Friday, October 1, 2010

THE BIGGEST CRASH ON EARTH

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During the collision of India with the Eurasian continent, the Indian plate is pushed about 500 kilometers under Tibet, reaching a depth of 250 kilometers. The result of this largest collision in the world is the world's highest mountain range, but the tsunami in the Indian Ocean from 2004 was also created by earthquakes generated by this collision.

The clash of the two continents is very complex, the Indian plate, for example, is compressed where it collides with the very rigid plate of the Tarim Basin at the north-western edge of Tibet. On the eastern edge of Tibet, the Wenchuan earthquake in May 2008 claimed over 70,000 deaths. Scientists at the GFZ German Research Center for Geosciences report in the latest issue of the scientific journal "Science" (vol. 329, Sept. 17, 2010) on the results of a new seismic method which was used to investigate the collision process.

In international cooperation, it was possible to follow the route of the approximately 100 kilometers thick Indian continental plate beneath Tibet. To achieve this, a series of large seismic experiments were carried out in Tibet, during which the naturally occurring earthquakes were recorded. By evaluating weak waves that were scattered at the lower edge of the continental plate, this edge was made visible in detail. The boundary between the rigid lithosphere and the softer asthenosphere proved to be much more pronounced than was previously believed.

The entire Indian sub-continent moves continuously north over millions of years and has moved 2 meters below Tibet in the last 50 years alone. The Himalayas and the highlands of Tibet, the highest and largest plateau in the world, were formed this way. But the recurring catastrophic earthquakes in China are also caused by this collision of two continents. For a better understanding of the processes involved in the collision of the two plates, it is hoped to ultimately reduce the earthquake risk to millions of people across the entire collision zone.

Helmholtz Association

A CHIP OFF THE EARLY HOMININ TOOTH

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Were our early mammalian ancestors vegetarians, vegans or omnivores? It's difficult for anthropologists to determine the diet of early mammalians because current fossil analysis provides too little information. But a new method that measures the size of chips in tooth fossils can help determine the kinds of foods these early humans consumed.

Prof. Herzl Chai of Tel Aviv University's School of Mechanical Engineering, in collaboration with scientists from George Washington University and the U.S. National Institute of Standards and Technology (NIST), has developed an equation for determining how the size of a chip found in the enamel of a tooth relates to the bite force needed to produce the chip. With the aid of this information, researchers can better determine the type of food that animals, and early humans, could have consumed during their lifetimes.

Teeth are the only relevant fossils with staying power, Prof. Chai explains. Made of hard, mineralized material, teeth from animals that are thousands of years old remain relatively intact. Teeth that display a greater number of large chips indicate that animals like our early ancestors were consuming harder foods such as nuts, seeds or items with bones. A lesser amount of small chips demonstrates that the animal’s diet more likely consisted of softer foods, such as vegetation. Dr. Chai's findings were recently reported in the journal Biology Letters.

In the recent study, Prof. Chai combined his mechanical engineering background with the expertise of anthropologists at George Washington University and material scientists at NIST to develop a simple equation to predict the maximum bite force used to create a tooth chip. The equation correlates well with a commonly-used equation from jaw mechanics — a more complex approach for determining the maximum bite force an animal can deliver.

Drawn from "fracture mechanics," concerned with the formation of cracks in brittle materials, Prof. Chai's equation takes into account the dimensions of the chip — its distance from the edge of the tooth — and from there solves for the bite force required to have made the chip. The maximum force an animal can apply, notes Prof. Chai, relates to the thickness of the enamel and the size of the tooth itself.

"The bigger the tooth, the bigger area for chips to develop, and therefore, the more force the animal can produce," he says. The team surveyed tooth fossils from many types of mammalians, including six hominins, gorillas and chimpanzees.

A tooth chip is a permanent signature of consumption, says Prof. Chai. His method demonstrates that the probable food sources of a given animal can be determined from a small number of well-preserved teeth. The fossils used for this particular study were widely available at museums. This is an improvement over previous methods, which relied solely on jaw mechanics and required an almost complete skull to determine eating habits.

This moves researchers one step closer towards grasping the dietary habits of early mammalians. Although the study of tooth chips cannot, thus far, reveal exactly what food produced the chip, it allows researchers to determine a range of foods, providing valuable information about the animal's life that other methods tend to miss.

(Photo: TAU)

Tel Aviv University

WHEN THE EARTH MANTLE FINDS ITS CORE

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The Earth's mantle and its core mix at a distance of 2900 km under our feet in a mysterious zone. A team of geophysicists has just verified that the partial fusion of the mantle is possible in this area when the temperature reaches 4200 Kelvin. This reinforces the hypothesis of the presence of a deep magma ocean.

The originality of this work, carried out by the scientists of the Institut de minéralogie et de physique des milieux condensés (UPMC/Université Paris Diderot/Institut de Physique du Globe/CNRS/IRD), lies in the use of X-ray diffraction at the European Synchrotron Radiation Facility in Grenoble (France). The results will have an effect in the understanding of the dynamics, composition and the formation of the depths of our planet.

On top of the core of the Earth, constituted of liquid iron, lies the solid mantle, which is made up essentially of magnesium oxides, iron and silicon. The border between the core and the mantle, located at 2900 km under our feet, is highly intriguing to geophysicists. With a pressure of around 1.4 million times the atmospheric pressure and a temperature of more than 4000 Kelvin, this zone is the home to chemical reactions and changes in states of matter still unknown. The seismologists who have studied this subject have acknowledged an abrupt reduction of the speed of the seismic waves, which sometimes reach 30% when getting close to this border. This fact has led scientists to formulate the hypothesis, for the last 15 years, of the partial melting of the Earth mantle at the level of this mantle-core border. Today it has been confirmed.

In order to access the depths of the Earth, scientists have not only seismological images but also a precious experimental technique: diamond anvil cells, coupled with a heating layer. This instrument allows to re-create the same pressure and temperature condition than those in the interior of the Earth, on samples of a few microns. This is the technique used by the researchers of the Institut de minéralogie et de physique des milieux condensés on natural samples that are representatives of the Earth mantle and that have been put under pressures of more than 140 gigapascals (or 1.4 million times the atmospheric pressure), and temperatures of more than 5000 Kelvin.

A new approach to this study has been the use of the X-ray diffraction technique at the European synchrotron ESRF. This has allowed the scientists to determine what mineral phases melt first, and they have also established, without extrapolation, fusion curves of the deep Earth mantle, i.e. the characterization of the passage from a solid state to a partially liquid state. Their observations show that the partial fusion of the mantle is possible when the temperature approaches 4200 Kelvin. These experiments also prove that the liquid produced during this partial fusion is dense and that it can hold multiple chemical elements, among which are important markers of the dynamics of the Earth mantle. These studies will allow geophysicists and geochemists to achieve a deeper knowledge of the mechanisms of differentiation of the Earth and the history of its formation, which started around 4.5 billion years ago.

(Photo: G.Fiquet)

ESRF

AMAZING HORNED DINOSAURS UNEARTHED ON 'LOST CONTINENT'

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Two remarkable new species of horned dinosaurs have been found in Grand Staircase-Escalante National Monument, southern Utah. The giant plant-eaters were inhabitants of the "lost continent" of Laramidia, formed when a shallow sea flooded the central region of North America, isolating the eastern and western portions of the continent for millions of years during the Late Cretaceous Period. The newly discovered dinosaurs, close relatives of the famous Triceratops, were announced today in PLoS ONE, the online open-access journal produced by the Public Library of Science.

The study, funded in large part by the Bureau of Land Management and the National Science Foundation, was led by Scott Sampson and Mark Loewen of the Utah Museum of Natural History (UMNH) and Department of Geology and Geophysics, University of Utah. Additional authors include Andrew Farke (Raymond Alf Museum), Eric Roberts (James Cook University), Joshua Smith (University of Utah), Catherine Forster (George Washington University), and Alan Titus (Grand Staircase-Escalante National Monument).

The bigger of the two new dinosaurs, with a skull 2.3 meters (about 7 feet) long, is Utahceratops gettyi (U-tah-SARA-tops get-EE-i). The first part of the name combines the state of origin with ceratops, Greek for "horned face." The second part of the name honors Mike Getty, paleontology collections manager at the Utah Museum of Natural History and the discoverer of this animal. In addition to a large horn over the nose, Utahceratops has short and blunt eye horns that project strongly to the side rather than upward, much more like the horns of modern bison than those of Triceratops or other ceratopsians. Mark Loewen, one of the authors on the paper, likened Utahceratops to "a giant rhino with a ridiculously supersized head."

Second of the new species is Kosmoceratops richardsoni (KOZ-mo-SARA-tops RICH-ard-SON-i). Here, the first part of the name refers to kosmos, Latin for "ornate," and ceratops, once again meaning "horned face." The latter part of the name honors Scott Richardson, the volunteer who discovered two skulls of this animal. Kosmoceratops also has sideways oriented eye horns, although much longer and more pointed than in Utahceratops. In all, Kosmoceratops possesses a total of 15 horns—one over the nose, one atop each eye, one at the tip of each cheek bone, and ten across the rear margin of the bony frill—making it the most ornate-headed dinosaur known. Scott Sampson, the paper's lead author, claimed that, "Kosmoceratops is one of the most amazing animals known, with a huge skull decorated with an assortment of bony bells and whistles."

Although much speculation has ensued about the function of ceratopsian horns and frills—from fighting off predators to recognizing other members of the same species or controlling body temperature—the dominant idea today is that these features functioned first and foremost to enhance reproductive success. Sampson added, "Most of these bizarre features would have made lousy weapons to fend off predators. It's far more likely that they were used to intimidate or do battle with rivals of the same sex, as well as to attract individuals of the opposite sex."

The dinosaurs were discovered in Grand Staircase-Escalante National Monument (GSENM), which encompasses 1.9 million acres of high desert terrain in south-central Utah. This vast and rugged region, part of the National Landscape Conservation System administered by the Bureau of Land Management, was the last major area in the lower 48 states to be formally mapped by cartographers. Today GSENM is the largest national monument in the United States. Sampson added that, "Grand Staircase-Escalante National Monument is now one of the country's last great, largely unexplored dinosaur boneyards."

For most of the Late Cretaceous, exceptionally high sea levels flooded the low-lying portions of several continents around the world. In North America, a warm, shallow sea called the Western Interior Seaway extended from the Arctic Ocean to the Gulf of Mexico, subdividing the continent into eastern and western landmasses, known as Appalachia and Laramidia, respectively. Whereas little is known of the plants and animals that lived on Appalachia, the rocks of Laramidia exposed in the Western Interior of North America have generated a plethora of dinosaur remains. Laramidia was less than one-third the size of present day North America, approximating the area of Australia.

Most known Laramidian dinosaurs were concentrated in a narrow belt of plains sandwiched between the seaway to the east and mountains to the west. Today, thanks to an abundant fossil record and more than a century of collecting by paleontologists, Laramidia is the best known major landmass for the entire Age of Dinosaurs, with dig sites spanning from Alaska to Mexico. Utah was located in the southern part of Laramidia, which has yielded far fewer dinosaur remains than the fossil-rich north. The world of dinosaurs was much warmer than the present day; Utahceratops and Kosmoceratops lived in a subtropical swampy environment about 100 km from the seaway.

Beginning in the 1960's, paleontologists began to notice that the same major groups of dinosaurs seemed to be present all over this Late Cretaceous landmass, but different species of these groups occurred in the north (for example, Alberta and Montana) than in the south (New Mexico and Texas). This finding of "dinosaur provincialism" was very puzzling, given the giant body sizes of many of the dinosaurs together with the diminutive dimensions of Laramidia. Currently, there are five giant (rhino-to-elephant-sized) mammals on the entire continent of Africa. Seventy-six million years ago, there may have been more than two dozen giant dinosaurs living on a landmass about one-quarter that size. Mark Loewen asks, "How could so many different varieties of giant animals have co-existed on such a small chunk of real estate?" One option is that there was a greater abundance of food during the Cretaceous. Another is that dinosaurs did not need to eat as much, perhaps because of slower metabolic rates more akin to those of modern day lizards and crocodiles than to those of mammals and birds. Whatever the factors permitting the presence of so many dinosaurs, it appears that some kind of barrier near the latitude of northern Utah and Colorado limited the exchange of dinosaur species north and south. Possibilities include physical barriers such as mountains, or climatic barriers that resulted in distinct northern and southern plant communities. Testing of these ideas has been severely hampered by a dearth of dinosaurs from the southern part of Laramidia. The new fossils from GSENM are now filling that major gap.

During the past decade, crews from the University of Utah and several partner institutions (e.g., the Utah Geologic Survey, the Raymond Alf Museum of Paleontology, and the Bureau of Land Management) have unearthed a new assemblage of more than a dozen dinosaurs in GSENM. In addition to Utahceratops and Kosmoceratops, the collection includes a variety of other plant-eating dinosaurs—among them duck-billed hadrosaurs, armored ankylosaurs, and dome-headed pachycephalosaurs—together with carnivorous dinosaurs great and small, from "raptor-like" predators to mega-sized tyrannosaurs (not T. rex but rather its smaller-bodied relatives). Also recovered have been fossil plants, insect traces, clams, fishes, amphibians, lizards, turtles, crocodiles, and mammals, offering a direct glimpse into this entire ancient ecosystem. Most remarkable of all is that virtually every identifiable dinosaur variety found in GSENM turns out to be new to science, offering dramatic confirmation of the dinosaur provincialism hypothesis. Many of these animals are still under study, but two have been previously named: the giant duck-billed hadrosaur Gryposaurus monumentensis and the raptor-like theropod Hagryphus giganteus.

Utahceratops and Kosmoceratops are part of a recent spate of ceratopsian dinosaur discoveries. Andrew Farke, another of the paper's authors, stated, "The past year has been a remarkable one for horned dinosaurs, with several new species named. The new Utah creatures are the icing on the cake, showing anatomy even more bizarre than typically expected for a group of animals known for its weird skulls."

Clearly many more dinosaurs remain to be unearthed in southern Utah. "It's an exciting time to be a paleontologist," Sampson added. "With many new dinosaurs still discovered each year, we can be quite certain that plenty of surprises still await us out there."

(Photo: Utah Museum of Natural History)

University of Utah

BRAIN CELL COMMUNICATION: WHY IT'S SO FAST

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Billions of brain cells are communicating at any given moment. Like an organic supercomputer they keep everything going, from breathing to solving riddles, and "programming errors" can lead to serious conditions such as schizophrenia, Parkinson's Disease and Attention-Deficit Hyperactivity Disorder.

Nowadays the biochemical language of the nerve cells is the subject of intensive research right down at the molecular level, and for the first time researchers, some from the University of Copenhagen, have described just how nerve cells are capable of transmitting signals practically simultaneously.

The cells of the nervous system communicate using small molecule neurotransmitters such as dopamine, serotonin and noradrenalin. Dopamine is associated with cognitive functions such as memory, serotonin with mood control, and noradrenaline with attention and arousal.

The brain cell communication network, the synapses, transmit messages via chemical neurotransmitters packaged in small containers (vesicles) waiting at the nerve ends of the synapses. An electrical signal causes the containers and membrane to fuse and the neurotransmitters flow from the nerve ending to be captured by other nerve cells. This occurs with immense rapidity in a faction of a millisecond.

Researchers from the Universities of Copenhagen, Göttingen and Amsterdam have been studying the complex organic protein complexes that link vesicles and membrane prior to fusion, in order to find an explanation for the rapidity of these transmissions. They have discovered that the vesicle contains no fewer than three copies of the linking bridge or "SNARE complex".

With only one SNARE complex the vesicle takes longer to fuse with the membrane and the neurotransmitter is therefore secreted more slowly.

- The precursors for the SNARE complexes are present in the vesicles before they reach the target membrane", Professor Jakob Balsev Sørensen from the Department of Neuroscience and Pharmacology at the University of Copenhagen. "Fast (synchronous) fusion is enabled when at least three of them work in tandem. If the vesicle only has one SNARE complex it can still fuse with the target membrane, but it takes much longer."

The discovery has just been published in Science, the leading journal of scientific research and commentary.

- Our next step will be to investigate the factors that influence and regulate the number of SNARE complexes in the vesicles. Is this a way for the nerve cells to choose to communicate more or less rapidly, and is this regulation altered when the brain is diseased?, professor Sørensen says.

(Photo: U. Copenhagen)

University of Copenhagen

INNER VOICE PLAYS ROLE IN SELF-CONTROL

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Talking to yourself might not be a bad thing, especially when it comes to exercising self control.

New research out of the University of Toronto Scarborough – published in this month's edition of Acta Psychologica – shows that using your inner voice plays an important role in controlling impulsive behaviour.

"We give ourselves messages all the time with the intent of controlling ourselves – whether that's telling ourselves to keep running when we're tired, to stop eating even though we want one more slice of cake, or to refrain from blowing up on someone in an argument," says Alexa Tullett, PhD Candidate and lead author on the study. "We wanted to find out whether talking to ourselves in this 'inner voice' actually helps."

Tullett and Associate Psychology Professor Michael Inzlicht, both at UTSC, performed a series of self control tests on participants. In one example, participants performed a test on a computer. If they saw a particular symbol appear on the screen, they were told to press a button. If they saw a different symbol, they were told to refrain from pushing the button. The test measures self control because there are more "press" than "don't press" trials, making pressing the button an impulsive response.

The team then included measures to block participants from using their "inner voice" while performing the test, to see if it had an impact on their ability to perform. In order to block their "inner voice," participants were told to repeat one word over and over as they performed the test. This prevented them from talking to themselves while doing the test.

"Through a series of tests, we found that people acted more impulsively when they couldn't use their inner voice or talk themselves through the tasks," says Inzlicht. "Without being able to verbalize messages to themselves, they were not able to exercise the same amount of self control as when they could talk themselves through the process."

"It's always been known that people have internal dialogues with themselves, but until now, we've never known what an important function they serve," says Tullett. "This study shows that talking to ourselves in this 'inner voice' actually helps us exercise self control and prevents us from making impulsive decisions."

University of Toronto

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