Jun 30, 2016

Shape-changing 'smart' material: Heat, light stimulate self-assembly

A smart new material reacts to light, can remember its shape as it folds and unfolds and can heal itself when damaged.
Washington State University researchers have developed a unique, multifunctional smart material that can change shape from heat or light and assemble and disassemble itself. They have filed a provisional patent on the work.

This is the first time researchers have been able to combine several smart abilities, including shape memory behavior, light-activated movement and self-healing behavior, into one material. They have published their work in ACS Applied Materials & Interfaces.

The work is led by Michael Kessler, professor and Berry Family director and in the WSU School of Mechanical and Materials Engineering (MME), and Yuzhan Li, MME staff scientist, in collaboration with Orlando Rios, a researcher at Oak Ridge National Laboratory.

Adding functional versatility

Smart materials that can react to external stimuli, like light or heat, have been an interesting novelty and look almost magical as they mysteriously fold and unfold themselves. They have a variety of potential applications, such as for actuators, drug delivery systems and self-assembling devices. For instance, smart materials could change shape to unfold a solar panel on a space satellite without need of a battery-powered mechanical device.

But smart materials haven't come into widespread use because they are difficult to make and often can only perform one function at a time. Researchers also have struggled to reprocess the material so its special properties can continually repeat themselves.

The WSU research team developed a material that allows multiple functions at once with potential to add more.

Fold and unfold, remember and heal

The team worked with a class of long-chain molecules, called liquid crystalline networks (LCNs), which provide order in one direction and give material unique properties. The researchers took advantage of the way the material changes in response to heat to induce a unique three-way shape shifting behavior. They added groups of atoms that react to polarized light and used dynamic chemical bonds to improve the material's reprocessing abilities.

"We knew these different technologies worked independently and tried to combine them in a way that would be compatible,'' said Kessler.

The resulting material reacts to light, can remember its shape as it folds and unfolds and can heal itself when damaged. For instance, a razor blade scratch in the material can be fixed by applying ultraviolet light. The material's movements can be preprogrammed and its properties tailored.

The Oak Ridge National Laboratory researchers used facilities at their Center for Nanophase Materials Sciences to study the mechanisms responsible for the material's unique abilities.

Read more at Science Daily

A 6,000 year old telescope without a lens: Prehistoric tombs enhanced astronomical viewing

a) Dolmen da Orca, a typical dolmenic structure in western Iberia; b) view of the passage and entrance while standing within the dolmens' chamber: the 'window of visibility'; c) Orca de Santo Tisco, a dolmen with a much smaller passage or corridor.
Astronomers are exploring what might be described as the first astronomical observing tool, potentially used by prehistoric humans 6,000 years ago. They suggest that the long, narrow entrance passages to ancient stone, or 'megalithic', tombs may have enhanced what early human cultures could see in the night sky, an effect that could have been interpreted as the ancestors granting special power to the initiated. The team present their study at the National Astronomy Meeting, being held this week in Nottingham.

The team's idea is to investigate how a simple aperture, for example an opening or doorway, affects the observation of slightly fainter stars. They focus this study on passage graves, which are a type of megalithic tomb composed of a chamber of large interlocking stones and a long narrow entrance. These spaces are thought to have been sacred, and the sites may have been used for rites of passage, where the initiate would spend the night inside the tomb, with no natural light apart from that shining down the narrow entrance lined with the remains of the tribe's ancestors.

These structures could therefore have been the first astronomical tools to support the watching of the skies, millennia before telescopes were invented. Kieran Simcox, a student at Nottingham Trent University, and leading the project, comments: "It is quite a surprise that no one has thoroughly investigated how for example the colour of the night sky impacts on what can be seen with the naked eye."

The project targets how the human eye, without the aid of any telescopic device, can see stars given sky brightness and colour. The team intend to apply these ideas to the case of passage graves, such as the 6,000 year old Seven-Stone Antas in central Portugal. Dr Fabio Silva, of the University of Wales Trinity Saint David, explains that, "the orientations of the tombs may be in alignment with Aldebaran, the brightest star in the constellation of Taurus. To accurately time the first appearance of this star in the season, it is vital to be able to detect stars during twilight."

The first sighting in the year of a star after its long absence from the night sky might have been used as a seasonal marker, and could indicate for example the start of a migration to summer grazing grounds. The timing of this could have been seen as secret knowledge or foresight, only obtained after a night spent in contact with the ancestors in the depths of a passage grave, since the star may not have been observable from outside. However, the team suggest it could actually have been the result of the ability of the human eye to spot stars in such twilight conditions, given the small entrance passages of the tombs.

Read more at Science Daily

It's not easy being green: What colors tell us about galaxy evolution

The green galaxy is caught in the act of transforming from blue to red as its gas supply runs out.
An international team of scientists, led from Durham's Institute for Computational Cosmology (ICC), used new computer modelling of the Universe to investigate the colours that galaxies have and what those colours might tell us about how galaxies evolve.

Using the state-of-the-art EAGLE simulations, the researchers modelled how both the ages of stars in galaxies and what those stars are made from translate into the colour of light that they produce.

The research team said its simulations showed that colours of galaxies can also help diagnose how they evolve.

While red and blue galaxies are relatively common, rare green galaxies are likely to be at an important stage in their evolution, when they are rapidly turning from blue -- when new stars and planets are being born -- to red as stars begin to burn themselves out.

The research funded by the Science and Technology Facilities Council (STFC) and the European Research Council (ERC) is being presented today (Thursday 30 June) at the Royal Astronomical Society's National Astronomy Meeting in Nottingham, UK.

Lead researcher James Trayford, PhD student in the ICC at Durham University, said: "Galaxies emit a healthy blue glow while new stars and planets are being born. However, if the formation of stars is halted galaxies turn red as stars begin to age and die.

"In the real Universe we see many blue and red galaxies, but these intermediate 'green' galaxies are more rare.

"This suggests that the few green galaxies we catch are likely to be at a critical stage in their evolution; rapidly turning from blue to red."

Because stars form from dense gas, a powerful process is needed to rapidly destroy their gas supply and cause such dramatic changes in colour, the research found.

James added: "In a recent study we followed simulated galaxies as they changed colour, and investigated what processes caused them to change.

"We typically find that smaller green galaxies are being violently tossed around by the gravitational pull of a massive neighbour, causing their gas supply to be stripped away.

"Meanwhile, bigger green galaxies may self-destruct as immense explosions triggered by super-massive black holes at their centres can blow dense gas away."

However, the research found that there was some hope for green galaxies as a lucky few might absorb a fresh supply of gas from their surroundings.

This can revive the formation of stars and planets, and restore galaxies to a healthy blue state.

James said: "By using simulations to study how galaxy colours change, we can speed up the process of galaxy evolution from the billions of years it takes in the real Universe to just a matter of days in a computer.

Read more at Science Daily

Hubble captures vivid auroras in Jupiter’s atmosphere

This image combines an image taken with Hubble Space Telescope in the optical (taken in spring 2014) and observat ions of its auroras in the ultraviolet, taken in 2016.
Astronomers are using the NASA/ESA Hubble Space Telescope to study auroras -- stunning light shows in a planet's atmosphere -- on the poles of the largest planet in the Solar System, Jupiter. This observation programme is supported by measurements made by NASA's Juno spacecraft, currently on its way to Jupiter.

Jupiter, the largest planet in the Solar System, is best known for its colourful storms, the most famous being the Great Red Spot. Now astronomers have focused on another beautiful feature of the planet, using the ultraviolet capabilities of the NASA/ESA Hubble Space Telescope.

The extraordinary vivid glows shown in the new observations are known as auroras. They are created when high energy particles enter a planet's atmosphere near its magnetic poles and collide with atoms of gas. As well as producing beautiful images, this programme aims to determine how various components of Jupiter's auroras respond to different conditions in the solar wind, a stream of charged particles ejected from the Sun.

This observation programme is perfectly timed as NASA's Juno spacecraft is currently in the solar wind near Jupiter and will enter the orbit of the planet in early July 2016. While Hubble is observing and measuring the auroras on Jupiter, Juno is measuring the properties of the solar wind itself; a perfect collaboration between a telescope and a space probe.

"These auroras are very dramatic and among the most active I have ever seen," says Jonathan Nichols from the University of Leicester, UK, and principal investigator of the study. "It almost seems as if Jupiter is throwing a firework party for the imminent arrival of Juno."

To highlight changes in the auroras Hubble is observing Jupiter daily for around one month. Using this series of images it is possible for scientists to create videos that demonstrate the movement of the vivid auroras, which cover areas bigger than the Earth.

Not only are the auroras huge, they are also hundreds of times more energetic than auroras on Earth. And, unlike those on Earth, they never cease. Whilst on Earth the most intense auroras are caused by solar storms -- when charged particles rain down on the upper atmosphere, excite gases, and cause them to glow red, green and purple -- Jupiter has an additional source for its auroras.

The strong magnetic field of the gas giant grabs charged particles from its surroundings. This includes not only the charged particles within the solar wind but also the particles thrown into space by its orbiting moon Io, known for its numerous and large volcanos.

Read more at Science Daily

Jun 29, 2016

It's not just a grunt: Pigs really do have something to say

The study indicated that pigs with more proactive personality types produced grunts at a higher rate than the more reactive animals.
The grunts made by pigs vary depending on the pig's personality and can convey important information about the welfare of this highly social species, new research has found.

Scientists specialising in animal behaviour and welfare devised an experiment to investigate the relationship between personality and the rate of grunting in pigs. They also examined the effect different quality living conditions had on these vocalisations.

Findings from the study, carried out by researchers from the University of Lincoln, UK, and Queens University Belfast, are published in the Royal Society journal Open Science.

The study involved 72 male and female juvenile pigs. Half were housed in spacious 'enriched' pens with straw bedding, while the other half were kept in more compact 'barren' pens with partially slatted concrete floors, which adhered to UK welfare requirements.

To get a measure of the pigs' personalities, the researchers conducted two tests: a social isolation test and a novel object test. Each pig spent three minutes in social isolation, and five minutes in a pen with a large white bucket or an orange traffic cone they had not previously encountered. Their behaviour, including vocalisations, were observed. These tests were repeated two weeks later, allowing the researchers to determine if the pigs' responses were repeatable -- the defining characteristic of personality (also known as 'coping style' in animals).

They also recorded the frequency of grunts they made by counting the number of grunts produced per minute of the test, and investigated the effect different quality environments had on the sounds made.

The study indicated that pigs with more proactive personality types produced grunts at a higher rate than the more reactive animals. The study also found that male pigs (but not females) kept in the lower-quality conditions made fewer grunts compared with those housed in the enriched environment, suggesting greater susceptibility among male pigs to environmental factors.

The results add to evidence that acoustic signalling indicates personality in pigs. This may have had far reaching consequences in shaping the evolution of social behaviours, the researchers believe. The findings also suggest personality needs to be kept in mind when using vocalisation as a measure of the animals' welfare status.

Principal investigator, Dr Lisa Collins, a specialist in animal health, behaviour and welfare epidemiology in the School of Life Sciences at the University of Lincoln, said: "The domestic pig is a highly social and vocal species which uses acoustic signals in a variety of ways; maintaining contact with other group members while foraging, parent-offspring communication, or to signal if they are distressed.

"The sounds they make convey a wide range of information such as the emotional, motivational and physiological state of the animal. For example, squeals are produced when pigs feel fear, and may be either alerting others to their situation or offering assurance. Grunts occur in all contexts, but are typical of foraging to let other members of the group know where they are."

Read more at Science Daily

Animals 'inherit' their social network from their mothers, study shows

Researchers at the University of Pennsylvania developed a simple mathematical model that describes how animal social networks arise. The model recapitulated important qualities of observed social networks of several species, including spotted hyenas.
Dolphins, lizards and hyenas may not be on Facebook or Twitter, but, as social species, their social networks influence every pivotal aspect of their lives: finding a mate, reproducing, becoming ill or surviving.

In a newly published study in the journal Nature Communications, two biologists from the University of Pennsylvania have developed a mathematical model of the way social networks arise in animal populations. Their model considers the likelihood that a newborn forms connections with its mother's connections or other individuals not connected to its mother, with the assumption that an individual is more likely to connect with those connected with its mother.

Though relatively simple, their model generated networks that faithfully recapitulated important properties of networks observed in field-collected data from four very different animal populations: spotted hyenas, sleep lizards, rock hyrax and bottlenose dolphins.

The work was conducted by Amiyaal Ilany, a postdoctoral researcher, and Erol Akçay, an assistant professor, both of Penn's Department of Biology in the School of Arts & Sciences.

"What we show," said Akçay, "is that we can fit this simple model to real-life networks and capture their degree distribution, or how connected everyone is, and, more strikingly, we can also capture the distribution of what's known as the clustering coefficient, which measures how cliquish the population is."

For as long as biologists have been studying animal populations, they've made observations about social relationships in the group. But it has only been in the last decade or so that social-network analysis has come to the fore in generating an understanding of the dynamics of these networks.

"There has been an explosion of studies in the last 10 years or more," Ilany said, "showing that social networks have implications for longevity or disease transmission or reproductive success. It's become quite clear that social network structure is important."

Yet these analyses, which have used field observations to construct a social network, have not provided researchers a more general picture of how networks emerge.

"What we saw as missing is some theory of how you actually get the social structure that we observe," Ilany said.

To address this gap on the theoretical side of network analysis, Akçay and Ilany envisioned a simple, straightforward process by which individual animals can either make or lose social connections.

"The model says, if someone enters into a network, they have two ways of making connections," Akçay explained. "Assuming the individual is a newborn, they will make a connection with their mother and their mother's connections, and they could also become connected to random individuals to whom their mother might not be connected."

Using only these two parameters, corresponding to the probabilities of each type of connection, and assuming a finite population in which individuals entered by being born and left by dying, they found that the model captured essential properties of animal social networks observed in the wild. This included a tendency for some individuals to be highly connected and others less so and a tendency to form clusters, or "cliques." This was true when the researchers ran data through the model from rock hyrax, the species Ilany studied for his Ph.D., as well as data on spotted hyenas, bottlenose dolphins and sleepy lizards.

"Alternative models that we considered," Akçay said, "like the theory that individuals connect based on shared traits or interests, captured the degree distribution but didn't generate enough clustering. There's something special about the idea that I'm more likely to connect with you if you're connected with someone I already know. That's what generates this cliquishness we see in the model."

While some researchers have postulated that social status might be genetically heritable, this work suggests that a newborn could "inherit" its mother's social status non-genetically, simply by copying its mother's social network. Akçay and Ilany term this "social inheritance."

"We show that, if I just copy my mother, I become very similar to her socially," Ilany said. "It's still possible that there is genetic inheritance of social traits, but part of that inheritance can be explained by this simple social process."

The biologists noted that the behavioral processes that lead to the formation of connections may look very different in different species. In many primates, for example, individuals of a group take a special interest in newborns, even offering the mother grooming in exchange for "baby time." In other species, the acquisition of social connections might be more passive, with young individuals simply developing relationships with their mother's connections because they remain in close proximity to their mother as they grow.

As a result, the model may be stronger for mammals, which are physically dependent on their mother, than for other species such as insects. The work also has the potential to inform how human social networks formed historically.

"If you want to think about how humans evolved to be this super cooperative species," Akçay said, "the fine-scale social structure of a group has implications for how that process might have worked."

Read more at Science Daily

Humans artificially drive evolution of new species

The London Underground Mosquito (Culex pipiens molestus) has been found in underground systems around the world. It is believed to have evolved from the common house mosquito through a subterranean population.
Species across the world are rapidly going extinct due to human activities, but humans are also causing rapid evolution and the emergence of new species. A new study published today summarises the causes of humanmade speciation, and discusses why newly evolved species cannot simply replace extinct wild species. The study was led by the Center for Macroecology, Evolution and Climate at the University of Copenhagen.

A growing number of examples show that humans not only contribute to the extinction of species but also drive evolution, and in some cases the emergence of entirely new species. This can take place through mechanisms such as accidental introductions, domestication of animals and crops, unnatural selection due to hunting, or the emergence of novel ecosystems such as the urban environment.

Although tempting to conclude that human activities thus benefit as well as deplete global biodiversity, the authors stress that extinct wild species cannot simply be replaced with newly evolved ones, and that nature conservation remains just as urgent.

"The prospect of 'artificially' gaining novel species through human activities is unlikely to elicit the feeling that it can offset losses of 'natural' species. Indeed, many people might find the prospect of an artificially biodiverse world just as daunting as an artificially impoverished one" says lead author and Postdoc Joseph Bull from the Center for Macroecology, Evolution and Climate at the University of Copenhagen.

The study which was carried out in collaboration with the University of Queensland was published today in Proceedings of Royal Society B. It highlights numerous examples of how human activities influence species' evolution. For instance: as the common house mosquito adapted to the environment of the underground railway system in London, it established a subterranean population. Now named the 'London Underground mosquito', it can no longer interbreed with its above ground counterpart and is effectively thought to be a new species.

"We also see examples of domestication resulting in new species. According to a recent study, at least six of the world's 40 most important agricultural crops are considered entirely new" explains Joseph Bull.

Furthermore, unnatural selection due to hunting can lead to new traits emerging in animals, which can eventually lead to new species, and deliberate or accidental relocation of species can lead to hybridization with other species. Due to the latter, more new plant species in Europe have appeared than are documented to have gone extinct over the last three centuries.

Although it is not possible to quantify exactly how many speciation events have been caused through human activities, the impact is potentially considerable, the study states.

"In this context, 'number of species' becomes a deeply unsatisfactory measure of conservation trends, because it does not reflect many important aspects of biodiversity. Achieving a neutral net outcome for species numbers cannot be considered acceptable if weighing wild fauna against relatively homogenous domesticated species. However, considering speciation alongside extinction may well prove important in developing a better understanding of our impact upon global biodiversity. We call for a discussion about what we, as a society, actually want to conserve about nature" says Associate Professor Martine Maron from the University of Queensland.

Read more at Science Daily

How water droplets freeze: The physics of ice and snow

Freezing water is a central issue for climate, geology and life. On earth, ice and snow cover 10 percent of the land and up to half of the northern hemisphere in winter. Polar ice caps reflect up to 90 percent of the sun's incoming radiation. But how water droplets freeze, whether from within or from the surface, has been a topic of much controversy over past decade among chemists and physicists.

A team of researchers at Beijing Institute of Technology and Zhejiang University in China propose another question, "Where in the droplet does the crystallization of water or liquid silicon begin?" The team explains their findings this week in The Journal of Chemical Physics, from AIP Publishing. This is an interesting problem and one that is crucial to understanding the crystallization mechanism of nanoscale tetrahedral liquid drops like water and silicon.

In their work, they used computer simulation, to find that the ripple-like density waves are markedly excited before crystallization of liquid silicon drops and films due to the volume expansion in a confined environment. The ripple-like density fluctuations create waves capable of promoting nucleation, eventually resulting in a ripple-like distribution of nucleation probability in drops and films. These results suggest that the freezing of nanoscale water or silicon liquid drops is initiated at a number of different distances from the center of the droplet, providing new insights on a long-standing dispute in the field of material and chemical physics.

The research team employed a molecular dynamics simulation to investigate the freezing of nanoscale silicon drops and films, a method widely used for the investigations of microscopic thermodynamic and dynamic process. In computer simulations of crystallization events, the short simulation time makes it difficult to observe. To address this issue some special simulation methods, namely, the rare event sampling algorithms, were proposed. But these methods inevitably drop some high probability regions of nucleation in the trajectory sampling starting from a single configuration, so the team employed brute-force simulation and sampled massive and independent crystallization processes. "Although the method is 'brute,' it can faithfully represent the distribution of nuclei," explained Yongjun Lü, a physicist at Beijing Institute of Technology and Zhejiang University. "This is why we were able to observe the ripple-like distribution of nucleation probability while it is absent in other studies."

A challenge for the team was the great calculation costs. To achieve the credible probability distributions of nucleation in drops and films requires massive statistical sampling, requiring more than 6 months of CPU time.

The implications of this research are far-reaching. "We can extend the present results to all the tetrahedral liquids including water due to their similarity in molecular structure," Lü said. "It suggests that the surface environment does not play a decisive role in the formation of ice and snow as expected. The density fluctuations inside drops result in that the possible freezing regions cover the middle and the surface regions, depending on the drop size. The freezing from the surface or from within may be random."

Read more at Science Daily

Jun 28, 2016

Previously unknown global ecological disaster discovered

Approximately 500,000 years after the major natural disaster at the boundary between the Permian and the Triassic another event altered the vegetation fundamentally and for longer.
There have been several mass extinctions in the history of Earth with adverse consequences for the environment. Researchers from the University of Zurich have now uncovered another disaster that took place around 250 million years ago and completely changed the prevalent vegetation during the Lower Triassic.

There have been several mass extinctions in the history of Earth. One of the largest known disasters occurred around 252 million years ago at the boundary between the Permian and the Triassic. Almost all sea-dwelling species and two thirds of all reptiles and amphibians died out. Although there were also brief declines in diversity in the plant world, they recovered in the space of a few thousand years, which meant that similar conditions to before prevailed again.

Change in flora within a millennia

Researchers from the Institute and Museum of Paleontology at the University of Zurich have now discovered another previously unknown ecological crisis on a similar scale in the Lower Triassic. The team headed by Peter A. Hochuli and Hugo Bucher revealed that another event altered the vegetation fundamentally and for longer approximately 500,000 years after the major natural disaster at the boundary between the Permian and the Triassic.

The scientists studied sediments towering over 400 meters high from North-Eastern Greenland. Carbon isotope curves suggest that the prevalent seed ferns and conifers were replaced by spore plants in the space of a few millennia. To this day, certain spore plants like ferns are still famous for their ability to survive hostile conditions better than more highly developed plants.

Catastrophic ecological upheaval changes plant world

Until now, it was assumed that the environment gradually recovered during the Lower Triassic 252.4 to 247.8 million years ago. "The drastic, simultaneous changes in flora and the composition of the carbon isotopes indicate that the actual upheaval in the vegetation didn't take place until the Lower Triassic, i.e. around 500,000 years later than previously assumed," explains Hochuli.

The researchers didn't just observe the mass death of vegetation in Greenland; they already discovered the first indications of this floral shift a few years ago in sediment samples from Pakistan. Moreover, the latest datings of volcanic ash by Australian scientists show that the most significant change in the plant world did not happen until a few millennia after the Permian/Triassic boundary. During this period, the indigenous glossopteris seed plant group died out, an event that had previously been dated back to the Permian. Thanks to these findings, the sediment sequences of the supercontinent Gondwana in the southern hemisphere now need to be reinterpreted.

Read more at Science Daily

Weird Dark Moon Orbiting Dwarf Planet Makemake

After scouring through Hubble images of one of the most extreme worlds in the badlands of our outer solar system, a small and very, very dark moon has been discovered.

Makemake orbits the sun at an average distance of around 45 AU (astronomical units, where 1 AU is the average distance the Earth orbits the sun), so to zoom in on its location, the most powerful space telescope was needed to understand more of its nature. Hubble uncovered the landmark find in April, but before then, there was little evidence that Makemake possessed its own natural satellite and if it didn't have a moon, astronomers wanted to understand why. But that changed when observations by Hubble's Wide Field Camera 3 were analyzed and an extremely dark moon emerged as a faint point of light very close to the dwarf planet. The Kuiper belt object (KBO) was discovered in 2005 by a Caltech team led by astronomer Mike Brown.

"Makemake's moon proves that there are still wild things waiting to be discovered, even in places people have already looked," said astronomer Alex Parker, of the Southwest Research Institute (SwRI), who is credited with the discovery of the moon. "Makemake's moon -- nicknamed MK2 -- is very dark, 1,300 times fainter than the dwarf planet."

Parker's research has now been published in the June 27 issue of Astrophysical Journal Letters.

The moon over Makemake is faint but visible on the left, but completely lost in the glare of the parent dwarf on the right.
It turns out that MK2 has an almost perfectly edge-on orbit from our perspective, ensuring that, for most of its short orbit that it remained hidden in the bright glare of Makemake's bright reflected light. Understanding why MK2 is so dark is a puzzle and will undoubtedly be the focus of future research.

Known to posses a shell of methane ice, Makemake measures around 870 miles across. It is estimated that MK2 is approximately 100 miles wide.

"With a moon, we can calculate Makemake's mass and density," said Parker. "We can contrast the orbits and properties of the parent dwarf and its moon, to understand the origin and history of the system. We can compare Makemake and its moon to other systems, and broaden our understanding of the processes that shaped the evolution of our solar system."

Read more at Discovery News