Jon Cartwright
PhysicsWebFri, 06 Jul 2007 10:42 UTC
Some physicists gaze at the stars in the sky, but Victor Tsai of Harvard University and John Wettlaufer of Yale University in the US gaze at the stars on frozen lakes. Such star patterns often surround holes in ice, but the origin of their shape has always been a mystery. Now, by modelling their formation, the researchers have discovered that the shape is governed by the properties of the snow that covers the ice.
Wettlaufer was first inspired to investigate star patterns when he and his wife were looking out of an aeroplane window landing in Chicago and noticed a frozen lake peppered with the distinct shapes. "We were absolutely struck," he said. "My wife is from Sweden and she knew these as the harbingers of dangerous ice skating, but had never seen so many."
Jon Cartwright
PhysicsWebFri, 06 Jul 2007 10:19 UTC
"Swarming" is often seen in the animal kingdom, for example when schools of fish rapidly change direction to evade a predator. Now physicists in India and the US have made collections of tiny copper rods swarm by vibrating them between two plates. The researchers claim that their experiment shows how simple small-scale interactions can give rise to large-scale changes in behaviour and could provide a better understanding of swarming in living organisms.
A swarm can be thought of as a system in which the density of particles fluctuates wildly from place to place. One such system is a school of fish, which exhibit density fluctuations as the fish rapidly change direction. Although physicists have tried to develop mathematical models of swarming, there are few simple experimental systems available for testing them.
Now, however, Vijay Narayan of the Indian Institute of Science in Bangalore and colleagues have demonstrated swarming in a table-top experiment involving very simple inanimate objects - thousands of short copper rods less than a millimetre thick vibrated between two horizontal plates. The system is similar to a so-called "active nematic" liquid crystal - a fluid made up of long, symmetrical molecules.
In space, a loo costs a lot.
NASA has agreed to pay $19 million (€13.93 million) for a Russian-built toilet system for the international space station. The figure may sound astronomical for a toilet in space, but NASA officials said it was cheaper than building their own.
"It's akin to building a municipal treatment center on Earth," NASA spokeswoman Lynnette Madison said Thursday, explaining the cost of the new toilet system.
Also, astronauts are familiar with how it works since it is similar to one already in use at the space station. The new system will be able to transfer urine to a device that can produce drinking water.
The new system is scheduled to be delivered to the U.S. side of the space station in 2008. It will offer more privacy than the old toilet system, which will definitely be needed: The space station crew is expected to grow from three to six people by 2009.
KEITH RIDLER
APFri, 06 Jul 2007 04:05 UTC
Biologists at Washington State University say they have isolated a bacteria that may have contributed to the deaths of thousands of bighorn sheep in the West over the past five decades.
One of the strangest moons in our solar system is Hyperion, a Saturnian satellite so pockmarked by deep craters that it looks like a giant, rotating bath sponge adrift in space.
New image analyses suggest the moon's odd appearance is the result of a highly porous surface that preserves craters, allowing them to remain nearly as pristine as the day they were created.
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| ©NASA / JPL / SSI
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| This view of Hyperion, captured during the Cassini spacecraft's flyby in September 2005, reveals details of the moon's spongy surface. The picture is a combination of images taken using infrared, green and ultraviolet spectral filters.
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Comment: This is just the latest in a long line of evidence that there is far more loose material floating around our solar system than previously expected. Funny how it is never expressed in those terms.
Diggers constructing a new access road have uncovered a mysterious serpent-shaped feature, dating from the early bronze age.
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| ©BBC news
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| An aerial view of the 'Rotherwas Ribbon' - thought to be 4000 years old.
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The 197ft (60m) long ribbon of stones, found in Rotherwas, near Hereford, is thought to date from the same period as Stonehenge, roughly 2000 BC.
Archaeologists working on a remote Scottish island have discovered an ancient stone ceremonial enclosure that is perfectly aligned to the winter and summer solstices.
The find was made by members of the Bath and Camerton Archaeological Society (Bacas) working on the island of Foula.
Although the discrepancy is not large, it is significant: Geodesists from the University of Bonn have remeasured the size of the Earth in a long lasting international cooperation project. The blue planet is accordingly some millimeters smaller than up to now assumed. The results are important, for example, to be able to demonstrate a climate contingent rise in sea level. The results have now appeared in the renowned Journal of Geodesy.
The system of measurement used by the Bonn Geodesists is invisible. It consists of radiowaves that are transmitted into space from punctiform sources, the so-called Quasars. A network of more than 70 radio telescopes worldwide receives these waves. Because the gaging stations are so far apart from each other, the radio signals are received with a slight time-lag. ,From this difference we can measure the distance betwen the radio telescopes - and to the preciseness of two millimeters per 1,000 kilometers," explained Dr. Axel Nothnagel, reasearch group leader for the Geodesy Institute of the University of Bonn.
Ice cores drilled from southern Greenland have revealed the first evidence of a surprisingly lush forest that existed in the region within the past million years. The findings from an international study published today in the journal Science suggest that the southern Greenland ice sheet may be much more stable against rising temperatures than previously thought.
Researchers analysed ice cores from a number of locations in Greenland, including Dye 3 in the south of the country. From the base of the 2km deep Dye 3 core, they were able to extract what they believe is likely to be the oldest authenticated DNA obtained to date.
By analysing these DNA samples, the researchers identified a surprising variety of plant and insect life, including species of trees such as alder, spruce, pine and members of the yew family, as well as invertebrates related to beetles, flies, spiders, butterflies and moths. The researchers believe that the samples date back to between 450,000 and 800,000 years ago.
"We have shown for the first time that southern Greenland, which is currently hidden under more than 2km of ice, was once very different to the Greenland we see today," explains Professor Eske Willerslev, a Wellcome Trust Bioarchaeology Fellow from the University of Copenhagen, who led the study."Back then, it was inhabited by a diverse array of conifer trees and insects."
Villagers in central China dug up a ton of dinosaur bones and boiled them in soup or ground them into powder for traditional medicine, believing they were from flying dragons and had healing powers.
Until last year, the fossils were being sold in Henan province as "dragon bones" at about 2 yuan, or about 25 cents, per pound, scientist Dong Zhiming told the Associated Press yesterday.
Mr. Dong, a professor with the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, said when the villagers found out the bones were from dinosaurs they donated 440 pounds to him and his colleagues for research.
Comment: This is just the latest in a long line of evidence that there is far more loose material floating around our solar system than previously expected. Funny how it is never expressed in those terms.