Third-Generation Pesticides
The first generation is exemplified by arsenate of lead; the second, by DDT. Now insect hormones promise to provide insecticides that are not only more specific but also proof against the evolution of resistance...
Features
Integrated Computer Memories
The standard computer memory consists of ring-shaped ferrite "cores" threaded on wires. In the search for bigger, faster and less costly memories a number of microelectronic devices are being investigated...
Tektites and Geomagnetic Reversals
The glassy stones strewn from the Indian Ocean to the South Pacific have an age that is coincident with the last reversal of the earth's magnetic field. Can both be attributed to the fall of a cosmic body?...
Escape From Paradox
Paradoxes and other apparently unsolvable problems can sometimes be solved by broadening the logical framework in which they are presented. A stubborn paradox in game theory provides an example...
Building a Bacterial Virus
T4 viruses with mutations in certain genes produce unassembled viral components. These particles are combined in the test tube in an effort to learn how the genes of a virus specify its shape...
The Leakage Problem in Fusion Reactors
To obtain useful power from thermonuclear reactions it is necessary to contain a plasma of ions and electrons in a magnetic bottle. The bottles leak, which presents the theoretician with a difficult task...
Pre-Columbian Ridged Fields
In four areas of tropical lowland in South America there are huge arrays of ancient earthworks. Many of them are ridges put up to farm land subject to seasonal flooding
General Tom Thumb and Other Midgets
He was a midget of a type that has not been known to lack pituitary hormone. Now it is clear that such midgets have a deficiency of the pituitary's growth hormone, which indicates that they can be treated...
Departments
50 and 100 Years Ago: July 1967
Science and the Citizen: July 1967
- Letters
Letters to the Editors, July 1967
- Recommended
Books
- Mathematical Recreation
Mathematical Games
- Amateur Scientist
The Amateur Scientist
- Departments
The Authors
Bibliography
