August 16, 1997 | Volume 152 | Number 7
Cover:
Wheat is one of the three cereals that together provide half the world's calories. Though global harvests of all three have been growing for decades, their rate of growth has slowed recently -- to half the rate at which humanities numbers are increasing. Scientists are working to reinvigorate those yields, but their success appears threatened by increasing natural and fiscal constraints.
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MathLand
TimeLine
Food for Thought
The Mystery Box
Biological Pest Control Harms Natives
An insect imported to control exotic weeds now poses a threat to native plants.
The computer program Logistello defeated world champion Takeshi Murakami, winning six out of six games.
United neighbors take a bite out of crime
Violent crime rates drop in neighborhoods in which residents trust one another and show a willingness to act for the common good.
Volcanic explosions rocked the tiny island of Montserrat for 5 days in early August.
The abnormal accumulation of mutant proteins inside a cell's nucleus may underlie the neurodegeration seen in Huntington's disease and several similar illnesses.
An improved vacuum system leads to gallium arsenide crystals of record purity.
Conversion of an unusual form of frozen water into its more familiar crystalline counterpart creates pathways that release trapped gas molecules.
Mutated gene can delay onset of AIDS
An altered gene may delay AIDS onset in some HIV-positive individuals.
Research Notes:
Astronomy
Modeling the moon's originNew computer simulations are beginning to pin down the details of the moon's origin in a violent collision between Earth and a planet-sized body 4.5 billion years ago.
Earth, water, and comets
Measurements of the deuterium-hydrogen ratio in Comet Hale-Bopp suggest that comets could not have been the main source of water for Earth's oceans.
The Hubble Space Telescope and the Galileo spacecraft are providing new insight about three long-lived storms on Jupiter.
Science and Society
Counseling highlighted for gene test
The final version of a consensus document on genetic testing for cystic fibrosis, prepared by a National Institutes of Health panel, includes a statement emphasizing the importance of education and counseling.
A National Research Council report recommends that the federal government take charge of the care and management of chimpanzees used in scientific research.
Ammonia enhances cigarettes' nicotine . . .
A common cigarette additive puts tobacco's nicotine into a form that more readily enters the lungs.
. . . and music videos their image
A large percentage of music videos aired on television during hours when children watch feature role models who drink or smoke.
Articles:
Can Grain Yields Keep Pace?
Stiff challenges face today's breeders--and tomorrow's farmers
World cereal grain production is climbing at roughly half the pace of population growth, raising questions about what can be done to make up for the anticipated shortfall.
New detergents dissolve obstacles to pollutionfree solvents
Carbon dioxide may be the ideal replacement for the hazardous organic chemicals typically used in dry cleaning and plastics manufacturing.
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