Friday, October 16, 2009

BIZARRE NEW HORNED TYRANNOSAUR FROM ASIA DESCRIBED

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Now, just a few weeks after tiny, early Raptorex kriegsteini was unveiled, a new wrench has been thrown into the family tree of the tyrannosaurs. The new Alioramus altai—a horned, long-snouted, gracile cousin of Tyrannosaurus rex—shared the same environment with larger, predatory relatives. A paper published in the Proceedings of the National Academy of Sciences describes this exceptionally well-preserved fossil, shedding light on a previously poorly understood genus of tyrannosaurs and describing a new suite of adaptations for meat eating.

"This spectacular fossil tells us that there is a lot more anatomical and ecological variety in tyrannosaurs than we previously thought," says Stephen Brusatte, a graduate student affiliated with the American Museum of Natural History. "Not all tyrannosaurs were megapredators adapted for stalking and dismembering large prey. Some tyrannosaurs were small and slender. Compared to Tyrannosaurus, this new animal is like a ballerina."

Mark Norell, Chair of the Division of Paleontology at the Museum, agrees. "We now have evidence of two very different tyrannosaurs that lived in Asia at the same time and place—just like today, where lions and cheetahs live in the same area but look dissimilar and exploit their environment differently."

Tyrannosaurs are bipedal predators that lived at the end of the Cretaceous (from 85 million years to approximately 65 million years ago) is currently known from several groups of fossils. One subfamily from North America includes Albertosaurus and Gorgosaurus, while the other subfamily bridges Asia and North America and includes Tyranosaurus, Tarbosaurus, and Alioramus. Both T. rex and Tarbosaurus are remarkably similar, even though they lived on different continents; both were predators with massive jaws and thick teeth that could crunch through bones. In fact, bite marks have been found on some fossils that were prey. Until now, Alioramus was known only from fragmentary fossils that were briefly described decades ago by a Russian paleontologist, and it has long been debated whether Alioramus was a proper tyrannosaur, a more primitive cousin, or perhaps a juvenile Tarbosaurus.

The new specimen and species, A. altai, was found on a 2001 Museum expedition to the Gobi Desert of Mongolia led by Norell and Michael Novacek. In fact, it was found at the same site as a Tarbosaurus fossil. But although its skeleton is anatomically similar to this larger relative, A. altai is half the size; the reconstructed size is about 369 kilograms, or 810 pounds. It is the skull that is dramatically different from close relatives. Although this dinosaur was carnivorous, the teeth are slender, the skull has small and weak muscle attachments, and the skull has a long snout with eight horns that were probably about five inches in length, features never seen in a tyrannosaur before.

Analysis of the braincase, though, ties the new species closely to tyrannosaurs. CT scans of the brain by co-author Gabe Bever, also of the Museum, show the large air sacks, huge olfactory bulbs, and the small inner ear expected for a tyrannosaur. Another co-author, Gregory Erickson, of Florida State University, analyzed the microstructure of the bone to determine that this animal died as a nine year old, essentially a teenager at 85% of its adult size.

"This fossil reveals an entirely new body type among tyrannosaurs, a group we thought we understood pretty well," says Norell. "The different body forms probably allowed Alioramus and Tarbosaurus to coexist."

Brusatte agrees, "A. altai probably fed differently from its larger cousin, going for smaller prey because it could not crunch through bone like its larger relatives."

(Photo: Jason Brougham)

American Museum of National History

COLOR SENSORS FOR BETTER VISION

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The car of the future will have lots of smart assistants onboard – helping to park the car, recognize traffic signs and to warn the driver of blind spot hazards. Many driver assistance systems incorporate high-tech cameras which have to meet a wide range of requirements. They must be able to withstand high ambient temperatures and be particularly small, light and robust. What's more, they have to reliably capture all the required images and should cost as little as possible. Nowadays CMOS sensors are used for most in-car systems. These semiconductor chips convert light signals into electrical pulses and are installed in most digital cameras. At present, however, the sensors used for industrial and other special cameras are mostly color blind.

Now researchers at the Fraunhofer Institute for Microelectronic Circuits and Systems IMS in Duisburg are adding some color to the picture. They have developed a new process for producing CMOS image sensors which enables the chips to see color. Normally the image sensors are produced on silicon wafers using a semiconductor technique, the CMOS process. "We have integrated a color filter system in the process," explains Prof. Dr. Holger Vogt, Deputy Director of the IMS. "In the same way as the human eye needs color-specific cone types, color filters have to be inserted in front of the sensors so that they can distinguish color." This job is handled by polymers dyed in the primary colors red, green and blue. Each pixel on the sensor is coated with one of the three colors by a machine which coats the sensor disk propels with a micrometer-thick polymer layer. Using UV light and a mask which is only transparent on the desired pixels, the dye is fixed at the requisite points and the rest is then washed off. In addition, the researchers have developed special microlenses which help the sensor to capture and measure the light more efficiently. With the aid of a transparent polyimide they create a separate lens for each individual pixel, which almost doubles the light-sensitivity of the image sensor.

The optimized CMOS process not only makes it possible to cost-efficiently improve the performance of driver assistance systems. Endoscopes can also benefit from the new properties of CMOS image sensors.

(Photo: Fraunhofer IMS)

Fraunhofer Institute

WHERE RELIGIOUS BELIEF AND DISBELIEF MEET IN THE BRAIN

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While religious faith remains one of the most significant features of human life, little is known about its relationship to ordinary belief. Nor is it known whether religious believers differ from nonbelievers in how they evaluate statements of fact.

In the first neuroimaging study to systematically compare religious faith with ordinary cognition, UCLA and University of Southern California researchers have found that while the human brain responds very differently to religious and nonreligious propositions, the process of believing or disbelieving a statement, whether religious or not, seems to be governed by the same areas in the brain.

The study also found that devout Christians and nonbelievers use the same brain regions to judge the truth of religious and nonreligious propositions. The results, the study authors say, represent a critical advance in the psychology of religion. The paper appeared Sept. 30 in the journal PLoS ONE (http://www.plosone.org/).

Sam Harris, who recently completed his doctoral dissertation in the lab of Mark Cohen, a professor of psychiatry at the UCLA Staglin Center for Cognitive Neuroscience, was a lead author on the study. Jonas Kaplan, a research assistant professor at the USC's Brain and Creativity Institute, was the co-lead author.

The study involved 30 adults — 15 committed Christians and 15 nonbelievers — who underwent three functional MRI (fMRI) scans while evaluating religious and nonreligious statements as "true" or "false." The statements were designed to produce near perfect agreement between the two groups during nonreligious trials (e.g., "Eagles really exist") and near perfect disagreement during religious trials (e.g., "Angels really exist").

Contrasting belief and disbelief yielded increased activity in the ventromedial prefrontal cortex (VMPFC), an area of the brain thought to be involved in reward and in judgments of self-relevance.

"This region showed greater activity whether subjects believed statements about God, the Virgin Birth, etc., or statements about ordinary facts," the authors said.

The case for belief being content-independent was further bolstered by the fact that while the trial statements accepted by religious believers were rejected by nonbelievers, and vice versa, the brains of both showed the same pattern of activity for belief and disbelief.

A comparison of all religious with all nonreligious statements suggested that religious thinking is more associated with brain regions that govern emotion, self-representation and cognitive conflict in both believers and nonbelievers, while thinking about ordinary facts is more reliant upon memory retrieval networks. Activity in the brain's anterior cingulate cortex, an area associated with cognitive conflict and uncertainty, suggested that both believers and nonbelievers experienced greater uncertainty when evaluating religious statements.

The study raises the possibility that the differences between belief and disbelief may one day be reliably distinguished by neuroimaging techniques.

"Despite vast differences in the underlying processing responsible for religious and nonreligious modes of thought," the authors write, "the distinction between believing and disbelieving a proposition appears to transcend content. These results may have many areas of application — ranging from the neuropsychology of religion, to the use of 'belief-detection' as a surrogate for 'lie-detection,' to understanding how the practice of science itself, and truth-claims generally, emerge from the biology of the human brain."

UCLA

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