1. From the Neonatal Perinatal Research Institute, Division of Neonatology, Duke University Medical Center (T.M.Y., M.L.K.), and the Department of Biomedical Engineering, Duke University (M.A.C., J.A.I.), Durham, NC; Optics and Fluid Dynamics Department, Risoe National Laboratory, Roskilde, Denmark (L.T.); and Department of Pediatric Cardiology, University Children’s Hospital, Münster, Germany (T.M.Y.).