In Swahili, red-billed oxpeckers are called Askari wa kifaru, or "the rhino's guard." Now, a paper appearing April 9 in the journal Current Biology suggests that this indigenous name rings true: red-billed oxpeckers may act as a first line of defense against poachers by behaving like sentinels, sounding an alarm to potential danger. By tracking wild black rhinos, researchers found that those carrying oxpeckers were far better at sensing and avoiding humans than those without the hitchhiking bird.
While conservation efforts have rebounded the critically endangered black rhino's numbers, poaching remains a major threat. "Although black rhinos have large, rapier-like horns and a thick hide, they are as blind as a bat. If the conditions are right, a hunter could walk within five meters of one, as long as they are downwind," says Roan Plotz (@RoanPlotz), a lecturer and behavioral ecologist at Victoria University, Australia., who co-authored the paper with ecological scientist Wayne Linklater (@PolitEcol) of California State University -- Sacramento. Oxpeckers, which are known to feed on the ticks and lesions found on the rhino's body, may make up for the rhino's poor eyesight by calling out if they detect an approaching human.
To study the role that oxpeckers might play, Plotz and his team recorded the number of oxpeckers on two groups of the rhinos they encountered. Rhinos tagged with radio transmitters -- which allowed researchers to track them while evading detection from oxpeckers -- carried the bird on their backs more than half the time. The untagged black rhinos they found, on the other hand, carried no oxpeckers most of the time -- suggesting that other untagged rhinos that carried the birds might have avoided encountering the researchers altogether. "Using the differences we observed between oxpeckers on the tagged versus untagged rhinos, we estimated that between 40% and 50% of all possible black rhino encounters were thwarted by the presence of oxpeckers," says Plotz.
Even when the researchers were able to locate the tagged rhinos, the oxpeckers' alarm calls still appeared to play a role in predator defense. The field team ran a "human approach" experiment, where one researcher would walk towards the rhino from crosswind while a colleague recorded the rhino's behavior. The field team recorded the number of oxpecker carried, the rhinos' behavior upon approach, and the distance of the researcher when either the rhinos became vigilant or, if undetected, it became unsafe to get any closer.
"Our experiment found that rhinos without oxpeckers detected a human approaching only 23% of the time. Due to the bird's alarm call, those with oxpeckers detected the approaching human in 100% of our trials and at an average distance of 61 meters -- nearly four times further than when rhinos were alone. In fact, the more oxpeckers the rhino carried, the greater the distance at which a human was detected," he says. He adds that these improved detection and distance estimates may even be conservative, because they don't take into account the untagged rhinos carrying oxpeckers that the team could not detect.
When a rhino perceived the oxpecker alarm call, it nearly always re-oriented itself to face downwind -- their sensory blind spot. "Rhinos cannot smell predators from downwind, making it their most vulnerable position. This is particularly true from humans, who primarily hunt game from that direction," says Plotz.
Taken together, these results suggest that oxpeckers are effective companions that enable black rhinos to evade encounters with people and facilitate effective anti-predator strategies once found. Some scientists even hypothesize that oxpeckers evolved this adaptive behaviour as a way to protect their source of food: the rhinos.
"Rhinos have been hunted by humans for tens of thousands of years, but the species was driven to the brink of extinction over the last 150 years. One hypothesis is that oxpeckers have evolved this cooperative relationship with rhinos relatively recently to protect their food source from human overkill," says Plotz.
Despite this closely tied relationship, oxpecker populations have significantly declined, even becoming locally extinct in some areas. As a result, most wild black rhino populations now live without oxpeckers in their environment. But based on the findings in this study, reintroducing the bird back into rhino populations may bolster conservation efforts. "While we do not know that reintroducing the birds would significantly reduce hunting impacts, we do know oxpeckers would help rhinos evade detection, which on its own is a great benefit," says Plotz.
Read more at Science Daily
Apr 10, 2020
In a first, NASA measures wind speed on a brown dwarf
For the first time, scientists have directly measured wind speed on a brown dwarf, an object larger than Jupiter (the largest planet in our solar system) but not quite massive enough to become a star. To achieve the finding, they used a new method that could also be applied to learn about the atmospheres of gas-dominated planets outside our solar system.
Described in a paper in the journal Science, the work combines observations by a group of radio telescopes with data from NASA's recently retired infrared observatory, the Spitzer Space Telescope, managed by the agency's Jet Propulsion Laboratory in Southern California.
Officially named 2MASS J10475385+2124234, the target of the new study was a brown dwarf located 32 light-years from Earth -- a stone's throw away, cosmically speaking. The researchers detected winds moving around the planet at 1,425 mph (2,293 kph). For comparison, Neptune's atmosphere features the fastest winds in the solar system, which whip through at more than 1,200 mph (about 2,000 kph).
Measuring wind speed on Earth means clocking the motion of our gaseous atmosphere relative to the planet's solid surface. But brown dwarfs are composed almost entirely of gas, so "wind" refers to something slightly different. The upper layers of a brown dwarf are where portions of the gas can move independently. At a certain depth, the pressure becomes so intense that the gas behaves like a single, solid ball that is considered the object's interior. As the interior rotates, it pulls the upper layers -- the atmosphere -along so that the two are almost in synch.
In their study, the researchers measured the slight difference in speed of the brown dwarf's atmosphere relative to its interior. With an atmospheric temperature of over 1,100 degrees Fahrenheit (600 degrees Celsius), this particular brown dwarf radiates a substantial amount of infrared light. Coupled with its close proximity to Earth, this characteristic made it possible for Spitzer to detect features in the brown dwarf's atmosphere as they rotate in and out of view. The team used those features to clock the atmospheric rotation speed.
To determine the speed of the interior, they focused on the brown dwarf's magnetic field. A relatively recent discovery found that the interiors of brown dwarfs generate strong magnetic fields. As the brown dwarf rotates, the magnetic field accelerates charged particles that in turn produce radio waves, which the researchers detected with the radio telescopes in the Karl G. Jansky Very Large Array in New Mexico.
Planetary Atmospheres
The new study is the first to demonstrate this comparative method for measuring wind speed on a brown dwarf. To gauge its accuracy, the group tested the technique using infrared and radio observations of Jupiter, which is also composed mostly of gas and has a physical structure similar to a small brown dwarf. The team compared the rotation rates of Jupiter's atmosphere and interior using data that was similar to what they were able to collect for the much more distant brown dwarf. They then confirmed their calculation for Jupiter's wind speed using more detailed data collected by probes that have studied Jupiter up close, thus demonstrating that their approach for the brown dwarf worked.
Scientists have previously used Spitzer to infer the presence of winds on exoplanets and brown dwarfs based on variations in the brightness of their atmospheres in infrared light. And data from the High Accuracy Radial velocity Planet Searcher (HARPS) -- an instrument on the European Southern Observatory's La Silla telescope in Chile -- has been used to make a direct measurement of wind speeds on a distant planet.
But the new paper represents the first time scientists have directly compared the atmospheric speed with the speed of a brown dwarf's interior. The method employed could be applied to other brown dwarfs or to large planets if the conditions are right, according to the authors.
"We think this technique could be really valuable to providing insight into the dynamics of exoplanet atmospheres," said lead author Katelyn Allers, an associate professor of physics and astronomy at Bucknell University in Lewisburg, Pennsylvania. "What's really exciting is being able to learn about how the chemistry, the atmospheric dynamics and the environment around an object are interconnected, and the prospect of getting a really comprehensive view into these worlds."
Read more at Science Daily
Described in a paper in the journal Science, the work combines observations by a group of radio telescopes with data from NASA's recently retired infrared observatory, the Spitzer Space Telescope, managed by the agency's Jet Propulsion Laboratory in Southern California.
Officially named 2MASS J10475385+2124234, the target of the new study was a brown dwarf located 32 light-years from Earth -- a stone's throw away, cosmically speaking. The researchers detected winds moving around the planet at 1,425 mph (2,293 kph). For comparison, Neptune's atmosphere features the fastest winds in the solar system, which whip through at more than 1,200 mph (about 2,000 kph).
Measuring wind speed on Earth means clocking the motion of our gaseous atmosphere relative to the planet's solid surface. But brown dwarfs are composed almost entirely of gas, so "wind" refers to something slightly different. The upper layers of a brown dwarf are where portions of the gas can move independently. At a certain depth, the pressure becomes so intense that the gas behaves like a single, solid ball that is considered the object's interior. As the interior rotates, it pulls the upper layers -- the atmosphere -along so that the two are almost in synch.
In their study, the researchers measured the slight difference in speed of the brown dwarf's atmosphere relative to its interior. With an atmospheric temperature of over 1,100 degrees Fahrenheit (600 degrees Celsius), this particular brown dwarf radiates a substantial amount of infrared light. Coupled with its close proximity to Earth, this characteristic made it possible for Spitzer to detect features in the brown dwarf's atmosphere as they rotate in and out of view. The team used those features to clock the atmospheric rotation speed.
To determine the speed of the interior, they focused on the brown dwarf's magnetic field. A relatively recent discovery found that the interiors of brown dwarfs generate strong magnetic fields. As the brown dwarf rotates, the magnetic field accelerates charged particles that in turn produce radio waves, which the researchers detected with the radio telescopes in the Karl G. Jansky Very Large Array in New Mexico.
Planetary Atmospheres
The new study is the first to demonstrate this comparative method for measuring wind speed on a brown dwarf. To gauge its accuracy, the group tested the technique using infrared and radio observations of Jupiter, which is also composed mostly of gas and has a physical structure similar to a small brown dwarf. The team compared the rotation rates of Jupiter's atmosphere and interior using data that was similar to what they were able to collect for the much more distant brown dwarf. They then confirmed their calculation for Jupiter's wind speed using more detailed data collected by probes that have studied Jupiter up close, thus demonstrating that their approach for the brown dwarf worked.
Scientists have previously used Spitzer to infer the presence of winds on exoplanets and brown dwarfs based on variations in the brightness of their atmospheres in infrared light. And data from the High Accuracy Radial velocity Planet Searcher (HARPS) -- an instrument on the European Southern Observatory's La Silla telescope in Chile -- has been used to make a direct measurement of wind speeds on a distant planet.
But the new paper represents the first time scientists have directly compared the atmospheric speed with the speed of a brown dwarf's interior. The method employed could be applied to other brown dwarfs or to large planets if the conditions are right, according to the authors.
"We think this technique could be really valuable to providing insight into the dynamics of exoplanet atmospheres," said lead author Katelyn Allers, an associate professor of physics and astronomy at Bucknell University in Lewisburg, Pennsylvania. "What's really exciting is being able to learn about how the chemistry, the atmospheric dynamics and the environment around an object are interconnected, and the prospect of getting a really comprehensive view into these worlds."
Read more at Science Daily
Doubts about basic assumption for the universe
No matter where we look, the same rules apply everywhere in space: countless calculations of astrophysics are based on this basic principle. A recent study by the Universities of Bonn and Harvard, however, has thrown this principle into question. Should the measured values be confirmed, this would toss many assumptions about the properties of the universe overboard. The results are published in the journal Astronomy & Astrophysics, but are already available online.
Since the big bang, the universe has swollen like a freshly formed raisin roll put in a warm place to rise. Until recently, it was thought that this increase in size was occurring evenly in all directions, as with a good yeast dough. Astrophysicists call this "isotropy." Many calculations on the fundamental properties of the universe are based on this assumption. It is possible that they are all wrong -- or at least, inaccurate -- thanks to compelling observations and analyses of the scientists from the Universities of Bonn and Harvard.
For they have put the isotropy hypothesis to the test for the first time with a new method that allows more reliable statements than before. With an unexpected result: According to this method, some areas in space expand faster than they should, while others expand more slowly than expected. "In any case, this conclusion is suggested by our measurements," states Konstantinos Migkas, from the Argelander Institute for Astronomy at the University of Bonn.
Migkas and his colleagues have developed a new, efficient isotropy test in their study. It is based on the observation of so-called galaxy clusters -- in a sense, the raisins in the yeast bun. The clusters emit X-ray radiation that can be collected on Earth (in this case, this was done by the satellite-based telescopes Chandra and XMM-Newton). The temperature of the galaxy clusters can be calculated based on certain characteristics of the radiation. Also, their brightness can be measured. The hotter they are, the brighter they glow.
In an isotropic universe, a simple rule applies. The further away a celestial object is from us, the faster it moves away from us. From its speed, we can therefore deduce its distance from us, regardless of the direction in which the object lies. At least that's what we thought until now. "In reality, however, our brightness measurements seem to disagree with the above distance calculation," Migkas emphasizes.
This is because the amount of light that reaches the earth decreases with increasing distance. So, anyone who knows the original luminosity of a celestial body and its distance knows how bright it should shine in the telescope image. And it is precisely at this point that scientists have come across discrepancies that are difficult to reconcile with the isotropy hypothesis: that some galaxy clusters are much fainter than expected. Their distance from Earth is probably much greater than calculated from their speed. And for some others, however, the opposite is the case.
"There are only three possible explanations for this," states Migkas, who is doing his doctorate in the research group of Prof. Dr. Thomas Reiprich at the Argelander Institute. "Firstly, it is possible that the X-ray radiation, whose intensity we have measured, is attenuated on its way from the galaxy clusters to Earth. This could be due to as yet undiscovered gas or dust clouds inside or outside the Milky Way. In preliminary tests, however, we find this discrepancy between measurement and theory not only in X-rays but also at other wavelengths. It is extremely unlikely that any kind of matter nebula absorbs completely different types of radiation in the same way. But we won't know for sure for several months."
A second possibility are so-called "bulk flows." These are groups of neighboring galaxy clusters that move continuously in a certain direction -- for example, due to some structures in space that generate strong gravitational forces. These would therefore attract the galaxy clusters to themselves and thus change their speed (and thus also their derived distance). "This effect would also mean that many calculations on the properties of the local universe would be imprecise and would have to be repeated," explains Migkas.
The third possibility is the most serious: What if the universe is not isotropic at all? What if -- metaphorically speaking -- the yeast in the galactic raisin roll is so unevenly distributed that it quickly bulges in some places while it hardly grows at all in other regions? Such an anisotropy could, for example, result from the properties of the mysterious "dark energy," which acts as an additional driving force for the expansion of the universe. However, a theory is still missing that would make the behavior of the Dark Energy consistent with the observations. "If we succeed in developing such a theory, it could greatly accelerate the search for the exact nature of this form of energy," Migkas is certain.
Read more at Science Daily
Since the big bang, the universe has swollen like a freshly formed raisin roll put in a warm place to rise. Until recently, it was thought that this increase in size was occurring evenly in all directions, as with a good yeast dough. Astrophysicists call this "isotropy." Many calculations on the fundamental properties of the universe are based on this assumption. It is possible that they are all wrong -- or at least, inaccurate -- thanks to compelling observations and analyses of the scientists from the Universities of Bonn and Harvard.
For they have put the isotropy hypothesis to the test for the first time with a new method that allows more reliable statements than before. With an unexpected result: According to this method, some areas in space expand faster than they should, while others expand more slowly than expected. "In any case, this conclusion is suggested by our measurements," states Konstantinos Migkas, from the Argelander Institute for Astronomy at the University of Bonn.
Migkas and his colleagues have developed a new, efficient isotropy test in their study. It is based on the observation of so-called galaxy clusters -- in a sense, the raisins in the yeast bun. The clusters emit X-ray radiation that can be collected on Earth (in this case, this was done by the satellite-based telescopes Chandra and XMM-Newton). The temperature of the galaxy clusters can be calculated based on certain characteristics of the radiation. Also, their brightness can be measured. The hotter they are, the brighter they glow.
In an isotropic universe, a simple rule applies. The further away a celestial object is from us, the faster it moves away from us. From its speed, we can therefore deduce its distance from us, regardless of the direction in which the object lies. At least that's what we thought until now. "In reality, however, our brightness measurements seem to disagree with the above distance calculation," Migkas emphasizes.
This is because the amount of light that reaches the earth decreases with increasing distance. So, anyone who knows the original luminosity of a celestial body and its distance knows how bright it should shine in the telescope image. And it is precisely at this point that scientists have come across discrepancies that are difficult to reconcile with the isotropy hypothesis: that some galaxy clusters are much fainter than expected. Their distance from Earth is probably much greater than calculated from their speed. And for some others, however, the opposite is the case.
"There are only three possible explanations for this," states Migkas, who is doing his doctorate in the research group of Prof. Dr. Thomas Reiprich at the Argelander Institute. "Firstly, it is possible that the X-ray radiation, whose intensity we have measured, is attenuated on its way from the galaxy clusters to Earth. This could be due to as yet undiscovered gas or dust clouds inside or outside the Milky Way. In preliminary tests, however, we find this discrepancy between measurement and theory not only in X-rays but also at other wavelengths. It is extremely unlikely that any kind of matter nebula absorbs completely different types of radiation in the same way. But we won't know for sure for several months."
A second possibility are so-called "bulk flows." These are groups of neighboring galaxy clusters that move continuously in a certain direction -- for example, due to some structures in space that generate strong gravitational forces. These would therefore attract the galaxy clusters to themselves and thus change their speed (and thus also their derived distance). "This effect would also mean that many calculations on the properties of the local universe would be imprecise and would have to be repeated," explains Migkas.
The third possibility is the most serious: What if the universe is not isotropic at all? What if -- metaphorically speaking -- the yeast in the galactic raisin roll is so unevenly distributed that it quickly bulges in some places while it hardly grows at all in other regions? Such an anisotropy could, for example, result from the properties of the mysterious "dark energy," which acts as an additional driving force for the expansion of the universe. However, a theory is still missing that would make the behavior of the Dark Energy consistent with the observations. "If we succeed in developing such a theory, it could greatly accelerate the search for the exact nature of this form of energy," Migkas is certain.
Read more at Science Daily
Ancient teeth from Peru hint now-extinct monkeys crossed Atlantic from Africa
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| Marmoset. Ucayalipithecus perdita would have been very small, similar in size to a modern-day marmoset. |
The teeth are from a newly discovered species belonging to an extinct family of African primates known as parapithecids. Fossils discovered at the same site in Peru had earlier offered the first proof that South American monkeys evolved from African primates.
The monkeys are believed to have made the more than 900-mile trip on floating rafts of vegetation that broke off from coastlines, possibly during a storm.
"This is a completely unique discovery," said Erik Seiffert, the study's lead author and Professor of Clinical Integrative Anatomical Sciences at Keck School of Medicine of USC. "It shows that in addition to the New World monkeys and a group of rodents known as caviomorphs -- there is this third lineage of mammals that somehow made this very improbable transatlantic journey to get from Africa to South America."
Researchers have named the extinct monkey Ucayalipithecus perdita. The name comes from Ucayali, the area of the Peruvian Amazon where the teeth were found, pithikos, the Greek word for monkey and perdita, the Latin word for lost.
Ucayalipithecus perdita would have been very small, similar in size to a modern-day marmoset.
Dating the migration
Researchers believe the site in Ucayali where the teeth were found is from a geological epoch known as the Oligocene, which extended from about 34 million to 23 million years ago.
Based on the age of the site and the closeness of Ucayalipithecus to its fossil relatives from Egypt, researchers estimate the migration might have occurred around 34 million years ago.
"We're suggesting that this group might have made it over to South America right around what we call the Eocene-Oligocene Boundary, a time period between two geological epochs, when the Antarctic ice sheet started to build up and the sea level fell," said Seiffert. "That might have played a role in making it a bit easier for these primates to actually get across the Atlantic Ocean."
An improbable discovery
Two of the Ucayalipithecus perdita teeth were identified by Argentinean co-authors of the study in 2015 showing that New World monkeys had African forebears. When Seiffert was asked to help describe these specimens in 2016, he noticed the similarity of the two broken upper molars to an extinct 32 million-year-old parapithecid monkey species from Egypt he had studied previously.
An expedition to the Peruvian fossil site in 2016 led to the discovery of two more teeth belonging to this new species. The resemblance of these additional lower teeth to those of the Egyptian monkey teeth confirmed to Seiffert that Ucayalipithecus was descended from African ancestors.
"The thing that strikes me about this study more than any other I've been involved in is just how improbable all of it is," said Seiffert. "The fact that it's this remote site in the middle of nowhere, that the chances of finding these pieces is extremely small, to the fact that we're revealing this very improbable journey that was made by these early monkeys, it's all quite remarkable."
About this study
In addition to Seiffert, the study's other authors are Marcelo Tejedor and Nelson Novo from the Instituto Patagónico de Geología y Paleontología (CCT CONICET -- CENPAT); John G. Fleagle from the Department of Anatomical Sciences, Renaissance School of Medicine, Stony Brook University; Fanny Cornejo and Dorien de Vries from the Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University; Mariano Bond from CONICET, División Paleontología Vertebrados, Museo de Ciencias Naturales de La Plata and Kenneth E. Campbell Jr. from the Department of Vertebrate Zoology, Natural History Museum of Los Angeles County.
Read more at Science Daily
Apr 9, 2020
Origins of Earth's magnetic field remain a mystery
Microscopic minerals excavated from an ancient outcrop of Jack Hills, in Western Australia, have been the subject of intense geological study, as they seem to bear traces of the Earth's magnetic field reaching as far back as 4.2 billion years ago. That's almost 1 billion years earlier than when the magnetic field was previously thought to originate, and nearly back to the time when the planet itself was formed.
But as intriguing as this origin story may be, an MIT-led team has now found evidence to the contrary. In a paper published in Science Advances, the team examined the same type of crystals, called zircons, excavated from the same outcrop, and have concluded that zircons they collected are unreliable as recorders of ancient magnetic fields.
In other words, the jury is still out on whether the Earth's magnetic field existed earlier than 3.5 billion years ago.
"There is no robust evidence of a magnetic field prior to 3.5 billion years ago, and even if there was a field, it will be very difficult to find evidence for it in Jack Hills zircons," says Caue Borlina, a graduate student in MIT's Department of Earth, Atmospheric, and Planetary Sciences (EAPS). "It's an important result in the sense that we know what not to look for anymore."
Borlina is the paper's first author, which also includes EAPS Professor Benjamin Weiss, Principal Research Scientist Eduardo Lima, and Research Scientist Jahandar Ramezan of MIT, along with others from Cambridge University, Harvard University, the University of California at Los Angeles, the University of Alabama, and Princeton University.
A field, stirred up
Earth's magnetic field is thought to play an important role in making the planet habitable. Not only does a magnetic field set the direction of our compass needles, it also acts as a shield of sorts, deflecting away solar wind that might otherwise eat away at the atmosphere.
Scientists know that today the Earth's magnetic field is powered by the solidification of the planet's liquid iron core. The cooling and crystallization of the core stirs up the surrounding liquid iron, creating powerful electric currents that generate a magnetic field stretching far out into space. This magnetic field is known as the geodynamo.
Multiple lines of evidence have shown that the Earth's magnetic field existed at least 3.5 billion years ago. However, the planet's core is thought to have started solidifying just 1 billion years ago, meaning that the magnetic field must have been driven by some other mechanism prior to 1 billion years ago. Pinning down exactly when the magnetic field formed could help scientists figure out what generated it to begin with.
Borlina says the origin of Earth's magnetic field could also illuminate the early conditions in which Earth's first life forms took hold.
"In the Earth's first billion years, between 4.4 billion and 3.5 billion years, that's when life was emerging," Borlina says. "Whether you have a magnetic field at that time has different implications for the environment in which life emerged on Earth. That's the motivation for our work."
"Can't trust zircon"
Scientists have traditionally used minerals in ancient rocks to determine the orientation and intensity of Earth's magnetic field back through time. As rocks form and cool, the electrons within individual grains can shift in the direction of the surrounding magnetic field. Once the rock cools past a certain temperature, known as the Curie temperature, the orientations of the electrons are set in stone, so to speak. Scientists can determine their age and use standard magnetometers to measure their orientation, to estimate the strength and orientation of the Earth's magnetic field at a given point in time.
Since 2001, Weiss and his group have been studying the magnetization of the Jack Hills rocks and zircon grains, with the challenging goal of establishing whether they contain ancient records of the Earth's magnetic field.
"The Jack Hills zircons are some of the most weakly magnetic objects studied in the history of paleomagnetism," Weiss says. "Furthermore, these zircons include the oldest known Earth materials, meaning that there are many geological events that could have reset their magnetic records."
In 2015, a separate research group that had also started studying the Jack Hills zircons argued that they found evidence of magnetic material in zircons that they dated to be 4.2 billion years old -- the first evidence that Earth's magnetic field may have existed prior to 3.5 billion years ago.
But Borlina notes that the team did not confirm whether the magnetic material they detected actually formed during or after the zircon crystal formed 4.2 billion years ago -- a goal that he and his team took on for their new paper.
Borlina, Weiss, and their colleagues had collected rocks from the same Jack Hills outcrop, and from those samples, extracted 3,754 zircon grains, each around 150 micrometers long -- about the width of a human hair. Using standard dating techniques, they determined the age of each zircon grain, which ranged from 1 billion to 4.2 billion years old.
Around 250 crystals were older than 3.5 billion years. The team isolated and imaged those samples, looking for signs of cracks or secondary materials, such as minerals that may have been deposited on or within the crystal after it had fully formed, and searched for evidence that they were significantly heated over the last few billion years since they formed. Of these 250, they identified just three zircons that were relatively free of such impurities and therefore could contain suitable magnetic records.
The team then carried out detailed experiments on these three zircons to determine what kinds of magnetic materials they might contain. They eventually determined that a magnetic mineral called magnetite was present in two of the three zircons. Using a high-resolution quantum diamond magnetometer, the team looked at cross-sections of each of the two zircons to map the location of the magnetite in each crystal.
They discovered magnetite lying along cracks or damaged zones within the zircons. Such cracks, Borlina says, are pathways that allow water and other elements inside the rock. Such cracks could have let in secondary magnetite that settled into the crystal much later than when the zircon originally formed. Either way, Borlina says the evidence is clear: These zircons cannot be used as a reliable recorder for Earth's magnetic field.
"This is evidence we can't trust these zircon measurements for the record of the Earth's magnetic field," Borlina says. "We've shown that, before 3.5 billion years ago, we still have no idea when Earth's magnetic field started."
Read more at Science Daily
But as intriguing as this origin story may be, an MIT-led team has now found evidence to the contrary. In a paper published in Science Advances, the team examined the same type of crystals, called zircons, excavated from the same outcrop, and have concluded that zircons they collected are unreliable as recorders of ancient magnetic fields.
In other words, the jury is still out on whether the Earth's magnetic field existed earlier than 3.5 billion years ago.
"There is no robust evidence of a magnetic field prior to 3.5 billion years ago, and even if there was a field, it will be very difficult to find evidence for it in Jack Hills zircons," says Caue Borlina, a graduate student in MIT's Department of Earth, Atmospheric, and Planetary Sciences (EAPS). "It's an important result in the sense that we know what not to look for anymore."
Borlina is the paper's first author, which also includes EAPS Professor Benjamin Weiss, Principal Research Scientist Eduardo Lima, and Research Scientist Jahandar Ramezan of MIT, along with others from Cambridge University, Harvard University, the University of California at Los Angeles, the University of Alabama, and Princeton University.
A field, stirred up
Earth's magnetic field is thought to play an important role in making the planet habitable. Not only does a magnetic field set the direction of our compass needles, it also acts as a shield of sorts, deflecting away solar wind that might otherwise eat away at the atmosphere.
Scientists know that today the Earth's magnetic field is powered by the solidification of the planet's liquid iron core. The cooling and crystallization of the core stirs up the surrounding liquid iron, creating powerful electric currents that generate a magnetic field stretching far out into space. This magnetic field is known as the geodynamo.
Multiple lines of evidence have shown that the Earth's magnetic field existed at least 3.5 billion years ago. However, the planet's core is thought to have started solidifying just 1 billion years ago, meaning that the magnetic field must have been driven by some other mechanism prior to 1 billion years ago. Pinning down exactly when the magnetic field formed could help scientists figure out what generated it to begin with.
Borlina says the origin of Earth's magnetic field could also illuminate the early conditions in which Earth's first life forms took hold.
"In the Earth's first billion years, between 4.4 billion and 3.5 billion years, that's when life was emerging," Borlina says. "Whether you have a magnetic field at that time has different implications for the environment in which life emerged on Earth. That's the motivation for our work."
"Can't trust zircon"
Scientists have traditionally used minerals in ancient rocks to determine the orientation and intensity of Earth's magnetic field back through time. As rocks form and cool, the electrons within individual grains can shift in the direction of the surrounding magnetic field. Once the rock cools past a certain temperature, known as the Curie temperature, the orientations of the electrons are set in stone, so to speak. Scientists can determine their age and use standard magnetometers to measure their orientation, to estimate the strength and orientation of the Earth's magnetic field at a given point in time.
Since 2001, Weiss and his group have been studying the magnetization of the Jack Hills rocks and zircon grains, with the challenging goal of establishing whether they contain ancient records of the Earth's magnetic field.
"The Jack Hills zircons are some of the most weakly magnetic objects studied in the history of paleomagnetism," Weiss says. "Furthermore, these zircons include the oldest known Earth materials, meaning that there are many geological events that could have reset their magnetic records."
In 2015, a separate research group that had also started studying the Jack Hills zircons argued that they found evidence of magnetic material in zircons that they dated to be 4.2 billion years old -- the first evidence that Earth's magnetic field may have existed prior to 3.5 billion years ago.
But Borlina notes that the team did not confirm whether the magnetic material they detected actually formed during or after the zircon crystal formed 4.2 billion years ago -- a goal that he and his team took on for their new paper.
Borlina, Weiss, and their colleagues had collected rocks from the same Jack Hills outcrop, and from those samples, extracted 3,754 zircon grains, each around 150 micrometers long -- about the width of a human hair. Using standard dating techniques, they determined the age of each zircon grain, which ranged from 1 billion to 4.2 billion years old.
Around 250 crystals were older than 3.5 billion years. The team isolated and imaged those samples, looking for signs of cracks or secondary materials, such as minerals that may have been deposited on or within the crystal after it had fully formed, and searched for evidence that they were significantly heated over the last few billion years since they formed. Of these 250, they identified just three zircons that were relatively free of such impurities and therefore could contain suitable magnetic records.
The team then carried out detailed experiments on these three zircons to determine what kinds of magnetic materials they might contain. They eventually determined that a magnetic mineral called magnetite was present in two of the three zircons. Using a high-resolution quantum diamond magnetometer, the team looked at cross-sections of each of the two zircons to map the location of the magnetite in each crystal.
They discovered magnetite lying along cracks or damaged zones within the zircons. Such cracks, Borlina says, are pathways that allow water and other elements inside the rock. Such cracks could have let in secondary magnetite that settled into the crystal much later than when the zircon originally formed. Either way, Borlina says the evidence is clear: These zircons cannot be used as a reliable recorder for Earth's magnetic field.
"This is evidence we can't trust these zircon measurements for the record of the Earth's magnetic field," Borlina says. "We've shown that, before 3.5 billion years ago, we still have no idea when Earth's magnetic field started."
Read more at Science Daily
Long-living tropical trees play outsized role in carbon storage
A group of trees that grow fast, live long lives and reproduce slowly account for the bulk of the biomass -- and carbon storage -- in some tropical rainforests, a team of scientists says in a paper published this week in the journal Science. The finding that these trees, called long-lived pioneers, play a much larger role in carbon storage than previously thought may have implications in efforts to preserve forests as a strategy to fight climate change.
"People have been arguing about whether these long-lived pioneers contribute much to carbon storage over the long term," said Caroline Farrior, an assistant professor of integrative biology at The University of Texas at Austin and a primary investigator on the study. "We were surprised to find that they do."
It is unclear the extent to which tropical rainforests can help soak up excess carbon dioxide in the atmosphere produced by burning fossil fuels. Nonetheless, the new study provides insights about the role of different species of trees in carbon storage.
Using more than 30 years' worth of data collected from a tropical rainforest in Panama, the team has uncovered some key traits of trees that, when integrated into computer models related to climate change, will improve the models' accuracy. With the team's improved model, the scientists plan to begin answering questions about what drives forest composition over time and what factors affect carbon storage.
Most existing Earth system models used to forecast global climate decades from now, including those used by the Intergovernmental Panel on Climate Change, represent the trees in a forest as all basically the same.
"This analysis shows that that is not good enough for tropical forests and provides a way forward," Farrior said. "We show that the variation in tropical forest species's growth, survival and reproduction is important for predicting forest carbon storage."
The project was led by Nadja Rüger, research fellow at the German Centre for Integrative Biodiversity Research (iDiv), Halle-Jena-Leipzig.
In addition to the finding about long-lived pioneers, the team found the composition of a tropical forest over time depends on how each tree species balances two different sets of trade-offs: growth versus survival (for example, one type of tree might grow fast but die young) and stature versus reproduction (another might grow tall but reproduce leisurely). Plotting every species as a point on a graph based on where they fall along these two different axes allowed the scientists to have a more sophisticated and accurate model than prior ones, which usually focused exclusively on the first of these two trade-offs or parametrized the groups by different means.
"To really appreciate that there is this second trade-off between stature and reproduction, and that it's important in old-growth forests, is a big deal biologically," Farrior said.
The team also discovered that the nearly 300 unique tree species that live on Barro Colorado Island, which sits in the middle of the Panama Canal, can be represented in their computer model by just five functional groups and still produce accurate forecasts of tree composition and forest biomass over time.
It's not possible to directly verify the forecasts of a forest model in future decades. So the researchers did the next best thing: They seeded their model with forest composition data collected at their site in Panama during the 1980s and then ran the model forward to show that it accurately represents the changes that occurred from then until now. This is called "hindcasting."
Next, they plan to explore how a warming world might benefit trees with certain traits over others, shifting forest composition and the potential of forests to store carbon.
Read more at Science Daily
"People have been arguing about whether these long-lived pioneers contribute much to carbon storage over the long term," said Caroline Farrior, an assistant professor of integrative biology at The University of Texas at Austin and a primary investigator on the study. "We were surprised to find that they do."
It is unclear the extent to which tropical rainforests can help soak up excess carbon dioxide in the atmosphere produced by burning fossil fuels. Nonetheless, the new study provides insights about the role of different species of trees in carbon storage.
Using more than 30 years' worth of data collected from a tropical rainforest in Panama, the team has uncovered some key traits of trees that, when integrated into computer models related to climate change, will improve the models' accuracy. With the team's improved model, the scientists plan to begin answering questions about what drives forest composition over time and what factors affect carbon storage.
Most existing Earth system models used to forecast global climate decades from now, including those used by the Intergovernmental Panel on Climate Change, represent the trees in a forest as all basically the same.
"This analysis shows that that is not good enough for tropical forests and provides a way forward," Farrior said. "We show that the variation in tropical forest species's growth, survival and reproduction is important for predicting forest carbon storage."
The project was led by Nadja Rüger, research fellow at the German Centre for Integrative Biodiversity Research (iDiv), Halle-Jena-Leipzig.
In addition to the finding about long-lived pioneers, the team found the composition of a tropical forest over time depends on how each tree species balances two different sets of trade-offs: growth versus survival (for example, one type of tree might grow fast but die young) and stature versus reproduction (another might grow tall but reproduce leisurely). Plotting every species as a point on a graph based on where they fall along these two different axes allowed the scientists to have a more sophisticated and accurate model than prior ones, which usually focused exclusively on the first of these two trade-offs or parametrized the groups by different means.
"To really appreciate that there is this second trade-off between stature and reproduction, and that it's important in old-growth forests, is a big deal biologically," Farrior said.
The team also discovered that the nearly 300 unique tree species that live on Barro Colorado Island, which sits in the middle of the Panama Canal, can be represented in their computer model by just five functional groups and still produce accurate forecasts of tree composition and forest biomass over time.
It's not possible to directly verify the forecasts of a forest model in future decades. So the researchers did the next best thing: They seeded their model with forest composition data collected at their site in Panama during the 1980s and then ran the model forward to show that it accurately represents the changes that occurred from then until now. This is called "hindcasting."
Next, they plan to explore how a warming world might benefit trees with certain traits over others, shifting forest composition and the potential of forests to store carbon.
Read more at Science Daily
Looking for dark matter
Dark matter, which cannot be physically observed with ordinary instruments, is thought to account for well over half the matter in the Universe, but its properties are still mysterious. One commonly held theory states that it exists as 'clumps' of extremely light particles. When the earth passes through such a clump, the fundamental properties of matter are altered in ways that can be detected if instruments are sensitive enough. Physicists Rees McNally and Tanya Zelevinsky from Columbia University, New York, USA, have now published a paper in EPJ D proposing two new methods of looking for such perturbations and, thus, dark matter. This paper is part of a special issue of the journal on quantum technologies for gravitational physics.
Until now, searches for dark matter clumps have relied on the fact that tiny changes in the values of fundamental constants will alter the 'tick rate' of atomic clocks, some of which may be precise enough to pick up this difference. McNally and Zelevinsky's work adds methods that involve measuring a small extra 'push' or acceleration on normal matter caused by the clump, using, firstly, gravity sensors and, secondly, gravitational wave detectors. Gravity sensors are already spread around the world in the IGETS network, which is used for geological research; and scientists at the LIGO observatories in the United States are already looking for gravitational waves. Thus, McNally and Zelevinsky can mine the data from these ongoing experiments for evidence of dark matter.
McNally explains that this work was inspired by two things: the benefits of re-purposing existing experiments, and science fiction. "I enjoy novels like A Fire Upon the Deep [by Vernor Vinge] and The Three-Body Problem [by Liu Cixin] that explore what might happen if fundamental constants change, and it's fun to explore such things in the real world." As for practical applications of this work, however, he advised taking things one step at a time. "First we need to find out what Dark Matter is, then maybe we can find out how to use it."
From Science Daily
Until now, searches for dark matter clumps have relied on the fact that tiny changes in the values of fundamental constants will alter the 'tick rate' of atomic clocks, some of which may be precise enough to pick up this difference. McNally and Zelevinsky's work adds methods that involve measuring a small extra 'push' or acceleration on normal matter caused by the clump, using, firstly, gravity sensors and, secondly, gravitational wave detectors. Gravity sensors are already spread around the world in the IGETS network, which is used for geological research; and scientists at the LIGO observatories in the United States are already looking for gravitational waves. Thus, McNally and Zelevinsky can mine the data from these ongoing experiments for evidence of dark matter.
McNally explains that this work was inspired by two things: the benefits of re-purposing existing experiments, and science fiction. "I enjoy novels like A Fire Upon the Deep [by Vernor Vinge] and The Three-Body Problem [by Liu Cixin] that explore what might happen if fundamental constants change, and it's fun to explore such things in the real world." As for practical applications of this work, however, he advised taking things one step at a time. "First we need to find out what Dark Matter is, then maybe we can find out how to use it."
From Science Daily
Archaeologists on a 5,000-year-old egg hunt
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| Ostrich with eggs |
Long before Fabergé, ornate ostrich eggs were highly prized by the elites of Mediterranean civilisations during the Bronze and Iron Ages, but to date little has been known about the complex supply chain behind these luxury goods.
Examining ostrich eggs from the British Museum's collection, the team, led by Bristol's Dr Tamar Hodos, were able to reveal secrets about their origin and how and where they were made. Using state-of-the-art scanning electron microscopy, Dr Caroline Cartwright, Senior Scientist at the British Museum was able to investigate the eggs' chemical makeup to pinpoint their origins and study minute marks that reveal how they were made.
In the study, published today in the journal Antiquity, the researchers describe for the first time the surprisingly complex system behind ostrich egg production. This includes evidence about where the ostrich eggs were sourced, if the ostriches were captive or wild, and how the manufacture methods can be related to techniques and materials used by artisans in specific areas.
"The entire system of decorated ostrich egg production was much more complicated than we had imagined! We also found evidence to suggest the ancient world was much more interconnected than previously thought," said Dr Hodos, Reader in Mediterranean Archaeology in Bristol's School of Arts.
"Mediterranean ostriches were indigenous to the eastern Mediterranean and North Africa. Using a variety of isotopic indicators, we were able to distinguish eggs laid in different climatic zones (cooler, wetter and hotter, drier). What was most surprising to us was that eggs from both zones were found at sites in the other zone, suggestive of more extensive trade routes."
Dr Hodos and colleagues believe eggs were taken from wild birds' nests despite evidence of ostriches being kept in captivity during this period. This was no ordinary egg-hunt -- ostriches can be extremely dangerous so there was a tremendous risk involved in taking eggs from wild birds.
"We also found eggs require time to dry before the shell can be carved and therefore require safe storage. This has economic implications, since storage necessitates a long-term investment and this, combined with the risk involved, would add to an egg's luxury value," said Dr Hodos.
The study is part of an ongoing research project into ancient luxury goods, Globalising Luxuries.
Dr Hodos explains: "We are assessing not only how ancient luxuries were produced but also how they were used by different peoples. These questions are incredibly important for our own society today, in which the same object may have different social or symbolic meanings for different groups. Such knowledge and understanding helps foster tolerance and mutual respect in a multi-cultural society. If we can understand these mechanisms in the past, for which we have long-term outcomes in terms of social development, we can use this knowledge to better inform our own society in a number of ways."
Read more at Science Daily
Synchrotron X-ray sheds light on some of the world's oldest dinosaur eggs
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| Dinosaur egg concept |
University of the Witwatersrand scientists publish 3D reconstructions of the ~2cm-long skulls of some of the world's oldest dinosaur embryos in an article in Scientific Reports. The embryos, found in 1976 in Golden Gate Highlands National Park (Free State Province, South Africa) belong to South Africa's iconic dinosaur Massospondylus carinatus, a 5-meter long herbivore that nested in the Free State region 200 million years ago.
The scientific usefulness of the embryos was previously limited by their extremely fragile nature and tiny size. In 2015, scientists Kimi Chapelle and Jonah Choiniere, from the University of Witwatersrand, brought them to the European Synchrotron (ESRF) in Grenoble, France for scanning. At the ESRF, an 844 metre-ring of electrons travelling at the speed of light emits high-powered X-ray beams that can be used to non-destructively scan matter, including fossils. The embryos were scanned at an unprecedented level of detail -- at the resolution of an individual bone cell. With these data in hand, and after nearly 3 years of data processing at Wits' laboratory, the team was able to reconstruct a 3D model of the baby dinosaur skull. "No lab CT scanner in the world can generate these kinds of data," said Vincent Fernandez, one of the co-authors and scientist at the Natural History Museum in London (UK). "Only with a huge facility like the ESRF can we unlock the hidden potential of our most exciting fossils. This research is a great example of a global collaboration between Europe and the South African National Research Foundation," he adds.
Up until now, it was believed that the embryos in those eggs had died just before hatching. However, during the study, lead author Chapelle noticed similarities with the developing embryos of living dinosaur relatives (crocodiles, chickens, turtles, and lizards). By comparing which bones of the skull were present at different stages of their embryonic development, Chapelle and co-authors can now show that the Massospondylus embryos were actually much younger than previously thought and were only at 60% through their incubation period.
The team also found that each embryo had two types of teeth preserved in its developing jaws. One set was made up of very simple triangular teeth that would have been resorbed or shed before hatching, just like geckos and crocodiles today. The second set were very similar to those of adults, and would be the ones that the embryos hatched with. "I was really surprised to find that these embryos not only had teeth, but had two types of teeth. The teeth are so tiny; they range from 0.4 to 0.7mm wide. That's smaller than the tip of a toothpick!," explains Chapelle.
The conclusion of this research is that dinosaurs developed in the egg just like their reptilian relatives, whose embryonic developmental pattern hasn't changed in 200 million years. "It's incredible that in more than 250 million years of reptile evolution, the way the skull develops in the egg remains more or less the same. Goes to show -- you don't mess with a good thing!," concludes Jonah Choiniere, professor at the University of Witwatersrand and also co-author of the study.
Read more at Science Daily
Apr 8, 2020
False memories of crime appear real when retold to others
People are no better than chance at identifying when someone else is recounting a false or real memory of a crime, according to a new UCL study.
The findings, published in Frontiers in Psychology, build on a previous study that was the first to successfully implant false memories of committing a crime -- involving either assault or assault with a weapon that resulted in police contact.
Study author Dr Julia Shaw (UCL Psychology & Language Sciences) said: "Everyone thinks that they couldn't be tricked into believing they have done something they never did, and that if someone were telling them about a false memory, they would be able to spot it. But we found that actually, people tend to be quite susceptible to having false memories, and they sound just like real memories."
For the previous study, published in 2015, Dr Shaw and a colleague invited young adults into a study about emotional memories, and also spoke with a member of their family to learn about events from the participants' early adolescence, in as much detail as possible.
The researchers spoke to the participants about their past, and used leading questions and suggestive tactics, as well as visualisation techniques to convince the participants that they were helping them recover a forgotten memory -- while in fact they were implanting a false memory that the participant had committed a crime when they were young, such as theft or assault.
"We were essentially doing exactly 'what not to do' when conducting a police interview," explained Dr Shaw.
The 2015 study reported that the majority of participants developed a false memory of committing a crime, and the participants consistently reported that the false memories felt incredibly real.
The current research involves two studies that used videos from the 2015 study, of the study participants recounting their false memories of a crime, which they believed to be real. The new participants watched those videos and were asked if the person was describing an event that actually happened or not.
Participants were only 53% accurate (no better than chance) at identifying false memories of committing a crime. These results were replicated in the second study. Even when participants were explicitly told that one of the memories they watched was false, their judgment was still no better than tossing a coin.
In addition to incorrectly believing false memories to be true, participants were just as likely to watch someone recount a genuine memory, and then misidentify it as false, once the research team told them that some of the videos would feature false memories. In other words, many true memories looked like false memories.
"Legal professionals and police officers need to realise how easy it is to manipulate someone's memories. Judges in particular should never assume that they can tell when someone has a false memory, and should consider the entire process to see if there was any risk of contamination of a defendant or witness' memories," Dr Shaw said.
Read more at Science Daily
The findings, published in Frontiers in Psychology, build on a previous study that was the first to successfully implant false memories of committing a crime -- involving either assault or assault with a weapon that resulted in police contact.
Study author Dr Julia Shaw (UCL Psychology & Language Sciences) said: "Everyone thinks that they couldn't be tricked into believing they have done something they never did, and that if someone were telling them about a false memory, they would be able to spot it. But we found that actually, people tend to be quite susceptible to having false memories, and they sound just like real memories."
For the previous study, published in 2015, Dr Shaw and a colleague invited young adults into a study about emotional memories, and also spoke with a member of their family to learn about events from the participants' early adolescence, in as much detail as possible.
The researchers spoke to the participants about their past, and used leading questions and suggestive tactics, as well as visualisation techniques to convince the participants that they were helping them recover a forgotten memory -- while in fact they were implanting a false memory that the participant had committed a crime when they were young, such as theft or assault.
"We were essentially doing exactly 'what not to do' when conducting a police interview," explained Dr Shaw.
The 2015 study reported that the majority of participants developed a false memory of committing a crime, and the participants consistently reported that the false memories felt incredibly real.
The current research involves two studies that used videos from the 2015 study, of the study participants recounting their false memories of a crime, which they believed to be real. The new participants watched those videos and were asked if the person was describing an event that actually happened or not.
Participants were only 53% accurate (no better than chance) at identifying false memories of committing a crime. These results were replicated in the second study. Even when participants were explicitly told that one of the memories they watched was false, their judgment was still no better than tossing a coin.
In addition to incorrectly believing false memories to be true, participants were just as likely to watch someone recount a genuine memory, and then misidentify it as false, once the research team told them that some of the videos would feature false memories. In other words, many true memories looked like false memories.
"Legal professionals and police officers need to realise how easy it is to manipulate someone's memories. Judges in particular should never assume that they can tell when someone has a false memory, and should consider the entire process to see if there was any risk of contamination of a defendant or witness' memories," Dr Shaw said.
Read more at Science Daily
First study on the health conditions of adults one month into COVID-19 lockdown
A new study provides some of the earliest pieces of evidence that the COVID-19 outbreak affected people mentally as well as physically.
The preliminary results reveal adults in locations more affected by COVID-19 had distress, and lower physical and mental health, and life satisfaction.
Researchers from the University of Adelaide, Tongji University and University of Sydney surveyed 369 adults living in 64 cities in China after they had lived under one-month of confinement measures in February this year.
Led by Dr Stephen Zhang from the University of Adelaide, the study identifies adults with existing health conditions and those who stopped working as most at risk of worse mental and physical health.
"As many parts of the world are only just beginning to go into lockdown, we examined the impact of the one-month long lockdown on people's health, distress and life satisfaction," said Dr Zhang.
"The study offers somewhat of a 'crystal ball' into the mental health of Australian residents once they have been in the lockdown for one month."
More than a quarter of the participants worked at the office during the lockdown period while 38 percent worked from home and 25 percent stopped work due to the outbreak.
Published in Psychiatry Research, the study suggests adults living in locations more affected by COVID-19 reported negative life satisfaction only among adults with chronic medical issues but not for those without existing health issues.
Co-author on the study, Professor Andreas Rauch from the University of Sydney said; "We weren't surprised that adults who stopped working reported worse mental and physical health conditions as well as distress. Work can provide people with a sense of purpose and routine, which is particularly important during this global pandemic."
Study participants who exercised for more than 2.5 hours per day reported worse life satisfaction in more affected locations while those who exercised for half an hour or less during the lockdown reported positive life satisfaction.
"We were really surprised by the findings around exercising hours because it appears to be counter-intuitive," said lead author Dr Zhang.
Read more at Science Daily
The preliminary results reveal adults in locations more affected by COVID-19 had distress, and lower physical and mental health, and life satisfaction.
Researchers from the University of Adelaide, Tongji University and University of Sydney surveyed 369 adults living in 64 cities in China after they had lived under one-month of confinement measures in February this year.
Led by Dr Stephen Zhang from the University of Adelaide, the study identifies adults with existing health conditions and those who stopped working as most at risk of worse mental and physical health.
"As many parts of the world are only just beginning to go into lockdown, we examined the impact of the one-month long lockdown on people's health, distress and life satisfaction," said Dr Zhang.
"The study offers somewhat of a 'crystal ball' into the mental health of Australian residents once they have been in the lockdown for one month."
More than a quarter of the participants worked at the office during the lockdown period while 38 percent worked from home and 25 percent stopped work due to the outbreak.
Published in Psychiatry Research, the study suggests adults living in locations more affected by COVID-19 reported negative life satisfaction only among adults with chronic medical issues but not for those without existing health issues.
Co-author on the study, Professor Andreas Rauch from the University of Sydney said; "We weren't surprised that adults who stopped working reported worse mental and physical health conditions as well as distress. Work can provide people with a sense of purpose and routine, which is particularly important during this global pandemic."
Study participants who exercised for more than 2.5 hours per day reported worse life satisfaction in more affected locations while those who exercised for half an hour or less during the lockdown reported positive life satisfaction.
"We were really surprised by the findings around exercising hours because it appears to be counter-intuitive," said lead author Dr Zhang.
Read more at Science Daily
'Fake news' increases consumer demands for corporate action
New research finds that "fake news" inspires consumers to demand corrective action from companies -- even if the company is a victim of the fake news story. The study also supports the idea that most people feel they are better at detecting fake news than other people are -- and found that fake news increases calls for improved digital media literacy.
"The idea that I am less influenced by fake news than you are is an example of something called the third-person effect," says Yang Cheng, first author of the study and an assistant professor of communication at North Carolina State University.
"The third-person effect predicts that people tend to perceive that mass media messages have a greater effect on others than on themselves, and we found that this effect is pronounced among consumers who use social media. We also found that the third-person effect plays a significant role in how people respond to fake news online."
For this study, the researchers enlisted 661 study participants from across the United States who identified as being Coca-Cola consumers. The researchers first gave the participants an example of a fake news story that circulated in Facebook in 2016, which (falsely) claimed that Coca-Cola had recalled bottles of its Dasani-brand water due to the presence of aquatic parasites. The researchers then asked study participants a range of questions designed to ascertain how the participants felt about fake news and what they felt should be done to address it.
"The strongest finding was that consumers expect corporations to take responsibility for combating fake news, even if the company in question was a victim of the fake news story," Cheng says. "This is news that public relations professionals can use. It highlights the need for communication professionals to step up and take an active role in responding to fake news items. That could mean collaborating with reporters to provide them with accurate information, or making correct information directly available to the public, or both. But it suggests that simply being quiet and waiting for the crisis to blow over may be unwise.
"Anyone can spread fake news on social media, and the expectation from consumers is that affected companies should play an active role in addressing it."
The study also found that consumers wanted more to be done to improve media literacy, and that media users should be taught how to evaluate media critically.
The researchers also found that the most powerful factor in triggering these responses from consumers appeared to be the third-party effect. In other words, the people who were most confident in their ability to detect fake news felt most strongly that other people would be influenced by fake news. And highly-confident consumers were the most likely to call for corrective action from corporations and improved media literacy efforts.
Read more at Science Daily
"The idea that I am less influenced by fake news than you are is an example of something called the third-person effect," says Yang Cheng, first author of the study and an assistant professor of communication at North Carolina State University.
"The third-person effect predicts that people tend to perceive that mass media messages have a greater effect on others than on themselves, and we found that this effect is pronounced among consumers who use social media. We also found that the third-person effect plays a significant role in how people respond to fake news online."
For this study, the researchers enlisted 661 study participants from across the United States who identified as being Coca-Cola consumers. The researchers first gave the participants an example of a fake news story that circulated in Facebook in 2016, which (falsely) claimed that Coca-Cola had recalled bottles of its Dasani-brand water due to the presence of aquatic parasites. The researchers then asked study participants a range of questions designed to ascertain how the participants felt about fake news and what they felt should be done to address it.
"The strongest finding was that consumers expect corporations to take responsibility for combating fake news, even if the company in question was a victim of the fake news story," Cheng says. "This is news that public relations professionals can use. It highlights the need for communication professionals to step up and take an active role in responding to fake news items. That could mean collaborating with reporters to provide them with accurate information, or making correct information directly available to the public, or both. But it suggests that simply being quiet and waiting for the crisis to blow over may be unwise.
"Anyone can spread fake news on social media, and the expectation from consumers is that affected companies should play an active role in addressing it."
The study also found that consumers wanted more to be done to improve media literacy, and that media users should be taught how to evaluate media critically.
The researchers also found that the most powerful factor in triggering these responses from consumers appeared to be the third-party effect. In other words, the people who were most confident in their ability to detect fake news felt most strongly that other people would be influenced by fake news. And highly-confident consumers were the most likely to call for corrective action from corporations and improved media literacy efforts.
Read more at Science Daily
Revolutionary new method for dating pottery sheds new light on prehistoric past
A team at the University of Bristol has developed a new method of dating pottery which is allowing archaeologists to date prehistoric finds from across the world with remarkable accuracy.
The exciting new method, reported in detail today in the journal Nature, is now being used to date pottery from a range of key sites up to 8,000 years old in Britain, Europe and Africa.
Pottery and the dating game
Archaeological pottery has been used to date archaeological sites for more than a century, and from the Roman period onwards can offer quite precise dating. But further back in time, for example at the prehistoric sites of the earliest Neolithic farmers, accurate dating becomes more difficult because the kinds of pottery are often less distinctive and there are no coins or historical records to give context.
This is where radiocarbon dating, also known as 14C-dating, comes to the rescue. Until now, archaeologists had to radiocarbon date bones or other organic materials buried with the pots to understand their age.
But the best and most accurate way to date pots would be to date them directly, which the University of Bristol team has now introduced by dating the fatty acids left behind from food preparation.
Professor Richard Evershed from the University of Bristol's School of Chemistry led the team. He said: "Being able to directly date archaeological pots is one of the "Holy Grails" of archaeology. This new method is based on an idea I had going back more than 20 years and it is now allowing the community to better understand key archaeological sites across the world.
"We made several earlier attempts to get the method right, but it wasn't until we established our own radiocarbon facility in Bristol that we cracked it. There's a particular beauty in the way these new technologies came together to make this important work possible and now archaeological questions that are currently very difficult to resolve could be answered."
How the method works
The trick was isolating individual fat compounds from food residues, perhaps left by cooking meat or milk, protected within the pores of prehistoric cooking pots. The team brought together the latest high resolution nuclear magnetic resonance spectroscopy and mass spectrometry technologies to design a new way of isolating the fatty acids and checking they were pure enough for accurate dating.
The team then had to show that the new approach gave dates as accurate as those given by materials commonly dated in archaeology, such as bones, seeds and wood. To do this the team looked at fat extracts from ancient pottery at a range of key sites in Britain, Europe and Africa with already precise dating which were up to 8,000 years old.
From the famous Sweet Track site in Somerset and several sites in the Alsace region of France, to the World Heritage site of Çatalhöyük in central Turkey and the famous rock shelter site of Takarkori in Saharan Africa, the new method was proven to date sites incredibly accurately, even to within a human life span.
Professor Alex Bayliss, Head of Scientific Dating at Historic England, who undertook the statistical analyses, added: "It is very difficult to overstate the importance of this advance to the archaeological community. Pottery typology is the most widely used dating technique in the discipline, and so the opportunity to place different kinds of pottery in calendar time much more securely will be of great practical significance."
Using the pottery calendar to better understand London's pre-history
In London, England, the new dating method has been used on a remarkable collection of pottery found in Shoreditch, thought to be the most significant group of Early Neolithic pottery ever found in the capital. The extraordinary trove, comprising 436 fragments from at least 24 separate vessels weighing nearly 6.5 kilos in total, was discovered by archaeologists from MOLA (Museum of London Archaeology).
The site appeared to date from the time when the first farmers came to Britain but accurately dating it was difficult until the Bristol team, using their new dating method on traces of milk fats extracted from the pots, showed the pottery was 5,500 years old. The team were able to date the pottery collection to a window of just 138 years, to around 3600BC.
The results indicate that around 5600 years ago the area around what is now Shoreditch High Street was used by established farmers who ate cow, sheep or goat dairy products as a central part of their diet. These people were likely to have been linked to the migrant groups who were the first to introduce farming to Britain from Continental Europe around 4000 BC -- just 400 years earlier.
Jon Cotton, a consultant prehistorian working for MOLA, said: "This remarkable collection helps to fill a critical gap in London's prehistory. Archaeological evidence for the period after farming arrived in Britain rarely survives in the capital, let alone still in-situ. This is the strongest evidence yet that people in the area later occupied by the city and its immediate hinterland were living a less mobile, farming-based lifestyle during the Early Neolithic period."
Read more at Science Daily
The exciting new method, reported in detail today in the journal Nature, is now being used to date pottery from a range of key sites up to 8,000 years old in Britain, Europe and Africa.
Pottery and the dating game
Archaeological pottery has been used to date archaeological sites for more than a century, and from the Roman period onwards can offer quite precise dating. But further back in time, for example at the prehistoric sites of the earliest Neolithic farmers, accurate dating becomes more difficult because the kinds of pottery are often less distinctive and there are no coins or historical records to give context.
This is where radiocarbon dating, also known as 14C-dating, comes to the rescue. Until now, archaeologists had to radiocarbon date bones or other organic materials buried with the pots to understand their age.
But the best and most accurate way to date pots would be to date them directly, which the University of Bristol team has now introduced by dating the fatty acids left behind from food preparation.
Professor Richard Evershed from the University of Bristol's School of Chemistry led the team. He said: "Being able to directly date archaeological pots is one of the "Holy Grails" of archaeology. This new method is based on an idea I had going back more than 20 years and it is now allowing the community to better understand key archaeological sites across the world.
"We made several earlier attempts to get the method right, but it wasn't until we established our own radiocarbon facility in Bristol that we cracked it. There's a particular beauty in the way these new technologies came together to make this important work possible and now archaeological questions that are currently very difficult to resolve could be answered."
How the method works
The trick was isolating individual fat compounds from food residues, perhaps left by cooking meat or milk, protected within the pores of prehistoric cooking pots. The team brought together the latest high resolution nuclear magnetic resonance spectroscopy and mass spectrometry technologies to design a new way of isolating the fatty acids and checking they were pure enough for accurate dating.
The team then had to show that the new approach gave dates as accurate as those given by materials commonly dated in archaeology, such as bones, seeds and wood. To do this the team looked at fat extracts from ancient pottery at a range of key sites in Britain, Europe and Africa with already precise dating which were up to 8,000 years old.
From the famous Sweet Track site in Somerset and several sites in the Alsace region of France, to the World Heritage site of Çatalhöyük in central Turkey and the famous rock shelter site of Takarkori in Saharan Africa, the new method was proven to date sites incredibly accurately, even to within a human life span.
Professor Alex Bayliss, Head of Scientific Dating at Historic England, who undertook the statistical analyses, added: "It is very difficult to overstate the importance of this advance to the archaeological community. Pottery typology is the most widely used dating technique in the discipline, and so the opportunity to place different kinds of pottery in calendar time much more securely will be of great practical significance."
Using the pottery calendar to better understand London's pre-history
In London, England, the new dating method has been used on a remarkable collection of pottery found in Shoreditch, thought to be the most significant group of Early Neolithic pottery ever found in the capital. The extraordinary trove, comprising 436 fragments from at least 24 separate vessels weighing nearly 6.5 kilos in total, was discovered by archaeologists from MOLA (Museum of London Archaeology).
The site appeared to date from the time when the first farmers came to Britain but accurately dating it was difficult until the Bristol team, using their new dating method on traces of milk fats extracted from the pots, showed the pottery was 5,500 years old. The team were able to date the pottery collection to a window of just 138 years, to around 3600BC.
The results indicate that around 5600 years ago the area around what is now Shoreditch High Street was used by established farmers who ate cow, sheep or goat dairy products as a central part of their diet. These people were likely to have been linked to the migrant groups who were the first to introduce farming to Britain from Continental Europe around 4000 BC -- just 400 years earlier.
Jon Cotton, a consultant prehistorian working for MOLA, said: "This remarkable collection helps to fill a critical gap in London's prehistory. Archaeological evidence for the period after farming arrived in Britain rarely survives in the capital, let alone still in-situ. This is the strongest evidence yet that people in the area later occupied by the city and its immediate hinterland were living a less mobile, farming-based lifestyle during the Early Neolithic period."
Read more at Science Daily
Apr 7, 2020
Climate change triggers Great Barrier Reef bleaching
Australia's iconic Great Barrier Reef is experiencing its third coral bleaching event in just five years. The 2020 bleaching is severe, and more widespread than earlier events.
"We surveyed 1,036 reefs from the air during the last two weeks in March, to measure the extent and severity of coral bleaching throughout the Barrier Reef region," said Professor Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University.
"For the first time, severe bleaching has struck all three regions of the Great Barrier Reef -- the northern, central and now large parts of the southern sectors," Prof Hughes said.
Coral bleaching at regional scales is caused by thermal stress due to spikes in sea temperatures during unusually hot summers. The first recorded mass bleaching event along the Great Barrier Reef occurred in 1998, then the hottest year on record. Four more mass bleaching events have occurred since -- as more temperature records were broken -- in 2002, 2016, 2017, and now in 2020.
This year, February had the highest monthly temperatures ever recorded on the Great Barrier Reef since the Bureau of Meteorology's sea surface temperature records began in 1900.
"Bleaching isn't necessarily fatal, and it affects some species more than others," said Professor Morgan Pratchett, also from Coral CoE at JCU, who led underwater surveys to assess the bleaching.
"A pale or lightly bleached coral typically regains its colour within a few weeks or months and survives," he said.
However, many corals die when bleaching is severe. In 2016, more than half of the shallow-water corals died on the northern region of the Great Barrier Reef.
"We will go back underwater later this year to assess the losses of corals from this most recent event," Prof Pratchett said.
"The north was the worst affected region in 2016, followed by the central region in 2017. In 2020, the cumulative footprint of bleaching has expanded further to include the south."
The distinctive footprint of each bleaching event closely matches the location of hotter and cooler conditions in different years.
"As summers grow hotter and hotter, we no longer need an El Niño event to trigger mass bleaching at the scale of the Great Barrier Reef," Prof Hughes said.
"Of the five events we have seen so far, only 1998 and 2016 occurred during El Niño conditions."
The gap between recurrent bleaching events is shrinking, hindering a full recovery.
"We have already seen the first example of back-to-back bleaching -- in the consecutive summers of 2016 and 2017," Prof Hughes said.
Read more at Science Daily
"We surveyed 1,036 reefs from the air during the last two weeks in March, to measure the extent and severity of coral bleaching throughout the Barrier Reef region," said Professor Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University.
"For the first time, severe bleaching has struck all three regions of the Great Barrier Reef -- the northern, central and now large parts of the southern sectors," Prof Hughes said.
Coral bleaching at regional scales is caused by thermal stress due to spikes in sea temperatures during unusually hot summers. The first recorded mass bleaching event along the Great Barrier Reef occurred in 1998, then the hottest year on record. Four more mass bleaching events have occurred since -- as more temperature records were broken -- in 2002, 2016, 2017, and now in 2020.
This year, February had the highest monthly temperatures ever recorded on the Great Barrier Reef since the Bureau of Meteorology's sea surface temperature records began in 1900.
"Bleaching isn't necessarily fatal, and it affects some species more than others," said Professor Morgan Pratchett, also from Coral CoE at JCU, who led underwater surveys to assess the bleaching.
"A pale or lightly bleached coral typically regains its colour within a few weeks or months and survives," he said.
However, many corals die when bleaching is severe. In 2016, more than half of the shallow-water corals died on the northern region of the Great Barrier Reef.
"We will go back underwater later this year to assess the losses of corals from this most recent event," Prof Pratchett said.
"The north was the worst affected region in 2016, followed by the central region in 2017. In 2020, the cumulative footprint of bleaching has expanded further to include the south."
The distinctive footprint of each bleaching event closely matches the location of hotter and cooler conditions in different years.
"As summers grow hotter and hotter, we no longer need an El Niño event to trigger mass bleaching at the scale of the Great Barrier Reef," Prof Hughes said.
"Of the five events we have seen so far, only 1998 and 2016 occurred during El Niño conditions."
The gap between recurrent bleaching events is shrinking, hindering a full recovery.
"We have already seen the first example of back-to-back bleaching -- in the consecutive summers of 2016 and 2017," Prof Hughes said.
Read more at Science Daily
First-ever photo proof of powerful jet emerging from colliding galaxies
A team of Clemson University College of Science researchers, in collaboration with international colleagues, has reported the first definitive detection of a relativistic jet emerging from two colliding galaxies -- in essence, the first photographic proof that merging galaxies can produce jets of charged particles that travel at nearly the speed of light.
Furthermore, scientists had previously discovered that these jets could be found in elliptical-shaped galaxies, which can be formed in the merging of two spiral galaxies. Now, they have an image showing the formation of a jet from two younger, spiral-shaped galaxies.
"For the first time, we have found two spiral- or disk-shaped galaxies on path for a collision that have produced a nascent, baby jet that has just started its life at the center of one of the galaxies," said Vaidehi Paliya, a former Clemson post-doctoral researcher and lead author of the findings reported in the Astrophysical Journal on April 7, 2020.
The paper is titled "TXS 2116-077: A gamma-ray emitting relativistic jet hosted in a galaxy merger." In addition to Paliya, who is now at the Deutsches Elektronen Synchrotron (DESY) in Germany, the other Clemson authors include associate professor Marco Ajello, professor Dieter Hartmann, and adjunct professor Stefano Marchesi of the department of physics and astronomy.
The fact that the jet is so young enabled the researchers to clearly see its host.
According to Ajello, others have already imaged galactic collisions many times. But he and his colleagues are the first to capture two galaxies merging where there is a fully formed jet pointing at us -- albeit, a very young one, and thus not yet bright enough to blind us.
"Typically, a jet emits light that is so powerful we can't see the galaxy behind it," Marchesi said. "It's like trying to look at an object and someone points a bright flashlight into your eyes. All you can see is the flashlight. This jet is less powerful, so we can actually see the galaxy where it is born."
Jets are the most powerful astrophysical phenomena in the universe. They can emit more energy into the universe in one second than our sun will produce in its entire lifetime. That energy is in the form of radiation, such as intense radio waves, X-rays, and gamma-rays.
"Jets are the best accelerators in the universe -- far better than the super colliders we have on Earth," said Hartmann, referring to accelerators used in high-energy physics studies.
Jets were thought to be born from older, elliptical-shaped galaxies with an active galactic nucleus (AGN), which is a super-massive black hole that resides at its center. As a point of reference, scientists believe all galaxies have centrally located super-massive black holes, but not all of them are AGNs. For example, our Milky Way's massive black hole is dormant.
Scientists theorize that the AGNs grow larger by gravitationally drawing in gas and dust through a process called accretion. But not all of this matter gets accreted into the black hole. Some of the particles become accelerated and are spewed outward in narrow beams in the form of jets.
"It's hard to dislodge gas from the galaxy and have it reach its center," Ajello explained. "You need something to shake the galaxy a little bit to make the gas get there. The merging or colliding of galaxies is the easiest way to move the gas, and if enough gas moves, then the super-massive black hole will become extremely bright and could potentially develop a jet."
Ajello believes that the team's image captured the two galaxies, a Seyfert 1 galaxy known as TXS 2116-077 and another galaxy of similar mass, as they were colliding for the second time because of the amount of gas seen in the image.
"Eventually, all the gas will be expelled into space, and without gas, a galaxy cannot form stars anymore," Ajello said. "Without gas, the black hole will switch off and the galaxy will lay dormant."
Billions of years from now, our own Milky Way will merge with the nearby Andromeda galaxy.
"Scientists have carried out detailed numerical simulations and predicted that this event may ultimately lead to the formation of one giant elliptical galaxy," said Paliya. "Depending on the physical conditions, it may host a relativistic jet, but that's in the distant future."
Read more at Science Daily
Furthermore, scientists had previously discovered that these jets could be found in elliptical-shaped galaxies, which can be formed in the merging of two spiral galaxies. Now, they have an image showing the formation of a jet from two younger, spiral-shaped galaxies.
"For the first time, we have found two spiral- or disk-shaped galaxies on path for a collision that have produced a nascent, baby jet that has just started its life at the center of one of the galaxies," said Vaidehi Paliya, a former Clemson post-doctoral researcher and lead author of the findings reported in the Astrophysical Journal on April 7, 2020.
The paper is titled "TXS 2116-077: A gamma-ray emitting relativistic jet hosted in a galaxy merger." In addition to Paliya, who is now at the Deutsches Elektronen Synchrotron (DESY) in Germany, the other Clemson authors include associate professor Marco Ajello, professor Dieter Hartmann, and adjunct professor Stefano Marchesi of the department of physics and astronomy.
The fact that the jet is so young enabled the researchers to clearly see its host.
According to Ajello, others have already imaged galactic collisions many times. But he and his colleagues are the first to capture two galaxies merging where there is a fully formed jet pointing at us -- albeit, a very young one, and thus not yet bright enough to blind us.
"Typically, a jet emits light that is so powerful we can't see the galaxy behind it," Marchesi said. "It's like trying to look at an object and someone points a bright flashlight into your eyes. All you can see is the flashlight. This jet is less powerful, so we can actually see the galaxy where it is born."
Jets are the most powerful astrophysical phenomena in the universe. They can emit more energy into the universe in one second than our sun will produce in its entire lifetime. That energy is in the form of radiation, such as intense radio waves, X-rays, and gamma-rays.
"Jets are the best accelerators in the universe -- far better than the super colliders we have on Earth," said Hartmann, referring to accelerators used in high-energy physics studies.
Jets were thought to be born from older, elliptical-shaped galaxies with an active galactic nucleus (AGN), which is a super-massive black hole that resides at its center. As a point of reference, scientists believe all galaxies have centrally located super-massive black holes, but not all of them are AGNs. For example, our Milky Way's massive black hole is dormant.
Scientists theorize that the AGNs grow larger by gravitationally drawing in gas and dust through a process called accretion. But not all of this matter gets accreted into the black hole. Some of the particles become accelerated and are spewed outward in narrow beams in the form of jets.
"It's hard to dislodge gas from the galaxy and have it reach its center," Ajello explained. "You need something to shake the galaxy a little bit to make the gas get there. The merging or colliding of galaxies is the easiest way to move the gas, and if enough gas moves, then the super-massive black hole will become extremely bright and could potentially develop a jet."
Ajello believes that the team's image captured the two galaxies, a Seyfert 1 galaxy known as TXS 2116-077 and another galaxy of similar mass, as they were colliding for the second time because of the amount of gas seen in the image.
"Eventually, all the gas will be expelled into space, and without gas, a galaxy cannot form stars anymore," Ajello said. "Without gas, the black hole will switch off and the galaxy will lay dormant."
Billions of years from now, our own Milky Way will merge with the nearby Andromeda galaxy.
"Scientists have carried out detailed numerical simulations and predicted that this event may ultimately lead to the formation of one giant elliptical galaxy," said Paliya. "Depending on the physical conditions, it may host a relativistic jet, but that's in the distant future."
Read more at Science Daily
What type of cells does the novel coronavirus attack?
Scientists from the Berlin Institute of Health (BIH), Charité -- Universitätsmedizin Berlin and the Thorax Clinic at Heidelberg University Hospital, whose collaboration is taking place under the auspices of the German Center for Lung Research (DZL), have examined samples from non-virus infected patients to determine which cells of the lungs and bronchi are targets for novel coronavirus (SARS-CoV-2) infection. They discovered that the receptor for this coronavirus is abundantly expressed in certain progenitor cells. These cells normally develop into respiratory tract cells lined with hair-like projections called cilia that sweep mucus and bacteria out of the lungs. The scientists have now published their findings in The EMBO Journal.
Professor Roland Eils and his colleagues from the Thorax Clinic in Heidelberg initially intended to study why lung cancer sometimes occurs in people who have never smoked. They began by analyzing samples of twelve lung cancer patients. These samples were obtained from the Heidelberg Lung Biobank and came from both the cancerous part of the lungs and the surrounding healthy lung tissue. They also studied cells from the airways of healthy patients, which had been collected in a minimally invasive manner during a bronchoscopy examination performed to rule out lung cancer. The rapidly spreading coronavirus prompted the researchers to take another look at these existing but so far unpublished data. "I was convinced that the data we gathered from these non-coronavirus infected patients would provide important information for understanding the viral infection," says Roland Eils, founding director of the BIH Digital Health Center.
Infection requires receptors and cofactors
"We wanted to find out which specific cells the coronavirus attacks," explains Professor Christian Conrad, who also works at the BIH Digital Health Center. The scientists knew, from studies by BIH Professor Christian Drosten, director of the Institute of Virology at Campus Charité; Mitte, and by others, that the virus's spike protein attaches to an ACE2 receptor on the cell surface. In addition, the virus needs one or more cofactors for it to be able to penetrate cells. But which cells are endowed with such receptors and cofactors? Which cells in which part of the respiratory system are particularly susceptible to SARS-CoV-2 infection? Eils and his colleagues at the BIH and Charité; now used single-cell sequencing technology to examine the cells in the samples from Heidelberg.
60,000 single cells were sequenced
"We then analyzed a total of nearly 60,000 cells to determine whether they activated the gene for the receptor and potential cofactors, thus in principle allowing them to be infected by the coronavirus," reports Soeren Lukassen, one of the lead authors of the study now being published in The EMBO Journal. "We only found the gene transcripts for ACE2 and for the cofactor TMPRSS2 in very few cells, and only in very small numbers." Lukassen and his four co-lead authors Robert Lorenz Chua, Timo Trefzer, Nicolas C. Kahn and Marc A. Schneider discovered that certain progenitor cells in the bronchi are mainly responsible for producing the coronavirus receptors. These progenitor cells normally develop into respiratory tract cells lined with hair-like projections called cilia that sweep mucus and bacteria out of the lungs. "Armed with the knowledge of which cells are attacked, we can now develop targeted therapies," explains Professor Michael Kreuter from the Thorax Clinic at Heidelberg University Hospital.
Why does the infection progress so differently?
An interesting additional finding of the study was that the ACE2 receptor density on the cells increased with age and was generally higher in men than in women. "This was only a trend, but it could explain why SARS-CoV-2 has infected more men than women," Eils says. However, he points out, "our sample sizes are still much too small to make conclusive statements, so we need to repeat the study in larger patient cohorts."
"These results show us that the virus acts in a highly selective manner, and that it is dependent on certain human cells in order to spread and replicate," Eils explains. "The better we understand the interaction between the virus and its host, the better we will be able to develop effective counterstrategies." He and the other researchers will next study COVID 19 patients to ascertain whether the virus has actually infected these cells. "We want to understand why the infection takes a benign course in some patients, while causing severe disease in others," Eils says. "So we will also look closely at the immune cells in the infected tissue."
Tech firms provide expertise
Based on a high-performance technology solution designed by Intel, Dell developed a hardware and system architecture that reduced the processing time needed to sequence the 60,000 single cells. Hannes Schwaderer, country manager of Intel Germany, explains: "There are many things we don't know about the coronavirus. This research project and the next steps require enormous computing resources. That's exactly where our expertise can help."
Read more at Science Dialy
Professor Roland Eils and his colleagues from the Thorax Clinic in Heidelberg initially intended to study why lung cancer sometimes occurs in people who have never smoked. They began by analyzing samples of twelve lung cancer patients. These samples were obtained from the Heidelberg Lung Biobank and came from both the cancerous part of the lungs and the surrounding healthy lung tissue. They also studied cells from the airways of healthy patients, which had been collected in a minimally invasive manner during a bronchoscopy examination performed to rule out lung cancer. The rapidly spreading coronavirus prompted the researchers to take another look at these existing but so far unpublished data. "I was convinced that the data we gathered from these non-coronavirus infected patients would provide important information for understanding the viral infection," says Roland Eils, founding director of the BIH Digital Health Center.
Infection requires receptors and cofactors
"We wanted to find out which specific cells the coronavirus attacks," explains Professor Christian Conrad, who also works at the BIH Digital Health Center. The scientists knew, from studies by BIH Professor Christian Drosten, director of the Institute of Virology at Campus Charité; Mitte, and by others, that the virus's spike protein attaches to an ACE2 receptor on the cell surface. In addition, the virus needs one or more cofactors for it to be able to penetrate cells. But which cells are endowed with such receptors and cofactors? Which cells in which part of the respiratory system are particularly susceptible to SARS-CoV-2 infection? Eils and his colleagues at the BIH and Charité; now used single-cell sequencing technology to examine the cells in the samples from Heidelberg.
60,000 single cells were sequenced
"We then analyzed a total of nearly 60,000 cells to determine whether they activated the gene for the receptor and potential cofactors, thus in principle allowing them to be infected by the coronavirus," reports Soeren Lukassen, one of the lead authors of the study now being published in The EMBO Journal. "We only found the gene transcripts for ACE2 and for the cofactor TMPRSS2 in very few cells, and only in very small numbers." Lukassen and his four co-lead authors Robert Lorenz Chua, Timo Trefzer, Nicolas C. Kahn and Marc A. Schneider discovered that certain progenitor cells in the bronchi are mainly responsible for producing the coronavirus receptors. These progenitor cells normally develop into respiratory tract cells lined with hair-like projections called cilia that sweep mucus and bacteria out of the lungs. "Armed with the knowledge of which cells are attacked, we can now develop targeted therapies," explains Professor Michael Kreuter from the Thorax Clinic at Heidelberg University Hospital.
Why does the infection progress so differently?
An interesting additional finding of the study was that the ACE2 receptor density on the cells increased with age and was generally higher in men than in women. "This was only a trend, but it could explain why SARS-CoV-2 has infected more men than women," Eils says. However, he points out, "our sample sizes are still much too small to make conclusive statements, so we need to repeat the study in larger patient cohorts."
"These results show us that the virus acts in a highly selective manner, and that it is dependent on certain human cells in order to spread and replicate," Eils explains. "The better we understand the interaction between the virus and its host, the better we will be able to develop effective counterstrategies." He and the other researchers will next study COVID 19 patients to ascertain whether the virus has actually infected these cells. "We want to understand why the infection takes a benign course in some patients, while causing severe disease in others," Eils says. "So we will also look closely at the immune cells in the infected tissue."
Tech firms provide expertise
Based on a high-performance technology solution designed by Intel, Dell developed a hardware and system architecture that reduced the processing time needed to sequence the 60,000 single cells. Hannes Schwaderer, country manager of Intel Germany, explains: "There are many things we don't know about the coronavirus. This research project and the next steps require enormous computing resources. That's exactly where our expertise can help."
Read more at Science Dialy
The Milky Way's satellites help reveal link between dark matter halos and galaxy formation
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| Spiral galaxy illustration |
Astrophysicists believe that dark matter is responsible for much of that structure, and now researchers at the Department of Energy's SLAC National Accelerator Laboratory and the Dark Energy Survey have drawn on observations of faint galaxies around the Milky Way to place tighter constraints on the connection between the size and structure of galaxies and the dark matter halos that surround them. At the same time, they have found more evidence for the existence of LMC satellite galaxies and made a new prediction: If the scientists' models are correct, the Milky Way should have an additional 150 or more very faint satellite galaxies awaiting discovery by next-generation projects such as the Vera C. Rubin Observatory's Legacy Survey of Space and Time.
The new study, forthcoming in the Astrophysical Journal and available as a preprint here, is part of a larger effort to understand how dark matter works on scales smaller than our galaxy, said Ethan Nadler, the study's first author and a graduate student at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) and Stanford University.
"We know some things about dark matter very well -- how much dark matter is there, how does it cluster -- but all of these statements are qualified by saying, yes, that is how it behaves on scales larger than the size of our local group of galaxies," Nadler said. "And then the question is, does that work on the smallest scales we can measure?"
Shining galaxies' light on dark matter
Astronomers have long known the Milky Way has satellite galaxies, including the Large Magellanic Cloud, which can be seen by the naked eye from the Southern Hemisphere, but the number was thought to be around just a dozen or so until around the year 2000. Since then, the number of observed satellite galaxies has risen dramatically. Thanks to the Sloan Digital Sky Survey and more recent discoveries by projects including the Dark Energy Survey (DES), the number of known satellite galaxies has climbed to about 60.
Such discoveries are always exciting, but what's perhaps most exciting is what the data could tell us about the cosmos. "For the first time, we can look for these satellite galaxies across about three-quarters of the sky, and that's really important to several different ways of learning about dark matter and galaxy formation," said Risa Wechsler, director of KIPAC. Last year, for example, Wechsler, Nadler and colleagues used data on satellite galaxies in conjunction with computer simulations to place much tighter limits on dark matter's interactions with ordinary matter.
Now, Wechsler, Nadler and the DES team are using data from a comprehensive search over most of the sky to ask different questions, including how much dark matter it takes to form a galaxy, how many satellite galaxies we should expect to find around the Milky Way and whether galaxies can bring their own satellites into orbit around our own -- a key prediction of the most popular model of dark matter.
Hints of galactic hierarchy
The answer to that last question appears to be a resounding "yes."
The possibility of detecting a hierarchy of satellite galaxies first arose some years back when DES detected more satellite galaxies in the vicinity of the Large Magellanic Cloud than they would have expected if those satellites were randomly distributed throughout the sky. Those observations are particularly interesting, Nadler said, in light of the Gaia measurements, which indicated that six of these satellite galaxies fell into the Milky Way with the LMC.
To study the LMC's satellites more thoroughly, Nadler and team analyzed computer simulations of millions of possible universes. Those simulations, originally run by Yao-Yuan Mao, a former graduate student of Wechsler's who is now at Rutgers University, model the formation of dark matter structure that permeates the Milky Way, including details such as smaller dark matter clumps within the Milky Way that are expected to host satellite galaxies. To connect dark matter to galaxy formation, the researchers used a flexible model that allows them to account for uncertainties in the current understanding of galaxy formation, including the relationship between galaxies' brightness and the mass of dark matter clumps within which they form.
An effort led by the others in the DES team, including former KIPAC students Alex Drlica-Wagner, a Wilson Fellow at Fermilab and an assistant professor of astronomy and astrophysics at the University of Chicago, and Keith Bechtol, an assistant professor of physics at the University of Wisconsin-Madison, and their collaborators produced the crucial final step: a model of which satellite galaxies are most likely to be seen by current surveys, given where they are in the sky as well as their brightness, size and distance.
Those components in hand, the team ran their model with a wide range of parameters and searched for simulations in which LMC-like objects fell into the gravitational pull of a Milky Way-like galaxy. By comparing those cases with galactic observations, they could infer a range of astrophysical parameters, including how many satellite galaxies should have tagged along with the LMC. The results, Nadler said, were consistent with Gaia observations: Six satellite galaxies should currently be detected in the vicinity of the LMC, moving with roughly the right velocities and in roughly the same places as astronomers had previously observed. The simulations also suggested that the LMC first approached the Milky Way about 2.2 billion years ago, consistent with high-precision measurements of the motion of the LMC from the Hubble Space Telescope.
Galaxies yet unseen
In addition to the LMC findings, the team also put limits on the connection between dark matter halos and galaxy structure. For example, in simulations that most closely matched the history of the Milky Way and the LMC, the smallest galaxies astronomers could currently observe should have stars with a combined mass of around a hundred suns, and about a million times as much dark matter. According to an extrapolation of the model, the faintest galaxies that could ever be observed could form in halos up to a hundred times less massive than that.
And there could be more discoveries to come: If the simulations are correct, Nadler said, there are around 100 more satellite galaxies -- more than double the number already discovered -- hovering around the Milky Way. The discovery of those galaxies would help confirm the researchers' model of the links between dark matter and galaxy formation, he said, and likely place tighter constraints on the nature of dark matter itself.
Read more at Science Daily
Apr 6, 2020
Tooth be told: Earless seals existed in ancient Australia
A fossilised seal tooth found on a Victorian beach could hold the key to uncovering the history and geography of earless seals that graced Australia's shores three million years ago.
This prehistoric specimen is only the second earless seal fossil ever discovered in Australia, and proves the country's local fur seals and sea lions were preceded by a group of sea mammals, known as monachines, now long extinct in Australia.
The study also highlights the current dangers of climate change to Earth's existing wildlife, with falling sea levels likely to have played a role in the extinction of these ancient seals.
The history of this rare specimen was published today (Friday 3 April) in the Journal of Vertebrate Paleontology by a team of scientists from Monash University's School of Biological Sciences and Department of Anatomy and Developmental Biology, and Museums Victoria, led by PhD candidate James Rule.
"This tooth, roughly three million years old, tells a story similar to what occurred in South Africa and South America in the past. Earless monachine seals used to dominate southern beaches and waters, and then suddenly disappeared, with eared seals replacing them," Mr Rule said.
"Since seal fossils are rare globally, this discovery makes a vital contribution to our understanding of this iconic group of sea mammals."
An Australian citizen scientist and amateur fossil collector discovered the tooth while strolling along the beach at Portland, western Victoria.
But it wasn't until he donated the fossil to Museums Victoria many years later that it was found to have been a tooth from an extinct group of earless seals.
The research team compared the tooth to other pinnipeds -- a group that includes earless seals, fur seals, sea lions and the walrus.
They found the tooth possessed characteristics of monachines and shed light on how these seals lived and what they ate.
"This seal lived in shallow waters close to the shore, likely hunting fish and squid. As monachines cannot use their limbs to walk on land, it would have required flat, sandy beaches when it came ashore to rest," Mr Rule said.
Researchers believe drastic changes in the Earth's climate fundamentally altered Australia's environment by eliminating the beaches used by earless seals to rest.
"These changes in the past have led to the extinction of Australia's ancient earless seals," Dr David Hocking, co-author and Research Fellow in Monash University's School of Biological Sciences, said.
"Our living fur seals and sea lions will likely face similar challenges as the Earth continues to warm, with melting polar ice leading to rising sea levels.
Read more at Science Daily
This prehistoric specimen is only the second earless seal fossil ever discovered in Australia, and proves the country's local fur seals and sea lions were preceded by a group of sea mammals, known as monachines, now long extinct in Australia.
The study also highlights the current dangers of climate change to Earth's existing wildlife, with falling sea levels likely to have played a role in the extinction of these ancient seals.
The history of this rare specimen was published today (Friday 3 April) in the Journal of Vertebrate Paleontology by a team of scientists from Monash University's School of Biological Sciences and Department of Anatomy and Developmental Biology, and Museums Victoria, led by PhD candidate James Rule.
"This tooth, roughly three million years old, tells a story similar to what occurred in South Africa and South America in the past. Earless monachine seals used to dominate southern beaches and waters, and then suddenly disappeared, with eared seals replacing them," Mr Rule said.
"Since seal fossils are rare globally, this discovery makes a vital contribution to our understanding of this iconic group of sea mammals."
An Australian citizen scientist and amateur fossil collector discovered the tooth while strolling along the beach at Portland, western Victoria.
But it wasn't until he donated the fossil to Museums Victoria many years later that it was found to have been a tooth from an extinct group of earless seals.
The research team compared the tooth to other pinnipeds -- a group that includes earless seals, fur seals, sea lions and the walrus.
They found the tooth possessed characteristics of monachines and shed light on how these seals lived and what they ate.
"This seal lived in shallow waters close to the shore, likely hunting fish and squid. As monachines cannot use their limbs to walk on land, it would have required flat, sandy beaches when it came ashore to rest," Mr Rule said.
Researchers believe drastic changes in the Earth's climate fundamentally altered Australia's environment by eliminating the beaches used by earless seals to rest.
"These changes in the past have led to the extinction of Australia's ancient earless seals," Dr David Hocking, co-author and Research Fellow in Monash University's School of Biological Sciences, said.
"Our living fur seals and sea lions will likely face similar challenges as the Earth continues to warm, with melting polar ice leading to rising sea levels.
Read more at Science Daily
Upper ocean water masses shrinking in changing climate: Less efficient CO2 sink
We're familiar with how climate change is impacting the ocean's biology, from bleaching events that cause coral die-offs to algae blooms that choke coastal marine ecosystems, but it's becoming clear that a warming planet is also impacting the physics of ocean circulation.
A team of scientists from the University of British Columbia, the Bermuda Institute of Ocean Sciences (BIOS), the French Institute for Ocean Science at the University of Brest, and the University of Southampton recently published the results of an analysis of North Atlantic Ocean water masses in the journal Nature Climate Change.
"The oceans play a vital role in buffering the Earth from climate change by absorbing carbon dioxide and heat at the surface and transporting it in the deep ocean, where it is trapped for long periods," said Sam Stevens, doctoral candidate at the University of British Columbia and lead author on the study. "Studying changes in the structure of the world's oceans can provide us with vital insight into this process and how the ocean is responding to climate change."
One particular layer in the North Atlantic Ocean, a water mass called the North Atlantic Subtropical Mode Water (or STMW), is very efficient at drawing carbon dioxide out of the atmosphere. It represents around 20% of the entire carbon dioxide uptake in the mid-latitude North Atlantic and is an important reservoir of nutrients for phytoplankton -- the base of the marine food chain -- at the surface of the ocean.
Using data from two of the world's longest-running open-ocean research programs -- the Bermuda Atlantic Time-series Study (BATS) Program and Hydrostation 'S' -- the team found that as much as 93% of STMW has been lost in the past decade. This loss is coupled with a significant warming of the STMW (0.5 to 0.71 degrees Celsius or 0.9 to 1.3 degrees Fahrenheit), culminating in the weakest, warmest STMW layer ever recorded.
"Although some STMW loss is expected due to the prevailing atmospheric conditions of the past decade, these conditions do not explain the magnitude of loss that we have recorded," said Professor Nick Bates, BIOS senior scientist and principal investigator of the BATS Program. "We find that the loss is correlated with different climate change indicators, such as increased surface ocean heat content, suggesting that ocean warming may have played a role in the reduced STMW formation of the past decade."
These findings outline a worrying relationship where ocean warming is restricting STMW formation and changing the anatomy of the North Atlantic, making it a less efficient sink for heat and carbon dioxide.
Read more at Science Daily
A team of scientists from the University of British Columbia, the Bermuda Institute of Ocean Sciences (BIOS), the French Institute for Ocean Science at the University of Brest, and the University of Southampton recently published the results of an analysis of North Atlantic Ocean water masses in the journal Nature Climate Change.
"The oceans play a vital role in buffering the Earth from climate change by absorbing carbon dioxide and heat at the surface and transporting it in the deep ocean, where it is trapped for long periods," said Sam Stevens, doctoral candidate at the University of British Columbia and lead author on the study. "Studying changes in the structure of the world's oceans can provide us with vital insight into this process and how the ocean is responding to climate change."
One particular layer in the North Atlantic Ocean, a water mass called the North Atlantic Subtropical Mode Water (or STMW), is very efficient at drawing carbon dioxide out of the atmosphere. It represents around 20% of the entire carbon dioxide uptake in the mid-latitude North Atlantic and is an important reservoir of nutrients for phytoplankton -- the base of the marine food chain -- at the surface of the ocean.
Using data from two of the world's longest-running open-ocean research programs -- the Bermuda Atlantic Time-series Study (BATS) Program and Hydrostation 'S' -- the team found that as much as 93% of STMW has been lost in the past decade. This loss is coupled with a significant warming of the STMW (0.5 to 0.71 degrees Celsius or 0.9 to 1.3 degrees Fahrenheit), culminating in the weakest, warmest STMW layer ever recorded.
"Although some STMW loss is expected due to the prevailing atmospheric conditions of the past decade, these conditions do not explain the magnitude of loss that we have recorded," said Professor Nick Bates, BIOS senior scientist and principal investigator of the BATS Program. "We find that the loss is correlated with different climate change indicators, such as increased surface ocean heat content, suggesting that ocean warming may have played a role in the reduced STMW formation of the past decade."
These findings outline a worrying relationship where ocean warming is restricting STMW formation and changing the anatomy of the North Atlantic, making it a less efficient sink for heat and carbon dioxide.
Read more at Science Daily
Cold War nuclear bomb tests reveal true age of whale sharks
Atomic bomb tests conducted during the Cold War have helped scientists for the first time correctly determine the age of whale sharks.
The discovery, published in the journal Frontiers in Marine Science, will help ensure the survival of the species -- the largest fish in the world -- which is classified as endangered.
Measuring the age of whale sharks (Rhincodon typus) has been difficult because, like all sharks and rays, they lack bony structures called otoliths that are used to assess the age of other fish.
Whale shark vertebrae feature distinct bands -- a little like the rings of a tree trunk -- and it was known that these increased in number as the animal grew older. However, some studies suggested that a new ring was formed every year, while others concluded that it happened every six months.
To resolve the question, researchers led by researchers led by Joyce Ong from Rutgers University in New Jersey, USA, Steven Campana from the University of Iceland, and Mark Meekan from the Australian Institute of Marine Science in Perth, Western Australia, turned to the radioactive legacy of the Cold War's nuclear arms race.
During the 1950s and 1960s, the USA, Soviet Union, Great Britain, France and China conducted tests of nuclear weapons. Many of these were explosions detonated several kilometres in the air.
One powerful result of the blasts was the temporary atmospheric doubling of an isotope called carbon-14.
Carbon-14 is a naturally occurring radioactive element that is often used by archaeologists and historians to date ancient bones and artefacts. Its rate of decay is constant and easily measured, making it ideal for providing age estimates for anything over 300 years old.
However, it is also a by-product of nuclear explosions. Fallout from the Cold War tests saturated first the air, and then the oceans. The isotope gradually moved through food webs into every living thing on the planet, producing an elevated carbon-14 label, or signature, which still persists.
This additional radioisotope also decays at a steady rate -- meaning that the amount contained in bone formed at one point in time will be slightly greater than that contained in otherwise identical bone formed more recently.
Using bomb radiocarbon data prepared by Steven Campana, Ong, Meekan, and colleagues set about testing the carbon-14 levels in the growth rings of two long-dead whale sharks stored in Pakistan and Taiwan. Measuring the radioisotope levels in successive growth rings allowed a clear determination of how often they were created -- and thus the age of the animal.
"We found that one growth ring was definitely deposited every year," Dr Meekan said.
"This is very important, because if you over- or under-estimate growth rates you will inevitably end up with a management strategy that doesn't work, and you'll see the population crash."
One of the specimens was conclusively established as 50 years old at death -- the first time such an age has been unambiguously verified.
"Earlier modelling studies have suggested that the largest whale sharks may live as long as 100 years," Dr Meekan said.
"However, although our understanding of the movements, behaviour, connectivity and distribution of whale sharks have improved dramatically over the last 10 years, basic life history traits such as age, longevity and mortality remain largely unknown.
"Our study shows that adult sharks can indeed attain great age and that long lifespans are probably a feature of the species. Now we have another piece of the jigsaw added."
Whale sharks are today protected across their global range and are regarded as a high-value species for eco-tourism. AIMS is the world's leading whale shark research body, and the animal is the marine emblem of Dr Meekan's home state, Western Australia.
Read more at Science Daily
The discovery, published in the journal Frontiers in Marine Science, will help ensure the survival of the species -- the largest fish in the world -- which is classified as endangered.
Measuring the age of whale sharks (Rhincodon typus) has been difficult because, like all sharks and rays, they lack bony structures called otoliths that are used to assess the age of other fish.
Whale shark vertebrae feature distinct bands -- a little like the rings of a tree trunk -- and it was known that these increased in number as the animal grew older. However, some studies suggested that a new ring was formed every year, while others concluded that it happened every six months.
To resolve the question, researchers led by researchers led by Joyce Ong from Rutgers University in New Jersey, USA, Steven Campana from the University of Iceland, and Mark Meekan from the Australian Institute of Marine Science in Perth, Western Australia, turned to the radioactive legacy of the Cold War's nuclear arms race.
During the 1950s and 1960s, the USA, Soviet Union, Great Britain, France and China conducted tests of nuclear weapons. Many of these were explosions detonated several kilometres in the air.
One powerful result of the blasts was the temporary atmospheric doubling of an isotope called carbon-14.
Carbon-14 is a naturally occurring radioactive element that is often used by archaeologists and historians to date ancient bones and artefacts. Its rate of decay is constant and easily measured, making it ideal for providing age estimates for anything over 300 years old.
However, it is also a by-product of nuclear explosions. Fallout from the Cold War tests saturated first the air, and then the oceans. The isotope gradually moved through food webs into every living thing on the planet, producing an elevated carbon-14 label, or signature, which still persists.
This additional radioisotope also decays at a steady rate -- meaning that the amount contained in bone formed at one point in time will be slightly greater than that contained in otherwise identical bone formed more recently.
Using bomb radiocarbon data prepared by Steven Campana, Ong, Meekan, and colleagues set about testing the carbon-14 levels in the growth rings of two long-dead whale sharks stored in Pakistan and Taiwan. Measuring the radioisotope levels in successive growth rings allowed a clear determination of how often they were created -- and thus the age of the animal.
"We found that one growth ring was definitely deposited every year," Dr Meekan said.
"This is very important, because if you over- or under-estimate growth rates you will inevitably end up with a management strategy that doesn't work, and you'll see the population crash."
One of the specimens was conclusively established as 50 years old at death -- the first time such an age has been unambiguously verified.
"Earlier modelling studies have suggested that the largest whale sharks may live as long as 100 years," Dr Meekan said.
"However, although our understanding of the movements, behaviour, connectivity and distribution of whale sharks have improved dramatically over the last 10 years, basic life history traits such as age, longevity and mortality remain largely unknown.
"Our study shows that adult sharks can indeed attain great age and that long lifespans are probably a feature of the species. Now we have another piece of the jigsaw added."
Whale sharks are today protected across their global range and are regarded as a high-value species for eco-tourism. AIMS is the world's leading whale shark research body, and the animal is the marine emblem of Dr Meekan's home state, Western Australia.
Read more at Science Daily
Scientists reveal brain tumors impact normally helpful cells
When the brain gets injured, star-shaped brain cells called astrocytes come to the rescue. In the case of glioma -- the most common type of primary brain tumor -- this protective action comes at a price.
A new study published in Neurochemistry International reveals that gliomas alter astrocyte function, which normally prevents the brain from being flooded with excess excitatory chemicals. This could contribute to the seizures experienced by many brain cancer patients.
"Seizures are a serious and debilitating comorbidity that affect most patients with primary brain tumors. Unfortunately, epilepsy dramatically reduces quality of life, and our current anti-epileptic drugs are not effective for all patients," said Stefanie Robel, an assistant professor at the Fralin Biomedical Research Institute at VTC and the study's co-senior author.
"My lab is looking for other cellular and molecular targets that contribute to seizures resulting from gliomas, and so far, what we're finding is that the scar-forming astrocytes that surround the tumor play an important role."
Gliomas are competitive, fast-growing tumors that -- just like all other living cells -- need an energy source to survive. Composed primarily of glia cells, gliomas take over the brain's microvasculature, syphoning off a fresh supply of nutrients from other healthy cells. The tumors also release toxic levels of glutamate, an excitatory neurotransmitter, which can kill off the brain's densely packed healthy neurons, making space for the cancer to grow. An abundance of glutamate can also cause more neurons to become electrically active, which can result in seizures.
Astrocytes swiftly scar the tumor to protect the brain from further damage -- but this comes at a price.
"Under ordinary circumstances, you'd expect astrocytes to buffer any additional glutamate. Part of their job is to maintain balanced, homeostatic conditions for neurons by removing excess glutamate and potassium," said Robel, who is also an assistant professor in Virginia Tech's School of Neuroscience and the Virginia Tech Carilion School of Medicine. "Like micro vacuum cleaners, they tidy up neurotransmitters and ions floating amid brain cells."
But the astrocytes encasing gliomas exhibited different molecular signatures based on their proximity to the cancer. The cells directly touching the tumor were elongated and swollen, mimicking the response to other brain injuries associated with epilepsy, such as stroke or physical trauma.
Electrophysiology and staining experiments revealed the stretched cells also lacked proper localization or function of proteins needed to carry potassium and glutamate inside an astrocyte. The cells had also lost a vital enzymatic process that converts glutamate into glutamine, a molecule that neurons use to suppress activity.
Under these conditions, the brain's delicate balance of excitation and inhibition tips, and problems arise.
Toxic levels of glutamate emitted from the tumor, exacerbated by the astrocytes dysfunctional state, destroy healthy neurons. Previous studies led by Sontheimer showed that the fluid suspended between brain cells reaches harmful levels of excitability -- enough to spark a seizure. After the first seizure, the circuits involved are preferentially strengthened, making future episodes even more likely.
"A tumor is a dynamic, living tissue that sends and receives chemical signals to surrounding glial cells and neurons, influencing their behavior," Robel said. "What we're seeing is that these very fine changes in astrocyte function and morphology in glioma response could have a very big impact for the patient."
As more research about astrocytic response to injury, disease, and cancer is published, Robel hopes that larger patterns will emerge.
Read more at Science Daily
A new study published in Neurochemistry International reveals that gliomas alter astrocyte function, which normally prevents the brain from being flooded with excess excitatory chemicals. This could contribute to the seizures experienced by many brain cancer patients.
"Seizures are a serious and debilitating comorbidity that affect most patients with primary brain tumors. Unfortunately, epilepsy dramatically reduces quality of life, and our current anti-epileptic drugs are not effective for all patients," said Stefanie Robel, an assistant professor at the Fralin Biomedical Research Institute at VTC and the study's co-senior author.
"My lab is looking for other cellular and molecular targets that contribute to seizures resulting from gliomas, and so far, what we're finding is that the scar-forming astrocytes that surround the tumor play an important role."
Gliomas are competitive, fast-growing tumors that -- just like all other living cells -- need an energy source to survive. Composed primarily of glia cells, gliomas take over the brain's microvasculature, syphoning off a fresh supply of nutrients from other healthy cells. The tumors also release toxic levels of glutamate, an excitatory neurotransmitter, which can kill off the brain's densely packed healthy neurons, making space for the cancer to grow. An abundance of glutamate can also cause more neurons to become electrically active, which can result in seizures.
Astrocytes swiftly scar the tumor to protect the brain from further damage -- but this comes at a price.
"Under ordinary circumstances, you'd expect astrocytes to buffer any additional glutamate. Part of their job is to maintain balanced, homeostatic conditions for neurons by removing excess glutamate and potassium," said Robel, who is also an assistant professor in Virginia Tech's School of Neuroscience and the Virginia Tech Carilion School of Medicine. "Like micro vacuum cleaners, they tidy up neurotransmitters and ions floating amid brain cells."
But the astrocytes encasing gliomas exhibited different molecular signatures based on their proximity to the cancer. The cells directly touching the tumor were elongated and swollen, mimicking the response to other brain injuries associated with epilepsy, such as stroke or physical trauma.
Electrophysiology and staining experiments revealed the stretched cells also lacked proper localization or function of proteins needed to carry potassium and glutamate inside an astrocyte. The cells had also lost a vital enzymatic process that converts glutamate into glutamine, a molecule that neurons use to suppress activity.
Under these conditions, the brain's delicate balance of excitation and inhibition tips, and problems arise.
Toxic levels of glutamate emitted from the tumor, exacerbated by the astrocytes dysfunctional state, destroy healthy neurons. Previous studies led by Sontheimer showed that the fluid suspended between brain cells reaches harmful levels of excitability -- enough to spark a seizure. After the first seizure, the circuits involved are preferentially strengthened, making future episodes even more likely.
"A tumor is a dynamic, living tissue that sends and receives chemical signals to surrounding glial cells and neurons, influencing their behavior," Robel said. "What we're seeing is that these very fine changes in astrocyte function and morphology in glioma response could have a very big impact for the patient."
As more research about astrocytic response to injury, disease, and cancer is published, Robel hopes that larger patterns will emerge.
Read more at Science Daily
Apr 5, 2020
Study offers new insight into the impact of ancient migrations on the European landscape
Neolithic populations have long been credited with bringing about a revolution in farming practices across Europe. However, a new study suggests it was not until the Bronze Age several millennia later that human activity led to significant changes to the continent's landscape.
Scientists from the University of Copenhagen and the University of Plymouth led research tracing how the two major human migrations recorded in Holocene Europe -- the northwestward movement of Anatolian farmer populations during the Neolithic and the westward movement of Yamnaya steppe peoples during the Bronze Age -- unfolded.
In particular, they analysed how they were associated with changes in vegetation -- which led to Europe's forests being replaced with the agricultural landscape still much in evidence today.
Their results, published in PNAS, show the two migrations differ markedly in both their spread and environmental implications, with the Yamnaya expansion moving quicker and resulting in greater vegetation changes than the earlier Neolithic farmer expansion.
The study -- also involving the University of Gothenburg and the University of Cambridge -- used techniques commonly applied in environmental science to model climate and pollution, and applied them to instead analyse human population movements in the last 10 millennia of European history.
It showed that a decline in broad-leaf forest and an increase in pasture and natural grassland vegetation was concurrent with a decline in hunter-gatherer ancestry, and may have been associated with the fast movement of steppe peoples during the Bronze Age.
It also demonstrated that natural variations in climate patterns during this period are associated with these land cover changes.
The research is the first to model the spread of ancestry in ancient genomes through time and space, and provides the first framework for comparing human migrations and land cover changes, while also accounting for changes in climate.
Dr Fernando Racimo, Assistant Professor at the University of Copenhagen and the study's lead author, said: "The movement of steppe peoples that occurred in the Bronze Age had a particularly strong impact on European vegetation. As these peoples were moving westward, we see increases in the amount of pasture lands and decreases in broad leaf forests throughout the continent. We can now also compare movements of genes to the spread of cultural packages. In the case of the Neolithic farming revolution, for example, the two track each other particularly well, in both space and time."
The research made use of land cover maps showing vegetation change over the past 11,000 years, which were produced through the University of Plymouth's Deforesting Europe project.
Scientists working on that project have previously shown more than half of Europe's forests have disappeared over the past 6,000 years due to increasing demand for agricultural land and the use of wood as a source of fuel.
Dr Jessie Woodbridge, Research Fellow at the University of Plymouth and co-author on the study, added: "European landscapes have been transformed drastically over thousands of years. Knowledge of how people interacted with their environment in the past has implications for understanding the way in which people use and impact upon the world today. Collaboration with palaeo-geneticists has allowed the migration of human populations in the past to be tracked using ancient DNA, and for the first time allowed us to assess the impact of different farming populations on land-cover change, which provides new insights into past human-environment interactions."
From Science Daily
Scientists from the University of Copenhagen and the University of Plymouth led research tracing how the two major human migrations recorded in Holocene Europe -- the northwestward movement of Anatolian farmer populations during the Neolithic and the westward movement of Yamnaya steppe peoples during the Bronze Age -- unfolded.
In particular, they analysed how they were associated with changes in vegetation -- which led to Europe's forests being replaced with the agricultural landscape still much in evidence today.
Their results, published in PNAS, show the two migrations differ markedly in both their spread and environmental implications, with the Yamnaya expansion moving quicker and resulting in greater vegetation changes than the earlier Neolithic farmer expansion.
The study -- also involving the University of Gothenburg and the University of Cambridge -- used techniques commonly applied in environmental science to model climate and pollution, and applied them to instead analyse human population movements in the last 10 millennia of European history.
It showed that a decline in broad-leaf forest and an increase in pasture and natural grassland vegetation was concurrent with a decline in hunter-gatherer ancestry, and may have been associated with the fast movement of steppe peoples during the Bronze Age.
It also demonstrated that natural variations in climate patterns during this period are associated with these land cover changes.
The research is the first to model the spread of ancestry in ancient genomes through time and space, and provides the first framework for comparing human migrations and land cover changes, while also accounting for changes in climate.
Dr Fernando Racimo, Assistant Professor at the University of Copenhagen and the study's lead author, said: "The movement of steppe peoples that occurred in the Bronze Age had a particularly strong impact on European vegetation. As these peoples were moving westward, we see increases in the amount of pasture lands and decreases in broad leaf forests throughout the continent. We can now also compare movements of genes to the spread of cultural packages. In the case of the Neolithic farming revolution, for example, the two track each other particularly well, in both space and time."
The research made use of land cover maps showing vegetation change over the past 11,000 years, which were produced through the University of Plymouth's Deforesting Europe project.
Scientists working on that project have previously shown more than half of Europe's forests have disappeared over the past 6,000 years due to increasing demand for agricultural land and the use of wood as a source of fuel.
Dr Jessie Woodbridge, Research Fellow at the University of Plymouth and co-author on the study, added: "European landscapes have been transformed drastically over thousands of years. Knowledge of how people interacted with their environment in the past has implications for understanding the way in which people use and impact upon the world today. Collaboration with palaeo-geneticists has allowed the migration of human populations in the past to be tracked using ancient DNA, and for the first time allowed us to assess the impact of different farming populations on land-cover change, which provides new insights into past human-environment interactions."
From Science Daily
New metabolism discovered in bacteria
They make sauerkraut sour, turn milk into yogurt and cheese, and give rye bread its intensive flavour: bacteria that ferment nutrients instead of using oxygen to extract their energy. Acetobacterium woodii (short: A. woodii) is one of these anaerobic living microbes. Cheese and bread are not its line of business -- it lives far from oxygen in the sediments on the floor of the ocean, and can also be found in sewage treatment plants and the intestines of termites.
These biotopes are teeming with microbes that use the organic substances to their advantage in different ways. A number of bacteria ferment sugars, fatty acids and alcohols to acetic acid, also creating hydrogen (H2) in the process. In higher concentration, however, hydrogen inhibits the fermentation -- too much hydrogen stops the fermentation reaction. For this reason, fermenting bacteria live together with microbes that depend on precisely this hydrogen, methanogens, for example, that create methane from hydrogen and carbon dioxide and thus gain energy. Both partners profit from this association -- and are simultaneously so dependent on each other that neither one can survive without the other.
A. woodii masters both disciplines of the anaerobic "hydrogen association": it can ferment organic substances into acetic acid, and can also form acetic acid from carbon dioxide and hydrogen. In doing so, A. woodii recycles the important hydrogen within its own cell, as has now been discovered by the microbiologists in Professor Volker Müller's team at the Institute for Molecular Biosciences at Goethe University Frankfurt.
In the laboratory, the Frankfurt scientists turned off the gene for the enzyme that creates hydrogen in A. woodii, which is called hydrogenase. The result: the bacterium was only able to grow, for example in a medium with fructose, if hydrogen was added externally. Different additional tests confirmed that both paths for creating acetic acid are connected to hydrogen that does not leave the cell.
"Though the 'hydrogen recycling' we discovered, A. woodii possesses a maximum of metabolic flexibility," says the Frankfurt experimenter Dr Anja Wiechmann. "In one cycle, it can both create and use hydrogen itself, or utilise hydrogen from external sources. This makes it capable of living both from organic as well as solely from inorganic substances."
Professor Volker Müller explains: "Our findings have implications far beyond the study of Acetobacterium woodii. There have already been speculations that many ancient life forms possess the kind of metabolism that we have described in A. woodii. This is assumed, for example for the Asgard archaea that were just discovered a few years ago on the seabed off of California. Our investigations provide the first evidence that these paths of metabolism actually exist."
From Science Daily
These biotopes are teeming with microbes that use the organic substances to their advantage in different ways. A number of bacteria ferment sugars, fatty acids and alcohols to acetic acid, also creating hydrogen (H2) in the process. In higher concentration, however, hydrogen inhibits the fermentation -- too much hydrogen stops the fermentation reaction. For this reason, fermenting bacteria live together with microbes that depend on precisely this hydrogen, methanogens, for example, that create methane from hydrogen and carbon dioxide and thus gain energy. Both partners profit from this association -- and are simultaneously so dependent on each other that neither one can survive without the other.
A. woodii masters both disciplines of the anaerobic "hydrogen association": it can ferment organic substances into acetic acid, and can also form acetic acid from carbon dioxide and hydrogen. In doing so, A. woodii recycles the important hydrogen within its own cell, as has now been discovered by the microbiologists in Professor Volker Müller's team at the Institute for Molecular Biosciences at Goethe University Frankfurt.
In the laboratory, the Frankfurt scientists turned off the gene for the enzyme that creates hydrogen in A. woodii, which is called hydrogenase. The result: the bacterium was only able to grow, for example in a medium with fructose, if hydrogen was added externally. Different additional tests confirmed that both paths for creating acetic acid are connected to hydrogen that does not leave the cell.
"Though the 'hydrogen recycling' we discovered, A. woodii possesses a maximum of metabolic flexibility," says the Frankfurt experimenter Dr Anja Wiechmann. "In one cycle, it can both create and use hydrogen itself, or utilise hydrogen from external sources. This makes it capable of living both from organic as well as solely from inorganic substances."
Professor Volker Müller explains: "Our findings have implications far beyond the study of Acetobacterium woodii. There have already been speculations that many ancient life forms possess the kind of metabolism that we have described in A. woodii. This is assumed, for example for the Asgard archaea that were just discovered a few years ago on the seabed off of California. Our investigations provide the first evidence that these paths of metabolism actually exist."
From Science Daily
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