Water Doesn't Have to Freeze Until -55 F/ Study suggests

Regular ice crystals (red) are mixed with “intermediate ice” (green) near the end of the process of crystallizing from supercooled water. University of Utah chemists used computers to determine that water, which doesn’t necessarily become solid at its 32 degrees Fahrenheit freezing point, actually can get as cold as minus 55 F before it must freeze. (Credit: University of Utah)

University of Utah chemists may have solved one enigma by showing how cold water can get before it absolutely must freeze: 55 degrees below zero Fahrenheit.
That's 87 degrees Fahrenheit colder than what most people consider the freezing point of water, namely, 32 F.
Supercooled liquid water must become ice at minus 55 F not just because of the extreme cold, but because the molecular structure of water changes physically to form tetrahedron shapes, with each water molecule loosely bonded to four others, according to the new study by chemists Valeria Molinero and Emily Moore.

The findings suggest this structural change from liquid to "intermediate ice" explains the mystery of "what determines the temperature at which water is going to freeze," says Molinero, an assistant professor at the University of Utah and senior author of the study, published in the Nov. 24 issue of the journal Nature.
"This intermediate ice has a structure between the full structure of ice and the structure of the liquid," she adds. "We're solving a very old puzzle of what is going on in deeply supercooled water."

However, in the strange and wacky world of water, tiny amounts of liquid water theoretically still might be present even as temperatures plunge below minus 55 F and almost all the water has turned solid -- either into crystalline ice or amorphous water "glass," Molinero says. But any remaining liquid water can survive only an incredibly short time -- too short for the liquid's properties to be detected or measured.

How and at what temperature water must freeze has more than just "gee-whiz" appeal. Atmospheric scientists studying global warming want to know at what temperatures and rates water freezes and crystallizes into ice.
"You need that to predict how much water in the atmosphere is in the liquid state or crystal state," which relates to how much solar radiation is absorbed by atmospheric water and ice, Molinero says. "This is important for predictions of global climate."

A Strange Substance
Liquid water is a network of water molecules (each with two hydrogen atoms and one oxygen atom) held loosely together by what is called hydrogen bonding, which is somewhat like static cling. Molinero says that depending on its temperature and pressure, water ice has 16 different crystalline forms in which water molecules cling to each other with hydrogen bonds.

Molinero says that "what makes water so strange is that the way liquid water behaves is completely different from other liquids. For example, ice floats on water while most solids sink into their liquid forms because they are denser than the liquids."

Water's density changes with temperature, and it is most dense at 39 F. That's why fish survive under ice covering a pond by swimming in the warmer, denser water at the bottom of the pond.
But the property of water that "is most fascinating is that you can cool it down well below 32 degrees Fahrenheit and it still remains a liquid," says Molinero.

Liquid water as cold as minus 40 F has been found in clouds. Scientists have done experiments showing liquid water can exist at least down to minus 42 F.

Why doesn't water necessarily freeze at 32 F like we were taught in school?
"If you have liquid water and you want to form ice, then you have to first form a small nucleus or seed of ice from the liquid. The liquid has to give birth to ice," says Molinero. "For rain, you have to make liquid from vapor. Here, you have to make crystal [ice] from liquid."
Yet in very pure water, "the only way you can form a nucleus is by spontaneously changing the structure of the liquid," she adds.
Molinero says key questions include, "under which conditions do the nuclei form and are large enough to grow?" and "what is the size of this critical nucleus?"

Computing What Cannot Be Measured
Molinero says that "when you cool down water, its structure becomes closer to the structure of ice, which is why the density goes down, and this should be reflected in an increased crystallization rate."
Supercooled water has been measured down to about minus 42 F, which is its "homogenous nucleation temperature" -- the lowest temperature at which the ice crystallization rate can be measured as water is freezing. Below this temperature, ice is crystallizing too fast for any property of the remaining liquid to be measured.

To get around the problem, Molinero and chemistry doctoral student Moore used computers at the University of Utah's Center for High Performance Computing. The behavior of supercooled water was simulated and also modeled using real data.
Computers provide "a microscopic view through simulation that experiments cannot yet provide," Molinero says.

Previous computer simulations and modeling were too slow and had to last long enough for the freezing process to occur. And it was necessary to simulate thousands of nucleation events to make valid conclusions.
Molinero and Moore devised a new computer model that is 200 times faster than its predecessors. The model simplified the number crunching by considering each three-atom water molecule to be a single particle similar to a silicon atom and capable of sticking together with hydrogen bonding.

Even so, it took thousands of hours of computer time to simulate the behavior of 32,768 water molecules (much smaller than a tiny drop of water) to determine how the heat capacity, density and compressibility of water changes as it is supercooled, and to simulate how fast ice crystallized within a batch of 4,000 water molecules.

The Birth of Ice
The computers helped Molinero and Moore determine how cold water can get before it reaches its theoretical maximum crystallization rate and must freeze. The answer: minus 55 F (or minus 48 degrees Celsius).

The computers also showed that as water approaches minus 55 F, there is a sharp increase in the proportion of water molecules attached to four others to form tetrahedrons.
"The water is transforming to something else, and this something else is very close to ice," says Molinero. She calls it intermediate ice.

If a microscopic droplet of water is cooled very fast, it forms what is called a glass -- low-density amorphous ice -- in which all the tetrahedrons of water molecules are not lined up to form perfect crystals. Instead, low-density ice is amorphous like window glass. The study found that as many as one-quarter of the molecules in the amorphous "water glass" are organized either as intermediate ice or as tiny ice crystals.
When water approaches minus 55 F, there is an unusual decrease in density and unusual increases in heat capacity (which goes up instead of down) and compressibility (water gets easier to compress as it gets colder, unlike most liquids). These unusual thermodynamics coincide with liquid water changing to the tetrahedral structure.

"The change in structure of water controls the rate at which ice forms," Molinero says. "We show both the thermodynamics of water and the crystallization rate are controlled by the change in structure of liquid water that approaches the structure of ice."

(Via Science Daily)

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First Dogs Came from East Asia/Genetic Study

Researchers at KTH say they have found further proof that the wolf ancestors of today’s domesticated dogs can be traced to southern East Asia — findings that run counter to theories placing the cradle of the canine line in the Middle East.

Dr Peter Savolainen, KTH researcher in evolutionary genetics, says a new study released Nov. 23 confirms that an Asian region south of the Yangtze River was the principal and probably sole region where wolves were domesticated by humans.

Data on genetics, morphology and behaviour show clearly that dogs are descended from wolves, but there’s never been scientific consensus on where in the world the domestication process began. “Our analysis of Y-chromosomal DNA now confirms that wolves were first domesticated in Asia south of Yangtze River — we call it the ASY region — in southern China or Southeast Asia”, Savolainen says.

The Y data supports previous evidence from mitochondrial DNA. “Taken together, the two studies provide very strong evidence that dogs originated in the ASY region”, Savolainen says.

Archaeological data and a genetic study recently published in Nature suggest that dogs originate from the Middle East. But Savolainen rejects that view. “Because none of these studies included samples from the ASY region, evidence from ASY has been overlooked,” he says.

Peter Savolainen and PhD student Mattias Oskarsson worked with Chinese colleagues to analyse DNA from male dogs around the world. Their study was published in the scientific journal Heredity.

Approximately half of the gene pool was universally shared everywhere in the world, while only the ASY region had the entire range of genetic diversity. “This shows that gene pools in all other regions of the world most probably originate from the ASY region”, Savolainen says.

“Our results confirm that Asia south of the Yangtze River was the most important — and probably the only — region for wolf domestication, and that a large number of wolves were domesticated”, says Savolainen.

In separate research published recently in Ecology and Evolution, Savolainen, PhD student Arman Ardalan and Iranian and Turkish scientists conducted a comprehensive study of mitochondrial DNA , with a particular focus on the Middle East. Because mitochondrial DNA is inherited only from the mother in most species, it is especially useful in studying evolutionary relationships.

“Since other studies have indicated that wolves were domesticated in the Middle East, we wanted to be sure nothing had been missed. We find no signs whatsoever that dogs originated there”, says Savolainen.

In their studies, the researchers also found minor genetic contributions from crossbreeding between dogs and wolves in other geographic regions, including the Middle East.

“This subsequent dog/wolf hybridisation contributed only modestly to the dog gene pool”, Savolainen explains.
 (SciLifeLab)

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New Hydrogen Storage Material Based on Liquid Nitrogen developed

Hydrogen releases in the presence of iron chloride

In a research funded by the US Department of Energy, four scientists from the University of Oregon have developed a material to store hydrogen, using boron-nitrogen-based liquid-phase.This new material has displayed stability in both air and moisture. To be more specific, the research team developed a platform based on cyclic amine borane, which is also called BN-methylcyclopentane. Apart from being stable, the platform displayed the ability to retain hydrogen without changing phase. For the purpose of hydrogen desorption, the platform used iron chloride which enabled the conversion of the used fuel into the charged state.

This is a welcome change from the current storage materials which are solid, as liquid materials allow for a smooth transition from gasoline phase to hydrogen phase. During the course of the study, the researchers initially discovered six cyclic amine borane materials that were membered. On the release of hydrogen, these materials produced a large molecule. Although these materials were in their solid state, scientists altered the structure of the materials to convert them into liquid forms. The materials that were changed into liquid form in such a manner had low vapour pressure and retained their liquid form even upon the release of hydrogen.

Scientists believe that the new platform could be applicable in devices that use fuel cells. However, they also believe that the greatest hurdle in the commercial usage of such a platform would be the increase of hydrogen yield and the development of an effective mechanism to regenerate. The US Department of Energy is encouraging research to develop a solid or liquid hydrogen fuel carrier by 2017.

Source: http://www.uoregon.edu

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Study rejects "faster than light" particle finding

An international team of scientists in Italy studying the same neutrino particles colleagues say appear to have travelled faster than light rejected the startling finding this weekend, saying their tests had shown it must be wrong.

The September announcement of the finding, backed up last week after new studies, caused a furor in the scientific world as it seemed to suggest Albert Einstein's ideas on relativity, and much of modern physics, were based on a mistaken premise.

The first team, members of the OPERA experiment at the Gran Sasso laboratory south of Rome, said they recorded neutrinos beamed to them from the CERN research center in Switzerland as arriving 60 nanoseconds before light would have done.

But ICARUS, another experiment at Gran Sasso -- which is deep under mountains and run by Italy's National Institute of National Physics -- now argues that their measurements of the neutrinos energy on arrival contradict that reading.

In a paper posted Saturday on the same website as the OPERA results, arxiv.org/abs/1110.3763v2, the ICARUS team says their findings "refute a superluminal (faster than light) interpretation of the OPERA result."

They argue, on the basis of recently published studies by two top U.S. physicists, that the neutrinos pumped down from CERN, near Geneva, should have lost most of their energy if they had travelled at even a tiny fraction faster than light.

But in fact, the ICARUS scientists say, the neutrino beam as tested in their equipment registered an energy spectrum fully corresponding with what it should be for particles traveling at the speed of light and no more.

Physicist Tomasso Dorigo, who works at CERN, the European Organization for Nuclear Research, and the U.S. Fermilab near Chicago, said in a post on the website Scientific Blogging that the ICARUS paper was "very simple and definitive."

It says, he wrote, "that the difference between the speed of neutrinos and the speed of light cannot be as large as that seen by OPERA, and is certainly smaller than that by three orders of magnitude, and compatible with zero."

Under Einstein's 1905 theory of special relativity, nothing can travel faster than light. That idea lies at the heart of all current science of the cosmos and of how the vast variety of particles that make it up behave.

There was widespread skepticism when the OPERA findings were first revealed, and even the leaders of the experiment insisted that they were not announcing a discovery but simply recording measurements they had made and carefully checked.

However, last Friday they said a new experiment with shorter neutrino beams from CERN and much larger gaps between them had produced the same result. Independent scientists said however this was not conclusive.

Other experiments are being prepared -- at Fermilab and at the KEK laboratory in Japan -- to try to replicate OPERA's findings. Only confirmation from one of these would open the way for a full scientific discovery to be declared.

(Reuters)

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Mystery of Moon's Lost Magnetism Solved?

One of the abiding mysteries of our moon is why it apparently once had a magnetic field. Now two teams of scientists have offered two separate, but potentially complementary, explanations.

This illustration shows one suggested mechanism for creating an ancient magnetic field on the moon. In this scenario, impacting space rocks on the moon would create instability in the moon's core that could lead to a dynamo that creates a magnetic field. credit: M.-H. Deproost, ORB, Belgique

When Apollo astronauts brought back samples of moon rocks from their lunar landing missions in the 1960s and '70s, some of them shocked scientists by being magnetic. That means that individual rocks might have a magnetic north and south pole and a small magnetic field of their own.
This can happen to rocks with the right minerals inside them, if they cool in the presence of a magnetic field. The problem is, scientists had no idea that the moon had ever had a magnetic field, and were at a loss to explain how that might have happened.

A magnetic field is generated by what's called a dynamo, which is caused by the fluid motion of a conducting material, such as liquid iron. In the case of the Earth's magnetic field, this motion occurs in the planet's outer core, and is caused by the convection of heat.
But the moon isn't large enough for convection to take place. Scientists were at a loss to explain what else might generate the required liquid motion of iron inside the moon, until now.
Stirring it up
In one new proposal, Christina Dwyer of the University of California, Santa Cruz, and her colleagues suggest that the moon's solid-rock middle layer, called its mantle, stirs up its liquid iron core. The researchers think this happens because the moon's core and its mantle rotate around slightly different axes, and the boundary between them is not quite spherical, so their relative motion causes the fluid to mix around.
The strength of this stirring is determined by the angle between the core and the mantle, and the distance between the Earth and the moon, because the tidal gravitational tug from the Earth causes the moon's mantle to rotate differently than the core.

This model would explain why the moon used to have a magnetic field, but no longer does. That's because the angle between the mantle and the core has narrowed over time, while the distance between the moon and the Earth has widened, causing the tidal forces to steadily decrease. While these forces used to be enough to generate a dynamo inside the moon, they aren't anymore.
Based on their calculations, the researchers estimate the lunar magnetic field might have lasted for about a billion years, somewhere between around 2.7 billion and 4.2 billion years ago.
"Based on what we know about stirring, and everything we know about fluid motion, we can find no reason that this would not work," Dwyer told SPACE.com. "All the flags are go, and now this needs to be taken to the next level to get tested."
Dwyer said her research team had studied the basic scenario, but hopes that scientists who specialize in modeling the complex physics of dynamos will now step in to investigate whether this could explain what happened on the moon.
The researchers reported their theory in the Nov. 10 issue of the journal Nature.

Violent impacts
But theirs isn't the only possible solution to the moon's mystery.
In the same issue of Nature, Michael Le Bars of the French National Center for Scientific Research and the Université Aix-Marseille in France, along with his colleagues, propose another explanation for the ancient lunar magnetic field.

Le Bars' team also suggests that the moon's mantle might have stirred up the liquid in its core. However, they offer a different impetus for this stirring. Instead of tidal interactions between the Earth and the moon, the researchers posit that impacts by large space rocks slamming into the moon have changed its rotation rate, causing differential motion between the mantle and the core.

While the first scenario would cause steady stirring while the Earth and moon were the right distance apart, the second picture would induce brief periods of especially strong stirring of the core, creating spikes of a magnetic field on the moon.
While either option may be correct, it's also possible that both mechanisms played a role in causing an ancient magnetic field on the moon.

"The two studies are thought-provoking and may be complementary," Dominique Jault, a researcher at ETH Zürich in Switzerland and the Université Joseph-Fourier in France, who was not involved in either new study, wrote in an accompanying essay in the same issue of Nature. "Future palaeomagnetic experiments on samples from very old lunar rocks will enable their theories to be tested."
Via Space.com

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Lost Civilization Discovered in Sahara Desert

New evidence of a lost civilization in an area of the Sahara in Libya has emerged from images taken by satellites.

An ancient mudbrick village with a castle-like structure emerges in Libya

Using satellites and air photographs to identify the remains in one of the most inhospitable parts of the desert, a team from the University of Leicester in England has discovered more than 100 fortified farms and villages with castle-like structures and several towns, most dating between AD 1 to 500.

"It is like someone coming to England and suddenly discovering all the medieval castles. These settlements had been unremarked and unrecorded under the Gadhafi regime," said project leader David Mattingly, professor of Roman archaeology at the university. The fall of the regime has opened up Libya to more exploration by archaeologists of its pre-Islamic heritage.
These "lost cities" were built by a little-known ancient civilization called the Garamantes, whose lifestyle and culture was far more advanced and historically significant than ancient sources had suggested.

Castle-like complexes
The team from the University of Leicester has identified the mud brick remains of the castle-like complexes, with walls still standing up to 13 feet (4 meters) high, along with traces of dwellings, cairn cemeteries, associated field systems, wells and sophisticated irrigation systems. Follow-up ground surveys earlier this year confirmed the pre-Islamic date and remarkable preservation of the sites.

"Satellite imagery has given us the ability to cover a large region. The evidence suggests that the climate has not changed over the years and we can see that this inhospitable landscape with zero rainfall was once very densely built up and cultivated. These are quite exceptional ancient landscapes, both in terms of the range of features and the quality of preservation," said Martin Sterry, who has been responsible for much of the image analysis and site interpretation.
The findings challenge a view dating back to Roman accounts that the Garamantes consisted of barbaric nomads and troublemakers on the edge of the Roman Empire.

"In fact, they were highly civilized, living in large-scale fortified settlements, predominantly as oasis farmers. It was an organized state with towns and villages, a written language and state of the art technologies. The Garamantes were pioneers in establishing oases and opening up trans-Saharan trade," Mattingly said.
Libyan heritage
The professor and his team were forced to evacuate Libya in February when the anti-Gadhafi revolt started, but hope to be able to return to the field as soon as security is fully restored. The Libyan antiquities department, badly neglected under Gadhafi, is closely involved in the project.
"It is a new start for Libya's antiquities service and a chance for the Libyan people to engage with their own long-suppressed history," Mattingly said. "These represent the first towns in Libya that weren't the colonial imposition of Mediterranean people such as the Greeks and Romans. The Garamantes should be central to what Libyan school children learn about their history and heritage."
The research is funded by the European Research Council, the Leverhulme Trust, the Society for Libyan Studies and the GeoEye Foundation.

| LiveScience

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So That’s What Dreams Are Made Of

Scientists measure dream content for the first time and find that dreams activate the brain in a similar way to real actions.

Patient in a functional magnetic resonance imaging machine. © MPI of Psychiatry

The ability to dream is a fascinating aspect of the human mind. However, how the images and emotions that we experience so intensively when we dream form in our heads remains a mystery. Up to now it has not been possible to measure dream content. Max Planck scientists working with colleagues from the Charité hospital in Berlin have now succeeded, for the first time, in analyzing the activity of the brain during dreaming. They were able to do this with the help of lucid dreamers, i.e. people who become aware of their dreaming state and are able to alter the content of their dreams. The scientists measured that the brain activity during the dreamed motion matched the one observed during a real executed movement in a state of wakefulness.
Methods like functional magnetic resonance imaging have enabled scientists to visualize and identify the precise spatial location of brain activity during sleep. However, up to now, researchers have not been able to analyze specific brain activity associated with dream content, as measured brain activity can only be traced back to a specific dream if the precise temporal coincidence of the dream content and measurement is known. Whether a person is dreaming is something that could only be reported by the individual himself.
Scientists from the Max Planck Institute of Psychiatry in Munich, the Charité hospital in Berlin and the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig availed of the ability of lucid dreamers to dream consciously for their research. Lucid dreamers were asked to become aware of their dream while sleeping in a magnetic resonance scanner and to report this “lucid” state to the researchers by means of eye movements. They were then asked to voluntarily “dream” that they were repeatedly clenching first their right fist and then their left one for ten seconds.
This enabled the scientists to measure the entry into REM sleep – a phase in which dreams are perceived particularly intensively – with the help of the subject’s electroencephalogram (EEG) and to detect the beginning of a lucid phase. The brain activity measured from this time onwards corresponded with the arranged “dream” involving the fist clenching. A region in the sensorimotor cortex of the brain, which is responsible for the execution of movements, was actually activated during the dream. This is directly comparable with the brain activity that arises when the hand is moved while the person is awake. Even if the lucid dreamer just imagines the hand movement while awake, the sensorimotor cortex reacts in a similar way.
The coincidence of the brain activity measured during dreaming and the conscious action shows that dream content can be measured. “With this combination of sleep EEGs, imaging methods and lucid dreamers, we can measure not only simple movements during sleep but also the activity patterns in the brain during visual dream perceptions,” says Martin Dresler, a researcher at the Max Planck Institute for Psychiatry.
The researchers were able to confirm the data obtained using MR imaging in another subject using a different technology. With the help of near-infrared spectroscopy, they also observed increased activity in a region of the brain that plays an important role in the planning of movements. “Our dreams are therefore not a ‘sleep cinema’ in which we merely observe an event passively, but involve activity in the regions of the brain that are relevant to the dream content,” explains Michael Czisch, research group leader at the Max Planck Institute for Psychiatry

Source: Max-Planck-Gesellschaft   

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Scientists Developing Self-Repairing Plastic Material

A UK-based specialty chemical company has apparently developed a self-mending plastic that can repair itself without the need for glue, tape, or other materials, Telegraph Science Correspondent Richard Gray reported on Sunday.
“It could mean that sitting on a pair of glasses may no longer be the disaster it once was as they could be quickly repaired by pushing the broken bits back together,” Gray said. “The material could also put an end to broken children’s toys as they could be easily put back together even after the most destructive play session.”
The technology, which is being developed by AkzoNobel with assistance from Dutch scientists from the Eindhoven University of Technology, is described as a supramolecular polymer. It is known as Supra B and utilizes hydrogen bonding, which takes advantage of the natural attraction between hydrogen atoms and other atoms, such as oxygen or nitrogen, the Telegraph reporter added.
In addition to glasses or toys, Graham Armstrong, corporate director of research, development and innovation at AkzoNobel, told Gray that it could also be used to repair automobiles, thus avoiding the need for potentially costly body work following a car wreck. Other AkzoNobel officials say that it could also lead to new scratch-resistant coatings for vehicles, laptop computers, and similar devices.
“We are working on polymers that are able to heal themselves,” Armstrong told Gray. “They use supramolecular chemistry, which exploits some of the lessons we have learned from the way proteins bind together in biology. It means we can have solids that genuinely can heal.”
Gray says that the scientists working on Supra B have managed to “quadruple the number of hydrogen bonds between the small plastic, or polymer, molecules so that it is as strong as other forms of plastic, but does not require a chemical reaction to join them together.”
“What we want to do… is to adapt this principle, using either this chemistry or a similar one, to create a hard, protective coating that exhibits good self-healing,” AkzoNobel Chief Scientist Andrew Burgess told the Telegraph. “We are very excited by this prospect and we are seeking out the very best collaborations we can to help us on this journey.”

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Weird Science/Black Death genome reconstructed

 

Five skeletal remains from the East Smithfield site (Photo: Museum of London)

It's hard to comprehend the impact of the Black Death. The "Great Pestilence" is believed to have originated somewhere in Northern Asia in the 1330s before hitting Europe in 1347. It killed an estimated 75 million people worldwide - that's around 25 per cent of all humans in existence at the time. Now in an effort to better understand modern infectious diseases, scientist have sequenced the entire genome of the Black Death.

The research is based on analysis of skeletal remains from the East Smithfield "plague pits" in London using a previously developed methodology for extracting degraded DNA fragments of the bacteria that caused the plague - Yersinia pestis.

    Close-up of teeth from a plague victim (Photo: Museum of London)

The international team, led by researchers from McMaster University and the University of Tubingen, say this is the first time a reconstructed genome of any ancient pathogen has been drafted.
So why is this relevant in the 21st Century?
Descendants of the specific variant of the Yersinia pestis found in the 14th Century remain exist today, killing an estimated 2,000 people a year. By drafting the reconstruction of the genome scientist are able to see changes in the pathogen's evolution - which in this case have been minor - and gain a better understanding of such deadly infections.
(Hendrik Poinar, associate professor and director of the McMaster Ancient DNA Centre Photo: Museum of London)
"The genomic data show that this bacterial strain, or variant, is the ancestor of all modern plagues we have today worldwide," says Hendrik Poinar, associate professor and director of the McMaster Ancient DNA Centre. "Every outbreak across the globe today stems from a descendant of the medieval plague. With a better understanding of the evolution of this deadly pathogen, we are entering a new era of research into infectious disease."
There are still questions that remain unanswered about why the Black Death was so devastating however.
"We found that in 660 years of evolution as a human pathogen, there have been relatively few changes in the genome of the ancient organism, but those changes, however small, may or may not account for the noted increased virulence of the bug that ravaged Europe," says Poinar. "The next step is to determine why this was so deadly."
In other words, the research may have knocked out one of the main contenders in establishing why the Black Death had such a deadly impact. The Paper states that because the Black Death may not have been due to bacterial phenotype, "factors other than microbial genetics, such as environment, vector dynamics and host susceptibility, should be at the forefront of epidemiological discussions regarding emerging Y. pestis infections."
It has also been shown that the variation of Yersinia pestis that caused the medieval plague originated sometime around the 12th Century, which means that it was not the cause of the Justinian plague that struck the Byzantine Empire around 540 CE was not caused by the same pathogen as once thought.
"Using the same methodology, it should now be possible to study the genomes of all sorts of historic pathogens," says Johannes Krause of the University of Tubingen Krause. "This will provide us with direct insights into the evolution of human pathogens and historical pandemics."
The research is published online in the scientific journal Nature

Source: McMaster University

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Why men with deep voices get the girls

Scientists discover that women remember deep-voiced men better — and are more inclined to pick basses as mates

Men, if you want a woman to remember your name, say it with a boomingly deep voice. That's the stereotype-perpetuating finding of a new study from the University of Aberdeen in the U.K., which reveals that women not only recall men with deeper voices more vividly than their squeaky-voiced brethern, but that women are also more likely to choose a Barry White sound-alike as a mate. Here, a brief guide:
How was this research conducted?
In a series of experiments — the results were just published in the journal Memory & Cognition — researchers showed women a succession of images of ordinary objects. Each image was introduced by the voice of a man or a woman at varying pitches. The women were then shown two similar — but not identical — versions of the objects they had been shown before, and were asked to identify which of the two images they had seen earlier.
What did the psychologists discover?
In each experiment, the women had better recall of the objects that were introduced by the deep male voice — they had more trouble remembering objects that had been described by women's voices and higher-pitched male voices. The women were also asked which of the voices they preferred, and, to a significant degree, opted for the rumbling Darth Vader-esque guy.
How would this affect a woman's choice of mate?
The psychologists conducting the study suggest that the timbre of a man's voice communicates a "genetic quality as well as behavioral traits" that women find alluring in a long-term mate, says Claire Bates at Britain's Daily Mail. "We think this is evidence that evolution has shaped women's ability to remember information associated with desirable men," says researcher Dr. Kevin Allan, as quoted by ScienceDaily. One caveat: A similar study conducted earlier this year at Canada's McMaster University found that, while women are more magnetized by deeper male voices, they're also more likely to suspect the owners of those voices of infidelity.
Sources: Daily Mail, Globe and Mail, ScienceDaily

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Older dads may father kids with lower IQ's

Washington, Oct 4 (ANI): Older fathers are to be blamed for chromosomal abnormalities linked to intellectual disability in children, according to a new study.
Chromosomal abnormalities are caused by copy number variations, or CNVs. These are structural variations resulting in missing, repeated, inverted or misplaced DNA sequences in cells.
They can be inherited or arise anew, and are a common cause of disease.
The research team systematically analysed the prevalence of rare CNVs in almost 3500 people with intellectual disabilities between 2006 and 2010.
They found CNVs, which had arisen anew, as opposed to being inherited, in 227 people, meaning the prevalence was around twice as common in this group as among people with autism and three times as common as among those with asthma.
 Further analysis to determine the parental origin of the CNVs in the 118 people for whom data were available, showed that 90 had come from the father, and that three quarters represented missing DNA sequences.
The researchers then divided people with CNVs into two groups - those with CNVs occurring in regions of the genome with highly repetitive DNA sequences, and those with CNVs occurring in non - repetitive DNA sequences.
 They also compared paternal ages in both groups with those of the people without any intellectual disability.
A significant increase in the father's age was found in the group of CNVs in non-repetitive DNA sequences - which accounted for most CNVs - providing a crucial insight into the understanding of how and why disease - causing CNVs are formed, say the authors.
 The findings also indicate that newly arising CNVs not only originate more often from the father's DNA, but that the father's age has a role, the authors say.
"In conclusion, our data provide for the first time convincing evidence that CNVs in intellectual disability are largely paternal in origin," they add.
The study has been published online in the Journal of Medical Genetics. (ANI)

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Space Science/Did Ocean Water Originate From Comets?

A once off-the-wall idea gets back up as astronomers report on ocean-like water in a comet.

Comet Hartley 2 can be seen in detail in this image from NASA's EPOXI mission.

THE GIST

• Comet Hartley 2’s ice has one deuterium atom to every 6,200 hydrogen atoms, a ratio that is very close to water on Earth.

• Direct measurements of Kuiper Belt objects, including the dwarf planet Pluto, will be made with NASA's New Horizons spacecraft.

• Finding boosts pool of water available for delivery to baby Earth.

A family of comets from the Kuiper Belt may have assisted asteroids with bringing water to early Earth, a key development in the planet's ability to host life.
Scientists believe Earth’s water was delivered sometime after the planet formed, as its close proximity to the sun would have boiled off water inside rocks that were part of the original building materials.
Previous studies of meteorites, which are bits of asteroids that land on Earth, show a water chemistry that is similar to Earth’s oceans. The analysis is based on the ratio of regular water -- two hydrogen atoms bound with an oxygen atom, or H2O -- and so-called “heavy water,” which has an extra neutron in its nucleus.
The ratio was different in a handful of measurements made of comets, so scientists theorized that asteroids were the primary source of Earth’s water.
Not so, concludes a new study that looked at a comet hailing from a different part of the solar system than previously studied comets.
The target, Comet Hartley 2, is believed to have formed in the Kuiper Belt region, located beyond Neptune's orbit. Hartley 2 is now a member of the Jupiter family of short-period comets that swing around the sun in less than 20 years. The comet's water chemistry matches that of Earth's.
"This is an important constraint on models of the formation of planets in the solar system, a field of science which is moving forward very rapidly at present," astronomer Miriam Rengel of the Max Planck Institute for Solar System Research in Germany, wrote in an email to Discovery News.
Previous studies, which looked at comets originating from the Oort cloud, a spherical cluster of icy bodies in the outer solar system, led scientists to conclude that only about 10 percent of Earth's water could have come from comets.
The finding significantly boosts the pool of resources available to carry water to Earth.
"The reservoir of material that has the same isotopic signature as the Earth’s water is much larger in our solar system than we had previously assumed," astronomer Ted Bergin, with the University of Michigan, told Discovery News.
The studies were made in October and November 2010 as Hartley 2 passed closely by Earth with the European Space Agency's Herschel space telescope. The research is reported in this week's Nature

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Facial Expressions Develop Before Birth, Researchers Show

 Babies in the womb develop a range of facial movements in such a way that it is possible to identify facial expressions such as laughter and crying. For the first time, a group of researchers was able to show that recognisable facial expressions develop before birth and that, as the pregnancy progresses from 24 to 36 weeks gestation, fetal facial movements become more complex.
The group of researchers include Dr Nadja Reissland, a psychologist and Professor James Mason Director of Research in Medicine and Health of Durham University, Professor Brian Francis, Professor of social statistics at Lancaster University and Dr Karen Lincoln, consultant in Obstetrics and Gynaecology at the James Cook University Hospital, Middlesbrough, where the fetal scans are collected.
The group examined video-taped fetal facial movements obtained by 4D ultrasound machines in the later stages of pregnancy.
They recorded the same fetuses after they had been found to be healthy at their 20 week scan, several times between 24 and 36 weeks of gestation. They found that the movements of the fetal face become more complex over time.
Fetuses at the first stage of observation (24 weeks) were able to move one muscle in their face at a time. They would for example stretch their lips or open their mouth. By 35 weeks gestational age, fetuses combined a number of facial muscle movements, combining for example lip stretch, lowering of the eyebrows and deepening the nasolabial furrow, thereby turning isolated movements into recognisable and increasingly complex expressions.
Professor Brian Francis from the Department of Maths and Statistics at Lancaster University said: "This is a new and fascinating insight into the remarkable process of fetal development. This research has for the first time demonstrated that in healthy fetuses there is a developmental progression from simple to complex facial movements, preparing the fetus for life post birth."
Although the fetus cannot make any sounds, the development of facial expressions means that at birth, the baby has already developed the facial movements to accompany crying and laughing.
Dr Nadja Reissland from Durham University said: "We have found so much more than we expected. We knew that the baby blinks before birth and that some research has identified scowling before birth. However in this study for the first time we have developed a method of coding and analysis which allows us to objectively trace the increasing complexity of movements over time which results in recognisable facial expressions."
The researchers argue that these patterns of the motor movements are developed before the baby feels the emotion, just as the baby practises breathing movements in the uterus even before it has drawn a breath.
The discovery could help potentially identify health problems in utero, since there is a link between fetal behavioural patterns and the development of the fetal brain. Looking at differences between normal and abnormal fetal facial developments may indicate problems with brain development.
The researchers now plan to look at whether fetal facial movement might help differentiate between fetuses of mothers who smoke during pregnancy and non-smokers. They will also examine the development of facial expressions relating to anger, smiling and sadness.

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‘Artificial leaf’ makes fuel from sunlight

Researchers led by MIT professor Daniel Nocera have produced something they’re calling an “artificial leaf”: Like living leaves, the device can turn the energy of sunlight directly into a chemical fuel that can be stored and used later as an energy source.

The artificial leaf — a silicon solar cell with different catalytic materials bonded onto its two sides — needs no external wires or control circuits to operate. Simply placed in a container of water and exposed to sunlight, it quickly begins to generate streams of bubbles: oxygen bubbles from one side and hydrogen bubbles from the other. If placed in a container that has a barrier to separate the two sides, the two streams of bubbles can be collected and stored, and used later to deliver power: for example, by feeding them into a fuel cell that combines them once again into water while delivering an electric current.
The creation of the device is described in a paper published Sept. 30 in the journal Science. Nocera, the Henry Dreyfus Professor of Energy and professor of chemistry at MIT, is the senior author; the paper was co-authored by his former student Steven Reece PhD ’07 (who now works at Sun Catalytix, a company started by Nocera to commercialize his solar-energy inventions), along with five other researchers from Sun Catalytix and MIT.
The device, Nocera explains, is made entirely of earth-abundant, inexpensive materials — mostly silicon, cobalt and nickel — and works in ordinary water. Other attempts to produce devices that could use sunlight to split water have relied on corrosive solutions or on relatively rare and expensive materials such as platinum.
The artificial leaf is a thin sheet of semiconducting silicon — the material most solar cells are made of — which turns the energy of sunlight into a flow of wireless electricity within the sheet. Bound onto the silicon is a layer of a cobalt-based catalyst, which releases oxygen, a material whose potential for generating fuel from sunlight was discovered by Nocera and his co-authors in 2008. The other side of the silicon sheet is coated with a layer of a nickel-molybdenum-zinc alloy, which releases hydrogen from the water molecules.
“I think there’s going to be real opportunities for this idea,” Nocera says. “You can’t get more portable — you don’t need wires, it’s lightweight,” and it doesn’t require much in the way of additional equipment, other than a way of catching and storing the gases that bubble off. “You just drop it in a glass of water, and it starts splitting it,” he says.
Now that the “leaf” has been demonstrated, Nocera suggests one possible further development: tiny particles made of these materials that can split water molecules when placed in sunlight — making them more like photosynthetic algae than leaves. The advantage of that, he says, is that the small particles would have much more surface area exposed to sunlight and the water, allowing them to harness the sun’s energy more efficiently. (On the other hand, engineering a system to separate and collect the two gases would be more complicated in such a setup.)
(Science Daily)

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Aspirin Tied to Risk of Vision Loss

Seniors who take aspirin daily are twice as likely to have late stage macular degeneration, an age-related loss of vision, than people who never take the pain reliever, according to a new study.

The data do not show that aspirin causes vision loss. But the findings, published in Opthalmology, are of concern if aspirin somehow exacerbates the eye disorder, given how many seniors take it daily for heart disease.
"For people who have age-related macular degeneration, it probably isn't wise to recommend taking aspirin," said William Christen of Brigham and Women's Hospital in Boston, who was not involved in the study.
Researchers led by Paulus de Jong at the Netherlands Institute for Neuroscience and Academic Medical Center collected health and lifestyle information from nearly 4,700 people over age 65. The study included Norwegian, Estonian, British, French, Italian, Greek and Spanish seniors.
Of the 839 people who took aspirin each day, 36 had an advanced form of the disease called wet macular degeneration -- or about four out of every 100 daily aspirin users.
In comparison, roughly two out of every 100 people who took aspirin less frequently had the same type of macular degeneration.
The wet form of the condition, caused by leaking blood vessels in the eyes, leads to vision loss in the center of the eye's field of vision. The dry form is more common and less severe, although people still suffer visual impairment.
Together, wet and dry macular degeneration make up the leading causes of vision loss among people over age 60, afflicting millions of residents.
The researchers found that aspirin use was not tied to the dry form, nor to earlier stages of the disease.
"I don't think that's surprising," Christen told Reuters health. "I think the effects of aspirin may be different in the early stages of age-related macular degeneration than in the late stages."
De Jong told Reuters Health there has been controversy over the link between cardiovascular disease and macular degeneration.
He wrote in an email that his team had analyzed as "meticulously as possible" whether cardiovascular disease might have influenced the results, and still found that aspirin users -- regardless of their heart health -- are at a greater risk of the more serious type of vision loss.
For people with cardiovascular disease who take aspirin to prevent the condition from worsening, the benefits of the drug outweigh the risks to visual health, he added.
"A healthy eye with full visual capacities is of no use in a dead body," he said.
Larger studies that follow people over time and document their aspirin use and vision will help resolve aspirin's role in macular degeneration, de Jong added.

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Weird Science/Red Wine Ingredient Resveratrol Stops Breast Cancer Growth

Resveratrol, the "healthy" ingredient in red wine, stops breast cancer cells from growing by blocking the growth effects of estrogen, new research shows. (Credit: © Mist / Fotolia)

A new research report appearing in the October 2011 issue of The FASEB Journal shows that resveratrol, the "healthy" ingredient in red wine, stops breast cancer cells from growing by blocking the growth effects of estrogen. This discovery, made by a team of American and Italian scientists, suggests for the first time that resveratrol is able to counteract the malignant progression since it inhibits the proliferation of hormone resistant breast cancer cells. This has important implications for the treatment of women with breast cancer whose tumors eventually develop resistance to hormonal therapy.

"Resveratrol is a potential pharmacological tool to be exploited when breast cancer become resistant to the hormonal therapy," said Sebastiano Andò, a researcher involved in the work from the Faculty of Pharmacy at the University of Calabria in Italy.

To make this discovery, Andò and colleagues used several breast cancer cell lines expressing the estrogen receptor to test the effects of resveratrol. Researchers then treated the different cells with resveratrol and compared their growth with cells left untreated. They found an important reduction in cell growth in cells treated by resveratrol, while no changes were seen in untreated cells. Additional experiments revealed that this effect was related to a drastic reduction of estrogen receptor levels caused by resveratrol itself.

"These findings are exciting, but in no way does it mean that should people go out and start using red wine or resveratrol supplements as a treatment for breast cancer," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "What it does mean, however, is that scientists haven't finished distilling the secrets of good health that have been hidden in natural products such as red wine."

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Weird Science/Tree Frogs Chill out to Collect Precious Water

Research published in the October issue of The American Naturalist shows that Australian green tree frogs survive the dry season with the help of the same phenomenon that fogs up eyeglasses in the winter.

According to researchers from Charles Darwin University in Australia, tree frogs often plop themselves down outside on cool nights during the dry season in tropical Australia. When they return to their dens, condensation forms on their cold skin -- just like it does on a pair of glasses when we come in from the cold. The researchers found that frogs absorb this moisture through their skin, which helps to keep them hydrated during periods of little or no rain.

Before this study, the frogs' dry-season excursions were a bit mysterious.

"Every once in a while, we would find frogs sitting on a stick under the open sky, on nights when it was so cold they could barely move," said Dr. Chris Tracy, who led the research. "It was a real puzzle."

Tracy and his colleagues thought this behavior might enable the frogs collect condensation, but the hypothesis had never been tested.

The researchers designed a series of experiments using real frog dens in eucalyptus trees and artificial ones made from PVC pipe. They wanted to see if the frogs could collect enough moisture through condensation to compensate for what they lost being in the cold. They found that a cold night out cost a frog as much as .07 grams of water. However, a frog could gain nearly .4 grams, or nearly 1 percent of its total body weight, in water upon returning to the warm den.

The researchers also tested how well a frog's skin could absorb water, and found that as much as 60 percent of each water drop could be absorbed.

The results show that frogs can use condensation to hydrate themselves. And in a place as arid as the Australian savannahs during the dry season, where there is essentially no rain from June through August, every little bit counts.

"When there's no water available, even a small amount can mean the difference between surviving the dry season or not," Tracy said.

Tree frogs often plop themselves down outside on cool nights during the dry season in tropical Australia. When they return to their dens, condensation forms on their cold skin -- just like it does on a pair of glasses when we come in from the cold.

(story credit: Science Daily)

(photo Credit: © Patryk Kosmider / Fotolia)

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