1. Office of International Research and Development, Snell Hall 400, Oregon State University, Corvallis, OR 97331-1641, USA
2. Department of Public Health, 309 Waldo Hall, Oregon State University, Corvallis, OR 97331-6406, USAPhone 541-737-3830, Fax: 541-737-4001, E-mail: anna.harding@oregonstate.edu