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Monday, June 30, 2014

Scientists Chart A Baby Boom--In Southwestern Native Americans From 500 To 1300 A.D.

Scientists have sketched out one of the greatest baby booms in North American history, a centuries-long "growth blip" among southwestern Native Americans between 500 and 1300 A.D.

It was a time when the early features of civilization--including farming and food storage--had matured to a level where birth rates likely "exceeded the highest in the world today," the researchers report in this week's issue of the journal Proceedings of the National Academy of Sciences.

Reconstruction of life on a Hohokam platform mound in the Sonoran Desert in the 13th century A.D.

Credit: Pueblo Grande Museum, City of Phoenix

Then a crash followed, says Tim Kohler, an anthropologist at Washington State University (WSU), offering a warning sign to the modern world about the dangers of overpopulation.

"We can learn lessons from these people," says Kohler, who co-authored the paper with WSU researcher Kelsey Reese.

The study looks at a century's worth of data on thousands of human remains found at hundreds of sites across the Four Corners region of the Southwest.

"This research reconstructed the complexity of human population birth rate change and demographic variability linked with the introduction of agriculture in the Southwest U.S.," says Alan Tessier, acting deputy division director in the National Science Foundation's (NSF) Directorate for Biological Sciences, which supported the research through NSF's Dynamics of Coupled Natural and Human Systems (CNH) Program.

"It illustrates the coupling and feedbacks between human societies and their environment."

CNH is also co-funded by NSF's Directorates for Geosciences and Social, Behavioral & Economic Sciences.

While many of the remains studied have been repatriated, the data let Kohler assemble a detailed chronology of the region's Neolithic Demographic Transition, in which stone tools reflect an agricultural transition from cutting meat to pounding grain.

"It's the first step toward all the trappings of civilization that we currently see," says Kohler.

Maize, which we know as corn, was grown in the region as early as 2000 B.C.

At first, populations were slow to respond, probably because of low productivity, says Kohler. But by 400 B.C., he says, the crop provided 80 percent of the region's calories.

Sites like Pueblo Bonito in northern New Mexico reached their maximum size in the early 1100s A.D.

Credit: Nate Crabtree Photography

Crude birth rates--the number of newborns per 1,000 people per year--were by then on the rise, mounting steadily until about 500 A.D.

The growth varied across the region.

People in the Sonoran Desert and Tonto Basin, in what is today Arizona, were more culturally advanced, with irrigation, ball courts, and eventually elevated platform mounds and compounds housing elite families.

Yet birth rates were higher among people to the North and East, in the San Juan Basin and northern San Juan regions of Northwest New Mexico and Southwest Colorado.

Kohler said that the Sonoran and Tonto people eventually would have had difficulty finding new farming opportunities for many children, since corn farming required irrigation. Water from canals also may have carried harmful protozoa, bacteria and viruses.

But groups to the Northeast would have been able to expand maize production into new areas as their populations grew.

Around 900 A.D., populations remained high but birth rates began to fluctuate.

The mid-1100s saw one of the largest known droughts in the Southwest. The region likely hit its carrying capacity.

Pottery became common across the Southwest around A.D. 600; many vessels stored corn.

Credit: Bureau of Land Management/Anasazi Heritage Center Collections/Mark Montgomery

From the mid-1000s to 1280, by which time all the farmers had left, conflicts raged across the northern Southwest but birth rates remained high.

"They didn't slow down," says Kohler. "Birth rates were expanding right up to the depopulation. Why not limit growth? Maybe groups needed to be big to protect their villages and fields.

"It was a trap, however."

The northern Southwest had as many as 40,000 people in the mid-1200s, but within 30 years it was empty, leaving a mystery.

Ears of corn from a "Basketmaker II period" cache in Colorado, dating to the third century B.C.

Credit: Karen Adams, Crow Canyon Archaeological Center

Perhaps the population had grown too large to feed itself as the climate deteriorated. Then as people began to leave, that may have made it harder to maintain the social unity needed for defense and new infrastructure, says Kohler.

Whatever the reason, he says, the ancient Puebloans show that population growth has clear consequences.


Contacts and sources:
Cheryl Dybas, NSF
Eric Sorensen, WSU

Comet Churyumov–Gerasimenko Sweats Two Glasses Of Water Per Hour

ESA’s Rosetta spacecraft has found that comet 67P/Churyumov–Gerasimenko is releasing the equivalent of two small glasses of water into space every second, even at a cold 583 million kilometres from the Sun.


The first observations of water vapour streaming from the comet were made by the Microwave Instrument for Rosetta Orbiter, or MIRO, on 6 June, when the spacecraft was about 350 000 kilometres from the comet.

Since the initial detection, water vapour has been found every time MIRO has been pointed towards the comet.

“We always knew we would see water vapour outgassing from the comet, but we were surprised at how early we detected it,” says Sam Gulkis, the instrument’s principal investigator at NASA’s Jet Propulsion Laboratory in Pasadena, California, USA.

“At this rate, the comet would fill an Olympic-size swimming pool in about 100 days. But, as it gets closer to the Sun, the gas production rate will increase significantly. With Rosetta, we have an amazing vantage point to observe these changes up close and learn more about exactly why they happen.”

Comet 67P/Churyumov–Gerasimenko on 4 June
Credit: ESA

Water is a major volatile component of comets, along with carbon monoxide, methanol and ammonia. MIRO is designed to help determine the abundance of each of these ingredients, in order to understand the nature of the comet’s nucleus, the process of outgassing and where they originate on the surface.

These gases stream away from the nucleus carrying dust, forming the comet’s surrounding ‘coma’. As the comet moves closer to the Sun, its coma will expand and, eventually, pressure from the solar wind will cause some of the material to stream out into a long tail.

Rosetta will be there to watch these developments up close. The comet – and Rosetta – will make its nearest approach to the Sun in August 2015, between the orbits of Earth and Mars.

Determining the changes in production rate of water vapour and other gases as the icy object moves around the Sun is important for comet science. But it is also vital for mission planning, because once Rosetta is closer to the comet, the outflow of gases may alter the craft’s trajectory.

“Our comet is coming out of its deep-space slumber and beginning to put on a show for Rosetta’s science instruments,” says Matt Taylor, ESA’s Rosetta project scientist.

“Rosetta’s engineers will also be using MIRO’s observations to help them plan for future mission events when we are operating close to the comet’s nucleus.”

Today (June 30th, 2014), the spacecraft is within 72 000 km of its destination. Six out of a total of ten rendezvous manoeuvres still need to be carried out to ensure that Rosetta arrives at a distance of just 100 km from the nucleus on 6 August.


Contacts and sources:
ESA

Changes In Skin’s Barrier Set Northern Europeans Apart In Human Evolution, Study Questions Why

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 UC San Francisco researchers in a new study published online in the journal Evolutionary Biology.

Ramping up the skin’s capacity to capture UV light to make vitamin D is indeed important, according to a team led by Peter Elias, MD, a UCSF professor of dermatology. However, Elias and colleagues 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.

Elias’ team concluded that genetic mutations compromising the skin’s ability to serve as a barrier allowed fair-skinned Northern Europeans to populate latitudes where too little ultraviolet B (UVB) light for vitamin D production penetrates the atmosphere.

Among scientists studying human evolution, it has been almost universally assumed that the need to make more vitamin D at Northern latitudes drove genetic mutations that reduce production of the pigment melanin, the main determinant of skin tone, according to Elias.

“At the higher latitudes of Great Britain, Scandinavia and the Baltic States, as well as Northern Germany and France, very little UVB light reaches the Earth, and it’s the key wavelength required by the skin for vitamin D generation,” Elias said.

“While is seems logical that the loss of the pigment melanin would serve as a compensatory mechanism, allowing for more irradiation of the skin surface and therefore more vitamin D production, this hypothesis is flawed for many reasons,” he continued. “For example, recent studies show that dark-skinned humans make vitamin D after sun exposure as efficiently as lightly-pigmented humans, and osteoporosis – which can be a sign of vitamin D deficiency – is less common, rather than more common, in darkly-pigmented humans.”

Furthermore, evidence for a south to north gradient in the prevalence of melanin mutations is weaker than for this alternative explanation explored by Elias and colleagues.

In earlier research, Elias began studying the role of skin as a barrier to water loss. He recently has focused on a specific skin-barrier protein called filaggrin, which is broken down into a molecule called urocanic acid – the most potent absorber of UVB light in the skin, according to Elias. “It’s certainly more important than melanin in lightly-pigmented skin,” he said.

Family from South Africa showing some spectrum of human skin coloration 
Credit: Wikipedia

In their new study, the researchers identified a strikingly higher prevalence of inborn mutations in the filaggrin gene among Northern European populations. Up to 10 percent of normal individuals carried mutations in the filaggrin gene in these northern nations, in contrast to much lower mutation rates in southern European, Asian and African populations.

Moreover, higher filaggrin mutation rates, which result in a loss of urocanic acid, correlated with higher vitamin D levels in the blood. Latitude-dependent variations in melanin genes are not similarly associated with vitamin D levels, according to Elias. This evidence suggests that changes in the skin barrier played a role in Northern European’s evolutionary adaptation to Northern latitudes, the study concluded.

Yet, there was an evolutionary tradeoff for these barrier-weakening filaggrin mutations, Elias said. Mutation bearers have a tendency for very dry skin, and are vulnerable to atopic dermatitis, asthma and food allergies. But these diseases have appeared only recently, and did not become a problem until humans began to live in densely populated urban environments, Elias said.

The Elias lab has shown that pigmented skin provides a better skin barrier, which he says was critically important for protection against dehydration and infections among ancestral humans living in sub-Saharan Africa. But the need for pigment to provide this extra protection waned as modern human populations migrated northward over the past 60,000 years or so, Elias said, while the need to absorb UVB light became greater, particularly for those humans who migrated to the far North behind retreating glaciers less than 10,000 years ago.

The data from the new study do not explain why Northern Europeans lost melanin. If the need to make more vitamin D did not drive pigment loss, what did? Elias speculates that, “Once human populations migrated northward, away from the tropical onslaught of UVB, pigment was gradually lost in service of metabolic conservation. The body will not waste precious energy and proteins to make proteins that it no longer needs.”

For the Evolutionary Biology study, labeled a “synthesis paper” by the journal, Elias and co-author Jacob P. Thyssen, MD, a professor at the University of Copenhagen, mapped the mutation data and measured the correlations with blood levels of vitamin D. Labs throughout the world identified the mutations. Daniel Bikle, MD, PhD, a UCSF professor of medicine, provided expertise on vitamin D metabolism.

The research was funded by the San Francisco Veterans Affairs Medical Center, the Department of Defense, the National Institutes of Health, and by a Lundbeck Foundation grant.


Contacts and sources:

Some Sharks Tolerated Brackish Arctic Ocean 50 Million Years Ago

Sharks were a tolerant bunch some 50 million years ago, cruising an Arctic Ocean that contained about the same percentage of freshwater as Louisiana’s Lake Ponchatrain does today, says a new study involving the University of Colorado Boulder and the University of Chicago.

The study indicates the Eocene Arctic sand tiger shark, a member of the lamniform group of sharks that includes today’s great white, thresher and mako sharks, was thriving in the brackish water of the western Arctic Ocean back then. In contrast, modern sand tiger sharks living today in the Atlantic Ocean are very intolerant of low salinity, requiring three times the saltiness of the Eocene sharks in order to survive.

Modern Sand Tiger Shark 
Credit: Wikipedia

“This study shows the Arctic Ocean was very brackish and had reduced salinity back then,” said University of Chicago postdoctoral researcher Sora Kim, first author on the study. “The ancient sand tiger sharks that lived in the Arctic during the Eocene were very different than sand tiger sharks living in the Atlantic Ocean today.”

The findings have implications for how today’s sharks might fare in a warming Arctic region, which is heating up at about twice the rate of the rest of the planet due to increasing greenhouse gases, said CU-Boulder geological sciences Associate Professor Jaelyn Eberle, a study co-author. The potential consequences of warming in the Arctic include changes in freshwater runoff and atmospheric water vapor and decreases in salinity that can affect marine biology and seawater circulation dynamics.

CU-Boulder Associate Professor Jaerlyn Eberle, left, and research colleagues collect ancient sharks teeth on Banks Island in the Arctic Circle. Oxygen isotopes in the teeth indicated sharks living in the Eocene Arctic Ocean roughly 50 million years ago were tolerant of brackish water, unlike their shark relatives living today. 
Courtesy Jaelyn Eberle, University of Colorado  

“As more freshwater flows into the Arctic Ocean due to global warming, I think we are going to see it become more brackish,” said Eberle, also curator of fossil vertebrates at the University of Colorado Museum of Natural History. “Maybe the fossil record can shed some light on how the groups of sharks that are with us today may fare in a warming world.”

A paper on the subject was published online June 30 in the journal Geology. Other co-authors include David Bell from the University of Wyoming, Dewayne Fox from Delaware State University and Aspen Padilla, a CU-Boulder graduate who worked with Eberle as a master’s candidate. The study was funded in part by the National Science Foundation.

The new findings on Arctic Ocean salinity conditions in the Eocene were calculated in part by comparing ratios of oxygen isotopes locked in ancient shark teeth found in sediments on Banks Island in the Arctic Circle and incorporating the data into a salinity model. The team also compared its information to prior studies of sediment cores extracted from an oceanic region in the central Arctic Ocean called the Lomonosov Ridge -- a steep hump of continental crust that rises more than 1,000 feet from the ocean floor -- to estimate past environmental conditions in the Arctic Ocean.

“Oxygen isotopes in ancient bones and teeth reflect the water animals are living in or drinking,” said Kim, a former postdoctoral researcher at the University of Wyoming. “Because sharks are aquatic, the oxygen from the ocean is constantly being exchanged with oxygen in their body water, and that’s what is incorporated into their teeth. When I analyzed their isotopic composition, the numbers seemed weird at first because they indicated an essentially freshwater environment.”

The team analyzed 30 fossil sand tiger shark teeth exhumed from Banks Island and 19 modern sand tiger shark teeth from specimens caught in Delaware Bay bordered by Delaware and New Jersey. The paleo-salinity estimate for the modern sand tiger sharks is consistent with the continental shelf salinity present from Delaware south to Florida and from the coastline to roughly six miles offshore, known hunting grounds for modern sand tiger sharks, which have formidable teeth and can reach a length of nearly 10 feet.

The Eocene Epoch, which ran from about 56 to 34 million years ago, was marked by wild temperature fluctuations, including intense greenhouse periods when lush rainforests abounded in the Arctic. Previous studies by Eberle and colleagues showed the fauna there included ancestors of tapirs, hippo-like creatures, crocodiles and giant tortoises. Despite the six months of darkness each year, the terrestrial Arctic climate included warm humid summers and mild winters with temperatures ranging from just above freezing to about 70 degrees Fahrenheit.

“We now know a fair amount about the terrestrial animals and plants that were living in the Eocene Arctic greenhouse period,” said Eberle. “To finally get some data on the Eocene marine environment using these shark teeth will help us to begin filling in the gaps.”

Eberle said the Eocene Arctic Ocean was largely isolated from the global oceans. “Increased freshwater runoff from the land due to an intensified hydrologic cycle and a humid Arctic would have turned it more brackish pretty quickly,” she said.

The salinity gradient across the Eocene Arctic Ocean that provided habitat for the ancient sand tiger sharks also was found to be much larger than the salinity gradient tolerated by modern sand tiger sharks living in the Atlantic Ocean, said Eberle. “The Eocene lamniform group of sharks had a much broader environmental window than lamniform sharks do today.”

Eberle and Kim said the early-middle Eocene greenhouse period from 53 to 38 million years ago is used as a deep-time analog by climate scientists for what could happen on Earth if CO2 and other greenhouse gases in Earth’s atmosphere continue to rise, and what a “runaway” greenhouse effect potentially could look like.

“Through an analysis of fossil sand tiger shark teeth from the western Arctic Ocean, this study offers new evidence for a less salty Arctic Ocean during an ancient ‘greenhouse period,’ ” says Yusheng “Chris” Liu, program director in the NSF’s Division of Earth Sciences, which co-funded the research with NSF’s Division of Polar Programs. “The results also confirm that the Arctic Ocean was isolated during that long-ago time.


Contacts and sources:
Jaelyn Eberle
University of Colorado at Boulder

Optogenetics: Controlling The Mind With Light, A Powerful New Technology

New light-sensitive protein enables simpler, more powerful optogenetics.

Optogenetics, a technology that allows scientists to control brain activity by shining light on neurons, relies on light-sensitive proteins that can suppress or stimulate electrical signals within cells. This technique requires a light source to be implanted in the brain, where it can reach the cells to be controlled.

Illustration: Jose-Luis Olivares/MIT
MIT engineers have now developed the first light-sensitive molecule that enables neurons to be silenced noninvasively, using a light source outside the skull. This makes it possible to do long-term studies without an implanted light source. The protein, known as Jaws, also allows a larger volume of tissue to be influenced at once.

This noninvasive approach could pave the way to using optogenetics in human patients to treat epilepsy and other neurological disorders, the researchers say, although much more testing and development is needed. Led by Ed Boyden, an associate professor of biological engineering and brain and cognitive sciences at MIT, the researchers described the protein in the June 29 issue of Nature Neuroscience.

Optogenetics, a technique developed over the past 15 years, has become a common laboratory tool for shutting off or stimulating specific types of neurons in the brain, allowing neuroscientists to learn much more about their functions.

The neurons to be studied must be genetically engineered to produce light-sensitive proteins known as opsins, which are channels or pumps that influence electrical activity by controlling the flow of ions in or out of cells. Researchers then insert a light source, such as an optical fiber, into the brain to control the selected neurons.



Such implants can be difficult to insert, however, and can be incompatible with many kinds of experiments, such as studies of development, during which the brain changes size, or of neurodegenerative disorders, during which the implant can interact with brain physiology. In addition, it is difficult to perform long-term studies of chronic diseases with these implants.

Mining nature’s diversity

To find a better alternative, Boyden, graduate student Amy Chuong, and colleagues turned to the natural world. Many microbes and other organisms use opsins to detect light and react to their environment. Most of the natural opsins now used for optogenetics respond best to blue or green light.

Boyden’s team had previously identified two light-sensitive chloride ion pumps that respond to red light, which can penetrate deeper into living tissue. However, these molecules, found in the bacteria Haloarcula marismortui and Haloarcula vallismortis, did not induce a strong enough photocurrent — an electric current in response to light — to be useful in controlling neuron activity.

Chuong set out to improve the photocurrent by looking for relatives of these proteins and testing their electrical activity. She then engineered one of these relatives by making many different mutants. The result of this screen, Jaws, retained its red-light sensitivity but had a much stronger photocurrent — enough to shut down neural activity.

“This exemplifies how the genomic diversity of the natural world can yield powerful reagents that can be of use in biology and neuroscience,” says Boyden, who is a member of MIT’s Media Lab and the McGovern Institute for Brain Research.

Using this opsin, the researchers were able to shut down neuronal activity in the mouse brain with a light source outside the animal’s head. The suppression occurred as deep as 3 millimeters in the brain, and was just as effective as that of existing silencers that rely on other colors of light delivered via conventional invasive illumination.

A key advantage to this opsin is that it could enable optogenetic studies of animals with larger brains, says Garret Stuber, an assistant professor of psychiatry and cell biology and physiology at the University of North Carolina at Chapel Hill.

“In animals with larger brains, people have had difficulty getting behavior effects with optogenetics, and one possible reason is that not enough of the tissue is being inhibited,” he says. “This could potentially alleviate that.”

Restoring vision

Working with researchers at the Friedrich Miescher Institute for Biomedical Research in Switzerland, the MIT team also tested Jaws’s ability to restore the light sensitivity of retinal cells called cones. In people with a disease called retinitis pigmentosa, cones slowly atrophy, eventually causing blindness.

Friedrich Miescher Institute scientists Botond Roska and Volker Busskamp have previously shown that some vision can be restored in mice by engineering those cone cells to express light-sensitive proteins. In the new paper, Roska and Busskamp tested the Jaws protein in the mouse retina and found that it more closely resembled the eye’s natural opsins and offered a greater range of light sensitivity, making it potentially more useful for treating retinitis pigmentosa.

This type of noninvasive approach to optogenetics could also represent a step toward developing optogenetic treatments for diseases such as epilepsy, which could be controlled by shutting off misfiring neurons that cause seizures, Boyden says. “Since these molecules come from species other than humans, many studies must be done to evaluate their safety and efficacy in the context of treatment,” he says.

Boyden’s lab is working with many other research groups to further test the Jaws opsin for other applications. The team is also seeking new light-sensitive proteins and is working on high-throughput screening approaches that could speed up the development of such proteins.

The research at MIT was funded by Jerry and Marge Burnett, the Defense Advanced Research Projects Agency, the Human Frontiers Science Program, the IET A. F. Harvey Prize, the Janet and Sheldon Razin ’59 Fellowship of the MIT McGovern Institute, the New York Stem Cell Foundation-Robertson Investigator Award, the National Institutes of Health, the National Science Foundation, and the Wallace H. Coulter Foundation.


Contacts and sources: 
Anne Trafton
MIT News Office

Mysterious Features Spotted On Titan Reveal The Moon's Seasonal Changes, Says Stanford Scientist

Bright spots in a large lake on Titan suggest that Saturn's largest moon supports processes similar to Earth's water cycle, says Howard Zebker.

At first glance, Titan has little in common with Earth. The largest moon of Saturn, temperatures on Titan's surface dip nearly 300 F below zero, its seas slosh with liquid methane, and its sky is a murky shade of creamsicle.

Using data collected by Cassini's radar instruments, scientists have observed changes in Titan's liquid methane lakes and seas that indicate the moon experiences seasonal changes.

Image: NASA/JPL-Caltech

And yet, fresh analysis of mysterious features spotted on the moon indicates that it experiences one of the same global processes that is important here on Earth.

In a study published in the latest issue of Nature Geoscience, scientists operating the Cassini satellite, including Stanford's Howard Zebker, present evidence that Titan has seasonal cycles analogous to Earth's, and that the moon's surface conditions change as the Titan year unfolds.

The Cassini satellite has been orbiting Saturn and its moons since 2004. Zebker, a professor of electrical engineering and of geophysics, is one of the lead scientists operating the spacecraft's radar instruments. Radar is critical for studying Titan in particular because the moon's atmosphere is typically too cloudy and thick for optical instruments to see through easily.

During five fly-bys of Titan's Ligeia Mare – a liquid methane sea larger than Lake Superior – the scientists noticed bright features that appeared and changed shape on the sea's surface. After ruling out a technical glitch or an exotic artifact of radar scattering, the group focused on three causes most likely for the phenomena.

Ligeia Mare
Credit: NASA

"We are driven to use our imaginations and picture what could be happening on the sea to produce a transient feature," Zebker said.

One such explanation could involve low-density solids that usually sink below the surface – much like silt in a river delta – but then rise and clump together. Unlike ice on Earth, frozen methane is denser than its liquid phase, so it sinks instead of floats. "On Earth, ice floats and we get icebergs," Zebker said. "On Titan, icebergs would sink."

Seasonal temperature changes could account for the appearance and disappearance of these solids, as they might be released from the bottom and rise to the surface in warmer temperatures.

A second explanation involves bubbles. As summer temperatures warm the sea, bubbles trapped by the sunken frozen material could be released and float to the surface.

Finally, the bright features could be cresting waves, whipped up by summer winds.

"Waves are usually not visible on Titan, but in this case the onset of the summer season may create a more turbulent atmosphere," Zebker said. "On Earth we see this effect as the ocean warms and we start a new hurricane season."
A global cycle

All together, the observation and the possible explanations suggest that Titan's surface changes seasonally. They also support the idea that liquid methane might flow and evaporate in response to changing exposure to sunlight, in much the same way that water cycles through various systems on Earth.

Liquid methane lakes and seas have been observed on Titan's surface, and the atmosphere appears to carry methane and ethane similar to the way that Earth's atmosphere transports water vapor, Zebker said, and so scientists can expect Titan to have variations in liquid methane, ethane and other hydrocarbons driven by changes in temperature and sunlight.

As with any discovery that compares an alien world to Earth, the question of "Can it support life?" must be addressed. Although a dynamic process like the methane cycle and seasons go hand-in-hand with life on Earth, Zebker said that this discovery didn't significantly increase the chances that this moon of Saturn might support life.

"If there is sufficient energy pumped into Titan's atmosphere and surface from the sun, then it is possible that this would spawn evolution of life forms that take advantage of the energy source," Zebker said. "It would be very different life than on Earth, as it is minus 292 degrees Fahrenheit most of the time. Still, Titan remains one of the best places for life to evolve in the solar system."


Contacts and sources:
Howard Zebker


Citation: 'Transient features in a Titan sea,' Nature Geoscience (doi: 10.1038/ngeo2190)

The Chemistry Of Fireworks: Fourth Of July Science (Video)

The Fourth of July is just days away, and that means millions of Americans will soon enjoy eye-popping fireworks displays around the country. These dazzling light shows are actually carefully crafted chemical reactions. 

Credit: Wikipedia

This week's Reactions episode features John Conkling, Ph.D., the professor who literally wrote the book on pyrotechnics. In the video, Conkling explains the chemistry that creates those amazing fireworks displays.



From the sizzle of the fuse to the boom and burst of colors, this video brings you all of the exciting sights and sounds of Fourth of July fireworks, plus a little chemical know how. John A. Conkling, Ph.D., shows how the familiar rockets and other neat products that light up the night sky all represent chemistry in action.


Contacts and sources:
Michael Bernstein
American Chemical Society

Sunday, June 29, 2014

Tightest Trio Of Black Holes Ever Found Yield Best Hope In Search For Gravity Waves

The discovery of three closely orbiting supermassive black holes in a galaxy more than four billion light years away could help astronomers in the search for gravitational waves: the 'ripples in spacetime' predicted by Einstein.

An international team, including Oxford University scientists, led by Dr Roger Deane from the University of Cape Town, examined six systems thought to contain two supermassive black holes. The team found that one of these contained three supermassive black holes – the tightest trio of black holes detected at such a large distance – with two of them orbiting each other rather like binary stars. The finding suggests that these closely-packed supermassive black holes are far more common than previously thought.

A report of the research is published in this week's Nature.

Dr Roger Deane from the University of Cape Town said: 'What remains extraordinary to me is that these black holes, which are at the very extreme of Einstein's Theory of General Relativity, are orbiting one another at 300 times the speed of sound on Earth. Not only that, but using the combined signals from radio telescopes on four continents we are able to observe this exotic system one third of the way across the Universe. It gives me great excitement as this is just scratching the surface of a long list of discoveries that will be made possible with the Square Kilometre Array (SKA).'

Professor Matt Jarvis of Oxford University's Department of Physics, an author of the paper, said: 'General Relativity predicts that merging black holes are sources of gravitational waves and in this work we have managed to spot three black holes packed about as tightly together as they could be before spiralling into each other and merging. The idea that we might be able to find more of these potential sources of gravitational waves is very encouraging as knowing where such signals should originate will help us try to detect these ‘ripples’ in spacetime as they warp the Universe.'

The team used a technique called Very Long Baseline Interferometry (VLBI) to discover the inner two black holes of the triple system. This technique combines the signals from large radio antennas separated by up to 10,000 kilometres to see detail 50 times finer than that possible with the Hubble Space Telescope.

The discovery was made with the European VLBI Network, an array of European, Chinese, Russian and South African antennas, as well as the 305 metre Arecibo Observatory in Puerto Rico. Future radio telescopes such as the SKA will be able to measure the gravitational waves from such black hole systems as their orbits decrease.

Helical jets from one supermassive black hole caused by a very closely orbiting companion (see blue dots). The third black hole is part of the system, but farther away and therefore emits relatively straight jets.

Inset image: Modified from NASA Goddard original.

At this point, very little is actually known about black hole systems that are so close to one another that they emit detectable gravitational waves. Professor Jarvis said: 'This discovery not only suggests that close-pair black hole systems emitting at radio wavelengths are much more common than previously expected, but also predicts that radio telescopes such as MeerKAT and the African VLBI Network (AVN, a network of antennas across the continent) will directly assist in the detection and understanding of the gravitational wave signal. 

Further in the future the SKA will allow us to find and study these systems in exquisite detail, and really allow us gain a much better understanding of how black holes shape galaxies over the history of the Universe.'

Dr Keith Grainge of the University of Manchester, an author of the paper, said: 'This exciting discovery perfectly illustrates the power of the VLBI technique, whose exquisite sharpness of view allows us to see deep into the hearts of distant galaxies. The next generation radio observatory, the SKA, is being designed with VLBI capabilities very much in mind.'

While the VLBI technique was essential to discover the inner two black, the team has also shown that the binary black hole presence can be revealed by much larger scale features. The orbital motion of the black hole is imprinted onto its large jets, twisting them into a helical or corkscrew-like shape. So even though black holes may be so close together that our telescopes can’t tell them apart, their twisted jets may provide easy-to-find pointers to them, much like using a flare to mark your location at sea. This may provide sensitive future telescopes like MeerKAT and the SKA a way to find binary black holes with much greater efficiency.

The UK team included researchers from Oxford University, the University of Manchester, and the University of Cambridge. A report of the research, entitled 'A close-pair binary in a distant triple supermassive black-hole system', is published in this week's Nature.


Contacts and sources:
Oxford University

Most Earth-Like Planet Found Orbits Red Dwarf Star

A  University of New South Wales (UNSW) led team of researchers has discovered a potentially habitable Earth-like planet that is only 16 light years away.

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, because red dwarfs shine more dimly than our Sun, and may have similar temperatures to our planet.

An artist's impression of the new planet and Earth 
Credit: PHL, University of Puerto Rica, Arecibo

These characteristics put it among the top three most Earth-like planets, according to the Earth Similarity Index developed by scientists at the University of Puerto Rica in Arecibo.

The international team, led by Dr Robert Wittenmyer in the UNSW School of Physics, report their finding of the planet online ahead of publication in the Astrophysical Journal.

Team member and Head of UNSW’s Exoplanetary Science research group, Professor Chris Tinney, says that if the planet has a similar atmosphere to Earth it may be possible for life to survive, although seasonal shifts would be extreme.

“However, given the large mass of the planet, it seems likely that it would possess a massive atmosphere, which may well render the planet inhospitable. A denser atmosphere would trap heat and could make it more like a super-Venus and too hot for life,” says Professor Tinney.

The planet was discovered from its gravitational pull on its parent star, which causes the star to wobble slightly. Members of the Anglo-Australian Planet Search team used the Anglo-Australian Telescope to make observations of the planet.

Their data were combined with observations from the 6.5m Magellan Telescope and the European Southern Observatory 3.6m telescope (both in Chile) to make this new discovery.

This team had previously found, in 2009, that the star has a cold Jupiter-like planet with a near-circular orbit of about nine years, called Gliese GJ b.

“With an outer giant planet and an interior potentially rocky planet, this planetary system can be thought of as a miniature version of our Solar System,” says Professor Tinney.

On the Earth Similarity Index, or ESI, the highest ranking exoplanet is Gliese 667C c, which is about 23 light years away. It has an ESI of 0.84 compared to Earth’s maximum score of 1.0

Next on the list is Kepler-62 e with an ESI of 0.83, although it is much further away – about 1,200 light years distant. And the new planet – the closest at just 16 light years away – comes in third with an ESI of 0.81.

For comparison, the Milky Way is about 100,000 light years across.

The team includes researchers from Australia, the UK, Finland, the US, Italy and Chile.


Contacts and sources:
Deborah Smith

The Secrets Of Children’s Chatter: Research Shows Boys And Girls Learn Language Differently

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’.

However, most research into understanding how these processes work has been carried out with adults.

“Most researchers agree that the way we use language in our minds involves both storing and real-time composition,” said lead researcher Dr Cristina Dye, a specialist in child language development at Newcastle University. “But a lot of the specifics about how this happens are unclear, such as identifying exactly which parts of language are stored and which are composed.

Dr Cristina Dye

Credit: Newcastle University UK

“Most research on this topic has concentrated on adults and we wanted to see if studying children could help us learn more about these processes.”

A test based around 29 irregular verbs and 29 regular verbs was presented to the young participants. Only verbs which would be known by eight-year-olds were used.

They were presented with two sentences. One featured the verb in the context of the sentence, with the second sentence containing a blank to allow the children to produce the past-tense form. For example: Every day I walk to school. Just like every day, yesterday I ____ to school.

The children were asked to produce the missing word as quickly and as accurately as possible and their response times were recorded. The results were then analysed to discover which words were stored or created in real-time.

Results showed girls were more likely to memorise words and phrases – use their mental dictionary - while boys used mental grammar - i.e assembled these from smaller parts - more often.

The findings could have implications in the way youngsters are taught in the classroom, believes Dr Dye, who is based in the Centre for Research in Linguistics and Language Sciences.

She said: “What we found as we carried out the study was that girls were far more likely to remember forms like ‘walked’ while boys relied much more on their mental grammar to compose ‘walked’ from ‘walk’ and ‘ed’. This fits in with previous research which has identified differences between the sexes when it comes to memorising facts and events, where girls also seem to have an advantage compared to boys.

“One interesting aside to this is that as girls often outperform boys at school, it could be that the curriculum is put together in a way which benefits the way girls learn. It may be worth further investigation to see if this is the case and if so, is there a way lessons could be changed so boys can get the most out of them too.”

Dr Dye will be discussing aspects of the research at a conference, Grammar: Universals and Acquisitions, at Cambridge University on Monday 30 June.



Contacts and sources:
Newcastle University


Citation: The paper Children’s Computation of Complex Linguistic Forms: A study of Frequency and Imageability Effects is published in Plos One.

Wonder Material To Revolutionize Auto Industry

A pioneering research project to develop lighter, stronger, more energy-efficient, and safe vehicles using ‘wonder material’ graphene is being led by the University of Sunderland and could potentially revolutionize the global automotive industry.

Graphene is a material made from a single layer of carbon atoms, which is stronger than diamond, lightweight and flexible, first discovered during experiments by Professors Kostya Novoselov and Andrew Geim, who were awarded the Nobel Prize for Physics in 2010.

Credit:  University of Sunderland

Since the discovery, the European Commission is investing €1bn as part of the Graphene Flagship over 10 years, which aims to take graphene related technologies from academic laboratories to everyday use in multiple industries, creating economic growth and new jobs in Europe.

To coincide with Graphene Week 2014, the Graphene Flagship has today announced it is doubling in size as a result of a €9m Competitive Call, with 21 new proposals out of 218 from 19 countries, selected for funding.

The University of Sunderland, working with a consortium of five research partners from Italy Spain and Germany, was one of those selected as a partner for their iGCAuto proposal, which will see the group conduct a series of tests analysing the properties of graphene to determine how it behaves when it’s used to enhance the advanced composite materials used in the production of cars.

The automotive industry is widely viewed as being the industry in which the greatest volume of advanced composite materials will be used in the future to produce light vehicles. However, due to the trade-off between light vehicles and safety standards, new directions need to be adopted to overcome safety issues. 

Professor Ahmed Elmarakbi, a Professor of Automotive Engineering at Sunderland’s Department of Computing, Engineering and Technology, at the University of Sunderland
Credit: University of Sunderland

Several attempts have been made to strengthen the vehicle’s structure to enhance its crashworthiness, however, safety issues remain the main obstacle to producing lighter and greener cars. Therefore, in this project, a novel graphene-based polymer material will be investigated, modelled, and designed to enhance both vehicle and occupant safety; yet remain very light. This material will provide benefits such as improved strength, dimensional stability, and superior durability.

From some recent experiments and numerical simulations, it has been clarified that the impact resistance and crashworthiness optimisation studies of advanced composites components remain at an early stage. A large amount of work remains to be done to develop a practical, reliable and capable tool to analyse and design the new graphene-based polymer composites and study the crashworthiness optimisation for its structures and their applications in the automotive industry.

iGCAuto will address the gap between light vehicles and safety through the establishment of a high-level, enduring collaboration. The particular strength of this project is that it brings together the necessary expertise to develop novel graphene-based polymer composite materials and to then assess and predict their safety behaviour and long-term performance under severe conditions (i.e. crashworthiness, fatigue, etc.). This enhanced understanding will inform asset owners and managers and lead to improved design strategies.

Partners involved in the iGCAuto include: Centro Ricerche FIAT (Italy), Fraunhofer ICT (Germany), Interquimica (Spain), Nanesa S.r.l. (Italy), and Delta-Tech S.p.A. (Italy).

Professor Ahmed Elmarakbi, a Professor of Automotive Engineering at Sunderland’s Department of Computing, Engineering and Technology, initiated the idea and wrote the Graphene Flagship proposal and will drive the project forward over the next 18 months.

He said: “Graphene has tremendous applications for the automotive industry and using it to enhance the composite materials in cars has so much potential. It’s an honor for the University of Sunderland to lead on a project that has been recognized though the Graphene Flagship Competitive Call, which reinforces our reputation as a leading group in international research in automotive, manufacturing and ultra-low carbon vehicle technology.”

Graphene
  Credit:  University of Sunderland

He added: “The global automotive industry is currently facing great challenges, such as CO2 emissions and safety issues. The development and manufacture of environmentally-friendly, energy-efficient, and safe vehicles (EESVs) is a great solution to these challenges. Our goal is that the future EESVs is achieved by a combination of novel materials concepts with safety design approaches through the development and optimisation of advanced ultra-light graphene-based polymer materials, efficient fabrication and manufacturing processes, and life-cycle analysis (LCA) to reduce the environmental impact of the vehicle.

“The development of novel graphene-based materials and their potential applications in the automotive industry are the main focus of the iGCAuto project. Using graphene-based materials in the fabrication of nanocomposites with different polymer matrices will be investigated, modelled, and designed to enhance both vehicle and occupant safety; yet remain very light. This material will provide benefits such as improved strength, dimensional stability and better thermal behaviour, better flame behaviour (active as flame retardant and for reducing the emission of smoke), and superior durability.

“There will be challenges with this project, the issue is not only producing graphene-based products, the issue is applying them on a large-scale in cars. To achieve this, we have formed a consortium which comprises some of the best researchers in graphene materials and vehicle light-weighting in the world. The grant opportunity allows the consortium to aim to deliver fundamental solutions to the key challenges faced by the future development of EESVs. A key part of our project is building strong collaborations with world-class researchers who will be able to develop, understand and predict the behaviour of the new graphene composites. Such a predictive ability will be a big step forward in bringing graphene composites to real-world automotive applications.”

Vice-President of the European Commission Neelie Kroes, responsible for the Graphene Flagship Digital Agenda, welcomed the extended partnership: "Europe is leading the graphene revolution.

“This ‘wonder material’ has the potential dramatically to improve our lives: it stimulates new medical technologies, such as artificial retinas, and more sustainable transport with light and ultra-efficient batteries. The more we can unlock the potential of graphene, the better!”

Professor Andrea Ferrari, Director of the Cambridge Graphene Centre and Chair of the Executive Board of the Graphene Flagship commenting on the new partners, said: "This adds strength to our unprecedented effort to take graphene and related materials from the lab to the factory floor, so that the world-leading position of Europe in graphene science can be translated into technology, creating a new graphene-based industry, with benefits for Europe in terms of job creation and competitiveness.”


Contacts and sources:University of Sunderland

Superconductor World Record Broken By Cambridge Team, Heralds Arrival Of New Materials For Real World Applications

New record for a trapped field in a superconductor, beating a record that has stood for more than a decade, could herald the arrival of materials in a broad range of fields.

A world record that has stood for more than a decade has been broken by a team led by University of Cambridge engineers, harnessing the equivalent of three tonnes of force inside a golf ball-sized sample of material that is normally as brittle as fine china.

A bulk superconductor levitated by a permanent magnet

Credit: University of Cambridge 

The Cambridge researchers managed to ‘trap’ a magnetic field with a strength of 17.6 Tesla - roughly 100 times stronger than the field generated by a typical fridge magnet - in a high temperature gadolinium barium copper oxide (GdBCO) superconductor, beating the previous record by 0.4 Tesla. The results are published today in the journal Superconductor Science and Technology.

The research demonstrates the potential of high-temperature superconductors for applications in a range of fields, including flywheels for energy storage, ‘magnetic separators’, which can be used in mineral refinement and pollution control, and in high-speed levitating monorail trains.

Superconductors are materials that carry electrical current with little or no resistance when cooled below a certain temperature. While conventional superconductors need to be cooled close to absolute zero (zero degrees on the Kelvin scale, or –273 °C) before they superconduct, high temperature superconductors do so above the boiling point of liquid nitrogen (–196 °C), which makes them relatively easy to cool and cheaper to operate.

Superconductors are currently used in scientific and medical applications, such as MRI scanners, and in the future could be used to protect the national grid and increase energy efficiency, due to the amount of electrical current they can carry without losing energy.

The current carried by a superconductor also generates a magnetic field, and the more field strength that can be contained within the superconductor, the more current it can carry. State of the art, practical superconductors can carry currents that are typically 100 times greater than copper, which gives them considerable performance advantages over conventional conductors and permanent magnets.

The new record was achieved using 25 mm diameter samples of GdBCO high temperature superconductor fabricated in the form of a large, single grain using an established melt processing method and reinforced using a relatively simple technique. The previous record of 17.24 Tesla, set in 2003 by a team led by Professor Masato Murakami from the Shibaura Institute of Technology in Japan, used a highly specialised type of superconductor of a similar, but subtly different, composition and structure.

“The fact that this record has stood for so long shows just how demanding this field really is,” said Professor David Cardwell of Cambridge’s Department of Engineering, who led the research, in collaboration with Boeing and the National High Field Magnet Laboratory at the Florida State University. “There are real potential gains to be had with even small increases in field.”

To contain such a large field, the team used materials known as cuprates: thin sheets of copper and oxygen separated by more complex types of atoms. The cuprates were the earliest high temperature superconductors to be discovered, and have the potential to be used widely in scientific and medical applications.

While they are high quality superconductors with outstanding potential for practical applications, the cuprates can be as brittle as dried pasta when fabricated in the form of sintered ceramics, so trying to contain a strong magnetic field within bulk forms of the cuprates tends to cause them to explode.

In order to hold in, or trap, the magnetic field, the researchers had to modify both the microstructure of GdBCO to increase its current carrying and thermal performance, and reinforce it with a stainless steel ring, which was used to ‘shrink-wrap’ the single grain samples. “This was an important step in achieving this result,” said Dr John Durrell who led the experiment in Florida.

The lines of magnetic flux in a superconductor repel each other strongly, making containing such a large field difficult. But, by engineering the bulk microstructure, the field is retained in the sample by so-called ‘flux pinning centres’ distributed throughout the material. “The development of effective pinning sites in GdBCO has been key to this success,” said Dr Yun-Hua Shi, who has been responsible for developing the melt process fabrication technique at Cambridge for the past 20 years.

The result was the biggest ever trapped field achieved in a bulk, standalone material at any temperature.

“This work could herald the arrival of superconductors in real-world applications,” said Professor Cardwell. “In order to see bulk superconductors applied for everyday use, we need large grains of superconducting material with the required properties that can be manufactured by relatively standard processes.”

A number of niche applications are currently being developed by the Cambridge team and its collaborators, and it is anticipated that widespread commercial applications for superconductors could be seen within the next five years.

“This record could not have been achieved without the support of our academic and industrial colleagues and partners,” said Professor Cardwell, who is the next Head of the Department of Engineering. “It was a real team effort, and one which we hope will bring these materials a significant step closer to practical applications.”

“Boeing continues to see practical applications for this superconducting material research and we are excited about the possibilities being enabled by the recent advances achieved by the Cambridge team,” said Patrick Stokes, who leads the Boeing-funded research portfolio with Cambridge University.

The research was funded by The Boeing Company and by the UK Engineering and Physical Sciences Research Council (EPSRC). The National High Magnetic Field Laboratory, where the measurements were performed, is funded the National Science Foundation and the State of Florida. 


Contacts and sources:

Cell Division Synchronized To Cell And Body’s Daily Clock - Could Optimize Timing Of Chemotherapy And Explain Some Cancers Say Researchers

Research led by the University of Warwick’s Systems Biology Centre and Warwick Medical School in collaboration with groups in Nice and Rotterdam has been able to demonstrate how the cycle of cell division in mammalian cells synchronizes with the body’s own daily rhythm, its circadian clock.

Cancer Cells 
Credit: crafty_dame

The study not only helps to explain why people with sustained disrupted circadian rhythms can be more susceptible to cancer, it may also help establish the optimal time of day to administer chemotherapy.

In a paper entitled Phase locking and multiple oscillating attractors for the coupled mammalian clock and cell cycle just published in PNAS (Proceedings of the National Academy of Sciences) the researchers drew on an idea of clock synchronization first demonstrated in the 18th century when Dutch scientist Christian Huygens observed the synchronization of two pendulum clocks. The University of Warwick led research team wanted to establish if the two clocks within a mammalian cell (the gene based “clock” regulating the cycle of cell division and the separate gene based clock within the same cell that was regulated by the body’s circadian) were or could be synchronized in the same way.

Past researchers had failed to measure the clock mechanism behind normal circadian rhythms in single cells. The Warwick research team solved that by using multispectral imaging of single live cells, computational methods, and mathematical modelling to track the cycles of the two clocks and were able to observe (by making copies of the key genes that fluoresce) that that they were indeed synchronized with each other.

While trying to understand why this synchronization has not been seen before they discovered that the protocol used by circadian researchers to reset the clocks in cells so that their clocks progress in step with each other disrupted the 1:1 synchronization between the clocks and pushed them over into a new pattern in which there were 3 cell divisions every two clock periods. This ability of the clock and cell cycle to have multiple patterns of oscillatory behavior is a surprising discovery that has not been seen before in any cellular systems.

These new findings could provide a significant clue as to why people with sustained disrupted circadian rhythms such as those doing shift work can be more susceptible to cancer. If a person’s circadian rhythms are messed up that disruption will also directly impact on the timings of cell division allowing more rapid proliferation. As Professor David Rand the Director of the University of Warwick’s Systems Biology Centre who led the Warwick research team said:

“Robust phase locking between the mammalian clock and the cell cycle is of primary relevance to cancer because the clock is often disrupted or turned off in cancer cells allowing faster cell division and disorganization of the crucial anti-cancer cellular processes whose timing is regulated by the circadian clock inside each cell.”

As well as providing a significant clue to a cause of cancer this research underpins a method of how to pick an optimal time of day to administer chemotherapy. Most chemotherapy drugs targets and attack cells at a particular phase of the cell division cycle. In healthy cells where the clock and cell cycle are synchronized this will be at a particular time of the day while in cancer cells that are not synchronized cell division will be occurring all round the clock. Thus one can time the therapy to avoid hitting susceptible healthy cells while still hitting the full amount of susceptible cancer cells.

The European project that provided the funding for this project was led by the oncologist Professor Francis Levi who has just moved to the University of Warwick and the Queen Elizabeth Hospital in Birmingham from France. He has pioneered basic and clinical research in the field of circadian biology and its applications to cancer. The experiments were carried out in the laboratories of Dr Franck Delaunay in Nice and Dr Bert van der Horst in Rotterdam.


Contacts and sources:
Professor David Rand
University of Warwick Systems Biology Centre

Scientists Close To Catching Gravitational Wave

Catching a gravitational wave

When Albert Einstein proposed the existence of gravitational waves as part of his theory of relativity, he set in train a pursuit for knowledge that continues nearly a century later.

These ripples in the space-time continuum exert a powerful appeal because it is believed they carry information that will allow us to look back into the very beginnings of the universe. But although the weight of evidence continues to build, undisputed confirmation of their existence still eludes scientists.

Credit: University of Warwick

Researchers from University of Warwick and Monash University have provided another piece of the puzzle with their precise measurements of a rapidly rotating neutron star: one of the smallest, densest stars in the universe.

Neutron stars, along with colliding black holes and the Big Bang, may all be sources of gravitational waves.

In work published in The Astrophysical Journal, the Monash and Warwick scientists significantly improved the precision with which they could measure the orbit of Scorpius X-1, a double star system containing a neutron star that feeds off a nearby companion star. This interaction makes it the strongest source of X-rays in the sky apart from the sun.

Dr Duncan Galloway from the Monash Centre for Astrophysics said that the main difficulty in searching for gravitational waves emitted by Scorpius X-1 was the lack of precise knowledge about the neutron star’s orbit.

“We have made a concerted effort to refine Scorpius X-1’s orbit and other parameters, with the goal of significantly boosting the sensitivity of searches for gravitational waves,” Dr Galloway said.

“Detecting gravitational waves will open a new window for observation and allow us to study objects in the universe in a way that can’t be achieved using traditional astronomy techniques.”

Monash PhD student Ms Shakya Premachandra spent three months at the University of Warwick learning specific techniques and methods to improve the team’s measurements.

Under the guidance of Dr Danny Steeghs from Warwick’s Astronomy and Astrophysics Group, Ms Premachandra worked on the research data and learnt a specific software program developed by Warwick astronomers.

Dr Steeghs said he first started researching gravitational waves with Monash in 2009 and seed funding from the Monash Warwick Alliance has supported these efforts.

“With help from the Monash Warwick Alliance, we quickly identified a genuine opportunity to make substantial research progress by combining our expertise, which also led to an ambitious plan for continued collaboration,” Dr Steeghs said.

Dr Galloway and Ms Premachandra are members of the LIGO Scientific Collaboration, a world-wide network of more than 800 astronomers. Its work is complementary to that of the BICEP collaboration, which last month made headlines with its analysis of gravitational waves in the afterglow of the Big Bang, called the cosmic microwave background.

The Monash Warwick Alliance, which supports this research project and many others, is an innovative approach to higher education that is accelerating the exchange of people, ideas and information between Monash and Warwick Universities.


Contacts and sources:
Tom Frew
 University of Warwick

Saturday, June 28, 2014

A Rain Storm On The Sun With Droplets Each As Big As Ireland

Just like on Earth, the Sun has spells of bad weather, with high winds and showers of rain. But unlike the all-too-frequent storms of the UK and Ireland, rain on the Sun is made of electrically charged gas (plasma) and falls at around 200,000 kilometres an hour from the outer solar atmosphere, the corona, to the Sun's surface. And the thousands of droplets that make up a 'coronal rain' shower are themselves each as big as Ireland.

A mosaic of images obtained using the Swedish Solar Telescope (SST), revealing evidence of a large-scale coronal rain shower pouring relentlessly into the dark sunspot on the surface of the Sun. The coronal rain shower appears as the labelled giant arching water-fall-like flow. At the top left the Earth is depicted on the same scale.

Credit: E. Scullion / SST

Now a team of solar physicists, led by Dr Eamon Scullion of Trinity College Dublin, have pieced together an explanation for this intriguing phenomenon, with imagery that shows a 'waterfall' in the atmosphere of the Sun. Dr Scullion presented their work at the National Astronomy Meeting (NAM 2014) in Portsmouth on Tuesday 24 June 2014.

Discovered almost 40 years ago, solar physicists are now able to study coronal rain in great detail thanks to state-of-the-art satellites like the NASA Solar Dynamics Observatory (SDO) and ground-based observatories like theSwedish 1-m Solar Telescope (SST). The scientists see regular and massive shifts in the solar 'climate', but despite decades of research have until now been unable to understand the physics of coronal rain.

It turns out that the process through which hot rain forms on the Sun is surprisingly similar to how rain happens on Earth. If the conditions in the solar atmosphere are just right, then clouds of hot, dense plasma can naturally cool and condense and eventually fall back to the solar surface as droplets of coronal rain.



In another parallel with terrestrial weather, the material that makes up the hot rain clouds reaches the corona through a rapid evaporation process. But here the evaporation is caused by solar flares, the most powerful explosions in the Solar system that are thought to help heat the Sun's outer atmosphere. The origins of solar coronal heating nonetheless remain one of the longest standing puzzles in solar physics.

The torrential rain storms, driven by solar flares, may play a fundamental role in controlling the mass cycling of the solar atmosphere and act as a kind of "solar-scale" thermostat in regulating the temperature fluctuations of the solar corona. Dr Scullion and his team have now developed a new insight into how coronal rain forms. Together with collaborators in Trinity College Dublin and the University of Oslo in Norway, he suggests a model of 'catastrophic cooling', where an exceptionally rapid fall in temperature causes material to change from rarefied coronal gas to 'raindrops'.

The team used images from the Swedish Solar Telescope based on La Palma in the Canary Islands, a telescope that produces some of the sharpest images of the Sun available. In June 2012 they observed a giant 'waterfall' of solar material pouring down from the outer atmosphere of the Sun into a dark sunspot on its surface. Another set of images have been assembled into a movie and show how a solar flare precedes a 'rain shower'.

Dr Scullion comments: "Showers of 'rain' and waterfalls on the Sun are quite something, though I wouldn't recommend taking a stroll there anytime soon. But the parallels with weather on Earth are both striking and surprising."


Contacts and sources:
Dr Eamon Scullion
Trinity College Dublin

Dr Robert Massey
Royal Astronomical Society

Puffing Sun Gives Birth To Reluctant Eruption

A suite of Sun-gazing spacecraft, SOHO, STEREO and Solar Dynamics Observatory (SDO), have spotted an unusual series of eruptions in which a series of fast 'puffs' force the slow ejection of a massive burst of plasma from the Sun's corona. The eruptions took place over a period of three days, starting on 17 January 2013. Images and animations of the phenomena were presented at the National Astronomy Meeting 2014 in Portsmouth by Nathalia Alzate on Monday 23 June.

One of the multiple jets that lead to the coronal 'puffs', observed by the Solar Dynamics Observatory .
The Sun's outermost layer, the corona, is a magnetised plasma that has a temperature of millions of degrees and extends millions of kilometres into space. The LASCO C2 coronagraph aboard the SOHO spacecraft observed puffs emanating from the base of the corona and rapidly exploding outwards into interplanetary space.

One of the multiple jets that lead to the coronal 'puffs', observed by the Solar Dynamics Observatory (SDO). A still from a movie which has three channels - red, green and blue, corresponding to three coronal temperature regimes ranging from ~0.8Mk to 2MK.


Credit: SDO/U. Aberystwyth

The puffs occurred approximately once every three hours; after about 12 hours, a much larger eruption of material began, apparently eased out by the smaller-scale explosions. By looking at high-resolution images taken by SDO and STEREO over the same time period and in different wavelengths, Alzate and her colleagues at the University of Aberystwyth were able to focus down on the cause of the puffs and the interaction between the small and large-scale eruptions.


 "Looking at the corona in Extreme UltraViolet light we see the source of the puffs is a series of energetic jets and related flares," explained Alzate. "The jets are localised, catastrophic releases of energy that spew material out from the Sun into space. These rapid changes in the magnetic field cause flares, which release a huge amount of energy in a very short time in the form of super-heated plasma, high-energy radiation and radio bursts. The big, slow structure is reluctant to erupt, and does not begin to smoothly propagate outwards until several jets have occurred."

Puffs emanating from the base of the corona explode outwards into interplanetary space, driving a larger, reluctant eruption of magnetized plasma. The sequence was observed by the LASCO C2 coronagraph aboard the SOHO spacecraft.

 Credit: SOHO/LASCO/U. Aberystwyth

Because the events were observed by multiple spacecraft, each viewing the Sun from a different perspective, Alzate and her colleagues were able to resolve the 3D configuration of the eruptions. This allowed them to estimate the forces acting on the slow eruption and discuss possible mechanisms for the interaction between the slow and fast phenomena.




"We still need to understand whether there are shock waves, formed by the jets, passing through and driving the slow eruption, or whether magnetic reconfiguration is driving the jets allowing the larger, slow structure to slowly erupt. Thanks to recent advances in observation and in image processing techniques we can throw light on the way jets can lead to small and fast, and/or large and slow, eruptions from the Sun," said Alzate.




Contacts and sources:
Nathalia Alzate
Institute of Maths, Physics & Computer Science (IMPACS)
Aberystwyth University

Friday, June 27, 2014

How The 'Pillars Of Creation' … Were Created

The 'Pillars of Creation', an image made with the Hubble Space Telescope in 1995, is one of the most famous astronomical views. It shows how 'elephant trunks' of cooler interstellar gas are eroded by the intense radiation and winds from nearby massive stars.

The famous Hubble Space Telescope image of the 'Pillars of Creation', from 1995
 Credit: NASA / ESA / STScI / J. Hester and P. Scowen (Arizona State University)

Now Scott Balfour, an astronomer at Cardiff University, has run a new simulation where similar structures appear with a remarkably close appearance to their real life counterparts. He also suggests that the stars that make these structures are of little help in forming new siblings. On Thursday 26 June Scott presented his results in a talk at the National Astronomy Meeting in Portsmouth.

A movie of the simulation, showing how the cloud collapses and forms 'elephant trunks' and bright rims over 1.6 million years. 
Credit: S. Balfour / University of Cardiff

The massive O-type stars, more than 16 times as 'heavy' as our Sun, have short but dramatic lives. During their most stable phase on the so-called main sequence, they have surface temperatures of more than 30,000 degrees Celsius (on the Sun the surface is about 5500 degrees), are strong sources of ultraviolet light and emit copious material in a powerful wind.

All of this shapes their surroundings. The O-type stars heat any interstellar gas in their vicinity, creating bubbles which act like snow ploughs sweeping up surrounding colder material. In these regions, where gas is compressed, large numbers of new stars are seen forming so many scientists argue that the O stars drive star formation.

In his new work, Scott has tried to test this idea by simulating the way the gas behaves over a period of 1.6 million years, a simulation that took several weeks of computing time to calculate. His model explored what would happen when a massive star forms in a smooth cloud of gas that is already collapsing under its own weight.

Light from the O-type star creates a bubble in the cloud as expected, but its future can follow one of three paths. It may expand forever; expand, contract a little and then become almost stationary or expand and then contract all the way back to the centre of the cloud. Scott found that only the second case leads to prolific star formation and even then only under very specific conditions.

 An image from the simulation, showing a slice of space 25 x 25 light years across and 0.2 light years thick (for reference 1 light year is about 9.6 million million km or a bit more than 63000 times the distance from the Earth to the Sun). The model depicts how a hot star in the centre of the cloud changes its surroundings over 1.6 million years, creating the ‘elephant trunks’ seen in Hubble imagery. Insets show close-ups of a pillar and bright rimmed cloud. 
Credit: S. Balfour / University of Cardiff

He comments: "If I'm right, it means that O-type and other massive stars play a much more complex role than we previously thought in nursing a new generation of stellar siblings to life."

His model also neatly replicates the bright rims and pillars seen in the Hubble image, which seem to form naturally along the outer edge of the bubble as it breaks up.

Scott adds: "The model neatly produces exactly the same kind of structures seen by astronomers in the classic 1995 image, vindicating the idea that giant O-type stars have a major effect in sculpting their surroundings."


Contacts and sources:
Dr Robert Massey
Royal Astronomical Society

Scott Balfour
University of Cardiff

New Study Pinpoints 'Lemur' Protein As Main Player In Spread Of Breast Cancer

Researchers have confirmed the role of a protein called Lemur Tyrosine Kinase 3 (LMTK3) in the spread of breast cancer to other parts of the body.

Previous studies have demonstrated that LMTK3 is involved in breast cancer but little has been discovered about how, where and why it influences the development of the disease.

Credit: Imperial College London

A group of scientists and clinicians from Imperial College London alongside other collaborators have made important headway into answering these questions, demonstrating that it plays a crucial role in enabling cancer cells to break away from the primary tumour site. This eventually results in the spread of the cancer to other parts of the body (such as bones, liver, brain), known as metastasis. The findings, published in Science Signalling, provide valuable clues as to how this devastating process could be stopped or controlled.

Using a mouse model, the researchers first demonstrated that overexpression of LMTK3 gene led to an increase in tumour growth and that at a molecular level LMTK3 was involved in the breaching of tissue barriers and the subsequent infiltration of cancer cells throughout the surrounding tissue, a process known as ‘invasion’, which is the first step in their spread to a remote organ. By examining samples from patient tumours, they ascertained some of the detailed mechanisms at work. They now aim to identify compounds that could inhibit LMTK3 activity and help prevent the spread of breast cancer.

“Our research shows an involvement of LMTK3 protein in metastasis,” said lead researcher Dr Georgios Giamas from the Department of Surgery and Cancer at Imperial College London. “LMTK3 is now on the map of well-established processes that are involved in the development of tumours and we have demonstrated that it promotes breast cancer cell invasion and migration or movement of cancer cells. This knowledge is valuable in identifying possible candidate compounds that could ‘control’ the action of LMTK3 and prevent the spread of cancer to other regions. We are now in the process of screening over 30,000 compounds to identify a selection of candidates that could be used in the development of a potential future drug.”

Professor Justin Stebbing from the Department of Surgery and Cancer Imperial College London who was involved with the translational (from bench to ‘bed-side’) significance of this work said: “We are integrating a hitherto largely unknown kinase into well-known signaling pathways that cause cancer cell invasion and spread. It places LMTK3, known now to play a role in therapy resistance across tumour types, as a valid therapeutic target.”

Yichen Xu, a PhD student at the Department of Surgery and Cancer and first author of the Science Signaling paper, further emphasized: “This is the first time LMTK3 has been placed in a well-known metastatic pathway, suggesting LMTK3 as a potential target for anti-metastasis therapy in breast cancer.”

Localised cancer is often curable by surgery to remove the tumour but when it spreads to other parts of the body it becomes more dangerous and difficult to treat. Metastatic breast cancer can be treated, but it cannot be cured. In approximately 90 per cent of breast cancer deaths the main cause is metastasis in remote organs. Metastasis happens through a series of stages starting with the growth of the primary tumour and followed by the cancerous cells breaking out and invading the blood stream. Once in the blood stream, the cancerous cells move to another location and finally invade another organ.

Having established that the over-expression of the LMTK3 gene causes tumour growth, the researchers investigated the role of this protein at the stage when the cancer cells break from the tumour and invade the blood stream. They discovered that LMTK3 promotes the deformation and mobility of the cancerous cells so they are ready to move out of the tumour and it also helps to break down the extracellular matrix (ECM) between the tumour and blood vessels, so the cells can burst through and move into the bloodstream.

Using molecular and cell biology techniques they further identified the specific molecular mechanisms at work, demonstrating that LMTK3 modulated several different proteins which suggests multiple pathways are at work. One of the most important proteins was Integrin β1 (ITGB1), which has already been implicated in the invasion process. Using tumour samples the researchers demonstrated that the greater the amount of LMTK3 present in a tumour, the greater the amount of ITGB1, indicating a link between these two proteins in enabling invasion by breast cancer cells.

With this detailed knowledge of the mechanisms at work the Imperial College researchers already have a drug development program underway starting with the screening of a large amount of chemical and natural compounds to identify prime candidates for LMTK3 inhibitors that could be used to treat the spread of breast cancer.Imperial Innovations is managing the prosecution of a patent application based on Professor Stebbing’s work around LMTK3. Imperial Innovations is the technology commercialisation and investment company that provides technology transfer services to Imperial College London.

This work was funded by the National Institute for Health Research, the Pink Ribbon Foundation, Action Against Cancer, the CSC Imperial Ph.D. Scholarships, the Sally Roter Ph.D. Studentship, Breast Cancer Campaign and Cancer Research UK.


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By Francesca Davenport