Iron Deficiency
One of the most common health problems worldwide and potentially one of the most treatable, iron deficiency can have devastating effects. It can jeopardize a child's mental and physical development...
Features
Fullerenes
These cagelike molecules constitute the third form of pure carbon (the other two are diamond and graphite). C 60 , the archetype, is the roundest molecule that can possibly exist...
End of the Proterozoic Eon
Some 800 million years ago the earth entered a period of major tectonic and environmental change. An increase in oxygen levels probably occurred at this time, which in turn may have opened the door to large animals...
How the Immune System Learns about Self
The immature immune system produces cells that would attack every tissue in the body. Within the thymus, however, it learns which cells would be harmful, useless or useful
Natural Selection and Darwin's Finches
The finches of the Galápagos—the classic example of how natural selection works over millions of years-have now been observed to evolve in real time. A single drought can change a population...
The Origins of the Asteroids
Once regarded as "vermin of the skies," asteroids are now known to offer important clues to the birth of the solar system. They are the remnants of a planet that failed to form
Focused Ion Beams
Liquid-metal sources, their conical shape generated by electrostatic fields, produce charged atoms that can cut away and rebuild circuits on a microscopic scale
Soiled Shores
Cleanup technologies, from hot-water washing to fertilizer, were applied to the mess left by the Exxon Valdez oil spill. But nature, it seems, fared better on its own.
Departments
50 and 100 Years Ago: October 1991
Howls of Dismay
Greenhouse Gusher
Sol's Plumage
Spin Cycle
The Danger from Kuwait's Air Pollution
Crossed Lines
Sharper Image
Word Games
Sharing Germplasm
Digital Dyslexia
The Satisfaction of Delayed Gratification
The Light Fantastic
Don't Change the Channel, Rearrange that Face
Secret Garden
Body Heat
How's My Driving?
- Letters
Letters to the Editors, October 1991
- Recommended
Book Reviews, October 1991
- Mathematical Recreation
Concentration: A Winning Strategy
- Departments
An Illusion of Economic Stability?
Quantum English
