Image 3 (IMAGE) The University of Hong Kong Caption Professor Yu Yizhou Credit The University of Hong Kong Usage Restrictions This work is licensed for non-commercial, non-exclusive, one-time usage with attribution to the copyright holder. License Original 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.