1. Department of Biomedical Engineering, University of Iowa;
2. Department of Neurosurgery, University of Iowa Hospitals and Clinics; and
3. Department of Surgery, Division of Neurosurgery, Beth Israel Deaconess Medical Center; and
4. Department of Neurosurgery, Jefferson University Hospital, Philadelphia;
5. Department of Epidemiology, University of Iowa, Iowa City, Iowa;
6. Department of Neurosurgery, Penn State University, Hershey; and
7. Department of Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts;
8. Department of Engineering Science and Mechanics, Pennsylvania State University, State College, Pennsylvania