机构:
Univ Utah, Sch Med, Dept Family & Prevent Med, Div Publ Hlth, Salt Lake City, UT 84112 USAEunice Kennedy Shriver Natl Inst Child Hlth & Hum, Epidemiol Branch, Div Intramural Populat Hlth Res, NIH, 6710B Rockledge Dr MSC 7004, Bethesda, MD 20892 USA