1. Sea Fisheries Research Institute, Private Bag X2, Rogge Bay, 8012 Cape Town, South Africa
2. Dept. Applied Mathematics FS-20, University of Washington, Seattle, WA 98195, USA
3. Dept. Mathematics, Southern Methodist University, Dallas, TX 75275, USA
4. TIMC-IMAG, CNRS URA 1618, Faculte de Medicine de Grenoble, 38700 La Tronche, France
5. Dept. Pathology and Neurological Surgery, University of Washington School of Medicine, Seattle, WA 98195, USA
6. Centre for Bioengineering, University of Washington, Seattle, WA 98195, USA