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Knowledge Update

Obese? You may become more forgetful

London, Feb 27 (IANS) If you are obese, you are at risk of physical and psychological health problems such as diabetes, heart disease, depression and anxiety.
But, your high body mass index (BMI) is also likely to affect your episodic memory -- the ability to recall past events, warns a new study.A higher BMI was previously found to affect the structural and functional changes in the brain. But, it may also be accompanied by a reduced ability to form and/or retrieve episodic memories and also affect brain's ability to perform certain cognitive tasks optimally, suggested the researchers.The results showed that obesity might also impair an individual's ability to use memory to help regulate consumption. 
In other words, it is possible that becoming overweight may make it harder for an individual to keep track of what and how much he or she has eaten, potentially making one more likely to overeat."The possibility that there may be episodic memory deficits in overweight individuals is of concern, especially given the growing evidence that episodic memory may have a considerable influence on feeding behaviour and appetite regulation," said Lucy Cheke, lecturer at the University.However, she cautioned that not all overweight people are necessarily forgetful.But if the results are generalised to memory in everyday life, then it could be that overweight people are less able to vividly relive details of past events -- such as their past meals, the researchers explained in the study published in The Quarterly Journal of Experimental Psychology.
Obesity has been previously, linked with dysfunction of the hippocampus, an area of the brain involved in memory and learning, and of the frontal lobe, the part of the brain involved in decision-making, problem solving and emotions.Around 60 percent of adults in Britain are overweight or obese: this number is predicted to rise to approximately 70 percent by 2034, the researchers noted. "Understanding what drives our consumption and how we instinctively regulate our eating behaviour is becoming more and more important given the rise of obesity in society," Cheke added. 
The researchers tested 50 participants aged 18-35, with body mass indexes (BMIs) ranging from 18 through to 51 -- a BMI of 18-25 is considered healthy, 25-30 overweight, and over 30 obese. The participants took part in a memory test known as the 'Treasure-Hunt Task', where they were asked to hide items around complex scenes (for example, a desert with palm trees) across two 'days'.They were then asked to remember which items they had hidden, where they had hidden them, and when they were hidden.
Overall, the team found an association between higher BMI and poor performance on the tasks.​

Keep your mind active to keep Alzheimer's at bay

Keep your mind active to keep Alzheimer's at bay

Too much exercise may be bad for your heart

Toronto, Feb 25 (IANS) Just as most therapies have a dose-response relationship whereby benefits diminish at high doses and the risk of adverse events increases, high level of intense exercise may also be bad for the heart, suggests a new study.

The researchers reviewed studies that looked into the relationship between exercise and heart problems and found that there is growing evidence that high levels of intense exercise may be cardiotoxic and promote permanent structural changes in the heart.

There is already fairly compelling evidence supporting the association between long-term sports practice and increased prevalence of atrial fibrillation -- abnormal heart rhythm characterised by rapid and irregular beating.

"Much of the discussion regarding the relative risks and benefits of long-term endurance sports training is hijacked by definitive media-grabbing statements, which has fuelled an environment in which one may be criticized for even questioning the benefits of exercise," explained study author Andre La Gerche from the Baker IDI Heart and Diabetes Institute, Melbourne, Australia. 

"This paper discusses the often questionable, incomplete, and controversial science behind the emerging concern that high levels of intense exercise may be associated with some adverse health effects," La Gerche noted.

The study was published in the Canadian Journal of Cardiology.

"The answers regarding the healthfulness of 'extreme' exercise are not complete and there are valid questions being raised," La Gerche said. 

"Given that this is a concern that affects such a large proportion of society, it is something that deserves investment. The lack of large prospective studies of persons engaged in high-volume and high-intensity exercise represents the biggest deficiency in the literature to date, and, although such work presents a logistical and financial challenge, many questions will remain controversies until such data emege," La Gerche observed.​

High-salt diet may lead to liver damage

New York, Feb 25 (IANS) While high salt intake has been known to cause high blood pressure and other side effects, researchers have now found that a high-salt diet might also contribute to liver damage in adults and developing embryos.
"This study demonstrates that high salt exposure in mice (four percent sodium chloride or NaCl in drinking water) and chick embryo could lead to derangement of the hepatic cords and liver fibrosis,” the researchers said.Fibrosis is the first stage of liver scarring.The findings by Xuesong Yang from Jinan University, Guangzhou, China, and colleagues were published in the Journal of Agricultural and Food Chemistry.Our bodies need a small amount of salt -- the US government recommends one teaspoon per day if you are a healthy adult.
Among other functions, the sodium ions from the savoury mineral help regulate water movement within the body and conduct nerve impulses.But too much of salt can be dangerous and in this study the researchers wanted to explore its potential effect at a cellular level.The researchers gave adult mice a high-salt diet and exposed chick embryos to a briny environment. Excessive sodium was associated with a number of changes in the animals' livers, including oddly shaped cells, an increase in cell death and a decrease in cell proliferation, which can contribute to the development of fibrosis. 
"The pathological mechanism may be the result from an imbalance between oxidative stress and the antioxidant system," the researchers explained.
On a positive note, the researchers found that treating damaged cells with vitamin C appeared to partially counter the ill effects of excess salt.​

Nature-inspired system to pull water from thin air

Washington, Feb 25 (IANS) Inspired by a desert beetle, cactus and pitcher plant, researchers from Harvard University have designed a new material to collect water droplets from thin air that can one day help fill the drying reservoirs on our planet.

The team from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering drew inspiration from these organisms to develop a better way to promote and transport condensed water droplets.

“Our research shows that a complex bio-inspired approach, in which we marry multiple biological species to come up with non-trivial designs for highly efficient materials with unprecedented properties, is a new, promising direction in biomimetics,” explained Joanna Aizenberg, the Amy Smith Berylson professor of materials science at SEAS.

Organisms such as cacti and desert beetles can survive in arid environments because they have evolved mechanisms to collect water from thin air. 

The Namib desert beetle, for example, collects water droplets on the bumps of its shell while V-shaped cactus spines guide droplets to the plant's body.

The new system, described in the journal Nature, is inspired by the bumpy shell of desert beetles, the asymmetric structure of cactus spines and slippery surfaces of pitcher plants. 

The material harnesses the power of these natural systems, plus Slippery Liquid-Infused Porous Surfaces technology (SLIPS) developed in Aizenberg's lab, to collect and direct the flow of condensed water droplets.

This approach is promising not only for harvesting water but also for industrial heat exchangers.

Thermal power plants, for example, rely on condensers to quickly convert steam to liquid water.

“This design could help speed up that process and even allow for operation at a higher temperature, significantly improving the overall energy efficiency,” added Philseok Kim, vice president of technology at SEAS spin-off SLIPS Technologies, Inc.

The major challenges in harvesting atmospheric water are controlling the size of the droplets, speed in which they form and the direction in which they flow.

“This research is an exciting first step towards developing a passive system that can efficiently collect water and guide it to a reservoir,” Kim noted.​

World's 33 major deltas are shrinking: Study

New York, Feb 24 (IANS) The world's 33 major deltas are sinking and the vast majority of those have experienced flooding in recent years, primarily as a result of human activity, says a new study.
Some 500 million people live on river deltas around the world, a number that continues to climb as the population increases, the study pointed out.
"These deltas are starved of the sediments they need for stability because of upstream dams that trap the material," said researcher James Syvitski, professor in geological sciences at the University of Colorado Boulder in the US.
"We are seeing coastal erosion increasing in many places across the planet," Syvitski noted.
Human effects on river deltas range from engineering tributaries and river channels, extracting groundwater and fossil fuels, trapping sediments behind dams, reducing peak flows of rivers and varied agricultural practices, he said.The findings were presented at the 2016 Ocean Sciences meeting held in New Orleans, US.River deltas are land areas created by sediment that collects at the mouths of rivers as they enter slow moving or standing water like oceans and estuaries. 
"Deltas are sinking at a much greater rate than sea levels are rising," Syvitski said.
The findings are based on international Community Surface Dynamics Modeling System (CSDMS) - global, interdisciplinary programme involving hundreds of researchers and students in 500 institutes in 68 countries.
For the study, the researchers looked into the degradation of major river deltas in the world, from Yellow River in China to the Mississippi River in Louisiana, US.The two major river deltas in the United States are the Mississippi River Delta in Louisiana and the Sacramento-San Joaquin River Delta in California. 
While the Sacramento-Joaquin Delta has significant issues with agricultural, industrial and urban pollution and subsidence, things are more dire in the Mississippi River Delta, where a football field-sized chunk of wetlands disappears every hour, Syvitski said. 
There are more than 40,000 dams 20 feet or higher on the Mississippi River system, he noted.​