All Stories
- Math
A Magic Knight’s Tour
For as long as chessboards have existed, there have been puzzles involving chessboards and chess pieces. Some of the most enduring conundrums involve knights. Example of a knight’s tour in which the rows and columns have the same sum (260), but the diagonals add up to 348 and 168. According to the rules of chess, […]
- Agriculture
Calling All Cows
Last May, tissues from the carcass of a North American cow turned up positive for bovine spongiform encephalopathy–the ailment responsible for mad cow disease. Within hours, the Canadian government traced the animal to the Alberta farm where it had been raised for its 8 years of life. In short order, other members of its herd […]
- Health & Medicine
Coronary Fix: Coated inserts keep vessels unclogged
Mesh cylinders called stents, which doctors use to prop open coronary arteries, work better when they are coated with sirolimus, a drug that inhibits the accumulation of cells along the device.
- Planetary Science
News Splash: Strong evidence of lakes on Titan
Using Earth-based radar to penetrate the thick atmosphere of Saturn's moon Titan, planetary scientists have the best evidence yet that the smog-shrouded moon has lakes or oceans of hydrocarbons over large stretches of its surface.
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In the era before global positioning system (GPS) instruments, determining longitude was difficult since it required a fairly accurate clock, in addition to a sextant. I was under the impression that one of the clocks Lewis and Clark used was Jupiter’s moon Io, which would have made them pretty sophisticated navigators. Michael D. DelanoBrooklyn, N.Y. […]
- Earth
North vs. Northwest: Lewis and Clark diaries provide directional clue
Observations from the Lewis and Clark expedition may offer insight into Earth's magnetic field.
- Health & Medicine
Timing That First Spoonful: Diabetes risk reflects when cereals enter infant diet
The timing of cereals' introduction into children's diets may affect their risk of developing type 1 diabetes, two studies suggest.
- Anthropology
Y Trail of the First Americans: DNA data point to late New World entry
Scientists identified a gene variant on the Y chromosome that allowed them to estimate that people first reached the Americas no earlier than about 18,000 years ago.
- Earth
Volcanic Legacy: Tortoises chronicle eruption in their genes
An ancient volcanic eruption in the Galápagos Islands left its legacy in the diminished genetic diversity of one subspecies of the archipelago's famed giant tortoises.
- Animals
Carnivores in Captivity: Size of range in wild may predict risk in zoo
A survey of zoo reports of troubled animals suggests that the minimum size of a species' range predicts how well it will adapt to captivity.
- Health & Medicine
One bug’s bane may be another’s break
People who carry pneumococcus bacteria in their nasal passages may be partially protected against having their noses colonized by Staphylococcus aureus.
- Health & Medicine
Drug combination unexpectedly flops
A combination of therapies that researchers anticipated would work well against HIV failed to stop the virus from replicating in more than half the volunteers who received it.
