1. Department of Health, Behavior & Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
2. Center for Child and Community Health Research, Department of Pediatrics, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
3. DC Center for AIDS Research, Department of Psychology, George Washington University, Washington, DC, USA
4. Cabell-Huntington Health Department, Huntington, West Virginia, USA
5. National Center for Injury Prevention and Control, Centers for Disease Control and Prevention, Atlanta, Georgia, USA