New Evidence That Comets Deposited Building Blocks of Life On Primordial Earth
May 09, 2012
New research reported in San Diego on March 27 at the 243rd National Meeting & Exposition of the American Chemical Society (ACS) provides further support for the idea that comets bombarding Earth billions of years ago carried and deposited the key ingredients for life to spring up on the planet.
Jennifer G. Blank, Ph.D., who led the research team, described experiments that recreated with powerful laboratory "guns" and computer models the conditions that existed inside comets when these celestial objects hit Earth's atmosphere at almost 25,000 miles per hour and crashed down upon the surface. The research is part of a broader scientific effort to understand how amino acids and other ingredients for the first living things appeared on a planet that billions of years ago was barren and desolate. Amino acids make up proteins, which are the workhorses of all forms of life, ranging from microbes to people.
"Our research shows that the building blocks of life could, indeed, have remained intact despite the tremendous shock wave and other violent conditions in a comet impact," Blank said. "Comets really would have been the ideal packages for delivering ingredients for the chemical evolution thought to have resulted in life. We like the comet delivery scenario because it includes all of the ingredients for life -- amino acids, water and energy."
Comets are chunks of frozen gases, water, ice, dust and rock that astronomers have termed "dirty snowballs." These snowballs, however, may be 10 miles or more in diameter. Comets orbit the sun in a belt located far beyond the most distant planets in the solar system. Periodically, comets break loose and hurtle inward, where they may become visible in the sky.
Billions of years ago, however, swarms of comets and asteroids bombarded Earth with the remnants still visible as craters on the moon. Scientific evidence suggests that life on Earth began at the end of a period 3.8 billion years ago called the "late heavy bombardment" that involved both comets and asteroids. Before that, Earth was too hot for living things to survive. The earliest known fossils with evidence of life date from 3.5 billion years ago. So how could life originate so quickly when there was little evidence of water or the amino-acid building blocks for making proteins?
Blank and colleagues at the Bay Area Environmental Research Institute NASA/Ames Research Center, Moffett Field, Calif., set out to check whether amino acids could remain intact after a comet's descent through Earth's atmosphere. Previous analyses of comet dust samples returned to Earth by a NASA spacecraft eliminated any doubt that amino acids do occur in comets.
In one set of experiments, they used gas guns to simulate the enormous temperatures and powerful shock waves that amino acids in comets would experience on upon entering Earth's atmosphere. The gas guns, devices that weigh thousands of pounds, hit objects with high-pressure blasts of gas moving at supersonic speeds. They shot the gas at capsules filled with amino acids, water and other materials.
The amino acids did not break down due to the heat and shock of the simulated crash. Indeed, they began forming the so-called "peptide bonds" that link amino acids together into proteins. The pressure from the impact of the crash apparently offset the intense heat and also supplied the energy needed to create the peptides, she explained. In other experiments, Blank's team used sophisticated computer models to simulate conditions as comets collided with Earth.
Blank suggested that there may well have been multiple deliveries of seedlings of life through the years from comets, asteroids and meteorites.
Pioneering engineers at the University of Strathclyde in Glasgow are developing an innovative technique based on lasers that could radically change asteroid deflection technology.
The research has unearthed the possibility of using a swarm of relatively small satellites flying in formation and cooperatively firing solar-powered lasers onto an asteroid -- this would overcome the difficulties associated with current methods that are focused on large unwieldy spacecraft.
Dr Massimiliano Vasile, of Strathclyde's Department of Mechanical and Aerospace Engineering, is leading the research. He said: "The approach we are developing would involve sending small satellites, capable of flying in formation with the asteroid and firing their lasers targeting the asteroid at close range.
"The use of high power lasers in space for civil and commercial applications is in its infancy and one of the main challenges is to have high power, high efficiency and high beam quality all at the same time.
"The additional problem with asteroid deflection is that when the laser begins to break down the surface of the object, the plume of gas and debris impinges the spacecraft and contaminates the laser. However, our laboratory tests have proven that the level of contamination is less than expected and the laser could continue to function for longer than anticipated."
Just over 100 years ago a 2000-kilometer area of vegetation was destroyed when an object believed to be 30-50 metres in diameter exploded in the skies above Tunguska, Siberia. While the likelihood of an immediate threat from a similar asteroid strike remains low, it is widely recognised that researching preventative measures is of significant importance.
Dr Vasile added: "The Tunguska class of events are expected to occur within a period of a few centuries. Smaller asteroids collide with Earth more frequently and generally burn in the atmosphere although some of them reach the ground or explode at low altitude potentially causing damage to buildings and people.
"We could reduce the threat posed by the potential collision with small to medium size objects using a flotilla of small agile spacecraft each equipped with a highly efficient laser which is much more feasible than a single large spacecraft carrying a multi mega watt. Our system is scalable, a larger asteroid would require adding one or more spacecraft to the flotilla, and intrinsically redundant -- if one spacecraft fails the others can continue."
Dr Vasile is now investigating the use of the same concept to remove space debris. The number of objects in orbit classified as debris is ever-increasing and with no widely accepted solution for their removal. Researchers at the University of Strathclyde believe the space-borne lasers could be used to lower the original orbit of the space debris and reduce the congestion.
Dr Vasile said: "The amount of debris in orbit is such that we might experience a so called Kessler syndrome -- this is when the density becomes so high that collisions between objects could cause an exponentially increasing cascade of other collisions.
"While there is significant monitoring in place to keep track of these objects, there is no specific system in place to remove them and our research could be a possible solution.
"A major advantage of using our technique is that the laser does not have to be fired from the ground. Obviously there are severe restrictions with that process as it has to travel through the atmosphere, has a constrained range of action and can hit the debris only for short arcs."
The research was carried out in collaboration with the University of Strathclyde's Institute of Photonics and was presented to the Planetary Society at the end of February. ?
Elusive Bururi Long-Fingered Frog Found After 62 Years
May 09, 2012
Herpetologists from the California Academy of Sciences and University of Texas at El Paso discovered a single specimen of the Bururi long-fingered frog (Cardioglossa cyaneospila) during a research expedition to Burundi in December 2011. The frog was last seen by scientists in 1949 and was feared to be extinct after decades of turmoil in the tiny East African nation.
For biologists studying the evolution and distribution of life in Africa, Burundi sits at an intriguing geographic crossroads since it borders the vast Congo River Basin, the Great Rift Valley, and the world's second largest freshwater lake, Lake Tanganyika. Many of the species in its high-elevation forests may be closely related to plants and animals found in Cameroon's mountains, suggesting that at some point in the past, a cooler climate may have allowed the forests to become contiguous.
Previous knowledge of Burundi's wildlife came from scientific surveys conducted in the mid-20th century, when the nation was under Belgian administration. But its history since then has been one of political unrest, population growth, and habitat loss. Today, approximately 10 million people occupy an area the size of Massachusetts, giving Burundi one of the highest population densities in Africa.
Academy curator David Blackburn joined his colleague Eli Greenbaum, professor at the University of Texas at El Paso, on the 2011 expedition with the goal of finding Cardioglossa cyaneospila, as well as other amphibians and reptiles first described 60 years ago. To their pleasant surprise, the habitats of the Bururi Forest Reserve in the southwest part of the country were still relatively intact, with populations of rare forest birds and chimpanzees present.
With little knowledge to go on except a hunch that C. cyaneospila would make a call like its possible close relatives in Cameroon, Blackburn finally found a single specimen on his fifth night in the forest.
"I thought I heard the call and walked toward it, then waited," said Blackburn. "In a tremendous stroke of luck, I casually moved aside some grass and the frog was just sitting there on a log. I heard multiple calls over the next few nights, indicating a healthy population of the species, but I was only able to find this one specimen."
The Bururi long-fingered frog is about 1.5 inches long, with a black and bluish-gray coloration. The males are notable for one extra-long finger on each foot, analogous to the "ring finger" in humans, whose purpose is unknown. Its closest relatives live in the mountains of Cameroon, more than 1,400 miles away.
The lone specimen collected, which now resides in the Academy's herpetology collection, can be used for DNA studies to determine how long the Cardioglossa species from Burundi and Cameroon have been genetically isolated from one another. The results will shed light on Africa's historical climate conditions, a topic that has far-reaching implications for understanding the evolution of life in the continent that gave rise to our own species.
In addition to locating the Bururi long-fingered frog, Blackburn and Greenbaum also documented dozens of other amphibians in Burundi, many of which had never before been recorded in the country. The team also discovered some species that may be new to science.
"Eventually, we will use the data from our expedition to update the IUCN conservation assessment for amphibians of Burundi," said Greenbaum. "Because Burundi is poorly explored, we've probably doubled the number of amphibian species known from the country. Once we demonstrate that Burundi contains rare and endemic species, we can work with the local community to make a strong case for preserving their remaining natural habitats."
New 'Electronic Skin' Patches Monitor Health Wirelessly
May 09, 2012
Like the colorful temporary tattoos that children stick to their arms for fun, people may one day put thin "electronic skin" patches onto their arms to wirelessly diagnose health problems or deliver treatments. A scientist recently reported on the development of "electronic skin" that paves the way for such innovations at the 243rd National Meeting & Exposition of the American Chemical Society (ACS).
John Rogers, Ph.D., said the patches have the potential to eliminate the need for patients to stay tethered to large machines in a doctor's office or hospital room for hours of treatment or monitoring. Each year, hundreds of thousands of patients worldwide have electroencephalograms, electrocardiograms and electromyograms to check the health of their brains, hearts or muscles.
The procedures are uncomfortable, Rogers explained, with patients hooked to machines by cumbersome wires or pins adhering to the skin with gels or tape that can be painful to remove and can leave a sticky residue. More importantly, the tests detect brain, heart and muscle activity while patients are in a medical setting, rather than carrying out activities of everyday life.
"A key feature of our epidermal electronics is its natural interface to the body, without wires, pins, adhesives or gels, to allow a much more comfortable and functional system," said Rogers. "The technology can be used to monitor brain, heart or muscle activity in a completely noninvasive way, while a patient is at home."
The electronic skin patches are about the thickness of a human hair, and wearers can't feel them on their skin. They could even be covered up with a real temporary tattoo. Despite their miniscule dimensions, the patches can pack full-scale electronic circuits needed to monitor health status with wireless capabilities that can, with future development, be used to transmit data to the patient's cell phone and on to the doctor's office.
Rogers and colleagues at the University of Illinois at Urbana-Champaign developed the patches to not only be flexible, but stretchable to move with the natural motions of the skin as people go about their normal business. This was a big challenge, however. Silicon-based wafers are typically used for electronics, such as laptops and smartphones. But these wafers are hard and brittle, like glass. To get these onto a material that bends and stretches like skin or rubber, they had to use very small pieces in a wavy pattern. "We had to structure the system in a strategic way that would avoid any strains or stresses that would crack or fracture these tiny bits of silicon," Rogers explained.
The patches are transferred to the skin just like a temporary tattoo, with water and a backing that peels off. The first versions wore off after a day or sooner if they got wet. The latest version is applied in the same way, but a modified form of the spray-on bandages sold in drugstores is applied over the patch. The spray protects the circuit from water and normal wear-and-tear and keeps it on the skin for up to a week. In this format, the devices can accommodate transpiration, sweat and even washing with soapy water.
"We've also figured out how to make the devices operate in a bi-directional way," Rogers explained. "The older devices only measure what's going on in the body. Our newest patch can measure muscle activity and stimulate the muscles. That's useful for rehabilitation after an accident or long periods of bed rest or even for helping people move prosthetic limbs more easily." And with plans to add Wi-Fi capabilities, electronic skin could also send information back to a physician.
A company Rogers co-founded called mc10 is going a step further and putting the patches on medical instruments that go inside the body, such as catheters, which are balloon-like tubes used in heart surgery. The electronic skin patch is placed on the outside surface of the catheter. When the catheter expands in the heart, the patch expands with it and touches the inside of the heart, taking measurements used to guide surgery.
Rogers said the patches also could have applications in other areas useful for the consumer. For example, new devices allow monitoring and depth-profiling of skin hydration, with relevance in sports, skin-care and cosmetics, alike.
More Economical Way to Produce Cleaner, Hotter Natural Gas
May 09, 2012
New technology is offering the prospect of more economical production of a concentrated form of natural gas with many of the advantages -- in terms of reduced shipping and storage costs -- of the familiar frozen fruit juice concentrates, liquid laundry detergents and other household products that have been drained of their water, scientists reported in San Diego on March 27.
They told the 243rd National Meeting & Exposition of the American Chemical Society (ACS), the world's largest scientific society, that this "super natural gas" would burn hotter than the familiar workhorse fuel and occupy about 40 percent less space in pipelines, railroad tank cars and storage chambers. But its potential benefits range beyond that -- to making natural gas a better source of hydrogen for use in fuel-cell-powered cars in the much-discussed "hydrogen economy" of the future, according to Mohammad G. Rabbani, Ph.D., who reported on the study and is a research scientist in the team of Hani El-Kaderi, Ph.D.
"Natural gas has a reputation among the public as a clean-burning fuel, and that is true," said El-Kaderi. "Compared to coal and oil, burning natural gas releases small amounts of pollutants and less carbon dioxide, the main greenhouse gas. People may not realize, however, that natural gas straight from the well often is contaminated with carbon dioxide and other undesirable gases, such as sulfur dioxide and nitrogen oxides, that are highly corrosive, increase its volume and decrease its heating value. Our new porous polymers, which have exceptionally high thermal and chemical stabilities, remove that carbon dioxide and do it better than any other solid, porous material."
Scientists are searching for such new solid materials to purify natural gas, and the quest has grown more intense as reserves of high-quality gas, lower in contaminants and higher in heating value, grow scarcer, and concerns about global warming due to carbon dioxide continue. The traditional process for purifying natural gas, performed for decades, uses liquids to capture and separate the carbon dioxide and other gases. The process, however, is far from ideal, and scientists are seeking solids and other materials that can more efficiently capture the carbon dioxide, and then can be purged of the gas more economically, recycled and reused time and again. "Our theoretical studies on variable mixtures of CO2/CH4 have actually indicated that these polymers would have high selectivities for CO2," said Thomas E. Reich, Ph.D., who performed these theoretical investigations as a part of his doctoral research in the El-Kaderi group.
El-Kaderi's group developed purely organic polymers termed benzimidazole-linked polymers (BILPs) that are riddled with nano-engineered, minute, empty chamber-like pores so small that thousands would fit on the period at the end of this sentence. When exposed to streams of natural gas, the pores absorb and trap its carbon dioxide. When all of the pores are full of carbon dioxide, the BILPs can be run through a low-pressure processing unit to remove the carbon dioxide and prepare them for reuse.
Rabbani, who is in El-Kaderi's team at Virginia Commonwealth University in Richmond, noted that the new material is as effective at capturing carbon dioxide as monoethanolamine, the most common nitrogen-based liquid used for carbon dioxide scrubbing. Amine liquids have a disadvantage, however, in that they must be purged of carbon dioxide by heating, which requires more energy than the BILPs, which are regenerated under low-pressure conditions.
El-Kaderi said the BILPs seem well-suited for removing the traces of carbon dioxide that remain in hydrogen produced with existing technology. "Carbon dioxide can account for 20 percent of the finished product, the hydrogen, and if we consider a true hydrogen economy of the future, we should be removing that carbon dioxide. Our technology appears to be an excellent candidate."
The scientists acknowledged funding from Virginia Commonwealth University and the U.S. Department of Energy, Basic Energy Sciences.
New Dimension for Solar Energy: Innovative 3-D Designs More Than Double the Solar Power Generated Per Area
May 09, 2012
Intensive research around the world has focused on improving the performance of solar photovoltaic cells and bringing down their cost. But very little attention has been paid to the best ways of arranging those cells, which are typically placed flat on a rooftop or other surface, or sometimes attached to motorized structures that keep the cells pointed toward the sun as it crosses the sky.
Now, a team of MIT researchers has come up with a very different approach: building cubes or towers that extend the solar cells upward in three-dimensional configurations. Amazingly, the results from the structures they've tested show power output ranging from double to more than 20 times that of fixed flat panels with the same base area.
The biggest boosts in power were seen in the situations where improvements are most needed: in locations far from the equator, in winter months and on cloudier days. The new findings, based on both computer modeling and outdoor testing of real modules, have been published in the journal Energy and Environmental Science.
"I think this concept could become an important part of the future of photovoltaics," says the paper's senior author, Jeffrey Grossman, the Carl Richard Soderberg Career Development Associate Professor of Power Engineering at MIT.
The MIT team initially used a computer algorithm to explore an enormous variety of possible configurations, and developed analytic software that can test any given configuration under a whole range of latitudes, seasons and weather. Then, to confirm their model's predictions, they built and tested three different arrangements of solar cells on the roof of an MIT laboratory building for several weeks.
While the cost of a given amount of energy generated by such 3-D modules exceeds that of ordinary flat panels, the expense is partially balanced by a much higher energy output for a given footprint, as well as much more uniform power output over the course of a day, over the seasons of the year, and in the face of blockage from clouds or shadows. These improvements make power output more predictable and uniform, which could make integration with the power grid easier than with conventional systems, the authors say.
The basic physical reason for the improvement in power output -- and for the more uniform output over time -- is that the 3-D structures' vertical surfaces can collect much more sunlight during mornings, evenings and winters, when the sun is closer to the horizon, says co-author Marco Bernardi, a graduate student in MIT's Department of Materials Science and Engineering (DMSE).
The time is ripe for such an innovation, Grossman adds, because solar cells have become less expensive than accompanying support structures, wiring and installation. As the cost of the cells themselves continues to decline more quickly than these other costs, they say, the advantages of 3-D systems will grow accordingly.
"Even 10 years ago, this idea wouldn't have been economically justified because the modules cost so much," Grossman says. But now, he adds, "the cost for silicon cells is a fraction of the total cost, a trend that will continue downward in the near future." Currently, up to 65 percent of the cost of photovoltaic (PV) energy is associated with installation, permission for use of land and other components besides the cells themselves.
Although computer modeling by Grossman and his colleagues showed that the biggest advantage would come from complex shapes -- such as a cube where each face is dimpled inward -- these would be difficult to manufacture, says co-author Nicola Ferralis, a research scientist in DMSE. The algorithms can also be used to optimize and simplify shapes with little loss of energy. It turns out the difference in power output between such optimized shapes and a simpler cube is only about 10 to 15 percent -- a difference that is dwarfed by the greatly improved performance of 3-D shapes in general, he says. The team analyzed both simpler cubic and more complex accordion-like shapes in their rooftop experimental tests.
At first, the researchers were distressed when almost two weeks went by without a clear, sunny day for their tests. But then, looking at the data, they realized they had learned important lessons from the cloudy days, which showed a huge improvement in power output over conventional flat panels.
For an accordion-like tower -- the tallest structure the team tested -- the idea was to simulate a tower that "you could ship flat, and then could unfold at the site," Grossman says. Such a tower could be installed in a parking lot to provide a charging station for electric vehicles, he says.
So far, the team has modeled individual 3-D modules. A next step is to study a collection of such towers, accounting for the shadows that one tower would cast on others at different times of day. In general, 3-D shapes could have a big advantage in any location where space is limited, such as flat-rooftop installations or in urban environments, they say. Such shapes could also be used in larger-scale applications, such as solar farms, once shading effects between towers are carefully minimized.
A few other efforts -- including even a middle-school science-fair project last year -- have attempted 3-D arrangements of solar cells. But, Grossman says, "our study is different in nature, since it is the first to approach the problem with a systematic and predictive analysis."
David Gracias, an associate professor of chemical and biomolecular engineering at Johns Hopkins University who was not involved in this research, says that Grossman and his team "have demonstrated theoretical and proof-of-concept evidence that 3-D photovoltaic elements could provide significant benefits in terms of capturing light at different angles. The challenge, however, is to mass produce these elements in a cost-effective manner."
The novel H1N1 flu pandemic in 2009 underscored weaknesses in methods widely used to diagnose the flu, from frequent false negatives to long wait times for results. Now a four-year, National Institutes of Health-funded study of 146 patients with flu-like symptoms spearheaded by Associate Professor Catherine Klapperich (BME, MSE) has validated a prototype rapid, low-cost, accurate, point-of-care device that promises a better standard of care. Once optimized and deployed in the clinic, the new device could provide clinicians with an effective tool to quickly diagnose both seasonal and pandemic strains of influenza, and thus limit the spread of infection.
The study's research team -- Klapperich, Qingqing Cao(ME PhD'11), Madhumita Mahalanabis(BME postdoctoral fellow), Jessie Chang (BME MS'10), Brendan Carey (BME'11), Christopher Hsieh (BME'11) and Ahjegannie Stanley (summer intern) from the College of Engineering; medical personnel from the Boston University Medical Center (BUMC) Emergency Department; and an infectious disease physician from Beth Israel Deaconess Medical Center (BIDMC)/ Harvard Medical School -- published its findings in the March 22 online edition of PLoS ONE.
To produce a faster, cheaper, highly accurate flu diagnostic test that could be run at the point of care, the researchers miniaturized an expensive, three-hour, lab-scale diagnostic test -- known as RT-PCR and now considered the gold standard in flu detection -- into a single-use microfluidic chip. About the size of a standard microscope slide, the integrated chip consists of a column at the top that extracts RNA from signature proteins in the sample associated with the influenza A virus; a middle chamber that converts the RNA into DNA; and a climate-controlled lower channel used to replicate the DNA in sufficient quantities so it can be detected by an external reader.
Working with two types of nasal specimens, the researchers used the chip to produce results that matched the high accuracy and relatively fast turn-around time of the lab-scale method.
"We wanted to show that our technique was feasible on real-world samples prepared on the chip," said Klapperich. "Making each chip single-use decreases the possibility of cross-contamination between specimens, and the chip's small size makes it a good candidate for true point-of-care testing."
The microfluidic chip also proved far more effective than other commonly used flu diagnostic tests including viral culture, a lab procedure requiring up to a week to produce results; rapid immunoassays, which work like pregnancy tests but were only 40 percent reliable in detecting the presence of a flu virus in this study; and direct fluorescent antigen testing (DFA), a more accurate but labor-intensive process in which medical personnel prepare and interpret samples stained with fluorescent antibodies.
"The new test represents a major improvement over viral culture in terms of turn-around time, over rapid immunoassay tests in terms of sensitivity (ability to detect the virus from minimal sample material) and over DFA and RT-PCR in terms of ease of use and portability," Klapperich observed.
Ultimately seeking to enable clinicians to use their microfluidic chips for frontline flu virus detection, the researchers next plan to optimize their method so that it can produce results in a third less time (an hour) with chips that cost half as much to make (five dollars). In addition, they are exploring ways to develop a lower cost external reader that's no bigger than a clinical digital thermometer.
Deepest Ever High-Resolution Radio Survey of Hubble Deep Field Begun
May 09, 2012
A team of astronomers at Jodrell Bank Observatory have begun the deepest ever high-resolution radio imaging of the region around the Hubble Deep Field (HDF), the images originally captured by the Hubble Space Telescope (HST) in the mid 1990s. The HDF led to the discovery of numerous galaxies billions of light years distant and provided direct visual evidence of the evolution of the Universe. First results from the new imaging, which uses observations from the UK's newly upgraded e-MERLIN radio telescope array together with the EVLA radio array based in New Mexico, show galaxies some 7 billion light years away in unprecedented detail.
Graduate student Nick Wrigley presented the new results at the National Astronomy Meeting in Manchester on 27 March 2012.
e-MERLIN is an array of radio telescopes distributed across the United Kingdom connected together by optical fibres. Data from each telescope is sent across this network to Jodrell Bank where a device known as a 'correlator' processes them into a single image. This technique, known as interferometry, simulates a single radio telescope hundreds of kilometres across and produces exceptionally sharp images of astronomical objects.
EVLA is a similar more compact array in New Mexico in the United States that shows the coarser structure of objects and complements the e-MERLIN observations. The two arrays started to survey the HDF region in 2011 and the team expect the project to be completed in the next few years.
The first wide-band images of the whole HDF region capture the brightest objects in the field at sub-arcsecond resolution, equivalent to being able to distinguish a ten pence piece at a distance of over 5 kilometres. The pictures were assembled by Mr Wrigley under the supervision of Dr Rob Beswick and Dr Tom Muxlow at the Jodrell bank Centre for Astrophysics in Manchester. The image in the background, observed using the EVLA, shows the unresolved emission from whole galaxies, whereas the inset images produced using mapping in combination with e-MERLIN show the fine detail.
The high resolution provided by e-MERLIN allows astronomers to distinguish between the different types of galaxies, identifying those that have emission from material being dragged into supermassive black holes (so called Active Galactic Nuclei or AGNs) and those where the emission originates from rapid star formation or starbursts. The HDF galaxies are so far away that the light we see from them left as long ago as 12 billion years ago, so the new radio observations are giving us an insight into the formation of stars when the universe was less than 10% of its present age.
This new work is just the start of a multi-year survey of the HDF and provides a glimpse of the capabilities of wide-band (broadband data transmission) synthesis imaging now possible with simultaneous use of the e-MERLIN and EVLA arrays. Crucially, the e-MERLIN and EVLA correlators now generate compatible data allowing future observations to be combined like never before.
The first images were made with relatively short exposure times, but the whole project, named e-MERGE (led by Dr. Tom Muxlow (Manchester), Prof. Ian Smail (Durham) & Prof. Ian McHardy (Southampton)) will include long observations gathered at various wide-bands within the radio spectrum generating an unsurpassed combination of sensitivity and detail. The survey will ultimately measure massive star formation and AGN activity in very distant galaxies, tracing the development of the stellar populations and black hole growth in the very first large galaxies. Using the more accurate observations from e-MERLIN, it will be possible to produce more precise models of the physical process of star formation within star clusters in such galaxies and help to answer some of the many questions faced by cosmologists today.
Chemical Microgradients Accelerate Coral Death at the Great Barrier Reef
May 09, 2012
Researchers of the Max Planck Institute for Marine Microbiology along with Australian colleagues, have examined corals from the Great Barrier Reef affected by the Black Band Disease and identified the critical parameters that allow this prevalent disease to cause wide mortality of corals around the world. Corals infected with Black Band show a characteristic appearance of healthy tissue displaced by a dark front, the so called Black Band, which leaves the white limestone skeleton of the coral animal exposed. The dark front is commonly one to two centimetres broad and consists of a complex microbial community among which there are phototrophic cyanobacteria, sulfur oxidizing bacteria and sulfate reducing microorganisms.
The corals and their endosymbiotic algae are struck by three stress factors at once: toxic sulfide, anoxia, and a low pH at the boundary of the bacterial mat and the coral tissue.
The scientists investigated the tissue lesions with microsensors for oxygen, sulfide and pH. These microprobes have a tip diameter in the micrometre range and allow the scientists to measure highly resolved depth profiles in the coral tissue. They identified big differences between infected tissue and tissue in the preliminary stage of the disease: "In diseased coral tissue two zones develop: A phototrophic zone at the top in which the cyanobacteria produce oxygen and a lower anoxic zone in which the bacteria degrade the necrotic coral tissue. Sulfide is formed in the degradation process," Martin Glas of the Max Planck Institute in Bremen explains the results. "In tissue that is only slightly infected the zonation is not nearly that strong. Usually we could not detect sulfide, and oxygen penetrated deep into the bacterial mat."
At the front of the dark zone the conditions are particularly detrimental for the corals. The increased sulfide concentration around the necrosing tissue and the resulting decrease in oxygen leads to the spreading of the lesions to the surrounding, healthy tissue; a positive feedback that causes rapid migration of the Black Band Disease.
"We assume that the biogeochemical conditions at the surface of the coral tissue are responsible for the fast spreading of the disease. The higher the sulfide concentrations are and the less oxygen there is, the faster the dark front is migrating," Martin Glas describes the causes for the origin and the high virulence of the disease. So far, at least, the scientists have not identified a pathogen that could be responsible for the necrosis of the coral tissue. "Our measurements show that the Black Band Disease can migrate at one centimetre per day in the summer months. At this speed, within a very short time, whole coral colonies can die and the population size of many coral species on the reef can number of species in the reef can drastically decline," says Martin Glas.
For several years, David Bourne of the Australian Institute of Marine Science in Townsville and his colleague Yui Sato have been performing monitoring programs on the condition of coral reefs in which they also examined the coral diseases in the Great Barrier Reef. David Bourne says: „Presumably the Black Band Disease is one of the most frequently reported diseases in tropical reefs. One major cause is the seasonally high water temperature. Thus, results from this study allow us to understand at the micro-scale how the environmental conditions and the complex microbial community interact to result in the onset and progression of this coral disease."
Is there any cure for the reefs? "If the temperature decreases in winter the disease is stagnant. However, with increasing frequency the disease recurs in the next year. The bare coral skeleton can be overgrown by new polyps. But this may take many years," as Yui Sato of the James Cook University states.
Cassini Makes Simultaneous Measurements of Saturn's Nightside Aurora and Associated Electric Current System
May 09, 2012
Since the NASA / ESA Cassini-Huygens spacecraft arrived at Saturn in 2004, astronomers and space scientists have been able to study the ringed planet and its moons in great detail. Now, for the first time, a team of planetary scientists have made simultaneous measurements of Saturn's nightside aurora, magnetic field, and associated charged particles. Together the fields and particle data provide information on the electric currents flowing that produce the emissions.
Team leader Dr Emma Bunce of the University of Leicester will present the new work at the National Astronomy Meeting in Manchester on 27 March 2012.
Generally, images of the aurora (equivalent to the terrestrial 'northern lights') provide valuable information about the electromagnetic connection between the solar wind, the planet's magnetic field (magnetosphere) and its upper atmosphere. Variations in the aurora then provide information on changes in the associated magnetosphere. But viewing the aurora (best done at a large distance) at the same time as measuring the magnetic field and charged particles at high latitudes (where the aurora is found, best done close to the planet) is hard
In 2009, Cassini made a crossing of the magnetic field tubes that connect to the aurora on the night side of Saturn. Because of the position of the spacecraft, Dr Bunce and her team were able to obtain ultraviolet images of the aurora (which manifests itself as a complete oval around each pole of the planet) at the same time.
This is the first time it has been possible to make a direct comparison between Cassini images of the nightside aurora and the magnetic field and particle measurements made by the spacecraft. And because of the geometry of the orbit at Cassini, it took about 11 hours to pass through the high-latitude region or about the same time it takes Saturn to make one rotation.
This meant that the team were able to watch the auroral oval move as the planet turned. As Saturn and its magnetosphere rotated, the auroral oval was tilted back and forth across the spacecraft with a speed that is consistent with a planetary rotation effect:
Dr Bunce comments: "With these observations we can see the simultaneous motion of the electric current systems connecting the magnetosphere to the atmosphere, producing the aurora. Ultimately these observations bring us a step closer to understanding the complexities of Saturn's magnetosphere and its ever elusive rotation period."
New Twist On 1930s Technology May Become a 21st Century Weapon Against Global Warming
Far from being a pipe dream years away from reality, practical technology for capturing carbon dioxide -- the main greenhouse gas -- from smokestacks is aiming for deployment at coal-fired electric power generating stations and other sources, scientists saidin San Diego March 27. Their presentation at the 243rd National Meeting of the American Chem...
May 10, 2012
Transparent, Flexible '3-D' Memory Chips May Be the Next Big Thing in Small Memory Devices
New memory chips that are transparent, flexible enough to be folded like a sheet of paper, shrug off 1,000-degree Fahrenheit temperatures -- twice as hot as the max in a kitchen oven -- and survive other hostile conditions could usher in the development of next-generation flash-competitive memory for tomorrow's keychain drives, cell phones and comp...
May 10, 2012
Researchers Discover a New Path for Light Through Metal
Helping bridge the gap between photonics and electronics, researchers from Purdue University have coaxed a thin film of titanium nitride into transporting plasmons, tiny electron excitations coupled to light that can direct and manipulate optical signals on the nanoscale. Titanium nitride's addition to the short list of surface-plasmon-supporting m...