Knowledge Update

​London, April 3 (IANS) Light can put active materials into motion and humans can use this movement for development of new programmable materials which can be used for environment protection and deliver pharmaceutical substances, a study said.

Light of a certain wavelength can be used to put so-called active materials into motion and control their movement.

In future, this discovery can become significant in widely different areas such as environmental protection, medicine and the development of new materials that can be programmed.

Joakim Stenhammar from Lund University in Sweden led a study in which his team of international researchers developed a model in which patterns of light control the movement of active particles.

The results of the study were published in journal Science Advances.

The light makes synthetically produced particles as well as microorganisms, such as bacteria and algae, spontaneously form into something that can be compared to a pump.

The light makes active particles construct their own pump to move themselves around. By adjusting the light, it is possible to steer the particles in a different direction.

"Our strategy has the potential of developing into an inexpensive and simple way to pump and control bacteria and other active materials," Stenhammar said.

One possible application is to have active particles deliver pharmaceutical substances or nanosensors to specific parts of the body. Within environmental science, the active particles could be compared to targeted robots that can locate oil spills and then release chemicals to break down any contamination.

"Our results show how the properties of active particles can be used to design new materials that we are unable to produce today," Stenhammar added.​

​London, April 3 (IANS) The Moon plays a major role in maintaining the Earth's magnetic field, say researchers, adding that the lunar action, overlooked till now, is thought to have kept the geodynamo active.

The Earth's magnetic field permanently protects us from the charged particles and radiation that originate in the Sun.

This shield is produced by the geodynamo, the rapid motion of huge quantities of liquid iron alloy in the Earth's outer core.

To maintain this magnetic field till the present day, the classical model required the Earth's core to have cooled by around 3,000 degrees Celsius over the past 4.3 billion years.

Now, a team of researchers from the National Centre for Scientific Research and Universite Blaise Pascal in France suggests that on the contrary, its temperature has fallen by only 300 degrees Celsius.

According to the researchers, the Earth has a slightly flattened shape and rotates about an inclined axis that wobbles around the poles.

The Earth continuously receives 3,700 billion watts of power through the transfer of the gravitational and rotational energy of the Earth-Moon-Sun system and over 1,000 billion watts is thought to be available to bring about this type of motion in the outer core.

This energy is enough to generate the Earth's magnetic field, which together with the Moon resolves the major paradox in the classical theory.

The effect of gravitational forces on a planet's magnetic field has already been well documented for two of Jupiter's moons, Io and Europa, and for a number of exoplanets.

This new model shows that the Moon's effect on the Earth goes well beyond merely causing tides.

The work was published in the journal Earth and Planetary Science Letters.​

​New York, April 4 (IANS) Testosterone therapy can help the elderly - suffering from low testosterone levels and pre-existing heart condition - reduce their risks of stroke, heart attacks and death, researchers report.

The study from the Intermountain Medical Center Heart Institute in Salt Lake City showed that patients who received testosterone as part of their follow-up treatment fared much better than patients who didn't.

Non-testosterone-therapy patients were 80 percent more likely to suffer an adverse event.

"The study shows that using testosterone replacement therapy to increase testosterone to normal levels in androgen-deficient men doesn't increase their risk of a serious heart attack or stroke,” said cardiologist Brent Muhlestein.

That was the case even in the highest-risk men -- those with known pre-existing heart disease.

The research team studied 755 male patients between the ages of 58 and 78 at Intermountain Medical Center who had severe coronary artery disease.

They were split into three different groups which received varied doses of testosterone administered either by injection or gel.

After one year, 64 patients who weren't taking testosterone supplements suffered major adverse cardiovascular events while only 12 who were taking medium doses of testosterone and nine who were taking high doses did.

After three years, 125 non-testosterone-therapy patients suffered major adverse cardiovascular events, while only 38 medium-dose and 22 high-dose patients did.

“Although this is an observational study, it does, however, substantiate the need for a randomised clinical trial that can confirm or refute the results,” Muhlestein noted.

The team presented the results at the American College of Cardiology's 65th annual scientific session in Chicago last weekend.​

​New York, April 4 (IANS) Companies appear to structure compensation contracts and incentive pay based on seniors' personality traits and not just firm characteristics, a team of US researchers, including an Indian-origin scientist, has found.

Companies offer incentive-heavy compensation contracts to overconfident CEOs to "exploit" their positively biased views of the firms' prospects, the researchers noted.

"There are divergent views on the use of options and stock in CEO compensation contracts: Do they appropriately incentivise managers and enhance shareholder value and if so, why is there much variation in their use across firms?" said Vikram Nanda from Naveen Jindal School of Management in the US.

The notion is that if managers and shareholders -- represented by the board -- have a different take on a firm's prospects and CEO talent, there will be greater use of incentive pay that the managers value highly but the board regards as less costly.

"When you think about incentive contracts, you don't usually think about the personality of the individual being a factor in the contract," Nanda added in the paper published in the Journal of Financial Economics. 

Using the compensation data of CEOs between 1992 and 2011, the researchers identified managers who were exhibiting behaviour that was overconfident compared to other CEOs. 

"You don't usually hear about how two profit-sharing agreements are going to look different because the personalities and the beliefs of the individuals are coming into play," Nanda stated.

The team conducted empirical tests to explore the relationship between CEO overconfidence and incentive compensation.

The researchers found that CEO overconfidence increases the proportions of total compensation that comes from both option grants and equity grants, compared to other executives.

Overconfident CEOs receive even greater option and equity intensity in innovative and risky firms.

"Overconfident CEOs are prone to overestimate returns to investments and underestimate risks. They may use extremely positive words in the media or tend to invest more than a typical manager in the industry," Nanda stated.​

New York, April 1 (IANS) Asia, the continent that houses roughly half the world's population, will face a "high risk of severe water stress" by 2050 if the current environmental, economical and population growth persists, warns a new study.

The study points out that water shortages are not simply the results of climate change and environmental stress. 

"It's not just a climate change issue. We simply cannot ignore that economic and population growth in society can have a very strong influence on our demand for resources and how we manage them," said one of the researchers Adam Schlosser, a senior research scientist at Massachusetts Institute of Technology (MIT) in US.

"And climate, on top of that, can lead to substantial magnifications to those stresses," Schlosser added.

The findings, published in the journal PLOS One, showed that the median amounts of projected growth and climate change in the next 35 years in Asia would lead to about 1 billion more people becoming "water-stressed" compared to the present time.

To conduct the study, the scientists built upon an existing model developed previously at MIT, the Integrated Global Systems Model (IGSM), which contains probabilistic projections of population growth, economic expansion, climate, and carbon emissions from human activity. 

They then linked the IGSM model to detailed models of water use for a large portion of Asia encompassing China, India, and many smaller nations.

The scientists then ran an extensive series of repeated projections using varying conditions. 

In what they call the "just growth" scenario, they held climate conditions constant and evaluated the effects of economic and population growth on the water supply. 

In an alternate "just climate" scenario, the scientists held growth constant and evaluated climate-change effects alone. And in a "climate and growth" scenario, they studied the impact of rising economic activity, growing populations, and climate change.

The study gave the researchers a "unique ability to tease out the human (economic) and environmental" factors leading to water shortages and to assess their relative significance, Schlosser said.

The IGSM model also allowed the team to look at how, under the same variables, scenarios change according to countries. This is particularly useful to come up with country-specific strategies, in order to avoid water stress.

"For China, it looks like industrial growth (has the greatest impact) as people get wealthier. In India, population growth has a huge effect. It varies by region," explained lead author Charle Fant, researcher at MIT.

Other variables, such as water supply networks into and out of the different areas, and the way population is distributed around said supplies should be examined, the researchers said. 

"We are assessing the extent to which climate mitigation and adaptation practices - such as more efficient irrigation technologies - can reduce the future risk of nations under high water stress," Schlosser said.​

Washington, April 1 (IANS) Delving deep into the heart of our Milky Way galaxy, NASA's Hubble Space Telescope has revealed a rich tapestry of more than half a million stars at its core.

Except for a few blue foreground stars, the stars are part of the Milky Way's nuclear star cluster - the most massive and densest star cluster in our galaxy. 

So packed with stars, it is equivalent to having a million suns crammed between us and our closest stellar neighbour Alpha Centauri. 

At the very hub of our galaxy, this star cluster surrounds the Milky Way's central supermassive black hole which is about four million times the mass of our sun.

Astronomers used Hubble's infrared vision to pierce through the dust in the disk of our galaxy that obscures the star cluster. 

Hubble's sharp vision allowed astronomers to measure the movements of the stars over four years. 

Using this information, scientists were able to infer important properties such as the mass and structure of the nuclear star cluster. 

The motion of the stars may also offer a glimpse into how the star cluster was formed -- whether it was built up over time by globular star clusters that happen to fall into the galaxy's centre, or from gas spiraling in from the Milky Way's disk to form stars at the core.

The picture, spanning 50 light-years across, is a mosaic stitched from nine separate images from Hubble's Wide Field Camera 3. 

The centre of the Milky Way is located 27,000 light-years away. 

Astronomers estimate that about 10 million stars in this cluster are too faint to be captured in this image.​

​London, April 1 (IANS) Forgetting can be the result of an active deletion process in the brain rather than a failure to remember -- a mechanism that helps us adapt our behaviour according to the surroundings, says a new study.

The findings could point towards new ways of tackling memory loss associated with conditions such as Alzheimer's disease and other types of dementia.

"Our study looks at the biological processes that happen in the brain when we forget something,” said Oliver Hardt from University of Edinburgh in Scotland.

"The next step is to work out why some memories survive whilst others are erased. If we can understand how these memories are protected, it could one-day lead to new therapies that stop or slow pathological memory loss," Hardt said.

The findings were published in The Journal of Neuroscience.

The study conducted in rats could also help scientists to understand why some unwanted memories are so long-lasting - such as those of people suffering from post-traumatic stress disorders.

Memories are maintained by chemical signalling between brain cells that relies on specialised receptors called AMPA receptors. 

The more AMPA receptors there are on the surface where brain cells connect, the stronger the memory.

The team found that the process of actively wiping memories happens when brain cells remove AMPA receptors from the connections between brain cells.

Over time, if the memory is not recalled, the AMPA receptors may fall in number and the memory is gradually erased.

Blocking the removal of AMPA receptors with a drug that keeps them at the surface of the cell stopped the natural forgetting of memories, the study found.​

​New York, March 29 (IANS) Patients with skin infections are less likely to take all their prescribed antibiotic doses after leaving the hospital, resulting in new infection or needing additional treatment for the existing skin infection, says a study.

The researchers found that patients with S. aureus skin and soft tissue infections took, on average, just 57 percent of their prescribed antibiotic doses after leaving the hospital.

"These findings suggest that we need better methods to have patients receive antibiotics for skin infections, such as counselling them on the importance of adhering to the medication dosing or by using newer antibiotics that require only once-weekly dosing," said lead researcher Loren Miller from Harbor-UCLA Medical Centre in California, US.

The study, published in the journal Antimicrobial Agents and Chemotherapy, followed 188 patients who had been hospitalised and suffered S. aureus associated skin and soft tissue infections. 

The researchers measured antibiotic dosing by using medication containers fitted with electronic caps that reported when the patient opened the antibiotic container. 

By using this measurement system, the researchers found a large discrepancy in patient reports and the electronic measurement. 

Patients reported taking, on average, 96 percent of their medication, or nearly twice the 57 percent reported by the electronic caps.

The researchers were able to obtain complete records on 87 out of the 188 patients. Of the 87 patients, 40 needed additional treatment within 30 days of leaving the hospital. They had a new skin infection, required incision and drainage of their infections or new antibiotics.​

New York, March 29 (IANS) The formation of a distinct pattern of sea surface temperatures in the middle of the North Pacific Ocean can predict an increased chance of summer heat waves in the eastern half of the US up to 50 days in advance, say researchers.

The scientists believe that the new technique could improve existing seasonal forecasts, which do not focus on predicting daily extremes.

"Summertime heat waves are among the deadliest weather events, and can have big effects on farming, energy use and other critical aspects of society," said lead author Karen McKinnon from US National Centre for Atmospheric Research (NCAR) in Colorado, US.

"If we can give city planners and farmers a heads-up that extreme heat is on the way, we might be able to avoid some of the worst consequences," McKinnon noted.

The pattern that the researchers discovered is a contrast of warmer-than-average water coming up against cooler-than-average seas. 

When it appears, the odds that extreme heat will strike during a particular week -- or even on a particular day -- can more than triple, depending on how well-formed the pattern is, the study said.

The findings were published in the journal Nature Geoscience. 

For the study, the US scientists divided the country into regions that tend to experience extreme heat at the same time. 

They then focused on the largest of the resulting blocks: a swath that stretches across much of the Midwest and up the East Coast, encompassing important agricultural areas and heavily populated cities.

The researchers looked for a relationship between global sea surface temperature anomalies -- waters warmer or cooler than average -- and extreme heat in the eastern half of the US.

A pattern popped out in the middle of the Pacific, above a point roughly 20 degrees north latitude. The scientists could find the particular configuration of ocean water temperatures, which they named the Pacific Extreme Pattern, not only when the eastern US was already hot, but also in advance of that heat.

"Whatever mechanisms ultimately lead to the heat wave also leave a fingerprint of sea surface temperature anomalies behind," McKinnon said.​

​London, March 29 (IANS) In a first, researchers in Scotland are using smartphone-based technology to find the reason behind plummeting numbers of harbour seals in the country.

Part of a three-year study by researchers at Sea Mammal Research Unit (SMRU) at University of St Andrews in Scotland, the smartphone-based technology is being used to monitor the well-being of marine mammals, The National reported.

"Over the last 15 years, many of the harbour seal populations in the Northern Isles and on the north and east coasts of Scotland have been declining. Marine data collected during this project on Orkney will help to assess the causes, management and mitigation options in relation to the harbour seals' decline and to prioritise future research directions," Bernie McConnell, SMRU's deputy director, was quoted as saying. 

For the study, marine telemetry tags will be attached to the fur at the back of the heads of a number of harbour seals in Orkney Archipelago of Scotland. 

Small and light, the tags work like smartphones, sending information back to scientists and will eventually drop off when the seal moults, the report explained.

The study is being carried out at the request of the Scottish Government and Scottish Natural Heritage after concerns were raised about the survival of harbour seals in the country.

"This exciting, collaborative study is vital to help us to better understand the drivers of population change in Scottish harbour seals, and to evaluate the potential conservation and management options open to us," professor John Baxter from Scottish Natural Heritage was quoted as saying.

Harbour seals - one of two seal species in Britain - have declined by up to 90 percent in some areas in and around the north and east coast of Scotland, including Orkney, since 2000.​