PNAS . ORG {}

ARTICLES Current IssueLatest ArticlesSpecial FeaturesList of IssuesPNAS Nexus Front Matter AUTHORS Information for AuthorsEditorial and Journal PoliciesSubmission ProceduresPublication Charges Topics Physical Sciences Social Sciences Biological Sciences Featured Topics Physics Chemistry Sustainability Science Sustainable Development Goals Articles By Topic Applied Mathematics Applied Physical Sciences Astronomy Biophysics and Computational Biology Computer Sciences Earth, Atmospheric, and Planetary Sciences Engineering Environmental Sciences Mathematics Statistics Featured Topics Anthropology Sustainability Science Sustainable Development Goals Articles By Topic Demography Economic Sciences Environmental Sciences Political Sciences Psychological and Cognitive Sciences Social Sciences Featured Topic Anthropology Sustainability Science Sustainable Development Goals Articles By Topic Agricultural Sciences Applied Biological Sciences Biochemistry Biophysics and Computational Biology Cell Biology Developmental Biology Ecology Environmental Sciences Evolution Genetics Immunology and Inflammation Medical Sciences Microbiology Neuroscience Pharmacology Physiology Plant Biology Population Biology Psychological and Cognitive Sciences Systems Biology 0 Cart Sign in Register Individual Login Institutional Login Submit Quick Search anywhere Enter journal, DOI, article type, keywords, authors, etc. Quick search in Citations Journal* Journal* PNAS Nexus Proceedings of the National Academy of Sciences Year Volume* Issue* Page/eLocation ID* *Required field Quick Search in Journals Enter journal, DOI, article type, keywords, authors, etc. Quick Search in Journals Enter journal, DOI, article type, keywords, authors, etc. Searching: Anywhere AnywhereCitationPNAS NexusProceedings of the National Academy of Sciences Advanced Search Search SUGGESTED SEARCHES: Covid-19 Artificial Intelligence Mpox Climate Change Gun Violence Sign in Register Individual Login Institutional Login Quick Search anywhere Enter journal, DOI, article type, keywords, authors, etc. ARTICLES Current Issue Latest Articles Special Features List of Issues PNAS Nexus Front Matter AUTHORS Information for Authors Editorial and Journal Policies Submission Procedures Publication Charges Topics Contact Site Map Terms & Privacy Policy Accessibility back Physical Sciences Featured Topics Physics Chemistry Sustainability Science Sustainable Development Goals Articles By Topic Applied Mathematics Applied Physical Sciences Astronomy Biophysics and Computational Biology Computer Sciences Earth, Atmospheric, and Planetary Sciences Engineering Environmental Sciences Mathematics Statistics back Social Sciences Featured Topics Anthropology Sustainability Science Sustainable Development Goals Articles By Topic Demography Economic Sciences Environmental Sciences Political Sciences Psychological and Cognitive Sciences Social Sciences back Biological Sciences Featured Topic Anthropology Sustainability Science Sustainable Development Goals Articles By Topic Agricultural Sciences Applied Biological Sciences Biochemistry Biophysics and Computational Biology Cell Biology Developmental Biology Ecology Environmental Sciences Evolution Genetics Immunology and Inflammation Medical Sciences Microbiology Neuroscience Pharmacology Physiology Plant Biology Population Biology Psychological and Cognitive Sciences Systems Biology back Topics Physical Sciences Social Sciences Biological Sciences 102 No Nobelium 259 404 Page Not Found The requested page is unavailable due to a broken or nonexistent link. Please use the search bar to find what you are looking for. Quick Search anywhere Search Search 91 Pa Protactinium 231.04 32 Ge Germanium 72.630 9 F Fluorine 18.998 8 O Oxygen 15.999 92 U Uranium 238.03 60 Nd Neodymium 144.24 Sign up for thePNAS Highlights newsletter Get in-depth science stories sent to your inbox twice a month. Subscribe Browse Current Issue PNAS Nexus Special Features List of Issues Collected Papers PNAS In The News Front Matter Journal Club Multimedia Podcasts Information About Sustainable Development Goals Editorial Board Authors Reviewers Subscribers Librarians Press Cozzarelli Prize PNAS Updates Back to top Copyright © 2025 National Academy of Sciences. All rights reserved. | Online ISSN 1091-6490 PNAS is a partner of CHORUS, CLOCKSS, COPE, CrossRef, ORCID, and Research4Life. Contact Site Map Terms & Privacy Policy Accessibility Request Username x Close Can't sign in? Forgot your username? Enter your email address below and we will send you your username Email Submit If the address matches an existing account you will receive an email with instructions to retrieve your username Create a new account x Close Email Returning user Submit Login x Close Email* Password* Forgot your password? Reset it here Keep me logged in Login Don’t have an account? Register here Institutional Login Change Password x Close Enter the verification code Submit Congrats! Your Phone has been verified