Παρασκευή, 25 Απριλίου 2014

ScienceDaily: Most Popular News

ScienceDaily: Most Popular News


Male or female? First sex-determining genes appeared in mammals some 180 million years ago

Posted: 23 Apr 2014 12:10 PM PDT

The Y chromosome, which distinguishes males from females at the genetic level, appeared some 180 million years ago. It originated twice independently in all mammals. Scientists have managed to date these events that are crucial for both mammalian evolution and our lives, because the Y chromosome determines whether we are born as a boy or girl.

Scientists identify source of mysterious sound in the Southern Ocean

Posted: 23 Apr 2014 10:26 AM PDT

Scientists have conclusive evidence that the source of a unique rhythmic sound, recorded for decades in the Southern Ocean and called the 'bio-duck,' is the Antarctic minke whale (Balaenoptera bonaerensis). First described and named by submarine personnel in the 1960s who thought it sounded like a duck, the bio-duck sound has been recorded at various locations in the Southern Ocean, but its source has remained a mystery, until now.

Liquid spacetime: What if spacetime were a kind of fluid?

Posted: 23 Apr 2014 06:52 AM PDT

What if spacetime were a kind of fluid? This is the question tackled by theoretical physicists working on quantum gravity by creating models attempting to reconcile gravity and quantum mechanics. Some of these models predict that spacetime at the Planck scale is no longer continuous – as held by classical physics – but discrete in nature. Just like the solids or fluids we come into contact with every day, which can be seen as made up of atoms and molecules when observed at sufficient resolution. A structure of this kind generally implies, at very high energies, violations of Einstein's special relativity (a integral part of general relativity).

Brain circuits involved in emotion discovered by neuroscientists

Posted: 22 Apr 2014 05:23 PM PDT

A brain pathway that underlies the emotional behaviors critical for survival have been discovered by neuroscientists. The team has identified a chain of neural connections which links central survival circuits to the spinal cord, causing the body to freeze when experiencing fear. Understanding how these central neural pathways work is a fundamental step towards developing effective treatments for emotional disorders such as anxiety, panic attacks and phobias.

Male health linked to testosterone exposure in womb, study finds

Posted: 22 Apr 2014 08:34 AM PDT

Men's susceptibility to serious health conditions may be influenced by low exposure to testosterone in the womb, new research suggests. Understanding why some men have less of the hormone than others is important because testosterone is crucial for life-long health. Low levels of the hormone have been linked to obesity, diabetes and heart disease.

Brain size matters when it comes to animal self-control

Posted: 22 Apr 2014 08:34 AM PDT

Chimpanzees may throw tantrums like toddlers, but their total brain size suggests they have more self-control than, say, a gerbil or fox squirrel, according to a new study of 36 species of mammals and birds ranging from orangutans to zebra finches.

Cloaked DNA nanodevices survive pilot mission

Posted: 22 Apr 2014 07:00 AM PDT

By mimicking a viral strategy, scientists have created the first cloaked DNA nanodevice that survives the body's immune defenses. Their success opens the door to smart DNA nanorobots that use logic to spot cancerous tissue and manufacture drugs on the spot to cripple it, as well as artificial microscopic containers called protocells that detect pathogens in food or toxic chemicals in drinking water.

Solved: Mysteries of a nearby planetary system

Posted: 22 Apr 2014 05:46 AM PDT

Mysteries of one of the most fascinating nearby planetary systems now have been solved. A new study presents the first viable model for the planetary system orbiting one the first stars discovered to have planets - the star named 55 Cancri. Numerous studies since 2002 had failed to determine a plausible model for the masses and orbits of two giant planets located closer to 55 Cancri than Mercury is to our Sun. Astronomers had struggled to understand how these massive planets orbiting so close to their star could avoid a catastrophe such as one planet being flung into the star, or the two planets colliding with each other.

Sleep behavior disorder linked to brain disease

Posted: 22 Apr 2014 05:45 AM PDT

A sleep disorder that causes people to act out their dreams is the best current predictor of brain diseases like Parkinson's and Alzheimer's, research suggests. In this disorder, the disturbance occurs during the rapid-eye-movement (REM) stage of sleep and causes people to act out their dreams, often resulting in injury to themselves and/or bed partner. In healthy brains, muscles are temporarily paralyzed during sleep to prevent this from happening.

Sleeping away infection: Researchers find link between sleep, immune function in fruitflies

Posted: 21 Apr 2014 06:13 PM PDT

When we get sick it feels natural to try to hasten our recovery by getting some extra shuteye. Researchers found that this response has a definite purpose, in fruitflies: enhancing immune system response and recovery to infection. "These studies provide new evidence of the direct and functional effects of sleep on immune response and of the underlying mechanisms at work. The take-home message from these papers is that when you get sick, you should sleep as much as you can -- we now have the data that supports this idea," researchers conclude.

Collider reveals sharp change from 'quark soup' to atoms

Posted: 18 Apr 2014 11:07 AM PDT

Scientists using the atom smasher at the U.S. Department of Energy's Brookhaven National Laboratory have observed a phase transition different than the smooth transition of the early universe from the hot "soup" of subatomic particles to the atoms, made up of neutrons, protons and electrons that are the building blocks of matter.

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