1. AIDS Program, Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
2. Department of Economics, University of New Mexico, Albuquerque, New Mexico, USA
3. Center for Alcoholism Substance Abuse and Addiction, University of New Mexico, Albuquerque, New Mexico, USA
4. Center for Interdisciplinary Research on AIDS, Yale University School of Public Health, New Haven, Connecticut, USA