Τετάρτη, 2 Ιουλίου 2014

ScienceDaily: Most Popular News

ScienceDaily: Most Popular News


Ancient baby boom holds a lesson in over-population

Posted: 30 Jun 2014 01:41 PM PDT

Researchers have sketched out one of the greatest baby booms in North American history, a centuries-long 'growth blip' among southwestern Native Americans between 500 to 1300 A.D. It was a time when the early features of civilization -- including farming and food storage -- had matured to where birth rates likely 'exceeded the highest in the world today,' the researchers write. A crash followed, offering a warning sign to the modern world about the dangers of overpopulation.

In human evolution, changes in skin's barrier set northern Europeans apart

Posted: 30 Jun 2014 11:08 AM PDT

The popular idea that northern Europeans developed light skin to absorb more UV light so they could make more vitamin D -- vital for healthy bones and immune function -- is questioned by researchers in a new study. Ramping up the skin's capacity to capture UV light to make vitamin D is indeed important, however, researchers concluded in their study that changes in the skin's function as a barrier to the elements made a greater contribution than alterations in skin pigment in the ability of northern Europeans to make vitamin D.

Potentially habitable Earth-like planet discovered; May have similar temperatures to our planet

Posted: 30 Jun 2014 10:34 AM PDT

A potentially habitable Earth-like planet that is only 16 light years away has been discovered. The "super-Earth" planet, GJ 832 c, takes 16 days to orbit its red-dwarf star, GJ 832, and has a mass at least five times that of Earth. It receives about the same average stellar energy as Earth does and may have similar temperatures to our planet. These characteristics put it among the top three most Earth-like planets.

Noninvasive brain control: New light-sensitive protein enables simpler, more powerful optogenetics

Posted: 29 Jun 2014 11:21 AM PDT

Engineers have now developed the first light-sensitive molecule that enables neurons to be silenced noninvasively, using a light source outside the skull. This noninvasive approach could pave the way to using optogenetics in human patients to treat epilepsy and other neurological disorders.

Herpes virus infection drives HIV infection among non-injecting drug users in New York

Posted: 27 Jun 2014 01:37 PM PDT

HIV infection among non-injecting drug users doubled over the last two decades, a study has found. HIV and its transmission has long been associated with injecting drug use, where hypodermic syringes are used to administer illicit drugs. Now, a newly reported study shows that HIV infection among heterosexual non-injecting drug users (no hypodermic syringe is used; drugs are taken orally or nasally) in New York City has now surpassed HIV infection among persons who inject drugs.

Monkeys also believe in winning streaks, study shows

Posted: 27 Jun 2014 10:31 AM PDT

Humans have a well-documented tendency to see winning and losing streaks in situations that, in fact, are random. But scientists disagree about whether the "hot-hand bias" is a cultural artifact picked up in childhood or a predisposition deeply ingrained in the structure of our cognitive architecture.

The secrets of children's chatter: research shows boys and girls learn language differently

Posted: 27 Jun 2014 06:45 AM PDT

Experts believe language uses both a mental dictionary and a mental grammar.  The mental 'dictionary' stores sounds, words and common phrases, while mental 'grammar' involves the real-time composition of longer words and sentences. For example, making a longer word 'walked' from a smaller one 'walk'.

Ultra-stiff and lightweight: Carbon-fiber epoxy honeycombs mimic material performance of balsa wood

Posted: 25 Jun 2014 12:15 PM PDT

For centuries, the fast-growing balsa tree has been prized for its light weight and stiffness relative to density. But balsa wood is expensive and natural variations in the grain can be an impediment to achieving the increasingly precise performance requirements of turbine blades and other sophisticated applications. Materials scientists have now developed cellular composite materials of unprecedented light weight and stiffness.

Curiosity travels through ancient glaciers on Mars

Posted: 25 Jun 2014 07:15 AM PDT

Some 3,500 million years ago, the Martian crater Gale -- through which the NASA rover Curiosity is currently traversing -- was covered with glaciers, mainly over its central mound. Very cold liquid water also flowed through its rivers and lakes on the lower-lying areas, forming landscapes similar to those which can be found in Iceland or Alaska.

Clumped galaxies give General Relativity its toughest test yet

Posted: 24 Jun 2014 06:59 PM PDT

Nearly 100 years since Albert Einstein developed General Relativity, the theory has passed its toughest test yet in explaining the properties of observable Universe.  The most precise measurements to date of the strength of gravitational interactions between distant galaxies show perfect consistency with General Relativity's predictions.

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