1. Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine; University of Oxford; Oxford OX3 7LE UK
2. Department of Computer Science; University of Oxford; Oxford OX1 3QD UK
3. Metabolic Physiology, Department of Physiology, Institute of Neuroscience and Physiology; University of Gothenburg; SE-405 30 Gothenburg Sweden