upgrade the OS, so that was out. </p><p>So, old trick -- separate the problem into easy steps.</p><blockquote><div><p> <tt>perl -MPOSIX=strftime -MFile::Find<br>&nbsp; -le 'find( { wanted=&gt;\&amp;foo , follow=&gt;1}, "/");<br>&nbsp; sub foo {return if -M $_ &gt; 0;<br>&nbsp; &nbsp;my $ts=strftime ("%Y%m%d%H%M.%S",<br>&nbsp; &nbsp; &nbsp; &nbsp; localtime ((stat($_))[9]));<br>&nbsp; &nbsp;return unless $ts=~s/\b(202[45])/$1-20/e;<br>&nbsp; &nbsp;print "touch -t $ts $File::Find::name";}' \<br>&nbsp; | tee touch-2025<br>$ (set -x; .<nobr> <wbr></nobr>./touch-2025)<br>+ .<nobr> <wbr></nobr>./touch-2025<br>++ touch -t 200502052006.08<nobr> <wbr></nobr>/<br>++ touch -t 200412192026.04<nobr> <wbr></nobr>/homex<br>++ touch -t 200412192133.13<nobr> <wbr></nobr>/homex/wdr<br>++ touch -t 200412192026.04<nobr> <wbr></nobr>/homex/wdr/.bashrc<br>++ touch -t 200412192026.04<nobr> <wbr></nobr>/homex/wdr/.bash_profile<br>...</tt></p></div> </blockquote><p>Of course, I tested it as an unprivileged user before running it as <code>root</code> from<nobr> <wbr></nobr><code>/</code> (via <code>sudo bash</code>).</p> n1vux 2006-01-02T03:59:37+00:00 journal Merry Christmas to all http://use.perl.org/~n1vux/journal/28123?from=rss Or other seasonal holiday(s) of your choice, as appropriate.<p>I've had fun contributing to Jerrad's <a href="http://web.mit.edu/belg4mit/www/">YAPerl Advent Calendar</a> this season. I only wish I'd not gotten ill so could have gotten my 3rd submission in a little earlier. Thanks to Jerrad for keeping that fine tradition of Mark's going.</p> n1vux 2005-12-25T03:56:33+00:00 journal Python Considered Dangerous, but what to do? http://use.perl.org/~n1vux/journal/27453?from=rss <b>Python Considered Dangerous <br>Famine threatens, Modest Proposals needed <br> <em>or, an Ecology of Free Software - </em> </b> <p>I was reminded by Nat's comment on <a href="http://use.perl.org/~gnat/journal/27449">learning Python</a> and a comment on Boston.PM list referring to a <a href="http://developers.slashdot.org/article.pl?sid=05/10/21/1240258&amp;from=rss">Slash-Dot thread (that strangely claims PHP has defeated Java)</a> that that I had had a revelation at a LUG meeting recently. </p><p> I have heard two reasons to <em>prefer</em> Python to Perl that made sense -- and the source and sense of the second one scared me. </p><ul> <li> <b>A friend with little remaining wrist does his scripting in Python</b>, since his voice-typer works better with a non-punctuated language. <br>(<em>Yes he can reconfigure it to do Perl, but he can do Python with the same training set as email and data files, and it doesn't like switching training sets. If he could switch brands he would, but there's not a good open source alternative in voice-typers yet, there's a very high cost to entry to that market. I assume he uses auto-indent so he doesn't have to say TAB TAB TAB for each line.</em>) <br> <b>This is reasonable, limited, and harmless.</b></li> <li> <b> <a href="http://www.markshuttleworth.com/bounty.html">Mark Shuttleworth is pushing</a> to make Python the dominant scripting language of the universe.</b> If I understood <a href="http://mako.cc/">Mako</a> correctly <a href="http://mako.cc/copyrighteous/2005/Oct/24#20051024-00">at his Ubuntu talk</a> to <a href="http://www.blu.org/cgi-bin/calendar/2005-oct">BLU </a><blockquote><div><p>&#171;Python: One goal is "python everywhere." It is the energy that surrounds us and binds us as Jeff Waugh has said. </p><p>&#171;We are working hard to have everything extensible by Python. Mark loves Python.&#187; <br>[<a href="http://mako.cc/talks/20051019-ubuntu_talk/ubuntu_overview_and_development-notes.html">notes</a>]</p></div> </blockquote><p>In Q&amp;A, Mako elaborated that having one scripting language for system install, config, startup files and for application customization/integration/scripting is obviously a win. But the reason for preferring Python over Perl in the <a href="http://mako.cc/talks/20051019-ubuntu_talk/slides/img12.html">Gnome+Python+security</a> Ubuntu-preferred feature-set is the simplicity of syntax will make it more acceptable / accessible as a mere scripting language to non-programmers, the desktop users. The minimal subset is perceived to be smaller. </p><p> <b>This is reasonable, potentially pervasive, and thus dangerous.</b> Since he's the millionaire <a href="http://news.bbc.co.uk/hi/english/sci/tech/newsid_1989000/1989461.stm">astronaut</a> behind <a href="http://planet.ubuntulinux.org/">Ubuntu</a>, Mark <em>can</em> do this. If he succeeds in making Ubuntu the replacement for Windows -- and all FLOSS users should hope he does, even Perl Mongers -- <b>Python will be</b> <em>the</em> replacement for WinDos ComManD files and VBA scripting (Visual Basic for Applications), and the replacement for most BASH too.</p></li> </ul><p> <b>Modest Proposals Needed</b> </p><p>In the sense of Swift, we need some <a href="http://www.victorianweb.org/previctorian/swift/goodman2.html">modest proposals</a> to let us see the <a href="http://www.bartow.k12.ga.us/psych/crisis/elephant.htm">elephant in the room</a> -- maybe some <a href="http://www.nntp.perl.org/group/perl.perl6.meta/424">cup-throwing</a> too, because Jon's comments that Perl is in trouble</p><blockquote><div><p>&#171; unless we can come up with something that will excite the community, because everyone's getting bored and going off and doing other things&#187;</p></div> </blockquote><p> is still, or again, true. <b>Perl6 is exciting, but what Perl community will be left for it to excite when it is done?</b> They are wandering off -- even Nat is learning Python, though he says it's only a dalliance, not an affair of the heart -- but more seriously, the niches that were once Perl's alone are crowded with too many kinds of <a href="http://www.biology-online.org/2/11_natural_selection.htm">finches</a> in one niche.</p><p>I'll play <a href="http://www.onelook.com/?w=Devil's+Advocate&amp;ls=a">Devil's Advocate</a>.(or perhaps Estate Agent and look at our location, location location selling points) </p><p> <b>Is Parrot the redemption of Perl, or the path to obscurity?</b> If Parrot makes Python run faster and gives it native access to all of CPAN and 6PAN, does Perl become just the esoteric language for a small band of FLOSS gurus to implement modules for Ubuntu and Open Office users to call from their Python scripts? </p><p> <b>So what "ecological" niches has Perl had in the past, and where can Perl5/Perl6 continue expand in the future?</b> </p><ul> <li> <b>PHP</b>, a watered down Perl, has colonized the low-end LAMP niche (in spite of mod_perl and FastCGI actually being faster and safer, contrary to mythology).</li> <li> <b>Ruby on Rails</b> seems to be gaining mind-share in larger and rich-client (AJAX) LAMP applications, as if <b>Catalyst, Maypole, CGI::Applicaiton, FastCGI</b> didn't exist. Having a cool name that plugs the language is an advantage?</li> <li> <b>Java</b> (contrary to the<nobr> <wbr></nobr>/. article) retains the high ground of stick-build web-apps, thanks in part to the high-profile <b>Apache+Struts</b> library-stack community.</li> <li> <b>Python</b> may well get the <b>VBA</b> and <b>Better Shell</b> niche thanks to <b>Ubuntu</b> and the backfeed to Debian (if FLOSS wins all).</li> <li>The added <b>academic</b> respectability of the Junctions, Grammar, <em>etc.</em> of Perl6 may give Perl an academic life, but the academic life can be the kiss of death, look at poor Pascal and SmallTalk.</li> <li> <b>One liners</b> rule! but the are not a community-building niche.</li> <li> <b> <a href="http://use.perl.org/article.pl?sid=05/10/25/127229&amp;from=rss">CPAN</a></b> continues to be the "killer app" as the mechanism <a href="http://use.perl.org/comments.pl?sid=29148&amp;cid=44143">implementing</a> <a href="http://en.wikipedia.org/wiki/Brad_Cox">Cox's</a> <a href="http://www.virtualschool.edu/cox/pub/92ByteWhatIfSilverBullet/">Software IC</a> <a href="http://www.stepwise.com/Articles/Technical/Objectware_Realities.html">marketplace</a>, but will that be an advantage forever? <a href="http://use.perl.org/~gnat/journal/27449">Python may not have a repository</a> yet, but it will on the Ubuntu side, and <em>must</em> eventually get there for all platforms. PHP and JScript already do. The new Debian.CPAN.org provides automated packaging, which Ubuntu is planning for Python.)</li> <li> <b>BioPerl</b> <em>owns</em> not just its niche but its whole microclime, because of a standard SDK.</li> <li> <b>Thick-Client</b> programming -- possible with TK or Win32 libs, but this is not "mainstream", and not likely to be competitive</li> <li>WebServices -- should be a sustainable niche, but limited growth for the same reason -- largely professional coders, this is more complicated than scripting users usually get.</li> <li>Systems Administration -- well established in proprietary Unixes and Linux; likely to remain so in Proprietary and non-Ubuntu Linux. But if Python takes over on Ubuntu and thence Debian and thence DCC- and thence LSB-based distros, perhaps this is a shrinking pool?</li> </ul><p> <b>In the market place of ideas</b> it's grow or die. The Media new and old -- magazine publishers, slash-dot, book publishers, stock pickers, bloggers -- treat everything as if you aren't growing you <em>must</em> be shrinking, and if you aren't the fastest growing you aren't growing. This is strange logic, but all too often self-fulfilling. </p><p>So, where do we grow?</p> n1vux 2005-11-04T23:51:11+00:00 journal Major win for Open Source Science -- and BioPerl too? http://use.perl.org/~n1vux/journal/27331?from=rss Duplicating a SubmitStory for the record<nobr> <wbr></nobr>... <p> <a href="http://news.bbc.co.uk/2/hi/health/4378624.stm">BBC</a> reporting <i> <b>"Gene map points to personal drugs"</b> </i> </p><p> <i> "Experts say the study should simplify genetic research Scientists have completed a map of the most common differences in the human genome, which could lead to personalised treatments for diseases."</i> </p><p>This is a major ($100M) OpenSource science project -- their CopyLeft License on the data requires foreswearing patenting results of research using the HapMap. <a href="http://eprints.law.duke.edu/archive/00000882/01/ssrn_574863_open.pdf">Article</a> </p><p> <a href="http://doc.bioperl.org/bioperl-live/Bio/PopGen/IO/hapmap.html">Bio::PopGen::IO::hapmap.pm</a> is a part of <a href="http://bio.perl.org/">BioPerl</a> SDK. I'm not sure if only the data is accessed via BioPerl, or if the HapMap was built with BioPerl too. But the whole HapMap website runs on cgi-perl. </p><p> <b>Back story</b> -- from 2003 launch of HapMap: <a href="http://www.eurekalert.org/pub_releases/2003-12/nhgr-ihc121603.php">1</a>; <a href="http://www.eurekalert.org/pub_releases/2003-12/jhmi-sp121803.php">2</a></p> n1vux 2005-10-27T16:13:40+00:00 journal Only wimps read the release notes first ... Memoes to Self http://use.perl.org/~n1vux/journal/27290?from=rss <b>Memoes to self</b>: <p> <b>1. Always read the release notes carefuly before <i>and during</i> and upgrade.</b> </p><p>Luckily there wasn't anything important on the server that I tried to update from Debian 3.0/Woody to 3.1/Sarge withough following the recommended procedure in the platform-specific release note. For the <b>DEC-Alpha platform</b>, it's a just a wee bit more involved than the Ubuntu "just do it". (On DEC-Alpha, everything is a wee bit more complicated<nobr> <wbr></nobr>... except Perl is 64bit out of the box, hence my fascination with it.) I tried to just do it and hosed the Alpha<nobr> <wbr></nobr>... but since it was a standby system with nothing on it, which is why I was upgrading it first, no harm done expect I had to re-install 3.0 to try the upgrade again. </p><p>Upgrading Ubuntu 5.04 Hoary Hedgehog to 5.10 Breezy Badger was pretty slick. Not even in comparison, just slick. </p><p>2. <b>If on a ADSL "broadband" not real broadband, doing one upgrade-over-internet is quite enough, don't try to do two different ones at the same time.</b> </p><p>3. <b>Math helps with KVM Switches</b> </p><p>Knowing modular arithmetic makes using a KVM switch easier<nobr> <wbr></nobr>... -1 mod 4 = 3, so to go BACK 1 step on the KVM, advance 3 to wrap around back<nobr> <wbr></nobr>... sort of like two wrongs don't make a right, but three lefts do.</p> n1vux 2005-10-24T02:19:32+00:00 linux Science News omnibus http://use.perl.org/~n1vux/journal/26383?from=rss <p> &#171;<a href="http://www.aip.org/pnu/2005/split/742-1.html"> <strong>Room-temperature ice is possible</strong> </a> if the water molecules you&#8217;re freezing are submitted to a high enough electric field. &#187; -- Physics News Update</p><dl> <dt> <a href="http://www.eurekalert.org/pub_releases/2005-08/epfd-ltt081905.php"> <strong>Light that travels&#8230; faster than light!</strong> </a></dt> <dd>&#171;A team of researchers from the Ecole Polytechnique F&#233;d&#233;rale de Lausanne (EPFL) has successfully demonstrated, for the first time, that it is possible to control the speed of light &#8211; both slowing it down and speeding it up &#8211; in an optical fiber, using off-the-shelf instrumentation in normal environmental conditions.<nobr> <wbr></nobr>... They were also able to create extreme conditions in which the light signal travelled faster than 300 million meters a second. And even though this seems to violate all sorts of cherished physical assumptions, Einstein needn't move over &#8211; relativity isn't called into question, because <strong>only a portion of the signal is affected.</strong> &#187; [<em>emphasis supplied</em> ]</dd> <dd> <p>-&nbsp;<em>The <a href="http://scienceworld.wolfram.com/physics/Superluminal.html">Brillouin</a> phenomena apparently involve group velocity, not actual FTL propagation of waves, just of group crests? One of the 3 Google News hits for this story says it's embargoed until Monday 2AM, but two others are out with it, and it's on the university website;... apparently the press release also travelled faster than the speed of light?&nbsp;</em>&nbsp; </p><p>- <cite> <a href="http://www.epfl.ch/">Ecole Polytechnique F&#233;d&#233;rale de Lausanne</a> (<a href="http://actualites.epfl.ch/index.php?module=Presseinfo&amp;func=view_com&amp;id=286"> <b>Fran&#231;ais</b> </a>; <a href="http://actualites.epfl.ch/index.php?module=Presseinfo&amp;func=view_com&amp;id=287">Deutsch Presskommunique</a>; <a href="http://actualites.epfl.ch/index.php?module=Presseinfo&amp;func=view_com&amp;id=288">English press release </a>) &amp; Applied Physics Letters via <a href="http://www.eurekalert.org/pubnews.php">EurekAlert</a> <br> Their <a href="http://www.opticsexpress.org/abstract.cfm?URI=OPEX-13-1-82">previous</a> <a href="http://www.opticsinfobase.org/abstract.cfm?id=84595">work</a>. </cite> </p></dd> <dt> <a href="http://www.princeton.edu/main/news/archive/S12/43/81A28/index.xml?section=newsreleases"> <b>New method for trapping light may improve communications technologies</b> </a></dt> <dd>&#171; A discovery by Princeton researchers may lead to an efficient method for controlling the transmission of light and improve new generations of communications technologies powered by light rather than electricity.&nbsp;[...] [<em>They</em>] tested whether quasicrystals -- an unusual form of solid -- would be useful for controlling the path of light by constructing a three-dimensional, softball-sized model of such a structure with 4,000 [<em>count of one</em> ] centimeter-long polymer rods.&nbsp; [...] A quasicrystal is an unusual form of solid composed of two building blocks, or groups of atoms, that repeat regularly throughout the structure with two different spacings. [...] They observed how microwaves were blocked at certain angles in order to gauge how well the structure would control light passing through it. Building the physical model was a breakthrough that proved more valuable than using complex mathematical calculations, which had been a hurdle in previous efforts to evaluate the effectiveness of photonic quasicrystals in blocking light.&#187;&nbsp; (<em>PR; photo on PU site.</em> )</dd> <dd>&#171; [O]ur quasicrystal is far from optimized because it consists solely of thin rods connecting lattice points. A [...] more equal filled/void ratio would reduce polarization effects and enhance the gap overlap while maintaining the nearly spherical Brillouin zone. Laser tweezers used for particle trapping or two-photon polymerization would allow the construction of a quasicrystalline matrix of dielectric components with a photonic bandgap in the visible spectrum.&#187; [<em>Conclusion of preprint</em>]</dd> <dd> <p> <em>- Initially this sounds deceptively similar to the above Swiss fiber-optic experiment, and both involve </em> <a href="http://scienceworld.wolfram.com/physics/BrillouinScattering.html"> <em>Brillouin Scattering</em> </a> <em> phenomena, but this actually quite different.&nbsp;<br>(1) </em> <a href="http://en.wikipedia.org/wiki/Quasicrystal"> <em>Quasicrystals</em> </a> <em> (</em> <a href="http://scienceworld.wolfram.com/physics/Quasicrystal.html"> <em>*</em> </a> <em>) are 3-dimensional analogs of the </em> <a href="http://en.wikipedia.org/wiki/Penrose_tiling"> <em>Penrose tiling</em> </a> <em>&nbsp;(</em> <a href="http://mathworld.wolfram.com/PenroseTiles.html"> <em>*</em> </a> <em>), both of which seemingly violate the </em> <a href="http://mathworld.wolfram.com/CrystallographyRestriction.html"> <em>impossibility of 5-fold rotational symmetry</em> </a> <em> --&nbsp;counter-intuitively, 5-fold symmetry of a sort is possible in an&nbsp;</em> <a href="http://mathworld.wolfram.com/Tiling.html"> <em>aperiodic tiling</em> </a> <em>. (Thus providing&nbsp;a simpler counter-example to </em> <a href="http://mathworld.wolfram.com/WangsConjecture.html"> <em>Wang's conjecture</em> </a> <em>, which held all tilings could be periodic.) &nbsp;<br>(2) This is a scaled experiment performed with macroscopic stereolithographic model(s) inspected&nbsp;with microwaves and RF network analyzers, instead of an actual light experiment in light media as with the Swiss study above. <br>(3) This study is identifying candidates for <a href="http://www.nanoword.net/library/def/Photonic_Band_Gap.htm">photonic band-gap</a> <a href="http://en.wikipedia.org/wiki/Nanomaterials">nanomaterials</a>, and thus is similar to the <a href="http://scienceworld.wolfram.com/physics/IndexofRefraction.html">negative index of refraction materials</a>.&nbsp;</em> </p><p>- <cite> <a href="http://www.princeton.edu/">Princeton University</a> <a href="http://www.princeton.edu/main/news/archive/S12/43/81A28/index.xml?section=newsreleases">PR</a> and <a href="http://wwwphy.princeton.edu/~steinh/quasiphoton/">Website</a> <a href="http://www.princeton.edu/~wman/research.htm">with preprint</a>&nbsp;from <strong> <a href="http://www.nature.com/">Nature</a> </strong>436 p993ff, &nbsp;18 August 2005, Letters; via <a href="http://www.eurekalert.org/pubnews.php">EurekAlert</a> </cite> </p></dd> <dt> <a href="http://www.esa.int/esaSC/SEMSF0908BE_index_0.html"> <b>Saturn's rings have own atmosphere</b> </a></dt> <dd>&#171; Data from the NASA/ESA/ASI Cassini spacecraft indicate that Saturn's majestic ring system has its own atmosphere - separate from that of the planet itself. During its close fly-bys of the ring system, instruments on Cassini have been able to determine that the environment around the rings is like an atmosphere, composed principally of molecular oxygen. This atmosphere is very similar to that of Jupiter's moons Europa and Ganymede.&#187; <p>-&nbsp;<em>This again reminds me of </em> <a href="http://www.larryniven.org/biography.htm"> <em>Larry Niven</em> </a> <em>'s novels </em> <a href="http://isbn.nu/078610967X"> <em>The Integral Trees</em> </a> <em> and </em> <a href="http://isbn.nu/0786110120"> <em>The Smoke Ring</em> </a> <em> novels, set in a </em> <a href="http://kosmoi.com/Science/Physics/Mechanics/tpecp3.html#m8"> <em>physically plausible torus of atmosphere around a double star</em> </a> <em>&nbsp;(the physics are </em> <a href="http://www.vectorsite.net/tpecp_05.html#m4"> <em>quite similar to those for space-tethers in use on modern satellites</em> </a> <em>)&nbsp;.&nbsp; <br>&nbsp; Note that phrase <strong>similar to Europa's</strong> -- whose atmospheric pressure&nbsp;is estimated at one-hundred-billionth of Earth's (<a href="http://www.solarviews.com/portug/europapr.htm">*</a>) and thus not breathable; what little there is would also be rather cold. </em> </p><p>- <cite> <a href="http://www.esa.int/">European Space Agency</a>, Src, via <a href="http://www.eurekalert.org/pubnews.php">EurekAlert</a>&nbsp;(and also&nbsp;<a href="http://www.spaceref.com/news/viewpr.html?pid=17653">SpaceRef</a>, <a href="http://www.sciscoop.com/story/2005/8/18/105255/307">SciScoop</a>,<nobr> <wbr></nobr>...) </cite> </p></dd> <dt> <a href="http://www.eurekalert.org/pub_releases/2005-08/uow-gsr081605.php"> <b>Galactic survey reveals a new look for the Milky Way</b> </a></dt> <dd>&#171;With the help of NASA's Spitzer Space Telescope, astronomers have conducted the most comprehensive structural analysis of our galaxy and have found tantalizing new evidence that the Milky Way is much different from your ordinary spiral galaxy. &#187; <p>-&nbsp;<em>Ordinary? Ordinary may be the wrong word for un-barred in this case.&nbsp;The <strong>typical </strong> spiral galaxy <strong>is</strong> barred. The non-barred spirals are <strong>less</strong> <strong>typical</strong>, possibly <strong>older</strong>.&nbsp; E.g.,<br>&nbsp;</em>&nbsp;&#171;Barred spiral galaxies are relatively common, with surveys showing that up to two-thirds of all spiral galaxies contain a bar.&#187;&nbsp;&nbsp;&nbsp;&nbsp;- <a href="http://en.wikipedia.org/wiki/Barred_spiral_galaxy">Wikipedia</a> </p><p>- <cite> <a href="http://www.wisc.edu/">University of Wisconsin-Madison</a>, Src, via <a href="http://www.eurekalert.org/pubnews.php">EurekAlert</a> </cite> </p></dd> <dt> <a href="http://www.primidi.com/2005/08/14.html"> <strong>Too Many Roads Lead to Traffic Congestion</strong> </a></dt> <dd>&#171; In all networks, like road or airline traffic networks, the Internet, cancer tumors or industry supply chains, you need to pass packets from node to node, such as cars, information or data. But which are the most efficient, decentralized networks or hub-like centralized ones? According to <em> <a href="http://www.trnmag.com/Stories/2005/072705/Traffic_model_maps_congestion_072705.html">Technology Research News</a> </em> (TRN), researchers from Oxford University, U.K., have designed <a href="http://www.trnmag.com/Stories/2005/072705/Traffic_model_maps_congestion_072705.html"> <strong>a model which maps traffic congestion</strong> </a>. This model combines roads going through the center of a city and other ones avoiding it. And they found that, from a cost point of view, it would be sometimes better to close roads going through cities than adding more. They also think that these conclusions can be applied to almost all kinds of networks, biological ones or created by humans. &#187; [RP]<p>&#171;Researchers from Oxford University in England have tackled the problem [of network optimization] by examining the congestion costs within a network model that combines paths that go around the perimeter of the network and central hubs that provide shorter paths through the network. Real-world networks are too complicated to describe exactly mathematically. The researchers' model is simple enough to solve exactly, yet realistic enough to provide insights into real networks. <br>The research is aimed at finding ways to ease bottlenecks in networks involving manufacturing, the Internet and traffic, and ways to disrupt networks like tumor blood flow and terrorist supply chains. The findings could also help design better networks. &#187; [OU] </p><p>-&nbsp; <i>That <strong>adding</strong> a road may <strong>increase</strong> congestion is <strong>not</strong> a new result: traffic modellers were aware of this in 1980 if not before.</i>&nbsp; </p><p>- <cite>Oxford University, via <a href="http://www.trnmag.com/Stories/2005/072705/Traffic_model_maps_congestion_072705.html">Technology Research News</a>&nbsp; and <a href="http://www.primidi.com/2005/08/14.html">Roland Piquepaille's Technology Trends</a> </cite> </p></dd></dl> n1vux 2005-08-19T21:34:06+00:00 journal Science News http://use.perl.org/~n1vux/journal/25643?from=rss <dl> <dt> <a href="http://www.eurekalert.org/pub_releases/2005-07/bu-agp070805.php"> <strong>African grey parrot is first bird to comprehend numerical concept akin to zero</strong> </a> </dt> <dd>&#171;A Brandeis Univesity researcher has shown that an African grey parrot with a walnut-sized brain understands a zero-like concept -- an abstract notion that humans don't typically understand until age 3 or 4, and that can significantly challenge learning-disabled children.&#187; <p> -&nbsp;<em>This is harder than one might expect -- it took a long time for&nbsp;Zero to be accepted in Western mathematics. See, for instance, </em> <a href="/0823988694"> <em>The History of Zero: Exploring Our Place-Value Number&nbsp;System</em> </a> <em>, or </em> <a href="/0195142373"> <em>The Nothing That Is: A Natural History of Zero</em> </a>. </p><p>&nbsp;- <cite> <a href="http://www.brandeis.edu/">Brandeis University</a>&nbsp;&amp; the&nbsp;<a href="http://www.alexfoundation.org/research/">Alex Foundation</a> ; <a href="http://content.apa.org/journals/com">Journal of Comparative Psychology</a> ; <br> via <a href="http://www.eurekalert.org/pubnews.php">EurekAlert</a> and <a href="http://www.world-science.net/exclusives/exclusives-nfrm/050701_parrotzero.htm"> World Science News</a> and <a href="http://www.primidi.com/2005/07/09.html#a1242"> <strong>Primidi</strong> </a> ; <br> and also <a href="http://www.sciencedaily.com/releases/2005/07/050711013845.htm">Science Daily</a>, and <a href="http://news.google.com/news?ned=us&amp;ncl=http://www.physorg.com/news5049.html&amp;hl=en">Google News</a> </cite> </p></dd> <dt> <a href="http://www.world-science.net/exclusives/050526_colorfrm.htm"> <strong>Is my red your red?</strong> </a> </dt> <dd>&#171;Does society determine the way you see a rainbow? New findings are re-igniting an old controversy.&#187; <p> -&nbsp;<em>Nice comparitive 2d color map in the linked summary. This debate has been running for 35 years -- interestingly, Paul Kay is cited as the </em> <a href="http://plato.stanford.edu/entries/relativism/supplement2.html"> <em>original in color Relativism</em> </a> <em>, so could be significant that he's a co-author in the non-relativist paper, but his 1969 title was "Basic Color Terms: Their Universality and Evolution"</em> <em>, so maybe the relativists took him out of context?</em> </p><p> <a href="http://www.essex.ac.uk/psychology/psychology/CLIENTS/debiRoberson/debiRoberson.html">Debi&nbsp; Roberson</a> (University of Essex in Colchester, U.K), J. Davidoff, I.R. Davies, L.R. Shapiro, 2005. <br> <strong> <a href="http://www.sciencedirect.com/science?_ob=GatewayURL&amp;_method=citationSearch&amp;_urlVersion=4&amp;_origin=SDTOPTWOFIVE&amp;_version=1&amp;_piikey=S0010028504000763&amp;md5=af76d4b6ba0d7ad3b58a57c86c447f3b">Color categories: Evidence for the cultural relativity hypothesis</a> </strong>. <em>Cognitive Psychology</em>. 50, 378-411.<br>Terry Regier (U.Chicago), <a href="http://www.icsi.berkeley.edu/~kay/">Paul Kay</a> (ICSI), R.S. Cook, 2005. <br> <strong> <a href="http://www.pnas.org/cgi/content/full/102/23/8386">Focal colors are universal after all</a> </strong>. <em>Proceedings of the National Academy of Sciences</em>&nbsp;102, 8386-91.</p></dd> <dd> <p> ICSI's <a href="http://www.icsi.berkeley.edu/wcs/">World Color Survey</a>.</p></dd> <dt> <a href="http://www.aip.org//pnu/2005/split/736-2.html"> <strong>Why Is The Sky Blue, and Not Violet?</strong> </a> </dt> <dd>&#171;The hues that we see in the sky are not only determined by the laws of physics, but are also colored by the human visual system, shows a new paper in the American Journal of Physics. On a clear day when the sun is well above the horizon, the analysis demonstrates, we perceive the complex spectrum of colors in the sky as a mixture of white light and pure blue. When sunlight enters the earth's atmosphere, it scatters (ricochets) mainly from oxygen and nitrogen molecules that make up most of our air. What scatters the most is the light with the shortest wavelengths, towards the blue end of the spectrum, so more of that light will reach our eyes than other colors. But according to the 19th-century physics equations introduced by Lord Rayleigh, as well as actual measurements, our eyes get hit with peak amounts of energy in violet as well as blue. [...]<br> <br>The sky's complex multichromatic rainbow of colors tickles our eye's cones in the same way as does a specific mixture of pure blue and white light. This is similar to how the human visual system will perceive the right mixture of pure red and pure green as being equivalent to pure yellow. The cones that allow us to see color cannot identify the actual wavelengths that hit them, but if they are stimulated by the right combination of wavelengths, then it will appear the same to our eyes as a single pure color, or a mixture of a pure color and white light. &#187;</dd> <dd> <p>-&nbsp; <i>Interesting.</i> </p><p>- <cite>American Journal of Physics, July 2005, via <a href="http://www.aip.org/">AIP Physics News Update</a> </cite> </p></dd><dt> <a href="http://www.nasa.gov/vision/earth/environment/sealevel_feature.html"> <strong>Scientists get a real 'rise' out of breakthroughs in how we understand changes in sea level</strong> </a> </dt> <dd>&#171;For the first time, researchers have the tools and expertise to understand the rate at which sea level is changing and the mechanisms that drive that change.<nobr> <wbr></nobr>... <br>&#8220;We&#8217;ve found that the largest likely factor for sea level rise is changes in the amount of ice that covers Earth. Three-fourths of the planet&#8217;s freshwater is stored in glaciers and ice sheets, or about 220 feet of sea level."<nobr> <wbr></nobr>... <br>The latest sea level research conducted by Dr. Steve Nerem, Associate Professor, Colorado Center for Astrodynamics Research at the University of Colorado in Boulder, and his colleagues, published in a 2004 issue of Marine Geodesy Journal, has found that recent TOPEX/Poseidon and Jason satellite observations show an average increase in global mean sea level of three millimeters a year from 1993-2005. This rate is more than 50 percent greater than the average rate of the last 50 years.&nbsp;&#187; <p> - <i>Comment</i> </p><p> - <a href="http://www.nasa.gov/goddard">NASA/Goddard Space Flight Center--EOS Project Science Office</a>&nbsp;via <a href="http://www.eurekalert.org/pubnews.php">EurekAlert</a>&nbsp;&nbsp; </p></dd> <dt> <a href="http://www.nasa.gov/vision/earth/lookingatearth/trmm_3D.html"> <strong>NASA offers a real-time 3-D look at the inside of hurricanes</strong> </a></dt> <dd>&#171;Seeing how rain falls from top to bottom and how heavy the rain falls throughout parts of a tropical cyclone is very important to hurricane forecasters. NASA has sped up the process of getting this data within three hours, and making it appear in 3-D. The new process now gives information quickly enough for forecasters to use.&#187; <p> - <i>Tropical Rainfall Measuring Mission or TRMM provided some astonishing view of H.Bonnie last year. They're providing similar views in near-real-time to tropical forecasters now.</i> </p><p> - <cite> <a href="http://www.nasa.gov/goddard">NASA/Goddard Space Flight Center--EOS Project Science Office</a>&nbsp;( <a href="http://trmm.gsfc.nasa.gov/">http://trmm.gsfc.nasa.gov/</a> ) via <a href="http://www.eurekalert.org/pubnews.php">EurekAlert</a> </cite> </p></dd> <dt> <a href="http://www.eurekalert.org/pub_releases/2005-07/nrl-nsf070605.php"> <strong>NRL study finds shuttle exhaust is source of mysterious clouds in Antarctica</strong> </a> </dt> <dd>&#171;A new study, funded in part by the Naval Research Laboratory (NRL) and the National Aeronautics and Space Administration (NASA) reports that exhaust from the space shuttle can create high-altitude clouds over Antarctica mere days following launch, providing valuable insight to global transport processes in the lower thermosphere. The same study also finds that the shuttle's main engine exhaust plume carries small quantities of iron that can be observed from the ground, half a world away.&#187; <p> - <em> Days before the next Shuttle launch, they're still getting new science from the ill-fated Columbia.&nbsp; <br> </em>"Antarctic polar mesospheric clouds (PMCs)" <em>or Noctilucent clouds form over the&nbsp;antarctic only days later, showing pretty rapid transport in the&nbsp;thermosphere, and bloomed later in the year.</em> </p><p> - <cite>Naval Research Laboratory, NASA , Geophysical Research Letters,&nbsp; via <a href="http://www.eurekalert.org/pubnews.php">EurekAlert</a>&nbsp; </cite> </p></dd> <dt> <a href="http://sciencenow.sciencemag.org/cgi/content/full/2005/708/1"> <strong>Experts Explore Science's Unanswered Questions</strong> </a> </dt> <dd>&#171;Four AAAS symposia tackle overpopulation, string theory, the causes of disease, and what makes us human &#187; <p> - <i>Science Magazine has full discussion of 25 top questions and 100 more listed.</i> </p><p> -&nbsp; <cite> <a href="http://www.sciencemag.org/">AAAS Science magazine</a> <br> </cite> </p></dd> <dt> <a href="http://sciencenow.sciencemag.org/cgi/content/full/2005/708/2"> <strong>Simplifying a Nutty Problem</strong> </a> <strong> -- The Brazil-Nut Problem. </strong></dt> <dd>&#171; Swirling marbles may give clues to why larger nuts tend to float to the top of the can. &#187; <p>-&nbsp; <i>Includes do-it-yourself experiment link!</i>&nbsp; </p><p> - <cite> via <a href="http://www.sciencemag.org/">AAAS Science magazine</a>&nbsp; </cite> </p></dd> <dt> <a href="http://www.aip.org/pnu/2005/split/736-1.html"> <strong>A Coulomb Experiment for the Weak Nuclear Force</strong> </a> </dt> <dd>&#171;Physicists at the SLAC accelerator have measured, with much greater precision than ever before, the variation in the weak nuclear force, one of the four known physical forces, over an enormous size scale (a distance of more than ten proton diameters) for so feeble a force. Although the results were not surprising (the weak force diminished with distance as expected) this new quantitative study of the weak force helps to cement physicists&#8217; view of the sub-nuclear world.&nbsp;... The SLAC work is, in effect, a 21st century analog of the landmark 18th experiments in which the intrinsic strength of the electromagnetic and gravitational forces were measured (by Charles Coulomb and Henry Cavendish, respectively) through careful observation of test objects causing a torsion balance to swing around. The weak force, in the modern way of thinking, is a cousin of the electromagnetic (EM) force; both of them are considered as different aspects of a single &#8220;electroweak&#8221; force.&nbsp;&nbsp;&#187; <p> -&nbsp; <i>Reuse of a classic experimental&nbsp;design to measure a radically expression of a related force. This&nbsp;experiment indirectly measures the weak force by measuring a parity violation.</i>&nbsp; </p><p> - <cite> <a href="http://www-project.slac.stanford.edu/e158/">Slac</a>, via <a href="http://www.aip.org/">AIP Physics News Update</a> </cite> </p></dd> </dl> n1vux 2005-07-11T20:15:55+00:00 journal Science News http://use.perl.org/~n1vux/journal/25474?from=rss Good heavens, it's been a MONTH since I made a Science News entry. <p> <b>Two from Saturn </b> - <a href="http://news.bbc.co.uk/2/hi/science/nature/4640641.stm">http://news.bbc.co.uk/2/hi/science/nature/4640641.stm</a> - Rings have own atmosphere; and Saturn has gained 7 minutes per day in 20-30 years. (<i>I could use an extra 7 minutes per day.</i>) -- BBC </p><p> <b>Einstein ring in distant universe</b> <a href="http://www.eso.org/outreach/press-rel/pr-2005/phot-20-05.html">Einstein Ring</a> Using ESO's Very Large Telescope, R&#233;mi Cabanac and his European colleagues have discovered an amazing cosmic mirage, known to scientists as an Einstein Ring. This cosmic mirage, dubbed FOR J0332-3557, is seen towards the southern constellation Fornax (the Furnace), and is remarkable on at least two counts. First, it is a bright, almost complete Einstein ring. Second, it is the farthest ever found. - <a href="http://www.eso.org/">European Southern Observatory (ESO) </a>; Astronomy &amp; Astrophysics Letters </p><p> <b>Oregon study confirms health benefits of cobblestone walking for older adults</b> </p><p> <a href="http://www.sciencemag.org/cgi/content/abstract/1112399"> <b>Melting starts at defects in colloidial crystals. </b> </a> <br> <i>I might have guessed if I'd thought to ask the question, nice to have it confirmed. </i>. <br> Also at <a href="http://www.aip.org/pnu/2005/split/733-2.html">AIP PNU</a>; <i>Contrast with</i> <a href="http://www.physlink.com/News/Index.cfm?ID=254">Ultra-fast X-ray pulses reveal how a solid melts into a liquid</a> </p><p> <a href="http://www.sciencemag.org/cgi/rapidpdf/1109602v1"> <b>"Supernova Olivine from Cometary Dust"</b> </a> -- <i>Rocks for Astronomers</i> </p><p> <b>Network theory of getting lost in a strange city</b><nobr> <wbr></nobr>... <i>and why locals' directions make no sense</i>. <a href="http://www.primidi.com/2005/06/30.html#a1233">primidi</a></p> n1vux 2005-07-01T23:00:44+00:00 journal