As a second-generation oilman, Zhang began working in 1990 for the First Machinery Factory of Huabei Petroleum Administration Bureau, a state oil subsidiary.
Under Barton's predecessor, Donald Fites, Cat squeezed its working capital in the machinery and engine businesses down to 10% of sales from 25% in 1991.
The signals that indicate where the copying machinery should start and stop, which is a good working definition of where on a chromosome a gene begins and ends, are imperfectly understood.