Knowledge Update

​London, June 2 (IANS) A part of the Antarctica coastline has been losing ice to the ocean for over four decades, far longer than had been expected, finds a new study of satellite images.

The images of 2,000 km of west Antarctica's coastline showed a loss of about 1,000 km of ice, the researchers said.

"We knew that ice had been retreating from this region recently but now, thanks to a wealth of freely available satellite data, we know this has been occurring pervasively along the coastline for almost half a century," said lead researcher Frazer Christie, doctoral student at the University of Edinburgh's School of GeoSciences in Britain.

The findings showed that ice has been retreating consistently along almost the entire coastline of Antarctica's Bellingshausen Sea since satellite records began.

Warmer ocean waters reaching Antarctica's coast, rather than rising air temperatures, are the reason behind the loss of ice, the scientists suggest. 

For the study, published in Geophysical Research Letters, the team analysed hundreds of satellite photographs of the ice margin captured by NASA, the United States Geological Survey (USGS) and the European Space Agency (ESA).

The team also monitored ice thickness and thinning rates using data taken from satellites and the air. 

This showed that some of the largest changes, where ice has rapidly thinned and retreated several miles since 1975, correspond to where the ice front is deepest.

"This study provides important context for our understanding of what is causing ice to retreat around the continent," said Robert Bingham from School of GeoSciences. 

The results will help improve estimates of global sea level rise caused by ice melt, the researchers noted adding that further satellite monitoring is needed to track progress of the ice sheet.

"We now know change to West Antarctica has been longstanding, and the challenge ahead is to determine what has been causing these ice losses for so long," Bingham said.​

Washington, June 3 (IANS) In a significant find, astronomers using NASA's Hubble Space Telescope have discovered that the universe is expanding five percent to nine percent faster than expected.

There are a few possible explanations for the universe's excessive speed. One possibility is that dark energy, already known to be accelerating the universe, may be shoving galaxies away from each other with even greater -- or growing -- strength.

"This surprising finding may be an important clue to understanding those mysterious parts of the universe that make up 95 per cent of everything and don't emit light, such as dark energy, dark matter and dark radiation," explained study leader and Nobel Laureate Adam Riess from the Space Telescope Science Institute and Johns Hopkins University.

Riess' team made the discovery by refining the universe's current expansion rate to unprecedented accuracy, reducing the uncertainty to only 2.4 per cent.

For the results, the team looked for galaxies containing both Cepheid stars and Type Ia supernova.

Cepheid stars pulsate at rates that correspond to their true brightness, which can be compared with their apparent brightness as seen from Earth to accurately determine their distance.

Type Ia supernovae are exploding stars that flare with the same brightness and are brilliant enough to be seen from relatively longer distances.

By measuring about 2,400 Cepheid stars in 19 galaxies and comparing the observed brightness of both types of stars, they accurately measured their true brightness and calculated distances to roughly 300 Type Ia supernovae in far-flung galaxies.

The team compared those distances with the expansion of space as measured by the stretching of light from receding galaxies.

They used these two values to calculate how fast the universe expands with time, or the Hubble constant.

The improved Hubble constant value 45.5 miles per second per megaparsec. (A megaparsec equals 3.26 million light-years.)

The new value means the distance between cosmic objects will double in another 9.8 billion years.

Measurements of the afterglow from the Big Bang by NASA's Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency's Planck satellite mission yield predictions which are 5 percent and 9 percent smaller for the Hubble constant, respectively.

"Comparing the universe's expansion rate with WMAP, Planck, and Hubble is like building a bridge," Riess added.

Another possibility of this expansion is that the cosmos contained a new subatomic particle in its early history that travelled close to the speed of light.

Such speedy particles are collectively referred to as "dark radiation" and include previously known particles like neutrinos.

More energy from additional dark radiation could be throwing off the best efforts to predict today's expansion rate from its post-Big Bang trajectory.

The speedier universe may be telling astronomers that Albert Einstein's theory of gravity is incomplete.

"We know so little about the dark parts of the universe, it's important to measure how they push and pull on space over cosmic history," said Lucas Macri from Texas A&M University in College Station.

The results are forthcoming in The Astrophysical Journal.​​

​New York, June 3 (IANS) A team of scientists from Harvard University has co-created a unique "bionic leaf" that uses solar energy to split water molecules and hydrogen-eating bacteria to produce liquid fuels.

Dubbed “bionic leaf 2.0,” the new system can convert solar energy to biomass with 10 percent efficiency -- far above the one per cent seen in the fastest growing plants.

"This is a true artificial photosynthesis system. Before this, people were using artificial photosynthesis for water-splitting but this is a true A-to-Z system and we've gone well over the efficiency of photosynthesis in nature,” said Daniel Nocera, the Patterson Rockwood professor of energy at Harvard University.

While the study shows the system can be used to generate usable fuels, its potential doesn't end there.

"In principle, we have a platform that can make any downstream carbon-based molecule. So this has the potential to be incredibly versatile,” added co-author Pamela Silver, the Elliott T. and Onie H. Adams Professor of Biochemistry and Systems Biology.

For this paper, the team designed a new cobalt-phosphorous alloy catalyst which, “we showed does not make reactive oxygen species. That allowed us to lower the voltage, and that led to a dramatic increase in efficiency”, Nocera noted in a paper published in the journal Science.

The new catalyst also came with another advantage. Its chemical design allows it to "self-heal" -- meaning it wouldn't leech material into solution.

The new system is already effective enough to consider possible commercial applications but within a different model for technology translation.

"It's an important discovery -- it says we can do better than photosynthesis," Nocera said. "But I also want to bring this technology to the developing world as well."

In many ways, the new system marks the fulfillment of the promise of his “artificial leaf” which used solar power to split water and make hydrogen fuel.​

New York, June 3 (IANS) A massive amount of ammonia gas lies beneath the colourful clouds on Jupiter, astronomers have revealed, a discovery coming just a month prior to the arrival of NASA's Juno spacecraft at the planet on July 4.

Using the Karl G. Jansky Very Large Array in New Mexico, the researchers from University of California-Berkeley measured radio emissions from Jupiter's atmosphere in wavelength bands where clouds are transparent. 

The observers were able to see as deep as 100 km below the cloud tops, a largely unexplored region where clouds form.

The planet's thermal radio emissions are partially absorbed by ammonia gas. Based on the amount of absorption, the researchers could determine how much ammonia is present and at what depth.

“We, in essence, created a three-dimensional picture of ammonia gas in Jupiter's atmosphere, which reveals upward and downward motions within the turbulent atmosphere," said principal author Imke de Pater, a UC Berkeley professor of astronomy.

The map bears a striking resemblance to visible-light images taken by amateur astronomers and the Hubble Space Telescope.

The study will shed light on similar processes occuring on other giant planets in our solar system and on newly-discovered giant exoplanets around distant stars.

The radio map shows ammonia-rich gases rising into and forming the upper cloud layers.

Conversely, the radio maps show ammonia-poor air sinking into the planet, similar to how dry air descends from above the cloud layers on Earth.

The map also shows that hotspots -- so-called because they appear bright in radio and thermal infrared images -- are ammonia-poor regions that encircle the planet like a belt just north of the equator. Between these hotspots are ammonia-rich upwellings that bring ammonia from deeper in the planet.

“With radio, we can peer through the clouds and see that those hotspots are interleaved with plumes of ammonia rising from deep in the planet, tracing the vertical undulations of an equatorial wave system," said UC Berkeley research astronomer Michael Wong.

The observations were reported in the journal Science at a time when NASA's Juno spacecraft plans, in part, to measure the amount of water in the deep atmosphere where the Very Large Array looked for ammonia.

"Maps like ours can help put their data into the bigger picture of what's happening in Jupiter's atmosphere," de Pater noted.​

​London, June 3 (IANS) A test to identify long-term memory loss is likely to provide an early indication of Alzheimer's disease and potentially help in reversing its effects by the development of new treatment, new research suggests.

Alzheimer's disease is caused by proteins building up in the brain to form structures called plagues and tangles. This leads to the loss of connection between nerve cells and, eventually, to the death of the nerve cells and loss of brain tissue.

The findings showed that testing memory over a long timescale reveals early deficits in the brain's ability to remember. These are not detected by checks for short-term forgetfulness, which is the current practice for diagnosis.

When short-term memory is used to diagnose Alzheimer's disease - as is currently the case - it may not reveal the true extent of memory loss at the onset of the condition.

By testing long-term memory, it may be possible to detect the earliest signs of Alzheimer's disease and offer interventions sooner.

A brain scan in combination with a memory test could identify early abnormalities in the brain activity of Alzheimer's patients that would be otherwise undetected, the researchers said.

The researchers studied long-term memory in young mice, some of which had the equivalent of very early stage Alzheimer's disease, and some of which were healthy.

Both groups were taught to locate a hidden platform in a pool filled with water, using signs on the wall of the room to navigate.

The results showed that when tested shortly after the initial task, both groups of mice were able to remember the way to their destination.

However, when both groups were tested one week later, the mice in the Alzheimer's group had significantly more difficulty remembering the route.

Tests revealed that brain activity was normal in both groups of mice at their young age when no task was involved.

"We recognise that tests with animals must be interpreted with caution, but the use of these genetic models in conjunction with appropriate testing is pointing at an important dimension of early diagnosis," said lead researcher Richard Morris, Professor at University of Edinburgh in Britain. 

"It is widely acknowledged that earlier intervention is needed to effectively treat Alzheimer's disease, and better diagnostic tools are needed for that. We believe that our approach could make a significant contribution," added Vassilios Beglopoulos from University of Edinburgh.

New York, June 3 (IANS) Each injury could mean a little more for the elderly -- more impact and more healing time. A new study has now found that the skin's ability to repair itself takes longer as we age because the healing function of sweat glands declines with time.

"We've identified, for the first time, the cellular mechanisms of altered skin wound repair in elderly patients," said study first author Laure Rittie from the University of Michigan.

The researchers compared 18 elderly person's skin to 18 young adults' skin, to see how each group healed from skin lesions. 

The lesions were smaller than the diametre of a pencil eraser, performed under local anesthesia.

The researchers had already determined that eccrine sweat glands, which are located throughout the body, are important for wound closure. 

They are major contributors of new cells that replace the cells that were lost due to injury. This finding led to a new research question.

"Since we know elderly people tend to sweat less than young adults, we concentrated on this healing function of sweat glands," Rittie said.

In young people, they discovered sweat glands contributed more cells to wound closure than in aged adults. 

The cells in aged skin were not as cohesive, either. Fewer cells participating, spaced further apart, means a delay in wound closure and a thinner repaired epidermis in aged versus young skin.

It was not that the sweat glands were less active in older people, rather, that the environment in the ageing skin had been slowly degraded, making the skin structures less able to support the new cells that were generated, the study said.

The findings were published in the journal Aging Cell.

"This tells us that, beyond the frustrating appearance, skin ageing also negatively impacts the ability of the skin to repair itself," Rittie noted.​

​London, June 3 (IANS) Your loving dog may have come into being independently from two separate -- possibly now extinct -- wolf populations that lived on opposite sides of the Eurasian continent, new research has revealed.

An international team of scientists compared genetic data with existing archaeological evidence and found that dogs may have been domesticated not once, as widely believed, but twice.

A review of the archaeological record shows that early dogs appear in both the East and West more than 12,000 years ago, but in Central Asia no earlier than 8,000 years ago.

"Our ancient DNA evidence, combined with the archaeological record of early dogs, suggests that we need to reconsider the number of times dogs were domesticated independently,” said professor Greger Larson from University of Oxford.

The project on dog domestication, led by University of Oxford, reconstructed the evolutionary history of dogs by first sequencing the genome (at Trinity College Dublin) of a 4,800-year old medium-sized dog from bone excavated at the Neolithic Passage Tomb of Newgrange, Ireland.

The team (including French researchers based in Lyon and at the National Museum of Natural History in Paris) also obtained mitochondrial DNA from 59 ancient dogs living between 14,000 to 3,000 years ago and then compared them with the genetic signatures of more than 2,500 previously studied modern dogs.

Combined, the new findings suggest that dogs were first domesticated from geographically separated wolf populations on opposite sides of the Eurasian continent.

At some point after their domestication, the eastern dogs dispersed with migrating humans into Europe where they mixed with and mostly replaced the earliest European dogs.

Most dogs today are a mixture of both Eastern and Western dogs -- one reason why previous genetic studies have been difficult to interpret.

The new genetic evidence also shows a population turnover in Europe that appears to have mostly replaced the earliest domestic dog population there, which supports the evidence that there was a later arrival of dogs from elsewhere.

"The Newgrange dog bone had the best preserved ancient DNA we have ever encountered, giving us prehistoric genome of rare high quality. It is not just a postcard from the past, rather a full package special delivery,” added senior author professor Dan Bradley from Trinity College Dublin in a paper appared in the journal Science.

"With so much new and exciting data to come, we will finally be able to uncover the true history of man's best friend,” noted professor Keith Dobney, co-author from Liverpool University.​

​London, June 3 (IANS) The elderly are less willing to indulge in risk-taking behaviour for potential rewards when compared to youngsters because of the declining levels of dopamine in the brain, finds a study.

Dopamine is a chemical in the brain involved in predicting which actions will lead to rewards and has been known to fall by up to 10 per cent every decade throughout adult life.

The findings showed that older people were not overall more risk-averse as well as they didn't make much mistakes as compared to young adults. 

Rather, the elderly were found simply less attracted to big rewards and this made them less willing to take risks to try to get them, the researchers said.

"The findings offer a potential neuroscientific explanation, suggesting that a natural decline in dopamine with age might make people less receptive to the positive approach than they would have been when they were younger," said lead author Robb Rutledge from University College London.

The steady decline in risky choices with age matched up with the declining dopamine level.

However, they were no different to younger participants when it came to choosing risky gambles to avoid losing points. 

"As one ages, the dopamine levels naturally decline explaining the reason why one is less likely to seek rewards," added Rutledge.

The study, published in Current Biology, involving 25,189 smartphone users aged 18-69, found that older people were less likely to choose risky gambles to win more points in a smartphone app called The Great Brain Experiment.

In the game, players start with 500 points and aim to win as many points as possible in 30 different trials where they must choose between a safe option and a risky 50/50 gamble.

"This study is an excellent example of the use of digital technology to produce new and robust insights into the workings of the brain," explained Raliza Stoyanova from the neuroscience and mental health team at Wellcome Trust in Britain.​

Bangkok, June 3 (IANS) The discovery of more than 40 dead tiger cubs in Thailand's Tiger Temple represents only a "tiny proportion" of the enormous extent of an illegal trade in wildlife that is "pushing species to the brink of extinction", the UNEP-UNODC said on Friday.

"While circumstances of their death remain unclear, sadly, those tiger cubs represent only a tiny proportion of the enormous extent of an illegal trade in wildlife that is pushing species to the brink of extinction. Indeed, only around 4,000 tigers are left in the wild," United Nations Environment Programme-United Nations Office on Drugs and Crime (UNODC) said in a statement.

"Until the illegal trade in wildlife is stopped, we are only likely to see more of these types of situations," the statement added.

The theme for World Environment Day on June 5 this year is the illegal trade in wildlife to raise awareness of this severe problem. Tigers are one of the key species in the campaign.

The illegal trade in wildlife, estimated to profit criminals to the tune of billions of dollars annually worldwide, comprises everything from the lucrative trade in Tiger parts in East Asia to ivory from African elephants, the organisations said.

"It undermines our environment, economies, communities and security."

"The commendable action by Thailanda's authorities, coordinated by the Department of National Parks, Wildlife and Plant Conservation, highlights the need for constant vigilance by wildlife law enforcement authorities to the threat posed by traffickers."

"Given the extent of the illegal wildlife market in Asia it is important for all countries to unite and eradicate these illegal practices," the statement said.

Officials had recovered 40 dead tiger cubs, just one to two days old, from a freezer at Wat Pha Luang Ta Bua temple, known as the "Tiger Temple", on Wednesday, EFE news reported.

The cubs were not recorded in the register for wild animals the temple has to maintain by law and that means the protection department will press charges for illegal possession, besides other possible offences.​

​New York, June 3 (IANS) By fabricating tiny lasers directly on silicon, an international group of scientists has found a way that could make microprocessors run faster without consuming more power.

The group of scientists from Hong Kong University of Science and Technology, the University of California, Santa Barbara, Sandia National Laboratories and Harvard University grew tiny high-performance lasers directly on silicon wafers.

Reported in the journal Applied Physics Letters, the group said integrating subwavelength cavities -- the essential building blocks of tiny lasers -- onto silicon enabled them to create and demonstrate high-density on-chip light-emitting elements.

"Putting lasers on microprocessors boosts their capabilities and allows them to run at much lower powers, which is a big step toward photonics and electronics integration on the silicon platform," said professor Kei May Lau from Hong Kong University of Science and Technology.

The scientists used "tiny whispering gallery mode lasers -- only 1 micron in diameter -- that are 1,000 times shorter in length and 1 million times smaller in area than those currently used."

In terms of applications, the group's tiny lasers on silicon are ideally suited for high-speed data communications.​