Extreme exoplanet even more exotic than originally thought

Considered an ultra-hot Jupiter -- a place where iron gets vaporized, condenses on the night side and then falls from the sky like rain -- the fiery, inferno-like WASP-76b exoplanet may be even more sizzling than scientists had realized.

An international team, led by scientists at Cornell University, University of Toronto and Queen's University Belfast, reports the discovery of ionized calcium on the planet -- suggesting an atmospheric temperature higher than previously thought, or strong upper atmosphere winds.

The discovery was made in high-resolution spectra obtained with Gemini North near the summit of Mauna Kea in Hawaii.

Hot Jupiters are named for their high temperatures, due to proximity to their stars. WASP-76b, discovered in 2016, is about 640 light-years from Earth, but so close to its F-type star, which is slightly hotter than the sun, that the giant planet completes one orbit every 1.8 Earth days.

The research results are the first of a multiyear, Cornell-led project, Exoplanets with Gemini Spectroscopy survey, or ExoGemS, that explores the diversity of planetary atmospheres.

"As we do remote sensing of dozens of exoplanets, spanning a range of masses and temperatures, we will develop a more complete picture of the true diversity of alien worlds -- from those hot enough to harbor iron rain to others with more moderate climates, from those heftier than Jupiter to others not much bigger than the Earth," said co-author Ray Jayawardhana, Harold Tanner Dean of the College of Arts and Sciences at Cornell University and a professor of astronomy.

"It's remarkable that with today's telescopes and instruments, we can already learn so much about the atmospheres -- their constituents, physical properties, presence of clouds and even large-scale wind patterns -- of planets that are orbiting stars hundreds of light-years away," Jayawardhana said.

The group spotted a rare trio of spectral lines in highly sensitive observations of the exoplanet WASP-76b's atmosphere, published in the Astrophysical Journal Letters on Sept. 28 and presented on Oct. 5 at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society.

"We're seeing so much calcium; it's a really strong feature," said first author Emily Deibert, a University of Toronto doctoral student, whose adviser is Jayawardhana.

"This spectral signature of ionized calcium could indicate that the exoplanet has very strong upper atmosphere winds," Deibert said. "Or the atmospheric temperature on the exoplanet is much higher than we thought."

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Hidden mangrove forest in the Yucatan peninsula reveals ancient sea levels

Deep in the heart of the Yucatan Peninsula, an ancient mangrove ecosystem flourishes more than 200 kilometers (124 miles) from the nearest ocean. This is unusual because mangroves -- salt-tolerant trees, shrubs, and palms -- are typically found along tropical and subtropical coastlines.

A new study led by researchers across the University of California system in the United States and researchers in Mexico focuses on this luxuriant red mangrove forest. This "lost world" is located far from the coast along the banks of the San Pedro Martir River, which runs from the El Petén rainforests in Guatemala to the Balancán region in Tabasco, Mexico.

Because the red mangrove (Rhizophora mangle) and other species present in this unique ecosystem are only known to grow in salt water or somewhat salty water, the binational team set out to discover how the coastal mangroves were established so deep inland in fresh water completely isolated from the ocean. Their findings were published Oct. 4 in the Proceedings of the National Academy of Sciences.

Integrating genetic, geologic, and vegetation data with sea-level modeling, the study provides a first glimpse of an ancient coastal ecosystem. The researchers found that the San Pedro mangrove forests reached their current location during the last interglacial period, some 125,000 years ago, and have persisted there in isolation as the oceans receded during the last glaciation.

The study provides a snapshot of the global environment during the last interglacial period, when the Earth became very warm and polar ice caps melted entirely, making global sea levels much higher than they are today.

"The most amazing part of this study is that we were able to examine a mangrove ecosystem that has been trapped in time for more than 100,000 years," said study co-author Octavio Aburto-Oropeza, a marine ecologist at Scripps Institution of Oceanography at UC San Diego and a PEW Marine Fellow. "There is certainly more to discover about how the many species in this ecosystem adapted throughout different environmental conditions over the past 100,000 years. Studying these past adaptations will be very important for us to better understand future conditions in a changing climate."

Combining multiple lines of evidence, the study demonstrates that the rare and unique mangrove ecosystem of the San Pedro River is a relict -- that is, organisms that have survived from an earlier period -- from a past warmer world when relative sea levels were six to nine meters (20 to 30 feet) higher than at present, high enough to flood the Tabasco lowlands of Mexico and reach what today are tropical rainforests on the banks of the San Pedro River.

The study highlights the extensive landscape impacts of past climate change on the world's coastlines and shows that during the last interglacial, much of the Gulf of Mexico coastal lowlands were under water. Aside from providing an important glimpse of the past and revealing the changes suffered by the Mexican tropics during the ice ages, these findings also open opportunities to better understand future scenarios of relative sea-level rise as climate change progresses in a human-dominated world.

Carlos Burelo, a botanist at the Universidad Juárez Autónoma de Tabasco and a native of the region, drew the attention of the rest of the team towards the existence of this relict ecosystem in 2016. "I used to fish here and play on these mangroves as a kid, but we never knew precisely how they got there," said Burelo. "That was the driving question that brought the team together."

Burelo's field work and biodiversity surveys in the region established the solid foundation of the study. His remarkable discovery of the ancient ecosystem is documented in "Memories of the Future: the modern discovery of a relict ecosystem," anaward-winning short film produced by Scripps alumnus Ben Fiscella Meissner (MAS MBC '17).

Felipe Zapata and Claudia Henriquez of UCLA led the genetic work to estimate the origin and age of the relict forest. Sequencing segments of the genomes of the red mangrove trees, they were able to establish that this ecosystem migrated from the coasts of the Gulf of Mexico into the San Pedro River over 100,000 years ago and stayed there in isolation after the ocean receded when temperatures dropped. While mangroves are the most notable species in the forest, they found nearly 100 other smaller species that also have a lineage from the ocean.

"This discovery is extraordinary," said Zapata. "Not only are the red mangroves here with their origins printed in their DNA, but the whole coastal lagoon ecosystem of the last interglacial has found refuge here."

Paula Ezcurra, science program manager at the Climate Science Alliance, carried out the sea-level modeling, noting that the coastal plains of the southern Gulf of Mexico lie so low that a relatively small change in sea level can produce dramatic effects inland. She said a fascinating piece of this study is how it highlights the benefits of working collaboratively among scientists from different disciplines.

"Each piece of the story alone is not sufficient, but when taken together, the genetics, geology, botany, and field observations tell an incredible story. Each researcher involved lent their expertise that allowed us to uncover the mystery of a 100,000+ year-old forest," said Ezcurra, an alumna of Scripps Oceanography (MAS CSP '17).

The field work was led by the ecologists on the team -- Octavio Aburto-Oropeza, Paula Ezcurra, Exequiel Ezcurra of UC Riverside, and Sula Vanderplank of Pronatura Noroeste. Visiting the study sites several times starting in 2016, they collected rocks, sediments and fossils to analyze in the lab, helping them pinpoint evidence from the past that is consistent with a marine environment.

The authors note that the region surrounding the study sites was systematically deforested in the 1970s by a misguided development plan; the banks of the San Pedro River were only spared because the bulldozers could not reach it. The area is still threatened by human activities, so the researchers stressed the need to protect this biologically important area in the future.

Read more at Science Daily

Brain-circuit discovery may help explain sex differences in binge drinking

A brain circuit that works as a "brake" on binge alcohol drinking may help explain male-female differences invulnerability to alcohol use disorders, according to a preclinical study led by scientists at Weill Cornell Medicine.

In the study, which appeared August 23 in Nature Communications, the researchers examined a brain region in mice called the bed nucleus of the stria terminalis (BNST) -- a major node in a stress-response network whose activity in humans has been linked to binge drinking behaviors. The researchers found that one important population of BNST neurons is more excitable in female mice than in males, helping to account for female mice's greater susceptibility to binge drinking.

The researchers also found that a distant cluster of neurons called the paraventricular nucleus of the thalamus (PVT), which is wired into the BNST, acts as a brake on its activity and has a stronger influence on the female BNST compared with the male BNST. Thus, the PVT is able to curb excessive alcohol consumption through this circuit brake in female mice but not males. While females may be offered more protection through this mechanism, they may also be more vulnerable to disease when this brake is disrupted.

"This study highlights that there are sex differences in the brain biology that controls alcohol drinking behaviors, and we really need to understand those differences if we're going to develop optimal treatments for alcohol use disorder," said senior author Dr. Kristen Pleil, assistant professor of pharmacology at Weill Cornell Medicine.

Women tend to consume less alcohol than men do, but researchers believe that is due mostly to cultural factors, and in recent decades that gender gap has narrowed significantly, especially among younger women. Women may in fact have an inherently greater vulnerability to alcohol use disorders, for reasons that lie deep within mammalian biology.

"Females across mammalian species, compared to males, display greater binge drinking and progress from first alcohol use to disease states more quickly," Dr. Pleil said. "But there has been hardly any research on the neural details that underlie this sex difference."

For the study, she and her team showed that BNST neurons, whose activity enhances binge-drinking behavior in mice, are more excitable and likely to fire spontaneously in female mice compared to males, apparently due to greater stimulation from other brain regions wired into the BNST. This higher excitability in females means that more inhibition of the female BNST is needed to prevent or reduce binge-drinking behavior.

The researchers found that the brain region with the densest projection to the BNST is the PVT -- which works as a natural inhibitor of BNST activity, more so in female mice. They found that reducing the strength of this PVT projection promotes binge alcohol drinking behavior in female mice, but not in male mice, whose BNST activity is lower to begin with.

The results, Dr. Pleil said, indicate that although this BNST-driven stress response circuit is tuned to be more excitable in females, it is also more heavily regulated in females, perhaps as an adaptation for more female-specific behaviors.

What behaviors? That is still unclear, although the researchers found that altering BNST activity via the PVT had no effect on the mice's intake of sweet-tasting sucrose -- suggesting that the PVT-BNST circuit, with its greater sensitivity and tighter regulation in females, evolved for something more specific than guiding general reward-seeking behaviors.

"Female mammals have a different set of goals compared to males, and may need to be more sensitive to different types of reward," Dr. Pleil said.

She added that sex differences in the PVT-BNST circuit may be relevant to sex differences not only in alcohol-use disorders but also in anxiety disorders -- which are much more common in women and frequently co-occur with binge drinking. The researchers found that enhancing PVT inhibition of the BNST led to reduced avoidance behaviors -- a proxy for reduced anxiety in humans -- in both male and female mice.

Read more at Science Daily

Mitigating lung damage, mortality due to SARS-CoV-2

In a new paper, researchers at the University of Illinois Chicago report that a drug approved for treating patients with autoimmune disease helped to prevent lung damage and death in mice infected with the SARS-CoV-2 virus, which causes COVID-19 in humans.

The results of their study provide strong evidence that inflammatory lung vascular leakage -- or leaky lungs -- is a key feature of COVID-19 illness. Vascular leakage can be caused by severe inflammation and results in a buildup of fluid in the lungs, which interferes with oxygen uptake. Mice infected with SARS-CoV-2 showed very clear and early signs of leakage from the blood vessels of the lung.

The research also suggests targeted drug treatments that suppress only select immune system pathways, like the rheumatoid arthritis drug used in the study that targets the molecular receptor called IL-1, might be a more suitable therapy for COVID-19 patients than drug treatments that suppress the entire immune system.

The study was led by senior author Asrar Malik, head of the department of pharmacology and regenerative medicine at the College of Medicine, and by co-senior author Jalees Rehman, professor of medicine in the department of pharmacology and regenerative medicine.

"With COVID-19, we need to strike a balance. On the one hand, we need a strong immune system to eliminate the virus. On the other hand, several studies suggest that in patients with severe COVID-19, the immune system can go overboard and even cause damage to our own body," Rehman said. "So, while we need the immune system to work efficiently, we also need to prevent it from becoming hyperactive and causing collateral damage."

The need for balance is why the UIC researchers decided to study the effects of a drug that works on only one targeted immune system pathway and see if that would help prevent SARS-CoV-2-induced leaky lungs.

For the study, the researchers observed mice infected with the virus and tracked the progression of illness. They saw that the mice quickly showed symptoms like weight loss, fluid buildup in the lungs from leaky lung blood vessels, and even indicators of lung scarring, such as increased collagen levels in lung tissue.

"This is important evidence that blood vessel leakage in the lungs is a key feature of severe COVID-19 and that treatments which prevent or reduce vascular leakage warrant further study," Rehman said.

The researchers also treated some of the mice with the approved autoimmune disease drug, called anakinra, to block the IL-1 receptor, a key molecule regulating inflammation.

"We saw that the mice who received the drug had reduced signs of disease -- including less lung fluid buildup and less scarring of the lungs -- and better survival," Rehman said.

Rehman said these findings pave the way for helping COVID-19 patients and illuminate the need for more research on targeted, personalized treatments.

"Obviously, the best approach to reducing short-term and long-term damage as a result of COVID-19 is to get vaccinated and reduce the risk of SARS-CoV-2 infection as well as the risk of severe disease. However, the hesitancy of many individuals to get vaccinated as well as the lack of access to vaccines in many parts of the world means that we will continue to see patients with severe COVID-19 in the near future. Our results suggest that it is possible to identify a select a vulnerable COVID-19 patient population that is most likely to benefit from this therapy," Rehman said.

In their paper, "Interleukin-1RA Mitigates SARS-CoV-2-Induced Inflammatory Lung Vascular Leakage and Mortality in Humanized K18-hACE-2 Mice," the researchers hypothesize that by assessing the level of certain inflammatory signals in patients, such as the activation of the IL-1 receptor pathway, scientists could identify when a patient's immune system might be heading into overdrive and use a targeted immunosuppressant, like anakinra, to keep inflammation at the right balance.

"It is important to get the right drug to the right patient at the right time, and this study shines a light on a path forward for clinical trials that are investigating this drug and others that target specific components of the immune system," Rehman said.

Read more at Science Daily

'Mini psyches' give insights into mysterious metal-rich near-earth asteroids

Metal-rich near-Earth asteroids, or NEAs, are rare, but their presence provides the intriguing possibility that iron, nickel and cobalt could someday be mined for use on Earth or in Space.

New research, published in the Planetary Science Journal, investigated two metal-rich asteroids in our own cosmic backyard to learn more about their origins, compositions and relationships with meteorites found on Earth.

These metal-rich NEAs were thought to be created when the cores of developing planets were catastrophically destroyed early in the solar system's history, but little more is known about them. A team of students co-led by University of Arizona planetary science associate professor Vishnu Reddy studied asteroids 1986 DA and 2016 ED85 and discovered that their spectral signatures are quite similar to asteroid 16 Psyche, the largest metal-rich body in the solar system. Psyche, located in the main asteroid belt between the orbits of Mars and Jupiter rather than near Earth, is the target of NASA's Psyche mission.

"Our analysis shows that both NEAs have surfaces with 85% metal such as iron and nickel and 15% silicate material, which is basically rock," said lead author Juan Sanchez, who is based at the Planetary Science Institute. "These asteroids are similar to some stony-iron meteorites such as mesosiderites found on Earth."

Astronomers have been speculating as to what the surface of Psyche is made of for decades. By studying metal-rich NEAs that come close to the Earth, they hope to identify specific meteorites that resemble Psyche's surface.

"We started a compositional survey of the NEA population in 2005, when I was a graduate student, with the goal of identifying and characterizing rare NEAs such as these metal-rich asteroids," said Reddy, principal investigator of the NASA grant that funded the work. "It is rewarding that we have discovered these 'mini Psyches' so close to the Earth."

"For perspective, a 50-meter (164-foot) metallic object similar to the two asteroids we studied created the Meteor Crater in Arizona," said Adam Battle, who is a co-author of the paper along with fellow Lunar and Planetary Laboratory graduate students Benjamin Sharkey and Theodore Kareta, and David Cantillo, an undergraduate student in the Department of Geosciences.

The paper also explored the mining potential of 1986 DA and found that the amount of iron, nickel and cobalt that could be present on the asteroid would exceed the global reserves of these metals.

Additionally, when an asteroid is catastrophically destroyed, it produces what is called an asteroid family -- a bunch of small asteroids that share similar compositions and orbital paths.

The team used the compositions and orbits of asteroids 1986 DA and 2016 ED85 to identify four possible asteroid families in the outer region of the main asteroid belt, which is home to the largest reservoir of small bodies in the inner part of the solar system. This also happens to be the region where most of the largest known metallic asteroids including 16 Psyche reside.

"We believe that these two 'mini Psyches' are probably fragments from a large metallic asteroid in the main belt, but not 16 Psyche itself," Cantillo said. "It's possible that some of the iron and stony-iron meteorites found on Earth could have also come from that region in the solar system too."

Read more at Science Daily

Earliest evidence yet of huge hippos in Britain

Palaeobiologists have unearthed the earliest evidence yet of hippos in the UK.

Excavations at Westbury Cave in Somerset, led by University of Leicester PhD student Neil Adams, uncovered a million-year-old hippo tooth which shows the animal roamed Britain much earlier than previously thought.

In a new study published in the Journal of Quaternary Science and co-authored with researchers from Royal Holloway, University of London, the tooth is identified as belonging to an extinct species of hippo called Hippopotamus antiquus, which ranged across Europe in warm periods during the Ice Age.

It was much larger than the modern African hippo, weighing around 3 tonnes, and was even more reliant on aquatic habitats than its living relative.

Research demonstrates that the fossil is over one million years old, eclipsing the previous record of hippo in the UK by at least 300,000 years and filling an important gap in the British fossil record.

Neil Adams, PhD researcher in the Centre for Palaeobiology Research at the University of Leicester and Earth Collections Project Officer at the Oxford University Museum of Natural History, said:

"It was very exciting to come across a hippo tooth during our recent excavations at Westbury Cave. It is not only the first record of hippo from the site, but also the first known hippo fossil from any site in Britain older than 750,000 years.

"Erosion caused by the coming and going of ice sheets, as well as the gradual uplift of the land, has removed large parts of the deposits of this age in Britain. Our comparisons with sites across Europe show that Westbury Cave is an important exception and the new hippo dates to a previously unrecognised warm period in the British fossil record."

Scientists know remarkably little about the fauna, flora and environments in Britain between about 1.8 and 0.8 million years ago, a key period when early humans were beginning to occupy Europe.

But new research at Westbury Cave is helping to fill in this gap. It shows that during this interval there were periods warm and wet enough to allow hippos to migrate all the way from the Mediterranean to southern England.

Professor Danielle Schreve, Professor of Quaternary Science at Royal Holloway and co-author of the study, said:

"Hippos are not only fabulous animals to find but they also reveal evidence about past climates. Many megafaunal species (those over a tonne in weight) are quite broadly tolerant of temperature fluctuations but in contrast, we know modern hippos cannot cope with seasonally frozen water bodies.

"Our research has demonstrated that in the fossil record, hippos are only found in Britain during periods of climatic warmth, when summer temperatures were a little warmer than today but most importantly, winter temperatures were above freezing."

By examining the European fossil record, the research team show that the Westbury Cave hippo was likely to have lived during a particularly warm period around 1.1 to 1.0 million years ago.

Hippo remains of this age are known from Germany, France and the Netherlands and the new fossil from Somerset represents a previously unknown part of this colonisation of northwest Europe.

Read more at Science Daily

How apples get their shapes

Apples are among the oldest and most recognizable fruits in the world. But have you ever really considered an apple's shape? Apples are relatively spherical except for that characteristic dimple at the top where the stem grows.

How do apples grow that distinctive shape?

Now, a team of mathematicians and physicists have used observations, lab experiments, theory and computation to understand the growth and form of the cusp of an apple.

The paper is published in Nature Physics.

"Biological shapes are often organized by the presence of structures that serve as focal points," said L Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, of Organismic and Evolutionary Biology, and of Physics at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and senior author of the study. "These focal points can sometimes take the form of singularities where deformations are localized. A ubiquitous example is seen in the cusp of an apple, the inward dimple where the stalk meets the fruit."

Mahadevan had already developed a simple theory to explain the form and growth of apples but the project began to bear fruit when the researchers were able to connect observations of real apples at different growth stages and gel experiments to mimic the growth along with theory and computations.

The research team began by collecting apples at various growth stages from an orchard at Peterhouse College at University of Cambridge in the U.K., (the alma mater of another famous apple lover, Sir Isaac Newton).

Using those apples, the team mapped the growth of the dimple, or cusp as they called it, over time.

To understand the evolution of the shape of the apple and the cusp in particular, the researchers turned to a long-standing mathematical theory known as singularity theory. Singularity theory is used to describe a host of different phenomena, from black holes, to more mundane examples such as the light patterns at the bottom of a swimming pool, droplet breakup and crack propagation.

"What is exciting about singularities is that they are universal. The apple cusp has nothing in common with light patterns in a swimming pool, or a droplet breaking off from a column of water, yet it makes the same shape as they do," said Thomas Michaels, a former postdoctoral fellow at SEAS and co-lead author of the paper, now at University College London. "The concept of universality goes very deep and can be very useful because it connects singular phenomena observed in very different physical systems."

Building from this theoretical framework, the researchers used numerical simulation to understand how differential growth between the fruit cortex and the core drives formation of the cusp. They then corroborated the simulations with experiments which mimicked the growth of apples using gel that swelled over time. The experiments showed that different rates of growth between the bulk of the apple and the stalk region resulted in the dimple-like cusp.

"Being able to control and replay morphogenesis of singular cusps in the laboratory with simple material toolkits was particularly exciting," said Aditi Chakrabarti, a postdoctoral fellow at SEAS and co-author of the paper. "Varying the geometry and composition of the gel mimics showed how multiple cusps form, as seen in some apples and other drupes, such as peaches, apricots, cherries and plums."

The team found that the underlying fruit anatomy along with mechanical instability may play joint roles in giving rise to multiple cusps in fruits.

"Morphogenesis, literally the origin of shape, is one of the grand questions in biology," said Mahadevan. "The shape of the humble apple has allowed us to probe some physical aspects of a biological singularity. Of course, we now need to understand the molecular and cellular mechanisms behind the formation of the cusp, as we move slowly towards a broader theory of biological shape."

Read more at Science Daily

When the western US burns, the east also gets sick

While most of the largest U.S. wildfires occur in the Western U.S., almost three-quarters of the smoke-related deaths and visits to the emergency room for asthma occur east of the Rocky Mountains.

Smoke exposure, whether from wildfires or local burning, contributes to health problems across the U.S., but the impacts vary by region. A new study finds that smoke contributes to a larger percentage of health problems in the West, but affects greater numbers of people in the East -- possibly when they aren't even aware of the smoky air.

The new study was published in GeoHealth, AGU's journal investigating the intersection of human and planetary health for a sustainable future.

In the West, where population density is generally lower and smoke concentrations are typically higher, smoke played a larger role in the number of asthma complaints and ER visits, contributing to more than 1% of annual visits in some years. In the East, with its high population density and lower smoke concentrations, there were a higher number of visits overall, even though a smaller percentage were related to smoke (0.3% to 0.6%).

The researchers estimate that long-term smoke exposure results in about 6,300 extra deaths each year, with the highest numbers occurring in the most populous states. Only 1,700 of those deaths occurred in the West.

Fires throw tremendous amounts of pollutants into the air, including toxic gases and soot. Smoke contains tiny particles smaller than 2.5 microns, called PM2.5, that enter the lungs and contribute to multiple health problems. Short-term exposure to PM2.5 from smoke is linked to respiratory health problems, like asthma attacks, and the long-term effects of PM2.5 from smoke are not fully understood. Research on PM2.5 from urban pollution suggests that exposure is linked to lung cancer, heart disease and an overall higher chance of death.

"Large wildfires are projected to increase in frequency and burned area in the Western U.S. Because of that, and projected decreases in urban-sourced PM2.5, fires are expected to become the dominant source of PM2.5 in the U.S. by the end of the century," said atmospheric scientist and first author Katelyn O'Dell. O'Dell was formerly a graduate student at Colorado State University but is now a postdoctoral researcher at George Washington University. "We wanted to study the impacts of wildfire smoke specifically on health so we can better prepare for that future, when we expect to have more smoke in our lives."

O'Dell collaborated with epidemiologists at Colorado State University to perform a health impact assessment. The researchers estimated the fraction of asthma ER visits and hospitalizations resulting from PM2.5 in smoke across the country from 2006 to 2018. They used existing data on asthma hospital visits and daily local estimates of PM2.5 based on readings from instruments at ground level and satellite data showing the location of smoke in the atmosphere.

The new study also included the first analysis of the health impacts of 18 hazardous air pollutants (HAPs) present in smoke, such as formaldehyde and benzene. The researchers determined that HAPs are likely a less important but more uncertain factor than PM2.5 in the health problems caused by smoke exposure.

As smoke pollution is likely to increase, the researchers argue that the U.S. needs better national smoke forecasting and alerts so that people in downwind regions know when to take precautions like wearing a mask, limiting time outside and using indoor air purifiers.

"We talk about smoke in the West so much, but we don't often talk about smoke in the East," O'Dell said. "I wonder if there's a lack of awareness because you think, 'Oh, that's a Western problem.'"

O'Dell emphasized that their study didn't determine the source of the smoke affecting each region and that local burning and Canadian fires also contribute to smoky air in the Eastern U.S. She said that establishing the source of the smoke impacting health in each region is an important next step.

Tarik Benmarhnia, a climate change epidemiologist at the University of California, San Diego, who was not involved in the study, agreed that we need better smoke warning systems, especially for farm workers and others who labor outside. He pointed out that while smoke plumes impact entire regions, they don't affect all residents equally. Age, race, ethnicity, exposure to other types of air pollution -- such as from traffic -- and pre-existing health conditions can all put a person at higher risk of developing health problems from smoke. He said that future research should investigate these disparities.

Read more at Science Daily

Using dunes to interpret wind on Mars

Dunes develop when wind-blown sand organizes into patterns, most often in deserts and arid or semi-arid parts of the world. Every continent on Earth has dune fields, but dunes and dune-like sand patterns are also found across the solar system: on Mars, Venus, Titan, Comet 67P, and Pluto. On Earth, weather stations measure the wind speed and direction, allowing us to predict and understand airflow in the atmosphere.

On other planets and planetary bodies, we do not yet have weather stations measuring the winds (with a few recent exceptions on Mars only). Without a way to directly measure wind on the surface of another planet, we can use the patterns in dunes to interpret what the wind must be doing, based on our knowledge of dunes on Earth. Furthermore, by studying dunes across planets, we can get a better understanding of how wind and sand behave in general.

In this Geology paper, published today, Mackenzie Day of the University of California Los Angeles focuses on what happens when two dunes collide.

"On Earth, we know that dunes collide, combine, link, and merge all the time," says Day. This is what drives changes in dune-field patterns over time. When this happens, the dune-dune interaction leaves behind a particular pattern in the sand, but that pattern is usually covered by actively moving sand and difficult to see without special tools."

On Mars, many dunes look and behave similar to dunes on Earth, but in addition Mars hosts patterns of organized sand that are dune-like but have some differences that have yet to be explained by the scientific community. Whether or not these unusual features, sometimes called "transverse aeolian ridges" or "megaripples," are formed like dunes has been long debated.

"In this work, says Day, I show that these unusual wind-blown sand ridges sometimes show on their surfaces the pattern that forms when two dunes combine."

In the Iapygia region of Mars, transverse aeolian ridges incorporated both light and dark sands, leading to light-dark banding in the upwind side of the ridges. Banding occurring only on one side of the ridges suggests that the banding formed as the ridges migrated. Furthermore, the dune-interaction pattern known from Earth can be seen in some ridges where the banding is truncated and then reconnects, just like two dunes touching and then combining downwind.

The pattern associated with dune-interactions only forms when two dunes combine, therefore seeing it in these martian sand ridges demonstrates that these enigmatic features (like those shown in the image attached) behave like dunes on Earth. "Just like dunes on Earth, transvers aeolian ridges on Mars migrate, combine, and develop complex patterns in response to the wind."

Transverse aeolian ridges are incredibly common on Mars, and the results of this work allow us to better interpret the wind at the surface of Mars using these dune-like features.

Read more at Science Daily

Primordial ‘hyper-eye’ discovered

An international research team has found an eye system in trilobites of the suborder Phacopina from the Devonian (390 million years B.P.) that is unique in the animal kingdom: each of the about 200 lenses of a hyper-facet eye spans a group of six normal compound-eye-facets, forming a compound eye itself. In addition to the hyper-facetted eyes, the researchers, led by zoologist Dr. Brigitte Schoenemann at the University of Cologne's Institute for Didactics of Biology, identified a structure that they believe to be a local neural network which directly processed the information from this special eye, and an optic nerve that carried information from the eye to the brain. The article, 'A 390 million-year-old hyper-compound eye in Devonian phacopid trilobites,' has been published in Scientific Reports.

Trilobites are arthropods that once inhabited the world's oceans and became extinct about 251 million years ago. The discovery was made when Schoenemann and her colleagues examined X-ray images taken by radiologist and amateur paleontologist Wilhelm Stürmer in the 1970s. Stürmer had already believed the filaments under the trilobite eyes to be nerves, or a light guiding system. Schoenemann also found markings by Stürmer on the images designating the six subfacets. However, scientists at the time did not believe his interpretations. Now, however, the re-examination of the images and verification with modern computed tomography succeeded in confirming his conjectures.

Most trilobites had compound eyes similar to those that are still found in insects today: a large number of hexagonal facets form the eye. There are usually eight photoreceptors under each facet. Comparable to the image of a computer screen, which is built up from individual pixels, an image is built up from the individual facets. In dragonflies, there are up to ten thousand individual facets. In order to produce a coherent image, the facets must be very close together and connected by neurons. However, in the trilobite suborder Phacopinae, the externally visible lenses of the compound eyes are much larger, up to 1 mm in diameter and more. In addition, they are set farther apart. Until now, scientists had not been able to explain this because space is wasted where light could be captured. Since a small cup sits under the lens, they assumed that at the bottom of the capsule was a small retina comparable to that of humans.

Dr Schoenemann's analysis of Wilhelm Stürmer's 40-year-old X-ray archive now suggests a different interpretation: a hyper-compound eye. Each phacopid had two eyes, one on the left and one on the right. 'Each of these eyes consisted of about 200 lenses up to 1 mm in size,' said Schoenemann. 'Under each of these lenses, in turn, at least 6 facets are set up, each of which together again makes up a small compound eye. So we have about 200 compound eyes (one under each lens) in one eye.' These sub-facets are arranged in either one ring or two rings. 'Underneath sat a foam-like nest that was probably a small neural network to process the signals,' the zoologist added. The filaments Stürmer found in fact did turn out to be nerves leading from the eyes to the trilobite's brain. Further examination with modern computer tomography confirmed these structures.

Wilhelm Stürmer was the head of the X-ray department at Siemens and an avid paleontologist. With a VW bus equipped as an X-ray station, he drove from quarry to quarry to X-ray fossils. Among other things, he discovered structures called filaments under the animals' eyes, which he thought were fossils of soft tissues, especially optic nerves. 'At that time, the consensus was that only bones and teeth, the hard parts of living things, could be seen in the fossils, but not the soft parts, such as intestines or nerves,' Schoenemann explained. Stürmer's heir gave the zoologist his archive. But the hobby-paleontologist had not only correctly identified the optic nerve, she notes: 'On an X-ray negative, there was an arrow in red pen pointing to the structure of the six lower facets under a main lens. This probably indicated that Stürmer had already recognized the hyper-compound eye.' At the time, however, scientists assumed that nerves did not fossilize, nor that light guides existed in natural optical system. Optical fibres were not discovered until the 1980s in the compound eyes of a deep-sea crab.

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