Showing posts with label from. Show all posts
Showing posts with label from. Show all posts
Tuesday, December 10, 2024
Firm warning from Trump to NATO
Saturday, November 30, 2024
Italy revokes over 3,000 applications from non-EU workers in smuggling crackdown
Saturday, February 8, 2020
Normal resting heart rate appears to vary widely from person to person
Monitoring heart rate (stock image).
A person's normal resting heart rate is fairly consistent over time, but may vary from others' by up to 70 beats per minute, according to analysis of the largest dataset of daily resting heart rate ever collected. Giorgio Quer of the Scripps Research Translational Institute in La Jolla, California, and colleagues present these findings in the open-access journal PLOS ONE on February 5, 2020 as part of an upcoming PLOS Collection on Digital Health Technology.
A routine visit to the doctor usually involves a measurement of resting heart rate, but such measurements are rarely actionable unless they deviate significantly from a "normal" range established by population-level studies. However, wearables that track heart rate now provide the opportunity to continuously monitor heart rate over time, and identify normal resting heart rates at the individual level.
In the largest study of its kind to date, Quer and colleagues retrospectively analyzed de-identified heart rate data from wearables worn for a median of 320 days by 92,457 people from across the U.S. Nearly 33 million days' worth of heart rate data were collected in total. The researchers used the data to examine variations in resting heart rate for individuals over time, as well as between individuals with different characteristics.
The analysis showed that one person's mean daily resting heart rate may differ by up to 70 beats per minute from another person's normal rate. Taken together, age, sex, body mass index (BMI), and average daily sleep duration accounted for less than 10 percent of the observed variation between individuals.
The authors observed also a small seasonal trend in the resting heart rate, with slightly higher values observed in January and slightly lower values in July. The researchers also found that some individuals may occasionally experience brief periods when their resting heart rate differs by 10 or more beats per minute from their normal range.
These findings suggest the potential value of further research to investigate whether tracking a person's daily resting heart rate could enable earlier detection of clinically important changes.
The authors add: "Day-to-day changes in resting heart rate could be the first true, individualized digital vital sign, which is only now possible to measure thanks to wearable sensor technologies. We analyzed the extent of inter- and intra-individual changes in resting heart rate over a prolonged period of time, showing distinct patterns of variation according to age and sex, time of the year, average sleep duration and body mass index. These variations in resting heart rate may allow for the identification of early unexpected changes in an individuals' health."
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Tuesday, February 4, 2020
Low-energy solar particles from beyond Earth found near the Sun
Sun (stock image; elements furnished by NASA).
Using data from NASA's Parker Solar Probe (PSP), a team led by Southwest Research Institute identified low-energy particles lurking near the Sun that likely originated from solar wind interactions well beyond Earth orbit. PSP is venturing closer to the Sun than any previous probe, carrying hardware SwRI helped develop. Scientists are probing the enigmatic features of the Sun to answer many questions, including how to protect space travelers and technology from the radiation associated with solar events.
"Our main goal is to determine the acceleration mechanisms that create and transport dangerous high-energy particles from the solar atmosphere into the solar system, including the near-Earth environment," said Dr. Mihir Desai, a mission co-investigator on the Integrated Science Investigation of the Sun (IS?IS) instrument suite, a multi-institutional project led by Principal Investigator Prof. Dave McComas of Princeton University.. IS?IS consists of two instruments, Energetic Particle Instrument-High (EPI-Hi) and Energetic Particle Instrument-Low (EPI-Lo). "With EPI-Lo, we were able to measure extremely low-energy particles unexpectedly close to the solar environment. We considered many explanations for their presence, but ultimately determined they are the smoking gun pointing to interactions between slow- and fast-moving regions of the solar wind that accelerate high-energy particles from beyond the orbit of Earth. Some of those travel back toward the Sun, slowing against the tide of the outpouring solar wind but still retaining surprisingly high energies."
PSP, which will travel within 4 million miles of the Sun's surface, is collecting new solar data to help scientists understand how solar events, such as coronal mass ejections, impact life on Earth. During the rising portion of the Sun's activity cycle, our star releases huge quantities of energized matter, magnetic fields and electromagnetic radiation in the form of coronal mass ejections (CMEs). This material is integrated into the solar wind, the steady stream of charged particles released from the Sun's upper atmosphere. The high-energy solar energetic particles (SEPs) present a serious radiation threat to human explorers living and working outside low-Earth orbit and to technological assets such as communications and scientific satellites in space. The mission is making the first-ever direct measurements of both the low-energy source populations as well as the more hazardous, higher-energy particles in the near-Sun environment, where the acceleration takes place.
When the Sun's activity reaches a lull, roughly about every 11 years, solar equatorial regions emit slower solar wind streams, traveling around 1 million miles per hour, while the poles spew faster streams, traveling twice as fast at 2 million miles per hour. Stream Interaction Regions (SIRs) are created by interactions at boundaries between the fast and slow solar wind. Fast-moving streams tend to overtake slower streams that originate westward of them on the Sun, forming turbulent corotating interaction regions (CIRs) that produce shock waves and accelerated particles, not unlike those produced by CMEs.
"For the first time, we observed low-energy particles from these CIRs near the orbit of Mercury," Desai said. "We also compared the PSP data with data from STEREO, another solar energy probe. By measuring the full range of energetic populations and correlating the data with other measurements, we hope to get a clear picture of the origin and the processes that accelerate these particles. Our next step is to integrate the data into models to better understand the origin of SEPs and other materials. Parker Solar Probe will solve many puzzling scientific questions -- and is guaranteed to generate new ones as well."
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Tuesday, December 24, 2019
Unexpected Dip in Gamma Rays from the Sun
The sun radiates at a range of energies from the high-energy range to the low-energy range. However, new data, spanning this broad energy range, reveals just how much we don’t know about our own star.
The gamma-rays we observe from the Sun are thought to be due to the interactions of hadronic cosmic rays with the solar atmosphere. Although gamma rays are produced in the solar interior, they are thought to leave the sun as much lower energy waves due to scattering effects. Back in 1991 David Seckel, Todor Stanev and Thomas Gaisser thus proposed that cosmic rays from outer space would be turned around or “mirrored” before entering the sun, thus emerging as a faint glow of gamma-rays. However, the underlying mechanism responsible for the production of these gamma rays is not fully understood – all that is known is that its efficiency must be enhanced by magnetic field interactions. Read more here.
To further understand the mechanisms responsible, Qing-Wen Tang and his team analyzed the gamma ray emission from the sun for the past 9 years – spanning nearly one full 11-year solar cycle. The magnetic activity of the sun oscillates from low to high activity over an 11-year cycle – the solar cycle.
In agreement with recent studies they detected significant emission across all energy ranges – from 1-200 billion electron volts (1-200 GeV). As well, as expected, they observed clear anticorrelation between the lower energy gamma-ray emission and solar cycle – during solar minimum more cosmic rays can reach the magnetic field near the sun’s surface to get “mirrored”, which is why more gamma-rays of the lower energy range would be observed at solar minimum. However, in the middle range of energies of 30-50 billion electron volts (30-50 GeV) they found a dip in an otherwise continuous spectrum. The team say that such a dip “was not predicted, is not understood, and may provide crucial clues to the gamma-ray emission mechanism.”
The lower energy gamma ray emission can be explained by the current theory, however, the significant emission of high energy gamma rays, along with the dip in the data, does not agree with the current theory as put forward by Seckel, Stanev and Gaisser.
“It’s amazing that we were so spectacularly wrong about something we should understand really well: the sun.” – Brian Fields, a particle astrophysicist at the University of Illinois.
Our understanding on the sun, its magnetic field and/or new physics could be the answer. To delve deeper the team of scientists investigating the data hope that more data, and data in the even high energy realms of trillions of electron volts (TeV), could provide the answer.
“The worst that can happen here is that we find out that the sun is stranger and more beautiful than we ever imagined … and the best that could happen is we discover some kind of new physics.” – John Beacom, a professor at Ohio State and one of the leaders on the analysis.
RSF in perspective
If the gamma-rays are of high enough energy and intensity – as would be produced by a black hole dynamic – then higher energy gamma-rays would be observed to be emanating from the sun and would not be as affected by the effects of scattering. Perhaps the gamma-rays we observe are both from the interior black hole dynamic of the sun and the exterior “mirrored” cosmic rays as proposed by Seckel, Stanev and Gaisser. So, we observe the very high above 50 GeV from the interior and the very low 1-10 GeV from the surface – maybe that is why we see a gap in the spectrum. There are many interesting explanations, but one thing for sure is our understanding of the sun, its energy and its magnetic field are yet to be fully understood.
Was a Star Ejected from Our Central Black Hole?
Was a Star Ejected from Our Central Black Hole?
Generally thought to be the point of no return, our very own black hole seems to have ejected a star at hyper velocity.
In something known as the Hills mechanism – which occurs in binary star systems when they are disrupted by a super massive black hole – the stars are pulled apart and left to continue on their separate journeys. The closest star is pulled into an orbit around the black hole while the other is ejected at extremely high velocity. However, although this was proposed in 1988 by astronomer Jack Hills, it has never been confirmed.
Now, a worldwide team of scientists led by Ting Li have observed what they believe to be the first example of such a mechanism.
The team utilised data from the 3.9 metre Anglo-Australian Telescope as part of the Southern Stellar Stream Spectroscopic Survey – a survey that aims to map the kinematics and chemistry of long, dense regions of stars, known as stellar streams. Looking through the data for any stars with velocities greater than 800km/s, the team came across a star with a radial velocity of ~1020 km/s – that’s more than 2 million miles per hour. Further analysis revealed the star, known as S5-HVS, is a hot dwarf star more than twice the mass of our Sun and located 9 kpc (kila parsecs) – approximately 30 thousand light years – from the galactic centre in the Jhelum stellar stream system. Given the measured distance, the proper motion and the radial velocity, the total velocity of the star in the Galactic rest frame is a whopping 1755 km/s – almost 4 million miles per hour – making it one of the fastest known stars in the Galaxy.
To infer the origin of the star, the team studied the kinematics and traced the orbit backwards in time in the gravitational potential of the Milky Way. Remarkably, they found that the star can unambiguously be traced back to the Galactic Centre where it was ejected at a speed of 1800km/s 4.8 million years ago, making S5-HVS the first clear demonstration of the Hill Mechanism.
Tuesday, December 17, 2019
First identified comet to visit our solar system from another star
Comet 2I/Borisov is only the second interstellar object known to have passed through the solar system. These two images, taken by NASA's Hubble Space Telescope, capture the comet appearing near a background galaxy (left) and soon after its closest approach to the Sun (right).
Credit: NASA, ESA, and D. Jewitt (UCLA)
When astronomers see something in the universe that at first glance seems like one-of-a-kind, it's bound to stir up a lot of excitement and attention. Enter comet 2I/Borisov. This mysterious visitor from the depths of space is the first identified comet to arrive here from another star. We don't know from where or when the comet started heading toward our Sun, but it won't hang around for long. The Sun's gravity is slightly deflecting its trajectory, but can't capture it because of the shape of its orbit and high velocity of about 100,000 miles per hour.
Telescopes around the world have been watching the fleeting visitor. NASA's Hubble Space Telescope has provided the sharpest views as the comet skirts by our Sun. Since October the space telescope has been following the comet like a sports photographer following horses speeding around a racetrack. Hubble revealed that the heart of the comet, a loose agglomeration of ices and dust particles, is likely no more than about 3,200 feet across, about the length of nine football fields. Though comet Borisov is the first of its kind, no doubt there are many other comet vagabonds out there, plying the space between stars. Astronomers will eagerly be on the lookout for the next mysterious visitor from far beyond.
These two images, taken by Hubble, capture comet 2I/Borisov streaking though our solar system and on its way back to interstellar space. It is only the second interstellar object known to have passed through the solar system.
Nov. 16, 2019, photo
The comet appears in front of a distant background spiral galaxy (2MASX J10500165-0152029). The galaxy's bright central core is smeared in the image because Hubble was tracking the comet. Comet Borisov was approximately 203 million miles from Earth in this exposure. Its tail of ejected dust streaks off to the upper right. The comet has been artificially colored blue to discriminate fine detail in the halo of dust, or coma, surrounding the central nucleus. It also helps to visually separate the comet from the background galaxy.
Dec. 9, 2019, photo
Hubble revisited the comet shortly after its closest approach to the Sun where it received maximum heating after spending most of its life in frigid interstellar space. The comet also reached a breathtaking maximum speed of about 100,000 miles per hour. Comet Borisov is 185 million miles from Earth in this photo, near the inner edge of the asteroid belt but below it. The nucleus, an agglomeration of ices and dust, is still too small to be resolved. The bright central portion is a coma made up of dust leaving the surface. The comet will make its closest approach to Earth in late December at a distance of 180 million miles.
"Hubble gives us the best upper limit of the size of comet Borisov's nucleus, which is the really important part of the comet," said David Jewitt, a UCLA professor of planetary science and astronomy, whose team has captured the best and sharpest look at this first confirmed interstellar comet. "Surprisingly, our Hubble images show that its nucleus is more than 15 times smaller than earlier investigations suggested it might be. Our Hubble images show that the radius is smaller than half a kilometer. Knowing the size is potentially useful for beginning to estimate how common such objects may be in the solar system and our galaxy. Borisov is the first known interstellar comet, and we would like to learn how many others there are."
Crimean amateur astronomer Gennady Borisov discovered the comet on Aug. 30, 2019, and reported the position measurements to the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts. The Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory in Pasadena, California, working with the Minor Planet Center, computed an orbit for the comet, which shows that it came from elsewhere in our Milky Way galaxy, point of origin unknown.
Nevertheless, observations by numerous telescopes show that the comet's chemical composition is similar to the comets found inside our solar system, providing evidence that comets also form around other stars. By the middle of 2020 the comet will have already zoomed past Jupiter's distance of 500 million miles on its way back into the frozen abyss of interstellar space.
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Sunday, December 15, 2019
First identified comet to visit our solar system from another star
Comet 2I/Borisov is only the second interstellar object known to have passed through the solar system. These two images, taken by NASA's Hubble Space Telescope, capture the comet appearing near a background galaxy (left) and soon after its closest approach to the Sun (right).
When astronomers see something in the universe that at first glance seems like one-of-a-kind, it's bound to stir up a lot of excitement and attention. Enter comet 2I/Borisov. This mysterious visitor from the depths of space is the first identified comet to arrive here from another star. We don't know from where or when the comet started heading toward our Sun, but it won't hang around for long. The Sun's gravity is slightly deflecting its trajectory, but can't capture it because of the shape of its orbit and high velocity of about 100,000 miles per hour.
Telescopes around the world have been watching the fleeting visitor. NASA's Hubble Space Telescope has provided the sharpest views as the comet skirts by our Sun. Since October the space telescope has been following the comet like a sports photographer following horses speeding around a racetrack. Hubble revealed that the heart of the comet, a loose agglomeration of ices and dust particles, is likely no more than about 3,200 feet across, about the length of nine football fields. Though comet Borisov is the first of its kind, no doubt there are many other comet vagabonds out there, plying the space between stars. Astronomers will eagerly be on the lookout for the next mysterious visitor from far beyond.
These two images, taken by Hubble, capture comet 2I/Borisov streaking though our solar system and on its way back to interstellar space. It is only the second interstellar object known to have passed through the solar system.
Nov. 16, 2019, photo
The comet appears in front of a distant background spiral galaxy (2MASX J10500165-0152029). The galaxy's bright central core is smeared in the image because Hubble was tracking the comet. Comet Borisov was approximately 203 million miles from Earth in this exposure. Its tail of ejected dust streaks off to the upper right. The comet has been artificially colored blue to discriminate fine detail in the halo of dust, or coma, surrounding the central nucleus. It also helps to visually separate the comet from the background galaxy.
Dec. 9, 2019, photo
Hubble revisited the comet shortly after its closest approach to the Sun where it received maximum heating after spending most of its life in frigid interstellar space. The comet also reached a breathtaking maximum speed of about 100,000 miles per hour. Comet Borisov is 185 million miles from Earth in this photo, near the inner edge of the asteroid belt but below it. The nucleus, an agglomeration of ices and dust, is still too small to be resolved. The bright central portion is a coma made up of dust leaving the surface. The comet will make its closest approach to Earth in late December at a distance of 180 million miles.
"Hubble gives us the best upper limit of the size of comet Borisov's nucleus, which is the really important part of the comet," said David Jewitt, a UCLA professor of planetary science and astronomy, whose team has captured the best and sharpest look at this first confirmed interstellar comet. "Surprisingly, our Hubble images show that its nucleus is more than 15 times smaller than earlier investigations suggested it might be. Our Hubble images show that the radius is smaller than half a kilometer. Knowing the size is potentially useful for beginning to estimate how common such objects may be in the solar system and our galaxy. Borisov is the first known interstellar comet, and we would like to learn how many others there are."
Crimean amateur astronomer Gennady Borisov discovered the comet on Aug. 30, 2019, and reported the position measurements to the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts. The Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory in Pasadena, California, working with the Minor Planet Center, computed an orbit for the comet, which shows that it came from elsewhere in our Milky Way galaxy, point of origin unknown.
Nevertheless, observations by numerous telescopes show that the comet's chemical composition is similar to the comets found inside our solar system, providing evidence that comets also form around other stars. By the middle of 2020 the comet will have already zoomed past Jupiter's distance of 500 million miles on its way back into the frozen abyss of interstellar space.
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Saturday, December 7, 2019
4 Hyderabad rape accused snatched 2 guns from 10 cops, shot dead: Police
HYDERABAD/NEW DELHI: All four accused in the rape-and-murder of a 25-year-old woman veterinarian last month were killed by police on Friday morning, triggering a chorus of praise for what many saw as speedy justice but also raising concerns over extra-judicial executions.
The incident took place around 6.30 am when the accused, lorry workers aged between 20 and 24, were taken to the scene of the crime near Hyderabad for a reconstruction of events as part of the investigation.
Sunday, December 1, 2019
Scientists inch closer than ever to signal from cosmic dawn
Scientists inch closer than ever to signal from cosmic dawn
Around 12 billion years ago, the universe emerged from a great cosmic dark age as the first stars and galaxies lit up. With a new analysis of data collected by the Murchison Widefield Array (MWA) radio telescope, scientists are now closer than ever to detecting the ultra-faint signature of this turning point in cosmic history.
In a paper on the preprint site ArXiv and soon to be published in the Astrophysical Journal, researchers present the first analysis of data from a new configuration of the MWA designed specifically to look for the signal of neutral hydrogen, the gas that dominated the universe during the cosmic dark age. The analysis sets a new limit -- the lowest limit yet -- for the strength of the neutral hydrogen signal.
"We can say with confidence that if the neutral hydrogen signal was any stronger than the limit we set in the paper, then the telescope would have detected it," said Jonathan Pober, an assistant professor of physics at Brown University and corresponding author on the new paper. "These findings can help us to further constrain the timing of when the cosmic dark ages ended and the first stars emerged."
The research was led by Wenyang Li, who performed the work as a Ph.D. student at Brown. Li and Pober collaborated with an international group of researchers working with the MWA.
Despite its importance in cosmic history, little is known about the period when the first stars formed, which is known as the Epoch of Reionization (EoR). The first atoms that formed after the Big Bang were positively charged hydrogen ions -- atoms whose electrons were stripped away by the energy of the infant universe. As the universe cooled and expanded, hydrogen atoms reunited with their electrons to form neutral hydrogen. And that's just about all there was in the universe until about 12 billion years ago, when atoms started clumping together to form stars and galaxies. Light from those objects re-ionized the neutral hydrogen, causing it to largely disappear from interstellar space.
The goal of projects like the one happening at MWA is to locate the signal of neutral hydrogen from the dark ages and measure how it changed as the EoR unfolded. Doing so could reveal new and critical information about the first stars -- the building blocks of the universe we see today. But catching any glimpse of that 12-billion-year-old signal is a difficult task that requires instruments with exquisite sensitivity.
When it began operating in 2013, the MWA was an array of 2,048 radio antennas arranged across the remote countryside of Western Australia. The antennas are bundled together into 128 "tiles," whose signals are combined by a supercomputer called the Correlator. In 2016, the number of tiles was doubled to 256, and their configuration across the landscape was altered to improve their sensitivity to the neutral hydrogen signal. This new paper is the first analysis of data from the expanded array.
Neutral hydrogen emits radiation at a wavelength of 21 centimeters. As the universe has expanded over the past 12 billion years, the signal from the EoR is now stretched to about 2 meters, and that's what MWA astronomers are looking for. The problem is there are myriad other sources that emit at the same wavelength -- human-made sources like digital television as well as natural sources from within the Milky Way and from millions of other galaxies.
"All of these other sources are many orders of magnitude stronger than the signal we're trying to detect," Pober said. "Even an FM radio signal that's reflected off an airplane that happens to be passing above the telescope is enough to contaminate the data."
To home in on the signal, the researchers use a myriad of processing techniques to weed out those contaminants. At the same time, they account for the unique frequency responses of the telescope itself.
"If we look at different radio frequencies or wavelengths, the telescope behaves a little differently," Pober said. "Correcting for the telescope response is absolutely critical for then doing the separation of astrophysical contaminants and the signal of interest."
Those data analysis techniques combined with the expanded capacity of the telescope itself resulted in a new upper bound of the EoR signal strength. It's the second consecutive best-limit-to-date analysis to be released by MWA and raises hope that the experiment will one day detect the elusive EoR signal.
"This analysis demonstrates that the phase two upgrade had a lot of its desired effects and that the new analysis techniques will improve future analyses," Pober said. "The fact that MWA has now published back-to-back the two best limits on the signal gives momentum to the idea that this experiment and its approach has a lot of promise."
The research was supported in part by the U.S. National Science Foundation (grant #1613040). The MWA receives support from the Australian government and acknowledges Wajarri Yamatji people as the traditional owners of the observatory site.
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Saturday, November 30, 2019
A runaway star ejected from the galactic heart of darkness
A runaway star ejected from the galactic heart of darkness
Astronomers have spotted an ultrafast star, traveling at a blistering 6 million km/h, that was ejected by the supermassive black hole at the heart at the Milky Way five million years ago.
The discovery of the star, known as S5-HVS1, was made by Carnegie Mellon University Assistant Professor of Physics Sergey Koposov as part of the Southern Stellar Stream Spectroscopic Survey (S5). Located in the constellation of Grus -- the Crane -- S5-HVS1 was found to be moving ten times faster than most stars in the Milky Way.
"The velocity of the discovered star is so high that it will inevitably leave the galaxy and never return," said Douglas Boubert from the University of Oxford, a co-author on the study.
Astronomers have wondered about high velocity stars since their discovery only two decades ago. S5-HVS1 is unprecedented due to its high speed and close passage to the Earth, "only" 29 thousand light years away. With this information, astronomers could track its journey back into the center of the Milky Way, where a four million solar mass black hole, known as Sagittarius A*, lurks.
"This is super exciting, as we have long suspected that black holes can eject stars with very high velocities. However, we never had an unambiguous association of such a fast star with the galactic center," said Koposov, the lead author of this work and member of Carnegie Mellon's McWilliams Center for Cosmology. "We think the black hole ejected the star with a speed of thousands of kilometers per second about five million years ago. This ejection happened at the time when humanity's ancestors were just learning to walk on two feet."
Superfast stars can be ejected by black holes via the Hills Mechanism, proposed by astronomer Jack Hills thirty years ago. Originally, S5-HSV1 lived with a companion in a binary system, but they strayed too close to Sagittarius A*. In the gravitational tussle, the companion star was captured by the black hole, while S5-HVS1 was thrown out at extremely high speed.
"This is the first clear demonstration of the Hills Mechanism in action," said Ting Li from Carnegie Observatories and Princeton University, and leader of the S5 Collaboration. "Seeing this star is really amazing as we know it must have formed in the galactic center, a place very different to our local environment. It is a visitor from a strange land."
The discovery of S5-HVS1 was made with the 3.9-meter Anglo-Australian Telescope (AAT) near Coonabarabran, NSW, Australia, coupled with superb observations from the European Space Agency's Gaia satellite, that allowed the astronomers to reveal the full speed of the star and its journey from the center of the Milky Way.
"The observations would not be possible without the unique capabilities of the 2dF instrument on the AAT," said Daniel Zucker, an astronomer at Macquarie University in Sydney, Australia, and a member of the S5 executive committee. "It's been conducting cutting-edge research for over two decades and still is the best facility in the world for our project."
These results were published on November 4 online in the Monthly Notices of the Royal Astronomical Society, and the S5 collaboration unites astronomers from the United States, United Kingdom, Australia and Chile.
"I am so excited this fast-moving star was discovered by S5," says Kyler Kuehn, at Lowell Observatory and a member of the S5 executive committee. "While the main science goal of S5 is to probe the stellar streams -- disrupting dwarf galaxies and globular clusters -- we dedicated spare resources of the instrument to searching for interesting targets in the Milky Way, and voila, we found something amazing for 'free.' With our future observations, hopefully we will find even more!"
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Tuesday, November 26, 2019
Measuring methane from coal and gas in Pennsylvania informative
Measuring methane from coal and gas
While methane pollution caused by natural gas production in Pennsylvania is underestimated by the U.S. Environmental Protection Agency, natural gas still has half the carbon footprint of underground coal mining, according to an international team of researchers.
"At the rates we found for methane, natural gas in Pennsylvania is still much, much cleaner than coal," said Zachary Barkley research associate in meteorology, Penn State. "Obviously, renewable energy would be better, but there is no debate, switching to natural gas is worth it in the short run."
The researchers looked at methane in the atmosphere by flying transects over the southwestern portion of Pennsylvania and adjacent portions of West Virginia and Ohio. Researchers from the University of Maryland collected data from the flights.
"The southwestern part of the state has huge amounts of natural gas and coal and we were getting methane from there during a previous project in northeastern Pennsylvania," said Barkley.
The southwestern area of Pennsylvania has long been a coal mining area and drilling into the Marcellus shale also has increased the numbers of unconventional natural gas wells in the area. The EPA estimates the amounts of methane put into the atmosphere from both coal mining and natural gas drilling every year.
Because both sources of methane exist in the same area, the researchers could not just measure methane and separate the sources. To determine the split between coal and natural gas, the researchers looked at the amounts of both methane and ethane and determined that more ethane is produced from natural gas wells, than from coal mines. They reported their results in a recent issue of Geophysical Research Letters.
Using the ratio of methane to ethane, the researchers found that the amount of methane released to the atmosphere from coal mines was very close to the EPA estimates, but that the amounts of methane from unconventional natural gas wells were between two to eight times the estimated EPA amounts. The EPA estimate is about 0.1 percent leakage, while the study found about 0.5 percent leakage. However, they note that because the wells in the Marcellus shale are such high-production wells, the net impact on climate of this natural gas production is still much lower than from coal mines after accounting for emissions from energy generation.
"High-producing wells have a much lower leakage rate than older wells which only produce 2 to 3 percent of Pennsylvania gas, but are estimated to produce about 40 percent of the state's total emission of methane from natural gas," said Barkley.
The researchers suggest that using the ratio of methane to ethane in other areas where emissions are from mixed sources could help to tease out the percentages of the carbon footprint from each source.
"Burning fossil fuel, whether coal or gas, is bad for the climate," said Kenneth J. Davis, professor of atmospheric and climate science, Penn State. "These underground coal mines are clearly more damaging than Marcellus gas production, but the gas production isn't as clean as we thought. We need more data like this to inform energy policy."
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Trash talk hurts, even when it comes from a robot
Trash talk hurts
Trash talking has a long and colorful history of flustering game opponents, and now researchers at Carnegie Mellon University have demonstrated that discouraging words can be perturbing even when uttered by a robot.
The trash talk in the study was decidedly mild, with utterances such as "I have to say you are a terrible player," and "Over the course of the game your playing has become confused." Even so, people who played a game with the robot -- a commercially available humanoid robot known as Pepper -- performed worse when the robot discouraged them and better when the robot encouraged them.
Lead author Aaron M. Roth said some of the 40 study participants were technically sophisticated and fully understood that a machine was the source of their discomfort.
"One participant said, 'I don't like what the robot is saying, but that's the way it was programmed so I can't blame it,'" said Roth, who conducted the study while he was a master's student in the CMU Robotics Institute.
But the researchers found that, overall, human performance ebbed regardless of technical sophistication.
The study, presented last month at the IEEE International Conference on Robot & Human Interactive Communication (RO-MAN) in New Delhi, India, is a departure from typical human-robot interaction studies, which tend to focus on how humans and robots can best work together.
"This is one of the first studies of human-robot interaction in an environment where they are not cooperating," said co-author Fei Fang, an assistant professor in the Institute for Software Research. It has enormous implications for a world where the number of robots and internet of things (IoT) devices with artificial intelligence capabilities is expected to grow exponentially. "We can expect home assistants to be cooperative," she said, "but in situations such as online shopping, they may not have the same goals as we do."
The study was an outgrowth of a student project in AI Methods for Social Good, a course that Fang teaches. The students wanted to explore the uses of game theory and bounded rationality in the context of robots, so they designed a study in which humans would compete against a robot in a game called "Guards and Treasures." A so-called Stackelberg game, researchers use it to study rationality. This is a typical game used to study defender-attacker interaction in research on security games, an area in which Fang has done extensive work.
Each participant played the game 35 times with the robot, while either soaking in encouraging words from the robot or getting their ears singed with dismissive remarks. Although the human players' rationality improved as the number of games played increased, those who were criticized by the robot didn't score as well as those who were praised.
It's well established that an individual's performance is affected by what other people say, but the study shows that humans also respond to what machines say, said Afsaneh Doryab, a systems scientist at CMU's Human-Computer Interaction Institute (HCII) during the study and now an assistant professor in Engineering Systems and Environment at the University of Virginia. This machine's ability to prompt responses could have implications for automated learning, mental health treatment and even the use of robots as companions, she said.
Future work might focus on nonverbal expression between robot and humans, said Roth, now a Ph.D. student at the University of Maryland. Fang suggests that more needs to be learned about how different types of machines -- say, a humanoid robot as compared to a computer box -- might invoke different responses in humans.
In addition to Roth, Fang and Doryab, the research team included Manuela Veloso, professor of computer science; Samantha Reig, a Ph.D. student in the HCII; Umang Bhatt, who recently completed a joint bachelor's-master's degree program in electrical and computer engineering; Jonathan Shulgach, a master's student in biomedical engineering; and Tamara Amin, who recently finished her master's degree in civil and environmental engineering.
The National Science Foundation provided some support for this work.
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Materials provided by Carnegie Mellon University. Original written by Byron Spice. Note: Content may be edited for style and length.
Monday, November 25, 2019
Milk from teeth: Dental stem cells can generate milk-producing cells
Milk from teeth
The ability of adult stem cells to generate various tissue-specific cell populations is of great interest in the medical and dental research fields. These cells can replace damaged cells and therefore represent a good alternative to classical medical treatments for tissue regeneration. This may even allow the de novo formation of entire tissues and organs in the future.
Dental stem cells capable of regenerating mammary gland
Dental epithelial stem cells are able to generate all epithelial cell types of the teeth; however, it was not yet clear whether these cells could also produce non-dental cell populations. In a recent paper published in the open access journal Cells, a team of researchers led by Thimios Mitsiadis, professor at the Institute of Oral Biology of the University of Zurich (UZH), has shown for the first time that epithelial stem cells isolated from the continuously growing incisors of young mice are indeed able to form mammary glands in female mice.
In a first set of experiments, after removing all cells of mammary origin, dental epithelial stem cells and mammary epithelial cells were directly injected into the areas where the mammary glands normally develop. The researchers used advanced genetic, molecular and imaging tools that allow the precise follow-up of the transplanted dental stem cells in the mammary gland fat pad of the animals. "The results show that the dental stem cells contribute to mammary gland regeneration, and are able to generate all mammary cell populations and, even more strikingly, milk-producing cells," says Mitsiadis.
This work demonstrates the exceptional plasticity of dental epithelial stem cells to generate not only dental tissues but also other tissues of the body. "These findings represent a major contribution to the understanding of the cellular and molecular mechanisms involved in the regenerative capacity of dental stem cells, and, furthermore, indicate the clinical potential of these specific stem cell populations," Mitsiadis adds.
Stem cell-based therapies could be used for breast tissue regeneration
In a second set of experiments, dental epithelial stem cells were injected alone, without mammary epithelial cells. In this case, the dental stem cells were also able to form small ductal systems consisting of branching rudiments. However, in some cases this resulted in the formation of cysts. "This plasticity might be unique for dental epithelial stem cells, since all other non-mammary epithelial cells examined so far have never shown the ability to generate mammary ducts without the support of mammary epithelial cells," states co-author Pierfrancesco Pagella from the Institute of Oral Biology.
One of the most severe pathological conditions is breast cancer, which is often treated with surgery. "Our discovery that dental epithelial stem cells are able to replace cells from the mammary gland opens up new paths for developing stem cell-based therapies that could be used for breast regeneration in the future," says Thimios Mitsiadis.
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Materials provided by University of Zurich. Note: Content may be edited for style and length.
Saturday, November 23, 2019
Ancient Egyptians gathered birds from the wild for sacrifice and mummification
Ibis
In ancient Egypt, Sacred Ibises were collected from their natural habitats to be ritually sacrificed, according to a study released November 13, 2019 in the open-access journal PLOS ONE by Sally Wasef of Griffith University, Australia and colleagues.
Egyptian catacombs are famously filled with the mummified bodies of Sacred Ibises. Between around 664BC and 250AD, it was common practice for the birds to be sacrificed, or much more rarely worshipped in ritual service to the god Thoth, and subsequently mummified. In ancient sites across Egypt, these mummified birds are stacked floor to ceiling along kilometers of catacombs, totaling many millions of birds. But how the Egyptians got access to so many birds has been a mystery; some ancient texts indicate that long-term farming and domestication may have been employed.
In this study, Wasef and colleagues collected DNA from 40 mummified Sacred Ibis specimens from six Egyptian catacombs dating to around 2500 years ago and 26 modern specimens from across Africa. 14 of the mummies and all of the modern specimens yielded complete mitochondrial genome sequences. These data allowed the researchers to compare genetic diversity between wild populations and the sacrificed collections.
If the birds were being domesticated and farmed, the expected result would be low genetic diversity due to interbreeding of restricted populations, but in contrast, this study found that the genetic diversity of mummified Ibises within and between catacombs was similar to that of modern wild populations. This suggests that the birds were not the result of centralized farming, but instead short-term taming. The authors suggest the birds were likely tended in their natural habitats or perhaps farmed only in the times of year they were needed for sacrifice.
The authors add: "We report the first complete ancient genomes of the Egyptian Sacred Ibis mummies, showing that priests sustained short-term taming of the wild Sacred Ibis in local lakes or wetlands contrary to centralised industrial scale farming of sacrificial birds."
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Materials provided by PLOS. Note: Content may be edited for style and length.
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