Sunday, August 01, 2021

Spatial relationship between damaged understory and felled trees in a shelterwood forest

SHINSHU UNIVERSITY

The shelterwood forest system is a natural regeneration method of forest management that supplies the next generation of trees from overstory tree seeds without planting. This method lowers the cost of forest management by reducing the need for artificial reforestation through planting. This means that the understory trees must be preserved from felled trees during harvest.

However, protection of understory trees reduces harvesting efficiency, and thus increases the cost of logging. To evaluate whether the conservation of understory trees is commensurate with the increase in harvesting costs, it is necessary to quantitatively clarify the relationship between removing the overstory trees and the emergence pattern of the understory loss. A research group led by Dai Otsuka of Shinshu University's Faculty of Agriculture has proposed a model to measure such damage to the understory spatial distribution.

Researcher Otsuka states that the group was able to come to a simple but clear conclusion that, "felled trees should be worked on so they do not come into contact with conservation targets." The group counted the number of understory trees before and after final cutting, as well as the extent of damage to the trees per spatial grid. Geographic Information System was used to reproduce the felling direction and physical contact between the harvested trees and understory trees. Logistic regression was performed using the extracted frequencies of physical contact as explanatory variables and variables important for reproducing the spatial pattern of the damaged understory were selected.

This method of avoiding damage to the understory has a low barrier to entry for forest management. The research made clear that widely assumed ideas from the field are not wrong. Through a real damage model, forest owners can predict in advance potential losses for harvesting. This will be useful especially in natural renewal operations.

In upcoming research projects, Otsuka hopes to minimize damage to understory in areas targeted in this paper. He hopes to also clarify if natural renewal operations are cost-effective or disadvantageous compared to general clear-cutting, which requires the cost of artificial planting.

This study was supported by the Japan Society for the Promotion of Science Grant 15H04508 and 20H03023.

For more information, please read Spatial relationship between damaged understory and felled trees during the final cutting in a shelterwood forest in the International Journal of Forest Engineering

CAPTION

The forest before harvest.

CREDIT

Dai Ostuka, Shinshu University

JOURNAL

International Journal of Forest Engineering

DOI

10.1080/14942119.2021.1943801

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Spatial relationship between damaged understory and felled trees during the final cutting in a shelterwood forest

ARTICLE PUBLICATION DATE

1-Jul-2021

Disclaimer: AAAS an

SwRI scientists help identify water vapor in atmosphere of icy Jupiter moon

Ganymede’s atmospheric composition varies significantly on day, night sides

Peer-Reviewed Publication

SOUTHWEST RESEARCH INSTITUTE

Juno Ganymede flyby — IMAGE: USING HUBBLE SPACE TELESCOPE DATASETS AND COMPARING THEM TO THE EXPECTED VALUES OF ATMOSPHERIC EMISSIONS, SOUTHWEST RESEARCH INSTITUTE SCIENTISTS PLAYED A CRUCIAL ROLE IN THIS DISCOVERY OF WATER VAPOR IN THE ATMOSPHERE OF JUPITER’S ICY MOON GANYMEDE, SHOWN HERE IN A RECENT IMAGE CAPTURED BY THE JUNO SPACECRAFT. view more
CREDIT: NASA/JPL-CALTECH/SWRI/MSSS/KEVIN M. GILL

SAN ANTONIO — July 26, 2021 — Using spectral images from the Hubble Space Telescope (HST), a team of scientists led by Dr. Lorenz Roth of the KTH Royal Institute of Technology in Stockholm, Sweden, has determined that water vapor forms a large fraction of the atmosphere of Jupiter’s icy moon Ganymede. Southwest Research Institute scientists played a crucial role in this discovery, looking at the HST datasets and comparing them to the expected values of atmospheric emissions.

Ganymede’s atmosphere is produced by charged particle erosion and sublimation of its icy surface. Sublimation occurs when an ice changes directly into a gas without first turning into a liquid. Previous far-ultraviolet observations found both molecular oxygen (O2) and atomic oxygen (O) in the moon’s atmosphere but did not detect the water scientists had expected to find. The new observations find that H2O is more abundant than oxygen near the subsolar point, when the Sun is at its zenith, directly overhead, where the Sun's rays strike the planet most intensely.

“Sublimated water vapor at high noon on Ganymede, where the surface is relatively warm, is likely a key feature of the tenuous atmospheres of Jupiter’s icy moons,” said SwRI’s Dr. Kurt Retherford, a co-author of the Nature Astronomy paper describing this research. “As we prepare to launch NASA’s Ultraviolet Spectrograph (UVS) instrument, built and led by SwRI, aboard the European Space Agency’s (ESA’s) Jupiter Icy Moons Explorer (JUICE) mission next year, this new understanding of Ganymede’s atmosphere will let us better plan our observations and enhance our science return.”

Scientists expect that molecular oxygen is globally the most abundant constituent in Ganymede’s atmosphere, as it is gravitationally bound, stable and less likely to react with surface materials. The lighter products of the ice surface erosion, atomic hydrogen (H) and hydrogen gas (H2), escape quickly and are less abundant. Ganymede’s surface temperatures range from 80 Kelvin (-315 F) to perhaps as high as 150 K (-190 F), but water molecules only sublimate and fly off where it’s hotter than 110 K (-260 F) and get stuck frozen on colder surfaces, limiting the abundance of water elsewhere in the atmosphere. Atmospheric modeling suggests a dichotomy in the atmosphere between an H2O-dominated atmosphere near the warmer region where the Sun is overhead, and an O2-dominated atmosphere everywhere else.

“Showing that water vapor is a large fraction of the atmosphere of Ganymede — at least where the Sun is high — is a very timely result,” said SwRI’s Dr. Randy Gladstone, another co-author. “NASA’s Juno spacecraft is currently making close-up observations of Ganymede, including the emissions observed by HST, and these new results will be used to plan future observations with JUICE, which is designed to orbit Ganymede in 2033.”

“It’s interesting to think of an atmosphere that has a very different composition on its dayside relative to its nightside, with completely different processes driving the production of gases at different locations,” said Dr. Philippa Molyneux, a third SwRI co-author. “Imagine if Earth’s atmosphere worked that way, and how life might have evolved to adapt to that changing environment.”

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For more information, see paper at DOI: 10.1038/s41550-021-01426-9, visit https://www.swri.org/planetary-science.

DOI

10.1038/s41550-021-01426-9

ARTICLE TITLE

A sublimated water atmosphere on Ganymede detected from Hubble Space Telescope observations

First detection of light from behind a black hole

Peer-Reviewed Publication

STANFORD UNIVERSITY

Wilkins illustration — IMAGE: RESEARCHERS OBSERVED BRIGHT FLARES OF X-RAY EMISSIONS, PRODUCED AS GAS FALLS INTO A SUPERMASSIVE BLACK HOLE. THE FLARES ECHOED OFF OF THE GAS FALLING INTO THE BLACK HOLE, AND AS THE FLARES WERE SUBSIDING, SHORT FLASHES OF X-RAYS WERE SEEN – CORRESPONDING TO THE REFLECTION OF THE FLARES FROM THE FAR SIDE OF THE DISK, BENT AROUND THE BLACK HOLE BY ITS STRONG GRAVITATIONAL FIELD. view more
CREDIT: DAN WILKINS

Watching X-rays flung out into the universe by the supermassive black hole at the center of a galaxy 800 million light-years away, Stanford University astrophysicist Dan Wilkins noticed an intriguing pattern. He observed a series of bright flares of X-rays – exciting, but not unprecedented – and then, the telescopes recorded something unexpected: additional flashes of X-rays that were smaller, later and of different “colors” than the bright flares.

According to theory, these luminous echoes were consistent with X-rays reflected from behind the black hole – but even a basic understanding of black holes tells us that is a strange place for light to come from.

“Any light that goes into that black hole doesn’t come out, so we shouldn’t be able to see anything that’s behind the black hole,” said Wilkins, who is a research scientist at the Kavli Institute for Particle Astrophysics and Cosmology at Stanford and SLAC National Accelerator Laboratory. It is another strange characteristic of the black hole, however, that makes this observation possible. “The reason we can see that is because that black hole is warping space, bending light and twisting magnetic fields around itself,” Wilkins explained.

The strange discovery, detailed in a paper published July 28 in Nature, is the first direct observation of light from behind a black hole – a scenario that was predicted by Einstein’s theory of general relativity but never confirmed, until now.

“Fifty years ago, when astrophysicists starting speculating about how the magnetic field might behave close to a black hole, they had no idea that one day we might have the techniques to observe this directly and see Einstein’s general theory of relativity in action,” said Roger Blandford, a co-author of the paper who is the Luke Blossom Professor in the School of Humanities and Sciences, Stanford professor of physics and SLAC professor of particle physics and astrophysics.

How to see a black hole

The original motivation behind this research was to learn more about a mysterious feature of certain black holes, called a corona. Material falling into a supermassive black hole powers the brightest continuous sources of light in the universe, and as it does so, forms a corona around the black hole. This light – which is X-ray light – can be analyzed to map and characterize a black hole.

The leading theory for what a corona is starts with gas sliding into the black hole where it superheats to millions of degrees. At that temperature, electrons separate from atoms, creating a magnetized plasma. Caught up in the powerful spin of the black hole, the magnetic field arcs so high above the black hole, and twirls about itself so much, that it eventually breaks altogether – a situation so reminiscent of what happens around our own Sun that it borrowed the name “corona.”

“This magnetic field getting tied up and then snapping close to the black hole heats everything around it and produces these high energy electrons that then go on to produce the X-rays,” said Wilkins.

As Wilkins took a closer look to investigate the origin of the flares, he saw a series of smaller flashes. These, the researchers determined, are the same X-ray flares but reflected from the back of the disk – a first glimpse at the far side of a black hole.

“I’ve been building theoretical predictions of how these echoes appear to us for a few years,” said Wilkins. “I’d already seen them in the theory I’ve been developing, so once I saw them in the telescope observations, I could figure out the connection.”

Future observations

The mission to characterize and understand coronas continues and will require more observation. Part of that future will be the European Space Agency’s X-ray observatory, Athena (Advanced Telescope for High-ENergy Astrophysics). As a member of the lab of Steve Allen, professor of physics at Stanford and of particle physics and astrophysics at SLAC, Wilkins is helping to develop part of the Wide Field Imager detector for Athena.

“It’s got a much bigger mirror than we’ve ever had on an X-ray telescope and it’s going to let us get higher resolution looks in much shorter observation times,” said Wilkins. “So, the picture we are starting to get from the data at the moment is going to become much clearer with these new observatories.”

Co-authors of this research are from Saint Mary’s University (Canada), Netherlands Institute for Space Research (SRON), University of Amsterdam and The Pennsylvania State University.

This work was supported by the NASA NuSTAR and XMM-Newton Guest Observer programs, a Kavli Fellowship at Stanford University, and the V.M. Willaman Endowment at the Pennsylvania State University.

ESA illustration (IMAGE)

STANFORD UNIVERSITY

CAPTION
Illustration of how light echoes from behind a black hole.
CREDIT
ESA

JOURNAL

Nature

DOI

10.1038/s41586-021-03667-0

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE PUBLICATION DATE

28-Jul-2021

Computer science, environmental health experts at UIC team up to protect US Navy divers with AI

Office of Naval Research awards UIC, DPI researchers $725,000

Grant and Award Announcement

UNIVERSITY OF ILLINOIS AT CHICAGO

Underwater — IMAGE: RESEARCHERS AT UIC ARE WORKING ON AN AI SYSTEM TO HELP SAILORS, THANKS TO A TWO-YEAR, $725,000 GRANT AWARD view more
CREDIT: VLAD TCHOMPALOV/UNSPLASH

The U.S. Office of Naval Research has awarded University of Illinois Chicago researchers $725,000 to develop an artificial intelligence system that can help protect divers from waterborne bacteria, parasites, and other harmful pathogens and microbes.

Sailors are sent into all kinds of water as part of their service in the U.S. Navy, but they have limited resources to understand in real-time the health risks that may exist when they conduct underwater duties — everything from fleet maintenance and repairs to search and rescue and research missions. The most reliable water testing technologies typically rely on lab-based analysis of samples and scientists knowing which microbes to screen. But with dynamic weather, currents, water temperatures, and sewage and pollution factors, the exact condition of water, particularly of coastal water, at a specific time is hard to predict.

“By the time a water sample arrives at a lab and is tested, the conditions may have changed,” said Dr. Samuel Dorevitch, associate professor of environmental and occupational health sciences at the School of Public Health and co-principal investigator. “If Navy divers had real-time information, they could select the best protective equipment, dive duration and take other measures to prevent the various health issues, like heat stress or gastrointestinal, skin, and respiratory infections that may result from microbes in water.”

That’s where a new approach using artificial intelligence can make a difference.

“Artificial intelligence offers a way to synthesize a vast amount of information quickly for a specific calculation and this technology, if we can bring it to fruition, provides an opportunity for us to improve the tools available to the Navy,” said Isabel Cruz, distinguished professor of computer science at the College of Engineering and co-principal investigator.

The researchers hope that they can develop a system that can be used in any location by divers to analyze water conditions through a combination of user-provided and web-based information and human data, such as the age of the divers, their health, and the size of the diving team.

“This project is both exciting and challenging because of its multidimensionality,” Cruz said. “We hope to pull information from many sources that offer different types of data, and we will have to integrate data that are quite complex, heterogeneous, and often without metadata. We will build the artificial intelligence and machine learning methods in stages, and if we can teach our system to reliably and accurately filter and prioritize all these data for risk prediction, I think we will have something remarkable.”

“If we could provide divers or their commanders with a handheld device or app to evaluate the ever-changing ecosystem of a particular body of water and any potential health risks at the time they enter the water, they would be better able to plan their mission for optimal health and safety,” Dorevitch said. “For those in the Navy, getting in the water is not optional and anything we can do to aid quick, data-driven decision-making for mitigating health risk is beneficial.”

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Charlie Catlett, senior research scientist at Discovery Partners Institute, is a co-investigator. The grant, which started May 16, will support this research for two years.

Scientists capture most-detailed radio image of Andromeda galaxy to date

Disk of galaxy identified as region where new stars are born

Peer-Reviewed Publication

UNIVERSITY OF BRITISH COLUMBIA

Andromeda galaxy captured at 6.6 GHz — IMAGE: RADIO IMAGE OF ANDROMEDA GALAXY AT 6.6 GHZ (INSET), CAPTURED USING THE SARDINIA RADIO TELESCOPE IN ITALY. view more
CREDIT: S. FATIGONI ET AL (2021)

Scientists have published a new, detailed radio image of the Andromeda galaxy – the Milky Way’s sister galaxy – which will allow them to identify and study the regions of Andromeda where new stars are born.

The study – which is the first to create a radio image of Andromeda at the microwave frequency of 6.6 GHz – was led by University of British Columbia physicist Sofia Fatigoni, with colleagues at Sapienza University of Rome and the Italian National Institute of Astrophysics. It was published online in Astronomy and Astrophysics.

“This image will allow us to study the structure of Andromeda and its content in more detail than has ever been possible,” said Fatigoni, a PhD student in the department of physics and astronomy at UBC. “Understanding the nature of physical processes that take place inside Andromeda allows us to understand what happens in our own galaxy more clearly – as if we were looking at ourselves from the outside.”

Prior to this study, no maps capturing such a large region of the sky around the Andromeda Galaxy had ever been made in the microwave band frequencies between one GHz to 22 GHz. In this range, the galaxy’s emission is very faint, making it hard to see its structure. However, it is only in this frequency range that particular features are visible, so having a map at this particular frequency is crucial to understanding which physical processes are happening inside Andromeda.

In order to observe Andromeda at this frequency, the researchers required a single-dish radio telescope with a large effective area. For the study, the scientists turned to the Sardinia Radio Telescope, a 64-metre fully steerable telescope capable of operating at high radio frequencies.

It took 66 hours of observation with the Sardinia Radio Telescope and consistent data analysis for the researchers to map the galaxy with high sensitivity. They were then able to estimate the rate of star formation within Andromeda, and produce a detailed map that highlighted the disk of the galaxy as the region where new stars are born.

“By combining this new image with those previously acquired, we have made significant steps forward in clarifying the nature of Andromeda’s microwave emissions and allowing us to distinguish physical processes that occur in different regions of the galaxy,” said Dr. Elia Battistelli, a professor in the department of physics at Sapienza and coordinator of the study.

“In particular, we were able to determine the fraction of emissions due to thermal processes related to the early stations of new star formation, and the fraction of radio signals attributable to non-thermal mechanisms due to cosmic rays that spiral in the magnetic field present in the interstellar medium,” Fatigoni said.

For the study, the team developed and implemented software that allowed – among other things – to test new algorithms to identify never-before-examined lower emission sources in the field of view around Andromeda at a frequency of 6.6 GHz. From the resulting map, researchers were able to identify a catalog of about 100 point sources, including stars, galaxies and other objects in the background of Andromeda.