Tech

A program to reduce Earth's heat capture by injecting aerosols into the atmosphere from high-altitude aircraft is possible, but unreasonably costly with current technology, and would be unlikely to remain secret.

Those are the key findings of new research published today in Environmental Research Letters, which looked at the capabilities and costs of various methods of delivering sulphates into the lower stratosphere, known as stratospheric aerosol injection (SAI).

The researchers examined the costs and practicalities of a large scale, hypothetical 'solar geoengineering' project beginning 15 years from now. Its aim would be to halve the increase in anthropogenic radiative forcing, by deploying material to altitudes of around 20 kilometres.

They also discussed whether such an idealized program could be kept secret.

Dr Gernot Wagner, from Harvard University's John A. Paulson School of Engineering and Applied Sciences, is a co-author of the study. He said: "Solar geoengineering is often described as 'fast, cheap, and imperfect'.

"While we don't make any judgement about the desirability of SAI, we do show that a hypothetical deployment program starting 15 years from now, while both highly uncertain and ambitious, would be technically possible strictly from an engineering perspective. It would also be remarkably inexpensive, at an average of around $2 to 2.5 billion per year over the first 15 years."

The researchers confirm earlier studies that discuss the low direct costs of potential stratospheric aerosol geoengineering intervention, but they arrive at those numbers with the help of direct input from aerospace engineering companies in specifying what the paper dubs the 'SAI Lofter (SAIL)'.

Wake Smith, a co-author of the study, is a lecturer at Yale College and held former positions as CEO of Pemco World Air Services (a leading aircraft modification company), COO of Atlas Air Worldwide Holdings (a global cargo airline), and President of the flight training division of Boeing. He said: "I became intrigued by the engineering questions around SAI and the many studies that purport to show that modified existing planes could do the job. Turns out that is not so. It would indeed take an entirely new plane design to do SAI under reasonable albeit entirely hypothetical parameters. No existing aircraft has the combination of altitude and payload capabilities required."

Mr. Smith said: "We developed the specifications for SAIL with direct input from several aerospace and engine companies. It's equivalent in weight to a large narrow body passenger aircraft. But to sustain level flight at 20 kms, it needs roughly double the wing area of an equivalently sized airliner, and double the thrust, with four engines instead of two.

"At the same time, its fuselage would be stubby and narrow, sized to accommodate a heavy but dense mass of molten sulphur rather than the large volume of space and air required for passengers."

The team estimated the total development costs at less than $2 billion for the airframe, and a further $350 million for modifying existing low-bypass engines.

The new planes would comprise a fleet of eight in the first year, rising to a fleet of just under 100 within 15 years. The fleet would fly just over 4,000 missions a year in year one, rising to just over 60,000 per year by year 15.

Dr Wagner said: "Given the potential benefits of halving average projected increases in radiative forcing from a particular date onward, these numbers invoke the 'incredible economics' of solar geoengineering. Dozens of countries could fund such a program, and the required technology is not particularly exotic."

However, in the authors' view, this should not reinforce the often-invoked fear that a rogue country or operator might launch a clandestine SAI program upon an unsuspecting world.

Mr Smith said: "No global SAI program of the scale and nature discussed here could reasonably expect to maintain secrecy. Even our hypothesized Year one deployment program entails 4000 flights at unusually high altitudes by airliner-sized aircraft in multiple flight corridors in both hemispheres. This is far too much aviation activity to remain undetected, and once detected, such a program could be deterred."

Scientists have shown that the social insect Lasius niger (or black garden ant) changes its behavior following exposure to a fungus, a strategy that protects the most vulnerable and important members of the colony from infection. Their findings, which have been difficult for researchers to measure tangibly, provide the first evidence that animal social networks can adapt to decrease the spread of disease. Here, Nathalie Stroeymeyt and colleagues tested whether colonies change their patterns of social contact in response to the threat of infection by developing an automated tracking system that zeroed in on 22 colonies for 24 hours. They closely studied the movement of both individual ants exposed to Metarhizium brunneum spores and of their unexposed nestmates, comparing social network activities before and after introduction of the spores. Interestingly, not only did infected workers alter their behavior after exposure, but healthy workers altered their behavior toward their infected counterparts, the authors found. They observed that both exposed and unexposed workers maintained their distance from indoor workers by active isolation - increasing their time outside away from the nest. Indoor workers, too, increased their movement to avoid further interaction with colony members. Stroeymeyt et al. saw that such responses kept fungal infection at bay. The responses among the ants were potentially triggered by chemical or mechanical cues associated with Metarhizium brunneum spores, they say, though additional research is needed to better grasp the underlying detection processes involved. The ants' ability to adopt a flexible social network on demand may represent a widespread tactic to survive environmental hazards, according to the authors, minimizing risk to high-value colony members including the queen and young workers.

While probiotics are often used to treat acute gastroenteritis (also known as infectious diarrhea) in children, the latest evidence shows no significant differences in outcomes, compared to a placebo. These results come from the large, double-blind, randomized controlled trial conducted at 10 geographically diverse U.S. pediatric emergency departments, including Kenneth & Anne Griffin Emergency Care Center at Ann & Robert H. Lurie Children's Hospital of Chicago. Findings were published in the New England Journal of Medicine.

"This study presents the most robust evidence to date that use of probiotics does not improve outcomes of acute gastroenteritis in children, which calls into question current recommendations," says author Elizabeth Powell, MD, MPH, pediatric emergency medicine specialist at Lurie Children's and Professor of Pediatrics at Northwestern University Feinberg School of Medicine. "Recommendations to use probiotics for these patients were based on previous meta-analyses that have suggested probiotics may be beneficial, but the trials that were included had significant limitations. The rigor of our research design and our results warrant reconsideration of common practice."

Acute gastroenteritis, which can present with diarrhea, vomiting and abdominal pain, accounts for approximately 1.7 million visits to the emergency department and more than 70,000 hospitalizations per year in the U.S. It is the second leading cause of death worldwide in children younger than 5 years.

The study included 943 children, aged 3 months to 4 years of age. Two weeks after an emergency department visit for acute gastroenteritis, children in the study who received a five-day course of probiotic (Lactobacillus rhamnosus) fared no better than the placebo group in terms of illness severity, duration and frequency of diarrhea or vomiting, day-care absenteeism and rate of household transmission of the infection.

The lucrative truffle industry is set to disappear within a generation due to climate change, according to new research by a University of Stirling academic.

A warmer and drier climate will be responsible for the decline - which will have a "huge economic, ecological and social impact" - and could be accelerated by other factors, such as heatwave events, forest fires, pests and diseases.

With the truffle species Tuber melanosporum trading at more than £1,000 per kilogram, the industry is worth hundreds of millions of pounds. Estimates have suggested that it could reach as much as £4.5 billion over the next 10 to 20 years, but the new study suggests a bleaker future for the sector.

Dr Paul Thomas, from the Faculty of Natural Sciences at Stirling, led the research, which is the first study to consider the future threat of climate change on European truffle production.

He said: "Our new study predicts that, under the most likely climate change scenario, European truffle production will decline by between 78 and 100 per cent between 2071 and 2100.

"However, the decline may well occur in advance of this date, when other climate change factors are taken into account, such as heatwaves, forest fires, drought events, pests and disease.

"We risk losing an industry worth hundreds of millions of pounds to the economy. However, the socio-economic impact of the predicted decline could be substantially larger as truffle harvesting and related activities form a key component of local history and cultural activity."

Dr Thomas, working with Professor Ulf Bu?ntgen at the University of Cambridge, studied continuous records, spanning 36 years, of Mediterranean truffle yield in France, Spain and Italy.

The team correlated the data with local weather conditions to assess the impact of climate on production - and combined the results with state-of-the-art climate model projections to predict the likely impact of climate change on truffle yields.

"This is a wake-up call to the impacts of climate change in the not-too-distant future," Dr Thomas said. "These findings indicate that conservational initiatives are required to afford some protection to this important and iconic species. Potential action could include the expansion of truffle plantations into new territories of a more favourable future climate.

"Management strategies should further include mulching materials and cultivation practices to mitigate soil temperature fluctuations and conserve soil moisture."

Research led by a University of Sussex scientist has turned a 156-year-old law of physics on its head in a development which could lead to more efficient recharging of batteries in cars and mobile phones.

Dr Jordi Prat-Camps, a research fellow at the University of Sussex, has for the first time demonstrated that the coupling between two magnetic elements can be made extremely asymmetrical. Working with colleagues from the Austrian Academy of Sciences and University of Innsbruck, Dr Prat-Camps' research rips up the physics rule book by showing it is possible to make one magnet connect to another without the connection happening in the opposite direction.

The findings run contrary to long-established beliefs of magnetic coupling, which emerge from the four Maxwell equations dating back to the seminal works of Michael Faraday and James Clerk Maxwell in the 19th century.

Dr Prat-Camps said: "We have created the first device that behaves like a diode for magnetic fields. Electric diodes are so crucial that none of the existing electronic technologies such as microchips, computers or mobile phones would be possible without them. If our result for magnetic fields would have one millionth of the same impact as the developments in electric diodes, it would be a hugely impactful success. The creation of such a diode opens up a lot of new possibilities for other scientists and technicians to explore. Thanks to our discovery we think it might be possible to improve and the performance of wireless power transfer technologies to improve the efficiency of recharging phones, laptops and even cars."

Dr Prat-Camps' breakthrough builds on research he and colleagues have carried out over a number of years focusing on the control and manipulation of magnetic fields by the use of metamaterials. Recently Dr Prat-Camps and his collaborators have developed new tools to control magnetism including magnetic undetectability cloaks, magnetic concentrators and wormholes.

As other researchers working with other kinds of metamaterials explored the possibility of breaking reciprocity for light and sound waves, Dr Prat-Camps explored whether the same challenge could be applied to magnetic fields.

After several unsuccessful attempts to break magnetic reciprocity, the team decided to try using an electrical conductor in movement. By solving Maxwell's equations analytically, the researchers very quickly demonstrated that not only could reciprocity be broken down but that, the coupling could be made maximally asymmetric, whereby the coupling from A to B would be different from zero but from B to A it would be exactly zero. Having shown that total unidirectional coupling was possible theoretically, the team designed and built a proof-of-concept experiment which confirmed their findings.

Dr Prat-Camps said: "The magnetic coupling between magnets or circuits is something extremely well-known. It dates back to the seminal works of Faraday and Maxwell and it is deeply embedded into the four Maxwell equations that describe all electromagnetic phenomena. A vast majority of the technologies we rely on today are based on magnetic coupling including motors, transformers, low-frequency antennas and wireless power transfer devices. As far as we know, nobody before us thought to ask whether this symmetry could be broken and to what extent."

The researchers are hopeful the findings could have wide implications. Technology reliant on magnetically-based wireless power transfer includes the vast majority of everyday electronic devices like mobile phones and laptops.

Innsbruck physicists Oriol Romero-Isart and Gerhard Kirchmair said: "If the coupling between coils is symmetric, some part of the energy can also flow in the opposite direction which can greatly reduce the efficiency of the transfer. By using a magnetic diode to prevent this backwards flow, the efficiency of the transfer could be greatly enhanced."

The findings suggest that fruit and other foods containing fructose seem to have no harmful effect on blood glucose levels, while sweetened drinks and some other foods that add excess "nutrient poor" energy to diets may have harmful effects.

"These findings might help guide recommendations on important food sources of fructose in the prevention and management of diabetes," said Dr. John Sievenpiper, the study's lead author and a researcher in the Clinical Nutrition and Risk Factor Modification Centre of St. Michael's Hospital in Toronto, Canada. "But the level of evidence is low and more high quality studies are needed."

The role of sugars in the development of diabetes and heart disease attracts widespread debate and increasing evidence suggests that fructose could be particularly harmful to health.

Fructose occurs naturally in a range of foods, including whole fruits and vegetables, natural fruit juices and honey. It is also added to foods, such as soft drinks, breakfast cereals, baked goods, sweets, and desserts as 'free sugars'.

Current dietary guidelines recommend reducing free sugars, especially fructose from sweetened beverages, but it is unclear whether this holds for all food sources of these sugars.

So researchers based at St. Michael's and the University of Toronto in Canada analysed the results of 155 studies that assessed the effect of different food sources of fructose sugars on blood glucose levels in people with and without diabetes monitored for up to 12 weeks.

Results were based on four study designs: substitution (comparing sugars with other carbohydrates), addition (energy from sugars added to diet), subtraction (energy from sugars removed from diet), or ad libitum (energy from sugars freely replaced).

Outcomes were glycated haemoglobin or HbA1c (amount of glucose attached to red blood cells), fasting glucose, and fasting insulin (blood glucose and insulin levels after a period of fasting).

Studies were also assessed for bias and certainty of evidence. Overall, no serious risk of bias was detected, but the certainty of evidence was low.

The results show that most foods containing fructose sugars do not have a harmful effect on blood glucose levels when these foods do not provide excess calories. However, a harmful effect was seen on fasting insulin in some studies.

Analysis of specific foods suggest that fruit and fruit juice when these foods do not provide excess calories may have beneficial effects on blood glucose and insulin control, especially in people with diabetes, whereas several foods that add excess "nutrient poor" energy to the diet, especially sweetened drinks and fruit juice, seem to have harmful effects.

The low glycaemic index (GI) of fructose compared with other carbohydrates, and higher fibre content of fruit, may help explain the improvements in blood glucose levels, by slowing down the release of sugars, say the researchers.

They point to some limitations, such as small sample sizes, short follow-up periods, and limited variety of foods in some studies. However, strengths included an in-depth search and selection process and thorough assessment of evidence quality.

As such, they conclude: "Until more information is available, public health professionals should be aware that harmful effects of fructose sugars on blood glucose seem to be mediated by energy and food source."

The availability of a key prey for seabirds has changed dramatically over the past three decades, particularly in winter, with possible consequences for their population numbers, a new study has found.

In the first long-term study of its kind, led by the Centre for Ecology & Hydrology, researchers looking at the diet of a North Sea seabird, the European shag, found that the birds' food source has altered substantially throughout the year.

In 1988, shags' diets comprised almost 100 per cent sandeel, but by 2014 this had reduced to just 13 per cent, while the number of prey types increased from six to 12, the study of regurgitated pellets all-year-round over three decades at the Isle of May, Firth of Forth, has found.

Climate change may be an important mechanism driving the observed patterns, since ocean warming is having pronounced impacts on fish populations in the North Sea.

The availability of prey and change in diet can affect seabirds' survival rates and therefore populations because food is a key determinant of their biology, affecting their general health and condition plus the number of chicks they raise.

As sandeel were considered one of the most favourable prey types in the North Sea, the increasing contribution of other fish to the diet may have important implications for shags and other seabirds.

Crucially, the study by the Centre for Ecology & Hydrology, University of Liverpool and Biomathematics & Statistics Scotland, which is published today in the journal Marine Biology, demonstrated that the decline in sandeel frequency in the diet was more marked during winter, when the majority of seabird deaths occur.

Therefore, the dietary patterns observed may have substantial implications for survival and may be an important factor contributing to the declines observed in some UK seabird populations, according to the researchers who carried out the study, which was funded by the Natural Environment Research Council.

Lead author Richard Howells of the Centre for Ecology & Hydrology explained that while previous research had been done during summer, when birds are at their nests and relatively easy to access, there had been limited information regarding seabird diet during the energetically challenging winter months and how these have changed over time, until now.

He said: "Our study addresses key knowledge gaps not only in the understanding of how birds are responding to the environmental impacts of climate change but also the factors underpinning the steep declines observed in many species.

"The overall picture for seabirds is a marked decline, particularly those who have traditionally relied upon sandeels."

Mr Howells said that by exploiting a wider range of prey - such as codfishes, sculpins and flatfish - shags may be partly buffered to the predicted future impacts of climate-linked environmental change, although other seabird species may not have such flexibility.

However, he added that because they have to travel to different areas to find food than in the past, this may bring them into contact with potential new threats, such as tidal renewable developments.

Although populations of some birds have increased in recent years, all monitored seabird species apart from the cormorant have been Red or Amber listed.

The Joint Nature Conservation Committee (JNCC) estimates that the UK's European shag population fell by 45 per cent between 1986 and 2015, kittiwakes by 60 per cent and Arctic skua by 76 per cent. Worldwide, the overall seabird population declined by 70 per cent between 1950 and 2010, according to research by the University of British Columbia.

Rodent mothers produce more offspring after smelling odors produced by frightened males. This is reported by a team of biologists from Finland and the Netherlands and bring new information the proximate and ultimate explanations of small mammal behavioral responses.

Fear of being eaten has the power to shape populations and drive evolution. The effect the authors report is large: exposed mothers produce litters with about fifty percent more pups compared to unexposed control mothers.

What is most striking about this study is that the cause of the change in numerical reproduction was indirect, says postdoctoral researcher Marko Haapakoski from the University of Jyväskylä, Finland. Second-hand information about predators was sufficient to increase the number of offspring, he continues.

Chemical messages

Predation involves more than just predators consuming prey.

Predators can also scare the living daylights out of the animals they target. Our study demonstrates that the resulting fear changes how these prey animals behave and reproduce, explains Dr. Kevin Matson from Wageningen University, The Netherlands.

The study shows that a frightening experience can be communicated to neighboring individuals in the population, even when the neighbors do not see, smell, or hear an actual predator themselves.

When a separate group of male voles were exposed to a weasel, they produced chemical messages that could be read by the voles in our study, explains Alwin Hardenbol, who conducted this research as part of his master's thesis at Wageningen University, The Netherlands.

Vole mothers might produce more offspring when they sense their chances of being eaten soon are high and that their next litter may be their last. Simple physiological mechanisms could allow mothers to adjust litter size. For example, previous research has shown that females can produce more pups simply by mating with more males.

Implications of the findings

Danielle Lee of the Southern Illinois University (USA), an ecologist specializing in rodent behavior and who is unaffiliated with this research project, described the significance of this research.

This innovative experimental study bridges the proximate and ultimate explanations of small mammal behavioral responses. It's been long hypothesized that small, highly fecund (so called "r-selected") species like voles might respond to heavy predation via reproductive compensation. This field study shows how these responses are mediated via chemo-olfactory cues, she says. The work demonstrates once again the importance of this modality for intraspecific communication, population regulation, and trophic interactions, she continues.

In the era of personalized medicine, scientists are using new genetic and genomic insights to help them determine the best treatment for a given patient. In the case of cancer, the first step toward these treatments is an investigation into how tumor cells behave in an effort to figure out the best drugs to use to attack them.

Researchers then use DNA- and RNA- sequencing to look at populations of cells, examining which genes are expressed within a sample of cancerous tissue. However, traditional sequencing methods can hide that fact that not all tumor cells necessarily behave in the same way. Not recognizing this means that if you target a tumor with a specific type of drug, some cells may be just different enough to survive and thrive.

In a major advance for genomics, it is now possible to look at what one single cell is doing at any given time with a technique called single-cell RNA sequencing (scRNA-seq). This method looks at the amount of messenger RNAs (mRNAs) in a cell and compares those to other cells to look for differences in gene expression.

However, what information you find can depend on how your run your experiment and how the data are analyzed. Lana Garmire, Ph.D., associate professor of the department of computational medicine & bioinformatics at Michigan Medicine and her team is studying ways to eliminate some of the biases that can make interpreting scRNA-seq data difficult.

"A lot of the noise in this type of sequencing comes from the fact that you have to measure samples in extreme low quantities and in different batches," she explains. For example, the tissue sample a researcher is analyzing may not fit on one plate, a piece of equipment used to house cell samples, and therefore have to be split onto two plates. Differences that arise due to this split are called batch effects. Genomics researchers must correct for these batch effects, but this process can raise a conundrum: how do you know if a difference is a batch effect or a true difference between cells?

New uses for data

Bioinformatics is the term for collecting and analyzing complex biological data using computer programs. It is a relatively new field born out of the ability to gather enormous amounts of biological data, such as DNA and protein sequences.

Researchers rely on bioinformatics techniques to determine which genes are expressed in single cells. But they've had to work around the noise introduced through different research protocols and batch effects. Garmire, who recently joined U-M from the University of Hawaii and is the new faculty director University of Michigan Medical School Bioinformatics Core, has discovered a more efficient way of identifying differences between cells using the same set of data produced during sequencing experiments. Instead of relying on gene expression, she found that looking at what are known as single nucleotide variants (SNVs) can eliminate some of this uncertainty. "With SNVs, you are dealing with numbers that are binary, 0 and 1. Either the mutation is there or not."

Recall that genes are made up of nucleotides represented by the letters A, T, G and C that make up a code that is translated into a protein. Garmire's method looks for differences in single nucleotides, knowing that an A can only be replaced by a T and a G by a C. This new work, described in Nature Communications, developed a new set of procedures to process scRNA-seq data and retrieve this variant information. Further, using a computer program called SSrGE, they can link this variant information to more traditional gene expression information.

"This gives us information on different subpopulations of tumor cells and becomes sort of like a fingerprint that can be marked to identify cell-to-cell differences," says Garmire.

What it all means

Ultimately, drug makers and clinicians use these targets to guide pharmaceutical treatments. "When you want to attack the issue, you go at it by attacking the fundamental features of that issue: the mutations. Clinicians may be able to use this information later on to guide their therapeutics." Garmire looks forward to bringing bioinformatics out of the lab, helping researchers who amass large amounts of data to use them and develop downstream clinical applications. "We divide the body up and specialize but at the end of the day, you need to look holistically and ask, what am I doing and who is this helping? We are developing computational tools to bring bioinformatics researchers and bench scientists and clinicians together to connect the dots and ultimately make change.

Colorectal cancer is the third most common form of cancer in the world. Every year in Finland, approximately 3,000 new cases are diagnosed, and roughly 1,200 patients die of it. Between 2004 and 2016, an extensive screening programme was conducted in Finland, intending to study the potential benefits and downsides of a nation-wide screening for colorectal cancer.

The study targeted people aged 60-69 years, and just under a half of the age group, or a little more than 300,000 people, were randomised by late 2011. Half of the population in the study were invited for screening, while the other half of the age cohort served as a control group. Faecal occult blood tests (FOBT) were used in the screening, and patients who tested positive for blood were referred for a colonoscopy.

The first study based on the screening results indicated no significant decrease in mortality, so the screenings were discontinued after 2016. However, researchers from the Helsinki University Hospital and the Finnish Cancer Registry wanted to examine whether the screening had offered benefits to patients with colorectal cancer.

"Practically no cancer screenings have been found to have an impact on overall mortality. However, they may still be useful in other ways. We wanted to study whether the patients could avoid the more intense treatments if they participated in screening for colorectal cancer," says Dr. Laura Koskenvuo, gastrointestinal surgeon.

The study examined the data of approximately 1,400 patients diagnosed with colorectal cancer. The results indicated that among patients from the screening group, the surgical removal of the entire tumour was more commonly successful than it was among the control group patients, and they were less likely to require chemotherapy. The patients from the screening group were also less likely to undergo emergency surgery because of their tumour than the control group patients.

"The control group had 50% more emergency surgeries, 40% more incomplete tumour removals and 20% more chemotherapy treatments than patients in the screening group," says Adjunct Professor Ville Sallinen, gastrointestinal surgeon.

Closer inspection of the results showed that these benefits were particularly prevalent among male patients. Similar benefits were not seen among women. Additionally, the researchers found that the screening was most efficient at detecting left-sided colorectal cancer and the screening was found to have no benefit for patients with cancer on the right side, possibly because blood seeping from tumours on the right side becomes so diluted as it travels through the colon that the gFOBT can no longer detect it.

"The strength of this Finnish study is that it randomised an enormous number of people in the public health care system, which meant that we could objectively evaluate the benefits of the screening. Similar studies have not been available anywhere else," says Professor Nea Malila, director of the Finnish Cancer Registry.

"In the future, we must examine whether different screening techniques could improve the situation of female patients and facilitate the diagnosis of right-sided colorectal cancer," the researchers state.

PROVIDENCE, R.I. [Brown University] -- Brown University researchers have shown a way to use graphene oxide (GO) to add some backbone to hydrogel materials made from alginate, a natural material derived from seaweed that's currently used in a variety of biomedical applications. In a paper published in the journal Carbon, the researchers describe a 3-D printing method for making intricate and durable alginate-GO structures that are far stiffer and more fracture resistant that alginate alone.

"One limiting factor in the use of alginate hydrogels is that they're very fragile -- they tend to fall apart under mechanical load or in low salt solutions," said Thomas Valentin, a Ph.D. student in Brown's School of Engineering who led the work. "What we showed is by including graphene oxide nanosheets, we can make these structures much more robust."

The material is also capable of becoming stiffer or softer in response to different chemical treatments, meaning it could be used to make "smart" materials that are able to react to their surroundings in real time, the research shows. In addition, alginate-GO retains alginate's ability to repel oils, giving the new material potential as a sturdy antifouling coating.

The 3-D printing method used to make the materials is known as stereolithography. The technique uses an ultraviolet laser controlled by a computer-aided design system to trace patterns across the surface of a photoactive polymer solution. The light causes the polymers to link together, forming solid 3-D structures from the solution. The tracing process is repeated until an entire object is built layer-by-layer from the bottom up. In this case the polymer solution was made using sodium alginate mixed with sheets of graphene oxide, a carbon-based material that forms one-atom-thick nanosheets that are stronger pound-for-pound than steel.

One advantage to the technique is that the sodium alginate polymers link through ionic bonds. The bonds are strong enough to hold the material together, but they can be broken by certain chemical treatments. That gives the material the ability to respond dynamically to external stimuli. Previously, the Brown researchers showed that this "ionic crosslinking" can be used to create alginate materials that degrade on demand, rapidly dissolving when treated with a chemical that sweeps away ions from the material's internal structure.

For this new study, the researchers wanted to see how graphene oxide might change mechanical properties of alginate structures. They showed that alginate-GO could be made twice as stiff as alginate alone, and far more resistant to failure through cracking.

"The addition of graphene oxide stabilizes the alginate hydrogel with hydrogen bonding," said Ian Y. Wong, an assistant professor of engineering at Brown and the paper's senior author. "We think the fracture resistance is due to cracks having to detour around the interspersed graphene sheets rather than being able to break right though homogeneous alginate."

The extra stiffness enabled the researchers to print structures that had overhanging parts, which would have been impossible using alginate alone. Moreover, the increased stiffness didn't prevent alginate-GO also from responding to external stimuli like alginate alone can. The researchers showed that by bathing the materials in a chemical that removes its ions, the materials swelled up and became much softer. The materials regained their stiffness when ions were restored through bathing in ionic salts. Experiments showed that the materials' stiffness could be tuned over a factor of 500 by varying their external ionic environment.

That ability to change its stiffness could make alginate-GO useful in a variety of applications, the researchers say, including dynamic cell cultures.

"You could imagine a scenario where you can image living cells in a stiff environment and then immediately change to a softer environment to see how the same cells might respond," Valentin said. That could be useful in studying how cancer cells or immune cells migrate through different organs throughout the body.

And because alginate-GO retains the powerful oil-repellant properties of pure alginate, the new material could make an excellent coating to keep oil and other grime from building up on surfaces. In a series of experiments, the researchers showed that a coating of alginate-GO could keep oil from fouling the surface of glass in highly saline conditions. That could make alginate-GO hydrogels useful for coatings and structures used in marine settings, the researchers say.

"These composite materials could be used as a sensor in the ocean that can keep taking readings during an oil spill, or as an antifouling coating that helps to keep ship hulls clean," Wong said. The extra stiffness afforded by the graphene would make such materials or coatings far more durable than alginate alone.

The researchers plan to continue experimenting with the new material, looking for ways to streamline its production and continue to optimize its properties.

While trying e-cigarettes may prompt some young people to take up smoking at the individual level, there is little evidence that this is the case at the population level, conclude the researchers. And these findings are consistent over several years, they emphasise.

Earlier this year, the National Academies of Sciences, Engineering and Medicine published a report which concluded there was "substantial evidence" that vaping among young people is strongly associated with progression to smoking.

But the report also noted that recent increases in the popularity of e-cigarettes have been associated with falling smoking rates among this age group.

To try and explore these trends in more depth and settle the question of whether vaping might act as a gateway to smoking, the researchers carried out a time trend analysis, using publicly available data up to and including 2017.

They first drew on nationally representative surveys on vaping and tobacco use for 15-25 year olds, as this is the age group most likely to start and/or progress to regular smoking.

They then looked at smoking patterns among teens and young adults, going back as far as 2004, to gauge smoking trends before e-cigarette use became popular.

They used responses to five different national surveys. Where information was available, they included any cigarette use during the preceding 30 days as well as established use-defined as daily/half a pack a day/100 cigarettes smoked to date and currently smoking some days.

The responses revealed that vaping prevalence was low between 2011 and 2013, but reached much higher levels by 2014, so this was identified as the tipping point when vaping became popular among teens and young adults.

The choice of this date is backed up by retail sales data, which recorded a more than doubling in sales in 2014, and by the percentage of adults switching from cigarettes to e-cigarettes, which also doubled between 2012-13 and 2013-14.

The analysis showed that the downward trend in smoking prevalence among young people in the US sped up after 2013, just as vaping was becoming more widespread, and that this was particularly evident among 18-21 year olds.

The analysis also showed that the decline in more established smoking sped up sharply when vaping prevalence increased. And the proportion of those who said they had smoked within the past 30 days, which had fallen slowly throughout 2012, fell more steeply (two to four times) once vaping became popular.

The findings were consistent across different surveys, suggesting that the results were reliable despite different methods of data collection, and after correcting for data input anomalies.

The researchers suggest that the increase in smoking prevalence in tandem with vaping prevalence, found by other researchers, may nevertheless be consistent with their findings.

"It is possible that trying e-cigarettes is causally related to smoking for some youth, but the aggregate effect of this relationship at the population level may be small enough that its effects are swamped by other factors that influence smoking behaviour," they suggest.

These factors could include media campaigns and tobacco control policies: further research would be needed to distinguish between their potential role and the rise in popularity of vaping, they add.

This is an observational study, and as such, can't establish cause. And as the analyses were all done using US data, the findings may not be applicable elsewhere, caution the researchers.

"While caution is warranted in interpreting our findings, they paint a consistent picture of accelerated reductions in youth and young adult smoking prevalence as vaping became more widespread," they write.

And referring to the National Academies report, they add: "In our view, it is premature to conclude that the observed increased rate of decline in smoking is due to vaping diverting youth from smoking, although it is a plausible explanation."

They conclude: "If our primary concern is population level trends in youth and young adult smoking, which we believe is appropriate, then vaping has not shown to be a serious cause for concern....and may be playing a contributing role to the recent steep declines in youth and young adult smoking."

Energy, calmness, empathy, maturity and intellectual curiosity may be protective, while impulsivity may harm the chances of longevity, the findings indicate.

Previous research suggests that personality traits in mid-life may predict the probability of dying earlier or later. But it's not clear if the potential seeds of this association might go back even further, as has already been suggested for IQ and family background.

To explore this further, the researchers drew on data compiled for the Project Talent Study, a nationally representative sample of 5 per cent (1226) of all US high (secondary) schools in 1960.

Some 377,016 pupils, mostly ranging in age from 13 (9th grade) to 18 (12th grade) completed a battery of psychological tests and questionnaires over two days at that time.

The information sought, included family background-parents' educational attainment and job titles, income, housing and property ownership-as well as 10 personality traits, measured by the Project Talent Personality Inventory (PTPI), and considered important for lifetime success.

These were calmness; social sensitivity (empathy and sensitivity to other people's feelings); impulsivity; leadership (responsibility and self-determination); vigour (energetic disposition); self-confidence; tidiness (preference for organisation and order); sociability (outgoing disposition); culture (intellectual curiosity); and mature personality (goal-oriented).

These traits have subsequently been mapped to the current 'Big 5' dimensions used to describe personality: agreeableness; extraversion; conscientiousness; openness; and neuroticism.

The final analysis included 26,845 participants from 1171 of the original schools for whom there were complete data and whose records were tracked through the National Death Index up to 2009.

During the monitoring period, which averaged nearly 48 years, just over 13 per cent of the participants died.

The analysis revealed that a higher score for energy, empathy, calmness, tidiness, intellectual curiosity and maturity, and a lower score for impulsivity, as a teen were associated with a lower relative risk of death from any cause over the subsequent half century.

Factoring in ethnicity and family background did little to alter the observed associations between personality traits and survival.

And when all potentially influential factors were accounted for, the analysis showed that every 1-point change (from the expected average) in personality trait score was associated with increases or decreases of 5 to 7 per cent in the relative risk of death over the average 48-year monitoring period.

This is an observational study, and as such, can't establish cause, added to which not all the sample was randomly selected nor were ethnicity data available for all the participants. And the researchers didn't look at specific causes of death.

Nevertheless, the findings are based on large numbers, nearly half a century of monitoring, and an extensive personality trait inventory, say the researchers.

"In one sense, the tracing of personality-mortality associations back to adolescence is surprising because the high school years are widely seen as a time of personality development and malleability," they comment.

And they acknowledge: "Personality change over the life course is a complex issue, with considerable individual variability."

But they suggest that the possible ways in which personality may be linked longevity include the adoption of unhealthy behaviours and the long term physiological impact of psychological factors on the body's immune, hormonal, and cardiovascular systems.

"Maladaptive traits also appear to limit later educational attainment, impede mid-life occupational advancement and increase risk of divorce-social and socioeconomic factors linked to later death," they point out.

Large amounts of the potent greenhouse gas methane are being released from an Icelandic glacier, scientists have discovered.

A study of Sólheimajökull glacier, which flows from the active, ice-covered volcano Katla, shows that up to 41 tonnes of methane is being released through meltwaters every day during the summer months. This is roughly equivalent to the methane produced by more than 136,000 belching cows.

The Lancaster university-led research, which is featured in Scientific Reports, is the first published field study to show methane release from glaciers on this scale.

"This is a huge amount of methane lost from the glacial meltwater stream into the atmosphere," said Dr Peter Wynn, a glacial biogeochemist from the Lancaster Environment Centre and corresponding author of the study. "It greatly exceeds average methane loss from non-glacial rivers to the atmosphere reported in the scientific literature. It rivals some of the world's most methane-producing wetlands; and represents more than twenty times the known methane emissions of all Europe's other volcanoes put together."

Dr Wynn added: "Methane has a global warming potential 28 times that of carbon dioxide (CO2). It is therefore important that we know about different sources of methane being released to the atmosphere and how they might change in the future.

"There has been a lot of speculation about whether or not glaciers can release methane. The beds of glaciers contain the perfect cocktail of conditions for methane production - microbes, low oxygen, organic matter and water - along with an impermeable cap of ice on the surface trapping the methane beneath.

"However, nobody has thoroughly investigated this in the field before and this is the strongest evidence yet that glaciers are releasing methane."

The study comes out of PhD research carried out by Dr Rebecca Burns when she was a graduate researcher at Lancaster University through the Centre for Global Eco-innovation, part-funded by the European Regional Development Fund.

Dr Burns took water samples from the edge of the melt water lake in front of the Sólheimajökull glacier and measured the methane concentrations, comparing them with methane levels in nearby sediments and other rivers, to make sure that the methane wasn't being released from the surrounding landscape.

"The highest concentrations were found at the point where the river emerges from underneath the glacier and enters the lake. This demonstrates the methane must be sourced from beneath the glacier," Dr Wynn explains.

Using a mass spectrometer, which identifies the unique 'fingerprint' of the methane, the researchers discovered the methane is coming from microbiological activity at the bed of the glacier. But there is still a connection with the volcano.

"We believe that while the volcano is not producing the methane, it is providing the conditions that allow the microbes to thrive and release methane into the surrounding meltwaters," Said Dr Wynn.

Normally when methane comes into contact with oxygen it combines to form CO2, so the methane effectively disappears. On a glacier, meltwaters rich in dissolved oxygen access the bed of the ice mass and convert any methane present into carbon dioxide.

"Understanding the seasonal evolution of Sólheimajökull's subglacial drainage system and how it interacts with the Katla geothermal area formed part of this work", said Professor Fiona Tweed, an expert in glacier hydrology at Staffordshire University and co-author of the study.

At Sólheimajökull when the meltwater reaches the glacier bed, it comes into contact with gases produced by the Katla volcano. These gases lower the oxygen content of the water, meaning some of the methane produced by the microbes can be dissolved into the water and transported out of the glacier without being converted to CO2.

Dr Hugh Tuffen, a volcanologist at Lancaster University and co-author on the study, said: "The heat from Katla volcano may greatly accelerate the generation of microbial methane, so in fact you could see Katla as a giant microbial incubator.

"Scientists have also recently discovered that Katla emits vast amounts of CO2 - it's in the top five globally in terms of CO2 emissions from volcanoes - so Katla is certainly a very interesting, very gassy volcano."

"Both Iceland and Antarctica have many ice-covered, active volcanoes and geothermal systems," said Dr Burns. "The recent International Panel on Climate Change (IPCC) report highlights that current trajectories indicate global warming is likely to reach 1.5oC between 2030 and 2052, with greatest perceived climate sensitivity at higher latitudes. If methane produced under these ice caps has a means of escaping as the ice thins, there is the chance we may see short term increases in the release of methane from ice masses into the future."

Andri Stefánsson, Professor of Hydrothermal Geochemistry at the University of Iceland, who was not involved in the study said: "These findings provide important and new information on the origin and fluxes of methane at the Earth's surface and the significance of this greenhouse gas to the atmosphere from such systems.

However, the researchers caution that it is still unclear how these effects will play out. They believe that although there could be a short-term spike of methane released while the glacier melts and thins, in the long-term the process could be self-limiting as, along with other reasons, without the ice the conditions for methane production are removed.

Epigenetic therapies -- targeting enzymes that alter what genes are turned on or off in a cell -- are of growing interest in the cancer field as a way of making a cancer less aggressive or less malignant. Researchers at Boston Children's Hospital now report that at least one epigenetic therapy that initially looked promising for lung cancer actually has the opposite effect, boosting cancer stem cells that are believed to drive tumors. They also identify a strategy that reduces these cells, curbing lung cancer in mice.

Findings were published online today in Nature Communications.

Cancer stem cells have been identified in blood cancers and a variety of solid tumors. They make up a tiny fraction of tumor cells, but can regenerate a cancer on their own. Carla Kim, PhD, and colleagues in Boston Children's Hospital's Stem Cell Research program have shown that cancer stem cells play a role in adenocarcinoma, the most common type of lung cancer. When they transplanted cancer stem cells from a diseased mouse, previously healthy mice developed lung cancer.

The new study, led by lab member Samuel Rowbotham, PhD, looked at an epigenetic therapy that inhibits the enzyme G9a, a type of histone methyltransferase. G9a had been thought to be cancer-promoting, and some studies have suggested that inhibiting G9a is an effective strategy in certain cancers, including adenocarcinoma. Rowbotham and Kim now call this into question.

"People had looked at cell lines from lung tumors and found that they are sensitive to drugs inhibiting G9a," says Rowbotham, first author on the paper. "In general tumor cell populations, these drugs would slow down growth or even kill the cells. But we found that these drugs were also making the surviving tumor cells more stem-like. We predicted that this would advance disease progression, and this is what we saw."

The team first looked at adenocarcinoma cell lines and found that when the cells were treated with G9a, they became more like stem cells. They then transplanted cancer stem cells into live mice and tracked the development of adenocarcinoma. When they knocked down the G9a gene in lung tumors, the tumors grew bigger and spread farther.

Kim believes this down side to G9a hadn't been noticed because prior studies only looked at cell lines, and because cancer stem cells are hard to detect.

"Earlier studies couldn't see that cancer stem cells were still around, and there's more of them when you treat with these drugs," she says. "Because they're such a small fraction of the tumor, anything that affects them can easily be missed."

A new epigenetic target?

But Rowbotham, Kim and colleagues also found potentially better enzymes to target: Histone demethylases. Their action is chemically opposite to that of G9a, stripping off a methyl group from histone where G9a adds one. When Rowbotham knocked down the gene for demethylase enzymes, and added drug that prevents them from working, he was able to make the cells look less like cancer stem cells in a dish and behave less like cancer stem cells in live mice. When he gave demethylase inhibitors to mice with established lung tumors, cancer progression was slowed and the animals survived longer than untreated mice.

Although a cancer stem cell hasn't been found in human adenocarcinoma, Kim believes the findings are worth pursuing further. She notes a related line of evidence -- a 2017 study that found that demethylase inhibitors were effective in killing chemotherapy-resistant cells from patient tumors.

"Even if we can't pinpoint cancer stem cells in human patients, Sam's work shows you can start by studying a cancer stem cell in a mouse model and identify targets that could be clinically important," she says. "It shows the importance of finding the right molecule the cancer is sensitive to. In adenocarcinoma, a demethylase inhibitor is likelier to be more useful than methyltransferase inhibitor."

They and others envision a two-phase strategy for adenocarcinoma that would first target the general population of cancer cells to "debulk" the tumor, then add a second treatment specifically directed at cancer stem cells.

The team is now doing further studies to explore demethylase inhibitors as potential therapeutic drugs, alone or in combination with other treatments. Because demethylase inhibitors have very broad effects, they will also look for genes the inhibitors affect downstream, which could provide more specific drug targets.