The Proceedings of the National Academy of Sciences of the United States of America, usually referred to as PNAS,'s the official journal of the United States National Academy of Sciences. PNAS's an important scientific journal that printed its first issue in 1915 and continues to publish highly cited research reports, commentaries, reviews, perspectives, feature articles, profiles, letters to the editor, and actions of the Academy. Coverage in PNAS broadly spans the biological, physical, and so… (More on Pnas)