Physical Disability and Public Policy
The civil rights of disabled Americans require a more accessible environment. The present Administration, however, hesitates to enforce laws calling for the removal of architectural barriers
Volume 248, Issue 6
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Features
A Vector for Introducing New Genes into Plants
The induction of a plant tumor by a bacterium is a natural form of genetic engineering. The piece of DNA the bacterium injects may serve as a tool for the genetic modification of crop plants
Giant Volcanic Calderas
They are craters tens of kilometers in diameter that remain after eruptions far more violent than any in the span ofhuman history. Perhaps 10 of them have been created over the past million years
Peking Man
In 230,000 years of cave dwelling Homo erectus pekinensis left an abundance of fossils and artifacts that now give information on biological, technological and perhaps even social evolution
Dark Matter in Spiral Galaxies
It appears that much of the matter in spiral galaxies emits no light. Moreover, it is not concentrated near the center of the galaxies
The Physiological Ecology of Whales and Porpoises
Like other mammals, these marine species have a high-energy way of life. In pursuing it they evolved particular adaptations of their own, notably the ability to dive deep for long periods
Georg Cantor and the Origins of Transfinite Set Theory
How large is an infinite set? Cantor demonstrated that there is a hierarchy of infinities, each one "Larger" than the preceding one. His set theory is one of the cornerstones of mathematics
The Slide Fastener
Otherwise known as the zipper, it took hold, so to speak, some 60 years ago. It is the creation of a host ofinventors going back to Elias Howe of the sewing machine, and the end is not in sight