Hexbyte Glen Cove Scientists sketch aged star system using over a century of observations thumbnail

Hexbyte Glen Cove Scientists sketch aged star system using over a century of observations

Hexbyte Glen Cove

U Mon’s primary star, an elderly yellow supergiant, has around twice the Sun’s mass but has billowed to 100 times the Sun’s size. Scientists know less about the companion, the blue star in the background of this illustration, but they think it’s of similar mass and much younger than the primary. Credit: Credit: NASA’s Goddard Space Flight Center/Chris Smith (USRA/GESTAR)

Astronomers have painted their best picture yet of an RV Tauri variable, a rare type of stellar binary where two stars—one approaching the end of its life—orbit within a sprawling disk of dust. Their 130-year dataset spans the widest range of light yet collected for one of these systems, from radio to X-rays.

“There are only about 300 known RV Tauri variables in the Milky Way galaxy,” said Laura Vega, a recent doctoral recipient at Vanderbilt University in Nashville, Tennessee. “We focused our study on the second brightest, named U Monocerotis, which is now the first of these systems from which X-rays have been detected.”

A paper describing the findings, led by Vega, was published in The Astrophysical Journal.

The system, called U Mon for short, lies around 3,600 light-years away in the constellation Monoceros. Its two stars circle each other about every six and a half years on an orbit tipped about 75 degrees from our perspective.

The primary star, an elderly yellow supergiant, has around twice the Sun’s mass but has billowed to 100 times the Sun’s size. A tug of war between pressure and temperature in its atmosphere causes it to regularly expand and contract, and these pulsations create predictable brightness changes with alternating deep and shallow dips in light—a hallmark of RV Tauri systems. Scientists know less about the companion star, but they think it’s of similar mass and much younger than the primary.

This infographic shows U Mon’s components to scale. Credit: NASA’s Goddard Space Flight Center/Chris Smith (USRA/GESTAR)

The cool disk around both stars is composed of gas and dust ejected by the primary star as it evolved. Using radio observations from the Submillimeter Array on Maunakea, Hawai’i, Vega’s team estimated that the disk is around 51 billion miles (82 billion kilometers) across. The binary orbits inside a central gap that the scientists think is comparable to the distance between the two stars at their maximum separation, when they’re about 540 million miles (870 million kilometers) apart.

When the stars are farthest from each other, they’re roughly aligned with our line of sight. The disk partially obscures the primary and creates another predictable fluctuation in the system’s light. Vega and her colleagues think this is when one or both interact with the disk’s inner edge, siphoning off streams of gas and dust. They suggest that the companion star funnels the gas into its own disk, which heats up and generates an X-ray-emitting outflow of gas. This model could explain X-rays detected in 2016 by the European Space Agency’s XMM-Newton satellite.

“The XMM observations make U Mon the first RV Tauri variable detected in X-rays,” said Kim Weaver, the XMM U.S. project scientist and an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s exciting to see ground- and space-based multiwavelength measurements come together to give us new insights into a long-studied system.”

In their analysis of U Mon, Vega’s team also incorporated 130 years of visible light observations.

Two stars orbit each other within an enormous dusty disk in the U Monocerotis system, illustrated here. When the stars are farthest from each other, they funnel material from the disk’s inner edge. At this time, the primary star is slightly obscured by the disk from our perspective. The primary star, a yellow supergiant, expands and contracts. The smaller secondary star is thought to maintain its own disk of material, which likely powers an outflow of gas that emits X-rays. Credit: NASA’s Goddard Space Flight Center/Chris Smith (USRA/GESTAR)

The earliest available measurement of the system, collected on Dec. 25, 1888, came from the archives of the American Association of Variable Star Observers (AAVSO), an international network of amateur and professional astronomers headquartered in Cambridge, Massachusetts. AAVSO provided additional historical measurements ranging from the mid-1940s to the present.

The researchers also used archived images cataloged by the Digital Access to a Sky Century @ Harvard (DASCH), a program at the Harvard College Observatory in Cambridge dedicated to digitizing astronomical images from glass photographic plates made by ground-based telescopes between the 1880s and 1990s.

U Mon’s light varies both because the primary star pulsates and because the disk partially obscures it every 6.5 years or so. The combined AAVSO and DASCH data allowed Vega and her colleagues to spot an even longer cycle, where the system’s brightness rises and falls about every 60 years. They think a warp or clump in the disk, located about as far from the binary as Neptune is from the Sun, causes this extra variation as it orbits.

Vega completed her analysis of the U Mon system as a NASA Harriett G. Jenkins Predoctoral Fellow, a program funded by the NASA Office of STEM Engagement’s Minority University Research and Education Project.

On May 12, 1948, astronomers at Boyden Observatory in Bloemfontein, South Africa, captured a portion of the sky containing U Monocerotis (left, circled) on a glass photographic plate. The logbook entry (right) for the observation reads: Gusty S wind. H.A. [Hour Angle] should be 2 02 W. Credit: Harvard College Observatory, Photographic Glass Plate Collection. Used with permission.

“For her doctoral dissertation, Laura used this historical dataset to detect a characteristic that would otherwise appear only once in an astronomer’s career,” said co-author Rodolfo Montez Jr., an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian, also in Cambridge. “It’s a testament to how our knowledge of the universe builds over time.”

Co-author Keivan Stassun, an expert in star formation and Vega’s doctoral advisor at Vanderbilt, notes that this evolved system has many features and behaviors in common with newly formed binaries. Both are embedded in disks of gas and dust, pull material from those disks, and produce outflows of gas. And in both cases, the disks can form warps or clumps. In young binaries, those might signal the beginnings of planet formation.

“We still have questions about the feature in U Mon’s , which may be answered by future radio observations,” Stassun said. “But otherwise, many of the same characteristics are there. It’s fascinating how closely these two binary life stages mirror each other.”



More information:
Laura D. Vega et al. Multiwavelength Observations of the RV Tauri Variable System U Monocerotis: Long-term Variability Phenomena That Can Be Explained by Binary Interactions with a Circumbinary Disk, The Astrophysical Journal (2021). DOI: 10.3847/1538-4357/abe302

Citation:
Scientists sketch aged star system using over a century of observations (2021, March 12)
retrieved 13 March 2021
from https://phys.org/news/2021-03-scientists-aged-star-century.html

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Hexbyte Glen Cove Farm-level study shows rising temperatures hurt rice yields thumbnail

Hexbyte Glen Cove Farm-level study shows rising temperatures hurt rice yields

Hexbyte Glen Cove

Credit: CC0 Public Domain

A study of the relationship between temperature and yields of various rice varieties, based on 50 years of weather and rice-yield data from farms in the Philippines, suggests that warming temperatures negatively affect rice yields.

Recent varieties of rice, bred for environmental stresses like heat, showed better yields than both traditional rice varieties and modern varieties of rice that were not specifically bred to withstand warmer temperatures. But the study found that warming adversely affected crop yields even for those varieties best suited to the heat. Overall, the advantage of varieties bred to withstand increased heat was too small to be statistically significant.

One of the top 10 countries globally in rice production, the Philippines is also a top-10 rice importer, as domestic supply cannot meet demand.

Roderick Rejesus, a professor and extension specialist of agricultural and resource economics at North Carolina State University and the corresponding author of a paper that describes the study, says that teasing out the effects of temperature on rice yields is important to understand whether rice-breeding efforts have helped address the environmental challenges faced by modern society, such as global warming.

The study examined rice yields and atmospheric conditions from 1966 to 2016 in Central Luzon, the major rice-growing region of the Philippines. Rejesus and study colleagues were able to utilize -level data of rice yields and area weather conditions in four-to-five-year increments over the 50-year period, a rare data trove that allowed the researchers to painstakingly examine the relationship between rice yield and temperature in actual farm environments.

“This rich data set allowed us to see what was actually happening at the farm level, rather than only observing behavior at higher levels of aggregation like in provinces or districts,” Rejesus said.

The study examined three general rice varieties planted during those 50 years: traditional rice varieties; “early modern varieties” planted after the onset of the Green Revolution, which were bred for higher yields; and “recent modern varieties” bred for particular characteristics, like heat or pest resistance, for example.

Perhaps as expected, the study showed that, in the presence of warming, recent modern varieties had the best yields when compared with the early modern and traditional varieties, and that early modern varieties outperformed traditional varieties. Interestingly, some of the early modern varieties may have also mitigated heat challenges given their smaller “semi-dwarf” plant architecture, even though they were not bred to specifically resist heat.

“Taken all together, there are two main implications here,” Rejesus said. “The first is that, at the farm level, there appears to be a ‘ gap’ between how rice performs in breeding trials and on farms, with farm performance of recent varieties bred to be more tolerant to environmental stresses not being statistically different relative to the older varieties.

“The second is that rice breeding efforts may not have reached their full potential such that it may be possible to produce new varieties that will statistically perform better than older varieties in a farm setting.”

Rejesus also acknowledged that the study’s modest sample size may have contributed to the inability to find statistical significance in the differences in warming impacts between rice varietal yields.

“This paper has implications for other rice-breeding countries, like Vietnam, because the timing of the release of various rice varieties is somewhat similar to that of the Philippines,” Rejesus said. “Plant-breeding institutions can learn from this type of analysis, too. It provides guidance as to where research funding may be allocated by policymakers to further improve the high temperature tolerance of varieties available to farmers.”

Rejesus plans to further study other agricultural practices and innovations that affect crop yields, including an examination of cover crops, or plants grown on cropland in the off season that aim to keep soils healthy, to gauge whether they can mitigate the adverse impacts of a changing climate.

The paper appears in the American Journal of Agricultural Economics.



More information:
Ruixue Wang et al, Quantifying the Yield Sensitivity of Modern Rice Varieties to Warming Temperatures: Evidence from the Philippines, American Journal of Agricultural Economics (2021). DOI: 10.1111/ajae.12210

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Hexbyte Glen Cove Scientists stabilize atomically thin boron for practical use thumbnail

Hexbyte Glen Cove Scientists stabilize atomically thin boron for practical use

Hexbyte Glen Cove

In this schematic, the teal balls represent boron and the red balls are hydrogen. Credit: Northwestern University

Northwestern University researchers have, for the first time, created borophane—atomically thin boron that is stable at standard temperatures and air pressures.

Researchers have long been excited by the promise of borophene—a single-atom-thick sheet of boron—because of its strength, flexibility and electronics properties. Stronger, lighter and more flexible than graphene, borophene could potentially revolutionize batteries, electronics, sensors, photovoltaics and quantum computing.

Unfortunately, borophene only exists inside of an chamber, limiting its practical use outside the lab. By bonding borophene with atomic hydrogen, the Northwestern team created borophane, which has the same exciting properties as borophene and is stable outside of a vacuum.

“The problem is that if you take borophene out of the ultrahigh vacuum and into air, it immediately oxidizes,” said Mark C. Hersam, who led the research. “Once it oxidizes, it is no longer borophene and is no longer conductive. The field will continue to be hindered in exploring its real-world use unless borophene can be rendered stable outside an ultrahigh vacuum chamber.”

The research will be published March 12 in the journal Science and featured on the cover (“Synthesis of borophane polymorphs through hydrogenation of borophene”). The study marks the first time scientists report the synthesis of borophane.

Hersam is the Walter P. Murphy Professor of Materials Science and Engineering at Northwestern’s McCormick School of Engineering and director of the Materials Research Science and Engineering Center.

Although borophene is frequently compared to its super-material predecessor graphene, borophene is much more difficult to create. Graphene is the atomically thin version of graphite, a layered material comprising stacks of two-dimensional sheets. To remove a two-dimensional layer from graphite, scientists simply peel it off.

Boron, on the other hand, is not layered when in bulk form. Five years ago, Hersam and collaborators created borophene for the first time by growing it directly on a substrate. The resulting material, however, was highly reactive, making it vulnerable to oxidation.

“The atoms in are highly susceptible to further chemical reactions,” Hersam said. “We found that once the are bonded with hydrogen, they will no longer react with oxygen when in open air.”

Now that borophane can be taken out into the real world, Hersam said researchers will be able to more rapidly explore borophane’s properties and its potential applications.

“Materials synthesis is a bit like baking,” Hersam said. “Once you know the recipe, it’s not hard to replicate. However, if your recipe is just a little off, then the final product can flop terribly. By sharing the optimal recipe for borophane with the world, we anticipate that its use will rapidly proliferate.”



More information:
“Synthesis of borophane polymorphs through hydrogenation of borophene” Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abg1874

Citation:
Scientists stabilize atomically thin boron for practical use (2021, March 11)
retrieved 12 March 2021
from https://phys.org/news/2021-03-scientists-stabilize-atomically-thin-boron.html

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Hexbyte Glen Cove AI analysis of how bacteria attack could help predict infection outcomes thumbnail

Hexbyte Glen Cove AI analysis of how bacteria attack could help predict infection outcomes

Hexbyte Glen Cove

Credit: CC0 Public Domain

Insights into how bacterial proteins work as a network to take control of our cells could help predict infection outcomes and develop new treatments.

Much like a hacker seizes control of a company’s software to cause chaos, disease-causing bacteria, such as E. coli and Salmonella, use miniature molecular syringes to inject their own chaos-inducing agents (called effectors) into the cells that keep our guts healthy.

These effectors take control of our cells, overwhelming their defences and blocking key immune responses, allowing the to take hold.

Previously, studies have investigated single effectors. Now a team led by scientists at Imperial College London and The Institute of Cancer Research, London, and including researchers from the UK, Spain and Israel, has studied whole sets of effectors in different combinations.

The study, published today in Science, investigated data from experiments in mice infected with the mouse version of E. coli, called Citrobacter rodentium, which injects 31 effectors.

The results show how effectors work together as a network, allowing them to colonise their hosts even if some effectors are removed. The investigation also revealed how the host’s immune system can bypass the obstacles the effectors create, triggering complementary immune responses.

The researchers suggest that knowing how the makeup of effector networks influences the ability of infections to take hold could help design interventions that disrupt their effects.

Study lead Professor Gad Frankel, from the Department of Life Sciences at Imperial, said: “The data represent a breakthrough in our understanding of the mechanisms of bacterial infections and host responses. Our results show that the injected effectors are not working individually, but instead as a pack.

An animation describing the results of the paper ‘Type III secretion system effectors form robust and flexible intracellular virulence networks’ Credit: LIA-UPM

“We found there is an inherent strength and flexibility to the network, which ensures that if one or several components don’t work, the infection can go on. Importantly, this work has also revealed that our cells have a built-in firewall, which means that we can deal with the hacker’s corruptive networks and mount effective immune responses that can clear the infection.”

Study co-lead Professor Jyoti Choudhary, from the Functional Proteomics Lab at The Institute of Cancer Research, London, said: “Our study shows that we can predict how a cell will respond when attacked by different combinations of bacterial effector proteins. The research will help us to better understand how cells, the immune system and bacteria interact, and we can apply this knowledge to diseases like cancer and inflammatory bowel disease where bacteria in the gut play an important role.

“We hope, through further study, to build on this knowledge and work out exactly how these effector proteins function, and how they work together to disrupt host . In future, this enhanced understanding could lead to the development of new treatments.”

During their experiments, the team were able to remove different effectors when infecting mice with the pathogen, tracking how successful each infection was. This showed that the effector produced by the pathogen could be reduced by up to 60 percent and still produce a successful infection.

The team collected data on more than 100 different synthetic combinations of the 31 effectors, which Professor Alfonso Rodríguez-Patón and Elena Núñez-Berrueco at the Universidad Politécnica de Madrid used to build an artificial intelligence (AI) algorithm.

The AI model was able to predict the outcomes of infection with Citrobacter rodentium expressing different effector networks, which were tested with experiments in mice. As it is impossible to test in the lab all the possible networks that 31 effectors can form, employing an AI model is the only practical approach to studying biological systems of this complexity.

Co-first author Dr. David Ruano-Gallego from the Department of Life Sciences at Imperial, said: “The AI allows us to focus on creating the most relevant combinations of effectors and learn from them how bacteria are counteracted by our . These combinations would not be obvious from our experimental results alone, opening up the possibility of using AI to predict infection outcomes.”

Co-first author Dr. Julia Sánchez-Garrido, from the Department of Life Sciences at Imperial, added: “Our results also mean that in the future, using AI and synthetic biology, we should be able to work out which cell functions are essential during infection, enabling us to find ways to fight the infection not by killing the pathogen with antibiotics, but instead by changing and improving our natural defence responses to infection.”



More information:
“Type III secretion system effectors form robust and flexible intracellular virulence networks” Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abc9531

Citation:
AI analysis of how bacteria attack could help predict infection outcomes (2021, March 11)
retrieved 12 March 2021
from https://phys.org/news/2021-03-ai-analysis-bacteria-infection-outcomes.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written

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Hexbyte Glen Cove The skeleton of the malaria parasite reveals its secrets thumbnail

Hexbyte Glen Cove The skeleton of the malaria parasite reveals its secrets

Hexbyte Glen Cove

Plasmodium at the ookinete stage viewed by expansion microscopy. The image shows the cytoskeleton of the pathogen following the labelling of tubulin. The conoid is the ring visible at the upper tip of the cell. Credit: © UNIGE/HAMEL

Plasmodium is the parasite causing malaria, one of the deadliest parasitic diseases. The parasite requires two hosts —the Anopheles mosquito and the human— to complete its life cycle and goes through different forms at each stage of its life cycle. Transitioning from one form to the next involves a massive reorganization of the cytoskeleton. Two teams from the University of Geneva (UNIGE) have shed new light on the cytoskeleton organization in Plasmodium. Their research, published in PLOS Biology, details the organization of the parasite’s skeleton at an unprecedented scale, adapting a recently developed technique called expansion microscopy. Cells are “inflated” before imaging, providing access to more structural details, at a nanometric scale. The study identifies traces of an organelle called “conoid,” which was thought to be lacking in this species despite its crucial role in host invasion of closely related parasites.

The , or cell skeleton, consists of a network of several types of filaments, including actin and tubulin. It confers rigidity to the cell, allows the attachment or movement of organelles and molecules inside the cell, as well as cell deformations. As the parasite transitions between developmental stages, its cytoskeleton undergoes repeated, drastic, reorganizations. In particular, Plasmodium needs a very specific cytoskeleton in order to move and penetrate the membrane barriers of its host cells, two processes that are central to the pathogenesis of malaria-causing . “Due to the very small size of Plasmodium—up to 50 times smaller than a human cell—it is a to view its cytoskeleton,” says Eloïse Bertiaux, a researcher at UNIGE and the first author of the study.

“That is why we adapted our protocol, which consists of inflating the biological sample while keeping its original shape, so it can be observed at a resolution that has never been attained before,” says Virginie Hamel, a researcher at the Department of Cell Biology of the Faculty of Sciences of UNIGE and co-leading the study.

A Vestigial Form of an Organelle

The researchers observed the parasite at the ookinete stage, the form responsible for the invasion of the mosquito midgut, an essential step for the dissemination of malaria. A structure made of tubulin was visible at the tip of the parasite. This structure is similar to a conoid, an organelle involved in host cell invasion, in related Apicomplexa parasites. “The structure observed in Plasmodium seems, however, divergent and reduced compared with the well-described conoid of Toxoplasma, the parasite causing toxoplasmosis. We still need to determine whether this remnant conoid is also important for host cell invasion of Plasmodium,” says Mathieu Brochet, a professor at the Department of Microbiology and Molecular Medicine of the Faculty of Medicine of UNIGE.

Cytoskeleton Under the Microscope

The discovery of this vestigial conoid highlights the power of expansion microscopy, which can be used to view cytoskeletal structures at the nanoscale without the need for specialized microscopes. Used in combination with and super-resolution microscopy approaches, this method adds molecular details to the available structural information, paving the way for more in-depth studies of the cytoskeleton and its molecular organization. This will allow us to gain a better understanding of how Plasmodium invades its host , a process that is essential for the pathogenesis of this parasite.



More information:
PLOS Biology (2021). DOI: 10.1371/journal.pbio.3001020

Citation:
The skeleton of the malaria parasite reveals its secrets (2021, March 11)
retrieved 12 March 2021
from https://phys.org/news/2021-03-skeleton-malaria-parasite-reveals-secrets.html

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part may be reproduced without the written permission

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Hexbyte Glen Cove Retreating glaciers threaten herbs used to make iconic alpine liqueurs thumbnail

Hexbyte Glen Cove Retreating glaciers threaten herbs used to make iconic alpine liqueurs

Hexbyte Glen Cove

Saxifrage oppositifolia, or purple mountain saxifrage, grows directly on a rock face in the Alps. Credit: Appollonio Tottoli

Alpine landscapes are irrevocably changing: scientists estimate that the Alps may be glacier-free by the end of this century. As the ice melts, the unique ecosystems that exist at their edges are also fading. New research published in Frontiers in Ecology and Evolution untangled what changing flora might mean for the ecology, economy and culture of the region.

The Alps, known for their meadows brimming with wildflowers in the spring and summer, are home to many that are specialized for glacial growing conditions. Many of these plants are fragrant herbs, some of which have been used to make medicines and liqueurs for centuries. These distinctive, have become an important part of the culture and economy of the mountains. The herbs are part of a landscape that hosts a dynamic, evolving system of plants that scientists are watching shift in real-time.

As glaciers retreat, they expose new land which is readily colonized by plants. “The retreat of glaciers is a double-edged sword,” said lead author Gianalberto Losapio in an interview with GlacierHub. “There is an initial increase in biodiversity because the retreating glaciers are making space available. If today there is ice and the glacier is retreating, it means that tomorrow there might be new terrain because the ice is gone, which means that seeds can grow.”

At the fringes of a glacier, the soil that is exposed is often not well-suited to hosting plant life. There is often more rocky debris than soil, and the soil that is present is not always rich in the nutrients that plants need. Many native Alpine herbs have carved out a niche for themselves in these proglacial areas. These plants, which survive where others cannot, are called “pioneers” by ecologists. “The initial plants, the pioneers, are adapted to living in this harsh environment,” said Losapio.

The pioneer species are often small and low to the ground. They don’t need much in the way of soil or nutrients to grow. In the past, these were the only plants able to survive at the edges of a glacier. Now, with year-round ice-free ground, the proglacial habitats are narrowing.

Ranunculus glacialis, or Arctic Buttercup, is a pioneer species. Credit: Gianalberto Losapio

The pioneer species not only establish themselves, but also prime the land for new plants to thrive by building up biomass and providing nutrients. “These early plants improve the environment in such a way that other plants can benefit from,” said Losapio. “The higher the colonization, the more this facilitation and mutualistic interaction take place, which increases biodiversity.”

After the early plants have done the work of stabilizing the landscape, other plants move in. The later species that enter are not as well-suited for the difficult initial growing conditions as the pioneer plants are, but thrive on the land primed by them. In the past, the ice returned after a few short months and later species did not have time to establish. But now, with many glaciers disappearing and the annual period of snow cover shrinking, the later species have a new opening.

As the later species move in, the dynamic of the area changes. “The arrival of the late species increases the competition,” said Losapio. “They require more organic matter and they also reproduce vegetatively, not with seeds, so they occupy much more of the space.”

The later plants piggy-back off the conditions that the hardy, early species help create. And then, they take over. The later species reproduce much faster than the , and take up more resources, leaving little space for the slower-growing plants that came before them.

Many of the early species, including Arctic buttercup, saxifrage, and wormwood, simply cannot compete with these fast-growing newcomers. Eventually, the later species might be all that is left on high-elevation Alpine land. “The area is going to be much more dominated by grasslands,” said Losapio. “This is going to decrease biodiversity in general.”

Cyril Gros” data-thumb=”https://scx1.b-cdn.net/csz/news/tmb/2021/2-retreatinggl.jpg”>

Cyril Gros”>
Artemisia genipi growing in the Alps. Credit: Cyril Gros

These effects extend beyond just the plants; insect populations could suffer, too. “We also observed a decline in insect-pollinated species,” explained Losapio “[Insect] populations are very high in pioneer and initial stages, but the plants in grasslands are not usually pollinated by insects.”

In addition to changing the appearance and biodiversity of the area, the shifts due to deglaciation could also have economic and cultural impacts. Among the pioneer plants that are being squeezed out is Artemisia genipi, often called simply genipi, genepy or black wormwood. “Artemisia genipi is a very rare, iconic plant. Already, after 100 years of glacier retreat, it has been declining,” said Losapio. “Its distribution is very narrow. It grows only in the northwestern Alps. Culturally it is super important. Hikers up in the mountains go and they stop at a hut, they have a piece of cake and a shot of genepi.”

Varieties of Artemisia have been used throughout Europe since Roman times as a key ingredient in medicines. “Genepi varieties have historically been used in folk and because of their bioactivity,” said Alessio Anselmo, an herbal technician with Italian Alpine liqueur producer Bordiga, in an interview with GlacierHub. “They were known and used as thermogenic agents against the common cold, in infusions against fever, and in aromatic wines and liqueurs to stimulate appetite and digestion.”

Centuries of production of Artemisia genipi–infused drinks has led the flavor to become an emblem of the region. “To produce genepi liqueur, the aerial parts and flowers are introduced into a hydroalcoholic solution and rest lightless at ambient temperature for 40 days,” explains Anselmo. “Then the solid parts are pressed with a hydraulic press and the infusion rests for some months. Finally, the infusion is mixed with alcohol, water and sugar, filtered and bottled.”

Traditional recipes for absinthe, Chartreuse, amari and various other alpine liqueurs use Artemisia genipi as a key ingredient. “Artemesia genepi is a type of wormwood and as such, adds a bitter vegetal flavor to the spirit,” said David Curiel, spirits specialist with the importer Oliver McCrum Wines & Spirits in an interview with GlacierHub. “It’s a distinct alpine flavor that embodies the sense of place.”

Alpe & Bordiga” data-thumb=”https://scx1.b-cdn.net/csz/news/tmb/2021/3-retreatinggl.jpg”>

Alpe & Bordiga“>
A selection of beverages that feature Alpine herbs. Credit: Alpe & Bordiga

Today, producers throughout the Alps continue to make liqueurs and fortified wines using Artemisia and other Alpine herbs. Once primarily consumed by chilly mountain hikers as a respite from Alpine snow and ice, Artemisia genipi has found a new home in cocktail bars across the world.

“Most people [in the United States] tend to be familiar with these flavors because of Chartreuse, possibly the biggest commercial exporter of genepi, but the category is actually quite broad in Europe,” said Curiel. “[In the Alps,] Artemisia genipi commonly finds itself being consumed during the colder months, maybe in a ski lodge, sitting by a fire. Here in the U.S., the craft cocktail scene seems to lean into using it in refreshing citrus-driven cocktails that you might consume in the summer while sitting on a patio, or poolside.”

Even American producers have been trying their hand at Artemisia genipi–based liqueurs. At Forthave Spirits in Brooklyn, New York co-founders Aaron Sing Fox and Daniel de la Nuez have been making botanical liqueurs since 2013. “Genepi has a very complex, enchanting and difficult to describe flavor,” Fox told GlacierHub. “We wanted to make something that highlighted the delicate aspects of this botanical so we used it to make a wine-based aperitif.”

Fox and de la Nuez source their Artemisia genipi not from the wild, but from a grower in the Alps who cultivates a very limited crop each year. Still, the loss of wild genipi looms large. “The loss of wild genepi would be heartbreaking,” said Fox. “There is much more to learn and explore from the many wild genepi that are out there.”



More information:
Gianalberto Losapio et al. The Consequences of Glacier Retreat Are Uneven Between Plant Species, Frontiers in Ecology and Evolution (2021). DOI: 10.3389/fevo.2020.616562

This story is republished courtesy of Earth Institute, Columbia University http://blogs.ei.columbia.edu.

Citation:
Retreating glaciers threaten herbs used to make iconic alpine liqueurs (2021, March 10)
retrieved 11 March 2021
from https://phys.org/news/2021-03-retreating-glaciers-threaten-herbs-iconic.html

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part may be reproduced without the written permission. The content is provided for information purpos

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Hexbyte Glen Cove COVID-19 has exacerbated gender inequities in housework, childcare and mental health thumbnail

Hexbyte Glen Cove COVID-19 has exacerbated gender inequities in housework, childcare and mental health

Hexbyte Glen Cove

Credit: Pixabay/CC0 Public Domain

During the height of the first COVID-19 lockdown in the UK, women spent more time on unpaid housework and childcare than men, were more likely to reduce working hours, and reported higher levels of psychological distress, according to a new study published last week in the open-access journal PLOS ONE by Baowen Xue and Anne McMunn of University College London, UK.

Before the COVID-19 pandemic, studies had already shown that in the UK today spend more time doing unpaid care work than men. In March 2020, facilities and schools in the UK were shut down in response to the ongoing COVID-19 pandemic. There has been concern that the shutdown and school closures may have exacerbated existing gender inequities in care work and .

In the new study, researchers used data from the Understanding Society Covid-19 study, part of a longitudinal study being carried out in the UK since 2009. In 2020, participants from recent waves of the Understanding Society study were invited to complete a web survey each month on their experiences during the pandemic. A total of 17,452 respondents completed the survey in April and 14,811 completed the survey in May.

On average, in April and May 2020, women spent about 15 hours a week doing housework while men spent less than 10 hours per week on housework. Women spent 20.5 hours a week on childcare and homeschooling in April, and 22.5 hours per week in May, while men spent about 12 hours on these responsibilities in both months. Overall, within couples, women were responsible for 64% of housework and 63% of childcare. In addition, working fathers were 5 percent less likely to reduce working hours and 7 percent less likely to change their work patterns due to childcare or homeschooling compared to working mothers.

With regards to mental health, the study found that increased housework and childcare/homeschooling hours were associated with higher levels of psychological distress among women in April; no significant association was found among men and the association was weaker in May. Levels of psychological distress were particularly high if a parent was the only member in the household who adapted work patterns, as well as among lone mothers who had to adapt work patterns. The authors conclude that the COVID-19 pandemic has put a strain on parents, especially lone mothers, and influenced their mental health. Awareness of continued , the authors say, is important for both couples and employers going forward.

The authors add: “There are continued gender inequalities in divisions of unpaid . Juggling home working with homeschooling and childcare as well as extra is likely to lead to poor for people with families, particularly for lone mothers.”



More information:
Baowen Xue et al, Gender differences in unpaid care work and psychological distress in the UK Covid-19 lockdown, PLOS ONE (2021). DOI: 10.1371/journal.pone.0247959

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COVID-19 has exacerbated gender inequities in housework, childcare and mental health (2021, March 10)
retrieved 11 March 2021
from https://phys.org/news/2021-03-covid-exacerbated-gender-inequities-housework.html

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Hexbyte Glen Cove A nanoparticle's size is fine-tuned to offer high-resolution images before and during surgical procedures thumbnail

Hexbyte Glen Cove A nanoparticle’s size is fine-tuned to offer high-resolution images before and during surgical procedures

Hexbyte Glen Cove

The scientists injected the nanoparticle solution into the tail veins of live mice and were able to obtain high quality MRI (left) and near-infrared fluorescence (right) scans of tissues and blood vessels. Credit: National Institute for Materials Science (NIMS)

Scientists have found a way to control the size of special nanoparticles to optimize their use for both magnetic resonance and near-infrared imaging. Their approach could help surgeons use the same nanoparticles to visualize tumors just before and then during surgery using the two different imaging techniques. Their findings were published in the journal Science and Technology of Advanced Materials.

“Magnetic resonance imaging is routinely used in pre-operative diagnosis, while surgeons have started using near-infrared fluorescence imaging during surgical procedures,” says nanobiotechnologist Kyohei Okubo of Tokyo University of Science. “Our nanoparticle probes could provide a bimodality that will be clinically appealing to medical device researchers and doctors.”

Ceramic made with the rare earth metals ytterbium (Yb) and erbium (Er) have demonstrated low toxicity and prolonged near-infrared luminescence, showing promise as a contrast agent in MRI scans and a fluorescing agent for near-infrared fluorescence imaging. Images of blood vessels and organs in live bodies can be obtained with the two imaging techniques by further modifying the nanoparticle surfaces with polyethylene glycol (PEG)-based polymers. But to improve , scientists need to have more control over nanoparticle size during the fabrication process.

Okubo and his colleagues used a step-by-step fabrication process that starts with mixing rare earth oxides in water and trifluoracetic acid. The mixture is heated to form a solid. Then it is dissolved in solution, oleic acid is added and gas is removed. So-called rare-earth-doped ceramic nanoparticles form when this solution is cooled.

A few more steps lead to the coating of the nanoparticle surfaces with PEG. The scientists found they could slow the growth rate of the nanoparticles by increasing their concentration before the coating process. This allowed them to form nanoparticles 15 and 45 nanometres in diameter.

The team conducted a series of tests to examine the properties of their nanoparticles. They found that they could be used for obtaining high-quality of blood vessels in live mice using MRI and near-infrared fluorescence imaging techniques. Further tests showed the nanoparticles exhibited minimal toxicity on mouse fibroblast cells when used in low concentrations. They also have a short half-life, meaning they would be cleared relatively quickly from the body, making them safe for .

The team next aims to investigate how different distributions of paramagnetic ions on the nanoparticles affect their magnetic properties. They also aim to study whether modifications made to the nanoparticles could make them applicable for use in light-based ‘photodynamic’ therapies for treating skin cancers and acne, for example.



More information:
Kyohei Okubo et al. Size-controlled bimodal in vivo nanoprobes as near-infrared phosphors and positive contrast agents for magnetic resonance imaging, Science and Technology of Advanced Materials (2021). DOI: 10.1080/14686996.2021.1887712

Citation:
A nanoparticle’s size is fine-tuned to offer high-resolution images before and during surgical procedures (2021, March 10)
retrieved 11 March 2021
from https://phys.org/news/2021-03-nanoparticle-size-fine-tuned-high-resolution-images.html

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part may be reproduced without the written permission. The content is provided for information purposes only.

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Hexbyte Glen Cove Key step reached to­ward long-​sought goal of a silicon-​based laser thumbnail

Hexbyte Glen Cove Key step reached to­ward long-​sought goal of a silicon-​based laser

Hexbyte Glen Cove

Scanning transmission electron microscopy (STEM) images of one of the Ge/SiGe heterostructures at different magnifications. The SiGe layers appear darker. Credit: Università Roma Tre, De Seta Group

When it comes to microelectronics, there is one chemical element like no other: silicon, the workhorse of the transistor technology that drives our information society. The countless electronic devices we use in everyday life are a testament to how today very high volumes of silicon-based components can be produced at very low cost. It seems natural, then, to use silicon also in other areas where the properties of semiconductors—as silicon is one—are exploited technologically, and to explore ways to integrate different functionalities. Of particular interest in this context are diode lasers, such as those employed in barcode scanners or laser pointers, which are typically based on gallium arsenide (GaAs). Unfortunately though, the physical processes that create light in GaAs do not work so well in silicon. It therefore remains an outstanding, and long-standing, goal to find an alternative route to realizing a ‘laser on silicon.’

Writing today in Applied Physics Letters, an international team led by Professors Giacomo Scalari and Jérôme Faist from the Institute for Quantum Electronics present an important step towards such a device. They report electroluminescence—electrical light generation—from a based on silicon-germanium (SiGe), a material that is compatible with standard fabrication processes used for silicon devices. Moreover, the emission they observed is in the terahertz frequency band, which sits between those of microwave electronics and infrared optics, and is of high current interest with a view to a variety of applications.

Make silicon shine

The main reason why silicon cannot be used directly for building a laser following to the GaAs template has to do with the different nature of their band gaps, which is direct in the latter but indirect in the former. In a nutshell, in GaAs electrons recombine with holes across the bandgap producing light; in silicon, they produce heat. Laser action in silicon therefore requires another path. And exploring a fresh approach is what ETH doctoral researcher David Stark and his colleagues are doing. They work towards a silicon-based quantum cascade laser (QCL). QCLs achieve light emission not by electron-hole recombination across the bandgap, but by letting electrons tunnel through repeated stacks of precisely engineered semiconductor structures, during which process photons are emitted.

The QCL paradigm has been demonstrated in a number of materials—for the first time in 1994 by a team including Jérôme Faist, then working at Bell Laboratories in the US—but never in silicon-based ones, despite promising predictions. Turning these predictions into reality is the focus of an interdisciplinary project funded by the European Commission, bringing together a team of leading experts in growing highest-quality semiconductor materials (at the Università Roma Tre), characterizing them (at the Leibniz-Institut für innovative Mikroelektronik in Frankfurt an der Oder) and fabricating them into devices (at the University of Glasgow). The ETH group of Scalari and Faist is responsible for performing the measurements on the devices, but also for the design of the laser, with numerical and theoretical support from partners in the company nextnano in Munich and at the Universities of Pisa and Rome.

As electrons tunnel through the Ge/SiGe heterostructure, they emit light, currently at two slightly different frequencies, due to suboptimal injection in the upper state of the radiative transition. Credit: ETH Zurich/David Stark

From electroluminescence to lasing

With this bundled knowledge and expertise, the team designed and built devices with a unit structure made of SiGe and pure germanium (Ge), less than 100 nanometres in height, which repeats 51 times. From these heterostructures, fabricated with essentially atomically precision, Stark and co-workers detected electroluminescence, as predicted, with the spectral features of the emerging light agreeing well with calculations. Further confidence that the devices work as intended came from a comparison with a GaAs-based structure that was fabricated with identical device geometry. Whereas the emission from the Ge/SiGe structure is still significantly lower than for its GaAs-based counterpart, these results clearly signal that the team is on the right track. The next step will be now to assemble similar Ge/SiGe structures according to a laser design that the team developed. The ultimate goal is to reach room-temperature operation of a silicon-based QCL.

Such an achievement would be significant in several respects. Not only would it, at long last, realize a laser on a silicon substrate, thereby bringing a boost to photonics. The emission of the structure created by Stark et al. is in the terahertz region, for which currently compact light sources are widely missing. Silicon-based QCLs, with their potential versatility and reduced fabrication cost, could be a boon for the large-scale use of terahertz radiation in existing and new fields of application, from medical imaging to wireless communication.



More information:
David Stark et al, THz intersubband electroluminescence from n-type Ge/SiGe quantum cascade structures, Applied Physics Letters (2021). DOI: 10.1063/5.0041327

Citation:
Key step reached to­ward long-​sought goal of a silicon-​based laser (2021, March 8)
retrieved 10 March 2021
from https://phys.org/news/2021-03-key-long-sought-goal-silicon-based-laser.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no

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Hexbyte Glen Cove A better way to measure acceleration thumbnail

Hexbyte Glen Cove A better way to measure acceleration

Hexbyte Glen Cove

Illustration of an optomechanical accelerometer, which uses light to measure acceleration. The NIST device consists of two silicon chips, with infrared laser light entering at the bottom chip and exiting at the top. The top chip contains a proof mass suspended by silicon beams, which enables the mass to move up and down freely in response to acceleration. A mirrored coating on the proof mass and a hemispherical mirror attached to the bottom chip form an optical cavity. The wavelength of the infrared light is chosen so that it nearly matches the resonant wavelength of the cavity, enabling the light to build in intensity as it bounces back and forth between the two mirrored surfaces many times before exiting. When the device experiences an acceleration, the proof mass moves, changing the length of the cavity and shifting the resonant wavelength. This alters the intensity of the reflected light. An optical readout converts the change in intensity into a measurement of acceleration. Credit: F. Zhou/NIST

You’re going at the speed limit down a two-lane road when a car barrels out of a driveway on your right. You slam on the brakes, and within a fraction of a second of the impact an airbag inflates, saving you from serious injury or even death.

The airbag deploys thanks to an —a sensor that detects sudden changes in velocity. Accelerometers keep rockets and airplanes on the correct flight path, provide navigation for self-driving cars, and rotate images so that they stay right-side up on cellphones and tablets, among other essential tasks.

Addressing the increasing demand to accurately measure acceleration in smaller navigation systems and other devices, researchers at the National Institute of Standards and Technology (NIST) have developed an accelerometer a mere millimeter thick that uses laser light instead of mechanical strain to produce a signal.

Although a few other accelerometers also rely on light, the design of the NIST instrument makes the measuring process more straightforward, providing higher accuracy. It also operates over a greater range of frequencies and has been more rigorously tested than similar devices.

Not only is the NIST device, known as an optomechanical accelerometer, much more precise than the best commercial accelerometers, it does not need to undergo the time-consuming process of periodic calibrations. In fact, because the instrument uses of a known frequency to measure acceleration, it may ultimately serve as a portable reference standard to calibrate other accelerometers now on the market, making them more accurate.

The accelerometer also has the potential to improve inertial navigation in such critical systems as military aircraft, satellites and submarines, especially when a GPS signal is not available. NIST researchers Jason Gorman, Thomas LeBrun, David Long and their colleagues describe their work in the journal Optica.

The study is part of NIST on a Chip, a program that brings the institute’s cutting-edge measurement-science technology and expertise directly to users in commerce, medicine, defense and academia.

Accelerometers, including the new NIST device, record changes in velocity by tracking the position of a freely moving , dubbed the “proof mass,” relative to a fixed reference point inside the device. The distance between the proof mass and the reference point only changes if the accelerometer slows down, speeds up or switches direction. The same is true if you’re a passenger in a car. If the car is either at rest or moving at constant velocity, the distance between you and the dashboard stays the same. But if the car suddenly brakes, you’re thrown forward and the distance between you and the dashboard decreases.

The motion of the proof mass creates a detectable signal. The accelerometer developed by NIST researchers relies on infrared light to measure the change in distance between two highly reflective surfaces that bookend a small region of empty space. The proof mass, which is suspended by flexible beams one-fifth the width of a human hair so that it can move freely, supports one of the mirrored surfaces. The other reflecting surface, which serves as the accelerometer’s fixed reference point, consists of an immovable microfabricated concave mirror.

Together, the two reflecting surfaces and the empty space between them form a cavity in which infrared light of just the right wavelength can resonate, or bounce back and forth, between the mirrors, building in intensity. That wavelength is determined by the distance between the two mirrors, much as the pitch of a plucked guitar depends on the distance between the instrument’s fret and bridge. If the proof mass moves in response to acceleration, changing the separation between the mirrors, the resonant wavelength also changes.

To track the changes in the cavity’s resonant wavelength with high sensitivity, a stable single-frequency laser is locked to the cavity. As described in a recent publication in Optics Letters, the researchers have also employed an optical frequency comb—a device that can be used as a ruler to measure the wavelength of light—to measure the cavity length with high accuracy. The markings of the ruler (the teeth of the comb) can be thought of as a series of lasers with equally spaced wavelengths. When the proof mass moves during a period of acceleration, either shortening or lengthening the cavity, the intensity of the reflected light changes as the wavelengths associated with the comb’s teeth move in and out of resonance with the cavity.

Accurately converting the displacement of the proof mass into an acceleration is a critical step that has been problematic in most existing optomechanical accelerometers. However, the team’s new design ensures that the dynamic relationship between the displacement of the proof mass and the acceleration is simple and easy to model through first principles of physics. In short, the proof mass and supporting beams are designed so that they behave like a simple spring, or harmonic oscillator, that vibrates at a single frequency in the operating range of the accelerometer.

This simple dynamic response enabled the scientists to achieve low measurement uncertainty over a wide range of acceleration frequencies—1 kilohertz to 20 kilohertz—without ever having to calibrate the device. This feature is unique because all commercial accelerometers have to be calibrated, which is time-consuming and expensive. Since the publication of their study in Optica, the researchers have made several improvements that should decrease their device’s uncertainty to nearly 1%.

Capable of sensing displacements of the proof mass that are less than one hundred-thousandth the diameter of a hydrogen atom, the optomechanical accelerometer detects accelerations as tiny as 32 billionths of a g, where g is the acceleration due to Earth’s gravity. That’s a higher sensitivity than all accelerometers now on the market with similar size and bandwidth.

With further improvements, the NIST optomechanical accelerometer could be used as a portable, high-accuracy reference device to calibrate other accelerometers without having to bring them into a laboratory.



More information:
Feng Zhou et al, Broadband thermomechanically limited sensing with an optomechanical accelerometer, Optica (2021). DOI: 10.1364/OPTICA.413117

D. A. Long et al. Electro-optic frequency combs for rapid interrogation in cavity optomechanics, Optics Letters (2020). DOI: 10.1364/OL.405299

Citation:
A better way to measure acceleration (2021, March 8)
retrieved 10 March 2021
from https://phys.org/news/2021-03-a-better-way-to-measure.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

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