1. Lazer Laboratory, Northeastern University, Boston, MA 02115, USA.
2. Harvard Kennedy School, Harvard University, Cambridge, MA 02138, USA.
3. Institute for Quantitative Social Science, Harvard University, Cambridge, MA 02138, USA.
4. University of Houston, Houston, TX 77204, USA.
5. Laboratory for the Modeling of Biological and Sociotechnical Systems, Northeastern University, Boston, MA 02115, USA.
6. Institute for Scientific Interchange Foundation, Turin, Italy.