that mimic their effect and do it better than the genes themselves," Dickie said.

Those gathered in Cambridge have a run of talks into the evening on Saturday, with appearances from Andrei Linde from Stanford University, who helped formulate inflation theory in the 1980s, and Michael Green, the string theorist who is Hawking's successor as Lucasian professor of mathematics at the university.

Kitty Ferguson, author of Stephen Hawking: His Life and Work, said of Hawking: "He loves to go on a speculative edge and be in the vanguard and sometimes make outrageous and shocking suggestions – which everyone has to scurry around and get the mathematics together to see if he's right.

"It's that energy that he has, that spirit of adventure and fun. The fact that he is able to"We still can't say how many government employees and private passengers were killed, but there were heavy human losses."

At the blast site, the back of the colourfully decorated bus was torn apart, leaving a mass of snarled metal.

The injured, who included two policemen, were moved to Peshawar's Lady Reading Hospital. Local television footage showed locals carrying victims to the hospital in private vehicles.

US warning

The attack came one day after a remote-controlled bomb killed at least 15 people outside a madrassa, a religious school, in the southwestern city of Quetta.

Pakistan, a country of 180 million people, sits on the frontline of the US-led war on al-Qaeda and since July 2007 has been gripped by local Taliban-led attacks, concentrated largely in the northwest.

In the last five years, attacks blamed on