Hexbyte Glen Cove Once again, volcanic Caribbean island looks to recovery thumbnail

Hexbyte Glen Cove Once again, volcanic Caribbean island looks to recovery

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In this 1902 photo provided by York Museums Trust, men survey the devastation of the landscape following eruptions of La Soufrière, a volcano on the island of St. Vincent in the Caribbean. On April 9, 2021, La Soufriere once again started spewing hot torrents of gas, ash and rock, forcing thousands to evacuate to government-run shelters and private homes. (Tempest Anderson/York Museums Trust via AP)

A group of nervous fish sellers got very close to La Soufrière, the volcano on the Caribbean island of St. Vincent, on the morning of May 7, 1902.

“The top of the mountain was covered in mist, and the foremost of them followed the path up to the base of the summit cone,” according to a written account of their experience. “Some went up to quite near the lip of the crater, or possibly even to the actual edge. What they saw there was enough to dismay the stoutest hearts.″

The volcano was about to erupt explosively, devastating swathes of the island. Last week, La Soufrière once again started spewing hot torrents of gas, ash and rock, forcing thousands to evacuate to government-run shelters and private homes.

Things look bleak, even if there are no reported casualties. Crops, fishing and other livelihoods are in peril. The pandemic was already battering the economy, including tourism. Still, regional aid is arriving, the United Nations plans to help, and the 1902 catastrophe is a reminder that St. Vincent recovered from massive eruptions in the past.

Recovery this time could take years, requiring sustained support from around the Caribbean and beyond, said Jenni Barclay, a volcanology professor at the University of East Anglia in Britain who co-authored a study on the impact, relief and response of the 1902-3 eruptions.

“The most important thing is making effective use of the resources that they do have, some of the resources that are actually just the ingenuity and the resilience of the people on the island,” Barclay said.

St. Vincent is the biggest of the islands forming St. Vincent and the Grenadines, which gained independence from Britain in 1979 and has a population of about 110,000. In 1902, the warnings of the fish sellers who experienced the volcano up close—the thick steam, the scorched vegetation, the sulfurous smell, the constant shaking—were at first dismissed.

″They were received with incredulity, and when they came to Georgetown they were scoffed at as fools and cowards,″ according to an account of the disaster commissioned by the Royal Society of London and published in 1903. The authors were Tempest Anderson, an ophthalmologist deeply interested in volcanoes, and geologist John Flett.

The names of the fish sellers are not included in the report about what happened on St. Vincent, where a white minority dominated a population that included the descendants of Indigenous inhabitants and enslaved Africans.

In this 1902 photo provided by York Museums Trust, the seared landscape is seen following the eruptions of La Soufrière, a volcano on the island of St. Vincent in the Caribbean. The 1902 catastrophe is a reminder that St. Vincent recovered from massive eruptions in the past. (Tempest Anderson/York Museums Trust via AP)

Clouds and a poor line of sight to the volcano top from the sugar cane plantations and places like Georgetown on the eastern side of St. Vincent contributed to uncertainty about what was happening. To the west, people had no doubt. They prepared to flee while watching an enormous column of vapor billow into a mushroom-shaped cloud, accompanied by showers of black, heavy material, and lightning and thunder.

(On April 8 of this year, the government ordered an evacuation of the 20,000 people living in the northern “red zone″ near La Soufrière following increasing volcanic and seismic activity. The started the next day).

In the 1902 climax, a ″Great Black Cloud″ raced down the volcano’s slopes, swept over homes and farms and surged out to sea, raining scalding ash, stones and sulfurous fumes on boats of people rowing furiously away.

On the east of St. Vincent, plantation workers gazed in amazement as the implacable black curtain descended toward them, then rushed indoors or died in the open. At Orange Hill, dozens crammed into a rum cellar.

″One man stood by the door holding it ajar, to admit any who fled from the huts in the village. Forty were in the cellar, and all were saved. Thirty were in the passage leading into the cellar, and they were all killed,″ Anderson and Flett wrote.

An estimated 1,600 people died, though that cataclysm was eclipsed by eruptions, the worst on May 8, at Mount Pelée on the nearby French-held island of Martinique. At least 29,000 people died there.

Most of St. Vincent’s casualties were in the east, possibly and partly because workers on large plantations were less able to make an independent decision to flee, according to the study that Barclay co-authored.

La Soufrière’s continuing explosions hampered British-led recovery efforts for months, said the study, published in 2018. The eruptions accelerated the decline of the sugar industry, but other commodities recovered within a year or two, it said. New plants, including cacao, nutmeg and coffee, were introduced. Experimentation led to agricultural innovation.

The volcanic ash, which then and now spread as far as Barbados, about 110 miles (180 kilometers) away, nourished the soil. On Sunday, the Seismic Research Centre of the University of the West Indies posted a photo of St. Vincent coconut trees, fronds drooping under ash.

In this 1902 photo provided by York Museums Trust, residents are seen outside their home following explosive eruptions of La Soufrière volcano, in Chateaubelair, St. Vincent. Most of St. Vincent’s casualties from the volcano in 1902 were in the east, possibly and partly because workers on large plantations were less able to make an independent decision to flee, according to Jenni Barclay, a volcanology professor. (Tempest Anderson/York Museums Trust via AP)

″The impact on vegetation is devastating in the short term but beneficial in the long term,″ the group said.

The British navy delivered aid in 1902. The USS Dixie also brought relief, along with scientists and newspaper correspondents. In an account of the eruption build-up, The Boston Globe reported ”a noise like the monster guns of the world’s navy in perpetual action.”

In recent days, a navy ship from Venezuela, a nation long in the grip of shortages, delivered water and other supplies to St. Vincent. Caribbean island nations are sending aid.

The 1902 and 2021 eruptions are ”possibly on a par” in power and intensity, but it’s difficult to make a ”direct comparison” because a deep crater lake existed at the time of the earlier one, Barclay said.

When flowing magma hit the lake, vaporization created ”a huge additional extra energy and it generated pyroclastic density currents that were very fast-moving and deadly, early on in the eruptive sequence,” she said.

Daniel Defoe, author of ″Robinson Crusoe,″ is the purported writer of an account of an explosive eruption at La Soufrière in 1718, when Indigenous inhabitants effectively controlled the island. An 1812 eruption killed dozens, mostly enslaved Black people. Prior to this month, the last big eruption was during Easter 1979, causing mass evacuations but no deaths.

La Soufrière’s history could inform St. Vincent’s residents as they recover. In the meantime, unlike their ancestors, they are getting continual updates and guidance.

On Wednesday, emergency officials warned people not to play in covering St. Vincent. The ash contains tiny shards of rock and glass.

“Though ash may fall like snow,” they said, ”it is deadly.″



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Once again, volcanic Caribbean island looks to recovery (2021, April 17)
retrieved 18 April 2021
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Hexbyte Glen Cove Two Russian cosmonauts, NASA astronaut return from ISS thumbnail

Hexbyte Glen Cove Two Russian cosmonauts, NASA astronaut return from ISS

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For the last decade, the space station’s population has varied between three and six as crews that blasted off from Russia’s Baikonur cosmodrome in Kazakhstan came and went. 

Two Russian cosmonauts and a NASA astronaut touched down Saturday on the steppe of Kazakhstan following a half-year mission on the International Space Station, footage broadcast by the Russian space agency showed.

Russia’s Sergei Ryzhikov and Sergei Kud-Sverchkov as well as NASA’s Kate Rubins landed on barren land at 0455 GMT around 150 kilometres (90 miles) southeast of the town of Zhezkazgan.

The Soyuz descent module carring the trio landed upright after descending through a cloudless sky on a fine spring day in central Kazakhstan, a Roscosmos TV commentator confirmed.

Molecular biologist Rubins, 42, and former military pilot Ryzhikov, 46, were rounding off their second missions in space having both made their ISS debuts following launches in July and October of 2016 respectively.

Kud’-Sverchkov, 39, another ex-military man, was completing his first mission.

Footage from the landing site showed Rubins smiling as she received a bouquet of flowers from retired cosmonaut Yuri Malenchenko, who was there to greet the crew.

“It is great to be on this side of things,” Rubins said.

She will return to NASA’s hub in Houston while colleagues Ryzhikov and Kud-Sverchkov are bound for Moscow as they wind down their missions.

During her debut mission in 2016, Rubins became the first person to sequence DNA in space.

In her second mission she continued her sequencing activities, worked on cariovascular experiments and oversaw a small patch of radishes “as they grew in orbit… harvesting them for analysis back on Earth”, according to NASA.

Busy orbital lab

For the last decade, the space station’s population has typically varied between three and six as crews that blasted off from Russia’s Baikonur cosmodrome in Kazakhstan came and went.

Entrepreneur Elon Musk’s SpaceX last year broke the monopoly that Russia and Baikonur had held on manned launches since the mothballing of the US shuttle programme in 2011, beginning a new chapter of spaceflight from US soil.

As a result the number of crew on board will reach 11 next week with the arrival of NASA’s SpaceX Crew-2 mission.

NASA’s Shane Kimbrough and Megan McArthur, Japanese astronaut Akihiko Hoshide, and Thomas Pesquet of the European Space Agency are expected to dock with the ISS next Friday, with the four-person crew they are replacing scheduled to return to Earth on April 28.

The absolute record for people aboard the ISS was set in 2009, when an arriving crew took the orbital lab’s population to 13.

That is also the joint all-time record for the most people in space at any one time after seven astronauts were aboard the NASA space shuttle Endeavour and a six-man crew was aboard the Mir space station simultaneously in March 1995.

Continuously occupied for more than 20 years, the ISS is expected to be retired before the end of the decade, raising questions about future cooperation between Russia and the West in space.

NASA on Friday said it had selected SpaceX to develop a spacecraft to land the first astronauts on the surface of the Moon since 1972—a huge victory for Elon Musk’s company.

April 12 marked the sixtieth anniversary of Soviet cosmonaut Yuri Gagarin’s historic marking the beginning of human spaceflight and a key moment in the race between Moscow and the West.

Since the fall of the Soviet Union there has been more cooperation than competition, although it is difficult to disguise the appearance that Roscosmos and NASA are going their separate ways as the ISS winds down.



© 2021 AFP

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Two Russian cosmonauts, NASA astronaut return from ISS (2021, April 17)
retrieved 18 April 2021
from https://phys.org/news/2021-04-russian-cosmonauts-nasa-astronaut-iss.html

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Hexbyte Glen Cove NASA chooses SpaceX to take humans back to Moon thumbnail

Hexbyte Glen Cove NASA chooses SpaceX to take humans back to Moon

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For its Moon lander bid, SpaceX put forward its reuseable Starship spacecraft

NASA has selected SpaceX to land the first astronauts on the surface of the Moon since 1972, the agency said Friday, in a huge victory for Elon Musk’s company.

The contract, worth $2.9 billion, involves the prototype Starship spacecraft that is being tested at SpaceX’s south Texas facility.

“Today I’m very excited, and we are all very excited to announce that we have awarded SpaceX to continue the development of our integrated human landing system,” said Lisa Watson-Morgan, NASA’s Human Landing System program manager.

SpaceX beats out Jeff Bezos’ Blue Origin and defense contractor Dynetics to be the sole provider for the system, a surprising break from the past when NASA has chosen multiple companies in case one fails.

Industry analysts said the decision underscores the company, founded by Musk in 2002 with the goal of colonizing Mars, as NASA’s most trusted private sector partner.

Last year, SpaceX became the first private firm to successfully send a crew to the International Space Station, restoring American capacity to accomplish the feat for the first time since the Shuttle program ended.

For its Moon lander bid, SpaceX put forward its reusable Starship spacecraft, which is designed to carry large crews and cargo for deep space voyages, and land upright both on Earth and other celestial bodies.

Prototypes of the vessel are currently being put through their paces at the company’s south Texas facility, though all four versions that have so far attempted test flights have exploded.

Under the Artemis program to return humans to the Moon, NASA wants to use the Space Launch System rocket to launch four astronauts on board an Orion crew capsule, which will then dock with a lunar space station called Gateway.

Starship will be waiting to receive two crew members for the final leg of the journey to the surface of the Moon.

The idea is for Gateway to be the go-between but for the initial mission Orion might dock directly with Starship, Watson-Morgan said.

The astronauts would then spend a week on the Moon before boarding Starship to return to lunar orbit, then take Orion back to Earth.

Separately, SpaceX has plans to combine the Starship spaceship with its own Super Heavy rocket, to make a combined vessel that will tower 394 feet (120 meters) tall and be the most powerful launch vehicle ever deployed.

Humanity last stepped foot on the Moon in 1972 during the Apollo program.

NASA wants to go back and establish a sustainable presence, complete with a lunar space station, in order to test new technologies that will pave the way for a crewed mission to Mars.

In 2019, then vice president Mike Pence challenged NASA to land the first woman and the next man on the Moon by 2024, but it’s likely that timeline will be relaxed under President Joe Biden.

Another change under the current administration is its stated goal of placing the first person of color on the Moon under the Artemis program.



© 2021 AFP

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NASA chooses SpaceX to take humans back to Moon (2021, April 16)
retrieved 18 April 2021

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Hexbyte Glen Cove Oldest piece of writing ever found in Israel identified on ancient shard of pottery thumbnail

Hexbyte Glen Cove Oldest piece of writing ever found in Israel identified on ancient shard of pottery

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Hexbyte Glen Cove Fast radio bursts shown to include lower frequency radio waves than previously detected thumbnail

Hexbyte Glen Cove Fast radio bursts shown to include lower frequency radio waves than previously detected

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A burst from the periodically active repeating fast radio burst source 20180916B arrives at the LOFAR telescope. The higher frequency radio waves (purple) arrive earlier than the lower frequency radio waves (red). The inset shows an optical image from the host galaxy of the fast radio burst source and the position of the source in the host galaxy. Credit: Futselaar / ASTRON / Tendulkar

Since fast radio bursts (FRBs) were first discovered over a decade ago, scientists have puzzled over what could be generating these intense flashes of radio waves from outside of our galaxy. In a gradual process of elimination, the field of possible explanations has narrowed as new pieces of information are gathered about FRBs—how long they last, the frequencies of the radio waves detected, and so on.

Now, a team led by McGill University researchers and members of Canada’s CHIME Fast Radio Burst collaboration has established that FRBs include radio waves at frequencies lower than ever detected before, a discovery that redraws the boundaries for theoretical astrophysicists trying to put their finger on the source of FRBs.

“We detected down to 110 MHz where before these bursts were only known to exist down to 300 MHz,” explained Ziggy Pleunis, a postdoctoral researcher in McGill’s Department of Physics and lead author of the research recently published in the Astrophysical Journal Letters. “This tells us that the region around the source of the bursts must be transparent to low-frequency emission, whereas some theories suggested that all low-frequency emission would be absorbed right away and could never be detected.”

The study focussed on an FRB source first detected in 2018 by the CHIME radio telescope in British Columbia. Known as FRB 20180916B, the source has attracted particular attention because of its relative proximity to Earth and the fact that it emits FRBs at regular intervals.

The research team combined the capacities of CHIME with those of another radio telescope, LOFAR, or Low Frequency Array, in the Netherlands. The joint effort not only enabled the detection of the remarkably low FRB frequencies, but also revealed a consistent delay of around three days between the higher frequencies being picked up by CHIME and the lower ones reaching LOFAR.

“This systematic delay rules out explanations for the periodic activity that do not allow for the frequency dependence and thus brings us a few steps closer to understanding the origin of these mysterious bursts,” adds co-author Daniele Michilli, also a postdoctoral researcher in the Department of Physics at McGill.



More information:
Z. Pleunis et al, LOFAR Detection of 110–188 MHz Emission and Frequency-dependent Activity from FRB 20180916B, The Astrophysical Journal Letters (2021). DOI: 10.3847/2041-8213/abec72

Citation:
Fast radio bursts shown to include lower frequency radio waves than previously detected (2021, April 16)
retrieved 17 April 2021
from https://phys.org/news/2021-04-fast-radio-shown-frequency-previously.html

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Hexbyte Glen Cove You're not imagining it: 3 ways COVID-19 has been extra hard on American parents thumbnail

Hexbyte Glen Cove You’re not imagining it: 3 ways COVID-19 has been extra hard on American parents

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Credit: Chart: The Conversation, CC-BY-ND Source: UNC Covid Survey Project, Wave 3, September 2020

For over a year, Americans have been struggling with the challenges imposed on them by the global coronavirus pandemic. While all Americans have struggled, the pandemic has imposed three distinctive sets of burdens on the 64 million Americans living with children under the age of 18.

As those who have know firsthand, becoming a parent is a life-changing, challenging, long-term experience. Even before the , surveys showed that a majority of parents were struggling to balance their and their desire to spend quality time with their children.

Since March 2020, however, have had to negotiate their own workplace demands and other responsibilities with around-the-clock child care responsibilities. They have been spending hours every day helping their children navigate remote and hybrid schooling, while also taking on increased household tasks, like preparing multiple meals a day and cleaning more often because everyone is at home.

Stories in the have profiled specific families to illustrate powerfully how already overstretched parents are now taking on many more time-consuming responsibilities. Many parents feel they are failing to be good parents and not able to do their paying jobs well. In some cases, parents have had to leave their jobs to care for their children, even though this undermines their family’s financial security.

Profiles of specific families are eye-opening, but as social science researchers with extensive expertise in the American family, we looked at the broader picture. We have found that these anecdotes are indeed supported by nationally representative empirical data: This pandemic year has been harder for parents than almost anyone else, in terms of finances, physical health and mental health.

Finances and health

Life has been extra tough for parents in three specific ways, as shown in our analysis of national data on pandemic experiences, the UNC COVID Panel Study Wave 3, published in Social Science Quarterly.

People who are parents are more likely than those who do not have children to report losing their job during the pandemic. Parents are also more likely than those without children to report having experienced a worsening financial situation over the past year.

Parents are also more likely than those without children to report having had COVID-19. Why exactly this is the case is a question better answered by epidemiologists than by social scientists. But it seems plausible that the demands of parenthood are increasing parents’ risk.

When parents have to work outside the home to support their families, they must rely on others to care for their children. That means using day care, finding in-person schooling, paying a caregiver, or relying on friends and family. All of that is normal in nonpandemic times, but in a pandemic, every one of those options means expanding the pool of interpersonal contacts, increasing parents’ risk.

Fear was a constant factor this past year, for nearly everyone—but our research shows parents were more fearful and viewed COVID-19 as more of a threat than those without children. This finding is consistent with other research showing that parents, understandably, have a very strong desire to keep their children safe and that the act of caring for a child or children intensifies fears about possible threats.

The used in our research also included questions about mental health. Respondents were asked how often they have been bothered by feeling down, depressed or hopeless; feeling nervous, anxious or on edge; and not being able to stop worrying or control their worrying.

Parents were more likely than those without children to report experiencing these problems. Mothers were the most likely to indicate that they were depressed, anxious and worried—but fathers were also more likely to report these negative feelings than were men without kids.

School-related stress

Beyond these three major categories of problems, schooling decisions added to the strain on parents. Despite parents’ economic and psychological strain, just 14% of the survey respondents supported a return to fully in-person school for their children.

Surveyed early in the 2020-21 school year, the plurality of parents, 49%, supported online learning, and 37% supported a hybrid option, which inherently increases in-person contact and therefore the potential for disease to spread. Caught between a need to do their jobs to support their families and critical concerns about the health and safety of their children, parents are in many ways in an impossible situation.

While the data in and of itself does not offer solutions to the significant toll of the pandemic on parents, it does show that the problems faced by parents are real. Parents who have been feeling overwhelmed over the past year should know that they are not alone. The challenges of parenting during the pandemic are real and widespread.



This article is republished from The Conversation under a Creative Commons license. Read the original article.

Citation:
You’re not imagining it: 3 ways COVID-19 has been extra hard on American parents (2021, April 16)
retrieved 17 April 2021
from https://phys.org/news/2021-04-youre-ways-covid-extra-hard.html

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Hexbyte Glen Cove Snake species from different terrains surrender surface secrets behind slithering success thumbnail

Hexbyte Glen Cove Snake species from different terrains surrender surface secrets behind slithering success

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Credit: Pixabay/CC0 Public Domain

Some snake species slither across the ground, while others climb trees, dive through sand or glide across water. Today, scientists report that the surface chemistry of snake scales varies among species that negotiate these different terrains. The findings could have implications for designing durable materials, as well as robots that mimic snake locomotion to cross surfaces that would otherwise be impassable.

The researchers will present their results today at the spring meeting of the American Chemical Society (ACS).

The research began as a collaboration with Woodland Park Zoo in Seattle, explains Tobias Weidner, Ph.D., the project’s principal investigator. One of the zoo’s biologists told Weidner that not much was known about the chemistry of surfaces. “Biologists typically don’t have techniques that can identify molecules on the outermost layer of a such as a snake scale,” he says. “But I’m a chemist—a surface scientist—so I felt I could add something to the picture with my lab’s methods.”

In that initial project, the researchers discovered that land snakes are covered with a lipid layer. This oily layer is so thin—a mere one or two nanometers—that no one had noticed it before. The team also found that the molecules in this layer are disorganized on the snake’s back scales but highly organized and densely packed on belly scales, an arrangement that provides lubrication and protection against wear.

“Some people are afraid of snakes because they think they’re slimy, but biologists tell them snakes aren’t slimy; they’re dry to the touch,” Weidner says. “That’s true, but it’s also not true because at the nanoscale we found they actually are greasy and slimy, though you can’t feel it. They’re ‘nanoslimy.'”

In the new study, the team wanted to find out if this nanoslimy surface chemistry differs in species adapted to various habitats, says Mette H. Rasmussen, a graduate student who is presenting the latest findings at the meeting. Both Weidner and Rasmussen are at Aarhus University in Denmark.

Working with recently shed skins, Rasmussen compared the surface chemistry of ground, tree and sand snakes. She used laser spectroscopy and an electron microscopy technique that probes the chemistry of the surface by knocking electrons out of it with X-rays. The project was a collaboration with Joe Baio, Ph.D., at Oregon State University; Stanislav Gorb, Ph.D., at Kiel University and researchers at the U.S. National Institute of Standards and Technology.

Rasmussen found that the tree snake has a layer of ordered lipid molecules on its belly, just like the ground snake. But the sand snake, which dives through sand, has an ordered lipid layer on both its front and back. “From a snake’s point of view, it makes sense,” she says. “You would like to have this friction reduction and wear resistance on both sides if you’re surrounded by your environment instead of only moving across it.” Next, the researchers want to find out where the lipids come from and to look at variations across other snake species, including those that live in water. They would also like to identify the lipids, though Weidner suspects the chemical makeup of the is less important than the organization and density of the lipid molecules it contains.

The work could have broad applications. “A snake’s slithering locomotion requires constant contact with the surface it’s crossing, which poses stringent requirements for friction, wear and mechanical stability,” Rasmussen says. Learning how snakes maintain the integrity of their skin when encountering sharp rocks, hot sand and other challenges could help in the design of more .

In addition, the researchers say, multiple groups are developing robots that mimic a snake’s slithering or sidewinding locomotion and—unlike robots with wheels—can therefore negotiate difficult terrain such as steep, sandy slopes. These groups have recently begun taking into account the microstructure of snake scales, Rasmussen notes, but scales’ surface chemistry is also critical to their performance. Bringing these fields together could one day lead to snakelike robots capable of helping in rescue operations or freeing a Mars rover stuck in sand, she says.



More information:
Abstract Title: The surface chemistry of snake slithering locomotion

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Hexbyte Glen Cove Tunisia 'sandy' farms resist drought, development thumbnail

Hexbyte Glen Cove Tunisia ‘sandy’ farms resist drought, development

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Tunisian farmers in the small fishing town of Ghar El Melh are fighting to preserve a unique way of growing crops on sandy plots using a traditional, delicate irrigation system

Farmers near a seaside lagoon in northern Tunisia are fighting to preserve a unique, traditional irrigation system that has sparked renewed interest as North Africa’s water shortages intensify.

Retired schoolteacher Ali Garci wanders among tiny sandy plots, inspecting his potatoes, lettuces and onions.

“It’s not land that we cultivate for the profit it brings, but for the art and the pleasure,” says the 61-year-old, who works around a hectare (2.5 acres) inherited from his family.

Local farmers have used the “ramli” technique since the 17th century, when Muslims and Jews settled in North Africa after fleeing the Catholic reconquest of Andalusia.

Some found safety in Ghar El Melh, a small fishing town in Tunisia’s north.

But they had to battle a lack of cultivated land and water.

They learned to take advantage of the light, sandy soil, and the fact that underground freshwater, which is lighter than seawater, “floats” above the saltier groundwater below.

When rainwater from the hills reaches the sandy area around Ghar El Melh’s lagoons, instead of mixing immediately with the brine below, it forms a thin layer of fresh groundwater.

Twice a day, the tides of the nearby Mediterranean raise the level of both, bringing precious freshwater in contact with the vegetables in the ramli plots.

“It’s as if the sea is suckling its young,” said Abdelkarim Gabarou, who has worked the traditional plots for more than 40 years.

Tunisian farmers have learned to take advantage of the light, sandy soil and the fact that underground freshwater floats above the saltier, heavier groundwater below providing crucial water for crops

‘Every drop of water’

The ramli farms—ramli is Arabic for “sandy”—cover around 200 hectares (500 acres) and support around 300 people.

They were listed last year in the UN Food and Agriculture Organization’s (FAO) list of Globally Important Agricultural Heritage Systems.

The FAO said the ramli system was “unique not only in Tunisia but in the whole world”.

Ramli produce is said to have a particular taste, and is in high demand both locally and in Tunis.

But farmers voice regret that their products lack formal certification, despite the FAO designation.

They must also contend with growing threats to their unique farming system, both from and development.

As rainfall becomes less regular and sea levels rise, the ramli farmers’ delicate dance with nature is becoming harder.

“We’re totally dependent on rainwater,” Garci said. “We try to preserve it in the most natural way possible.”

Known as ‘ramli’ farms, this delicate balance with nature is under threat as rainfall becomes less regular due to climate change

For the system to work, the roots of the vegetables must reach freshwater but also, crucially, not the saltwater below.

That requires precisely the right amount of sand above: a layer exactly 40 centimetres (15-and-a-half inches) thick.

Raoudha Gafrej, an expert on and climate change, says it would be near-impossible to reproduce the ramli system elsewhere.

“This ingenious system doesn’t cover a huge area… but we have to preserve it, because the country needs every drop of water it can get,” she said.

Valuable real estate

Unlike in other parts of Tunisia, these farms thrive all year round without artificial irrigation, allowing the farmers to produce up to 20 tonnes (22 tons) of crops per year.

Reeds protect the plots, just four metres wide, from wind and erosion, but shielding them from human activity is another matter.

This beautiful coastline, where a long strip of white sand separates the lagoon from the sea, is popular with holidaymakers.

Retired Tunisian school teacher Ali Garci farms a plot of land inherited from his family and says this traditional form of agriculture recognised by the UN as a globally important heritage is ‘totally dependant on rainwater’

“Lots of farmers are thinking of selling their land for good prices, to people who want to build houses overlooking the sea and the hills,” said Garci.

Meanwhile, he says, very few young Tunisians want to become farmers.

But in a country where 80 percent of water goes to irrigation, any effort to make more efficient use of water is valuable.

On the Tunisian island of Djerba, where summer water outages are common, an NGO recently renovated 15 ancient reservoirs to collect rainwater for irrigation in the drier months.

Gafrej said such efforts were vital.

“We need to help this culture of preservation to take root,” she said.



© 2021 AFP

Citation:
Tunisia ‘sandy’ farms resist drought, development (2021, April 15)
retrieved 15 April 2021
from https://phys.org/news/2021-04-tunisia-sandy-farms-resist-drought.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 Lipid research may help solve COVID-19 vaccine challenges thumbnail

Hexbyte Glen Cove Lipid research may help solve COVID-19 vaccine challenges

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University of Texas at Dallas scientists developed a method to stabilize liposomes in a crystalline exoskeleton, which allows the biomolecules to remain stable at room temperature. This illustration depicts a proteoliposome — a spherical bilayer of fat molecules (white and blue) — stabilized in a structure called a zeolitic-imidazole framework composed of zinc acetate and methylimidazole. Inserted into the lipid bilayer — which mimics a cell membrane — are modeled structures of CopA proteins, with a section (in pink) that resides inside the lipid and sections above the lipid surface (brown) and slightly inside the liposome (also brown, but inside). Credit: University of Texas at Dallas

New research by University of Texas at Dallas scientists could help solve a major challenge in the deployment of certain COVID-19 vaccines worldwide—the need for the vaccines to be kept at below-freezing temperatures during transport and storage.

In a study published online April 13 in Nature Communications, the researchers demonstrate a new, inexpensive technique that generates crystalline exoskeletons around delicate liposomes and other nanoparticles and stabilizes them at room temperature for an extended period—up to two months—in their proof-of-concept experiments.

The Moderna and Pfizer/BioNTech COVID-19 vaccines use lipid nanoparticles—basically spheres of fat molecules—to protect and deliver the messenger RNA that generates a vaccine recipient’s immune response to the SARS-CoV-2 virus.

“The expense of keeping these vaccines very cold from the time they’re made to the time they’re delivered is a challenge that needs to be addressed, especially because many countries don’t have sufficient infrastructure to maintain this kind of cold chain,” said Dr. Jeremiah Gassensmith, associate professor of chemistry and biochemistry and of bioengineering at UT Dallas and a corresponding author of the study. “Although we did not include in this work the specific used in current COVID-19 vaccines, our findings are a step toward stabilizing a lipid nanoparticle in a way that’s never been done before, so far as we know.”

The idea for the research project began during a coffee-break discussion between Gassensmith and Dr. Gabriele Meloni, a corresponding co-author of the study and assistant professor of chemistry and biochemistry in the School of Natural Sciences and Mathematics at UT Dallas.

Gassensmith’s area of expertise is biomaterials and , while Meloni’s research focus is transmembrane transporter proteins. These proteins reside within cell membranes and are crucial for moving a variety of small molecules, including ions and trace metals, in and out of cells for several purposes.

“Membrane proteins sit in a , which is a lipid bilayer,” Meloni said. “To study their structure and biophysical and biochemical properties, we must extract these proteins from the membrane using detergents and then reconstitute them back into an artificial membrane—a proteoliposome—that mimics the proteins’ natural environment.”

Shell Creation

Lipid nanoparticles and liposomes are similar in structure, and neither are thermodynamically stable at room temperature, Gassensmith said. The lipid structures can fuse or aggregate, exposing any embedded or cargo to degradation.

“One of the challenges in my field of research is that both membrane proteins and lipid bilayers are very delicate and intrinsically metastable, and we’re trying to combine them in order to understand how these proteins function,” Meloni said. “We have to handle them carefully and prepare them fresh each time. They cannot be stored for long periods and are not easily shipped to colleagues in other labs.”

The researchers joined forces to develop a methodology to stabilize this kind of lipid system and demonstrated their results using transmembrane proteins from Meloni’s lab as a case study.

They mixed liposomes—some with embedded proteins, some without—with a combination of two inexpensive chemicals, zinc acetate and methylimidazole, in a buffer solution. In about a minute, a crystal matrix began to form around individual liposomes.

“We think that the lipids interact with the zinc just strongly enough to form an initial zinc-methylimidazole structure that then grows around the lipid sphere and completely envelops it, like an exoskeleton,” Gassensmith said. “It’s analogous to biomineralization, which is how certain animals form shells. We sort of co-opted nature in creating this totally fake shell, where the biomacromolecules—the lipids and proteins—catalyze the growth of this exoskeleton.”

The ability of biomimetic shells to form around biological molecules is not new, Gassensmith said, but the process hasn’t worked well with lipids or liposomes because the metal salts that comprise the shell material suck water out of the liposomes by osmosis and cause them to explode.

“One of the keys to this research was identifying the buffer solution in which everything resides,” Gassensmith said.

Building a Buffer

Three graduate students collaborated on the project to develop the unique buffer medium that allows the reaction to occur.

“The buffer medium maintains the ionic strength of the solution and keeps the pH stable so that when you add a huge amount of metal salts, it doesn’t osmotically shock the system,” said Fabián Castro BS’18, a chemistry doctoral student in Gassensmith’s lab and a lead author of the study.

Castro and co-lead authors Sameera Abeyrathna and Nisansala Abeyrathna, chemistry doctoral students (and siblings) in Meloni’s lab, worked together to develop the buffer formulation.

Once the biomolecules have grown a shell, they are locked in, and the lipids remain stable. While the exoskeleton is very stable, it has a fortuitous Achilles’ heel.

“The shell will dissolve if it encounters something that is attracted to zinc,” Gassensmith said. “So, to release and reconstitute the liposomes, we used a zinc chelating factor called EDTA (ethylenediaminetetraacetic acid), which is a common, inexpensive food additive and medicine used to treat lead poisoning.”

In addition to the laboratory experiments, in another proof-of concept exercise, Gassensmith mailed through the U.S. Postal Service a sample of the stabilized lipid particles to his mother in Rhode Island. She shipped them back to Texas, but because the COVID-19 pandemic forced the shutdown of most UT Dallas research labs in 2020, the samples sat untouched for about two months until the graduate students returned to campus to examine them. Although the informal experiment lasted much longer than the researchers had expected, the samples survived and functioned “just fine,” Gassensmith said.

“This project required two different types of expertise—my group’s expertise in membrane transport proteins and Dr. Gassensmith’s long track record working with metal-organic frameworks,” Meloni said. “Our success clearly demonstrates how such collaborative research can bring about novel and useful results.”



More information:
Fabian C. Herbert et al, Stabilization of supramolecular membrane protein–lipid bilayer assemblies through immobilization in a crystalline exoskeleton, Nature Communications (2021). DOI: 10.1038/s41467-021-22285-y

Citation:
Lipid research may help solve COVID-19 vaccine challenges (2021, April 15)
retrieved 15 April 2021
from https://phys.org/news/2021-04-lipid-covid-vaccine.html

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Hexbyte Glen Cove Dueling evolutionary forces drive rapid evolution of salamander coloration thumbnail

Hexbyte Glen Cove Dueling evolutionary forces drive rapid evolution of salamander coloration

Hexbyte Glen Cove

Spotted salamanders are a widespread species across the eastern United States that return to temporary ponds in the spring to breed. Credit: Sean Giery, Penn State

Two opposing evolutionary forces explain the presence of the two different colors of spotted salamander egg masses at ponds in Pennsylvania, according to a new study led by a Penn State biologist. Understanding the processes that maintain biological diversity in wild populations is a central question in biology and may allow researchers to predict how species will respond to global change.

Spotted salamanders (Ambystoma maculatum) are a widespread species that occur across the eastern United States and return to temporary ponds in the spring to reproduce. Female salamanders lay their in clumps called egg masses, which are either opaque white or completely clear. Females lay the same color egg masses throughout their life, but it is unclear what causes the different coloration, or if either of these colors confers an advantage to the eggs—for example if one color is less obvious to predators.

“We usually think of evolution operating over hundreds or thousands of years, but in reality, the at play in a system can influence each generation of animals,” said Sean Giery, Eberly Postdoctoral Research Fellow at Penn State and leader of the research team. “In this study, we resurveyed ponds that were originally studied in the early 1990s, which gave us a unique opportunity to explore the evolutionary processes that shape the frequencies of the two egg mass color types, or morphs, that we see today.”

Giery resurveyed a network of 31 ponds in central Pennsylvania, noting the color of salamander egg masses as well as environmental characteristics at each pond. The ponds were originally surveyed in 1990 and 1991 by then Penn State Professor of Biology Bill Dunson and his students. The new study appears April 14 in the journal Biology Letters.

The research team found that salamander population sizes and pond chemistry remained stable over the last three decades. When averaged across the region, the overall frequency of each egg color morph also remained the same—about 70% white egg masses in both 1990 and 2020—but in many cases the frequency within individual ponds changed drastically.

“At the scale of individual ponds, it’s an extremely dynamic system,” said Giery. “They don’t just reach one frequency and stay there. By focusing on individual ponds rather than just the region as a whole, we could tease apart what is driving these changes in population frequencies. In this case, we found two opposing evolutionary processes—selection and drift.”

Two opposing evolutionary forces help explain why we see two different colors of spotted salamander egg masses in ponds in central Pennsylvania, according to a new study. Egg masses are either completely clear or opaque white. Credit: Mark Urban, University of Connecticut

The researchers uncovered strong signatures of an evolutionary process called genetic drift, which can result in morph frequencies changing due to chance. In small populations, drift is more likely to have a major effect, for example with one of the morphs disappearing entirely. As expected due to drift, the researchers found that the frequencies of each morph changed more dramatically in ponds with fewer egg masses.

“However, none of the ponds completely shifted to one morph or the other, which suggests something else might also be going on,” said Giery. “We found that ponds at the extremes in the 1990s—with a high frequency of clear or a high frequency of white egg masses—became less extreme, shifting toward the overall mean for the region. This supports the idea that ‘balancing selection’ is operating in this system.”

Balancing selection is a type of natural selection that can help preserve multiple traits or morphs in a population. According to Giery, one possible explanation for balancing selection in egg mass color is that the rare morph in a —regardless of the actual color—has an advantage, which would lead to the rare morph becoming more common. Another possibility is that the white morph has an advantage in some ponds while the clear morph has an advantage in others, and movement of salamanders between the ponds leads to the persistence of both morphs.

“Ultimately we found a tension between these two evolutionary processes, with potentially leading to a reduction of diversity in this system, and balancing selection working to maintain it,” said Giery.

The researchers are currently surveying egg masses in ponds outside of Pennsylvania to explore if morph frequencies differ in other regions and whether these evolutionary processes operate in the same way over a larger scale.

“Although we did not see a relationship between egg mass color and environmental characteristics in this study, it’s possible that environmental characteristics at a larger scale might drive an optimal frequency for each region,” said Giery. “By looking at a much larger scale, we can get a better idea of whether there are regional optimums and how they are maintained. Understanding the processes that maintain may ultimately help us predict how wild animals will adapt in our changing world.”



More information:
Balancing selection and drift in a polymorphic salamander metapopulation, Biology Letters, royalsocietypublishing.org/doi … .1098/rsbl.2020.0901

Citation:
Dueling evolutionary forces drive rapid evolution of salamander coloration (2021, April 13)
retrieved 14 April 2021
from https://phys.org/news/2021-04-dueling-evolutionary-rapid-evolution-salamander.html

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