Scientific American Magazine Vol 262 Issue 4

Scientific American Magazine

Volume 262, Issue 4

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Features

Deforestation in the Tropics

Government policies that encourage exploitation-in particular excessive logging and clearing for ranches and farms-are largely to blame for the accelerating destruction of tropical forests

Robert Repetto

What is Happening at the Center of Our Galaxy?

This mysterious region contains antimatter, radioactive clouds, veiled sources of intense radiation, swirling gas and dust and an unseen object with a tremendous gravitational pull-perhaps a massive black hole

Charles H. Townes, Reinhard Genzel

The Unusual Origin of the Polymerase Chain Reaction

A surprisingly simple method for making unlimited copies of DNA fragments was conceived under unlikely circumstances-during a moonlit drive through the mountains of California

Kary B. Mullis

Impact Cratering on the Earth

The explosion of the world's nuclear arsenal could not match the power released when a kilometer-size meteorite hits the earth. Have impacts even more powerful altered biological as well as geologic evolution?

Richard A. F. Grieve

Advanced Light-Water Reactors

New designs that include "passive" safety features can make nuclear power more attractive, but only if attention is paid to economics, effective management and rigorous training methods

Neil E. Todreas, Michael W. Golay

What the Brain Tells the Eye

A circadian clock adjusts the sensitivity of the horseshoe crab's eyes. Study of the mechanism opens a window on the brain's control of sensory organs in other animals as well

Robert B. Barlow Jr.

The Transformation of the Kalahari !Kung

Why after centuries of stability has this society, an apparent relic of ancient hunting and gathering groups, abandoned many of its traditional ways?

John E. Yellen

Ancient Glazes

The beauty of a glazed ceramic arises from the interplay of light with the complex structure of the glaze. The methods of materials science reveal the ingenuity of ancient glazing technologies

Pamela B. Vandiver

Departments

Letters to the Editors, April 1990

50 and 100 Years Ago: April 1990

Slow Boat to Mars

Right to Lie?

Acid Test

Science Behind the Wall

Zap!

Gone in a Flash

All about Eve

Green Thumbs

Net Result: Folded Protein

Space Invaders

Tone of Relief

Mandelbrot Set-To

Milliken & Co.

Of Mice and Men

Atmosphere of Uncertainty

Cashcowosaurus

Breakup?

The Analytical Economist: Budgeting Smoke and Mirrors

The Amateur Scientist, April 1990

Books, April 1990

Essay: A New Initiative to Save the Planet