The study, an extension of previous data mining work that was carried out on measurements acquired at the same station, uses an additional 10 years of data, which is expected to enhance the reliability of the results and accuracy of the conclusions. In contrast to the previous studies that used data mining methods based on clustering and classification, the new approach looked at the mutual information between observed new-particle formation events and a variety of measured variables. The method was shown to be powerful and computationally light, highlighting its potential as a useful tool.

“The conclusions reached using our analysis were found to agree with previous findings; however, the analysis was achieved without supervision and did not require a deep understanding of the physics,” study coauthor Adam Foster says. “Previous studies have required involved field, lab, and theory work, so being able to get to where we have through data analysis is a very positive step for future studies.”

The work showed that new-particle formation was strongly correlated with water content and sulfuric acid concentration, as well as other factors such as temperature, relative humidity, condensation sink (how quickly molecules and small particles condense onto existing particles), and radiation.

“We hope that the method will provide a robust first option for analyzing atmospheric data sets,” says Foster. “We aim to extend our approach to data sets from other SMEAR stations, as well as to use it to investigate different phenomena and their influences.”

These findings are expected to be implemented widely in the field of atmospheric science. It is hoped that the effect of other variables such as volatile organic compounds and aerosol particles below 3 nm can be assessed using the reported approach.

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Now, a team of researchers at Kanazawa University in Japan have made an important step towards identifying a biomarker based on motor-related brain activity. Their work followed on from the key hypothesis that autism results from an excitatory and inhibitory imbalance in the brain, which is associated with repetitive brainwaves called gamma oscillations. A reduction in this type of brain activity has been seen during visual, auditory, and tactile stimulation in individuals with ASD.

The researchers set out to further explore motor-induced gamma oscillations in children with ASD, and recently reported their findings in The Journal of Neuroscience.

They formed two groups of children who were 5-7 years old. Those in the first group were conventionally diagnosed with ASD, while the second group was made up of children classed as developing typically. The children each performed a video-game-like task where they had to press a button with their right finger, while in a relaxed environment. Magnetoencephalography, which records magnetic activity from neurons, was used to monitor the children’s brainwaves during the task.

“We measured the button response time, motor-evoked magnetic fields, and motor-related gamma oscillations,” study corresponding author Mitsuru Kikuchi says. “As found in other studies, the ASD children’s response time was slightly slower and the amplitude in their magnetic fields was a bit decreased. The gamma oscillations were where we saw significant and interesting differences.”

There was a considerably lower peak frequency of the gamma oscillations in the ASD group. A lower peak frequency of motor-related gamma oscillations also signaled low concentration of the inhibitory neurotransmitter GABA, which has also been found associated with ASD. The findings additionally suggest delayed development of motor control in young children with ASD. Collectively the behavioral performance and brainwave findings offer promise for ASD diagnosis.

“Early diagnosis of ASD is highly important so that we can actively manage the disorder as soon as possible,” first author Kyung-min An says. “These findings may prove to be extremely useful in helping us understand the neurophysiological mechanism behind social and motor control development in children with ASD. Using magnetoencephalography in this way gives us a noninvasive and quantifiable biomarker, which is something we are in great need of.”

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To make a longer-lasting battery, it needs to be bigger, and bigger isn’t better when it comes to cell phones or electric cars — not to mention pacemakers.

Lithium ion batteries already have a less-than-stellar reputation: think exploding cell phones or fires on airplanes. Beyond these existing problems, when researchers attempt to shrink these batteries without compromising the performance, the results are even more unstable and prone to short-circuiting; engineers have not been able to move past these issues.

Researchers at Washington University in St. Louis have new insights into the cause — or causes — of these issues, paving the way for smaller, safer, more energy-dense batteries. The result of their work has recently been published online in the journal Joule.

Peng Bai, assistant professor in the School of Engineering & Applied Science, has identified three key current boundaries when it comes to these energy-dense lithium metal batteries. It turns out, engineers had been looking for one solution to what turns out to be three problems.

A lithium ion battery is made of three layers: one layer of low-voltage material (graphite) called the anode; one of high-voltage material (lithium cobalt oxide) called the cathode; and a layer of porous plastic which separates the two.

The separator is wetted by a liquid called an electrolyte. When the battery discharges, lithium ions empty out of the anode, passing through the liquid electrolyte, and move into the cathode. The process is reversed as the battery charges.

“With half of the lithium-ion-hosting electrode materials empty at all times,” Bai said, “you are wasting half of your space.”

Engineers have known that they could build a more energy-dense battery (a smaller battery with a similar output capabilities) by discarding some of the dead weight that comes with half of the host materials always being empty. They have been minimally successful by removing the graphite anode, then reducing the lithium ions with electrons during recharge, a process which forms a thin plating of lithium metal.

“The problem is that the lithium metal plating is not uniform,” Bai said. “It can grow ‘fingers.’ “

Researchers have referred to these fingers as “dendrites.” As they spread from the lithium metal plating, they can penetrate the separator in the battery, leading to a short circuit.

But not all “fingers” are the same. “If you call them all dendrites, you’re looking for one solution to solve actually three problems, which is impossible,” Bai said. “That’s why after so many years this problem has never been solved.”

His team has identified three distinct types of fingers, or growth modes, in these lithium metal anodes. They also outline at which current each growth mode appears.

“If you use very high current, it builds at the tip to produce a treelike structure,” Bai said. Those are “true dendrites.”

Below the lower limit you have whiskers growing from the root.

And within those two limits there exists the dynamic transition from whiskers to dendrites, which Bai calls “surface growth.”

These growths are all related to the competing reactions in the region between the liquid electrolyte and the metal deposits.

The study found that a nanoporous ceramic separator can block whiskers up to a certain current density, after which surface growths can slowly penetrate the separator. With a strong enough current, “true dendrites” form, which can easily and very quickly penetrate the separator to short the battery.

At this point, Bai said, “our unique transparent cell revealed that the voltage of battery could look quite normal, even though the separator has been penetrated by a lithium metal filament. Without seeing what is happening inside, you could be easily fooled by the seemingly reasonable voltage, but, really, your battery has already failed.”

In order to build a safe, efficient, reliable battery with a lithium metal anode, the three growth modes need to be controlled by three different methods.

This will be a challenge considering consumers want batteries that can store more energy, and at the same time want them to be charged more quickly. The combination of these two inevitably yields a higher and higher charging current, which may exceed one of the critical currents identified by Bai’s team.

And, batteries can degrade. When they do, the critical currents identified for the fresh battery no longer apply; the threshold becomes lower. At that point, given the same fast charge current, there’s a higher likelihood that the battery will short.

“Battery operation is highly dynamic, in a very wide range of currents. Yet its disposition varies dramatically along the cycle life” Bai said. “That is why this becomes necessary.”

Rice postdoctoral researcher and seismologist Jonathan Delph and Earth scientists Fenglin Niu and Alan Levander make a case for the incursion of fluid related to slippage deep inside the Cascadia margin off the Pacific Northwest’s coast.

Their paper, which appears in the American Geophysical Union journal Geophysical Research Letters, links fluids escaping from deep subduction to the frequent shakes that Delph said happen in relative slow motion when compared to the sudden, violent jolts occasionally felt by Southern Californians at the southern end of the west coast.

“These aren’t large, instantaneous events like a typical earthquake,” Delph said. “They’re seismically small, but there’s a lot of them and they are part of the slow-slip type of earthquake that can last for weeks instead of seconds.”

Delph’s paper is the first to show variations in the scale and extent of fluids that come from dehydrating minerals and how they relate to these low-velocity quakes. “We are finally at the point where we can address the incredible amount of research that’s been done in the Pacific Northwest and try to bring it all together,” he said. “The result is a better understanding of how the seismic velocity structure of the margin relates to other geologic and tectonic observations.”

The North American plate and Juan de Fuca plate, a small remnant of a much larger tectonic plate that used to subduct beneath North America, meet at the Cascadia subduction zone, which extends from the coast of northern California well into Canada. As the Juan de Fuca plate moves to the northeast, it sinks below the North American plate.

Delph said fluids released from minerals as they heat up at depths of 30 to 80 kilometers propagate upward along the boundary of the plates in the northern and southern portions of the margin, and get trapped in sediments that are subducting beneath the Cascadia margin.

“This underthrust sedimentary material is being stuck onto the bottom of the North American plate,” he said. “This can allow fluids to infiltrate. We don’t know why, exactly, but it correlates well with the spatial variations in tremor density we observe. We’re starting to understand the structure of the margin where these tremors are more prevalent.”

Delph’s research is based on extensive seismic records gathered over decades and housed at the National Science Foundation-backed IRIS seismic data repository, an institutional collaboration to make seismic data available to the public.

“We didn’t know these tremors existed until the early 2000s, when they were correlated with small changes in the direction of GPS stations at the surface,” he said. “They’re extremely difficult to spot. Basically, they don’t look like earthquakes. They look like periods of higher noise on seismometers.

“We needed high-accuracy GPS and seismometer measurements to see that these tremors accompany changes in GPS motion,” Delph said. “We know from GPS records that some parts of the Pacific Northwest coast change direction over a period of weeks. That correlates with high-noise ‘tremor’ signals we see in the seismometers. We call these slow-slip events because they slip for much longer than traditional earthquakes, at much slower speeds.”

He said the phenomenon isn’t present in all subduction zones. “This process is pretty constrained to what we call ‘hot subduction zones,’ where the subducting plate is relatively young and therefore warm,” Delph said. “This allows for minerals that carry water to dehydrate at shallower depths.

“In ‘colder’ subduction zones, like central Chile or the Tohoku region of Japan, we don’t see these tremors as much, and we think this is because minerals don’t release their water until they’re at greater depths,” he said. “The Cascadia subduction zone seems to behave quite differently than these colder subduction zones, which generate large earthquakes more frequently than Cascadia. This could be related in some way to these slow-slip earthquakes, which can release as much energy as a magnitude 7 earthquake over their duration. This is an ongoing area of research.”

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Now, as part of an international team of scientists, researchers at The University of Manchester have identified a new species of Archaeopteryx that is closer to modern birds in evolutionary terms.

Dr John Nudds, from the University’s School of Earth and Environmental Sciences, and the team have been re-examining one of the only 12 known specimens by carrying out the first ever synchrotron examination, a form of 3D X-ray analysis, of an Archaeopteryx.

Thanks to this new insight, the team says that this individual Archaeopteryx fossil, known as ‘specimen number eight’, is physically much closer to a modern bird than it is to a reptile. Therefore, it is evolutionary distinctive and different enough to be described as a new species — Archaeopteryx albersdoerferi.

The research, which is being published in journal Historical Biology, says that some of the differing skeletal characteristics of Archaeopteryx albersdoerferi include the fusion of cranial bones, different pectoral girdle (chest) and wing elements, and a reinforced configuration of carpals and metacarpals (hand) bones.

These characteristics are seen more in modern flying birds and are not found in the older Archaeopteryx lithographica species, which more resembles reptiles and dinosaurs.

Specimen number eight is the youngest of all the 12 known specimens by approximately half a million years. This age difference in comparison to the other specimens is a key factor in describing it as a new species.

Dr Nudds explains: “By digitally dissecting the fossil we found that this specimen differed from all of the others. It possessed skeletal adaptations which would have resulted in much more efficient flight. In a nutshell we have discovered what Archaeopteryx lithographica evolved into — i.e. a more advanced bird, better adapted to flying — and we have described this as a new species of Archaeopteryx.”

Archaeopteryx was first described as the ‘missing link’ between reptiles and birds in 1861 — and is now regarded as the link between dinosaurs and birds. Only 12 specimens have ever been found and all are from the late Jurassic of Bavaria, now Germany, dating back approximately 150 million years.

Lead author, Dr Martin Kundrát, from the University of Pavol Jozef Šafárik, Slovakia, said: “This is the first time that numerous bones and teeth of Archaeopteryx were viewed from all aspects including exposure of their inner structure. The use of synchrotron microtomography was the only way to study the specimen as it is heavily compressed with many fragmented bones partly or completely hidden in limestone.”

Dr Nudds added: “Whenever a missing link is discovered, this merely creates two further missing links — what came before, and what came after! What came before was discovered in 1996 with the feathered dinosaurs in China. Our new species is what came after. It confirms Archaeopteryx as the first bird, and not just one of a number of feathered theropod dinosaurs, which some authors have suggested recently. You could say that it puts Archaeopteryx back on its perch as the first bird!”

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