Science & TechnologyS


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Freezing: A Phenomenon That "Jumps"

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© LSFC 2009Structure of ice crystals in the presence (left) or in the absence (right) of jumps in the interface. The arrows indicate future defects in the structure.
The freezing of suspensions of particles is not always a uniform phenomenon; in certain conditions it leads to a modification of the redistribution of particles and the growth of crystals. These results have been obtained by researchers at the Laboratoire de Synthèse et Fonctionnalisation des Céramiques (CNRS/Saint Gobain) and the Laboratoire Matériaux, Ingénierie et Sciences (CNRS/INSA Lyon) by observing, through X-ray imaging at the European Synchrotron Radiation Facility (ESRF), the movement of particles while they are being frozen.

Their work could make it easier not just to develop porous materials with specific properties but also to understand better the mechanisms of soils freezing in winter, which can have a considerable impact on plants, roads and thoroughfares. These results were published online in the journal Nature Materials on 8 November 2009.

What is the connection between sea ice formation at the poles, frozen soils in winter, cryopreservation of cells, ice-cream and composite material synthesis? All of these situations involve the propagation of a solidification interface and its encounter with particles, microorganisms or bubbles in suspension in a liquid. Although the phenomenon can be described in just a few words, its mechanism and control remain however extremely complex and still far from being fully understood.

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Right-Handed Chimpanzees Provide Clues to the Origin of Human Language

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© William D. HopkinsAn adult male extends his right arm toward an adult female in order to greet her.
Most of the linguistic functions in humans are controlled by the left cerebral hemisphere. A study of captive chimpanzees at the Yerkes National Primate Research Center (Atlanta, Georgia), reported in the January 2010 issue of Elsevier's Cortex, suggests that this "hemispheric lateralization" for language may have its evolutionary roots in the gestural communication of our common ancestors. A large majority of the chimpanzees in the study showed a significant bias towards right-handed gestures when communicating, which may reflect a similar dominance of the left hemisphere for communication in chimpanzees as that seen for language functions in humans.

A team of researchers, supervised by Prof. William D. Hopkins of Agnes Scott College (Decatur, Georgia), studied hand-use in 70 captive chimpanzees over a period of 10 months, recording a variety of communicative gestures specific to chimpanzees. These included 'arm threat', 'extend arm' or 'hand-slap' gestures produced in different social contexts, such as attention-getting interactions, shared excitation, threat, aggression, greeting, reconciliation or invitations for grooming or for play. The gestures were directed at the human observers, as well as toward other chimpanzees.

"The degree of predominance of the right hand for gestures is one of the most pronounced we have ever found in chimpanzees in comparison to other non-communicative manual actions. We already found such manual biases in this species for pointing gestures exclusively directed to humans. These additional data clearly showed that right-handedness for gestures is not specifically associated to interactions with humans, but generalizes to intraspecific communication," notes Prof. Hopkins.

Sherlock

Ancient Weapons Dug Up by Archaeologists in England

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© University of LeicesterOver 5000 worked flints came from one small area, including flint cores used for tool creation, blades, flakes and 'debitage' (small chips from tool-working), and scrapers, piercers and microlith tools with the latter being used in composite arrowheads.
Staff at the University of Leicester Archaeological Services (ULAS) have been excited by the results from a recently excavated major Prehistoric site at Asfordby, near Melton Mowbray, Leicestershire.

The Mesolithic site may date from as early as 9000BC, by which time hunter-gatherers had reoccupied the region after the last ice age. These hunters crossed the land bridge from the continental mainland -- 'Britain' was only to become an island several thousand years later.

The site was excavated during 2009 by ULAS in advance of a residential development for Jelson Homes Ltd. Initial trenching work identified several worked flint blades of characteristic Mesolithic type, and clearly in an unworn and undisturbed state. Further work confirmed that these rare flint finds were preserved in a Mesolithic soil, buried by a much later ploughsoil. Because this early soil had survived intact, it was thought possible that original features such as hearths and structures might still remain, and activities linked to the flint scatter could also be found.

Bulb

Scientists find key to creating clean fuel from coal and waste

'Gasification' process enhanced to save millions of tonnes of carbon and provide energy

Millions of tonnes of carbon dioxide could be prevented from entering the atmosphere following the discovery of a way to turn coal, grass or municipal waste more efficiently into clean fuels.

Scientists have adapted a process called "gasification" which is already used to clean up dirty materials before they are used to generate electricity or to make renewable fuels. The technique involves heating organic matter to produce a mixture of hydrogen and carbon monoxide, called syngas.

However gasification is very energy-intensive, requiring high-temperature air, steam or oxygen to react with the organic material. Heating this up leads to the release of large amounts of carbon dioxide. In addition, gasification is often inefficient, leaving behind significant amounts of solid waste at the end of the process.

To find out how to make the process more efficient, researchers led by Marco Castaldi, at the department of earth and environmental engineering at Columbia University, tried varying the atmosphere in the gasifier. They found that, by adding CO2 into the steam atmosphere of a gasifier, significantly more of the biomass or coal was turned into useful syngas.

Sun

Solar Prominence

Yesterday, Alan Friedman of Buffalo, New York, trained his telescope on the sun and waited for sunspot 1029 to reappear. But that wasn't going to happen. It was shaping up to be a dull observing session when something completely different popped into view.

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© Alan FriedmanCorpse of Sunspot 1029
"This magnificent looping prominence stole the show from the corpse of sunspot 1029," says Friedman. "It was the most dramatic prominence I have seen in many months."

The same prominence was putting on a show this morning, Nov. 15th, when the sun rose over the Philippines. "I was elated when I was able to see it clearly visible in the field of my eyepiece!" reports James Kevin Ty from Manila. "I quickly set up my PST (Personal Solar Telescope) and was able to monitor the prominence for more than 2 hours."

Igloo

Best of the Web: Study of lake in Ireland shows last ice age took just months to set in

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© UnknownBlackhead Lighthouse, where the Burren meets Galway Bay, Co. Clare, Ireland
It wasn't quite The Day After Tomorrow but it's closer than we thought. An analysis of mud from Lough Monreagh, a lake in Co Clare, has revealed that Europe was struck by a sudden mini ice age 12,800 years ago, suggesting the kind of rapid climate change previously seen only in Hollywood disaster movies.

It was believed that the "Big Freeze" took about a decade to set in. Based on an analysis of Greenland's ice cores, scientists have estimated that the Younger Dryas, as the event is also named, occurred gradually.

However, after analysing mud deposits from Lough Monreagh, William Patterson of the University of Saskatchewan in Canada, has found that the freeze took only months to take hold.

Using a very precise robotic scalpel, Patterson and his colleagues shaved 0.5mm layers from the lake bed, each representing up to three months of sediment. Carbon isotopes in the samples recorded changes to biological activity in the lake, while oxygen isotopes revealed temperature and rainfall patterns.

The tiny mud deposits showed for the first time that temperatures in Ireland dropped suddenly in the space of several months at the time of the Big Freeze.

Comment: We can add this to the growing body of data pointing to the very real prospect of a sudden onset ice age:

Fire and Ice: The Day After Tomorow


Question

A Physics Paradox: Holes That Block Light

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© J. Braun et alNo entry. A scanning electron microscope image of the gold film, which didn't let much light through its holes
The way light moves, with its fixed speed and its ability to act like either a wave or a particle, often leads to some of the most curious paradoxes of physics. A new one has just been found: Make holes in a film of gold so thin that it's already semitransparent, and less light gets through.

Because of its wave nature, light generally can't squeeze through a hole whose width is smaller than the wavelength of the light. In 1998, however, researchers discovered that light could zip through certain patterns of such holes punched into thin metal plates. Physicists figured out that the light created waves in the metal's electrons--called plasmons--that move across the material's surface in much the same way that ripples move through water. The plasmons, which have wavelengths much shorter than light, couple with each other across the tiny holes and pull the light along for the ride. One possible application is to use plasmons to build better light-based integrated circuits that would be as fast as fiber optics but less bulky.

Toward this end, researchers from the University of Stuttgart in Germany laid very thin films of gold onto pieces of glass and then used ion beams to etch the film with holes arranged in a regular, square array. These holes were smaller than the wavelength of light and, despite being so tiny, are just the kind of openings that have been shown to let light through the thicker, opaque film used in the 1998 experiment. But in the new experiment, the gold film was so thin--only 20 nanometers--that light could already shine through it. And surprisingly, less light went through the holey gold than through the original semitransparent film.

Telescope

University of Alberta Physicist Solves Mystery of Supernova 11,000 Years Ago

It took a decade, but two scientists have solved the mystery behind a chunk of radioactive rock the size of a small city that has been floating in space.

It turns out the material, discovered by astronomers in 1999, is the core of a supernova, or exploding star, that occurred 11,000 years ago, but only became visible 330 years ago.

Craig Heinke, a physics professor at the University of Alberta, along with Wynn Ho of Southampton University in the United Kingdom, finally figured it out.

"I'm pretty pumped. It's been absolutely great," said Heinke in an interview with The Canadian Press. The duo's findings are being published in the Nov. 5 edition of Nature.

"This one has been a real puzzle for about 10 years since other astronomers detected this object first. We have been able to figure out what it is. We are able to show conclusively that this is a neutron star, something that was not entirely clear before," Heinke explained.

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Flashback The Puzzle of the Half-Comet, Half-Asteroid

A mysterious object that ejects dust like a comet but orbits like an asteroid could be a new class of object in the solar system.

comsteroid
In 1996, astronomers identified an extraordinary object orbiting the Sun between Mars and Jupiter in a region best known for its asteroids. And yet this body, called 133P, defied description: it had the orbit of an asteroid yet emitted dust like a comet.

Sherlock

Incas Practiced Ritual Decapitation of Enemies, Archaeologists Say

Peruvian archaeologists have reached the conclusion that the Incas decapitated their enemies to use their heads as offerings after finding three skulls in a ceremonial vessel in the southeastern city of Cuzco.

The director of Sacsayhuaman Archaeological Park, Washington Camacho, told EFE Friday that the heads found this week on Qowicarana ridge, an ancient ceremonial center north of Cuzco, could have been those of ancient chiefs or leaders of peoples who were enemies of the Incas.

For the archaeologist, the "trophy heads" could have been cut off "during a battle or in some other place after the capture of these "curacas" (chiefs of enemy peoples).

It is believed, Camacho said, that the offering of heads belonged to "the last phase of the Inca Empire," in other words around 1500, probably "when Huayna Capac reigned."