Tuesday, December 15, 2009

NEWLY DISCOVERED STAR ONE OF HOTTEST IN GALAXY

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Astronomers at The University of Manchester's Jodrell Bank Centre for Astrophysics have discovered one of the hottest stars in the Galaxy with a surface temperature of around 200,000 degrees - 35 times hotter than the Sun.

Despite numerous attempts by astronomers across the world, the mysterious dying star at the heart of the Bug nebula - one of the brightest and most beautiful of the planetary nebulae - has never been seen before.

"This star was so hard to find because it is hidden behind a cloud of dust and ice in the middle of the nebula", explained Professor Albert Zijlstra from The University of Manchester.

"Planetary nebulae like the Bug form when a dying star ejects much of its gas back into space and are among the most beautiful objects in the night sky."

"Our own Sun will do this in about 5 billion years time. The Bug nebula, which is about 3500 light years away in the constellation Scorpius, is one of the most spectacular of all planetary nebulae."

Using the recently refurbished Hubble Space Telescope (HST), a team of astronomers led by Professor Zijlstra have shed new light on the nebula with a set of spectacular images.

The images were taken to show off the new improved HST after it began work again in September this year and will be published in the Astrophysical Journal next week.

The Manchester astronomers were amazed to find that the images unexpectedly revealed the missing central star.

Cezary Szyszka, lead author on the paper and a research student at the University of Manchester currently working at the European Southern Observatory, said: "We are extremely lucky that we had the opportunity to catch this star near its hottest point, from now on it will gradually cool as it dies. This is truly an exceptional object."

Professor Zijlstra added: "It's extremely important to understand planetary nebulae such as the Bug Nebula, as they are crucial to understanding our own existence on Earth".

That is because the elements necessary for life, especially carbon, are created inside stars, and ejected into space as part of these planetary nebulae.

Planets such as the Earth form from small dust particles, which also form within planetary nebulae. The cloud of dust and ice in the Bug Nebula contains the seeds of a future generation of planets."

Finding the star was made possible by the Space Shuttle's final servicing mission of the HST, earlier this year. During the mission, astronauts installed the new Wide Field Camera 3 which was used to take these images.

"How a star ejects a nebula like this is still a mystery", added Dr Tim O'Brien from The University of Manchester.

"It seems most stars, including the Sun, will eject as much as 80 per cent of their mass when they finally run out of nuclear fuel at the end of their lives. Material that then goes on to help form the next generation of stars and planets.

"These observations have shown that the star at the heart of the Bug Nebula is only about 2/3 as heavy as the Sun, but was several times heavier before it threw off its outer layers to form the nebula which had previously hidden it from our
view.

"Images like these are remarkable not only for their beauty but also for what they tell us about our own origins."

(Photo: Anthony Holloway & Tim O'Brien, JBCA)

The University of Manchester

ISU PSYCHOLOGIST STUDIES HOW PRODUCT MESSAGES INFLUENCE OUR WILLINGNESS TO PAY

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As retailers bombard holiday shoppers with a blizzard of product bargains and layaway options, they should probably be concerned with the power of the words being used to promote their products to consumers. So says an Iowa State University psychologist who has studied how a product's message influences what consumers are ultimately willing to pay for it.

Kevin Blankenship, an assistant professor of psychology at Iowa State, led two recent studies of 280 student subjects -- 100 from Purdue University and 180 at Fresno State University. He found that those who were given a message that assigned greater value to an alarm clock were willing to pay an average of $15 more for that clock than the subjects who were given an opposite message.

Blankenship previously presented the study's results at a Division 8 Society for Personality and Social Psychology conference. He's also co-authored a paper on the results with Duane Wegener, professor of psychological sciences at Purdue, that is currently under review for publication in a social psychology professional journal.

"With this study, and some of the other work I've done, we are trying to figure how we can get people to think about their attitude toward the object," Blankenship said. "If we can get them to think about it, then presumably they'll create a strong attitude about it. And in the consumer domain, a strong attitude means that consumers will be more likely to purchase that kind of product."

Blankenship says researchers tried to get subjects in the study to think about the alarm clock as it relates to important values to them.

"If something is important to a person, they've probably thought about it a great deal, and that's going to guide how they interact with that particular object later on," Blankenship said. "If we can get people to relate important things to initially unimportant things, like an alarm clock, they will hopefully think a lot about that product, which then will guide whether they purchase the product."

Researchers initially pre-tested subjects in the study to determine the values that were important to them. Important values included freedom, loyalty and self-respect. Less important values included unity, social power and wealth.

Half of the participants were then given a message that reflected upon the clock's important values, while the other half were given the information associated with the less important values. Researchers assessed the subjects' overall attitudes toward the clock in light of the message, and then asked them how much they would be willing to pay for it.

"So not only did we measure evaluations, but we also measured behavioral intentions," he said. "And what we found was that when they were asked to consider the clock in light of the important values, they did indeed seem to think more about the product information. This was also reflected in how much they were willing to pay for the clock as well -- and the average was about $15 more. So it was a good amount considering we tracked amounts between zero and $100."

Blankenship also has a second study on "word power" -- determining how language can influence a person's processing of information and behavior -- under review with another professional journal.

(Photo: ISU)

Iowa State University

VALLEY IN JORDAN INHABITED AND IRRIGATED FOR 13,000 YEARS

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You can make major discoveries by walking across a field and picking up every loose item you find. Dutch researcher Eva Kaptijn succeeded in discovering – based on 100,000 finds – that the Zerqa Valley in Jordan had been successively inhabited and irrigated for more than 13,000 years. But it was not just communities that built irrigation systems: the irrigation systems also built communities.

Archaeologist Eva Kaptijn has given up digging in favour of gathering. With her colleagues, she has been applying an intensive field exploration technique: 15 metres apart, the researchers would walk forward for 50 metres. On the outward leg, they’d pick up all the earthenware and, on the way back, all of the other material. This resulted in more than 100,000 finds, varying from about 13,000 years to just a few decades old. Based on further research on the finds and where they were located, Kaptijn succeeded in working out the extent of habitation in the Zerqa Valley in Jordan over the past millennia.

The area where she undertook her research is also called the Zerqa Triangle; it is bounded by the River Zerqa and forms part of the Jordan Valley. The area covers roughly 72 square kilometres. Kaptijn discovered that the triangle had been inhabited, on and off, for thousands of years, but that this habitation was always highly dependent on the irrigation methods used by those who lived there. While the soil in the valley is very rich, there was usually not enough rainfall to cultivate plants without some additional irrigation.

The irrigation methods exerted a major influence on the people who lived in the valley; power was often dependent on controlling the allocation of water. Kaptijn discovered that the type of irrigation system could result in a community of internally egalitarian tribes, with these tribes being linked to each other in a strict, hierarchical order. At other times, the valley was actually dominated by a large-scale, almost capitalist cultivation of sugar cane.

Eva Kaptijn’s research is part of the multi-disciplinary project Settling the Steppe. The Archaeology of changing societies in Syro-Palestinian drylands during the Bronze and Iron Ages. This project is funded by the NWO’s Open Competition scheme.

The Netherlands Organization for Scientific Research

MORE COMPETITORS, LESS COMPETITION

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A new study carried out by the University of Haifa and the University of Michigan found that motivation and performance is weakened when competing against a large group of people.

The larger the number of examinees, the lower the average grade. This is one of the findings of a series of new studies carried out by scientists at the University of Haifa and the University of Michigan. "It is a well-established fact that subjective factors influence our motivation to compete. Our recent studies have shown that objective factors, such as the size of a competing group, also have an effect on motivation," explains Dr. Avishalom Tor from the University of Haifa's Faculty of Law.

The series of studies, which Dr. Tor carried out along with Dr. Stephen Garcia of the University of Michigan, were designed to examine whether a large number of participants in a competition would affect motivation and the performance of the individual competitor even in cases where the number of competitors does not influence the anticipated value of winning.

The first study investigated the grades of the SAT university entrance examination across the USA. The scientists divided the number of examinees in each state by the number of sites where the test was held in that state, to determine the average number of examinees per site in each state. The researchers took into consideration differences between the states in relevant socioeconomic variables, finding that the lower the average number of students being examined at the sites of a given state, the higher the average score in that state.

Seeing as it is difficult to make assumptions based on averages calculated at a state level, a second and more focused study was carried out. This time, the results were gathered from a psychological test, known as the Cognitive Reflection Test, that was taken by 1,383 students at the University of Michigan. The data was assembled from 22 different sittings of the same test over the course of three years, when it was known not only how many examinees were taking the test at each session but also their individual grades and demographic variables. This individual-level data similarly showed that the fewer the examinees at a specific session, the higher the average results.

A third study that the researchers carried out consisted of a controlled survey. The experiment asked 74 students to take a short, timed quiz when sitting alone. Half the students were told they belonged to a group of 10 students taking the quiz, while the other half were told there were 100 examinees in total. They were also told that the first 20% to complete the test – without compromising the accuracy of their answers – would be given 5 dollars. The results showed that students who thought they were competing against 9 others completed their tests significantly faster than those who thought they were competing against 99 others, although the accuracy of the responses did not differ between the groups.

Additional experiments directly examined how competitors judge their chances to win, considered interpersonal differences, and showed that the variation in competitive motivation and performance directly results from the drop in the importance ascribed to social comparison (the process by which people evaluate themselves in comparison to others) as the number of competitors rises.

"The results of this study have relevance in almost all areas of life. They shed light on the issue of classroom size, as smaller classes would improve student motivation to 'compete' and to strive for better achievements. The findings also affect the workplace: salespersons working in large warehouses, for example, would be lower achievers than those working in small groups," Dr. Tor concludes.

University of Haifa

TURBULENCE AROUND HEAT TRANSPORT

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Not only in the Earth's mantle, in the atmosphere and in the outer layers of the Sun, but also in a chemical reactor, the exchange of heat may not be as effective as originally thought.

There, because warm fluid rises and hence induces movement, the turbulent convection can be 100 billion times stronger than in the typical cooking pot. Hot fluids mix turbulently with warm fluids. As the temperature difference between the cold and warm sides increases, the heat transport increases exponentially. When the turbulence is very strong, the exponential growth decreases twofold. Physicists from the Max Planck Institute for Dynamics and Self-Organization, University of California at Santa Barbara, and the French Centre National de la Recherche Scientifique in Nancy report this discovery in the current issue of New Journal of Physics. The long standing theory for turbulent convective heat transport from 1962 had predicted that the exponential growth would increase. Now, the theory will need to be reconsidered.

In some respects the experimental apparatus of Eberhard Bodenschatz and colleagues is similar to a gigantic pressure cooker - even if the Director at the Max Planck Institute for Dynamics and Self-Organization calls it (due to its shape) the "Göttingen submarine". In the hermetically sealed submarine, a two-metre high container of one-metre in diameter is heated from below and cooled from above. In-between, a pressurized gas is mixed by turbulent convection, where hot water rises from the hot plate and sinks from the cool one. The main difference is that the convection in the "Göttingen submarine" is a million times stronger than in a cooking pot. With this, the scientists want to learn about turbulence in the Earth mantle, in the atmosphere and in the outer layers of the Sun, where the convection is yet another 100,000 times stronger.

"We have measured the heat transport of very strong convection and found that it is completely different from what we expect on the basis of previously established theory", says Eberhard Bodenschatz. The stronger the turbulence mixes the hot and cold gas, the stronger the heat transport from the hot bottom to the cold top will be - in essence the heat transport increases exponentially. The team measured this increase and found, surprisingly, that the exponent in the law decreases by the power of two. For a given temperature difference, not only one but two states were observed; once where the exponent falls from 0.308 to 0.253, and, sometimes, for a second time to 0.17. In 1962, the American physicist Robert Kraichnan predicted that the exponent should increase from 0.3 to 0.4 and then should be almost constant in this ultimate regime of thermal turbulence. "In the meantime we have conducted more measurements at the highest turbulence levels and found yet another state with possibly another exponent" says Eberhard Bodenschatz: "This time it may be the predicted Kraichnan regime. The multiplicity of states and the exponents baffles us, as the physical processes are yet to be understood".

To understand this better let's take a closer look at the "cooking pot" in the submarine. At the bottom and top plates, the heat is conducted through a few hundred micron thick thermal boundary layer into the gas. Here, a thermal plume develops which carries hot or cold gas into the interior of the vessel. It is well known that plumes of this type form a lava lamp - for yet unknown reasons however, rising and falling plumes merge to create one large circulation that flows up one side and falls on the other. According to Kraichnan's theory, this circulation should lead the boundary layer to become turbulent. From this point on, the heat conduction should increase more rapidly. "Instead the efficiency decreases and we find two states instead of one" says Eberhard Bodenschatz: "Somehow the boundary layers are changing, but we do not know how".

To investigate the heat transport in a planet like Earth or a star like the Sun is ultimately difficult. Even if scientists only want to investigate the turbulence itself, the conditions are difficult to achieve in the laboratory. Therefore the known experimental data are very limited. "Recently, with the submarine we were able to reach very high turbulence levels by using a two metre high container and sulfur hexafluoride (SF6) at 20 times atmospheric pressure" says Eberhard Bodenschatz.

The experimental data from Guenter Ahlers, Denis Funfschilling, and Eberhard Bodenschatz poses a riddle that will challenge theorists and experimentalist alike. The international team is already on its way to designing an experiment that can resolve the fine scales of the boundary layer. Results will give deeper insights into convective processes in the Earth, the atmosphere and the Sun, as well as the potential to optimize heat transfer in industrial reactors.

(Photo: Max Planck Institute for Dynamics and Self-Organization)

Max-Planck-Gesellschaft, München

INCREASED NICOTINE LEVELS DETECTED IN THOSE WHO LIGHT-UP EARLIER

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People who smoke their first cigarette within minutes after waking up have much higher levels of cotinine, a by-product of nicotine when processed by the body, than those who wait to smoke, regardless of the number of cigarettes smoked.

"Since cotinine levels appear to reflect the risk of lung cancer, our results suggest that smokers who smoke immediately after waking may be especially at risk for lung cancer," said researcher Joshua E. Muscat, Ph.D., M.P.H., professor of public health sciences at Penn State College of Medicine. "These people may require a more intensive intervention than other smokers to help them quit smoking on a sustained or permanent basis."

Results of this study are published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, as part of a special tobacco focus in the December issue.

Nicotine levels in the blood can be measured biochemically by the concentration of the metabolite cotinine. Muscat, along with John P. Richie, Jr., Ph.D., professor of public health sciences and pharmacology at Penn State College of Medicine, and colleagues conducted a community-based study in Westchester County, N.Y., to examine whether a behavioral aspect of nicotine dependence (the amount of time to the first cigarette after waking up) affects the physiological uptake of nicotine. This in turn may affect one's success in quitting smoking and have multiple health effects, such as lung cancer.

The study included 252 healthy black and white people who were daily cigarette smokers. Researchers examined a number of behavioral factors that are thought to measure the urge to smoke, and results showed a clear trend between lighting-up earlier and higher cotinine levels.

Cotinine levels varied from 16 ng/mL to 1180 ng/mL — a 74-fold difference, according to the study. Participants who waited 30 minutes or more were categorized into the "low" dependant phenotype; those who smoked within the first 30 minutes of waking were considered "high." Number of cigarettes smoked per day and its association with cotinine levels varied as well.

"Not all smokers are the same and approaches to smoking reduction may need to account for individual smoking behaviors such as the intensity and frequency of puffing, cravings and physiological symptoms," said Muscat. "It is unclear why smokers who take their first puff immediately after waking have higher cotinine levels, but this may reflect a more intense pattern of smoking. We need to find out why this is."

The researchers are currently conducting follow-up studies to investigate levels of additional nicotine metabolites that will further confirm this association and help determine the impact of time to first cigarette as a novel risk factor for lung cancer.

(Photo: Joshua E. Muscat)

American Association for Cancer Research

SPECIES DOWN, DISEASE UP

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The extinction of plant and animal species can be likened to emptying a museum of its collection, or dumping a cabinet full of potential medicines into the trash, or replacing every local cuisine with McDonald's burgers.

But the decline of species and their habitats may not just make the world boring. New research now suggests it may also put you at greater risk for catching some nasty disease.

"Habitat destruction and biodiversity loss," — driven by the replacement of local species by exotic ones, deforestation, global transportation, encroaching cities, and a litany of other environmental woes — "can increase the incidence and distribution of infectious diseases in humans," write University of Vermont biologist Joe Roman, EPA scientist Montira Pongsiri, and seven co-authors in BioScience.

Their study, "Biodiversity Loss Affects Global Disease Ecology," will appear in the December issue of the journal, available online on Dec. 7.

"Lots of new diseases are coming up and diseases that used to be local are now global," says Roman, a wildlife expert and fellow at UVM's Gund Institute for Ecological Economics, "diseases like West Nile Virus now spread around the world very quickly."

This is not the first time humans have faced a raft of new diseases. About 10,000 years ago, humans invented farming. This move from hunting to agriculture brought permanent settlements, domestication of animals, and changes in diet. It also brought new infectious diseases, in what scientists call an "epidemiologic transition."

Another of these transitions came with the Industrial Revolution. Infectious diseases decreased in many places while cancer, allergies and birth defects shot up.

Now, it seems, another epidemiologic transition is upon us. A host of new infectious diseases — like West Nile Virus — have appeared. And infectious diseases thought to be in decline — like malaria — have reasserted themselves and spread.

"Ours is the first article to link the current epidemiological transition," says Pongsiri, an environmental health expert in EPA's Office of the Science Advisor, "with biodiversity change, decline and extinction."

"People have been working on this in individual diseases but no one has put all the studies together to compare them," says Roman. In 2006, he and Pongsiri gathered a group of scientists and policy analysts with expertise in a range of the new diseases being observed — including West Nile virus as well as malaria, the African parasitic disease schistosomiasis, hantavirus pulmonary syndrome, and several others. From that meeting, the forthcoming BioScience study developed.

"We've reviewed all those studies and show that emergence or reemergence of many diseases is related to loss of biodiversity," say Pongsiri.

"We've taken a broad look at this problem to say that it's not just case-study specific," she says, "we're saying something is happening at a global scale."

One of the studies that Pongsiri and Roman's team examined was a 2006 investigation in Amazonian Peru. It was the first to demonstrate that malaria transmission can rise in response to deforestation. Though the mechanisms are complex and not fully worked out, it appears that loss of the structural diversity provided by trees led to higher density of Anopheles darlingi mosquitoes, a potent transmitter of malaria, as well as to higher biting rates.

"Or think about Lyme disease," says Roman, calling from Connecticut.

People get this disease from ticks infected with a bacterium, Borrelia burgdorferi. The ticks, in turn, usually get the bacterium by feeding on small mammals — particularly white-footed mice.

"Historically, Lyme disease was probably rare, because you had a large range of mammals, everything from pumas all the way down to a widespread community of rodents," says Roman. Ticks would happily feed on dozens of these animals, and, since many of them were unlikely or unable to transmit the bacterium to the tick, only a limited number of ticks would carry the disease to people. But fragmentation and reduction of forests has led to deep declines in the number of mammals — and white-footed mice tend to thrive in species-poor places, like small patches of forest on the edge of neighborhoods.

"In fact, white-footed mice appear to be the most competent animal host reservoir of Lyme disease in the northeastern U.S.," Pongsiri notes on an EPA blog, "So, the more white-footed mice that are in the forest, the greater chance more ticks will be infected, and the greater chance you have of getting bitten by an infected tick."

In other words, if you're worried about catching Lyme disease, it's a good idea to wear long pants — but it might be a better idea to join your conservation commission or zoning board since "protecting large forested areas in the vicinity of residential areas may reduce the risk of Lyme disease," the BioScience paper notes.

It is new to think about biodiversity — and therefore, species and land conservation — as integral to public health. Until recently, almost no epidemiologists, nor medical schools, were framing questions of human infectious disease prevention in terms of, say, habitat structure, promoting genetic diversity in non-human species, or protecting animal predators as ecosystem regulators. Human diseases, goes the conventional thinking, are best understood and treated by looking at humans.

"Now there is the beginning of a movement to bring epidemiology and ecology together," say Pongsiri.

"We're not saying that biodiversity loss is the primary driver of all of these diseases emerging," says Roman, "it could be the major factor, or it could be one of many factors."

"We're trying to make the case that all these environmental changes we're making, because they are anthropogenic, can be managed, can be controlled," say Pongsiri. "We may be able to actually reduce or prevent these diseases by managing for biodiversity from the gene level to habitat level."

A third of the bird species on the planet are at risk of extinction and a quarter of the mammals, Roman says, "and we have an incredible amount of habitat at risk and climate change. We should expect to see the impacts of these changes occurring now, to people — and we do."

"The standard argument for protecting biodiversity is often that, well, there are medicines out there and you don't want to destroy a forest where you might have a cure for cancer," he says, "and that's true — but I don't think that's as compelling as the fear that if you cut down the forest you or your kids are more prone to infectious diseases."

(Photo: Centers for Disease Control and Prevention)

The University of Vermont

BIG FREEZE PLUNGED EUROPE INTO ICE AGE IN MONTHS

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In the film, ‘The Day After Tomorrow’ the world enters the icy grip of a new glacial period within the space of just a few weeks. Now new research shows that this scenario may not be so far from the truth after all.

William Patterson, from the University of Saskatchewan in Canada, and his colleagues have shown that switching off the North Atlantic circulation can force the Northern hemisphere into a mini ‘ice age’ in a matter of months. Previous work has indicated that this process would take tens of years.

Around 12,800 years ago the northern hemisphere was hit by a mini ice-age, known by scientists as the Younger Dryas, and nicknamed the ‘Big Freeze’, which lasted around 1300 years. Geological evidence shows that the Big Freeze was brought about by a sudden influx of freshwater, when the glacial Lake Agassiz in North America burst its banks and poured into the North Atlantic and Arctic Oceans. This vast pulse, a greater volume than all of North America’s Great Lakes combined, diluted the North Atlantic conveyor belt and brought it to a halt.

Without the warming influence of this ocean circulation temperatures across the Northern hemisphere plummeted, ice sheets grew and human civilisation fell apart.

Previous evidence from Greenland ice cores has indicated that this sudden change in climate occurred over the space of a decade or so. Now new data shows that the change was amazingly abrupt, taking place over the course of a few months, or a year or two at most.

Patterson and his colleagues have created the highest resolution record of the ‘Big Freeze’ event to date, from a mud core taken from an ancient lake, Lough Monreach, in Ireland. Using a scalpel layers were sliced from the core, just 0.5mm thick, representing a time period of one to three months.

Carbon isotopes in each slice reveal how productive the lake was, while oxygen isotopes give a picture of temperature and rainfall. At the start of the ‘Big Freeze’ their new record shows that temperatures plummeted and lake productivity stopped over the course of just a few years. “It would be like taking Ireland today and moving it up to Svalbard, creating icy conditions in a very short period of time,” says Patterson, who presented the findings at the European Science Foundation BOREAS conference on humans in the Arctic, in Rovaniemi, Finland.

Meanwhile, their isotope record from the end of the Big Freeze shows that it took around two centuries for the lake and climate to recover, rather than the abrupt decade or so that ice cores indicate. “This makes sense because it would take time for the ocean and atmospheric circulation to turn on again,” says Patterson.

Looking ahead to the future Patterson says there is no reason why a ‘Big Freeze’ shouldn’t happen again. “If the Greenland ice sheet melted suddenly it would be catastrophic,” he says.

European Science Foundation

FEAR OF ANXIETY LINKED TO DEPRESSION IN ABOVE-AVERAGE WORRIERS

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Anxiety sensitivity, or the fear of feeling anxious, may put people who are already above-average worriers at risk for depression, according to Penn State researchers. Understanding how sensitivity to anxiety is a risk factor for depression may make anxiety sensitivity a potential target for treating depression in the future.

"Anxiety sensitivity has been called a fear of fear," said Andres Viana, graduate student in psychology. "Those with anxiety sensitivity are afraid of their anxiety because their interpretation is that something catastrophic is going to happen when their anxious sensations arise."

Statistical analyses of questionnaire responses showed that anxiety sensitivity, after controlling for worry and generalized anxiety symptoms in above-average worriers, significantly predicted depression symptoms. In addition, two of the four dimensions that make up anxiety sensitivity - the "fear of cognitive dyscontrol" and the "fear of publically observable anxiety symptoms" specifically predicted depression symptoms. The third and fourth dimensions, the fear of cardiovascular symptoms and the fear of respiratory symptoms, were not significant predictors.

"We were interested in examining the relationship between anxiety sensitivity as a whole and depression," said Viana. "In addition, we looked at the different dimensions of anxiety sensitivity to see which correlated with depression symptoms. One of the novel aspects of our study was to look at anxiety sensitivity in a sample of moderate to high worriers."

Viana, working with Brian Rabian, associate clinical professor and director of the psychological clinic, Penn State, published their findings in the December issue of the Journal of Anxiety Disorders.

To examine the link between anxiety sensitivity and depression the researchers recruited 94 participants -- 74 females and 22 males -- with an average age of 19. All participants were above-average, or moderate to high worriers, on two questionnaires for worry and generalized anxiety disorder, the Generalized Anxiety Disorder Questionnaire and the Penn State Worry Questionnaire, respectively.

Viana and Rabian assessed anxiety sensitivity for each participant with a revised version of the Anxiety sensitivity index, a 36-item questionnaire that determines the fear of anxious sensations. By rating questions like, "when my thoughts seems to speed up, I worry I might be going crazy," on a scale ranging from one to five, researchers were able to determine if participants were sensitive to anxiety and which of the four dimensions they were most fearful of.

"With anxiety sensitivity we are really talking about an individual's interpretation of anxiety symptoms, so the only way to get at that is by asking the person what they think in the form of a self-report questionnaire," said Viana.

Researchers also asked participants to complete the Beck Depression Inventory, a 21-item questionnaire which assesses depression. Participants then rated on a scale of zero to three the degree to which they experience symptoms of sadness, hopefulness or guilt.

"What we found was that the fear of the cognitive sensations typical of anxiety, like the inability to concentrate, was related to depression," said Viana. "And we also found that the link exists in people who are afraid of symptoms that could potentially have social implications or symptoms of anxiety that may be subject to negative evaluation."

Because anxiety sensitivity has been linked to depression in several studies, anxiety sensitivity may be a target for clinicians. Current depression therapies tend to focus solely on depressive symptoms, not anxiety sensitivity. Viana thinks future therapy may incorporate working with people to alter their perception of anxious sensations by helping them interpret their experiences in a positive and less fearful way.

Viana acknowledges the limitations to using questionnaires in his study. He thinks future research should identify individuals with anxiety sensitivity and track them over time to see if depression develops.

Penn State University

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