Scientific American Magazine

Below the arid surface of the great desert are huge natural reservoirs of water. These resources are now beginning to be studied and exploited for the benefit of the Saharan nations

Predicted in 1962 by a British graduate student, these two unusual manifestations of the superconducting state have now been observed directly. Their theoretical and technological significance is discussed

Chelates are molecules that can seize a metal ion in a clawlike structure. Some of these substances are already used in medicine, and the principle seems to have even wider clinical applications

Concluding a series of three articles on the highly successful voyage of the spacecraft. Its instruments not only provided new information on Mars but also monitored fields and particles in planetary space

The dramatic changes of the process are stimulated by thyroid hormone. The level of hormone is regulated by a feedback system involving the hypothalamus of the brain and the pituitary gland

While Egypt and Sumer prospered, a state of greater size was swept away In South Asia. Aryan invaders have traditionally received the blame; it now appears that instead the Harappans were flooded out

In muscular action some muscles must be stimulated to contract and others must be inhibited from doing so. In vertebrates this inhibition occurs at the level of the brain and the spinal cord

"Normally a sphere can be turned inside out only if it has been torn. In differential topology one assumes that the surface can be pushed through itself, but then the problem is to avoid forming a crease"