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The Structure of the U.S. Economy

The input-output tables on the next seven pages divide the economy into 81 sectors and list the transactions among them. The numbers are the constants of the technological relations among the sectors...

By Wassily W. Leontief

The Control of Biochemical Reactions

The cell is a factory and enzymes are its machines. Two feedback systems control production, one regulating synthesis of enzymes, another their activity. Models of the two systems are described...

By Jean-Pierre Changeux

Attitude and Pupil Size

Dilation and constriction of the pupils reflect not only changes in light intensity but also ongoing mental activity. The response is a measure of interest, emotion, thought processes and attitudes...

By Eckhard H. Hess

Intense Magnetic Fields

Continuous fields as strong as 250,000 gauss, 500,000 times the strength of the earth's magnetic field, have been generated at the National Magnet Laboratory

By Henry H. Kolm and Arthur J. Freeman

An Early Neolithic Village in Greece

Excavations at Nea Nikomedeia in northern Greece have uncovered a community of 8,000 years ago. Its remains suggest that agriculture and animal husbandry came to Europe earlier than has been supposed...

By Robert J. Rodden

Moths and Ultrasound

Certain moths can hear the ultrasonic cries by which bats locate their prey. The news is sent from ear to central nervous system by only two fibers. These can be tapped and the message decoded...

By Kenneth D. Roeder

The Discovery of Icarus

A chunk of rock less than a mile in diameter, Icarus comes closer to the sun and the earth than any other asteroid whose orbit has been accurately computed. It should miss us by four million miles in 1968...

By Robert S. Richardson

The Stirling Refrigeration Cycle

In 1816 Robert Stirling invented an engine that operated by heating and cooling air in a closed cycle. The cycle has now been "reversed" in an efficient machine for cooling things to very low temperatures...

By J. W. L. Köhler


  • 50 and 100 Years Ago: April 1965

  • Science and the Citizen: April 1965

  • Letters

    Letters to the Editors, April 1965

  • Recommended


  • Mathematical Recreation

    Mathematical Games

  • Amateur Scientist

    The Amateur Scientist

  • Departments

    The Authors

  • Bibliography

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