Tuesday, May 4, 2010

VOLCANIC ERUPTION IN ICELAND UNLIKELY TO HAVE GLOBAL EFFECTS

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The eruption of an Icelandic volcano that sent a huge plume of ash into the atmosphere and caused sweeping disruptions of air traffic over Great Britain and Scandinavia today will likely dissipate in the next several days, according to a University of Colorado at Boulder atmospheric scientist.

Professor Brian Toon, chair of CU-Boulder's atmospheric and oceanic sciences department, said the plume created by the eruption of the Eyjafjallajokull Volcano contains tiny rock particles made up of silicate and basaltic glass that can be extremely damaging to aircraft engines. Unfortunately, the plume is at about 30,000 feet -- the same altitude as jet aircraft fly -- and is directly in the flight path between New York and Europe, he said.

The destination and duration of the volcanic plume depends primarily on weather conditions like rain and winds, said Toon. The plume should get washed away by rain as it continues to drift east, and likely will have no effect on the United States, he said. Fortunately, the plume also is below the stratosphere, where volcanic gases can have global effects because of a lack of rain there prohibits the removal of volcanic material.

Toon said the amount of sulfur dioxide spewed by the volcano so far poses no threat to world climate as determined by an instrument aboard NASA's Aura satellite. But he noted than an apparently larger eruption of an Icelandic volcano in 1783 --which was written about by Benjamin Franklin -- caused some climate issues in Europe by creating smog-like conditions in London that partially blocked out the sun and persisted through the summer months.

Toon compared the Icelandic eruption to the popping of a champagne bottle cork. When the pressure is released by breeching the rock "cork," gases bubble out, spewing tiny rock particles into the air like champagne droplets. Such rocks threaten the safety of airliners.

Toon was involved in a 2000 NASA research campaign to study Arctic ozone when a research jet passed through a similar Icelandic volcanic plume from Mount Hekla, damaging the engine turbines and subsequently requiring the replacement of the jet's engines at a cost of several million dollars. Several other similar incidents in the past several decades also have caused the failure of jet engines, but the aircraft were able to restart their engines and no crashes occurred, he said.

University of Colorado at Boulder

NEW BONY-SKULLED DINOSAUR SPECIES DISCOVERED IN TEXAS

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Paleontologists have discovered a new species of dinosaur with a softball-sized lump of solid bone on top of its skull, according to a paper published in the April issue of the journal Cretaceous Research.

The species was a plant-eating dinosaur about as big as a medium-sized dog that lived 70 to 80 million years ago, said Nicholas Longrich of Yale University, lead author of the paper. The team discovered two skull fragments in Big Bend National Park in southwest Texas in 2008. They compared them to dozens of fossils from related species found in Canada and Montana before confirming that the fossils represented a new genus of pachycephalosaur, a group of bipedal, thick-skulled dinosaurs.

The researchers named the new species Texacephale langstoni. (“Texacephale” means “Texas head” and “langstoni” is in honor of Wann Langston, a fellow paleontologist.) The new species is one of about a dozen known to have solid lumps of bone on top of their skulls, which Longrich speculates was probably used to ram one another head-on in a manner similar to modern-day musk oxen and cape buffalo.

The discovery of the new species lends further weight to the idea, which has gained popularity in recent years, that dinosaurs found in Canada and the northern United States were distinct from their southern neighbors.

“Instead of roaming across the North American continent, we see pockets of different dinosaurs that are pretty isolated from one another,” Longrich said. “Every time we get good fossils from Texas, they end up looking very different from those to the north.”

Because fossils from the Big Bend region are rare and tend to be poorly preserved, scientists do not have a complete picture of the different species that once inhabited the area, Longrich said.

But the team may have uncovered an important piece of the puzzle with their discovery. They found that this particular group of dinosaurs, which was previously thought to have originated in Asia, likely evolved in North America.

Longrich expects more related species to be discovered in the future as fossils from the Texas site and elsewhere continue to be examined.

“I think we underestimate how many different species there were,” he says.

Other authors of the paper include Julia Sankey (California State University, Stanislaus), who led the fieldwork, and Darren Tanke (Royal Tyrrell Museum), who discovered the more complete specimen on which the naming of the new species was based.

(Photo: Nicholas Longrich)

Yale University

CARBON NANOTUBES BOOST CANCER-FIGHTING CELLS

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Yale University engineers have found that the defects in carbon nanotubes—cylindrical carbon molecules with novel properties that are useful in a number of applications, including nanotechnology and optics—cause T cell antigens to cluster in the blood and stimulate the body’s natural immune response. Their findings, which appear as the cover article of the April 20 issue of the journal Langmuir, could improve current adoptive immunotherapy, a treatment used to boost the body’s ability to fight cancer.

Adoptive immunotherapy involves extracting a patient’s blood so that the number of naturally occurring T cells (a type of white blood cell) can reproduce more effectively in the laboratory. Although the body produces its own tumor-fighting T cells, they are often suppressed by the tumor and are too few to be effective. Scientists boost the production of T cells outside the body using different substances that encourage T cell antigens to cluster in high concentrations. The better these substances are at clustering T cell antigens, the greater the immune cell proliferation. Once enough T cells are produced, the blood is transferred back into the patient’s body.

The Yale team had previously reported the unexpected effect that carbon nanotubes had on T cell production. They found that the antigens, when presented on the surface of the nanotubes, stimulated T cell response far more effectively than coating other substrates such as polystyrene in the antigens, even though the total amount of antigens used remained the same.

Now they have discovered the reason behind the increased stimulation. They found that the antigens cluster in high concentrations around the tiny defects found in the carbon nanotubes.

“Carbon nanotube bundles resemble a lymph node microenvironment, which has a labyrinth sort of geometry,” said Tarek Fahmy, associate professor of chemical engineering and biomedical engineering at Yale and senior author of the paper. “The nanotube bundles seem to mimic the physiology and adsorb more antigens, promoting a greater immunological response.”

Current adoptive immunotherapy takes weeks to produce enough T cells, but lab tests showed that the nanotubes produced the same T cell concentration in just one-third the time, Fahmy said.

Carbon nanotubes can cause problems, such as an embolism, when used in the body. But this isn’t the case when they are used in blood that has been extracted from the patient, Fahmy said. Next, the team will work on a way to effectively remove the carbon nanotubes from the blood before it is returned to the patient.

“We think this is a really interesting use of carbon nanotubes. It’s a way to exploit the unique properties of this material for biological application in a safe way.”

Other authors of the paper include lead author Tarek Fadel, Michael Look, Peter Staffier, Gary Haller and Lisa Pfefferle, all of the Yale School of Engineering & Applied Science.

(Photo: Tarek Fahmy/Yale University)


CALTECH RESEARCHERS CREATE 'SOUND BULLETS'

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Taking inspiration from a popular executive toy ("Newton's cradle"), researchers at the California Institute of Technology (Caltech) have built a device—called a nonlinear acoustic lens—that produces highly focused, high-amplitude acoustic signals dubbed "sound bullets."

The acoustic lens and its sound bullets (which can exist in fluids—like air and water—as well as in solids) have "the potential to revolutionize applications from medical imaging and therapy to the nondestructive evaluation of materials and engineering systems," says Chiara Daraio, assistant professor of aeronautics and applied physics at Caltech and corresponding author of a recent paper in the Proceedings of the National Academy of Sciences (PNAS) describing the development.

Daraio and postdoctoral scholar Alessandro Spadoni, first author of the paper, crafted their acoustic lens by assembling 21 parallel chains of stainless steel spheres into an array. Each of the 21 chains was strung with 21 9.5-millimeter-wide spheres. (Daraio says particles composed of other elastic materials and/or with different shapes also could be used.)

The device is akin to the Newton's cradle toy, which consists of a line of identical balls suspended from a frame by wires in such a way that they only move in one plane, and just barely touch one another. When one of the end balls is pulled back and released, it strikes the next ball in line and the ball at the opposite end of the cradle flies out; the balls in the middle appear to remain stationary (but really are not, because of the nonlinear dynamics triggered in the system).

The chains of particles in Daraio's and Spadoni's acoustic lens are like a longer version of a Newton's cradle. In the lens, a pulse is excited at one end by an impact with a striker, and nonlinear waves are generated within each chain. These chains, Daraio says, "are the simplest representation of highly nonlinear acoustic waveguides, which exploit the properties of particle contacts to tune the shapes of the traveling acoustic signals and their speed of propagation, creating compact acoustic pulses known as solitary waves." Solitary waves—unlike the rippling waves produced by dropping a pebble into a pond—can exist in isolation, neither preceded nor followed by other waves.

"The solitary waves always maintain the same spatial wavelength in a given system," she adds, "and can have very high amplitude without undergoing any distortion within the lens, unlike the signals produced by currently available technology."

The chains are squeezed closer together—or "precompressed"—using fishing line. By changing the amount of precompression, Daraio and Spadoni were able to vary the speed of the solitary wave. When a series of those waves exit the array, they coalesce at a particular location—a focal point—in a target material (which can be a gas, like air; a liquid; or a solid). This superposition of solitary waves at the focal point forms the sound bullet—a highly compact, large-amplitude acoustic wave. Varying the parameters of the system can also produce a rapid-fire barrage of sound bullets, all trained on the same spot.

In the current design, the spheres are assembled in a two-dimensional arrangement, with each row independent of its neighbors. "Three-dimensional arrangements will be just as easy to create and will allow 3-D control of the sound bullets' appearance and travel path," Spadoni says.

"Our lens introduces the ability to generate compact, high-amplitude signals in a linear medium, and also allows us to dynamically control the location of the focal point," Daraio says. That means it isn't necessary to change any of the geometric components of the lens to change the location of the focal point.

"All we do is adjust the precompression for each chain of spheres," she says.

This simple adjustment should make the sound bullets easy to adapt to a variety of applications. "Anybody who has had an ultrasound exam has noted that the operator switches the probes according to the characteristics and location within the body of what is being imaged," Daraio says. "The acoustic lens we propose would not require replacement of its components, but rather simple adjustments of the precompression on each chain."

The acoustic lens created by Daraio and Spadoni was intended to be a proof of concept, and is probably many years away from being used in commercial applications. "For practical uses," Daraio says, "an improved design for controlling the application of static precompression on each chain would be required—based, for example, on electronics rather than on mechanical impacts as is currently done in our lab."

Still, the instrument has the potential to surpass the clarity and safety of conventional medical ultrasound imaging. The pulses produced by the acoustic lens—which are an order of magnitude more focused and have amplitudes that are orders of magnitude greater than can be created with conventional acoustic devices—"reduce the detrimental effects of noise, producing a clearer image of the target." They also "can travel farther"—deeper within the body—"than low-amplitude pulses," Daraio says.

More intriguingly, the device could enable the development of a non-invasive scalpel that could home in on and destroy cancerous tissues located deep within the body.

"Medical procedures such as hyperthermia therapy seek to act on human tissues by locally increasing the temperature. This is often done by focusing high-energy acoustic signals onto a small area, requiring significant control of the focal region" so that healthy tissue is not also heated and damaged, Daraio explains. "Our lens produces a very compact focal region which could aid further development of hyperthermia techniques."

Furthermore, sound bullets could offer a nondestructive way to probe and analyze the interior of nontransparent objects like bridges, ship hulls, and airplane wings, looking for cracks or other defects.

"Today the performance of acoustic devices is decreased by their linear operational range, which limits the accuracy of the focusing and the amplitude achievable at the focal point," Daraio says. "The new nonlinear acoustic lens proposed with this work leverages nonlinear effects to generate compact acoustic pulses with energies much higher than are currently achievable, with the added benefit of providing great control of the focal position."

(Photo: Spadoni & Daraio/Caltech)

California Institute of Technology

HOW RED WINE MAY SHIELD BRAIN FROM STROKE DAMAGE

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Researchers at Johns Hopkins say they have discovered the way in which red wine consumption may protect the brain from damage following a stroke.

Two hours after feeding mice a single modest dose of resveratrol, a compound found in the skins and seeds of red grapes, the scientists induced an ischemic stroke by essentially cutting off blood supply to the animals' brains. They found that the animals that had preventively ingested the resveratrol suffered significantly less brain damage than the ones that had not been given the compound.

Sylvain Doré, Ph.D., an associate professor of anesthesiology and critical care medicine and pharmacology and molecular sciences at the Johns Hopkins University School of Medicine, says his study suggests that resveratrol increases levels of an enzyme (heme oxygenase) already known to shield nerve cells in the brain from damage. When the stroke hits, the brain is ready to protect itself because of elevated enzyme levels. In mice that lacked the enzyme, the study found, resveratrol had no significant protective effect and their brain cells died after a stroke.

"Our study adds to evidence that resveratrol can potentially build brain resistance to ischemic stroke," says Doré, the leader of the study, which appears online in the journal Experimental Neurology.

Red wine has gotten a lot of attention lately for its purported health benefits. Along with reducing stroke, moderate wine consumption has been linked to a lowered incidence of cardiovascular disease — the so-called French paradox. Despite diets high in butter, cheese and other saturated fats, the paradox goes, the French have a relatively low incidence of cardiovascular events, which some have attributed to the regular drinking of red wine.

Doré cautions against taking resveratrol supplements, available alongside vitamins and minerals and on websites touting its benefits, because it is unclear whether such supplements could do harm or good. He has not tested resveratrol in clinical trials. And while resveratrol is found in red grapes, it's the alcohol in the wine that may be needed to concentrate the amounts of the beneficial compound. Doré also cautions that drinking alcohol carries risks along with potential benefits.

He also notes that even if further research affirms the benefits of red wine, no one yet knows how much would be optimal to protect the brain, or even what kind of red wine might be best, because not all types contain the same amount of resveratrol. More research is needed, he says.

Doré says his research suggests that the amount needed could end up being quite small because the suspected beneficial mechanism is indirect. "Resveratrol itself may not be shielding brain cells from free radical damage directly, but instead, resveratrol, and its metabolites, may be prompting the cells to defend themselves," he suggests.

"It's not likely that brain cells can have high enough local levels of resveratrol to be protective," he says. The resveratrol is needed to jump-start this protective enzymatic system that is already present within the cells. "Even a small amount may be sufficient," Doré says.

Doré says his ongoing research also suggests some therapeutic benefits to giving resveratrol to mice after a stroke to limit further neuronal damage.

Johns Hopkins Medicine

ANCESTRAL EVE' CRYSTAL MAY EXPLAIN ORIGIN OF LIFE'S LEFT-HANDEDNESS

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Scientists are reporting discovery of what may be the "ancestral Eve" crystal that billions of years ago gave life on Earth its curious and exclusive preference for so-called left-handed amino acids. Those building blocks of proteins come in two forms — left- and right-handed — that mirror each other like a pair of hands. Their study, which may help resolve one of the most perplexing mysteries about the origin of life, is in ACS' Crystal Growth & Design, a bi-monthly journal.

Tu Lee and Yu Kun Lin point out that conditions on the primordial Earth held an equal chance of forming the same amounts of left-handed and right-handed amino acids. Nevertheless, when the first forms of life emerged more than 3 billion years ago, all the amino acids in the proteins had the left-handed configuration. That pattern continued right up to modern plants and animals.

The scientists used mixtures of both left- and right-handed aspartic acid (an amino acid) in laboratory experiments to see how temperature and other conditions affected formation of crystals of the material. They found that under conditions that could have existed on primitive Earth, left-handed aspartic acid crystals could have formed easily and on a large scale. "The aspartic acid crystal would then truly become a single mother crystal: an ancestral Eve for the whole left-handed population," the article notes.

(Photo: American Chemical Society)

American Chemical Society

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