16x9_vortex reversal image 011322x (IMAGE) DOE/Argonne National Laboratory Caption Experimental snapshot of a Quincke roller suspension during a vortex reversal induced by a temporal modulation of the activity. Groups of particles with identical color represent flocks moving in the same direction. Credit (Image by Bo Zhang, Alexey Snezhko/Argonne National Laboratory.) Usage Restrictions Original content 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.