1. Department of Epidemiology, George Washington University, Washington D.C., USA
2. Department of Medicine, George Washington University, Washington D.C., USA
3. HIV/AIDS, Hepatitis, STD and TB Administration, District of Columbia Department of Health, Washington D.C., USA
4. Department of Psychological and Brain Sciences, George Washington University, Washington D.C
5. Department of Sociology, American University, Washington, D.C., USA