Doctor

Screen-addicted teens are unhappy

Posted on


180122091249_1_540x360

Happiness is not a warm phone, according to a new study exploring the link between adolescent life satisfaction and screen time. Teens whose eyes are habitually glued to their smartphones are markedly unhappier, said study lead author and San Diego State University and professor of psychology Jean M. Twenge.

To investigate this link, Twenge, along with colleagues Gabrielle Martin at SDSU and W. Keith Campbell at the University of Georgia, crunched data from the Monitoring the Future (MtF) longitudinal study, a nationally representative survey of more than a million U.S. 8th-, 10th-, and 12th-graders. The survey asked students questions about how often they spent time on their phones, tablets and computers, as well as questions about their in-the-flesh social interactions and their overall happiness.

On average, they found that teens who spent more time in front of screen devices — playing computer games, using social media, texting and video chatting — were less happy than those who invested more time in non-screen activities like sports, reading newspapers and magazines, and face-to-face social interaction.

Twenge believes this screen time is driving unhappiness rather than the other way around.

“Although this study can’t show causation, several other studies have shown that more social media use leads to unhappiness, but unhappiness does not lead to more social media use,” said Twenge, author of “iGen: Why Super-Connected Kids Are Growing Up Less Rebellious, More Tolerant, Less Happy — And Completely Unprepared for Adulthood.”

Total screen abstinence doesn’t lead to happiness either, Twenge found. The happiest teens used digital media a little less than an hour per day. But after a daily hour of screen time, unhappiness rises steadily along with increasing screen time.

“The key to digital media use and happiness is limited use,” Twenge said. “Aim to spend no more than two hours a day on digital media, and try to increase the amount of time you spend seeing friends face-to-face and exercising — two activities reliably linked to greater happiness.”

Looking at historical trends from the same age groups since the 1990s, the researchers found that the proliferation of screen devices over time coincided with a general drop-off in reported happiness in U.S. teens. Specifically, young people’s life satisfaction, self-esteem and happiness plummeted after 2012. That’s the year that the percentage of Americans who owned a smartphone rose above 50 percent, Twenge noted.

“By far the largest change in teens’ lives between 2012 and 2016 was the increase in the amount of time they spent on digital media, and the subsequent decline in in-person social activities and sleep,” she said. “The advent of the smartphone is the most plausible explanation for the sudden decrease in teens’ psychological well-being.”

Advertisements

Transformation to wind and solar achievable with low indirect GHG emissions

Posted on


171207141709_1_540x360

Different low carbon technologies from wind or solar energy to fossil carbon capture and sequestration (CCS) differ greatly when it comes to indirect greenhouse gas emissions in their life cycle. Unlike what some critics argue, the researchers not only found that wind and solar energy belong to the more favorable when it comes to life-cycle emissions. They also show that a full decarbonization of the global power sector by scaling up these technologies would induce only modest indirect greenhouse gas emissions — and hence not impede the transformation towards a climate-friendly power system.

“Both fossil and non-fossil power technologies still come with a certain amount of greenhouse gas emissions within their life cycle — on the one hand because it needs energy to construct and operate them, on the other hand because of methane emissions, e.g. from coal and gas production,” explains lead author Michaja Pehl. “However, we found there are substantial differences across technologies regarding their greenhouse gas balance. Electricity production from biomass, coal, gas and hydropower for instance induces much higher indirect greenhouse gas emissions than nuclear electricity, or wind and solar-based power supply.”

With their study the researchers provide an innovative and comprehensive global analysis of embodied energy use and indirect greenhouse gas emissions — from all relevant power sector technologies. For the first time, their study combines the strengths of simulations based on integrated energy-economy-climate models that estimate cost-optimal long-term strategies to meet climate targets with life cycle assessment approaches. So far, these research branches have operated separately. Exploring the life cycle emissions of future low-carbon supply systems and the implications for technology choices, they found that fossil power plants equipped with CCS will still account for life-cycle emissions of around 100 grams of CO2-equivalents per kWh of electricity produced, ten times more than the around 10 grams of CO2-equivalents for wind and solar power they project for 2050 in a climate protection scenario in which power production is almost completely decarbonized.

Wind and solar provide a much better greenhouse gas emissions balance than fossil-based technologies

“There is no such thing as truly clean coal. Conventional coal power currently comes with around 1000 grams of CO2-equivalents per kWh. Capturing CO2 from coal plants can reduce emissions per kWh by around 90 percent, but substantial life-cycle greenhouse gas emissions remain,” says Gunnar Luderer, energy system analyst from PIK and project leader. “To keep global warming below 2°C, however, virtually carbon free electricity is necessary. This makes it increasingly implausible that coal power will play a major role in the future, even if equipped with CO2 scrubbers.”

“When it comes to life cycle greenhouse gas emissions, wind and solar energy provide a much better greenhouse gas balance than fossil-based low carbon technologies, because they do not require additional energy for the production and transport of fuels, and the technologies themselves can be produced to a large extend with decarbonized electricity,” states Edgar Hertwich, an industrial ecologist from Yale University who co-authored the study. Due to technological innovation, less and less energy will be needed to produce wind turbines and solar photovoltaic systems.

“Some critics have argued renewable energies could come with high hidden greenhouse gas emissions that would negate their benefits to the climate. Our study now shows that the opposite is true,” concludes Luderer. “During the transition to clean power supply, the additional life-cycle emissions for building up wind and solar capacities are much smaller than the remaining emissions from existing fossil power plants before they can finally be decommissioned. The faster the low-carbon transformation of power supply is accomplished, the lower is the overall remaining carbon burden for the climate.”

CRISPR-Cas9 technique targeting epigenetics reverses disease in mice

Posted on


171207141644_1_540x360

Much of the enthusiasm around gene-editing techniques, particularly the CRISPR-Cas9 technology, centers on the ability to insert or remove genes or to repair disease-causing mutations. A major concern of the CRISPR-Cas9 approach, in which the double-stranded DNA molecule is cut, is how the cell responds to that cut and how it is repaired. With some frequency, this technique leaves new mutations in its wake with uncertain side effects.

In a paper appearing in the journal Cell on December 7, scientists at the Salk Institute report a modified CRISPR-Cas9 technique that alters the activity, rather than the underlying sequence, of disease-associated genes. The researchers demonstrate that this technique can be used in mice to treat several different diseases.

“Cutting DNA opens the door to introducing new mutations,” says senior author Juan Carlos Izpisua Belmonte of the Salk Institute for Biological Studies whose laboratory developed the new technique. “That is something that is going to stay with us with CRISPR or any other tool we develop that cuts DNA. It is a major bottleneck in the field of genetics — the possibility that the cell, after the DNA is cut, may introduce harmful mistakes.”

That fact guided every experiment in the Belmonte lab as they developed the technique using a modified CRISPR-Cas9 system that does not cut the DNA. Their findings are the first to provide evidence that one can alter the phenotype of an animal with a epigenetic editing technology, preserving DNA integrity.

The principal idea behind the Salk technique is the use of two adeno-associated viruses (AAVs) as the machinery to introduce their genetic manipulation machinery to cells in post-natal mice. The researchers inserted the gene for the Cas9 enzyme into one AAV virus. They used another AAV virus to introduce a short single guide RNA (sgRNA), which specifies the precise location in the mouse genome where Cas9 will bind, and a transcriptional activator. The shorter sgRNA is only 14 or 15 nucleotides compared with the standard 20 nucleotides used in most CRISPR-Cas9 techniques, and this prevents Cas9 from cutting the DNA.

“Basically, we used the modified guide RNA to bring a transcriptional activator to work together with the Cas9 and delivered that complex to the region of the genome we were interested in,” says co-first author Hsin-Kai Liao of the Belmonte laboratory.

The complex sits in the region of DNA of interest and promotes expression of a gene of interest. Similar techniques could be used to activate virtually any gene or genetic pathway without the risk of introducing potentially harmful mutations.

“We wanted to change the cell fate with therapeutic efficiency without a DNA cut,” co-first author Fumiyuki Hatanaka explains.

Strikingly, the team demonstrated disease reversal in several disease models in mice. In a mouse model of acute kidney disease, they showed that the technique activated previously damaged or silenced genes to restore normal kidney function. They were also able to induce some liver cells to differentiate into pancreatic ?-like cells, which produce insulin, to partially rescue a mouse model of type 1 diabetes.

The team also showed that they could recover muscle growth and function in mouse models of muscular dystrophy, a disease with a known gene mutation. Instead of trying to correct the mutated gene, the researchers increased the expression of genes in the same pathway as the mutated gene, over-riding the effect of the damaged gene. “We are not fixing the gene; the mutation is still there,” says Belmonte, “Instead, we are working on the epigenome and the mice recover the expression of other genes in the same pathway. That is enough to recover the muscle function of these mutant mice.”

Preliminary data suggest that the technique is safe and does not produce unwanted genetic mutations. However, the researchers are pursuing further studies to ensure safety, practicality, and efficiency before considering bringing it to a clinical environment.

Belmonte sees this technology as a way of potentially treating neurological disorders such as Alzheimer’s and Parkinson’s diseases. Just as the technique restored kidney, muscle, and insulin-producing function in the mouse models, he sees a future for rejuvenating neuronal populations.

Black holes’ magnetism surprisingly wimpy

Posted on


171207141644_1_540x360

Black holes are famous for their muscle: an intense gravitational pull known to gobble up entire stars and launch streams of matter into space at almost the speed of light.

It turns out the reality may not live up to the hype.

In a paper published today in the journal Science, University of Florida scientists have discovered these tears in the fabric of the universe have significantly weaker magnetic fields than previously thought.

A 40-mile-wide black hole 8,000 light years from Earth named V404 Cygni yielded the first precise measurements of the magnetic field that surrounds the deepest wells of gravity in the universe.

The measurements bring scientists closer to understanding how black holes’ magnetism works, deepening our knowledge of how matter behaves under the most extreme conditions — knowledge that could broaden the limits of nuclear fusion power and GPS systems.

The measurements also will help scientists solve the half-century-old mystery of how “jets” of particles traveling at nearly the speed of light shoot out of black holes’ magnetic fields, while everything else is sucked into their abysses, said study co-author Stephen Eikenberry, a professor of astronomy in UF’s College of Liberal Arts and Sciences.

“The question is, how do you do that?” Eikenberry said. “Our surprisingly low measurements will force new constraints on theoretical models that previously focused on strong magnetic fields accelerating and directing the jet flows. We weren’t expecting this, so it changes much of what we thought we knew.”

Study authors developed the measurements from data collected in 2015 during a black hole’s rare outburst of jets. The event was observed through the lens mirror of the 34-foot Gran Telescopio Canarias, the world’s largest telescope, co-owned by UF and located in Spain’s Canary Islands, with the help of its UF-built infrared camera named CIRCE (Canarias InfraRed Camera Experiment).

Smaller jet-producing black holes, like the one observed for the study, are the rock stars of galaxies. Their outbursts occur suddenly and are short-lived, said study lead author Yigit Dalilar and co-author Alan Garner, doctoral students in UF’s astronomy department. The 2015 outbursts of V404 Cygni lasted only a couple of weeks. The previous time the same black hole had a similar episode was in 1989.

“To observe it was something that happens once or twice in one’s career,” Dalilar said. “This discovery puts us one step closer to understanding how the universe works.”

‘Bandit-masked’ feathered dinosaur hid from predators using multiple types of camouflage

Posted on


 

Researchers from the University of Bristol have revealed how a small feathered dinosaur used its colour patterning, including a bandit mask-like stripe across its eyes, to avoid being detected by its predators and prey.

By reconstructing the likely colour patterning of the Chinese dinosaur Sinosauropteryx, researchers have shown that it had multiple types of camouflage which likely helped it to avoid being eaten in a world full of larger meat-eating dinosaurs, including relatives of the infamous Tyrannosaurus Rex, as well as potentially allowing it to sneak up more easily on its own prey.

Fiann Smithwick from the University’s School of Earth Sciences led the work,  He said: “Far from all being the lumbering prehistoric grey beasts of past children’s books, at least some dinosaurs showed sophisticated colour patterns to hide from and confuse predators, just like  animals.

“Vision was likely very important in dinosaurs, just like today’s birds, and so it is not surprising that they evolved elaborate colour patterns.” The colour patterns also allowed the team to identify the likely habitat in which the dinosaur lived 130 million years ago.

The work involved mapping out how dark pigmented feathers were distributed across the body and revealed some distinctive colour patterns.

These colour patterns can also be seen in modern animals where they serve as different types of camouflage.

The patterns include a dark stripe around the eye, or ‘bandit mask’, which in modern birds helps to hide the eye from would-be predators, and a striped tail that may have been used to confuse both predators and prey.

Senior author, Dr Jakob Vinther, added: “Dinosaurs might be weird in our eyes, but their colour patterns very much resemble modern counterparts.

“They had excellent vision, were fierce predators and would have evolved camouflage patterns like we see in living mammals and birds.”

The small dinosaur also showed a ‘counter-shaded’ pattern with a dark back and light belly; a pattern used by many modern animals to make the body look flatter and less 3D.

This stops animals standing out from their background, making them harder to spot, avoiding detection from would-be predators and potential prey.

Previous work on modern animals, carried out by one of the authors, Bristol’s Professor Innes Cuthill, has shown that the precise pattern of countershading relates to the specific environments in which animals live.

Animals living in open habitats, such as savannahs, often have a counter-shaded pattern that goes from dark to light sharply and high on the side of the body, while those living in more closed habitats, like forests, usually change from dark to light much lower and more gradually.

This principal was applied to Sinosauropteryx, and allowed for the reconstruction of its habitat 130 million years ago. The countershading on Sinosauropteryx went from dark to light high on the body, suggesting that it would be more likely to live in open habitats with minimal vegetation.

Behavioural ecologist Professor Cuthill, who was also a co-author of this study, said: “We’ve shown before that countershading can act as effective camouflage against living predators. It’s exciting that we can now use the colours of extinct animals to predict the sort of environment they lived in.”

Fiann Smithwick added: “By reconstructing the colour of these long-extinct dinosaurs, we have gained a better understanding of not only how they behaved and possible predator-prey dynamics, but also the environments in which they lived.

“This highlights how palaeocolour reconstructions can tell us things not possible from looking at just the bones of these animals.”

Scientists detect comets outside our solar system

Posted on


Scientists from MIT and other institutions, working closely with amateur astronomers, have spotted the dusty tails of six exocomets  comets outside our solar system  orbiting a faint star 800 light years from Earth.

These cosmic balls of ice and dust, which were about the size of Halley’s Comet and traveled about 100,000 miles per hour before they ultimately vaporized, are some of the smallest objects yet found outside our own solar system.

The discovery marks the first time that an object as small as a comet has been detected using transit photometry, a technique by which astronomers observe a star’s light for telltale dips in intensity. Such dips signal potential transits, or crossings of planets or other objects in front of a star, which momentarily block a small fraction of its light.

In the case of this new detection, the researchers were able to pick out the comet’s tail, or trail of gas and dust, which blocked about one-tenth of 1 percent of the star’s light as the comet streaked by.

“It’s amazing that something several orders of magnitude smaller than the Earth can be detected just by the fact that it’s emitting a lot of debris,” says Saul Rappaport, professor emeritus of physics in MIT’s Kavli Institute for Astrophysics and Space Research. “It’s pretty impressive to be able to see something so small, so far away.”

“Where few have traveled”

The detection was made using data from NASA’s Kepler Space Telescope, a stellar observatory that was launched into space in 2009. For four years, the spacecraft monitored about 200,000 stars for dips in starlight caused by transiting exoplanets.

To date, the mission has identified and confirmed more than 2,400 exoplanets, mostly orbiting stars in the constellation Cygnus, with the help of automated algorithms that quickly sift through Kepler’s data, looking for characteristic dips in starlight.

The smallest exoplanets detected thus far measure about one-third the size of the Earth. Comets, in comparison, span just several football fields, or a small city at their largest, making them incredibly difficult to spot.

However, on March 18, Jacobs, an amateur astronomer who has made it his hobby to comb through Kepler’s data, was able to pick out several curious light patterns amid the noise.

Jacobs, who works as an employment consultant for people with intellectual disabilities by day, is a member of the Planet Hunters — a citizen scientist project first established by Yale University to enlist amateur astronomers in the search for exoplanets. Members were given access to Kepler’s data in hopes that they might spot something of interest that a computer might miss.

In January, Jacobs set out to scan the entire four years of Kepler’s data taken during the main mission, comprising over 200,000 stars, each with individual light curves, or graphs of light intensity tracked over time. Jacobs spent five months sifting by eye through the data, often before and after his day job, and through the weekends.

“Looking for objects of interest in the Kepler data requires patience, persistence, and perseverance,” Jacobs says. “For me it is a form of treasure hunting, knowing that there is an interesting event waiting to be discovered. It is all about exploration and being on the hunt where few have traveled before.”

“Something we’ve seen before”

Jacobs’ goal was to look for anything out of the ordinary that computer algorithms may have passed over. In particular, he was searching for single transits — dips in starlight that happen only once, meaning they are not periodic like planets orbiting a star multiple times.

In his search, he spotted three such single transits around KIC 3542116, a faint star located 800 light years from Earth (the other three transits were found later by the team). He flagged the events and alerted Rappaport and Vanderburg, with whom he had collaborated in the past to interpret his findings.

“We sat on this for a month, because we didn’t know what it was — planet transits don’t look like this,” Rappaport recalls. “Then it occurred to me that, ‘Hey, these look like something we’ve seen before.'”

In a typical planetary transit, the resulting light curve resembles a “U,” with a sharp dip, then an equally sharp rise, as a result of a planet first blocking a little, then a lot, then a little of the light as it moves across the star. However, the light curves that Jacobs identified appeared asymmetric, with a sharp dip, followed by a more gradual rise.

Rappaport realized that the asymmetry in the light curves resembled disintegrating planets, with long trails of debris that would continue to block a bit of light as the planet moves away from the star. However, such disintegrating planets orbit their star, transiting repeatedly. In contrast, Jacobs had observed no such periodic pattern in the transits he identified.

“We thought, the only kind of body that could do the same thing and not repeat is one that probably gets destroyed in the end,” Rappaport says.

In other words, instead of orbiting around and around the star, the objects must have transited, then ultimately flown too close to the star, and vaporized.

“The only thing that fits the bill, and has a small enough mass to get destroyed, is a comet,” Rappaport says.

The researchers calculated that each comet blocked about one-tenth of 1 percent of the star’s light. To do this for several months before disappearing, the comet likely disintegrated entirely, creating a dust trail thick enough to block out that amount of starlight.

Vanderburg says the fact that these six exocomets appear to have transited very close to their star in the past four years raises some intriguing questions, the answers to which could reveal some truths about our own solar system.

“Why are there so many comets in the inner parts of these solar systems?” Vanderburg says. “Is this an extreme bombardment era in these systems? That was a really important part of our own solar system formation and may have brought water to Earth. Maybe studying exocomets and figuring out why they are found around this type of star … could give us some insight into how bombardment happens in other solar systems.”

The researchers say that in the future, the MIT-led Transiting Exoplanet Survey Satellite (TESS) mission will continue the type of research done by Kepler.

Apart from contributing to the fields of astrophysics and astronomy, Rappaport says, the new detection speaks to the perseverence and discernment of citizen scientists.

“I could name 10 types of things these people have found in the Kepler data that algorithms could not find, because of the pattern-recognition capability in the human eye,” Rappaport says. “You could now write a computer algorithm to find this kind of comet shape. But they were missed in earlier searches. They were deep enough but didn’t have the right shape that was programmed into algorithms. I think it’s fair to say this would never have been found by any algorithm.”

Martian landscapes formed from sand ‘levitating’ on a little boiling water

Posted on


Scientists from The Open University (OU) have discovered a process that could explain the long-debated mystery of how land features on Mars are formed in the absence of significant amounts of water.

Experiments carried out in the OU Mars Simulation Chamber — specialised equipment, which is able to simulate the atmospheric conditions on Mars — reveal that Mars’ thin atmosphere (about 7 mbar — compared to 1,000 mbar on Earth) combined with periods of relatively warm surface temperatures causes water flowing on the surface to violently boil. This process can then move large amounts of sand and other sediment, which effectively ‘levitates’ on the boiling water.

This means that, in comparison to Planet Earth, relatively small amounts of liquid water moving across Mars’ surface could form the large dune flows, gullies and other features, which characterise the Red Planet.

“Whilst planetary scientists already know that the surface of Mars has ‘mass-wasting’ features — such as dune flows, gullies, and recurring slope lineae — which occur as a result of sediment transportation down a slope, the debate about what is forming them continues.

“Our research has discovered that this levitation effect caused by boiling water under low pressure enables the rapid transport of sand and sediment across the surface. This is a new geological phenomenon, which doesn’t happen on Earth, and could be vital to understanding similar processes on other planetary surfaces.”

Dr Raack conducted these experiments in the Hypervelocity Impact (HVI) Laboratory based at the OU. He added:

“The sources of this liquid water will require more observational studies; however, the research shows that the effects of relatively small amounts of water on Mars in forming features on the surface may have been widely underestimated.

“We need to carry out more research into how water levitates on Mars, and missions such as the ESA ExoMars 2020 Rover will provide vital insight to help us better understand our closest neighbour.”