1. Department
of Chemical Engineering, Imperial College London, London SW7 2AZ, U.K.
2. ISIS
Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, U.K.
3. Department
of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, U.K.
4. BP Exploration Operating Co. Ltd., Sunbury-on-Thames TW16 7LN, U.K.