Knowledge Update

​Sydney, April 10 (IANS) A breakthrough chip for the nano-manipulation of light has pioneered new paths for developing next generation optical technologies and enabling deeper understanding of black holes.

Developed by a team of researchers at RMIT University in Melbourne, Australia, the integrated nanophotonic chip can achieve unparalleled levels of control over the angular momentum (AM) of light.

This means that now AM can be used at a chip-scale for the generation, transmission, processing and recording of information, and could also be used to help scientists better understand the evolution and nature of black holes.

While traveling approximately in a straight line, a beam of light also spins and twists around its optical axis. The AM of light measures the quantum of that dynamic rotation. 

Given the potential of using AM to enable the mass expansion of the available capacity of optical fibres, scientists have been trying to harness it on a chip scale.

"By designing a series of elaborate nano-apertures and nano-grooves on the photonic chip, our team has enabled the on-chip manipulation of twisted light for the first time," said Min Gu from RMIT University, who led the study that was published recently in the journal Science. 

"Our discovery could open up truly compact on-chip AM applications such as ultra-high definition display, ultra-high capacity optical communication and ultra-secure optical encryption," Gu added.

"It could also be extended to characterise the AM properties of gravitational waves, to help us gain more information on how black holes interact with each other in the universe," the researcher noted.​

London, April 10 (IANS) A formula taking into account the maximum mass of non-rotating neutron star has made it possible for scientists to calculate the critical mass when a rotating neutron star would collapse to become a black hole.

"It is quite remarkable that a system as complex as a rotating neutron star can be described by such a simple relation," said Luciano Rezzolla from the Goethe University in Frankfurt, one of the authors of the study.

Neutron stars have a mass that is up to twice that of the sun but a radius of only a dozen km, making them thousands of billions of times denser than that of the densest element on the Earth. 

But their mass cannot grow without bound. Indeed, if a non-rotating star increases its mass, its density also will increase. Normally this will lead to a new equilibrium and the star can live stably in this state for thousands of years. 

This process, however, cannot repeat indefinitely and the accreting star will reach a mass above which no physical pressure will prevent it from collapsing to a black hole. 

The critical mass when this happens is called the "maximum mass" and represents an upper limit to the mass that a non-rotating neutron star can be.

However, once the maximum mass is reached, the star also has an alternative to the collapse: It can rotate. 

A rotating star, in fact, can support a mass larger than if it was non-rotating, simply because the additional centrifugal force can help balance the gravitational force. 

Also in this case, however, the star cannot be arbitrarily massive because an increase in mass must be accompanied by an increase in rotation and there is a limit to how fast a star can rotate before breaking apart. Hence, for any neutron star there is an absolute maximum mass and is given by the largest mass of the fastest-spinning model.

Determining this value from first principles is difficult because it depends on the equation of state of the matter composing the star and this is still essentially unknown. Because of this, the determination of the maximum rotating mass of a neutron star has been an unsolved problem for decades. 

Scientists had to compute a very large number of stellar models to find the result, published recently in the journal Monthly Notices of the Royal Astronomical Society.

"Surprisingly, we now know that even the fastest rotation can at most increase the maximum mass of 20 percent at most," Rezzolla noted.

"This result has always been in front of our eyes, but we needed to look at it from the right perspective to actually see it," said Cosima Breu, a research student at the University of Frankfurt, who performed the analysis of the data during her bachelor thesis.

This simple but powerful result opens the prospects for more universal relations to be found in rotating stars. "We hope to find more equally exciting results when studying the largely unexplored grounds of differentially rotating neutron stars," Rezzolla said.​

​New York, April 10 (IANS) People with severe obesity who undergo bariatric surgery are likely to experience improvement in pain, physical function and walking ability, says a study.

The findings revealed that about 50-70 percent of adults experienced clinically significant improvements in perceived bodily pain and physical function and in objectively measured walking capacity.

The study's "large geographically diverse sample, inclusion of multiple validated measures of pain and physical function, longitudinal design, and follow-up through 3 years make it one of the most informative studies of pain and function following RYGB and LAGB to date," said Wendy C. King from the University of Pittsburgh in the US.

Severe obesity and excess weight can lead to joint damage and pain, resulting in limitations in walking and restricted other physical activities

The study, published in the journal JAMA, analysed 2,458 participants and was conducted at 10 hospitals. Of the participants, 79 percent were women with the median age 47 years and 2,221 completed baseline and follow-up assessments.

The assessments were conducted prior to surgery and annually thereafter.

Bariatric surgery is effective at achieving and maintaining weight loss, although the variability and durability of improvements in pain and physical function are not well described.

The team examined changes in pain and physical function in the first three years following bariatric surgery and factors associated with improvement, among adults with severe obesity.

Pre-surgery-to-post-surgery reductions in weight and depressive symptoms were associated with improvements in multiple outcomes.

About three-fourth of participants with severe knee and hip pain or disability at baseline experienced improvements in osteoarthritis symptoms.​

New York, April 10 (IANS) Researchers have determined that certain gastrointestinal tumours are more deadly than previously assumed.

Gastrointestinal stromal tumours (GISTs) may be malignant cancer or benign and are most commonly found in the stomach and small intestine and have significant variability in terms of size and malignant behaviour.

The finding, published online in the Journal of Gastrointestinal Surgery, showed that GISTs that are less than two cm cause 12.1 percent mortality rate for five years.

Also, up to 30 percent of patients have GISTs less than two cm in size, or slightly more than half an inch, the researchers noted.

More than 79 percent of patients have localised disease of GISTs, while for 11.4 percent the disease can spread to other regions. Previously, researchers did not expect any disease to have spread.

"While GISTs are rare, we have found that certain groups of these tumours result in a much higher mortality than expected," said Jason Sicklick, assistant professor at University of California-San Diego in US.

For the study, the team identified 378 patients with malignant GISTs of less than two cms between 2001 and 2011.​

London, April 11 (IANS) Ancestors of modern-day humans are thought to have wiped out the ancient Neanderthals from Europe by passing on diseases and infections when they moved out of Africa and into the continent previously dominated by them.

The Neanderthals, who would only have developed resistance to the diseases of their European environment, are most likely to have been infected with a bacterium that causes stomach ulcers, the virus that causes genital herpes, tapeworms and tuberculosis.

The researchers said that some infectious diseases are likely to be many thousands of years older than previously believed.

The diseases and infections to which the hunter-gatherers were exposed would have made them less able to find enough food and remain healthy. The diseases would have spread through sexual contact between the two species.

"Humans migrating out of Africa would have been a significant reservoir of tropical diseases," said Charlotte Houldcroft from the University of Cambridge in Britain.

"For the Neanderthal population of Eurasia, adapted to that geographical infectious disease environment, exposure to new pathogens carried out of Africa may have been catastrophic," Houldcroft added.

The findings showed Helicobacter pylori -- a bacterium that causes stomach ulcers -- as highly likely to have been passed by humans to Neanderthals. 

It is estimated to have first infected humans in Africa between 88,000 to 116,000 years ago, and in Europe 52,000 years ago.

Another likely candidate is herpes simplex 2 -- the virus that causes genital herpes. Evidence in the genome of this disease suggested that it was transmitted to humans in Africa 1.6 million years ago from another, currently unknown hominin species that in turn acquired it from chimpanzees.

The researchers have challenged the view that the spread of infectious diseases exploded with the evolution of agriculture about 8,000 years ago, which saw denser and more settled human populations coexisting with livestock.

Instead, genetic data showed that many infectious diseases have been "co-evolving with humans and our ancestors for tens of thousands to millions of years, and passed from them to the animals,” the researchers noted in the paper published in the American Journal of Physical Anthropology.

"Hunter-gatherers lived in small foraging groups. Neanderthals lived in groups of between 15-30 members, for example. So disease would have broken out sporadically, but have been unable to spread very far. Once agriculture came along, these diseases had the perfect conditions to explode, but they were already around,” Houldcroft maintained.

Recent theories for the cause of Neanderthal extinction range from climate change to an early human alliance with wolves resulting in domination of the food chain.

"It is probable that a combination of factors caused the demise of Neanderthals and the evidence is building that spread of disease was an important one," Houldcroft concluded.​

​London, April 11 (IANS) Assessing the relationship between gender, BMI and notion of 'attractiveness', a new study finds that weight is intrinsically linked to attractiveness and women are the harshest judges and most harshly judged.

The findings showed that females perceive men and women with higher body mass index (BMI) as less attractive and judge other women harshly about weight in relation to beauty.

Conversely, men do not judge another man with a higher weight negatively, but still see overweight women as less attractive.

"This is the first study that looks at the relationship between BMI and attractiveness, from both gender's perspective" explained Sonia Oreffice, professor of University of Surrey in Britain.

Further, the anthropometric attributes -- physical measures of a person's size, form, and functional capacities, play a significant role in wage regressions in addition to attractiveness, showing that body size cannot be dismissed as a simple component of beauty.

The study, published in the journal Economics and Human Biology, provides insight into the relationship between body size and beauty and the wage inequality associated with it.

Body size -- height for both men and women and BMI only for men -- explains wages above and beyond beauty.

This contributes to bridge the gap between studies on the economics of anthropometric measures (including height and BMI), on one hand, and the economics of beauty, on the other, estimating the relevance of body size and beauty, the researchers concluded.​

​London, April 11 (IANS) Using data from NASA's Kepler space telescope, astrophysicists from the University of Birmingham have discovered extra-solar planets whose atmospheres have been stripped away by their host stars.

According to them, planets with gaseous atmospheres that lie very close to their host stars are bombarded by a torrent of high-energy radiation. 

Due to their proximity to the star, the heat that the planets suffer means that their "envelopes" have been blown away by intense radiation. 

This violent "stripping" occurs in planets that are made up of a rocky core with a gaseous outer layer.

"The results show that planets of a certain size that lie close to their stars are likely to have been much larger at the beginning of their lives. Those planets will have looked very different," said Dr Guy Davies from the University of Birmingham's school of physics and astronomy. 

The findings have important implications for understanding how stellar systems, like our own solar system, and their planets, evolve over time and the crucial role played by the host star.

Scientists expect to discover many such "stripped systems" using a new generation of satellites including the NASA TESS Mission which will be launched next year. 

The paper was published in the journal Nature Communications. ​

​London, April 11 (IANS) How to determine that a person is trustworthy? According to researchers, people who hold onto moral absolutes are more trusted and more valued as social partners, suggesting that people gauge others' trustworthiness based on their moral judgments.

The findings help explain that snap judgements about morality tend to be based on a set of absolute moral rules even if a person makes different decisions when given more time.

"If people who stick to moral absolutes are preferred as social partners, expressing this view will reap benefits for oneself," said lead researcher Jim AC Everett from the University of Oxford.

The team used several variations of moral dilemmas where a person must decide whether or not to sacrifice an innocent person in order to save the lives of many others. 

The results indicate that across nine experiments, more than 2,400 participants who took an absolute approach to the dilemmas (like refusing to kill an innocent person, even when this maximised the greater good) were seen as more trustworthy than those who advocated a more flexible approach. 

When asked to entrust a person with a sum of money, participants handed over more money and were more confident of getting it back, when dealing with someone who refused to sacrifice one to save many. 

"This explains why we appear to like people who stick to these intuitive moral rules -- not because they are sticklers for the letter of the law, but because the rules themselves tend to emphasize the absolute importance of respecting the wishes and desires of others," added David Pizarro from Cornell University in the US.

Our day-to-day moral decisions don't fit into the neat categories defined by moral philosophers. Instead, real life morality is suited to the complexity of real life situations, the researchers suggested in a paper that appeared in the Journal of Experimental Psychology: General. ​

New York, April 11 (IANS) Scientists have invented a “smart” paint spray can that robotically reproduces photographs as giant murals.

The computerised technique which basically spray paints a photo is not likely to spawn a wave of giant graffiti but it can be used in digital fabrication, digital and visual arts, artistic stylisation and other applications, said the team from Dartmouth college and colleagues.

The system uses an ordinary paint spray can, tracks the can's position relative to the wall or canvas and recognises what image it "wants" to paint. 

As the person waves the pre-programmed spray can around the canvas, the system automatically operates the spray on and off button to reproduce the specific image as a spray painting.

“We show that by combining computer graphics and computer vision techniques, we can bring such assistance technology to the physical world even for this very traditional painting medium, creating a somewhat unconventional form of digital fabrication,” said study co-author Wojciech Jarosz who worked as senior research scientist at Disney Research Zurich. 

“We wanted to maintain the aesthetic aspects of physical spray painting and the tactile experience of holding and waving a physical spray can while enabling unskilled users to create a physical piece of art,” he added.

The prototype includes two webcams and QR-coded cubes for tracking and a small actuation device for the spray can 00 attached via a 3D-printed mount. 

Paint commands are transmitted via radio directly connected to a servo-motor operating the spray nozzle. 

Running on a nearby computer, the real-time algorithm determines the optimal amount of paint of the current colour to spray at the spray can's tracked location. 

“The end result is that the painting reveals itself as the user waves the can around, without the user necessarily needing to know the image beforehand,” the team noted in a paper that appeared in the journal Computer & Graphics. ​

​New York, April 11 (IANS) US doctors, including an Indian American doctor reported the first case of a human patient whose severely damaged oesophagus was reconstructed using commercially available stents and skin tissues.

After the 24-year-old man was paralysed in a car crash seven years ago, doctors struggled to repair his disrupted oesophagus.

Despite several surgeries, the defect in the oesophagus was too large to repair and it was resulting in life-threatening infection, the physicians noted in the paper published in the journal in The Lancet.

The team of doctors decided to try a technique previously tested only in animals, to reconstruct the upper oesophagus with stents and skin tissue approved by the US Food and Drug Administration.

"This is a first in human operation and one that we undertook as a life-saving measure once we had exhausted all other options available to us and the patient,” Kulwinder Dua, professor at Medical College of Wisconsin in the US. 

The doctors used metal stents as a non-biological scaffold and a regenerative tissue matrix from donated human skin to rebuild a full-thickness five cm defect in the oesophagus of the patient.

They inserted an endoscope containing a wire through the man's stomach and up through what remained of his oesophagus, leading to his mouth. 

Guided by the wire, they then inserted three stents to recreate the structure of the oesophagus and covered it with skin tissue. 

The tissue was then sprayed with a gel made from the patient's own blood, which contained natural substances to attract stem cells.

Although the doctors wanted to remove the stents about three months after the surgery, the patient refused, fearing he would not be able to eat and drink; he was also worried about possible scarring. 

Nearly four years later, doctors removed the stents after the man had trouble swallowing when a problem arose with the lower stent.

One year after that, doctors examined the man's oesophagus and found that all five layers of the oesophagus had regrown, closely resembling a normal one. 

The patient now does not need a feeding tube and also has not reported any other complications.

Swallowing tests showed full recovery and functioning was also established with oesophageal muscles able to propel water and liquid along the oesophagus into the stomach in both upright and 45 degrees sitting positions.

"The approach we used is novel because we used commercially available products which are already approved for use in the human body and hence didn't require complex tissue engineering," Dua explained.

The research including animal studies and clinical trials, are now needed to investigate whether the technique can be reproduced and used in other similar cases.

“The use of this procedure in routine clinical care is still a long way off as it requires rigorous assessment in large animal studies and phase one and two clinical trials," Dua stated.

The oesophagus is a hollow muscular tube that connects the mouth to the stomach carrying food and liquids.