1. School of Public Health, Capital Medical University, Beijing, China
2. Department of Environmental Health, Boston University School of Public Health, Boston, Massachusetts
3. Department of Social Medicine and Health Education, School of Public Health, Peking University, Beijing, China
4. Department of Epidemiology and Biostatistics, School of Public Health, University of Georgia, Athens
5. The Dr. Lynn Cook Hartwig Public Health Program, The University of Southern Mississippi, Hattiesburg
6. Department of Public Health and Community Medicine, Tufts University School of Medicine, Boston, Massachusetts