(19)

(11)

EP 0 591 335 A1

(12)

(43) Date of publication: 13.04.1994 Bulletin 1994/15 (21) Application number: 92913403.0 (22) Date of filing: 26.06.1992

(51) International Patent Classification (IPC):  G01R 27/ 26( . ) (86) International application number: PCT/GB1992/001160 (87) International publication number: WO 1993/000591 (07.01.1993 Gazette 1993/02)

(84) Designated Contracting States: DE FR NL (30) Priority: 28.06.1991 GB 19910140442 (71) Applicant: UNIVERSITY OF BRISTOL Bristol BS8 1TH (GB)	(72) Inventors: PREECE, Alan, William 12 South Dene Bristol BS9 2BW (GB) JOHNSON, Reginald, Harry 22 Geraldine Road Worcestershire WR14 3PA (GB) (74) Representative: Newstead, Michael John, et al  Page & Hargrave Temple Gate House Temple Gate Bristol BS1 6PL Bristol BS1 6PL (GB)