Information for April 7.

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<!--
<li><a href="Apr07.ppt">presentation of April 7 (powerpoint)</a>
<li><a href="Apr07.pdf">presentation of April 7 (PDF)</a>
-->

<li><a href="http://www.pnas.org/cgi/content/full/98/20/11462">"http://www.pnas.org/cgi/content/full/98/20/11462" pointer to paper being presented on April 7.</a>

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