Proceedings of the National Academy of Sciences of the United States of America

PNAS publishes research reports, Brief Reports, Letters, Front Matter magazine content, Commentaries, Perspectives, and Colloquium Papers. In accordance with the guiding principles established by George Ellery Hale in 1914, PNAS also publishes brief first announcements of NAS members’ and foreign associates’ more important contributions to research and of work that appears to a member to be of particular importance. All submissions are evaluated by a member of the Editorial Board prior to acceptance. PNAS is a general science journal, and all papers should be intelligible to a broad scientific audience.