Skype Social Network (IMAGE) Aalto University Caption Snowball sample of the Skype social network (gray links), showing multiple innovators as green nodes, induced small vulnerable trees as red nodes and links, and the triggered connected stable cluster as blue nodes and links. Credit Nature Publishing Group 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.