Brain

We see crystals all around us: snowflakes, ice cubes, table salt, gemstones, to name a few. Invisible to the naked eye, but of special interest to scientists, are crystalline “nanowires” — wires with a diameter of a mere few nanometers and a typical length of a micrometer.

Normally in a rod-like shape, these wires are an interesting area of worldwide research because of their many potential applications, including semiconductors and miniaturized optical and optoelectronic devices.

As reported in a recent Nature paper, scientists at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at Argonne National Laboratory, played a critical role in the discovery of a DNA-like twisted crystal structure created with a germanium sulfide nanowire, also known as a “van der Waals material.” The research was conducted in collaboration with the University of California at Berkeley and Lawrence Berkeley National Laboratory.

“It is amazing that these inorganic germanium sulfide nanowires so closely resemble the organic DNA structure,” said co-author Jianguo Wen, a CNM materials scientist. “Nature creates remarkable structures beyond our imagination.”

The helical DNA-like structure forms spontaneously by giving the nanowire an “Eshelby twist.” Co-first author Jie Wang, a former materials scientist in CNM (now at Thorlabs, Inc.), explained that the term “Eshelby twist” refers to its discoverer, John Eshelby.

While a research associate working at the University of Illinois at Urbana-Champaign in the 1950s, Eshelby conducted an important theoretical analysis of “screw dislocation” in a thin rod. Relating the effect to crystals, Wang noted that the “screw dislocation occurs when stress is applied to a rod shape in which the atoms become rearranged in a helical pattern.”

When applied to a germanium sulfide nanowire, this twisting causes it to elongate and widen into a helical structure.

“It is amazing that these inorganic germanium sulfide nanowires so closely resemble the organic DNA structure,” said co-author Jianguo Wen, a CNM materials scientist.  “Nature creates remarkable structures beyond our imagination.”

Also important, added CNM scientist and co-author Dafei Jin, was the finding that the nanostructure automatically divides into segments that resemble helically stacked bricks. These brick-like segments arise from the release of energy as the wire diameter grows from tens of nanometers to micrometers.

“The discovered Eshelby twist here offers a new way to engineer nanomaterials,” said Wang. “We can tailor these nanowires in many different ways — twist periods from two to twenty micrometers, lengths up to hundreds of micrometers, and radial dimensions from several hundred nanometers to about ten micrometers.”

By this means, researchers can adjust the electrical and optical properties of the nanowires to optimize performance for different applications.

“This is an important materials discovery,” Wen said. “We are excited to have figured out, using CNM’s high-resolution transmission electron microscope, the dislocation structures that drive the nanowires to have an Eshelby twist.”

Researchers at the Stanford University School of Medicine have found that neural signatures in sleeping zebrafish are analogous to those of humans, suggesting that the brain activity evolved at least 450 million years ago, before any creatures crawled out of the ocean.

Scientists have known for more than 100 years that fish enter a sleeplike state, but until now they didn't know if their sleep resembled that of land animals.

The researchers found that when zebrafish sleep, they can display two states that are similar to those found in mammals, reptiles and birds: slow-wave sleep and paradoxical, or rapid eye movement, sleep. The discovery marks the first time these brain patterns have been recorded in fish.

"This moves the evolution of neural signatures of sleep back quite a few years," said postdoctoral scholar Louis Leung, PhD.

A paper describing the research will be published July 10 in Nature. Philippe Mourrain, PhD, associate professor of psychiatry and behavioral sciences, is the senior author. Leung is the lead author.

To study the zebrafish, common aquarium dwellers also known as danios, the researchers built a benchtop fluorescent light-sheet microscope capable of full-fish-body imaging with single-cell resolution. They recorded brain activity while the fish slept in an agar solution that immobilized them. They also observed the heart rate, eye movement and muscle tone of the sleeping fish using a fluorescence-based polysomnography that they developed.

They named the sleep states they observed "slow-bursting sleep," which is analogous to slow-wave sleep, and "propagating-wave sleep," analogous to REM sleep. Though the fish don't move their eyes during REM sleep, the brain and muscle signatures are similar. (Fish also don't close their eyes when they sleep, as they have no eyelids.)

Sleeping like the fish

The researchers found another similarity between fish and human sleep. By genetically disrupting the function of melanin-concentrating hormone, a peptide that governs the sleep-wake cycle, and observing neural expressions as the fish slept, the researchers determined that the hormone's signaling regulates the fish's propagating wave sleep the way it regulates REM sleep in mammals.

Other aspects of their sleep state are similar to those of land vertebrates, Mourrain said: The fish remain still, their muscles relax, their cardio-respiratory rhythms slow down and they fail to react when they're approached.

"They lose muscle tone, their heartbeat drops, they don't respond to stimuli -- the only real difference is a lack of rapid eye movement during REM sleep," Mourrain said, though he added, "The rapid movement of the eyes is not a good criterion of this state, and we prefer to call it paradoxical sleep, as the brain looks awake while one is asleep."

While scientists can't say for certain that all animals sleep, it appears to be a universal need among vertebrates and invertebrates. Animals will die if they are deprived of sleep long enough, and people who fail to receive adequate sleep suffer from mental problems such as memory lapses and impaired judgment, along with a higher risk of disorders such as obesity and high blood pressure.

The exact benefits of sleep are still a mystery, however. "It's an essential function," Mourrain said, "but we don't know precisely what it does."

He added that sleep disorders are linked to most neurological disorders such as autism spectrum disorders, Fragile X syndrome, and Alzheimer's and Parkinson's disease. "Sleep disturbances are an aggravating factor of these disorders," Mourrain said. It is critical to develop this animal model to study sleep functions at the cellular level, including neuronal connectivity and DNA repair, and in turn understand the pathophysiological consequences of sleep disruptions, he added.

The discovery means sleep research can be conducted on zebrafish, which are easy to study, in part because they're transparent. They breed quickly, are inexpensive to care for and are just over an inch long. Drug testing requires only the addition of chemicals to their water.

"Because the fish neural signatures are in essence the same as ours, we can use information about them to generate new leads for drug trials," Leung said. He added that mice, often a stand-in for human research, are nocturnal and a less relevant model for our sleep.

"As zebrafish are diurnal like humans, it's perhaps more biologically accurate to compare fish sleep with humans' for some aspects," Leung said.

AMES, Iowa - A new study from Iowa State University entomologists describes how mosquitoes fight off parasites that cause malaria, a disease that sickens millions of people every year.

The study, published recently in the scientific journal Proceedings of the National Academy of Sciences, shows how the mosquito immune system combats malaria parasites at multiple stages of development. A better understanding of the mosquito immune response could lay the groundwork for future research to combat the transmission of malaria, said Ryan Smith, assistant professor of entomology and lead author of the study.

Roughly 219 million cases of malaria, a disease transmitted to humans by the bite of infected mosquitoes, occurred worldwide in 2017, according to the Centers for Disease Control and Prevention. Most cases are concentrated in tropical and subtropical climates such as sub-Saharan Africa and South Asia. The disease resulted in 435,000 deaths in 2017, according to the CDC.

Mosquitoes are required to transmit malaria, acquiring malaria parasites by biting an infected person, then transmitting the disease weeks later after the parasite has completed development in the mosquito. The new study focused on how the mosquito immune system responds to the parasite.

"Mosquitoes are generally pretty good at killing off the parasite," Smith said. "We wanted to figure out the mechanisms and pathways that make that happen."

The researchers treated mosquitoes with a chemical that depleted their immune cells, which are needed to defend the mosquito against pathogens. The experiments showed that malaria parasites survived at greater rates in mosquitoes when the immune cells were depleted. The research also illuminated how these immune cells promoted different "waves" of the mosquito immune response targeting distinct stages of malaria parasites in the mosquito host.

Smith, who also leads the ISU Medical Entomology Laboratory, said the findings increase the understanding of a complement-like pathway that is involved in the initial recognition and killing of parasites, similar to that found in mammals. The work also implicates phenoloxidases, an insect-specific immune response, in causing a secondary immune response directed at later stages of the malaria parasite, he said.

Understanding these immune responses could lead to opportunities to eliminate malaria parasites in the mosquito, thus reducing the transmission of malaria. For instance, Smith said scientists could use genetic approaches to make mosquitoes resistant to malaria parasites. Introducing mosquitoes with enhanced immunity in endemic areas of malaria could significantly reduce human malaria cases.

"There are more steps required to validate that kind of approach, but we think this study lays a foundation for those future experiments," Smith said.

A paper by Research Associate Daria Khanolainen appeared in Quality Assurance in Education.

"The objective was to find out how ready the teachers are to implement the expected changes. That is, do they understand what is required of them, are they motivated to implement the federal educational standard, do they have the necessary resources, etc.," explains the author.

The research took place in Tatarstan, Russia, and comprised two stages. At the first stage, 123 teachers (62 from secondary schools and 61 from primary schools) responded to a questionnaire, and then 10 of them were invited to semi-structured interviews (transcripts of questions are available at https://figshare.com/s/1c10d8ab8194457fb422).

87% of respondents were women, with 81% having over 12 years of teaching experience and 93% having obtained a graduate degree.

The results showed that teachers are only partially ready to work under a new system - 13% answered that they are completely confident to do so, while 80% approve of the new standards in general. 34% reported not receiving any support from school superiors or public administrators. 64% confessed that they lack motivation to adapt to the new regulations.

"This is in contradiction to the positive attitude towards the new standards that the teachers express in the same interview, and this can undermine the reform. Positive attitudes can be reinforced through program reevaluation, offering practical courses, school renovations, etc.," says Khanolainen.

What is "water in the mantle"?

Hydrogen is the most abundant element in our solar system. In the Earth, hydrogen exists as vapor in the atmosphere, water and ice in the ocean, super-critical fluids in the volcanoes and Earth crusts, hydroxyls in hydrous and nominally anhydrous minerals in the Earth's crust and mantle, proton and hydroxyl (OH) in magmas, and hydrogen in metallic iron in the Earth's core.

Hydrogen and water play important roles in dynamics of the Earth's interior. They lower the internal friction of rocks and cause earthquakes and fracturing. Water generates magmas by lowering the melting temperature of silicates in the mantle. Water softens rocks and enhances mantle convection.

How much "water in the mantle" is there? How it works?

Seismic and electrical conductivity observations combined with experimental mineral physics data on sound velocity and electrical conductivity of minerals suggest the transition zone that is hydrated at least locally. Continental and oceanic sediment components together with the basaltic and peridotite components might be stored in the mantle transition zone. Low seismic velocity regions have been reported at around 410 km beneath some plate convergent regions. These regions might be caused by the existence of dense volatile rich magmas.

Water can be carried further into the lower mantle by descent of the slabs due to gravitational instability. The anomalous Q and Vs regions might be created at the top of the lower mantle. Dehydration from the slabs produces fluids or hydrous melts in this region due to a large difference of the water solubility between the transition zone and lower mantle assemblages. Although hydrous magmas without density crossover can escape upwards, continuous descent of the slabs causes dehydration from the slabs and produces low Q and Vs regions at the shallow part of the lower mantle. Δ-H solid solution AlO2H-MgSiO4H2 is a major carrier of water into the lower mantle. The hydrogen bond symmetrization could occur in various hydrous phases stable in the mantle.

The core-mantle boundary (CMB) is a region where extensive reaction between water and iron might occur. The Δ-H solid solution is stable to the CMB conditions. Therefore, this hydrous phase carries water into the base of lower mantle and also into the core. Pyrite FeO2Hx can be formed due to a reaction between the core and hydrated slabs at CMB. This phase could be a potential candidate existing at ULVZ. Formation of FeO2Hx and its decomposition due to its thermal instability at CMB could cause global geodynamical events.

Mathematical thought is seen as the pinnacle of abstract thinking. But are we capable of filtering out our knowledge about the world to prevent it from interfering with our calculations? Researchers from the University of Geneva (UNIGE), Switzerland, and the University of Bourgogne Franche-Comté, France, have demonstrated that our ability to solve mathematical problems is influenced by non-mathematical knowledge, which often results in mistakes. The findings, published in Psychonomic Bulletin & Review, indicate that high-level mathematicians can be duped by some aspects of their knowledge about the world and fail to solve primary school-level subtraction problems. It follows that this bias needs to be factored into the way mathematics is taught.

Maths teaching at school usually draws on examples taken from everyday life. Whether it's adding up oranges and apples to make a pie or dividing a bunch of tulips by the number of vases for a floral arrangement, we master mathematics with the help of concrete examples. But to what extent do the examples chosen affect a child's ability to use the mathematical concepts in new contexts?

Researchers from UNIGE and the University of Bourgogne Franche-Comté tested the degree to which our worldly knowledge interferes with mathematical reasoning by presenting twelve problems to two distinct groups. The first group consisted of adults who had taken a standard university course, while the second was composed of high-level mathematicians. "We speculated that the adults and mathematicians alike would rely on their knowledge about the world, even when it would lead them to make mistakes," explains Hippolyte Gros, a researcher in UNIGE's Faculty of Psychology and Educational Sciences (FPSE).

Counting animals versus counting centimetres

When faced with numbers, we tend to represent them mentally either as sets or as values on axes. "We devised six 5th grade subtraction problemss (i.e. for pupils aged 10-11) that could be represented by sets, and six others that could be represented by axes", begins Emmanuel Sander, an FPSE professor. "But all of them had exactly the same mathematical structure, the same numerical values and the same solution. Only the context was different." These problems were presented in two different types of contexts. Half of the problems involved calculating the number of animals in a pack, the price of a meal in a restaurant or the weight of a stack of dictionaries (elements that can be grouped together as sets). For example: "Sarah has 14 animals: cats and dogs. Mehdi has two cats fewer than Sarah, and as many dogs. How many animals does Mehdi have?" The second type of problems required calculating how long it takes to build a cathedral, to which floor an elevator arrives or how tall a Smurf is (statements that can be represented along a horizontal or vertical axis). For example: "When Lazy Smurf climbs onto a table, he attains 14 cm. Grumpy Smurf is 2 cm shorter than Lazy Smurf, and he climbs onto the same table. What height does Grumpy Smurf attain".

These mathematical problems can all be solved via a single calculation: a simple subtraction. "This is instinctive for the problems represented on an axis (14 - 2 = 12, in the case of the Smurfs) but we need to change perspective for the problems describing sets, where we automatically try and work out the individual value of each mentioned subset, which is impossible to do. For instance, in the problem with animals, we look to calculate the number of dogs that Sarah has, which is impossible, whereas the calculation 14 - 2 = 12 provides the solution directly", explains Jean-Pierre Thibaut, a researcher at the University of Bourgogne Franche-Comté. The scientists relied on the fact that the answer would be more difficult to find for the animal problems than the Smurf problems, despite their shared mathematical structure.

When worldly knowledge impedes mathematical reasoning

"We presented the twelve problems to both groups of participants. Each problem was accompanied by its solution and the participants had to decide whether it was correct or if the problem couldn't be solved," adds Gros. And the results were astonishing! In the non-expert adult group, 82% answered correctly for the axis problems, compared to only 47% for the problems involving sets. In 53% of cases the respondents thought that there was no solution to the statement, reflecting their inability to detach themselves from their knowledge about the elements mentioned in the statements. Regarding the expert mathematicians, 95% answered correctly for the axis problems, a rate that dropped to only 76% for the sets problems! "One out of four times, the experts thought there was no solution to the problem even though it was of primary school level! And we even showed that the participants who found the solution to the set problems were still influenced by their set-based outlook, because they were slower to solve these problems than the axis problems", continues the Geneva-based researcher.

The results highlight the critical impact our knowledge about the world has on our ability to use mathematical reasoning. They show that it is not easy to change perspective when solving a problem. Thus they argue that we need to take this bias into account in math education. "We see that the way a mathematical problem is formulated has a real impact on performance, including that of experts, and it follows that we can't reason in a totally abstract manner," says professor Sander. Educational initiatives need to be introduced based on methods that help pupils learn about mathematical abstraction. "We have to detach ourselves from our non-mathematical intuition by working with students in non-intuitive contexts!" concludes Gros.

Scientists from the Skoltech Center for Energy Science and Technology, the Institute for Problems of Chemical Physics of RAS, and the Department of Chemistry of MSU presented solar cells based on conjugated polymers and fullerene derivatives, that demonstrated record-high radiation stability and withstand gamma radiation of >6,000 Gy raising hopes for their stable operation on the near-earth orbit during 10 years or even longer. The results of the study were published in ACS Applied Materials & Interfaces.

As the Soviet Union launched the first-ever satellite some 60 years ago, its radio signal transmitted at three frequencies could be captured anywhere on Earth. However, three weeks later the transmitter went silent, having consumed all the power provided by the onboard batteries which accounted for a larger part of the satellite's weight. A lesson was learnt from the first launch and all satellites that followed carried solar cells that convert the energy of light into electricity to power the onboard electronic systems. Silicon solar cells and photoelectric converters based on the elements from groups 3 and 5 of the periodic table (A3B5) are the most common varieties despite their multiple drawbacks, including heavy weight and, therefore, a low energy-to-weight ratio. To top it off, they are fragile and easily affected by ionizing radiation: unlike high-energy particle flows that can be fended off by encapsulation, gamma rays have high penetrating capability and are more difficult to manage. The formation and accumulation of radiation-induced defects in a crystal structure of conventional inorganic semiconductors cause severe degradation of their electronic properties and quick decay of the solar cells efficiency.

Over the past two decades, organic solar cells have garnered much attention thanks to their light weight, flexibility and unprecedented energy-to-weight ratios of 10 to 20 W/g, which make them a promising candidate for space applications, although their radiation stability is still poorly understood.

Earlier, a group of researchers led by Skoltech professor Pavel Troshin studied the radiation stability of perovskite solar cells and showed that current generation complex lead halides are too sensitive to γ-rays to be used in space. The researchers were far more optimistic about the organic solar cells, which exhibited excellent radiation stability in their recent study.

"The carbazole-containing conjugated polymers selected for the study ensure a long operation lifetime and fairly high light conversion efficiency of solar cells under standard terrestrial conditions, as we demonstrated back in 2015. In this paper, we examine the behavior of two model fullerene-polymer systems exposed to γ-rays. One of the two systems displayed record-high radiation stability, with the solar cells retaining over 80% of their initial efficiency after exposure to 6,500 Gy of γ-rays ? a dose that near-Earth orbit satellites are estimated to receive during 10 years or longer. This is just one of our first achievements in this research thrust and we will pursue the development of even more stable and efficient organic solar cells for space applications," says the first author of the paper, Ilya Martynov.

The high radiation stability revealed by organic solar cells based on carbazole-containing conjugated polymers is indicative of their extensive space potential, with their light weight, flexibility and high energy-to-weight ratio enabling a significant reduction in the ballast weight and increase in the payload.

"Deploying space solar sails made of flexible plastic solar cells represents an enticing opportunity for ramping up the power of photoelectric converters on the satellites," says Prof. Troshin.

New evidence suggests that adolescent bullying and victimization may have origins in the home. Many bullies have parents who are hostile, punitive and rejecting. Researchers from Florida Atlantic University's Charles E. Schmidt College of Science, Concordia University in Montreal, Canada, and Uppsala University in Sweden, have identified another type of parenting that contributes to peer difficulties: those who direct derision and contempt at their children.

Derisive parents use demeaning or belittling expressions that humiliate and frustrate the child, without any obvious provocation from the child. These parents respond to child engagement with criticism, sarcasm, put-downs and hostility, and rely on emotional and physical coercion to obtain compliance.

The study, published in the Journal of Youth and Adolescence, emphasizes the emotional underpinnings of peer difficulties. The researchers followed 1,409 children for three consecutive years from grades 7 to 9 (ages 13-15 years).

Findings show that derisive parenting fosters dysregulated anger in adolescent children. Dysregulated anger is indicative of difficulties regulating emotion, which typically result in negative emotions, verbal and physical aggression, and hostility. Increases in dysregulated anger, in turn, place adolescents at greater risk for bullying and victimization, and for becoming bully-victims (bullies who also are victimized by other bullies).

The latter finding is noteworthy given that past research indicates that bully-victims are at the greatest risk for poor mental health, behavioral difficulties, and suicidal thoughts when compared to "pure" victims, "pure" bullies, or non-victims. Identification of the family-specific origins of bully-victim status may be a key step in limiting or preventing such poor outcomes.

Importantly, these findings held after controlling for parenting behaviors implicated in child adjustment, such as warmth, control and physical punishment. This study suggests that derisive behavior is a unique form of parenting that increases the risks that adolescent children will adopt inappropriate anger management strategies that increases their risk for peer difficulties.

"Inappropriate interpersonal responses appear to spread from parents to children, where they spawn peer difficulties. Specifically, derisive parenting precipitates a cycle of negative affect and anger between parents and adolescents, which ultimately leads to greater adolescent bullying and victimization," said Brett Laursen, Ph.D., co-author and a professor of psychology in FAU's Charles E. Schmidt College of Science. "Our study is important because it provides a more complete understanding of how parents' belittling and critical interactions with adolescents thwart their ability to maintain positive relationships with peers."

Daniel J. Dickson, Ph.D., Department of Psychology at Concordia University, is the senior author of the study.

"Implications from our study are far-reaching: practitioners and parents should be informed of the potential long-term costs of sometimes seemingly harmless parenting behaviors such as belittlement and sarcasm," said Dickson. "Parents must be reminded of their influence on adolescents' emotions and should take steps to ensure that adolescents do not feel ridiculed at home."

Wandering through the Harvard campus one day in 2015, graduate student Andrew Yegian recalls how something unusual caught his eye. 'I noticed a person running with straight arms', he explains. This really stood out for Yegian, as runners usually bend the elbow, while walkers keep their arms straight, which made him wonder: 'If straight arms are better for walking, why aren't they better for running, and vice versa?' he puzzled. Was there a trade-off between the cost of keeping the elbow bent and swinging the arm at the shoulder that could benefit runners? Could walkers conserve energy by keeping their swinging arms straight? Intrigued, Yegian and this thesis advisor, Dan Lieberman, decided to film athletes walking and running with straight and bent arms to find out why runners keep their arms bent while walkers let them swing loose. They publish their discovery that walking with a straight arm is much more efficient than walking with a bent arm in Journal of Experimental Biology at http://jeb.biologists.org.

Selecting eight undergraduate and graduate students - ranging from runners who dabbled twice a week to serious marathon competitors - to walk and run on a treadmill, Yegian says, 'We wanted to study that kind of variation because bent arm running seems to be an almost universal behaviour, regardless of how much a person runs'. Together with undergraduates Yanish Tucker and Stephen Gillinov, Yegian placed reflective markers on the athletes' shoulders, elbows and wrists before asking the runners to walk at ~1.4 m s?1 and run at ~3 m s?1 with straight and bent arms while they filmed the volunteers' movements in 3D. 'The hardest thing was running with straight arms', recalls Yegian, adding that all of the athletes found the movement strange. Then, Yegian and his undergraduate colleagues invited the volunteers to return 2 weeks later, so they could repeat the running and walking trials, but this time the athletes breathed through a mask to measure their oxygen consumption, allowing the scientists to calculate their energy consumption as they moved with their arms in different positions.

Comparing the energy costs, the team was impressed that holding the arms bent while walking increases the walkers' cost by 11%. And when they calculated the amount of effort required to keep the arm crooked, it was clear that bending the elbow came at a cost, although this was slightly offset by the lower cost of swinging the relatively short arm. So, walking with straight arms is by far the most efficient option.

However, when the team compared the runners' energy costs, the outcome was less clear. 'We didn't find any evidence that the energy cost was different between arm postures when running', says Yegian, who had suspected that running with bent arms would be more efficient, 'since that's what almost everyone does', he says.

So the jury is still out as to why runners bend their arms, although Yegian suspects that there must be some benefit that bears no relation to energetic costs, which keeps runners' arms pumping when pounding the streets.

Researchers have developed a new technique to help doctors more quickly and accurately detect autism spectrum disorder (ASD) in children.

In a study led by the University of Waterloo, researchers characterized how children with ASD scan a person's face differently than a neuro-typical child. Based on the findings, the researchers were able to develop a technique that considers how a child with ASD gaze transitions from one part of a person's face to another.

According to the developers, the use of this technology makes the diagnostic process less stressful for the children and if combined with existing manual methods could help doctors better avoid a false positive autism diagnosis.

"Many people are suffering from autism, and we need early diagnosis especially in children," said Mehrshad Sadria, a master's student in Waterloo's Department of Applied Mathematics. "The current approaches to determining if someone has autism are not really child-friendly. Our method allows for the diagnosis to be made more easily and with less possibility of mistakes.

"The new technique can be used in all ASD diagnosis, but we believe it's particularly effective for children."

In developing the new technique, the researchers evaluated 17 children with ASD and 23 neuro-typical children. The mean chronological ages of the ASD and neuro-typical groups were 5.5 and 4.8, respectively.

Each participant was shown 44 photographs of faces on a 19-inch screen, integrated into an eye-tracking system. The infrared device interpreted and identified the locations on the stimuli at which each child was looking via emission and reflection of wave from the iris.

The images were separated into seven key areas of interest (AOIs) in which participants focussed their gaze: under the right eye, right eye, under the left eye, left eye, nose, mouth and other parts of the screen. The researchers wanted to know more than how much time the participants spent looking at each AOI, but also how they moved their eyes and scan the faces. To get that information, the researchers used four different concepts from network analysis to evaluate the varying degree of importance the children placed on the seven AOIs when exploring the facial features.

The first concept determined the number of other AOIs that the participant directly moves their eyes to and from a particular AOI. The second concept looked at how often a particular AOI is involved when the participant moves their eyes between two other AOIs as quickly as possible. The third concept is related to how quickly one can move their eyes from a particular AOI to other AOIs. The fourth concept measured the importance of an AOI, in the context of eye movement and face scanning, by the number of important AOIs that it shares direct transitions with.

Currently, the two most favoured ways of assessing ASD involve a questionnaire or an evaluation from a psychologist.

"It is much easier for children to just look at something, like the animated face of a dog, than to fill out a questionnaire or be evaluated by a psychologist," said Anita Layton, who supervises Sadria and is a professor of Applied Mathematics, Pharmacy and Biology at Waterloo. "Also, the challenge many psychologists face is that sometimes behaviours deteriorate over time, so the child might not display signs of autism, but then a few years later, something starts showing up.

"Our technique is not just about behaviour or whether a child is focussing on the mouth or eyes. It's about how a child looks at everything."

The study, Network Centrality Analysis of Eye-gaze Data in Autism Spectrum Disorder, authored by Waterloo's Faculty of Mathematics researchers Sadria, Layton and Shahid Beheshti University's Department of Physics graduate student, Soroush Karimi, was recently published in the journal Computers in Biology and Medicine.

For the first time, scientists grappling with how to improve the efficiency of CRISPR technology -- a gene-editing platform that uses an enzyme called Cas9 to precisely cut and edit specific sequences of DNA within a live cell -- have captured atomic-level, three-dimensional images of the enzyme before and after cutting the DNA.

The images provide new structural information on how the enzyme works and will help researchers develop modified versions of the enzyme that can more efficiently and precisely alter targeted genes. The images and insights into Cas9 made from them are published in Nature Structural and Molecular Biology.

CRISPR is a gene-editing tool that allows scientists to cut out unwanted genes or genetic material from DNA or add a desired sequence within a gene to change its function or regulate its activity. CRISPR uses an enzyme called Cas9 that acts like scissors that cut a specific DNA sequence. Once cuts are made on either side of the DNA, the cell initiates repair systems that rejoin the two ends of the DNA strands back together.

"One of the main hurdles preventing the development of better gene-editing tools using Cas9 is that we didn't have any images of the enzyme after the cutting DNA and did not have complete information about the changes this very important enzyme undergoes to execute the reaction," said Miljan Simonovic, associate professor of biochemistry and molecular genetics at the University of Illinois at Chicago and a corresponding author on the paper.

Earlier structural images of Cas9 have been obtained using X-ray crystallography, but this approach has limitations. To capture various states of the enzyme in crystalline form, researchers use either inactive Cas9 (a version of the enzyme that doesn't cleave DNA) or form the crystals under conditions that don't support DNA cleavage. These processes can only produce images of the enzyme before it makes its cut.

"Researchers interested in either modulating Cas9 activity or engineering mutant enzymes that might work better just didn't have complete information to begin with, so advancement was not as fast as desired," Simonovic said. "But now we have a much clearer picture, and we even see how the major domains of the enzyme move during reaction, which may be important for further exploration."

"It is exciting to be able to see how Cas9 actually works to cut and edit DNA strands at such a high level of detail," said the study's co-senior author, Sriram Subramaniam, professor of medicine at the University of British Columbia. "These images provide us with invaluable information to improve the efficiency of the gene-editing process so that we can hopefully correct disease-causing DNA mutations more quickly and precisely in the future."

Simonovic knew a different imaging technique was needed in order to really see Cas9 at work. In the last decade, cryogenic electron microscopy, or cryo-EM, has become well known for its ability to image large molecules at high resolution under conditions that approximate their natural environments.

Simonovic and his colleagues used active Cas9 along with DNA and guide RNA. Magnesium, which is required to activate the enzyme for DNA cleavage, was added and Cas9 complexes were flash frozen and imaged using cryo-EM. The end results were snapshots of Cas9 trapped in three distinct structural arrangements while bound to nucleic acids. Most remarkably, in two of the three states, the target DNA was cleaved but the enzyme remained bound to it, allowing this final step of the biochemical reaction sequence to be observed with high resolution.

In the first state, the enzyme is captured before cutting DNA, with its major domains "assessing" if the sequence to be cut is proper. In the second, Cas9 was imaged almost immediately after the cut in the DNA is made. Practically, the enzyme's active site hovers above the cut in the DNA strand. And, in the third state, the enzyme began its movement toward its departure from the cleaved DNA.

"We discovered several new things about how Cas9 interacts with DNA and how it operates. One of the most interesting is how several enzyme domains move in concert and cycle between ordered and disordered states during reaction. This feature of the enzyme in which some domains are stable while others seem to be in a process of rapidly moving between different conformational states before settling down has not been seen nor predicted before," Simonovic said. "This new information could be used to modulate how Cas9 processes targeted DNA and could help the design of better genome-editing tools."

The discovery of Tamu Massif, a gigantic volcano located about 1,000 miles east of Japan, made big news in 2013 when researchers reported it was the largest single volcano documented on earth, roughly the size of New Mexico.

New findings, reported this week in Nature Geoscience, conclude that it is a different breed of volcanic mountain than earlier thought, throwing into doubt the prior claim that it is the world's largest single volcano.

The study analyzed magnetic field data over Tamu Massif, finding that magnetic anomalies - perturbations to the field caused by magnetic rocks in the Earth's crust - resemble those formed at mid-ocean ridge plate boundaries.

William Sager, a geophysicist at the University of Houston and senior author for the paper, said the discovery led researchers to conclude that Tamu Massif formed by mid-ocean ridge "spreading," the geologists' term for creation of ocean crust at mid-ocean ridge plate boundaries, rather than as a shield volcano, as previously thought. Shield volcanos are formed primarily as stacks of fluid lava flows and are one of the most common types of volcano.

An international group of researchers - from Texas, China and Japan - sought to understand how the massive Tamu Massif volcano formed near the nexus of three spreading ridges. The key, they report, is magnetic anomalies.

Mid-ocean ridges - plate boundaries where oceanic plates move apart - are themselves large volcanoes. These ridges record distinctive linear magnetic anomalies, parallel to the ridge, as they form new crust. This is a result of lava flows and magma being concentrated near the ridge axis where the magnetic minerals in the new crust record reversals of the magnetic field polarity.

A New Understanding of Tamu Massif

Linear magnetic anomalies formed by the three ridges had previously been found around Tamu Massif, but it was unclear where they stopped within the volcano. A paper published in 2013 by Sager and colleagues concluded that Tamu Massif is an enormous shield volcano, formed by far-reaching lava flows emanating from its summit.

The latest study compiled a magnetic anomaly map over Tamu Massif, using 4.6 million magnetic field readings collected over 54 years along 72,000 kilometers of ship tracks. The data set was anchored by a new grid of magnetic profiles, positioned with modern GPS navigation, collected by the study authors using the Schmidt Ocean Institute ship Falkor. The resulting map shows that linear magnetic anomalies around Tamu Massif blend into linear anomalies over the mountain itself - implying that the underwater volcano formed by extraordinary mid-ocean ridge crustal formation.

Sager said the finding is important because it demonstrates that Tamu Massif and other oceanic plateaus are formed by a different process than previously thought. A widely-accepted model suggests a large blob of magma, known as a "mantle plume," rises through the mantle and creates a massive volcano when it arrives at the surface. This eruption is thought to be analogous to massive eruptions on land, called "continental flood basalts" and it creates a vertical succession of lava flows.

The ocean-ridge-spreading hypothesis suggests the age progression is instead lateral. New material is always added at the center of the ridge as older material drifts laterally away. An implication is that the gradual slopes of Tamu Massif are not caused by lava flow shape but instead by a gradual inflation and then deflation of ridge volcanism as the crust became thicker and then grew thinner.

The new finding also weakens the accepted analogy between eruptions of continental flood basalts and oceanic plateaus because the formation mechanisms are shown to be different, Sager said.

'Certainly One of the Largest'

With the discovery, Sager said Tamu Massif can no longer be considered the world's largest shield volcano. That title reverts to Mauna Loa, on the island of Hawaii.

"The largest volcano in the world is really the mid-ocean ridge system, which stretches about 65,000 kilometers around the world, like stitches on a baseball," Sager said. "This is really a large volcanic system, not a single volcano."

Researchers now think Tamu Massif formed as part of that mid-ocean ridge system, he said. "Tamu Massif is certainly one of the largest volcanic mountains in the world."

The 2013 paper was based on what researchers knew at the time, Sager said. "Science is a process and is always changing. There were aspects of that explanation that bugged me, so I proposed a new cruise and went back to collect the new magnetic data set that led to this new result.

"In science, we always have to question what we think we know and to check and double check our assumptions. In the end, it is about getting as close to the truth as possible - no matter where that leads."

The chemistry of drip waters that form stalagmites and stalactites in caves around the world have given researchers an insight into our past climate.

In the first ever global analysis of cave drip water, an international team, led by Andy Baker at UNSW Australia and including scientists from Cardiff University, have explored how stalagmites and stalactites can show how groundwater resources have recharged in the past.

Groundwater, found underground in the cracks and pore spaces in rocks and sediments, is the largest source of usable freshwater in the world, and is relied on by more than two billion people as a source of drinking and irrigation water.

Groundwater resources are replenished predominantly through rainfall in a process known as recharge. At the same time, water exits or discharges from groundwater resources into lakes, streams and oceans to maintain an overall balance.

If there is a change in recharge, for example due to a reduction in rainfall as a result of climate change, the levels of water in the ground will begin to change until a new balance is achieved.

However, questions remain about how groundwater will be specifically impacted by future climate change, and where and when any changes will take place.

Though it has historically been difficult to determine past groundwater changes, scientists have recently made progress using new methods involving stalactites and stalagmites.

The oxygen isotope composition of stalagmites and stalactites found in caves can hold valuable clues about our past climate.

This oxygen comes from the water dripping from the stalactites and onto the stalagmites. The drip water originally comes from rainfall, providing a direct link to the surface climate.

Understanding the extent to which the oxygen isotopic composition of drip water is related to rainfall is a fundamental research question which will unlock the full climate potential of stalagmites and stalactites.

In their study, which has been published in Nature Communications, the team explored 163 sites from 39 caves on five continents, comparing the oxygen isotope composition of drip water to that of rainfall and groundwater recharge.

In cool climates, cave drip water oxygen isotope composition was similar to that of rainfall, meaning that stalagmite oxygen isotopes might best preserve past rainfall in these regions.

In warmer climates, and strongly seasonal climates, cave drip water oxygen isotope composition was similar to that of modelled groundwater recharge, meaning the records are more likely to preserve a record of past groundwater recharge.

Dr Mark Cuthbert, from Cardiff University's School of Earth and Ocean Sciences, and co-author of the study, said: "These results are particularly important for interpreting records of past groundwater recharge from stalagmites in dryland regions. This can help us understand the relationship between climate variability and water resources in naturally water scarce parts of the world and inform water management strategies in the context of climate change."

UPTON, NY--Solar energy harvested by semiconductors--materials whose electrical resistance is in between that of regular metals and insulators--can trigger surface electrochemical reactions to generate clean and sustainable fuels such as hydrogen. Highly stable and active catalysts are needed to accelerate these reactions, especially to split water molecules into oxygen and hydrogen. Scientists have identified several strong light-absorbing semiconductors as potential catalysts; however, because of photocorrosion, many of these catalysts lose their activity for the water-splitting reaction. Light-induced corrosion, or photocorrosion, occurs when the catalyst itself undergoes chemical reactions (oxidation or reduction) via charge carriers (electrons and "holes," or missing electrons) generated by light excitation. This degradation limits catalytic activity.

Now, scientists from the Center for Functional Nanomaterials (CFN)--a U.S. Department of Energy (DOE) Office of Science User Facility at Brookhaven National Laboratory--have come up with a technique for optimizing the activity of one such catalyst: 500-nanometer-long but relatively thin (40 to 50 nanometers) wire-looking nanostructures, or nanowires, made of zinc oxide (ZnO). Their technique--described in a paper published online in Nano Letters on May 3--involves chemically treating the surface of the nanowires in such a way that they can be uniformly coated with an ultrathin (two to three nanometers thick) film of titanium dioxide (titania), which acts as both a catalyst and protective layer.

The CFN-led research is a collaboration between Brookhaven Lab's National Synchrotron Light Source II (NSLS-II)--another DOE Office of Science User Facility-- and Computational Science Initiative (CSI); the Center for Computational Materials Science at the Naval Research Laboratory; and the Department of Materials Science and Chemical Engineering at Stony Brook University.

"Nanowires are ideal catalyst structures because they have a large surface area for absorbing light, and ZnO is an earth-abundant material that strongly absorbs ultraviolet light and has high electron mobility," said co-corresponding author and study lead Mingzhao Liu, a scientist in the CFN Interface Science and Catalysis Group. "However, by themselves, ZnO nanowires do not have high enough catalytic activity or stability for the water-splitting reaction. Uniformly coating them with ultrathin films of titania, another low-cost material that is chemically more stable and more active in promoting interfacial charge transfer, enhances these properties to boost reaction efficiency by 20 percent compared to pure ZnO nanowires."

To "wet" the surface of the nanowires for the titania coating, the scientists combined two surface processing methods: thermal annealing and low-pressure plasma sputtering. For the thermal annealing, they heated the nanowires in an oxygen environment to remove defects and contaminants; for the plasma sputtering, they bombarded the nanowires with energetic oxygen gas ions (plasma), which ejected oxygen atoms from the ZnO surface.

"These treatments modify the surface chemistry of the nanowires in such a way that the titania coating is more likely to adhere during atomic layer deposition," explained Liu. "In atomic layer deposition, different chemical precursors react with a material surface in a sequential manner to build thin films with one layer of atoms at a time."

The scientists imaged the nanowire-shell structures with transmission electron microscopes at the CFN, shining a beam of electrons through the sample and detecting the transmitted electrons. However, because the ultrathin titania layer is not crystalline, they needed to use other methods to decipher its "amorphous" structure. They performed x-ray absorption spectroscopy experiments at two NSLS-II beamlines: Inner-Shell Spectroscopy (ISS) and In situ and Operando Soft X-ray Spectroscopy (IOS).

"The x-ray energies at the two beamlines are different, so the x-rays interact with different electronic levels in the titanium atoms," said co-author Eli Stavitski, ISS beamline physicist. "The complementary absorption spectra generated through these experiments confirmed the highly amorphous structure of titania, with crystalline domains limited to a few nanometers. The results also gave us information about the valence (charge) state of the titanium atoms--how many electrons are in the outermost shell surrounding the nucleus--and the coordination sphere, or the number of nearest neighboring oxygen atoms."

Theorists and computational scientists on the team then determined the most likely atomic structure associated with these experimental spectra. In materials with crystalline structure, the arrangement of an atom and its neighbors is the same throughout the crystal. But amorphous structures lack this uniformity or long-range order.

"We had to figure out the correct combination of structural configurations responsible for the amorphous nature of the material," explained co-corresponding author Deyu Lu, a scientist in the CFN Theory and Computation Group. "First, we screened an existing structural database and identified more than 300 relevant local structures using data analytics tools previously developed by former CFN postdoc Mehmet Topsakal and CSI computational scientist Shinjae Yoo. We calculated the x-ray absorption spectra for each of these structures and selected 11 representative ones as basis functions to fit our experimental results. From this analysis, we determined the percentage of titanium atoms with a particular local coordination."

The analysis showed that about half of the titanium atoms were "undercoordinated." In other words, these titanium atoms were surrounded by only four or five oxygen atoms, unlike the structures in most common forms of titania, which have six neighboring oxygen atoms.

To validate the theoretical result, Lu and the other theorists--Mark Hybertsen, leader of the CFN Theory and Computation Group; CFN postdoc Sencer Selcuk; and former CFN postdoc John Lyons, now a physical scientist at the Naval Research Lab--created an atomic-scale model of the amorphous titania structure. They applied the computational technique of molecular dynamics to simulate the annealing process that produced the amorphous structure. With this model, they also computed the x-ray absorption spectrum of titania; their calculations confirmed that about 50 percent of the titanium atoms were undercoordinated.

"These two independent methods gave us a consistent message about the local structure of titania," said Lu.

"Fully coordinated atoms are not very active because they cannot bind to the molecules they do chemistry with in reactions," explained Stavitski. "To make catalysts more active, we need to reduce their coordination."

"Amorphous titania transport behavior is very different from bulk titania," added Liu. "Amorphous titania can efficiently transport both holes and electrons as active charge carriers, which drive the water-splitting reaction. But to understand why, we need to know the key atomic-scale motifs."

To the best of their knowledge, the scientists are the first to study amorphous titania at such a fine scale.

"To understand the structural evolution of titania on the atomic level, we needed scientists who know how to grow active materials, how to characterize these materials with the tools that exist at the CFN and NSLS-II, and how to make sense of the characterization results by leveraging theory tools," said Stavitski.

Next, the team will extend their approach of combining experimental and theoretical spectroscopy data analysis to materials relevant to quantum information science (QIS). The emerging field of QIS takes advantage of the quantum effects in physics, or the strange behaviors and interactions that happen at ultrasmall scales. They hope that CFN and NSLS-II users will make use of the approach in other research fields, such as energy storage.

The team of Toma Susi at the University of Vienna uses a state-of-the-art electron microscope, the UltraSTEM, to manipulate strongly bound materials with atomic precision. Since the instruments used are fully computerized, it is possible to show in a simulation how researchers actually use them. This allows for compelling and largely realistic presentations of the most recent research in materials science. A simulation game on display at the Vienna Technical Museum in their special exhibition "Work & Production; thinking_forward_" is now also released online, together with the latest research advance of silicon impurity manipulation in single-walled carbon nanotubes.

Electron microscopes enable much greater resolution than optical microscopes. While optical microscopes image using visible light and thus can image objects down to a thousandth of a millimeter, electron microscopes use electron beams and can image much smaller objects, down to individual atoms, such as silicon impurities in the lattice of graphene. The Nion UltraSTEM scanning transmission electron microscope of the University of Vienna allows a 50,000,000x magnification, and is fully computer-controlled. Since image contrast depends on how much the electrons are scattered at each location - which in turn is determined by the charge of the nucleus, with silicon having more protons than carbon - we can directly see the where the impurities are located.

In addition to imaging, the focused electron beam of the microscope can be used to move the atoms. Each electron of this beam has a small chance of being scattered back by the nucleus of this targeted atom, giving the atom a small push in the opposite direction, as revealed by earlier research by the group. The electron beam scans across a graphene sample line by line, revealing the locations of the carbon atoms that make up the lattice, as well as the brighter silicon impurities. In practice, the electron beam is directed by moving a mouse cursor on a computer screen, which controls the microscope electronics. "So, in effect, we are playing a computer game in order to do our research", Susi explains. He continues. "I used to play many games when I was younger, and I notice that I am faster than some of my younger colleagues who are more used to touch screens!"

The simulation game has been part of the special exhibition "Work & Production; thinking_forward_" at the Vienna Technical Museum that opened last November, and also features typical samples used for the research as well as information on the underlying physics. Now, to reach an even larger audience, the team is launching a website with the same content, including a browser-based version of the simulation game called "Atom Tractor Beam". The name is inspired by the science fiction concept of an attractive beam of energy popularized by Star Trek. "The name is appropriate since the silicon impurities move to the location where the cursor is pointed, as if attracted by the electron beam", Susi concludes.

Concurrently with the launch of the website, the team has reported their latest research advance in atom manipulation in an article published by Advanced Functional Materials. In this work, the team demonstrates that silicon impurities, which have thus far been studied in graphene, can also be controllably manipulated in a new material, namely single-walled carbon nanotubes. Since these are confined one-dimensional structures, this advance may enable new kinds of tunable electronic devices.