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The Geometric Phase

A circuit tracing a closed curve in an abstract space can explain both a curious shift in the wave function of a particle and an apparent rotation of a pendulum's plane of oscillation

By Michael Berry

Soft-X-Ray Lasers

A quarter of a century after the appearance of the optical laser, experimental X-ray lasers have begun to produce beams with wavelengths 100 times shorter than those of visible light

By Dennis L. Matthews and Mordecai D. Rosen

Snakes, Blood Circulation and Gravity

When a snake climbs or rears up, its cardiovascular system must resist strong pressure gradients. These effects of gravity explain why the circulatory system of a tree snake differs from that of a sea snake

By Harvey B. Lillywhite

Plasticity in Brain Development

The final wiring of the brain occurs after birth and is governed by early experience. A protein called MAP2 seems to take part in the molecular events that underlie the brain's ability to change

By Chiye Aoki and Philip Siekevitz

Managing Solid Waste

Poor disposal practices have taxed the U.S. economy and environment.Municipalities should construct better incinerators and landfills and support active resource-conservation and recycling programs

By Philip R. O'Leary, Patrick W. Walsh and Robert K. Ham

Fertilization in Mammals

The events that immediately precede and follow the fusion of sperm and egg must occur in a precise sequence. Surprisingly, a single molecule seems to have a crucial role at many points along the way

By Paul M. Wassarman

Canal Builders of Pre-Inca Peru

The engineers of Chimor built canals to carry water from rivers to fields as much as 70 kilometers away. In the end they were defeated by relentless geologie forces

By Charles R. Ortloff

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