1. aDepartment of Geography, University of North Carolina-Chapel Hill, Campus Box 3220, 308 Saunders Hall, Chapel Hill, NC, 27599-3220, United States of America (USA).
2. bDepartment of Sociology, University of North Carolina-Chapel Hill, Chapel Hill, USA.
3. cDemographic and Health Surveillance Unit, International Centre for Diarrhoeal Disease Research-Bangladesh, Dhaka, Bangladesh.
4. dLamont–Doherty Earth Observatory of Columbia University, Palisades, USA.