1. Carolina Center for Interdisciplinary Applied Mathematics, Department of Mathematics, University of North Carolina, Chapel Hill, NC 27599, USA.
2. Institute for Advanced Materials, Nanoscience and Technology, University of North Carolina, Chapel Hill, NC 27599, USA.
3. Operations Research, North Carolina State University, Raleigh, NC 27695, USA.
4. Oxford Centre for Industrial and Applied Mathematics, Mathematical Institute, University of Oxford, Oxford OX1 3LB, UK.
5. CABDyN Complexity Centre, University of Oxford, Oxford OX1 1HP, UK.
6. Department of Health Care Policy, Harvard Medical School, Boston, MA 02115, USA.
7. Harvard Kennedy School, Harvard University, Cambridge, MA 02138, USA.