The second release of data from Gaia star-mapping satellite, published in 2018, has been revolutionising many fields of astronomy. The unprecedented catalogue contains the brightness, positions, distance indicators and motions across the sky for more than one billion stars in our Milky Way galaxy, along with information about other celestial bodies.
This is just the beginning. While the second release is based on the first twenty-two months of Gaia's surveys, the satellite has been scanning the sky for five years, and will keep doing so at least until 2022. New data releases planned in coming years will steadily improve measurements as well as provide extra information that will enable us to chart our home galaxy and delve into its history like never before.
Meanwhile, a team of astronomers have combined the latest Gaia data with infrared and optical observations performed from ground and space to provide a preview of what future releases of ESA's stellar surveyor will reveal.
"We looked in particular at two of the stellar parameters contained in the Gaia data: the surface temperature of stars and the 'extinction', which is basically a measure of how much dust there is between us and the stars, obscuring their light and making it appear redder," says Friedrich Anders ICCUB member and lead author of the new study.
"These two parameters are interconnected, but we can estimate them independently by adding extra information obtained by peering through the dust with infrared observations," continues the expert.
The team combined the second Gaia data release with several infrared surveys using a computer code called StarHorse, developed by co-author Anna Queiroz and other collaborators. The code compares the observations with stellar models to determine the surface temperature of stars, the extinction and an improved estimate of the distance to the stars.
As a result, the astronomers obtained much better determination of the distances to about 150 million stars -- in some cases, the improvement is up to 20% or more. This enabled them to trace the distribution of stars across the Milky Way to much greater distances than possible with the original Gaia data alone.
"With the second Gaia data release, we could probe a radius around the Sun of about 6500 light years, but with our new catalogue, we can extend this 'Gaia sphere' by three or four times, reaching out to the centre of the Milky Way," explains co-author Cristina Chiappini from Leibniz Institute for Astrophysics Potsdam, Germany, where the project was coordinated. At the centre of our galaxy, the data clearly reveals a large, elongated feature in the three-dimensional distribution of stars: the galactic bar.
"We know the Milky Way has a bar, like other barred spiral galaxies, but so far we only had indirect indications from the motions of stars and gas, or from star counts in infrared surveys. This is the first time that we see the galactic bar in three-dimensional space, based on geometric measurements of stellar distances," says Friedrich Anders.
"Ultimately, we are interested in galactic archaeology: we want to reconstruct how the Milky Way formed and evolved, and to do so we have to understand the history of each and every one of its components," adds Cristina Chiappini.
"It is still unclear how the bar -- a large amount of stars and gas rotating rigidly around the centre of the galaxy -- formed, but with Gaia and other upcoming surveys in the next years we are certainly on the right path to figure it out," notes the researcher.
The team is looking forward to the next data release from the Apache Point Observatory Galaxy Evolution Experiment (APOGEE-2), as well as upcoming facilities such as the 4-metre Multi-Object Survey Telescope (4MOST) at the European Southern Observatory in Chile and the WEAVE (WHT Enhanced Area Velocity Explorer) survey at the William Herschel Telescope (WHT) in La Palma (Canary Islands).
The third Gaia data release, currently planned for 2021, will include greatly improved distance determinations for a much larger number of stars, and is expected to enable progress in our understanding of the complex region at the centre of the Milky Way.
"With this study, we can enjoy a taster of the improvements in our knowledge of the Milky Way that can be expected from Gaia measurements in the third data release," explains co-author Anthony Brown of Leiden University (the Netherlands).
Read more at Science Daily
Jul 16, 2019
Breakthrough material could lead to cheaper, more widespread solar panels and electronics
Imagine printing electronic devices using a simple inkjet printer -- or even painting a solar panel onto the wall of a building.
Such technology would slash the cost of manufacturing electronic devices and enable new ways to integrate them into our everyday lives. Over the last two decades, a type of material called organic semiconductors, made out of molecules or polymers, has been developed for such purposes. But some properties of these materials pose a major hurdle that limits their widespread use.
"In these materials, an electron is usually bound to its counterpart, a missing electron known as 'hole,' and can't move freely," said Wai-Lun Chan, associate professor of physics & astronomy at the University of Kansas. "So-called 'free electrons,' which wander freely in the material and conduct electricity, are rare and can't be generated readily by light absorption. This impedes the use of these organic materials in applications like solar panels because panels built with these materials often have poor performance."
Because of this problem, Chan said "freeing the electrons" has been a focus in developing organic semiconductors for solar cells, light sensors and many other optoelectronic applications.
Now, two physics research groups at KU, led by Chan and Hui Zhao, professor of physics & astronomy, have effectively generated free electrons from organic semiconductors when combined with a single atomic layer of molybdenum disulfide (MoS2), a recently discovered two-dimensional (2D) semiconductor.
The introduced 2D layer allows the electrons to escape from "holes" and move freely. The findings have just been published in the Journal of American Chemical Society, a leading journal in chemistry and interfacing areas of science.
Over the last few years, many researchers have been investigating how free charges can be generated effectively from hybrid organic-2D interfaces.
"One of the prevailing assumptions is free electrons can be generated from the interface as long as electrons can be transferred from one material to another in a relatively short period of time -- less than one-trillionth of a second," Chan said. "However, my graduate students Tika Kafle and Bhupal Kattel and I have found the presence of the ultrafast electron transfer in itself is not sufficient to guarantee the generation of free electrons from the light absorption. That's because the 'holes' can prevent the electrons from moving away from the interface. Whether the electron can be free from this binding force depends on the local energy landscape near the interface."
Chan said the energy landscape of the electrons could be seen as a topographic map of a mountain.
"A hiker chooses his path based on the height contour map," he said. "Similarly, the motion of the electron at the interface between the two materials is controlled by the electron energy landscape near the interface."
Chan and Zhao's findings will help develop general principles of how to design the "landscape" to free the electrons in such hybrid materials.
The discovery was made by combining two highly complementary experimental tools based on ultrafast lasers, time-resolved photoemission spectroscopy in Chan's lab and transient optical absorption in Zhao's lab. Both experimental setups are located in the basement of the Integrated Science Building.
In the time-resolved photoemission spectroscopy experiment, Kafle used an ultrashort laser pulse that only exists for 10-quadrillionths (10-14) of a second to trigger the motion of electrons. The advantage of using such a short pulse is the researcher knows precisely the starting time of the electron's journey. Kafle then used another ultrashort laser pulse to hit the sample again at an accurately controlled time relative to the first pulse. This second pulse is energetic enough to kick out these electrons from the sample. By measuring the energy of these electrons (now in a vacuum) and using the principle of energy conservation, the researchers were able to figure out the energy of electrons before they were kicked out and thus reveal the journey of these electrons since they were hit by the first pulse. This technique resolved the energy of the excited electrons as it moves across the interface after the light absorption. Because only electrons near the front surface of the sample can be released by the second pulse, the position of the electron relative to the interface is also revealed with atomic precision.
In the transient optical absorption measurements, Peng Yao (a visiting student) and KU graduate Peymon Zereshki, both supervised by Zhao, also used a two-pulse technique, with the first pulse initiating the electron motion in the same way. However, in their measurements, the second pulse does the trick of monitoring electrons by detecting the fraction of the second pulse that is reflected from the sample, instead of kicking out the electrons.
Read more at Science Daily
Such technology would slash the cost of manufacturing electronic devices and enable new ways to integrate them into our everyday lives. Over the last two decades, a type of material called organic semiconductors, made out of molecules or polymers, has been developed for such purposes. But some properties of these materials pose a major hurdle that limits their widespread use.
"In these materials, an electron is usually bound to its counterpart, a missing electron known as 'hole,' and can't move freely," said Wai-Lun Chan, associate professor of physics & astronomy at the University of Kansas. "So-called 'free electrons,' which wander freely in the material and conduct electricity, are rare and can't be generated readily by light absorption. This impedes the use of these organic materials in applications like solar panels because panels built with these materials often have poor performance."
Because of this problem, Chan said "freeing the electrons" has been a focus in developing organic semiconductors for solar cells, light sensors and many other optoelectronic applications.
Now, two physics research groups at KU, led by Chan and Hui Zhao, professor of physics & astronomy, have effectively generated free electrons from organic semiconductors when combined with a single atomic layer of molybdenum disulfide (MoS2), a recently discovered two-dimensional (2D) semiconductor.
The introduced 2D layer allows the electrons to escape from "holes" and move freely. The findings have just been published in the Journal of American Chemical Society, a leading journal in chemistry and interfacing areas of science.
Over the last few years, many researchers have been investigating how free charges can be generated effectively from hybrid organic-2D interfaces.
"One of the prevailing assumptions is free electrons can be generated from the interface as long as electrons can be transferred from one material to another in a relatively short period of time -- less than one-trillionth of a second," Chan said. "However, my graduate students Tika Kafle and Bhupal Kattel and I have found the presence of the ultrafast electron transfer in itself is not sufficient to guarantee the generation of free electrons from the light absorption. That's because the 'holes' can prevent the electrons from moving away from the interface. Whether the electron can be free from this binding force depends on the local energy landscape near the interface."
Chan said the energy landscape of the electrons could be seen as a topographic map of a mountain.
"A hiker chooses his path based on the height contour map," he said. "Similarly, the motion of the electron at the interface between the two materials is controlled by the electron energy landscape near the interface."
Chan and Zhao's findings will help develop general principles of how to design the "landscape" to free the electrons in such hybrid materials.
The discovery was made by combining two highly complementary experimental tools based on ultrafast lasers, time-resolved photoemission spectroscopy in Chan's lab and transient optical absorption in Zhao's lab. Both experimental setups are located in the basement of the Integrated Science Building.
In the time-resolved photoemission spectroscopy experiment, Kafle used an ultrashort laser pulse that only exists for 10-quadrillionths (10-14) of a second to trigger the motion of electrons. The advantage of using such a short pulse is the researcher knows precisely the starting time of the electron's journey. Kafle then used another ultrashort laser pulse to hit the sample again at an accurately controlled time relative to the first pulse. This second pulse is energetic enough to kick out these electrons from the sample. By measuring the energy of these electrons (now in a vacuum) and using the principle of energy conservation, the researchers were able to figure out the energy of electrons before they were kicked out and thus reveal the journey of these electrons since they were hit by the first pulse. This technique resolved the energy of the excited electrons as it moves across the interface after the light absorption. Because only electrons near the front surface of the sample can be released by the second pulse, the position of the electron relative to the interface is also revealed with atomic precision.
In the transient optical absorption measurements, Peng Yao (a visiting student) and KU graduate Peymon Zereshki, both supervised by Zhao, also used a two-pulse technique, with the first pulse initiating the electron motion in the same way. However, in their measurements, the second pulse does the trick of monitoring electrons by detecting the fraction of the second pulse that is reflected from the sample, instead of kicking out the electrons.
Read more at Science Daily
Maternal secrets of our earliest ancestors unlocked
Extended parental care is considered one of the hallmarks of human evolution. A stunning new research result published today in Nature reveals for the first time the parenting habits of one of our earliest extinct ancestors.
Analysis of more than two-million-year-old teeth from Australopithecus africanus fossils found in South Africa have revealed that infants were breastfed continuously from birth to about one year of age. Nursing appears to continue in a cyclical pattern in the early years for infants; seasonal changes and food shortages caused the mother to supplement gathered foods with breastmilk. An international research team led by Dr Renaud Joannes-Boyau of Southern Cross University, and by Dr Luca Fiorenza and Dr Justin W. Adams from Monash University, published the details of their research into the species in Nature today.
"For the first time, we gained new insight into the way our ancestors raised their young, and how mothers had to supplement solid food intake with breastmilk when resources were scarce," said geochemist Dr Joannes-Boyau from the Geoarchaeology and Archaeometry Research Group (GARG) at Southern Cross University.
"These finds suggest for the first time the existence of a long-lasting mother-infant bond in Australopithecus. This makes us to rethink on the social organisations among our earliest ancestors," said Dr Fiorenza, who is an expert in the evolution of human diet at the Monash Biomedicine Discovery Institute (BDI).
"Fundamentally, our discovery of a reliance by Australopithecus africanus mothers to provide nutritional supplementation for their offspring and use of fallback resources highlights the survival challenges that populations of early human ancestors faced in the past environments of South Africa," said Dr Adams, an expert in hominin palaeoecology and South African sites at the Monash BDI.
For decades there has been speculation about how early ancestors raised their offspring. With this study, the research team has opened a new window into our enigmatic evolutionary history.
Australopithecus africanus lived from about two to three million years ago during a period of major climatic and ecological change in South Africa, and the species was characterised by a combination of human-like and retained ape-like traits. While the first fossils of Australopithecus were found almost a century ago, scientists have only now been able to unlock the secrets of how they raised their young, using specialised laser sampling techniques to vaporise microscopic portions on the surface of the tooth. The gas containing the sample is then analysed for chemical signatures with a mass spectrometer- enabling researchers to develop microscopic geochemical maps which can tell the story of the diet and health of an individual over time. Dr Joannes-Boyau conducted the analyses at the Geoarchaeology and Archaeometry Research Group at Southern Cross University in Lismore NSW and at the Icahn School of Medicine at Mount Sinai in New York.
Teeth grow similarly to trees; they form by adding layer after layer of enamel and dentine tissues every day. Thus, teeth are particularly valuable for reconstructing the biological events occurring during the early period of life of an individual, simply because they preserve precise temporal changes and chemical records of key elements incorporated in the food we eat.
By developing micro geochemical maps, we are able to 'read' successive bands of daily signal in teeth, which provide insights into food consumption and stages of life. Previously the team had revealed the nursing behaviour of our closest evolutionary relatives, the Neanderthals. With this latest study, the international team has analysed teeth that are more than ten times older than those of Neanderthals.
"We can tell from the repetitive bands that appear as the tooth developed that the fall back food was high in lithium, which is believed to be a mechanism to reduce protein deficiency in infants more prone to adverse effect during growth periods," Dr Joannes-Boyau said.
"This likely reduced the potential number of offspring, because of the length of time infants relied on a supply of breastmilk. The strong bond between mothers and offspring for a number of years has implications for group dynamics, the social structure of the species, relationships between mother and infant and the priority that had to be placed on maintaining access to reliable food supplies," he said.
"This finding underscores the diversity, variability and flexibility in habitats and adaptive strategies these australopiths used to obtain food, avoid predators, and raise their offspring," Dr Adams emphasised.
"This is the first direct proof of maternal roles of one of our earliest ancestors and contributes to our understanding of the history of family dynamics and childhood," concluded Dr Fiorenza.
Read more at Science Daily
Analysis of more than two-million-year-old teeth from Australopithecus africanus fossils found in South Africa have revealed that infants were breastfed continuously from birth to about one year of age. Nursing appears to continue in a cyclical pattern in the early years for infants; seasonal changes and food shortages caused the mother to supplement gathered foods with breastmilk. An international research team led by Dr Renaud Joannes-Boyau of Southern Cross University, and by Dr Luca Fiorenza and Dr Justin W. Adams from Monash University, published the details of their research into the species in Nature today.
"For the first time, we gained new insight into the way our ancestors raised their young, and how mothers had to supplement solid food intake with breastmilk when resources were scarce," said geochemist Dr Joannes-Boyau from the Geoarchaeology and Archaeometry Research Group (GARG) at Southern Cross University.
"These finds suggest for the first time the existence of a long-lasting mother-infant bond in Australopithecus. This makes us to rethink on the social organisations among our earliest ancestors," said Dr Fiorenza, who is an expert in the evolution of human diet at the Monash Biomedicine Discovery Institute (BDI).
"Fundamentally, our discovery of a reliance by Australopithecus africanus mothers to provide nutritional supplementation for their offspring and use of fallback resources highlights the survival challenges that populations of early human ancestors faced in the past environments of South Africa," said Dr Adams, an expert in hominin palaeoecology and South African sites at the Monash BDI.
For decades there has been speculation about how early ancestors raised their offspring. With this study, the research team has opened a new window into our enigmatic evolutionary history.
Australopithecus africanus lived from about two to three million years ago during a period of major climatic and ecological change in South Africa, and the species was characterised by a combination of human-like and retained ape-like traits. While the first fossils of Australopithecus were found almost a century ago, scientists have only now been able to unlock the secrets of how they raised their young, using specialised laser sampling techniques to vaporise microscopic portions on the surface of the tooth. The gas containing the sample is then analysed for chemical signatures with a mass spectrometer- enabling researchers to develop microscopic geochemical maps which can tell the story of the diet and health of an individual over time. Dr Joannes-Boyau conducted the analyses at the Geoarchaeology and Archaeometry Research Group at Southern Cross University in Lismore NSW and at the Icahn School of Medicine at Mount Sinai in New York.
Teeth grow similarly to trees; they form by adding layer after layer of enamel and dentine tissues every day. Thus, teeth are particularly valuable for reconstructing the biological events occurring during the early period of life of an individual, simply because they preserve precise temporal changes and chemical records of key elements incorporated in the food we eat.
By developing micro geochemical maps, we are able to 'read' successive bands of daily signal in teeth, which provide insights into food consumption and stages of life. Previously the team had revealed the nursing behaviour of our closest evolutionary relatives, the Neanderthals. With this latest study, the international team has analysed teeth that are more than ten times older than those of Neanderthals.
"We can tell from the repetitive bands that appear as the tooth developed that the fall back food was high in lithium, which is believed to be a mechanism to reduce protein deficiency in infants more prone to adverse effect during growth periods," Dr Joannes-Boyau said.
"This likely reduced the potential number of offspring, because of the length of time infants relied on a supply of breastmilk. The strong bond between mothers and offspring for a number of years has implications for group dynamics, the social structure of the species, relationships between mother and infant and the priority that had to be placed on maintaining access to reliable food supplies," he said.
"This finding underscores the diversity, variability and flexibility in habitats and adaptive strategies these australopiths used to obtain food, avoid predators, and raise their offspring," Dr Adams emphasised.
"This is the first direct proof of maternal roles of one of our earliest ancestors and contributes to our understanding of the history of family dynamics and childhood," concluded Dr Fiorenza.
Read more at Science Daily
Australian bee sting vaccine trial holds promise against allergic reactions
Most people have probably been stung by a bee and while it can be painful, it's especially dangerous for the many that are at risk of suffering a life threatening allergic reaction.
Australian researchers have successfully completed a human trial on a vaccine designed to eliminate the risk of a severe allergic reaction to European honeybee stings.
The clinical trial at Flinders University and the Royal Adelaide Hospital included 27 adults with a history of allergic reactions to bee stings.
The vaccine used in the trial contained a unique sugar-based ingredient called an adjuvant, developed in Australia, which is designed to help the body neutralise the bee venom at a faster rate.
Professor Nikolai Petrovsky says the adjuvant used to enhance the bee sting vaccines has now been successfully given to over a thousand individuals across a range of different vaccines including in the current bee sting allergy trial.
"Our technology is like adding a turbocharger to a car and in this case makes the bee allergy vaccine much more powerful, allowing the immune system to better neutralise the bee venom and prevent allergic symptoms," says Professor Petrovsky.
Associate Professor Robert Heddle, lead investigator in the trial, says the aim was to see if the Advax adjuvant would safely speed up and improve bee sting immunotherapy.
"The results of the study were very promising and confirmed the safety of this approach to improving bee sting immunotherapy."
Dr Anthony Smith, an investigator in the trial, says while a commercial bee venom therapy is already available, it requires patients to have over 50 injections over a 3 year period to build up their immune system.
"The current treatment option for serious bee venom allergies is lengthy and cumbersome, so I hope this enhanced bee venom therapy brings about faster, but longer lasting protection to bee stings for allergic individuals."
The Advax adjuvant which enhances the bee sting vaccines was developed in Adelaide by Vaxine Pty Ltd and has also been used to develop vaccines for seasonal and pandemic influenza, hepatitis, malaria, Alzheimers disease, cancer and other diseases.
From Science Daily
Australian researchers have successfully completed a human trial on a vaccine designed to eliminate the risk of a severe allergic reaction to European honeybee stings.
The clinical trial at Flinders University and the Royal Adelaide Hospital included 27 adults with a history of allergic reactions to bee stings.
The vaccine used in the trial contained a unique sugar-based ingredient called an adjuvant, developed in Australia, which is designed to help the body neutralise the bee venom at a faster rate.
Professor Nikolai Petrovsky says the adjuvant used to enhance the bee sting vaccines has now been successfully given to over a thousand individuals across a range of different vaccines including in the current bee sting allergy trial.
"Our technology is like adding a turbocharger to a car and in this case makes the bee allergy vaccine much more powerful, allowing the immune system to better neutralise the bee venom and prevent allergic symptoms," says Professor Petrovsky.
Associate Professor Robert Heddle, lead investigator in the trial, says the aim was to see if the Advax adjuvant would safely speed up and improve bee sting immunotherapy.
"The results of the study were very promising and confirmed the safety of this approach to improving bee sting immunotherapy."
Dr Anthony Smith, an investigator in the trial, says while a commercial bee venom therapy is already available, it requires patients to have over 50 injections over a 3 year period to build up their immune system.
"The current treatment option for serious bee venom allergies is lengthy and cumbersome, so I hope this enhanced bee venom therapy brings about faster, but longer lasting protection to bee stings for allergic individuals."
The Advax adjuvant which enhances the bee sting vaccines was developed in Adelaide by Vaxine Pty Ltd and has also been used to develop vaccines for seasonal and pandemic influenza, hepatitis, malaria, Alzheimers disease, cancer and other diseases.
From Science Daily
Jul 15, 2019
Healthy lifestyle may offset genetic risk of dementia
Living a healthy lifestyle may help offset a person's genetic risk of dementia, according to new research.
The study was led by the University of Exeter -- simultaneously published today in JAMA and presented at the Alzheimer's Association International Conference 2019 in Los Angeles. The research found that the risk of dementia was 32 per cent lower in people with a high genetic risk if they had followed a healthy lifestyle, compared to those who had an unhealthy lifestyle.
Participants with high genetic risk and an unfavourable lifestyle were almost three times more likely to develop dementia compared to those with a low genetic risk and favourable lifestyle.
Joint lead author Dr El?bieta Ku?ma, at the University of Exeter Medical School, said: "This is the first study to analyse the extent to which you may offset your genetic risk of dementia by living a healthy lifestyle. Our findings are exciting as they show that we can take action to try to offset our genetic risk for dementia. Sticking to a healthy lifestyle was associated with a reduced risk of dementia, regardless of the genetic risk."
The study analysed data from 196,383 adults of European ancestry aged 60 and older from UK Biobank. The researchers identified 1,769 cases of dementia over a follow-up period of eight years. The team grouped the participants into those with high, intermediate and low genetic risk for dementia.
To assess genetic risk, the researchers looked at previously published data and identified all known genetic risk factors for Alzheimer's disease. Each genetic risk factor was weighted according to the strength of its association with Alzheimer's disease.
To assess lifestyle, researchers grouped participants into favourable, intermediate and unfavourable categories based on their self-reported diet, physical activity, smoking and alcohol consumption. The researchers considered no current smoking, regular physical activity, healthy diet and moderate alcohol consumption as healthy behaviours. The team found that living a healthy lifestyle was associated with a reduced dementia risk across all genetic risk groups.
Joint lead author Dr David Llewellyn, from the University of Exeter Medical School and the Alan Turing Institute, said: "This research delivers a really important message that undermines a fatalistic view of dementia. Some people believe it's inevitable they'll develop dementia because of their genetics. However it appears that you may be able to substantially reduce your dementia risk by living a healthy lifestyle."
Read more at Science Daily
The study was led by the University of Exeter -- simultaneously published today in JAMA and presented at the Alzheimer's Association International Conference 2019 in Los Angeles. The research found that the risk of dementia was 32 per cent lower in people with a high genetic risk if they had followed a healthy lifestyle, compared to those who had an unhealthy lifestyle.
Participants with high genetic risk and an unfavourable lifestyle were almost three times more likely to develop dementia compared to those with a low genetic risk and favourable lifestyle.
Joint lead author Dr El?bieta Ku?ma, at the University of Exeter Medical School, said: "This is the first study to analyse the extent to which you may offset your genetic risk of dementia by living a healthy lifestyle. Our findings are exciting as they show that we can take action to try to offset our genetic risk for dementia. Sticking to a healthy lifestyle was associated with a reduced risk of dementia, regardless of the genetic risk."
The study analysed data from 196,383 adults of European ancestry aged 60 and older from UK Biobank. The researchers identified 1,769 cases of dementia over a follow-up period of eight years. The team grouped the participants into those with high, intermediate and low genetic risk for dementia.
To assess genetic risk, the researchers looked at previously published data and identified all known genetic risk factors for Alzheimer's disease. Each genetic risk factor was weighted according to the strength of its association with Alzheimer's disease.
To assess lifestyle, researchers grouped participants into favourable, intermediate and unfavourable categories based on their self-reported diet, physical activity, smoking and alcohol consumption. The researchers considered no current smoking, regular physical activity, healthy diet and moderate alcohol consumption as healthy behaviours. The team found that living a healthy lifestyle was associated with a reduced dementia risk across all genetic risk groups.
Joint lead author Dr David Llewellyn, from the University of Exeter Medical School and the Alan Turing Institute, said: "This research delivers a really important message that undermines a fatalistic view of dementia. Some people believe it's inevitable they'll develop dementia because of their genetics. However it appears that you may be able to substantially reduce your dementia risk by living a healthy lifestyle."
Read more at Science Daily
Warming climate intensifes summer drought in parts of US
Climate change is amplifying the intensity and likelihood of heatwaves during severe droughts in the southern plains and southwest United States, according to a new study by a University of Arkansas researcher.
Linyin Cheng, assistant professor of geosciences, used data from the National Center for Atmospheric Research's Community Earth System Model to study summer droughts that occurred both before and after the Industrial Revolution. Cheng and colleagues from the National Oceanic and Atmospheric Administration and universities in China and Colorado ran simulations to assess how, and by how much, human-induced climate change affects summer heatwaves in the contiguous United States. The study was published in the Journal of Climate.
The researchers found that in places with low moisture in the soil, such as the southern plains and southwest, higher temperatures brought about by climate change led to an increased "coupling" of land and atmosphere, which further increased the severity of heatwaves. In places with more moisture in the soil, such as the northeast, they found no appreciable coupling and therefore no contribution to heatwave intensification.
"Our analysis of climate simulation finds that summertime drought-heatwave relationships change significantly over the southern and southwest U.S. due to human-made climate change since the late 19th century," said Cheng. "By contrast, the drought-heatwave relationship over northern U.S regions undergoes little change in the warmed climate."
The findings raise the idea of a self-reinforcing climate loop: as a region's climate becomes more arid due to climate change, droughts become hotter, further reducing soil moisture.
"Overall, these results indicate that strengthened land-atmosphere feedback is a significant physical driver for increasing occurrences of drought-related extreme heatwaves, particularly over the semi-arid and arid regions of the United States," the report states.
From Science Daily
Linyin Cheng, assistant professor of geosciences, used data from the National Center for Atmospheric Research's Community Earth System Model to study summer droughts that occurred both before and after the Industrial Revolution. Cheng and colleagues from the National Oceanic and Atmospheric Administration and universities in China and Colorado ran simulations to assess how, and by how much, human-induced climate change affects summer heatwaves in the contiguous United States. The study was published in the Journal of Climate.
The researchers found that in places with low moisture in the soil, such as the southern plains and southwest, higher temperatures brought about by climate change led to an increased "coupling" of land and atmosphere, which further increased the severity of heatwaves. In places with more moisture in the soil, such as the northeast, they found no appreciable coupling and therefore no contribution to heatwave intensification.
"Our analysis of climate simulation finds that summertime drought-heatwave relationships change significantly over the southern and southwest U.S. due to human-made climate change since the late 19th century," said Cheng. "By contrast, the drought-heatwave relationship over northern U.S regions undergoes little change in the warmed climate."
The findings raise the idea of a self-reinforcing climate loop: as a region's climate becomes more arid due to climate change, droughts become hotter, further reducing soil moisture.
"Overall, these results indicate that strengthened land-atmosphere feedback is a significant physical driver for increasing occurrences of drought-related extreme heatwaves, particularly over the semi-arid and arid regions of the United States," the report states.
From Science Daily
Quantum logic clock returns to top performance
The quantum logic clock -- perhaps best known for showing you age faster if you stand on a stool -- has climbed back to the leading performance echelons of the world's experimental atomic clocks.
Physicists at the National Institute of Standards and Technology (NIST) have been quietly upgrading their quantum logic clock design for the past eight years, mainly to reduce errors from unwanted motion of the single aluminum ion (electrically charged atom) that provides the clock "ticks."
As described in Physical Review Letters, the quantum logic clock's systematic uncertainty (how closely the clock represents the ion's natural vibrations, or frequency) is 9.5×10−19, the best of any clock worldwide. This means the logic clock would now neither gain nor lose one second in 33 billion years, which is about two-and-a-half times the estimated age of the universe.
In this metric, it now outpaces both NIST clocks using neutral atoms trapped in lattices of laser beams, the ytterbium lattice clock and the strontium lattice clock.
"The logic clock's performance is not surprising to me," project leader David Leibrandt said. "Ion clocks are naturally better isolated from the environment -- which is the source of inaccuracy for atomic clocks -- than lattice clocks are. It's important to distinguish between precision and stability on this point. People expect that lattice clocks should perform the best in stability, and they currently do. Our newest quantum logic clock is the world leader in precision but not stability."
The logic clock's stability (how long it takes to measure the time) is 1.2×10−15 for a 1-second measurement, which is near the best achieved by a single ion clock but about 10 times worse than both NIST lattice clocks.
The quantum logic clock got its nickname because it borrows logical decision-making techniques from experimental quantum computing. Aluminum is an exceptionally stable source of clock ticks, vibrating between two energy levels over a million billion times per second, but its properties are not easily manipulated or detected with lasers. So, logic operations with a partner magnesium ion are used to cool the aluminum and to signal its ticks.
Back in 2010, NIST's quantum logic clock had the best performance of any experimental atomic clock. The clock also attracted attention for 2010 demonstrations of "time dilation" aspects of Einstein's theories of relativity: that time passes faster at higher elevations but more slowly when you move faster.
Since then, NIST's lattice clocks have been continually leapfrogging each other in performance, giving the impression of a race to identify a single winner. In fact, all the clocks are useful for research purposes and are possible contenders for future time standards or other applications.
The international definition of the second (in the International System of Units, or SI) has been based on the cesium atom since 1967, so cesium remains the "ruler" for official timekeeping. The logic clock is one contender for a future time standard to be selected by the international scientific community. NIST scientists are working on several different types of experimental clocks, each based on different atoms and offering its own advantages. All these experimental clocks are based on optical frequencies, which are higher than the microwave frequencies used in today's timekeeping standards based on cesium.
Several technical advances enabled the improved performance of the logic clock, including a new ion trap design that reduced heat-induced ion motion, enabling operation near the desirable ground state, or lowest motional energy level. In addition, a lower frequency was used to operate the ion trap, reducing unwanted ion motion caused by the electric field used to trap the ions. Finally, improved quantum control has reduced the uncertainty of measurements of frequency shifts due to ion motion.
The clock's precision was determined by measuring and adding up the frequency shifts caused by nine different effects. Stability was measured by comparison to NIST's ytterbium lattice clock.
Read more at Science Daily
Physicists at the National Institute of Standards and Technology (NIST) have been quietly upgrading their quantum logic clock design for the past eight years, mainly to reduce errors from unwanted motion of the single aluminum ion (electrically charged atom) that provides the clock "ticks."
As described in Physical Review Letters, the quantum logic clock's systematic uncertainty (how closely the clock represents the ion's natural vibrations, or frequency) is 9.5×10−19, the best of any clock worldwide. This means the logic clock would now neither gain nor lose one second in 33 billion years, which is about two-and-a-half times the estimated age of the universe.
In this metric, it now outpaces both NIST clocks using neutral atoms trapped in lattices of laser beams, the ytterbium lattice clock and the strontium lattice clock.
"The logic clock's performance is not surprising to me," project leader David Leibrandt said. "Ion clocks are naturally better isolated from the environment -- which is the source of inaccuracy for atomic clocks -- than lattice clocks are. It's important to distinguish between precision and stability on this point. People expect that lattice clocks should perform the best in stability, and they currently do. Our newest quantum logic clock is the world leader in precision but not stability."
The logic clock's stability (how long it takes to measure the time) is 1.2×10−15 for a 1-second measurement, which is near the best achieved by a single ion clock but about 10 times worse than both NIST lattice clocks.
The quantum logic clock got its nickname because it borrows logical decision-making techniques from experimental quantum computing. Aluminum is an exceptionally stable source of clock ticks, vibrating between two energy levels over a million billion times per second, but its properties are not easily manipulated or detected with lasers. So, logic operations with a partner magnesium ion are used to cool the aluminum and to signal its ticks.
Back in 2010, NIST's quantum logic clock had the best performance of any experimental atomic clock. The clock also attracted attention for 2010 demonstrations of "time dilation" aspects of Einstein's theories of relativity: that time passes faster at higher elevations but more slowly when you move faster.
Since then, NIST's lattice clocks have been continually leapfrogging each other in performance, giving the impression of a race to identify a single winner. In fact, all the clocks are useful for research purposes and are possible contenders for future time standards or other applications.
The international definition of the second (in the International System of Units, or SI) has been based on the cesium atom since 1967, so cesium remains the "ruler" for official timekeeping. The logic clock is one contender for a future time standard to be selected by the international scientific community. NIST scientists are working on several different types of experimental clocks, each based on different atoms and offering its own advantages. All these experimental clocks are based on optical frequencies, which are higher than the microwave frequencies used in today's timekeeping standards based on cesium.
Several technical advances enabled the improved performance of the logic clock, including a new ion trap design that reduced heat-induced ion motion, enabling operation near the desirable ground state, or lowest motional energy level. In addition, a lower frequency was used to operate the ion trap, reducing unwanted ion motion caused by the electric field used to trap the ions. Finally, improved quantum control has reduced the uncertainty of measurements of frequency shifts due to ion motion.
The clock's precision was determined by measuring and adding up the frequency shifts caused by nine different effects. Stability was measured by comparison to NIST's ytterbium lattice clock.
Read more at Science Daily
A material way to make Mars habitable
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| Mars north pole illustration |
Sagan's work inspired other researchers and futurists to take seriously the idea of terraforming. The key question was: are there enough greenhouse gases and water on Mars to increase its atmospheric pressure to Earth-like levels?
In 2018, a pair of NASA-funded researchers from the University of Colorado, Boulder and Northern Arizona University found that processing all the sources available on Mars would only increase atmospheric pressure to about 7 percent that of Earth - far short of what is needed to make the planet habitable.
Terraforming Mars, it seemed, was an unfulfillable dream.
Now, researchers from the Harvard University, NASA's Jet Propulsion Lab, and the University of Edinburgh, have a new idea. Rather than trying to change the whole planet, what if you took a more regional approach?
The researchers suggest that regions of the Martian surface could be made habitable with a material -- silica aerogel -- that mimics Earth's atmospheric greenhouse effect. Through modeling and experiments, the researchers show that a two to three-centimeter-thick shield of silica aerogel could transmit enough visible light for photosynthesis, block hazardous ultraviolet radiation, and raise temperatures underneath permanently above the melting point of water, all without the need for any internal heat source.
The paper is published in Nature Astronomy.
"This regional approach to making Mars habitable is much more achievable than global atmospheric modification," said Robin Wordsworth, Assistant Professor of Environmental Science and Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Department of Earth and Planetary Science. "Unlike the previous ideas to make Mars habitable, this is something that can be developed and tested systematically with materials and technology we already have."
"Mars is the most habitable planet in our Solar System besides Earth," said Laura Kerber, Research Scientist at NASA's Jet Propulsion Laboratory. "But it remains a hostile world for many kinds of life. A system for creating small islands of habitability would allow us to transform Mars in a controlled and scalable way."
The researchers were inspired by a phenomenon that already occurs on Mars.
Unlike Earth's polar ice caps, which are made of frozen water, polar ice caps on Mars are a combination of water ice and frozen CO2. Like its gaseous form, frozen CO2 allows sunlight to penetrate while trapping heat. In the summer, this solid-state greenhouse effect creates pockets of warming under the ice.
"We started thinking about this solid-state greenhouse effect and how it could be invoked for creating habitable environments on Mars in the future," said Wordsworth. "We started thinking about what kind of materials could minimize thermal conductivity but still transmit as much light as possible."
The researchers landed on silica aerogel, one of the most insulating materials ever created.
Silica aerogels are 97 percent porous, meaning light moves through the material but the interconnecting nanolayers of silicon dioxide infrared radiation and greatly slow the conduction of heat. These aerogels are used in several engineering applications today, including NASA's Mars Exploration Rovers.
"Silica aerogel is a promising material because its effect is passive," said Kerber. "It wouldn't require large amounts of energy or maintenance of moving parts to keep an area warm over long periods of time."
Using modeling and experiments that mimicked the Martian surface, the researchers demonstrated that a thin layer of this material increased average temperatures of mid-latitudes on Mars to Earth-like temperatures.
"Spread across a large enough area, you wouldn't need any other technology or physics, you would just need a layer of this stuff on the surface and underneath you would have permanent liquid water," said Wordsworth.
This material could be used to build habitation domes or even self-contained biospheres on Mars on Mars.
"There's a whole host of fascinating engineering questions that emerge from this," said Wordsworth.
Next, the team aims to test the material in Mars-like climates on Earth, such as the dry valleys of Antarctica or Chile.
Read more at Science Daily
Jul 14, 2019
Super salty, subzero Arctic water provides peek at possible life on other planets
In recent years, the idea of life on other planets has become less far-fetched. NASA announced June 27 that it will send a vehicle to Saturn's icy moon, Titan, a celestial body known to harbor surface lakes of methane and an ice-covered ocean of water, boosting its chance for supporting life.
On Earth, scientists are studying the most extreme environments to learn how life might exist under completely different settings, like on other planets. A University of Washington team has been studying the microbes found in "cryopegs," trapped layers of sediment with water so salty that it remains liquid at below-freezing temperatures, which may be similar to environments on Mars or other planetary bodies farther from the sun.
At the recent AbSciCon meeting in Bellevue, Washington, researchers presented DNA sequencing and related results to show that brine samples from an Alaskan cryopeg isolated for tens of thousands of years contain thriving bacterial communities. The lifeforms are similar to those found in floating sea ice and in saltwater that flows from glaciers, but display some unique patterns.
"We study really old seawater trapped inside of permafrost for up to 50,000 years, to see how those bacterial communities have evolved over time," said lead author Zachary Cooper, a UW doctoral student in oceanography.
Cryopegs were first discovered by geologists in Northern Alaska decades ago. This field site in Utqia?vik, formerly known as Barrow, was excavated in the 1960s by the U.S. Army's Cold Regions Research and Engineering Laboratory to explore large wedges of freshwater ice that occur in the permafrost there. Subsurface brine was eventually collected from the site in the 2000s.
"The extreme conditions here are not just the below-zero temperatures, but also the very high salt concentrations," said Jody Deming, a UW professor of oceanography who studies microbial life in the Arctic Ocean. "One hundred and forty parts per thousand -- 14% -- is a lot of salt. In canned goods that would stop microbes from doing anything. So there can be a preconceived notion that very high salt should not enable active life."
It's not fully known how cryopegs form. Scientists believe the layers might be former coastal lagoons stranded during the last ice age, when rain turned to snow and the ocean receded. Moisture evaporated from the abandoned seabed was then covered by permafrost, so the remaining briny water became trapped below a layer of frozen soil.
To access the subsurface liquids, researchers climb about 12 feet down a ladder and then move carefully along a tunnel within the ice. The opening is just a single person wide and is not high enough to stand in, so researchers must crouch and work together to drill during the four- to eight-hour shifts.
Deming describes it as "exhilarating" because of the possibility for discovery.
Samples collected in the spring of 2017 and 2018, geologically isolated for what researchers believe to be roughly 50,000 years, contain genes from healthy communities of bacteria along with their viruses.
"We're just discovering that there's a very robust microbial community, coevolving with viruses, in these ancient buried brines," Cooper said. "We were quite startled at how dense the bacterial communities are."
The extreme environments on Earth may be similar to the oceans and ice of other planets, scientist believe.
"The dominant bacterium is Marinobacter," Deming said. "The name alone tells us that it came from the ocean -- even though it has been in the dark, buried in frozen permafrost for a very long time, it originally came from the marine environment."
Mars harbored an ocean of water in the past, and our solar system contains at least a half-dozen oceans on other planets and icy moons. Titan, the moon of Saturn that NASA will explore, is rich in various forms of ice. Studying life on Earth in frozen settings that may have similarities can prepare explorers for what kind of life to expect, and how to detect it.
Read more at Science Daily
On Earth, scientists are studying the most extreme environments to learn how life might exist under completely different settings, like on other planets. A University of Washington team has been studying the microbes found in "cryopegs," trapped layers of sediment with water so salty that it remains liquid at below-freezing temperatures, which may be similar to environments on Mars or other planetary bodies farther from the sun.
At the recent AbSciCon meeting in Bellevue, Washington, researchers presented DNA sequencing and related results to show that brine samples from an Alaskan cryopeg isolated for tens of thousands of years contain thriving bacterial communities. The lifeforms are similar to those found in floating sea ice and in saltwater that flows from glaciers, but display some unique patterns.
"We study really old seawater trapped inside of permafrost for up to 50,000 years, to see how those bacterial communities have evolved over time," said lead author Zachary Cooper, a UW doctoral student in oceanography.
Cryopegs were first discovered by geologists in Northern Alaska decades ago. This field site in Utqia?vik, formerly known as Barrow, was excavated in the 1960s by the U.S. Army's Cold Regions Research and Engineering Laboratory to explore large wedges of freshwater ice that occur in the permafrost there. Subsurface brine was eventually collected from the site in the 2000s.
"The extreme conditions here are not just the below-zero temperatures, but also the very high salt concentrations," said Jody Deming, a UW professor of oceanography who studies microbial life in the Arctic Ocean. "One hundred and forty parts per thousand -- 14% -- is a lot of salt. In canned goods that would stop microbes from doing anything. So there can be a preconceived notion that very high salt should not enable active life."
It's not fully known how cryopegs form. Scientists believe the layers might be former coastal lagoons stranded during the last ice age, when rain turned to snow and the ocean receded. Moisture evaporated from the abandoned seabed was then covered by permafrost, so the remaining briny water became trapped below a layer of frozen soil.
To access the subsurface liquids, researchers climb about 12 feet down a ladder and then move carefully along a tunnel within the ice. The opening is just a single person wide and is not high enough to stand in, so researchers must crouch and work together to drill during the four- to eight-hour shifts.
Deming describes it as "exhilarating" because of the possibility for discovery.
Samples collected in the spring of 2017 and 2018, geologically isolated for what researchers believe to be roughly 50,000 years, contain genes from healthy communities of bacteria along with their viruses.
"We're just discovering that there's a very robust microbial community, coevolving with viruses, in these ancient buried brines," Cooper said. "We were quite startled at how dense the bacterial communities are."
The extreme environments on Earth may be similar to the oceans and ice of other planets, scientist believe.
"The dominant bacterium is Marinobacter," Deming said. "The name alone tells us that it came from the ocean -- even though it has been in the dark, buried in frozen permafrost for a very long time, it originally came from the marine environment."
Mars harbored an ocean of water in the past, and our solar system contains at least a half-dozen oceans on other planets and icy moons. Titan, the moon of Saturn that NASA will explore, is rich in various forms of ice. Studying life on Earth in frozen settings that may have similarities can prepare explorers for what kind of life to expect, and how to detect it.
Read more at Science Daily
Hear them roar: How humans and chickadees understand each other
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| Black-capped chickadee |
The researchers examined the elements within vocalizations that indicate a level of arousal such as fear or excitement. They found that both humans and black-capped chickadees can detect arousal levels in other species.
"The idea is that some species can understand other species' vocalizations," explained Jenna Congdon, PhD student in the Department of Psychology. "For instance, a songbird is able to understand the call of distress of a different type of songbird when they are in the presence of a predator, like an owl or a hawk. Or, for example, if your friend scared you and you screamed. Both of these are high-arousal vocalizations, and being able to understand what that sounds like in a different species can be very useful."
Sounds like it
Under the supervision of Professor Chris Sturdy, Congdon conducted two experiments, one examining chickadees and another examining humans. In the experiments, participants distinguished between high- and low-arousal vocalizations produced by other species, including alligators, chickadees, elephants, humans, pandas, piglets, ravens, macaques, and tree frogs. Human subjects were able to identify high arousal in different species.
"Black-capped chickadees were also able to identify high arousal in other chickadees, humans, and giant pandas," said Congdon. "This is fascinating, because a chickadee that has never come across a giant panda before is able to categorize high -- and low -- arousal vocalizations."
The scientists suspect that other vocal learners, or species that learn their vocalizations from parents and models in order to survive, have this ability as well. "It is only a small group of species who do this in the world -- humans, songbirds, hummingbirds, parrots, bats, whales and dolphins, and elephants," said Congdon. "If humans and songbirds show an innate ability to understand the vocalizations of other species, would other vocal learners show this same propensity?"
From Science Daily
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