Growing up in Israel, Gili Greenbaum would give tours of local caves once inhabited by Neanderthals and wonder along with others why our distant cousins abruptly disappeared about 40,000 years ago. Now a scientist at Stanford, Greenbaum thinks he has an answer.
In a new study published in the journal Nature Communications, Greenbaum and his colleagues propose that complex disease transmission patterns can explain not only how modern humans were able to wipe out Neanderthals in Europe and Asia in just a few thousand years but also, perhaps more puzzling, why the end didn't come sooner.
"Our research suggests that diseases may have played a more important role in the extinction of the Neanderthals than previously thought. They may even be the main reason why modern humans are now the only human group left on the planet," said Greenbaum, who is the first author of the study and a postdoctoral researcher in Stanford's Department of Biology.
The slow kill
Archeological evidence suggests that the initial encounter between Eurasian Neanderthals and an upstart new human species that recently strayed out of Africa -- our ancestors -- occurred more than 130,000 years ago in the Eastern Mediterranean in a region known as the Levant.
Yet tens of thousands of years would pass before Neanderthals began disappearing and modern humans expanded beyond the Levant. Why did it take so long?
Employing mathematical models of disease transmission and gene flow, Greenbaum and an international team of collaborators demonstrated how the unique diseases harbored by Neanderthals and modern humans could have created an invisible disease barrier that discouraged forays into enemy territory. Within this narrow contact zone, which was centered in the Levant where first contact took place, Neanderthals and modern humans coexisted in an uneasy equilibrium that lasted tens of millennia.
Ironically, what may have broken the stalemate and ultimately allowed our ancestors to supplant Neanderthals was the coming together of our two species through interbreeding. The hybrid humans born of these unions may have carried immune-related genes from both species, which would have slowly spread through modern human and Neanderthal populations.
As these protective genes spread, the disease burden or consequences of infection within the two groups gradually lifted. Eventually, a tipping point was reached when modern humans acquired enough immunity that they could venture beyond the Levant and deeper into Neanderthal territory with few health consequences.
At this point, other advantages that modern humans may have had over Neanderthals -- such as deadlier weapons or more sophisticated social structures -- could have taken on greater importance. "Once a certain threshold is crossed, disease burden no longer plays a role, and other factors can kick in," Greenbaum said.
Why us?
To understand why modern humans replaced Neanderthals and not the other way around, the researchers modeled what would happen if the suite of tropical diseases our ancestors harbored were deadlier or more numerous than those carried by Neanderthals.
"The hypothesis is that the disease burden of the tropics was larger than the disease burden in temperate regions. An asymmetry of disease burden in the contact zone might have favored modern humans, who arrived there from the tropics," said study co-author Noah Rosenberg, the Stanford Professor of Population Genetics and Society in the School of Humanities and Sciences.
According to the models, even small differences in disease burden between the two groups at the outset would grow over time, eventually giving our ancestors the edge. "It could be that by the time modern humans were almost entirely released from the added burden of Neanderthal diseases, Neanderthals were still very much vulnerable to modern human diseases," Greenbaum said. "Moreover, as modern humans expanded deeper into Eurasia, they would have encountered Neanderthal populations that did not receive any protective immune genes via hybridization."
The researchers note that the scenario they are proposing is similar to what happened when Europeans arrived in the Americas in the 15th and 16th centuries and decimated indigenous populations with their more potent diseases.
Read more at Science Daily
Nov 8, 2019
Unless warming is slowed, emperor penguins will be marching towards extinction
Emperor penguins are some of the most striking and charismatic animals on Earth, but a new study from the Woods Hole Oceanographic Institution (WHOI) has found that a warming climate may render them extinct by the end of this century. The study, which was part of an international collaboration between scientists, published Nov. 7, 2019, in the journal Global Change Biology.
"If global climate keeps warming at the current rate, we expect emperor penguins in Antarctica to experience an 86 percent decline by the year 2100," says Stephanie Jenouvrier, a seabird ecologist at WHOI and lead author on the paper. "At that point, it is very unlikely for them to bounce back."
The fate of the penguins is largely tied to the fate of sea ice, which the animals use as a home base for breeding and molting, she notes. Emperor penguins tend to build their colonies on ice with extremely specific conditions -- it must be locked in to the shoreline of the Antarctic continent, but close enough to open seawater to give the birds access to food for themselves and their young. As climate warms, however, that sea ice will gradually disappear, robbing the birds of their habitat, food sources, and ability to hatch chicks.
Jenouvrier and her team conducted the study by combining two existing computer models. The first, a global climate model created by the National Center for Atmospheric Research (NCAR), offered projections of where and when sea ice would form under different climate scenarios. The second, a model of the penguin population itself, calculated how colonies might react to changes in that ice habitat.
"We've been developing that penguin model for 10 years," says Jenouvrier. "It can give a very detailed account of how sea ice affects the life cycle of emperor penguins, their reproduction, and their mortality. When we feed the results of the NCAR climate model into it, we can start to see how different global temperature targets may affect the emperor penguin population as a whole."
The researchers ran the model on three different scenarios: a future where global temperature increases by only 1.5 degrees Celsius (the goal set out by the Paris climate accord), one where temperatures increase by 2 degrees Celsius, and one where no action is taken to reduce climate change, causing to a temperature increase of 5 to 6 degrees Celsius.
Under the 1.5 degree scenario, the study found that only 5 percent of sea ice would be lost by 2100, causing a 19 percent drop in the number of penguin colonies. If the planet warms by 2 degrees, however, those numbers increase dramatically: the loss of sea ice nearly triples, and more than a third of existing colonies disappear. The 'business as usual' scenario is even more dire, Jenouvrier adds, with an almost complete loss of the colonies ensured.
Read more at Science Daily
"If global climate keeps warming at the current rate, we expect emperor penguins in Antarctica to experience an 86 percent decline by the year 2100," says Stephanie Jenouvrier, a seabird ecologist at WHOI and lead author on the paper. "At that point, it is very unlikely for them to bounce back."
The fate of the penguins is largely tied to the fate of sea ice, which the animals use as a home base for breeding and molting, she notes. Emperor penguins tend to build their colonies on ice with extremely specific conditions -- it must be locked in to the shoreline of the Antarctic continent, but close enough to open seawater to give the birds access to food for themselves and their young. As climate warms, however, that sea ice will gradually disappear, robbing the birds of their habitat, food sources, and ability to hatch chicks.
Jenouvrier and her team conducted the study by combining two existing computer models. The first, a global climate model created by the National Center for Atmospheric Research (NCAR), offered projections of where and when sea ice would form under different climate scenarios. The second, a model of the penguin population itself, calculated how colonies might react to changes in that ice habitat.
"We've been developing that penguin model for 10 years," says Jenouvrier. "It can give a very detailed account of how sea ice affects the life cycle of emperor penguins, their reproduction, and their mortality. When we feed the results of the NCAR climate model into it, we can start to see how different global temperature targets may affect the emperor penguin population as a whole."
The researchers ran the model on three different scenarios: a future where global temperature increases by only 1.5 degrees Celsius (the goal set out by the Paris climate accord), one where temperatures increase by 2 degrees Celsius, and one where no action is taken to reduce climate change, causing to a temperature increase of 5 to 6 degrees Celsius.
Under the 1.5 degree scenario, the study found that only 5 percent of sea ice would be lost by 2100, causing a 19 percent drop in the number of penguin colonies. If the planet warms by 2 degrees, however, those numbers increase dramatically: the loss of sea ice nearly triples, and more than a third of existing colonies disappear. The 'business as usual' scenario is even more dire, Jenouvrier adds, with an almost complete loss of the colonies ensured.
Read more at Science Daily
Study: Actually, potted plants don't improve indoor air quality
Plants can help spruce up a home or office space, but claims about their ability to improve the air quality are vastly overstated, according to research out of Drexel University. A closer look at decades of research suggesting that potted plants can improve the air in homes and offices reveals that natural ventilation far outpaces plants when it comes to cleaning the air.
"This has been a common misconception for some time. Plants are great, but they don't actually clean indoor air quickly enough to have an effect on the air quality of your home or office environment," said Michael Waring, PhD, an associate professor of architectural and environmental engineering in Drexel's College of Engineering.
Waring and one of his doctoral students, Bryan Cummings, reviewed a dozen studies, spanning 30 years of research, to draw their conclusions and recently published findings in the Journal of Exposure Science and Environmental Epidemiology . The central finding is that the natural or ventilation air exchange rates in indoor environments, like homes and offices, dilutes concentrations of volatile organic compounds -- the air pollution that plants are allegedly cleaning -- much faster than plants can extract them from the air.
The high-profile experiment that seemed to create the myth of houseplants as air purifiers happened in 1989 when NASA, in search of ways to clean the air on space stations, declared that plants could be used to remove cancer-causing chemicals from the air.
But the problem with this experiment, and others like it, is that they were conducted in a sealed chamber in a lab -- a contained environment that has little in common with a house or office -- and the data from these studies was not interpreted further to reflect what the findings would be if the plant were in a real indoor environment with natural or ventilation air exchange.
"Typical for these studies," the researchers write, "a potted plant was placed in a sealed chamber (often with a volume of a cubic meter or smaller), into which a single VOC was injected, and its decay was tracked over the course of many hours or days."
Waring and Cummings's review takes the data from volumes of potted plant research one step farther, by using it to calculate a measure called the "clean air delivery rate," or "CADR." They were able to make this calculation for nearly all of the studies and what they found in every case was that the rate at which plants dissipated VOCs in a chamber was orders of magnitude slower than the standard rate of air exchange in a building -- thus proving the plants' overall effect on indoor air quality to be irrelevant.
"The CADR is the standard metric used for scientific study of the impacts of air purifiers on indoor environments, but many of the researchers conducting these studies were not looking at them from an environmental engineering perspective and did not understand how building air exchange rates interplay with the plants to affect indoor air quality," Waring said.
Many of these studies did show a reduction in the concentration of volatile organic compounds over time, which is likely why people have seized on them to extol the air purifying virtues of plants. But according to Waring and Cummings's calculations, it would take between 10 and 1,000 plants per square meter of floor space to compete with the air cleaning capacity of a building's air handling system or even just a couple open windows in a house.
Read more at Science Daily
"This has been a common misconception for some time. Plants are great, but they don't actually clean indoor air quickly enough to have an effect on the air quality of your home or office environment," said Michael Waring, PhD, an associate professor of architectural and environmental engineering in Drexel's College of Engineering.
Waring and one of his doctoral students, Bryan Cummings, reviewed a dozen studies, spanning 30 years of research, to draw their conclusions and recently published findings in the Journal of Exposure Science and Environmental Epidemiology . The central finding is that the natural or ventilation air exchange rates in indoor environments, like homes and offices, dilutes concentrations of volatile organic compounds -- the air pollution that plants are allegedly cleaning -- much faster than plants can extract them from the air.
The high-profile experiment that seemed to create the myth of houseplants as air purifiers happened in 1989 when NASA, in search of ways to clean the air on space stations, declared that plants could be used to remove cancer-causing chemicals from the air.
But the problem with this experiment, and others like it, is that they were conducted in a sealed chamber in a lab -- a contained environment that has little in common with a house or office -- and the data from these studies was not interpreted further to reflect what the findings would be if the plant were in a real indoor environment with natural or ventilation air exchange.
"Typical for these studies," the researchers write, "a potted plant was placed in a sealed chamber (often with a volume of a cubic meter or smaller), into which a single VOC was injected, and its decay was tracked over the course of many hours or days."
Waring and Cummings's review takes the data from volumes of potted plant research one step farther, by using it to calculate a measure called the "clean air delivery rate," or "CADR." They were able to make this calculation for nearly all of the studies and what they found in every case was that the rate at which plants dissipated VOCs in a chamber was orders of magnitude slower than the standard rate of air exchange in a building -- thus proving the plants' overall effect on indoor air quality to be irrelevant.
"The CADR is the standard metric used for scientific study of the impacts of air purifiers on indoor environments, but many of the researchers conducting these studies were not looking at them from an environmental engineering perspective and did not understand how building air exchange rates interplay with the plants to affect indoor air quality," Waring said.
Many of these studies did show a reduction in the concentration of volatile organic compounds over time, which is likely why people have seized on them to extol the air purifying virtues of plants. But according to Waring and Cummings's calculations, it would take between 10 and 1,000 plants per square meter of floor space to compete with the air cleaning capacity of a building's air handling system or even just a couple open windows in a house.
Read more at Science Daily
Mammals' complex spines are linked to high metabolisms; we're learning how they evolved
Mammals' backbones are weird. Compared to other four-legged animals like reptiles, mammal spines are a complex mix of sections of differently-shaped bones. Our Frankenstein's monster backbones are a key component of mammals evolving the ability to move in a bunch of different ways -- compare a cheetah running, a person walking, a bat flying, and a whale swimming. A new study in Nature Communications delves into the nitty-gritty of how mammals' backbones became so complex. The scientists discovered that the process was marked by big, dramatic evolutionary changes, and that it's linked to mammals being active animals with high metabolisms.
"Looking around, the animals and plants that surround us are remarkably complex, but putting a number to that phenomenon is very tricky. With this study, we wanted to take a complex system-the mammal vertebral column-and measure how its complexity changed through time. We show that increases in complexity were discrete steps like rungs on a ladder instead of a smooth increase like a ramp. Adaptations for high activity levels in mammals seem to trigger these jumps in complexity, and they continue to influence its evolution today," says Katrina Jones, the paper's first author and a paleontologist from Harvard's Museum of Comparative Zoology.
"It's basically the story of how weird mammals' backbones are and how they evolved to be like that, starting starting from ancient relatives whose spines were much simpler," says Ken Angielczyk, a paleontologist at the Field Museum and one of the study's authors. "It looks like it's not just a gradual accumulation of little changes over time -- it's more discrete changes. And one of these big changes may be related to changes in how mammals are able to move and breathe that let us be so active."
Angielczyk and his co-authors, Jones and Stephanie Pierce of Harvard's Museum of Comparative Zoology, wanted to figure out how and when mammals and their ancestors first evolved these specialized backbones. They examined fossil backbones from mammal relatives called synapsids that lived between 300 and 200 million years ago and took precise measurements of the bones to determine how the spines were changing over time. They then fed all the data into a computer program that modeled the different ways that the spines might have evolved.
Based on the information from all the fossils, the model showed that the changes in synapsid backbones probably developed in comparatively quick bursts, rather than a super-slow, gradual pathway. Of course, explains Angielczyk, evolution is such a slow process that even quick bursts of evolutionary change can take millions of years. "It looks fast from our mountain-top view of evolution, but if you were one of these animals, it's not like your grandchildren would look totally different from you," he says. Rather, these big leaps really just mean that the evolutionary changes happened more quickly than what you'd expect to see in a totally random system where mutations and changes weren't good or bad, just neutral. Basically, big step-wise jumps in evolution mean that the changes that were happening made a big difference in the organisms' lives, making them better able to survive and pass on their genes.
Increasingly complex spines were such a good thing for mammal ancestors, the researchers argue, because they were part of a suite of changes related to higher activity levels.
Compared to reptiles, modern mammals have very high metabolisms -- we have more chemical reactions happening to keep our bodies going -- and we're more active. In general, mammals can move more efficiently and have more stamina, but those benefits come with a cost: mammals have to breathe more than reptiles do, we have to eat more, and we need fur to keep our bodies warm enough to keep our systems going. "As part of our study, we found that modern mammals with the most complex backbones also usually have the highest activity levels," says Pierce, "and some changes in in backbone complexity evolved at about the same time that other features associated with a more active lifestyle evolved, like fur or specialized muscles for breathing."
"The uniqueness of mammalian backbones is something that's been recognized for a long time, and our results show that there's a strong connection between the evolution of our backbones and the evolution of the soft tissues in our muscular and respiratory systems," says Angielczyk.
"We're interested in the big picture of how backbones evolve, and there are these long-standing ideas about it being related to the evolution of mammals' respiration, locomotion, and high acitvity levels," Angielczyk adds. "We're trying to test and refine those hypotheses, and to use them to better understand the broader question of how complexity increases through evolution."
And this big picture of how mammals' spines became complex could help to explain a lot about mammals alive today, including us. "Mammals kind of do their own thing," says Angielczyk. "If you look at mammals today, we have lots of weird features in our metabolism and our bodies and reproductive strategies. It would be really confusing to figure out how they evolved if you were only looking at modern mammals. But we have a really good fossil record of early mammal relatives, and that can help us understand the history of many of these very unusual traits."
Read more at Science Daily
"Looking around, the animals and plants that surround us are remarkably complex, but putting a number to that phenomenon is very tricky. With this study, we wanted to take a complex system-the mammal vertebral column-and measure how its complexity changed through time. We show that increases in complexity were discrete steps like rungs on a ladder instead of a smooth increase like a ramp. Adaptations for high activity levels in mammals seem to trigger these jumps in complexity, and they continue to influence its evolution today," says Katrina Jones, the paper's first author and a paleontologist from Harvard's Museum of Comparative Zoology.
"It's basically the story of how weird mammals' backbones are and how they evolved to be like that, starting starting from ancient relatives whose spines were much simpler," says Ken Angielczyk, a paleontologist at the Field Museum and one of the study's authors. "It looks like it's not just a gradual accumulation of little changes over time -- it's more discrete changes. And one of these big changes may be related to changes in how mammals are able to move and breathe that let us be so active."
Angielczyk and his co-authors, Jones and Stephanie Pierce of Harvard's Museum of Comparative Zoology, wanted to figure out how and when mammals and their ancestors first evolved these specialized backbones. They examined fossil backbones from mammal relatives called synapsids that lived between 300 and 200 million years ago and took precise measurements of the bones to determine how the spines were changing over time. They then fed all the data into a computer program that modeled the different ways that the spines might have evolved.
Based on the information from all the fossils, the model showed that the changes in synapsid backbones probably developed in comparatively quick bursts, rather than a super-slow, gradual pathway. Of course, explains Angielczyk, evolution is such a slow process that even quick bursts of evolutionary change can take millions of years. "It looks fast from our mountain-top view of evolution, but if you were one of these animals, it's not like your grandchildren would look totally different from you," he says. Rather, these big leaps really just mean that the evolutionary changes happened more quickly than what you'd expect to see in a totally random system where mutations and changes weren't good or bad, just neutral. Basically, big step-wise jumps in evolution mean that the changes that were happening made a big difference in the organisms' lives, making them better able to survive and pass on their genes.
Increasingly complex spines were such a good thing for mammal ancestors, the researchers argue, because they were part of a suite of changes related to higher activity levels.
Compared to reptiles, modern mammals have very high metabolisms -- we have more chemical reactions happening to keep our bodies going -- and we're more active. In general, mammals can move more efficiently and have more stamina, but those benefits come with a cost: mammals have to breathe more than reptiles do, we have to eat more, and we need fur to keep our bodies warm enough to keep our systems going. "As part of our study, we found that modern mammals with the most complex backbones also usually have the highest activity levels," says Pierce, "and some changes in in backbone complexity evolved at about the same time that other features associated with a more active lifestyle evolved, like fur or specialized muscles for breathing."
"The uniqueness of mammalian backbones is something that's been recognized for a long time, and our results show that there's a strong connection between the evolution of our backbones and the evolution of the soft tissues in our muscular and respiratory systems," says Angielczyk.
"We're interested in the big picture of how backbones evolve, and there are these long-standing ideas about it being related to the evolution of mammals' respiration, locomotion, and high acitvity levels," Angielczyk adds. "We're trying to test and refine those hypotheses, and to use them to better understand the broader question of how complexity increases through evolution."
And this big picture of how mammals' spines became complex could help to explain a lot about mammals alive today, including us. "Mammals kind of do their own thing," says Angielczyk. "If you look at mammals today, we have lots of weird features in our metabolism and our bodies and reproductive strategies. It would be really confusing to figure out how they evolved if you were only looking at modern mammals. But we have a really good fossil record of early mammal relatives, and that can help us understand the history of many of these very unusual traits."
Read more at Science Daily
Nov 7, 2019
Strained family relations and worsening of chronic health conditions
Strained relationships with parents, siblings or extended family members may be more harmful to people's health than a troubled relationship with a significant other, according to a study published by the American Psychological Association.
"We found that family emotional climate had a big effect on overall health, including the development or worsening of chronic conditions such as stroke and headaches over the 20-year span of midlife," said Sarah B. Woods, PhD, assistant professor of family and community medicine at UT Southwestern Medical Center and lead author of the study. "Contrary to previous research, which found that intimate relationships had a large effect on physical health, we did not get the same results."
The study was published in the Journal of Family Psychology.
"Most often, researchers focus on romantic relationships, especially marriage, presuming they likely have more of a powerful effect on heath," Woods said. "Given changes in how Americans are partnering, waiting longer to marry, if at all, and the lengthier, and possibly more emotion-laden trajectories of family-of-origin relationships, we wanted to compare the strength of associations between family and intimate partners and health over time."
The researchers used data from 2,802 participants in the Midlife Development in the U.S. survey that included a nationally representative sample of adults from 1995 to 2014. Three rounds of data were collected -- in 1995 to 1996, 2004 to 2006 and 2013 to 2014. The average participant was 45 years old during the first round.
The survey asked questions about family strain (e.g., "Not including your spouse or partner, how often do members of your family criticize you?") and family support (e.g., "How much can you rely on [your family] for help if you have a serious problem?") as well as intimate partner strain (e.g., "How often does your spouse or partner argue with you?") and support (e.g., "How much does your spouse or partner appreciate you?")
Health was measured using participants' total number of chronic conditions, such as stroke, headaches and stomach trouble, experienced in the 12 months prior to each of the three data collection times.
Participants also rated their overall health from excellent to poor at each round.
The researchers found that greater family relationship strain was associated with a greater number of chronic conditions and worse health appraisal 10 years later, during the second and third rounds of data collection.
"Comparatively, we found that greater family support during the second round of data collection in 2004 to 2006 was associated with better health appraisal 10 years later," said Jacob B. Priest, PhD, assistant professor of education at the University of Iowa and co-author of the study.
There were no significant effects of intimate partner relationships on health outcomes.
"We were honestly stunned that there were zero associations between intimate partner emotional climate and later health," Woods said.
She and her co-authors theorize that the lack of significant associations between intimate partner relationships and later health could be because those relationships can break up, whereas people are more likely to have longer associations with family members who aren't a spouse.
"The vast majority of the people in the study had living parents or siblings and thus, their relationship with a spouse or intimate partner was less likely to be as long as that of their family members," said Patricia N.E. Roberson, PhD, assistant professor of nursing of the University of Tennessee, Knoxville and co-author of the study. "Therefore, the emotional intensity of these relationships may be greater, so much so that people experience more of an effect on their health and well-being."
Woods and her colleagues said their findings show why physical and mental health care providers should consider family relationships when assessing and treating patients.
Read more at Science Daily
"We found that family emotional climate had a big effect on overall health, including the development or worsening of chronic conditions such as stroke and headaches over the 20-year span of midlife," said Sarah B. Woods, PhD, assistant professor of family and community medicine at UT Southwestern Medical Center and lead author of the study. "Contrary to previous research, which found that intimate relationships had a large effect on physical health, we did not get the same results."
The study was published in the Journal of Family Psychology.
"Most often, researchers focus on romantic relationships, especially marriage, presuming they likely have more of a powerful effect on heath," Woods said. "Given changes in how Americans are partnering, waiting longer to marry, if at all, and the lengthier, and possibly more emotion-laden trajectories of family-of-origin relationships, we wanted to compare the strength of associations between family and intimate partners and health over time."
The researchers used data from 2,802 participants in the Midlife Development in the U.S. survey that included a nationally representative sample of adults from 1995 to 2014. Three rounds of data were collected -- in 1995 to 1996, 2004 to 2006 and 2013 to 2014. The average participant was 45 years old during the first round.
The survey asked questions about family strain (e.g., "Not including your spouse or partner, how often do members of your family criticize you?") and family support (e.g., "How much can you rely on [your family] for help if you have a serious problem?") as well as intimate partner strain (e.g., "How often does your spouse or partner argue with you?") and support (e.g., "How much does your spouse or partner appreciate you?")
Health was measured using participants' total number of chronic conditions, such as stroke, headaches and stomach trouble, experienced in the 12 months prior to each of the three data collection times.
Participants also rated their overall health from excellent to poor at each round.
The researchers found that greater family relationship strain was associated with a greater number of chronic conditions and worse health appraisal 10 years later, during the second and third rounds of data collection.
"Comparatively, we found that greater family support during the second round of data collection in 2004 to 2006 was associated with better health appraisal 10 years later," said Jacob B. Priest, PhD, assistant professor of education at the University of Iowa and co-author of the study.
There were no significant effects of intimate partner relationships on health outcomes.
"We were honestly stunned that there were zero associations between intimate partner emotional climate and later health," Woods said.
She and her co-authors theorize that the lack of significant associations between intimate partner relationships and later health could be because those relationships can break up, whereas people are more likely to have longer associations with family members who aren't a spouse.
"The vast majority of the people in the study had living parents or siblings and thus, their relationship with a spouse or intimate partner was less likely to be as long as that of their family members," said Patricia N.E. Roberson, PhD, assistant professor of nursing of the University of Tennessee, Knoxville and co-author of the study. "Therefore, the emotional intensity of these relationships may be greater, so much so that people experience more of an effect on their health and well-being."
Woods and her colleagues said their findings show why physical and mental health care providers should consider family relationships when assessing and treating patients.
Read more at Science Daily
Physical activity linked to lower risk of fracture
Regular physical activity, including lighter intensity activities such as walking, is associated with reduced risk of hip and total fracture in postmenopausal women, according to new research from the University at Buffalo.
Published Oct. 25 in JAMA Network Open, the study is the most comprehensive evaluation of physical activity and fracture incidence in older women.
The study included more than 77,000 participants in the Women's Health Initiative, who were followed up over 14 years. During follow-up, 33% of participants reported experiencing at least one fracture.
The women who did the highest amount of physical activity -- which was approximately 35 minutes or more of daily recreational and household activities -- had an 18% lower risk of hip fracture and 6% lower risk of total fracture.
The study is one more among several papers -- all using data from the Women's Health Initiative -- published by UB researchers within the past few years that highlights the health benefits of being active, even at levels that are lower than the current physical activity guidelines.
"These findings provide evidence that fracture reduction is among the many positive attributes of regular physical activity in older women," said Jean Wactawski-Wende, PhD, study co-author and dean of the University at Buffalo School of Public Health and Health Professions.
"Fracture is very common in postmenopausal women, and is associated with loss of independence, physical limitations and increased mortality," Wactawski-Wende said.
In fact, the researchers note, approximately 1.5 million fractures occur in U.S. women each year, creating $12.7 billion in health care costs. About 14% of these fractures are in the hip. Mortality after a hip fracture is as high as 20%.
"Modest activities, including walking, can significantly reduce the risk of fracture, which can, in turn, lower the risk of death," Wactawski-Wende said.
Non-recreation physical activity -- examples include yardwork and household chores such as sweeping the floors or folding laundry -- also was inversely associated with several types of fracture.
The research has important implications for public health, considering that these lighter intensity activities are common among older adults.
The main message, says study first author Michael LaMonte, PhD, research associate professor of epidemiology and environmental health at UB, is "sit less, move more, and every movement counts."
Read more at Science Daily
Published Oct. 25 in JAMA Network Open, the study is the most comprehensive evaluation of physical activity and fracture incidence in older women.
The study included more than 77,000 participants in the Women's Health Initiative, who were followed up over 14 years. During follow-up, 33% of participants reported experiencing at least one fracture.
The women who did the highest amount of physical activity -- which was approximately 35 minutes or more of daily recreational and household activities -- had an 18% lower risk of hip fracture and 6% lower risk of total fracture.
The study is one more among several papers -- all using data from the Women's Health Initiative -- published by UB researchers within the past few years that highlights the health benefits of being active, even at levels that are lower than the current physical activity guidelines.
"These findings provide evidence that fracture reduction is among the many positive attributes of regular physical activity in older women," said Jean Wactawski-Wende, PhD, study co-author and dean of the University at Buffalo School of Public Health and Health Professions.
"Fracture is very common in postmenopausal women, and is associated with loss of independence, physical limitations and increased mortality," Wactawski-Wende said.
In fact, the researchers note, approximately 1.5 million fractures occur in U.S. women each year, creating $12.7 billion in health care costs. About 14% of these fractures are in the hip. Mortality after a hip fracture is as high as 20%.
"Modest activities, including walking, can significantly reduce the risk of fracture, which can, in turn, lower the risk of death," Wactawski-Wende said.
Non-recreation physical activity -- examples include yardwork and household chores such as sweeping the floors or folding laundry -- also was inversely associated with several types of fracture.
The research has important implications for public health, considering that these lighter intensity activities are common among older adults.
The main message, says study first author Michael LaMonte, PhD, research associate professor of epidemiology and environmental health at UB, is "sit less, move more, and every movement counts."
Read more at Science Daily
Carbon dioxide capture and use could become big business
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| Carbon dioxide emissions concept |
Should that happen, the phenomenon would help the environment by reducing greenhouse gas emissions.
The research, published in Nature, is the most comprehensive study to date investigating the potential future scale and cost of 10 different ways to use carbon dioxide, including in fuels and chemicals, plastics, building materials, soil management and forestry. The study considered processes using carbon dioxide captured from waste gases that are produced by burning fossil fuels or from the atmosphere by an industrial process.
And in a step beyond most previous research on the subject, the authors also considered processes that use carbon dioxide captured biologically by photosynthesis.
The research found that on average each utilization pathway could use around 0.5 gigatonnes of carbon dioxide per year that would otherwise escape into the atmosphere. (A tonne, or metric ton, is equivalent to 1,000 kilograms, and a gigatonne is 1 billion tonnes, or about 1.1 billion U.S. tons.)
A top-end scenario could see more than 10 gigatonnes of carbon dioxide a year used, at a theoretical cost of under $100 per tonne of carbon dioxide. The researchers noted, however, that the potential scales and costs of using carbon dioxide varied substantially across sectors.
"The analysis we presented makes clear that carbon dioxide utilization can be part of the solution to combat climate change, but only if those with the power to make decisions at every level of government and finance commit to changing policies and providing market incentives across multiple sectors," said Emily Carter, a distinguished professor of chemical and biomolecular engineering at the UCLA Samueli School of Engineering and a co-author of the paper. "The urgency is huge and we have little time left to effect change."
According to the Intergovernmental Panel on Climate Change, keeping global warming to 1.5 degrees Celsius over the rest of the 21st century will require the removal of carbon dioxide from the atmosphere on the order of 100 to 1,000 gigatonnes of carbon dioxide. Currently, fossil carbon dioxide emissions are increasing by over 1% annually, reaching a record high of 37 gigatonnes of carbon dioxide in 2018.
"Greenhouse gas removal is essential to achieve net zero carbon emissions and stabilise the climate," said Cameron Hepburn, one of the study's lead authors, director of Oxford's Smith School of Enterprise and Environment. "We haven't reduced our emissions fast enough, so now we also need to start pulling carbon dioxide out of the atmosphere. Governments and corporations are moving on this, but not quickly enough.
"The promise of carbon dioxide utilization is that it could act as an incentive for carbon dioxide removal and could reduce emissions by displacing fossil fuels."
Critical to the success of these new technologies as mitigation strategies will be a careful analysis of their overall impact on the climate. Some are likely to be adopted quickly simply because of their attractive business models. For example, in certain kinds of plastic production, using carbon dioxide as a feedstock is a more profitable and environmentally cleaner production process than using conventional hydrocarbons, and it can displace up to three times as much carbon dioxide as it uses.
Biological uses might also present opportunities to reap co-benefits. In other areas, utilization could provide a "better choice" alternative during the global decarbonization process. One example might be the use of fuels derived from carbon dioxide, which could find a role in sectors that are harder to decarbonize, such as aviation.
The authors stressed that there is no "magic bullet" approach.
Read more at Science Daily
Go with the flow: Scientists design new grid batteries for renewable energy
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| High-voltage tower |
Now, a battery membrane technology developed by researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) may point to a solution.
As reported in the journal of Joule, the researchers developed a versatile yet affordable battery membrane -- from a class of polymers known as AquaPIMs. This class of polymers makes long-lasting and low-cost grid batteries possible based solely on readily available materials such as zinc, iron, and water. The team also developed a simple model showing how different battery membranes impact the lifetime of the battery, which is expected to accelerate early stage R&D for flow-battery technologies, particularly in the search for a suitable membrane for different battery chemistries.
"Our AquaPIM membrane technology is well-positioned to accelerate the path to market for flow batteries that use scalable, low-cost, water-based chemistries," said Brett Helms, a principal investigator in the Joint Center for Energy Storage Research (JCESR) and staff scientist at Berkeley Lab's Molecular Foundry who led the study. "By using our technology and accompanying empirical models for battery performance and lifetime, other researchers will be able to quickly evaluate the readiness of each component that goes into the battery, from the membrane to the charge-storing materials. This should save time and resources for researchers and product developers alike."
Most grid battery chemistries have highly alkaline (or basic) electrodes -- a positively charged cathode on one side, and a negatively charged anode on the other side. But current state-of-the-art membranes are designed for acidic chemistries, such as the fluorinated membranes found in fuel cells, but not for alkaline flow batteries. (In chemistry, pH is a measure of the hydrogen ion concentration of a solution. Pure water has a pH of 7 and is considered neutral. Acidic solutions have a high concentration of hydrogen ions, and are described as having a low pH, or a pH below 7. On the other hand, alkaline solutions have low concentrations of hydrogen ions and therefore have a high pH, or a pH above 7. In alkaline batteries, the pH can be as high as 14 or 15.)
Fluorinated polymer membranes are also expensive. According to Helms, they can make up 15% to 20% of the battery's cost, which can run in the range of $300/kWh.
One way to drive down the cost of flow batteries is to eliminate the fluorinated polymer membranes altogether and come up with a high-performing yet cheaper alternative such as AquaPIMs, said Miranda Baran, a graduate student researcher in Helms' research group and the study's lead author. Baran is also a Ph.D. student in the Department of Chemistry at UC Berkeley.
Getting back to basics
Helms and co-authors discovered the AquaPIM technology -- which stands for "aqueous-compatible polymers of intrinsic microporosity" -- while developing polymer membranes for aqueous alkaline (or basic) systems as part of a collaboration with co-author Yet-Ming Chiang, a principal investigator in JCESR and Kyocera Professor of Materials Science and Engineering at the Massachusetts Institute of Technology (MIT).
Through these early experiments, the researchers learned that membranes modified with an exotic chemical called an "amidoxime" allowed ions to quickly travel between the anode and cathode.
Later, while evaluating AquaPIM membrane performance and compatibility with different grid battery chemistries -- for example, one experimental setup used zinc as the anode and an iron-based compound as the cathode -- the researchers discovered that AquaPIM membranes lead to remarkably stable alkaline cells.
In addition, they found that the AquaPIM prototypes retained the integrity of the charge-storing materials in the cathode as well as in the anode. When the researchers characterized the membranes at Berkeley Lab's Advanced Light Source (ALS), the researchers found that these characteristics were universal across AquaPIM variants.
Baran and her collaborators then tested how an AquaPIM membrane would perform with an aqueous alkaline electrolyte. In this experiment, they discovered that under alkaline conditions, polymer-bound amidoximes are stable -- a surprising result considering that organic materials are not typically stable at high pH.
Such stability prevented the AquaPIM membrane pores from collapsing, thus allowing them to stay conductive without any loss in performance over time, whereas the pores of a commercial fluoro-polymer membrane collapsed as expected, to the detriment of its ion transport properties, Helms explained.
This behavior was further corroborated with theoretical studies by Artem Baskin, a postdoctoral researcher working with David Prendergast, who is the acting director of Berkeley Lab's Molecular Foundry and a principal investigator in JCESR along with Chiang and Helms.
Baskin simulated structures of AquaPIM membranes using computational resources at Berkeley Lab's National Energy Research Scientific Computing Center (NERSC) and found that the structure of the polymers making up the membrane were significantly resistant to pore collapse under highly basic conditions in alkaline electrolytes.
A screen test for better batteries
While evaluating AquaPIM membrane performance and compatibility with different grid battery chemistries, the researchers developed a model that tied the performance of the battery to the performance of various membranes. This model could predict the lifetime and efficiency of a flow battery without having to build an entire device. They also showed that similar models could be applied to other battery chemistries and their membranes.
"Typically, you'd have to wait weeks if not months to figure out how long a battery will last after assembling the entire cell. By using a simple and quick membrane screen, you could cut that down to a few hours or days," Helms said.
Read more at Science Daily
New model for the way humans localize sounds
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| Man listening |
Unlike other sensory perceptions, such as feeling where raindrops hit the skin or being able to distinguish high notes from low on the piano, the direction of sounds must be computed; the brain estimates them by processing the difference in arrival time across the two ears, the so-called interaural time difference (ITD). A longstanding consensus among biomedical engineers is that humans localize sounds with a scheme akin to a spatial map or compass, with neurons aligned from left to right that fire individually when activated by a sound coming from a given angle -- say, at 30 degrees leftward from the center of the head.
But in research published this month in the journal eLife, Antje Ihlefeld, director of NJIT's Neural Engineering for Speech and Hearing Laboratory, is proposing a different model based on a more dynamic neural code. The discovery offers new hope, she says, that engineers may one day devise hearing aids, now notoriously poor in restoring sound direction, to correct this deficit.
"If there is a static map in the brain that degrades and can't be fixed, that presents a daunting hurdle. It means people likely can't "relearn" to localize sounds well. But if this perceptual capability is based on a dynamic neural code, it gives us more hope of retraining peoples' brains," Ihlefeld notes. "We would program hearing aids and cochlear implants not just to compensate for an individual's hearing loss, but also based upon how well that person could adapt to using cues from their devices. This is particularly important for situations with background sound, where no hearing device can currently restore the ability to single out the target sound. We know that providing cues to restore sound direction would really help."
What led her to this conclusion is a journey of scholarly detective work that began with a conversation with Robert Shapley, an eminent neurophysiologist at NYU who remarked on a peculiarity of human binocular depth perception -- the ability to determine how far away a visual object is -- that also depends on a computation comparing input received by both eyes. Shapley noted that these distance estimates are systematically less accurate for low-contrast stimuli (images that are more difficult to distinguish from their surrounding) than for high-contrast ones.
Ihlefeld and Shapley wondered if the same neural principle applied to sound localization: whether it is less accurate for softer sounds than for louder ones. But this would depart from the prevailing spatial map theory, known as the Jeffress model, which holds that sounds of all volumes are processed -- and therefore perceived -- the same way. Physiologists, who propose that mammals rely on a more dynamic neural model, have long disagreed with it. They hold that mammalian neurons tend to fire at different rates depending on directional signals and that the brain then compares these rates across sets of neurons to dynamically build up a map of the sound environment.
"The challenge in proving or disproving these theories is that we can't look directly at the neural code for these perceptions because the relevant neurons are located in the human brainstem, so we cannot obtain high-resolution images of them," she says. "But we had a hunch that the two models would give different sound location predictions at a very low volume."
They searched the literature for evidence and found only two papers that had recorded from neural tissue at these low sounds. One study was in barn owls -- a species thought to rely on the Jeffress model, based on high-resolution recordings in the birds' brain tissue -- and the other study was in a mammal, the rhesus macaque, an animal thought to use dynamic rate coding. They then carefully reconstructed the firing properties of the neurons recorded in these old studies and used their reconstructions to estimate sound direction both as a function of ITD and volume.
"We expected that for the barn owl data, it really should not matter how loud a source is -- the predicted sound direction should be really accurate no matter the sound volume -- and we were able to confirm that. However, what we found for the monkey data is that predicted sound direction depended on both ITD and volume," she said. "We then searched the human literature for studies on perceived sound direction as a function of ITD, which was also thought not to depend on volume, but surprisingly found no evidence to back up this long-held belief."
She and her graduate student, Nima Alamatsaz, then enlisted volunteers on the NJIT campus to test their hypothesis, using sounds to test how volume affects where people think a sound emerges.
"We built an extremely quiet, sound-shielded room with specialized calibrated equipment that allowed us to present sounds with high precision to our volunteers and record where they perceived the sound to originate. And sure enough, people misidentified the softer sounds," notes Alamatsaz.
"To date, we are unable to describe sound localization computations in the brain precisely," adds Ihlefeld. "However, the current results are inconsistent with the notion that the human brain relies on a Jeffress-like computation. Instead, we seem to rely on a slightly less accurate mechanism.
More broadly, the researchers say, their studies point to direct parallels in hearing and visual perception that have been overlooked before now and that suggest that rate-based coding is a basic underlying operation when computing spatial dimensions from two sensory inputs.
Read more at Science Daily
Nov 6, 2019
Exceptional fossils may need a breath of air to form
Some of the world's most exquisite fossil beds were formed millions of years ago during time periods when the Earth's oceans were largely without oxygen.
That association has led paleontologists to believe that the world's best-preserved fossil collections come from choked oceans. But research led by The University of Texas at Austin has found that while low oxygen environments set the stage, it takes a breath of air to catalyze the fossilization process.
"The traditional thinking about these exceptionally preserved fossil sites is wrong," said lead author Drew Muscente. "It is not the absence of oxygen that allows them to be preserved and fossilized. It is the presence of oxygen under the right circumstances."
The research was published in the journal PALAIOS on November 5.
Muscente conducted the research during a postdoctoral research fellowship at the UT Jackson School of Geosciences. He is currently an assistant professor at Cornell College in Mount Vernon, Iowa. The research co-authors are Jackson School Assistant Professor Rowan Martindale, Jackson School undergraduate students Brooke Bogan and Abby Creighton and University of Missouri Associate Professor James Schiffbauer.
The best-preserved fossil deposits are called "Konservat-lagerstätten." They are rare and scientifically valuable because they preserve soft tissues along with hard ones -- which in turn, preserves a greater variety of life from ancient ecosystems.
"When you look at lagerstätten, what's so interesting about them is everybody is there," said Bogan. "You get a more complete picture of the animal and the environment, and those living in it."
The research examined the fossilization history of an exceptional fossil site located at Ya Ha Tinda Ranch in Canada's Banff National Park. The site, which Martindale described in a 2017 paper, is known for its cache of delicate marine specimens from the Early Jurassic -- such as lobsters and vampire squids with their ink sacks still intact -- preserved in slabs of black shale.
During the time of fossilization, about 183 million years ago, high global temperatures sapped oxygen from the oceans. To determine if the fossils did indeed form in an oxygen-deprived environment, the team analyzed minerals in the fossils. Since different minerals form under different chemical conditions, the research could determine if oxygen was present or not.
"The cool thing about this work is that we can now understand the modes of formation of these different minerals as this organism fossilizes," Martindale said. "A particular pathway can tell you about the oxygen conditions."
The analysis involved using a scanning electron microscope to detect the mineral makeup.
"You pick points of interest that you think might tell you something about the composition," said Creighton, who analyzed a number of specimens. "From there you can correlate to the specific minerals."
The workup revealed that the vast majority of the fossils are made of apatite -- a phosphate-based mineral that needs oxygen to form. However, the research also found that the climatic conditions of a low-oxygen environment helped set the stage for fossilization once oxygen became available.
That's because periods of low ocean oxygen are linked to high global temperatures that raise sea levels and erode rock, which is a rich source of phosphate to help form fossils. If the low oxygen environment persisted, this sediment would simply release its phosphate into the ocean. But with oxygen around, the phosphate stays in the sediment where it could start the fossilization process.
Muscente said that the apatite fossils of Ya Ha Tinda point to this mechanism.
The research team does not know the source of the oxygen. But Muscente wasn't surprised to find evidence for it because the organisms that were fossilized would have needed to breathe oxygen when they were alive.
Read more at Science Daily
That association has led paleontologists to believe that the world's best-preserved fossil collections come from choked oceans. But research led by The University of Texas at Austin has found that while low oxygen environments set the stage, it takes a breath of air to catalyze the fossilization process.
"The traditional thinking about these exceptionally preserved fossil sites is wrong," said lead author Drew Muscente. "It is not the absence of oxygen that allows them to be preserved and fossilized. It is the presence of oxygen under the right circumstances."
The research was published in the journal PALAIOS on November 5.
Muscente conducted the research during a postdoctoral research fellowship at the UT Jackson School of Geosciences. He is currently an assistant professor at Cornell College in Mount Vernon, Iowa. The research co-authors are Jackson School Assistant Professor Rowan Martindale, Jackson School undergraduate students Brooke Bogan and Abby Creighton and University of Missouri Associate Professor James Schiffbauer.
The best-preserved fossil deposits are called "Konservat-lagerstätten." They are rare and scientifically valuable because they preserve soft tissues along with hard ones -- which in turn, preserves a greater variety of life from ancient ecosystems.
"When you look at lagerstätten, what's so interesting about them is everybody is there," said Bogan. "You get a more complete picture of the animal and the environment, and those living in it."
The research examined the fossilization history of an exceptional fossil site located at Ya Ha Tinda Ranch in Canada's Banff National Park. The site, which Martindale described in a 2017 paper, is known for its cache of delicate marine specimens from the Early Jurassic -- such as lobsters and vampire squids with their ink sacks still intact -- preserved in slabs of black shale.
During the time of fossilization, about 183 million years ago, high global temperatures sapped oxygen from the oceans. To determine if the fossils did indeed form in an oxygen-deprived environment, the team analyzed minerals in the fossils. Since different minerals form under different chemical conditions, the research could determine if oxygen was present or not.
"The cool thing about this work is that we can now understand the modes of formation of these different minerals as this organism fossilizes," Martindale said. "A particular pathway can tell you about the oxygen conditions."
The analysis involved using a scanning electron microscope to detect the mineral makeup.
"You pick points of interest that you think might tell you something about the composition," said Creighton, who analyzed a number of specimens. "From there you can correlate to the specific minerals."
The workup revealed that the vast majority of the fossils are made of apatite -- a phosphate-based mineral that needs oxygen to form. However, the research also found that the climatic conditions of a low-oxygen environment helped set the stage for fossilization once oxygen became available.
That's because periods of low ocean oxygen are linked to high global temperatures that raise sea levels and erode rock, which is a rich source of phosphate to help form fossils. If the low oxygen environment persisted, this sediment would simply release its phosphate into the ocean. But with oxygen around, the phosphate stays in the sediment where it could start the fossilization process.
Muscente said that the apatite fossils of Ya Ha Tinda point to this mechanism.
The research team does not know the source of the oxygen. But Muscente wasn't surprised to find evidence for it because the organisms that were fossilized would have needed to breathe oxygen when they were alive.
Read more at Science Daily
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