A family of comets reopens the debate about the origin of Earth's water

Illustration of comet over Earth.

Where did the Earth's water come from? Although comets, with their icy nuclei, seem like ideal candidates, analyses have so far shown that their water differs from that in our oceans.

Now, however, an international team, bringing together CNRS researchers at the Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (Paris Observatory -- PSL/CNRS/ Sorbonne University/University of Cergy-Pontoise) and the Laboratory of Space Studies and Instrumentation in Astrophysics (Paris Observatory -- PSL/CNRS/Sorbonne University/University of Paris), has found that one family of comets, the hyperactive comets, contains water similar to terrestrial water. The study, published in the journal Astronomy & Astrophysics on May 20, 2019, is based in particular on measurements of comet 46P/Wirtanen carried out by SOFIA, NASA's Stratospheric Observatory for Infrared Astronomy.

According to the standard theory, the Earth is thought to have formed from the collision of small celestial bodies known as planetesimals. Since such bodies were poor in water, Earth's water must have been delivered either by a larger planetesimal or by a shower of smaller objects such as asteroids or comets.

To trace the source of terrestrial water, researchers study isotopic ratios (1), and in particular the ratio in water of deuterium to hydrogen, known as the D/H ratio (deuterium is a heavier form of hydrogen). As a comet approaches the Sun, its ice sublimes (2), forming an atmosphere of water vapour that can be analysed remotely. However, the D/H ratios of comets measured so far have generally been twice to three times that of ocean water, which implies that comets only delivered around 10% of the Earth's water.

When comet 46P/Wirtanen approached the Earth in December 2018 it was analysed using the SOFIA airborne observatory, carried aboard a Boeing aircraft. This was the third comet found to exhibit the same D/H ratio as terrestrial water. Like the two previous comets, it belongs to the category of hyperactive comets which, as they approach the Sun, release more water than the surface area of their nucleus should allow. The excess is produced by ice-rich particles present in their atmosphere.

Intrigued, the researchers determined the active fraction (i.e. the fraction of the nucleus surface area required to produce the amount of water present in their atmosphere) of all comets with a known D/H ratio. They found that there was an inverse correlation between the active fraction and the D/H ratio of the water vapour: the more a comet tends towards hyperactivity (i.e. an active fraction exceeding 1), the more its D/H ratio decreases and approaches that of the Earth.

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Study predicts shift to smaller animals over next century

The white-browed sparrow-weaver is one of the 'winners'.

Researchers at the University of Southampton have forecast a worldwide move towards smaller birds and mammals over the next 100 years.

In the future, small, fast-lived, highly-fertile, insect-eating animals, which can thrive in a wide-variety of habitats, will predominate. These 'winners' include rodents, such as dwarf gerbil -- and songbirds, such as the white-browed sparrow-weaver. Less adaptable, slow-lived species, requiring specialist environmental conditions, will likely fall victim of extinction. These 'losers' include the tawny eagle and black rhinoceros.

The researchers predict the average (median) body mass of mammals specifically will collectively reduce by 25 per cent over the next century. This decline represents a large, accelerated change when compared with the 14 per cent body size reduction observed in species from 130,000 years ago (the last interglacial period) until today.

Findings are published in detail in the journal Nature Communications.

Rob Cooke is lead author on this work and a postgraduate researcher at the University of Southampton. He comments: "By far the biggest threat to birds and mammals is humankind -- with habitats being destroyed due to our impact on the planet, such as deforestation, hunting, intensive farming, urbanisation and the effects of global warming.

"The substantial 'downsizing' of species which we forecast could incur further negative impacts for the long-term sustainability of ecology and evolution. This downsizing may be happening due to the effects of ecological change but, ironically, with the loss of species which perform unique functions within our global ecosystem, it could also end up as a driver of change too."

The research team focussed on 15,484 living land mammals and birds and considered five characteristics that relate to the role of each species in nature: body mass, litter/clutch size, breadth of habitat, diet and length of time between generations. In addition, the researchers used the International Union for Conservation of Nature (IUCN) Red List of Threatened Species to determine which animals are most likely to become extinct in the next century. They used modern statistical tools to combine all this data to make their projections and evaluate the loss of biodiversity.

Felix Eigenbrod, professor at the University of Southampton, says: "We have demonstrated that the projected loss of mammals and birds will not be ecologically random -- rather a selective process where certain creatures will be filtered out, depending on their traits and vulnerability to ecological change."

Amanda Bates, Research Chair at Memorial University in Canada, says: "Extinctions were previously viewed as tragic, deterministic inevitabilities, but they can also be seen as opportunities for targeted conservation actions. As long as a species that is projected to become extinct persists, there is time for conservation action and we hope research such as ours can help guide this."

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Oldest meteorite collection on Earth found in one of the driest places

Meteor illustration.

Earth is bombarded every year by rocky debris, but the rate of incoming meteorites can change over time. Finding enough meteorites scattered on the planet's surface can be challenging, especially if you are interested in reconstructing how frequently they land. Now, researchers have uncovered a wealth of well-preserved meteorites that allowed them to reconstruct the rate of falling meteorites over the past two million years.

"Our purpose in this work was to see how the meteorite flux to Earth changed over large timescales -- millions of years, consistent with astronomical phenomena," says Alexis Drouard, Aix-Marseille Université, lead author of the new paper in Geology.

To recover a meteorite record for millions of years, the researchers headed to the Atacama Desert. Drouard says they needed a study site that would preserve a wide range of terrestrial ages where the meteorites could persist over long time scales.

While Antarctica and hot deserts both host a large percentage of meteorites on Earth (about 64% and 30%, respectively), Drouard says, "Meteorites found in hot deserts or Antarctica are rarely older than half a million years." He adds that meteorites naturally disappear because of weathering processes (e.g., erosion by wind), but because these locations themselves are young, the meteorites found on the surface are also young.

"The Atacama Desert in Chile, is very old ([over] 10 million years)," says Drouard. "It also hosts the densest collection of meteorites in the world."

The team collected 388 meteorites and focused on 54 stony samples from the El Médano area in the Atacama Desert. Using cosmogenic age dating, they found that the mean age was 710,000 years old. In addition, 30% of the samples were older than one million years, and two samples were older than two million. All 54 meteorites were ordinary chondrites, or stony meteorites that contain grainy minerals, but spanned three different types.

"We were expecting more 'young' meteorites than 'old' ones (as the old ones are lost to weathering)," says Drouard. "But it turned out that the age distribution is perfectly explained by a constant accumulation of meteorites for millions years." The authors note that this is the oldest meteorite collection on Earth's surface.

Drouard says this terrestrial crop of meteorites in the Atacama can foster more research on studying meteorite fluxes over large time scales. "We found that the meteorite flux seems to have remained constant over this [two-million-year] period in numbers (222 meteorites larger than 10 g per squared kilometer per million year), but not in composition," he says. Drouard adds that the team plans to expand their work, measuring more samples and narrowing in on how much time the meteorites spent in space. "This will tell us about the journey of these meteorites from their parent body to Earth's surface."

From Science Daily

Geometry of an electron determined for the first time

Quantum computing concept.

Physicists at the University of Basel are able to show for the first time how a single electron looks in an artificial atom. A newly developed method enables them to show the probability of an electron being present in a space. This allows improved control of electron spins, which could serve as the smallest information unit in a future quantum computer. The experiments were published in Physical Review Letters and the related theory in Physical Review B.

The spin of an electron is a promising candidate for use as the smallest information unit (qubit) of a quantum computer. Controlling and switching this spin or coupling it with other spins is a challenge on which numerous research groups worldwide are working. The stability of a single spin and the entanglement of various spins depends, among other things, on the geometry of the electrons -- which previously had been impossible to determine experimentally.

Only possible in artificial atoms

Scientists in the teams headed by professors Dominik Zumbühl and Daniel Loss from the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have now developed a method by which they can spatially determine the geometry of electrons in quantum dots.

A quantum dot is a potential trap which allows to confine free electrons in an area which is about 1000 times larger than a natural atom. Because the trapped electrons behave similar to electrons bound to an atom, quantum dots are also known as "artificial atoms."

The electron is held in the quantum dot by electric fields. However, it moves within the space and, with different probabilities corresponding to a wave function, remains in certain locations within its confinement.

Charge distribution sheds light

The scientists use spectroscopic measurements to determine the energy levels in the quantum dot and study the behavior of these levels in magnetic fields of varying strength and orientation. Based on their theoretical model, it is possible to determine the electron's probability density and thus its wave function with a precision on the sub-nanometer scale.

"To put it simply, we can use this method to show what an electron looks like for the first time," explains Loss.

Better understanding and optimization

The researchers, who work closely with colleagues in Japan, Slovakia and the US, thus gain a better understanding of the correlation between the geometry of electrons and the electron spin, which should be stable for as long as possible and quickly switchable for use as a qubit.

"We are able to not only map the shape and orientation of the electron, but also control the wave function according to the configuration of the applied electric fields. This gives us the opportunity to optimize control of the spins in a very targeted manner," says Zumbühl.

The spatial orientation of the electrons also plays a role in the entanglement of several spins. Similarly to the binding of two atoms to a molecule, the wave functions of two electrons must lie on one plane for successful entanglement.

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Meteor magnets in outer space: Finding elusive giant planets

Jupiter.

Astronomers believe planets like Jupiter shield us from space objects that would otherwise slam into Earth. Now they're closer to learning whether giant planets act as guardians of solar systems elsewhere in the galaxy.

A UCR-led team has discovered two Jupiter-sized planets about 150 light years away from Earth that could reveal whether life is likely on the smaller planets in other solar systems.

"We believe planets like Jupiter have profoundly impacted the progression of life on Earth. Without them, humans might not be here to have this conversation," said Stephen Kane, lead study author and UCR associate professor of planetary astrophysics. "Understanding how many other stars have planets like Jupiter could be very important for learning about the habitability of planets in those systems."

Along with liquid water oceans, Kane said astronomers believe such planets have the ability to act as 'slingshots,' pulling objects like meteors, comets, and asteroids out of their trajectories en route to impact with small, rocky planets.

Many larger planets have been found close to their stars. However, those aren't as useful for learning about the architecture of our own solar system, where the giant planets including Saturn, Uranus and Neptune are all farther from the sun. Big planets far from their stars have, until now, been harder to find.

A study recently accepted for publication in the Astronomical Journal details how Kane's team found success in a novel approach combining traditional detection methods with the latest technologies.

One popular method of searching for exoplanets -- planets in other solar systems -- involves monitoring stars for "wobble," in which a star moves toward and away from Earth. The wobble is likely caused by the gravitational pull a nearby planet is exerting on it. When a star wobbles, it's a clue there may be an exoplanet nearby.

When the planet is far from its star, the gravitational pull is weaker, making the wobble smaller and harder to detect. The other problem with using the wobble detection method, Kane said, is that it just takes a long time. Earth only takes a year to orbit the sun. Jupiter takes 12, Saturn takes 30, and Neptune takes an astonishing 164 years.

The larger exoplanets also take many years to circle their stars, which means observing a complete orbit could engulf an astronomer's entire career. To accelerate the process, Kane and his team combined the wobble method with direct imaging. This way, if the team thought a planet might be causing wobble, they could confirm it by sight.

Obtaining a direct image of a planet quadrillions of miles away is no simple task. It requires the largest possible telescope, one that is at least 32 feet long and highly sensitive. Even from this distance, the light of the stars can overexpose the image, obscuring the target planets.

The team overcame this challenge by learning to recognize and eliminate the patterns in their images created by starlight. Removing the starlight allowed Kane's team to see what remained.

"Direct imaging has come a long way both in terms of understanding the patterns we find, and in terms of the instruments used to create the images, which are much higher resolution than they've ever been," Kane said. "You see this every time a new smartphone is released -- the camera detectors are always being improved and that's true in astronomy as well."

In this project, the team applied the combination of wobble and imaging method to 20 stars. In addition to the two being orbited by giant Jupiter-like planets that had not been previously discovered, the team also detected a third, previously observed star with a giant planet in its system.

Going forward, the team will continue to monitor 10 of the stars where planetary companions could not be ruled out. In addition, Kane is planning a new project to measure how long it takes these exoplanets to complete rotations toward and away from their stars, which cannot currently be measured.

Kane's team is international, with members at the Australian Astronomical Observatory, University of Southern Queensland, University of New South Wales and Macquarie University in Australia, as well as at the University of Hertfordshire in the United Kingdom. They are also spread across the U.S. at the National Optical Astronomy Observatory in Tucson, AZ, Southern Connecticut State University, NASA Ames Research Center and Stanford University in California and the Carnegie Institution of Washington in D.C.

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Exotic matter uncovered in the sun's atmosphere

Solar flare illustration.

Scientists from Ireland and France have announced a major new finding about how matter behaves in the extreme conditions of the Sun's atmosphere.

The scientists used large radio telescopes and ultraviolet cameras on a NASA spacecraft to better understand the exotic but poorly understood "fourth state of matter." Known as plasma, this matter could hold the key to developing safe, clean and efficient nuclear energy generators on Earth. The scientists published their findings in the leading international journal Nature Communications.

Most of the matter we encounter in our everyday lives comes in the form of solid, liquid or gas, but the majority of the Universe is composed of plasma -- a highly unstable and electrically charged fluid. The Sun is also made up of this plasma.

Despite being the most common form of matter in the Universe plasma remains a mystery, mainly due to its scarcity in natural conditions on Earth, which makes it difficult to study. Special laboratories on Earth recreate the extreme conditions of space for this purpose, but the Sun represents an all-natural laboratory to study how plasma behaves in conditions that are often too extreme for the manually constructed Earth-based laboratories.

Postdoctoral Researcher at Trinity College Dublin and the Dublin Institute of Advanced Studies (DIAS), Dr Eoin Carley, led the international collaboration. He said: "The solar atmosphere is a hotbed of extreme activity, with plasma temperatures in excess of 1 million degrees Celsius and particles that travel close to light-speed. The light-speed particles shine bright at radio wavelengths, so we're able to monitor exactly how plasmas behave with large radio telescopes."

"We worked closely with scientists at the Paris Observatory and performed observations of the Sun with a large radio telescope located in Nançay in central France. We combined the radio observations with ultraviolet cameras on NASA's space-based Solar Dynamics Observatory spacecraft to show that plasma on the sun can often emit radio light that pulses like a light-house. We have known about this activity for decades, but our use of space and ground-based equipment allowed us to image the radio pulses for the first time and see exactly how plasmas become unstable in the solar atmosphere."

Studying the behaviour of plasmas on the Sun allows for a comparison of how they behave on Earth, where much effort is now under way to build magnetic confinement fusion reactors. These are nuclear energy generators that are much safer, cleaner and more efficient than their fission reactor cousins that we currently use for energy today.

Professor at DIAS and collaborator on the project, Peter Gallagher, said: "Nuclear fusion is a different type of nuclear energy generation that fuses plasma atoms together, as opposed to breaking them apart like fission does. Fusion is more stable and safer, and it doesn't require highly radioactive fuel; in fact, much of the waste material from fusion is inert helium."

"The only problem is that nuclear fusion plasmas are highly unstable. As soon as the plasma starts generating energy, some natural process switches off the reaction. While this switch-off behaviour is like an inherent safety switch -- fusion reactors cannot form runaway reactions -- it also means the plasma is difficult to maintain in a stable state for energy generation. By studying how plasmas become unstable on the Sun, we can learn about how to control them on Earth."

The success of this research was made possible by the close ties between researchers at Trinity, DIAS, and their French collaborators.

Dr Nicole Vilmer, lead collaborator on the project in Paris, said: "The Paris Observatory has a long history of making radio observations of the Sun, dating back to the 1950s. By teaming up with other radio astronomy groups around Europe we are able to make groundbreaking discoveries such as this one and continue the success we have in solar radio astronomy in France. It also further strengthens scientific collaboration between France and Ireland, which I hope continues in the future."

Dr Carley previously worked at the Paris Observatory, funded by a fellowship awarded by the Irish Research Council and the European Commission. He continues to work closely with his French colleagues today, and hopes to soon study the same phenomena using both French instruments and newly built, state-of-the-art equipment in Ireland.

Read more at Science Daily

How to enhance or suppress memories

Erasing memories concept.

What if scientists could manipulate your brain so that a traumatic memory lost its emotional power over your psyche? Steve Ramirez, a Boston University neuroscientist fascinated by memory, believes that a small structure in the brain could hold the keys to future therapeutic techniques for treating depression, anxiety, and PTSD, someday allowing clinicians to enhance positive memories or suppress negative ones.

Inside our brains, a cashew-shaped structure called the hippocampus stores the sensory and emotional information that makes up memories, whether they be positive or negative ones. No two memories are exactly alike, and likewise, each memory we have is stored inside a unique combination of brain cells that contain all the environmental and emotional information associated with that memory. The hippocampus itself, although small, comprises many different subregions all working in tandem to recall the elements of a specific memory.

Now, in a new paper in Current Biology, Ramirez and a team of collaborators have shown just how pliable memory is if you know which regions of the hippocampus to stimulate -- which could someday enable personalized treatment for people haunted by particularly troubling memories.

"Many psychiatric disorders, especially PTSD, are based on the idea that after there's a really traumatic experience, the person isn't able to move on because they recall their fear over and over again," says Briana Chen, first author of the paper, who is currently a graduate researcher studying depression at Columbia University.

In their study, Chen and Ramirez, the paper's senior author, show how traumatic memories -- such as those at the root of disorders like PTSD -- can become so emotionally loaded. By artificially activating memory cells in the bottom part of the brain's hippocampus, negative memories can become even more debilitating. In contrast, stimulating memory cells in the top part of the hippocampus can strip bad memories of their emotional oomph, making them less traumatic to remember.

Well, at least if you're a mouse.

Using a technique called optogenetics, Chen and Ramirez mapped out which cells in the hippocampus were being activated when male mice made new memories of positive, neutral, and negative experiences. A positive experience, for example, could be exposure to a female mouse. In contrast, a negative experience could be receiving a startling but mild electrical zap to the feet. Then, identifying which cells were part of the memory-making process (which they did with the help of a glowing green protein designed to literally light up when cells are activated), they were able to artificially trigger those specific memories again later, using laser light to activate the memory cells.

Their studies reveal just how different the roles of the top and bottom parts of the hippocampus are. Activating the top of the hippocampus seems to function like effective exposure therapy, deadening the trauma of reliving bad memories. But activating the bottom part of the hippocampus can impart lasting fear and anxiety-related behavioral changes, hinting that this part of the brain could be overactive when memories become so emotionally charged that they are debilitating.

That distinction, Ramirez says, is critical. He says that it suggests suppressing overactivity in the bottom part of the hippocampus could potentially be used to treat PTSD and anxiety disorders. It could also be the key to enhancing cognitive skills, "like Limitless," he says, referencing the 2011 film starring Bradley Cooper in which the main character takes special pills that drastically improve his memory and brain function.

"The field of memory manipulation is still young.... It sounds like sci-fi but this study is a sneak preview of what's to come in terms of our abilities to artificially enhance or suppress memories," says Ramirez, a BU College of Arts & Sciences assistant professor of psychological and brain sciences. Although the study got its start while Chen and Ramirez were both doing research at Massachusetts Institute of Technology, its data has been the backbone of the first paper to come out of the new laboratory group that Ramirez established at BU in 2017.

"We're a long way from being able to do this in humans, but the proof of concept is here," Chen says. "As Steve likes to say, 'never say never.' Nothing is impossible."

"This is the first step in teasing apart what these [brain] regions do to these really emotional memories.... The first step toward translating this to people, which is the holy grail," says memory researcher Sheena Josselyn, a University of Toronto neuroscientist who was not involved in this study. "[Steve's] group is really unique in trying to see how the brain stores memories with the goal being to help people... they're not just playing around but doing it for a purpose."

Although mouse brains and human brains are very different, Ramirez, who is also a member of the BU Center for Systems Neuroscience and the Center for Memory and Brain, says that learning how these fundamental principles play out in mice is helping his team map out a blueprint of how memory works in people. Being able to activate specific memories on demand, as well as targeted areas of the brain involved in memory, allows the researchers to see exactly what side effects come along with different areas of the brain being overstimulated.

"Let's use what we're learning in mice to make predictions about how memory functions in humans," he says. "If we can create a two-way street to compare how memory works in mice and in humans, we can then ask specific questions [in mice] about how and why memories can have positive or negative effects on psychological health."

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Neptune's moon Triton fosters rare icy union

Triton (left) orbiting Neptune.

Astronomers using the Gemini Observatory explore Neptune's largest moon Triton and observe, for the first time beyond the lab, an extraordinary union between carbon monoxide and nitrogen ices. The discovery offers insights into how this volatile mixture can transport material across the moon's surface via geysers, trigger seasonal atmospheric changes, and provide a context for conditions on other distant, icy worlds.

Extreme conditions can produce extreme results. In this case, it's the uncommon pairing of two common molecules -- carbon monoxide (CO) and nitrogen (N2) -- frozen as solid ices on Neptune's frigid moon Triton.

In the laboratory, an international team of scientists have pinpointed a very specific wavelength of infrared light absorbed when carbon monoxide and nitrogen molecules join together and vibrate in unison. Individually, carbon monoxide and nitrogen ices each absorb their own distinct wavelengths of infrared light, but the tandem vibration of an ice mixture absorbs at an additional, distinct wavelength identified in this study.

Using the 8-meter Gemini South Telescope in Chile, the team have recorded this same unique infrared signature on Triton. Key to the discovery was the high-resolution spectrograph called IGRINS (Immersion Grating Infrared Spectrometer) which was built as a collaboration between the University of Texas at Austin and the Korea Astronomy and Space Science Institute (KASI). Both the Gemini Observatory and IGRINS receive funding from the US National Science Foundation (NSF) and KASI.

"While the icy spectral fingerprint we uncovered was entirely reasonable, especially as this combination of ices can be created in the lab, pinpointing this specific wavelength of infrared light on another world is unprecedented," said Stephen C. Tegler of Northern Arizona University's Astrophysical Materials Laboratory who led the international study. The research results have been accepted for publication in the Astronomical Journal.

In the Earth's atmosphere carbon monoxide and nitrogen molecules exist as gases, not ices. In fact, molecular nitrogen is the dominant gas in the air we breath, and carbon monoxide is a rare contaminant that can be lethal.

On distant Triton, however, carbon monoxide and nitrogen freeze as solid ices. They can form their own independent ices, or can condense together in the icy mix detected in the Gemini data. This icy mix could be involved in Triton's iconic geysers first seen in Voyager 2 spacecraft images as dark, windblown streaks on the surface of the distant, icy moon.

The Voyager 2 spacecraft first captured Triton's geysers in action in the moon's south polar region back in 1989. Since then, theories have focused on an internal ocean as one possible source of erupted material. Or, the the geysers may erupt when the summertime Sun heats this thin layer of volatile ice on Triton's surface, potentially involving the mixed carbon monoxide and nitrogen ice revealed by the Gemini observation. That ice mixture could also migrate around the surface of Triton in response to seasonally varying patterns of sunlight.

"Despite Triton's distance from the Sun and the cold temperatures, the weak sunlight is enough to drive strong seasonal changes on Triton's surface and atmosphere," adds Henry Roe, Deputy Director of Gemini and a member of the research team. "This work demonstrates the power of combining laboratory studies with telescope observations to understand complex planetary processes in alien environments so different from what we encounter every day here on Earth."

Seasons progress slowly on Triton, as Neptune takes 165-Earth years to orbit the Sun. A season on Triton lasts a little over 40 years; Triton passed its southern summer solstice mark in 2000, leaving about 20 more years to conduct further research before its autumn begins.

Looking ahead, the researchers expect that these findings will shed light on the composition of ices and seasonal variations in the atmosphere on other distant worlds beyond Neptune. Astronomers have suspected that the mixing of carbon monoxide and nitrogen ice exists not only on Triton, but also on Pluto, where the New Horizons spacecraft found the two ices coexisting. This Gemini finding is the first direct spectroscopic evidence of these ices mixing and absorbing this type of light on either world.

Background

Triton orbits Neptune, the eighth planet from the Sun, some 2.7 billion miles from Earth -- at the cold outer fringe of our Solar System's major planet zone. It is the only large moon in the Solar System that orbits "backwards" or in the opposite direction to its planet's rotation. The peculiar motion suggests that Triton is a captured trans-Neptunian object from the Kuiper Belt -- a region of leftovers from the Solar System's early history, which is why it shares several features with the dwarf planet Pluto and Eris: size (roughly two-thirds that of our Moon), and surface temperatures that hover near absolute zero; so low that common compounds we know as gases on Earth freeze into ices.

Triton's atmosphere is also 70,000 times less dense than Earth's and is composed of nitrogen, methane, and carbon monoxide. Its surface appears to consist of two different terrains, one composed by the volatile ices and the second one formed by water and carbon dioxide ices.

Read more at Science Daily

Wild chimpanzees eat tortoises after cracking them open against tree trunks

Chimpanzee.

An international team of researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig and the University of Osnabrück, Germany, have observed wild chimpanzees in the Loango National Park, Gabon, eating tortoises. They describe the first observations of this potentially cultural behavior where chimpanzees hit tortoises against tree trunks until the tortoises' shells break open and then feed on the meat.

"We have known for decades that chimpanzees feed on meat from a variety of animal species, but until now the consumption of reptiles has not been observed," says Tobias Deschner, a primatologist at the Max Planck Institute for Evolutionary Anthropology. "What is particularly interesting is that they use a percussive technique that they normally employ to open hard-shelled fruits to gain access to meat of an animal that is almost inaccessible for any other predator."

The researchers studied the behaviour of chimpanzees of the newly habituated Rekambo community. They observed 38 prey events by ten different chimpanzees in the dry season, a period when other preferred food such as fruits is abundant. "Sometimes, younger animals or females were unable to crack open the tortoise on their own. They then regularly handed the tortoise over to a stronger male who cracked the tortoise's shell open and shared the meat with all other individuals present," says Simone Pika, first author of the study and a cognitive scientist at the University of Osnabrück.

Leftovers from dinner

There was one exceptional case in which an adult male, who was on his own, cracked a tortoise, ate half of it up while sitting in a tree and then tucked the rest of it in a tree fork. He climbed down, built his nest in a nearby tree and came back the next morning to retrieve the leftovers and continue to feast on them for breakfast. "This indicates that chimpanzees may plan for the future," says Pika. "The ability to plan for a future need, such as for instance hunger, has so far only been shown in non-human animals in experimental and/or captive settings. Many scholars still believe that future-oriented cognition is a uniquely human ability. Our findings thus suggest that even after decades of research, we have not yet grasped the full complexity of chimpanzees' intelligence and flexibility."

Deschner adds: "Wild chimpanzee behaviour has been studied now for more than 50 years and at more than ten long-term field sites all across tropical Africa. It is fascinating that we can still discover completely new facets of the behavioural repertoire of this species as soon as we start studying a new population."

The authors further emphasize the importance of non-human primate field observations to inform theories of hominin evolution. "As one of our closest living relatives, the study of chimpanzee behaviour is a window into our own history and evolution," says Pika. "To prevent this window from closing once and for all, we need to do whatever we can to secure the survival of these fascinating animals in their natural habitats across Africa," concludes Deschner.

From Science Daily

Chemistry of stars sheds new light on the Gaia Sausage

Milky Way.

Chemical traces in the atmospheres of stars are being used to uncover new information about a galaxy, known as the Gaia Sausage, which was involved in a major collision with the Milky Way billions of years ago.

Astrophysicists at the University of Birmingham in collaboration with colleagues at European institutions in Aarhus, Bologna and Trieste, have been studying evidence of the chemical composition of stars in this area of the Milky Way to try to pinpoint more accurately the age of the smaller galaxy.

The Gaia Sausage was identified last year by an international team using information from the European Space Agency's Gaia satellite. Its merger with the Milky Way, estimated to have occurred about 10 billion years ago, is thought to have contributed to the shape of the Milky Way that we recognise today.

Using only the information about the chemical traces of Gaia Sausage stars coming from the international APOGEE astronomical survey, the Birmingham researchers have pinpointed more precisely the age of the galaxy. By developing detailed models of the production, or nucleosynthesis of chemical elements by all kinds of stars and supernovae in the cosmos, they estimate the Sausage was formed around 12.5bn years ago -- 2.5bn years older than suggested by previous estimates.

"Elements interact with light in different ways and so by studying the properties of light from the stars, we can infer the chemical make-up of those stars," explains Fiorenzo Vincenzo, in the School of Physics and Astronomy at the University of Birmingham.

"All chemical elements heavier than helium are produced by stars via thermonuclear burning deep in the heart of the star. Different chemical elements are typically synthesised by different kinds of stars in the cosmos. The oxygen atoms that are so important for life processes, for example, were deposited in the interstellar medium by many successive generations of massive stars until they were incorporated by our planet about 4.5 billion years ago. We can measure the relative proportion of different chemical traces in the atmosphere of stars and use this measurement as a clock to determine their age."

Calculating the ages of stars accurately is a complex process and the technique used by the Birmingham team provides one piece of the puzzle. The next step will be to cross reference the chemical data with evidence from other techniques, such as studying the relative speeds at which stars move -- a project also underway at the University of Birmingham.

The merger between the two galaxies seems to have produced another effect, too. The team spotted a gap in the age distribution of stars in the Milky Way, that occurred at the same time as the merger, suggesting that the collision caused an interruption in star formation within the Milky Way.

"We speculate that the turbulence and heating caused by the merger of the Gaia Sausage with the Milky Way could have prevented the formation of stars at this time," says Dr Vincenzo. "However to confirm this we would need even more precise measurements of the ages of the stars in the Milky Way and in the smaller galaxy."

The study is published in Monthly Notices of the Royal Astronomical Society and is part of the Asterochronometry project, funded by the European Research Council and led by the University of Birmingham. The main aim of the project is to pinpoint precise and accurate stellar ages -- a keystone for understanding the assembly history of our galaxy.

Read more at Science Daily

Unexpected observation of ice at low temperature, high pressure questions water theory

Ice crystals.

Through an experiment designed to create a super-cold state of water, scientists at the Department of Energy's Oak Ridge National Laboratory used neutron scattering to discover a pathway to the unexpected formation of dense, crystalline phases of ice thought to exist beyond Earth's limits.

Observation of these particular crystalline ice phases, known as ice IX, ice XV and ice VIII, challenges accepted theories about super-cooled water and amorphous, or non-crystalline, ice. The researchers' findings, reported in the journal Nature, will also lead to better basic understanding of ice and its various phases found on other planets and moons and elsewhere in space.

"Hydrogen and oxygen are among the most abundant elements in the universe, and the simplest molecular compound of the two, H2O, is common," said Chris Tulk, ORNL neutron scattering scientist and lead author. "In fact, a popular theory suggests that most of Earth's water was brought here through collisions with icy comets."

On Earth, when water molecules reach zero degrees Celsius, they enter a lower energy state and settle onto a hexagonal crystalline lattice. This frozen form is denoted as ice Ih, the most common phase of water that can be found in household freezers or at skating rinks.

Ice IX, ice XV and ice VIII are three of at least 17 ice phases realized when molecules reorganize into a stable crystalline structure at varying super-low temperatures and very high pressures, conditions that don't occur naturally on Earth.

"As ice changes phases, it's similar to water going from a gas to a liquid to a solid except at low temperatures and high pressure -- the ice transforms between various different solid forms," Tulk said.

Each known ice phase is characterized by its unique crystal structure within its pressure-temperature range of stability, where the molecules reach equilibrium and the water molecules exhibit a regular three-dimensional pattern, and the structure becomes stable.

Initially, Tulk and colleagues at the National Research Council of Canada and from the University of California at Los Angeles were exploring the structural nature of amorphous ice -- a state of ice that forms with no ordered crystalline structure -- as it recrystallizes at even higher pressures.

To make amorphous ice, scientists freeze water into a high-pressure device that is cooled to minus 173 degrees Celsius and pressurized to approximately 10,000 atmospheres, or 147,000 pounds per square inch (car tires are inflated to about 32 pounds per square inch).

"This type of amorphous ice is thought to be related to liquid water, and understanding that link was the original purpose of this study," said Tulk.

At ORNL's Spallation Neutron Source, the team froze a three-millimeter sphere, or about half a drop, of deuterated water, which has an additional neutron in the hydrogen nucleus needed for neutron scattering analysis. Then, they programmed the Spallation Neutrons and Pressure, or SNAP, diffractometer to minus 173 degrees C. The instrument increased the pressure incrementally every couple of hours up to 411,000 pounds per square inch, or about 28,000 atmospheres while collecting neutron scattering data between each hike in pressure.

"Once we achieved amorphous ice, we planned to raise the temperature and pressure and observe the local molecular ordering as the amorphous ice 'melts' into a supercooled liquid and then recrystallizes," Tulk said. However, after analyzing the data, they were surprised to learn they had not created amorphous ice, but rather a sequence of crystalline transformations through four phases of ice with ever-increasing density: from ice Ih to ice IX to ice XV to ice XIII. There was no evidence of amorphous ice at all.

"I've made many of these samples always by compressing ice at low temperature," said co-author Dennis Klug from the National Research Council of Canada, the lab that originally discovered the pressure-induced amorphization of ice in 1984. "I've never previously seen this pressure-temperature path result in a series of crystalline forms like this."

"If the data from our experiment was true, it would mean that amorphous ice is not related to liquid water but is rather an interrupted transformation between two crystalline phases, a major departure from widely accepted theory," Klug added.

At first, the team thought their observation was the result of a contaminated sample.

Three more experiments with a fresh, carefully handled samples on SNAP produced identical results, reconfirming the structural transformation sequence with no formation of amorphous ice.

The key was the slow rate of pressure increase and collection of data at a lower pressure that allowed the ice structure to relax and become the stable ice IX form. Previous experiments quickly passed over the ice IX structure without relaxation, this resulted in the amorphous phase.

For 35 years, scientists have been researching the properties of super-cold water and looking for what's known as the second critical point, which is buried within the solid ice phases. But these results question its very existence. "The relationship between pressure-induced amorphous ice and water is now in doubt, and the second critical point may not even exist," Tulk said.

"The results of this paper will form the basis of the analysis of future studies of amorphous ice phases during upcoming experiments done at the SNS," he added.

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Artificial photosynthesis transforms carbon dioxide into liquefiable fuels

Carbon dioxide molecules illustration.

Chemists at the University of Illinois have successfully produced fuels using water, carbon dioxide and visible light through artificial photosynthesis. By converting carbon dioxide into more complex molecules like propane, green energy technology is now one step closer to using excess CO2 to store solar energy -- in the form of chemical bonds -- for use when the sun is not shining and in times of peak demand.

Plants use sunlight to drive chemical reactions between water and CO2 to create and store solar energy in the form of energy-dense glucose. In the new study, the researchers developed an artificial process that uses the same green light portion of the visible light spectrum used by plants during natural photosynthesis to convert CO2 and water into fuel, in conjunction with electron-rich gold nanoparticles that serve as a catalyst. The new findings are published in the journal Nature Communications.

"The goal here is to produce complex, liquefiable hydrocarbons from excess CO2 and other sustainable resources such as sunlight," said Prashant Jain, a chemistry professor and co-author of the study. "Liquid fuels are ideal because they are easier, safer and more economical to transport than gas and, because they are made from long-chain molecules, contain more bonds -- meaning they pack energy more densely."

In Jain's lab, Sungju Yu, a postdoctoral researcher and first author of the study, uses metal catalysts to absorb green light and transfer electrons and protons needed for chemical reactions between CO2 and water -- filling the role of the pigment chlorophyll in natural photosynthesis.

Gold nanoparticles work particularly well as a catalyst, Jain said, because their surfaces interact favorably with the CO2 molecules, are efficient at absorbing light and do not break down or degrade like other metals that can tarnish easily.

There are several ways in which the energy stored in bonds of the hydrocarbon fuel is freed. However, the easy conventional method of combustion ends up producing more CO2 -- which is counterproductive to the notion of harvesting and storing solar energy in the first place, Jain said.

"There are other, more unconventional potential uses from the hydrocarbons created from this process," he said. "They could be used to power fuel cells for producing electrical current and voltage. There are labs across the world trying to figure out how the hydrocarbon-to-electricity conversion can be conducted efficiently," Jain said.

As exciting as the development of this CO2-to-liquid fuel may be for green energy technology, the researchers acknowledge that Jain's artificial photosynthesis process is nowhere near as efficient as it is in plants.

Read more at Science Daily

Water formation on the Moon demonstrated

Olivine mineral.

For the first time, a cross-disciplinary study has shown chemical, physical, and material evidence for water formation on the Moon. Two teams from the University of Hawai?i at Manoa collaborated on the project: physical chemists at the UH Manoa Department of Chemistry's W.M. Keck Research Laboratory in Astrochemistry and planetary scientists at the Hawaii Institute of Geophysics and Planetology (HIGP).

Although recent discoveries by orbiting spacecraft such as the Lunar Prospector and the hard lander Lunar Crater Observation and Sensing Satellite suggest the existence of water ice at the poles the Moon, the origin of this water has remained uncertain. Lunar water represents one of the key requirements for permanent colonization of the Moon as a feedstock for fuel and energy generation (hydrogen, oxygen) and also as "drinking water."

The breakthrough research is outlined in "Untangling the formation and liberation of water in the lunar regolith," lead-authored by UH Manoa postdoctoral fellow Cheng Zhu and colleagues in the Proceedings of the National Academy of Sciences.

Chemistry Professor Ralf I. Kaiser and HIGP's Jeffrey Gillis-Davis designed the experiments to test the synergy between hydrogen protons from solar wind, lunar minerals, and micrometeorite impacts. Zhu irradiated samples of olivine, a dry mineral that serves as a surrogate of lunar material, with deuterium ions as a proxy for solar wind protons.

Deuterium irradiated only "experiments did not reveal any trace of water formation, even after increasing the temperature to lunar mid-latitude daytime temperatures," Zhu explained. "But when we warmed the sample, we detected molecular deuterium, suggesting that deuterium -- or hydrogen -- implanted from the solar wind can be stored in the lunar rock."

Kaiser added, "Therefore, another high-energy source might be necessary to trigger water formation within the Moon's minerals followed by its release as a gas that can be detected."

The second set of deuterium irradiation experiments was followed by laser heating to simulate the thermal effects of micrometeorite impacts. A burst of ions with mass-to-charge ratios matching that of singly ionized heavy water was observed in the gas phase during the laser pulses. "Water continued to be produced during laser pulses after the temperature was increased, suggesting that the olivine was storing precursors to heavy water that were released by laser heating," said Zhu.

To image these processes and interpret the broader impact on the Moon and other bodies, HIGP's Hope Ishii and John Bradley used focused ion beam-scanning electron microscopy and transmission electron microscopy in the Advanced Electron Microscopy Center. They observed sub-micrometer-sized surface pits, some partially covered by lids, suggesting that water vapor builds up under the surface in vesicles until they burst, releasing water from lunar silicates upon micrometeorite impact.

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Three exocomets discovered around the star Beta Pictoris

Comet illustration.

Three extrasolar comets have been discovered around the star Beta Pictoris, 63 light years away, by the University of Innsbruck. Analysis of data from the current NASA mission TESS by Sebastian Zieba and Konstanze Zwintz from the Institute for Astro- and Particle Physics, together with colleagues from Leiden University and the University of Warwick has revealed the extrasolar objects.

Just about a year after the launch of the NASA mission TESS, the first three comets orbiting the nearby star Beta Pictoris outside our solar system were discovered in data from the space telescope. The main goal of TESS is to search for exoplanets -- planets orbiting other stars. The recognition of signals from much smaller exocomets compared to planets requires the analysis of a precise light curve, which can now be obtained using the technical sophistication of the new space telescope.

Sebastian Zieba, Master's student in the team of Konstanze Zwintz at the Institute of Astro- and Particle Physics at the University of Innsbruck, discovered the signal of the exocomets when he investigated the TESS light curve of Beta Pictoris in March this year. "The data showed a significant decrease in the intensity of the light of the observed star. These variations due to darkening by an object in the star's orbit can clearly be related to a comet," Sebastian Zieba and Konstanze Zwintz explain the sensational discovery.

In collaboration with Matthew Kenworthy from Leiden University (Netherlands) and Grant Kennedy from the University of Warwick (UK), they analysed and interpreted the signals of the exocomets. The results will now be published in the international journal Astronomy and Astrophysics. Three similar exocomet systems have recently been found around three other stars during data analysis by NASA's Kepler mission. The researchers suggest that exocomets are more likely to be found around young stars. "The space telescope Kepler concentrated on older stars similar to the Sun in a relatively small area in the sky. TESS, on the other hand, observes stars all over the sky, including young stars. We therefore expect further discoveries of this kind in the future," says Konstanze Zwintz. Zwintz's research focuses on young stars and she is regarded as an internationally renowned expert in the field of asteroseismology.

Dr Grant Kennedy, from the University of Warwick Department of Physics, assisted with the modelling and interpretation of the data. He said: "This discovery is really important for the science of extrasolar comets for several reasons. Beta Pictoris had been thought to host exocomets for three decades from a different technique, and the TESS data provide long overdue and independent evidence for their existence. Our next aim is to find similar signatures around other stars, and this discovery shows that TESS is up to the task."

Famous star

The young and very bright star Beta Pictoris is a "celebrity" among astronomers for many reasons: "Already in the 1980s, investigations of Beta Pictoris provided convincing evidence for planetary systems around stars other than our Sun -- a decade before exoplanets were even discovered for the first time. In addition, there was already indirect evidence for comets at that time based on the characteristic signature of evaporating gas coming off them," adds Konstanze Zwintz. At about 23 million years old, Beta Pictoris is a relatively young star, "a young adult star compared to human age," says the astronomer.

The discovery of exocomets around Beta Pictoris was predicted in 1999 in a paper by the astrophysicists Alain Lecavelier des Etangs, Alfred Vidal-Madjar and Roger Ferlet. "Together with our colleagues from Leiden and Warwick, we are pleased to have finally confirmed this theory," say Zieba and Zwintz. The scientists expect to discover many more comets and asteroids in this area, as it is a young star. "In the future, we want to find answers to the question of how often exocomets occur and whether their number really decreases with the age of a star. Information about this is important because by analysing the comets around a young star we can also draw conclusions about the history of our own solar system. Because we know that our solar system showed considerably more comets in 'young years'," explains Konstanze Zwintz.

Read more at Science Daily

18 Earth-sized exoplanets discovered

Extrasolar planet illustration.

Somewhat more than 4000 planets orbiting stars outside our solar system are known so far. Of these so-called exoplanets, about 96 percent are significantly larger than our Earth, most of them more comparable with the dimensions of the gas giants Neptune or Jupiter. This percentage likely does not reflect the real conditions in space, however, since small planets are much harder to track down than big ones. Moreover, small worlds are fascinating targets in the search for Earth-like, potentially habitable planets outside the solar system.

The 18 newly discovered worlds fall into the category of Earth-sized planets. The smallest of them is only 69 percent of the size of the Earth; the largest is barely more than twice the Earth's radius. And they have another thing in common: all 18 planets could not be detected in the data from the Kepler Space Telescope so far. Common search algorithms were not sensitive enough.

In their search for distant worlds, scientists often use the so-called transit method to look for stars with periodically recurring drops in brightness. If a star happens to have a planet whose orbital plane is aligned with the line of sight from Earth, the planet occults a small fraction of the stellar light as it passes in front of the star once per orbit.

"Standard search algorithms attempt to identify sudden drops in brightness," explains Dr. Rene Heller from MPS, first author of the current publications. "In reality, however, a stellar disk appears slightly darker at the edge than in the center. When a planet moves in front of a star, it therefore initially blocks less starlight than at the mid-time of the transit. The maximum dimming of the star occurs in the center of the transit just before the star becomes gradually brighter again," he explains.

Large planets tend to produce deep and clear brightness variations of their host stars so that the subtle center-to-limb brightness variation on the star hardly plays a role in their discovery. Small planets, however, present scientists with immense challenges. Their effect on the stellar brightness is so small that it is extremely hard to distinguish from the natural brightness fluctuations of the star and from the noise that necessarily comes with any kind of observation. René Heller's team has now been able to show that the sensitivity of the transit method can be significantly improved, if a more realistic light curve is assumed in the search algorithm.

"Our new algorithm helps to draw a more realistic picture of the exoplanet population in space," summarizes Michael Hippke of Sonneberg Observatory. "This method constitutes a significant step forward, especially in the search for Earth-like planets."

The researchers used data from NASA's Kepler space telescope as a test bed for their new algorithm. In the first mission phase from 2009 to 2013, Kepler recorded the light curves of more than 100,000 stars, resulting in the discovery of over 2300 planets. After a technical defect, the telescope had to be used in an alternative observing mode, called the K2 mission, but it nevertheless monitored more than another 100,000 stars by the end of the mission in 2018. As a first test sample for their new algorithm, the researchers decided to re-analyze all 517 stars from K2 that were already known to host at least one transiting planet.

In addition to the previously known planets, the researchers discovered 18 new objects that had previously been overlooked. "In most of the planetary systems that we studied, the new planets are the smallest," co-author Kai Rodenbeck of the University of Göttingen and MPS describes the results. What is more, most of the new planets orbit their star closer than their previously known planetary companions. The surfaces of these new planets therefore likely have temperatures well in excess of 100 degrees Celsius; some even have temperatures of up to 1000 degrees Celsius. Only one of the bodies is an exception: it likely orbits its red dwarf star within the so-called habitable zone. At this favorable distance from its star, this planet may offer conditions under which liquid water could occur on its surface -- one of the basic prerequisites for life as we know it on Earth.

Of course, the researchers cannot rule out that their method, too, is blind to other planets in the systems they investigated. In particular, small planets at large distances to their host stars are known to be problematic. They require more time to complete a full orbit than planets orbiting their stars closer in. As a consequence, the transits of planets in wide orbits occur less often, which makes their signals even harder to detect.

Read more at Science Daily

Ammonium fertilized early life on Earth

Early Earth concept.

A team of international scientists -- including researchers at the University of St. Andrews, Syracuse University and Royal Holloway, University of London -- has demonstrated a new source of food for early life on the planet.

Life on Earth relies on the availability of critical elements such as nitrogen and phosphorus. These nutrient elements are ubiquitous to all life, as they are required for the formation of DNA, the blueprints of life, and proteins, the machinery. They are originally sourced from rocks and the atmosphere, so their availability to life has fluctuated alongside significant changes in the chemistry of Earth's surface environments over geologic time.

The research, published in Nature Geoscience, reveals how the supply of these elements directly impacted the growth of Earth's oxygen-rich atmosphere and were key to the evolution of early life on Earth.

The most dramatic change in Earth history followed the evolution of oxygenic photosynthesis, which fundamentally transformed the planet by providing a source of carbon to the biosphere and a source of oxygen to the atmosphere, the latter culminating in the Great Oxidation Event (GOE) some 2.3 billion years ago.

Despite the critical importance of nutrients to life, the availability of nitrogen and phosphorus in pre-GOE oceans is not well understood, particularly how the supply of these elements drove and/or responded to planetary oxygenation.

Using samples of exceptionally well-preserved rocks that have been associated with early evidence for oxygenic photosynthesis 2.7 billion year ago, the team of researchers examined Earth's early nitrogen cycle to decipher feedbacks associated with the initial stages of planetary oxygenation.

"There is precious little rock available from this time interval that is suitable for the type of analyses we performed. Most rocks that are this old have been deformed and heated during 2.7 billion years of plate tectonic activity, rendering the original signals of life lost," says Christopher Junium, associate professor of Earth sciences in the College of Arts and Sciences.

The rock samples showed the first direct evidence of the build-up of a large pool of ammonium in the pre-GOE oceans. This ammonium would have provided an ample source of nitrogen to fuel the early biosphere and associated oxygen production.

Research team leader Aubrey Zerkle, reader in the School of Earth and Environmental Sciences at the University of St Andrews, says: "Today we think of ammonium as the unpleasant odor in our cleaning supplies, but it would've served as an all-you-can-eat buffet for the first oxygen-generating organisms, a significant improvement on the dumpster scraps they relied on earlier in Earth's history."

As well as helping scientists better understand the role of the nitrogen cycle in global oxygenation, the new findings also provide context for other nutrient feedbacks during early planetary evolution.

"It is becoming ever more clear that the game of nutrient limitation has tipped back and forth through Earth's history as life has evolved and as conditions have changed," Junium says.

Read more at Science Daily

New lens manufacturing technique

Researchers from Washington State University and Ohio State University have developed a low-cost, easy way to make custom lenses that could help manufacturers avoid the expensive molds required for optical manufacturing.

Led by Lei Li, assistant professor in the School of Mechanical and Materials Engineering, and graduate student, Mojtaba Falahati, the researchers developed a liquid mold from droplets that they can manipulate with magnets to create lenses in a variety of shapes and sizes. Their work is featured on the cover of the journal, Applied Physics Letters.

High-quality lenses are increasingly used in everything from cameras, to self-driving cars, and virtually all robotics, but the traditional molding and casting processes used in their manufacturing require sophisticated and expensive metal molds. So, manufacturers are mostly limited to mass producing one kind of lens.

"The molds are precisely finished and are difficult to make," said Li. "It isn't worthwhile to make a mold for low-volume production."

The researchers ran into the problem firsthand as they searched for lenses for their work to develop a portable laboratory reader on a phone.

They first tried to make their own lenses using 3D printing but found it difficult to control the lens shape. They then came up with the idea of using magnets and the surface tension of liquids to literally create free-flowing molds.

They placed tiny, magnetic iron particles into liquid droplets and built a device to surround the droplets with magnets. They then poured the plastic material used in lenses over the droplet. As they applied a magnetic field, the droplet took on a conical lens shape -- creating a mold for the plastic lens material. Once they cured the plastic, it hardened and had the same optical properties and imaging quality as a commercially purchased lens. The liquid droplet remains separate and can be re-used.

The magnets can be moved to change the magnetic field, the shape of the mold, and the resulting lens. The researchers also used bigger or smaller droplets to create lenses of varying sizes.

"We brought the concept of interfacial tension to the field of optics by introducing an innovative controllable liquid mold," said Li. "This novel process allowed us to regulate the shape of a magnetic drop and to create lenses without having to fabricate expensive molds."

From Science Daily

Counter-intuitive climate change solution

Gas burning.

A relatively simple process could help turn the tide of climate change while also turning a healthy profit. That's one of the hopeful visions outlined in a new Stanford-led paper that highlights a seemingly counterintuitive solution: converting one greenhouse gas into another.

The study, published in Nature Sustainability on May 20, describes a potential process for converting the extremely potent greenhouse gas methane into carbon dioxide, which is a much less potent driver of global warming. The idea of intentionally releasing carbon dioxide into the atmosphere may seem surprising, but the authors argue that swapping methane for carbon dioxide is a significant net benefit for the climate.

"If perfected, this technology could return the atmosphere to pre-industrial concentrations of methane and other gases," said lead author Rob Jackson, the Michelle and Kevin Douglas Provostial Professor in Earth System Science in Stanford's School of Earth, Energy & Environmental Sciences.

The basic idea is that some sources of methane emissions -- from rice cultivation or cattle, for example -- may be very difficult or expensive to eliminate. "An alternative is to offset these emissions via methane removal, so there is no net effect on warming the atmosphere," said study coauthor Chris Field, the Perry L. McCarty Director of the Stanford Woods Institute for the Environment.

A problem and a possible solution

In 2018, methane -- about 60 percent of which is generated by humans -- reached atmospheric concentrations two and a half times greater than pre-industrial levels. Although the amount of carbon dioxide in the atmosphere is much greater, methane is 84 times more potent in terms of warming the climate system over the first 20 years after its release.

Most scenarios for stabilizing average global temperatures at 2 degrees Celsius above pre-industrial levels depend on strategies for both reducing the overall amount of carbon dioxide entering the atmosphere and removing what's already in the atmosphere through approaches such as tree planting or underground sequestration. However, removing other greenhouse gases, particularly methane, could provide a complementary approach, according to the study's authors, who point to the gas's outsized influence on the climate.

Most scenarios for removing carbon dioxide typically assume hundreds of billions of tons removed over decades and do not restore the atmosphere to pre-industrial levels. In contrast, methane concentrations could be restored to pre-industrial levels by removing about 3.2 billion tons of the gas from the atmosphere and converting it into an amount of carbon dioxide equivalent to a few months of global industrial emissions, according to the researchers. If successful, the approach would eliminate approximately one-sixth of all causes of global warming to date.

Methane is challenging to capture from air because its concentration is so low. However, the authors point out that zeolite, a crystalline material that consists primarily of aluminum, silicon and oxygen, could act essentially as a sponge to soak up methane. "The porous molecular structure, relatively large surface area and ability to host copper and iron in zeolites make them promising catalysts for capturing methane and other gases," said Ed Solomon, the Monroe E. Spaght Professor of Chemistry in the School of Humanities and Sciences.

The whole process might take the form of a giant contraption with electric fans forcing air through tumbling chambers or reactors full of powdered or pelletized zeolites and other catalysts. The trapped methane could then be heated to form and release carbon dioxide, the authors suggest.

A profitable future

The process of converting methane to carbon dioxide could be profitable with a price on carbon emissions or an appropriate policy. If market prices for carbon offsets rise to $500 or more per ton this century, as predicted by most relevant assessment models, each ton of methane removed from the atmosphere could be worth more than $12,000.

A zeolite array about the size of a football field could generate millions of dollars a year in income while removing harmful methane from the air. In principle, the researchers argue that the approach of converting a more harmful greenhouse gas to one that's less potent could also apply to other greenhouse gases.

Read more at Science Daily

Formation of the moon brought water to Earth

Earth seen from the moon.

The Earth is unique in our solar system: It is the only terrestrial planet with a large amount of water and a relatively large moon, which stabilizes the Earth's axis. Both were essential for Earth to develop life.

Planetologists at the University of Münster (Germany) have now been able to show, for the first time, that water came to Earth with the formation of the Moon some 4.4 billion years ago. The Moon was formed when Earth was hit by a body about the size of Mars, also called Theia. Until now, scientists had assumed that Theia originated in the inner solar system near the Earth. However, researchers from Münster can now show that Theia comes from the outer solar system, and it delivered large quantities of water to Earth. The results are published in the current issue of Nature Astronomy.

From the outer into the inner solar system

The Earth formed in the 'dry' inner solar system, and so it is somewhat surprising that there is water on Earth. To understand why this the case, we have to go back in time when the solar system was formed about 4.5 billion years ago. From earlier studies, we know that the solar system became structured such that the 'dry' materials were separated from the 'wet' materials: the so-called 'carbonaceous' meteorites, which are relatively rich in water, come from the outer solar system, whereas the drier 'non-carbonaceous' meteorites come from the inner solar system. While previous studies have shown that carbonaceous materials were likely responsible for delivering the water to Earth, it was unknown when and how this carbonaceous material -- and thus the water -- came to Earth.

"We have used molybdenum isotopes to answer this question. The molybdenum isotopes allow us to clearly distinguish carbonaceous and non-carbonaceous material, and as such represent a 'genetic fingerprint' of material from the outer and inner solar system," explains Dr. Gerrit Budde of the Institute of Planetology in Münster and lead author of the study.

The measurements made by the researchers from Münster show that the molybdenum isotopic composition of the Earth lies between those of the carbonaceous and non-carbonaceous meteorites, demonstrating that some of Earth's molybdenum originated in the outer solar system. In this context, the chemical properties of molybdenum play a key role because, as it is an iron-loving element, most of the Earth's molybdenum is located in the core.

"The molybdenum which is accessible today in the Earth's mantle, therefore, originates from the late stages of Earth's formation, while the molybdenum from earlier phases is entirely in the core," explains Dr. Christoph Burkhardt, second author of the study. The scientists' results therefore show, for the first time, that carbonaceous material from the outer solar system arrived on Earth late.

But the scientists are going one step further. They show that most of the molybdenum in Earth's mantle was supplied by the protoplanet Theia, whose collision with Earth 4.4 billion years ago led to the formation of the Moon. However, since a large part of the molybdenum in Earth's mantle originates from the outer solar system, this means that Theia itself also originated from the outer solar system. According to the scientists, the collision provided sufficient carbonaceous material to account for the entire amount of water on Earth.

Read more at Science Daily

Bonobo mothers help their sons to have more offspring

Bonobos.

In many social animal species individuals share child-rearing duties, but new research from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, finds that bonobo mothers go the extra step and actually take action to ensure their sons will become fathers. This way bonobo mothers increase their sons' chance of fatherhood three-fold.

"This is the first time that we can show the impact of the mother's presence on a very important male fitness trait, which is their fertility," says Martin Surbeck, a primatologist at the Max Planck Institute for Evolutionary Anthropology. "We were surprised to see that the mothers have such a strong, direct influence on the number of grandchildren they get."

Surbeck and his colleagues observed wild populations of bonobos in the Democratic Republic of Congo, as well as wild populations of chimpanzees in Ivory Coast, Tanzania, and Uganda. They found that while both bonobo and chimpanzee mothers would advocate for their sons in male-on-male conflicts, bonobo moms went the extra mile to aid their sons' copulation efforts. This involved protecting their sons' mating attempts from other males and intervening in other male's mating attempts.

The bonobo mothers were also able to use their rank in the bonobo's matriarchal society to give their sons access to popular spots within social groups in the community and help them achieve higher male status -- and therefore, better mating opportunities. The authors note that these interactions were rare in chimpanzee societies and did not have an effect on male fertility; in chimpanzees males hold dominant positions over females, making the actions of chimp mothers less influential than those of bonobo mothers.

Interestingly, bonobo moms did not extend similar help to their daughters, nor were there any observations of daughters receiving assistance in rearing their offspring. "In bonobo social systems, the daughters disperse from the native community and the sons stay," Surbeck says. "And for the few daughters that stay in the community, which we don't have many examples of, we don't see them receiving much help from their mothers."

Moving forward, Surbeck and his team would like to better understand the benefits these behaviors confer on bonobo mothers. Currently, they think that it allows for an indirect continuation of their genes. "These females have found a way to increase their reproductive success without having more offspring themselves," he says, noting that the prolongation of the post-reproductive human female lifespan, as well as the early-age at which human women can no longer bare children, may have evolved from this indirect method of continuing their genetic line.

Surbeck acknowledges that gathering data on post-reproductive lifespans of females in chimp and bonobo communities will require a long-term, collaborative study, similar to this one. "Without the help and participation from all of the field sites where data was collected, these important interactions could have been overlooked," he says. "Now as the director of a bonobo field site, I'm looking forward to further exploring this topic."

Read more at Science Daily

Evolution in the gut

They are a part of us: we all carry about ten times as many bacteria and archaea as our own cells. The bacterial ecosystem in our digestive tract, the so-called microbiome, is not only of great importance for our metabolism, but also for the immune system and even our behaviour. The same is true to animals, but the composition of the microbiome differs greatly between animal species. For the first time, a large-scale study was carried out to explain the development of the microbiome using faecal samples from free-living animals. 128 different species from very classes fish, amphibians, reptiles, birds and mammals were examined. The research groups involved were able to show how evolution and dietary habits interact and determine the composition of bacteria in the digestive tract. Many microorganisms in the intestine seem to have developed in sync with their host animals over millions of years. These results should also help in the characterisation of faecal pollution in water by allowing attribution to certain animal species in a much more precise way in the future.

Samples from all branches of the family tree

"So far there have been studies on the microbiome of humans, or special data for individual species such as rats. However, we wanted to select many animal species that were as representative as possible of the entire evolutionary tree of vertebrates -- from birds to mammals to fish," says Prof. Andreas Farnleitner, Co-Leader of the Interuniversity Research Centre "Water and Health" at the TU Wien (ICC Water & Health) and Professor of Microbiological Diagnostics in extension of the ICC Water & Health group at Karl Landsteiner Private University in Krems.

It was important to get samples from wild animals, as zoo animals can have a completely different microbiome than their wild counterparts. The Institute for Wildlife Science and Ecology of the University of Veterinary Medicine Vienna was the lead partner for the sample collection. The DNA of the microorganisms studied was then sequenced -- partly at the TU Wien and partly at the Max Planck Institute for Developmental Biology in Tübingen.

"A total of more than 400 samples from 180 different species were analysed, resulting in 20 million gene sequences," said Dr. Georg Reischer (TU Vienna). The cooperation partners of the MPI in Tübingen contributed their know-how in bioinformatic data analysis and evolutionary biology to the study. This revealed striking relationships that can be explained by evolutionary history: The microbiome has developed over many millions of years in co-evolution with the host animals. Closely related species that are close to the evolutionary family tree also have similarities in the microbiome. "Nutrition also plays a role, but it is never the only decisive factor," explains Georg Reischer. "If a mammal eats the same food as a bird, it still does not have the same bacteria in its intestines."

The contamination bio-detector
The data collected in this study not only allows the interpretation of the co-evolution of host animals and the microorganisms in their digestive tract, it also facilitates the development of methods to assist in the provision of clean water. In recent years, a technology has been developed at the TU Wien that uses DNA tests to provide information on the source of fecal pollution in water. Thus it became possible to find out whether the contamination was caused by human wastewater or grazing animals. "Now we have a very extensive data set at our disposal that will make such tests possible in a much more comprehensive and accurate way," says Andreas Farnleitner.

From Science Daily

True identity of imposter 'pigs' on 17th century map overturns early colonial history of Barbados

Peccary.

Which came first, the pigs or the pioneers? In Barbados, that has been a historical mystery ever since the first English colonists arrived on the island in 1627 to encounter what they thought was a herd of wild European pigs.

A recent discovery by an SFU archaeologist is shedding new light on the matter. Christina Giovas uncovered the jaw bone of a peccary, a South American mammal that resembles a wild pig, while researching a larger project on prehistoric animal introductions in the Caribbean.

"I didn't give it much notice at the time, but simply collected it along with other bones," says Giovas, the lead author of a study just published in PLOS ONE. "It was completely unexpected and I honestly thought I must have made a mistake with the species identification."

Giovas and collaborators George Kamenov and John Krigbaum of the University of Florida radiocarbon-dated the bone and conducted strontium isotope analysis to determine the age and whether the peccary was born on Barbados or had been imported from elsewhere.

The results showed the peccary was local and dated to 1645-1670, when the English wrote their account of finding wild European pigs on the Caribbean island. The researchers were not only able to show there had been a previously undetected historic peccary introduction but that the region's earliest celebrated maps depicted peccaries that had been mistaken for pigs by the English.

Giovas says the findings upend Barbados' accepted colonial history and reflect how quickly Europeans began to alter New World environments by altering species distributions.

"Checking historical and archaeological records, we determined the most likely source of peccary introduction was from Spanish or Portuguese ships passing the island in the 16th century -- and most likely left as a source of meat for future visiting sailors," she says.

From Science Daily

Gas insulation could be protecting an ocean inside Pluto

Pluto.

A gassy insulating layer beneath the icy surfaces of distant celestial objects could mean there are more oceans in the universe than previously thought.

Computer simulations provide compelling evidence that an insulating layer of gas hydrates could keep a subsurface ocean from freezing beneath Pluto's icy exterior, according to a study published in the journal Nature Geoscience.

In July 2015, NASA's New Horizons spacecraft flew through Pluto's system, providing the first-ever close-up images of this distant dwarf planet and its moons. The images showed Pluto's unexpected topography, including a white-colored ellipsoidal basin named Sputnik Planitia, located near the equator and roughly the size of Texas.

Because of its location and topography, scientists believe a subsurface ocean exists beneath the ice shell which is thinned at Sputnik Planitia. However, these observations are contradictory to the age of the dwarf planet because the ocean should have frozen a long time ago and the inner surface of the ice shell facing the ocean should have also been flattened.

Researchers at Japan's Hokkaido University, the Tokyo Institute of Technology, Tokushima University, Osaka University, Kobe University, and at the University of California, Santa Cruz, considered what could keep the subsurface ocean warm while keeping the ice shell's inner surface frozen and uneven on Pluto. The team hypothesized that an "insulating layer" of gas hydrates exists beneath the icy surface of Sputnik Planitia. Gas hydrates are crystalline ice-like solids formed of gas trapped within molecular water cages. They are highly viscous, have low thermal conductivity, and could therefore provide insulating properties.

The researchers conducted computer simulations covering a timescale of 4.6 billion years, when the solar system began to form. The simulations showed the thermal and structural evolution of Pluto's interior and the time required for a subsurface ocean to freeze and for the icy shell covering it to become uniformly thick. They simulated two scenarios: one where an insulating layer of gas hydrates existed between the ocean and the icy shell, and one where it did not.

The simulations showed that, without a gas hydrate insulating layer, the subsurface sea would have frozen completely hundreds of millions of years ago; but with one, it hardly freezes at all. Also, it takes about one million years for a uniformly thick ice crust to completely form over the ocean, but with a gas hydrate insulating layer, it takes more than one billion years.

The simulation's results support the possibility of a long-lived liquid ocean existing beneath the icy crust of Sputnik Planitia.

The team believes that the most likely gas within the hypothesized insulating layer is methane originating from Pluto's rocky core. This theory, in which methane is trapped as a gas hydrate, is consistent with the unusual composition of Pluto's atmosphere -- methane-poor and nitrogen-rich.

Read more at Science Daily