Webb captures a cosmic tarantula

by European Space Agency

In this mosaic image stretching 340 light-years across, Webb’s Near-Infrared Camera 

(NIRCam) displays the Tarantula Nebula star-forming region in a new light, including tens 

of thousands of never-before-seen young stars that were previously shrouded in cosmic 

dust. The most active region appears to sparkle with massive young stars, appearing pale

 blue. Scattered among them are still-embedded stars, appearing red, yet to emerge from 

the dusty cocoon of the nebula. NIRCam is able to detect these dust-enshrouded stars 

thanks to its unprecedented resolution at near-infrared wavelengths. To the upper left of 

the cluster of young stars, and the top of the nebula’s cavity, an older star prominently 

displays NIRCam’s distinctive eight diffraction spikes, an artifact of the telescope’s structure

. Following the top central spike of this star upward, it almost points to a distinctive bubble

 in the cloud. Young stars still surrounded by dusty material are blowing this bubble, 

beginning to carve out their own cavity. Astronomers used two of Webb’s spectrographs to

 take a closer look at this region and determine the chemical makeup of the star and its 

surrounding gas. This spectral information will tell astronomers about the age of the 

nebula and how many generations of star birth it has seen. Farther from the core region of 

hot young stars, cooler gas takes on a rust color, telling astronomers that the nebula is 

rich with complex hydrocarbons. This dense gas is the material that will form future stars.

 As winds from the massive stars sweep away gas and dust, some of it will pile up and, 

with gravity’s help, form new stars. 

Credit: NASA, ESA, CSA, and STScI

Thousands of never-before-seen young stars are spotted in a stellar nursery called 30 Doradus, captured by the NASA/ESA/CSA James Webb Space Telescope. Nicknamed the Tarantula Nebula for the appearance of its dusty filaments in previous telescope images, the nebula has long been a favorite for astronomers studying star formation. In addition to young stars, Webb reveals distant background galaxies, as well as the detailed structure and composition of the nebula's gas and dust

At only 161,000 light-years away in the Large Magellanic Cloud galaxy, the Tarantula Nebula is the largest and brightest star-forming region in the Local Group, the galaxies nearest to our Milky Way. It is home to the hottest, most massive stars known. Astronomers focused three of Webb's high-resolution infrared instruments on the Tarantula. Viewed with Webb's Near-Infrared Camera (NIRCam), the region resembles a burrowing tarantula's home, lined with its silk. The nebula's cavity centered in the NIRCam image has been hollowed out by blistering radiation from a cluster of massive young stars, which sparkle pale blue in the image. Only the densest surrounding areas of the nebula resist erosion by these stars' powerful stellar winds, forming pillars that appear to point back toward the cluster. These pillars contain forming protostars, which will eventually emerge from their dusty cocoons and take their turn shaping the nebula.

Credit: European Space Agency

Webb's Near-Infrared Spectrograph (NIRSpec) caught one very young star doing just that. Astronomers previously thought this star might be a bit older and already in the process of clearing out a bubble around itself. However, NIRSpec showed that the star was only just beginning to emerge from its pillar and still maintained an insulating cloud of dust around itself. Without Webb's high-resolution spectra at infrared wavelengths, this episode of star formation-in-action could not have been revealed.

Webb’s Near-Infrared Spectrograph (NIRSpec) reveals what is really going on in an 

intriguing region of the Tarantula Nebula. Astronomers focused the powerful instrument 

on what looked like a small bubble feature in the image from Webb’s Near-Infrared 

Camera (NIRCam). However, the spectra reveal a very different picture from a young star 

blowing a bubble in its surrounding gas. The signature of atomic hydrogen, shown in blue, 

shows up in the star itself but not immediately surrounding it. Instead, it appears outside 

the “bubble,” which spectra show is actually “filled” with molecular hydrogen (green) and 

complex hydrocarbons (red). This indicates that the bubble is actually the top of a dense 

pillar of dust and gas that is being blasted by radiation from the cluster of massive young 

stars to its lower right (see the full NIRCam image). It does not appear as pillar-like as 

some other structures in the nebula because there is not much color contrast with the 

area surrounding it. The harsh stellar wind from the massive young stars in the nebula is

 breaking apart molecules outside the pillar, but inside they are preserved, forming a

 cushy cocoon for the star. This star is still too young to be clearing out its surroundings by

 blowing bubbles – NIRSpec has captured it just beginning to emerge from the protective

 cloud from which it was formed. Without Webb’s resolution at infrared wavelengths, the 

discovery of this star birth in action would not have been possible. 

Credit: NASA, ESA, CSA, and STScI

The region takes on a different appearance when viewed in the longer infrared wavelengths detected by Webb's Mid-infrared Instrument (MIRI). The hot stars fade, and the cooler gas and dust glow. Within the stellar nursery clouds, points of light indicate embedded protostars, still gaining mass. While shorter wavelengths of light are absorbed or scattered by dust grains in the nebula, and therefore never reach Webb to be detected, longer mid-infrared wavelengths penetrate that dust, ultimately revealing a previously unseen cosmic environment.

One of the reasons the Tarantula Nebula is interesting to astronomers is that the nebula has a similar type of chemical composition as the gigantic star-forming regions observed at the universe's "cosmic noon," when the cosmos was only a few billion years old and star formation was at its peak. Star-forming regions in our Milky Way galaxy are not producing stars at the same furious rate as the Tarantula Nebula, and have a different chemical composition. This makes the Tarantula the closest (i.e., easiest to see in detail) example of what was happening in the universe as it reached its brilliant high noon. Webb will provide astronomers the opportunity to compare and contrast observations of star formation in the Tarantula Nebula with the telescope's deep observations of distant galaxies from the actual era of cosmic noon.

Despite humanity's thousands of years of stargazing, the star formation process still holds many mysteries—many of them due to our previous inability to get crisp images of what was happening behind the thick clouds of stellar nurseries. Webb has already begun revealing a universe never seen before, and is only getting started on rewriting the stellar creation story.Webb reveals cosmic cliffs, glittering landscape of star birth

Provided by European Space Agency 

NASA's Webb catches Tarantula Nebula

Tue, September 6, 2022 

A stellar nursery nicknamed the Tarantula Nebula has been captured in crisp detail by NASA's Webb telescope, revealing hitherto unseen features that deepen scientific understanding, the agency said Tuesday.

Officially known as 30 Doradus, the region of space is characterized by its dusty filaments that resemble the legs of a hairy spider, and has long been a favorite for astronomers interested in star formation.

Thousands of young stars, distant background galaxies, and the detailed structure of the nebula's gas and dust structures were viewable for the first time thanks to Webb's high resolution infrared instruments.

Webb operates primarily in the infrared spectrum, because light from objects in the distant cosmos has been stretched into this wavelength over the course of the universe's expansion.

The telescope's primary imager, Near-Infrared Camera (NIRCam), found the cavity in the center of the nebula was hollowed out by radiation carried on stellar winds emanating from a cluster of massive young stars, which appear as pale blue dots.

Webb's Near-Infrared Spectrograph (NIRSpec), which analyzes light patterns to determine the composition of objects, caught one young star in the act of shedding a cloud of dust from around itself.

The same star was previously thought to be at a later stage of formation, already well on the way to clearing its dusty bubble.

The region was also imaged using the Mid-infrared Instrument (MIRI), which uses longer wavelengths of infrared to pierce through dust grains that absorb or scatter shorter wavelengths.

This faded the hot stars and clarified the cooler regions, revealing never-before-seen points of light within the stellar nursery, which indicate protostars that are still gaining mass.

Astronomic interest in the Tarantula Nebula stems from its similar chemical composition to gigantic star-forming regions observed a few billion years after the Big Bang, a period called the "cosmic noon" when star formation peaked.

At just 161,000 light-years away, Tarantula is a readily viewable example of this flourishing period of cosmic creation.

Webb should also provide scientists the opportunity to gaze at distant galaxies from the actual era of cosmic noon, and compare it to observations of Tarantula, to understand similarities and differences.

Operational since July, Webb is the most powerful space telescope ever built, with astronomers confident it will herald a new era of discovery.

ia/mlm

Astronomers capture most detailed images yet of radiation region in Orionʻs 'sword'

by W. M. Keck Observatory

Credit: Habart et al./W. M. Keck Observatory

Astronomers using the W. M. Keck Observatory on Hawaiʻi Island have captured from Maunakea the most detailed and complete images ever taken of the zone where the famed constellation of Orion gets zapped with ultraviolet (UV) radiation from massive young stars.

This irradiated neutral zone, called a Photo-Dissociation Region (PDR), is located in the Orion Bar within the Orion Nebula, an active star-forming site found in the middle of the "sword" hanging from Orion's "belt." When viewed with the naked eye, the nebula is often mistaken for one of the stars in the constellation; when viewed with a telescope, the photogenic nebula is seen as a glowing gaseous stellar nursery located 1,350 light years from Earth.

"It was thrilling being the first, together with my colleagues of the 'PDRs4All' James Webb Space Telescope team, to see the sharpest images of the Orion Bar ever taken in the near infrared," said Carlos Alvarez, a staff astronomer at Keck Observatory and co-author of the study.

Because the Orion Nebula is the closest massive star formation region to us and may be similar to the environment in which our solar system was born, studying its PDR—the area that's heated by starlight—is an ideal place to find clues as to how stars and planets are created.

"Observing photo-dissociation regions is like looking into our past," said Emilie Habart, an Institut d'Astrophysique Spatiale associate professor at Paris-Saclay University and lead author of a paper on this study. "These regions are important because they allow us to understand how young stars influence the gas and dust cloud they are born in, particularly sites where stars, like the sun, form."

The study has been accepted for publication in the journal Astronomy & Astrophysics, and is available in preprint format on arXiv.org.

These pathfinder observations have assisted in the planning of the James Webb Space Telescope (JWST) Early Release Science (ERS) program PDRs4All: Radiative feedback of massive stars (ID1288). The PDRs4All program is described in a Publications of the Astronomical Society of the Pacific paper by Berné, Habart, Peeters et al. (2022).

Left: Hubble Space Telescope mosaic of the Orion Bar. 

Credit: NASA/STScI/Rice Univ./C.O’Dell et al. 

The NIRC2 wide camera Field of View is shown in the yellow square. 

Right: Infrared heat map of the Orion Bar obtained with Keck Observatory’s NIRC2

instrument reveals substructures such as proplyds. 

Credit: Habart et al./W. M. Keck Observatory

Methodology

To probe Orion's PDR, the PDRs4All team used Keck Observatory's second generation Near-Infrared Camera (NIRC2) in combination with the Keck II telescope's adaptive optics system. They successfully imaged the region with such extreme detail, the researchers were able to spatially resolve and distinguish the Orion Bar's different substructures—such as ridges, filaments, globules, and proplyds (externally illuminated photoevaporating disks around young stars)—that formed as starlight blasted and sculpted the nebula's mixture of gas and dust.

"Never before have we been able to observe at a small scale how interstellar matter structures depend on their environments, particularly how planetary systems could form in environments strongly irradiated by massive stars," said Habart. "This may allow us to better understand the heritage of the interstellar medium in planetary systems, namely our origins."

Massive young stars emit large quantities of UV radiation that affect the physics and chemistry of their local environment; how this surge of energy the stars inject into their native cloud impacts and shapes star formation is not yet well known.

The new Keck Observatory images of the Orion Bar will help deepen astronomers' understanding of this process because they reveal in detail where gas in its PDR changes from hot ionized gas, to warm atomic, to cold molecular gas. Mapping this conversion is important because the dense, cold molecular gas is the fuel needed for star formation.

What's next

These new observations from Keck Observatory have informed plans for JWST observations of the Orion Bar, which is among JWST's targets and is expected to be observed in the coming weeks.

"One of the most exciting aspects of this work is seeing Keck play a fundamental role in the JWST era," said Alvarez. "JWST will be able to dive deeper into the Orion Bar and other PDRs, and Keck will be instrumental in validating JWST's early science results. Together, the two telescopes can provide unique insight into the characteristics of the gas and chemical composition of PDRs, which will help us understand the nature of these fascinating star-blasted regions.Hubble finds flame Nebula's searing stars may halt planet formation

More information: High angular resolution near-IR view of the Orion Bar revealed by Keck/NIRC2, arXiv:2206.08245v1 [astro-ph.GA] arxiv.org/pdf/2206.08245.pdf

Journal information: Astronomy & Astrophysic

Provided by W. M. Keck Observatory 

Snap employees have started joking they work at 'Snapazon' now, as massive layoffs, forced attrition and an Amazon-like metrics culture take over

tdotan@insider.com (Tom Dotan,Kali Hays,Rob Price) 


Snap CEO Evan Spiegel demos the company's AR glasses. Snap Inc/Getty Images for Snap Inc© Snap Inc/Getty Images for Snap Inc
Snap morale is at a low point after massive layoffs and a new harsh Amazon-like management style.
Snap's new COO Jerry Hunter worked at Amazon for many years.
Sources said to Insider that managers were told to put 10% of their teams on PIPs.

In the midst of a brutal reorganizationn, Snap employees have been grimly joking the company has been turning itself into "Snapazon."

The reference is both an acknowledgement that Amazon executives have ascended to key roles at the social media company, and that Snap managers are obsessing more over metrics, Amazon-style.

Last week, Snap made its most dramatic cuts ever, laying off about 1,500 employees amid a broad slowdown in its ads business. Employees told Insider the move was "shocking," especially when CEO Evan Spiegel shut down major initiatives like its Pixy drone and its subsidiary Zenly, a social app it had acquired.

Employees have seen the company's austere Amazonification take place in a few different waves. Prior to the layoffs, Snap managers had been told to put 10% of their teams on performance improvement plans, according to company insiders. Now, in a larger restructuring at the company, Snap's engineering chief and longtime Amazon cloud executive Jerry Hunter, is serving as Snap COO—a sign that the company will continue leaning into the Amazon style.

Snap's abrupt layoffs came as a surprise to many inside the company. Earlier in the year, Snap insisted it was only implementing a "slowdown" in hiring and said repeatedly it would still grow headcount this year by 10%, a claim many managers relied on. Workers felt the company was going through changes that it would pull through and were not led to believe their jobs were in peril."I did not expect to be impacted at all," one former staffer said. "They've been stringing people along," another said.

 

'Full-time work doesn't pay': Why are so many working American families living day to day?

by Bailey Schulz

Credit: Pixabay/CC0 Public Domain

Rosalba Hernandez and her husband both work full time at a restaurant, but with five kids, soaring inflation rates and a San Diego apartment that keeps jacking up rent, the family is living day to day.

Things have gotten especially tight after the onset of the pandemic. An immigration raid in 2019 caused Hernandez to lose a second job at a Korean grocery store. And when the restaurant she previously worked at closed after the state entered lockdowns, the family fell $6,000 behind on rent and continue to carry the debt.

Hernandez and her husband have had to be creative to make do. With housing costs up, the couple is renting one room in their two-bedroom apartment to a family member for $800 a month. Day care expenses are out of the question, so Hernandez and her husband work opposite shifts to care for their 1-year-old. Whatever tips Hernandez makes go toward food.

"(It's) stressful because we're worried about hours being cut or being sent home early," Hernandez told USA TODAY through a translator. "Every little bit is helping."

The Hernandez family isn't alone. Basics such as food, housing and medical care are too pricy for many American families, even with full-time jobs.

More than one-third of U.S. families that work full time year-round do not earn enough to cover a basic family budget, according to a recent report from researchers at Brandeis University's diversitydatakids.org program at the Institute for Child, Youth and Family Policy.

The situation is even more dire for Black and Hispanic families, according to the report. More than half cannot afford basic needs, compared to 25% of white families and 23% of Asian and Pacific Islander families. Inequities remain even when controlling for education and occupation.

"This is contributing to a significant difference in the opportunities that families can provide for their children," said Abigail Walters, a research associate at the Institute for Child, Youth and Family Policy. "Full-time work doesn't pay, and families need a raise."

How many families don't earn enough to meet basic needs?

The report found that 35% of families who work full time don't earn enough for basic necessities such as housing, food, medical care, transportation to work, child care and minimal household expenses.

For low-income families—those whose income falls below 200% of the supplemental poverty measure, or $52,492 for two adults and two related children in 2020 it's—77% who can't pay the bills despite working full time.

In 2020, more than a quarter of the population, 89.7 million people, were considered low income per the Population Reference Bureau, a nonprofit that collects statistics for research on the health and structure of populations.

How far off from prosperity are these families?

The report found that low-income families working full time would need an additional $23,500 annually—or $11 more per hour—to cover basic expenses. Black and Hispanic families would need about $26,000 more per year.

The data used in the report is from 2015 to 2019. Researchers say the situation has likely gotten worse after the pandemic brought on massive layoffs and record inflation rates.

What can be done to lift Americans out of poverty?

Researchers noted that earning more isn't as easy as changing fields or taking on a second job.

"(There are) issues with structural racism," Walters said. "There are significant barriers to getting the better job, whether it's due to hiring discrimination or being the last hired and first fired, as well as pay gaps."

Researchers outlined actions employers and policymakers can take to help families:

• Give working families a raise: Employers can help by raising wages, offering more benefits and providing opportunities to advance to higher-paying jobs. Alternatively, policymakers can boost families' incomes with increased tax credits.
• Fix the child care system: A more affordable child care system would also benefit families struggling to afford the basics. The average annual cost of child care in the U.S. is $10,174, according to the nonprofit advocacy group Child Care Aware.
• Expand paid family and medical leave: Researchers say families should be able to afford medical leave without the threat of losing their job or a substantial portion of their income.

Full-time working families still lack benefits

About 80% of families working full time have access to health insurance from their employer if they are white or Asian. If they're Black or Hispanic, it's only 71% and 59%, respectively.

Employer benefits are less common for low-income families. Less than half of low-income Hispanic families with full-time jobs have access to health insurance from their employers.

"(The low wages are) not being made up by employer benefits," said Pamela Joshi, a senior research scientist and the paper's lead author.

Disparities in access to high-speed internet found among Chicago parents

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Distributed by Tribune Content Agency, LLC.

Using science to solve a 1,300-year-old art mystery

by University of Cincinnati

Dancing Horse, 608-907 CE, China, Tang Dynasty, earthenware with pigments, Cincinnati

 Art Museum, Gift of Carl and Eleanor Strauss, 1997.

 Credit: Cincinnati Art Museum

The Cincinnati Art Museum turned to a scientist at the University of Cincinnati for help solving a mystery 1,300 years in the making.

The museum's Chinese dancing horse sculpture is so realistic that the fiery steed seems ready to gallop off its pedestal. But East Asian art curator Hou-mei Sung questioned the authenticity of a decorative tassel on the terracotta horse's forehead that resembles the horn of a mythological unicorn.

The museum reached out to UC College of Arts and Sciences assistant professor of chemistry Pietro Strobbia for help to determine if the tassel was original to the work.

"Many museums have a conservator but not necessarily scientific facilities needed to do this kind of examination," Strobbia said. "The forehead tassel looks original, but the museum asked us to determine what materials it was made from."

Strobbia and his collaborators wrote about the project for a paper published in the journal Heritage Science.

Sung has seen many examples of ancient sculptures paying tribute to the dancing horses that performed for emperors as far back as 202 B.C. But no others have forehead tassels, she said. Was it perhaps added at some later date?

"I believed it was a mistake. The tassel wasn't in the right position," she said. "These pieces are so old. They often go through many repairs."

The Dancing Horse sculpture featured a decorative tassel on its forehead, prompting the

 Cincinnati Art Museum to undertake a scientific investigation that found it was not original

 to the piece. Dancing Horse, 608-907 CE, China, Tang Dynasty, earthenware with 

pigments, Cincinnati Art Museum, Gift of Carl and Eleanor Strauss, 1997. 

Credit: Cincinnati Art Museum

Donated to the Cincinnati museum by a collector in 1997, the dancing horse dates back to the Tang dynasty when such sculptures were commissioned for the express purpose of entombing them with royalty upon their deaths, Sung said.

Dancing horses were trained to move in time with a drumbeat. Sung said Emperor Xuanzong from the eighth century loved horses so much that he had a stable of more than 40,000. For one birthday celebration, he invited a troupe of 400 dancing horses to perform the "Song of the Upturned Cup."

"During the dramatic finale, one horse would bend its knees and clench a cup in its mouth and offer wine to the ruler to wish him longevity," Sung said. "This became a ritual."

The museum's terracotta horse is saddled with a blanket and flowing silken material where stirrups often hang. Ten conical tassels adorn the horse in the same reddish color as its short-cropped tail and long mane.

"The making of the sculpture is beautiful. These horses are renowned," said Kelly Rectenwald, co-author of the paper and associate objects conservator at the Cincinnati Art Museum.

With a background in archaeology and chemistry, Rectenwald said she understands how the latest science techniques are helping to shed new light on antiquities.

"We don't have that kind of scientific equipment here, so partnering with UC has been a great resource," she said.

To answer some of the fundamental questions about the piece, the museum agreed to allow UC's Strobbia and collaborators such as Claudia Conti at Italy's Institute of Heritage Science to take 11 tiny samples for analysis.

"We judged the risk was worth the reward to answer the question," Rectenwald said.

Researchers deployed a battery of molecular, chemical and mineralogical tests of the masterpiece and its features using cutting-edge techniques such as X-ray powder diffraction, ionic chromatography and Raman spectroscopy.


University of Cincinnati assistant professor Pietro Strobbia is using chemistry tools to help museums understand the provenance and origins of ancient masterpieces. Credit: Andrew Higley/UC

Strobbia has always had an interest in art, surrounded by the work of Raphael, Michelangelo and Bernini in Italy.

"I think I grew up a little spoiled coming from Rome," he said.

He and his research partners found that, indeed, the sculpture's forehead tassel was made of plaster, not terra cotta. It was added to the sculpture using animal glue.

The museum decided to remove the tassel in keeping with what they know about the original artworks, Rectenwald said. Beneath the tassel, Rectenwald found a smooth surface with no sign of scoring one might expect to see under sculptural adornments, providing more evidence that the tassel was a subsequent addition.

Researchers also discovered that two other tassels were repaired at different times, suggesting the sculpture was the subject of multiple restoration efforts over its many centuries, Rectenwald said.

"It was restored at least twice in its lifetime," she said. "Finding anything new about an artwork is really interesting."

Now Strobbia hopes to expand on his experience with the Cincinnati Art Museum by offering his chemistry expertise to other museums in the Midwest and perhaps UC's own art collection.

Collaborations between art historians and scientists give an added dimension to the stories behind these precious masterpieces.Long-term relationship with owner reduces horses' stress reactions in new situations

More information: C. Conti et al, Scientific investigation to look into the conservation history of a Tang Dynasty terracotta Dancing Horse, Heritage Science (2022). DOI: 10.1186/s40494-022-00758-7

Provided by University of Cincinnati 

Researchers capture live footage of virus infecting cell

by Stephanie Dutchen, Harvard Medical School

Schematic representation of the principal entry routes SARS-CoV-2 uses for infection. 

Entry starts with membrane attachment and ends with S protein–catalyzed membrane

 fusion releasing the viral contents into the cytosol. Fusion activity depends on two

 proteolytic cleavage steps, namely, one typically carried out by furin in the producing cell 

and the second by TMPRSS2 on the cell surface on in endosomes of the target cell. 

Alternatively, endosomal cathepsins can carry out both cleavages. Exposure of the virus 

to an acidic milieu is essential for membrane fusion, genome penetration, and productive 

infection. Fusion and penetration occur only in acidic early and late endosomal/lysosomal 

compartments but not at the cell surface, even when the furin and TMPRSS2 cleavages 

have both occurred. Fusion and penetration can occur at the cell surface of cells expressing

 TMPRSS2 if the extracellular pH is ∼6.8.

 Credit: Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2209514119

In a first, scientists have captured on video all the steps a virus follows as it enters and infects a living cell in real time and in three dimensions.

Scientists achieved the feat by using advanced imaging called lattice light sheet microscopy as well as chemical and genetic manipulation.

The first part of the video shown here follows a virus engineered to sprout SARS-CoV-2 spike proteins (labeled pink) as it is captured at a cell surface and engulfed by a cellular compartment called an endosome. The virus then fuses with the endosome membrane and injects its genetic material (labeled blue) inside the cell—the steps necessary to kick off a cycle of viral infection and replication.

The second part of the video shows many such viruses inside the cell. The video covers 4 minutes of activity, with snapshots taken every 4 seconds.

The findings, published Sept. 1 in PNAS, provide new insights into the fundamental mechanics of viral infection and could point the way to new methods for intervening before the onset of COVID-19.

The researchers' work reveals that viruses can't fuse with the membrane and release their genomes unless they're bathed in a slightly acidic environment. Experiments indicated that the pH must fall between 6.2 and 6.8, just shy of neutral and on par with bodily fluids such as saliva and urine. Endosomes have such acidity, and the team's measurements confirmed that this is also the pH range inside a typical human nose, where SARS-CoV-2 infection often begins.

Credit: Harvard Medical School

"Amusingly enough, measuring the pH of the nostril cavity has rarely been done before," noted co-senior author Tomas Kirchhausen, professor of cell biology in the Blavatnik Institute at Harvard Medical School and HMS professor of pediatrics at Boston Children's Hospital.

The acidic environment allows enzymes in the endosome or on the cell surface—including TMPRSS2, a key enabler of SARS-CoV-2 infection—to cut the spike protein and facilitate membrane fusion, the team found.

The work was led by the labs of Kirchhausen; former HMS professor Sean Whelan, now at Washington University in St. Louis; and Giuseppe Balistreri at the University of Helsinki. Alex Kreutzberger, HMS instructor in pediatrics in the Kirchhausen lab, is first author of the paper.Powerful new antibody neutralizes all known SARS-CoV-2 variants

More information: Alex J. B. Kreutzberger et al, SARS-CoV-2 requires acidic pH to infect cells, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2209514119

Journal information: Proceedings of the National Academy of Sciences 

Provided by Harvard Medical School 

Archaeologists discover monumental evidence of prehistoric hunting across Arabian desert

by University of Oxford

Aerial photo of a typical kite from eastern Jordan. Credit: APAAME

Archaeologists at the University of Oxford's School of Archaeology have used satellite imagery to identify and map more than 350 monumental hunting structures known as "kites" across northern Saudi Arabia and southern Iraq—most of which had never been previously documented.

Led by Dr. Michael Fradley, a team of researchers in the Endangered Archaeology in the Middle East and North Africa (EAMENA) project used a range of open-source satellite imagery to carefully study the region around the eastern Nafud desert, an area little studied in the past. The surprising results, published in the journal The Holocene, have the potential to change our understanding of prehistoric connections and climate change across the Middle East.

Termed kites by early aircraft pilots, these structures consist of low stone walls making up a head enclosure and a number of guiding walls, sometimes kilometers long. They are believed to have been used to guide game such as gazelles into an area where they could be captured or killed. There is evidence that these structures may date back as far as 8,000 BCE in the Neolithic period.

Kites cannot be observed easily from the ground, however the advent of commercial satellite imagery and platforms such as Google Earth have enabled recent discoveries of new distributions. While these structures were already well-known from eastern Jordan and adjoining areas in southern Syria, these latest results take the known distribution over 400km further east across northern Saudi Arabia, with some also identified in southern Iraq for the first time.

Dr. Fradley said, "The structures we found displayed evidence of complex, careful design. In terms of size, the 'heads' of the kites can be over 100 meters wide, but the guiding walls (the 'strings' of the kite) which we currently think gazelle and other game would follow to the kite heads can be incredibly long. In some of these new examples, the surviving portion of walls run in almost straight lines for over 4 kilometers, often over very varied topography. This shows an incredible level of ability in how these structures were designed and built."

Evidence suggests considerable resources would have had to be coordinated to build, maintain, and rebuild the kites over generations, combined with hunting and returning butchered remains to settlements or camps for further preservation. The researchers suggest that their exaggerated scale and form may be an expression of status, identity and territoriality. Appearances of the kites in rock art found in Jordan suggests they had an important place within the symbolic and ritual spheres of Neolithic peoples in the region.

From the design of the kite heads to the careful runs of guiding walls over long distances, these structures contrast markedly in scale with any other evidence of architecture from the early Holocene period. The researchers suggest that the builders of these kites dwelt in temporary structures made from organic materials that have left no trace visible on current satellite imagery data.

These new sites suggest a previously unknown level of connection right across northern Arabia at the time they were built. They raise exciting questions about who built these structures, who the hunted game were intended to feed, and how the people were able to not only survive, but also invest in these monumental structures.

In the context of this new connectedness, the distribution of the star-shaped kites now provides the first direct evidence of contact through, rather than around, the Nafud desert. This underlines the importance areas that are now desert had under more favorable climatic conditions in enabling the movement of humans and wildlife. It is thought the kites were built during a wetter, greener climatic period known as the Holocene Humid Period (between around 9000 and 4000 BCE).

The largest number of kites were built on the Al Labbah plateau in the Nafud desert, where the absence of later Bronze Age burial monuments suggests that a shift into a drier period meant some of these areas became too marginal to support the communities once using these landscapes, with game species also potentially displaced by climate change.

Whether the patterns of kite construction over space and time represent the movement of ideas or people, or even the direction of that movement, remain questions to be answered.

The project is now extending its survey work across these now arid zones to further develop our understanding of these landscapes and the effect of climate change.

The study, "Following the herds? A new distribution of hunting kites in Southwest Asia," is published in The Holocene.

Stone age desert kites found in southern Africa

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More information: Michael Fradley et al, Following the herds? A new distribution of hunting kites in Southwest Asia, The Holocene (2022). DOI: 10.1177/09596836221114290

Provided by University of Oxford