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The Photorefractive Effect

A laser beam passing through a crystal can suddenly burst into a spray of light. This photorefractive effect may be the key to developing computers that exploit light instead of electricity

By David M. Pepper, Jack Feinberg and Nicolai V. Kukhtarev

Parental Imprinting of Genes

Even when fathers and mothers contribute identical genes to their offspring, the genes may have different effects. Sex-specific gene imprints may influence normal development and trigger diseases

By Carmen Sapienza

Ocean Acoustic Tomography

Oceanographers are using principles analogous to medical X-ray tomography to obtain three-dimensional images of ocean currents and temperatures

By Peter F. Worcester and Robert C. Spindel

Boron Neutron Capture Therapy for Cancer

A twofold treatment brings together boron and neutrons to create a lethal radiation that can attack tumor cells without damaging normal tissues in the process

By Albert H. Soloway, Ralph G. Fairchild and Rolf F. Barth

An Extraterrestrial Impact

Accumulating evidence suggests an asteroid or comet caused the Cretaceous extinction

By Frank Asaro and Walter Alvarez

A Volcanic Eruption

What dramatic event 65 million years ago killed most species of life on the earth? The author argues it was a massive volcanic eruption

By Vincent E. Courtillot

A Grandmaster Chess Machine

In the 40 years since this magazine published the original prospectus for a chess computer, machines have vanquished first novices, then masters and now grandmasters. Will Gary Kasparov be next?

By Andreas Nowatzyk, Feng-hsiung Hsu, Murray Campbell and Thomas Anantharaman


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