[1] Duke University Medical Center,Department of Community and Family Medicine
[2] University of North Carolina at Chapel Hill,Center for Health Promotion and Disease Prevention
[3] University of North Carolina at Chapel Hill,Department of Nutrition, Gillings School of Global Public Health
[4] Johns Hopkins University,Department of Health, Behvaior and Society, Johns Hopkins Bloomberg School of Public Health
[5] Duke University Medical Center,Duke Office of Clinical Research