1. Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT, UK.
2. Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK.
3. Dow Benelux B.V., Polyethylene Product Research, P.O. Box 48, 4530 AA, Terneuzen, Netherlands.
4. LyondellBasell Polyolefine GmbH, R&D Polymer Physics and Characterization, Frankfurt, Germany.
5. Departments of Physics and Chemistry, Durham University, Durham DH1 3LE, UK.