Knowledge Update

​London, April 6 (IANS) The salt levels of oceans on distant Earth-like planets could have a major effect on their climates and may provide more habitable conditions for alien life, says a study involving an Indian-origin scientist.

"The number of planets being discovered outside our solar system is rapidly increasing. Our research helps to answer whether or not these planets could sustain alien life," said David Stevens from Britain's University of East Anglia (UEA). 

"Oceans play a vital role in sustaining life and also have an immense capacity to control climate. But previous studies on ocean circulation on other planets have made the assumption that fundamental ocean properties - such as the salinity and depth of water - would be similar to that on Earth," he added.

Stevens' team used computer models of ocean circulation on exoplanets to see what would happen when their oceans had different salinity levels to Earth. 

The study, published recently in the Proceedings of the National Academy of Sciences, considered oceans with very low salinity (similar to freshwater), salinity similar to the average value of Earth's oceans, and high salinity (similar levels to the Dead Sea).

"On Earth, we have a circulation where warm water moves towards the poles at the surface, before being cooled, then sinking at high latitudes and travelling towards the equator at depth," said Manoj Joshi from UEA's School of Environmental Sciences.

"Our research shows that oceans on other planets with a much higher salinity could circulate in the opposite direction - with polar water flowing towards the equator at the surface, sinking in the tropics and travelling back towards the poles at depth. We also found a similar pattern emerging for freshwater oceans," Joshi added.

"These circulation patterns are the opposite of what happens on Earth, and would result in a dramatic warming in the polar regions. Such a circulation scenario might extend the planet's range of habitability," he noted.

The study assumes significance as until recently computer simulations of habitable climates on Earth-like planets have mainly focused on their atmospheres. But studying their oceans is vital for understanding climate stability and habitability -- as on our own Earth.​

New York, March 31 (IANS) Do you become the "grammar police?" when reading emails? If yes, you could be an introvert, suggests new research that established a link between personality traits and reaction of typos and grammatical errors in emails.

Extroverted people are likely to overlook typos and grammatical errors that would cause introverted people to judge the person who makes such errors more negatively, said the study published in the journal PLOS ONE.

"This is the first study to show that the personality traits of listeners/readers have an effect on the interpretation of language," said the study's lead author Julie Boland, professor of linguistics and psychology at the University of Michigan in the US.

"In this experiment, we examined the social judgments that readers made about the writers," Boland noted. 

Eighty three participants read email responses to an ad for a housemate that either contained no errors or had been altered to include either typos, such as mkae (make) or abuot (about), or grammar errors, such as to/too, it's/its or your/you're. 

They rated the email writers in terms of perceived intelligence, friendliness and other attributes, as well as provided information about themselves.

At the end of the experiment, participants were asked if they noticed any grammatical errors in the responses. If they answered "yes," they indicated how much the errors bothered them.

As expected, participants who reported grammar being important at the beginning of the experiment were more likely to be bothered by grammatical errors at the end, study co-author Robin Queen from the University of Michigan said..

In addition, less agreeable people are more sensitive to grammatical errors, while more conscientious and less open people are sensitive to typos, the researchers said.​

London, April 5 (IANS) In older adults, especially women, higher dietary calcium intake may lower the risk of cardiovascular disease, but not of stroke and fracture, new research suggests.

"The role of dietary calcium intake in cardiovascular disease, stroke and fracture is controversial. We aimed to evaluate whether high dietary calcium intake increases the risk of CVD, stroke and fracture in a population with low calcium intake," said lead study author Sung Hye Kong from Seoul National University Hospital in Seoul, South Korea.

Researchers conducted their study among individuals in Korea's ongoing prospective community-based Ansung and Ansan Cohort Study that began in 2001.

The authors performed their analyses in 2,199 men and 2,704 women over 50 years of age without previous cardiovascular disease and stroke.

The participants in the study reported their dietary food intake in periodic food frequency questionnaires.

Cardiovascular disease, stroke and fractures were recorded during interviews and examinations every two years.

The findings suggest, in older women in this population with low dietary calcium intake, higher dietary calcium intake was significantly associated with decreased risk of cardiovascular disease, but not significantly associated with risk of stroke and fracture.​

​New York, April 5 (IANS) Depression is a known risk factor for cardiovascular disease. However, a team of US researchers has found that effectively treating depression can reduce a person's risk of cardiovascular problems - stroke, heart failure, heart attack or death.

The researchers found effective treatment for depression can reduce a patient's heart risks to the same level as those who never had short-term depression.

"Our study shows that prompt, effective treatment of depression appears to improve the risk of poor heart health," said Heidi May from Intermountain Medical Center Heart Institute in US.

"With the help of past research, we know depression affects long-term cardiovascular risks, but knowing that alleviating the symptoms of depression reduces a person's risk of heart disease in the short term, too, can help care providers and patients commit more fully to treating the symptoms of depression," she added.

"The key conclusion of our study is: If depression isn't treated, the risk of cardiovascular complications increases significantly," May stated.

The team compiled information from 7,550 participants, who completed at least two depression questionnaires over the course of one to two years.

They were categorised based on the results of their survey as never depressed, no longer depressed, remained depressed, or became depressed.

Following each patient's completion of the last questionnaire, patients were followed to see if they had any major cardiovascular problems.

The findings suggested that 4.6 percent of patients who were no longer depressed had a similar occurrence of major cardiovascular complications as those who had no depression at all (4.8 percent).

The results indicated that changes in depression symptoms may also cause immediate physiological changes in the body, which in turn cause major cardiovascular problems to occur in the short term, but future studies are needed to further answer these questions.​

​London, April 5 (IANS) The North Atlantic Ocean played a key role in the last climate transition, says a study providing valuable insights into why large continental ice-sheets first grew in North America and Scandinavia some 2.7 million years ago.

An international team of researchers measured the composition of isotopes of the chemical element neodymium that can be found in fish teeth preserved in a North Atlantic marine core to track the origin of deep waters bathing the bottom of the ocean during the climate transition that took place in the late Pliocene Epoch era.

Contrary to previous assertions, they found that the first of these glacial events in the northern hemisphere was associated with major expansions of carbon-rich southern-sourced deep waters into the northwestern Atlantic abyss, over one million years earlier than previously thought.

The study, published recently in the journal Nature Geoscience, said that three of the largest glacial cycles between 2.5 and 2.7 million years ago appear to be associated with southern-sourced water incursions into the deep Atlantic that were as significant as those documented for the last glacial maximum.

"We could not have made these new findings with confidence using only a classic method for tracing watermass origin such as carbon isotopes," said Ian Bailey from the University of Exeter in Britain.

"But when we combined such data with an alternative novel proxy such as neodymium isotopes, we were able to reveal a dramatically new picture of watermass mixing in the deep North Atlantic during late Pliocene glacial intensification," Bailey added.

It has long been argued that changes in North Atlantic circulation played a leading role in driving late Pliocene northern hemisphere glaciation because of its capacity to modulate the transfer of heat and moisture from the tropics to the poles.

"Our findings suggest, though, that the North Atlantic Ocean was not a driving factor in this transition, but, through storage of atmospheric carbon dioxide in the deep Atlantic, it operated as a positive feedback that helped to usher in glaciation at this time," Bailey said.

"What we've done is document a process which is thought to be special to the largest and longest glacial cycles of the past one million years, but we have shown that it has been occurring ever since large continental ice-sheets formed in the Northern Hemisphere," he added.​

​New York, April 5 (IANS) Some landslides travel much greater distances than scientists would normally expect. Now a team of researchers has come out with an explanation for this phenomenon using a sophisticated computer model.

A team of geoscientists from Brown University, Purdue University and the University of Southern California in the US has found that vibrations generated by large slides can cause tonnes of rock to flow like a fluid, enabling the rocks to rumble across vast distances.

According to the study's lead author Brandon Johnson, an assistant professor at Brown, the "runout" distance of most landslides -- the distance debris travels once it reaches flat land -- tends to be about twice the vertical distance that the slide falls. 

So if a slide breaks loose a half-mile vertically up a slope, it can be expected to run out about a mile.

But "long-runout" landslides, also known as sturzstroms, are known to travel horizontal distances 10-20 times further than they fall. 

"There are a few examples where these slides have devastated towns, even when they were located at seemingly safe distances from a mountainside," Johnson said. 

Scientists developed several hypotheses to explain long-runout slides. But none could convincingly explain their behaviour. 

In 1995, Charles Campbell from the University of Southern California created a computer model that was able to replicate the behaviour of long-runout slides using only the dynamic interactions between rocks.

However, due to the limitations of computers at the time, he was unable to determine what mechanism was responsible for the behaviour.

"The model showed that there was something about rocks, when you get a lot of them together, that causes them to slide out further than you expect," Johnson said. "But it didn't tell us what was actually happening to give us this lower friction."

For this new study, described in the Journal of Geophysical Research: Earth Surface, Johnson was able to resurrect that model, tweak it a bit, and run it on a modern workstation to capture the dynamics in finer detail. 

The new model showed that, indeed, vibrations do reduce the effective friction acting on the slide.

The amount of friction acting on a slide depends in part on gravity pulling it downward. 

The same gravitational force that accelerates the slide as it moves downslope tends to slow it down when it reaches flat land. But the model showed that vibrational waves counteract the gravitational force for brief moments. 

The rocks tend to slide more when the vibration reduces the friction effect of the gravitational force. Because the vibrational waves affect different rocks in the slide at different times, the entire slide tends to move more like a fluid.​

​New York, April 5 (IANS) Researchers have identified a pattern of brain activity that may be a sign of memory problems in people with schizophrenia.

The findings proved that memory problem in schizophrenia stems from disruptions in the brain's dorsolateral prefrontal cortex (DLPFC), long hypothesised by scientists. 

This area of the brain plays a key role in working memory -- the system for temporarily storing and managing information required to carry out complex cognitive tasks. 

"Our findings provide evidence that the DLPFC is compromised in patients with schizophrenia," said first author Jared X. Van Snellenberg, assistant professor at Columbia University in US. 

In the study, published in the journal Biological Psychiatry, 45 healthy controls and 51 schizophrenia patients, including 21 who were not taking antipsychotic medications, were given the eight-level memory test while undergoing fMRI imaging. 

The healthy controls demonstrated a gradual increase in DLPFC activation, followed by a gradual decrease in activation, as the task got harder. 

But in both medicated and unmedicated schizophrenia patients, the overall response was significantly weaker, with the weakest response occurring in those who had the most difficulty with the memory task.

While schizophrenia typically causes hallucinations and delusions, many people with the disorder also have cognitive deficits, including problems with short- and long-term memory, which is one of the most devastating symptoms.

"Of all the symptoms linked to schizophrenia, memory issues may have the greatest impact on quality of life, as they can make it difficult to hold down a job and maintain social relationships," Van Snellenberg stated.​

​New York, April 5 (IANS) Anti-oxidants are likely to be an effective method of treatment for elderly patients suffering from melanoma, finds a new study.

It also identified that the older tumour cells in the worst form of skin cancer behave differently than the younger tumour cells.

The research showed that changes in the microenvironment make these older tumours cells to spread more and makes them more resistant to treatment with targeted therapies.

"It's fascinating to see that the microenvironment can have such a profound effect on both metastasis, and response to a therapy that is specifically targeted to a mutation in a gene," said lead author Ashani Weeraratna, associate professor at The Wistar Institute in US.

However, the findings revealed that antioxidant N-acetylcysteine (NAC) killed melanoma cells in aged dermal fibroblasts - the cells found in the skin.

Cells found in the skin help the skin recovery from injuries, and can contribute to the growth and invasion of melanoma cells. 

For the study, published in the journal Nature, the researchers used dermal fibroblasts from healthy donors 25-35 years of age or from donors 55-65 years of age.

They determined that a secreted factor sFRP2 was present in aging cells, which regulates beta-catenin -- a protein that normally blocks the invasion of melanoma cells. 

The age-induced loss of beta-catenin renders melanoma cells less capable of dealing with reactive oxygen species (ROS), resulting in a genetically unstable tumour.

The increased activity of ROS and decreased levels of beta-catenin all contribute to the increased resistance of melanoma to treatment with drugs that inhibit a gene, BRAF, mutated in approximately half of all cases of the skin cancer. 

"Our findings highlight how vital it is to treat that melanoma in an age-appropriate manner," said one of the researchers Amanpreet Kaur, a graduate student at The Wistar Institute. 

​New York, April 5 (IANS) Electrical stimulation of a deep, middle brain structure blocks pain signals at the spinal cord level without drug intervention, finds a new study.

"This is the first study to use a wireless electrical device to alleviate pain by directly stimulating the ventral tegmental area of the brain," said Yuan Bo Peng, a psychology professor at the University of Texas in Arlington.

"While still under laboratory testing, this new method does provide hope that in the future we will be able to alleviate chronic pain without the side effects of medications," Peng added.

Peng and J.C. Chiao, an electrical engineering professor, detail their discoveries in the neuroscience journal Experimental Brain Research.

In their experiments, the researchers used their patented custom-designed wireless device to demonstrate that stimulation of the ventral tegmental area reduced the sensation of pain. They also confirmed that this stimulation reduced pain signals in the spinal cord, effectively blocking the perception of pain.

The process also triggered the release of beneficial dopamine, which may reduce the emotional distress associated with long-term pain, researchers said.

"Until this study, the ventral segmental area of the brain was studied more for its key role in positive reinforcement, reward and drug abuse," Peng said. "We have now confirmed that stimulation of this area of the brain can also be an analgesic tool," he added.​

​New York, April 5 (IANS) Scientists have proposed a new concept that could make it possible to generate electricity from coal with much greater efficiency -- possibly reaching as much as twice the fuel-to-electricity efficiency of today's conventional coal plants.

The concept, proposed by doctoral student Katherine Ong and professor Ahmed Ghoniem at the Massachusetts Institute of Technology (MIT), combines into a single system two well-known technologies -- coal gasification and fuel cells.

Coal gasification is a way of extracting burnable gaseous fuel from pulverised coal, rather than burning the coal itself, while fuel cells produce electricity from a gaseous fuel by passing it through a battery-like system where the fuel reacts electrochemically with oxygen from the air.

The attraction of combining these two systems, explained in the Journal of Power Sources, is that both processes operate at similarly high temperatures of 800 degrees Celsius or more. 

Combining them in a single plant would thus allow the two components to exchange heat with minimal energy losses. In fact, the fuel cell would generate enough heat to sustain the gasification part of the process, Ong said, eliminating the need for a separate heating system, which is usually provided by burning a portion of the coal.

Coal gasification, by itself, works at a lower temperature than combustion and "is more efficient than burning," Ong said. 

First, the coal is pulverised to a powder, which is then heated in a flow of hot steam, somewhat like popcorn kernels heated in an air-popper. The heat leads to chemical reactions that release gases from the coal particles -- mainly carbon monoxide and hydrogen, both of which can produce electricity in a solid oxide fuel cell.

In the combined system, these gases would then be piped from the gasifier to a separate fuel cell stack, or ultimately, the fuel cell system could be installed in the same chamber as the gasifier so that the hot gas flows straight into the cell. 

In the fuel cell, a membrane separates the carbon monoxide and hydrogen from the oxygen, promoting an electrochemical reaction that generates electricity without burning the fuel.

Because there is no burning involved, the system produces less ash and other air pollutants than would be generated by combustion, the MIT researchers said.

It does produce carbon dioxide, but this is in a pure, uncontaminated stream and not mixed with air as in a conventional coal-burning plant. That would make it much easier to carry out carbon capture and sequestration (CCS) -- that is, capturing the output gas and burying it underground or disposing of it some other way -- to eliminate or drastically reduce the greenhouse gas emissions. 

In conventional plants, nitrogen from the air must be removed from the stream of gas in order to carry out CCS.

One of the big questions answered by this new study, which used simulations rather than lab experiments, was whether the process would work more efficiently using steam or carbon dioxide to react with the particles of coal. 

Both methods have been widely used, but most previous attempts to study gasification in combination with fuel cells chose the carbon dioxide option. This new study demonstrates that the system produces two to three times as much power output when steam is used instead.​