1. Department of Health Behavior and Health Education, School of Public Health, University of North Carolina, CB# 7400 Rosenau Hall, Chapel Hill, NC 27599-7400; phone: (919) 966-7546; fax: (919) 966-2921;
2. Stanford Center for Research in Disease Prevention, Stanford University
3. Department of Health Behavior and Health Education in the School of Public Health at the University of North Carolina, Chapel Hill