1. Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA
2. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA
3. Department of Civil and Systems Engineering, Johns Hopkins Whiting School of Engineering, 3400 N. Charles Street, Baltimore, MD 21218, USA