The discipline information given by PNAS.

Abstract

<p>The panels (a,b) respectively come from <a href="http://www.pnas.org/content/110/18.toc" target="_blank">http://www.pnas.org/content/110/18.toc</a>, <a href="http://www.pnas.org/content/110/18.toc#PhysicalSciences" target="_blank">http://www.pnas.org/content/110/18.toc#PhysicalSciences</a>.</p