Wednesday, March 31, 2010

UF RESEARCHER MAPS HOW AGE, GENDER CAN AFFECT RISK TO RADIATION EXPOSURE

0 comentarios

Doctors have a clearer picture than ever before of how much radiation reaches sensitive tissues during routine X-rays and similar imaging, thanks to sophisticated models of the human body being developed at the University of Florida.

“We’re building a rich library of computer simulation tools and 3-D patient models that will make dose estimates much more accurate and patient-specific,” said Wesley E. Bolch, a professor in the UF departments of nuclear and radiological engineering and biomedical engineering, and a member of the UF Shands Cancer Center.

In the March 5 issue of Physics in Medicine and Biology, Bolch and researchers in his lab discuss how they used three-dimensional microCT imaging to describe cartilage, bone marrow and two types of mineral bone in 20 different skeletal sites from two newborns. It is the second in a series of planned articles that will describe variations in tissue and bone that can affect how much radiation is absorbed by the body.

They discovered that children have a greater percentage of total mineral bone in direct contact with sensitive bone marrow than do adults. This has implications for radiation treatments and types of chemotherapy used to treat cancer patients, especially therapies targeting pediatric bone cancers.

In contrast to existing models, the study also found that a large amount of the electron and beta particle energy once believed to stay contained within the bone marrow of children actually escapes to surrounding tissue, said Deanna Pafundi, a UF researcher and lead author of the paper, now a research fellow at the Mayo Clinic in Rochester, Minn. This finding is being used in existing UF research calculating the impact of radiation to the skeletal surrounding tissues, she said.

Radiation epidemiologists can use the revised model to look back in time, estimating doses of radiation associated with leukemia risk, Bolch said. He pointed to the case of unusually high rates of leukemia among a Russian population exposed to river discharges of bone-seeking radionuclides during the Soviet’s nuclear weapons program in the 1950s. UF’s newborn skeletal model suggests that radiation doses to newborn bone marrow have been overestimated by existing clinical skeletal models.

Most current estimates of bone marrow radiation dose are obtained from two-dimensional images acquired from seven skeletal sites in a 44-year-old adult male during the late 1960s, Bolch said. UF’s current work seeks to replace these widely used estimates from the University of Leeds by using three-dimensional imaging and extending the work to the pediatric and prenatal skeleton. The work will illustrate how bone marrow radiation dose can vary with patient size, whether a patient has osteoporosis, and marrow health.

“Wes Bolch is doing research that will give clinicians the tools to reduce the level of patients’ radiation exposure. It’s very important work,” said George Xu, a professor in the department of mechanical, aerospace and nuclear engineering at Rensselaer Polytechnic Institute in Troy, N.Y.

The models are being created at a time when the medical community is sounding the alarm about the potential for harm from excessive radiation exposure. According to the National Council on Radiation Protection and Measurements, the average annual radiation exposure in the United States increased about 75 percent between 1982 and 2006. During that time, the proportion of exposure due to medical interventions rose from 15 percent to 48 percent.

“The current philosophy is that there is a small but perceptible risk of cancer with every radiation exposure. Consequently, you want to maximize the dose delivered to the tumor in radiation therapy, while minimizing the dose and thus additional cancer risk to surrounding healthy tissues,” Bolch said.

Children are at particular risk from radiation exposure, Bolch said, as the carcinogenic effects of radiation have more time to develop in children than in adults. In response to these concerns, professionals involved in pediatric imaging have launched a campaign, dubbed Image Gently, to highlight opportunities to lower radiation dosing when imaging children.

“The risk in using ionizing radiation for both therapy and imaging is never going to be zero, but it can be reduced through proper guidelines and patient modeling of these procedures,” Bolch said.

(Photo: U. Florida)

University of Florida

SPIDER SILK REVEALS A PARADOX OF SUPER-STRENGTH

0 comentarios

Since its development in China thousands of years ago, silk from silkworms, spiders and other insects has been used for high-end, luxury fabrics as well as for parachutes and medical sutures. Now, National Science Foundation-supported researchers are untangling some of its most closely guarded secrets, and explaining why silk is so super strong.

Researchers at the Massachusetts Institute of Technology's Center for Materials Science and Engineering say the key to silk's pound-for-pound toughness, which exceeds that of steel, is its beta-sheet crystals, the nano-sized cross-linking domains that hold the material together.

Markus Buehler, the Esther and Harold E. Edgerton Associate Professor in MIT's department of civil and environmental engineering, and his team recently used computer models to simulate exactly how the components of beta sheet crystals move and interact with each other. They found that an unusual arrangement of hydrogen bonds--the "glue" that stabilizes the beta-sheet crystals--play an important role in defining the strength of silk.

They found that hydrogen bonds, which are among the weakest types of chemical bonds, gain strength when confined to spaces on the order of a few nanometers in size. Once in close proximity, the hydrogen bonds work together and become extremely strong. Moreover, if a hydrogen bond breaks, there are still many hydrogen bonds left that can contribute to the material's overall strength, due to their ability to "self-heal" the beta-sheet crystals.

The researchers conclude that silk's strength and ductility--its ability to bend or stretch without breaking--results from this peculiar arrangement of atomic bonds. They say controlling the size of the area in which hydrogen or other chemical bonds act can lead to significantly enhanced properties for future materials, even when the initial chemical bonds are very weak.

(Photo: M.J. Buehler (MIT))

National Science Foundation

MEXICAN CAVE SCORPIONS SHOW SPECIALIZATION NOT EVOLUTIONARY DEAD END

0 comentarios

Blind scorpions that live in the stygian depths of caves are throwing light on a long-held assumption, showing that specialized adaptations aren’t always an evolutionary dead-end.

Looking at the phylogenetic relationships among species of the scorpion family Typhlochactidae, endemic to Mexico, Associate Curator Lorenzo Prendini and colleagues found that species currently living closer to the surface (under stones and in leaf litter) evolved independently on more than one occasion from specialized deep-cave ancestors adapted to life further below the surface (in caves). This finding puts a dent in both Cope’s Law of the unspecialized, which assumes that novel evolutionary traits tend to originate from a generalized member of an ancestral taxon, and Dollo’s Law of evolutionary irreversibility, which theorizes that specialized evolutionary traits are unlikely to reverse.

Scorpions are predatory, venomous, nocturnal arachnids related to spiders, mites, and other arthropods. About 2,000 species are distributed throughout the world, but only 23 species found in ten different families are adapted to a permanent life in caves. One of these families is the Typhlochactidae, comprising four genera and nine species.

“Scorpions have been around for 450 million years, and their biology is obviously flexible,” says Prendini. “This unique group of eyeless Mexican scorpions may have started re-colonizing niches closer to the surface from the deep caves of Mexico after their surface-living ancestors were wiped out by the nearby Chicxuluxb impact along with non-avian dinosaurs, ammonites, and other species.”

(Photo: V. Vignoli)

American Museum of Natural History

NEW CU-BOULDER HAND BACTERIA STUDY HOLDS PROMISE FOR FORENSICS IDENTIFICATION

0 comentarios

Forensic scientists may soon have a valuable new item in their toolkits -- a way to identify individuals using unique, telltale types of hand bacteria left behind on objects like keyboards and computer mice, says a new University of Colorado at Boulder study.

The CU-Boulder study showed that "personal" bacterial communities living on the fingers and palms of individual computer users that were deposited on keyboards and mice matched the bacterial DNA signatures of users much more closely than those of random people. While the development of the technique is continuing, it could provide a way for forensics experts to independently confirm the accuracy of DNA and fingerprint analyses, says CU-Boulder Assistant Professor Noah Fierer, chief author on the study.

"Each one of us leaves a unique trail of bugs behind as we travel through our daily lives," said Fierer, an assistant professor in CU-Boulder's ecology and evolutionary biology department. "While this project is still in its preliminary stages, we think the technique could eventually become a valuable new item in the toolbox of forensic scientists."

The study was published March 15 in the Proceedings of the National Academy of Sciences. Co-authors on the PNAS study included Christian Lauber and Nick Zhou of CU-Boulder's Cooperative Institute for Research in Environmental Sciences, or CIRES, Daniel McDonald of CU-Boulder's department of chemistry and biochemistry, Stanford University Postdoctoral Researcher Elizabeth Costello and CU-Boulder chemistry and biochemistry Assistant Professor Rob Knight.

Using powerful gene-sequencing techniques, the team swabbed bacterial DNA from individual keys on three personal computers and matched them up to bacteria on the fingertips of keyboard owners, comparing the results to swabs taken from other keyboards never touched by the subjects. The bacterial DNA from the keys matched much more closely to bacteria of keyboard owners than to bacterial samples taken from random fingertips and from other keyboards, Fierer said.

In a second test, the team swabbed nine keyboard mice that had not been touched in more than 12 hours and collected palm bacteria from the mouse owners. The team compared the similarity between the owner's palm bacteria and owner's mouse with 270 randomly selected bacterial samples from palms that had never touched the mouse. In all nine cases, the bacterial community on each mouse was much more similar to the owner's hand.

The team sampled private and public computers at CU-Boulder, as well as hand bacteria collected from a variety of volunteers on campus. The study showed the new technique is about 70 to 90 percent accurate, a percentage that likely will rise as the technology becomes more sophisticated, said Fierer, who also is a CIRES fellow.

In an effort to see how persistent the bacteria colonies were, the team also swabbed the skin surfaces of two individuals, freezing one set of samples at minus 4 degrees Fahrenheit and leaving the other room temperature. The results showed room-temperature bacterial colonies remained essentially unchanged after two weeks, pointing up the technique's potential as a forensic tool. "That finding was a real surprise to us," said Fierer. "We didn't know just how hearty these creatures were."

Previous research by Fierer and his colleagues -- which indicated a typical hand carries about 150 bacterial species -- also showed only 13 percent of bacteria species found a single hand were shared by any two people. "The obvious question then was whether we could identify objects that have been touched by particular individuals," Fierer said.

The CU-Boulder team used a "metagenomic" survey to simultaneously analyze all of the bacteria on the fingers, palms and computer equipment, said Knight. The effort involved isolating and amplifying tiny bits of microbial DNA, then building complementary DNA strands with a high-powered sequencing machine that allowed the team to identify different families, genera and species of bacteria from the sample.

"This is something we couldn't have done even two years ago," said Fierer. "Right now we can sequence bacterial DNA from 450 samples at once, and we think the number will be up to 1,000 by next year. And as the cost of the technology continues to drop, even smaller labs could undertake these types of projects."

Another reason the new technique may prove valuable to forensic experts is that unless there is blood, tissue, semen or saliva on an object, it's often difficult to obtain sufficient human DNA for forensic identification, said Fierer. But given the abundance of bacterial cells on the skin surface, it may be easier to recover bacterial DNA than human DNA from touched surfaces, they said. "Our technique could provide another independent line of evidence."

More research needs to done on how human bacterial signatures adhere to different surfaces like metal, plastic and glass, said Fierer. But the new technique may be useful for linking objects to users in cases where clear fingerprints cannot be obtained – from smudged surfaces, fabrics and highly textured materials, he said. The new technique would even be useful for identifying objects touched by identical twins, since they share identical DNA but they have different bacterial communities on their hands.

The new PNAS study was funded by the National Science Foundation, the National Institutes of Health, the Crohn's and Colitis Foundation of America and the Howard Hughes Medical Institute.

"This project is one example of why I got into science," said Fierer. "We go down a lot of different paths trying to answer research questions we have, some of which pan out and some that don't. This particular project is exciting for the whole team."

Fierer said the new technique brings up bioethical issues to consider, including privacy. "While there are legal restrictions on the use of DNA and fingerprints, which are ‘personally-identifying', there currently are no restrictions on the use of human-associated bacteria to identify individuals," he said. "This is an issue we think needs to be considered."

In a related November 2009 CU study led by Knight, the team developed the first atlas of microbial diversity across the human body, charting wide variations in microbe populations from the forehead and feet to noses and navels of individuals. One goal of the human bacterial atlas project is to find out what is normal to healthy people to provide a baseline for studies looking at human disease states, said Knight.

Working with a $1.1 million NIH grant to develop new computational tools to better understand the composition and dynamics of microbial communities, Knight and his colleagues have been developing novel methods to tag DNA samples with error-correcting "barcodes" to obtain more accurate gene sequencing data.

In the 2008 hand bacteria study, the researchers detected and identified more than 4,700 different bacteria species across 102 human hands in the study, only five species of which were shared among all 51 participants. The study also showed that the diversity of bacteria on individual hands was not significantly affected by regular hand washing.

(Photo: Steve Miller, CIRES)

University of Colorado

FOR BETTER ROMANTIC RELATIONSHIPS, BE TRUE TO YOURSELF

0 comentarios

Be true to yourself, and better romantic relationships will follow, research suggests.

A new study examined how dating relationships were affected by the ability of people to see themselves clearly and objectively, act in ways consistent with their beliefs, and interact honestly and truthfully with others.

In other words, the ability to follow the words of William Shakespeare: “to thine own self be true,” said Amy Brunell, lead author of the study and assistant professor of psychology at Ohio State University’s Newark campus.

Findings showed that college students who reported being more true to themselves also reported more positive dating relationships.

“If you’re true to yourself, it is easier to act in ways that build intimacy in relationships, and that’s going to make your relationship more fulfilling,” Brunell said.

The study appears online in the journal Personality and Individual Differences and will be published in an upcoming print edition.

Participating in the study were 62 heterosexual couples, all of whom were college students. The participants completed a long list of questionnaires in three separate sessions that took place about two weeks apart.

The first set of questionnaires probed how true participants were to themselves, a characteristic that psychologists call “dispositional authenticity.” This was measured through the answers to questions like “For better or for worse, I am aware of who I truly am.”

In the second phase, participants answered questions examining various aspects of their relationship functioning, including their willingness to discuss their emotions with their partner, and whether they kept secrets.

The third phase involved measures of relationship satisfaction and personal well-being.

Overall, the study found that both men and women who reported being more true to themselves also behaved in more intimate and less destructive ways with their partner, and that led to them feeling their relationship was more positive. In addition, they also reported greater personal well-being.

But the study revealed an interesting gender difference in how authenticity in men and women affected their partners, Brunell said.

Men who were more true to themselves had partners who showed more healthy relationship behaviors. However, there was no significant relationship between women being true to themselves and men’s relationship behaviors.

That finding may be the result of relationship gender roles in our society, she said.

“Typically in dating and marital relationships, the women tend to be ‘in charge’ of intimacy in the relationship,” Brunell explained.

“So when men have this dispositional authenticity, and want to have an open, honest relationship, it makes women’s job easier – they can more easily regulate intimacy,” she said.

But since men have less of a role in developing relationship intimacy, they were not affected as much by whether their partners were true to themselves or not.

The study also confirmed findings from other studies that show that when men or women act in constructive, healthy ways in a relationship, it increases their partners’ satisfaction with the relationship.

Brunell said being true to yourself doesn’t mean that you should accept all of your flaws and not try to make positive changes in your life. But you should be aware of both your limitations and areas where you can improve. One payoff could be better romantic relationships.

“It shouldn’t be a surprise, but being true to yourself is linked to having healthier and happier relationships for both men and women,” she said.

(Photo: OSU)

Ohio State University

RESEARCH REVEALS MASSIVE EXTENT OF SLAVERY BETWEEN MUSLIMS, CHRISTIANS FOR THREE CENTURIES

0 comentarios

Although most people think of slavery as a matter of racial oppression, new research has suggested that, between 1500 and 1800, human bondage was often based on religion rather than on race.

Long-running hostilities between Muslims and Christians in Europe, Africa, and the Middle East during these three centuries resulted in the enslavement of at least 3 million people of both faiths, according to Robert C. Davis, professor of history at Ohio State University.

Davis examined this “faith slavery” – a term he coined -- in his new book, Holy War and Human Bondage: Tales of Christian-Muslim Slavery in the Early-Modern Mediterranean (Praeger).

As a result of his research, Davis estimated that during these centuries more than 1 million Muslims were enslaved in Europe and another 2 million Christians suffered the same fate in North Africa and the Near East.

“Faith slavery had huge economic and social consequences at the time but most people today don’t even know about it,” Davis said.

Though we are familiar with the clash between Christianity and Islam today, in early-modern times the balance of forces was much different from what it is now, according to Davis.

“During this period, both sides, Muslims and Christians, had nearly equal power,” Davis said. “It was really a clash of empires and taking slaves was part of the conflict.”

If people today are familiar with faith slavery at all, it is because of novels and films about Muslim corsairs who used Christians as their galley slaves and about Turkish harems including Christian slave women.

But in reality Mediterranean slavery was much more extensive, and much more brutal, than these fictional versions might suggest, Davis says.

Muslim corsairs would capture ships and raid seaside towns in the Mediterranean and Atlantic, in search of men, women and children for slaves.

Once captured, men were made to row galleys, work in heavy construction, at stone quarries, or on private farms. Women were typically sold into harems, for either household or sexual duties.

But faith slavery went both ways: many thousands of Muslims were also captured and enslaved, in Italy, Spain, and Malta.

Davis first explored faith slavery in his 2004 book, Christian Slaves, Muslim Master: White Slavery in the Mediterranean, the Barbary Coast, and Italy, 1500-1800 (Palgrave MacMillian).

To calculate how many Europeans were enslaved on Africa’s Barbary Coast, Davis developed a unique methodology in that book. Taking the best contemporary estimates of how many slaves were at each location at a given time, he then calculated how many new slaves it would take to replace the ones who died, escaped or were ransomed.

He felt that this is the best way available to make enslavement estimates, given the limited records.

In his new book, he expanded this research methodology to calculate how many Christians were enslaved in the Near East, as well as the extent of Islamic slavery in Christian Europe.

“Even rough calculations make it clear that Mediterranean faith slaving was not some minor phenomenon, a petty problem for people at the time, as has been assumed by many historians today,” Davis said.

“Rather, it was a huge business and a vital part of the economy and the social fabric at the time.”

Entire villages along the coast of Italy and Spain were abandoned after raids by Muslim corsairs, Davis said.

In addition, ransoming back a slave was expensive – a year’s income or more for many Europeans.

“The sheer expense of getting their loved ones back represented an enormous transfer of wealth from Europe to Africa,” he said (Muslim slaves were more rarely ransomed).

And while faith slaving was concentrated in the Mediterranean, its reach extended far beyond, Davis found.

In 1627, for instance, a corsair raid on Iceland brought about 400 Icelandic slaves to Algiers. Similar attacks were carried out in Ireland and all along the English coast in the 1630s and 1640s. Most of the captives died in slavery.

Nor was the United States immune. One of the many personal stories that Davis used to give a human face to the statistics is that of the American seaman John Foss. Captured by Algerian corsairs near Spain in 1793, Foss and his fellow crew members labored as slaves for two years before the fledgling American government finally ransomed them.

In his journal, Foss recalled how he, together with 130 fellow Americans and a thousand or more other slaves quarried and hauled enormous stone blocks under the overseers’ lash.

Faith slavery was different in one significant way from the more familiar race slavery, Davis said. Faith slaves, both Christian and Muslim, could convert to their masters’ religion.

For Christians, conversion to Islam was simple: all they had to do was swear there was one God, and his name was Allah.

But the results of their conversion were mixed. Though now Muslims, such “renegades” were still slaves, even if their masters usually gave them easier work. On the other hand, such converts had a much lower chance of being ransomed.

“A Muslim slave owner who let a Muslim slave be ransomed was essentially abandoning someone from the faith, which was punishable by death,” Davis said.

Consequently, many Muslim slave owners didn’t want their Christians slaves to convert. Davis told of one master who beat a would-be renegade until the slave recanted his conversion.

Given the historical magnitude and impact of faith slavery, Davis said he is often asked why more people don’t know about it and why it isn’t taught in schools.

Davis admitted he is not entirely sure. One reason, he said, may be that faith slavery “does not fit the historical master narrative that people in the United States and Europe tend to assume.”

“This narrative holds that from Columbus’ time until the 20th century, history was largely about European colonial expansion, with the imposition of white, European, Christian power on much of the world,” Davis said.

“This story of faith slavery does not fit that narrative. The idea that triumphant Europeans were not everywhere inflicting their dominance on others seems counter-intuitive,” Davis said.

“But in fact, during this centuries-long struggle between nearly equal empires, millions of European Christians ended up enslaved in Muslim hands.”

Some historians have minimized faith slavery by calling victims “captives” rather than “slaves,” as if they were simply prisoners of war. They argue that since some of those captured were eventually ransomed, they were never really slaves.

“That ignores the fact that more than half of the Christian slaves, and almost all of the Muslims, were never ransomed,” Davis said.

Moreover, these faith slaves were treated very much like the more familiar African slaves, Davis said: made to work long days in difficult, dangerous jobs, poorly fed and brutally beaten.

“Some people assume that faith slavery, because it was not based on race, was less brutal or dehumanizing. Nothing could be further from the truth,” he said.

“Just as with black Africans, faith slaves were considered commodities to be bought and sold. If anything, religious intolerance justified extremely cruel and harsh treatment of both Christian and Muslim slaves.”

Davis noted that race slavery ensnared more victims than faith slavery. About 10 to 12 million black Africans were brought to the Americas as slaves, over three times the number he has calculated for Mediterranean faith slaves.

“But that shouldn’t minimize the huge impact that 3 or 4 million faith slaves had on history.”

Davis said he hopes his research encourages people to remember an historical reality that is often forgotten or ignored.

“Faith slavery played an important role in both American and European history. It deserves more attention,” Davis said.

Yet Davis has taken issue with the argument that the slavery of white Europeans somehow mitigates or diminishes the enslavement of black Africans in the Americas.

“That doesn’t make sense to me. Though faith and race slavery were both pervasive in these centuries, the enslavement of some white Christians can hardly balance the moral wrong of the slavery other whites inflicted on Africans,” he said. “Two such enormous wrongs don’t make anything right.”

(Photo: OSU)

Ohio State University

Tuesday, March 30, 2010

CATASTROPHIC FLOODING MAY BE MORE PREDICTABLE AFTER PENN RESEARCHERS BUILD A MINI RIVER DELTA

0 comentarios

An interdisciplinary team of physicists and geologists led by the University of Pennsylvania has made a major step toward predicting where and how large floods occur on river deltas and alluvial fans.

In a laboratory, researchers created a miniature river delta that replicates flooding patterns seen in natural rivers, resulting in a mathematical model capable of aiding in the prediction of the next catastrophic flood.

The results appear in the current issue of Geophysical Research Letters.

Slow deposition of sediment within rivers eventually fills channels, forcing water to spill into surrounding areas and find a new, steeper path. The process is called avulsion. The result, with the proper conditions, is catastrophic flooding and permanent relocation of the river channel.

The goal of the Penn research was to improve prediction of why and where such flooding will occur and to determine how this avulsion process builds deltas and fans over geologic time.

Research was motivated by the Aug. 18, 2008, flooding of the Kosi River fan in northern India, where an artificial embankment was breached and the resulting floodwaters displaced more than a million people. Looking at satellite pictures, scientists from Penn and University of Minnesota Duluth noticed that floodwaters principally filled abandoned channel paths.

Meredith Reitz, lead author of the study and a graduate student in the Department of Physics and Astronomy in Penn’s School of Arts and Sciences, conducted a set of four laboratory experiments to study the avulsion process in detail. Reitz injected a mixture of water and sediment into a bathtub-sized tank and documented the formation and avulsion of river channels as they built a meter-sized delta.

“Reducing the scale of the system allows us to speed up time,” Reiz said. “We can observe processes in the lab that we could never see in nature.”

The laboratory experiments showed flooding patterns that were remarkably similar to the Kosi fan and revealed that flooding and channel relocation followed a repetitive cycle.

One major finding was that the formation of a river channel on a delta followed a random path; however, once a network of channels was formed, avulsion consistently returned flow to these same channels, rather than creating new ones. An additional important finding was that the average frequency of flooding was determined by how long it took to fill a channel with sediment. Researchers constructed a mathematical model incorporating these two ideas, which was able to reproduce the statistical behavior of flooding.

“Avulsions on river deltas and fans are like earthquakes,” said Douglas Jerolmack, director of the Sediment Dynamics Laboratory in the Department of Earth and Environmental Science at Penn and a co-author of the study. “It is impossible to predict exactly where and when they will occur, but we might be able to predict approximately how often they will occur and which areas are most vulnerable. Just as earthquakes occur along pre-existing faults, flooding occurs along pre-existing channel paths. If you want to know where floodwaters will go, find the old channels.”

The authors derived a simple method for estimating the recurrence interval of catastrophic flooding on real deltas. When used in conjunction with satellite images and topographic maps, this work will allow for enhanced flood hazard prediction. Such prediction is needed to protect the hundreds of millions of people who are threatened by flooding on river deltas and alluvial fans. The work could also help in exploration for oil reservoirs, because sandy river channels are an important source of hydrocarbons.

(Photo: NASA Earth Observatory)

University of Pennsylvania

UA ASTRONOMERS DISCOVER MOST PRIMITIVE SUPERMASSIVE HOLES KNOWN

0 comentarios

Astronomers have come across what appear to be two of the earliest and most primitive supermassive black holes known. The discovery will provide a better understanding of the roots of our universe, and how the very first black holes, galaxies and stars all came to be.

Astronomers have come across what appear to be two of the earliest and most primitive supermassive black holes known. The discovery, based largely on observations from NASA's Spitzer Space Telescope, will provide a better understanding of the roots of our universe, and how the very first black holes, galaxies and stars all came to be.

"We have found what are likely first-generation quasars, born in a dust-free medium and at the earliest stages of evolution," said Linhua Jiang, a research associate at the University of Arizona's Steward Observatory. Jiang is the lead author on a paper announcing the findings in the March 18 issue of Nature.

Black holes are beastly distortions of space and time. The most massive and active ones lurk at the cores of galaxies, and are usually surrounded by doughnut-shaped structures of dust and gas that feed and sustain the growing black holes. These hungry supermassive black holes are called quasars.

As grimy and unkempt as our present-day universe is today, scientists believe the very early universe didn't have any dust – which tells them that the most primitive quasars should also be dust-free. But nobody had seen such pristine quasars – until now. Spitzer has identified two such immaculate quasars – the smallest quasars on record – about 13 billion light-years away from Earth.

The two quasars, called J0005-0006 and J0303-0019, were first unveiled by Xiaohui Fan, a UA professor of astronomy who coauthored the paper. Jiang and their colleagues, using visible-light data from the Sloan Digital Sky Survey. NASA's Chandra X-ray Observatory had also observed X-rays from one of the objects. X-rays, ultraviolet and optical light stream out from quasars as the gas surrounding them is swallowed.

"As surrounding gas is swallowed by the supermassive black hole, it emits an enormous amount of light, making those quasars detectable literally at the edge of the observable universe," said Fan.

When Jiang and his colleagues set out to observe J0005-0006 and J0303-0019 with Spitzer between 2006 and 2009, their targets didn't stand out much from the usual quasar bunch. Spitzer measured infrared light from the objects along with 18 others, all belonging to a class of the most distant quasars known. Each quasar is anchored by a supermassive black hole weighing more than 100 million suns.

The Spitzer data showed that, of the 20 quasars, J0005-0006 and J0303-0019 lacked characteristic signatures of hot dust. Spitzer's infrared sight makes the space telescope ideally suited to detect the warm glow of dust that has been heated by the feeding black holes.

This is the first observation project to combine data from all three of Spitzer's instruments, including the Multiband Imaging Photometer, or MIPS, a far-infrared camera built at UA's Steward Observatory that gives the Spitzer telescope is ability to see very cold dust.

"The most exciting discovery for us is what we don't see," said Fan, "the dust that typically surrounds all other quasars that have been found so far."

"We think these early black holes are forming around the time when the dust was first forming in the universe, less than one billion years after the Big Bang," Fan added. "The primordial universe did not contain any molecules that could coagulate to form dust. The elements necessary for this process were produced and pumped into the universe later by stars."

The astronomers also observed that the amount of hot dust in a quasar goes up with the mass of its black hole. As a black hole grows, dust has more time to materialize around it. The black holes at the cores of J0005-0006 and J0303-0019 have the smallest measured masses known in the early universe, indicating they are particularly young, and at a stage when dust has not yet formed around them.

(Photo: NASA/JPL-Caltech)

University of Arizona

ULTRA-POWERFUL LASER MAKES SILICON PUMP LIQUID UPHILL WITH NO ADDED ENERGY

0 comentarios
Researchers at the University of Rochester's Institute of Optics have discovered a way to make liquid flow vertically upward along a silicon surface, overcoming the pull of gravity, without pumps or other mechanical devices.

In a paper in the journal Optics Express, professor Chunlei Guo and his assistant Anatoliy Vorobyev demonstrate that by carving intricate patterns in silicon with extremely short, high-powered laser bursts, they can get liquid to climb to the top of a silicon chip like it was being sucked through a straw.

Unlike a straw, though, there is no outside pressure pushing the liquid up; it rises on its own accord. By creating nanometer-scale structures in silicon, Guo greatly increases the attraction that water molecules feel toward it. The attraction, or hydrophile, of the silicon becomes so great, in fact, that it overcomes the strong bond that water molecules feel for other water molecules.

Thus, instead of sticking to each other, the water molecules climb over one another for a chance to be next to the silicon. (This might seem like getting energy for free, but even though the water rises, thus gaining potential energy, the chemical bonds holding the water to the silicon require a lower energy than the ones holding the water molecules to other water molecules.) The water rushes up the surface at speeds of 3.5 cm per second.

Yet the laser incisions are so precise and nondestructive that the surface feels smooth and unaltered to the touch.

In a paper a few months ago in the journal Applied Physics Letters, the same researchers proved that the phenomenon was possible with metal, but extending it to silicon could have some important implications. For instance, Guo said, this work could pave the way for novel cooling systems for computers that operate much more effectively, elegantly, and efficiently than currently available options.

"Heat is definitely the number one problem deterring the design of faster conventional processors," said Michael Scott, a professor of computer science at the University, who is not involved in this research.

Computer chips are essentially wafers of silicon covered with billions of microscopic transistors that communicate by sending electrical signals through metal wires that connect them. As technological innovations make it possible to pack astounding numbers of transistors on small pieces of silicon, computer processing speeds could increase substantially; however, the electrical current constantly surging through the chips creates a lot of heat, Scott said. If left unchecked, the heat can melt or otherwise destroy the chip components.

Most computers these days are cooled with fans. Essentially, the air around the circuit components absorbs the heat that is generated and the fan blows that hot air away from the components. The disadvantages of this method are that cold air cannot absorb very much heat before becoming hot, making fans ineffective for faster processors, and fans are noisy.

For these reasons, many companies have been eager to investigate the possibility of using liquid as a coolant instead of air. Liquids can absorb far more heat, and transmit heat much more effectively than air. So far, designers have not created liquid cooling systems that are cost-effective and energy efficient enough to become widely used in economical personal computers. Although Guo's discovery has not yet been incorporated into a prototype, he thinks that silicon that can pump its own coolant has the potential to contribute greatly to the design of future cooling systems.

University of Rochester

NEW REPORT REVEALS THE ENVIRONMENTAL AND SOCIAL IMPACT OF THE 'LIVESTOCK REVOLUTION'

0 comentarios

Global meat production has tripled in the past three decades and could double its present level by 2050, according to a new report on the livestock industry by an international team of scientists and policy experts. The impact of this "livestock revolution" is likely to have significant consequences for human health, the environment and the global economy, the authors conclude.

"The livestock industry is massive and growing," said Harold A. Mooney, co-editor of the two-volume report, Livestock in a Changing Landscape (Island Press). Mooney is a professor of biology and senior fellow at the Woods Institute for the Environment.

"This is the first time that we've looked at the social, economic, health and environmental impacts of livestock in an integrated way and presented solutions for reducing the detrimental effects of the industry and enhancing its positive attributes," he said.

Among the key findings in the report are:

-More than 1.7 billion animals are used in livestock production worldwide and occupy more than one-fourth of the Earth's land.
-Production of animal feed consumes about one-third of total arable land.
-Livestock production accounts for approximately 40 percent of the global agricultural gross domestic product.
-The livestock sector, including feed production and transport, is responsible for about 18 percent of all greenhouse gas emissions worldwide.

Although about 1 billion poor people worldwide derive at least some part of their livelihood from domesticated animals, the rapid growth of commercialized industrial livestock has reduced employment opportunities for many, according to the report. In developing countries, such as India and China, large-scale industrial production has displaced many small, rural producers, who are under additional pressure from health authorities to meet the food safety standards that a globalized marketplace requires.

Beef, poultry, pork and other meat products provide one-third of humanity's protein intake, but the impact on nutrition across the globe is highly variable, according to the report. "Too much animal-based protein is not good for human diets, while too little is a problem for those on a protein-starved diet, as happens in many developing countries," Mooney noted.

While overconsumption of animal-source foods – particularly meat, milk and eggs – has been linked to heart disease and other chronic conditions, these foods remain a vital source of protein and nutrient nutrition throughout the developing world, the report said. The authors cited a recent study of Kenyan children that found a positive association between meat intake and physical growth, cognitive function and school performance.

Human health also is affected by pathogens and harmful substances transmitted by livestock, the authors said. Emerging diseases, such as highly pathogenic avian influenza, are closely linked to changes in the livestock production but are more difficult to trace and combat in the newly globalized marketplace, they said.

The livestock sector is a major environmental polluter, the authors said, noting that much of the world's pastureland has been degraded by grazing or feed production, and that many forests have been clear-cut to make way for additional farmland. Feed production also requires intensive use of water, fertilizer, pesticides and fossil fuels, added co-editor Henning Steinfeld of the United Nations Food and Agriculture Organization (FAO).

Animal waste is another serious concern. "Because only a third of the nutrients fed to animals are absorbed, animal waste is a leading factor in the pollution of land and water resources, as observed in case studies in China, India, the United States and Denmark," the authors wrote. Total phosphorous excretions are estimated to be seven to nine times greater than that of humans, with detrimental effects on the environment.

The beef, pork and poultry industries also emit large amounts of carbon dioxide, methane and other greenhouse gases, Steinfeld said, adding that climate-change issues related to livestock remain largely unaddressed. "Without a change in current practices, the intensive increases in projected livestock production systems will double the current environmental burden and will contribute to large-scale ecosystem degradation unless appropriate measures are taken," he said.

The report concludes with a review of various options for introducing more environmentally and socially sustainable practices to animal production systems.

"We want to protect those on the margins who are dependent on a handful of livestock for their livelihood," Mooney said. "On the other side, we want people engaged in the livestock industry to look closely at the report and determine what improvements they can make."

One solution is for countries to adopt policies that provide incentives for better management practices that focus on land conservation and more efficient water and fertilizer use, he said.

But calculating the true cost of meat production is a daunting task, Mooney added. Consider the piece of ham on your breakfast plate, and where it came from before landing on your grocery shelf. First, take into account the amount of land used to rear the pig. Then factor in all the land, water and fertilizer used to grow the grain to feed the pig and the associated pollution that results.

Finally, consider that while the ham may have come from Denmark, where there are twice as many pigs as people, the grain to feed the animal was likely grown in Brazil, where rainforests are constantly being cleared to grow more soybeans, a major source of pig feed.

"So much of the problem comes down to the individual consumer," said co-editor Fritz Schneider of the Swiss College of Agriculture (SHL). "People aren't going to stop eating meat, but I am always hopeful that as people learn more, they do change their behavior. If they are informed that they do have choices to help build a more sustainable and equitable world, they can make better choices."

(Photo: Keith Weller; Agricultural Research Service; USDA)

Stanford University

JAWS -- 4 MILLION B.C.

0 comentarios
It might sound like a mashup of monster movies, but palaeontologists have discovered evidence of how an extinct shark attacked its prey, reconstructing a killing that took place 4 million years ago.

Such fossil evidence of behaviour is incredibly rare, but by careful, forensic-style analysis of bite marks on an otherwise well-preserved dolphin skeleton, the research team, based in Pisa, Italy, have reconstructed the events that led to the death of the dolphin, and determined the probably identity of the killer: a 4 m shark by the name of Cosmopolitodus hastalis.

The evidence, published in the latest issue of the journal Palaeontology, comes from the fossilised skeleton of a 2.8 m long dolphin discovered in the Piedmont region of northern Italy.

According to Giovanni Bianucci, who led the study: "the skeleton lay unstudied in a museum in Torino for more than a century, but when I examined it, as part of a larger study of fossil dolphins, I noticed the bite marks on the ribs, vertebrae and jaws. Identifying the victim of the attack was the easy part - it's an extinct species of dolphin known as Astadelphis gastaldii– working out the identity of the killer called for some serious detective work, as the only evidence to go on was the bite marks."

The overall shape of the bite indicated a shark attack, and Bianucci called in fossil shark expert Walter Landini. "The smoothness of the bite marks on the ribs clearly shows that the teeth of whatever did the biting were not serrated, and that immediately ruled out some possibilities. We simulated bite marks of the potential culprits and, by comparing them with the shape and size of the marks on the fossils, we narrowed it down to Cosmopolitodus hastalis." Circumstantial evidence also supports this verdict: fossil teeth from Cosmopolitodus are common in the rock sequences that the dolphin was found in. "From the size of the bite, we reckon that this particular shark was about 4 m long" says Landini.

Detailed analysis of the bite pattern allowed the researchers to go even further. "The deepest and clearest incisions are on the ribs of the dolphin" says Bianucci, "indicating the shark attached from below, biting into the abdomen. Caught in the powerful bite, the dolphin would have struggled, and the shark probably detached a big amount of flesh by shaking its body from side to side. The bite would have caused severe damage and intense blood loss, because of the dense network of nerves, blood vessels and vital organs in this area. Then, already dead or in a state of shock, the dolphin rolled onto its back, and the shark bit again, close to the fleshy dorsal fin."

The study is significant because of the rarity of such 'fossilized behaviour'. According to Dr Kenshu Shimada, fossil shark expert at DePaul University and the Sternberg Museum of Natural History in the US, "studies like this are important because they give us a glimpse of the ecological interactions between organisms in prehistoric seas. Shark teeth are among the most common vertebrate remains in the fossil record, yet interpreting the details of diet and feeding behaviour of extinct sharks is extremely difficult. Fossil remains of prey species with shark bite marks, like those described by Bianucci and his team, provide direct evidence of what each prehistoric shark ate and how it behaved."

Wiley-Blackwell

SHUTTING OUT SOFT TISSUE CANCERS IN THE COLD

0 comentarios
Cryotherapy, an interventional radiology treatment to freeze cancer tumors, may become the treatment of the future for cancer that has metastasized in soft tissues (such as ovarian cancer) and in bone tumors. Such patients are often not candidates for surgery and would benefit from minimally invasive treatment, say researchers at the Society of Interventional Radiology's 35th Annual Scientific Meeting in Tampa, Fla.

"Improved treatment options are needed for individuals affected by metastases in bone and soft tissues since patients with multifocal metastatic disease are often not candidates for surgery," said Peter J. Littrup, M.D., an interventional radiologist and director of imaging research and image-guided therapy for the Barbara Ann Karmanos Cancer Institute in Detroit, Mich. "Percutaneous soft tissue cryotherapy is a well-tolerated treatment option, especially for patients with anesthesia risks, painful lesions or those seeking local control during chemotherapy. Tumor size and/or location do not preclude thorough treatment or pose greater risk with appropriate precautions," added Littrup, who is also a professor of radiology, urology and radiation oncology at Wayne State University in Detroit. In the 97-patient study, researchers used sufficient deadly temperatures to effectively kill tumor cells, resulting in an average of 77 percent tumor shrinkage in patients after 24 months. "Because of the variable placement of tumors within these soft tissue and bone locations, this study shows the versatility of this treatment option when using proper techniques to safeguard nearby structures. Aside from the successful tumor control, what makes this technique even more preferable is the excellent tumor shrinkage since the underlying fibrous or collagenous structures are preserved. The body can then better heal at the ablation (removal) site with minimal additional scar tissue formation," said Littrup.

Last year, it was estimated that 1.5 million new cases of cancer were diagnosed, and up to 85 percent of patients who have breast, prostate or lung cancer have bone metastases at the time of death. Additionally, 5 percent of all cancers result in skin cancer as well. Based on these numbers, conservative estimates determine that up to 500,000 of these newly diagnosed cancer patients alone will suffer from metastatic disease in bone and soft tissue areas. Cryotherapy is a good option for a large—but perhaps under-recognized—problem that could deliver a quantum impact. Namely, the original cancer tumor site (or even a few unresponsive tumors sites) can still cause cancer management problems even after a generally good response to chemotherapy and/or radiation therapy, said Littrup. "Metastasized tumors can occur nearly anywhere in the body and frequently cannot receive additional radiation therapy or would be difficult or very morbid to be controlled with surgery," said Littrup. "Cryotherapy was able to preserve quality of life by providing good local treatment with minimal side effects, especially with advanced stages of cancer where any additional treatment is unlikely to provide a systemic cure," he added. However, cryotherapy is not a first-line therapy for tumor treatment. Despite "superb" cryotherapy outcomes for many tumor types and locations, medical insurance may not cover the treatment, said Littrup.

Historically, cyoablation has been performed on the prostate and liver, but this technique has been recently found effective in other tumors including the breast, kidney and lung. "We simply translated this concept to retroperitoneal, intraperitoneal, superficial and bone locations in order to generate successful use of cryotherapy in different patient groups," said Littrup. The major benefits of cryotherapy are its superb visualization of the ice treatment zone during the procedure, its low pain profile in an outpatient setting and its excellent healing with minimal scar, said Littrup. In this study's cryotherapy treatment, researchers used several needle-like cryoprobes that were inserted through the skin to deliver extremely cold gas directly to a tumor to freeze it. This technique has been used for many years by surgeons in the operating room; however, in the last few years, the needles have become small enough to be used by interventional radiologists through a small nick in the skin, without the need for an operation. The "ice ball" that is created around the needle grows in size and destroys the frozen tumor cells. Surgeons and radiation oncologists have long tried to provide at least a 1-centimer margin of treatment with cancer tumors, and it was important to assure a similar "surgical margin" of lethal temperatures beyond all tumor margins by cryotherapy in this study, said Littrup.

"One of our first soft tissue cryotherapy patients with recurrent ovarian cancer encouraged us to really begin this study," said Littrup. This patient has now undergone seven cryoablation procedures over the last five years in combination with only a few additional cycles of chemotherapy when more than one to two recurrences were noted, he said. "She called cryotherapy a major 'holiday' from chemotherapy and has been one of our big advocates, referring many other ovarian cancer patients with isolated recurrences," said Littrup.

In the study, 157 computed tomography/CT- and/or ultrasound/US-guided percutaneous cryotherapy procedures were performed (retroperitoneal, 30; intraperitoneal, 51; superficial, 47; and bone, 29) in 97 patients. Protection of adjacent crucial tissues (for example, skin, bowel) from cytotoxic temperatures was achieved by thermocouple monitoring, saline injection and/or direct skin warming. Patients were followed by CT or magnetic resonance imaging (MRI). The cryotherapy zone was well-defined by CT as a hypodense ice ball with an average ablation diameter of 5.4 centimeters; average tumor diameter was 3.5 centimeters.

Interventional radiologists are leaders in percutaneous cryotherapy because it requires interventional skills and a thorough understanding of cross-sectional imaging (US, CT, MRI) and IRs are the only physicians who have this rigorously trained skill set combination, said Littrup. Continued study is needed to determine the optimum probe number, spacing and freeze times needed to produce thorough ice coverage of all soft tissue tumors, he said. "With recent developments of powerful new cryotechnology, multiple directions for soft tissue cryotherapy can be pursued, including translating the current, somewhat challenging, procedure done with ultrasound and/or CT guidance to a more consistent and reproducible MR-guided approach," said Littrup. Cryotechnology promises to be more MR-compatible and would also allow accurate targeting of more difficult-to-see tumors. More importantly, larger studies in multiple centers needs to be done, following these basic cryobiology principles of sufficient lethal temperatures generated by multiple cryoprobes spaced evenly throughout a cancer region, he added.

Society of Interventional Radiology

Monday, March 29, 2010

NANO-BASED RFID TAGS COULD REPLACE BAR CODES

0 comentarios

Long lines at store checkouts could be history if a new technology created in part at Rice University comes to pass.

Rice researchers, in collaboration with a team led by Gyou-jin Cho at Sunchon National University in Korea, have come up with an inexpensive, printable transmitter that can be invisibly embedded in packaging. It would allow a customer to walk a cart full of groceries or other goods past a scanner on the way to the car; the scanner would read all items in the cart at once, total them up and charge the customer's account while adjusting the store's inventory.

More advanced versions could collect all the information about the contents of a store in an instant, letting a retailer know where every package is at any time.

The technology reported in the March issue of the journal IEEE Transactions on Electron Devices is based on a carbon-nanotube-infused ink for ink-jet printers first developed in the Rice lab of James Tour, the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science. The ink is used to make thin-film transistors, a key element in radio-frequency identification (RFID) tags that can be printed on paper or plastic.

"We are going to a society where RFID is a key player," said Cho, a professor of printed electronics engineering at Sunchon, who expects the technology to mature in five years. Cho and his team are developing the electronics as well as the roll-to-roll printing process that, he said, will bring the cost of printing the tags down to a penny apiece and make them ubiquitous.

RFID tags are almost everywhere already. The tiny electronic transmitters are used to identify and track products and farm animals. They're in passports, library books and devices that let drivers pass through tollbooths without digging for change.

The technology behind RFID goes back to the 1940s, when Léon Theremin, inventor of the self-named electronic music instrument heard in so many '50s science fiction and horror movies, came up with a spy tool for the Soviet Union that drew power from and retransmitted radio waves.

RFID itself came into being in the 1970s and has been widely adopted by the Department of Defense and industry to track shipping containers as they make their way around the world, among many other uses.

But RFID tags to date are largely silicon-based. Paper or plastic tags printed as part of a package would cut costs dramatically. Cho expects his roll-to-roll technique, which uses a gravure process rather than ink-jet printers, to replace the bar codes now festooned on just about everything you can buy.

Cho, Tour and their teams reported in the journal a three-step process to print one-bit tags, including the antenna, electrodes and dielectric layers, on plastic foil. Cho's lab is working on 16-bit tags that would hold a more practical amount of information and be printable on paper as well.

Cho came across Tour's inks while spending a sabbatical at Rice in 2005. "Professor Tour first recommended we use single-walled carbon nanotubes for printing thin-film transistors," Cho said.

Tour's lab continues to support the project in an advisory role and occasionally hosts Cho's students. Tour said Rice owns half of the patent, still pending, upon which all of the technology is based. "Gyou-jin has carried the brunt of this, and it's his sole project," Tour said. "We are advisers and we still send him the raw materials" -- the single-walled carbon nanotubes produced at Rice.

Printable RFIDs are practical because they're passive. The tags power up when hit by radio waves at the right frequency and return the information they contain. "If there's no power source, there's no lifetime limit. When they receive the RF signal, they emit," Tour said.

There are several hurdles to commercialization. First, the device must be reduced to the size of a bar code, about a third the size of the one reported in the paper, Tour said. Second, its range must increase.

"Right now, the emitter has to be pretty close to the tags, but it's getting farther all the time," he said. "The practical distance to have it ring up all the items in your shopping cart is a meter. But the ultimate would be to signal and get immediate response back from every item in your store – what's on the shelves, their dates, everything.

"At 300 meters, you're set – you have real-time information on every item in a warehouse. If something falls behind a shelf, you know about it. If a product is about to expire, you know to move it to the front – or to the bargain bin."

Tour allayed concerns about the fate of nanotubes in packaging. "The amount of nanotubes in an RFID tag is probably less than a picogram. That means you can produce one trillion of them from a gram of nanotubes – a miniscule amount. Our HiPco reactor produces a gram of nanotubes an hour, and that would be enough to handle every item in every Walmart.

"In fact, more nanotubes occur naturally in the environment, so it's not even fair to say the risk is minimal. It's infinitesimal."

(Photo: Gyou-Jin Cho/Sunchon National University)

Rice University

BEES SEE SUPER COLOUR AT SUPER SPEED

0 comentarios

Bees see the world almost five times faster than humans, according to new research from scientists at Queen Mary, University of London.

This gives bumblebees the fastest colour vision of all animals, allowing them to easily navigate shady bushes to find food, write Dr Peter Skorupski and Prof Lars Chittka in the Journal of Neuroscience.

The ability to see at high speed is common in fast-flying insects; allowing them to escape predators and catch their mates mid-air. However, until now it wasn't known whether the bees' full colour vision was able to keep up with their high speed flight. This research sheds new light on the matter; suggesting that although slower, it is also about twice as fast as human vision.

Dr Skorupski, who carried out the work at Queen Mary's Research Centre for Psychology in the School of Biological and Chemical Sciences says; "We can't easily follow a fast flying insect by eye, but they can follow each other, thanks to their very fast vision. How fast you can see depends on how quickly the light-detecting cells in your eye can capture snapshots of the world and send them to your brain. Most flying insects can see much quicker than humans, for example so they can avoid getting swatted!"

Bumblebees use their advanced colour vision in many ways. Dr Skorupski explains: "Bees were the first animals that scientists proved to have colour vision, and they have since been shown to put it to good use; navigating dappled light and shady areas, recognising shapes like their hive entrance, and particularly for finding nectar-bearing coloured flowers."

The experiments show that the bees burn more energy to see in colour than they would to see in monochrome (black and white), raising questions about how they make the most of it. "Bees' energy can't be used frivolously, as they need so much of it just to stay alive. It seems they only see colours at half the speed they see white light, which give them enough detail to find their favourite flowers and navigate back home," suggests Dr Skorupski.

(Photo: Helga Heilmann, BEEgroup Wuerzburg)

Queen Mary, University of London

RARE ARMOR-PLATED CREATURE DISCOVERED IN CANADA'S CAPITAL

0 comentarios
Scientists have unearthed the remains of one of the World’s rarest fossils - in downtown Ottawa. The 450 million year old fossil preserves the complete skeleton of a plumulitid machaeridian, one of only 8 such specimens known. Plumulitids were annelid worms - the group including earthworms, bristleworms and leeches, today found everywhere from the deepest sea to the soil in your yard - and although plumulitids were small they reveal important evidence of how this major group of organisms evolved.

"Such significant new fossils are generally discovered in remote or little studied areas of the globe, requiring difficult journeys and a bit of adventure to reach them" notes Jakob Vinther of Yale University, lead author of the paper describing the specimen. "Not this one though. It was found in a place that has an address rather than map co-ordinates!"

Plumulites canadensis, Albert Street, Ottawa, Canada K1P1A4. The fossil is described by Vinther and Dave Rudkin, of Toronto's Royal Ontario Museum, in the current issue of the journal Palaeontology.

It was Rudkin who first recognised its scientific significance: "This nifty little specimen first came to my notice when I received a letter from an amateur fossil collector in Nepean, Ontario. In prospecting for fossils in rock from a temporary building excavation he had turned up a small block containing a complete trilobite, but next to it was something else and he sent me a slightly fuzzy but very intriguing photo. The mystery fossil was clearly not another trilobite, and I although couldn't be certain, I thought it might be some sort of annelid worm with broad, flattened scales. James, the collector, generously agreed to lend me the specimen and I realised immediately it was a complete, fully articulated machaeridian! The first I had ever seen."

At that time it was not known that machaeridians were annelids. "James was happy to donate the specimen to the Royal Ontario Museum, in exchange for a promise that I'd someday publish his discovery."

It was not until 2008 that Rudkin's hunch was confirmed, when a team of palaeontologists, including Jakob Vinther, decribed new machaeridian fossils from remote mountain localities in Morocco, revealing their relationship to annelid worms. Rudkin and Vinther agreed to work together to interpret the Ottawa specimen, and it is the results of that collaboration that are published in the current Palaeontology.

Plumulitid machaeridians look like modern bristleworms, with stout walking limbs bearing long bundles of bristles, but on their back they carried a set of mineralized plates. According to Vinther, "the plates themselves were rigid, but they could move relative to one other, providing plumulitids with a protective body armour very similar to the flexible metal armour invented by humans 450 million years later. Machaeridian body armour is unique among annelids, and probably helped them to succeed as ubiquitous components of marine ecosystems for more than 200 million years."

With the publication of this paper Rudkin is finally able to make good on his promise "It's great to be able to acknowledge the collector", says Rudkin, but there is a twist to this tale: the man who found the specimen has now gone missing. "Regrettably, I lost contact with James and numerous enquiries as to his whereabouts have come up empty. I hope he somehow gets wind of all this."

John Wiley & Sons, Inc.

Friday, March 26, 2010

EXPLORING STATUS QUO BIAS IN THE HUMAN BRAIN

0 comentarios
The more difficult the decision we face, the more likely we are not to act, according to new research by UCL scientists that examines the neural pathways involved in 'status quo bias' in the human brain.

The study, published in Proceedings of the National Academy of Sciences (PNAS), looked at the decision-making of participants taking part in a tennis 'line judgement' game while their brains were scanned using functional MRI (fMRI).

First author Stephen Fleming, Wellcome Trust Centre for Neuroimaging at UCL, said: "When faced with a complex decision people tend to accept the status quo, hence the old saying 'When in doubt, do nothing.'

"Whether it's moving house or changing TV channel, there is a considerable tendency to stick with the current situation and choose not to act, and we wanted to explore this bias towards inaction in our study and examine the regions of the brain involved."

The 16 study participants were asked to look at a cross between two tramlines on a screen while holding down a 'default' key. They then saw a ball land in the court and had to make a decision as to whether it was in or out. On each trial, the computer signalled which was the current default option – 'in' or 'out'. The participants continued to hold down the key to accept the default and had to release it and change to another key to reject the default.

The results showed a consistent bias towards the default, which led to errors. As the task became more difficult, the bias became even more pronounced. The fMRI scans showed that a region of the brain known as the subthalamic nucleus (STN) was more active in the cases when the default was rejected. Also, greater flow of information was seen from a separate region sensitive to difficulty (the prefrontal cortex) to the STN. This indicates that the STN plays a key role in overcoming status quo bias when the decision is difficult.

Stephen added: "Interestingly, current treatments of Parkinson's disease like deep-brain stimulation (DBS) work by disrupting the subthalamic nucleus to alleviate impaired initiation of action. This is one example of how knowing about disease mechanisms can inform our knowledge of normal decision making, and vice-versa.

"This study looked at a very simple perceptual decision and there are obviously other powerful factors, such as desires and goals that influence decisions about whether or not to act. So, it would be of interest to investigate how these regions respond when values and needs come into play."

University College London

THE FORMULA FOR MAKING TEETH WILL SOON BE FOUND

0 comentarios
Each cusp of our teeth is regulated by genes which carefully control the development. A similar genetic puzzle also regulates the differentiation of our other organs and of all living organisms. A team of researchers at the Institute of Biotechnology of the University of Helsinki has developed a computer model reproducing population-level variation in complex structures like teeth and organs. The research takes a step towards the growing of correctly shaped teeth and other organs. The results were published in Nature, the esteemed science journal.

Academy Professor Jukka Jernvall and his team investigate the evolutionary development of mammal teeth. After over 15 years of work, the team has compiled so much data that the main aspects of a formula for making teeth are beginning to be clear. The model shows that regulation of tooth development is already well known. Teeth are a kind of "model species" for Jernvall's team, which means that the study results also tell about the development of other organs.

According to a mathematical computer model, a rather simple basic formula seems to be behind the complex gene puzzle resulting in tooth formations; the jungle of gene networks has a 'patterning kernel' regulating the variation of teeth among individuals in the same population. Also the variation of human teeth from the incisors to the molar teeth may result from a single factor regulating cell division.

The researchers tested their theoretical model, which is based on mouse tooth development, by investigating seal teeth. The Ladoga ringed seal collection of the Finnish Museum of Natural History at the University of Helsinki provided an ideal population sample for the research because dentitions are highly variable.

The mathematical model proposed by the research team may give new kind of understanding on the formation of organisms' three-dimensional shapes: How do different levels of ontogeny function together? What factors guide the emergence of specific external features? The new research results may promote medical research, such as growing new organs.

Jernvall is known as an international pioneer in cross-disciplinary evolutionary development biology. A few years ago, the science journal Nature chose a teeth evolution work conducted by Jernvall and two post-doc researchers as one of the 15 educational topics in the field of evolutionary biology. The research published now was conducted with Jernvall's third post-doc researcher, Isaac Salazar-Ciudad. Salazar-Ciudad currently works at the Autonomous University of Barcelona in Spain.

University of Helsinki

TIMING IS (ALMOST) EVERYTHING

0 comentarios
What determines whether a scene is remembered or forgotten? According to a study published in the open access journal PLoS Biology, memory for visual scenes may not depend on attention level or what a scene contains, but when the scene is presented. The study, presented by researchers at the University of Washington, shows how visual scenes are encoded into memory at behaviorally relevant points in time.

The ability to remember a briefly presented scene depends on a number of factors, such as its saliency, novelty, degree of threat, or behavioral relevance to a task. Generally, attention is thought to be key, in that people can only remember part of a visual scene when paying attention to it at any given moment.

In this study, participants performed an attention-demanding "target detection task at fixation," while also viewing a rapid sequence of full-field photographs of urban and natural scenes. Participants were then tested on whether they recognized a specific scene from the sequence they had been shown or not. "Usually, the addition of a secondary task decreases performance on the first task. However, in this particular case, adding a second task (letter identification) actually enhanced performance in the first task (scene memory) when targets were accurately detected in the second letter identification task," says Jeffrey Lin, the lead author of the study.

This study adds to our understanding of how selective attention can influence the ability to remember specific features of our environment. The results point to a brain mechanism that automatically encodes certain visual features into memory at behaviorally relevant points in time, regardless of the spatial focus of attention. Timing may not be everything, but it's more important than you realize.

PLoS Biology

SCIENTISTS AT UCSB DISCOVER 600-MILLION-YEAR-OLD ORIGINS OF VISION

0 comentarios

By studying the hydra, a member of an ancient group of sea creatures that is still flourishing, scientists at UC Santa Barbara have made a discovery in understanding the origins of human vision.

The finding is published in Proceedings of the Royal Society B, a British journal of biology.

Hydra are simple animals that, along with jellyfish, belong to the phylum cnidaria. Cnidarians first emerged 600 million years ago.

"We determined which genetic 'gateway,' or ion channel, in the hydra is involved in light sensitivity," said senior author Todd H. Oakley, assistant professor in UCSB's Department of Ecology, Evolution and Marine Biology. "This is the same gateway that is used in human vision."

Oakley explained that there are many genes involved in vision, and that there is an ion channel gene responsible for starting the neural impulse of vision. This gene controls the entrance and exit of ions; i.e., it acts as a gateway.

The gene, called opsin, is present in vision among vertebrate animals, and is responsible for a different way of seeing than that of animals like flies. The vision of insects emerged later than the visual machinery found in hydra and vertebrate animals.

"This work picks up on earlier studies of the hydra in my lab, and continues to challenge the misunderstanding that evolution represents a ladder-like march of progress, with humans at the pinnacle," said Oakley. "Instead, it illustrates how all organisms –– humans included –– are a complex mix of ancient and new characteristics."

(Photo: Todd Oakley, UCSB)

UC Santa Barbara

CAN WE DETECT QUANTUM BEHAVIOR IN VIRUSES?

0 comentarios
The weird world of quantum mechanics describes the strange, often contradictory, behaviour of small inanimate objects such as atoms. Researchers have now started looking for ways to detect quantum properties in more complex and larger entities, possibly even living organisms.

German-Spanish research group, split between the Max Planck Institute for Quantum Optics in Garching and the Institute of Photonic Sciences (ICFO), is using the principles of an iconic quantum mechanics thought experiment - Schrödinger's superpositioned cat – to test for quantum properties in objects composed of as many as one billion atoms, possibly including the flu virus.

New research published Thursday 11 March, in New Journal of Physics (co-owned by the Institute of Physics and German Physical Society), describes the construction of an experiment to test for superposition states in these larger objects.

Quantum optics is a field well-rehearsed in the process of detecting quantum properties in single atoms and some small molecules but the scale that these researchers wish to work at is unprecedented.

When physicists try to fathom exactly how the tiniest constituents of matter and energy behave, confusing patterns of their ability to do two things at once (referred to as being in a superposition state), and of their 'spooky' connection (referred to as entanglement) to their physically distant sub-atomic brethren, emerge.

It is the ability of these tiny objects to do two things at once that Oriol Romero-Isart and his co-workers are preparing to probe.

With this new technique, the researchers suggest that viruses are one type of object that could be probed. Albeit speculatively, the researchers hope that their technique might offer a route to experimentally address questions such as the role of life and consciousness in quantum mechanics.

In order to test for superposition states, the experiment involves finely tuning lasers to capture larger objects such as viruses in an 'optical cavity' (a very tiny space), another laser to slow the object down (and put it into what quantum mechanics call a 'ground state') and then adding a photon (the basic element of light) in a specific quantum state to the laser to provoke it into a superposition.

The researchers say, "We hope that this system, apart from providing new quantum technology, will allow us to test quantum mechanics at larger scales, by preparing macroscopic superpositions of objects at the nano and micro scale. This could then enable us to use more complex microorganisms, and thus test the quantum superposition principle with living organisms by performing quantum optics experiments with them."

IOP Science

EARLY TERRESTRIAL AMPHIBIAN DESCRIBED BY CARNEGIE MUSEUM OF NATURAL HISTORY SCIENTISTS

0 comentarios
A team of researchers from Carnegie Museum of Natural History has described a new genus and species of carnivorous amphibian from western Pennsylvania. The fossil skull, found in 2004 near Pittsburgh International Airport, was recovered from rocks deposited approximately 300 million years ago during the Late Pennsylvanian Period.

Named Fedexia striegeli, it is one of only a very few relatively large amphibian fossils to display evidence of a predominantly terrestrial (land-based) life history so early in geologic time. The rocks where Fedexia was found are nearly 20 million years older than the localities of its fossil relatives, suggesting that the expansion and diversification of this group occurred much earlier than had been recognized previously.

Fedexia was described on the basis of a remarkably well-preserved fossil skull. Unlike similar discoveries, the five-inch-long (11.5 cm) fossil skull remained three-dimensional over time because it was never crushed by rocks that were deposited above it. Fedexia striegeli was named for FedEx, the corporation that owns the land on which the fossil was found, and for amateur discoverer Mr. Adam Striegel, who originally found the specimen on a geology field trip while a senior at the University of Pittsburgh.

Fedexia represents an extinct group of amphibians called Trematopidae that lived about 70 million years before the first dinosaurs appeared. Unlike almost all other Pennsylvanian Period amphibians, which did not often venture out of the water, this rare, diverse group lived mostly on land, returning to the water perhaps only to mate or lay eggs. The trematopids also provide evidence of the earliest vertebrate life in North America adapted to a mostly terrestrial existence. Their success may have been a result of a long-term, global trend toward drier, warmer conditions that reached its climax near the end of the Pennsylvanian Period.

At the time of Fedexia’s preservation, the earth’s climate was in a period of transition. Immense glaciers in Earth’s southern polar region produced rapidly fluctuating global climates. Western Pennsylvania, which was near the equator at that time, experienced tremendous amounts of rain. Swamps which would later develop into coal developed, and amphibians—which are dependent on moist conditions—flourished; in fact, the Pennsylvanian Period is known as the “Age of Amphibians.”

Gradually, however, as an increasing amount of the planet’s water became locked up in polar ice, the sea level dropped and more land was exposed. Vast regions of the earth became drier and warmer, including the region that would become western Pennsylvania. The coal swamps and lakes dried up, and many of the coal-forming plants became extinct. It was at this time that amphibian populations in what would become the Pittsburgh region shifted from mainly aquatic to mainly terrestrial, paralleling the change in climate from tropical to semi-arid. Vertebrates that had already begun adapting to terrestrial life—including amphibians closely related to Fedexia striegeli—became far more abundant, widespread, and diverse than their relatives who were still dependent upon cooler, moist environments.

The large number of trematopid amphibians appearing in the fossil record in the Permian Period suggests that climate change was a major factor in the diversification of terrestrial amphibians. The appearance of Fedexia during the Pennsylvanian Period—20 million years earlier than the Permian—was an early indicator of the diversification that was to come. Co-author David Brezinski states, “The one-to-one correspondence between this early appearance of trematopids in the fossil record and the preservation of dry climate indicators in the surrounding rock units suggests that this is a climatically driven immigration and/or origination event.”

Although the appearance of Fedexia and other highly terrestrial vertebrates in the fossil record seems sudden, this is undoubtedly misleading. They or their close relatives had probably already existed for a few million years, occupying upland regions where conditions for fossil preservation were not optimal. However, the climatic change to drier, warmer conditions led to an explosive dispersal of terrestrial vertebrates to coastal regions and lowlands—including western Pennsylvania—where accumulating sediments increased the chances for fossil preservation. Because western Pennsylvania is the “type stratigraphic sequence”—or best record—of sediments deposited during the Pennsylvanian geologic period, this region offers exceptional opportunities for future discoveries of terrestrial vertebrate fossils of this age.

Fedexia striegeli was described on the basis of a remarkably well-preserved fossil skull. Unlike many other fossil finds, the fossil skull remained three-dimensional and did not suffer post-mortem crushing over time by the compaction of rock formations above it. The preservation of the skull is so precise that even the middle-ear bone, known as the stapes, remains perfectly intact and in its correct position, a very rare discovery in fossils. Owing to the remarkable preservation of the skull, Fedexia was easily identified as a trematopid, mainly by the hallmark feature of the group, a greatly elongated external nasal opening that is partially subdivided into fore and aft portions. Some scientists speculate that the posterior division held a gland—similar to that in some modern-day reptiles and marine birds—that rid the body of excess salt, or perhaps enhanced the sense of smell; either function would have been an advantage for a terrestrial existence. Fedexia is the first trematopid to be found in Pennsylvania, and only the third in the world of Late Pennsylvanian age, the group’s earliest appearance.

Now that the immediate study of Fedexia striegeli is complete, the fossil has been permanently preserved for future research in the Carnegie Museum of Natural History vertebrate paleontology collection. Casts of the skull will be given to FedEx Corporation and to Mr. Striegel.

According to co-author David S Berman, “What is particularly amazing about this discovery is that it was made by an amateur who had no prior experience in recognizing vertebrate fossils in the rock, a talent that usually takes years to develop.”

Carnegie Museum of Natural History

Thursday, March 25, 2010

BREAKTHROUGH MAY LEAD TO ABUNDANT ADULT STEM CELLS FOR BONE MARROW TRANSPLANTS

0 comentarios

In a leap toward making stem cell therapy widely available, researchers at the Ansary Stem Cell Institute at Weill Cornell Medical College (WCMC) have discovered that endothelial cells, the most basic building blocks of the vascular system, produce growth factors that can grow copious amounts of adult stem cells and their progeny over the course of weeks.

The finding will likely revolutionize the use of adult stem cells for bone marrow transplants, organ regeneration, and therapies for hearts, brains, skin and lungs, say the researchers.

Until now, adult stem cell cultures would die within four or five days despite best efforts to grow them.

"This is groundbreaking research with potential application for regeneration of organs and inhibition of cancer cell growth," said Dr. Antonio M. Gotto Jr., the Stephen and Suzanne Weiss Dean of WCMC and provost for medical affairs of Cornell.

This new finding sets forth the innovative concept that blood vessels are not just passive conduits to deliver oxygen and nutrients, but are also programmed to maintain and proliferate stem cells and their mature forms in adult organs. Using a novel approach to harness the potential of endothelial cells by "co-culturing" them with stem cells, the researchers discovered how to manufacture an unlimited supply of blood-related stem cells that may eventually ensure that anyone who needs a bone marrow transplant can get one.

The vascular-cell model established in this study could also be used to grow abundant functional stem cells from other organs, such as the brain, heart, skin and lungs.

The findings are published in the March 5 issue of the journal Cell Stem Cell.

In adults, organs have few naturally occurring stem cells, so using them for organ regeneration is impractical. Until now, strategies to expand cultures of adult stem cells, which invariably used animal-based growth factors, serum and genetically manipulated feeder cells, have only been marginally successful. This study, however, uses endothelial cells to propagate stem cells without added growth factors and serum.

"This study will have a major impact on the treatment of any blood-related disorder that requires a stem cell transplant," says senior author, Dr. Shahin Rafii, the Arthur B. Belfer Professor in Genetic Medicine and co-director of the Ansary Stem Cell Institute at WCMC.

Currently, stem cells derived from bone marrow or umbilical cord blood are used to treat patients who require bone marrow transplants. Most stem cell transplants are successful, but because of the shortage of genetically matched bone marrow and umbilical cord blood cells, many patients cannot benefit from the procedure.

If this vascular-based stem cell expansion strategy continues to be validated, physicians could use any source of hematopoietic (blood-producing) stem cells, propagate them exponentially, and bank the cells for transplantation into patients, he said.

In a related study, researchers also discovered that endothelial cells not only could expand stem cells, but also instruct stem cells to generate mature differentiated progeny that could form immune cells, platelets, and red and white blood cells, all of which constitute functioning blood.

The "findings suggest that endothelial cells directly, through expression of stem-cell-active cytokines, promote stem cell reconstitution," said first author Dr. Jason Butler, a senior investigator at WCMC.

(Photo: Cornell U.)

Cornell University

BIRD WINGS MORPH QUICKLY TO ADAPT TO HUMAN-CREATED ENVIRONMENTAL CHANGES

0 comentarios

Can species quickly evolve when humans rapidly change their habitats? The answer, in some cases, is yes.

A new study of North American songbirds finds that major changes in wing shape have occurred over the last 100 years in response to human-driven forest changes.

The study, based on measurements of 851 specimens from 21 songbird species at the Cornell Museum of Vertebrates and the Canadian Museum of Nature in Ottawa, Canada, was published online Feb. 1 in the journal Ecology.

Since 1900, the extent of mature coniferous forests in Québec has shrunk as a result of extensive clear-cutting. That has put some birds under greater pressure to travel further to find mates, food and habitat. To fly the greater distances, such northern songbirds as boreal chickadees, gray jays and Cape May warblers have developed pointier wings.

"It is better for birds to have pointy wings because it is more efficient for sustained flight," said the paper's author, André Desrochers, an animal ecologist at Université Laval in Québec City, Canada, who conducted the research while a visiting researcher at the Cornell Lab of Ornithology in 2009.

On the other hand, since 1900 the forests of New England expanded after they had been heavily deforested in the late 1800s. That has prompted such songbirds as white-breasted nuthatches, hooded warblers and scarlet tanagers over the past 100 years to develop shorter, less pointy wings, presumably because the birds no longer needed to travel as far in search of suitable habitat.

"If a bird is going to forage more in dense vegetation, they don't want cumbersome pointy wings," Desrochers added.

Desrochers referred to a number of famous examples of how selective pressure has led to physical adaptations over short time scales: Beak length of Galapagos finches became shorter over a matter of a few years when an El Niño event changed precipitation patterns, which in turn, resulted in changes in food supply that favored finches with shorter beaks. And in England during the Industrial Revolution, soot made tree trunks dark -- which favored darker tree moths that could blend in and put white tree moths at a disadvantage. But recently, as pollution has abated and tree trunks have lightened, paler moths have reappeared.

"We should not underestimate the ability of species to adapt" to changes to the environment by humans, said Desrochers, adding that conservation measures are still necessary. "Polar bears, for example, are not going to find some sort of breakthrough" as the Arctic ice floes that the bears rely on for traveling and hunting are melting, thereby threatening their survival, he added.

(Photo: A. Desrochers)

Cornell University

Followers

Archive

 

Selected Science News. Copyright 2008 All Rights Reserved Revolution Two Church theme by Brian Gardner Converted into Blogger Template by Bloganol dot com