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A Ban on the Production of Fissionable Material for Weapons

Such a "cutoff" could serve two purposes: to stall the further buildup of nuclear arms by the present nuclear-weapons states and to prevent their spread to the non-nuclear-weapons states...

By William Epstein

Systemic Lupus Erythematosus

A rheumatic disease with varied symptoms, SLE is a disorder of the immune system. A patient makes autoantibodies that bind to such antigens as DNA, forming immune complexes that can injure tissue...

By David Koffler

Gamma-Ray-Line Astronomy

Astrophysical processes emit fine-tuned electromagnetic radiation at energies even greater than those of X rays. The resulting spectral lines can now be detected by instruments on balloons and satellites...

By Crawford J. MacCallum and Marvin Leventhal

Megalithic Monuments

These assemblages of massive stones, of which Stonehenge is one, are found by the thousands in Europe. How old they are was long uncertain, but they have now been dated to the Neolithic period...

By Glyn Daniel


The spontaneous upwelling of a heated fluid can be understood only by untangling the intricate relations among temperature, viscosity, surface tension and other characteristics of the fluid...

By Christiane Normand and Manuel G. Velarde

The Physiology of the Koala

This gentle marsupial eats mainly eucalyptus leaves (which are toxic to other animals) seldom drinks and uses no shelter. Recent studies indicate how the animal manages to survive in its distinctive niche...

By Robert Degabriele

Supercoiled DNA

In many forms of DNA the double helix itself forms a helix. This supercoiling, which has important biological consequences, is best described and analyzed by means of a simple mathematical model...

By F. H. C. Crick, James H. White and William R. Bauer

The Screw Propeller

Ship screws and aircraft propellers look quite different, but both are designed according to the circulation theory of lift. The theory is the traditional one developed to account for the lift of an airfoil...

By E. Eugene Larrabee


  • 50 and 100 Years Ago, July 1980

  • Science and the Citizen, July 1980

  • Letters

    Letters to the Editors, July 1980

  • Recommended

    Books, July 1980

  • Mathematical Recreation

    Mathematical Games, July 1980

  • Amateur Scientist

    The Amateur Scientist, July 1980

  • Departments

    The Authors, July 1980

  • Bibliography, July 1980

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