Uncategorized
- Math
Knot Views
Interested in playing around with some mathematical knots? Manuel Arala Chaves of the University of Porto in Portugal has created a table illustrating all 75 knots with up to 9 crossings in their standard representation. If your computer can handle LiveGraphics3D, you can manipulate the knots in three dimensions and look at them from different […]
- Math
Follow the Leader
In the sport of orienteering, a competitor uses a detailed map (and perhaps a compass) to navigate his or her way across varied terrain following a course drawn on the map. Selecting the best available route, each participant races from one marker to the next in the required sequence. The winner is the person who […]
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18976
The story correlates red tides in Florida with Saharan dust storms. The cover story of the same issue (“Dust, the thermostat,” p. 200: Dust, the Thermostat) dealt, in part, with dust blowing across the Mediterranean Sea and the Atlantic Ocean. Are there “red tides” in these areas? Are they correlated with Saharan dust? David D. […]
- Earth
Rain of foreign dust fuels red tides
Soil particles from Africa, raining out from clouds over the Americas, may trigger the first steps that lead to toxic red-tide algal blooms off Florida.
- Earth
EU moves against flame retardants
The European Union has provisionally voted to ban the use and importation of nearly all members of a family of flame retardants known as polybrominated diphenyl ethers.
- Earth
Where’s the smoke from the N.Y. fires?
Analyses of smoke from the destroyed World Trade Center towers indicated little risk that the fires would cause significant health effects for cleanup crews and city residents.
- Anthropology
Humans in eastern Asia show ancient roots
Human ancestors lived in northeastern Asia about 1.36 million years ago, making it the oldest confirmed occupation site in eastern Asia.
- Health & Medicine
Acacia-tree extract fights cancer in mice
Compounds called avicins extracted from Acacia victoriae, an Australian desert tree, inhibit inflammation and cancer in test-tube and mouse studies.
- Health & Medicine
Germs can survive weeks on fabrics, plastic
Soft, dry surfaces in hospitals can harbor live germs for more than a month.
- Health & Medicine
Blood vessels (sans blood) shape organs
Even before they begin to carry blood, blood vessels provide signals that help spark the development of organs such as the liver.
- Animals
Meerkat pups grow fatter with extra adults
Meerkat pups growing up in large, cooperative groups are heftier because there are more adults to entreat for food.
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18975
We read that the Chaco Anasazi builders used “large timbers” 5 meters long, 22 centimeters in diameter, and weighing 275 kilograms. As anyone who splits his own firewood could tell you, something is amiss here. The Handbook of Chemistry and Physics tells us that ponderosa pine has a density of about 0.5 gram per cubic […]
