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Advances in Optical Masers

Just three years ago this month the first optical maser, or laser, was announced. Today about 500 U.S. groups are engaged in laser development. The prospects are dazzling, the technical choices hard...

By Arthur L. Schawlow

The ACTH Molecule

A major product of the pituitary gland, the adrenocorticotropic hormone has an important role in health and disease. The study of its molecule shows how its function is related to structure...

By Choh Hao Li

Sex Differences in Cells

The chromosomes differ in males and females. So do certain other structures in cell nuclei. These distinctions are clues to the processes that determine the divergence of the sexes

By Ursula Mittwoch

The Voyage of Mariner II

Late in 1962 this 447-pound spacecraft flew by Venus in the deepest successful penetration of the solar system. A great technological feat, it produced much scientific information

By J. N. James

The Social Influence of Salt

Salt is a necessity of human life, and many people are addicted to using more of it than they need. Its sources are surprisingly limited, a fact that has shaped history in many curious respects...

By M. R. Bloch

The Archer Fish

This remarkable animal of southeast Asia downs its insect prey with a powerful spout of water. A discussion of the anatomical and behavioral adaptations that account for its unique ability...

By K. H. Lling

The Fermi Surface of Metals

It is not a real surface but a picture of how the electrons in a metal behave. These pictures explain such properties of metals as luster, ductility and the conduction of electricity and heat...

By A. R. Mackintosh

Inhibition in Visual Systems

Certain kinds of sensory nerve impulses suppress or inhibit the propagation of other impulses. This property enables the human eye to see contours more clearly and clams to respond to shadows...

By Donald Kennedy


  • 50 and 100 Years Ago: July 1963

  • Science and the Citizen: July 1963

  • Letters

    Letters to the Editors, July 1963

  • Recommended


  • Mathematical Recreation

    Mathematical Games

  • Amateur Scientist

    The Amateur Scientist

  • Departments

    The Authors

  • Bibliography

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