1Department of Computer Science, University of Colorado, Boulder, CO 80309, USA
2BioFrontiers Institute, University of Colorado, Boulder, CO 80303, USA
3Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
4Ewing Marion Kauffman Foundation, Kansas City, MO 64110, USA
5Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA
6Center for Communicable Disease Dynamics, Harvard School of Public Health, Boston, MA 02115, USA.