Uncategorized
- Earth
Air-Pollution Pileup: Mediterranean endures emissions from afar
Although most Mediterranean countries aren't big polluters, the area is a crossroads for pollution-carrying air currents from Europe, Asia, and North America.
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Outmuscled: Muscles, not nerve cells, fail in old worms
In aging worms, the nervous system stays intact but muscles don't.
- Astronomy
Cloudy Findings: A new population shows up in the Milky Way
A radio telescope has detected a previously unknown population of hundreds of hydrogen clouds in the gaseous halo that surrounds the disk of our galaxy.
- Anthropology
Ancient Lure of the Lakes: Early Americans followed the water
Archaeological investigations in Chile indicate that beginning around 13,000 years ago, early American settlers lived at high altitudes during humid periods, when they could set up hunting camps on the shores of lakes.
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19147
I am concerned about this article. It addresses the mass of fissile materials needed to “make a bomb,” yet it’s clear that the critical masses given–10 kilograms for plutonium-239, 50 kg for uranium-235, and 60 kg for neptunium-237–are for bare spheres with no neutron moderation, reflection, or other factors contributing to going critical. Consider that […]
- Physics
Neptunium Nukes? Little-studied metal goes critical
Researchers have measured with far greater accuracy than ever before how much neptunium it would take to make a bomb.
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19186
In your article, a spinning coin’s motion is explained by the existence of an air cushion between coin and tabletop. If this is indeed the case, then I would expect coins to do something quite different in a vacuum. What do they do? Richard Chambers Charlotte, N.C. H. Keith Moffatt offers an explanation for the […]
- Ecosystems
Insects, pollen, seeds travel wildlife corridors
Strips of habitat boost insect movement, plant pollination, and seed dispersal among patches of the same ecosystem.
- Paleontology
Trackway site shows dinosaur on the go
Scientists say that a sediment-filled, bathtub-shape depression found at one of North America's most significant dinosaur trackway sites is the first recognized evidence of urination in dinosaurs.
- Paleontology
Curved claws hint at pterosaur habits
A study of the claws of flying reptiles known as pterosaurs suggests that some of the creatures may have walked like present-day herons and used their wing fingers to hold prey.
- Paleontology
Mosasaurs were born at sea, not in safe harbors
Newly discovered fossils of prehistoric aquatic reptiles known as mosasaurs suggest that the creatures gave birth in midocean rather than in near-shore sanctuaries as previously suspected.
- Paleontology
Stegosaur tails packed a punch
A mathematical analysis of a fossil stegosaur's bones leaves little doubt that the creature's spike-studded tail was an effective defense against predators.
