1. Department of Epidemiology and Biostatistics; College of Public Health, University of South Florida; Tampa FL 33612 USA
2. Department of Biostatistical Sciences; Wake Forest School of Medicine; Winston-Salem NC 27157 USA
3. Barbara Davis Center; University of Colorado Denver; Aurora CO 80045 USA
4. Department of Pediatrics; Cincinnati Children's Hospital Medical Center; Cincinnati OH 45229 USA
5. Department of Pediatrics; University of Colorado School of Medicine; Aurora CO 80045 USA
6. Department of Epidemiology; Colorado School of Public Health, University of Colorado Denver; Aurora CO 80045 USA
7. Department of Metabolism, Endocrinology and Nutrition; University of Washington; Seattle WA 98105 USA
8. Department of Nutrition; UNC Gillings School of Public Health, University of North Carolina; Raleigh NC 27599 USA