1. Department of Medicine, Duke University School of Medicine, Durham, North Carolina
2. Center for the Study of Aging and Human Development, Durham, North Carolina
3. Center for Population Health Science, Duke University School of Medicine, Durham, North Carolina
4. Social Science Research Institute, Duke University, Durham, North Carolina
5. Duke Molecular Physiology Institute, Duke University, Durham, North Carolina
6. Department of Biostatistics, Duke University, Durham, North Carolina
7. Department of Biobehavioral Health, Pennsylvania State University, State College