Potential life at the bottom of Earth’s ocean & oceans on other planets

Published on December 4, 2021Written by phys.org

In the strange, dark world of the ocean floor, underwater fissures, called hydrothermal vents, host complex communities of life. These vents belch scorching hot fluids into extremely cold seawater, creating the chemical forces necessary for the small organisms that inhabit this extreme environment to live.

In a newly published study, biogeoscientists Jeffrey Dick and Everett Shock have determined that specific hydrothermal seafloor environments provide a unique habitat where certain organisms can thrive. In so doing, they have opened up new possibilities for life in the dark at the bottom of oceans on Earth, as well as throughout the solar system. Their results have been published in the Journal of Geophysical Research: Biogeosciences.
On land, when organisms get energy out of the food they eat, they do so through a process called cellular respiration, where there is an intake of oxygen and the release of carbon dioxide. Biologically speaking, the molecules in our food are unstable in the presence of oxygen, and it is that instability that is harnessed by our cells to grow and reproduce, a process called biosynthesis.
But for organisms living on the seafloor, the conditions for life are dramatically different.
“On land, in the oxygen-rich atmosphere of Earth, it is familiar to many people that making the molecules of life requires energy,” said co-author Shock of Arizona State University’s School of Earth and Space Exploration and the School of Molecular Sciences. “In stunning contrast, around hydrothermal vents on the seafloor, hot fluids mix with extremely cold seawater to produce conditions where making the molecules of life releases energy.”
In deep-sea microbial ecosystems, organisms thrive near vents where hydrothermal fluid mixes with ambient seawater. Previous research led by Shock found that the biosynthesis of basic cellular building blocks, like amino acids and sugars, is particularly favorable in areas where the vents are composed of ultramafic rock (igneous and meta-igneous rocks with very low silica content), because these rocks produce the most hydrogen.
Besides basic building blocks like amino acids and sugars, cells need to form larger molecules, or polymers, also known as biomacromolecules. Proteins are the most abundant of these molecules in cells, and the polymerization reaction (where small molecules combine to produce a larger biomolecule) itself requires energy in almost all conceivable environments.
“In other words, where there is life, there is water, but water needs to be driven out of the system for polymerization to become favorable,” said lead author Dick, who was a postdoctoral scholar at ASU when this research began and who is currently a geochemistry researcher in the School of Geosciences and Info-Physics at Central South University in Changsha, China. “So, there are two opposing energy flows: release of energy by biosynthesis of basic building blocks, and the energy required for polymerization.”
What Dick and Shock wanted to know is what happens when you add them up: Do you get proteins whose overall synthesis is actually favorable in the mixing zone?
They approached this problem by using a unique combination of theory and data.
From the theoretical side, they used a thermodynamic model for the proteins, called “group additivity,” which accounts for the specific amino acids in protein sequences as well as the polymerization energies. For the data, they used all the protein sequences in an entire genome of a well-studied vent organism called Methanocaldococcus jannaschii.
By running the calculations, they were able to show that the overall synthesis of almost all the proteins in the genome releases energy in the mixing zone of an ultramafic-hosted vent at the temperature where this organism grows the fastest, at around 185 degrees Fahrenheit (85 Celsius). By contrast, in a different vent system that produces less hydrogen (a basalt-hosted system), the synthesis of proteins is not favorable.
“This finding provides a new perspective on not only biochemistry but also ecology because it suggests that certain groups of organisms are inherently more favored in specific hydrothermal environments,” Dick said. “Microbial ecology studies have found that methanogens, of which Methanocaldococcus jannaschii is one representative, are more abundant in ultramafic-hosted vent systems than in basalt-hosted systems. The favorable energetics of protein synthesis in ultramafic-hosted systems are consistent with that distribution.”
For next steps, Dick and Shock are looking at ways to use these energetic calculations across the tree of life, which they hope will provide a firmer link between geochemistry and genome evolution.
“As we explore, we’re reminded time and again that we should never equate where we live as what is habitable to life,” Shock said.
See more here: phys.org
Header image: Le Geologique
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Trees found to reduce land surface area temperatures in cities up to 12°C

Published on November 30, 2021Written by phys.org

A team of researchers with the Institute for Atmospheric and Climate Science, ETH Zurich, has found evidence that indicates that stands of trees can reduce land surface area temperatures in cities up to 12°C.

In their paper published in the journal Nature Communications, the group describes how they analyzed satellite imagery for hundreds of cities across Europe and what they learned.
Prior research has suggested that adding green spaces to cities can help reduce high air temperatures during the warm months—cities are typically hotter than surrounding areas due to the huge expanses of asphalt and cement that absorb heat.
In this new effort, the researchers looked at possible temperature impacts on land surface areas instead of air temperatures.
Such temperatures are not felt as keenly as air temperatures by people in the vicinity because it is below their feet rather than surrounding them.
The work by the team involved analyzing data from satellites equipped with land surface temperature sensors.
In all, the researchers poured over data from 293 cities across Europe, comparing land surface temperatures in parts of cities that were covered with trees with similar nearby urban areas that were not covered with trees.
For comparison purposes, they did the same for rural settings covered in pastures and farmland.
They found urban areas with trees typically had land surface temperatures that were two to four times cooler than similar areas nearby that had no tree cover.
Such differences translated to approximately 0 to 4 K lower than surrounding areas in parts of Southern Europe—in other regions, such as Central Europe, the differences were as high as 8 to 12 K.
Interestingly, the researchers found no such differences in rural areas. And they found no differences for other types of vegetation in the cities.
The researchers note that trees are able keep the ground cooler due to the shade they provide, which suggests they help reduce building surface temperatures in similar ways.
Their work highlights the impact that adding tree cover to urban areas can have.
See more here: phys.org
Header image: Gardening KnowHow
Editor’s note: I am surprised these ‘researchers’ have only just discovered that trees shading the ground keeps the ground cooler than if it was in direct sunlight. I learned that in the Cub Scouts 50 years ago.
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Mystery of ‘high performing’ novel solar cell materials revealed

Published on November 27, 2021Written by phys.org

Researchers from the University of Cambridge have used a suite of correlative, multimodal microscopy methods to visualize, for the first time, why perovskite materials are seemingly so tolerant of defects in their structure. Their findings were published in Nature Nanotechnology.

The most commonly used material for producing solar panels is crystalline silicon, but to achieve efficient energy conversion requires an energy-intensive and time-consuming production process to create the highly ordered wafer structure required.
In the last decade, perovskite materials have emerged as promising alternatives.
The lead salts used to make them are much more abundant and cheaper to produce than crystalline silicon, and they can be prepared in a liquid ink that is simply printed to produce a film of the material. They also show great potential for other optoelectronic applications, such as energy efficient light emitting diodes (LEDs) and X-ray detectors.
The impressive performance of perovskites is surprising. The typical model for an excellent semiconductor is a very ordered structure, but the array of different chemical elements combined in perovskites creates a much ‘messier’ landscape.
This heterogeneity causes defects in the material that lead to nanoscale ‘traps’, which reduce the photovoltaic performance of the devices. But despite the presence of these defects, perovskite materials still show efficiency levels comparable to their silicon alternatives.
In fact, earlier research by the group has shown the disordered structure can actually increase the performance of perovskite optoelectronics, and their latest work seeks to explain why.
Combining a series of new microscopy techniques, the group present a complete picture of the nanoscale chemical, structural and optoelectronic landscape of these materials, that reveals the complex interactions between these competing factors and ultimately, shows which comes out on top.
“What we see is that we have two forms of disorder happening in parallel,” explains Ph.D. student Kyle Frohna, “the electronic disorder associated with the defects that reduce performance, and then the spatial chemical disorder that seems to improve it.
“And what we’ve found is that the chemical disorder—the ‘good’ disorder in this case—mitigates the ‘bad’ disorder from the defects by funneling the charge carriers away from these traps that they might otherwise get caught in.”
In collaboration with Cambridge’s Cavendish Laboratory, the Diamond Light Source synchrotron facility in Didcot and the Okinawa Institute of Science and Technology in Japan, the researchers used several different microscopic techniques to look at the same regions in the perovskite film. They could then compare the results from all these methods to present the full picture of what’s happening at a nanoscale level in these promising new materials.
“The idea is we do something called multimodal microscopy, which is a very fancy way of saying that we look at the same area of the sample with multiple different microscopes and basically try to correlate properties that we pull out of one with the properties we pull out of another one,” says Frohna. “These experiments are time consuming and resource intensive, but the rewards you get in terms of the information you can pull out are excellent.”
The findings will allow the group and others in the field to further refine how perovskite solar cells are made in order to maximize efficiency.
“For a long time, people have thrown the term defect tolerance around, but this is the first time that anyone has properly visualized it to get a handle on what it actually means to be defect tolerant in these materials.
“Knowing that these two competing disorders are playing off each other, we can think about how we effectively modulate one to mitigate the effects of the other in the most beneficial way.”
“In terms of the novelty of the experimental approach, we have followed a correlative multimodal microscopy strategy, but not only that, each standalone technique is cutting edge by itself,” says Miguel Anaya, Royal Academy of Engineering Research Fellow at Cambridge’s Department of Chemical Engineering and Biotechnology
“We have visualized and given reasons why we can call these materials defect tolerant. This methodology enables new routes to optimize them at the nanoscale to, ultimately, perform better for a targeted application. Now, we can look at other types of perovskites that are not only good for solar cells but also for LEDs or detectors and understand their working principles.
“Even more importantly, the set of acquisition tools that we have developed in this work can be extended to study any other optoelectronic material, something that may be of great interest to the broader materials science community.”
“Through these visualizations, we now much better understand the nanoscale landscape in these fascinating semiconductors—the good, the bad and the ugly,” says Sam Stranks, University Assistant Professor in Energy at Cambridge’s Department of Chemical Engineering and Biotechnology.
“These results explain how the empirical optimisation of these materials by the field has driven these mixed composition perovskites to such high performances. But it has also revealed blueprints for design of new semiconductors that may have similar attributes—where disorder can be exploited to tailor performance.”
See more here: phys.org
Header image: Youtube
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301 new extra-solar planets to Kepler’s total count

Published on November 27, 2021Written by phys.org

Scientists recently added a whopping 301 newly validated exoplanets to the total exoplanet tally.

The throng of planets is the latest to join the 4,569 already validated planets orbiting a multitude of distant stars. How did scientists discover such a huge number of planets, seemingly all at once? The answer lies with a new deep neural network called ExoMiner.
Deep neural networks are machine learning methods that automatically learn a task when provided with enough data. ExoMiner is a new deep neural network that leverages NASA’s Supercomputer, Pleiades, and can distinguish real exoplanets from different types of imposters, or “false positives.” Its design is inspired by various tests and properties human experts use to confirm new exoplanets. And it learns by using past confirmed exoplanets and false positive cases.
ExoMiner supplements people who are pros at combing through data and deciphering what is and isn’t a planet. Specifically, data gathered by NASA’s Kepler spacecraft and K2, its follow-on mission. For missions like Kepler, with thousands of stars in its field of view, each holding the possibility to host multiple potential exoplanets, it’s a hugely time-consuming task to pore over massive datasets. ExoMiner solves this dilemma.
“Unlike other exoplanet-detecting machine learning programs, ExoMiner isn’t a black box—there is no mystery as to why it decides something is a planet or not,” said Jon Jenkins, exoplanet scientist at NASA’s Ames Research Center in California’s Silicon Valley. “We can easily explain which features in the data lead ExoMiner to reject or confirm a planet.”
What is the difference between a confirmed and validated exoplanet? A planet is “confirmed,” when different observation techniques reveal features that can only be explained by a planet. A planet is “validated” using statistics—meaning how likely or unlikely it is to be a planet based on the data.
In a paper published in the Astrophysical Journal, the team at Ames shows how ExoMiner discovered the 301 planets using data from the remaining set of possible planets—or candidates—in the Kepler Archive. All 301 machine-validated planets were originally detected by the Kepler Science Operations Center pipeline and promoted to planet candidate status by the Kepler Science Office. But until ExoMiner, no one was able to validate them as planets.
When a planet crosses directly between us and its star, we see the star dim slightly because the planet is blocking out a portion of the light. This is one method scientists use to find exoplanets. They make a plot called a light curve with the brightness of the star versus time. Using this plot, scientists can see what percentage of the star’s light the planet blocks and how long it takes the planet to cross the disk of the star.
The paper also demonstrates how ExoMiner is more precise and consistent in ruling out false positives and better able to reveal the genuine signatures of planets orbiting their parent stars—all while giving scientists the ability to see in detail what led ExoMiner to its conclusion.
“When ExoMiner says something is a planet, you can be sure it’s a planet,” added Hamed Valizadegan, ExoMiner project lead and machine learning manager with the Universities Space Research Association at Ames. “ExoMiner is highly accurate and in some ways more reliable than both existing machine classifiers and the human experts it’s meant to emulate because of the biases that come with human labeling.”
None of the newly confirmed planets are believed to be Earth-like or in the habitable zone of their parent stars. But they do share similar characteristics to the overall population of confirmed exoplanets in our galactic neighborhood.
“These 301 discoveries help us better understand planets and solar systems beyond our own, and what makes ours so unique,” said Jenkins.
As the search for more exoplanets continues—with missions using transit photometry such as NASA’s Transiting Exoplanet Survey Satellite, or TESS, and the European Space Agency’s upcoming PLAnetary Transits and Oscillations of stars, or PLATO, mission—ExoMiner will have more opportunities to prove it’s up to the task.
“Now that we’ve trained ExoMiner using Kepler data, with a little fine-tuning, we can transfer that learning to other missions, including TESS, which we’re currently working on,” said Valizadegan. “There’s room to grow.”
See more here: phys.org
Header image: BBC
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New holographic camera sees the unseen with high precision

Published on November 24, 2021Written by phys.org

Northwestern University researchers have invented a new high-resolution camera that can see the unseen—including around corners and through scattering media, such as skin, fog or potentially even the human skull.

Called synthetic wavelength holography, the new method works by indirectly scattering coherent light onto hidden objects, which then scatters again and travels back to a camera. From there, an algorithm reconstructs the scattered light signal to reveal the hidden objects. Due to its high temporal resolution, the method also has potential to image fast-moving objects, such as the beating heart through the chest or speeding cars around a street corner.
The study was published on Nov. 17 in the journal Nature Communications.
The relatively new research field of imaging objects behind occlusions or scattering media is called non-line-of-sight (NLoS) imaging. Compared to related NLoS imaging technologies, the Northwestern method can rapidly capture full-field images of large areas with submillimeter precision. With this level of resolution, the computational camera could potentially image through the skin to see even the tiniest capillaries at work.
While the method has obvious potential for noninvasive medical imaging, early-warning navigation systems for automobiles and industrial inspection in tightly confined spaces, the researchers believe potential applications are endless.
“Our technology will usher in a new wave of imaging capabilities,” said Northwestern’s Florian Willomitzer, first author of the study. “Our current sensor prototypes use visible or infrared light, but the principle is universal and could be extended to other wavelengths. For example, the same method could be applied to radio waves for space exploration or underwater acoustic imaging. It can be applied to many areas, and we have only scratched the surface.”
Willomitzer is a research assistant professor of electrical and computer engineering at Northwestern’s McCormick School of Engineering. Northwestern co-authors include Oliver Cossairt, associate professor of computer science and electrical and computer engineering, and former Ph.D. student Fengqiang Li. The Northwestern researchers collaborated closely with Prasanna Rangarajan, Muralidhar Balaji and Marc Christensen, all researchers at Southern Methodist University.
Intercepting scattered light
Seeing around a corner versus imaging an organ inside the human body might seem like very different challenges, but Willomitzer said they are actually closely related. Both deal with scattering media, in which light hits an object and scatters in a manner that a direct image of the object can no longer be seen.
“If you have ever tried to shine a flashlight through your hand, then you have experienced this phenomenon,” Willomitzer said. “You see a bright spot on the other side of your hand, but, theoretically, there should be a shadow cast by your bones, revealing the bones’ structure. Instead, the light that passes the bones gets scattered within the tissue in all directions, completely blurring out the shadow image.”
The goal, then, is to intercept the scattered light in order to reconstruct the inherent information about its time of travel to reveal the hidden object. But that presents its own challenge.
“Nothing is faster than the speed of light, so if you want to measure light’s time of travel with high precision, then you need extremely fast detectors,” Willomitzer said. “Such detectors can be terribly expensive.”
Tailored waves
To eliminate the need for fast detectors, Willomitzer and his colleagues merged light waves from two lasers in order to generate a synthetic light wave that can be specifically tailored to holographic imaging in different scattering scenarios.
“If you can capture the entire light field of an object in a hologram, then you can reconstruct the object’s three-dimensional shape in its entirety,” Willomitzer explained. “We do this holographic imaging around a corner or through scatterers—with synthetic waves instead of normal light waves.”
Over the years, there have been many NLoS imaging attempts to recover images of hidden objects. But these methods typically have one or more problems. They either have low resolution, an extremely small angular field of regard, require a time-consuming raster scan or need large probing areas to measure the scattered light signal.
The new technology, however, overcomes these issues and is the first method for imaging around corners and through scattering media that combines high spatial resolution, high temporal resolution, a small probing area and a large angular field of view. This means that the camera can image tiny features in tightly confined spaces as well as hidden objects in large areas with high resolution—even when the objects are moving.
Turning ‘walls into mirrors’
Because light only travels on straight paths, an opaque barrier (such as a wall, shrub or automobile) must be present in order for the new device to see around corners. The light is emitted from the sensor unit (which could be mounted on top of a car), bounces off the barrier, then hits the object around the corner. The light then bounces back to the barrier and ultimately back into the detector of the sensor unit.
“It’s like we can plant a virtual computational camera on every remote surface to see the world from the surface’s perspective,” Willomitzer said.
For people driving roads curving through a mountain pass or snaking through a rural forest, this method could prevent accidents by revealing other cars or deer just out of sight around the bend. “This technique turns walls into mirrors,” Willomitzer said. “It gets better as the technique also can work at night and in foggy weather conditions.”
In this manner, the high-resolution technology also could replace (or supplement) endoscopes for medical and industrial imaging. Instead of needing a flexible camera, capable of turning corners and twisting through tight spaces—for a colonoscopy, for example—synthetic wavelength holography could use light to see around the many folds inside the intestines.
Similarly, synthetic wavelength holography could image inside industrial equipment while it is still running—a feat that is impossible for current endoscopes.
“If you have a running turbine and want to inspect defects inside, you would typically use an endoscope,” Willomitzer said. “But some defects only show up when the device is in motion. You cannot use an endoscope and look inside the turbine from the front while it is running. Our sensor can look inside a running turbine to detect structures that are smaller than one millimeter.”
Although the technology is currently a prototype, Willomitzer believes it will eventually be used to help drivers avoid accidents. “It’s still a long way to go before we see these kinds of imagers built in cars or approved for medical applications,” he said. “Maybe 10 years or even more, but it will come.”
See more here: phys.org
Header image: Florian Willomitzer/Northwestern University
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An ‘earthgrazer’ flew over the U.S., then vanished, NASA says

Published on November 17, 2021Written by phys.org

A space object with an intimidating name—”earthgrazer”—zoomed over Georgia and Alabama this week, offering witnesses a glimpse of something rare, NASA says.

“Earthgrazers” are fireball meteors with a trajectory so shallow that they skim long distances across the upper atmosphere, NASA says.
“Very rarely, they even ‘bounce off’ the atmosphere and head back out into space,” NASA Meteor Watch wrote on Facebook.
The fireball appeared Tuesday, Nov. 9, around 6:30 p.m. Eastern Daylight Time, officials say, and was “detected by three NASA meteor cameras in the region.”
It entered the atmosphere “at a very shallow angle—only 5 degrees from the horizontal.”
In fact, it was flying for so long that NASA had to recalculate its data to determine how far it traveled across the planet.
“The meteor was first seen at an altitude of 55 miles above the Georgia town of Taylorsville, moving northwest at 38,500 miles per hour,” NASA says.
Taylorsville is about 55 miles northwest of downtown Atlanta.
“Its path was so long that our automated software could not handle all the data. So we ran another analysis code this morning (Nov. 10) and discovered that the fireball traveled … a whopping 186 miles through the air,” according to NASA. “The revised calculations put the end point 34 miles above the town of Lutts, in southern Tennessee.”
It was “a rare meteor for those fortunate enough to see it,” NASA officials say.
An overcast sky in the region blocked the view for many people, and also foiled attempts to estimate the size of the rock, officials say.
Scientists believe it was “a small fragment of an asteroid burning up.”
NASA says an uptick in meteor sightings is expected annually between September and November as the planet “passes through a broad stream of debris left by Comet Encke.”
The debris travels as fast as 65,000 mph as it “burns up” in the atmosphere.
See more here: phys.org
Header image: Alchetron
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Confiscated fossil turns out to be exceptional flying reptile

Published on August 30, 2021Written by phys.org

A fossil acquired in a police raid has turned out to be one of the best-preserved flying reptiles ever found, according to a study published August 11, 2021 in the open-access journal PLOS ONE by Victor Beccari of the University of São Paulo and colleagues.

Tapejarids (an Early Cretaceous subgroup of flying reptiles called pterosaurs) are known for their enormous head crests and their abundance in the fossil record of Brazil, but most Brazilian tapejarid fossils preserve only partial remains.
In this study, researchers describe an exceptional tapejarid specimen which includes nearly the entire body, mostly intact and even including remnants of soft tissue alongside the bones, making it the most complete tapejarid skeleton ever found in Brazil.
This fossil belongs to a species called Tupandactylus navigans, and it has a dramatic history. It is preserved across six square-cut limestone slabs which were confiscated during a police raid at Santos Harbour in São Paulo. It is now among the collections of the University of São Paulo, where researchers were able to reunite the slabs and examine the entire fossil, even CT-scanning to reveal the bones concealed within the stone.
This is the first time that paleontologists have been able to study more than just the skull of this species.

Image: Victor Beccari
The description suggests this species had a terrestrial foraging lifestyle, due to its long neck and the proportions of its limbs, as well as its large head crest that could negatively influence long-distance flight. However, the specimen possesses all the necessary adaptation for powered flight, such as the presence of a notarium and a developed muscle anchoring region in the arm bones.
This specimen also has an unusually large crest on its chin, part of its already impressive skull ornamentation. Precisely how all these factors contributed to the flight performance and lifestyle of these animals will be a subject of future research, among the many other questions that can be answered through study of this exceptional fossil.
The authors add: “We described the most complete tapejarid fossil from Brazil, a partially articulated skeleton of Tupandactylus navigans with soft tissue preservation. This specimen brings new insights into the anatomy of this animal and its constraints for flight, arguing for terrestrial foraging ecology.”
See more here: phys.org
Header image: Victor Beccari
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