1. From the Department of Anesthesiology, Mayo Clinic, Rochester, MN (J.N.B., E.C.H., T.B.C., W.T.N., J.H.E., M.J.J.); Institute of Neuroscience and Physiology, The Sahlgren Academy at Gothenburg University, Goteborg, Sweden (B.G.W.); and Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA (N.C.).