1. Department of Pediatrics, Stanford University, Stanford, CA 94305
2. Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720
3. Open Source Medical Software Corporation, Santa Monica, CA 90403
4. ICME, Stanford University, Stanford, CA 94305
5. Department of Pediatrics, Stanford University, Clark Center E100B 318 Campus Drive, Stanford, CA 94305-5428;
6. ICME, Stanford University, Stanford, CA 94305;
7. Department of Bioengineering, Stanford University, Stanford, CA 94305 e-mail: