COMMISSION OF THE EUROPEAN COMMUNITIES ISSN 0014-2352 EURO ABSTRACTS Scientific and technical publications from Community-funded research and development VOL. 29 N° 2/1991 ABSTRACTS : PUBLICATIONS 29/149-29/300 EURO ABSTRACTS is compiled by the EABS (RTD-Publications), the on-line version of Euroabstracts, is accessible free of charge through ECHO (European Commission Host Organization). For information, Commission of the European Communities IM i XIII 'Telecommunications, Information Industries please contact : ECHO Customer Service BP 2373. L-1023 Luxembourg and Innovation' in association with © ECSC-EEC-EAEC, Brussels-Luxembourg, 1990. Reproduction is authorized, except for commercial purposes, provided the source is acknowledged. ECOTEC Research and Consulting Ltd Legal Notice: and published by the Neither the Commission of the European Communities nor any person acting on behalf of the Commission is responsible for the use Office for Official Publications of the European which might be made of the following information. Communities EURO ABSTRACTS The abstracting journal of scientific and technical publications of the Commission of the European Communities Vol.