1. Department of Behavioral Sciences & Health Education, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
2. Annenberg Public Policy Center, University of Pennsylvania, Philadelphia, PA 19104, USA
3. Center for Health and Behavior, Syracuse University, Syracuse, NY 13244-5040, USA
4. Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA
5. Department of Psychiatry, Rhode Island Hospital, Brown University, Providence, RI 02912, USA
6. Department of Pediatrics, Wayne State University, Detroit, MI 48201-2196, USA