Saturday, August 15, 2009

CNRS

A recent study on human genetics on various populations across the world conducted by researchers from the Institut Pasteur and the CNRS has shown how pathogens can shape the patterns of genetic diversity of our immune system over time. Results show that bacteria, fungi and parasites, unlike viruses, appear to have allowed the introduction of mutations in the genes of some proteins of the innate immunity system, thus enabling greater genetic variability. In some cases, these mutations may even constitute an advantage, giving the human host improved resistance to infectious diseases such as leprosy or tuberculosis.

"If both sighted people and people with blindness process the same ideas in the same parts of the brain, then it follows that visual experience is not necessary in order for those aspects of brain organization to develop," says Bradford Mahon, postdoctoral fellow in the Department of Brain and Cognitive Sciences at the University of Rochester, and lead author of the study. "We think this means significant parts of the brain are innately structured around a few domains of knowledge that were critical in humans' evolutionary history."





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Am vazut multe ceasuri superbe www.TOPCeas.ro
Am vazut multe ceasuri superbe www.TOPCeas.ro

World Record In Packing Puzzle

Finding the best way to pack the greatest quantity of a specifically shaped object into a confined space may sound simple, yet it consistently has led to deep mathematical concepts and practical applications, such as improved computer security codes.

One option is that the cloud cools, gravity gets the upper hand, and the cloud falls in on itself. The other possibility is that a "trigger" from some external source -- like radiation from a massive star or a shock from a supernova -- initiates the collapse. Some previous studies have noted a combination of triggering mechanisms in effect.+

While slightly farther away than the famous Orion star-forming region, Cepheus B is at a better orientation for astronomers to observe the triggering process. The Chandra observations allowed the astronomers to pick out young stars within and around Cepheus B. Young stars have turbulent interiors that generate highly active magnetic fields, which, in turn, produce strong and identifiable X-ray signatures.



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Am vazut multe ceasuri superbe www.TOPCeas.ro

Friday, August 14, 2009

extended

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Am vazut multe ceasuri superbe www.TOPCeas.ro


In the current study, the team identified a small extended family in which a mother and her adult daughter had life-long shorter daily sleep requirements than most individuals. Fu's lab then studied blood samples from these women and their extended family. They identified a mutation in a gene known as hDEC2, which is a transcription factor that represses expression of certain other genes and is implicated in the regulation of circadian rhythms.

phenomenon

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Am vazut multe ceasuri superbe www.TOPCeas.ro

Sleep remains a relatively inscrutable biological phenomenon. Scientists know that it is regulated in large part by two processes: 1) circadian rhythms -- genetic, biochemical and physiological mechanisms that wax and wane during a 24 hour period to regulate the timing of sleep, 2) and homeostasis – unknown mechanisms that ensure that the body acquires over time the necessary amount of sleep, nudging it toward sleep when it has been deprived, prompting it out of sleep when it has received enough. This regulation of sleep intensity is measured in non rapid eye movement sleep and REM sleep. Interactions between the circadian rhythms and homeostatic mechanisms influence the timing, duration and quality of sleep and wakefulness.

Pinnacle Point

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"In numerous field surveys with co-author David Roberts, who is a leading expert on silcrete formation, we were unable to locate stone outcrops with material that matched the fine-grained texture and often reddish color of the silcrete artifacts we excavated at Pinnacle Point," Brown says. "The silcrete we had collected was just not suitable for tool production."

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Calvaneo 1583 Squelette Gold arata neobisnuit, seamana cu ceva organi i-ti atrage imediat privirea, nu am mai vazut asa ceva este uimitor ca un ceas de tipul acesta costa asa putin. Este o piesa de arta chiar Am vazut multe ceasuri superbe pe www.topceas.ro
Evidence reported in the Aug. 14 issue of the journal Science shows that early humans living on the southern coast of Africa 72,000 years ago used a complex heat treatment process to manufacture blades and bifacial tools. Unheated silcrete (left) can show dramatic changes in color and texture after heating and flaking (right). An international team, including three researchers from the Institute of Human Origins at Arizona State University, note that silcrete is not found closer than 5 kilometers from their excavation at Pinnacle Point, Mossel Bay, South Africa, and that most pieces found are extensively flaked. (Photo by Kyle Brown/South African Coast Paleoclimate, Paleoenvironment, Paleoecology, Paleoanthropology Project)Am vazut multe ceasuri superbe www.topceas.roAm vazut multe ceasuri superbe www.topceas.ro

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