Open Access (IMAGE) IOP Publishing Caption Open access allows materials to be distributed online, free of cost or other access barriers. Credit Open access logo designed by the Public Library of Science Usage Restrictions As per the rules set out by the Public Library of Science License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.