Gerardo Chowell1, Patrick Sullivan2, Richard Rothenberg3. 1. School of Public Health, Georgia State University, Atlanta; Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, MD. Electronic address: gchowell@gsu.edu. 2. Rollins School of Public Health, Emory University, Atlanta, GA. 3. School of Public Health, Georgia State University, Atlanta.