Hong Kong paid tribute to four world-scientific grandees yesterday with the announcement of this year's Shaw Prize, the city's version of the Nobel Prize.

The winners are an astronomer who helped explain why so many galaxies look like spiralling discs; two mathematicians who found deep connections between prime numbers and the mathematical principle of symmetry; and a professor of medicine who made fundamental discoveries on how cell receptors mediate the body's responses to drugs.

'The advancement of society and the prosperity of civilisations can be attributed to the contribution of great talents of past and present,' said Ma Lin, Shaw Prize council member and former Chinese University vice-chancellor, at the announcement ceremony yesterday.

'Their achievements enable us to enjoy the advantages of modern civilization.'

This is the fourth year that the prize - worth US$1 million in each category - has been awarded and a presentation ceremony will be held on September 11.

Peter Goldreich, of the California Institute of Technology and Princeton University, was awarded the astronomy prize for his lifetime achievements in theoretical astrophysics and planetary sciences, which range from the structure of galaxies to the low radio-frequency effects of one of Jupiter's moons on its planet.

The life sciences and medicine award goes to Robert Lefkowitz, a professor of medicine and biochemistry at Duke University in North Carolina, whose research underlies much of contemporary understanding of drug treatment.

Robert Langlands, of Princeton University, and Harvard University mathematician Richard Taylor will share the maths prize for their work in what has come to be known as the Langlands programme. This is a complex series of conjectures linking contemporary number theory to another important branch of mathematics called representation theory.

A conjecture of Professor Langlands was used by British-American mathematician Andrew Wiles in his celebrated proof of the centuries-old Fermat's Last Theorem. Professor Taylor studied under Wiles and helped him complete his proof.