1. PhD Precandidate, Dept. of Mechanical Engineering, Univ. of Michigan, 2250 G.G. Brown, 2350 Hayward, Ann Arbor, MI 48109-2125.
2. Dept. of Electrical Engineering and Computer Science, Case Western Reserve Univ., 10900 Euclid Ave., Cleveland, OH 44106.
3. Dept. of Mechanical Engineering, Univ. of Michigan, 2250 G.G. Brown, 2350 Hayward, Ann Arbor, MI 48109-2125.
4. Dept. of Electrical Engineering and Computer Science, Case Western Reserve Univ., 10900 Euclid Ave., Cleveland OH 44106. Current address: Dept. of Biomedical Engineering, The Cleveland Clinic Foundation, Cleveland OH 44195.
5. BFGoodrich Professor of Engineering Innovation, Dept. of Electrical Engineering and Computer Science, Bingham Bldg, Room 118, Case Western Reserve Univ., 10900 Euclid Avenue, Cleveland, OH 44106 (corresponding author).