1. Division of Aerospace Medicine, Wright State University, Dayton, Ohio.
2. Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas.
3. The University of Texas Health Science Center at Houston, Houston, Texas.
4. The University of Texas Medical Branch at Galveston, Galveston, Texas.
5. University General Hospital, Houston, Texas.