1. From the Department of Mathematics (R.R.), Loyola Marymount University, Los Angeles, Calif; Department of Physics (X.C.), Beijing Normal University, People’s Republic of China; and Departments of Physiological Science (X.C., A.G.), Medicine (Cardiology) (A.G., J.N.W., Z.Q.), and Physiology (J.N.W.), David Geffen School of Medicine, University of California, Los Angeles.