1. Oak Ridge Institute for Science and Education, Atlanta, Georgia, USA;
2. Division of STD Prevention, National Center for HIV/AIDS, Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA;
3. Department of Applied Health Science, Indiana University Bloomington, Bloomington, Indiana, USA;
4. Department of Public Health, University of Texas at San Antonio, San Antonio, Texas, USA