1. Harvard/MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Mass. 02139
2. Department of Surgery, Harvard Medical School, Boston, Mass. 02139, and Blood Bank and Transfusion Service, Massachusetts General Hospital, Boston, Mass. 02114
3. Bio-Heat Transfer Laboratory, Biomedical Engineering Center, The University of Texas at Austin, Austin, Tex. 78712
4. Cryogenic Engineering Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Mass. 02139