Friday, August 28, 2020

Meteorite Study Suggests Earth May Have Always Been Wet

Enstatite chondrite meteorites, once considered 'dry,' contain enough water to fill the oceans -- and then some.

A new study finds that Earth’s water may have come from materials that were present in the inner solar system at the time the planet formed — instead of far-reaching comets or asteroids delivering such water. The findings published Aug. 28 in Science suggest that Earth may have always been wet.
 
Researchers from the Centre de Recherches Pétrographiques et Géochimiques (CRPG, CNRS/Université de Lorraine) in Nancy, France, including one who is now a postdoctoral fellow at Washington University in St. Louis, determined that a type of meteorite called an enstatite chondrite contains sufficient hydrogen to deliver at least three times the amount of water contained in the Earth’s oceans, and probably much more.

Enstatite chondrites are entirely composed of material from the inner solar system — essentially the same stuff that made up the Earth originally.

“Our discovery shows that the Earth’s building blocks might have significantly contributed to the Earth’s water,” said lead author Laurette Piani, a researcher at CPRG. “Hydrogen-bearing material was present in the inner solar system at the time of the rocky planet formation, even though the temperatures were too high for water to condense.”

A piece of the meteorite Sahara 97096 (about 10 cm long), an enstatite chondrite.
 (Photo courtesy of Laurette Piani)

The findings from this study are surprising because the Earth’s building blocks are often presumed to be dry. They come from inner zones of the solar system where temperatures would have been too high for water to condense and come together with other solids during planet formation.

The meteorites provide a clue that water didn’t have to come from far away.

“The most interesting part of the discovery for me is that enstatite chondrites, which were believed to be almost ‘dry,’ contain an unexpectedly high abundance of water,” said Lionel Vacher, a postdoctoral researcher in physics in Arts & Sciences at Washington University in St. Louis.

Vacher prepared some of the enstatite chondrites in this study for water analysis while he was completing his PhD at Université de Lorraine. At Washington University, Vacher is working on understanding the composition of water in other types of meteorites.

Enstatite chondrites are rare, making up only about 2 percent of known meteorites in collections.

But their isotopic similarity to Earth make them particularly compelling. Enstatite chondrites have similar oxygen, titanium and calcium isotopes as Earth, and this study showed that their hydrogen and nitrogen isotopes are similar to Earth’s, too. In the study of extraterrestrial materials, the abundances of an element’s isotopes are used as a distinctive signature to identify where that element originated.


“If enstatite chondrites were effectively the building blocks of our planet — as strongly suggested by their similar isotopic compositions — this result implies that these types of chondrites supplied enough water to Earth to explain the origin of Earth’s water, which is amazing!” Vacher said.

The paper also proposes that a large amount of the atmospheric nitrogen — the most abundant component of the Earth’s atmosphere — could have come from the enstatite chondrites.

“Only a few pristine enstatite chondrites exist: ones that were not altered on their asteroid nor on Earth,” Piani said. “In our study we have carefully selected the enstatite chondrite meteorites and applied a special analytical procedure to avoid being biased by the input of terrestrial water.”


Coupling two analytical techniques — conventional mass spectrometry and secondary ion mass spectrometry (SIMS) — allowed researchers to precisely measure the content and composition of the small amounts of water in the meteorites.

Prior to this study, “it was commonly assumed that these chondrites formed close to the sun,” Piani said. “Enstatite chondrites were thus commonly considered ‘dry,’ and this frequently reasserted assumption has probably prevented any exhaustive analyses to be done for hydrogen.”

This work was possible thanks to the national museum collections of meteorites, including those at Field Museum (Chicago, USA), the French National Museum of Natural History (Paris, France), the Japanese National Institute for Polar Research (Tokyo, Japan), the University of New Mexico (Albuquerque, USA), Natural History Museum (Vienna, Austria) and the CEREGE meteoritic collection (Aix en Provence, France).



Contacts and sources:
Talia OglioreWashington University in St. Louis







Hubble Maps Giant Halo Around Andromeda Galaxy


In a landmark study, scientists using NASA’s Hubble Space Telescope have mapped the immense envelope of gas, called a halo, surrounding the Andromeda galaxy, our nearest large galactic neighbor. Scientists were surprised to find that this tenuous, nearly invisible halo of diffuse plasma extends 1.3 million light-years from the galaxy—about halfway to our Milky Way—and as far as 2 million light-years in some directions. This means that Andromeda’s halo is already bumping into the halo of our own galaxy.

This illustration depicts the gaseous halo of the Andromeda galaxy if it could be seen with the naked eye. At a distance of 2.5 million light-years, the majestic spiral Andromeda galaxy is so close to us that it appears as a cigar-shaped smudge of light high in the autumn sky. If its gaseous halo could be seen with the naked eye, it would be about three times the width of the Big Dipper—easily the biggest feature on the nighttime sky. 
purple-hued glow in the night sky over rocky terrain: an illustration of Andromeda's halo
Credits: NASA, ESA, J. DePasquale and E. Wheatley (STScI), and Z. Levay (background image)

They also found that the halo has a layered structure, with two main nested and distinct shells of gas. This is the most comprehensive study of a halo surrounding a galaxy.

“Understanding the huge halos of gas surrounding galaxies is immensely important,” explained co-investigator Samantha Berek of Yale University in New Haven, Connecticut. “This reservoir of gas contains fuel for future star formation within the galaxy, as well as outflows from events such as supernovae. It’s full of clues regarding the past and future evolution of the galaxy, and we’re finally able to study it in great detail in our closest galactic neighbor.”

“We find the inner shell that extends to about a half million light-years is far more complex and dynamic,” explained study leader Nicolas Lehner of the University of Notre Dame in Indiana. “The outer shell is smoother and hotter. This difference is a likely result from the impact of supernova activity in the galaxy’s disk more directly affecting the inner halo.”

A signature of this activity is the team’s discovery of a large amount of heavy elements in the gaseous halo of Andromeda. Heavier elements are cooked up in the interiors of stars and then ejected into space—sometimes violently as a star dies. The halo is then contaminated with this material from stellar explosions.

The Andromeda galaxy, also known as M31, is a majestic spiral of perhaps as many as 1 trillion stars and comparable in size to our Milky Way. At a distance of 2.5 million light-years, it is so close to us that the galaxy appears as a cigar-shaped smudge of light high in the autumn sky. If its gaseous halo could be viewed with the naked eye, it would be about three times the width of the Big Dipper. This would easily be the biggest feature on the nighttime sky.

Through a program called Project AMIGA (Absorption Map of Ionized Gas in Andromeda), the study examined the light from 43 quasars—the very distant, brilliant cores of active galaxies powered by black holes—located far beyond Andromeda. The quasars are scattered behind the halo, allowing scientists to probe multiple regions. Looking through the halo at the quasars’ light, the team observed how this light is absorbed by the Andromeda halo and how that absorption changes in different regions. The immense Andromeda halo is made of very rarified and ionized gas that doesn’t emit radiation that is easily detectable. Therefore, tracing the absorption of light coming from a background source is a better way to probe this material.

This illustration shows the location of the 43 quasars scientists used to probe Andromeda’s gaseous halo. These quasars—the very distant, brilliant cores of active galaxies powered by black holes—are scattered far behind the halo, allowing scientists to probe multiple regions. Looking through the immense halo at the quasars’ light, the team observed how this light is absorbed by the halo and how that absorption changes in different regions. By tracing the absorption of light coming from the background quasars, scientists are able to probe the halo’s material.


Credits: NASA, ESA, and E. Wheatley (STScI)


The researchers used the unique capability of Hubble’s Cosmic Origins Spectrograph (COS) to study the ultraviolet light from the quasars. Ultraviolet light is absorbed by Earth’s atmosphere, which makes it impossible to observe with ground-based telescopes. The team used COS to detect ionized gas from carbon, silicon, and oxygen. An atom becomes ionized when radiation strips one or more electrons from it.

Andromeda’s halo has been probed before by Lehner’s team. In 2015, they discovered that the Andromeda halo is large and massive. But there was little hint of its complexity; now, it’s mapped out in more detail, leading to its size and mass being far more accurately determined.

“Previously, there was very little information—only six quasars—within 1 million light-years of the galaxy. This new program provides much more information on this inner region of Andromeda’s halo,” explained co-investigator J. Christopher Howk, also of Notre Dame. “Probing gas within this radius is important, as it represents something of a gravitational sphere of influence for Andromeda.”

Because we live inside the Milky Way, scientists cannot easily interpret the signature of our own galaxy’s halo. However, they believe the halos of Andromeda and the Milky Way must be very similar since these two galaxies are quite similar. The two galaxies are on a collision course, and will merge to form a giant elliptical galaxy beginning about 4 billion years from now.

Scientists have studied gaseous halos of more distant galaxies, but those galaxies are much smaller on the sky, meaning the number of bright enough background quasars to probe their halo is usually only one per galaxy. Spatial information is therefore essentially lost. With its close proximity to Earth, the gaseous halo of Andromeda looms large on the sky, allowing for a far more extensive sampling.

“This is truly a unique experiment because only with Andromeda do we have information on its halo along not only one or two sightlines, but over 40,” explained Lehner. “This is groundbreaking for capturing the complexity of a galaxy halo beyond our own Milky Way.”

In fact, Andromeda is the only galaxy in the universe for which this experiment can be done now, and only with Hubble. Only with an ultraviolet-sensitive future space telescope will scientists be able to routinely undertake this type of experiment beyond the approximately 30 galaxies comprising the Local Group.

“So Project AMIGA has also given us a glimpse of the future,” said Lehner.

The team’s findings appear in the Aug. 27 edition of The Astrophysical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

Banner image: This illustration depicts the gaseous halo of the Andromeda galaxy if it could be seen with the naked eye. At a distance of 2.5 million light-years, the majestic spiral Andromeda galaxy is so close to us that it appears as a cigar-shaped smudge of light high in the autumn sky. If its gaseous halo could be seen with the naked eye, it would be about three times the width of the Big Dipper—easily the biggest feature on the nighttime sky. Credits: NASA, ESA, J. DePasquale and E. Wheatley (STScI), and Z. Levay (background image)


Contacts and sources:
Claire Andreoli
NASA's Goddard Space Flight Center

Ann Jenkins / Ray Villard
Space Telescope Science Institute

Nicolas Lehner
University of Notre Dame 

250 Million Years Ago Strange Animal Hibernated in Antarctica

Hibernation is a familiar feature on Earth today. Many animals — especially those that live close to or within polar regions — hibernate to get through the tough winter months when food is scarce, temperatures drop and days are dark.

According to new research, this type of adaptation has a long history. In a paper published Aug. 27 in the journal Communications Biology, scientists at the University of Washington and its Burke Museum of Natural History and Culture report evidence of a hibernation-like state in an animal that lived in Antarctica during the Early Triassic, some 250 million years ago.

Life restoration of Lystrosaurus in a state of torpor.
An artist's rendition of an ancient vertebrate called Lystrosaurus
Credit:  Crystal Shin



The creature, a member of the genus Lystrosaurus, was a distant relative of mammals. Antarctica during Lystrosaurus’ time lay largely within the Antarctic Circle, like today, and experienced extended periods without sunlight each winter.

The fossils are the oldest evidence of a hibernation-like state in a vertebrate animal, and indicate that torpor — a general term for hibernation and similar states in which animals temporarily lower their metabolic rate to get through a tough season — arose in vertebrates even before mammals and dinosaurs evolved.

“Animals that live at or near the poles have always had to cope with the more extreme environments present there,” said lead author Megan Whitney, a postdoctoral researcher at Harvard University who conducted this study as a UW doctoral student in biology. “These preliminary findings indicate that entering into a hibernation-like state is not a relatively new type of adaptation. It is an ancient one.”

Lystrosaurus lived during a dynamic period of our planet’s history, arising just before Earth’s largest mass extinction at the end of the Permian Period — which wiped out about 70% of vertebrate species on land — and somehow surviving it. The stout, four-legged foragers lived another 5 million years into the subsequent Triassic Period and spread across swathes of Earth’s then-single continent, Pangea, which included what is now Antarctica.

“The fact that Lystrosaurus survived the end-Permian mass extinction and had such a wide range in the early Triassic has made them a very well-studied group of animals for understanding survival and adaptation,” said co-author Christian Sidor, a UW professor of biology and curator of vertebrate paleontology at the Burke Museum.


A map of Pangea during the Early Triassic, showing the locations of the Antarctic (blue) and South African (orange) Lystrosaurus populations compared in this study.
Credit: Megan Whitney/Christian Sidor

Paleontologists today find Lystrosaurus fossils in India, China, Russia, parts of Africa and Antarctica. These squat, stubby, creatures — most were roughly pig-sized, but some grew 6 to 8 feet long — had no teeth but bore a pair of tusks in the upper jaw, which they likely employed to forage among ground vegetation and dig for roots and tubers, according to Whitney.

Those tusks made Whitney and Sidor’s study possible. Like elephants, Lystrosaurus tusks grew continuously throughout their lives. The cross-sections of fossilized tusks can harbor life-history information about metabolism, growth and stress or strain. Whitney and Sidor compared cross-sections of tusks from six Antarctic Lystrosaurus to cross-sections of four Lystrosaurus from South Africa.


This thin-section of the fossilized tusk from an Antarctic Lystrosaurus shows layers of dentine deposited in rings of growth. The tusk grew inward, with the oldest layers at the edge and the youngest layers near the center, where the pulp cavity would have been. At the top right is a close-up view of the layers, with a white bar highlighting a zone indicative of a hibernation-like state. Scale bar is 1 millimeter.
Credit: Megan Whitney/Christian Sidor

Back in the Triassic, the collection sites in Antarctica were at about 72 degrees south latitude — well within the Antarctic Circle, at 66.3 degrees south. The collection sites in South Africa were more than 550 miles north during the Triassic at 58-61 degrees south latitude, far outside the Antarctic Circle.

The tusks from the two regions showed similar growth patterns, with layers of dentine deposited in concentric circles like tree rings. But the Antarctic fossils harbored an additional feature that was rare or absent in tusks farther north: closely-spaced, thick rings, which likely indicate periods of less deposition due to prolonged stress, according to the researchers.

“The closest analog we can find to the ‘stress marks’ that we observed in Antarctic Lystrosaurus tusks are stress marks in teeth associated with hibernation in certain modern animals,” said Whitney.


In this image of the thin-section of a fossilized tusk from a South African Lystrosaurus, black arrowheads show layers of dentine deposited in layers of growth, with no signs of a hibernation-like state. Scale bar is 0.1 millimeters.
Credit: Megan Whitney/Christian Sidor

The researchers cannot definitively conclude that Lystrosaurus underwent true hibernation —which is a specific, weeks-long reduction in metabolism, body temperature and activity. The stress could have been caused by another hibernation-like form of torpor, such as a more short-term reduction in metabolism, according to Sidor.

Lystrosaurus in Antarctica likely needed some form of hibernation-like adaptation to cope with life near the South Pole, said Whitney. Though Earth was much warmer during the Triassic than today — and parts of Antarctica may have been forested — plants and animals below the Antarctic Circle would still experience extreme annual variations in the amount of daylight, with the sun absent for long periods in winter.

Many other ancient vertebrates at high latitudes may also have used torpor, including hibernation, to cope with the strains of winter, Whitney said. But many famous extinct animals, including the dinosaurs that evolved and spread after Lystrosaurus died out, don’t have teeth that grow continuously.

“To see the specific signs of stress and strain brought on by hibernation, you need to look at something that can fossilize and was growing continuously during the animal’s life,” said Sidor. “Many animals don’t have that, but luckily Lystrosaurus did.”

If analysis of additional Antarctic and South African Lystrosaurus fossils confirms this discovery, it may also settle another debate about these ancient, hearty animals.

“Cold-blooded animals often shut down their metabolism entirely during a tough season, but many endothermic or ‘warm-blooded’ animals that hibernate frequently reactivate their metabolism during the hibernation period,” said Whitney. “What we observed in the Antarctic Lystrosaurus tusks fits a pattern of small metabolic ‘reactivation events’ during a period of stress, which is most similar to what we see in warm-blooded hibernators today.”

If so, this distant cousin of mammals isn’t just an example of a hearty creature. It is also a reminder that many features of life today may have been around for hundreds of millions of years before humans evolved to observe them.

The research was funded by the National Science Foundation.

 
Contacts and sources:
James Urton
University of Washington

Publication:  “Evidence of torpor in the tusks of Lystrosaurus from the Early Triassic of Antarctica” by Whitney MR and Sidor CA. DOI: 10.1038/s42003-020-01207-6






Thursday, August 27, 2020

Wireless Devices Converts Sunlight, CO2 and Water into Fuel

Researchers have developed a standalone device that converts sunlight, carbon dioxide and water into a carbon-neutral fuel, without requiring any additional components or electricity.

The device, developed by a team from the University of Cambridge, is a significant step toward achieving artificial photosynthesis – a process mimicking the ability of plants to convert sunlight into energy. It is based on an advanced ‘photosheet’ technology and converts sunlight, carbon dioxide and water into oxygen and formic acid – a storable fuel that can be either be used directly or be converted into hydrogen.

Dr Qian Wang
Credit:  University of Cambridge,

The results, reported in the journal Nature Energy, represent a new method for the conversion of carbon dioxide into clean fuels. The wireless device could be scaled up and used on energy ‘farms’ similar to solar farms, producing clean fuel using sunlight and water.

Harvesting solar energy to convert carbon dioxide into fuel is a promising way to reduce carbon emissions and transition away from fossil fuels. However, it is challenging to produce these clean fuels without unwanted by-products.

“It’s been difficult to achieve artificial photosynthesis with a high degree of selectivity, so that you’re converting as much of the sunlight as possible into the fuel you want, rather than be left with a lot of waste,” said first author Dr Qian Wang from Cambridge’s Department of Chemistry.

“In addition, storage of gaseous fuels and separation of by-products can be complicated – we want to get to the point where we can cleanly produce a liquid fuel that can also be easily stored and transported,” said Professor Erwin Reisner, the paper’s senior author.

In 2019, researchers from Reisner’s group developed a solar reactor based on an ‘artificial leaf’ design, which also uses sunlight, carbon dioxide and water to produce a fuel, known as syngas. The new technology looks and behaves quite similarly to the artificial leaf but works in a different way and produces formic acid.

While the artificial leaf used components from solar cells, the new device doesn’t require these components and relies solely on photocatalysts embedded on a sheet to produce a so-called photocatalyst sheet. The sheets are made up of semiconductor powders, which can be prepared in large quantities easily and cost-effectively.

In addition, this new technology is more robust and produces clean fuel that is easier to store and shows potential for producing fuel products at scale. The test unit is 20 square centimetres in size, but the researchers say that it should be relatively straightforward to scale it up to several square metres. In addition, the formic acid can be accumulated in solution, and be chemically converted into different types of fuel.

“We were surprised how well it worked in terms of its selectivity – it produced almost no by-products,” said Wang. “Sometimes things don’t work as well as you expected, but this was a rare case where it actually worked better.”

The carbon-dioxide converting cobalt-based catalyst is easy to make and relatively stable. While this technology will be easier to scale up than the artificial leaf, the efficiencies still need to be improved before any commercial deployment can be considered. The researchers are experimenting with a range of different catalysts to improve both stability and efficiency.

The current results were obtained in collaboration with the team of Professor Kazunari Domen from the University of Tokyo, a co-author of the study.

The researchers are now working to further optimise the system and improve efficiency. Additionally, they are exploring other catalysts for using on the device to get different solar fuels.

“We hope this technology will pave the way toward sustainable and practical solar fuel production,” said Reisner.




Contacts and sources:
Sarah Collins
University of Cambridge


Publication: ‘Molecularly engineered photocatalyst sheet for scalable solar formate production from carbon dioxide and water.’  Qian Wang et al.  Nature Energy (2020). DOI: 10.1038/s41560-020-0678-6









First Complete Dinosaur Skeleton Ever Found Is Ready for Its Closeup at Last

The first complete dinosaur skeleton ever identified has finally been studied in detail and found its place in the dinosaur family tree, completing a project that began more than a century and a half ago.

Credit: John Sibbick

The first complete dinosaur skeleton ever identified has finally been studied in detail and found its place in the dinosaur family tree, completing a project that began more than a century and a half ago.

The skeleton of this dinosaur, called Scelidosaurus, was collected more than 160 years ago on west Dorset's Jurassic Coast. The rocks in which it was fossilised are around 193 million years old, close to the dawn of the Age of Dinosaurs.

This remarkable specimen - the first complete dinosaur skeleton ever recovered - was sent to Richard Owen at the British Museum, the man who invented the word dinosaur.

So, what did Owen do with this find? He published two short papers on its anatomy, but many details were left unrecorded. Owen did not reconstruct the animal as it might have appeared in life and made no attempt to understand its relationship to other known dinosaurs of the time. In short, he 're-buried' it in the literature of the time, and so it has remained ever since: known, yet obscure and misunderstood.

Over the past three years, Dr David Norman from Cambridge's Department of Earth Sciences has been working to finish the work which Owen started, preparing a detailed description and biological analysis of the skeleton of Scelidosaurus, the original of which is stored at the Natural History Museum in London, with other specimens at Bristol City Museum and the Sedgwick Museum, Cambridge.

The results of Norman's work, published as four separate studies in the Zoological Journal of the Linnean Society of London, not only reconstruct what Scelidosaurus looked like in life, but reveal that it was an early ancestor of ankylosaurs, the armour-plated 'tanks' of the Late Cretaceous Period.

For more than a century, dinosaurs were primarily classified according to the shape of their hip bones: they were either saurischians ('lizard-hipped') or ornithischians ('bird-hipped').

However, in 2017, Norman and his former PhD students Matthew Baron and Paul Barrett argued that these dinosaur family groupings needed to be rearranged, re-defined and re-named. In a study published in Nature, the researchers suggested that bird-hipped dinosaurs and lizard-hipped dinosaurs such as Tyrannosaurus evolved from a common ancestor, potentially overturning more than a century of theory about the evolutionary history of dinosaurs.

Another fact that emerged from their work on dinosaur relationships was that the earliest known ornithischians first appeared in the Early Jurassic Period. "Scelidosaurus is just such a dinosaur and represents a species that appeared at, or close to, the evolutionary 'birth' of the Ornithischia," said Norman, who is a Fellow of Christ's College, Cambridge. "Given that context, what was actually known of Scelidosaurus? The answer is remarkably little!"

Norman has now completed a study of all known material attributable to Scelidosaurus and his research has revealed many firsts.

"Nobody knew that the skull had horns on its back edge," said Norman. "It had several bones that have never been recognised in any other dinosaur. It's also clear from the rough texturing of the skull bones that it was, in life, covered by hardened horny scutes, a little bit like the scutes on the surface of the skulls of living turtles. In fact, its entire body was protected by skin that anchored an array of stud-like bony spikes and plates."

Now that its anatomy is understood, it is possible to examine where Scelidosaurus sits in the dinosaur family tree. It had been regarded for many decades as an early member of the group that included the stegosaurs, including Stegosaurus with its huge bony plates along its spine and a spiky tail, and ankylosaurs, the armour-plated 'tanks' of the dinosaur era, but that was based on a poor understanding of the anatomy of Scelidosaurus. Now it seems that Scelidosaurus is an ancestor of the ankylosaurs alone.

"It is unfortunate that such an important dinosaur, discovered at such a critical time in the early study of dinosaurs, was never properly described," said Norman. "It has now - at last! - been described in detail and provides many new and unexpected insights concerning the biology of early dinosaurs and their underlying relationships. It seems a shame that the work was not done earlier but, as they say, better late than never."


Contacts and sources:
Sarah Collins
University of Cambridge




Publication: Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships
David B Norman, FLS
Zoological Journal of the Linnean Society, zlaa061, http://dx.doi.org/10.1093/zoolinnean/zlaa061





Everactive Provides 20 Year Sensors for IoT Devices with No Batteries Needed

Many analysts have predicted an explosion in the number of industrial “internet of things” (IoT) devices that will come online over the next decade. Sensors play a big role in those forecasts. Everactive provides an industrial “internet of things” platform built on its battery-free sensors.

Unfortunately, sensors come with their own drawbacks, many of which are due to the limited energy supply and finite lifetime of their batteries.

The startup Everactive uses ultra-low-power chips to run its industrial “internet of things” platform on battery-free sensors.
 Everactive
Credits: Image courtesy of Everactive

Now the startup Everactive has developed industrial sensors that run around the clock, require minimal maintenance, and can last over 20 years. The company created the sensors not by redesigning its batteries, but by eliminating them altogether.

The key is Everactive’s ultra-low-power integrated circuits, which harvest energy from sources like indoor light and vibrations to generate data. The sensors continuously send that data to Everactive’s cloud-based dashboard, which gives users real time insights, analysis, and alerts to help them leverage the full power of industrial IoT devices.

“It’s all enabled by the ultra-low-power chips that support continuous monitoring,” says Everactive Co-Chief Technology Officer David Wentzloff SM ’02, PhD ’07. “Because our source of power is unlimited, we’re not making tradeoffs like keeping radios off or doing something else [limiting] to save battery life.”

Everactive builds finished products on top of its chips that customers can quickly deploy in large numbers. Its first product monitors steam traps, which release condensate out of steam systems. Such systems are used in a variety of industries, and Everactive’s customers include companies in sectors like oil and gas, paper, and food production. Everactive has also developed a sensor to monitor rotating machinery, like motors and pumps, that runs on the second generation of its battery-free chips.

By avoiding the costs and restrictions associated with other sensors, the company believes it’s well-positioned to play a role in the IoT-powered transition to the factory of the future.

“This is technology that’s totally maintenance free, with no batteries, powered by harvested energy, and always connected to the cloud. There’s so many things you can do with that, it’s hard to wrap your head around,” Wentzloff says.

Breaking free from batteries

Wentzloff and his Everactive co-founder and co-CTO Benton Calhoun SM ’02, PhD ’06 have been working on low-power circuit design for more than a decade, beginning with their time at MIT. They both did their PhD work in the lab of Anantha Chandrakasan, who is currently the Vannevar Bush Professor of Electrical Engineering and Computer Science and the dean of MIT’s School of Engineering. Calhoun’s research focused on low-power digital circuits and memory while Wentzloff’s focused on low power radios.

After earning their PhDs, both men became assistant professors at the schools they attended as undergraduates — Wentzloff at the University of Michigan and Calhoun at the University of Virginia — where they still teach today. Even after settling in different parts of the country, they continued collaborating, applying for joint grants and building circuit-based systems that combined their areas of research.

The collaboration was not an isolated incident: The founders have maintained relationships with many of their contacts from MIT.

“To this day I stay in touch with my colleagues and professors,” Wentzloff says. “It’s a great group to be associated with, especially when you talk about the integrated circuit space. It’s a great community, and I really value and appreciate that experience and those connections that have come out of it. That’s far and away the longest impression MIT has left on my career, those people I continue to stay in touch with. We’re all helping each other out.”

Wentzloff and Calhoun’s academic labs eventually created a battery-free physiological monitor that could track a user’s movement, temperature, heart rate, and other signals and send that data to a phone, all while running on energy harvested from body heat.

“That’s when we decided we should look at commercializing this technology,” Wentzloff says.

In 2014, they partnered with semiconductor industry veteran Brendan Richardson to launch the company, originally called PsiKick.

In the beginning, when Wentzloff describes the company as “three guys and a dog in a garage,” the founders sought to reimagine circuit designs that included features of full computing systems like sensor interfaces, processing power, memory, and radio signals. They also needed to incorporate energy harvesting mechanisms and power management capabilities.

“We wiped the slate clean and had a fresh start,” Wentzloff recalls.

The founders initially attempted to sell their chips to companies to build solutions on top of, but they quickly realized the industry wasn’t familiar enough with battery-free chips.

“There’s an education level to it, because there’s a generation of engineers used to thinking of systems design with battery-operated chips,” Wentzloff says.

The learning curve led the founders to start building their own solutions for customers. Today Everactive offers its sensors as part of a wider service that incorporates wireless networks and data analytics.

The company’s sensors can be powered by small vibrations, lights inside a factory as dim as 100 lux, and heat differentials below 10 degrees Fahrenheit. The devices can sense temperature, acceleration, vibration, pressure, and more.

The company says its sensors cost significantly less to operate than traditional sensors and avoid the maintenance headache that comes with deploying thousands of battery-powered devices.

For instance, Everactive considered the cost of deploying 10,000 traditional sensors. Assuming a three-year battery life, the customer would need to replace an average of 3,333 batteries each year, which comes out to more than nine a day.

The next technological revolution

By saving on maintenance and replacement costs, Everactive customers are able to deploy more sensors. That, combined with the near-continuous operation of those sensors, brings a new level of visibility to operations.

“[Removing restrictions on sensor installations] starts to give you a sixth sense, if you will, about how your overall operations are running,” Calhoun says. “That’s exciting. Customers would like to wave a magic wand and know exactly what’s going on wherever they’re interested. The ability to deploy tens of thousands of sensors gets you close to that magic wand.”

With thousands of Everactive’s steam trap sensors already deployed, Wentzloff believes its sensors for motors and other rotating machinery will make an even bigger impact on the IoT market.

Beyond Everactive’s second generation of products, the founders say their sensors are a few years away from being translucent, flexible, and the size of a postage stamp. At that point customers will simply need to stick the sensors onto machines to start generating data. Such ease of installation and use would have implications far beyond the factory floor.

“You hear about smart transportation, smart agriculture, etc.,” Calhoun says. “IoT has this promise to make all of our environments smart, meaning there’s an awareness of what’s going on and use of that information to have these environments behave in ways that anticipate our needs and are as efficient as possible. We believe battery-less sensing is required and inevitable to bring about that vision, and we’re excited to be a part of that next computing revolution.”


Contacts and sources:
Zach Winn
Massachusetts Institute of Technology (MIT)











BMJ: Rigid Social Distancing Rules for COVID-19 Based on Outdated Science

Rules which stipulate a single specific physical distance (1 or 2 metres) between individuals to reduce the spread of covid-19 are based on outdated science and experiences of past viruses, argue researchers in The BMJ today. Rules should better reflect the multiple factors that combine to affect risk, say experts.

Such rules are based on an over-simplistic dichotomy describing viral transfer by either large droplets or small airborne droplets emitted in isolation without accounting for the exhaled air, say Nicholas Jones at the University of Oxford and colleagues.

Credit: Syced - Wikimedia Commons

In reality, transmission is more complex, involving a continuum of droplet sizes and an important role of the exhaled air that carries them, they explain.

Evidence suggests that smaller airborne droplets laden with covid-19 can travel more than 2 metres by activities such as coughing and shouting, and may spread up to 7-8 metres concentrated in exhaled air from an infected person.

As such, they say distancing rules need to take account of the multiple factors that affect risk, including type of activity, indoor versus outdoor settings, level of ventilation and whether face coverings are worn.

Viral load of the emitter, duration of exposure, and susceptibility of an individual to infection are also important, they add.

"This would provide greater protection in the highest risk settings but also greater freedom in lower risk settings, potentially enabling a return towards normality in some aspects of social and economic life," they write.

To facilitate this, they discuss how transmission risk may vary with setting, occupancy level, contact time, and whether face coverings are worn.

For example, in the highest risk situations, such as a crowded bar or nightclub, physical distancing beyond 2 metres and minimising occupancy time should be considered, while less stringent distancing is likely to be adequate in low risk scenarios.

They say further work is needed to examine areas of uncertainty and extend the guide to develop specific solutions to classes of indoor environments occupied at various usage levels.

"Physical distancing should be seen as only one part of a wider public health approach to containing the covid-19 pandemic," they conclude.

"It should be used in combination with other strategies to reduce transmission risk, including hand washing, regular surface cleaning, protective equipment and face coverings where appropriate, strategies of air hygiene, and isolation of affected individuals."


Contacts and sources:
BMJ


Publication: Two metres or one: what is the evidence for physical distancing in covid-19?
Nicholas R Jones, 1 clinical researcher, Zeshan U Qureshi, clinical academic,2, Robert J Temple, medical student3, Jessica P J Larwood, medical student4, Trisha Greenhalgh, professor1,
Lydia Bourouiba, professor5
Author affiliations
1Nuffield Department of Primary Care Health Sciences, University of Oxford, UK
2St Thomas’ Hospital, London, UK
3Somerville College, University of Oxford, Oxford, UK
4St John’s College, University of Oxford, Oxford, UK
5Fluid Dynamics of Disease Transmission Laboratory, Massachusetts Institute of Technology, Cambridge, MA, US
ABMJ 2020; 370 doi: https://doi.org/10.1136/bmj.m3223 (Published 25 August 2020) http://dx.doi.org/10.1136/bmj.m3223






New Observations of Black Hole Devouring a Star Reveal Rapid Disk Formation

First clear confirmation of accretion disk formation in a tidal disruption event without x-ray emissions supports theoretical predictions.

When a star passes too close to a supermassive black hole, tidal forces tear it apart, producing a bright flare of radiation as material from the star falls into the black hole. Astronomers study the light from these “tidal disruption events” (TDEs) for clues to the feeding behavior of the supermassive black holes lurking at the centers of galaxies.

This image from a computer simulation shows the rapid formation of an accretion disk during the disruption of a star by a supermassive black hole. 
tde-simulation-450.jpg
Image credit: Jamie Law-Smith and Enrico Ramirez-Ruiz

New TDE observations led by astronomers at UC Santa Cruz now provide clear evidence that debris from the star forms a rotating disk, called an accretion disk, around the black hole. Theorists have been debating whether an accretion disk can form efficiently during a tidal disruption event, and the new findings, accepted for publication in the Astrophysical Journal and available online, should help resolve that question, said first author Tiara Hung, a postdoctoral researcher at UC Santa Cruz.

“In classical theory, the TDE flare is powered by an accretion disk, producing x-rays from the inner region where hot gas spirals into the black hole,” Hung said. “But for most TDEs, we don’t see x-rays—they mostly shine in the ultraviolet and optical wavelengths—so it was suggested that, instead of a disk, we’re seeing emissions from the collision of stellar debris streams.”

Coauthors Enrico Ramirez-Ruiz, professor of astronomy and astrophysics at UCSC, and Jane Dai at the University of Hong Kong developed a theoretical model, published in 2018, that can explain why x-rays are usually not observed in TDEs despite the formation of an accretion disk. The new observations provide strong support for this model.

“This is the first solid confirmation that accretion disks form in these events, even when we don’t see x-rays,” Ramirez-Ruiz said. “The region close to the black hole is obscured by an optically thick wind, so we don’t see the x-ray emissions, but we do see optical light from an extended elliptical disk.”

Telltale evidence

The telltale evidence for an accretion disk comes from spectroscopic observations. Coauthor Ryan Foley, assistant professor of astronomy and astrophysics at UCSC, and his team began monitoring the TDE (named AT 2018hyz) after it was first detected in November 2018 by the All Sky Automated Survey for SuperNovae (ASAS-SN). Foley noticed an unusual spectrum while observing the TDE with the 3-meter Shane Telescope at UC’s Lick Observatory on the night of January 1, 2019.

A model of ultraviolet and optical emission from the tidal disruption event AT 2018hyz is shown in this schematic diagram. As an accretion disk forms quickly after the TDE, it generates x-ray emission (black arrows) at small radii, which is only visible through the vertical funnel. In other directions, x-rays are reprocessed by the photosphere or wind, powering the ultraviolet and optical emissions. Hydrogen emission is produced at two distinct sites outside of the photosphere: a large elliptical disk (color-coded by velocity to show rotation) joined by the fallback material, and a broad emission line region (BLR) that is likely created by a radiation-driven wind (purple shaded area). 
tde-disk-schematic-450.jpg
 Image credit: Tiara Hung

“My jaw dropped, and I immediately knew this was going to be interesting,” he said. “What stood out was the hydrogen line—the emission from hydrogen gas—which had a double-peaked profile that was unlike any other TDE we’d seen.”

Foley explained that the double peak in the spectrum results from the Doppler effect, which shifts the frequency of light emitted by a moving object. In an accretion disk spiraling around a black hole and viewed at an angle, some of the material will be moving toward the observer, so the light it emits will be shifted to a higher frequency, and some of the material will be moving away from the observer, its light shifted to a lower frequency.

“It’s the same effect that causes the sound of a car on a race track to shift from a high pitch as the car comes toward you to a lower pitch when it passes and starts moving away from you,” Foley said. “If you’re sitting in the bleachers, the cars on one turn are all moving toward you and the cars on the other turn are moving away from you. In an accretion disk, the gas is moving around the black hole in a similar way, and that’s what gives the two peaks in the spectrum.”

The team continued to gather data over the next few months, observing the TDE with several telescopes as it evolved over time. Hung led a detailed analysis of the data, which indicates that disk formation took place relatively quickly, in a matter of weeks after the disruption of the star. The findings suggest that disk formation may be common among optically detected TDEs despite the rarity of double-peaked emission, which depends on factors such as the inclination of the disk relative to observers.

“I think we got lucky with this one,” Ramirez-Ruiz said. “Our simulations show that what we observe is very sensitive to the inclination. There is a preferred orientation to see these double-peak features, and a different orientation to see x-ray emissions.”

He noted that Hung’s analysis of multi-wavelength follow-up observations, including photometric and spectroscopic data, provides unprecedented insights into these unusual events. “When we have spectra, we can learn a lot about the kinematics of the gas and get a much clearer understanding of the accretion process and what is powering the emissions,” Ramirez-Ruiz said.

In addition to Hung, Foley, Ramirez-Ruiz, and other members of the UCSC team, the coauthors of the paper also include scientists at the Niels Bohr Institute in Copenhagen (where Ramirez-Ruiz holds a Niels Bohr Professorship); University of Hong Kong; University of Melbourne, Australia; Carnegie Institution for Science; and Space Telescope Science Institute.

Observations were obtained at Lick Observatory, the W. M. Keck Observatory, the Southern Astrophysical Research (SOAR) telescope, and the Swope Telescope at Las Campanas Observatory in Chile. This work was supported in part by the National Science Foundation, the Gordon and Betty Moore Foundation, the David and Lucile Packard Foundation, and the Heising-Simons Foundation.




Contacts and sources:
Tim Stephens
University of California - Santa Cruz 


Publication: Prompt Accretion Disk Formation in an X-Ray Faint Tidal Disruption Event. Tiara Hung, Ryan J. Foley, Enrico Ramirez-Ruiz, Jane L. Dai, Katie Auchettl, Charles D. Kilpatrick, Brenna Mockler, Jonathan S. Brown, David A. Coulter, Georgios Dimitriadis, Thomas W.-S. Holoien, Jamie A.P. Law-Smith, Anthony L. Piro, Armin Rest, César Rojas-Bravo, Matthew R. Siebert. Astrophysical Journal, 2020 https://arxiv.org/abs/2003.09427





Asia's Hillstream Loaches Study Reveals Keys to Fish Family's Unusual Land-Walking Abilities

A new genetic and morphological study of South Asia’s hillstream loach (Balitoridae) family is shedding new light on the fishes’ unusual land-walking capabilities, including that of the family’s strangest relative — Cryptotora thamicola — a rare, blind cavefish from Thailand with an uncanny ability to walk on land and climb waterfalls using four limbs that move in salamander-like fashion. 

High-resolution computed tomography reconstruction of Cryptotora thamicola.

Credit: Zach Randall, Florida Museum of Natural History

In a study published in the Journal of Morphology, a team of researchers from New Jersey Institute of Technology (NJIT), Florida Museum of Natural History, Louisiana State University and Thailand's Maejo University have successfully pieced together the ancestral relationships that make up the family tree of hillstream loaches (Balitoridae), detailing for the first time a range of unusual pelvic adaptations across the family that have given some of its members an ability to crawl, or even walk as salamanders do, to navigate terrestrial surfaces.

The team’s DNA-based comparative analysis of the fish family, known to currently encompass more than 100 species native to South and Southeast Asia, is the first of its kind to include Cryptotora thamicola — the only living species of fish known to walk on land in a step pattern similar to tetrapods, or four-limbed vertebrates such as reptiles and amphibians.

The results have revealed three dominant variations of pelvic anatomy in the family, notably including key variations of a robust pelvic girdle and elongated sacral rib among many loaches, which researchers expect are central in explaining the different degrees of land-walking behavior exhibited by the fishes. The team says that the family’s modified pelvic features enabling terrestrial locomotion, which were found most pronounced in Cryptotora thamicola, may have been adapted to enhance their odds of survival in rivers and other fast-moving water environments that many Balitoridae inhabit today.


“The modified morphology of these Balitoridae, particularly the enlarged sacral rib connecting the pelvic plate to the vertebral column, is a big part of why studying this family is so exciting,” said Callie Crawford, the study’s corresponding author and Ph.D. candidate at NJIT’s Department of Biological Sciences. “These loaches have converged on a structural requirement to support terrestrial walking not seen in other fishes. What we’ve discovered is three anatomical groupings that have major implications for the biomechanics of terrestrial locomotion of these loaches, and the relationships among these fishes suggest that the ability to adapt to fast-flowing rivers may be what was passed on genetically, more than the specific morphology itself."

“Now that we have revealed a spectrum of pelvic morphologies among these fishes, we can compare the extent of skeletal support with the walking performance in a species,” said Brooke Flammang, the study's lead principal investigator and assistant professor of biology at NJIT. “This will allow us to measure the mechanical contribution of robust hips to terrestrial locomotion.”

Unlike most living fishes that feature pelvic fins located more anteriorly and attached to the pectoral girdle, balitorids typically boast a skeletal connection between the pelvic plate (basipterygium) and the vertebral column via a modified sacral rib and its distal ligament. These modifications are understood to help generate force against the ground useful for navigating land. The most extreme example emerged in 2016 with the discovery of Cryptotora thamicola in the fast-flowing aquatic conditions of the Tham Maelana and Tham Susa karst cave systems in northern Thailand. NJIT researchers then first identified that the rare species used a robust pelvic girdle attached to its vertebral column to walk and climb waterfalls with a salamander-like gait.


(Top left) Cryptotora thamicola; photograph of live fish in dorsal view (photo by Zach Randall); (bottom left) μCT of skeleton in lateral view (by Zach Randall); (right) μCT scan of pelvis in transverse view (by BE Flammang).

Credit: Zach Randall, Florida Museum of Natural History, and BE Flammang, NJIT


“This trait is likely key to helping these fishes avoid being washed away in the fast-flowing environment that they live in,” said Zach Randall, co-author of the paper and biological scientist at Florida Museum of Natural History. “What’s really cool about this paper is that it shows with high detail that robust pelvic girdles are more common than we thought in the hillstream loach family.”

“The sacral ribs allow forces from the fins pressing against the ground to be transferred to the body so that every time the fin pushes down during a step, the body is pushed up and forward,” explained Flammang. “The increased surface area of the more modified sacral ribs also offers more room for muscle attachment, so fishes such as Cryptotora thamicola can rotate their hips during walking, producing a salamander-like gait.”

River Loach Family Factions

To better understand the evolution of the family, the team conducted a broad sampling of μCT-scan data taken from 29 representative specimens, analyzing and comparing skeletal structures, muscle morphology as well as sacral rib shape across 14 of the 16 balitorid genera. The team also sampled genomic datasets of 72 loaches across seven families to reconstruct the evolutionary relationships in the Ballitoridae tree of life. “We were able to use a large survey of museum specimens and CT scanning to incorporate data even from specimens that didn’t have tissue or genetic data intact,” noted Randall.

The results showed that the loaches fall into three distinct morphotypes, which are expected to correlate to how well they are able to maneuver on land: species with a long, narrow rib that meets the pelvic plate; species with a thicker, slightly curved rib meeting the pelvic plate; and species with a robust crested rib interlocking with the pelvic plate. Of the species sampled, eleven fell into the third category with advanced land-walking abilities, such as Cryptotora thamicola, displaying the most robust sacral rib connection between the basipterygium and vertebral column.


Above: Combination image of CT scan segmentations from Cryptotora thamicola (center) and other river loach species showing skeletal and muscular morphological variations adapted for land-walking. Three newly identified morphotypes within the family shown from least modified pelvic anatomy (left) to most (right).

Credit: NJIT, Florida Museum of Natural History, LSU. Segmentations by Callie Crawford.

“Our analysis showed that the morphotypes are not grouped by closely related taxa, but instead appear spread out across the phylogeny. That indicates to us that the extent of the modification of these features is less reflecting shared ancestry and more likely a product of adaptation to the flow regimes of their environments,” explained Crawford. “To better understand how and why these distinct morphotypes developed, we need more knowledge of the habitat of each species, including water flow rates, substrate types and how the rivers and streams change between rainy and dry seasons.”

Crawford and colleagues now aim to further investigate the stability physics and muscular forces at play that allow certain species to push their bodies off their ground as they walk. The team, including a recent Rutgers University graduate, Amani Webber-Schultz, recently completed fieldwork in Thailand earlier this year to collect more balitorid specimens, which they are studying using high-speed videos of the fishes walking.

“This will allow us to study details of their walking kinematics and gain even more insight into how walking performance might change between species with different pelvic morphologies,” said Crawford.

The study was supported by the National Science Foundation’s Understanding the Rules of Life Grant # 1839915 to BE Flammang, P Chakrabarty, and LM Page.


Contacts and sources:
Jesse Jenkins
New Jersey Institute of Technology

Publication: Crawford, C. H., Randall, Z. S., Hart, P. B., Page, L. M., Chakrabarty, P., Suvarnaraksha, A., & Flammang, B. E. (2020) Skeletal and muscular pelvic morphology of hillstream loaches (Cypriniformes: Balitoridae). Journal of Morphology. https://doi.org/10.1002/jmor.21247






Vast Stone Monuments Constructed in Arabia 7,000 Years Ago

The last decade has seen rapid development in the archaeology of Saudi Arabia. Recent discoveries range from early hominin sites hundreds of thousands of years old to sites just a few hundred years old. One enigmatic aspect of the archaeological record of western Arabia is the presence of millions of stone structures, where people have piled rocks to make different kinds of structures, ranging from burial tombs to hunting traps. One enigmatic form consists of vast rectangular shapes. Archaeologists working with the AlUla Royal Commission gave these the name ‘mustatils,’ which is Arabic for rectangle.

View along the length of a mustatil structure, note researchers at far end for scale, image shows character of these structures as two platforms connected by low walls.

Photo: Huw Groucutt

Mustatils only occur in northwest Saudi Arabia. They had been previously recognized from satellite imagery and as they were often covered by younger structures, it had been speculated that they might be ancient, perhaps extending back to the Neolithic.


View from inside the largest mustatil yet identified, stretching for over 600 metres. This is just one of hundreds of examples of this kind of structure.

Credit: Max Planck Institute for the Science of Human History

In this new article led by Dr Huw Groucutt (group leader of the Extreme Events Research Group which is a Max Planck group spanning the Max Planck Institutes for Chemical Ecology, the Science of Human History, and Biogeochemistry) an international team of researchers under the auspices of the Green Arabia Project (a large project headed by Prof. Michael Petraglia from the Department of Archaeology at the Max Planck Institute for the Science of Human History and the Saudi Ministry for Tourism as well as collaborators from multiple Saudi and international institutions) conducted the first every detailed study of mustatils. Through a mixture of field survey and analyzing satellite imagery, the team have considerably extended knowledge on these enigmatic stone structures.

More than one hundred new mustatils have been identified around the southern margins of the Nefud Desert, between the cities of Ha’il and Tayma, joining the hundreds previously identified from studies of Google Earth imagery, particularly in the Khaybar area. The team found that these structures typically consist of two large platforms, connected by parallel long walls, sometimes extending over 600 meters in length. The long walls are very low, had no obvious openings and are located in diverse landscape settings. It is also interesting that little in the way of other archaeology – such as stone tools – was found around the mustatils. Together these factors suggest that the structures were not simply utilitarian entities for something like water or animal storage.

At one locality the team were able to date the construction of a mustatil to 7000 thousand years ago, by radiocarbon dating charcoal from inside one of the platforms. An assemblage of animal bones was also recovered, which included both wild animals and possibly domestic cattle, although it is possible that the latter are wild auroch. At another mustatil the team found a rock with a geometric pattern painted onto it.

"Our interpretation of mustatils is that they are ritual sites, where groups of people met to perform some kind of currently unknown social activities," says Groucutt. "Perhaps they were sites of animal sacrifices, or feasts."

The fact that sometimes several of the structures were built right next to each other may suggest that the very act of their construction was a kind of social bonding exercise. Northern Arabia 7,000 years ago was very different to today. Rainfall was higher, so much of the area was covered by grassland and there were scattered lakes. Pastoralist groups thrived in this environment, yet it would have been a challenging place to live, with droughts a constant risk.

The team's hypothesis is that mustatils were built as a social mechanism to live in this challenging landscape. They may not be the oldest buildings in the world, but they are on a uniquely large scale for this early period, more than two thousand years before pyramids began to be constructed in Egypt. Mustatils offer fascinating insights into how humans have lived in challenging environments and future studies promise to be extremely useful at understanding these ancient societies.






Contacts and sources:

Max Planck Institute for the Science of Human History.

Publication: Monumental landscapes of the Holocene humid period in Northern Arabia: The mustatil phenomenon.
Huw S Groucutt, Paul S Breeze, Maria Guagnin, Mathew Stewart, Nick Drake, Ceri Shipton, Badr Zahrani, Abdulaziz Al Omarfi, Abdullah M Alsharekh, Michael D Petraglia. The Holocene, 2020; 095968362095044 DOI: 10.1177/0959683620950449

Tuesday, August 25, 2020

COVID-19 in Wastewater May Be Serious Threat

Wastewater containing coronaviruses may be a serious threat, according to a new, global study led by researchers from the Zuckerberg Institute for Water Research at Ben-Gurion University of the Negev (BGU).

The new paper, published in Nature Sustainability, by an international collaboration of 35 researchers, evaluates recent studies on coronaviruses in wastewater and previous airborne infectious diseases, including SARS and MERS. The goal is to evaluate potential threats, avenues of research and possible solutions, as well as garner beneficial perspectives for the future.

Credit: CDC / Wikimedia Commons

"There is ample reason to be concerned about how long coronaviruses survive in wastewater and how it impacts natural water sources," says lead author Dr. Edo Bar-Zeev of the BGU Zuckerberg Institute. "Can wastewater contain enough coronaviruses to infect people? The simple truth is that we do not know enough and that needs to be rectified as soon as possible."

Bar-Zeev, and his postdoc student, Anne Bogler, together with other renowned researchers, indicate that sewage leaking into natural watercourses might lead to infection via airborne spray. Similarly, treated wastewater used to fill recreational water facilities, like lakes and rivers, could also become sources of contagion. Lastly, fruits and vegetables irrigated with wastewater that were not properly disinfected could also be an indirect infection route.

The research team recommends immediate, new research to determine the level of potential infection, if any, and how long coronaviruses last in various bodies of water and spray.

"Wastewater treatment plants need to upgrade their treatment protocols and in the near future also advance toward tertiary treatment through micro- and ultra-filtration membranes, which successfully remove viruses," Bar-Zeev and his colleagues say.

Three wastewater/sewage clarifiers at the Kailua Regional Wastewater Treatment Plant in Hawaii. The plant serves most of Kaneohe, Kailua, and MCBH. (Marine Corps Base Hawaii) This picture was taken near ʻAikahi community park with an unmanned aerial system / drone.
Credit: Roen Wainscoat / Wikimedia Commons

At the same time, wastewater can serve as a canary in a coal mine because it can be monitored to track COVID-19 outbreaks. Coronaviruses start showing up in feces before other symptoms like fevers and coughs show up in otherwise asymptomatic people. Regular monitoring, therefore, can give authorities advance warning of hot spots. 

BGU researchers recently completed a pilot study in Ashkelon, Israel using new methodology to detect and trace the presence of the virus and calculate its concentration to pinpoint emerging COVID-19 hotspots. Other BGU researchers are working on developing water nanofiltration technologies.

BGU researchers who participated in this study include: Prof. Amit Gross, Prof. Noam Weisbrod, Dr. Oded Nir, Prof. Osnat Gillor, Prof. Shai Arnon, Dr. Yakir Berchenko, Prof. Zeev Ronen, Prof. Ariel Kushmaro, Prof. Avner Ronen, and Prof. Jacob Moran-Gilad.

Additional researchers from the U.S. were from Yale University, Northwestern University, Drexel University, Temple University, Rice University, and the University of Notre Dame, Illinois. Other participants include researchers from University Limoges, France; Karlsruhe Institute of Technology, Germany; University of Girona, Spain; University of Venice, Italy; ETH Zurich, Switzerland; University College Cork, Ireland; and Tianjin Polytechnic University, China.



Contacts and sources:
Andrew Lavin
American Associates Ben-Gurion University of the Negev  (AABGU)



Publication: Rethinking wastewater risks and monitoring in light of the COVID-19 pandemic Anne Bogler, Aaron Packman, […]Edo Bar-Zeev Nature Sustainability (2020) https://www.nature.com/articles/s41893-020-00605-2 http://dx.doi.org/10.1038/s41893-020-00605-2

Southeast Asia Megadrought to Linked to Drying in Africa and End of Green Sahara



Physical evidence found in caves in Laos helps tell a story about a connection between the end of the Green Sahara - when once heavily vegetated Northern Africa became a hyper-arid landscape - and a previously unknown megadrought that crippled Southeast Asia 4,000 to 5,000 years ago. This
 mid-Holocene event led to major changes in human settlement

In a paper published in Nature Communications, scientists at the University of California, Irvine, the University of Pennsylvania, William Paterson University of New Jersey and other international institutions explain how this major climate transformation led to a shift in human settlement patterns in Southeast Asia, which is now inhabited by more than 600 million people.

To create a paleoclimate record for the study, co-author Kathleen Johnson, UCI associate professor of Earth system science, and other researchers collected stalagmite samples from caves in Northern Laos. The specimens hold geochemical evidence of past climate change in the highly populated Asian monsoon region. 
UCI and international institutions link Southeast Asia megadrought to drying in Africa
Credit: Amy Ellsworth

"In this study, we provide the first proof for a strong link between the end of the Green Sahara and Southeast Asian monsoon failure during the mid- to late Holocene period," said co-author Kathleen Johnson, UCI associate professor of Earth system science. "Our high-resolution and well-dated record suggests a strong connection between Northern Africa and mainland Southeast Asia during this time."

To create a paleoclimate record for the study, Johnson and other researchers gathered stalagmite samples from caves in Northern Laos. In her UCI laboratory, they measured the geochemical properties of the oxygen and carbon isotopes, carbon-14, and trace metals found in the specimens. This helped them verify the occurrence of the drought and extrapolate its impacts on the region.

Johnson said they combined data from the analysis of these stalagmite-derived proxies with a series of idealized climate model simulations - conducted by co-author Francesco Pausata of the University of Quebec in Montreal - in which Saharan vegetation and dust concentrations were altered in a way that permitted them to investigate the ocean-atmosphere feedbacks and teleconnections associated with such an abrupt shift in precipitation.

The modeling experiments suggested that reduced plant growth in the Sahara led to increased airborne dust that acted to cool the Indian Ocean and shift the Walker circulation pattern eastward, causing it to behave in ways similar to modern-day El Niño events. This, ultimately, led to a large reduction in monsoon moisture across Southeast Asia that lasted more than 1,000 years, according to Johnson.

Anthropologists and archaeologists have previously studied the effects of the demise of the Green Sahara, also known as the African humid period, on population centers closer to Western Asia and North Africa, noting the collapse of the Akkadian Empire of Mesopotamia, the de-urbanization of the Indus Civilization (near present-day Pakistan and India) and the spread of pastoralism along the Nile River.

But the link to the origin of the Southeast Asia megadrought and lifestyle pattern shifts in the region had not been previously investigated, according to lead author Michael Griffiths, professor of environmental science at William Paterson University of New Jersey.

"Archaeologists and anthropologists have been studying this event for decades now, in terms of societal adaptations and upheavals, but its exact cause has eluded the scientific community," said Griffiths, who was a National Oceanic and Atmospheric Administration-supported postdoctoral scholar in Johnson's lab and has collaborated with her on this research topic for more than 10 years.

"Results from this work provide a novel and convincing explanation for the origin of the Southeast Asia megadrought and could help us better understand, to varying degrees, the observed societal shifts across many parts of the tropics and extra-tropics," he said.

Johnson carries her caving gear across a river after exiting a cave in Laos, where she has been conducting paleoclimate research since 2010. 
Credit: Serge Caillault

The researchers suggest that the centuries-long megadrought corresponds to the "missing millennia" in Southeast Asia between 4,000 and 6,000 years ago, a time characterized by a noticeable lack of archaeological evidence in interior Southeast Asia compared to earlier and later portions of the Holocene.

They propose that the mid-Holocene megadrought may have been an impetus for mass population movements and the adoption of new, more resilient subsistence strategies - and that it should now be considered as a possible driver for the inception of Neolithic farming in mainland Southeast Asia.

"This is outstanding evidence for the type of climate change that must have affected society, what plants were available, what animals were available," said co-author Joyce White, adjunct professor of anthropology at the University of Pennsylvania. "All of life had to adjust to this very different climate. From an archaeological point of view, this really is a game changer in how we try to understand or reconstruct the middle Holocene period."

The collection of speleothem samples from Laotian caves was made possible by Johnson's collaboration since 2010 with the Middle Mekong Archaeological Project, managed by White, a consulting scholar at the University of Pennsylvania Museum of Archaeology and Anthropology. This project, which also involved researchers from Oxford University and Northumbria University in the United Kingdom, Los Alamos National Laboratory, and the University of New Mexico, was funded by the National Science Foundation, NOAA, the Swedish Research Council and a grant from the Henry Luce Foundation to the Penn Museum.




Contacts and sources:
Brian Bell
University of California, Irvine

Publication: http://dx.doi.org/10.1038/s41467-020-17927-6 






Are Antivitamins the New Antibiotics?

Antibiotics are among the most important discoveries of modern medicine and have saved millions of lives since the discovery of penicillin almost 100 years ago. Many diseases caused by bacterial infections – such as pneumonia, meningitis or septicaemia – are successfully treated with antibiotics. However, bacteria can develop resistance to antibiotics which then leaves doctors struggling to find effective treatments. 

First author Dr. Rabe von Pappenheim examines protein crystals of a bacterial enzyme that was "poisoned" with an antivitamin.

Credit: Lisa-Marie Funk


Particularly problematic are pathogens which develop multi-drug resistance and are unaffected by most antibiotics. This leads to severe disease progression in affected patients, often with a fatal outcome. Scientists all over the world are therefore engaged in the search for new antibiotics. Researchers at the University of Göttingen and the Max Planck Institute for Biophysical Chemistry Göttingen have now described a promising new approach involving “antivitamins” to develop new classes of antibiotics. The results were published in the journal Nature Chemical Biology.

Antivitamins are substances that inhibit the biological function of a genuine vitamin. Some antivitamins have a similar chemical structure to those of the actual vitamin whose action they block or restrict. For this study, Professor Kai Tittmann’s team from the Göttingen Center for Molecular Biosciences at the University of Göttingen worked together with Professor Bert de Groot’s group from the Max Planck Institute for Biophysical Chemistry Göttingen and Professor Tadgh Begley from Texas A&M University (USA). 

Together they investigated the mechanism of action at the atomic level of a naturally occurring antivitamin of vitamin B1. Some bacteria are able to produce a toxic form of this vital vitamin B1 to kill competing bacteria. This particular antivitamin has only a single atom in addition to the natural vitamin in a seemingly unimportant place and the exciting research question was why the action of the vitamin was still prevented or “poisoned”.

Tittmann's team used high-resolution protein crystallography to investigate how the antivitamin inhibits an important protein from the central metabolism of bacteria. The researchers found that the "dance of the protons", which can normally be observed in functioning proteins, almost completely ceases to function and the protein no longer works. "Just one extra atom in the antivitamin acts like a grain of sand in a complex gear system by blocking its finely tuned mechanics," explains Tittmann. It is interesting to note that human proteins are able to cope relatively well with the antivitamin and continue working. 

The chemist de Groot and his team used computer simulations to find out why this is so. "The human proteins either do not bind to the antivitamin at all or in such a way that they are not 'poisoned'," says the Max Planck researcher. The difference between the effects of the antivitamin on bacteria and on human proteins opens up the possibility of using it as an antibiotic in the future and thus creating new therapeutic alternatives.


The research project was funded by the German Research Foundation (DFG).



Contacts and sources:
Professor Kai Tittmann
University of Göttingen
Molecular Enzymology Group


Professor Bert de Groot
Max Planck Institute for Biophysical Chemistry
Computational Biomolecular Dynamics Research Group


Publication: Structural basis for antibiotic action of the B1 antivitamin 2′-methoxy-thiamine. Fabian Rabe von Pappenheim, Matteo Aldeghi, Brateen Shome, Tadhg Begley, Bert L. de Groot, Kai Tittmann. Nature Chemical Biology, 2020; DOI: 10.1038/s41589-020-0628-4

A.I. Could Use ‘Sefies’ To Detect Heart Disease



Sending a “selfie” to the doctor could be a cheap and simple way of detecting heart disease, according to the authors of a new study published today (Friday) in the European Heart Journal [1].

The study is the first to show that it’s possible to use a deep learning computer algorithm to detect coronary artery disease (CAD) by analysing four photographs of a person’s face.

File:Mike Gruntman selfie.jpg
Credit: Mike Gruntman / Wikimedia Commons

Although the algorithm needs to be developed further and tested in larger groups of people from different ethnic backgrounds, the researchers say it has the potential to be used as a screening tool that could identify possible heart disease in people in the general population or in high-risk groups, who could be referred for further clinical investigations.

“To our knowledge, this is the first work demonstrating that artificial intelligence can be used to analyse faces to detect heart disease. It is a step towards the development of a deep learning-based tool that could be used to assess the risk of heart disease, either in outpatient clinics or by means of patients taking ‘selfies’ to perform their own screening. This could guide further diagnostic testing or a clinical visit,” said Professor Zhe Zheng, who led the research and is vice director of the National Center for Cardiovascular Diseases and vice president of Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People’s Republic of China.

He continued: “Our ultimate goal is to develop a self-reported application for high risk communities to assess heart disease risk in advance of visiting a clinic. This could be a cheap, simple and effective of identifying patients who need further investigation. However, the algorithm requires further refinement and external validation in other populations and ethnicities.”

It is known already that certain facial features are associated with an increased risk of heart disease. These include thinning or grey hair, wrinkles, ear lobe crease, xanthelasmata (small, yellow deposits of cholesterol underneath the skin, usually around the eyelids) and arcus corneae (fat and cholesterol deposits that appear as a hazy white, grey or blue opaque ring in the outer edges of the cornea). However, they are difficult for humans to use successfully to predict and quantify heart disease risk.

Prof. Zheng, Professor Xiang-Yang Ji, who is director of the Brain and Cognition Institute in the Department of Automation at Tsinghua University, Beijing, and other colleagues enrolled 5,796 patients from eight hospitals in China to the study between July 2017 and March 2019. The patients were undergoing imaging procedures to investigate their blood vessels, such as coronary angiography or coronary computed tomography angiography (CCTA). They were divided randomly into training (5,216 patients, 90%) or validation (580, 10%) groups.

Trained research nurses took four facial photos with digital cameras: one frontal, two profiles and one view of the top of the head. They also interviewed the patients to collect data on socioeconomic status, lifestyle and medical history. Radiologists reviewed the patients’ angiograms and assessed the degree of heart disease depending on how many blood vessels were narrowed by 50% or more (≥ 50% stenosis), and their location. This information was used to create, train and validate the deep learning algorithm.

The researchers then tested the algorithm on a further 1,013 patients from nine hospitals in China, enrolled between April 2019 and July 2019. The majority of patients in all the groups were of Han Chinese ethnicity.

They found that the algorithm out-performed existing methods of predicting heart disease risk (Diamond-Forrester model and the CAD consortium clinical score). In the validation group of patients, the algorithm correctly detected heart disease in 80% of cases (the true positive rate or ‘sensitivity’) and correctly detected heart disease was not present in 61% of cases (the true negative rate or ‘specificity’). In the test group, the sensitivity was 80% and specificity was 54%.

Prof. Ji said: “The algorithm had a moderate performance, and additional clinical information did not improve its performance, which means it could be used easily to predict potential heart disease based on facial photos alone. The cheek, forehead and nose contributed more information to the algorithm than other facial areas. However, we need to improve the specificity as a false positive rate of as much as 46% may cause anxiety and inconvenience to patients, as well as potentially overloading clinics with patients requiring unnecessary tests.”

As well as requiring testing in other ethnic groups, limitations of the study include the fact that only one centre in the test group was different to those centres which provided patients for developing the algorithm, which may further limit its generalisabilty to other populations.

In an accompanying editorial [2], Charalambos Antoniades, Professor of Cardiovascular Medicine at the University of Oxford, UK, and Dr Christos Kotanidis, a DPhil student working under Prof. Antoniades at Oxford, write: “Overall, the study by Lin et al. highlights a new potential in medical diagnostics……The robustness of the approach of Lin et al. lies in the fact that their deep learning algorithm requires simply a facial image as the sole data input, rendering it highly and easily applicable at large scale.”

They continue: “Using selfies as a screening method can enable a simple yet efficient way to filter the general population towards more comprehensive clinical evaluation. Such an approach can also be highly relevant to regions of the globe that are underfunded and have weak screening programmes for cardiovascular disease. A selection process that can be done as easily as taking a selfie will allow for a stratified flow of people that are fed into healthcare systems for first-line diagnostic testing with CCTA. Indeed, the ‘high risk’ individuals could have a CCTA, which would allow reliable risk stratification with the use of the new, AI-powered methodologies for CCTA image analysis.”

They highlight some of the limitations that Prof. Zheng and Prof. Ji also include in their paper. These include the low specificity of the test, that the test needs to be improved and validated in larger populations, and that it raises ethical questions about “misuse of information for discriminatory purposes. Unwanted dissemination of sensitive health record data, that can easily be extracted from a facial photo, renders technologies such as that discussed here a significant threat to personal data protection, potentially affecting insurance options. Such fears have already been expressed over misuse of genetic data, and should be extensively revisited regarding the use of AI in medicine”.

The authors of the research paper agree on this point. Prof. Zheng said: “Ethical issues in developing and applying these novel technologies is of key importance. We believe that future research on clinical tools should pay attention to the privacy, insurance and other social implications to ensure that the tool is used only for medical purposes.”

Prof. Antoniades and Dr. Kotanidis also write in their editorial that defining CAD as ≥ 50% stenosis in one major coronary artery “may be a simplistic and rather crude classification as it pools in the non-CAD group individuals that are truly healthy, but also people who have already developed the disease but are still at early stages (which might explain the low specificity observed)”.


Contacts and sources:
Emma Mason
European Society of Cardiology

Publication: Feasibility of using deep learning to detect coronary artery disease based on facial photo.
Shen Lin, Zhigang Li, Bowen Fu, Sipeng Chen, Xi Li, Yang Wang, Xiaoyi Wang, Bin Lv, Bo Xu, Xiantao Song, Yao-Jun Zhang, Xiang Cheng, Weijian Huang, Jun Pu, Qi Zhang, Yunlong Xia, Bai Du, Xiangyang Ji, Zhe Zheng. European Heart Journal, 2020; DOI: 10.1093/eurheartj/ehaa640

Selfies in cardiovascular medicine: welcome to a new era of medical diagnostics. Christos P. Kotanidis, Charalambos Antoniades. European Heart Journal, 2020; DOI: 10.1093/eurheartj/ehaa608