1. Harborview Injury Prevention and Research Center, University of Washington, Seattle, Washington.
2. Harbor-University of California; Los Angeles BioMedical Research Institute, Los Angeles, California.
3. Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois.
4. Ohio State University College of Medicine, Columbus, Ohio.
5. University of Pittsburgh, Pittsburgh, Pennsylvania.
6. Mattel Children's Hospital, University of California, Los Angeles, Los Angeles, California.