1. Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA.
2. Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA.
3. Department of Mathematics, Sam Houston State University, Huntsville, TX 77340, USA.
4. Mansueto Institute for Urban Innovation and Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA.