[1] Duke Univ, Durham, NC 27706 USA
[2] Univ Alabama, Tuscaloosa, AL 35487 USA
[3] Kaiser Permanente San Diego, San Diego, CA USA
[4] Univ New Mexico, Albuquerque, NM 87131 USA
[5] Univ Penn, Philadelphia, PA 19104 USA
[6] Oregon Hlth & Sci Univ, Portland, OR USA
[7] Brown Univ, Providence, RI 02912 USA
[8] Univ Pittsburgh, Pittsburgh, PA 15260 USA
[9] Cleveland Clin, Cleveland, OH 44106 USA
[10] RTI Int, Res Triangle Pk, NC USA
[11] NICHD, Bethesda, MD USA