1. Department of Human Physiology, Flinders University, Bedford Park, South Australia, Australia
2. Department of Gastroenterology and Hepatology, St George Hospital, University of New South Wales, Australia
3. Commonwealth Scientific and Industrial Research Organisation Materials Science and Engineering, Lindfield, Australia
4. Department of Anorectal Physiology, St George Hospital, University of New South Wales, Kogarah, New South Wales, Australia
5. Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand