1. a Global Health Sciences , University of California , San Francisco , CA , USA
2. b Division of Global Public Health , University of California , San Diego , CA , USA
3. c Helen Diller Family Comprehensive Cancer Center and Department of Anthropology, History, and Social Medicine , University of California , San Francisco , CA , USA
4. d Department of Population Studies , El Colegio de la Frontera Norte , Tijuana , Mexico