div class=trans-pagebuttonPage 1button div class=trans-image amp-img class=trans-thumb alt=Page 1: February27 2007 vol 104 no9 pp 3017-3668 Proceedings limiteduAPapers07pnas_104_09_coverpdf · February27 2007 vol 104 no9 pp 3017-3668 Proceedings of the National src=https:reader036fdocumentsinreader036viewer20220708025f02da497e708231d40654ffhtml5thumbnails1jpg width=142 height=106 layout=responsive amp-img divdiv