1. Department of Physics; University of Bath; Bath BA2 7AY UK
2. School of Physiology and Pharmacology; Bristol CardioVascular; University of Bristol; Bristol BS8 1TD UK
3. Department of Physiology; School of Medicine of Ribeirão Preto; University of São Paulo; Ribeirão Preto SP Brazil
4. Department of Psychology; University of Virginia; Charlottesville VA 22904-4400 USA
5. Department of Cardiology; University Hospital Bristol NHS Trust; Bristol heart Institute; Bristol BS2 8HW UK
6. Department of Physics; and Marine Physical Laboratory; Bio-Circuits Institute; University of California San Diego; La Jolla CA 92093 USA