1. From the Cardiovascular Research Laboratory and the Departments of Medicine (Cardiology; J.N.W., Z.Q., A.G.), and Physiological Science (A.G.), David Geffen School of Medicine at UCLA, and Cedars-Sinai Medical Center (P.-S.C., S.-F.L., H.S.K., H.H.), Los Angeles, Calif, and the Department of Physics (A.K.), Northeastern University, Boston, Mass.