1. Department of Mathematics, University of Auckland, Auckland, New Zealand;
2. Secretory Mechanisms and Dysfunction Section, Division of Intramural Research, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland;
3. Department of Pharmacology and Physiology and the Center for Oral Biology, University of Rochester Medical Center, Rochester, New York; and
4. Auckland Bioengineering Institute and Department of Engineering Science, University of Auckland, Auckland, New Zealand