What happens in the brain while daydreaming?

You are sitting quietly, and suddenly your brain tunes out the world and wanders to something else entirely -- perhaps a recent experience, or an old memory. You just had a daydream.

Yet despite the ubiquity of this experience, what is happening in the brain while daydreaming is a question that has largely eluded neuroscientists.

Now, a study in mice, published Dec. 13 in Nature, has brought a team led by researchers at Harvard Medical School one step closer to figuring it out.

The researchers tracked the activity of neurons in the visual cortex of the brains of mice while the animals remained in a quiet waking state. They found that occasionally these neurons fired in a pattern similar to one that occurred when a mouse looked at an actual image, suggesting that the mouse was thinking -- or daydreaming -- about the image. Moreover, the patterns of activity during a mouse's first few daydreams of the day predicted how the brain's response to the image would change over time.

The research provides tantalizing, if preliminary, evidence that daydreams can shape the brain's future response to what it sees. This causal relationship needs to be confirmed in further research, the team cautioned, but the results offer an intriguing clue that daydreams during quiet waking may play a role in brain plasticity -- the brain's ability to remodel itself in response to new experiences.

"We wanted to know how this daydreaming process occurred on a neurobiological level, and whether these moments of quiet reflection could be important for learning and memory," said lead author Nghia Nguyen, a PhD student in neurobiology in the Blavatnik Institute at HMS.

An overlooked brain region

Scientists have spent considerable time studying how neurons replay past events to form memories and map the physical environment in the hippocampus, a seahorse-shaped brain region that plays a key role in memory and spatial navigation.

By contrast, there has been little research on the replay of neurons in other brain regions, including the visual cortex. Such efforts would provide valuable insights about how visual memories are formed.

"My lab became interested in whether we could record from enough neurons in the visual cortex to understand what exactly the mouse is remembering -- and then connect that information to brain plasticity," said senior author Mark Andermann, professor of medicine at Beth Israel Deaconess Medical Center, and professor of neurobiology at HMS.

In the new study, the researchers repeatedly showed mice one of two images, each consisting of a different checkerboard pattern of gray and dappled black and white squares. Between images, the mice spent a minute looking at a gray screen. The team simultaneously recorded activity from around 7,000 neurons in the visual cortex.

The researchers found that when a mouse looked at an image, the neurons fired in a specific pattern, and the patterns were different enough to discern image one from image two. More important, when a mouse looked at the gray screen between images, the neurons sometimes fired in a similar, but not identical, pattern, as when the mouse looked at the image, a sign that it was daydreaming about the image. These daydreams occurred only when mice were relaxed, characterized by calm behavior and small pupils.

Unsurprisingly, mice daydreamed more about the most recent image -- and they had more daydreams at the beginning of the day than at the end, when they had already seen each image dozens of times.

But what the researchers found next was completely unexpected.

Throughout the day, and across days, the activity patterns seen when the mice looked at the images changed -- what neuroscientists call "representational drift." Yet this drift wasn't random. Over time, the patterns associated with the images became even more different from each other, until each involved an almost entirely separate set of neurons. Notably, the pattern seen during a mouse's first few daydreams about an image predicted what the pattern would become when the mouse looked at the image later.

"There's drift in how the brain responds to the same image over time, and these early daydreams can predict where the drift is going," Andermann said.

Finally, the researchers found that the visual cortex daydreams occurred at the same time as replay activity occurred in the hippocampus, suggesting that the two brain regions were communicating during these daydreams.

To sit, perchance to daydream

Based on the results of the study, the researchers suspect that these daydreams may be actively involved in brain plasticity.

"When you see two different images many times, it becomes important to discriminate between them. Our findings suggest that daydreaming may guide this process by steering the neural patterns associated with the two images away from each other," Nguyen said, while noting that this relationship needs to be confirmed.

Nguyen added that learning to differentiate between the images should help the mouse respond to each image with more specificity in the future.

These observations align with a growing body of evidence in rodents and humans that entering a state of quiet wakefulness after an experience can improve learning and memory.

Next, the researchers plan to use their imaging tools to visualize the connections between individual neurons in the visual cortex and to examine how these connections change when the brain "sees" an image.

"We were chasing this 99 percent of unexplored brain activity and discovered that there's so much richness in the visual cortex that nobody knew anything about," Andermann said.

Whether daydreams in people involve similar activity patterns in the visual cortex is an open question, and the answer will require additional experiments. However, there is preliminary evidence that an analogous process occurs in humans when they recall visual imagery.

Randy Buckner, the Sosland Family Professor of Psychology and of Neuroscience at Harvard University, has shown that brain activity in the visual cortex increases when people are asked to recall an image in detail. Other studies have recorded flurries of electrical activity in the visual cortex and the hippocampus during such recall.

For the researchers, the results of their study and others suggest that it may be important to make space for moments of quiet waking that lead to daydreams. For a mouse, this may mean taking a pause from looking at a series of images and, for a human, this could mean taking a break from scrolling on a smartphone.

"We feel pretty confident that if you never give yourself any awake downtime, you're not going to have as many of these daydream events, which may be important for brain plasticity," Andermann said.

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Some icy exoplanets may have habitable oceans and geysers

A NASA study expands the search for life beyond our solar system by indicating that 17 exoplanets (worlds outside our solar system) could have oceans of liquid water, an essential ingredient for life, beneath icy shells. Water from these oceans could occasionally erupt through the ice crust as geysers. The science team calculated the amount of geyser activity on these exoplanets, the first time these estimates have been made. They identified two exoplanets sufficiently close where signs of these eruptions could be observed with telescopes.

The search for life elsewhere in the Universe typically focuses on exoplanets that are in a star's "habitable zone," a distance where temperatures allow liquid water to persist on their surfaces. However, it's possible for an exoplanet that's too distant and cold to still have an ocean underneath an ice crust if it has enough internal heating. Such is the case in our solar system where Europa, a moon of Jupiter, and Enceladus, a moon of Saturn, have subsurface oceans because they are heated by tides from the gravitational pull of the host planet and neighboring moons.

These subsurface oceans could harbor life if they have other necessities, such as an energy supply as well as elements and compounds used in biological molecules. On Earth, entire ecosystems thrive in complete darkness at the bottom of oceans near hydrothermal vents, which provide energy and nutrients.

"Our analyses predict that these 17 worlds may have ice-covered surfaces but receive enough internal heating from the decay of radioactive elements and tidal forces from their host stars to maintain internal oceans," said Dr. Lynnae Quick of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Thanks to the amount of internal heating they experience, all planets in our study could also exhibit cryovolcanic eruptions in the form of geyser-like plumes." Quick is lead author of a paper on the research published on October 4 in the Astrophysical Journal.

The team considered conditions on 17 confirmed exoplanets that are roughly Earth-sized but less dense, suggesting that they could have substantial amounts of ice and water instead of denser rock. Although the planets' exact compositions remain unknown, initial estimates of their surface temperatures from previous studies all indicate that they are much colder than Earth, suggesting that their surfaces could be covered in ice.

The study improved estimates of each exoplanet's surface temperature by recalculating using the known surface brightness and other properties of Europa and Enceladus as models. The team also estimated the total internal heating in these exoplanets by using the shape of each exoplanet's orbit to get the heat generated from tides and adding it to the heat expected from radioactive activity. Surface temperature and total heating estimates gave the ice layer thickness for each exoplanet since the oceans cool and freeze at the surface while being heated from the interior. Finally, they compared these figures to Europa's and used estimated levels of geyser activity on Europa as a conservative baseline to estimate geyser activity on the exoplanets.

They predict that surface temperatures are colder than previous estimates by up to 60 degrees Fahrenheit (16 degrees Celsius). Estimated ice shell thickness ranged from about 190 feet (58 meters) for Proxima Centauri b and one mile (1.6 kilometers) for LHS 1140 b to 24 miles (38.6 kilometers) for MOA 2007 BLG 192Lb, compared to Europa's estimated average of 18 miles (almost 29 kilometers). Estimated geyser activity went from just 17.6 pounds per second (about 8 kilograms/second) for Kepler 441b to 639,640 pounds/second (290,000 kilograms/second) for LHS 1140b and 13.2 million pounds/second (six million kilograms/second) for Proxima Centauri b, compared to Europa at 4,400 pounds/second (2,000 kilograms/second).

"Since our models predict that oceans could be found relatively close to the surfaces of Proxima Centauri b and LHS 1140 b, and their rate of geyser activity could exceed Europa's by hundreds to thousands of times, telescopes are most likely to detect geological activity on these planets," said Quick, who is presenting this research December 12at the American Geophysical Union meeting in San Francisco, California.

This activity could be seen when the exoplanet passes in front of its star. Certain colors of starlight could be dimmed or blocked by water vapor from the geysers. "Sporadic detections of water vapor in which the amount of water vapor detected varies with time, would suggest the presence of cryovolcanic eruptions," said Quick. The water might contain other elements and compounds that could reveal if it can support life. Since elements and compounds absorb light at specific "signature" colors, analysis of the starlight would let scientists determine the geyser's composition and evaluate the exoplanet's habitability potential.

For planets like Proxima Centauri b that don't cross their stars from our vantage point, geyser activity could be detected by powerful telescopes that are able to measure light that the exoplanet reflects while orbiting its star. Geysers would expel icy particles at the exoplanet's surface which would cause the exoplanet to appear very bright and reflective.

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Twenty-year study confirms California forests are healthier when burned -- or thinned

A 20-year experiment in the Sierra Nevada confirms that different forest management techniques -- prescribed burning, restoration thinning or a combination of both -- are effective at reducing the risk of catastrophic wildfire in California.

These treatments also improve forest health, making trees more resilient to stressors like drought and bark beetles, and they do not negatively impact plant or wildlife biodiversity within individual tree stands, the research found. The findings of the experiment, called the Fire Surrogate Study, were published today in the journal Ecological Applications.

"The research is pretty darn clear that these treatments are effective -- very effective," said study lead author Scott Stephens, a professor of fire science at the University of California, Berkeley."I hope this lets people know that there is great hope in doing these treatments at scale, without any negative consequences."

Last year, California announced a strategic plan for expanding the use of prescribed fire to 400,000 acres annually by 2025. However, the use of beneficial fire continues to be hindered by multiple factors, including the lack of a trained workforce, the need for specific weather conditions for burning, and fears about potential risks.

This study shows that restoration thinning is also a viable option for forest management and can be used in tandem with beneficial fire without harming forest health or biodiversity.

"Our findings show that there's not just one solution -- there are multiple things that you can do to impact the risk of catastrophic fire," said study co-author Ariel Roughton, research station manager at Berkeley Forests. "Folks can choose from different combinations of treatments that might fit their needs, and we can show them how those treatments might impact things like wildfire behavior, tree growth and carbon holding in their forests."

Surrogates to wildfire

Over the past two decades, Stephens and other researchers at Berkeley Forests have used prescribed burning, restoration thinning or a combination of both to treat plots of land at Blodgett Forest Research Station, a 4,000-acre experimental forest located about 65 miles northeast of Sacramento on the unceded lands of the Nisenan peoples.

The Fire Surrogate Study was one of 13 studies across the U.S. first launched in 1999 with funding from the U.S. Joint Fire Science Program. Its aim was to study whether the two treatments could mimic the beneficial impacts of lightning fires and Indigenous burning practices on California's forests, which have become dense and overgrown after a century of logging and fire suppression.

"Prescribed fire and restoration thinning are both surrogates for wildfire, a key process that happened frequently in California before European colonization," Stephens said. "The impetus of this study was: If you're going to implement these treatments at a large scale, is there anything that's going to be lost?"

The study created nine experimental plots and three control plots at Blodgett. Three of the experimental plots were managed only using prescribed burns; three burns occurred over the course of 20 years. Three other experimental plots were first thinned and then burned, and the final three were treated only with restoration thinning. The control plots were left to grow without human interference except continued fire suppression.

At the end of the 20-year period, the researchers surveyed the vegetation in each plot and used computational modeling to estimate how many trees were likely to survive wildfire. They found that all three types of experimental plots were significantly more resilient to wildfire than the control plots, showing an 80% likelihood that at least 80% of trees would survive.

They also calculated the "index of competition," a measure of how strongly trees must compete for resources like sunlight, water and soil nutrients. By removing excess trees and vegetation, thinning and burning both limited the amount of competition between trees, making them less vulnerable to stressors, like drought and bark beetles.

However, the plots that were treated with a combination of thinning and fire had the best index of competition, suggesting that they would be the most resilient to the impacts of climate change.

"When you combine thinning with fire, you're able to modify all different levels of the forest structure,and it speeds up the timeline for achieving a more resilient structure," Roughton said.

Restoration thinning can also provide financial benefits: Often, larger trees can be sold to sawmills, and the proceeds can be used to help offset the cost of forest management. Over the course of 20 years, the treatments at Blodgett were entirely paid for by revenue from timber.

"When I go to Sacramento and talk about [forest management] with legislators, the first question they always ask is about cost," Stephens said. "People in the state government are telling us that they can't be the sole source support for this work. That's why the economicsare so important."

Trial by fire

In September 2022, the forests at Blodgett were subjected to a real-life test: On the morning of Sept. 9, 2022, the Mosquito Fire breached the north side of the property, burning approximately 300 acres before it was contained two days later.

One of the study's control plots was located directly in the path of the blaze, and more than 60% of the trees in this plot were completely scorched. However, neighboring experimental plots that had been treated with prescribed burns served as "fuel breaks," burning less hot than the control and acting as staging areas for firefighters.

"We think that, overall, our management actions, coupled with the weather, did have a pretty big impact on the behavior of the fire," Roughton said.

The researchers have received a four-year grant from the Joint Fire Science Program to continue the Fire Surrogate Project. With the help of the grant, they have established a new control plot to replace the one that burned and plan to apply a fourth fire to the experimental burn-only plots.

They are also collaborating with the United Auburn Indian Community to reestablish Indigenous cultural burning at Blodgett.

"We want to be part of the solution, and that's part of our mission at Blodgett," Roughton said. "We hope that by doing these studies and bringing folks here to see the effects of the different treatments, they will take that back and apply it to the land that they're going to be managing."

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Ultra-hard material to rival diamond discovered

Scientists have solved a decades-long puzzle and unveiled a near unbreakable substance that could rival diamond, as the hardest material on earth, a study says.

Researchers found that when carbon and nitrogen precursors were subjected to extreme heat and pressure, the resulting materials -- known as carbon nitrides -- were tougher than cubic boron nitride, the second hardest material after diamond.

The breakthrough opens doors for multifunctional materials to be used for industrial purposes including protective coatings for cars and spaceships, high-endurance cutting tools, solar panels and photodetectors, experts say.

Materials researchers have attempted to unlock the potential of carbon nitrides since the 1980s, when scientists first noticed their exceptional properties, including high resistance to heat.

Yet after more than three decades of research and multiple attempts to synthesize them, no credible results were reported.

Now, an international team of scientists -- led by researchers from the Centre for Science at Extreme Conditions at the University of Edinburgh and experts from the University of Bayreuth, Germany and the University of Linköping, Sweden -- have finally achieved a breakthrough.

The team subjected various forms of carbon nitrogen precursors to pressures of between 70 and 135 gigapascals -- around one million times our atmospheric pressure -- while heating it to temperatures of more than one and a half thousand degrees celsius.

To identify the atomic arrangement of thecompounds under these conditions, the samples were illuminated by an intense X-ray beam at three particle accelerators -- the European Synchrotron Research Facility in France, the Deutsches Elektronen-Synchrotron in Germany and the Advanced Photon Source based in the United States.

Researchers discovered that three carbon nitride compounds were found to have the necessary building blocks for super-hardness.

Remarkably, all three compounds retained their diamond-like qualities when they returned to ambient pressure and temperature conditions.

Further calculations and experiments suggest the new materials contain additional properties including photoluminescence and high energy density, where a large amount of energy can be stored in a small amount of mass.

Researchers say the potential applications of these ultra-incompressible carbon nitrides is vast, potentially positioning them as ultimate engineering materials to rival diamonds.

The research, published in Advanced Materials, was funded by the UKRI FLF scheme and European research grants.

Dr Dominique Laniel, Future Leaders Fellow, Institute for Condensed Matter Physics and Complex Systems, School of Physics and Astronomy, University of Edinburgh, said: "Upon the discovery of the first of these new carbon nitride materials, we were incredulous to have produced materials researchers have been dreaming of for the last three decades. These materials provide strong incentive to bridge the gap between high pressure materials synthesis and industrial applications."

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Scientists unveil complete cell map of a whole mammalian brain

For the first time ever, an international team of researchers has created a complete cell atlas of a whole mammalian brain. This atlas serves as a map for the mouse brain, describing the type, location, and molecular information of more than 32 million cells and providing information on connectivity between these cells. The mouse is the most commonly used vertebrate experimental model in neuroscience research, and this cellular map paves the way for a greater understanding of the human brain -- arguably the most powerful computer in the world. The cell atlas also lays the foundation for the development of a new generation of precision therapeutics for people with mental and neurological disorders of the brain.

The findings were funded by the National Institutes of Health's Brain Research Through Advancing Innovative Neurotechnologies® Initiative, or The BRAIN Initiative®, and appear in a collection of 10 papers published in Nature.

"The mouse atlas has brought the intricate network of mammalian brain cells into unprecedented focus, giving researchers the details needed to understand human brain function and diseases," said Joshua A. Gordon, M.D., Ph.D., Director of the National Institute of Mental Health, part of the National Institutes of Health.

The cell atlas describes the types of cells in each region of the mouse brain and their organization within those regions.

In addition to this structural information, the cell atlas provides an incredibly detailed catalog of the cell's transcriptome -- the complete set of gene readouts in a cell, which contains instructions for making proteins and other cellular products.

The transcriptomic information included in the atlas is hierarchically organized, detailing cell classes, subclasses, and thousands of individual cell clusters within the brain.

The atlas also characterizes the cell epigenome -- chemical modifications to a cell's DNA and chromosomes that alter the way the cell's genetic information is expressed -- detailing thousands of epigenomic cell types and millions of candidate genetic regulation elements for different brain cell types.

Together, the structural, transcriptomic, and epigenetic information included in this atlas provide an unprecedented map of cellular organization and diversity across the mouse brain.

The atlas also provides an accounting of the neurotransmitters and neuropeptides used by different cells and the relationship among cell types within the brain.

This information can be used as a detailed blueprint for how chemical signals are initiated and transmitted in different parts of the brain.

Those electrical signals are the basis for how brain circuits operate and how the brain functions overall.

"This product is a testament to the power of this unprecedented, cross-cutting collaboration and paves our path for more precision brain treatments," said John Ngai, Ph.D., Director of the NIH BRAIN Initiative."

Of the 10 studies included in this collection, seven are funded through the NIH BRAIN Initiative Cell Census Network (BICCN), and two are funded through the larger NIH BRAIN Initiative.

The core aim of the BICCN, a groundbreaking, cross-collaborative effort to understand the brain's cellular makeup, is to develop a comprehensive inventory of the cells in the brain -- where they are, how they develop, how they work together, and how they regulate their activity -- to better understand how brain disorders develop, progress, and are best treated.

"By leveraging the unique nature of its multi-disciplinary and international collaboration, the BICCN was able to accomplish what no other team of scientists has been able to before," said Dr. Ngai.

"Now we are ready to take the next big step -- completing the cell maps of the human brain and the nonhuman primate brain."

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Ryugu samples illuminate terrestrial weathering effects on primitive meteorites

A groundbreaking study conducted by a team of international scientists has unveiled unprecedented insights into the nature of the asteroid Ryugu and shed light on the composition of water- and carbon-rich small bodies in the solar system.

Asteroids like Ryugu are remnants of planetary embryos that never reached larger sizes, making them invaluable windows into materials that formed in the early solar system.

The study centered on laboratory measurements of the samples brought back to the Earth by the Hayabusa2 spacecraft in 2020.

Led by the Japan Aerospace Exploration Agency (JAXA), Hayabusa2 aimed to uncover the true nature of Ryugu and explore how astrologists can use knowledge from meteorites to interpret telescopic observations of other hydrous asteroids.

Unlike meteorites derived from similar hydrous asteroids, the Ryugu samples avoided terrestrial alteration -- the interaction with oxygen and water in the Earth's atmosphere.

Reflectance spectroscopy, a primary technique linking laboratory analyses of meteorites to asteroid observations, was employed to compare fresh Ryugu samples with meteorites altered in terrestrial environments.

The team successfully developed analytical procedures that avoided exposing the samples to Earth's atmosphere, ensuring the preservation of their original conditions.

Previous studies suggested that Ryugu's sample mineralogy resembled CI chondrites, the most primitive meteorites chemically.

However, other studies have contradicted this by revealing a significant difference in reflectance spectra between Ryugu samples and CI chondrites.

Further investigations in the new study indicated that heating CI samples under reducing conditions at 300 °C reproduced Ryugu's sample mineralogy well, resulting in spectra closely matching those of Ryugu samples.

The findings challenge previous assumptions about the parent bodies of CI chondrites and underscore the susceptibility of primitive meteorite spectra to terrestrial weathering.

The study suggests that actual CI chondrite parent bodies likely exhibit darker and flatter reflectance spectra than previously thought.

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Alaskan allies: Communities unite to protect the areas they love

Natural resource management decisions in protected areas impact more than the wildlife and landscapes they're charged to conserve. They also affect neighbors, who could otherwise hunt, build, or recreate as they choose on their own land. For decades, community members primarily voiced their opinions through brief and impersonal public comment periods. But an initiative led by environmental social scientists at the University of Illinois Urbana-Champaign is putting a new spin on neighborly communication.

"Historically, public land management agencies would offer brief periods where people could submit a remark that may or may not be considered and that typically wouldn't result in any meaningful dialogue," said Carena van Riper, associate professor in the Department of Natural Resources and Environmental Sciences in the College of Agricultural, Consumer and Environmental Sciences (ACES) at U. of I. "For more inclusive conservation to happen, there needs to be in-depth engagement, communication, and deliberation with diverse stakeholders. There's real benefit to engaging people."

Van Riper has been working toward a model of inclusive conservation for nearly a decade in the area surrounding Alaska's Denali National Park, partnering with the National Park System (NPS) to examine the values and viewpoints of neighbors on everything from conservation priorities to tourism impacts. She and her colleagues published results of their latest engagement efforts in Sustainability Science.

The study brought Denali neighbors together in a month-long online discussion forum designed to understand their views on the benefits and threats facing the area, as well as how land management agencies could better incorporate their perspectives.

Van Riper noted that residents come from all walks of life and have priorities that span protected area conservation, indigenous use, tourism, energy development, and others.

"Although it is important, conservation is just one of many priorities," she said. "We tried to equalize the power dynamic among interest groups and in how we framed the National Park Service and its role in defining life in Interior Alaska."

Residents were grouped according to a values assessment, with two groups of like-minded participants and one group representing a mix of values. This allowed the research team to test whether the value-basis of decision-making affected the ways that people learned from one another and engaged in collaborative dialogue.

"I went into this project worried because a lot of online dialogue tends to be very combative. But the most wonderful discussions unfolded with this group of people; they were always thoughtful and respectful to one another. They disagreed, but we never had to step in and intervene," said lead author Devin Goodson, a doctoral student working with van Riper. "Another one of the benefits of engaging online is people weren't forced to fully explain their thoughts in the moment, like you'd have to do during a short public comment session. The platform created a really well informed and constructive conversation."

After a period where participants got to know each other during focus groups, they were engaged through the Denali Discussion Forum, where the researchers posed a series of questions about the park and its management. Residents were expected to answer the questions and interact with other participants' answers on a weekly basis during the month-long program.

Goodson said the residents discussed many of the same benefits of living near Denali, though the groups differed in the emphasis they placed on particular benefits, which included access to wilderness, solitude, recreation, hunting and fishing grounds, and the pursuit of a subsistence lifestyle. Likewise, the groups emphasized slightly different threats, including tourism, competing interests, mismanagement, and climate change -- the latter was mentioned only by the mixed values group, which comprised a younger demographic. The groups diverged more strongly in their discussions on management solutions.

"We found that residents value the Alaskan landscape in a lot of ways and often identify common threats, but they come up with different ways to solve these issues. However, a common thread across the proposed solutions for resource managers was that people just wanted to feel like they were a part of the process in a meaningful way," Goodson said. "They're open to what that looks like, but they want to feel that the process overall is fair."

Co-author William Stewart in the Department of Recreation, Sport and Tourism at U. of I. added, "The NPS makes well-intentioned decisions, yet sometimes, residents of nearby communities feel like their voices aren't being heard. They need help. Social scientists have a toolkit for that. We engage community residents not as decision-makers, but as outsiders who could represent community voices to help facilitate dialogue with the park, and within the park service."

Armed with results from the Denali Discussion Forum, which were summarized weekly by the study team with input from participants, NPS can move ahead with more informed management decisions. And they can use a similar model to solicit input for future management actions.

But the lessons extend well beyond Denali and even the National Park System. Goodson said the study is an example of one way to give average people a say in the things that impact them every day in their environment.

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This Japanese 'dragon' terrorized ancient seas

Researchers have described a Japanese mosasaur the size of a great white shark that terrorized Pacific seas 72 million years ago.

Extra-long rear flippers might have aided propulsion in concert with its long finned tail.

And unlike other mosasaurs, or large extinct marine reptiles, it had a dorsal fin like a shark's that would have helped it turn quickly and with precision in the water.

University of Cincinnati Associate Professor Takuya Konishi and his international co-authors described the mosasaur and placed it in a taxonomic context in the Journal of Systematic Palaeontology.

The mosasaur was named for the place where it was found, Wakayama Prefecture.

Researchers call it the Wakayama Soryu, which means blue dragon.

Dragons are creatures of legend in Japanese folklore, Konishi said.

"In China, dragons make thunder and live in the sky. They became aquatic in Japanese mythology," he said.

The specimen was discovered along the Aridagawa River in Wakayama by co-author Akihiro Misaki in 2006.

The specimen is the most complete skeleton of a mosasaur ever found in Japan or the northwestern Pacific, Konishi said.

"In this case, it was nearly the entire specimen, which was astounding," Konishi said.

He has dedicated his career to studying these ancient marine reptiles.

But the Japanese specimen has unique features that defies simple classification, he said.

Its rear flippers are longer than its front ones. These enormous flippers are even longer than its crocodile-like head, which is unique among mosasaurs.

"I thought I knew them quite well by now," Konishi said. "Immediately it was something I had never seen before."

Mosasaurs were apex predators in prehistoric oceans from about 100 million years ago to 66 million years ago.

They were contemporaries of Tyrannosaurus rex and other late Cretaceous dinosaurs that ruled the Earth.

Mosasaurs were victims of the same mass extinction that killed off nearly all dinosaurs when an asteroid struck what is now the Gulf of Mexico.

Researchers placed the specimen in the subfamily Mosasaurinae and named it Megapterygius wakayamaensis to recognize where it was found.

Megapterygius means "large winged" in keeping with the mosasaur's enormous flippers.

Konishi said those big paddle-shaped flippers might have been used for locomotion.

But that type of swimming would be extraordinary not only among mosasaurs but among virtually all other animals.

"We lack any modern analog that has this kind of body morphology -- from fish to penguins to sea turtles," he said.

"None has four large flippers they use in conjunction with a tail fin."

Researchers speculated that the large front fins might have helped with rapid maneuvering while its large rear fins might have provided pitch to dive or surface.

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Archaeologists unearth one of earliest known frame saddles

In April 2015, looters sacked an ancient cave burial at a site called Urd Ulaan Uneet high within the Altai Mountains of western Mongolia. When police apprehended the criminals, they uncovered, among other artifacts, an elegantly carved saddle made from several pieces of birch wood.

Now, in a new study, researchers from Mongolia collaborating with University of Colorado Boulder archaeologist William Taylor have described the find. The team's radiocarbon dating pins the artifact to roughly the 4th Century C.E., making it one of the earliest known frame saddles in the world.

"It was a watershed moment in the technological history of people and horses," said Taylor, corresponding author of the new study and curator of archaeology at the CU Museum of Natural History.

He and his colleagues, including scientists from 10 countries, published their findings Dec. 12 in the journal Antiquity.

The research reveals the underappreciated role that ancient Mongolians played in the spread of horse riding technology and culture around the globe. Those advances ushered in a new and sometimes brutal era of mounted warfare around the same time as the fall of the Roman Empire.

The discovery also highlights the deep relationships between human and animals in Mongolia. For millennia, pastoral peoples have traveled between the vast grasslands of the Mongolian Steppe with their horses -- which, in the region, tend to be short but sturdy, capable of surviving winter temperatures that can plummet far below freezing. Airag, a lightly alcoholic beverage made from fermented horse milk, remains a popular libation in Mongolia.

"Ultimately, technology emerging from Mongolia has, through a domino effect, ended up shaping the horse culture that we have in America today, especially our traditions of saddlery and stirrups," Taylor said.

But these insights also come at a time when Mongolia's horse culture is beginning to disappear, said study lead author Jamsranjav Bayarsaikhan.

"Horses have not only influenced the history of the region but also left a deep mark on the art and worldview of the Nomadic Mongols," said Bayarsaikhan, an archaeologist at the Max Planck Institute for the Science of Human History in Germany. "However, the age of technology is slowly erasing the culture and use of horses. Instead of herders riding horses, more and more people are riding motorcycles in the plains of Mongolia."

Mounted combat

Bayarsaikhan was working as a curator at the National Museum of Mongolia when he and his colleagues got the call from police in Hovd Province. The team later excavated the Urd Ulaan Uneet cave and unearthed the mummified remains of a horse, which the group partially described in a 2018 paper.

The saddle itself was made from about six pieces of birch wood held together with wooden nails. It bears traces of red paint with black trim and includes two leather straps that likely once supported stirrups. (The researchers also reported an iron stirrup recently discovered from around the same time period in eastern Mongolia).

The group couldn't definitively trace back where those materials came from. Birch trees, however, grow commonly in the Mongolian Altai, suggesting that locals had crafted the saddle themselves, not traded for it.

Taylor explained that humans had used pads, a form of proto-saddle, to keep their rear ends comfortable on horseback since the earliest days of mounted riding. Rigid wooden saddles, which were much sturdier, paired with stirrups opened a new range of things that people could do with horses.

"One thing they very gave rise to was heavy cavalry and high-impact combat on horseback," Taylor said. "Think of jousting in Medieval Europe."

Traveling west

In the centuries after the Mongolian saddle was crafted, these types of tools spread rapidly west across Asia and into the early Islamic world. There, cavalry forces became key to conquest and trade across large portions of the Mediterranean region and northern Africa.

Where it all began, however, is less clear. Archaeologists have typically considered modern-day China the birthplace of the first frame saddles and stirrups -- with some finds dating back to the 5th to 6th Century C.E. or even earlier.

The new study, however, complicates that picture, Taylor said.

"It's not the only piece of information suggesting that Mongolia might have been either among the very first adopters of these new technologies -- or could, in fact, be the place where they were first innovated," he said.

He suspects that Mongolia's place in that history may have gone underappreciated for so long in part because of the region's geography. The population density in the country's mountainous expanses is low, among the lowest on Earth, making it difficult to encounter and analyze important archaeological finds.

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When is an aurora not an aurora?

The shimmering green, red and purple curtains of the northern and southern lights -- the auroras -- may be the best-known phenomena lighting up the nighttime sky, but the most mysterious are the mauve and white streaks called Steve and their frequent companion, a glowing green "picket fence."

First recognized in 2018 as distinct from the common auroras, Steve -- a tongue-in-cheek reference to the benign name given a scary hedge in a 2006 children's movie -- and its associated picket fence were nevertheless thought to be caused by the same physical processes. But scientists were left scratching their heads about how these glowing emissions were produced.

Claire Gasque, a University of California, Berkeley, graduate student in physics, has now proposed a physical explanation for these phenomena that is totally different from the processes responsible for the well-known auroras. She has teamed up with researchers at the campus's Space Sciences Laboratory (SSL) to propose that NASA launch a rocket into the heart of the aurora to find out if she's correct.

Vibrant auroras and glowing phenomena such as Steve and the picket fence are becoming more common as the sun enters the active period of its 11-year cycle, and November was a good month for Steve observations in the northern latitudes. Because all these transient luminous phenomena are triggered by solar storms and coronal mass ejections from the sun, the approaching solar maximum is an ideal time to study rare events like Steve and the picket fence.

Gasque described the physics behind the picket fence in a paper published last month in the journal Geophysical Research Letters and will discuss the results on Dec. 14 in an invited talk at the American Geophysical Union meeting in San Francisco.

She calculated that in a region of the upper atmosphere farther south than that in which auroras form, electric fields parallel to Earth's magnetic field could produce the color spectrum of the picket fence. If correct, this unusual process has implications for how physicists understand energy flow between Earth's magnetosphere, which surrounds and protects Earth from the solar wind, and the ionosphere at the edge of space.

"This would upend our modeling of what creates light and the energy in the aurora in some cases," Gasque said.

"The really interesting thing about Claire's paper is that we've known for a couple of years now that the Steve spectrum is telling us there's some very exotic physics going on. We just didn't know what it was," said Brian Harding, a co-author of the paper and an SSL assistant research physicist. "Claire's paper showed that parallel electric fields are capable of explaining this exotic spectrum."

The paper was a side project from Gasque's Ph.D. thesis, which is focused on the connection between events like volcanoes on Earth's surface and phenomena in the ionosphere 100 kilometers or more above our heads.

But after hearing about Steve -- which has now become an acronym for Strong Thermal Emission Velocity Enhancement -- at a conference in 2022, she couldn't resist looking into the physics behind Steve and the picket fence.

"It's really cool," she said. "It's one of the biggest mysteries in space physics right now."

The physics of Steve and picket fence

The common auroras are produced when the solar wind energizes particles in Earth's magnetosphere, often at altitudes higher than 1,000 kilometers above the surface. These energized particles spiral around Earth's magnetic field lines toward the poles, where they crash into and excite oxygen and nitrogen molecules in the upper atmosphere. When those molecules relax, oxygen emits specific frequencies of green and red light, while nitrogen generates a bit of red, but primarily a blue, emission line.

The colorful, shimmering curtains that result can extend for thousands of kilometers across the northern or southern latitudes.

Steve, however, displays not individual emission lines, but a broad range of frequencies centered around purple or mauve. And unlike auroras, neither Steve nor the picket fence emit blue light, which is generated when the most energetic particles hit and ionize nitrogen. Steve and the picket fence also occur at lower latitudes than the aurora, potentially even as far south as the equator.

Some researchers proposed that Steve is caused by ion flows in the upper atmosphere, referred to as subauroral ion drift, or SAID, though there's no well accepted physical explanation for how SAID could generate the colorful emissions.

Gasque's interest was sparked by suggestions that the picket fence's emissions could be generated by low-altitude electric fields parallel to Earth's magnetic field, a situation thought to be impossible because any electric field aligned with the magnetic field should quickly short out and disappear.

Using a common physical model of the ionosphere, Gasque subsequently showed that a moderate parallel electric field -- around 100 millivolts per meter -- at a height of about 110 km could accelerate electrons to an energy that would excite oxygen and nitrogen and generate the spectrum of light observed from the picket fence. Unusual conditions in that area, such as a lower density of charged plasma and more neutral atoms of oxygen and nitrogen, could potentially act as insulation to keep the electric field from shorting out.

"If you look at the spectrum of the picket fence, it's much more green than you would expect. And there's none of the blue that's coming from the ionization of nitrogen," Gasque said. "What that's telling us is that there's only a specific energy range of electrons that can create those colors, and they can't be coming from way out in space down into the atmosphere, because those particles have too much energy."

Instead, she said, "the light from the picket fence is being created by particles that have to be energized right there in space by a parallel electric field, which is a completely different mechanism than any of the aurora that we've studied or known before."

She and Harding suspect that Steve itself may be produced by related processes. Their calculations also predict the type of ultraviolet emissions that this process would produce, which can be checked to verify the new hypothesis about the picket fence.

Though Gasque's calculations don't directly address the on-off glow that makes the phenomenon look like a picket fence, it's likely due to wavelike variations in the electric field, she said. And while the particles that are accelerated by the electric field are probably not from the sun, the scrambling of the atmosphere by solar storms probably triggers Steve and the picket fence, as it does the common aurora.

Enhanced auroras exhibit a picket fence-like glow

The next step, Harding said, is to launch a rocket from Alaska through these phenomena and measure the strength and direction of the electric and magnetic fields. SSL scientists specialize in designing and building instruments that do just that. Many of these instruments are on spacecraft now orbiting Earth and the sun.

Initially, the target would be what's known as an enhanced aurora, which is a normal aurora with picket fence-like emissions embedded in it.

"The enhanced aurora is basically this bright layer that's embedded in the normal aurora. The colors are similar to the picket fence in that there's not as much blue in them, and there's more green from oxygen and red from nitrogen. The hypothesis is that these are also created by parallel electric fields, but they are a lot more common than the picket fence," Gasque said.

The plan is not only "to fly a rocket through that enhanced layer to actually measure those parallel electric fields for the first time," she said, but also send a second rocket up to measure the particles at higher altitudes, "to distinguish the conditions from those that cause the auroras." Eventually, she hopes for a rocket that will fly directly through Steve and the picket fence.

Harding, Gasque and colleagues proposed just such a sounding rocket campaign to NASA this fall and expect to hear back regarding its selection in the first half of 2024. Gasque and Harding consider the experiment an important step in understanding the chemistry and physics of the upper atmosphere, the ionosphere and Earth's magnetosphere, and a proposal in line with the Low Cost Access to Space (LCAS) program sponsored by NASA for projects like this.

"It's fair to say that there's going to be a lot of study in the future about how those electric fields got there, what waves they are or aren't associated with, and what that means for the larger energy transfer between Earth's atmosphere and space," Harding said. "We really don't know. Claire's paper is the first step in the chain of that understanding."

Gasque expressed appreciation for the input from people who study the middle ionosphere, or mesosphere, and the stratosphere, whose ideas helped her puzzle out the solution.

"With this collaboration, we were able to make some really cool progress in this field," she said. "Honestly, it was just following our nose and being excited about it."

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