1. Division of Epidemiology, College of Public Health, The Ohio State University , 1841 Neil Ave., Columbus, OH 43210, USA
2. Department of Internal Medicine, Wexner Medical Center, Center for Tobacco Research, The Ohio State University Comprehensive Cancer Center , 3650 Olentangy River Road, Suite 410/420, Columbus, OH 43214, USA
3. Duke University School of Nursing , 307 Trent Dr., Durham, NC 27710, USA