Knowledge Update

​Washington, Sep 16 (IANS) Lakes and snowmelt-fed streams on Mars formed much later than previously thought possible, new research has found.

The recently discovered lakes and streams appeared roughly a billion years after a well-documented, earlier era of wet conditions on ancient Mars, the study said. 

These results provide insight into the climate history of the Red Planet and suggest the surface conditions at this later time may also have been suitable for microbial life.

"We discovered valleys that carried water into lake basins," said Sharon Wilson of the Smithsonian Institution, Washington, and the University of Virginia, Charlottesville. 

"Several lake basins filled and overflowed, indicating there was a considerable amount of water on the landscape during this time," Wilson noted.

Wilson and colleagues found evidence of these features in Mars' northern Arabia Terra region by analysing images from the Context Camera and High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter and additional data from NASA's Mars Global Surveyor and the European Space Agency's Mars Express.

To bracket the time period when the fresh shallow valleys in Arabia Terra formed, scientists started with age estimates for 22 impact craters in the area. 

They assessed whether or not the valleys carved into the blankets of surrounding debris ejected from the craters, as an indicator of whether the valleys are older or younger than the craters. 

They concluded that this fairly wet period on Mars likely occurred between two and three billion years ago, long after it is generally thought that most of Mars' original atmosphere had been lost and most of the remaining water on the planet had frozen.

"A key goal for Mars exploration is to understand when and where liquid water was present in sufficient volume to alter the Martian surface and perhaps provide habitable environments," Mars Reconnaissance Orbiter Project Scientist Rich Zurek of NASA's Jet Propulsion Laboratory, Pasadena, California, said.

"This paper presents evidence for episodes of water modifying the surface on early Mars for possibly several hundred million years later than previously thought, with some implication that the water was emplaced by snow, not rain," Zurek said.

The findings were reported in the Journal of Geophysical Research, Planets.

New York, Sep 16 (IANS) Children differ substantially in their mathematical abilities. But, some may remain persistently bad at addition or subtraction as a result of abnormalities in the brain areas supporting procedural memory, a study that developed a theory of how developmental "math disability" occurs has revealed.

Procedural memory is a learning and memory system that is crucial for the automatisation of non-conscious skills, such as driving or grammar and depends on a network of brain structures, including the basal ganglia and regions in the frontal and parietal lobes, the study said.

"Various domains, including math, reading, and language, seems to depend on both procedural as well as declarative memory -- where conscious knowledge is learned," said Michael T. Ullman, Professor at the Georgetown University in the US.

"However, for some children with math disability, procedural memory may be dysfunctioned, so math skills may not get automatised," added lead author Tanya M. Evans, postdoctoral student at the Stanford University in the US. 

In fact, the aspects of math that tend to be automatised, such as arithmetic, are more problematic in children with math disability. 

Evidence suggests that when procedural memory is impaired, children may have math disability, dyslexia, or developmental language disorder, though declarative memory -- where conscious knowledge is learned -- often compensates to some extent," Ullman said.

The researchers said that their theory, called the procedural deficit hypothesis of math disability, "offers a powerful, brain-based approach for understanding the disorder, and could help guide future research." 

"We believe that understanding the role of memory systems in these disorders should lead to diagnostic advances and possible targets for interventions," Ullman noted, in the paper published in the journal Frontiers in Psychology. 

London, Sep 16 (IANS) Leaders often believe that they should show anger to make subordinates more compliant. Though angry leaders are perceived by others to wield more power, followers warm up more easily to those showing more vulnerable emotions, such as sadness, a study has found.

Emphasising that leaders should consciously reflect on the emotions they display, the study revealed that though angry leaders are considered to be more powerful than sad leaders, they still score lower on their leadership report cards.

"Subordinates form impressions of their leaders when they view their displays of emotion in negative work situations", said Tanja Schwarzmuller from the Technical University of Munich in Germany.

Although leaders might benefit from stressing their legitimate power, displays of anger could backfire as they cause subordinates to infer that their "boss" has strong coercive power but weak referent power -- the ability of a leader to influence followers by making them identify and sympathise with him or her. 

This referent power is also a crucial prerequisite for ensuring followers' loyalty and commitment, the study said.

"Although angry leaders might be considered more powerful in general, their resulting power seems to rest upon a weak foundation", Schwarzmuller observed.

For the study, the team conducted three sets of experiments. In the first two, groups of students or working adults assessed videos depicting angry and sad leaders. In the third, an online survey was conducted where the participants were shown relevant photographs.

As expected, angry leaders were viewed as having higher levels of different types of position power. This includes being legitimately instated over others, having the right to give or withhold rewards and coercive power to punish others.

Followers hence seem to think that leaders displaying anger, in comparison to leaders showing sadness, more strongly stress their legitimate position within the hierarchy of an organisation and the control over punishment and reward that is available to them. 

However, when it comes to personal power, leaders displaying sadness seem to appeal to followers more strongly, the researchers stated.

On the other hand, showing sadness too may prove to be problematic, as it often reduces a leader's legitimate power to punish - a power base that negatively affects leadership outcomes, the researchers concluded in the paper, published in the Journal of Business and Psychology.

Washington, Sep 16 (IANS) NASA's Cassini spacecraft has entered the final year of its epic voyage during which it will make the the closest-ever observations of Saturn and its rings.

The conclusion of the historic scientific odyssey is planned for September 2017, but not before the spacecraft completes a daring two-part endgame, NASA said in a statement on Friday.

Beginning on November 30, Cassini's orbit will send the spacecraft just past the outer edge of the main rings. 

These orbits, a series of 20, are called the F-ring orbits. During these weekly orbits, Cassini will approach to within 7,800 kms of the centre of the narrow F ring, with its peculiar kinked and braided structure.

"During the F-ring orbits we expect to see the rings, along with the small moons and other structures embedded in them, as never before," said Linda Spilker, Cassini Project Scientist at NASA's Jet Propulsion Laboratory, Pasadena, California. 

"The last time we got this close to the rings was during arrival at Saturn in 2004, and we saw only their backlit side. Now we have dozens of opportunities to examine their structure at extremely high resolution on both sides," Spilker noted.

Cassini's final phase -- called the Grand Finale -- begins in earnest in April 2017, the US space agency said.

A close flyby of Saturn's giant moon Titan will reshape the spacecraft's orbit so that it passes through the gap between Saturn and the rings - an unexplored space only about 2,400 kms wide. 

The spacecraft is expected to make 22 plunges through this gap, beginning with its first dive on April 27.

During the Grand Finale, Cassini will make the closest-ever observations of Saturn, mapping the planet's magnetic and gravity fields with exquisite precision and returning ultra-close views of the atmosphere. 

Scientists also hope to gain new insights into Saturn's interior structure, the precise length of a Saturn day, and the total mass of the rings -- which may finally help settle the question of their age. 

The spacecraft will also directly analyse dust-sized particles in the main rings and sample the outer reaches of Saturn's atmosphere -- both first-time measurements for the mission.

"It's like getting a whole new mission," Spilker said. 

"The scientific value of the F ring and Grand Finale orbits is so compelling that you could imagine a whole mission to Saturn designed around what we're about to do," Spilker noted.

A joint endeavor of NASA, the European Space Agency (ESA) and the Italian space agency, Agenzia Spaziale Italiana (ASI), Cassini is a sophisticated robotic spacecraft orbiting the ringed planet and studying the Saturnian system in detail. 

The mission has already spent more than 12 years studying Saturn, its rings and moons.

Tokyo, Sep 15 (IANS) Do you pine for a long nap during the day? Be careful, as it could be a warning sign for Type-2 diabetes, suggests a recent research.

In the study led by Yamada Tomahide from the University of Tokyo, the team conducted a meta-analysis of observational studies involving more than 300,000 people.

They found that long daytime naps of more than 60 minutes may lead to a 45 per cent increased risk of Type-2 diabetes, compared with no daytime napping.

However, it was also possible that people who were less healthy or in the early stages of diabetes were more likely to nap for longer during the day.

People with long-term illnesses and undiagnosed diabetes often felt tired during the day, the researchers said.

"It's likely that risk factors which lead to diabetes also cause napping. This could include slightly high sugar levels, meaning napping may be an early warning sign of diabetes," Naveed Sattar, Professor at the University of Glasgow, was cited by bbc.com as saying in a comment on the research findings.

There was now a lot of evidence of some kind of link between sleep disturbances and diabetes, Sattar observed.

Long naps could also be a result of disturbed sleep at night, potentially caused by sleep apnea.

And this sleeping disorder could increase the risk of heart attacks, stroke, cardiovascular problems and other metabolic disorders, including Type-2 diabetes.

Sleep deprivation, caused by work or social life patterns, could also lead to increased appetite, which could increase the risk of Type-2 diabetes.

In contrast, shorter naps (less than 40 minutes), were more likely to increase alertness and motor skills, the researchers noted.

The findings were presented at 2016 European Association for the Study of Diabetes Meeting in Munich, Germany, recently.

​London, Sep 15 (IANS) Old age may slow down memory and other physical and cognitive skills, but the brain has the remarkable potential to reduce these effects, a study has found.

In order to process the information that we receive every day, our brain builds categories into which we sort everything that makes up the world around us.

The study found that this process of categorisation changes as we age. The brains of elderly struggle to categorise and rapidly switch focus from one to another.

"Older people find it harder to switch from one strategy to the other," said Sabrina Schenk, neuroscientist at Ruhr-Universitat Bochum (RUB) in Germany.

But, their brains compensate by paying more attention to detail than younger adults, the study said.

While the young adults spread their attention wide and gather information from different sources, the elderly focus their attention, looking more at detail, the researchers explained.

"To a certain extent, the brain is able to slow down negative effects of ageing by increasing its level of attentiveness," Schenk added.

In the study, the participants were asked to sort circles with varying colour combinations into one of two categories. 

Some of the circles were very similar to each other; others were distinctly different. To which category the circles belonged was indicated by a feedback during the test.

The researchers not only documented the participants' answers, they also recorded their brain waves via an electroencephalogram (EEG) and used an eye tracker to trace their line of vision. 

The results showed that both young and older participants had no difficulties categorising the similar looking circles -- the learning mechanism of both groups were comparable. 

It was only in the later stages of the experiment, when distinct looking circles where shown, that differences between the groups became apparent. 

Older participants found it more difficult to categorise these exceptions than their younger counterparts.

The measurements of brain waves also showed that the elderly develop a particular selective attentiveness.

In other words, they pay more attention to details and look more closely than younger people. This was also confirmed by the eye tracker, the researchers concluded in the paper published in the journal Neuropsychologia.

​Ontario, Sep 15 (IANS) Earth and other planetary objects formed in the early years of the Solar System share similar chemical origins, suggests a new finding.

Neodymium-142 (142Nd) is one of seven isotopes found in the chemical element neodymium which is widely distributed in the Earth's crust and most commonly used for magnets in commercial products like microphones and in-ear headphones.

In 2005, a small variation in 142Nd was detected between chondrites, which are stony meteorites, considered essential building blocks of the Earth and terrestrial rocks. 

These results were widely interpreted as an early differentiation of the interior of the Earth (including the crust and mantle) and these chondrites within the first 30 million years of its history.

The new results published by the journal Nature from Bouvier and Boyet showed that these differences in 142Nd were in fact already present during the growth of Earth and not introduced later, as was previously believed.

"How the Earth was formed and what type of planetary materials were part of that formation are issues that have puzzled generations of scientists. And these new isotopic measurements of meteorites provide exciting answers to these questions about our origins and what made the Earth so special," said Audrey Bouvier, Cosmochemist at the Western University. 

By using vastly improved measurement techniques, Bouvier and his colleague deduced that different meteoritical objects found in the Solar System incorporated the elements neodymium (Nd) and samarium (Sm) but with slightly different isotopic compositions. 

These variations in stable isotopes also show that the Solar System was not uniform during its earliest times and materials formed from previous generations of stars were incorporated in various proportions into the building blocks of planets.

Tokyo, Sep 15 (IANS) Astronomers have found signs of a giant icy planet growing around TW Hydrae, one of the closest young stars to Earth.

Based on the distance from the central star and the distribution of tiny dust grains, the baby planet is thought to be an icy giant, similar to Uranus and Neptune in our solar system. 

"Combined with the orbit size and the brightness of TW Hydrae, the planet would be an giant icy planet like Neptune," said lead researcher Takashi Tsukagoshi at Ibaraki University, Japan.

This result, to be published in the journal Astrophysical Journal Letters, is another step towards understanding the origins of various types of planets.

TW Hydrae is one of the most favourable targets for investigating planet formation.

Past observations have shown that TW Hydrae is surrounded by a disk made of tiny dust particles. This disk is the site of planet formation. 

Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations revealed multiple gaps in the disk. Some theoretical studies suggest that the gaps are evidence of planet formation.

The team observed the disk around TW Hydrae with ALMA in two radio frequencies. Since the ratio of the radio intensities in different frequencies depends on the size of the dust grains, researchers can estimate the size of dust grains. 

The ratio indicates that smaller, micrometer-sized, dust particles dominate and larger dust particles are absent in the most prominent gap with a radius of 22 astronomical units.

Theoretical studies have predicted that a gap in the disk is created by a massive planet, and that gravitational interaction and friction between gas and dust particles push the larger dust out from the gap, while the smaller particles remain in the gap. 

The current observation results match these theoretical predictions.

Researchers believe that the planet is probably a little more massive than Neptune.

Seoul, Sep 12 (IANS) Samsung Electronics on Monday said it has agreed to sell its printer business unit to US personal-computer maker HP. While the deal size has not been divulged, industry watchers put the figure at $1.05 billion.

​New York, Sep 14 (IANS) Facebook-owned instant messaging platform WhatsApp in its latest update to its iOS app now allows users to use Apple's digital assistant Siri to send messages and make voice calls, a media report said.