When ice ages held Europe in their grip, Africa also felt the pinch - though in a different way.
It has long been suspected that there is a connection between the west African monsoon and climate at higher latitudes - especially over geological timescales, says David Lea at the University of California, Santa Barbara. "But until now, there hasn't been enough supporting evidence." Now Lea, with team leader Syee Weldeab and colleagues, has reconstructed the most detailed history of the monsoon yet, spanning 155,000 years and two ice ages.
Science & Technology
Paper cuts are actually pretty subtle phenomena and, as you point out, sometimes you get them and sometimes you don't.
The first thing that's needed to break skin is pressure. Pressure is force per unit area. To get an idea of why it's pressure that matters more than force, think of what's worse -- someone standing on your hand with a stiletto heel (small area in contact) or a flat shoe (large area).
With paper, the area of the edge that cuts you is tiny, so even a small force will give a large pressure. This is not the whole story, however, since paper is floppy and can buckle before it manages to cut through skin. To get a paper cut you need to have the paper supported in such a way that it tends not to bend easily. This can happen when you have a book or a ream of paper where one page can easily slide out a little from the rest and present a cutting edge, but still be held tightly against bending.
The first thing that's needed to break skin is pressure. Pressure is force per unit area. To get an idea of why it's pressure that matters more than force, think of what's worse -- someone standing on your hand with a stiletto heel (small area in contact) or a flat shoe (large area).
With paper, the area of the edge that cuts you is tiny, so even a small force will give a large pressure. This is not the whole story, however, since paper is floppy and can buckle before it manages to cut through skin. To get a paper cut you need to have the paper supported in such a way that it tends not to bend easily. This can happen when you have a book or a ream of paper where one page can easily slide out a little from the rest and present a cutting edge, but still be held tightly against bending.
Despite overwhelming military superiority, the world's most powerful nations failed to achieve their objectives in 39 percent of their military operations since World War II, according to a new University of Georgia study.
The study, by assistant professor Patricia L. Sullivan in the UGA School of Public and International Affairs, explains the circumstances under which more powerful nations are likely to fail and creates a model that allows policymakers to calculate the probability of success in current and future conflicts.
"If you know some key variables - like the major objective, the nature of the target, whether there's going to be another strong state that will intervene on the side of the target and whether you'll have an ally - you can get a sense of your probability of victory," said Sullivan, whose study appears in the June issue of the Journal of Conflict Resolution.
Sullivan said the most important factor influencing whether the more powerful nation is successful is whether its strategic objective can be accomplished with brute force alone or requires the cooperation of the adversary.
The study, by assistant professor Patricia L. Sullivan in the UGA School of Public and International Affairs, explains the circumstances under which more powerful nations are likely to fail and creates a model that allows policymakers to calculate the probability of success in current and future conflicts.
"If you know some key variables - like the major objective, the nature of the target, whether there's going to be another strong state that will intervene on the side of the target and whether you'll have an ally - you can get a sense of your probability of victory," said Sullivan, whose study appears in the June issue of the Journal of Conflict Resolution.
Sullivan said the most important factor influencing whether the more powerful nation is successful is whether its strategic objective can be accomplished with brute force alone or requires the cooperation of the adversary.
Humans might have finished off the woolly mammoths, but the genetics of the giants apparently helped them decline well beforehand, scientists now find.
The woolly mammoth (Mammuthus primigenius) was coated in hair up to 20 inches long and possessed extremely long, curved tusks up to 16 feet in length. The giants lived for tens of thousands of years, apparently going extinct roughly 12,000 years ago, around the end of the last ice age.
For years, scientists suspected that ancient human tribes hunted the mammoths and other ice age giants to oblivion. Recent research seems to contradict this notion, however - for instance, a comet or tuberculosis may have helped kill off the American mastodons (Mammut americanum), closely related to mammoths.
The woolly mammoth (Mammuthus primigenius) was coated in hair up to 20 inches long and possessed extremely long, curved tusks up to 16 feet in length. The giants lived for tens of thousands of years, apparently going extinct roughly 12,000 years ago, around the end of the last ice age.
For years, scientists suspected that ancient human tribes hunted the mammoths and other ice age giants to oblivion. Recent research seems to contradict this notion, however - for instance, a comet or tuberculosis may have helped kill off the American mastodons (Mammut americanum), closely related to mammoths.
Although stars with masses reaching up to 150 times the mass of the Sun are expected in the local Universe, no one has reliably found a star exceeding 83 solar masses so far. Until now that is. A team of astronomers from Universite de Montreal has identified the most massive star ever weighed. The details are being presented today by Professor Anthony Moffat at the annual meeting of the Canadian Astronomical Society (CASCA) held at the Royal Military College of Canada in Kingston (ON).
Anti-death penalty forces have gained momentum in the past few years, with a moratorium in Illinois, court disputes over lethal injection in more than a half-dozen states and progress toward outright abolishment in New Jersey.
A team of astronomers using the Canada-France-Hawaii Telescope on Mauna Kea has found the most distant -- and therefore oldest -- black hole so far discovered in the universe.
The team announced their find yesterday at the annual conference of the Canadian Astronomical Society in Ontario.
The black hole is nearly 13 billion light-years away from Earth, meaning its light has been traveling almost since the birth of the universe about 13.7 billion years ago.
The team announced their find yesterday at the annual conference of the Canadian Astronomical Society in Ontario.
The black hole is nearly 13 billion light-years away from Earth, meaning its light has been traveling almost since the birth of the universe about 13.7 billion years ago.
With a 4-inch gap in the space shuttle's heat-protecting blanket not appearing to be an urgent problem, the crew of Atlantis yesterday readied itself for what NASA called a delicate ballet with the international space station.
Then the shuttle today will begin a weeklong docking with the orbital outpost.
Atlantis's seven astronauts spent much of yesterday on a mandatory inspection of the shuttle's delicate heat tiles, outer edges, and blankets for problems similar to the kind that caused the fatal Columbia accident in 2003. No glaring problems were reported.
But late Friday and early yesterday, the crew spent extra time using a robot arm to look at a gap in a thermal blanket on the left side of the shuttle. The gap, about 4 inches, is the result of an unusual fold in the blanket, not a debris hit -- which caused Columbia's fatal problem, NASA spokeswoman Lynette Madison said.
Then the shuttle today will begin a weeklong docking with the orbital outpost.
Atlantis's seven astronauts spent much of yesterday on a mandatory inspection of the shuttle's delicate heat tiles, outer edges, and blankets for problems similar to the kind that caused the fatal Columbia accident in 2003. No glaring problems were reported.
But late Friday and early yesterday, the crew spent extra time using a robot arm to look at a gap in a thermal blanket on the left side of the shuttle. The gap, about 4 inches, is the result of an unusual fold in the blanket, not a debris hit -- which caused Columbia's fatal problem, NASA spokeswoman Lynette Madison said.
Sargassum seaweed, famous in nautical lore for entangling ships in its dense floating vegetation, has been detected from space for the first time thanks to an instrument aboard ESA's environmental satellite, Envisat. The ability to monitor Sargassum globally will allow researchers to understand better the primary productivity of the ocean and better predict climate change.
Using optical radiance data from the Medium Resolution Imaging Spectrometer (MERIS) aboard Envisat, Dr Jim Gower and Stephanie King of the Canadian Institute of Ocean Sciences and Dr Chuamin Hu of the US University of South Florida were able to identify extensive lines of floating Sargassum in the western Gulf of Mexico in the summer of 2005.
"This appears to be the first report of a satellite image of Sargassum," Gower said. "It is usually associated with the area of the North Atlantic known as the Sargasso Sea after the Sargassum encountered there by early explorers. Our observations of Sargassum lines extending over large areas of the Gulf show that in this area and season it represents a significant fraction of marine primary productivity."
Using optical radiance data from the Medium Resolution Imaging Spectrometer (MERIS) aboard Envisat, Dr Jim Gower and Stephanie King of the Canadian Institute of Ocean Sciences and Dr Chuamin Hu of the US University of South Florida were able to identify extensive lines of floating Sargassum in the western Gulf of Mexico in the summer of 2005.
"This appears to be the first report of a satellite image of Sargassum," Gower said. "It is usually associated with the area of the North Atlantic known as the Sargasso Sea after the Sargassum encountered there by early explorers. Our observations of Sargassum lines extending over large areas of the Gulf show that in this area and season it represents a significant fraction of marine primary productivity."
The US military is developing a robot with a teddy bear-style head to help carry injured soldiers away from the battlefield.
The Battlefield Extraction Assist Robot (BEAR) can scoop up even the heaviest of casualties and transport them over long distances over rough terrain.
The Battlefield Extraction Assist Robot (BEAR) can scoop up even the heaviest of casualties and transport them over long distances over rough terrain.
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