1. From Pulmonary Diseases (A.V.N., J.H.B.) and Physics and Medical Technology (A.V.N.), Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands; Division of Cardiovascular Medicine, Department of Medicine and Stanford Cardiovascular Institute, Stanford University, Palo Alto, CA (F.H.); and Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University, Baltimore, MD (P.M.H.).