Saturday, December 11, 2010

CLARITY IN SHORT-TERM MEMORY SHOWS NO LINK WITH IQ

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One person correctly remembers four of eight items just seen but is fuzzy on details. Another person recalls only two of the items but with amazingly precise clarity. So what ability translates to higher IQ?

According to a University of Oregon study, the answer is very clear: More items stored in short-term memory is linked to greater fluid intelligence, as measured in IQ tests. The resolution of those memories, while important in many situations, shows no relationship with fluid intelligence.

The notion that numbers of items is vitally important to short-term memory has been shown in previous studies at the UO. Those studies found that people, generally, have a capacity to temporarily store three to five items in short-term memory. Previous research has shown that capacity in short-term memory is a reliable predictor of an individual's IQ.

However, the new study, published in the October issue of the journal Psychonomic Bulletin & Review, sought to take a more comprehensive look at the issue to determine which aspects of memory capacity explained the link with fluid intelligence.

"The number of things people can remember is robustly correlated with fluid intelligence -- the larger number remembered, the higher the IQ." said Edward Awh, a psychology professor and a member of the Oregon Visual Working Memory & Attention Lab. "Resolution in memory is not predictive of IQ at all."

"Clarity," said lead author Keisuke Fukuda, a UO doctoral student, "relates to how well a person can detect small changes." This clarity, Fukuda and Awh noted, is indeed important but is a reflection of a person's experience in specific domains of perception. For example, while Japanese characters may appear to be similar to an American's eye, regular Japanese readers will readily see the differences between distinct characters.

Fukuda put 79 undergraduate students through a series of experiments in which either four or eight objects were shown on a screen for an instant. After a one-second blank screen, one item was returned and the subject asked whether that object had been in a location previously.

By examining the ability to detect large and small changes in the memorized items, Fukuda was able to get estimates of both the number of items maintained in memory, as well as the resolution or clarity of those memories. These aspects of memory were then related to the subjects' scores on tests of fluid intelligence.

The discovery that clarity doesn't factor into a person's IQ score doesn't suggest that memory resolution is unimportant, the researchers noted. The importance of clarity or resolution of things remembered is indeed vital, for example, to a radiologist studying images of a patient's internal organs with potential disease conditions.

(Photo: U. Oregon)

University of Oregon

WALKING SLOWS PROGRESSION OF ALZHEIMER'S

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Walking may slow cognitive decline in adults with mild cognitive impairment (MCI) and Alzheimer's disease, as well as in healthy adults, according to a study presented at the annual meeting of the Radiological Society of North America (RSNA).

"We found that walking five miles per week protects the brain structure over 10 years in people with Alzheimer's and MCI, especially in areas of the brain's key memory and learning centers," said Cyrus Raji, Ph.D., from the Department of Radiology at the University of Pittsburgh in Pennsylvania. "We also found that these people had a slower decline in memory loss over five years."

Alzheimer's disease is an irreversible, progressive brain disease that slowly destroys memory and cognitive skills. According to the National Institute on Aging, between 2.4 million and 5.1 million Americans have Alzheimer's disease. Based on current population trends, that number is expected to increase significantly over the next decade.

In cases of MCI, a person has cognitive or memory problems exceeding typical age-related memory loss, but not yet as severe as those found in Alzheimer's disease. About half of the people with MCI progress to Alzheimer's disease.

"Because a cure for Alzheimer's is not yet a reality, we hope to find ways of alleviating disease progression or symptoms in people who are already cognitively impaired," Dr. Raji said.

For the ongoing 20-year study, Dr. Raji and colleagues analyzed the relationship between physical activity and brain structure in 426 people, including 299 healthy adults (mean age 78), and 127 cognitively impaired adults (mean age 81), including 83 adults with MCI and 44 adults with Alzheimer's dementia.

Patients were recruited from the Cardiovascular Health Study. The researchers monitored how far each of the patients walked in a week. After 10 years, all patients underwent 3-D MRI exams to identify changes in brain volume.

"Volume is a vital sign for the brain," Dr. Raji said. "When it decreases, that means brain cells are dying. But when it remains higher, brain health is being maintained."

In addition, patients were given the mini-mental state exam (MMSE) to track cognitive decline over five years. Physical activity levels were correlated with MRI and MMSE results. The analysis adjusted for age, gender, body fat composition, head size, education and other factors.

The findings showed across the board that greater amounts of physical activity were associated with greater brain volume. Cognitively impaired people needed to walk at least 58 city blocks, or approximately five miles, per week to maintain brain volume and slow cognitive decline. The healthy adults needed to walk at least 72 city blocks, or six miles, per week to maintain brain volume and significantly reduce their risk for cognitive decline.

Over five years, MMSE scores decreased by an average of five points in cognitively impaired patients who did not engage in a sufficient level of physical activity, compared with a decrease of only one point in patients who met the physical activity requirement.

"Alzheimer's is a devastating illness, and unfortunately, walking is not a cure," Dr. Raji said. "But walking can improve your brain's resistance to the disease and reduce memory loss over time."

Radiological Society of North America

CROWN REVEALS NEW HOLY FEMALE PHARAOH

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A unique queen's crown with ancient symbols combined with a new method of studying status in Egyptian reliefs forms the basis for a re-interpretation of historical developments in Egypt in the period following the death of Alexander the Great. A thesis from the University of Gothenburg (Sweden) shows that Cleopatra was not ancient Egypt's only female pharaoh – Queen Arsinoë II came first, 200 years earlier.

Researchers are largely agreed on Queen Arsinoë II's importance from the day that she was deified. She was put on a level with the ancient goddesses Isis and Hathor, and was still respected and honoured 200 years after her death when her better-known descendant Cleopatra wore the same crown. But the reasons behind Arsinoë's huge influence have been interpreted in many different ways.

Maria Nilsson has studied her historical importance by interpreting her personal crown and its ancient symbols. The crown, which has never been found but is depicted on statues and Egyptian reliefs, was created with the help of the powerful Egyptian priesthood to symbolise the qualities of the queen. The thesis questions the traditional royal line which excludes female regents, and defies some researchers' attempts to minimise Arsinoë's importance while she was still alive.

"My conclusion instead is that Arsinoë was a female pharaoh and high priestess who was equal to and ruled jointly with her brother and husband, and that she was deified during her actual lifetime," says Nilsson. "It was this combination of religion and politics that was behind her long-lived influence."

But it was not only Cleopatra who wanted to re-use Arsinoë's important and symbolic crown. Male descendants – all named Ptolemy – used her crown as a template when creating a new crown which they gave to the goddess Hathor to honour the domestic priesthood and so win its support when Egypt was gripped by civil war.

The thesis is clearly structured around the crown and includes its wider context in the reliefs. Nilsson paints an all-round picture of the queen, how she dressed, the gods she was depicted with, the titles she was given, and so on.

The source material comes from Egypt and can be used as a basis for understanding the country's political and religious development. At the same time, Nilsson paves the way for future studies of Egyptian crowns as symbols of power and status, and of the development of art in a more general sense.

"The creation of Queen Arsinoë's crown was just the beginning," she says.

(Photo: Maria Nilsson)

University of Gothenburg

REACHING 100 YEARS OF AGE MAY BE MORE ABOUT ATTITUDE AND ADAPTATION THAN HEALTH HISTORY

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University of Georgia research has provided new clues on surviving to be 100 years old, finding that how we feel about ourselves and our ability to adapt to an accumulation of challenging life experiences may be as or more important than health factors.

The research, published in the current edition of the journal Current Gerontology and Geriatrics Research, used data collected as part of the Georgia Centenarian Study, one of only two centenarian studies in the country, to measure psychological and social factors in addition to genetics and health of so-called expert survivors. Two hundred forty-four people age100 years or older were studied between 2001 and 2009. The research found that critical life events and personal history, along with how people adapt to stressful situations and cope with them are crucial to explaining successful aging.

“Understanding health in these terms has huge implications for quality of life,” said Leonard Poon, director of the Institute of Gerontology in the UGA College of Public Health and lead author of the study. “What is happening to you matters, but more importantly, it is your perception of what is happening to you that is really important for your individual health.”

A majority of past research on the oldest of the old focused on health factors, but the researchers found that centenarians’ feelings about their own health, well-being and support systems, rather than measures such as blood pressure and blood sugar are stronger predictors of survival, said Poon.

Personality also determined how well the centenarians reacted to life stress and change, and therefore whether they were as happy in their old age as they were when young. Healthy 100-year-olds had personalities described as open and conscientious. Neurotic personalities tended to be less healthy, the study found.

An individual confronted with a stressful situation can either find a quick emotional solution or ruminate on the problem, explained Poon. “One is very destructive in terms of general well-being,” he said, “and the other is very adaptive.”

Other research drawing from the Georgia Centenarian Study compared physical function of the elderly living in the community with those living in retirement facilities and found that physical activity decreased by approximately one-third when community residents moved to retirement facilities.

A decrease in physical activity accelerates a decline in health, explained Elaine Cress, professor in the Institute of Gerontology and lead author of a related study published in the current issue of the journal Gerontology.

“By understanding physical decline in functioning, caregivers can help maintain a high quality of life for the centenarian with appropriate support,” said Cress, who also is a faculty member in the department of kinesiology in the UGA College of Education. “We developed a scale to assess physical performance, which has not been done before with centenarians. This can be used in future research to predict when people are going to start needing more help. They need to know how to plan, and society needs to know how to plan, too.

Although still rare, centenarians are a growing segment of the population. Poon notes there were an estimated 50,454 in 2000, but the number is expected to rise to more than 800,000 by 2050, making accurate information about their well-being increasingly important.

Poon added that one phenomenon that occurs all over the world is that women live longer than men. In industrialized countries such as the U.S., France and Japan, five to six women reach 100 years for every man who does. Only Sardinia has a one-to-one ratio. At the opposite extreme, 13 South Korean women live to be 100 for every man.

“Our next phase is to go to four different countries where there are different gender survival ratios and see why they are the same, why they are different and what makes women live longer than men,” said Poon.

University of Georgia

GLOBAL SEA-LEVEL RISE AT THE END OF THE LAST ICE AGE

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Southampton researchers have estimated that sea-level rose by an average of about 1 metre per century at the end of the last Ice Age, interrupted by rapid ‘jumps’ during which it rose by up to 2.5 metres per century. The findings, published in Global and Planetary Change, will help unravel the responses of ocean circulation and climate to large inputs of ice-sheet meltwater to the world ocean.

Global sea level rose by a total of more than 120 metres as the vast ice sheets of the last Ice Age melted back. This melt-back lasted from about 19,000 to about 6,000 years ago, meaning that the average rate of sea-level rise was roughly 1 metre per century.

Previous studies of sea-level change at individual locations have suggested that the gradual rise may have been marked by abrupt ‘jumps’ of sea-level rise at rates that approached 5 metres per century. These estimates were based on analyses of the distribution of fossil corals around Barbados and coastal drowning along the Sunda Shelf, an extension of the continental shelf of East Asia.

However, uncertainties in fossil dating, scarcity of sea-level markers, and the specific characteristics of individual sites can make it difficult to reconstruct global sea level with a high degree of confidence using evidence from any one site.

“Rather than relying on individual sites that may not be representative, we have compared large amounts of data from many different sites, taking into account all potential sources of uncertainty,” said Professor Eelco Rohling of the University of Southampton’s School of Ocean and Earth Science (SOES) based at the National Oceanography Centre (NOC) in Southampton.

The researchers brought together about 400 high-quality sea-level markers from study sites around the globe, concentrating on locations far removed from the distorting effects of the past massive ice sheets.

Using an extensive series of sophisticated statistical tests, they then reconstructed sea-level history of the last 21 thousand years with a high degree of statistical confidence.

Their analyses indicate that the gradual rise at an average rate of 1 metre per century was interrupted by two periods with rates of rise up to 2.5 metres per century, between 15 and 13 thousand years ago, and between 11 and 9 thousand years ago.

The first of these jumps in the amount of ice-sheet meltwater entering the world ocean coincides with the beginning of a period of global climate warming called the Bølling-Allerød period. The second jump appears to have happened shortly after the end the ‘big freeze’ called the Younger Dryas that brought the Bølling-Allerød period to an abrupt end.

“Our estimates of rates of sea-level rise are lower than those estimated from individual study sites, but they are statistically robust and therefore greatly improve our understanding of loss of ice volume due to the melting of the ice sheets at the end of the last Ice Age,” said lead author Dr Jennifer Stanford of SOES.

“The new findings will be used to refine models of the Earth climate system, and will thus help to improve forecasts of future sea-level responses to global climate change,” added Rohling.

(Photo: E. Rohling)

National Oceanography Centre (NOC)

RESEARCHERS DEMYSTIFY GLASSES BY STUDYING CRYSTALS

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Glass is something we all know about. It's what we sip our drinks from, what we look out of to see what the weather is like before going outside and it is the backbone to our high speed communications infrastructure (optical fibers).

But what most people don't know is that "glass transitions," where changes in structure of a substance accompanying temperature change get "frozen in," can show up during cooling of most any material, liquids through metals. This produces "glassy states," of that material – exotic states that can be unfrozen and refrozen by merely changing the temperature a little up and down around the transition temperature.

"For liquids," says C. Austen Angell, an Arizona State University Regents professor of chemistry and biochemistry and a leading explorer in this domain, "it's fairly simple, glasses form when crystals don't." Beyond this "banality," as Angell calls it, things get more complicated.

Angell has done considerable work in this realm, the best known of which has been on the classification of glass-forming liquids between extreme types – "strong" liquids, like the silica glass that optical fibers are made from, and "fragile" liquids which glassblowers stay away from because, during cooling, they set up solid too quickly for them to work with.

Now another piece of the puzzle is being reported on what, exactly, glasses are. The report uses the unusual behavior of a non-liquid substance to help unlock the secrets. It is a metallic alloy consisting of equal parts of cobalt and iron.

In a paper in the Nov. 28, 2010, issue of Nature Physics, Angell and his colleagues – Shuai Wei, Isabella Gallino and Ralf Busch, all of Saarland University, Germany – describe the behavior of iron-cobalt (Fe50Co50) superlattice material as it cools down from its randomly ordered high temperature state. The paper, "Glass transition with decreasing correlation length during cooling of Fe50Co50 superlattice and strong liquids," builds on work from 1943 by Kaya and Sato in Japan who measured the heat capacity of the bi-metallic alloy.

Heat capacity is the amount of energy it takes to heat a sample by one degree Kelvin. Albert Einstein thought heat capacity was a material's most revealing property.

The iron-cobalt alloy heat capacity showed two features – a sharp spike at 1000 K (1340 F) called a lambda transition (which is quite common in metal alloys as the two types of atoms order themselves onto two individual interpenetrating lattices) – and near 750K (890 F) another feature which is very unusual for a metallic crystal, a glass-like transition, where the state of order gets "frozen in" during cooling.

Most glassy forms of matter experience a gradual increase in heat capacity as they are heated until this special transition point is reached. At this point (called the glass temperature) the materials suddenly jump to a new, higher heat capacity zone, often 100 percent higher, and change from a solid material to a very viscous liquid.

What the new measurements in the Nature Physics article show is that the disordering of the superlattice has the kinetic characteristic of strong liquids. But because the alloy lambda transition is well understood, researchers know that a property called the "correlation length" is decreasing as the temperature decreases from the lambda spike towards the (glass) transition temperature. This is the opposite behavior from what has been thought to be characteristic of liquids as they cool towards their transition temperature.

"We now argue that strong and fragile extremes are not really extremes, so much as they are opposites," Angell said.

"On a molecular level, we now think that in the strong liquids the organization of molecules in space is getting shorter-range as the glassy state is approached, while in the fragile liquids, that organization length is indeed getting longer as people have already proposed," he explained. "This shows that static correlation length changes do not, by themselves, account for the liquid turning solid at the glass transition."

To understand the paradox Angell turned to the substance water. Water is famous for having strikingly anomalous properties in its super cooled state. As 228 K (-49 F) is approached, water's heat capacity is racing up like that of iron-cobalt alloy at its critical point. Scientists now believe that water would show the same sort of spike if it didn't crystallize first. When water is quenched at a million degrees per second it doesn't crystallize and a glass that acts like a low temperature replica of silica results, i.e. a strong liquid. Angell sees water's behavior as a sort of Rosetta stone.

"The Rosetta stone has two faces, the same statement on each but in a different language," he said. "In my case, water speaks the language of fragile liquids on its upper face (at temperatures more than 228 K, or -49 F), and the language of strong liquids on its lower face (temperatures less than 228 K)."

Previous work by Angell (with Robin Speedy in 1976) pinpointed the 228 K temperature as a "divergence temperature" of a special mathematical law, called a power law, typical of critical systems, which described the physical properties of super cooled water.

"So now we see strong liquids and fragile liquids as occupying opposite flanks of some generalized 'order-disorder' transition," Angell explained. Angell and his colleague Dmitry Matyushov in ASU's physics department, plan to describe this generalized transition in more detail in the future.

Meantime there are practical benefits to be had. Angell points out that if optical fiber glasses, being silica or silica-like, have shorter range organization at lower temperatures, then fibers that have been annealed at lower temperatures than their fiber-drawing temperature (more than 2000 K) should be less scattering of light, hence better for communications purposes. Thus this new information can mean better performing materials in the future.

"Patent literature suggests that the fiber optics scientists already learned the benefits of annealing (a heat treatment that alters the microstructure of a material causing changes in properties such as strength, hardness and ductility). Now we would know exactly why this is so, and we could actually design that property into the material forming process," Angell said.

Arizona State University

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