[1] Johns Hopkins Univ, Sch Med, Dept Biomed Engn, Baltimore, MD 21205 USA
[2] Med Coll Wisconsin, Dept Physiol, Milwaukee, WI 53226 USA
[3] Univ Western Ontario, Dept Med Biophys, London, ON, Canada
[4] Univ Virginia, Dept Biomed Engn, Charlottesville, VA USA
[5] Marquette Univ, Dept Math Stat & Comp Sci, Milwaukee, WI 53233 USA