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Research with human subjects has produced advances in medicine but also some instances of ethical abuses. Studies of the attitudes and practices of investigators suggest that better controls are required
The cellular response to these hormones depends on the presence of protein molecules called receptors. The complex formed by the hormone and the receptor acts on the genetic material of the cell
Several theories of gravitation predict that the force of gravity diminishes as the universe expands. Preliminary results of timing eclipses of stars by the moon suggest that it may well be the case
Grasses and legumes that are fed to livestock are the mainstay of U.S. agriculture. Among their virtues is the fact that they can be grown on land that is not suited to growing other crops
Instructable machines capable of performing simple human tasks are appearing in many factories. Some experimental robots are being taught how to cope with uncertainties in the environment
When the glaciers retreated, the climate of Europe became variable. Tundra gave way to forest and forest to tundra. The technology and social organization of the indigenous hunters changed accordingly
The basic reaction mechanisms of organic chemistry are probed with the aid of these extremely reactive, short-lived molecules, created by depriving a carbon atom of two of its normal bonds
With the approach of winter, insects enter into a state of dormancy. This shift in metabolism implies that they have a clock to measure changes in the length of the day. What is the nature of the clock?