Category: Science News

{Armed with a new list of words and using the power of social media, a new study has found that by the age of 20, a native English-speaking American knows 42,000 dictionary words.}

How many words do we know? It turns out that even language experts and researchers have a tough time estimating this.

Armed with a new list of words and using the power of social media, a new study published in Frontiers in Psychology, has found that by the age of twenty, a native English speaking American knows 42 thousand dictionary words.

“Our research got a huge push when a television station in the Netherlands asked us to organize a nation-wide study on vocabulary knowledge,” states Professor Marc Brysbaert of Ghent University in Belgium and leader of this study. “The test we developed was featured on TV and, in the first weekend, over 300 thousand Dutch speakers had done it — it really went viral.”

Realising how interested people are in finding out their vocabulary size, the team then made similar tests in English and Spanish. The English test has now been taken by almost one million people. It takes up to four minutes to complete and has been shared widely on Facebook and Twitter, giving the team access to an unprecedented amount of data.

“At the Centre of Reading Research we are investigating what determines the ease with which words are recognized;” explained Professor Brysbaert. The test includes a list of 62,000 words that he and his team have compiled.

He added: “As we made the list ourselves and have not used a commercially available dictionary list with copyright restrictions, it can be made available to everyone, and all researchers can access it.”

The test is simple. You are asked if the word on the screen is, or is not, an existing word in English. In each test, there are 70 words, and 30 letter sequences that look like words but are not actually existing words.

The test will also ask you for some personal information such as your age, gender, education level and native language. This has enabled the team to discover that the average twenty-year-old native English speaking American knows 42 thousand dictionary words. As we get older, we learn one new word every two days, which means that by the age of 60, we know an additional 6000 words.

“As a researcher, I am most interested in what this data can tell us about word prevalence, i.e. how well each word is known in a language;” added Professor Brysbaert.

“In Dutch, we have seen that this explains a lot about word processing times. People respond much faster to words known by all people than to words known by 95% of the population, even if the words used with the same frequency. We are convinced that word prevalence will become an important variable in word recognition research.”

With data from about 200 thousand people who speak English as a second language, the team can also start to look at how well these people know certain words, which could have implications for language education.

This is the largest study of its kind ever attempted. Professor Brysbaert has plans to improve the accuracy of the test and extend the list to include over 75,000 words.

“This work is part of the big data movement in research, where big datasets are collected to be mined;” he concluded.

“It also gives us a snapshot of English word knowledge at the beginning of the 21st century. I can imagine future language researchers will be interested in this database to see how English has evolved over 100 years, 1000 years and maybe even longer.”

{Neuroscientists have identified the neural networks that connect the cerebral cortex to the adrenal medulla, which is responsible for the body’s rapid response in stressful situations. These findings provide evidence for the neural basis of a mind-body connection. Specifically, the findings shed new light on how stress, depression and other mental states can alter organ function, and show that there is a real anatomical basis for psychosomatic illness.}

Neuroscientists at the University of Pittsburgh have identified the neural networks that connect the cerebral cortex to the adrenal medulla, which is responsible for the body’s rapid response in stressful situations. These findings, reported in the online Early Edition of the journal Proceedings of the National Academy of Sciences (PNAS), provide evidence for the neural basis of a mind-body connection.

Specifically, the findings shed new light on how stress, depression and other mental states can alter organ function, and show that there is a real anatomical basis for psychosomatic illness. The research also provides a concrete neural substrate that may help explain why meditation and certain exercises such as yoga and Pilates can be so helpful in modulating the body’s responses to physical, mental and emotional stress.

“Our results turned out to be much more complex and interesting than we imagined before we began this study,” said senior author Peter L. Strick, Ph.D., Thomas Detre Chair of the Department of Neurobiology and scientific director of the University of Pittsburgh Brain Institute.

In their experiments, the scientists traced the neural circuitry that links areas of the cerebral cortex to the adrenal medulla (the inner part of the adrenal gland, which is located above each kidney). The scientific team included lead author Richard P. Dum, Ph.D., research associate professor in the Department of Neurobiology; David J. Levinthal, M.D., Ph.D., assistant professor in the Department of Medicine; and Dr. Strick.

The scientists were surprised by the sheer number of neural networks they uncovered. Other investigators had suspected that one or, perhaps, two cortical areas might be responsible for the control of the adrenal medulla. The actual number and location of the cortical areas were uncertain. In the PNAS study, the Strick laboratory used a unique tracing method that involves rabies virus. This approach is capable of revealing long chains of interconnected neurons. Using this approach, Dr. Strick and his colleagues demonstrated that the control of the adrenal medulla originates from multiple cortical areas. According to the new findings, the biggest influences arise from motor areas of the cerebral cortex and from other cortical areas involved in cognition and affect.

Why does it matter which cortical areas influence the adrenal medulla? Acute responses to stress include a wide variety of changes such as a pounding heart, sweating and dilated pupils. These responses help prepare the body for action and often are characterized as “fight or flight responses.” Many situations in modern life call for a more thought-out reaction than simple “fight or flight,” and it is clear that we have some cognitive control (or what neuroscientists call “top-down” control) over our responses to stress.

“Because we have a cortex, we have options,” said Dr. Strick. “If someone insults you, you don’t have to punch them or flee. You might have a more nuanced response and ignore the insult or make a witty comeback. These options are part of what the cerebral cortex provides.”

Another surprising result was that motor areas in the cerebral cortex, involved in the planning and performance of movement, provide a substantial input to the adrenal medulla. One of these areas is a portion of the primary motor cortex that is concerned with the control of axial body movement and posture. This input to the adrenal medulla may explain why core body exercises are so helpful in modulating responses to stress. Calming practices such as Pilates, yoga, tai chi and even dancing in a small space all require proper skeletal alignment, coordination and flexibility.

The PNAS study also revealed that the areas of the cortex that are active when we sense conflict, or are aware that we have made an error, are a source of influence over the adrenal medulla. “This observation,” said Dr. Strick, “raises the possibility that activity in these cortical areas when you re-imagine an error, or beat yourself up over a mistake, or think about a traumatic event, results in descending signals that influence the adrenal medulla in just the same way as the actual event.” These anatomical findings have relevance for therapies that deal with post-traumatic stress.

Additional links with the adrenal medulla were discovered in cortical areas that are active during mindful mediation and areas that show changes in bipolar familial depression. “One way of summarizing our results is that we may have uncovered the stress and depression connectome,” says Dr. Strick.

Overall, these results indicate that circuits exist to link movement, cognition and affect to the function of the adrenal medulla and the control of stress. This circuitry may mediate the effects of internal states like chronic stress and depression on organ function and, thus, provide a concrete neural substrate for some psychosomatic illness.

{Natural microstructures in transparent wood are key to lighting & insulation advantages}

Engineers demonstrate in a new study that windows made of transparent wood could provide more even and consistent natural lighting and better energy efficiency than glass.

Engineers at the A. James Clark School of Engineering at the University of Maryland (UMD) demonstrate in a new study that windows made of transparent wood could provide more even and consistent natural lighting and better energy efficiency than glass.

In a paper just published in the peer-reviewed journal Advanced Energy Materials, the team, headed by Liangbing Hu of UMD’s Department of Materials Science and Engineering and the Energy Research Center lay out research showing that their transparent wood provides better thermal insulation and lets in nearly as much light as glass, while eliminating glare and providing uniform and consistent indoor lighting. The findings advance earlier published work on their development of transparent wood.

The transparent wood lets through just a little bit less light than glass, but a lot less heat, said Tian Li, the lead author of the new study. “It is very transparent, but still allows for a little bit of privacy because it is not completely see-through. We also learned that the channels in the wood transmit light with wavelengths around the range of the wavelengths of visible light, but that it blocks the wavelengths that carry mostly heat,” said Li.

The team’s findings were derived, in part, from tests on tiny model house with a transparent wood panel in the ceiling that the team built. The tests showed that the light was more evenly distributed around a space with a transparent wood roof than a glass roof.

The channels in the wood direct visible light straight through the material, but the cell structure that still remains bounces the light around just a little bit, a property called haze. This means the light does not shine directly into your eyes, making it more comfortable to look at. The team photographed the transparent wood’s cell structure in the University of Maryland’s Advanced Imaging and Microscopy (AIM) Lab.

Transparent wood still has all the cell structures that comprised the original piece of wood. The wood is cut against the grain, so that the channels that drew water and nutrients up from the roots lie along the shortest dimension of the window. The new transparent wood uses theses natural channels in wood to guide the sunlight through the wood.

As the sun passes over a house with glass windows, the angle at which light shines through the glass changes as the sun moves. With windows or panels made of transparent wood instead of glass, as the sun moves across the sky, the channels in the wood direct the sunlight in the same way every time.

“This means your cat would not have to get up out of its nice patch of sunlight every few minutes and move over,” Li said. “The sunlight would stay in the same place. Also, the room would be more equally lighted at all times.”

Working with transparent wood is similar to working with natural wood, the researchers said. However, their transparent wood is waterproof due to its polymer component. It also is much less breakable than glass because the cell structure inside resists shattering.

The research team has recently patented their process for making transparent wood. The process starts with bleaching from the wood all of the lignin, which is a component in the wood that makes it both brown and strong. The wood is then soaked in epoxy, which adds strength back in and also makes the wood clearer. The team has used tiny squares of linden wood about 2 cm x 2 cm, but the wood can be any size, the researchers said.

{Our increasing reliance on the Internet and the ease of access to the vast resource available online is affecting our thought processes for problem solving, recall and learning. In a new article, researchers have found that ‘cognitive offloading’, or the tendency to rely on things like the Internet as an aide-mémoire, increases after each use.}

Our increasing reliance on the Internet and the ease of access to the vast resource available online is affecting our thought processes for problem solving, recall and learning. In a new article published in the journal Memory, researchers at the University of California, Santa Cruz and University of Illinois, Urbana Champaign have found that ‘cognitive offloading’, or the tendency to rely on things like the Internet as an aide-mémoire, increases after each use. We might think that memory is something that happens in the head but increasingly it is becoming something that happens with the help of agents outside the head. Benjamin Storm, Sean Stone & Aaron Benjamin conducted experiments to determine our likelihood to reach for a computer or smartphone to answer questions. Participants were first divided into two groups to answer some challenging trivia questions — one group used just their memory, the other used Google. Participants were then given the option of answering subsequent easier questions by the method of their choice.

The results revealed that participants who previously used the Internet to gain information were significantly more likely to revert to Google for subsequent questions than those who relied on memory. Participants also spent less time consulting their own memory before reaching for the Internet; they were not only more likely to do it again, they were likely to do it much more quickly. Remarkably 30% of participants who previously consulted the Internet failed to even attempt to answer a single simple question from memory.

Lead author Dr Benjamin Storm commented, “Memory is changing. Our research shows that as we use the Internet to support and extend our memory we become more reliant on it. Whereas before we might have tried to recall something on our own, now we don’t bother. As more information becomes available via smartphones and other devices, we become progressively more reliant on it in our daily lives.”

This research suggests that using a certain method for fact finding has a marked influence on the probability of future repeat behaviour.Time will tell if this pattern will have any further reaching impacts on human memory than has our reliance on other information sources. Certainly the Internet is more comprehensive, dependable and on the whole faster than the imperfections of human memory, borne out by the more accurate answers from participants in the internet condition during this research. With a world of information a Google search away on a smartphone, the need to remember trivial facts, figures, and numbers is inevitably becoming less necessary to function in everyday life.

{Brain area that lights up when we do good for others is more active in more empathetic.}

Scientists have identified part of our brain that helps us learn to be good to other people. People who rated themselves as having higher levels of empathy learned to benefit others faster than those who reported having lower levels of empathy. They also showed increased signalling in their subgenual anterior cingulate cortex when benefiting others.

Scientists from Oxford University and UCL have identified part of our brain that helps us learn to be good to other people. The discovery could help understanding of conditions like psychopathy where people’s behaviour is extremely antisocial.

The researchers were led by Dr Patricia Lockwood, who explained: ‘Prosocial behaviours are social behaviours that benefit other people. They are a fundamental aspect of human interactions, essential for social bonding and cohesion, but very little is currently known about how and why people do things to help others.

‘Although people have a remarkable inclination to engage in prosocial behaviours there are substantial differences between individuals. Empathy, the capacity to vicariously experience and understand another person’s feelings has been put forward as a critical motivator of prosocial behaviours, but we wanted to test why and how they might be linked.’

The scientists used a well-understood model of how people learn to maximise good outcomes for themselves and applied this model to understand how people learn to help others. While being scanned in a MRI machine, volunteers had to work out which symbols were more likely to give them, or someone else, a reward.

They found that while people readily learn to make choices that benefit other people, they do not learn it quite as fast as they learn to benefit themselves. However, they also identified a particular brain area involved in learning to get the best result for other people.

Dr Lockwood said: ‘A specific part of the brain called the subgenual anterior cingulate cortex was the only part of the brain that was activated when learning to help other people. Put another way, the subgenual anterior cingulate seems to be especially tuned to benefiting other people.

‘However, this region of the brain was not equally active in every person. People who rated themselves as having higher levels of empathy learnt to benefit others faster than those who reported having lower levels of empathy. They also showed increased signalling in their subgenual anterior cingulate cortex when benefitting others.’

‘This the first time anyone has shown a particular brain process for learning prosocial behaviours — and a possible link from empathy to learning to help others. By understanding what the brain does when we do things for other people, and individual differences in this ability, we are better placed to understand what is going wrong in those whose psychological conditions are characterised by antisocial disregard for others.’

{We are more susceptible to infection at certain times of the day as our body clock affects the ability of viruses to replicate and spread between cells, suggests new research. The findings may help explain why shift workers, whose body clocks are routinely disrupted, are more prone to health problems, including infections and chronic disease.}

We are more susceptible to infection at certain times of the day as our body clock affects the ability of viruses to replicate and spread between cells, suggests new research from the University of Cambridge. The findings, published today in the Proceedings of the National Academy of Sciences, may help explain why shift workers, whose body clocks are routinely disrupted, are more prone to health problems, including infections and chronic disease.

When a virus enters our body, it hijacks the machinery and resources in our cells to help it replicate and spread throughout the body. However, the resources on offer fluctuate throughout the day, partly in response to our circadian rhythms — in effect, our body clock. Circadian rhythms control many aspects of our physiology and bodily functions — from our sleep patterns to body temperature, and from our immune systems to the release of hormones. These cycles are controlled by a number of genes, including Bmal1 and Clock.

To test whether our circadian rhythms affect susceptibility to, or progression of, infection, researchers at the Wellcome Trust-Medical Research Council Institute of Metabolic Science, University of Cambridge, compared normal ‘wild type’ mice infected with herpes virus at different times of the day, measuring levels of virus infection and spread. The mice lived in a controlled environment where 12 hours were in daylight and 12 hours were dark.

The researchers found that virus replication in those mice infected at the very start of the day — equivalent to sunrise, when these nocturnal animals start their resting phase — was ten times greater than in mice infected ten hours into the day, when they are transitioning to their active phase. When the researchers repeated the experiment in mice lacking Bmal1, they found high levels of virus replication regardless of the time of infection.

“The time of day of infection can have a major influence on how susceptible we are to the disease, or at least on the viral replication, meaning that infection at the wrong time of day could cause a much more severe acute infection,” explains Professor Akhilesh Reddy, the study’s senior author. “This is consistent with recent studies which have shown that the time of day that the influenza vaccine is administered can influence how effectively it works.”

In addition, the researchers found similar time-of-day variation in virus replication in individual cell cultures, without influence from our immune system. Abolishing cellular circadian rhythms increased both herpes and influenza A virus infection, a dissimilar type of virus — known as an RNA virus — that infects and replicates in a very different way to herpes.

Dr Rachel Edgar, the first author, adds: “Each cell in the body has a biological clock that allows them to keep track of time and anticipate daily changes in our environment. Our results suggest that the clock in every cell determines how successfully a virus replicates. When we disrupted the body clock in either cells or mice, we found that the timing of infection no longer mattered — viral replication was always high. This indicates that shift workers, who work some nights and rest some nights and so have a disrupted body clock, will be more susceptible to viral diseases. If so, then they could be prime candidates for receiving the annual flu vaccines.”

As well as its daily cycle of activity, Bmal1 also undergoes seasonal variation, being less active in the winter months and increasing in summer. The researchers speculate that this may help explain why diseases such as influenza are more likely to spread through populations during winter.

Using cell cultures, the researchers also found that herpes viruses manipulate the molecular ‘clockwork’ that controls our circadian rhythms, helping the viruses to progress. This is not the first time that pathogens have been seen to ‘game’ our body clocks: the malaria parasite, for example, is known to synchronise its replication cycle with the host’s circadian rhythm, producing a more successful infection.

“Given that our body clocks appear to play a role in defending us from invading pathogens, their molecular machinery may offer a new, universal drug target to help fight infection,” adds Professor Reddy.

{Scientists seek cheaper strategies for producing freshwater.}

The world is on the verge of a water crisis.

Rainfall shifts caused by climate change plus the escalating water demands of a growing world population threaten society’s ability to meet its mounting needs. By 2025, the United Nations predicts, 2.4 billion people will live in regions of intense water scarcity, which may force as many as 700 million people from their homes in search of water by 2030.

Those water woes have people thirstily eyeing the more than one sextillion liters of water in Earth’s oceans and some underground aquifers with high salt content. For drinking or irrigation, the salt must come out of all those liters. And while desalination has been implemented in some areas — such as Israel and drought-stricken California — for much of the world, salt-removal is a prohibitively expensive energy drain.

Scientists and engineers, however, aren’t giving up on the quest for desalination solutions. The technology underlying modern desalination has been around for decades, “but we have not driven it in such a way as to be ubiquitous,” says UCLA chemical engineer Yoram Cohen. “That’s what we need to figure out: how to make desalination better, cheaper and more accessible.”

Recent innovations could bring costs down and make the technology more accessible. A new wonder material may make desalination plants more efficient. Solar-powered disks could also serve up freshwater with no need for electricity. Once freshwater is on tap, coastal floating farms could supply food to Earth’s most parched places, one scientist proposes.

{{Watering holes}}

Taking the salt out of water is hardly a new idea. In the fourth century B.C., Aristotle noted that Greek sailors would evaporate impure water, leaving the salt behind, and then condense the vapor to make drinkable water. In the 1800s, the advent of steam-powered travel and the subsequent need for water without corrosive salt for boilers prompted the first desalination patent, in England.

Most modern desalination plants use a technique that differs from these earlier efforts. Instead of evaporating water, pumps force pressurized saltwater from the ocean or salty underground aquifers through special sheets. These membranes contain molecule-sized holes that act like club bouncers, allowing water to pass through while blocking salt and other contaminants.

The membranes are rolled like rugs and stuffed into meter-long tubes with additional layers that direct water flow and provide structural support. A large desalination plant uses tens of thousands of membranes that fill a warehouse. This process is known as reverse osmosis and the result is salt-free water plus a salty brine waste product that is typically pumped underground or diluted with seawater and released back into the ocean. It takes about 2.5 liters of seawater to make 1 liter of freshwater.

In 2015, more than 18,000 desalination plants worldwide had the annual capacity to produce 31.6 trillion liters of freshwater across 150 countries. While still less than 1 percent of worldwide freshwater usage, desalination production is two-thirds higher than it was in 2008. Driving the boom is a decades-long drop in energy requirements thanks to innovations such as energy-efficient water pumps, improved membranes and plant configurations that use outbound water to help pressurize incoming water. Seawater desalination in the 1970s consumed as much as 20 kilowatt-hours of energy per cubic meter of produced fresh-water; modern plants typically require just over
three kilowatt-hours.

{{Water, water, everywhere}}

Desalination plants supply water to more than 300 million people worldwide and experts expect that number to grow. Blue dots in this map represent the more than 500 large desalination plants currently in operation. Each plant produces more than 20 million liters of freshwater daily from seawater and salty groundwater. The number of smaller plants, such as those that provide freshwater on ships or for personal use, is unclear.

There’s a limit, however, to the energy savings. Theoretically, separating a cubic meter of freshwater from two cubic meters of seawater requires a minimum of about 1.06 kilowatt-hours of energy. Desalination is typically only viable when it’s cheaper than the next alternative water source, says Brent Haddad, a water management expert at the University of California, Santa Cruz. Alternatives, such as reducing usage or piping freshwater in from afar, can help, but these methods don’t create more H2O. While other hurdles remain for desalination, such as environmentally friendly wastewater disposal, cost is the main obstacle.

The upfront cost of each desalination membrane is minimal. For decades, most membranes have been made from polyamide, a synthetic polymer prized for its low manufacturing cost — around $1 per square foot. “That’s very, very cheap,” says MIT materials scientist Shreya Dave. “You can’t even buy decent flooring at Home Depot for a dollar a square foot.”

But polyamide comes with additional costs. It degrades quickly when exposed to chlorine, so when the source water contains chlorine, plant workers have to add two steps: remove chlorine before desalination, then add it back later, since drinking water requires chlorine as a disinfectant. To make matters worse, in the absence of chlorine, the membranes are susceptible to growing biological matter that can clog up the works.

With these problems in mind, researchers are turning to other membrane materials. One alternative, graphene oxide, may knock polyamide out of the water.

{{Membrane maze}}

Since its discovery in 2004, graphene has been touted as a supermaterial, with proposed applications ranging from superconductors to preventing blood clots (SN: 10/3/15, p. 7; SN Online: 2/11/14). Each graphene sheet is a single-atom-thick layer of carbon atoms arranged in a honeycomb grid. As a hypothetical desalination membrane, graphene would be sturdy and put up little resistance to passing water, reducing energy demands, says MIT materials scientist Jeff Grossman.

Pure graphene is astronomically expensive and difficult to make in large sheets. So Grossman, Dave and colleagues turned to a cheaper alternative, graphene oxide. The carbon atoms in graphene oxide are bordered by oxygen and hydrogen atoms.

Those extra atoms make graphene oxide “messy,” eliminating many of the material’s unique electromagnetic properties. “But for a membrane, we don’t care,” Grossman says. “We’re not trying to run an electric current through it, we’re not trying to use its optical properties — we’re just trying to make a thin piece of material we can poke holes into.”

The researchers start with graphene flakes peeled from hunks of graphite, the form of carbon found in pencil lead. Researchers suspend the graphene oxide flakes, which are easy and cheap to make, in liquid. As a vacuum sucks the liquid out of the container, the flakes form a sheet. The researchers bind the flakes together by adding chains of carbon and oxygen atoms. Those chains latch on to and connect the graphene oxide flakes, forming a maze of interconnected layers. The length of these chains is fine-tuned so that the gaps between flakes are just wide enough for water molecules, but not larger salt molecules, to pass through.

The team can fashion paperlike graphene oxide sheets a couple of centimeters across, though the technique should easily scale up to the roughly 40-square-meter size currently packed into each desalination tube, Dave says. Furthermore, the sheets hold up under pressure. “We are not the only research group using vacuum filtration to assemble membranes from graphene oxide,” she says, “but our membranes don’t fall apart when exposed to water, which is a pretty important thing for water filtration.”

The slimness of the graphene oxide membranes makes it much easier for water molecules to pass through compared with the bulkier poly-amide, reducing the energy needed to pump water through them. Grossman, Dave and colleagues estimated the cost savings of such highly permeable membranes in 2014 in a paper in Energy & Environmental Science. Desalination of ground-water would require 46 percent less energy; processing of saltier seawater would use 15 percent less, though the energy demands of the new proto-types haven’t yet been tested.

So far, the new membranes are especially durable, Grossman says. “Unlike polyamide, graphene oxide membranes are resilient to important cleaning chemicals like chlorine, and they hold up in harsh chemical environments and at high temperatures.” With lower energy requirements and no need to remove and replace chlorine from source water, the new membranes could be one solution to many desalination challenges.

In large quantities, the graphene oxide membranes may be economically viable, Dave predicts. At scale, she estimates that manufacturing graphene oxide membranes will cost around $4 to $5 per square foot — not drastically more expensive than polyamide, considering its other benefits. Existing plants could swap in graphene oxide membranes when older polyamide membranes need replacing, spreading out the cost of the upgrade over about 10 years, Dave says. The team is currently patenting its membrane–making methodology, though the researchers think it will take a few more years before the technology is commercially viable.

“We are at a point where we need a quantum leap, and that can be achieved by new membrane structures,” says Nikolay Voutchkov, executive director of Water Globe Consulting, a company that advises industries and municipalities on desalination projects. The work on graphene oxide “is one way to do it.”

Other materials are also vying to be poly-amide’s successor. Researchers are testing carbon nanotubes, tiny cylindrical carbon structures, as a desalination membrane. Which material wins “will come down to cost,” Voutchkov says. Even if graphene oxide or other membranes save money in the long run, high upfront costs would make them less appealing.

Plus, those new membranes won’t solve the problems of desalination in less-developed areas. The costs of building a large plant and pumping freshwater over long distances make desalination a hard sell in rural Africa and other water-starved places. For hard-to-reach locales, scientists are thinking small.

{{A portable approach}}

The researchers have produced 2.5-centimeter-wide disks of the new material so far, which are light enough to float. The black disks absorb more than 96 percent of incoming sunlight and about 90 percent of the absorbed energy is used in evaporating water, the researchers reported in the June Nature Photonics.

The evaporated water condenses and collects in a transparent box containing stainless steel. In laboratory tests, the researchers successfully desalinated water from China’s Bohai Sea to levels low enough to meet drinking water standards. The researchers reckon that they can produce around five liters of fresh-water per hour for every square meter of material under intense light. In early tests, the disks held up after multiple uses without dropping in performance.

Aluminum is cheap and the material’s fabrication process can easily scale, Zhu says. While the disks can’t produce as much drinkable water as quickly as big desalination plants, the new method may serve a different need, since it’s more affordable and more portable, he says. “We are developing a personalized water solution without big infrastructure, without extra energy consumption and with a minimum carbon footprint.” The researchers hope that their new desalination technique will find use in developing countries and remote areas where conventional desalination plants aren’t feasible.

The disks are worth pursuing, says Haddad at UC Santa Cruz. “I say let’s try it out. Let’s work with some villages and see how well the tech works and get their feedback. That to me is a good next step to take.”

Desalinating water by evaporation has a downside, though, Voutchkov says. Unlike most methods for removing salt, evaporation produces pure distilled water without any important dissolved minerals such as calcium and magnesium. Drinking water without those minerals can cause health issues over time, he warns. “It’s OK for a few weeks, but you can’t drink it forever.” Minerals would need to be added back in to the water, which is hard to do in remote places, he says.

Freshwater isn’t just for filling water bottles, though. With a nearly endless supply of salt-free water at hand, desalination could bring agriculture to new places.

Coastal crops
When Khaled Moustafa looks at a beach, he doesn’t just see a place for sunning and surfing. The biologist at the National Conservatory of Arts and Crafts in Paris sees the future of farming.

In the April issue of Trends in Biotechnology, Moustafa proposed that desalination could supply irrigation water to colossal floating farms. Self-sufficient floating farms could bring agriculture to arid coastal regions previously inhospitable to crops. The idea, while radical, isn’t too farfetched, given recent technological advancements, Moustafa says.

Floating farms would lay anchor along coastlines and suck up seawater, he proposes. A solar panel–powered water desalination system would provide freshwater to rows of cucumbers, tomatoes or strawberries stacked like a big city high-rise inside a “blue house” (that is, a floating greenhouse).

In remote Africa, electricity is hard to come by. Materials scientist Jia Zhu of Nanjing University in China and colleagues are hoping to bring drinkable water to unpowered, parched places by turning to an old-school desalination technique: evaporating and condensing water.

Their system runs on sunshine, something that is both free and abundant in Earth’s hotter regions. Using the sun’s rays to desalinate water is hardly new, but most existing systems are inefficient. Only about 30 to 45 percent of incoming sunlight typically goes into evaporating water, which means a big footprint is needed to create sizable amounts of freshwater. Zhu and colleagues hope to boost efficiency with a more light-absorbing material.

The material’s fabrication starts with a base sheet made of aluminum oxide speckled with 300-nanometer-wide holes. The researchers then coat this sheet with a thin layer of aluminum particles.

When light hits aluminum particles inside one of the holes, the added energy makes electrons in the aluminum start to oscillate and ripple. These electrons can transfer some of that energy to their surroundings, heating and evaporating nearby water without the need for boiling (SN Online: 4/8/16).

Each floating farm would stretch 300 meters long by 100 meters wide, providing about 3 square kilometers of cultivable surface over only three-tenths of a square kilometer of ocean, Moustafa says. The farms could even be mobile, cruising around the ocean to transport crops and escape bad weather.

Such a portable and self-contained farming solution would be most appealing in dry coastal regions that get plenty of sunshine, such as the Arabian Gulf, North Africa and Australia.

“I wouldn’t say it’s a silly idea,” Voutchkov says. “But it’s an idea that can’t get a practical implementation in the short term. In the long term, I do believe it’s a visionary idea.”

Floating farms may come with a large price tag, Moustafa admits. Still, expanding agriculture should “be more of a priority than building costly football stadiums or indoor ski parks in the desert,” he argues.

Whether or not farming will ever take to the seas, new desalination technologies will transform the way society quenches its thirst. More than 300 million people rely on desalination for at least some of their daily water, and that number will only grow as needs rise and new materials and techniques improve the process.

“Desalination can sometimes get a rap for being energy intensive,” Dave says. “But the immediate benefits of having access to water that would not otherwise be there are so large that desalination is a technology that we will be seeing for a long time into the future.”

{{ {This article appears in the August 20, 2016, Science News with the headline, “Quenching society’s thirst: Desalination may soon turn a corner, from rare to routine.” } }}

{A new study that for the first time examined the internal anatomy of a fossil human relative’s heel bone, or calcaneus, shows greater similarities with gorillas than chimpanzees.}

The study, titled: Trabecular architecture in the StW 352 fossil hominin calcaneus and published in the Journal of Human Evolution, was undertaken by a team of international researchers from the University of the Witwatersrand in South Africa, Duke University, University of Southern California and Indiana University in the US.

The team examined the internal anatomy of our human relative, the StW 352 Australopithecus africanus fossil, from South Africa’s rich fossil record in the Cradle of Humankind World Heritage Site, some 40km from Johannesburg.

They analyzed the structure and orientation of trabecular struts — the spongy material inside a bone — in the fossil from Sterkfontein Member 4, demonstrating greater similarities between it and the heel bone of gorillas rather than humans or chimpanzees.

In doing this, the team revealed new insights into how our ancestors moved through and interacted with their environment approximately 2-2.5 million years ago. Similarities between the fossil from Sterkfontein and gorillas indicate that Australopithecus africanus, the species of human ancestor (or hominin) also represented by the Taung Child, or at least this individual member of the species, exhibited gorilla-like levels of joint mobility and structural reinforcement.

Results of the new study were surprising because other recent studies of the australopithecine calcaneus, focusing on its external anatomy, have emphasised similarities with chimpanzees or humans.

However, since the organisation of trabecular bone is determined in part by how an animal interacts with its environment during its lifetime, the gorilla-like features observed in the present study are particularly compelling in revising how we view behavioural reconstructions of our australopithecine ancestors.

Lowland gorillas are generally regarded as less arboreal than chimpanzees — they spend less time in trees and generally less time climbing — although it is important to remember that even gorillas depend on arboreal resources for their survival. Thus, the gorilla-like features in the Australopithecus africanus calcaneus substantiate claims that our hominin ancestors depended on arboreal resources for their survival, but importantly, it provides evidence that gorilla-like foot function should be considered more frequently when discussing the evolution of human feet and how they functioned within the environment.

Ultimately, whether internal structure of the Australopithecus africanus calcaneus from Sterkfontein indicates gorilla-like levels of arboreal resource exploitation, or whether it reveals greater variability (mobility) in foot interactions with uneven terrain compared to those characterising modern human feet, awaits follow-up research that the investigators are currently undertaking.

{Research shows stressed-out birds more attractive to mosquitoes, raising fears birds exposed to stressors such as road noise, pesticides and light pollution, will be bitten more often and spread more West Nile virus.}

When researchers from the University of South Florida (USF) and colleagues investigated how the stress hormone, corticosterone, affects how birds cope with West Nile virus, they found that birds with higher levels of stress hormone were twice as likely to be bitten by mosquitoes that transmit the virus. Their studies have implications for the transmission of other viruses such as Eastern Equine Encephalitis, and perhaps even Zika, both known to be carried by the kind of mosquitoes used in this study.

A paper describing their research was published in the Proceedings of the Royal Society B.

“Few studies have considered how stress hormone effects on individuals might influence population dynamics,” said study lead author Dr. Stephanie Gervasi, who conducted the studies while carrying out her postdoctoral work at USF and is now at the Monell Chemical Senses Center in Philadelphia. “For vector-borne diseases such as West Nile virus, the presence of corticosterone could influence pathogen spread through effects on contact rates with the mosquitoes that transmit it. In addition, stress hormones have negative effects on animals including immunosuppression and increased susceptibility to infections, which is why we are now also studying how corticosterone affects the birds’ immune response to the virus.”

According to the researchers, mosquitoes use a variety of cues to locate a target, including carbon dioxide output, body size and temperature. They hypothesized that these signals coming from a bird could convey information about stress hormones making the birds more appealing targets for the insects.

With the effects of corticosterone on mosquito feeding choices unknown, in a series of studies the researchers experimentally manipulated songbird stress hormones levels. Then they examined mosquito feeding preferences, feeding success and productivity as well as the defensive behaviors of birds trying to avoid being bitten.

In several phases of the study, zebra finches were treated with a low or high level of corticosterone and their caged light environment was altered to simulate dusk as the birds were made available to mosquitoes for measured periods of time. Bird and mosquito behavior was observed via video and the mosquitoes were later examined to determine if they had fed on the birds. The researchers also investigated the timing of subsequent mosquito egg-laying after the insects fed on the birds.

“Mosquitoes seem to be able to ‘sniff out’ the stress hormone and key in on individual birds,” said the study’s principal investigator Dr. Lynn Martin, associate professor in the USF Department of Integrative Biology. “The birds injected with higher levels of the hormone were twice as likely to be bitten by mosquitoes, even those hormone-treated birds were much more defensive than untreated ones. Corticosterone treatment increased tail flicks, and head shakes, and other defensive behaviors, but the mosquitoes managed to breach those defenses and feed more on stress hormone-treated birds.”

The study’s broader ecological implications suggest that an elevated stress hormone concentration raises the level of host attractiveness, potentially affecting the transmission of mosquito-borne diseases in a number of ways.

“Stress hormones also altered the relationship between the timing of laying and clutch size in mosquitoes,” said co-principal investigator Dr. Thomas Unnasch, chair and Distinguished USF Health Professor in the Department of Global Health, USF College of Public Health.

Mosquitoes that fed on birds with high stress hormone levels tended to lay different sized clutches of eggs at different rates than mosquitoes fed on control birds. These effects of bird stress on mosquito reproduction suggest that mosquito-feeding choice might also affect disease cycles in nature by changing the number of newborn mosquitoes that could be infected later by stressed birds.

The researchers concluded that the corticosterone levels in their test birds were within the range of normal for birds in the wild when exposed to stressors in natural their environments, such as road noise, pesticides and light pollution.

“Much more work is necessary to further understand on the interplay of host corticosterone, vector-feeding behavior, host defenses and mosquito productivity,” the researchers said.

{Pathways that exist before kids learn to read may determine development of brain’s word recognition area.}

A new study reveals that a brain region dedicated to reading has connections necessary for that skill even before children learn to read. By scanning the brains of children before and after they learned to read, the researchers found they could predict the location where each child’s visual word form area (VWFA) would develop.

{{}}A new study from MIT reveals that a brain region dedicated to reading has connections for that skill even before children learn to read.

By scanning the brains of children before and after they learned to read, the researchers found that they could predict the precise location where each child’s visual word form area (VWFA) would develop, based on the connections of that region to other parts of the brain.

Neuroscientists have long wondered why the brain has a region exclusively dedicated to reading — a skill that is unique to humans and only developed about 5,400 years ago, which is not enough time for evolution to have reshaped the brain for that specific task. The new study suggests that the VWFA, located in an area that receives visual input, has pre-existing connections to brain regions associated with language processing, making it ideally suited to become devoted to reading.

“Long-range connections that allow this region to talk to other areas of the brain seem to drive function,” says Zeynep Saygin, a postdoc at MIT’s McGovern Institute for Brain Research. “As far as we can tell, within this larger fusiform region of the brain, only the reading area has these particular sets of connections, and that’s how it’s distinguished from adjacent cortex.”

Saygin is the lead author of the study, which appears in the Aug. 8 issue of Nature Neuroscience. Nancy Kanwisher, the Walter A. Rosenblith Professor of Brain and Cognitive Sciences and a member of the McGovern Institute, is the paper’s senior author.

{{Specialized for reading}}

The brain’s cortex, where most cognitive functions occur, has areas specialized for reading as well as face recognition, language comprehension, and many other tasks. Neuroscientists have hypothesized that the locations of these functions may be determined by prewired connections to other parts of the brain, but they have had few good opportunities to test this hypothesis.

Reading presents a unique opportunity to study this question because it is not learned right away, giving scientists a chance to examine the brain region that will become the VWFA before children know how to read. This region, located in the fusiform gyrus, at the base of the brain, is responsible for recognizing strings of letters.

Children participating in the study were scanned twice — at 5 years of age, before learning to read, and at 8 years, after they learned to read. In the scans at age 8, the researchers precisely defined the VWFA for each child by using functional magnetic resonance imaging (fMRI) to measure brain activity as the children read. They also used a technique called diffusion-weighted imaging to trace the connections between the VWFA and other parts of the brain.

The researchers saw no indication from fMRI scans that the VWFA was responding to words at age 5. However, the region that would become the VWFA was already different from adjacent cortex in its connectivity patterns. These patterns were so distinctive that they could be used to accurately predict the precise location where each child’s VWFA would later develop.

Although the area that will become the VWFA does not respond preferentially to letters at age 5, Saygin says it is likely that the region is involved in some kind of high-level object recognition before it gets taken over for word recognition as a child learns to read. Still unknown is how and why the brain forms those connections early in life.

{{Pre-existing connections}}

The MIT team now plans to study whether this kind of brain imaging could help identify children who are at risk of developing dyslexia and other reading difficulties.

“It’s really powerful to be able to predict functional development three years ahead of time,” Saygin says. “This could be a way to use neuroimaging to try to actually help individuals even before any problems occur.”