Ground-breaking number of brown dwarfs discovered

Brown dwarfs are mysterious astronomical objects that fill the gap between the heaviest planets and the lightest stars, with a mix of stellar and planetary characteristics. Due to this hybrid nature, these puzzling objects are crucial to improve our understanding of both stars and giant planets. Brown dwarfs orbiting a parent star from sufficiently far away are particularly valuable as they can be directly photographed -- unlike those that are too close to their star and are thus hidden by its brightness. This provides scientists with a unique opportunity to study the details of the cold, planet-like atmospheres of brown dwarf companions.

However, despite remarkable efforts in the development of new observing technologies and image processing techniques, direct detections of brown dwarf companions to stars have remained rather sparse, with only around 40 systems imaged in almost three decades of searches. Researchers led by Mariangela Bonavita from the Open University and Clémence Fontanive from the Center for Space and Habitability (CSH) and the NCCR PlanetS at the University of Bern directly imaged four new brown dwarfs as they report in a study that has just been published in the journal Monthly Notices of the Royal Astronomical Society MNRAS. This is the first time that multiple new systems with brown dwarf companions on wide orbital separations have been announced at the same time.

Innovative search method

"Wide-orbit brown dwarf companions are rare to start with, and detecting them directly poses huge technical challenges since the host stars completely blind our telescopes," says Mariangela Bonavita. Most surveys conducted so far have been blindly targeting random stars from young clusters. "An alternative approach to increase the number of detections is to only observe stars that show indications of an additional object in their system," explains Clémence Fontanive. For example, the way a star moves under the gravitational tug of a companion can be an indicator of the existence of that companion, whether it is a star, a planet or something in between.

"We developed the COPAINS tool which predicts the types of companions that could be responsible for observed anomalies in stellar motions," Clémence Fontanive continues. Applying the COPAINS tool the research team carefully selected 25 nearby stars that seemed promising for the direct detection of hidden, low-mass companions based on data from the Gaia spacecraft of the European Space Agency (ESA). Using then the SPHERE planet-finder at the Very Large Telescope in Chile to observe these stars, they successfully detected ten new companions with orbits ranging from that of Jupiter to beyond that of Pluto, including five low-mass stars, a white dwarf (a dense stellar remnant), and a remarkable four new brown dwarfs.

Major boost in detection rate

"These findings significantly advance the number of known brown dwarfs orbiting stars from large distances, with a major boost in detection rate compared to any previous imaging survey," as Mariangela Bonavita explains. While for now this approach is mostly limited to signatures from brown dwarf and stellar companions, future phases of the Gaia mission will push these methods to lower masses and allow for the discovery of new giant exoplanets. Clémence Fontanive adds: "On top of having so many new discoveries in one go, our program also demonstrates the power of these search strategies."

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The Earth moves far under our feet: A new study shows the inner core oscillates

USC scientists have found evidence that the Earth's inner core oscillates, contradicting previously accepted models that suggested it consistently rotates at a faster rate than the planet's surface.

Their study, published today in Science Advances, shows that the inner core changed direction in the six-year period from 1969-74, according to the analysis of seismic data. The scientists say their model of inner core movement also explains the variation in the length of day, which has been shown to oscillate persistently for the past several decades.

"From our findings, we can see the Earth's surface shifts compared to its inner core, as people have asserted for 20 years," said John E. Vidale, co-author of the study and Dean's Professor of Earth Sciences at USC Dornsife College of Letters, Arts and Sciences. "However, our latest observations show that the inner core spun slightly slower from 1969-71 and then moved the other direction from 1971-74. We also note that the length of day grew and shrank as would be predicted.

"The coincidence of those two observations makes oscillation the likely interpretation."

Analysis of atomic tests pinpoints rotation rate and direction

Our understanding of the inner core has expanded dramatically in the past 30 years. The inner core -- a hot, dense ball of solid iron the size of Pluto -- has been shown to move and/or change over decades. It's also impossible to observe directly, meaning researchers struggle through indirect measurements to explain the pattern, speed and cause of the movement and changes.

Research published in 1996 was the first to propose the inner core rotates faster than the rest of the planet -- also known as super-rotation -- at roughly 1 degree per year. Subsequent findings from Vidale reinforced the idea that the inner core super-rotates, albeit at a slower rate.

Utilizing data from the Large Aperture Seismic Array (LASA), a U.S. Air Force facility in Montana, researcher Wei Wang and Vidale found the inner core rotated slower than previously predicted, approximately 0.1 degrees per year. The study analyzed waves generated from Soviet underground nuclear bomb tests from 1971-74 in the Arctic archipelago Novaya Zemlya using a novel beamforming technique developed by Vidale.

The new findings emerged when Wang and Vidale applied the same methodology to a pair of earlier atomic tests beneath Amchitka Island at the tip of the Alaskan archipelago -- Milrow in 1969 and Cannikin in 1971. Measuring the compressional waves resulting from the nuclear explosions, they discovered the inner core had reversed direction, sub-rotating at least a tenth of a degree per year.

This latest study marked the first time the well-known six-year oscillation had been indicated through direct seismological observation.

"The idea the inner core oscillates was a model that was out there, but the community has been split on whether it was viable," Vidale says. "We went into this expecting to see the same rotation direction and rate in the earlier pair of atomic tests, but instead we saw the opposite. We were quite surprised to find that it was moving in the other direction."

Future research to dig deeper into why inner core formed

Vidale and Wang both noted future research would depend on finding sufficiently precise observations to compare against these results. By using seismological data from atomic tests in previous studies, they have been able to pinpoint the exact location and time of the very simple seismic event, says Wang. However, the Montana LASA closed in 1978 and the era of U.S. underground atomic testing is over, meaning that the researchers would need to rely on comparatively imprecise earthquake data, even with recent advances in instrumentation.

The study does support the speculation that the inner core oscillates based on variations in the length of day -- plus or minus 0.2 seconds over six years -- and geomagnetic fields, both of which match the theory in both amplitude and phase. Vidale says the findings provide a compelling theory for many questions posed by the research community.

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Astronomers may have detected a 'dark' free-floating black hole

Black holes, by their nature, are invisible unless part of a stellar binary or surrounded by an accretion disk. Most stellar-sized black holes aren't, but astronomers have been searching for them through gravitational microlensing events, where the black hole brightens and distorts light from stars toward the galactic center. A UC Berkeley-led team may have found the first free-floating black hole, though more data is needed to rule out a neutron star.

If, as astronomers believe, the death of large stars leave behind black holes, there should be hundreds of millions of them scattered throughout the Milky Way galaxy. The problem is, isolated black holes are invisible.

Now, a team led by University of California, Berkeley, astronomers has for the first time discovered what may be a free-floating black hole by observing the brightening of a more distant star as its light was distorted by the object's strong gravitational field -- so-called gravitational microlensing.

The team, led by graduate student Casey Lam and Jessica Lu, a UC Berkeley associate professor of astronomy, estimates that the mass of the invisible compact object is between 1.6 and 4.4 times that of the sun. Because astronomers think that the leftover remnant of a dead star must be heavier than 2.2 solar masses in order to collapse to a black hole, the UC Berkeley researchers caution that the object could be a neutron star instead of a black hole. Neutron stars are also dense, highly compact objects, but their gravity is balanced by internal neutron pressure, which prevents further collapse to a black hole.

Whether a black hole or a neutron star, the object is the first dark stellar remnant -- a stellar "ghost" -- discovered wandering through the galaxy unpaired with another star.

"This is the first free-floating black hole or neutron star discovered with gravitational microlensing," Lu said. "With microlensing, we're able to probe these lonely, compact objects and weigh them. I think we have opened a new window onto these dark objects, which can't be seen any other way."

Determining how many of these compact objects populate the Milky Way galaxy will help astronomers understand the evolution of stars -- in particular, how they die -- and of our galaxy, and perhaps reveal whether any of the unseen black holes are primordial black holes, which some cosmologists think were produced in large quantities during the Big Bang.

The analysis by Lam, Lu and their international team has been accepted for publication in The Astrophysical Journal Letters. The analysis includes four other microlensing events that the team concluded were not caused by a black hole, though two were likely caused by a white dwarf or a neutron star. The team also concluded that the likely population of black holes in the galaxy is 200 million -- about what most theorists predicted.

Same data, different conclusions

Notably, a competing team from the Space Telescope Science Institute (STScI) in Baltimore analyzed the same microlensing event and claims that the mass of the compact object is closer to 7.1 solar masses and indisputably a black hole. A paper describing the analysis by the STScI team, led by Kailash Sahu, has been accepted for publication in The Astrophysical Journal.

Both teams used the same data: photometric measurements of the distant star's brightening as its light was distorted or "lensed" by the super-compact object, and astrometric measurements of the shifting of the distant star's location in the sky as a result of the gravitational distortion by the lensing object. The photometric data came from two microlensing surveys: the Optical Gravitational Lensing Experiment (OGLE), which employs a 1.3-meter telescope in Chile operated by Warsaw University, and the Microlensing Observations in Astrophysics (MOA) experiment, which is mounted on a 1.8-meter telescope in New Zealand operated by Osaka University. The astrometric data came from NASA's Hubble Space Telescope. STScI manages the science program for the telescope and conducts its science operations.

Because both microlensing surveys caught the same object, it has two names: MOA-2011-BLG-191 and OGLE-2011-BLG-0462, or OB110462, for short.

While surveys like these discover about 2,000 stars brightened by microlensing each year in the Milky Way galaxy, the addition of astrometric data is what allowed the two teams to determine the mass of the compact object and its distance from Earth. The UC Berkeley-led team estimated that it lies between 2,280 and 6,260 light years (700-1920 parsecs) away, in the direction of the center of the Milky Way Galaxy and near the large bulge that surrounds the galaxy's central massive black hole.

The STScI group estimated that it lies about 5,153 light years (1,580 parsecs) away.

Looking for a needle in a haystack

Lu and Lam first became interested in the object in 2020 after the STScI team tentatively concluded that five microlensing events observed by Hubble -- all of which lasted for more than 100 days, and thus could have been black holes -- might not be caused by compact objects after all.

Lu, who has been looking for free-floating black holes since 2008, thought the data would help her better estimate their abundance in the galaxy, which has been roughly estimated at between 10 million and 1 billion. To date, star-sized black holes have been found only as part of binary star systems. Black holes in binaries are seen either in X-rays, produced when material from the star falls onto the black hole, or by recent gravitational wave detectors, which are sensitive to mergers of two or more black holes. But these events are rare.

"Casey and I saw the data and we got really interested. We said, 'Wow, no black holes. That's amazing,' even though there should have been," Lu said. "And so, we started looking at the data. If there were really no black holes in the data, then this wouldn't match our model for how many black holes there should be in the Milky Way. Something would have to change in our understanding of black holes -- either their number or how fast they move or their masses."

When Lam analyzed the photometry and astrometry for the five microlensing events, she was surprised that one, OB110462, had the characteristics of a compact object: The lensing object seemed dark, and thus not a star; the stellar brightening lasted a long time, nearly 300 days; and the distortion of the background star's position also was long-lasting.

The length of the lensing event was the main tipoff, Lam said. In 2020, she showed that the best way to search for black hole microlenses was to look for very long events. Only 1% of detectable microlensing events are likely to be from black holes, she said, so looking at all events would be like searching for a needle in a haystack. But, Lam calculated, about 40% of microlensing events that last more than 120 days are likely to be black holes.

"How long the brightening event lasts is a hint of how massive the foreground lens bending the light of the background star is," Lam said. "Long events are more likely due to black holes. It's not a guarantee, though, because the duration of the brightening episode not only depends on how massive the foreground lens is, but also on how fast the foreground lens and background star are moving relative to each other. However, by also getting measurements of the apparent position of the background star, we can confirm whether the foreground lens really is a black hole."

According to Lu, the gravitational influence of OB110462 on the light of the background star was amazingly long. It took about one year for the star to brighten to its peak in 2011, then about a year to dim back to normal.

More data will distinguish black hole from neutron star

To confirm that OB110462 was caused by a super-compact object, Lu and Lam asked for more astrometric data from Hubble, some of which arrived last October. That new data showed that the change in position of the star as a result of the gravitational field of the lens is still observable 10 years after the event. Further Hubble observations of the microlens are tentatively scheduled for fall 2022.

Analysis of the new data confirmed that OB110462 was likely a black hole or neutron star.

Lu and Lam suspect that the differing conclusions of the two teams are due to the fact that the astrometric and photometric data give different measures of the relative motions of the foreground and background objects. The astrometric analysis also differs between the two teams. The UC Berkeley-led team argues that it is not yet possible to distinguish whether the object is a black hole or a neutron star, but they hope to resolve the discrepancy with more Hubble data and improved analysis in the future.

"As much as we would like to say it is definitively a black hole, we must report all allowed solutions. This includes both lower mass black holes and possibly even a neutron star," Lu said.

"If you can't believe the light curve, the brightness, then that says something important. If you don't believe the position versus time, that tells you something important," Lam said. "So, if one of them is wrong, we have to understand why. Or the other possibility is that what we measure in both data sets is correct, but our model is incorrect. The photometry and astrometry data arise from the same physical process, which means the brightness and position must be consistent with each other. So, there's something missing there. "

Both teams also estimated the velocity of the super-compact lensing object. The Lu/Lam team found a relatively sedate speed, less than 30 kilometers per second. The STScI team found an unusually large velocity, 45 km/s, which it interpreted as the result of an extra kick that the purported black hole got from the supernova that generated it.

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Yellowstone's history of hydrothermal explosions over the past 14,000 years

While much of public attention on Yellowstone focuses on its potential to produce large supereruptions, the hazards that are much more likely to occur are smaller, violent hydrothermal explosions. Hydrothermal explosions occur when near-boiling water suddenly flashes into steam, releasing large amounts of energy. The energy release fractures the rock downward, often leaving behind a crater. The same sources that can produce these explosions are what give Yellowstone its well-known hot springs, geysers, and fumaroles.

The Yellowstone Lake area in Yellowstone National Park hosts at least eight large craters produced by hydrothermal explosions, including three of the largest hydrothermal explosion craters known on Earth. Compared to other areas of interest within Yellowstone, hydrothermal explosion craters have not been as thoroughly studied. In a new study published on Tuesday in GSA Bulletin, researchers evaluated the history of hydrothermal explosions at Yellowstone Lake over the past 14,000.

"The hydrothermal system in Yellowstone is the largest in the world and is driven by high heat flow over a large area, by high precipitation rates, and by active seismicity and deformation. Over 10,000 hydrothermal features are present in Yellowstone," said Lisa Morgan, lead author of the study. "For this study, we wanted to know more about the recent geologic history of Yellowstone Lake and what role hydrothermal activity has had in the lake, especially the role of hydrothermal explosions and their triggering mechanisms."

The research team collected sediment cores from across the northern portion of Yellowstone Lake and correlated them with cores that were previously collected in the vicinity, with the goal of characterizing their chemical and physical attributes and identifying hydrothermal explosion deposits in the cores.

"Hydrothermal explosion sediments deposited underwater had never been described in published literature. In analyzing the cores, we made a lot of discoveries and had several surprises. Number one was how different the explosion deposits found in the cores looked from explosion deposits on land. That was to be expected since one was deposited through a water column and one was deposited on land," said Morgan.

The researchers found evidence for at least 16 deposits in the cores that were produced by hydrothermal explosions. While 14 of the deposits represented more localized explosion events, two of the deposits were associated with two of Yellowstone's largest hydrothermal explosion craters: the Mary Bay and Elliott's craters.

The Mary Bay hydrothermal explosion occurred 13,000 years ago and resulted in a 2.5-km (1.5-mi) wide crater, which is partly submerged under the lake. While deposits from the Mary Bay explosion exposed on land had been previously studied, the sediment cores from the lake demonstrated that the extent of its deposits was larger than previously thought and that the lake level must have been lower at the time of the explosion.

The researchers concluded that the Mary Bay explosion was triggered by a sudden 14-m (46-ft) drop in lake level caused by a seismic event and a tsunami that eroded the outlet waterway of Yellowstone Lake.

The Elliott's Crater explosion occurred 8,000 years ago and produced a 700-m (2,300-ft) wide crater. The crater is fully submerged underwater, and no deposits from the explosion are exposed on land. Based on records in the cores, the deposits from Elliott's Crater were also more broadly distributed than previously thought.

Differing from how the Mary Bay Crater likely formed, the researchers determined that Elliott's Crater formed when a seismic event fractured the dome cap of the hydrothermal system. In Yellowstone Lake, hydrothermal domes form when underlying pockets of gas or gas-charged fluids cause overlying sediments to arch upwards. Rupturing this dome would result in a sudden loss of pressure, triggering a hydrothermal explosion.

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Wreck of historic royal ship discovered off the English coast

The wreck of one of the most famous ships of the 17th century -- which sank 340 years ago while carrying the future King of England James Stuart -- has been discovered off the coast of Norfolk in the UK, it can be revealed today.

Since running aground on a sandbank on May 6, 1682, the wreck of the warship the Gloucester has lain half-buried on the seabed, its exact whereabouts unknown until brothers Julian and Lincoln Barnwell, with their friend James Little, found it after a four-year search.

Due to the age and prestige of the ship, the condition of the wreck, the finds already rescued, and the accident's political context, the discovery is described by maritime history expert Prof Claire Jowitt, of the University of East Anglia (UEA), as the most important maritime discovery since the Mary Rose.

The Gloucester represents an important 'almost' moment in British political history: a royal shipwreck causing the very near-death of the Catholic heir to the Protestant throne at a time of great political and religious tension.

Now a major exhibition is planned for Spring 2023, the result of a partnership between the Barnwell brothers, Norfolk Museums Service, and academic partner UEA. Running from February to July at Norwich Castle Museum & Art Gallery, the exhibition will display finds from the wreck -- including the bell that confirmed the ship's identity -- and share ongoing historical, scientific and archaeological research.

Prof Jowitt, a world-leading authority on maritime cultural history, is a co-curator of the exhibition. "Because of the circumstances of its sinking, this can be claimed as the single most significant historic maritime discovery since the raising of the Mary Rose in 1982," she said. "The discovery promises to fundamentally change understanding of 17th-century social, maritime and political history.

"It is an outstanding example of underwater cultural heritage of national and international importance. A tragedy of considerable proportions in terms of loss of life, both privileged and ordinary, the full story of the Gloucester's last voyage and the impact of its aftermath needs re-telling, including its cultural and political importance, and legacy. We will also try to establish who else died and tell their stories, as the identities of a fraction of the victims are currently known."

The Barnwell brothers are Norfolk-based printers, licensed divers and Honorary Fellows in the School of History at UEA. Lincoln said he was partly inspired to search for the wreck after watching the lifting of the Mary Rose on television as a child.

"It was our fourth dive season looking for Gloucester," he said. "We were starting to believe that we were not going to find her, we'd dived so much and just found sand. On my descent to the seabed the first thing I spotted were large cannon laying on white sand, it was awe- inspiring and really beautiful.

"It instantly felt like a privilege to be there, it was so exciting. We were the only people in the world at that moment in time who knew where the wreck lay. That was special and I'll never forget it. Our next job was to identify the site as the Gloucester."

Julian added: "When we decided to search for the Gloucester we had no idea how significant she was in history. We had read that the Duke of York was onboard but that was it. We were confident it was the Gloucester, but there are other wreck sites out there with cannons, so it still needed to be confirmed.

"There is still a huge amount of knowledge to be gained from the wreck, which will benefit Norfolk and the nation. We hope this discovery and the stories that are uncovered will inform and inspire future generations."

Lord Dannatt, Norfolk Deputy Lieutenant and longstanding resident of the county, is lending his skills and support to the historic rescue project. As former head of the British Army, he works with charities and organisations that have links to the armed services.

"This is going to be Norfolk's Mary Rose," said Lord Dannatt. "Julian and Lincoln have touched history, history that could have changed the course of this nation. It's such an amazing story to tell. Our aim is to bring that story to life and to share it with as many people as possible."

The Gloucester was commissioned in 1652, built at Limehouse in London, and launched in 1654. In 1682 it was selected to carry James Stuart, Duke of York, to Edinburgh to collect his heavily pregnant wife and their households. The aim was to bring them back to King Charles II's court in London in time, it was hoped, for the birth of a legitimate male heir.

The ship had set sail from Portsmouth with the Duke and his entourage joining it off Margate, having travelled by yacht from London. At 5.30am on May 6, the Gloucester ran aground some 45km off Great Yarmouth following a dispute about navigating the treacherous Norfolk sandbanks. The Duke, a former Lord High Admiral, had argued with the pilot for control over the ship's course.

Within an hour the vessel sank with the loss of hundreds of the crew and passengers. The Duke barely survived, having delayed abandoning ship until the last minute.

As well as the Duke of York, the Gloucester carried a number of prominent English and Scottish courtiers including John Churchill, later the 1st Duke of Marlborough.

Diarist and naval administratorSamuel Pepys, who witnessed events from another ship in the fleet, wrote his own account -- describing the harrowing experience for victims and survivors, with some picked up "half dead" from the water.

Together with their late father Michael, and two friends including James Little, a former Royal Navy submariner and diver, the Barnwell brothers found the wreck site in 2007, with the Gloucester split down the keel and remains of the hull submerged in sand.

The ship's bell, manufactured in 1681, was later recovered, and in 2012 it was used by the Receiver of Wreck and Ministry of Defence to decisively identify the vessel.

Due to the time taken to confirm the identity of the ship and the need to protect an 'at risk' site, which lies in international waters, it is only now that its discovery can be made public. As well as the Receiver of Wreck and Ministry of Defence, the wreck has been declared to Historic England.

Following the discovery, the brothers completed an underwater archaeology course with the Nautical Archaeology Society.

Artefacts rescued and conserved include clothes and shoes, navigational and other professional naval equipment, personal possessions, and many wine bottles.

One of the bottles bears a glass seal with the crest of the Legge family -- ancestors of George Washington, the first US President. The crest was a forerunner to the Stars and Stripes flag. Uniquely, in addition there were also some unopened bottles, with wine still inside - offering exciting opportunities for future research.

The accompanying historical research project, funded by the Leverhulme Trust and led by Prof Jowitt, will explore not only the failures of command at sea before the Gloucester sank, but conspiracy theories about the tragedy's causes and its political consequences.

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Most 'silent' genetic mutations are harmful, not neutral -- a finding with broad implications

In the early 1960s, University of Michigan alumnus Marshall Nirenberg and a few other scientists deciphered the genetic code of life, determining the rules by which information in DNA molecules is translated into proteins, the working parts of living cells.

They identified three-letter units in DNA sequences, known as codons, that specify each of the 20 amino acids that make up proteins, work for which Nirenberg later shared a Nobel Prize with two others.

Occasionally, single-letter misspellings in the genetic code, known as point mutations, occur. Point mutations that alter the resulting protein sequences are called nonsynonymous mutations, while those that do not alter protein sequences are called silent or synonymous mutations.

Between one-quarter and one-third of point mutations in protein-coding DNA sequences are synonymous. Ever since the genetic code was cracked, those mutations have generally been assumed to be neutral, or nearly so.

But in a study scheduled for online publication June 8 in the journal Nature that involved the genetic manipulation of yeast cells in the laboratory, University of Michigan biologists show that most synonymous mutations are strongly harmful.

The strong nonneutrality of most synonymous mutations -- if found to be true for other genes and in other organisms -- would have major implications for the study of human disease mechanisms, population and conservation biology, and evolutionary biology, according to the study authors.

"Since the genetic code was solved in the 1960s, synonymous mutations have been generally thought to be benign. We now show that this belief is false," said study senior author Jianzhi "George" Zhang, the Marshall W. Nirenberg Collegiate Professor in the U-M Department of Ecology and Evolutionary Biology.

"Because many biological conclusions rely on the presumption that synonymous mutations are neutral, its invalidation has broad implications. For example, synonymous mutations are generally ignored in the study of disease-causing mutations, but they might be an underappreciated and common mechanism."

In the past decade, anecdotal evidence has suggested that some synonymous mutations are nonneutral. Zhang and his colleagues wanted to know if such cases are the exception or the rule.

They chose to address this question in budding yeast (Saccharomyces cerevisiae) because the organism's short generation time (about 80 minutes) and small size allowed them to measure the effects of a large number of synonymous mutations relatively quickly, precisely and conveniently.

They used CRISPR/Cas9 genome editing to construct more than 8,000 mutant yeast strains, each carrying a synonymous, nonsynonymous or nonsense mutation in one of 21 genes the researchers targeted.

Then they quantified the "fitness" of each mutant strain by measuring how quickly it reproduced relative to the nonmutant strain. Darwinian fitness, simply put, refers to the number of offspring an individual has. In this case, measuring the reproductive rates of the yeast strains showed whether the mutations were beneficial, harmful or neutral.

To their surprise, the researchers found that 75.9% of synonymous mutations were significantly deleterious, while 1.3% were significantly beneficial.

"The previous anecdotes of nonneutral synonymous mutations turned out to be the tip of the iceberg," said study lead author Xukang Shen, a graduate student research assistant in Zhang's lab.

"We also studied the mechanisms through which synonymous mutations affect fitness and found that at least one reason is that both synonymous and nonsynonymous mutations alter the gene-expression level, and the extent of this expression effect predicts the fitness effect."

Zhang said the researchers knew beforehand, based on the anecdotal reports, that some synonymous mutations would likely turn out to be nonneutral.

"But we were shocked by the large number of such mutations," he said. "Our results imply that synonymous mutations are nearly as important as nonsynonymous mutations in causing disease and call for strengthened effort in predicting and identifying pathogenic synonymous mutations."

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Rapid-fire fast radio burst shows hot space between galaxies

A recently discovered, rare and persistent rapid-fire fast radio burst source -- sending out an occasional and informative cosmic ping from more than 3.5 billion light years away -- helps to reveal the secrets of the broiling hot space between the galaxies. That's according to an international team of astronomers who published their findings in the journal Nature.

Fast Radio Burst 20190520B -- a prolific repeating burst source -- was first observed in June 2019 by the Five-hundred-meter Aperture Spherical radio Telescope (FAST), in Ghizou province, southwest China. Astronomers generally consider this telescope as the spiritual successor to the now-defunct, Cornell University-built Arecibo Observatory in Puerto Rico.

After FAST found the burst, scientists then pinpointed the burst's location using the Very Large Array, Socorro, New Mexico.

What excites astronomers about the repeating fast radio bursts (FRBs) -- since they only burst once, generally speaking -- is that these quick-fire surges provide a pathway for scientists to comprehend the perplexing, mysterious and million-degree intergalactic medium.

"Examining the intergalactic medium is really hard," said co-author Shami Chatterjee, principal research scientist in astronomy at Cornell. "The intergalactic medium is difficult to probe, which is why fast radio bursts are exciting. The bursts let us study the properties of the intergalactic medium."

Joining Chatterjee on the Nature paper are James M. Cordes, professor of astronomy and Stella K. Ocker, a doctoral student in astronomy.

Co-author Di Li, is the chief scientist of both FAST and the radio division of the National Astronomical Observatories of Chinese Academy of Sciences. The observatory has discovered more than 100 pulsars and more than 5 FRBs.

Four bursts were detected during the initial 24-second scan in 2019, according to the paper. Between April and September 2020, during follow-up observations, FAST detected 75.

Due to the rapidly repeating bursts, astronomers believe that FRB 20190520B may be quite young. "It seems to reside in a complex plasma environment, like that expected in a young supernova remnant," Chatterjee said. "So one possibility is that the highly active source may be a newborn, and if so, it paints an intriguing evolutionary picture of FRB sources, where young burst sources are associated with persistent radio emission.

"The persistent emission fades away as the burst repetition rate slows down," Chatterjee said. "This is still very much a hypothesis and we are eager to test it with further examples of repeating FRBs."

Astronomers usually assume that FRBs pass through only a modest amount of gas (free electrons) in their host galaxies, which makes counting electrons in the intergalactic medium an easier task. FRB 20190520B shows the opposite: It has encountered far more gas in its host galaxy than scientists expected, calling into question previous assumptions.

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Europe's largest land predator unearthed on the Isle of Wight

Research led by palaeontologists at the University of Southampton has identified the remains of one of Europe's largest ever land-based hunters: a dinosaur that measured over 10m long and lived around 125 million years ago.

Several prehistoric bones, uncovered on the Isle of Wight, on the south coast of England, and housed at Dinosaur Isle Museum in Sandown, belonged to a type of two-legged, crocodile-faced predatory dinosaur known as spinosaurids. Dubbed the 'White Rock spinosaurid' -- after the geological layer in which it was found -- it was a predator of impressive proportions.

"This was a huge animal, exceeding 10 m in length and probably several tonnes in weight. Judging from some of the dimensions, it appears to represent one of the largest predatory dinosaur ever found in Europe -- maybe even the biggest yet known," said PhD student Chris Barker, who led the study. "It's a shame it's only known from a small amount of material, but these are enough to show it was an immense creature."

The discovery follows previous work on spinosaurids by the University of Southampton team, which published a study on the discovery of two new species in 2021.

The bones of the 'White Rock spinosaurid', which include huge pelvic and tail vertebrae, amongst other pieces, were discovered near Compton Chine, on the southwest coast of the Isle of Wight. The Cretaceous rocks are famous for their dinosaurs, but little appreciated is the fact that the Island's fossil record preserves dinosaurs from more than one section of history -- and some of those sections, even today, are poorly known.

"Unusually, this specimen eroded out of the Vectis Formation, which is notoriously poor in dinosaur fossils," said corresponding author Dr Neil Gostling, who teaches evolution and palaeobiology at the University of Southampton. "It's likely to be the youngest spinosaur material yet known from the UK."

The 125 million year old Vectis Formation preserves the beginning of a period of rising sea levels, where the 'White Rock spinosaurid' stalked lagoonal waters and sandflats in search of food.

"Because it's only known from fragments at the moment, we haven't given it a formal scientific name" said co-author Darren Naish. He added: "We hope that additional remains will turn up in time.

"This new animal bolsters our previous argument -- published last year -- that spinosaurid dinosaurs originated and diversified in western Europe before becoming more widespread."

Marks on the bone also showed how, even after death, the body of this giant probably supported a range of scavengers and decomposers.

"Most of these amazing fossils were found by Nick Chase, one of Britain's most skilled dinosaur hunters, who sadly died just before the Covid epidemic," said co-author Jeremy Lockwood, a PhD student at the University of Portsmouth and Natural History Museum. "I was searching for remains of this dinosaur with Nick and found a lump of pelvis with tunnels bored into it, each about the size of my index finger. We think they were caused by bone eating larvae of a type of scavenging beetle. It's an interesting thought that this giant killer wound up becoming a meal for a host of insects."

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Bizarre meat-eating dinosaur joins 'Rogues' Gallery' of giant predators from classic fossil site in Egypt's Sahara Desert

An Egyptian-American team of researchers has announced the discovery of a new kind of large-bodied meat-eating dinosaur, or theropod, from a celebrated fossil site in Egypt's Sahara Desert. The fossil of a still-unnamed species provides the first known record of the abelisaurid group of theropods from a middle Cretaceous-aged (approximately 98 million years old) rock unit known as the Bahariya Formation, which is exposed in the Bahariya Oasis of the Western Desert of Egypt.

In the early 20th century, this locality famously yielded the original specimens of a host of remarkable dinosaurs -- including the colossal sail-backed fish-eater Spinosaurus -- which were then destroyed in World War II. Abelisaurid fossils had previously been found in Europe and in many of today's Southern Hemisphere continents, but never before from the Bahariya Formation. The team describes the Bahariya abelisaurid discovery in a paper published today in Royal Society Open Science.

The study was led by Ohio University graduate student Belal Salem, based on work he initiated while a member of the Mansoura University Vertebrate Paleontology Center (MUVP) in Mansoura, Egypt. The research team also included Ohio University Heritage College of Osteopathic Medicine professor of biomedical sciences Patrick O'Connor; Matt Lamanna, associate curator of vertebrate paleontology at Carnegie Museum of Natural History; Sanaa El-Sayed, a doctoral student at the University of Michigan and the MUVP's former vice director; Hesham Sallam, a professor at the American University in Cairo (AUC) and Mansoura University and the founding director of the MUVP; and additional colleagues from Benha University and the Egyptian Environmental Affairs Agency.

The fossil in question, a well-preserved vertebra from the base of the neck, was recovered by a 2016 MUVP expedition to the Bahariya Oasis. The vertebra belongs to an abelisaurid, a kind of bulldog-faced, small-toothed, tiny-armed theropod that is estimated to have been roughly six meters (20 feet) in body length. Abelisaurids -- most notably represented by the horned, demonic-looking Patagonian form Carnotaurus of Jurassic World and Prehistoric Planet fame -- were among the most diverse and geographically widespread large predatory dinosaurs in the southern landmasses during the Cretaceous Period, the final time period of the Age of Dinosaurs. Along with Spinosaurus and two other giant theropods (Carcharodontosaurus and Bahariasaurus), the new abelisaurid fossil adds yet another species to the cadre of large predatory dinosaurs that roamed what is now the Egyptian Sahara roughly 98 million years ago.

"During the mid-Cretaceous, the Bahariya Oasis would've been one of the most terrifying places on the planet," says Salem, a new student in the biological sciences graduate program at Ohio University. "How all these huge predators managed to coexist remains a mystery, though it's probably related to their having eaten different things, their having adapted to hunt different prey."

The new vertebra holds implications for the biodiversity of Cretaceous dinosaurs in Egypt and the entire northern region of Africa. It is the oldest known fossil of Abelisauridae from northeastern Africa, and shows that, during the mid-Cretaceous, these carnivorous dinosaurs ranged across much of the northern part of the continent, east to west from present day Egypt to Morocco, to as far south as Niger and potentially beyond. Spinosaurus and Carcharodontosaurus are also known from Niger and Morocco, and a close relative of Bahariasaurus has been found in the latter nation as well, suggesting that this fauna of large to gigantic theropods coexisted throughout much of northern Africa at this time.

How can the discovery of a single neck vertebra lead researchers to conclude that the fossil belongs to a member of Abelisauridae, a kind of carnivorous dinosaur that has never been found in the Bahariya Formation before? The answer is remarkably simple: it is virtually identical to the same bone in other, better-known abelisaurids such as Carnotaurus from Argentina and Majungasaurus from Madagascar. As coauthor and Salem's graduate advisor Patrick O'Connor, who in 2007 published an exhaustive study of the vertebral anatomy of Majungasaurus,explains, "I've examined abelisaur skeletons from Patagonia to Madagascar. My first glimpse of this specimen from photos left no doubt about its identity. Abelisaurid neck bones are so distinctive."

The Site

The Bahariya Oasis is renowned within paleontological circles for having yielded the type specimens (the original, first-discovered, name-bearing fossils) of several extraordinary dinosaurs during the early 20th century, including, most famously, Spinosaurus. Unfortunately, all Bahariya dinosaur fossils collected prior to World War II were destroyed during an Allied bombing of Munich in 1944.

As a graduate student in the early 2000s, study coauthor Matt Lamanna helped make the first dinosaur discoveries from the oasis since the infamous 1944 air raid, including the gargantuan sauropod (long-necked plant-eating dinosaur) Paralititan. "The Bahariya Oasis has taken on near-legendary status among paleontologists for having produced the first-known fossils of some of the world's most amazing dinosaurs," says Lamanna, "but for more than three quarters of a century, those fossils have existed only as pictures in old books." Thankfully, discoveries made during recent expeditions led by researchers from AUC and MUVP -- such as the new abelisaurid vertebra -- are helping to restore the paleontological legacy of this classic site. These expeditions have recovered a wealth of additional fossils that the researchers plan to unveil in the near future.

As team member Sanaa El-Sayed, who co-led the 2016 expedition that collected the abelisaurid vertebra, explains, "This bone is just the first of many important new dinosaur fossils from the Bahariya Oasis."

The Bahariya Formation holds promise to shed further light on mid-Cretaceous African dinosaurs and the vanished ecosystems in which they once lived. Unlike more thoroughly explored rocks of the same age in Morocco that tend to yield isolated bones, the Bahariya Formation appears to preserve partial skeletons of dinosaurs and other land-living animals with a relatively high degree of frequency. The more bones that are preserved within the skeleton of a given fossil backboned species, the more paleontologists can generally learn about it. The propensity of the Bahariya Oasis for producing associated partial skeletons suggests that much remains to be learned from this historic locality.

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High optimism linked with longer life and living past 90 in women across racial, ethnic groups

Higher levels of optimism were associated with longer lifespan and living beyond age 90 in women across racial and ethnic groups in a study led by researchers at Harvard T.H. Chan School of Public Health.

"Although optimism itself may be affected by social structural factors, such as race and ethnicity, our research suggests that the benefits of optimism may hold across diverse groups," said Hayami Koga, a PhD candidate in the Department of Social and Behavioral Sciences at Harvard Chan School and lead author of the study. "A lot of previous work has focused on deficits or risk factors that increase the risks for diseases and premature death. Our findings suggest that there's value to focusing on positive psychological factors, like optimism, as possible new ways of promoting longevity and healthy aging across diverse groups."

The study will be published online on June 8, 2022, in the Journal of the American Geriatrics Society.

In a previous study, the research group determined that optimism was linked to a longer lifespan and exceptional longevity, which was defined as living beyond 85 years of age. Because they had looked at mostly white populations in that previous study, Koga and her colleagues broadened the participant pool in the current study to include women from across racial and ethnic groups. According to Koga, including diverse populations in research is important to public health because these groups have higher mortality rates than white populations, and there is limited research about them to help inform health policy decisions.

For this study, the researchers analyzed data and survey responses from 159,255 participants in the Women's Health Initiative, which included postmenopausal women in the U.S. The women enrolled at ages 50-79 from 1993 to 1998 and were followed for up to 26 years.

Of the participants, the 25% who were the most optimistic were likely to have a 5.4% longer lifespan and a 10% greater likelihood of living beyond 90 years than the 25% who were the least optimistic. The researchers also found no interaction between optimism and any categories of race and ethnicity, and these trends held true after taking into account demographics, chronic conditions, and depression. Lifestyle factors, such as regular exercise and healthy eating, accounted for less than a quarter of the optimism-lifespan association, indicating that other factors may be at play.

Koga said that the study's results could reframe how people view the decisions that affect their health.

"We tend to focus on the negative risk factors that affect our health," said Koga. "It is also important to think about the positive resources such as optimism that may be beneficial to our health, especially if we see that these benefits are seen across racial and ethnic groups."

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