[1] DUNDEE INST TECHNOL,DEPT ELECTR & ELECTR ENGN,DUNDEE DD1 1HG,SCOTLAND
[2] UNIV ESSEX,DEPT PHYS,COLCHESTER CO4 3SQ,ESSEX,ENGLAND
[3] HERIOT WATT UNIV,DEPT PHYS,EDINBURGH EH14 4AS,MIDLOTHIAN,SCOTLAND
[4] SERC,DARESBURY LAB,WARRINGTON WA4 4AD,CHESHIRE,ENGLAND