It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Thursday, March 05, 2020
Study find delta helps to decrease the impact of river flooding
by Dauphin Island Sea Lab
A ground-level view of the Tombigbee-Alabama Delta. Credit: Steve Dykstra, Dauphin Island Sea Lab
Most coastal cities and ports face a double threat from storm surge and river flooding. Infrastructure development along waterways and sea-level rise increase vulnerability for these communities. In a recent publication, The Propagation of Fluvial Flood Waves Through a Backwater-Estuarine Environment, historical data is examined to determine how to reduce the risk of coastal river flooding to communities.
Usually, in rivers, large flooding events move from upstream to downstream faster than small events. This study identified a different model by tracking flooding events as moved from the river to the coastal ocean. Theriver delta, which is common in manynatural systems, turned out to be very important for understanding when and where flooding is likely to happen.
Using years of observations (in some cases 9 decades of data), this study found that the Tombigbee-Alabama Delta (also known as the Mobile-Tensaw Delta) delays and reduces flooding for cities along the delta and bay. Amazingly, this effect is largely caused by the vegetation that naturally occurs in the delta.
Most of the delta is a densely packed tupelo-bald cypress swamp, supporting the most biodiverse location in temperate North America. For large events, the delta swamp acts like a sponge quickly absorbing the initial floodwaters, and then slowly releases the water back to the main rivers. This gives communities more time to prepare and reduces the risk of river flooding overlapping with a storm surge during a hurricane. The slower release of water from the delta also slows the impact on the bay, delaying the initial flushing while also keeping the salinity low for a longer period of time. In contrast, smaller flooding events moved downstream faster. This occurs because smaller flooding events remain in the confines of the river channel, where they are not impacted by the swamps of the delta.
These findings indicate the intensity of coastal flooding can be decreased and provide more time to prepare by allowing inland regions of rivers to flood and/or by managing vegetation type, both of which reduce the downstream height of water.
More information: S. L. Dykstra et al, The Propagation of Fluvial Flood Waves Through a Backwater‐Estuarine Environment, Water Resources Research (2019). DOI: 10.1029/2019WR025743
New model improves management of wetland, floodplain and river habitats
USU researchers developed a model that can help improve wetland and river habitats. Credit: USU
Wetlands, floodplains and aquatic habitats are some of Utah's most important ecosystems. They are home to many bird, plant and fish species, and they provide unique outdoor recreation opportunities.
But in recent years these habitats have faced mounting pressure from encroaching land use and increased demand for water. Now researchers at Utah State University are developing new tools that help preserve and increase the area and quality of wetland, floodplain and aquatic habitats.
USU Associate Professor David Rosenberg and Ayman Alafifi, a water resources engineer at Brown and Caldwell, have developed an innovative computer model that helps water and wetland managers make better, data-based decisions. Their work was recently published in the journal of Environmental Modelling and Software. The study is part of a multi-year research effort focused on creating more effective habitat management tools.
The Watershed Area of Suitable Habitat systems model, known as WASH, takes hydrologic, topography, ecological and management data and helps managers identify when, where and how to allocate water, financial resources and vegetation management to improve the area and quality of the three habitat types. Recommendations are subject to constraints, including water availability, vegetation growth, infrastructure and existing demands.
"It's important to manage water and vegetation together in these areas," said Rosenberg. "Managing water and vegetation together helps us identify synergies and trade-offs across the three habitat types."
Rosenberg and Alafifi recently tested the model along the lower Bear River in Northern Utah, the largest source of water to the Great Salt Lake. The results show potential to increase aquatic habitat area during all months of the year, an increase in floodplain habitat during spring and summer, and an increase in wetland habitat during critical summer months when water is most scarce.
"These habitats and their well-being affect many residents in Utah because Utahns like to fish, hunt, bird and recreate," said Rosenberg. "People value these outdoor areas and want to see them improved."
Rosenberg and Alafifi worked in collaboration with a group of stakeholders, including the Nature Conservancy, Trout Unlimited, PacifiCorp, Bear River Land Conservancy and Cache County. These stakeholders gave researchers information about the habitats, shared water and vegetation management on the river and provided feedback on model results.
More information: Ayman H. Alafifi et al, Systems modeling to improve river, riparian, and wetland habitat quality and area, Environmental Modelling & Software (2020). DOI: 10.1016/j.envsoft.2020.104643
Social studies teachers link their political views to assessment of news sources
by American Educational Research Association
Credit: CC0 Public Domain
At a time when there's been a sharp uptick in partisan critiques of the credibility of the news media and growing concern among educators about student media literacy, a new study finds a strong connection between high school social studies teachers' political ideology and how credible they find various mainstream news outlets. The finding, the study authors say, debunks any notion that social studies teachers are "above the fray" in how they present and discuss the credibility of news sources in their classrooms. The study was published today in Educational Researcher, a peer-reviewed journal of the American Educational Research Association.
"We find that social studies teachers are just as likely to be influenced by the current controversies and debates about news media credibility as the general public," said study coauthor Christopher H. Clark, an assistant professor at Northeastern State University in Oklahoma. "Social studies teachers are the educators most likely to bring the news into their classrooms on a regular basis, so understanding their choices and perceptions of news media is particularly important."
The study, conducted by Clark and University of Georgia researchers Mardi Schmeichel and H. James Garrett, drew from a survey of 1,065 high school social studies teachers from across six states—Indiana, Kansas, Minnesota, Missouri, New York, and Texas. The researchers identified five additional states to include in their survey but were not able to obtain teacher contact information from those states' education departments.
The study is the first to document the relationship between the ideology and media preferences of social studies teachers, despite the importance of linking to current events in social studies classrooms and using news media to help students understand political and social issues.
Teachers identifying as "very conservative" rated Fox News as the most credible news source from a set of 12 mainstream news sources, with a 2.03 credibility rating on a 0-to-3 scale. The only other news sources that these teachers gave an above-average credibility rating were the BBC and the Wall Street Journal.
On the other end of the political spectrum, liberals at all points on the continuum rated Fox News as least credible. "Very liberal" teachers gave Fox News a 0.39 rating, the lowest average credibility rating of any resource among the results. MSNBC received the next lowest rating from the "very liberal" group, but still earned an above-average rating 1.61.
When the researchers compared teachers who self-identified broadly as conservative to those who self-identified broadly as liberal—looking beyond those in very conservative or very liberal categories—they found some commonality. Both groups rated the BBC and NPR/PBS among the top three most trusted news sources, although liberals rated both higher on the credibility scale.
"Overall, however, there's a great deal of divergence between liberal and conservative teachers," said Clark. "In particular, conservative social studies teachers found most news sources not credible, while liberal social studies teachers found most sources credible," said Clark. "That reflects what other research has found in the general population."
The three news outlets with the widest gaps in credibility between liberal and conservative teachers were Fox News, the New York Times, and CNN.
"It is noteworthy that these three outlets, in particular, have been frequently and consistently mentioned by President Trump in his comments regarding news media outlets and their relative trustworthiness," said Schmeichel, an associate professor at the University of Georgia.
Clark and his colleagues asked social studies teachers how they defined credibility. Teachers who used a static definition—credibility as the absence of bias or having "just the facts"—were more likely to demonstrate a strong relationship between their ideological viewpoint and their assessment of news outlet trustworthiness.
Teachers who relied on a dynamic definition—credibility as adherence to fact checking, in-depth research, and other journalistic principles and practices—had a weaker relationship between ideology and credibility ratings for most of the news sources.
"Viewing credibility as a dynamic—or process-driven—characteristic seems to reduce the influence of ideology in teachers' judgments," said Garrett, an associate professor at the University of Georgia. "This suggests that by reframing the definition of credibility we could broaden exposure to a variety of news sources and perspectives on current events in the classroom."
"Our findings add support to making news media literacy a curricular mandate in schools and in teacher certification," Clark said. "They also make clear that we should not treat news stories as just conveying a neutral truth. Rather, we should understand the processes journalists use to provide fair representations of the news to their viewers, and note when they fail to follow those processes."
Why men (and other male animals) die younger: It's all in the Y chromosome
Like most other animals including humans, this lion and lioness have XY and XX chromosome pairings in their genetic makeup. Credit: Shutterstock
According to popular theory, men live shorter lives than women because they take bigger risks, have more dangerous jobs, drink and smoke more, and are poor at seeking advice from doctors.
But research by scientists at UNSW Sydney suggests the real reason may be less related to human behaviour and more to do with the type of sex chromosomes we share with most animal species.
In a study published today in Biology Letters, researchers from UNSW Science's School of Biological, Earth and Environmental Sciences analysed all available academic literature on sex chromosomes and lifespan—and they tried to establish whether there was a pattern of one sex outliving the other that was repeated across the animal kingdom.
Unguarded X hypothesis
Specifically, they wanted to test the 'unguarded X hypothesis' which suggests that the Y chromosome in heterogametic sexes—those with XY (male) sex chromosomes rather than XX (female) sex chromosomes—is less able to protect an individual from harmful genes expressed on the X chromosome. The hypothesis suggests that, as the Y chromosome is smaller than the X chromosome, and in some cases absent, it is unable to 'hide' an X chromosome that carries harmful mutations, which may later expose the individual to health threats.
Conversely, there is no such problem in a pair of homogametic chromosomes (XX), where a healthy X chromosome can stand in for another X that has deleterious genes to ensure those harmful genes aren't expressed, thus maximising the length of life for the organism.
First author on the paper and Ph.D. student Zoe Xirocostas says that after examining the lifespan data available on a wide range of animal species, it appears that the unguarded X hypothesis stacks up. This is the first time that scientists have tested the hypothesis across the board in animal taxonomy; previously it was tested only within a few groups of animals.
"We looked at lifespan data in not just primates, other mammals and birds, but also reptiles, fish, amphibians, arachnids, cockroaches, grasshoppers, beetles, butterflies and moths among others," she says.
"And we found that across that broad range of species, the heterogametic sex does tend to die earlier than the homogametic sex, and it's 17.6 percent earlier on average."
Birds, butterflies and moths
Interestingly, the researchers observed this same pattern in the classes of animals possessing their own unique pair of sex chromosomes that are the reverse of all other animals. In birds, butterflies and moths, it is the male of the species that has the homogametic sex chromosomes (denoted by ZZ) while the female has the heterogametic chromosomes (ZW). Female birds, butterflies and moths were usually found to die earlier than their male counterparts, giving credence to the unguarded X hypothesis—although strictly speaking, it's an unguarded Z in this case.
But while this study confirms that the unguarded X hypothesis is a reasonable explanation for why one sex outlives the other on average, there was one statistic that emerged from the data that took Ms Xirocostas by surprise.
"We found a smaller difference in lifespan between the males and females in the female heterogametic species compared to males and females in the male heterogametic species," she says. "In species where males are heterogametic (XY), females live almost 21 percent longer than males. But in the species of birds, butterflies and moths, where females are heterogametic (ZW), males only outlive females by 7 percent."
Simply put, heterogametic males (XY) die sooner than heterogametic females (ZW) when compared to the opposite sex in their species. Does this mean there is something still fundamentally life-shortening about being a male member of any species?
Ms Xirocostas thinks this could be the case, and lists side effects of sexual selection, the degree of Y chromosome degradation and telomere dynamics as possible explanations for this surprising trend.
"I was only expecting to see a pattern of the homogametic sex (XX or ZZ) living longer, so it came as an interesting surprise to see that the type of sex determination system (XX/XY or ZZ/ZW) could also play a role in an organism's longevity."
Ms Xirocostas says future studies of this phenomenon should test a hypothesis raised in the paper that the difference in lifespan between sexes is proportional to the difference in chromosome length between sexes, which could help us further understand the factors affecting ageing. But for now, she believes, the unguarded X hypothesis stands.
More information: Zoe A. Xirocostas et al. The sex with the reduced sex chromosome dies earlier: a comparison across the tree of life, Biology Letters (2020). DOI: 10.1098/rsbl.2019.0867
Tropical forests' carbon sink is already rapidly weakening
Amazon Forest canopy at Dawn Brazil. Credit: Peter Vander Sleen
The ability of the world's tropical forests to remove carbon from the atmosphere is decreasing, according to a study tracking 300,000 trees over 30 years, published today in Nature.
The global scientific collaboration, led by the University of Leeds, reveals that a feared switch of the world's undisturbed tropical forests from a carbon sink to a carbon source has begun.
Intact tropical forests are well-known as a crucial global carbon sink, slowing climate change by removing carbon from the atmosphere and storing it in trees, a process known as carbon sequestration. Climate models typically predict that this tropical forest carbon sink will continue for decades.
However, the new analysis of three decades of tree growth and death from 565 undisturbed tropical forests across Africa and the Amazon has found that the overall uptake of carbon into Earth's intact tropical forests peaked in the 1990s.
By the 2010s, on average, the ability of a tropical forest to absorb carbon had dropped by one-third. The switch is largely driven by carbon losses from trees dying.
The study by almost 100 institutions provides the first large-scale evidence that carbon uptake by the world's tropical forests has already started a worrying downward trend.
Study lead author Dr. Wannes Hubau, a former post-doctoral researcher at the University of Leeds now based at the Royal Museum for Central Africa in Belgium, said: "We show that peak carbon uptake into intact tropical forests occurred in the 1990s.
"By combining data from Africa and the Amazon we began to understand why these forests are changing, with carbon dioxide levels, temperature, drought, and forest dynamics being key."
"Extra carbon dioxide boosts tree growth, but every year this effect is being increasingly countered by the negative impacts of higher temperatures and droughts which slow growth and can kill trees.
"Our modelling of these factors shows a long-term future decline in the African sink and that the Amazonian sink will continue to rapidly weaken, which we predict to become a carbon source in the mid-2030s."
In the 1990s intact tropical forests removed roughly 46 billion tonnes of carbon dioxide from the atmosphere, declining to an estimated 25 billion tonnes in the 2010s.
Measuring Amazon trees Peru. Credit: Roel Brienen, University of Leeds
The lost sink capacity in the 2010s compared to the 1990s is 21 billion tonnes carbon dioxide, equivalent to a decade of fossil fuel emissions from the UK, Germany, France and Canada combined.
Overall, intact tropical forests removed 17% of human-made carbon dioxide emissions in the 1990s, reduced to just 6% in the 2010s.
This decline is because these forests were less able to absorb carbon by 33% and the area of intact forest declined by 19%, while global carbon dioxide emissions soared by 46%.
Senior author Professor Simon Lewis, from the School of Geography at Leeds, said: "Intact tropical forests remain a vital carbon sink but this research reveals that unless policies are put in place to stabilise Earth's climate it is only a matter of time until they are no longer able to sequester carbon.
"One big concern for the future of humanity is when carbon-cycle feedbacks really kick in, with nature switching from slowing climate change to accelerating it.
"After years of work deep in the Congo and Amazon rainforests we've found that one of the most worrying impacts of climate change has already begun. This is decades ahead of even the most pessimistic climate models.
"There is no time to lose in terms of tackling climate change."
To calculate changes in carbon storage the scientists measured the diameter and estimated the height of every individual tree in 565 patches of forest, returning every few years to re-measure them. By calculating the carbon stored in the trees that survived and those that died, the researchers tracked the changes in carbon storage over time.
After the final re-measurement, the study authors used a statistical model and trends in carbon dioxide emissions, temperature and rainfall to estimate changes in forest carbon storage until 2040.
By combining data from two large research networks of forests observations across Africa (AfriTRON) and Amazonia (RAINFOR) the authors show that the Amazon sink began weakening first, starting in the mid-1990s, followed by a waning of the African sink about 15 years later.
The continental difference arises from a combination of Amazon forests being more dynamic than those in Africa, and Amazon forests facing stronger climate impacts. Typical Amazonian forests are exposed to higher temperatures, faster temperature increases and more regular and severe droughts, than African forests.
A technician from the Ghana Forestry Commission collects data Credit: Sophie Fauset, University of Plymouth
Dr. Hubau, Professor Lewis and their colleagues have spent years travelling to numerous remote field sites, including spending a week in a dug-out canoe to reach Salonga National Park in central Democratic Republic of Congo.
Dr. Hubau said: "The ability of forests to slow climate change is a crucial element of understanding how the Earth system functions—particularly how much carbon is absorbed by the Earth and how much is released into the atmosphere.
"Continued on-the-ground monitoring of intact tropical forests is required to track the effects of accelerating environmental change. We need this more than ever, as our planet's last great tropical forests are threatened as never before."
The authors also highlight that tropical forests are still huge reservoirs of carbon, storing 250 billion tonnes of carbon in their trees alone. This storage is equivalent to 90 years of global fossil fuel emissions at today's level.
"African countries and the international community will need to seriously invest in preparation for ongoing climate change impacts in tropical regions."
Study author Professor Oliver Phillips, from University of Leeds, added "For too long the skills and potential of African and Amazonian scientists have been undervalued. We need to change this by ensuring their work is properly supported. It will fall to the next generation of African and Amazonian scientists to monitor these remarkable forests to help manage and protect them".
As tropical forests are likely to sequester less carbon than predicted, carbon budgets and emissions targets may need reassessing to account for this.
Professor Lewis said: "The immediate threats to tropical forests are deforestation, logging and fires. These require urgent action.
"In addition, stabilising Earth's climate is necessary to stabilise the carbon balance of intact tropical forests. By driving carbon dioxide emissions to net-zero even faster than currently envisaged, it would be possible to avoid intact tropical forests becoming a large source of carbon to the atmosphere. But that window of possibility is closing fast."Increasing tropical land use is disrupting the carbon cycle
More information: Asynchronous carbon sink saturation in African and Amazonian tropical forests, Nature (2020). DOI: 10.1038/s41586-020-2035-0 , https://nature.com/articles/s41586-020-2035-0
Study shows low carb diet may prevent, reverse age-related effects within the brain
Lilianne R. Mujica-Parodi, PhD. Credit: Stony Brook University
A study using neuroimaging led by Stony Brook University professor and lead author Lilianne R. Mujica-Parodi, Ph.D., and published in PNAS, reveals that neurobiological changes associated with aging can be seen at a much younger age than would be expected, in the late 40s. However, the study also suggests that this process may be prevented or reversed based on dietary changes that involve minimizing the consumption of simple carbohydrates.
To better understand how diet influences brain aging, the research team focused on the presymptomatic period during which prevention may be most effective. In the article titled "Diet modulates brain network stability, a biomarker for brain aging, in young adults," they showed, using large-scale life span neuroimaging datasets, that functional communication between brain regions destabilizes with age, typically in the late 40's, and that destabilization correlates with poorer cognition and accelerates with insulin resistance. Targeted experiments then showed this biomarker for brain aging to be reliably modulated with consumption of different fuel sources: glucose decreases, and ketones increase, the stability of brain networks. This effect was replicated across both changes to total diet as well as after drinking a fuel-specific calorie-matched supplement.
"What we found with these experiments involves both bad and good news," said Mujica-Parodi, a Professor in the Department of Biomedical Engineering with joint appointments in the College of Engineering & Applied Sciences and Renaissance School of Medicine at Stony Brook University, and a faculty member in the Laufer Center for Physical and Quantitative Biology. "The bad news is that we see the first signs of brain aging much earlier than was previously thought. However, the good news is that we may be able to prevent or reverse these effects with diet, mitigating the impact of encroaching hypometabolism by exchanging glucose for ketones as fuel for neurons."
What the researchers discovered, using neuroimaging of the brain, is that quite early on there is breakdown of communication between brain regions ("network stability").
"We think that, as people get older, their brains start to lose the ability to metabolize glucose efficiently, causing neurons to slowly starve, and brain networks to destabilize," said Mujica-Parodi. "Thus, we tested whether giving the brain a more efficient fuel source, in the form of ketones, either by following a low-carb diet or drinking ketone supplements, could provide the brain with greater energy. Even in younger individuals, this added energy further stabilized brain networks."
To conduct their experiments, brain network stability was established as a biomarker for aging by using two large-scale brain neuroimaging (fMRI) datasets totaling nearly 1,000 individuals, ages 18 to 88. Destabilization of brain networks was associated with impaired cognition and was accelerated with Type 2 diabetes, an illness that blocks neurons' ability to effectively metabolize glucose. To identify the mechanism as being specific to energy availability, the researchers then held age constant and scanned an additional 42 adults under the age of 50 years with fMRI. This allowed them to observe directly the impact of glucose and ketones on each individual's brain.
The brain's response to diet was tested in two ways. The first was holistic, comparing brain network stability after participants had spent one week on a standard (unrestricted) vs. low carb (for example: meat or fish with salad, but no sugar, grains, rice, starchy vegetables) diet. In a standard diet, the primary fuel metabolized is glucose, whereas in a low-carb diet, the primary fuel metabolized is ketones. However, there might have been other differences between diets driving the observed effects. Therefore, to isolate glucose vs. ketones as the crucial difference between the diets, an independent set of participants was scanned before and after drinking a small dose of glucose on one day, and ketones on the other, where the two fuels were individually weight-dosed and calorically matched. The results replicated, showing that the differences between the diets could be attributed to the type of fuel they provide to the brain.
Additional findings from the study included the following: Effects of brain aging emerged at age 47, with most rapid degeneration occurring at age 60. Even in younger adults, under age 50, dietary ketosis (whether achieved after one week of dietary change or 30 minutes after drinking ketones) increased overall brain activity and stabilized functional networks. This is thought to be due to the fact that ketones provide greater energy to cells than glucose, even when the fuels are calorically matched. This benefit has previously been shown for the heart, but the current set of experiments provides the first evidence for equivalent effects in the brain.
"This effect matters because brain aging, and especially dementia, are associated with "hypometabolism," in which neurons gradually lose the ability to effectively use glucose as fuel. Therefore, if we can increase the amount of energy available to the brain by using a different fuel, the hope is that we can restore the brain to more youthful functioning. In collaboration with Dr. Eva Ratai at Massachusetts General Hospital, we're currently addressing this question, by now extending our studies to older populations," said Mujica-Parodi.
"Additional research with collaborators at Children's National, under the direction of Dr. Nathan Smith, focuses on discovering the precise mechanisms by which fuel impacts signaling between neurons. Finally, in collaboration with Dr. Ken Dill and Dr. Steven Skiena, at Stony Brook, we're working on building a comprehensive computational model that can incorporate our understanding of the biology, from individual neurons to whole brains to cognition, as it develops."
More information: Lilianne R. Mujica-Parodi et al. Diet modulates brain network stability, a biomarker for brain aging, in young adults, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.1913042117
This self-portrait of NASA's Mars rover Curiosity combines dozens of exposures taken by the rover's Mars Hand Lens Imager (MAHLI) during the 177th Martian day, or sol, of Curiosity's work on Mars (Feb. 3, 2013), plus three exposures taken during Sol 270 (May 10, 2013) to update the appearance of part of the ground beside the rover. Credit: NASA
Organic compounds called thiophenes are found on Earth in coal, crude oil and oddly enough, in white truffles, the mushroom beloved by epicureans and wild pigs.
Thiophenes were also recently discovered on Mars, and Washington State University astrobiologist Dirk Schulze-Makuch thinks their presence would be consistent with the presence of early life on Mars.
Schulze-Makuch and Jacob Heinz with the Technische Universität in Berlin explore some of the possible pathways for thiophenes' origins on the red planet in a new paper published in the journal Astrobiology. Their work suggests that a biological process, most likely involving bacteria rather than a truffle though, may have played a role in the organic compound's existence in the Martian soil.
"We identified several biological pathways for thiophenes that seem more likely than chemical ones, but we still need proof," Dirk Schulze-Makuch said. "If you find thiophenes on Earth, then you would think they are biological, but on Mars, of course, the bar to prove that has to be quite a bit higher."
Thiophene molecules have four carbon atoms and a sulfur atom arranged in a ring, and both carbon and sulfur, are bio-essential elements. Yet Schulze-Makuch and Heinz could not exclude non-biological processes leading to the existence of these compounds on Mars.
Meteor impacts provide one possible abiotic explanation. Thiophenes can also be created through thermochemical sulfate reduction, a process that involves a set of compounds being heated to 248 degrees Fahrenheit (120 degrees Celsius) or more.
In the biological scenario, bacteria, which may have existed more than three billion years ago when Mars was warmer and wetter, could have facilitated a sulfate reduction process that results in thiophenes. There are also other pathways where the thiophenes themselves are broken down by bacteria.
While the Curiosity Rover has provided many clues, it uses techniques that break larger molecules up into components, so scientists can only look at the resulting fragments.
Further evidence should come from the next rover, the Rosalind Franklin, which is expected to launch in July 2020. It will be carrying a Mars Organic Molecule Analyzer, or MOMA, which uses a less destructive analyzing method that will allow for the collection of larger molecules.
Schulze-Makuch and Heinz recommend using the data collected by the next rover to look at carbon and sulfur isotopes. Isotopes are variations of the chemical elements that have different numbers of neutrons than the typical form, resulting in differences in mass.
"Organisms are 'lazy'. They would rather use the light isotope variations of the element because it costs them less energy," he said.
Organisms alter the ratios of heavy and light isotopes in the compounds they produce that are substantially different from the ratios found in their building blocks, which Schulze-Makuch calls "a telltale signal for life."
Yet even if the next rover returns this isotopic evidence, it may still not be enough to prove definitively that there is, or once was, life on Mars.
"As Carl Sagan said 'extraordinary claims require extraordinary evidence,'" Schulze-Makuch said. "I think the proof will really require that we actually send people there, and an astronaut looks through a microscope and sees a moving microbe."
How do social interactions change in the face of illness? As humans face potential global pandemics we look to nature for examples. Close observation of another highly social animal, the vampire bat, sheds light on how interactions change -- or do not change -- as individuals become sick. Credit: Rachel Page, STRI
As Italy urges tourists not to cancel their plans in the face of the coronavirus outbreak and a National Basketball Association memo reportedly encourages teammates to avoid hi-fives, a new study conducted at the Smithsonian Tropical Research Institute (STRI) in Panama takes a look at how social bonds change in response to illness in another highly social animal: the vampire bat. In these bats, just as in humans, strong family bonds were less affected by the appearance of disease than were weaker social relationships.
Vampire bats are an extremely social species. Their interactions range from grooming both family members and unrelated individuals, to saving another bat from starvation by sharing a regurgitated blood meal.
"By asking how different social connections change in response to sickness, we can better understand how social networks change as a pathogen spreads," said Gerry Carter, research associate at STRI and assistant professor of biology at The Ohio State University.
The lead author of the paper, Sebastian Stockmaier, did this project at STRI as part of his doctoral research at the University of Texas at Austin, advised by Dr. Daniel Bolnick at the University of Connecticut. Stockmaier injected vampire bats in a captive colony with a bacterial extract that challenged their immune systems, making them feel sick without harming their health or any risk of transmission. He then observed how the appearance of being sick would affect the ill bats' social relationships with other colony members.
Just as a sick person might choose to stop shaking hands with strangers but would still need to go to buy groceries, their results, published in the Journal of Animal Ecology, showed that sick vampire bats may reduce the amount of time they spend grooming—not a very important social interaction—but not food sharing—a more important social interaction.
Gerry Carter holding Desmotus rotundus. This research was done in a captive colony of vampire bats in Gamboa, Panama. Gerry Carter, now assistant professor at The Ohio State University, supervised this research. Credit: Beth King, STRI
Family relationships are very important: "A female vampire bat is less likely to groom an unrelated bat that is sick, but she won't reduce the amount of time grooming her own sick offspring," said Stockmaier.
"What we demonstrated in this study is that the type of social connection matters," Carter said. "Just as in the recent COVID-19 outbreak, we would expect that a virus transmitted by contact would spread mainly within family groups, because these social connections will not be reduced by sickness behavior. In vampire bats, as well as in humans, the most important social behaviors and relationships don't change as much when individuals are sick."
"This study underlies the importance of basic research," Page said. "Understanding how social interactions change in the face of illness is a key component in predicting the channels and speed at which a pathogen can spread across a population. Close observation of vampire bat behavior sheds light on how social animals interact, and how these interactions change—and importantly, when they do not change but persist—as individuals become sick.
More information: Sebastian Stockmaier et al, Sickness effects on social interactions depend on the type of behaviour and relationship, Journal of Animal Ecology (2020). DOI: 10.1111/1365-2656.13193
People can carry hazardous compounds from cigarette smoke that cling to their bodies and clothes and then release those compounds into non-smoking environments—exposing people nearby to cigarettes' adverse effects, a new study shows.
For the last decade, third-hand smoke has been described as the residual contamination from cigarette smoking that adheres to walls and other surfaces in places where smoking has previously occurred. For example, hotels and rental car companies have implemented smoking restrictions to limit this contaminating odor from their rooms and cars.
A team of researchers led by Yale's Drew Gentner shows for the first time that this third-hand smoke can travel in large quantities into indoor, non-smoking environments by way of humans. The research suggests that even if someone is in a room where no one has smoked, that person could still be exposed to many of the hazardous chemical compounds that make up cigarette smoke, depending on who else had entered the room or previously visited it. The results were published March 4 in Science Advances.
"In real-world conditions, we see concentrated emissions of hazardous gases coming from groups of people who were previously exposed to tobacco smoke as they enter a non-smoking location with strict regulations against indoor smoking," said Gentner, associate professor of chemical & environmental engineering. "People are substantial carriers of third-hand smoke contaminants to other environments. So, the idea that someone is protected from the potential health effects of cigarette smoke because they're not directly exposed to second-hand smoke is not the case."
Third-hand smoke was long considered stationary. Now, a new study shows people can carry it with them and transport it to other locations. Credit: Yale School of Engineering & Applied Science VIDEO
The researchers brought highly sensitive analytical instrumentation into a movie theater to track thousands of compounds, present as either gases or particles, over the course of a week. A diverse range of volatile organic compounds found in tobacco smoke spiked dramatically when certain audiences arrived for the movies. These increases were minor for G-rated movies, while audiences for R-rated movies—which included moviegoers more likely to smoke or to be exposed to smoke—consistently released much larger quantities of these compounds into the theater. The relative proportions of these emitted compounds confirmed that they were from slightly aged cigarette smoke.
"Despite regulations preventing people from smoking indoors, near entryways, and near air intakes, hazardous chemicals from cigarette smoke are still making their way indoors," said Roger Sheu, a Ph.D. student in Gentner's lab and lead author of the study.
The amount of these hazardous and reactive gases wasn't trivial, the researchers said. The gas emissions were equal to that of being exposed to 1-10 cigarettes of secondhand smoke in a one-hour period. These emissions and air concentrations peaked upon audience arrival and decreased over time, but not completely, even when the audiences left. In many cases, the movie-goers left a persistent contamination observable the following days in the unoccupied theater. The researchers said that is because the chemicals don't remain entirely in the air, but are also adsorbed onto various surfaces and furnishings, just as it does with third-hand smoke contamination in places where smoking has occurred.
The researchers also found a predominance of nitrogen-containing compounds from cigarettes, which would have migrated from people to other indoor surfaces.
"In particular, we noticed that nicotine was the most prominent compound by far," said co-author Jenna Ditto, a Ph.D. student in Gentner's lab.
The researchers said these results on human transport of third-hand smoke now help to explain why previous studies had found notable quantities of nicotine on surfaces in numerous non-smoking environments.
The researchers emphasized that avoiding movie theaters is not the solution to avoiding third-hand smoke. In fact, the theater used for the study is modern, large, and well-ventilated, which reduced the effect of the emissions on concentrations of hazardous compounds in the room. In less well-ventilated spaces—such as public transit, bars, offices, and homes—similar third-hand smoke emissions would likely result in considerably higher concentrations of many of these compounds.
More information: "Human transport of thirdhand tobacco smoke: A prominent source of hazardous air pollutants into indoor nonsmoking environments," Science Advances (2020). advances.sciencemag.org/content/6/10/eaay4109
Researchers one step closer to creating organic batteries
York University researchers have discovered a way to make Lithium-powered batteries more environmentally friendly while retaining performance, stability and storage capacity. Their latest breakthrough is the creation of a new carbon-based organic molecule that can replace the cobalt now used in cathodes or positive electrodes in lithium-ion batteries. The new material addresses the shortcomings of the inorganic material while maintaining performance. Credit: Paola Scattolon
York University researchers have discovered a way to make Lithium-powered batteries more environmentally friendly while retaining performance, stability and storage capacity.
Lithium-ion batteries use toxic,heavy metalswhich can impact the environment when they are extracted from the ground and are difficult to dispose of safely. Cobalt is one of those heavy metals, used inbattery electrodes. Part of the problem is that lithium and cobalt are not abundantly available, and supplies are dwindling.
Using organic materials are the way forward and that has scientists like Professor Thomas Baumgartner of the Faculty of Science and his team busy developing and testing new molecules to find the right ones to replace the rare metals currently in use.
"Organic electrode materials are considered to be extremely promising materials for sustainable batteries with high power capabilities," he says.
Their latest breakthrough is the creation of a new carbon-based organic molecule that can replace the cobalt now used in cathodes or positive electrodes in lithium-ion batteries. The new material addresses the shortcomings of the inorganic material while maintaining performance.
"Electrodes made with organic materials can make large-scale manufacturing, recycling or disposing of these elements more environmentally friendly," says Baumgartner. "The goal is to create sustainable batteries that are stable and have equally as good if not better capacity."
The research is published and featured on the cover of the March edition of the journal Batteries & Supercaps, a ChemPubSoc publication.
"With this particular class of molecules that we've made, the electroactive component is very suitable for batteries as it's very good at storing electrical charges and has good long-term stability," he says.
Baumgartner and his group previously reported on the electroactive component in a paper published in the journal Advanced Energy Materials.
"We have optimized this electroactive component and put it in a battery. It has a very good voltage, up to the 3.5 volts, which is really where current batteries are now," he says. "It's an important step forward in making fully organic and sustainable batteries."
Baumgartner, along with postdoctoral researchers Colin Brides and Monika Stolar, have also demonstrated that this material is stable in long-term operation with the ability to charge and discharge for 500 cycles. One of the downsides of inorganic electrodes is that they generate significant heat when charging and require limited discharging rates for safety reasons. This new molecule addresses that shortcoming.
The next step, says Baumgartner, is to improve the capacity further. His team is currently developing the next generation of molecules that show promise in being able to increase current capacity.
More information: Colin R. Bridges et al, Phosphaviologen‐Based Pyrene‐Carbon Nanotube Composites for Stable Battery Electrodes, Batteries & Supercaps (2019). DOI: 10.1002/batt.201900164
