For one week every October, a serious bout of anxiety grips China. But it is not purely down to nervousness over which prominent dissident is in the running for the Nobel Peace Prize, awarded to the Dalai Lama in 1989 and Liu Xiaobo in 2010.

The threat of a "brain drain" has long lingered over China's ambitions to transform its economy from one reliant on low-cost manufacturing to one powered by home-grown innovation. Alert to the danger, Beijing has acted swiftly to counter the departure of its scientific and entrepreneurial talent overseas.