Move, adapt or die. Those are the options marine plants and animals have in the face of climate change, said Stanford biologist Steve Palumbi, who has been exploring how to help them go with the first two options, rather than the third. He’s come up with some surprising answers.

Palumbi discussed the results of his research in two talks at the annual meeting of the American Association for the Advancement of Science in San Diego.

How to design marine protected areas to best benefit a wide variety of plant and animal species was the focus of a talk he gave on Feb. 20. The most practical kind of natural reserve is one that benefits species and local human populations, but Palumbi said striking that balance isn’t always easy. Many people have argued that bigger is better when it comes to marine reserves, but Palumbi has data suggesting that is not always the case.

In a separate Topical Lecture he delivered on Feb. 21, Palumbi presented his findings on how marine species are reacting to climate change, including new work on coral species in the Pacific that have poor powers of dispersal but a surprising ability to cope with higher temperatures.

Palumbi is director of Stanford’s Hopkins Marine Station and a senior fellow at the university’s Woods Institute for the Environment.

If you can’t move, then you’d better adjust

Many species, such as those along the west coast of California, can simply migrate north to colder waters. But other animals, such as the coral that Palumbi’s team has studied in Fiji and American Samoa, won’t be moving anytime soon.

“Each coral population is trapped on its own island, and as global climate changes around them, the populations are essentially stuck where they are. They have to go to the second stage, which is to adapt,” Palumbi said.

Marine scientists have predicted that coral reefs will be at risk of extinction due to high ocean temperatures caused by climate change, but Palumbi has found a species of coral that may have a better chance of adapting.

Palumbi’s team studied corals growing in shallow lagoons that face intense heat during noontime summer low tides. The team knew these corals were resistant to brief heating but were surprised to find that the corals survived five to six days of high water temperatures. Baking in the tropical summer sun at low tide for 4 to 6 hours a day seems to have better prepared these corals for global warming temperatures.

“When we tested these corals against high temperatures for extended periods of time, they showed all the evidence of having higher resilience,” Palumbi said. “It looks like the corals have adapted or acclimated to that stress and have a better chance of resisting high global warming temperatures.” How long this resilience will last, and whether all corals can do this, are remaining questions.

Does size matter for marine reserves

A major response to climate change is to protect reefs from other human-caused stresses such as overfishing. And as a result, a large number of Marine Protected Areas have been implemented in the Pacific. Some are the size of a football field. Some are the size of California. Is bigger better?

To determine how much difference the size of a protected area might make, Palumbi analyzed data from a set of small reserves in Fiji, from the Phoenix Islands and from the Papahanaumokuakea Reserve in Hawaii, the largest marine reserve in the world. All three areas are set aside by government agencies.

The Papahanaumokuakea Marine National Monument covers 360,000 square kilometers (139,000 square miles) in Northwest Hawaii and is a “no-take” reserve, which means nothing may be removed, including fish.

The Phoenix Islands Protected Area, which lies in the central Pacific Ocean between Hawaii and Fiji, is over 408,000 square kilometers (158,000 square miles). There are seven no-take reserves in this area, each about 39 kilometers (24 miles) across.

However, in densely populated areas, smaller reserves are more common. Fiji has 246 such protected areas, each averaging about 2 to 3 square kilometers (about a square mile).

“Small sets of marine protected areas are much more convenient: People can fish in between them or go around them easily. Species found within the marine protected areas easily spill out into the surrounding areas, potentially increasing fishing productivity,” Palumbi said.

However, wide stretches of protected ocean allow species to spread more easily than small areas, where they risk being caught by fishermen between the reserves. Therefore, small reserves must be well matched to the plants and animals they are protecting because each species spreads at different rates, Palumbi said.

“Species have lots of different dispersal abilities, so it’s very hard to have a marine protected area network that works equally well for all different species. You have to tailor the network of reserves to the species,” he said.

Though small reserves meet the needs of fewer species than those of larger reserves, setting aside enormous areas of ocean is not that simple. Scientists and policymakers must consider local residents who depend on fisheries for their well-being.

“With heavy human populations, the political, social and economic problems of a big marine protected area are paramount and you’ve got to go to another strategy. But it’s a strategy with limitations because it’s hard to design an area perfectly for all species that need protection,” Palumbi said. The most effective reserve is one that balances preservation of species with human needs, he said. Finding that balance is the challenge.

Source – Stanford University

While the technology is still new, Cui’s team has envisioned numerous functional uses for their inventions. Homes of the future could one day be lined with energy-storing wallpaper. Gadget lovers would be able to charge their portable appliances on the go, simply plugging them into an outlet woven into their T-shirts. Energy textiles might also be used to create moving-display apparel, reactive high-performance sportswear and wearable power for a soldier’s battle gear.

The key ingredients in developing these high-tech products are not visible to the human eye. Nanostructures, which can be assembled in patterns that allow them to transport electricity, may provide the solutions to a number of problems encountered with electrical storage devices currently available on the market.

The type of nanoparticle used in the Cui group’s experimental devices varies according to the intended function of the product — lithium cobalt oxide is a common compound used for batteries, while single-walled carbon nanotubes, or SWNTs, are used for supercapacitors.

Cui, an assistant professor of materials science and engineering at Stanford, leads a research group that investigates new applications of nanoscale materials. The objective, said Cui, is not only to supply answers to theoretical inquiries but also to pursue projects with practical value. Recently, his team has focused on ways to integrate nanotechnology into the realm of energy development.

“Energy storage is a pretty old research field,” said Cui. “Supercapacitors, batteries — those things are old. How do you really make a revolutionary impact in this field? It requires quite a dramatic difference of thinking.”

While electrical energy storage devices have come a long way since Alessandro Volta debuted the world’s first electrical cell in 1800, the technology is facing yet another revolution. Current methods of manufacturing energy storage devices can be capital intensive and environmentally hazardous, and the end products have noticeable performance constraints — conventional lithium ion batteries have a limited storage capacity and are costly to manufacture, while traditional capacitors provide high power but at the expense of energy storage capacity.

With a little help from new science, the batteries of the future may not look anything like the bulky metal units we’ve grown accustomed to. Nanotechnology is favored as a remedy both for its economic appeal and its capability to improve energy performance in devices that integrate it. Replacing the carbon (graphite) anodes found in lithium ion batteries with anodes of silicon nanowires, for example, has the potential to increase their storage capacity by 10 times, according to experiments conducted by Cui’s team.

Silicon had previously been recognized as a favorable anode material because it can hold a larger amount of lithium than carbon. But applications of silicon were limited by its inability to sustain physical stress — namely, the fourfold volume increase that silicon undergoes when lithium ions attach themselves to a silicon anode in the process of charging a battery, as well as the shrinkage that occurs when lithium ions are drawn out as it discharges. The result was that silicon structures would disintegrate, causing anodes of this material to lose much if not all of their storage capacity.

Cui and collaborators demonstrated in previous publications in Nature, Nanotechnology and Nano Letters that the use of silicon nanowire battery electrodes, mechanically capable of withstanding the absorption and discharge of lithium ions, was one way to sidestep the problem.

The findings hold promise for the development of rechargeable lithium batteries offering a longer life cycle and higher energy capacity than their contemporaries. Silicon nanowire technology may one day find a home in electric cars, portable electronic devices and implantable medical appliances.

Cui now hopes to direct his research toward studying both the “hard science” behind the electrical properties of nanomaterials and designing real-world applications.

“This is the right time to really see what we learn from nanoscience and do practical applications that are extremely promising,” said Cui. “The beauty of this is, it combines the lowest cost technology that you can find to the highest tech nanotechnology to produce something great. I think this is a very exciting idea … a huge impact for society.”

The Cui group’s latest research on energy storage devices was detailed in papers published in the online editions of the Proceedings of the National Academy of Sciences in December 2009 (“Highly Conductive Paper for Energy-Storage Devices”) and Nano Letters in January 2010 (“Stretchable, Porous and Conductive Energy Textiles”).

Cui’s presented his talk at the symposium “Nanotechnology: Will Nanomaterials Revolutionize Energy Applications?” at the San Diego Convention Center.

Source – Stanford University

Their study is scheduled for publication in the journal Nature on Feb. 24.

Now, for the first time, science has a solid grasp of what those relationships are, and a framework upon which to build. The new study makes a major contribution to our understanding of the nature and origins of the planet’s biodiversity. The paper’s other researchers are Jerome C. Regier, Andreas Zwick and April Hussey from the University of Maryland Biotechnology Institute; Jeffrey W. Shultz of the University of Maryland’s Department of Entomology; and Bernard Ball and Clifford W. Cunningham from Duke University’s Department of Biology.

There are millions of distinct species of arthropods, including all the insects, crustaceans, millipedes, centipedes, spiders, and a host of other animals, all united by having a hard external shell and jointed legs. They are by far the most numerous, and most diverse, of all creatures on Earth — in terms of the sheer number of species, no other group comes close. They make up perhaps 1.6 million of the estimated 1.8 to 1.9 million described species, dominating the planet in number, biomass, and diversity.

The economic aspects of arthropods are also overwhelming. From seafood industries worth billions of dollars annually to the world’s economy, to the importance of insects as pollinators of ornamental and agriculturally important crops, to the medical role played by arthropods (e.g. as disease vectors and parasites), to biological control of introduced species, to their role in every known food web, to toxicology and biopharmaceuticals, arthropods are by far the planet’s most important group of animals.

“We’ve never really known how arthropods, the most successful animals on Earth, evolved into the diversity we see today,” said research scientist and co-author Dr. Regina Wetzer. “For me, what makes this study really exciting is getting such a solid understanding of how these animals are related, so that now we can better understand how they evolved.”

Because of their amazing diversity, deciphering the evolutionary history and relationships among the major subgroups of arthropods has proven difficult. Scientists have tried using various combination of features, in recent years including DNA sequences, to try to understand which groups are related through common ancestors. To date, those attempts have been stymied by the sheer number of species and wild shape variations between the various groups.

One of the most important results of this new study is support for the hypothesis that the insects evolved from a group of crustaceans. So flies, honeybees, ants, and crickets all branched off the arthropod family tree from within the lineage that gave rise to today’s crabs, shrimp, and lobsters. Another important finding is that the “Chelicerata” (a group that includes the spiders, scorpions, ticks, and mites) branched off very early, earlier than the millipedes, centipedes, crustaceans, and insects. That means that the spiders, for example, are more distantly related to the insects than many researchers previously thought.

This team approached the problem of illuminating the arthropod family tree by using genetic data (DNA sequences) obtained from 75 species carefully selected to sample the range of arthropod diversity. Many previous analyses were based on the sequences of a handful of genes. The researchers in this study, knowing the daunting diversity they faced, used DNA sequence information from as many genes as they could. In the end, they were able to apply data from 62 protein-coding genes to the problem, leading to an extremely well-supported analysis.

“The Museum’s collection of arthropods, and in particular its collection of crustaceans, are what made a study like this possible in the first place,” says Dr. Joel W. Martin, NHM Curator of Crustacea and one of the authors who designed the study nearly eight years ago. “The wealth of stored biodiversity information contained in it, both in terms of specimens and in terms of the data, theories, and research related to those specimens, are why natural history museums exist, and why they play such a critical role in explaining the world’s diversity. Studies like this confirm the incredible value, not only of existing natural history museum collections, but of continuing to add to these collections every year.”

A key problem that the research team had to solve was obtaining specimens of some of rare and obscure organisms whose DNA was needed for the analysis. Because of their extensive experience in field biology, this was a major contribution to the project from NHM scientists. Dr. Wetzer recalls lying on the beach with a microscope at Woods Hole, Massachusetts. She was hunting for specimens of a tiny, little-known crustacean that lives between grains of sand. “I got the mystacocarids we needed, but I think I also provided pretty good entertainment to the families at the beach that day,” Dr. Wetzer said.

Source – Natural History Museum

The study, to be published the week of February 22 in the early edition of the Proceedings of the National Academy of Sciences, adds new insight to a highly controversial question: What is intelligence, and how can we measure it?

The research team included Jan Gläscher, first author on the paper and a postdoctoral fellow at Caltech, and Ralph Adolphs, the Bren Professor of Psychology and Neuroscience and professor of biology. The Caltech scientists teamed up with researchers at the University of Iowa and USC to examine a uniquely large data set of 241 brain-lesion patients who all had taken IQ tests. The researchers mapped the location of each patient’s lesion in their brains, and correlated that with each patient’s IQ score to produce a map of the brain regions that influence intelligence.

“General intelligence, often referred to as Spearman’s g-factor, has been a highly contentious concept,” says Adolphs. “But the basic idea underlying it is undisputed: on average, people’s scores across many different kinds of tests are correlated. Some people just get generally high scores, whereas others get generally low scores. So it is an obvious next question to ask whether such a general ability might depend on specific brain regions.”

The researchers found that, rather than residing in a single structure, general intelligence is determined by a network of regions across both sides of the brain.

“One of the main findings that really struck us was that there was a distributed system here. Several brain regions, and the connections between them, were what was most important to general intelligence,” explains Gläscher.

“It might have turned out that general intelligence doesn’t depend on specific brain areas at all, and just has to do with how the whole brain functions,” adds Adolphs. “But that’s not what we found. In fact, the particular regions and connections we found are quite in line with an existing theory about intelligence called the ‘parieto-frontal integration theory.’ It says that general intelligence depends on the brain’s ability to integrate — to pull together — several different kinds of processing, such as working memory.”

The researchers say the findings will open the door to further investigations about how the brain, intelligence, and environment all interact.

The work at Caltech was funded by the National Institutes of Health, the Simons Foundation, the Deutsche Akademie der Naturforscher Leopoldina, and a Global Center of Excellence grant from the Japanese government.

Link

“This is the first time cortisol reactivity has been identified as a mediator between depressed mood and obesity in girls,” said Elizabeth J. Susman, the Jean Phillips Shibley professor of biobehavioral health at Penn State. “We really haven’t seen this connection in kids before, but it tells us that there are biological risk factors that are similar for obesity and depression.”

Cortisol, a hormone, regulates various metabolic functions in the body and is released as a reaction to stress. Researchers have long known that depression and cortisol are related to obesity, but they had not figured out the exact biological mechanism.

Although it is not clear why high cortisol reactions translate into obesity only for girls, scientists believe it may be due to physiological and behavioral differences — estrogen release and stress eating in girls — in the way the two genders cope with anxiety.

“The implications are to start treating depression early because we know that depression, cortisol and obesity are related in adults,” said Susman.

If depression were to be treated earlier, she noted, it could help reduce the level of cortisol, and thereby help reduce obesity.

“We know stress is a critical factor in many mental and physical health problems,” said Susman. “We are putting together the biology of stress, emotions and a clinical disorder to better understand a major public health problem.”

Susman and her colleagues Lorah D. Dorn, professor of pediatrics, Cincinnati Children’s Hospital Medical Center, and Samantha Dockray, postdoctoral fellow, University College London, used a child behavior checklist to assess 111 boys and girls ages 8 to 13 for symptoms of depression. Next they measured the children’s obesity and the level of cortisol in their saliva before and after various stress tests.

“We had the children tell a story, make up a story, and do a mental arithmetic test,” said Susman. “The children were also told that judges would evaluate the test results with those of other children.”

Statistical analyses of the data suggest that depression is associated with spikes in cortisol levels for boys and girls after the stress tests, but higher cortisol reactions to stress are associated with obesity only in girls. The team reported its findings in a recent issue of the Journal of Adolescent Health.

“In these children, it was mainly the peak in cortisol that was related to obesity,” Susman explained. “It was how they reacted to an immediate stress.”

This relationship is pretty well known. But why it is so remains mysterious. Now physicists at Brown University have documented for the first time a quantum-level phenomenon that occurs to electrons subjected to magnetism in a superconducting material. In a paper published in Physical Review Letters, Vesna Mitrovic, joined by other researchers at Brown and in France, report that at under certain conditions, electrons in a superconducting material form odd, fluctuating magnetic waves. Apply a little more magnetic force, and those fluctuations cease: The electronic magnets form repeated wave-like patterns promoted by superconductivity.

The discovery may help scientists understand more fully the relationship between magnetism and superconductivity at the quantum level. The insight also may help advance research into superconducting magnets, which are used in magnetic resonance imaging (MRI) and a host of other applications. “If you don’t understand [what is happening at] the quantum [level], how can you design a more powerful magnet?” asked Mitrovic, assistant professor of physics.

When a magnetic field is applied to a superconducting material, vortices measured in nanometers (1 billionth of a meter) pop up. These vortices, like super-miniature tornadoes, are areas where the magnetic field has overpowered the superconducting field state, essentially suppressing it. Crank up the magnetic field and more vortices appear. At some point, the vortices are so widespread the material loses its superconducting ability altogether.

At an even more basic level, sets of electrons called Cooper pairs (named for Brown physicist Leon Cooper, who shared a Nobel Prize for the discovery) form superconductivity. But scientists believe there also are other electrons that are magnetically oriented and spin on their own axes like little globes; these electrons are tilted at various angles on their imaginary axes and move in a repeating, linear pattern that resembles waves, Mitrovic and her colleagues have observed.

“These funny waves most likely appear because of superconductivity, but the reason why is still unsettled,” Mitrovic said.

Adding to the mystery, Mitrovic and fellow researchers, including Brown graduate student Georgios Koutroulakis and former Brown postdoctoral associate Michael Stewart, saw that the waves fluctuated under certain conditions. After nearly three years of experiments at Brown and at the national magnetic field laboratory in Grenoble, France, Mitrovic’s team was able to produce the odd waves consistently when testing a superconducting material — cerium-cobalt-indium5 (CeCoIn5) — at temperatures close to absolute zero and at about 10 Tesla of magnetic force.

The waves appeared to be sliding, Mitrovic said. “It’s as if people are yanking on the wave,” she added. Mitrovic and her colleagues also observed that when more magnetic energy is added, the fluctuations disappear and the waves resume their repeating, linear patterns.

The researchers next want to understand why these fluctuations occur and whether they crop up in other superconducting material.

The research was funded by the National Science Foundation and a European Community grant, as well as the Alfred P. Sloan Foundation.

The iSWA is a robust, integrated system provides information about space weather conditions past, present, and future and, unlike many other programs currently in use, has an interface that the user can customize to suit a unique set of data requirements.

“The iSWA space-weather data analysis system offers a unique level of customization and flexibility to maintain, modify, and add new tools and data products as they become available,” says Marlo Maddox, iSWA system chief developer at NASA Goddard.

iSWA draws together information about conditions from the sun to the boundary of the sun’s influence, known as the heliosphere. The iSWA systems digests information from spacecraft including the National Oceanic and Atmospheric Administration’s (NOAA) Geostationary Operational Environmental Satellites (GOES), NASA’s Solar Terrestrial Relations Observatory (STEREO), the joint European Space Agency and NASA mission Solar and Heliospheric Observatory (SOHO), and NASA’s Advanced Composition Explorer (ACE).

Citizen scientists and science enthusiasts can also use the data, models, and tools of the iSWA system. Similar to the way in which armchair astronomers have used SOHO data to discover comets, enthusiasts will find the iSWA system a wonderful resource for increasing their familiarity with the concept of space weather.

“We are continuously evolving the iSWA system, and we hope that it will benefit not only NASA satellite operators, but also that it may also help space-weather forecasting at other agencies such as the Air Force Weather Agency and NOAA,” says Michael Hesse, chief of the Space Weather Laboratory at NASA Goddard.

Space-weather information tends to be scattered over various Web sites. NASA Goddard space physicist Antti Pulkkinen says the iSWA system represents “the most comprehensive single interface for general space-weather-related information,” providing data on past and current space-weather events. The system allows the user to configure or design custom displays of the information.

The system compiles data about conditions on the sun, in Earth’s magnetosphere—the protective magnetic field that envelops our planet—and down to Earth’s surface. It provides a user interface to provide NASA’s satellite operators and with a real-time view of space weather. In addition to NASA, the iSWA system is used by the Air Force Weather agency.

Access to space-weather information that combines data from state-of-the-art space-weather models with concurrent observations of the space environment provides a powerful tool for users to obtain a personalized “quick look” at space-weather information, detailed insight into space-weather conditions, as well as tools for historical analysis of the space-weather’s impact.

Development of the iSWA system has been a joint activity between the Office of the Chief Engineer at NASA Headquarters and the Applied Engineering and Technology Directorate and the Science and Exploration Directorate at NASA Goddard. The iSWA system is located at NASA Goddard.

The Community Coordinated Modeling Center is funded by the Heliophysics Division in the Science Mission Directorate at NASA Headquarters, and the National Science Foundation.

“This method can be used to determine if the cancer has spread from stage 2, where the melanoma is still just in the skin lesion, to stage 3, where the melanoma has spread to the lymph nodes,” said John Viator, assistant professor in the Department of Biological Engineering[1] and Department of Dermatology[2]. “If the cancer is still at stage 2, a simple procedure can remove that lesion. If the cancer has progressed from the initial skin lesion into the lymphatic region and possibly the bloodstream, doctors have to make serious decisions about patient care. The cancer may have possibly spread to other organs, such as the liver, lungs or brain.”

Currently, pathologists must perform several specific and detailed tests to determine if there is cancer in the lymph nodes. This new technology could make the search less time-consuming by identifying a general area of the lymph node that might contain cancer.

“It’s very similar to identifying a prize inside a cake,” Viator said. “Instead of looking through the entire cake, we can use our ultrasound to pinpoint a slice or two that might contain the ‘prize.’ In the case of the lymph nodes, when you get a signal, this alerts the pathologist that this is an area of the node that might contain cancer cells. At that point, a pathologist would be able to narrow down the search, saving time and money.”

In the photoacoustic method, a tabletop device scans a lymph node biopsy with laser pulses. About 95 percent of melanoma cells contain melanin, the pigment that gives skin its color, so they react to the laser’s beam, absorbing the light. The laser causes the cells to heat and cool rapidly, which makes them expand and contract. This produces a popping noise that special sensors can detect. This method would examine the entire biopsy and identify the general area of the node that has cancer, giving pathologists a better idea of where to look for the cancer.

“This method is quicker and simpler and could be used to improve the efficiency of how doctors determine if the cancer has spread from the original skin lesion into the lymphatic system,” Viator said. “This technology could be an important tool in our fight against cancer.”

In the study, Viator took human cancer cells and placed them inside canine lymph nodes. Then, using the laser, he determined the best ways to locate the cancer cells. The next step is to try the procedure using human lymph nodes.

The study, “Photoacoustic Detection of Melanoma Micrometastatis in Sentinel Lymph Nodes,” was published in the Journal of Biomedical Engineering.

In this prospective study of the relationship between happiness and heart disease, researchers concluded that if everyone did more of the things that made them happy, they could significantly reduce their risk of heart attack and angina.

“We were excited to discover in a large population-based sample of adults that the tendency to express positive emotion predicted fewer heart attacks across a period of 10 years,” said lead researcher Karina Davidson, director of Columbia’s Center for Behavioral Cardiovascular Health.

“The study suggests that those people who are happier have heart-protective outcomes,” she added.

Davidson speculated that several factors may combine to producing this effect. Happier people tend to sleep better and to practice more heart-healthy behaviors, she said.

“But they may also be physiologically different than those of us who are more unhappy,” Davidson said.

In addition, these people tend to have less stress in their lives and handle the stress they do have better than less happy people, she added.

The report is published in the Feb. 18 issue of the European Heart Journal.

For the study, Davidson’s team followed 1,739 men and women for 10 years. These people all participated in the 1995 Nova Scotia Health Survey. At the start of the study, everyone had their risk for heart disease assessed.

In addition, researchers looked for symptoms of depression, hostility, anxiety and the expression of positive emotions — known as “positive affect.” This is defined as the experience of pleasurable emotions, such as joy, happiness, excitement, enthusiasm and contentment, according to Davidson.

The researchers found that over the study period the happier someone was, the less likely he or she was to develop heart disease. In fact, for every point on a five-point scale that measured positive affect, the risk of heart disease dropped 22 percent.

However, unhappy people had a 22 percent increased risk of having a heart attack or chronic chest pain, compared with those who were somewhat happy. These somewhat happy people also had a 22 percent increased risk for heart problems compared with people who were moderately happy, the researchers noted.

People who were generally happy, but had a few symptoms of depression, did not see these symptoms increase their lowered risk for heart disease, Davidson added.

Davidson noted that she is involved in a clinical trial to test whether changing people’s happiness level improves their heart health.

“In the meantime, it is good for one’s quality of life and mental health to engage in happy behaviors or things that give you pleasure on a daily basis — and many of us here in North America don’t do that,” she said.

Dr. Gregg C. Fonarow, professor of cardiology at the University of California, Los Angeles and co-director of the UCLA Preventative Cardiology Program, said that “negative emotions such as depression, anxiety and anger have been shown to be associated with increased risk of cardiovascular events and mortality.”

Some, but not all previous studies, have suggested that positive affect is associated with lower risk of disease and improved clinical outcomes, he added.

“This new, large population-based study suggests that positive affect is associated with a reduced risk of coronary heart disease over 10 years independent of other cardiovascular risk factors and independent of depression and other negative affects,” Fonarow said.

“These findings are intriguing. The clinical significance will depend on whether it can be subsequently shown that interventions designed to increase positive affect can lower the risk of cardiovascular disease,” he added.

However, while maintaining a positive affect may be one factor associated with a lower risk of cardiovascular disease, regular exercise, not smoking, a healthy diet and maintaining optimal blood pressure, cholesterol levels and body weight are well-established and essential, Fonarow noted.

SOURCES: Karina Davidson, Ph.D., Herbert Irving Associate Professor of Medicine & Psychiatry, and director, Center for Behavioral Cardiovascular Health, Columbia University Medical Center, New York City; Gregg C. Fonarow, M.D., professor, cardiology, University of California, Los Angeles, and director, Ahmanson-UCLA Cardiomyopathy Center, and co-director, UCLA Preventative Cardiology Program; Feb. 18, 2010, European Heart Journal

From 1990 to 2005, birth weight decreased by 52 grams (1.83 oz) on average. The drop – from 3441 to 3389 grams – leaves the vast majority of babies in the safe range, and the overall health consequences of this development are unclear.

“It is important to study trends in low birth weight over time because an increasing proportion of the smallest babies could lead to increased resource requirements to address health concerns,” Sara Donahue of Boston University, who worked on the study, told Reuters Health.

Small babies (usually defined as lighter than 2500 grams, or 5.5 pounds) may face problems such as low blood sugar, lower body temperatures, or an increase in red blood cells, which can cause the blood to thicken and clot.

To track trends in birth weights, Donahue and her colleagues examined birth records for nearly 37 million newborns in the US, excluding California.

To make sure that the recent weight drop wasn’t related to changes in maternal age or life style, the researchers also analyzed data for half a million young mothers who were deemed to be at low risk of pregnancy complications. For children of these women, it turned out that birth weight decreased even more, going down 79 grams (2.79 oz).

The number of women giving birth to small newborns increased by one percent among the low-risk mothers, but remained stable overall.

By contrast, the number of women giving birth to large newborns (heavier than 4000 grams, or 8 pounds, 13 ounces) fell by 2.2 percent for the low-risk group and by 1.4 percent overall.

Large babies may be difficult to deliver, resulting in harm to the infant or requirement for cesarean section.

The average length of pregnancy decreased during the study period by 2.4 days (a bit less for the low-risk group), which could also have an effect on birth weight.

“Although the consequences of the modest differences over time in birth weight for gestational age that we observed here are uncertain, any underlying reasons for such a decline may themselves directly influence child health,” the authors write in the journal Obstetrics & Gynecology.

So far, the reasons for the weight decline are unknown, and none of the factors examined by the researchers — including maternal age, smoking, and hypertension — could explain the new trend.

SOURCE: Obstetrics & Gynecology, February 2010.