Tuesday, April 30, 2019

The Evolution Of South America Mammals: Climate, Grasses and Teeth

The atmospheric circulation called the Hadley circulation intensified about 6 million years ago and fueled environmental changes in South America, a University of Arizona (UA)-led team found.

The Hadley cell, named after George Hadley, is a global scale tropical atmospheric circulation that features air rising near the Equator, flowing poleward at a height of 10 to 15 kilometers above the earth’s surface, descending in the subtropics, and then returning equatorward near the surface. This circulation creates the trade winds, tropical rain-belts and hurricanes, subtropical deserts and the jet streams.  

Global circulation of Earth's atmosphere displaying Hadley cell, Ferrell cell and polar cell.
Credit: Kaidor / Wikimedia Commons

Armadillos as big as Volkswagens and other grass-eating mammals became more diverse in South America about 6 million years ago because shifts in atmospheric circulation drove changes in climate and vegetation, a UA geoscientist and her colleagues report.

Geoscientists already knew the Earth was cooling 7 to 5.5 million years ago, a period of time known as the late Miocene

An illustration of two male glyptodonts (Doedicurus clavicaudatus) facing off: The massive, club-shaped tails were probably used more for intraspecific combat than defense against predators. 
Illustration: © Peter Schouten

However, the changes in ocean climate during that time have been better understood than changes in the continental climate, said lead author Barbara Carrapa, professor and head of the UA Department of Geosciences.

The new research shows that about 7 to 6 million years ago, the global tropical atmospheric circulation known as the Hadley circulation intensified. As a result, the climate of South America became drier, subtropical grasslands expanded and the numbers of mammal species that were good at eating grasses increased.

Carrapa and her colleagues used a computer model to figure out that the Hadley circulation had strengthened in the late Miocene, altering the climate. They then compared the model's predictions of the past climate with the natural archives of rainfall and vegetation stored in ancient soils. The model's predictions agreed with the natural archives.

"We found a strong correlation between this big change in late Miocene climate and circulation that affected the ecology – the plants and animals," she said. "It has implications for ecosystem evolution."

Carrapa said the new research – an unusual blend of mammalian paleontology, the geochemistry of ancient soils and global climate computer models – provides a new understanding of the late Miocene, a time when near-modern ecosystems became established.

The paper, "Ecological and hydroclimate responses to strengthening of the Hadley circulation in South America during the Late Miocene Cooling," by Carrapa, Mark Clementz of the University of Wyoming and Ran Feng of the University of Connecticut was published April 29 in the Proceedings of the National Academy of Sciences. The National Science Foundation funded the research.

Geoscientists use the geochemistry of ancient soils, specifically forms of the elements oxygen and carbon, to infer past precipitation and vegetation. Researchers had thought the precipitation at the time the soil formed was mostly a function of the site's topography and elevation.

Carrapa wanted to test that idea by looking at the geochemistry of ancient soils on a continental scale. She teamed up with her long-time colleague Clementz, a paleontologist.

The researchers compiled the published data of the oxygen-18/oxygen-16 ratio and carbon-13/carbon-12 ratio from ancient soils covering a wide swath of South America – from 15 degrees South latitude to 35 degrees South latitude, or about the change from La Paz, Bolivia, to Buenos Aires, Argentina. Changes in the oxygen ratio provide information on past precipitation, while changes in carbon ratio indicate what plants were growing at the time.

Clementz scoured the published literature and did what Carrapa called "... an amazing job of pulling all the data together so we could look at it in a comprehensive way."

Barbara Carrapa takes rock samples at 14,000 feet (4267 m) on Cerro Penitentes in the Cordillera Central of Argentina. 
Barbara Carrapa takes rock samples at 14,000 feet (4267 m) on Cerro Penitentes in the Cordillera Central of Argentina. (Photo: Peter DeCelles/University of Arizona)
Photo: Peter DeCelles/University of Arizona

The results were surprising, Carrapa said. The changes in soil geochemistry during the late Miocene changed in latitudinal bands from north to south, indicating an underlying cause spanning much of South America, not just local changes in elevation or topography.

The two researchers thought the systematic shifts in soil geochemistry were related to changes in climate, so they asked Feng to help them by applying the global climate model she used for research.

Feng loaded known information about the Miocene-to-late-Miocene climate, including atmospheric carbon dioxide concentrations and the ocean temperatures, into the computer model and then asked it to simulate three different versions of late Miocene climate – not much cooler, cooler, and much cooler than before. In each case, the simulation indicated what soil geochemistry would have occurred under that climate regime.

The team found the geochemistry of South American ancient soils predicted by the model matches the geochemistry of the actual soil samples.

Feng figured out that the Earth's Hadley circulation intensified from 7 to 6 million years ago.

"The records compiled by Barbara and Mark could be explained by a significant change in the strength of the Hadley circulation," she said.

Feng's work with the global climate model shows how the past climate could have created the patterns the team was seeing in the soil geochemistry, Clementz said.

The carbon ratio from the ancient soils reflects the vegetation of the time and indicates that in the late Miocene, grasslands were expanding as the climate was changing.

"During the late Miocene, things are starting to dry out, particularly in the 25-30 degree South zone," he said. "There's also an increase in the numbers of animals with high-crowned or ever-growing teeth."

Grasses contain silica, an abrasive substance, which is why grass-eaters have either high-crowned teeth or teeth that continue to grow. The mammals that became more prevalent in the late Miocene included giant armadillos and rhinoceros-like animals and also smaller mammals, he said.

Carrapa said, "Looking at geological pasts is like looking at different planets. The state of the Earth we see today is very different from the Earth of 10 million years ago, 6 million years ago – it's a different planet. You have the possibility of looking at a different planet through the lens of time, and with the geological record we can do that."


Contacts and sources:
Mari N. Jensen
University of Arizona

Citation: Ecological and hydroclimate responses to strengthening of the Hadley circulation in South America during the Late Miocene cooling.
Barbara Carrapa, Mark Clementz, Ran Feng.Proceedings of the National Academy of Sciences, 2019; 201810721 DOI: 10.1073/pnas.1810721116


How Humans Hit Their Stride

No creature walks like humans do now.  Our ancestors moved like chimpanzees, bonobos, and gorillas before our current stride evolved.

African apes adapted to living on the ground, a finding that indicates human evolved from an ancestor not limited to tree or other elevated habitats. The analysis adds a new chapter to evolution, shedding additional light on what preceded human bipedalism.

File:Lightmatter silverback gorilla.jpg
Credit: Photo by Aaron Logan source / Wikimedia Commons

“Our unique form of human locomotion evolved from an ancestor that moved in similar ways to the living African apes—chimpanzees, bonobos, and gorillas,” explains Thomas Prang, a doctoral candidate in New York University’s Department of Anthropology and the author of the study, which appears in the journal eLife. “In other words, the common ancestor we share with chimpanzees and bonobos was an African ape that probably had adaptations to living on the ground in some form and frequency.”

The way that humans walk—striding bipedalism—is unique among all living mammals, an attribute resulting from myriad changes over time.

“The human body has been dramatically modified by evolutionary processes over the last several million years in ways that happened to make us better walkers and runners,” notes Prang.

Much of this change is evident in the human foot, which has evolved to be a propulsive organ, with a big toe incapable of ape-like grasping and a spring-like, energy-saving arch that runs from front to back.

An evolutionary tree depicting the relationships among living apes, Ardi, and modern humans. Each branch on the tree represents a species and their intersections represent their common ancestors. The dots represent hypothetical evolutionary changes associated with the evolution of ground-living adaptations in the common ancestor of African apes and humans as well as the evolution of bipedalism, which is supported by the analysis. This shows that human bipedalism evolved from an ancestral form similar to the living African apes.


Image courtesy of Thomas Prang.


These traits raise a long-studied, but not definitively answered, question: From what kind of ancestor did the human foot evolve?

In the eLife work, Prang, a researcher in NYU’s Center for the Study of Human Origins, focused on the fossil species Ardipithecus ramidus (‘Ardi’), a 4.4 million-years-old human ancestor from Ethiopia—more than a million years older than the well-known ‘Lucy’ fossil. Ardi’s bones were first publicly revealed in 2009 and have been the subject of debate since then.

In his research, Prang ascertained the relative length proportions of multiple bones in the primate foot skeleton to evaluate the relationship between species’ movement (locomotion) and their skeletal characteristics (morphology). In addition, drawing upon the Ardi fossils, he used statistical methods to reconstruct or estimate what the common ancestor of humans and chimpanzees might have looked like.

Here, he found that the African apes show a clear signal of being adapted to ground-living. The results also reveal that the Ardi foot and the estimated morphology of the human-chimpanzee last common ancestor is most similar to these African ape species.

“Therefore, humans evolved from an ancestor that had adaptations to living on the ground, perhaps not unlike those found in African apes,” Prang concludes. “These findings suggest that human bipedalism was derived from a form of locomotion similar to that of living African apes, which contrasts with the original interpretation of these fossils.”

The original interpretation of the Ardi foot fossils, published in 2009, suggested that its foot was more monkey-like than chimpanzee- or gorilla-like. The implication of this interpretation is that many of the features shared by living great apes (chimpanzees, bonobos, gorillas, and orangutans) in their foot and elsewhere must have evolved independently in each lineage—in a different time and place.

“Humans are part of the natural world and our locomotor adaptation—bipedalism—cannot be understood outside of its natural evolutionary context,” Prang observes. “Large-scale evolutionary changes do not seem to happen spontaneously. Instead, they are rooted in deeper histories revealed by the study of the fossil record.

“The study of the Ardi fossil shows that the evolution of our own ground-living adaptation—bipedalism—was preceded by a quadrupedal ground-living adaptation in the common ancestors that we share with the African apes.”  DOI: 10.7554/eLife.44433

Contacts and sources:
James Devitt
New York University

Citation: The African ape-like foot of Ardipithecus ramidus and its implications for the origin of bipedalism.
Thomas Cody Prang. eLife, 2019; 8 DOI: 10.7554/eLife.44433

Deep Learning Seeks Storms on Saturn

Artificial intelligence will we watching for storms on Saturn. 

A ‘deep learning’ approach to detecting storms on Saturn is set to transform our understanding of planetary atmospheres, according to UCL and University of Arizona researchers.

The new technique, called PlanetNet, identifies and maps the components and features in turbulent regions of Saturn’s atmosphere, giving insights into the processes that drive them.

 Pictured is the longest-lived electrical storm yet observed on Saturn by NASA's Cassini spacecraft.

Credit: University College London

A study, published today in Nature Astronomy, provides results from the first demonstration of the PlanetNet algorithm, which clearly shows the vast regions affected by storms, and that dark storm clouds contain material swept up from the lower atmosphere by strong vertical winds.

Developed by UCL and the University of Arizona researchers, PlanetNet was trained and tested using infrared data from the Visible and Infrared Mapping Spectrometer (VIMS) instrument on Cassini, a joint mission between NASA, the European Space Agency, and the Italian Space Agency.

A dataset containing multiple, adjacent storms observed at Saturn in February 2008 was chosen to provide a range of complex atmospheric features to challenge PlanetNet’s capabilities.

Previous analysis of the dataset indicated a rare detection of ammonia in Saturn’s atmosphere, in the form of an S-shaped cloud.

The map produced through PlanetNet shows that this feature is a prominent part of a much larger upwelling of ammonia ice clouds around a central dark storm. PlanetNet identifies similar upwelling around another small storm, suggesting that such features are quite common.

The map also shows pronounced differences between the centre of storms and the surrounding areas, indicating that the eye gives a clear view into the warmer, deep atmosphere.

“Missions like Cassini gather enormous amounts of data but classical techniques for analysis have drawbacks, either in the accuracy of information that can be extracted or in the time they take to perform. Deep learning enables pattern recognition across diverse, multiple data sets,” said Dr Ingo Waldmann (UCL Physics & Astronomy), lead author and Deputy Director of the UCL Centre for Space and Exoplanet Data.

“This gives us the potential to analyse atmospheric phenomena over large areas and from different viewing angles, and to make new associations between the shape of features and the chemical and physical properties that create them.”

Initially, PlanetNet searches the data for signs of clustering in the cloud structure and gas composition. For areas of interest, it trims the data to remove uncertainties at the edges and runs a parallel analysis of the spectral and spatial properties. Recombining the two data-streams, PlanetNet creates a map that presents quickly and accurately the major components of Saturn’s storms with unprecedented precision.

PlanetNet’s accuracy has been validated on Cassini data not included in the training phase. The whole dataset has also been rotated and resampled to create ‘synthetic’ data for further testing. PlanetNet has achieved over 90% classification accuracy in both test cases.

“PlanetNet enables us to analyse much bigger volumes of data, and this gives insights into the large-scale dynamics of Saturn,” said Professor Caitlin Griffith (University of Arizona), who co-authored this paper. “The results reveal atmospheric features that were previously undetected. PlanetNet can easily be adapted to other datasets and planets, making it an invaluable potential tool for many future missions.”

This project received funding from the European Research Council (ERC), the Science and Technology Funding Council (STFC) and the University of Arizona.




Contacts and sources:
Bex Caygill
University College London

Citation: Mapping Saturn using deep learning I. P. Waldmann & C. A. Griffith Nature Astronomy (2019) https://www.nature.com/articles/s41550-019-0753-8


Monday, April 29, 2019

Bats Hear in 3D Similar to Sense of Sight

The echolocation of animals uses information similar to our sense of sight to recognize spatial structures. 

The echolocation of bats, despite the different anatomy of the eyes and ears, uses information about three-dimensional spatial structure, as well as the sense of sight. Scientists at the Max Planck Institute for Ornithology in Seewiesen and the Ludwig-Maximilians-University Munich show in a new study that echoes contain information that allows the animals to differentiate different structured surfaces from each other. For example, a fidgety prey stands out acoustically even on a moving water surface for the bats.

The water bats owes their German name to their hunting behavior. In addition to creepy-crawlies, she also likes to taste small fish.

Credit: © dietmar-nill.de

Echo-locating bats have turned night into day. They sonicize their environment with loud ultrasonic calls and listen for reflected echoes. Over a thousand species of bats occupy all imaginable food niches, from mosquito hunters to nectar lickers to fishing bats. If bats hunt close to a background, they must hear the prey echo from a multitude of reflected echoes - the needle in the haystack.

However, why hunting close to the surface of the water, as for example water and pond bats do, is an advantage, explains Holger Goerlitz, head of the research group Acoustic and Functional Ecology at the Max Planck Institute for Ornithology in Seewiesen: "A smooth, still Water surface acts acoustically like a mirror: at the same angle as the sound strikes the surface, it is also reflected. In our case, mainly away from the bat, as it calls obliquely down-front on the water. However, a drifting insect reflects sound back directly to the bat, as a single striking booty echo amidst silence. "But what happens if the water surface is not mirror-smooth? Finally, bats hunt in wind and rain or over flowing waters.

Perception of waves

The scientists have recreated three-dimensional "still images" of water waves. The bats should then distinguish in the dark the flat disc in the middle of each one of the other discs. The animals find this task easier if the discs carry many and high waves - just like humans, if they had to solve a corresponding task visually.

Credit: © Klemen Koselj

Many aquatic predators such as leeches, spiders or amphibians can perceive the three-dimensional structure of water waves and thus distinguish them from prey. For Lutz Wiegrebe from the Biozentrum of the Ludwig-Maximilians-Universität, the question arose as to whether echolocation bats only perform this function with their sense of hearing. This is a real challenge, because it only has to be calculated by comparing the incoming signals at the left and right ear, from which direction the sound arriving at the eardrum of both ears originally comes: "If a noise comes from the left, it gets louder in the left ear and earlier than on the right, "says Leonie Baier, first author of the study. "And when a noise comes from the front, it sounds a little bit different than from the back. This is what the earcups are made of. "Bats also calculate distances:

In order to get to the bottom of the question of the perception of spatial structure, Baier taught her bats to distinguish a smooth surface from a rippled surface - in the dark, so only with the help of echolocation. It turned out that the animals were much better at detecting corrugated surfaces when they had a high spatial frequency, ie many waves on a narrow surface. Then they could even see waves of only about one to two millimeters high. 

However, if the spatial frequency was very low, with only a few waves across the surface, the animals could not detect a difference between the smooth and the rippled surfaces, even if the waves were over three inches high. In comparison to natural conditions, scientists interpret their results as that gentle background waves, such as those created by wind, are virtually invisible to the bats. In contrast, a prey wriggling in the waves catches the eye - or rather, in the ear.

Similarities between hearing and visual sense

"Comparing the sensitivity of echolocation for spatial frequencies with that of the human sense of sight produces astonishing parallels," explains Lutz Wiegrebe. But because the anatomy of the eye and ear are fundamentally different, the researchers went in search of the mechanism that could be behind the performance of the bats. On the computer they simulated the neural activity as it exists in the auditory nerve of the animals. In fact, they found that the echoes contain a lot of information to distinguish differently structured surfaces. Holger Goerlitz summarizes: "We were able to show that mere physical properties of surface structures provide the hearing system with information that the visual system uses to process spatial information."



Contacts and sources:
Dr. Leonie Baier   /  Dr. Holger R. Goerlitz
Max Planck Institute for Ornithology, Seewiesen


Citation: Echo Imaging Exploits to Environmental High-Pass Filter to Access Spatial Information with a Non-Spatial Sensor. A. Leonie Baier, Lutz Wiegrebe & Holger R. Goelitz (2019).
iScience (open access)

Insect World Zombies and Their Creators

In Brazil a wasp has a way to turn a spider in a zombie that will spin a protective web for it's killers children.

Parasitoid wasps lay their eggs on a spider’s back. This team proposes that by injecting the spider host with the molting hormone, ecdysone, the wasp induces the spider to make a special web for the wasp’s pupa.

This feat is dramatic because the wasp larva does not have direct contact with the spider’s nervous system: it is an external parasite, riding on the surface of the spider’s abdomen. Its only access to the spider’s brain is via injections of psychotropic substances into the hemolymph in the spider’s abdomen, to then be carried by the spider’s circulatory system to its central nervous system.

Setting off a startling chain of events, a parasitoid wasp can force a spider to weave a special web to suspend the wasp pupa just before it finishes killing its spider host. William Eberhard, staff scientist emeritus at the Smithsonian Tropical Research Institute and Marcelo Gonzaga at the Universidade Federal de Uberlândia in Brazil have assembled wide-ranging evidence that the ‘zombification’ mechanism involves hacking existing web-spinning mechanisms by hijacking the spider’s own molting hormone, ecdysone.

In a new paper published in the Biological Journal of the Linnean Society they combined a review of all known reports of different wasp species known to zombify different spider species around the world; the results from a molecular study in Brazil; and new observations of Costa Rican spiders to demonstrate several previously unappreciated patterns that suggest that the wasp larvae use ecdysone.

One puzzle the researchers address is how a single wasp species can induce an impressive diversity of changes in the webs of many different spider host species. In the most complex cases, the spider’s web construction is affected at several different stages: from selecting a site to modifying several different key design elements that usually result in a sheltered, stable home for its pupal cocoon.

 A wasp getting ready to attack a spider.

Photo credits: Marcelo O. Gonzaga

A wasp getting ready to attack a spider.

Photo credits: Marcelo O. Gonzaga

A wasp lays an egg on the spotted abdomen of its spider host.

Photo credits: Marcelo O. Gonzaga

Now fully developed, the wasp larva proceeds to eat its host spider.

Photo credits: Marcelo O. Gonzaga

After eating the spider, this wasp is now in its pupal stage and hangs from the spider’s molting web.

 Photo credits: Marcelo O. Gonzaga


“Several studies suggested that sometimes the webs induced by the wasps resemble the webs that unparasitized spiders build just prior to molting,” said Gonzaga. “We combined that observation with a previous discovery that, in one genus, spiders that had just built cocoon webs had unusually high concentrations of ecdysone in their bodies, and predicted that the specificity of the wasp larva’s effects may already be present in the spider’s nervous system, in the form of its specific behavioral responses to the hormone that controls its own molting cycle. By hacking into this system, the wasps ensure the safety of their own offspring at the expense of their host.”

“Now that we have a proposed mechanism, we can ask a new set of questions,” Eberhard says. “Because the lines in spider webs represent precise records of their behavior, we could study “zombification” in unprecedented detail by looking at the lines in cocoon and molting webs. We discovered that both web types vary, and more importantly, that the variations only overlap partially.

“The larvae probably tweak the spider’s molting web construction behavior to gain added protection. The mechanisms by which these additional modifications are obtained may result from differences in the timing or amounts of ecdysone, or modifications in the ecdysone molecules themselves, but they remain to be documented,” Eberhard continued.



Contacts and sources:
Smithsonian Tropical Research Institute


Citation: Evidence that Polysphincta-group wasps (Hymenoptera: Ichneumonidae) use ecdysteroids to manipulate the 
web-construction behaviour of their spider hosts
William G Eberhard, Marcelo O Gonzaga.. Biological Journal of the Linnean Society, 2019; DOI: 10.1093/biolinnean/blz044


Brain Activates Replay to Form Stronger Memories

Why do some memories last and others fade more quickly.  Researchers think they have found the mechanism in the brain that leads to lasting memories, the replay happens in the hippocampus, the memory-processing center of the brain.

Location of the Hippocampus in the Human Brain.

Credit: Wikimedia Commons 

Leuven researchers say they can shed new light on how the brain solidifies important memories through replay and rewards.

A team of scientists at NeuroElectronics Research Flanders (NERF- empowered by imec, KU Leuven and VIB) found that highly demanding and rewarding experiences result in stronger memories. By studying navigation in rats, the researchers traced back the mechanism behind this selective memory enhancement to so-called replay processes in the hippocampus, the memory-processing center of the brain. These important findings provide new insights into one of the most enigmatic brain features: memory consolidation.

When we experience something important, we usually remember it better over time. This enhanced memory can be the result of stronger memory encoding during the experience, or because of memory consolidation that takes place after the experience. For example, experiences that turn out to be very rewarding have been found to lead to stronger and longer-lasting memories.

“One of the ways in which our brains consolidate memories is by mentally reliving the experience,” explains Prof. Fabian Kloosterman, whose research is aimed at unravelling memory processing in the brain. “In biological terms, this boils down to the reactivation or replay of the neuronal activity patterns associated with a certain experience. This replay occurs in hippocampal-cortical brain networks during rest or sleep.” 

Four Memories - Joaquín Martínez de la Vega
File:Cuatro recuerdos- Martínez de la Vega.jpg
Credit: Wikimedia Commons

The question Kloosterman and his team at NERF (empowered by imec, KU Leuven and VIB) set out to answer was whether the positive effect of rewards on hippocampal replay extend beyond the time of the experience itself and thus could further support enhanced memory consolidation.


Rewards and challenges

To find answers, the researchers trained rats to learn two goal locations in a familiar setting. One of the goals was a large reward—nine food pellets—while the other goal location only had a single food pellet on offer as a small reward.

“Perhaps unsurprisingly, we found that rats remembered better the location where they found the large reward,” says Frédéric Michon, PhD student in the Kloosterman lab, who conducted the experiments. “But we also observed that this reward-related effect on memory was strongest when the food pellets were located in places that required more complex memory formation.”​


Replay for better memory

To assess the contribution of replay brain activity after the actual experience, the researchers disrupted this particular signaling network, but only after the rats got a chance to discover the reward locations. Michon: “Mirroring our earlier findings, we observed that memory was impaired only for the highly rewarded locations, and in particular, when the rewards were at challenging locations.”


In sum, the researchers could demonstrate that hippocampal replay, occurring after initial learning, contributes to the consolidation of highly rewarded experiences, and that this effect depends on the difficulty of a task. “A relatively simple experimental setting with rats and food pellets can teach us a lot about memory,” says Kloosterman. “Our results demonstrate that replay contributes to the finely tuned selective consolidation of memories. Such insights could open future opportunities for treatments that help to strengthen memories, and could also help us understand memory decline in diseases such as dementia.”



Contacts and sources:
VIB (the Flanders Institute for Biotechnology)



Citation: Post-learning hippocampal replay selectively reinforces spatial memory for highly rewarded locations
Frédéric Michon, Jyh-Jang Sun, Chae Young Kim, Davide Ciliberti, Fabian Kloosterman. Current Biology, 2019; DOI: 10.1016/j.cub.2019.03.048

Three Genetic Groups Dominate Inner Eurasia Diverse History

Genetically speaking three main groups of people founded the diverse societies that grew up along the area encompassing the Great Silk Road. 

People of the Silk Road, Dunhuang, 9th century.
Credit: Per Honor et Gloria / Wikimedia Commons

Inner Eurasia, including areas of modern-day Armenia, Georgia, Kazakhstan, Moldova, Mongolia, Russia, Tajikistan, Ukraine and Uzbekistan, was once the cross-roads connecting Asia and Europe, and a major intersection for the exchange of culture, trade goods and genes in prehistory and historical periods, including the era of the famous Silk Road.

Researchers combining genetics, archaeology, history and linguistics have gained new insights into the history of inner Eurasia, once a cultural and genetic crossroads connecting Europe and Asia.

An international team of researchers has combined archaeological, historical and linguistic data with genetic information from over 700 newly analyzed individuals to construct a more detailed picture of the history of inner Eurasia than ever before available. In a study published in Nature Ecology & Evolution, they found that the indigenous populations of inner Eurasia are very diverse in their genes, culture and languages, but divide into three groups that stretch across the area in east-west geographic bands.

Children from one of the Tajikistan communities included in the study.

Credit: © Elena Balanovska

This vast area can also be divided into several distinct ecological regions that stretch in largely east-west bands across Inner Eurasia, consisting of the deserts at the southern edge of the region, the steppe in the central part, taiga forests further north, and tundra towards the Arctic region. The subsistence strategies used by indigenous groups in these regions largely correlate with the ecological zones, for example reindeer herding and hunting in the tundra region and nomadic pastoralism on the steppe.

Despite the long and important history of inner Eurasia, details about past migrations and interactions between groups are not always clear, especially in prehistory. “Inner Eurasia is a perfect place to investigate the relationship between environmental conditions and the pattern of human migration and mixture, as well as changes driven by cultural innovations such as the introduction of dairy pastoralism into the steppe,” states Choongwon Jeong of the Max Planck Institute for the Science of Human History, co-first and senior author of the paper. 

Extent of Silk Route/Silk Road. Red is land route and the blue is the sea/water route.
Credit: NASA / Wikimedia Commons


In order to clarify our understanding of some of the nuances of the history of the region, an international team of researchers undertook an ambitious project to use modern and ancient DNA from a broad geographic range and time period, in concert with archaeological, linguistic and historical information, to clarify the relationships between the different populations. “A few ethnic groups were studied previously,” comments Oleg Balanovsky from the Vavilov Institute of General Genetics in Moscow, another co-first author, “but we conducted more than a hundred field trips to study this vast region systematically, and reached communities speaking almost all of the Inner Eurasian languages.”

Three distinct east-west groupings
 
For this study, the researchers analyzed DNA from 763 individuals from across the region as well as reanalyzed the genome-wide data from two ancient individuals from the Botai culture, and compared those results with previously published data from modern and ancient individuals. They found three distinct genetic groupings, which geographically are arranged in east-west bands stretching across the region and correlating generally to ecological zones, where populations within each band share a distinct combination of ancestries in varying proportions.

Geographic locations of the Eneolithic Botai, groups including newly sampled individuals, and nearby groups with published data. The map is overlayed with ecoregional information, divided into 14 biomes downloaded from https://ecoregions2017.appspot.com/(credited to Ecoregions 2017 © Resolve). 

Credit: © Jeong & Balanovsky et. al. 2019. The genetic history of admixture across inner Eurasia. Nature Ecology & Evolution, http://dx.doi.org/10.1038/s41559-019-0878-2.


The northernmost grouping, which they term “forest-tundra”, includes Russians, all Uralic language-speakers, which includes Hungarian, Finnish and Estonian, and Yeniseian-language speakers, of which only one remains today and is spoken in central Siberia. The middle grouping, which they term “steppe-forest”, includes Turkic- and Mongolic-speaking populations from the Volga and the region around the Altai and Sayan mountains, near to where Russia, China, Mongolia and Kazakhstan meet. The southernmost grouping, “southern-steppe”, includes the rest of Turkic- and Mongolic-speaking populations living further south, such as Kazakhs, Kyrgyzs and Uzbeks, as well as Indo-European-speaking Tajiks.

Previously unknown genetic connections revealed

Because the study includes data from a broad time period, it is able to show shifts in ancestry in the past that reveal previously unknown interactions. For example, the researchers found that the southern-steppe populations had a larger genetic component from West and South Asia than the other two groupings. This component is also widespread in the ancient populations of the region since the second half of the first millennium BC, but not found in Central Kazakhstan in earlier periods. This hints at a population movement from the southern-steppe region to the steppe-forest region that was previously unknown.

“Inner Eurasia has functioned as a conduit for human migration and cultural transfer since the first appearance of modern humans in this region. As a result, we observe deep sharing of genes between Western and Eastern Eurasian populations in multiple layers,” explains Jeong. “The opportunity to find direct evidence for the hidden old layers of admixture, which is often difficult to appreciate from present-day populations, is very exciting.”

“We found not only corridors, but also barriers for migrations,” adds Balanovsky. “Some of them separate the historical groups of populations, while others, like the distinct barrier following the Great Caucasus mountain ridge, were obviously shaped by the geographic landscape.”
 
Researchers from the study conducting field work along the Amur River.

Credit: © Yuri Bogunov

Two ancient individuals resequenced in this study originated from the Botai culture in Kazakhstan, where the horse was initially domesticated. Analysis of the Y-chromosome (inherited along the paternal genealogical lines) revealed a genetic lineage which is typical in the Kazakh steppe up to the present day. But analysis of the autosomes, which both parents contribute to their children, show no trace of Botai ancestry left in present-day people, likely due to repeated migrations into the region both from the west and the east since the Bronze Age.

The researchers emphasize that their model of three groupings does not perfectly explain all known populations and that there are examples of both outliers and intermediate groups. “It is important to organize a future study for further sampling of sparsely populated regions between the clines, for example, Central Kazakhstan or East Siberia,” states Johannes Krause, also of the Max Planck Institute for the Science of Human History, and senior author of the paper.



Contacts and sources:
Anne Gibson
Max Planck Institute for the Science of Human History


Citation:The genetic history of admixture across inner Eurasia Choongwon Jeong, Oleg Balanovsky, Elena Lukianova, Nurzhibek Kahbatkyzy, Pavel Flegontov, Valery Zaporozhchenko, Alexander Immel, Chuan-Chao Wang, Olzhas Ixan, Elmira Khussainova, Bakhytzhan Bekmanov, Victor Zaibert, Maria Lavryashina, Elvira Pocheshkhova, Yuldash Yusupov, Anastasiya Agdzhoyan, Sergey Koshel, Andrei Bukin, Pagbajabyn Nymadawa, Shahlo Turdikulova, Dilbar Dalimova, Mikhail Churnosov, Roza Skhalyakho, Denis Daragan, Yuri Bogunov, Anna Bogunova, Alexandr Shtrunov, Nadezhda Dubova, Maxat Zhabagin, Levon Yepiskoposyan, Vladimir Churakov, Nikolay Pislegin, Larissa Damba, Ludmila Saroyants, Khadizhat Dibirova, Lubov Atramentova, Olga Utevska, Eldar Idrisov, Evgeniya Kamenshchikova, Irina Evseeva, Mait Metspalu, Alan K. Outram, Martine Robbeets, Leyla Djansugurova, Elena Balanovska, Stephan Schiffels, Wolfgang Haak, David Reich and Johannes Krause
Nature Ecology & Evolution, DOI: 10.1038/s41559-019-0878-2

Can Nothing at All Be Found?



Bill Fairbank is looking for…nothing.

The Colorado State University professor of physics studies the fundamental matter particles known as neutrinos, and an exceedingly rare instance of radioactive decay in which neutrinos – otherwise present in such decays – are nowhere to be found.

This theorized but never-before-observed process, called “neutrinoless double-beta decay,” would rock the world of particle physics. If discovered, it would solve longstanding mysteries about the basic properties of neutrinos, which are among the most abundant but least understood particles in the universe.

Since 2005, Fairbank’s lab has been part of the international EXO-200 (Enriched Xenon Observatory) scientific collaboration, hunting for neutrinoless double-beta decay using a particle detector filled with super-cold liquid xenon.

The Enriched Xenon Observatory is an experiment in particle physics aiming to detect "neutrino-less double beta decay" using large amounts of xenon isotopically enriched in the isotope 136. A 200-kg detector using liquid Xe is currently being installed at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico. Many research and development efforts are underway for a ton-scale experiment, with the goal of probing new physics and the mass of the neutrino.


Publishing April 29 in the journal Nature, Fairbank’s team has laid the foundation for a single-atom illumination strategy called barium tagging. Their achievement is the first known imaging of single atoms in a solid noble gas.

Barium tagging could prove a key enabling technology for seeing neutrinoless double-beta decay in a future, upgraded experiment called nEXO. Crucially, barium tagging would empower scientists to clearly pinpoint single-atom byproducts of double-beta decay by separating real events from background imposter signals.

The EXO-200 particle detector is half a mile underground in Carlsbad, New Mexico, and is filled with 370 pounds (about 170 kilograms) of isotopically enriched xenon atoms in liquid form. Sometimes, the unstable xenon isotopes undergo radioactive decay, releasing two electrons and two neutrinos, changing the xenon atoms into barium atoms.

If the decay produces just two electrons and a barium atom, it signals that a neutrinoless double-beta decay may have occurred. And this can only occur if the neutrino is its own equal, opposite antiparticle – an outstanding question that scientists would like to answer through these experiments.
Neutrinoless decay would be historic

The confirmation of such a neutrinoless decay would be historic, requiring updates to the Standard Model of Particle Physics. In addition, the measured half-life of the decay would help scientists indirectly measure the absolute masses of neutrinos – a feat never before accomplished. Finally, if neutrinoless double-beta decay does exist, scientists could use that information to learn why the universe has so much matter, but so little antimatter. So far, the EXO-200 detector has produced decay events of the correct energy, but no definitive excess over what’s expected from the measured detector background.

“In EXO-200, we had something like 40 decay events in two years,” Fairbank said. “But we couldn’t tell exactly how many of those, if any, were real.”

Artist's view of nEXO in the Cryopit at SNOlab
Credit: LLNL

Like sifting through piles of identical-looking marbles, distinguishing between the real decay and similar-appearing background events has been a central problem for the researchers. That’s where Fairbank’s barium tagging comes in. If barium tagging is successfully implemented in a later upgrade of the nEXO detector currently being designed, the detector’s sensitivity to neutrinoless double-beta decay could increase by up to a factor of 4. This would be a significant upgrade for the multi-million dollar nEXO experiment. If a positive signal is observed, scientists can use barium tagging to know for sure that they’ve seen the decay they’re looking for.
NSF support

The barium tagging work was supported by the National Science Foundation INSPIRE program.

“It’s amazing to think of how sensitive these experiments are,” said John Gillaspy, a physicist at the National Science Foundation. “In experiments 30 years ago, I found it challenging to look for ‘one in a million’ exotic atoms. This new study searched for atoms that were 10 million times more rare. Physics and chemistry have come a long way. I’m excited to think about what Fairbank and his colleagues may eventually find using this new technique, as it holds the potential to really shake up what we know about the fundamental nature of reality.”

In their Nature publication, Fairbank’s team describes using a cryogenic probe to freeze the barium “daughter” atom – produced by radioactive decay of the isotope xenon-136 – in solid xenon on the end of the probe. Then, they use laser fluorescence to illuminate individual barium atoms within the now-solid xenon.

“Our group was pretty excited when we got images of single barium atoms,” said Fairbank, who has been leading the experiment for several years. Fairbank’s single-atom tagging technique could also be generalized for other applications, with implications for fields including nuclear physics, optical physics and chemistry.

The EXO program is an international collaboration of scientists from institutions in the US, Canada, China, Germany, Russia, South Korea and Switzerland.



Contacts and sources:
Anne Manning
Colorado State University


Citation: Imaging individual barium atoms in solid xenon for barium tagging in nEXO
nEXO Collaboration.. Nature, 2019 DOI: 10.1038/s41586-019-1169-4

Ancient Text Confirmed Star Exploded 2000 Years Ago

In 48 B.C.E. an astronomer in China described a star going nova. It is the oldest record of a stellar blast.  The remnants of the exploded star have been found, confirming the ancient text as the oldest description of an event outside the solar system. 

For the first time, a European research team involving the University of Göttingen has discovered the remains of a nova in a galactic globular cluster. A nova is an explosion of hydrogen on the surface of a star which makes it much brighter.

Near the center of the globular cluster Messier 22, the team of scientists discovered the remains of a nova.

Credit: ESA/Hubble and NASA, F Göttgens (IAG)

 The remains have formed a glowing nebula. The remnant is located near the center of the globular cluster Messier 22 and has recently been observed using modern instruments. The results will be published in the journal Astronomy & Astrophysics.

"The position and brightness of the remains match an entry from 48 BC in an ancient collection of observations by Chinese astronomers," says first author Fabian Göttgens of the Institute for Astrophysics at the University of Göttingen. This is research carried out for his PhD in the Stellar Astrophysics research group lead by Professor Dreizler. "They probably saw the original nova in the same place." This means modern measurements confirm one of the oldest observations of an event outside the solar system.

This Chinese text (marked in orange) from an ancient collection of observations (https://ctext.org/) describes a sighting of the original Nova by Chinese astronomers from the year 48 BC
Credit: The Chinese Text Project https://ctext.org/

Globular clusters are large, spherical clusters of several hundreds of thousands of very old stars that orbit together around their home galaxy. There are 150 known globular clusters orbiting our galaxy, the Milky Way. Messier 22 is one of these star clusters, it lies in the constellation Sagittarius in the direction of the centre of the Milky Way. It was observed together with two dozen other globular clusters with the instrument MUSE at the Very Large Telescope of the ESO in Chile. The MUSE instrument was developed with the participation of the Institute for Astrophysics, which was funded by the BMBF. It does not only produce images, it also simultaneously splits starlight by colour, measuring the brightness of stars as a function of colour. This makes it particularly suitable for finding nebulae that often only glow in a certain colour - usually red.

The newly discovered remains of the nova form a red shining nebula of hydrogen gas and other gases, which has a diameter of about 8,000 times the distance between Earth and Sun. Despite its size, the nebula is relatively light, with a mass about 30 times that of Earth, because the gas was dispersed by the explosion.


Contacts and sources:
Fabian Göttgens
University of Göttingen
Institute for Astrophysics
 
Professor Stefan Dreizler
University of Göttingen
Institute for Astrophysics


Citation: Discovery of an old nova remnant in the Galactic globular cluster M22. Fabian Göttgens et al.  Astronomy & Astrophysics (2019). DOI: 10.1051/0004-6361/201935221, Preprint available: arXiv:1904.11515


Star Made from a Disrupted Dwarf Galaxy

Stars retain the materials of their birthplace. Some stars are made of the residue of material from dwarf galaxies passing larger galaxies.

Small stellar systems like dwarf galaxies are suggested to be the main building blocks of our Galaxy. However, it is unclear how many and what kind of stars in our Galaxy are originated from satellite dwarf galaxies.

This is a star accreted from a disrupted dwarf galaxy.

Credit: Chinese National Astronomy

An international team led by ZHAO Gang, a professor from the National Astronomical Observatories of Chinese Academy of Sciences (NAOC) discovered a chemically peculiar star accreted from a disrupted dwarf galaxy. According to results obtained through the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and Subaru telescope, the star has an unusually low amount of magnesium which is the eighth most abundant element in the universe. 

Meanwhile it contains an excessive amount of heavy elements, such as europium, gold, and uranium. The team reported their findings online in Nature Astronomy on April 29th, 2019.

"Stars preserve chemical information of its birth site. We can distinguish stars formed in the Milky Way from stars formed in dwarf galaxies based on their chemical abundances," says ZHAO who is also the corresponding author of the paper.

The chemical composition of this star that the authors discovered suggests it is originated from a dwarf galaxy which was disrupted by interaction with the Milky Way.

The data was obtained by LAMOST, a spectroscopic survey telescope that is capable to take 4,000 spectra in a single exposure. So far LAMOST has obtained more than 8 million stellar spectra for studies of the formation of the Milky Way. "The massive spectra provided by the LAMOST survey give us a great opportunity to find chemically peculiar stars," says XING Qianfan, Ph.D., first author of this paper. This type of stars can be used to explore the chemical evolution of different stellar systems. 

XING continues, "This newly discovered star with large excesses of heavy elements provides a window for exploring the chemical evolution of disrupted dwarf galaxies. The star formation in dwarf galaxies is relatively slow comparing to larger galaxies, leading to chemical differences among their stellar populations. For instance, the magnesium to iron (Mg/Fe) abundance ratios in stars of dwarf galaxies currently found around the Milky Way are much smaller than those in the majority of stars in the Milky Way."

"This is the first discovery of a star having a very low amount of magnesium and an excessive amount of heavy elements," says co-author LI Haining, Ph.D.

The extreme enhancement of heavy elements of this star suggests this dwarf galaxy was affected by high-yield rapid neutron-capture process (r-process), the dominant process through which elements heavier than iron are formed. Such process may happen during mergers of binary neutron stars in the dwarf galaxy.

"The discovery of this chemically peculiar star is a good start of chemical identification of stars accreted from dwarf galaxies. Such stars will be good tracers for exploring the assemble history of the Milky Way," says ZHAO.

This study is supported by the National Natural Science Foundation of China.




Contacts and sources:
Xu Ang
The National Astronomical Observatories of Chinese Academy of Sciences (NAOC)



Dark Matter Exists: Doubts of Its Existence Removed

A new SISSA study clarifies one of the recent most intriguing controversies on the most widespread form of matter in the Universe

As fascinating as it is mysterious, dark matter is one of the greatest mysteries of astrophysics and cosmology. It is thought to account for 90% of the matter in the Universe, but its existence has been demonstrated only indirectly and recently called into question.

 Credit: SISSA

 New research conducted by SISSA removes the recent doubts on the presence of dark matter within the galaxies, disproving the empirical relations in support of alternative theories. The study, published in The Astrophysical Journal, also offers new insights into understanding the nature of dark matter and its relationship with ordinary matter.

From the expansion of the universe to the movement of stars in the galaxies, the phenomena are many, which, the presence of ordinary matter alone, namely that composed by atoms, is unable to explain. The attractive force it generates is not sufficient. This had led to the theory of the existence of dark matter, namely undetectable, and the idea that galaxies are embedded in its spherical halo.

"Three years ago, a few colleagues of the Case Western Reserve University strongly questioned our understanding of the universe and the in-depth work of many researchers, casting doubt on the existence of dark matter in the galaxies," explains Chiara Di Paolo, a doctoral student of astrophysics at SISSA.

 "Analysing the rotation curves of 153 galaxies, principally the 'classical' spiral kind, they obtained an empirical relationship between total gravitational acceleration of the stars (observed) and the component which we would observe in the presence of sole ordinary matter in the classical Newtonian theory. This empirical relationship which seemed valid in all the galaxies they analysed and at any galactic radius, motivated the explanation of gravitational acceleration without necessarily calling into question dark matter, but involving for example theories of modified gravity such as MOND (Modified Newtonian Dynamics)."

Di Paolo and her collaborators wanted to verify this relationship, analysing the rotation curves of galaxies other than the "classical" spiral kind: 72 galaxies with low surface brightness (LSB) and 34 dwarf disc galaxies. They produced more extended results, finding a relationship, which, besides total gravitational acceleration and its ordinary component, also involves the galactic radius and the morphology of the galaxies.

"We have studied the relationship between total acceleration and its ordinary component in 106 galaxies, obtaining different results from those that had been previously observed," explains Paolo Salucci, professor of astrophysics at SISSA and one of the research authors. "This not only demonstrates the inexactness of the empirical relationship previously described but removes doubts on the existence of dark matter in the galaxies. Furthermore, the new relationship found could provide crucial information on the understanding of the nature of this indefinite component."


Contacts and sources:
Chiara Saviane
Scuola Internazionale Superiore Di Studi Avanzati - SISSA

Citation:


Cosmic dust Reveals Presolar Building Blocks

A team of researchers found a grain of stardust (inset image) that survived the formation of our solar system and analyzed it with instruments sensitive enough to identify single atoms. Measuring one 25,000th of an inch, the carbon-rich graphite grain (red) revealed an embedded speck of oxygen-rich material (blue), two types of stardust that were thought could not form in the same nova eruption. 
A team of researchers found a grain of stardust (inset image) that survived the formation of our solar system and analyzed it with instruments sensitive enough to identify single atoms. Measuring one 25,000th of an inch, the carbon-rich graphite grain (red) revealed an embedded speck of oxygen-rich material (blue), two types of stardust that were thought could not form in the same nova eruption. (Illustration: University of Arizona/Heather Roper)
Illustration: University of Arizona/Heather Roper

The study of a tiny grain of stardust -- older than our solar system -- is shining new light on how planetary systems are formed.

The microbe-sized extraterrestrial particle, which originated from a nova explosion more than 4.5 billion years ago, was discovered inside a meteorite collected in Antarctica by the National Aeronautics and Space Administration (NASA).

Alongside planetary scientists at the University of Arizona (UA), the grain was studied last year at the atomic-level by University of Toronto Engineering professor Jane Howe while she was a senior scientist at Hitachi High Technologies.

"This grain is presolar. It originated before the formation of the sun. It's just amazing to analyze such an anomaly," says Howe.

Using advanced ion and electron microscopes, Howe and the researchers observed the arrangement of carbon atoms and its variants, known as carbon isotope anomalies, and discovered the presolar graphite grain contained oxygen-rich silicates -- something they did not expect to see.

The researchers' observation gives new insights into the conditions of a dying star. It also contradicts the scientific hypothesis that the two types of stardust material, oxygen- and carbon-rich -- which are presolar building blocks in the formation of a solar system -- could not form in the same nova outburst, under the same conditions.

The international collaboration, which includes Howe, planetary scientists, astronomers and material scientists at UA, Washington University in St. Louis, Polytechnic University of Catalonia in Spain, and Hitachi High Technologies in the U.S. and Japan, published their findings today in Nature Astronomy.

“Sometimes research is about satisfying your curiosity. One of the greatest curiosities is how the universe was formed and how life started,” says Howe. “And this weirdo particle showed us something we didn’t know before.”

Howe, who joined U of T Engineering in January 2019, is currently using her electron microscopy expertise to study materials to advance renewable energy, and also plans to expand her work to include meteoritic materials science research.

Dr. Pierre Haenecour (left) of the Lunar and Planetary Laboratory at the University of Arizona and Professor Jane Howe (MSE, ChemE, at right), analyze images of stardust particles with Hitachi’s SU9000 low-voltage STEM/SEM electron microscope. 
Photo courtesy of Maria Schuchardt, University of Arizona



“I thought this research project was really exciting, and I’m a curious person by nature. At the time, it was just part of my job assignment, but now it’s starting to become part of my research portfolio,” says Howe.

Howe hopes to further her collaboration with researchers at UA. In addition, she recently began a collaboration with U of T Professor Kim Tait (Earth Sciences), who is also the senior curator of mineralogy at the Royal Ontario Museum to study its collection of meteorites.

And, in September 2023 when the UA-led NASA OSIRIS-Rex mission returns to Earth after taking samples of carbon-rich asteroid, Bennu, Howe will be among the team of Canadian researchers to analyze its samples.

“This kind of research, it’s part of a much larger debate of how life started on Earth. We all care about who we are and where we came from,” says Howe. “I’m so excited to be part of advancing our knowledge in this.”




Contacts and sources:
Liz Do
University of Toronto Engineering




Strange Corridor Found on Titan



Global maps of Titan show great diversity in terrain types. Rain, seas and a surface of eroding organic material can be found both on Earth and on Saturn's largest moon, Titan. However, on Titan it is methane, not water, that fills the lakes with slushy raindrops and an icy cryo-volcanic corridor  .
-
This figure shows 3 orientations of Titan's globe. Mapped in blue is the icy corridor.

Credit: NASA/JPL-Caltech/Space Science Institute

While trying to find the source of Titan's methane, University of Arizona researcher Caitlin Griffith and her team discovered something unexpected – a long ice feature that wraps nearly half way around Titan.

Griffith, a professor in the UA Lunar and Planetary Laboratory, is the lead author on the paper published today in Nature Astronomy.

On Titan, atmospheric methane molecules are continuously broken apart by sunlight. The resulting atmospheric haze settles to the surface and accumulates as organic sediments, rapidly depleting the atmospheric methane.

This organic veneer is made up of the material of past atmospheres.

There is no obvious source of methane, except from the evaporation of methane from the polar lakes. But Titan's lakes contain only one-third of the methane in Titan's atmosphere and will be exhausted soon by geological time scales.

One theory is that the methane could be supplied by subsurface reservoirs that vent methane into the atmosphere. Prior studies of Titan indicate the presence of a singular region called Sotra, which looks like cryo-volcano, with icy flow features.

Griffith's team set out to study the composition of Titan's surface, partly hoping to find subtle small cryo-volcanos candidates. They analyzed half of Titan's surface and none were detected, but Sotra was found to be exceptional in that it exhibits the strongest ice features.

Yet the major ice feature the researchers found was completely unexpected. It consists of a linear ice corridor that wraps around 40 percent of Titan's circumference.

"This icy corridor is puzzling, because it doesn't correlate with any surface features nor measurements of the subsurface," Griffith said. "Given that our study and past work indicate that Titan is currently not volcanically active, the trace of the corridor is likely a vestige of the past. We detect this feature on steep slopes, but not on all slopes. This suggests that the icy corridor is currently eroding, potentially unveiling presence of ice and organic strata."

The team's analysis also indicates a diversity of organic material in certain regions. These surface deposits are of interest because laboratory simulations of Titan's atmosphere produce biologically interesting compounds such as amino acids.

Griffith analyzed tens of thousands of spectral images taken of the topmost layer of the surface by Cassini's Visible and Infrared Mapping Spectrometer, using a method that enabled the detection of weak surface features.

This feat was accomplished by Griffith's application of the principal components analysis, or PCA. It allowed her to tease out subtle features caused by ice and organic sediments on Titan's surface from the ubiquitous haze and more obvious surface features. Instead of measuring the surface features individually for each pixel in an image, the PCA uses all of the pixels to recognize the main and more subtle signatures.

Griffith's team compared their results with past studies including the Huygens probe, which landed on Titan in 2005. The comparison validated both the technique and the results. Plans are underway to use the technique to explore the poles where methane seas reside.

"Both Titan and Earth followed different evolutionary paths, and both ended up with unique organic-rich atmospheres and surfaces," Griffth said. "But it is not clear whether Titan and Earth are common blueprints of the organic-rich of bodies or two among many possible organic-rich worlds."

A portion of the funding for this research came from NASA space grants.

Image caption: Three orientations of Titan's globe. The icy corridor is mapped in blue. (Photo: Caitlin Griffith/UA Lunar & Planetary Laboratory)






Contacts and sources:
Mikayla Mace
University of Arizona

Caitlin Griffith
UA Lunar and Planetary Laboratory


Citation: A corridor of exposed ice-rich bedrock across Titan’s tropical region Caitlin A. Griffith, Paulo F. Penteado, Jake D. Turner, Catherine D. Neish, Giuseppe Mitri, Nicholas J. Montiel, Ashley Schoenfeld & Rosaly M. C. Lopes Nature Astronomy (2019)  https://www.nature.com/articles/s41550-019-0756-5  http://dx.doi.org/10.1038/s41550-019-0756-5 


New Breed of Rubber Robots Are Coming

It’s time to rethink our conception of robots. No longer the clunky machines of past, today a whole new breed of soft robots is emerging thanks to research being carried out at Jamie Paik’s Reconfigurable Robotics Lab

Paik – a spirited engineer with unfailing energy – is developing folding robots that could assist us not only with everyday tasks, but also with difficult physical maneuvers if placed on our arms and legs. Her soft, flexible and versatile devices are light years away from the machines we see on production lines and in science-fiction movies.

Jamie Paik, the head of EPFL’s Reconfigurable Robotics Lab, presented her reconfigurable robots at the TED2019 conference in Vancouver on 18 April. Her miniature, versatile devices stand to revolutionize the way robots are used.
© Marc Delachaux / 2019 EPFL
Credit: EPFL


Credit: Reconfigurable Robotics Lab - EPFL


“The rigid, powerful robots used in manufacturing are perfect for the preprogrammed environments of production plants – such as to make smartphones or computers,” says Paik. “But if we want devices that can assist us in our everyday lives, they need to be flexible, responsive to change and able to interact with us safely.” For instance, such robots could be used at home for doing the chores, or they could be integrated into our clothing.


Technology that moves with us

Paik’s futuristic vision and insightful work have attracted the attention of TED conference organizers. “One of the organizers attended a talk I gave and then invited me to speak at TED2019, whose topic is ‘Bigger than us.’ I didn’t think twice before accepting – it’s a once-in-a-lifetime opportunity!” says Paik.

This year’s TED conference will take a critical look at the technologies that are changing the world. Former TED speakers include Nobel prize winners and such prominent figures as Steve Jobs and Michelle Obama.

In her talk, Paik will outline her vision of a world where robots are as commonplace as smartphones. “The difference is that the new technology won’t be passive. It will move with us, but we won’t even notice it’s there. The robots will seem invisible,” she says.


Credit: Reconfigurable Robotics Lab - EPFL

Large-scale robot production

So what will these robots actually look like? Paik’s team of researchers is developing a couple of types. The first are robogamis, or folding robots inspired by origami. Equipped with several joints and actuators, they are initially flat, like a credit card, but can be folded into a variety of 3D shapes. Some robogamis, called tribots, can communicate with each other and move by jumping or climbing. And because robogamis can be manufactured in 2D, large-scale production is possible. “These robots have so many joints that even though their individual components may be rigid, they can bend in myriad ways and are completely flexible, like a mesh of yarn,” says Paik.

Paik’s team is also developing “rubber” robots of all shapes and sizes that move using pneumatic actuators. They can mimic human muscles and be connected together to move objects or climb walls. “If we integrate the actuators into clothing, they can receive tactile signals and transmit those signals to a motion device. The system could thus help patients during physical therapy, for example,” says Paik.

In the future, Paik’s robots could handle repetitive, mundane tasks related to housework or gardening – but their potential doesn’t stop there. She is working with the European Space Agency and the Swiss Space Center to study applications for her soft robots in space. “Astronauts often end up wasting time on routine tasks. And since every gram counts when you’re sending a vessel up in space, these soft robots could be an interesting alternative,” she says.

At her TED talk in Vancouver, Paik presented a miniature haptic joystick that provides realistic tactile feedback – a promising technological development for virtual reality applications. The joystick, made of carbon fiber, is also inspired by origami and can be folded up when not in use to become just as flat as a piece of cardboard. The joystick is being marketed by a spin-off of her EPFL lab, Foldaway-Haptics.


A talk for her grandmother

However, preparing for the TED talk is no child’s game. “I’m practicing with a coach who is helping me choose each word carefully. It’s a lot of stress, but it’s also highly stimulating,” she says. And speaking in Vancouver has special meaning for the Canadian-born engineer. “My grandmother, who is 94, lives in Vancouver and will come hear me speak. It’ll be the first time she will see me working. She’s always been my biggest supporter,” says Paik. “She used to say to me: there is nothing boys can do that girls cannot do. And you can do better than anybody. I hope she was right as always.”

Meet Tribot, the Swiss Army knife of robots for rescue missions
More videos: Reconfigurable Robotics Lab RRL

Paik was born in Canada and grew up in Seoul, Tokyo and Vancouver. Her father is a scientist and her mother is a painter. After obtaining Bachelor’s and Master’s degrees in engineering from the University of British Columbia, she went on to earn a PhD at Seoul National University. She conducted her PhD research in association with Samsung Electronics, designing the mechanical arm of a humanoid robot that weighed just 3.7 kg – a record at the time. 

She then completed a post-doc at Pierre and Marie Curie University in Paris, where she developed a simple, intuitive device for endoscopic surgery, called JAiMY. The device assists surgeons with suturing during laparoscopies and was launched on the market in 2011. Paik completed a second post-doc at the Harvard Microrobotics Laboratory where she became familiar with soft robotics. She founded the Reconfigurable Robotics Lab at EPFL’s School of Engineering in January 2012.

 Contacts and sources:
Laure-Anne Pessina
EPFL Reconfigurable Robotics Lab

Concentrated Sunlight Sets Record for Cheap Hydrogen Production

Using concentrated sunlight researchers produced a record amount of clean hydrogen from a low cost system which could run for four years with no maintenance and last 20 years   A prototype is being scaled up. 

Hydrogen will play a key role in reducing our dependence on fossil fuels. It can be sustainably produced by using solar energy to split water molecules. The resulting clean energy can be stored, used to fuel cars or converted into electricity on demand. But making it reliably on a large scale and at an affordable cost is a challenge for researchers. Efficient solar hydrogen production requires rare and expensive materials – for both the solar cells and the catalyst – in order to collect energy and then convert it.

EPFL researchers have created a smart device capable of producing large amounts of clean hydrogen. By concentrating sunlight, their device uses a smaller amount of the rare, costly materials that are required to produce hydrogen, yet it still maintains a high solar-to-fuel efficiency. Their research has been taken to the next scale with a pilot facility installed on the EPFL campus.
Sophia Haussener, Saurabh Tembhurne et Fredy Nandjou© Marc Delachaux / 2019 EPFL
Credit: EPFL

Scientists at EPFL’s Laboratory of Renewable Energy Science and Engineering (LRESE) came up with the idea of concentrating solar irradiation to produce a larger amount of hydrogen over a given area at a lower cost. They developed an enhanced photo-electrochemical system that, when used in conjunction with concentrated solar irradiation and smart thermal management, can turn solar power into hydrogen with a 17% conversion rate and unprecedented power and current density. What’s more, their technology is stable and can handle the stochastic dynamics of daily solar irradiation.

EPFL researchers have created a smart device capable of producing large amounts of clean hydrogen. By concentrating sunlight, their device uses a smaller amount of the rare, costly materials that are required to produce hydrogen, yet it still maintains a high solar-to-fuel efficiency. Their research has been taken to the next scale with a pilot facility installed on the EPFL campus.

Credit: École polytechnique fédérale de Lausanne (EPFL)

The results of their research have just been published in Nature Energy. “In our device, a thin layer of water runs over a solar cell to cool it. The system temperature remains relatively low, allowing the solar cell to deliver better performance,” says Saurabh Tembhurne, a co-author of the study. “At the same time, the heat extracted by the water is transferred to catalysts, thereby improving the chemical reaction and increasing the hydrogen production rate,” adds Fredy Nandjou, a researcher at the LRESE. Hydrogen production is therefore optimized at each step of the conversion process.

The scientists used the LRESE’s unique solar simulator to demonstrate the stable performance of their device. The results from the lab-scale demonstrations were so promising that the device has been upscaled and is now being tested outdoors, on EPFL’s Lausanne campus. The research team installed a 7-meter diameter parabolic mirror that concentrates solar irradiation by a factor of 1,000 and drives the device. The first tests are under way.

Hydrogen stations


The scientists estimate that their system can run for over 30,000 hours – or nearly four years – without any part replacements, and up to 20 years if some parts are replaced every four years. Their solar concentrator turns and follows the sun across the sky in order to maximize its yield. Sophia Haussener, the head of the LRESE and the project lead, explains: “In sunny weather, our system can generate up to 1 kilogram of hydrogen per day, which is enough fuel for a hydrogen-powered car to travel 100 to 150 kilometers.”

For distributed, large-scale hydrogen generation, several concentrator systems could be used together to produce hydrogen at chemical plants or for hydrogen stations. Tembhurne and Haussener are planning to take their technology from the lab to industry with a spin-off company called SoHHytec.


Open source software

Thanks to an open interface, it will be possible to monitor the instantaneous performance of the system.

As part of their research, the scientists also performed a technological and economic feasibility study and developed an open-source software program called SPECDO (Solar PhotoElectroChemical Device Optimization, http://specdo.epfl.ch). This program can help engineers design components for low-cost photoelectrochemical systems for producing solar hydrogen. Additionally, they provided a dynamic benchmarking tool called SPECDC (Solar PhotoElectroChemical Device Comparison), for the comparison and assessment of all photoelectrochemical system demonstrations.
Funding

This research is being funded by the NanoTera project SHINE and the SNFS Starting Grant SCOUTS; the scale-up is being funded by SNSF-Bridge, the Swiss Federal Office of Energy and EPFL.



Contacts and sources:
Ecole Polytechnique Fédérale de Lausanne - EPFL
Citation: A thermally synergistic photo-electrochemical hydrogen generator operating under concentrated solar irradiation.
Tembhurne, Nandjou and Haussener. Nature Energy, 2019 DOI: 10.1038/s41560-019-0373-7

Extraordinary Black Hole System Spraying Misaligned Jets of Plasma at Light Speed

Astronomers have discovered rapidly swinging jets coming from a misaligned black hole system almost 8000 light-years from Earth.

Published in the journal Nature, the research shows jets from V404 Cygni’s black hole behaving in a way never seen before on such short timescales.

An animation of the precessing jets and accretion flow in V404 Cygni narrated by Associate Professor James Miller-Jones of Curtin University and ICRAR. Zooming in from the high-speed plasma clouds observed with our radio telescope, we see the binary system itself. Mass from the star spirals in towards the black hole via an accretion disk, whose inner regions are puffed up by intense radiation. The spinning black hole pulls spacetime (the green gridlines) around with it, causing the inner disk to precess like a spinning top, redirecting the jets as it does so.


Credit: ICRAR

The jets appear to be rapidly rotating with high-speed clouds of plasma—potentially just minutes apart—shooting out of the black hole in different directions.

Lead author Associate Professor James Miller-Jones, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said black holes are some of the most extreme objects in the Universe.

Artist’s impression of the black hole X-ray binary system V404 Cygni as seen from a distance. Bright spots in the jets are detected by our high angular resolution radio imaging, and move away from the black hole in different directions.
Artist's impression of the black hole X-ray binary system V404 Cygni as seen from a distance. Bright spots in the jets are detected by our high angular resolution radio imaging, and move away from the black hole in different directions. Credit: ICRAR
Credit: ICRAR


“This is one of the most extraordinary black hole systems I’ve ever come across,” Associate Professor Miller-Jones said.

“Like many black holes, it’s feeding on a nearby star, pulling gas away from the star and forming a disk of material that encircles the black hole and spirals towards it under gravity.

Artist’s impression of V404 Cygni seen close up. The binary star system consists of a normal star in orbit with a black hole. Material from the star falls towards the black hole and spirals inwards in an accretion disk, with powerful jets being launched from the inner regions close to the black hole.

Credit: ICRAR

“What’s different in V404 Cygni is that we think the disk of material and the black hole are misaligned.

“This appears to be causing the inner part of the disk to wobble like a spinning top and fire jets out in different directions as it changes orientation.

Artist’s impression of the accretion disk around the black hole. During a powerful outburst in 2015, intense radiation caused the inner few thousand kilometres of the accretion disk to “puff up” into a doughnut-shaped structure.

 Credit: ICRAR

V404 Cygni was first identified as a black hole in 1989 when it released a big outburst of jets and radiation.

Astronomers looking at archival photographic plates then found previous outbursts in observations from 1938 and 1956.

Associate Professor Miller-Jones said that when V404 Cygni experienced another very bright outburst in 2015, lasting for two weeks, telescopes around the world tuned in to study what was going on.

“Everybody jumped on the outburst with whatever telescopes they could throw at it,” he said.

“So we have this amazing observational coverage.”

When Associate Professor Miller-Jones and his team studied the black hole, they saw its jets behaving in a way never seen before.

Where jets are usually thought to shoot straight out from the poles of black holes, these jets were shooting out in different directions at different times.

And they were changing direction very quickly—over no more than a couple of hours.

Artist’s impression of jet ejections in V404 Cygni. With our radio telescopes, we see individual bright clouds of plasma that have been ejected from the innermost regions, and redirected by the puffed-up inner accretion disk.

 Credit: ICRAR

Associate Professor Miller-Jones said the change in the movement of the jets was because of the accretion disk—the rotating disk of matter around a black hole.

He said V404 Cygni’s accretion disk is 10 million kilometres wide, and the inner few thousand kilometres was puffed up and wobbling during the bright outburst.

“The inner part of the accretion disk was precessing and effectively pulling the jets around with it,” Associate Professor Miller-Jones said.

“You can think of it like the wobble of a spinning top as it slows down—only in this case, the wobble is caused by Einstein’s theory of general relativity.”

Artist’s impression of twisted space-time around the spinning black hole. The black hole is so dense that it creates a rupture in the very fabric of space time, seen here as the infinitely deep well in the centre. As the black hole spins, it drags spacetime around with it, giving rise to the twisting of the spacetime grid shown here. This leads to the precession of the inner puffed-up accretion disk.

 Credit: ICRAR

The research used observations from the Very Long Baseline Array, a continent-sized radio telescope made up of 10 dishes across the United States, from the Virgin Islands in the Caribbean to Hawaii.

Co-author Alex Tetarenko—a recent PhD graduate from the University of Alberta and currently an East Asian Observatory Fellow working in Hawaii—said the speed the jets were changing direction meant the scientists had to use a very different approach to most radio observations.

“Typically, radio telescopes produce a single image from several hours of observation,” she said.

“But these jets were changing so fast that in a four-hour image we just saw a blur.

“It was like trying to take a picture of a waterfall with a one-second shutter speed.”

Instead, the researchers produced 103 individual images, each about 70 seconds long, and joined them together into a movie.

“It was only by doing this that we were able to see these changes over a very short time period,” Dr Tetarenko said.

Study co-author Dr Gemma Anderson, who is also based at ICRAR’s Curtin University node, said the wobble of the inner accretion disk could happen in other extreme events in the Universe too.

“Anytime you get a misalignment between the spin of a black hole and the material falling in, you would expect to see this when a black hole starts feeding very rapidly,” Dr Anderson said.

Movie made from our high-resolution radio images taken on 22nd June, 2015 with the National Science Foundation’s Very Long Baseline Array. It shows clouds of plasma in the precessing jets moving away from the black hole in different directions. The scale of the images is approximately the size of our Solar System, and time is shown by the clock.
Credit: ICRAR and the University of Alberta

“That could include a whole bunch of other bright, explosive events in the Universe, such as supermassive black holes feeding very quickly or tidal disruption events, when a black hole shreds a star.”


Contacts and sources:
Professor James Miller-Jones
International Centre for Radio Astronomy Research


Citation: A rapidly-changing jet orientation in the stellar-mass black hole V404 Cygni.
James C. A. Miller-Jones, Alexandra J. Tetarenko, Gregory R. Sivakoff, Matthew J. Middleton, Diego Altamirano, Gemma E. Anderson, Tomaso M. Belloni, Rob P. Fender, Peter G. Jonker, Elmar G. Körding, Hans A. Krimm, Dipankar Maitra, Sera Markoff, Simone Migliari, Kunal P. Mooley, Michael P. Rupen, David M. Russell, Thomas D. Russell, Craig L. Sarazin, Roberto Soria & Valeriu Tudose. Nature, 2019 DOI: 10.1038/s41586-019-1152-0