Knowledge Update

Seoul, June 21 (IANS) Scientists have made ultra-thin photovoltaic cells flexible enough to wrap around the average pencil that could power wearable electronics like fitness trackers and smart glasses.

"Our photovoltaic is about 1 micrometre, thinner than an average human hair," said Jongho Lee, an engineer at the Gwangju Institute of Science and Technology in South Korea. Standard photovoltaics are usually hundreds of times thicker and even most other thin photovoltaics are two to four times thicker.

The researchers made the ultra-thin solar cells from the semiconductor gallium arsenide.

They stamped the cells directly onto a flexible substrate without using an adhesive that would add to the material's thickness. The cells were then "cold welded" to the electrode on the substrate.

The researchers tested the efficiency of the device at converting sunlight to electricity and found that it was comparable to similar thicker photovoltaics. They performed bending tests and found the cells could wrap around a radius as small as 1.4 millimetres.

The team also performed numerical analysis of the cells, finding that they experience one-fourth the amount of strain of similar cells that are 3.5 micrometres thick.

"The thinner cells are less fragile under bending, but perform similarly or even slightly better," Lee said in a paper published in the journal Applied Physics Letters.

These thin cells can be integrated onto glasses frames or fabric and might power the next wave of wearable electronics, Lee noted.​

​New York, June 21 (IANS) Silencing a specific gene may affect human social behaviour, including a person's ability to form healthy relationships or to recognise the emotional states of others, says a study.

The scientists examined how a process known as methylation, which can reduce the expression of specific genes, affects a gene called OXT. 

This gene is responsible for the production of a hormone called oxytocin, which is linked to a wide range of social behaviours in humans and other mammals.

"Methylation restricts how much a gene is expressed," said the study's lead author Brian Haas, Assistant Professor of Psychology at the University of Georgia in the US.

"An increase in methylation typically corresponds to a decrease in the expression of a gene, so it affects how much a particular gene is functioning,” Haas explained.

"When methylation increases on the OXT gene, this may correspond to a reduction in this gene's activity. Our study shows that this can have a profound impact on social behaviours," he added.

The study was published in the journal Proceedings of the National Academy of Sciences.

Haas and his collaborators collected saliva samples from more than 120 study participants to perform genetic tests that show the levels of methylation on the OXT gene. 

The participants went through a battery of tests to evaluate their social skills as well as their brain structure and function.

What they found is that participants with greater methylation of the OXT gene - likely corresponding to lower levels of OXT expression - had more difficulty recognising emotional facial expressions, and they tended to have more anxiety about their relationships with loved ones.​

New York, June 21 (IANS) Children who often go hungry are more than twice as likely to develop impulse control problems and engage in violence later in life, new research has found.

Thirty-seven percent of the study's participants who had frequent hunger as children reported that they had been involved in interpersonal violence. 

Of those who experienced little to no childhood hunger, 15 percent said they were involved in interpersonal violence. 

Previous research has shown that childhood hunger contributes to a variety of other negative outcomes, including poor academic performance. 

The current study is among the first to find a correlation between childhood hunger, low self-control and interpersonal violence.

"Good nutrition is not only critical for academic success, but now we're showing that it links to behavioral patterns. When kids start to fail in school, they start to fail in other domains of life," said Alex Piquero, Professor of Criminology at University of Texas at Dallas.

The study was published in the International Journal of Environmental Research and Public Health.

The researchers used data from the US National Epidemiologic Survey on Alcohol and Related Conditions to examine the relationship between childhood hunger, impulsivity and interpersonal violence. 

Participants in that study responded to a variety of questions including how often they went hungry as a child, whether they have problems controlling their temper, and if they had physically injured another person on purpose.

The findings suggest that strategies aimed at alleviating hunger may also help reduce violence, Piquero said.​

​Washington, June 21 (IANS) Using NASA's Kepler Space Telescope and its extended K2 mission, astronomers have discovered a newborn fully-formed exoplanet -- planets that orbit stars beyond our Sun -- ever detected around a young star.

The newfound planet named K2-33b is a bit larger than Neptune and whips tightly around its star every five days.

It is only five to 10 million years old, making it one of a very few newborn planets found to date.

"Our Earth is roughly 4.5 billion years old. By comparison, the planet K2-33b is very young. You might think of it as an infant," said led researcher Trevor David from California Institute of Technology (Caltech).

Astronomers have discovered and confirmed roughly 3,000 exoplanets so far. However, nearly all of them are hosted by middle-aged stars, with ages of a billion years or more.

"The newborn planet will help us better understand how planets form, which is important for understanding the processes that led to the formation of the Earth," added co-author Erik Petigura from Caltech.

The first signals of the planet's existence were measured by K2. The telescope's camera detected a periodic dimming of the light emitted by the planet's host star, a sign that an orbiting planet could be regularly passing in front of the star and blocking the light.

"Initially, this material may obscure any forming planets, but after a few million years, the dust starts to dissipate," said co-author Anne Marie Cody, a NASA postdoctoral programme fellow.

A surprising feature in the discovery of K2-33b is how close the newborn planet lies to its star. The planet is nearly 10 times closer to its star than Mercury is to our sun, making it hot.

While numerous older exoplanets were found orbiting very tightly to their stars, astronomers have long struggled to understand how more massive planets like this one wind up in such small orbits.

Some theories propose that it takes hundreds of millions of years to bring a planet from a more distant orbit into a close one and, therefore, cannot explain K2-33b which is quite a bit younger.

K2-33b could have migrated there in a process called disk migration that takes hundreds of thousands of years.

Or, the planet could have formed "in situ" -- right where it is.

The discovery of K2-33b, therefore, gives theorists a new data point to ponder.

"The question we are answering is: Did those planets take a long time to get into those hot orbits or could they have been there from a very early stage? We are saying, at least in this one case, that they can indeed be there at a very early stage," David noted in a paper appeared in the journal Nature.​

New York, June 21 (IANS) High blood sugar for long periods can cause serious health problems but surprisingly it can have a protective effect against one type of brain tumour that is not cancerous, says a new study.

"It's so unexpected. Usually diabetes and high blood sugar raises the risk of cancer, and it's the opposite here," said lead researcher Judith Schwartzbaum, Associate Professor at Ohio State University. 

The discovery could shed light on the development of meningiomas -- tumours arising from the brain and spinal cord that are usually not cancerous but that can require risky surgery and affect a patient's quality of life.

When the researchers compared blood tests in a group of more than 41,000 Swedes with meningioma diagnoses, they found that high blood sugar, particularly in women, actually meant the person was less likely to face a brain tumour diagnosis.

"It should lead to a better understanding of what's causing these tumors and what can be done to prevent them," Schwartzbaum noted.

Though meningiomas are rarely cancerous, they behave in a similar way, leading scientists to wonder if some relationships between possible risk factors and tumour development would be similar, Schwartzbaum said.

The researchers, looking at data collected from 1985 to 2012, identified 296 cases of meningioma, more than 61 percent of them in women.

Women with the highest fasting blood sugar were less than half as likely as those with the lowest readings to develop a tumour.

The study was published in the British Journal of Cancer.

Possible explanations for the relationship could be found by closer examination of the role of sex hormones and the interplay between glucose levels and those hormones, Schwartzbaum said. 

It's also possible that sugar levels dip during early tumour development because the tumour is using glucose to grow, she said.

A diabetes diagnosis before meningioma also appeared to decrease the risk of this tumour, although Schwartzbaum said the data likely had incomplete information on diabetes.​

​New York, June 21 (IANS) DNA tests have confirmed that the earliest population to settle in the high valleys of the Himalayas were indeed East Asians of high altitude origin.

The genetic make-up of high-altitude Himalayan populations has remained remarkably stable despite cultural transitions and exposure to outside populations through trade, the findings showed.

"In this study, we demonstrate that the Himalayan mountain region was colonised by East Asians of high altitude origin, followed by millennia of genetic stability despite marked changes in material culture and mortuary behaviour," said senior author of the study Christina Warinner, Professor at the University of Oklahoma in the US.

The study was published in the journal Proceedings of the National Academy of Sciences.

The high altitude transverse valleys of the Himalayas were among the last habitable places permanently colonised by prehistoric humans due to the challenges of resource scarcity, cold stress and hypoxia.

The modern populations of these valleys, who share cultural and linguistic affinities with peoples found today on the Tibetan plateau, were commonly assumed to be the descendants of the earliest inhabitants of the Himalayan arc. 

However, this assumption had been challenged by archaeological and osteological evidence suggesting these valleys may have been originally populated from areas other than the Tibetan plateau, including those at low elevation.

To address the problem, Warinner and colleagues sequenced the nuclear and mitochondrial genomes of eight high-altitude Himalayan individuals dating to three distinct cultural periods spanning 3,150 to 1,250 years before present. 

The authors compared these ancient DNA sequences to genetic data from diverse modern humans, including four Sherpa and two Tibetans from Nepal.

All eight prehistoric individuals across the three time periods were most closely related to contemporary highland East Asian populations -- the Sherpas and Tibetans.

The findings strengthen the evidence that the diverse material culture of prehistoric Himalayan populations is the result of acculturation or culture diffusion rather than large-scale gene flow or population replacement from outside highland East Asia.​

​New York, June 20 (IANS) Babies who are born through Caesarean, exposed to antibiotics and are fed on formula milk are likely to have a slow growth as well as a decline in the diversity of microbes throughout the first year of life, finds a new study.

The findings showed that such children were at an increased risk of developing asthma, autoimmune diseases and obesity. 

Compared to vaginally born infants, those delivered by C-section showed significantly greater diversity of species in the weeks after birth. 

However, these measures declined in cesarean-born infants during their first month, after which they displayed lower diversity up to two years of age. 

"Our results provide evidence that modern practices have changed a baby's microbial communities in ways that last through the first year," said Martin Blaser, Professor at New York University.

"The change in birth mode interrupted the natural interplay between diversity and dominance," Blaser added.

Further, antibiotic treatment also significantly diminished diversity of bacterial species immediately following birth. 

Children fed on formula milk showed a decrease in the diversity of species during the second year of life also.

The study, published in the journal Science Translational Medicine, focused on the microbiome, the mix of bacterial species that live on human skin and in our guts and that co-evolved with humans to play roles in digestion, metabolism and immunity.

The team assessed the effects of modern practices on intestinal microbiota development in 43 US children of these 24 of were born by vaginal delivery and 19 by C-section.

They then used genomic and statistical techniques to analyse the millions of pieces of bacterial DNA in the samples.​

New York, June 20 (IANS) People who tend to put things off are more likely to develop insomnia -- a sleep disorder characterised by difficulty in falling or staying asleep, says a study.

The researchers said the link between procrastination and trouble falling asleep seemed to be explained by people worrying about things that they wanted to get done before going to bed, Live Science reported.

At bedtime "people who procrastinate are ruminating about the things they need to do and haven't done" and that makes it difficult for them to go to sleep, study author Ilana Hairston from Academic College of Tel Aviv in Israel was quoted as saying.

The study involved nearly 600 people. Through online questionnaires, the researchers examined their tendencies to procrastinate, along with their sleep problems and emotional states. 

The researchers found that trouble sleeping in participants could be an outcome of procrastination.

The results of the study will be published in a forthcoming issue of the journal Personality and Individual Differences.

Another important dimension that the researchers uncovered in the study was hat morning people -- those who wake up early in the morning and go to be early in the evening -- reported lower levels of procrastination and fewer sleep problems, compared to those who go to sleep late at night and wake up late -- the evening people.

The finding that evening people tend to procrastinate more than morning people is consistent with previous research, the researchers said.​

​London, June 20 (IANS) Scientists have discovered unexpectedly high number of giant exoplanets in a cluster of stars called Messier 67 that is about the same age as the Sun -- indicating that our solar system might have arisen in a similarly dense environment.

The team used several telescopes and instruments, including the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph at European Southern Observatory's La Silla centre in Chile, to collect high-precision measurements of 88 stars in Messier 67. 

"We want to use an open star cluster as laboratory to explore the properties of exoplanets and theories of planet formation", said Roberto Saglia from the Max Planck Institutes in Germany who led the team. 

"Here we have not only many stars possibly hosting planets, but also a dense environment, in which they must have formed," Saglia added.

The study, published in the journal Astronomy and Astrophysics, found that hot Jupiters were more common around stars in Messier 67 than is the case for stars outside of clusters.

A hot Jupiter is a giant exoplanet with a mass of more than about a third of Jupiter's mass. They are "hot" because they orbit close to their parent stars, as indicated by an orbital period (their "year") that is less than 10 days in duration. 

"This is really a striking result," said Anna Brucalassi, who carried out the analysis. 

"The new results mean that there are hot Jupiters around some 5 per cent of the Messier 67 stars studied -- far more than in comparable studies of stars not in clusters, where the rate is more like 1 per cent," Brucalassi added.

​Tokyo, June 20 (IANS) In a first, an international team of astronomers has found firm evidence of the presence of oxygen in the early universe -- only 700 million years after the Big Bang.

Using the Atacama Large Millimetre/submillimetre Array (ALMA) telescope in Chile, the team including scientists from Japan, Sweden, Britain and European Southern Observatory found light from ionised oxygen in the SXDF-NB1006-2 galaxy -- making it the most distant unambiguous detection of oxygen ever obtained.

SXDF-NB1006-2 lies at a redshift of 7.2, meaning that we see it only 700 million years after the Big Bang.

Oxygen in SXDF-NB1006-2 was found to be 10 times less abundant than it is in the Sun, according to the study published recently in the journal Science. 

"The small abundance is expected because the universe was still young and had a short history of star formation at that time," said study co-author Naoki Yoshida from the University of Tokyo. 

"Our simulation actually predicted an abundance 10 times smaller than the Sun. But we have another, unexpected, result: a very small amount of dust," he added.

The detection of ionised oxygen indicates that many very brilliant stars, several dozen times more massive than the Sun, have formed in the galaxy and are emitting the intense ultraviolet light needed to ionise the oxygen atoms.

In the time before objects formed in the universe, it was filled with electrically neutral gas. But when the first objects began to shine, a few hundred million years after the Big Bang, they emitted powerful radiation that started to break up those neutral atoms -- to ionise the gas.

During this phase -- known as cosmic reionisation -- the whole universe changed dramatically. But there is much debate about exactly what kind of objects caused the reionisation. Studying the conditions in very distant galaxies can help to answer this question.

"SXDF-NB1006-2 would be a prototype of the light sources responsible for the cosmic reionisation," said lead author Akio Inoue from Osaka Sangyo University in Japan​