1 Department of Applied Mathematics and Theoretical Physics (D.D., M.R., C.B.S.) and Division of Cardiovascular Medicine (J.H.F.R.), University of Cambridge, Cambridge, England; Department of Radiology, School of Clinical Medicine, University of Cambridge and CRUK Cambridge Centre, Cambridge Biomedical Campus, Cambridge CB2 0QQ, England (I.S., J.B., E.S.); Oncology R&D, AstraZeneca, Cambridge, England (M.R.); Department of Infectious Diseases, University of Cambridge Hospitals, Cambridge, England (E.G.K.); and National Heart and Lung Institute, Imperial College London, London, England (G.Y.).