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The Accuracy of Strategic Missiles

The U.S. has initiated the development of ultra-accurate missiles capable of destroying the land-based missile force of the U.S.S.R. The technology behind the new "counterforce" strategy is reviewed...

By Kosta Tsipis

The Manipulation of Genes

Techniques for cleaving DNA and splicing it into a carrier molecule make it possible to transfer genetic information from one organism to an unrelated one. There the DNA replicates and expresses itself...

By Stanley N. Cohen

Positrons as a Probe of the Solid State

When positrons are injected into a crystalline substance, they are annihilated in encounters with electrons. The resulting gamma rays yield unique information on the atomic structure of the substance...

By Werner Brandt

The Journal Bearing

In the oldest and still the commonest bearing a shaft (the journal) rotates in a sleeve (the bearing). Achieving low friction, long life and low cost in such bearings calls for sophisticated design...

By John C. Bierlein

The Effects of Light on the Human Body

Sunlight tans skin, stimulates the formation of vitamin D and sets biological rhythms. Light is also used in the treatment of disease. Such effects now raise questions about the role of artificial light...

By Richard J. Wurtman


It is the acoustic signal generated by a rapidly expanding channel of heated air. From the information in this signal it is possible to deduce the location, shape and orientation of a lightning flash...

By Arthur A. Few

The Mechanical Design of Trees

As the trunk and branches of a tree grow they get not only longer but also thicker. What law governs the relation between the two dimensions? The question is examined by hypothesis and experiment...

By Thomas A. McMahon

Why Mosquito Repellents Repel

They are not substances that a mosquito somehow finds distasteful. They jam the mosquito's sensors so that it is not able to follow the warm and moist air currents given off by a warm-blooded animal...

By R. H. Wright


  • 50 and 100 Years Ago, July 1975

  • Science and the Citizen, July 1975

  • Letters

    Letters to the Editors, July 1975

  • Recommended

    Books, July 1975

  • Mathematical Recreation

    Mathematical Games, July 1975

  • Amateur Scientist

    The Amateur Scientist, July 1975

  • Departments

    The Authors, July 1975

  • Bibliography, July 1975

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