1. OHSU-PSU School of Public Health , Portland, Oregon , USA
2. Department of Epidemiology, Columbia Mailman School of Public Health , New York, New York , USA
3. Department of Epidemiology, University of Washington School of Public Health , Seattle, Washington , USA
4. Department of Kinesiology and Nutrition, University of Illinois Chicago , Chicago, Illinois , USA
5. Department of Environmental and Occupational Health Sciences, University of Washington School of Public Health , Seattle, Washington , USA
6. Department of Sociology, University of British Columbia , Vancouver, British Columbia , Canada