1. Department of Epidemiology and Biostatistics, Robert Stempel College of Public Health and Social Work, Florida International University, Miami, Florida.
2. Centers for Behavioral & Preventive Medicine, The Miriam Hospital, Providence, Rhode Island.
3. The Miriam Hospital, Providence, Rhode Island.
4. Laboratory of Infectious Disease Prevention, New York Blood Center, New York, New York.
5. New York Blood Center/Project Achieve, Bronx, New York.
6. Statistical Center for HIV/AIDS Research & Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington.
7. HIV Prevention Research Division, Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania.