1. From Auckland Bioengineering Institute (J.Z., A.J.P., I.J.L., G.B.S., B.H.S.), Engineering Science (A.J.P.), and Physiology (I.J.L., B.H.S.), University of Auckland, Auckland, New Zealand; and the School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom (T.D.B., H.Z.).