Photo of Researchers (IMAGE) Karolinska Institutet Caption From left: Virginia Stone and Malin Flodström Tullberg, researchers at Karolinska Institutet in Sweden and co-authors of the study. Credit Stefan Zimmerman Usage Restrictions None 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.