1. Department of Epidemiology, University of North Carolina, Chapel Hill, NC
2. Department of Medicine, University of Mississippi Medical Center, Jackson, MS
3. Department of Biostatistics, University of North Carolina, Chapel Hill, NC
4. Department of Medicine, University of North Carolina, Chapel Hill, NC
5. Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, MS MN
6. Department of Epidemiology, Johns Hopkins University, Baltimore, MD