1 Department of Civil and Systems Engineering and Center for Systems Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA. Electronic address: l.gardner@jhu.edu.
2 Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA; Nuffield Department of Medicine, University of Oxford, Oxford, UK.
3 Department of Civil and Systems Engineering and Center for Systems Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
4 Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA.