[1] NHLBI, Cardiovasc & Pulm Branch, Div Intramural Res, NIH, Bldg 10, Bethesda, MD 20892 USA
[2] Johns Hopkins Univ, GOPC, Baltimore, MD 21218 USA
[3] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Hlth Policy & Management, Baltimore, MD USA
[4] NIH, Undergrad Scholarship Program, Off Intramural Training & Educ, Off Director, Bldg 10, Bethesda, MD 20892 USA
[5] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Int Hlth, Baltimore, MD 21205 USA
[6] Carnegie Mellon Univ, PSC, Pittsburgh, PA 15213 USA