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Thursday, March 31, 2011

Novel Technique Reveals How Glaciers Sculpted Their Valleys

The beautiful and distinctive U-shaped glacial valleys typical of alpine areas from Alaska to New Zealand have fascinated and frustrated geologists for centuries.

While it seems obvious that glaciers scoured the bedrock for millions of years, what the landscape looked like before glaciers appeared, and how the glaciers changed that landscape over time, have remained a mystery. The glaciers erased all the evidence.

A numerical model provides snapshots every 250,000 years of the evolution of the Neale Burn drainage in Fiordland, New Zealand, during the last 2.5 million years. Over this time, the glacier cut into the flanks of the mountain at the mouth of the drainage, and later cut further toward the headwaters. The white line in the upper panel is the centerline of the Neale Burn valley, while the dots show the location of elevation profiles referred to in the lower panel. The middle panel shows the local lowering rate (i.e., erosion rate minus uplift rate) along this profile, as calculated for the preceding 250,000 years of each time frame.
Credit: David Shuster and Kurt Cuffey, UC Berkeley

Now, University of California, Berkeley, and Berkeley Geochronology Center (BGC) scientists have employed a clever technique to reconstruct the landform history of a 300-square-mile area of Fiordland in New Zealand, from the early Pleistocene some 2.5 million years ago, when the world cooled and glaciers formed, through today's warmer interglacial period.

"The first question we asked was, how much of the current landscape and relief is a result of glacial erosion?" said David Shuster, who developed the novel technique, called helium-4/helium-3 thermochronometry. "The answer is, all of it."

Shuster is an associate adjunct professor of earth and planetary science at UC Berkeley and a geochemist at the Berkeley Geochronology Center.

"Geologists have wondered, what did the landscape look like 200,000 years ago, or 400,000 years ago, or back before the Pleistocene glaciations began?" said glaciologist Kurt Cuffey, professor and chair of geography and a professor of earth and planetary science at UC Berkeley. "Did the valleys start out as V-shaped canyons submerged in ice, and the glacier just widened and deepened them? Or perhaps the relief was sculpted by glaciation, and it didn't matter what the rock landscape looked like before."

"David's work opens up a whole new world of investigation to tell us how the alpine landscape progressed, with implications for how glaciers today act on the landscape," he said.

Shuster, Cuffey, UC Berkeley graduate student Johnny Sanders and BGC researcher Greg Balco report their conclusions in the April 1 issue of the journal Science.

Glaciers carved their mouths first, then their heads

The team found that in the Fiordland, a well-known tourist destination in the Southern Alps of New Zealand, the rock currently on the surface was about 1.5 miles (2 kilometers) underground when the glaciers began forming about 2.5 million years ago. Since then, the mountains rose as a result of tectonic activity, while the glaciers flowed downhill, scouring the landscape and gouging U-shaped valleys on their way to the sea.

What surprised the geologists was that most of the valley-making occurred at the downstream mouths of glaciers for the first million years, essentially stopping about 1.5 million years ago. For the next million years, until about 500,000 years ago, erosion took place primarily at the heads of glaciers, which steadily ate into their headwalls, characterized by steep, amphitheater-like cirques. As a result, the deep valleys advanced up their drainage basins toward the range divide, producing razorback ridges in the process.

"Apparently, the heads of glaciers would be directly opposite one another on either side of a high ridge, and faster erosion at the headwalls caused the glaciers to eat their way inward to the spine of the mountain range, farther from the glacier's outlet," Cuffey said.

Major changes to the mountain topography essentially stopped about half a million years ago. The current interglacial period started about 12,000 years ago, after warming temperatures caused the glaciers to melt and recede. The fact that these Fiordland valleys are now ice-free allowed the researchers to collect surface rock samples from 33 sites in four glacial valleys over six days with the assistance of a helicopter. The valleys end in Milford Sound or Lake Te Anau.

Temperature as a proxy for depth

Shuster developed helium-4/helium-3 thermochronometry while a graduate student at Caltech, from which he obtained his Ph.D. in 2005. The technique makes it possible to determine the temperature of a mineral as it cooled over geological time. Because temperature increases with depth, the temperature history of the mineral tells how deeply it was buried over a period of millions of years.

"The technique allows us to collect samples from the present surface and, based on observations, infer how they cooled through 80 degrees Celsius to 20 degrees Celsius (176 to 68 Fahrenheit) over the last few million years, and thus, how deep they were when they cooled," Shuster said.

At the moment, the technique works only with crystals of apatite, a calcium phosphate mineral found mainly in plutonic rocks, such as granite, that solidify from magma deep underground. The apatite crystals contain uranium and thorium, which over millions of years decay radioactively, producing helium-4. The helium gradually leaks out of the crystal into the surrounding rock, but the rate of leakage decreases as the crystal cools.

Using special equipment at the BGC, the geologists were able to date the cooling of the minerals by measuring the amount of uranium and thorium in each crystal as well as the total amount of helium-4. The new technique involves irradiating the crystal with a proton beam to create helium-3, then measuring the outgassing of both helium isotopes to obtain a cross section of the helium-4 concentration in the crystal. They then calculated the crystal's cooling history based on the helium diffusion rate.

The samples, all of them younger than 2.5 million years, showed a large range of temperature, and thus depth, histories. Cuffey and Shuster used a computer model to test various scenarios and concluded that only one fit the data: Glaciers initially scoured the U-shaped valleys on the flanks of the mountain range, and only later began eating away at their headwater regions, including cirques and drainage divides.

"… this morphology resembles modern analogs in Norway and Antarctica, where steep valley ramps descend to level floors," the authors wrote.

The common thread is that the rock erodes faster where the ice sits on a steep slope, they said. Thus, the erosion rate of a glacier is greatest where the flowing river of ice descends steeply downstream.

"This scenario is consistent with a subglacial erosion rate dependent on ice sliding velocity, but not ice discharge," Shuster said.

Cuffey, coauthor with W. S. B. Paterson of the fourth edition of the book "The Physics of Glaciers" (2010), hopes to use the new information to improve computer models of glacial sculpting of landscapes. Meanwhile, Shuster and Cuffey plan to apply thermochronometry to chart the history of Yosemite National Park before and after the arrival of Pleistocene glaciers, going back as far as 40 million years into the Cenozoic era.

The research was supported by the National Science Foundation. The work of the BGC was supported by the Ann and Gordon Getty Foundation.




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Climate Change And Evolution Of Cross River Gorillas

Two species of gorillas live in central equatorial Africa. Divergence between the Western gorillas (Gorilla gorilla) and Eastern Gorillas (G. beringei) began between 0.9 and 1.6 million years ago and now the two species live several hundred kilometres apart. New research published by BioMed Central's open access journal BMC Evolutionary Biology shows that the divergence of Western lowland gorillas and the Critically Endangered Cross River gorillas (G. g. diehli) occurred more recently, about 17,800 years ago, during the Pleistocene era.

Western gorilla
Credit: Wikipedia

Eastern Gorilla
Credit: Wikipedia

An evolutionary model of the two subspecies of Western gorillas was generated using microsatellite genotyping of living gorillas and 100 year old museum specimens. This data showed that, although Cross River gorillas diverged from Western lowland gorillas about 17,800 years ago, the two subspecies continued to intermittently interbreed. Drs Thalmann and Wegmann suggest that climate change during the Pleistocene era caused the forests to expand, permitting the Western gorillas to expand their range. When the forest contracted again the gorillas were separated into two populations which began to diverge. Successive rounds of climate change resulted in periods when the two subspecies could interbreed followed by repeated episodes of isolation of the Cross River population.

The model indicates that gene flow finally stopped between the two subspecies approximately 420 years ago. Over the last 320 years ago there has been a 60% decrease in the numbers of Cross River gorillas causing a loss of genetic diversity within the population. Dr Thalmann said, "The number of Cross River gorillas has continued to decrease, probably due to anthropogenic pressure, such as destruction of their habitat or hunting by humans. There are thought to be fewer than 300 individuals left."

He continued "It is unclear what effect this loss of genetic diversity will have on the long term viability of Cross River gorillas. But, given that this bottleneck occurred so recently, it is possible that if the population was allowed to expand the loss of diversity could be stopped."

Historical sampling reveals dramatic demographic changes in western gorilla populations
Olaf Thalmann, Daniel Wegmann, Marie Spitzner, Mimi Arandjelovic, Katerina Guschanski, Christoph Leuenberger, Richard A Bergl and Linda Vigilant  BMC Evolutionary Biology  

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Brain Research Reveals Possible Causes Of Sudden Infant Death Syndrome

New research published today in The Journal of Physiology sheds light on areas of the brain thought to be the root cause of Sudden Infant Death Syndrome (SIDS) – the poorly understood condition also known as 'cot death'.

The research looks at specific areas of the brain and how they communicate to control breathing. It builds on previous studies that suspected abnormalities in the brain may be responsible for SIDS. It is hoped this research may vastly improve understanding of the condition.

The team from Macquarie University in Sydney have identified two areas of the brain that work together to control breathing and swallowing to enable breathing without choking – they hope that by understanding how these areas should work, they can identify what may be going wrong in SIDS babies.

Professor Paul Pilowsky, lead author of the paper, commented: "Until now, the centres in the brain that coordinate breathing and swallowing were poorly understood, but our research has finally teased apart the two mechanisms in the brain, demonstrating how they work together in the presence of an irritant.

"If irritants such as food or water 'go down the wrong way' and enter the airway, a powerful protective response is initiated in the brain to stop breathing and prevent foreign matter entering the lungs. Abnormalities in this reflex may underlie a number of life threatening conditions, including SIDS."

This protective reflex brings the vocal chords together and initiates coughing and swallowing. It is vital to everyone, but babies in particular as they have a tendency to regurgitate liquids after feeding and saliva tends to pool in their throats. It is also risky – without breathing, blood oxygen levels can drop to dangerously low levels, heart rate slows and blood is re-routed to the brain, depriving and potentially damaging other organs.

"The closing of the airway in adults is only a small compromise as breathing is only stopped temporarily. But for babies the response has more radical implications, particularly if breathing stops for a long time, as they can't take in oxygen or get rid of carbon dioxide.

"The timing of breathing and swallowing is exquisitely coordinated. We suspect that coordination of the two may be going awry in SIDS, but to be sure of this, we need to know how the brain organises this response in the first place," added Prof. Pilowsky.

To understand how the central nervous system controls breathing and swallowing, the team recreated the brain and body's response to a throat irritant using electrical stimulation of the nerve (the superior laryngeal nerve) which normally carries information from the larynx (or voicebox) to the brain, to initiate the reflex response.

By artificially generating a response and measuring the neurotransmitters that indicate how the different regions of the brain are talking to one another, the team hopes to have a better understanding of what is going on in the brain to disrupt the reflex and cause breathing to stop for long periods.

"The next step is to work out why these regions 'decide' whether breathing should be stopped. The eventual hope is to have the ability to manipulate these two systems separately to prevent the excessively long breathing arrest that may cause SIDS," concluded Professor Pilowsky.

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Economic Importance Of Bats In The Billions, UT Professor Finds

Bats in North America are under a two-pronged attack but they are not the only victim -- so is the US economy

Bats in North America are under a two-pronged attack but they are not the only victim – so is the U.S. economy. Gary McCracken, head of the Department of Ecology and Evolutionary Biology at the University of Tennessee, Knoxville, analyzed the economic impact of the loss of bats in North America in agriculture and found it to be in the $3.7 to $53 billion a year range.

Townsend's big-eared bat, Corynorhinus townsendii
Credit: Wikipedia

McCracken's findings are published in the April edition of Science and can be found online.  McCracken conducted his study with Justin Boyles of the University of Pretoria in South Africa, Paul Cryan of the U.S. Geological Survey and Thomas Kunz of Boston University.

Since 2006, more than a million bats have died due to a fungal disease called White-Nose Syndrome (WNS). At the same time, several migratory tree-dwelling species are being killed in unprecedented numbers by wind turbines. This hurts the economy because bats' diet of pest insects reduces the damage the insects cause to crops and decreases the need for pesticides.

In fact, the researchers estimate the value of bats to the agricultural industry is roughly $22.9 billion a year, with the extremes ranging as low as $3.7 and $53 billion a year.

"These estimates include the reduced costs of pesticide applications that are not needed to suppress the insects consumed by bats. However, they do not include the downstream impacts of pesticides on humans, domestic and wild animals and our environment," said McCracken. "Without bats, crop yields are affected. Pesticide applications go up. Even if our estimates were quartered, they clearly show how bats have enormous potential to influence the economics of agriculture and forestry."

According to the researchers, a single colony of 150 big brown bats in Indiana eat nearly 1.3 million insects a year -- insects that could potentially be damaging to crops.

WNS infects the skin of bats while they hibernate. Some species such as the little brown bat are likely to go extinct in parts of North America. The disease has quickly spread from Canada to Tennessee, Missouri and Oklahoma and actions to slow or stop it have proven unsuccessful.

It is unknown how many bats have died due to wind turbines, but the scientists estimate by 2020, wind turbines will have killed 33,000 to 111,000 annually in the Mid-Atlantic Highlands alone. Why migratory tree-dwelling species are drawn to the turbines remains a mystery.

Due to the economic and ecological importance, the researchers urge policy-makers to avoid a wait-and-see approach to the issue of widespread declines of bat populations.

"Not acting is not an option because the life histories of these flying, nocturnal mammals -- characterized by long generation times and low reproductive rates -- mean that population recovery is unlikely for decades or even centuries, if at all," said McCracken.

According to McCracken, solutions will only be fueled in the next few years by increased awareness of the benefits of insectivorous bats among the public, policymakers and scientists.



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Human Impacts On The Marine Ecosystems Of Antarctica

A team of scientists in the United Kingdom and the United States has warned that the native fauna and unique ecology of the Southern Ocean, the vast body of water that surrounds the Antarctic continent, is under threat from human activity. Their study is published this week in the peer-reviewed journal Annals of the New York Academy of Sciences.

“Although Antarctica is still the most pristine environment on Earth, its marine ecosystems are being degraded through the introduction of alien species, pollution, overfishing, and a mix of other human activities,” said team member Dr Sven Thatje of the University of Southampton’s School of Ocean and Earth Science (SOES) based at the UK’s National Oceanography Centre.

Seastars and giant ribbon worms at McMurdo Sound, Antarctica, 32 metre depth 
Seastars and giant ribbon worms at McMurdo Sound, Antarctica, 32 metre depth (Photo by R. B. Aronson.)
Photo by R. B. Aronson

Biodiversity can be conceptualised in terms of its information content: the greater the diversity of species and interactions between them, the more ‘information’ the ecosystem has. “By damaging the ecological fabric of Antarctica, we are effectively dumbing it down – decreasing its information content – and endangering its uniqueness and resilience,” said lead author Professor Richard Aronson, a paleoecologist at the Florida Institute of Technology, USA.

The team’s conclusions are based on an extensive review of the impacts of a wide range of human activities on the ecosystems of Antarctica. The Antarctic Treaty system, which includes environmental and fisheries management, provides an effective framework for the management and protection of the continent, but some of the threats are not currently being fully addressed.

Some of these impacts, such as pollution, can be relatively localised. However, global climate change caused by human emissions of carbon dioxide and other greenhouse gases has the potential to affect the entire Antarctic region for decades to come.

The researchers point out that rising sea temperatures are already affecting marine creatures adapted to living within a particular temperature range.

A second major consequence of carbon dioxide emission from human activities – ocean acidification – is also likely to take its toll. “The Southern Ocean is the canary in the coal mine with respect to ocean acidification. This vulnerability is caused by a combination of ocean mixing patterns and low temperature enhancing the solubility of carbon dioxide,” noted co-author Dr. James McClintock of the University of Alabama at Birmingham, USA.

“Simultaneous action at local, regional and global scales is needed if we are to halt the damage being done to the marine ecosystems of the Southern Ocean,” urged Dr Aronson.

The researchers have identified a range of historical and ongoing human activities that have damaged or restructured food webs in the Southern Ocean over recent decades. At the local to regional scale, these include –

The hunting of top predators such as whales and seals.

Overexploitation of some fish species, leading to stock collapses.

Air and water pollution from shipping traffic, wrecks, and the transport of invasive alien species on hulls and in ballast tanks.

Tourism, including potential disturbance to breeding bird and seal colonies, as well as being responsible for chemical and noise pollution, and littering.

Chemical and sewage pollution from research stations and ships, the legacy of historical waste dumping, and pollution from scientific experiments, including lost or unrecovered equipment.

Antarctica has great, untapped natural resources. The Antarctic Treaty currently prohibits the extraction of oil and other mineral resources from Antarctica. The researchers note, however, that many major areas of the Southern Ocean fall outside the Antarctic Treaty region and could be claimed by nations as valuable ‘real estate’ for the future.

Although the Antarctic Treaty and other conventions have measures aimed at reducing the local- and regional-scale impacts of human activity on Antarctica and the Southern Ocean, they cannot address global-scale threats. Among these threats, the researchers highlight the following –

Depletion of atmospheric ozone (O3). The ‘ozone hole’ was discovered by BAS scientists in 1985 and is caused by the accumulation of atmospheric chlorofluorocarbons (CFCs) used as refrigerants and spray propellants.

Introduced species. The researchers are concerned that the warming conditions in Antarctica could facilitate colonisation of species previously unreported from the region, with consequences for the structure of its marine food webs. Alien species accidentally introduced by humans are also a major concern.

The vulnerability of cold-adapted species to observed rising sea temperatures caused by global warming. The researchers argue that the extinction of some species is likely, and that changes in the geographical distribution of others are to be expected.

They warn that the further spread and establishment of predatory king crabs on the continental slope of the western Antarctic Peninsula could wreak havoc among its unique seafloor animal communities. The possible invasion by bottom-feeding fishes, rays and sharks with crushing jaws could be equally damaging. They also expect increasing dominance of salps over Antarctic krill, with consequences for animals such as whales, penguins and seals that depend either directly or indirectly on krill.

Ocean acidification. The researchers note that organisms living in polar regions are uniquely vulnerable to the effects of ocean acidification because of low concentrations of dissolved calcium carbonate in the water column. They cite evidence that declining seawater pH will particularly affect organisms with calcified shells and skeletal elements, such as molluscs, seastars, sea urchins, coralline algae and cold-water corals.

 They also highlight evidence suggesting that ocean acidification could profoundly alter the structure and functioning of the planktonic food web, with unknown consequences for animals further up the food chain, including commercially exploited fish. They therefore advocate continued and expanded baseline monitoring of ocean chemistry as well as further field and laboratory studies of the impacts of acidification on physiology, growth, and calcification.

“It is clear that multiple causal factors are damaging the health of marine systems in Antarctica; we need to understand the relative importance of these factors and how they interact.” concluded Dr Thatje.

The researchers are Richard Aronson (Florida Institute of Technology), Sven Thatje (SOES), James McClintock (University of Alabama at Birmingham) and Kevin Hughes (British Antarctic Survey).

The research was supported by the US National Science Foundation, the Total Foundation (Abyss2100) and the Royal Society.

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Aronson, R. B.,Thatje, S., McClintock, J. B. &Hughes, K. A. Anthropogenic impacts on marine ecosystems in Antarctica. Annals of the New York Academy of Sciences (published online, 30 March 2011).DOI: 10.1111/j.1749-6632.2010.05926.x

Long Lost Cousin Of T. Rex Identified By Scientists, A Gigantic Theropod Dinosaur

Scientists have identified a new species of gigantic theropod dinosaur, a close relative of T. rex, from fossil skull and jaw bones discovered in China.

According to findings published online (01 April 2011) in the scientific journal Cretaceous Research, the newly named dinosaur species "Zhuchengtyrannus magnus" probably measured about 11 metres long, stood about 4 metres tall, and weighed close to 6 tonnes.

Scientists have identified a new species of gigantic theropod dinosaur, a close relative of T. rex, from fossil skull and jaw bones discovered in China. According to findings published online April 1, 2011, in the scientific journal Cretaceous Research, the newly named dinosaur species “Zhuchengtyrannus magnus” probably measured about 11 metres long, stood about 4 meters tall, and weighed close to 6 tons. Comparable in size and scale to the legendary T. rex, this new dinosaur is one of the largest theropod (carnivorous) dinosaurs ever identified by scientists.
Credit: Courtesy of Robert Nicholls (copyright)

Comparable in size and scale to the legendary T. rex, this new dinosaur is one of the largest theropod (carnivorous) dinosaurs ever identified by scientists.

Alongside T. rex and the Asian Tarbosaurus, Zhuchengtyrannus magnus is one of a specialised group of gigantic theropods called tyrannosaurines. The tyrannosaurines existed in North America and eastern Asia during the Late Cretaceous Period, which lasted from about 99 to 65 million years ago.

"Zhuchengtyrannus can be distinguished from other tyrannosaurines by a combination of unique features in the skull not seen in any other theropod," explains Dr David Hone from the UCD School of Biology and Environmental Science at University College Dublin, Ireland, the lead author of the scientific paper.

"With only some skull and jaw bones to work with, it is difficult to precisely gauge the overall size of this animal. But the bones we have are just a few centimetres smaller than the equivalent ones in the largest T. rex specimen. So there is no doubt that Zhuchengtyrannus was a huge tyrannosaurine."

"We named the new genus Zhuchengtyrannus magnus - which means the 'Tyrant from Zhucheng' - because the bones were found in the city of Zhucheng, in eastern China's Shandong Province," says Dr Hone.

A key member of the international team of scientists involved in the study is Professor Xu Xing of the Beijing Institute of Vertebrate Paleontology and Paleoanthropology in China. Professor Xu has named more than 30 dinosaurs, making him the world leader in describing new dinosaur species.

The tyrannosaurines, the group including T. rex and its closest relatives, were huge carnivores characterised by small arms, two-fingered hands, and large powerful jaws that could have delivered a powerful bone-crushing bite. They were likely both predators and scavengers.

Together with nearby sites, the quarry in Shandong Province, eastern China where the remains of this huge carnivore were found contains one of the largest concentrations of dinosaur bones in the world. Most of the specimens recovered from the quarry belong to a gigantic species of hadrosaur, or duck-billed dinosaur. Research suggests that the area contains so many dinosaur fossils because it was a large flood plain where many dinosaur bodies were washed together during floods and fossilised.

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NIH Investigators Find Link Between DNA Damage And Immune Response

Researchers offer the first evidence that DNA damage can lead to the regulation of inflammatory responses, the body's reaction to injury. The proteins involved in the regulation help protect the body from infection.

The study, performed by scientists at the National Institute of Environmental Health Sciences (NIEHS), which is part of the National Institutes of Health, is one of the first studies to come out of the recently established NIEHS Clinical Research Unit (CRU) (http://www.niehs.nih.gov/research/clinical/join/durham/index.cfm).

Appearing in the March 31 issue of PLoS Genetics, the research suggests that an injury to chromosomes alters the expression of a family of genes known as Toll-like receptors (TLRs). TLRs are proteins that play a role in the immune system by defending the body from infection. Following damage, the TLRs interact with the tumor suppressor gene p53 to regulate the amount of inflammation. The NIEHS investigators also establish that the integration of p53 and inflammation only occurs in primates.

Healthy volunteers with informed consent donated their blood cells for the study. The scientists separated white blood cells from the samples and exposed the cells to anti-cancer agents to activate p53. They then examined the expression of TLR genes. The team detected large variations among individuals, but found that p53 generally led to the activation of several TLR genes in patients' cells. They also found that TLR activation could be prevented by adding the p53 inhibitor pifithrin.

"We would not have found this connection if we only worked with rat or mice cells," said Michael Resnick, Ph.D., principal investigator in the Laboratory of Molecular Genetics (LMG) and corresponding author on the paper. "We needed to have human samples, so our collaboration with the CRU was crucial for these experiments."

Stavros Garantziotis, M.D., a principal investigator in the Laboratory of Respiratory Biology (LRB) and the medical director for the CRU, is a co-author on the article. He said that the publication had two main findings: humans evolved an inflammatory response when subjected to DNA damage, and the variation in TLR activity among humans suggests that some people are more prone to inflammation following DNA damage, for example, after receiving cancer therapy.

"Physicians don't have this information now, but understanding who would likely benefit from anti-inflammatory treatment after chemotherapy would greatly increase a doctor's ability to help his or her patient in the future," Garantziotis continued.

As a physician and co-author of the publication, LRB principal investigator Michael Fessler, M.D., went a step further in his explanation of how stimulating the human immune system could treat infection, and autoimmune and environmental diseases.

"The immune system very likely plays a role, not only in all inflammatory diseases that afflict humans, but also in cancer," Fessler concluded. "Because of the new connection discussed in our paper, we may have a new means to manipulate the responses that affect those diseases."

Now, the researchers are taking advantage of another NIEHS translational program, the Environmental Polymorphisms Registry (EPR) (http://www.niehs.nih.gov/research/clinical/join/epr/index.cfm), an ongoing study to collect DNA samples from nearly 20,000 North Carolinians. The EPR study will allow scientists to look for genes linked to disease. The study is a collaborative effort between NIEHS and the General Clinical Research Center at the University of North Carolina at Chapel Hill.

Daniel Menendez, Ph.D., and Maria Shatz, Ph.D., are two LMG scientists who share first authorship on the paper. Menendez added that the EPR work will permit researchers to further examine the association between p53 and inflammation. "In related studies, we are looking at individuals who have genetic alterations in the way they might respond to p53 activation," he said. "We will try to determine if their cells behave differently, and if these subjects have changes in their inflammatory response, or an increased risk for certain inflammatory diseases."

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US Cancer Death Rates In Decline, National Report Finds, Trends Are Encouraging, But More Improvements Are Needed

A report from the nation's leading cancer organizations shows rates of death in the United States from all cancers for men and women continued to decline between 2003 and 2007. The findings come from the latest Annual Report to the Nation on the Status of Cancer.

The report also finds that the overall rate of new cancer diagnoses for men and women combined decreased an average of slightly less than 1 percent per year for the same period. Edward J. Benz, Jr., MD, president of Dana-Farber Cancer in Institute in Boston, called the news encouraging, but cautions we still have a very long way to go in our fight against cancer.

"Overall, the rate of cancer deaths is falling, but not by a lot, not nearly enough," said Benz. "But considering that the incidence of cancer continues to increase, while the number of deaths is flat or falling a little bit, it does suggest that efforts of prevention, early detection, and better treatments are having a positive impact."

The report is co-authored by researchers from the North American Association of Central Cancer Registries, the National Cancer Institute, the Centers for Disease Control and Prevention, and the American Cancer Society. It will be posted on the web site of the Journal of the National Cancer Institute on March 31, and will be published in the journal's May 14 print issue.

The authors emphasized the need to focus further on reducing the cancer burden in the population as a whole through prevention, detection and treatment of cancer.

"One of the best ways to avoid dying of cancer is to prevent it in the first place," added Dr. Benz. "This involves making lifestyle adjustments, such as not smoking, being careful about exposure to the sun, diet and exercise, and being careful about exposure to chemicals in the workplace. Patients also need to be sure to participate with their primary care physician in the kinds of screening that can pick up cancers very early."

The New Face of Cancer (MOV file, 134.7 MB)


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F-22 Raptor Flown On Synthetic Biofuel

An F-22 Raptor successfully flew at supercruise March 18 on a 50/50 fuel blend of conventional petroleum-based JP-8 and biofuel derived from camelina, a weed-like plant not used for food.

The flight was the capstone of a series of ground and flight test events conducted by the 411th Flight Test Squadron at Edwards Air Force Base the week of March 14 for the Raptor using the biofuel blend. The Air Force selected the F-22 weapon system to be the biofuel blend flight test pathfinder for all fighter aircraft.

An F-22 Raptor powered by biofuel takes off at Edwards Air Force Base, Calif., March 18, 2011. The flight was the capstone of a series of ground and flight test events conducted by the 411th Flight Test Squadron for the Raptor using the biofuel blend.
U.S. Air Force photo/Kevin North

The overall test objective was to evaluate biofuel fuel blend suitability in the F-22 weapon system. Testing consisted of air starts, operability, and performance at different speeds and altitude throughout the flight envelope. The F-22 Raptor performed several maneuvers including a supercruise at 40,000 ft. reaching speeds of 1.5 Mach. Supercruise is supersonic flight without using the engine's afterburner.

The overall flight was a success and another milestone completed for the Alternative Fuels Certification Division in support the Air Force's 2016 acquisition goal to cost-competitively acquire 50 percent of the domestic aviation fuel requirement via alternative fuel blends in which the component is derived from domestic sources produced in a manner that is 'greener' than fuels produced from conventional petroleum.

The camelina-derived synthetic fuel falls into a class of hydro-processed blended biofuels known as hydrotreated renewable jet fuels, or "HRJs." The HRJ fuel can be derived from a variety of plant oil and animal fat feedstocks.

Air Force officials in February certified the entire C-17 Globemaster III fleet for unrestricted flight operations using the HRJ biofuel blend.

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by 95th Air Base Wing Public Affairs
EDWARDS AIR FORCE BASE, Calif.

Archaeologists Investigate Iraqi Marshes For Origins Of Mesopotamian Cities

Researchers conduct first US-led archeological survey inside Iraq in 20 years

Three National Science Foundation-supported researchers recently undertook the first non-Iraqi archaeological investigation of the Tigris-Euphrates delta in nearly 20 years. Archeologists Jennifer Pournelle and Carrie Hritz, with geologist Jennifer Smith, carried out the study late last year to look for links between wetland resources and the emergence of Mesopotamian cities.

Map showing the Babylonian territory upon Hammurabi's ascension in 1792 BC and upon his death in 1750 BC

Credit: Wikipedia

"Mesopotamia"--Greek for "the land between the rivers"--is an area about 300 miles long and 150 miles wide straddling the Tigris and Euphrates rivers, which now run through Iraq, northeastern Syria, southeastern Turkey and southwestern Iran. It is broadly considered a cradle of civilization, because urban societies first developed there, about six thousand years ago.

Alexander the Great conquered Mesopotamia in 332 B.C.

"This is an important project because it has the potential to shed new light on the processes by which civilization rose in the Near East," said John Yellen, an NSF program director for archeological research.

The researchers proposed the project to probe how the area's gulf shoreline and marshes contributed to the economic foundation of Mesopotamian cities. Specifically, they wanted to investigate archaeological sites from 5,000 B.C. to Islamic times to learn more about how wetland resources contributed to the locale's towns and cities during the early- to mid-Holocene period.

"Our interest is in early settlement," said Hritz, an assistant professor of archaeological anthropology at Penn State. "The early period of settlement is always linked to the development of agriculture."

An area of keen interest for the researchers was the Hammar marshlands, located south of the Euphrates River in Iraq and Iran, which were drained between 1950 and the 1990s, in part, to facilitate oil exploration and development. But after the first Gulf War, former Iraqi President Saddam Hussein diverted the Euphrates River away from the area, causing the marshlands to almost entirely disappear, while at the same time making it more accessible to archeologists.

Foreign archeological investigations there stopped, while Iraqis continued only limited research. "But because their work is unpublished, we are unsure of where they surveyed," said Hritz.

The three members of the research team were able to get a look--for the first time in nearly two decades.

"Certainly having pedestrian access to much of the region was a help," said Smith, who is an associate professor of Earth and Planetary Sciences and Environmental Studies at Washington University in St. Louis. "However, we only got to see a limited and relatively disturbed portion of the existing remnant marshlands, which made it harder to develop a real modern analog for past wetland environments."

"One thing that really surprised us was the surface condition of the dried bed of Lake Hammar. We expected it to be significantly deflated by wind scouring, like the silty desert areas around other major sites we visited," said Pournelle. "Instead, it was 'sealed' beneath a layer of consolidated silt and shell--obscuring any indication of what might lie below the surface."

"It surprised me that sometimes features clear on the imagery were virtually indiscernible from the ground, Smith added, pointing out the paleochannels as an example. "It is exceedingly important to use both remote sensing and groundtruthing in these incredibly flat regions." Smith was a co-principal investigator for the study.

Restoration of the Hammar marshes is now a high national priority in Iraq. The researchers say if they do not act quickly, the window of opportunity for conducting future work in the region will close.

"Iraq holds a wealth of significant archaeological sites and it has a long history of archaeological research," said Yellen. "Hopefully, this project will help reinvigorate this rich tradition."

But getting to the sites to carry out a survey in a country at war can be a bit tricky.

"Ultimately, we found that the only way to get into the country that was cost effective was to go on a tour with a British tour company," said Hritz. "While in Bagdad, we met with the State Board of Antiquities and Heritage (SBAH), and they encouraged us to visit the sites with a SBAH representative and report back to them any observations."

"We never imagined the degree of cooperation and openness," said research principal investigator Pournelle, a research assistant professor in the Environment and Sustainability Program of the School of the Earth, Ocean, and Environment at the University of South Carolina. "All of the ministries, universities and faculties involved were incredibly generous with their time and resources."

The researchers used local Iraqi security for their trip rather than a foreign security firm. They spent a week travelling with Hinterland Tours from Bagdad to Basra, the capital of Basra Province in Iraq. While in the Basra area, they then spent five days with a private guide conducting a geoarchaeological survey.

"We saw everything we intended to see, except for one area that was flooded," said Hritz. "We did not have the proper equipment to enter the flooded area."

The researchers hope to conduct more studies in Iraq.

"Next is systematic seismological study, coring and survey in order to relate past and future archaeological excavations and surveys to an explicit paleoenvironmental record," said Pournelle. "Amazingly, this has never been done. We need to work quickly on the ground-based operations, because some of this area is scheduled for re-flooding."

Contacts and sources:


Low-Cost Mass Production of Monodispersed Micro/Nanoparticles

Low Cost Nanoparticles Produced in Bulk 
Image by NIMTE

Researchers at the Division of Functional Materials and Nanodevices, Ningbo Institute of Materials Technology &. Engineering (NIMTE) have deloped a simple and viable route to produce various oxide micro/nano particles in kilogram quantities with low cost, simple and controllable process. According the route, the monodisperse micro/nano particles such as Silica, Titania, Hematite and Zinc Oxide were synthesized successfully. 
 
Pic. Hematite (Image by NIMTE)

The nanoparticles, including powders and colloids, may exhibit novel properties relative to fine particles and bulk materials due to increased percentage of atoms at the surface of a nanoparticle. Thus, they have a wide variety of potential applications in biomedical, optical, magnetic/electronic and catalysis fields. The unique properties of nanoparticles depend decisively on their size, shape and structure, and thus development of low-cost, simple and controllable processes is intensive studied issues of nanoscience. However, most of monodispersed particles are still prepared in exceedingly dilute system due to the problem of coalescence. The synthesis and applications of these materials are still in an early stage of technical development on account of the limited approach to produce diverse materials with controllable structure and properties. 
Pic. Silica Sol (Image by NIMTE)
The researchers systematically studied the characteristic and common formation law of typical monodispersed metal oxide nanoparticles, developed a simple, scalable and high yield approach for the production of various monodispersed micro/nano particles with controllable size, shape and property by using of the most inexpensive precursors. More remarkably, the monodispered spherical silica colloid with different sizes (8~100 nm) can be prepared by a phase-transfer method in large scale. The polydispersibility is less than 10%. Further, the kilogram scale productions of spherical titania, cigar-shaped hematite and columnar zinc oxide, with size range form 200 to 2000nm and polydispersity less than 15%, can also be achieved by simple one-step precipitation method. This will promote the applications of these materials in electronic, smart fluids and special coatings.
 
Pic. Zinc Oxide (Image by NIMTE)

 
Pic. Titania (Image by NIMTE)


Source: Chinese Academy of Sciences
Contacts:  Dr. Guo Jianjun 

Millions of Chinese Ducks Killed by Mysterious New Virus

Peking duck, salted duck eggs, duck soup: China is famous for its duck delicacies, and duck farms dot the country's agricultural belt. So last spring, when Chinese farmers noticed their prized birds were producing fewer eggs than usual, they began to worry. Egg production plummeted by as much as 90% in some flocks. Ducks were waddling about awkwardly, their coordination off kilter, and eating less than usual. Some died within days.

By the end of the year, an estimated 4.4 million ducks in Fujian, Shandong, and Zhejiang provinces, the swath of eastern China where duck farming is common, had caught the mysterious illness. And the outbreak reached at least six other provinces, along with rural areas outlying Beijing.

Credit: CAS

Enter microbiologist George Gao and colleagues at the Chinese Academy of Sciences in Beijing. By analyzing the affected animals, the scientists isolated an aggressive new flavivirus, a class of viruses that includes yellow and dengue fevers—the first flavivirus ever identified in ducks.

The discovery of what the scientists have dubbed the BYD virus raises some critical concerns. In addition to potentially devastating Chinese duck farming and the economy that depends on it, the flavivirus could put humans at risk. "Most flaviviruses are zoonotic," meaning they can be transmitted from animals to people, Gao says, "so infection of human beings cannot be ruled out."

When reports of the duck disease first reached the researchers last April, the symptoms farmers described—particularly a severe drop in egg production—alarmed them. Arriving at the farms, the microbiologists collected tissue and serum samples from animals in affected flocks for testing. As detailed in a paper published this month in PLoS ONE, Gao and his colleagues worked methodically to find the culprit.

First, they ruled out avian flu by testing serum samples from the animals for flu antibodies. Then, working with brain and ovary tissue from ducks that had died within 6 hours of infection, they isolated the BYD virus.

To make sure they had nailed the right culprit, they injected healthy ducks with BYD, comparing them with a control group. The BYD ducks soon fell ill.

Gao and colleagues say the BYD virus is closely related to the Tembusu virus, a flavivirus found in Southeast Asia. Like that other virus, they suggest, BYD could be spread by mosquitoes.
Transmission by mosquitoes should not be a foregone conclusion, says Ernest Gould, a virologist and visiting scholar at the Université de la Méditerranée in Aix-Marseille, France, noting that temperature changes over the period of the virus's spread are not consistent with those of other mosquito-borne flaviviruses. (Ducks started falling ill in the cool weather of early spring, when mosquito populations were presumably low, and the outbreak continued well through autumn.)

"Much more detailed epidemiological studies are required," Gould wrote in an e-mail.
But, he adds, the paper "raises an important alarm with potential implications way beyond the boundaries of China." He says a rapidly spreading Chinese flavivirus could mean a global problem.

Because of the pervasiveness of duck farming in China, Gao and colleagues stress that the disease should be closely monitored, in part because it could spread to people. The next step, they say, is the development of a BYD vaccine.

Source: Chinese Academy of Sciences

Dana-Farber Cancer Institute Study Identifies Promising Target For AIDS Vaccine

A section of the AIDS virus's protein envelope once considered an improbable target for a vaccine now appears to be one of the most promising, new research by Dana-Farber Cancer Institute scientists indicates.

The section, a twisting strand of protein known as the V3 loop, is an attractive vaccine target because immune system antibodies aimed at the loop may offer protection against multiple genetic subtypes of HIV-1, the virus that causes AIDS. This is a key prerequisite of any AIDS vaccine because the viruses mutate rapidly and by now comprise millions of different strains that are grouped into different genetic subtypes, or "clades." The researchers' findings are published online in the Public Library of Science journal PLoS One.

Diagram of HIV
Credit: Wikipedia

In the study, investigators injected a monoclonal antibody -- a preparation of millions of identical antibodies that fight viral infection -- into Asian monkeys known as macaques. The antibody came from a person infected with a specific clade of HIV-1. The macaques were then exposed to virus of a different clade. Investigators knew the antibody would latch onto a portion of the virus's V3 loop, potentially barring the virus from invading nearby cells, but they didn't know whether it would prevent infection from a separate subtype of the virus.

The results were striking: All of the treated monkeys were protected from infection by the monkey form of HIV-1, known as SHIV. Monkeys exposed to the virus without receiving the monoclonal antibody, by contrast, became heavily infected.

"This is the first time a monoclonal antibody made against an AIDS virus of one clade has provided complete protection against an AIDS virus of a different clade in animal models," said the study's senior author, Ruth Ruprecht, MD, PhD, of Dana-Farber. "Previous studies have shown that such neutralizing antibodies can protect macaques from infection within one clade; but as more clades of the AIDS virus evolve, it has been unclear whether such antibodies could shield across different clades and prevent infection. Now we have an answer."

AIDS vaccines need to be broadly effective, Ruprecht said, offering protection from a range of HIV-1 subtypes anywhere in the world. It is particularly important for such vaccines to shield against clade C, which accounts for almost 60 percent of worldwide AIDS cases and predominates in sub-Saharan Africa, India, and China. In many parts of the world, clade C has combined with clade B, but retains a clade C protein envelope. Ruprecht and her colleagues have showed that the antibody against the V3 loop prevented infection by a clade C virus.

The antibody treatment technique used in the study is unlikely to confer long-term protection against HIV-1 because the infected antibodies do not remain active in the body for very long. The value of the study is that it demonstrates that antibodies directed against the V3 loop of one clade of HIV-1 can create an immune system shield against another clade.

To translate this discovery into a vaccine, researchers need to devise a way to focus the body's immune system responses to the small portion of the V3 loop that is shared by viruses of different clades. The immune system could then generate its own protective antibodies against the virus. One way of accomplishing this may be to create small molecules that represent this special region inside the V3 loop so the immune system can recognize and attack it.

The study's findings represent something of a vindication for the V3 loop as an immune system target, Ruprecht remarked. While scientists have long known that V3 can spark an immune system response to HIV-1, the loop was thought to be a clever "decoy:" the body would produce antibodies that home in on V3, but these would be unable to block infection by slightly different versions of the AIDS virus. The V3 loop has long been known to mutate very rapidly. Viruses with slightly altered protein envelopes would then begin the infection process. The study has shown that a special region of V3 is a prime target, after all.

The study's co-lead authors are Jennifer Watkins, PhD, and Nagadenahalli Siddappa, PhD, of Dana-Farber. Other Dana-Farber co-authors are Samir Lakhashe, PhD, Michael Humbert, PhD, Anton Sholukh, PhD, Girish Hemashettar, Yin Ling Wong, John Yoon, and Wendy Wang. Francis Novembre, PhD, Francois Villinger, DVM, PhD, Chris Ibegbu, PhD, and Kalpana Patel of the Yerkes National Primate Research Center at Emory University in Atlanta conducted the studies in animals. Other co-authors include Davide Corti, Gloria Agatic, Fabrizia Vanzetta, and Siro Bianchi, of Humabs SAGL, in Bellinzona, Switzerland; Jonathan Heeney, DVM, PhD, of the University of Cambridge, England; and Federica Sallusto PhD, and Antonio Lanzavecchia, MD, of the Institute for Research in Biomedicine, Bellinzona, Switzerland.

The study was funded by grants from the National Institutes of Health, the Bill and Melinda Gates Foundation Collaboration for AIDS Vaccine Discovery, and the Center for AIDS Research Immunology Core.

Dana-Farber Cancer Institute is a principal teaching affiliate of the Harvard Medical School and is among the leading cancer research and care centers in the United States. It is a founding member of the Dana-Farber/Harvard Cancer Center (DF/HCC), designated a comprehensive cancer center by the National Cancer Institute. It provides adult cancer care with Brigham and Women's Hospital as Dana-Farber/Brigham and Women's Cancer Center and it provides pediatric care with Children's Hospital Boston as Dana-Farber/Children's Hospital Cancer Center. Dana-Farber is the top ranked cancer center in New England, according to U.S. News & World Report, and one of the largest recipients among independent hospitals of National Cancer Institute and National Institutes of Health grant funding.

Contacts and sources:
Bill Schaller
Dana-Farber Cancer Institute

Quantum Mechanics: New Findings Could Help Build Better Biomedical Devices


Do the principles of quantum mechanics apply to biological systems? Until now, says Prof. Ron Naaman of the Institute’s Chemical Physics Department (Faculty of Chemistry), both biologists and physicists have considered quantum systems and biological molecules to be like apples and oranges. But research he conducted together with scientists in Germany, which appeared recently in Science, definitively shows that a biological molecule – DNA – can discern between quantum states known as spin.

Quantum phenomena, it is generally agreed, take place in extremely tiny systems – single atoms, for instance, or very small molecules. To investigate them, scientists must usually cool their material down to temperatures approaching absolute zero. Once such a system exceeds a certain size or temperature, its quantum properties collapse, and “every day” classical physics takes over. 

Naaman: “Biological molecules are quite large, and they work at temperatures that are much warmer than the temperatures at which most quantum physics experiments are conducted. One would expect that the quantum phenomenon of spin, which exists in two opposing states, would be scrambled in these molecules – and thus irrelevant to their function.”

But biological molecules have another property: they are chiral. In other words, they exist in either “left-” or “right-handed” forms that can’t be superimposed on one another. Double-stranded DNA molecules are doubly chiral – both in the arrangement of the individual strands and in the direction of the helices’ twist. Naaman knew from previous studies that some chiral molecules can interact in different ways with the two different spins. Together with Prof. Zeev Vager of the Particle Physics and Astrophysics Department, research student Tal Markus, and Prof. Helmut Zacharias and his research team at the University of Münster, Germany, he set out to discover whether DNA might show some spin-selective properties.

The researchers fabricated self-assembling, single layers of DNA attached to a gold substrate. They then exposed the DNA to mixed groups of electrons with both directions of spin. Indeed, the team’s results surpassed expectations: The biological molecules reacted strongly with the electrons carrying one of those spins, and hardly at all with the others. 

The longer the molecule, the more efficient it was at choosing electrons with the desired spin, while single strands and damaged bits of DNA did not exhibit this property. These findings imply that the ability to pick and choose electrons with a particular spin stems from the chiral nature of the DNA molecule, which somehow “sets the preference” for the spin of electrons moving through it.

In fact, says Naaman, DNA turns out to be a superb “spin filter,” and the team’s findings could have relevance for both biomedical research and the field of spintronics. If further studies, for instance, bear out the finding that DNA only sustains damage from spins pointing in one direction, then exposure might be reduced and medical devices designed accordingly. On the other hand, DNA and other biological molecules could become a central feature of new types of spintronic devices, which will work on particle spin rather than electric charge, as they do today.

Recycling Of Carbon Dioxide Emissions Gets Significantly Easier Thanks To A Novel Copper–Organocatalyst Complex


Schemes for storing carbon dioxide (CO2) emissions underground often make the headlines, but chemically ‘fixing’ this molecule onto the frameworks of other compounds is a potentially more lucrative proposition. Transforming CO2 into useful products like polymers and pharmaceuticals could simultaneously reduce greenhouse gases and boost manufacturers’ profits. Unfortunately, the expensive metal catalysts and hot temperatures typically needed to break CO2 apart and rearrange the bonds render this technology too pricy for most applications.

 Credit: © iStockphoto.com/alohaspirit

Yugen Zhang and Dingyi Yu at the A*STAR Institute of Bioengineering and Nanotechnology1 have now discovered a way to make CO2 fixation more economical than ever before. The researchers developed a mixed copper–organocatalyst system that can convert almost any molecule bearing terminal alkyne groups—outward-facing carbon–carbon triple bonds—into carboxylic acids via CO2 insertion at room temperature. Alkynyl carboxylic acids have extensive applications in synthetic chemistry, so the discovery could have wide-reaching impact.

Adding CO2 onto a hydrocarbon is an energy-intensive process that generally requires the creation of a new carbon–carbon bond. Consequently, chemists have been hunting for metal catalysts that can lower these energy barriers to cost-effective levels.

Recent studies have identified copper complexes as promising catalysts because they could activate a variety of substrates by bonding to the carbon atom and then incorporating CO2 in between the carbon and its neighboring metal atoms. However, copper-catalyzed additions of CO2 to terminal alkynes have had limited success so far.

Zhang and Yu discovered that previous experiments were simply too hot to stabilize the important copper–alkyne intermediates. By mixing a copper catalyst containing a basic ligand with alkyne molecules and COat room temperature, instead of the usual 100 °C, the researchers obtained several types of alkynyl carboxylic acids in excellent yields. “We could achieve broad tolerance for different substrates because we use mild reaction conditions—no strong base or acid, no heating, no oxidant or reductant,” says Zhang.

However, alkynes containing deactivating ‘electron-withdrawing’ substituents remained stubbornly inert with copper catalysts. To resolve this, the researchers synthesized N-heterocyclic carbenes (NHCs)—molecules with proven CO2-activating behavior—into a large, robust polymer. When used as a copper catalyst ligand, the unique structure of poly-NHC enabled it to surround the metal and enhance the chances of CO2 conversion, boosting yields from 2% to 70% for a typical electron-withdrawing alkyne. Furthermore, the solid structure of the poly-NHC–copper catalyst makes it compatible with industrial systems, a technological advantage that Yu and Zhang are currently investigating.
 
The A*STAR-affiliated researchers contributing to this research are from the Institute of Bioengineering and Nanotechnology

References
  1. Yu, D. & Zhang, Y. Copper- and copper–N-heterocyclic carbene-catalyzed C–H activating carboxylation of terminal alkynes with CO2 at ambient conditions. Proceedings of the Natural Academy of Sciences 107, 20184–20189 (2010). | article

Source: A*STAR

Invisible Quantum Link Between Pairs Of Photons Can Be Tailored For Specific Applications


Entanglement is one of the most bizarre implications of quantum mechanics. It acts like an invisible link between two distant quantum bodies so that whatever happens to one instantaneously affects the other. Experimentally, this phenomenon has already been verified and studied using light.

A relatively simple technique known as spontaneous parametric down conversion (SPDC) can produce photons that are connected in this unusual way, and the method is now used in many laboratories throughout the world. Dmitry Kalashnikov and Leonid Krivitsky at the A*STAR Data Storage Institute1 have now shown that small differences in the properties of these two photons can affect the degree of entanglement, and that the effect can be put to good use. 

Light from a nonlinear crystal is emitted over a range of emission angles (as indicated by the concentric circles) and energies (as indicated by the different colors) with various levels of quantum entanglement.
 
Credit:  A*STAR

When a material with nonlinear optical propertiesabsorbs an incoming photon, it emits two new photons of lower energies. Although these two photons travel in different directions, they remain entangled, meaning that the polarization of one photon is linked to the polarization of the other. “In reality,” explains Kalashnikov, “the angle of emission and the energy of each photon can vary within a small band called the SPDC linewidth.” This linewidth makes it difficult to observe the polarization entanglement of the photon pair.

Kalashnikov and Krivitsky have now thoroughly investigated how the quantum state of photons emitted at different angles and energies within the linewidth are connected. They shot a continuous beam of laser light at a bulk crystal of beta-barium borate, and detected the photon pairs produced (see image) using two single-photon counters.

One counter scanned and measured light at different emission angles, while the other counter detected light after it had passed through a spectrometer that selected photons with a specific energy. This experiment was repeated for various choices of emission angle and energy to get a full map of the polarization state of the photon pairs using a procedure referred to as quantum tomography.

“We found that the generated polarization-entangled states are highly specific to the choice of energy and emission angle,” says Kalashnikov. “Thus, it is possible to obtain a wide range of polarization-entangled states using just a single nonlinear crystal. The generated states can be efficiently tailored to fit specific applications by placing a specially designed sample of quartz just after the beta-barium borate.”

Based on their results, the researchers hope to investigate highly entangled photon states further with the aim of implementing them in quantum information science.
 
Source: A*STAR

The A*STAR-affiliated researchers contributing to this research are from the Data Storage Institute

References
  1. Kalashnikov, D. A. & Krivitsky, L. A. Spectrally resolved quantum tomography of polarization-entangled states.New Journal of Physics 12, 093040 (2010). | article

New Insight into "Aha!" Memories


“Much of memory research involves repetitive, rote learning,” says Kelly Ludmer, a research student in the group of Prof. Yadin Dudai of the Institute’s Neurobiology Department, “but in fact, we regularly absorb large blocks of information in the blink of an eye and remember things quite well from single events. Insight is an example of a one-time event that is often well-preserved in memory.”

To investigate how lessons we gain from insight get embedded in our long-term memory, Ludmer, Dudai and Prof. Nava Rubin of New York University designed a test with “camouflage images” – photographs that had been systematically degraded until they resembled inkblots. When volunteers first viewed the images, they were hard pressed to identify them. 

But after the camouflage was switched with the original, undoctored picture for a second, the subjects experienced an ‘Aha!’ moment – the image now popped out clearly even in the degraded image. Their perceptions, says Ludmer, underwent a sudden change – just as a flash of insight instantly shifts our world view. To tax their memory of the insightful moment, participants were asked to repeat the exercise with dozens of different images and, in a later repeat session, they were given only the camouflaged images (together with some they hadn’t seen before) to identify.


Aha! 

Aha!
 Credit: Weizmann Institute 

The team found that some of the memories disappeared over time, but the ones that made it past a week were likely to remain. All in all, about half of all the learned “insights” seemed to be consolidated in the subjects’ memories.

To reveal what occurs in the brain at the moment of insight, the initial viewing session was conducted in a functional MRI (fMRI) scanner. When the scientists looked at the fMRI results, they were surprised to find that among the areas that lit up in the scans – those known to be involved in object recognition, for instance – was the amygdala. The amygdala is more famously known as the seat of emotion in the brain. Though it has recently been found to play a role in the consolidation of certain memories, studies have implied that it does so by attaching special weight to emotion-laden events. 

But the images used in the experiment – hot-air balloons, dogs, people looking through binoculars, etc. – were hardly the sort to elicit an emotional response. Yet, not only was the amygdala lighting up in the fMRI, the team found that its activity was actually predictive of the subject’s ability to identify the degraded image long after that moment of induced insight in which it was first recognized.

“Our results demonstrate, for the first time, that the amygdala is important for creating long-term memories – not only when the information learned is explicitly emotional, but also when there is a sudden reorganization of information in our brain, for example, involving a sudden shift in perception,” says Ludmer. “It might somehow evaluate the event, ‘deciding’ whether it is significant and therefore worthy of preservation.”

Erasing and Enhancing Long Term Memories with Proteins


Long-term memory is a slippery thing. Just how slippery it can be was demonstrated a few years ago by Weizmann Institute scientists, who erased entire memories in rats just by blocking a certain protein in the brain. In other words, memory – even the part we imagine to contain neatly packed files – is in reality a dynamic piece of equipment that must be actively maintained to work. Now, in research published in Science, these scientists have shown that manipulating the same protein can enhance memory.

The protein – PKMzeta – is produced in the brain in response to learning, and it acts on the synapses – the active contact points between neurons. It continues to operate there long after the memory has been formed, suggesting that its function is tied not to learning (that is, absorbing information), but to keeping what is learned available in the long-term memory. In 2007, Prof. Yadin Dudai and research student Reut Shema of the Neurobiology Department, together with Prof. Todd Sacktor of SUNY Downstate Medical Center, New York, trained rats to avoid a specific taste and then blocked the activity of PKMzeta in their brains. While the control rats still had a strong aversion to the taste, even months after the training, those in which the activity of the protein was briefly blocked had no such qualms, appearing to have forgotten what they had learned.

But, could extra doses of PKMzeta actually improve memory? Investigating this claim turned out to be a more difficult prospect than blocking protein activity. Simply injecting the protein into the rats’ grey matter was not an option, as the brain is built to keep such extraneous material from reaching the neurons. So Dudai, Shema and Sacktor teamed up with Dr. Alon Chen and Sharon Haramati, also of the Neurobiology Department, to create harmless viruses that carry extra copies of the PKMzeta gene into the brain cells’ nucleus, tricking the neurons themselves into producing greater quantities of the protein.

Once again, they trained the rats to avoid the taste. Weeks after the training, the rats whose brains were churning out more of the proteins were much more likely to avoid the taste. In other words, an excess of PKMzeta effectively enhanced their memories. This is the very first demonstration that memories formed long ago can be augmented by manipulating a component of the memory machinery in the brain.

While the technique they developed is only suitable for the lab, the researchers hope that by shedding light on the function of this key component of the memory machinery, their findings might eventually point to ways of preventing or treating memory loss. Shema: “Our research is evidence that our brains are very plastic – even our long-term memories can be augmented.”