Teenagers in urban communities may have less aggressive behaviour if they live in neighbourhoods with more greenery, such as parks, golf courses or fields, a new study has found.
Researchers from University of Southern California (USC) in the US conducted the first longitudinal study to see whether greenery surrounding the home could reduce aggressive behaviours in a group of adolescents living in urban communities.
They followed 1,287 adolescents, aged nine to 18 years. They assessed the adolescents' aggressive behaviours every two to three years, asking parents if their child physically attacked or threatened others, destroyed things, or exhibited other similar behaviours.
Researchers then linked the adolescents' residential locations to satellite data to measure the levels of greenery in their neighbourhood.
The study found that nine to 18-year-olds who lived in places with more greenery had significantly less aggressive behaviours than those living in neighborhoods with less greenery.
Both short-term (one to six months) and long-term (one to three years) exposure to greenspace within 1,000 metres surrounding residences were associated with reduced aggressive behaviours, researchers said.
The behavioural benefit of greenspace equated to approximately two to two-and-a-half years of adolescent maturation, they said.
The study also found that factors such as age, gender, race/ethnicity, socioeconomic status, parents' educational background, occupation, income level, or marital status, and whether their mother smoked while pregnant or was depressed, did not affect the findings.
These benefits existed for both boys and girls of all ages and races/ethnicities, and across populations with different socioeconomic backgrounds and living in communities with different neighbourhood quality, researchers said.
"Identifying effective measures to reduce aggressive and violent behaviours in adolescents is a pressing issue facing societies worldwide," said Diana Younan from USC.
"It is important that we target aggressive behaviours early on. Our study provides new evidence that increasing neighbourhood greenery may be an effective alternative intervention strategy for an environmental public health approach that has not been considered yet," said Younan.
Researchers estimate that increasing greenery levels commonly seen in urban environments could result in a 12 per cent decrease in clinical cases of aggressive behaviour in adolescents living in urban areas.
The results support the benefits of greenery in decreasing aggressive behaviours for adolescents living in urban communities, researchers said.
The findings were published in the Journal of the American Academy of Child and Adolescent Psychiatry.
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Gravitational waves or ripples in space-time captured by space detectors could soon be used to discover when and how some of the universe's largest black holes were born, scientists say.
Scientists led by researchers at the Durham University in the UK ran the huge cosmological simulations that can be used to predict the rate at which gravitational waves caused by collisions between the monster black holes might be detected.
The amplitude and frequency of these waves could unveil the initial mass of the seeds from which the first black holes grew since they were formed 13 billion years ago and provide further clues about what caused them and where they formed, the researchers said.
The study combined simulations from the EAGLE project - which aims to create a realistic simulation of the known universe inside a computer - with a model to calculate gravitational wave signals.
Two detections of gravitational waves caused by collisions between supermassive black holes should be possible each year using space-based instruments such as the Evolved Laser Interferometer Space Antenna (eLISA) detector that is due to launch in 2034, the researchers said.
In February the international LIGO and Virgo collaborations announced that they had detected gravitational waves for the first time using ground-based instruments and this month reported a second detection.
As eLISA will be in space - and will be at least 250,000 times larger than detectors on Earth - it should be able to detect the much lower frequency gravitational waves caused by collisions between supermassive black holes that are up to a million times the mass of our Sun.
Current theories suggest that the seeds of these black holes were the result of either the growth and collapse of the first generation of stars in the universe; collisions between stars in dense stellar clusters; or the direct collapse of extremely massive stars in the early universe.
As each of these theories predicts different initial masses for the seeds of supermassive black hole seeds, the collisions would produce different gravitational wave signals.
This means that the potential detections by eLISA could help pinpoint the mechanism that helped create supermassive black holes and when in the history of the universe they formed.
"Understanding more about gravitational waves means that we can study the universe in an entirely different way," said lead author Jaime Salcido, PhD student in Durham University's Institute for Computational Cosmology.
"By combining the detection of gravitational waves with simulations we could ultimately work out when and how the first seeds of supermassive black holes formed," he said. Gravitational waves were first predicted 100 years ago by Albert Einstein as part of his Theory of General Relativity.
The waves are concentric ripples caused by violent events in the universe that squeeze and stretch the fabric of space time but most are so weak they cannot be detected.
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The Earth passed another unfortunate milestone when carbon dioxide levels surpassed 400 parts per million (ppm) at the South Pole for the first time in 4 million years, according to US scientists.
The South Pole has shown the same, relentless upward trend in carbon dioxide (CO2) as the rest of world, but its remote location means it is the last to register the impacts of increasing emissions from fossil fuel consumption, the primary driver of greenhouse gas pollution, researchers said.
"The far southern hemisphere was the last place on earth where CO2 had not yet reached this mark," said Pieter Tans, the lead scientist of US National Oceanic and Atmospheric Administration (NOAA)'s Global Greenhouse Gas Reference Network.
"Global CO2 levels will not return to values below 400 ppm in our lifetimes, and almost certainly for much longer," said Tans.
Over the course of the year, CO2 levels rise during fall and winter and decline during the Northern Hemisphere's summer as terrestrial plants consume CO2 during photosynthesis.
However, plants only capture a fraction of annual CO2 emissions, so for every year since observations began in 1958, there has been more CO2 in the atmosphere than the year before.
Last year's global CO2 average reached 399 ppm, meaning that the global average in 2016 will almost certainly surpass 400 ppm. The only question is whether the lowest month for 2016 will also remain above 400 metres, researchers said.
The annual rate of increase appears to be accelerating. The annual growth rate of atmospheric carbon dioxide measured at NOAA's Mauna Loa Observatory in Hawaii jumped 3.05 ppm during 2015, the largest year-to-year increase in 56 years of monitoring.
Part of last year's jump was attributable to El Nino, the cyclical Pacific Ocean warming that produces extreme weather across the globe, causing terrestrial ecosystems to lose stored CO2 through wildfire, drought and heat waves.
Last year was the fourth consecutive year that CO2 grew more than 2 ppm – which set another record. This year promises to be the fifth.
"We know from abundant and solid evidence that the CO2 increase is caused entirely by human activities," Tans said.
"Since emissions from fossil fuel burning have been at a record high during the last several years, the rate of CO2 increase has also been at a record high. And we know some of it will remain in the atmosphere for thousands of years," he said.
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Scientist have found the most distant galaxy with oxygen ever to be detected, seen just 700 million years after the Big Bang, which provides a glimpse into the early history of the universe.
Using the Atacama Large Millimetre/submillimetre Array (ALMA) in Chile, astronomers detected glowing oxygen in a distant galaxy.
The galaxy SXDF-NB1006-2 lies at a redshift of 7.2, meaning that we see it only 700 million years after the Big Bang, researchers said.
The team was hoping to find out about the heavy chemical elements present in the galaxy, as they can tell us about the level of star formation, and hence provide clues about the period in the early universe known as cosmic reionisation.
"Seeking heavy elements in the early universe is an essential approach to explore the star formation activity in that period," said Akio Inoue from the Osaka Sangyo University in Japan.
"Studying heavy elements also gives us a hint to understand how the galaxies were formed and what caused the cosmic reionisation," said Inoue.
In the time before objects formed in the universe, it was filled with electrically neutral gas.
However, 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.
Researchers carried out high-sensitivity observations with ALMA and found light from ionised oxygen in SXDF-NB1006-2, making this the most distant unambiguous detection of oxygen ever obtained.
It is firm evidence for the presence of oxygen in the early Universe, only 700 million years after the Big Bang.
Oxygen in SXDF-NB1006-2 was found to be ten times less abundant than it is in the Sun.
"The small abundance is expected because the universe was still young and had a short history of star formation at that time," said Naoki Yoshida at the University of Tokyo.
The team was unable to detect any emission from carbon in the galaxy, suggesting that this young galaxy contains very little un-ionised hydrogen gas, and also found that it contains only a small amount of dust, which is made up of heavy elements.
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.The findings were published in the journal Science.
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For the second time, scientists have directly detected gravitational waves created by the collision of two black holes 1.4 billion light years away, which once again confirms Einstein's theory of general relativity.
The scientists detected the gravitational waves - ripples through the fabric of the space-time continuum - using the twin Laser Interferometer Gravitational-wave Observatory (LIGO) interferometers in the US.
On December 26 last year both detectors, situated more than 3,000 kilometres apart, picked up a very faint signal amid the surrounding noise.
While LIGO's first detection, reported on February 11 this year, produced a clear peak in the data, this second signal was far subtler, generating a shallower waveform that was almost buried in the data, researchers said.
Using advanced data analysis techniques, the team determined that indeed, the waveform signaled a gravitational wave.
The researchers calculated that the gravitational wave arose from the collision of two black holes, 14.2 and 7.5 times the mass of the Sun.
The signal picked up by LIGO's detectors encompasses the final moments before the black holes merged.
For roughly the final second, while the signal was detectable, the black holes spun around each other 55 times, approaching half the speed of light, before merging in a collision that released a huge amount of energy in the form of gravitational waves, equivalent to the mass of the Sun.
This cataclysm, occurring 1.4 billion years ago, produced a more massive spinning black hole that is 20.8 times the mass of the Sun.
This second detection of gravitational waves, which once again confirms Einstein's theory of general relativity, successfully tested LIGO's ability to detect incredibly subtle gravitational signals.
"The fact of having seen another gravitational wave proves that indeed we are observing a population of binary black holes in the universe, said Salvatore Vitale, a research scientist at MIT and a LIGO team member.
LIGO's two interferometers, each four kilometres long, are designed in such a way that each detector should stretch by an infinitesimal amount if a gravitational wave were to pass through.
On September 14 last year, the detectors picked up the very first signal of a gravitational wave, which stretched each detector by as little as a fraction of a proton's diameter.
Just four months later, LIGO recorded a second signal, which stretched the detectors by an even smaller amount.
In its first four months, the Advanced LIGO detectors have already detected two signals of gravitational waves, produced by the collision of two very different binary black hole systems.
The research was published in the journal Physical Review Letters.
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Listening to a soothing Mozart symphony may significantly lower blood pressure and heart rate, a new study has claimed.
The study of the effect of different musical genres on the cardiovascular system found that the music of Mozart and Strauss is able to lower blood lipid concentrations and the heart rate.
Researchers Hans-Joachim Trappe and Gabriele Volt of Ruhr University Bochum in Germany considered 120 study participants: half of the subjects were exposed to music for 25 minutes.
Subdivided into three groups they were played recorded music by either W A Mozart, J Strauss Jr, or the pop band ABBA.
The remaining 60 subjects were allocated to a control group that spent their time in silence.
Before and after exposure to music and quiet time, respectively, all participants had their blood pressure, heart rate and cortisol concentration measured.
Classical music by Mozart and Strauss notably lowered blood pressure and heart rate, whereas no substantial effect was seen for the songs of ABBA.
In the control group, resting in a supine position, or lying with the face up, also resulted in blood pressure lowering, but the effect was far less pronounced than for exposure to the music of Mozart or Strauss.
All musical genres resulted in notably lower cortisol concentrations, researchers said.
As far as cortisol concentrations were concerned, the sex of the participants must have played a part, because the drop in cortisol levels was more pronounced in men than in women, especially after exposure to the music of Mozart and Strauss, they said.
Comparison with the control group showed that the effect of music was far greater than that of silence. The study was published in the journal Deutsches Arzteblatt International.
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In a first, scientists have discovered that fish are able to distinguish between human faces with a high degree of accuracy - an impressive feat, given this task requires sophisticated visual recognition capabilities.
"Being able to distinguish between a large number of human faces is a surprisingly difficult task, mainly due to the fact that all human faces share the same basic features," said Cait Newport, a research fellow at University of Oxford in the UK.
It has been hypothesised that this task is so difficult that it can only be accomplished by primates, which have a large and complex brain, researchers said.
The fact that the human brain has a specialised region used for recognising human faces suggests that there may be something special about faces themselves.
"To test this idea, we wanted to determine if another animal with a smaller and simpler brain, and with no evolutionary need to recognise human faces, was still able to do so," said Newport.
The researchers, including those from University of Queensland in Australia, found that fish, which lack the sophisticated visual cortex of primates, are nevertheless capable of discriminating one face from up to 44 new faces.
The research provides evidence that fish - vertebrates lacking a major part of the brain called the neocortex - have impressive visual discrimination abilities.
In the study, archerfish - a species of tropical fish well known for its ability to spit jets of water to knock down aerial prey - were presented with two images of human faces and trained to choose one of them using their jets.
The fish were then presented with the learned face and a series of new faces and were able to correctly choose the face they had initially learned to recognise.
They were able to do this task even when more obvious features, such as head shape and colour, were removed from the images.
The fish were highly accurate when selecting the correct face, reaching an average peak performance of 81 per cent in picking the previously learned face from 44 new faces and 86 per cent in second experiment in which facial features such as brightness and colour were standardised.
"We positioned a computer monitor that showed images of human faces above the aquariums and trained them to spit at a particular face," said Newport.
"Once the fish had learned to recognise a face, we then showed them the same face, as well as a series of new ones," she said.
In all cases, the fish continued to spit at the face they had been trained to recognise, proving that they were capable of telling the two apart, researchers said.
Even when we did this with faces that were potentially more difficult because they were in black and white and the head shape was standardised, the fish were still capable of finding the face they were trained to recognise, they said.
The study was published in the journal Scientific Reports.
Due to changing climate, Arctic regions of North America are getting greener, with almost a third of the land cover looking more like landscapes found in warmer ecosystems, according to a new NASA study.
With 87,000 images taken from Landsat satellites, converted into data that reflects the amount of healthy vegetation on the ground, the researchers found that western Alaska, Quebec and other regions became greener between 1984 and 2012.
The new Landsat study further supports previous work that has shown changing vegetation in Arctic and boreal North America.
Landsat is a programme that provides the longest continuous space-based record of Earth's land vegetation in existence.
"It shows the climate impact on vegetation in the high latitudes," said Jeffrey Masek, scientist at NASA's Goddard Space Flight Centre in the US.
Temperatures are warming faster in the Arctic than elsewhere, which has led to longer seasons for plants to grow in and changes to the soils.
Scientists have observed grassy tundras changing to shrublands, and shrubs growing bigger and denser - changes that could have impacts on regional water, energy and carbon cycles.
With Landsat 5 and Landsat 7 data, researchers found that there was extensive greening in the tundra of western Alaska, the northern coast of Canada, and the tundra of Quebec and Labrador.
While northern forests greened in Canada, they tended to decline in Alaska.
Overall, the scientists found that 29.4 per cent of the region greened up, especially in shrublands and sparsely vegetated areas, while 2.9 per cent showed vegetation decline.
Landsat, like other satellite missions, can use the amount of visible and near-infrared light reflected by the green, leafy vegetation of grasses, shrubs and trees to characterise the vegetation.
Then, with computer programmes that track each individual pixel of data over time, researchers can see if an area is greening - if more vegetation is growing, or if individual plants are getting larger and leafier.
If the vegetation becomes sparser, the scientists would classify that area as browning.
With finer-resolution and better calibrated data from Landsat, the researchers were able to mask out areas that burned, or are covered in water, to focus on vegetation changes.
"The resolution with Landsat is drastically improved, it lets you look at the local effects of things like topography, such as in areas where you might have small woodlands or open areas," Masek said.
The study was published in the journal Remote Sensing of Environment.
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Flowers may be losing their diverse and delicious fragrances, thanks to increasing temperatures associated with global climate change, scientists say.
Flowers produce scent to attract pollinating insects to the flowers' reproductive organs, thereby ensuring the continued existence of plant species.
To do this, flowers assemble a mixture of dozens, and sometimes hundreds, of volatile substances from several biochemical groups.
Scientists have known for some time that increasing temperatures associated with global climate change have a negative effect on plant growth.
Expanding on this research, scientists at Hebrew University of Jerusalem in Israel have shown that increases in ambient temperature also lead to a decrease in the production of floral scents.
"Increases in temperature associated with the changing global climate are interfering with plant-pollinator mutualism, an interaction facilitated mainly by floral colour and scent," said Alon Can'ani, a PhD student at Hebrew University of Jerusalem.
Can'ani studied control mechanisms that allow plants to regulate their production of smell, and is researching strategies to overcome the decrease in production of beneficial volatile substances, a process that requires a huge energy investment from plants.
He discovered that Petunia plants grown at elevated temperature conditions are significantly defected in production and emission of scent compounds.
Increasing ambient temperature leads to a decrease in phenylpropanoid-based floral scent production in two Petunia varieties, P720 and Blue Spark, Can'ani said.
This was linked to arrested expression and activity of proteins that facilitate biosynthesis of the compounds.
Can'ani also demonstrated an approach to bypass this adverse effect, by expressing the Arabidopsis thaliana PAP1 gene, which boosts the production of scent regardless of the ambient temperature.
He characterised the first gene (called PH4) that functions as a direct regulator of scent emission.
When he manipulated the expression of this gene to a halt, Petunia flowers ceased to emit scent, but continued to produce it.
This gene serves as a switch between two crucial floral traits - colour and scent.
The research was published in the journal Plant, Cell and Environment.
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Carbon planets consisting of graphite, carbides and diamonds possibly hosted life in the early universe, according to a new study.Scientists suggest that searching a rare class of stars might help find these diamond worlds.
Our Earth consists of silicate rocks and an iron core with a thin veneer of water and life. But the first potentially habitable worlds to form might have been very different, researchers said.
"This work shows that even stars with a tiny fraction of the carbon in our solar system can host planets," said Natalie Mashian, graduate student at the Harvard University in the US.
"We have good reason to believe that alien life will be carbon-based, like life on Earth, so this also bodes well for the possibility of life in the early universe," she said.
The primordial universe consisted mostly of hydrogen and helium, and lacked chemical elements like carbon and oxygen necessary for life as we know it.
Only after the first stars exploded as supernovae and seeded the second generation did planet formation and life become possible.
Researchers examined a particular class of old stars known as carbon-enhanced metal-poor stars, or CEMP stars.
These anaemic stars contain only one hundred-thousandth as much iron as our Sun, meaning they formed before interstellar space had been widely seeded with heavy elements.
"These stars are fossils from the young universe," said Avi Loeb from the Harvard-Smithsonian Centre for Astrophysics.
"By studying them, we can look at how planets, and possibly life in the universe, got started," Loeb said.
Although lacking in iron and other heavy elements compared to our Sun, CEMP stars have more carbon than would be expected given their age.
This relative abundance would influence planet formation as fluffy carbon dust grains clump together to form tar-black worlds.
From a distance, these carbon planets would be difficult to tell apart from more Earth-like worlds. Their masses and physical sizes would be similar. Astronomers would have to examine their atmospheres for signs of their true nature.
Gases like carbon monoxide and methane would envelop these unusual worlds.
Researchers said that a dedicated search for planets around CEMP stars can be done using the transit technique.
"This is a practical method for finding out how early planets may have formed in the infant universe," said Loeb.
"We'll never know if they exist unless we look," said Mashian.
The study was published in the journal Monthly Notices of the Royal Astronomical Society.
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