1. Mott MacDonald Group Ltd; 8-10 Sydenham Road, Croydon, Surrey CR0 2EE UK
2. Department of Medical Physics and Bioengineering; University College London WC1E 6BT; UK
3. Department of Aeronautics; South Kensington Campus, Imperial College London SW7 2AZ; UK
4. BuNova, Postbus 1072; 8001 BB Zwolle The Netherlands