Forty South African scientists have received an "A" rating as world leaders in their fields. For the first time one of them, Christina Mynhardt of the distance-learning University of South Africa, is a woman.

An "A" rating is bestowed on academics deemed by their peers around the world to be top international scientists, and earns funding aimed at enhancing their research. The system is managed in South Africa by the Foundation for Research Development, and runs in four-year cycles.

Eight of the country's 21 universities and one museum produced all 40 top-rated scientists. The University of Cape Town was significantly in the lead, with 15 A-rated scientists.

The University of the Wi****ersrand has eight, the University of Natal six, Rand Afrikaans University four, the Universities of South Africa and Stellenbosch two each, and the Universities of the Orange Free State and Pretoria have one top scientist each.

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South African research excellence is found in nearly 20 fields. There are seven world leaders in chemistry and allied fields, five in mathematics, four each in physics and zoology, and two each in statistics, microbiology and geological science.

But in the March edition of ScienceWatch, the United States publication which analyses international citation indices, a less positive picture emerges. Numbers of publications by South African scientists increased between 1981 and 1993.

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But at 0.57 per cent the country's proportion of world publications is slipping back to the levels of the early 1980s after peaking at 0.69 per cent in 1987.

The impact index for South African publications - the rate at which they are cited as references in international academic publications relative to a world standard - has been increasing since 1987/89 - the years of maximum output - peaking at 37 per cent below the world average in 1993.

Simon Mitton, science director of the Cambridge University Press, said: "South Africa has the potential to flourish in the scientific sphere. But major investment by international industries as well as the state will be required to make up for years of neglect, which intensified in 1986 with the imposition of economic sanctions by many countries."

Professor Mynhardt is a graph theorist in the University of South Africa's department of mathematics, applied mathematics and astronomy, disciplines which come out of the ScienceWatch analysis relatively well. Her reviewers rated her one of the top ten researchers worldwide in the field of domination in graphs.

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