Tweet Density (image) University of Southern California Share Print E-Mail Caption This heat map shows the density of all tweets during the study collection period where the location was identifiable through ambient information or direct sharing. Credit Image courtesy of Chris Weidemann. Usage Restrictions For media use only, with credit. Share Print E-Mail 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.