Gut bacteria make neurotransmitters to shape the newborn immune system

Weill Cornell Medicine investigators discovered that unique bacteria colonize the gut shortly after birth and make the neurotransmitter serotonin to educate gut immune cells. This prevents allergic reactions to food and the bacteria themselves during early development.

The preclinical study, published in Science Immunology on Mar. 15, showed that bacteria abundant in the guts of newborns produce serotonin, which promotes the development of immune cells called T-regulatory cells or Tregs. These cells suppress inappropriate immune responses to help prevent autoimmune diseases and dangerous allergic reactions to harmless food items or beneficial gut microbes.

"The gut is now known as the second human brain as it makes over 90 percent of the neurotransmitters in the human body. While neurotransmitters such as serotonin are best known for their roles in brain health, receptors for neurotransmitters are located throughout the human body," explained the study's senior author, Dr. Melody Zeng, an assistant professor of immunology in the Gale and Ira Drukier Institute for Children's Research and the Department of Pediatrics at Weill Cornell Medicine.

Gut Bacteria in Babies Provide a Helping Hand

The researchers observed that the neonatal mouse gut had much higher levels of neurotransmitters, including serotonin, than the adult gut. "So far, almost all studies of gut neurotransmitters were conducted in adult animals or human subjects, where a specific gut cell type called enterochromaffin cells produce neurotransmitters," said Dr. Zeng. "However, we discovered that this isn't the case in the newborn gut where most of the serotonin is made by bacteria that are more abundant in the neonatal gut."

This was also confirmed in babies through a human infant stool biobank that the Zeng lab has established in collaboration with the Neonatal Intensive Care Unit in the NewYork-Presbyterian Alexandra Cohen Hospital for Women and Newborns. These samples were obtained with parental consent and deidentified.

The study results suggest that before the neonatal gut is mature enough to make its own neurotransmitters, unique gut bacteria may supply neurotransmitters that are needed for critical biological functions during early development.

"We found that gut bacteria in young mice not only directly produce serotonin but also decrease an enzyme called monoamine oxidase that normally breaks down serotonin, thus keeping gut serotonin levels high," said the study's lead author Dr. Katherine Sanidad, postdoctoral associate in pediatrics at Weill Cornell Medicine.

The high serotonin levels shift the balance of immune cells by increasing the number of Tregs, which helps prevent the immune system from overreacting and attacking gut bacteria or food antigens. "The neonatal gut needs these serotonin-producing bacteria to keep the immune system in check," Dr. Sanidad added.

Healthy Immune System Helps Later in Life

Dr. Zeng noted that this work underscores the importance of having the right types of beneficial bacteria soon after birth. Babies in developed countries have better access to antibiotics, less exposure to diverse microbes in their clean environments and potentially unhealthy diets that may significantly impact the abundance of serotonin-producing bacteria in their intestines.

As a result, these babies may have fewer Tregs and develop immune reactions to their own gut bacteria, or allergies to food. This may be one reason food allergies have become increasingly common in children, particularly in developed countries. "If educated properly, the immune system in babies would recognize that things like peanuts and eggs are okay, and it doesn't have to attack them," she said. This may also have an impact on developing autoimmune diseases -- when the immune system attacks the body's own healthy cells -- later in life.

The team next plans to look at bacteria in human infant stool samples to measure their production of serotonin, other neurotransmitters and molecules that may help train the immune system to prevent future immune-related diseases, such as allergies, infections and cancer.

"It's essential to understand how the immune system is trained during early life, but this is understudied in newborns and children. Further studies of these developmental periods may hopefully lead us to mitigation approaches to reduce the risk of inflammatory diseases like food allergies and inflammatory bowel disease later in life," Dr. Sanidad said.

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New research suggests that our universe has no dark matter

The current theoretical model for the composition of the universe is that it's made of 'normal matter,' 'dark energy' and 'dark matter.' A new uOttawa study challenges this.

A University of Ottawa study published today challenges the current model of the universe by showing that, in fact, it has no room for dark matter.

In cosmology, the term "dark matter" describes all that appears not to interact with light or the electromagnetic field, or that can only be explained through gravitational force.

We can't see it, nor do we know what it's made of, but it helps us understand how galaxies, planets and stars behave.

Rajendra Gupta, a physics professor at the Faculty of Science, used a combination of the covarying coupling constants (CCC) and "tired light" (TL) theories (the CCC+TL model) to reach this conclusion.

This model combines two ideas -- about how the forces of nature decrease over cosmic time and about light losing energy when it travels a long distance.

It's been tested and has been shown to match up with several observations, such as about how galaxies are spread out and how light from the early universe has evolved.

This discovery challenges the prevailing understanding of the universe, which suggests that roughly 27% of it is composed of dark matter and less than 5% of ordinary matter, remaining being the dark energy.

Challenging the need for dark matter in the universe

"The study's findings confirm that our previous work ("JWST early Universe observations and ΛCDM cosmology") about the age of the universe being 26.7billionyears has allowed us to discover that the universe does not require dark matter to exist," explains Gupta.

"In standard cosmology, the accelerated expansion of the universe is said to be caused by dark energy but is in fact due to the weakening forces of nature as it expands, not due to dark energy."

"Redshifts" refer to when light is shifted toward the red part of the spectrum.

The researcher analyzed data from recent papers on the distribution of galaxies at low redshifts and the angular size of the sound horizon in the literature at high redshift.

"There are several papers that question the existence of dark matter, but mine is the first one, to my knowledge, that eliminates its cosmological existence while being consistent with key cosmological observations that we have had time to confirm," says Gupta.

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Drought, soil desiccation cracking, and carbon dioxide emissions: an overlooked feedback loop exacerbating climate change

The accuracy of climate models depends on many factors -- greenhouse gas emissions from industrial and transportation activity, farm animal "emissions," urban growth and loss of forests, and solar reflections off snow and ground cover. Natural phenomena like volcanic eruptions also contribute and are incorporated into models.

However, some other natural processes have been overlooked. Farshid Vahedifard, professor and Louis Berger Chair in civil and environmental engineering, points to an important one that lies directly beneath our feet and covers most of our planet above water.

In a study published in Environmental Research Letters, Vahedifard notes that soil stores 80 percent of carbon on Earth, and with increasing cycles and severity of droughts in several regions, that crucial reservoir is cracking and breaking down, releasing even more carbon dioxide and other greenhouse gases into the atmosphere.

In fact, it may be creating an amplified feedback loop that could accelerate climate change well beyond current predictions.

"This process has not been sufficiently evaluated in the existing literature or incorporated into models," said Vahedifard.

"If we don't consider the interplay of drought, soil desiccation cracking, and CO2 emissions, that could result in significant inaccuracies when modeling and predicting climate change. There are other repercussions as well. Poorer soil health can lead to reduced photosynthesis and lower carbon dioxide uptake, and it can compromise the structural integrity of earthen dams that protect against floods."

There are also other amplifying feedback loops that may not have been fully accounted for in climate change models, he said.

These include melting of sea ice and exposure of darker ocean surfaces that absorb more heat from the sun.

The increase of wildfires due to warm, dry conditions releases a lot of carbon dioxide into the atmosphere, which in turn creates hotter, drier weather more conducive to fires.

Another amplified feedback loop is the thawing of Arctic and sub-Arctic permafrost, which also releases carbon dioxide into the atmosphere and raises climate temperature, leading to more melted permafrost.

But soil changes caused by drought could be as significant, if not more significant, than any of those factors.

Drought, manifested by long periods of low soil moisture content and high temperature, leads to cracking in fine-grained soils, sometimes extending meters below the surface.

The cracks result in more exposure to the air, increased microbial activity and breakdown of organic matter, released carbon dioxide, and loss of nutrients and ability to support plant growth, reducing carbon dioxide sequestering.

The deep cracks expose much older reserves of carbon that had previously been stable and protected.

The permeation of air into the soil accelerates the release of not only carbon dioxide from organic matter but also other greenhouse gases like nitrous oxide.

Small animals like earthworms and millipedes that help turn the soil over are also affected by the reduced moisture and increased air exposure, being less able to play active roles in nutrient cycling and soil structure maintenance.

That, in turn, increases the likelihood of soil cracking and aeration.

"The amplifying effect of soil carbon feedback loops and its interactions with other loops could carry us across tipping points and lead to even more severe and permanent shifts in climate," said Vahedifard.

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Speaking without vocal cords, thanks to a new AI-assisted wearable device

People with voice disorders, including those with pathological vocal cord conditions or who are recovering from laryngeal cancer surgeries, can often find it difficult or impossible to speak. That may soon change.

A team of UCLA engineers has invented a soft, thin, stretchy device measuring just over 1 square inch that can be attached to the skin outside the throat to help people with dysfunctional vocal cords regain their voice function. Their advance is detailed this week in the journal Nature Communications.

The new bioelectric system, developed by Jun Chen, an assistant professor of bioengineering at the UCLA Samueli School of Engineering, and his colleagues, is able to detect movement in a person's larynx muscles and translate those signals into audible speech with the assistance of machine-learning technology -- with nearly 95% accuracy.

The breakthrough is the latest in Chen's efforts to help those with disabilities. His team previously developed a wearable glove capable of translating American Sign Language into English speech in real time to help users of ASL communicate with those who don't know how to sign.

The tiny new patch-like device is made up of two components. One, a self-powered sensing component, detects and converts signals generated by muscle movements into high-fidelity, analyzable electrical signals; these electrical signals are then translated into speech signals using a machine-learning algorithm. The other, an actuation component, turns those speech signals into the desired voice expression.

The two components each contain two layers: a layer of biocompatible silicone compound polydimethylsiloxane, or PDMS, with elastic properties, and a magnetic induction layer made of copper induction coils. Sandwiched between the two components is a fifth layer containing PDMS mixed with micromagnets, which generates a magnetic field.

Utilizing a soft magnetoelastic sensing mechanism developed by Chen's team in 2021, the device is capable of detecting changes in the magnetic field when it is altered as a result of mechanical forces -- in this case, the movement of laryngeal muscles. The embedded serpentine induction coils in the magnetoelastic layers help generate high-fidelity electrical signals for sensing purposes.

Measuring 1.2 inches on each side, the device weighs about 7 grams and is just 0.06 inch thick. With double-sided biocompatible tape, it can easily adhere to an individual's throat near the location of the vocal cords and can be reused by reapplying tape as needed.

Voice disorders are prevalent across all ages and demographic groups; research has shown that nearly 30% of people will experience at least one such disorder in their lifetime. Yet with therapeutic approaches, such as surgical interventions and voice therapy, voice recovery can stretch from three months to a year, with some invasive techniques requiring a significant period of mandatory postoperative voice rest.

"Existing solutions such as handheld electro-larynx devices and tracheoesophageal- puncture procedures can be inconvenient, invasive or uncomfortable," said Chen who leads the Wearable Bioelectronics Research Group at UCLA, and has been named one the world's most highly cited researchers five years in a row. "This new device presents a wearable, non-invasive option capable of assisting patients in communicating during the period before treatment and during the post-treatment recovery period for voice disorders."

How machine learning enables the wearable tech

In their experiments, the researchers tested the wearable technology on eight healthy adults. They collected data on laryngeal muscle movement and used a machine-learning algorithm to correlate the resulting signals to certain words. They then selected a corresponding output voice signal through the device's actuation component.

The research team demonstrated the system's accuracy by having the participants pronounce five sentences -- both aloud and voicelessly -- including "Hi, Rachel, how are you doing today?" and "I love you!"

The overall prediction accuracy of the model was 94.68%, with the participants' voice signal amplified by the actuation component, demonstrating that the sensing mechanism recognized their laryngeal movement signal and matched the corresponding sentence the participants wished to say.

Going forward, the research team plans to continue enlarging the vocabulary of the device through machine learning and to test it in people with speech disorders.

Read more at Science Daily

Do astronauts experience 'space headaches'?

Space travel and zero gravity can take a toll on the body. A new study has found that astronauts with no prior history of headaches may experience migraine and tension-type headaches during long-haul space flight, which includes more than 10 days in space. The study was published in the March 13, 2024, online issue of Neurology®, the medical journal of the American Academy of Neurology.

"Changes in gravity caused by space flight affect the function of many parts of the body, including the brain," said study author W. P. J. van Oosterhout, MD, PhD, of Leiden University Medical Center in the Netherlands.

"The vestibular system, which affects balance and posture, has to adapt to the conflict between the signals it is expecting to receive and the actual signals it receives in the absence of normal gravity. This can lead to space motion sickness in the first week, of which headache is the most frequently reported symptom. Our study shows that headaches also occur later in space flight and could be related to an increase in pressure within the skull."

The study involved 24 astronauts from the European Space Agency, the U.S. National Aeronautics and Space Administration (NASA) and the Japan Aerospace Exploration Agency.

They were assigned to International Space Station expeditions for up to 26 weeks from November 2011 to June 2018.

Prior to the study, nine astronauts reported never having any headaches and three had a headache that interfered with daily activities in the last year.

None of them had a history of recurrent headaches or had ever been diagnosed with migraine.

Of the total participants, 22 astronauts experienced one or more episode of headache during a total of 3,596 days in space for all participants.

Astronauts completed health screenings and a questionnaire about their headache history before the flight.

During space flight, astronauts filled out a daily questionnaire for the first seven days and a weekly questionnaire each following week throughout their stay in the space station.

The astronauts reported 378 headaches in flight.

Researchers found that 92% of astronauts experienced headaches during flight compared to just 38% of them experiencing headaches prior to flight.

Of the total headaches, 170, or 90%, were tension-type headache and 19, or 10%, were migraine.

Researchers also found that headaches were of a higher intensity and more likely to be migraine-like during the first week of space flight.

During this time, 21 astronauts had one or more headaches for a total of 51 headaches.

Of the 51 headaches, 39 were considered tension-type headaches and 12 were migraine-like or probable migraine.

In the three months after return to Earth, none of the astronauts reported any headaches.

"Further research is needed to unravel the underlying causes of space headache and explore how such discoveries may provide insights into headaches occurring on Earth," said Van Oosterhout.

"Also, more effective therapies need to be developed to combat space headaches as for many astronauts this a major problem during space flights."

This research does not prove that going into space causes headaches; it only shows an association.

A limitation of the study was that astronauts reported their own symptoms, so they may not have remembered all the information accurately.

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Tropical birds could tolerate warming better than expected, study suggests

Consider the globe, spinning silently in space. Its poles and its middle, the equator, remain relatively stable, thermally speaking, for the duration of Earth's annual circuit around the sun. The spaces between -- Earth's temperate zones -- experience seasons, with their characteristic temperature extremes.

It would follow that animals that evolved in each of these zones should match them, physiologically. We expect tropical animals to handle a certain degree of heat, but not wild swings in temperature. That seems to be the case for tropical ectotherms, or "cold-blooded" animals such as amphibians, reptiles, and insects. However, in a first-of-its-kind study of "warm-blooded" endotherms, a University of Illinois Urbana-Champaign team found tropical birds can handle thermal variation just fine.

"We tested the climate variability hypothesis, which predicts that organisms can't handle variation because they haven't seen it over evolutionary time," said study co-author Jeff Brawn, professor emeritus in the Department of Natural Resources and Environmental Sciences (NRES), part of the College of Agricultural, Consumer and Environmental Sciences (ACES) at Illinois. "That may be true for ectotherms, but the evidence is just not there yet for birds in the Neotropics. Now we know they're able to handle it."

Climate change may increase the average annual temperature in the tropics, as well as in microclimates like forest edges or tree canopies. The study provides some reassurance that, at least when looking at temperature alone, tropical birds should be okay. Why does that matter?

"The Neotropics alone are home to 40% of the world's bird species. Anyone who cares about birds should care about what's happening in the tropics," Brawn said. "Also, birds are important for the overall integrity of tropical forest systems, holding down insect populations that could damage trees."

Brawn and co-author Henry Pollock, who did postdoctoral research in NRES, already showed that both temperate and tropical birds can withstand temperature extremes, disproving the climate variability hypothesis across latitudes. Their new study explains whether variation within habitats matters for specific groups of tropical birds.

Many tropical birds spend their lives deep in the forest understory. Their large eyes suggest they're well adapted to the dark, where temperatures stay relatively cool and stable. Conversely, other bird groups zip between the forest canopy and its floor, or in and out of forest gaps and edges. These birds, Pollock reasoned, might have more tolerance to temperature fluctuations than their understory counterparts.

He captured birds from 89 species in Panama and, using a technique called respirometry, measured their metabolic rates across a range of temperatures. The birds were safely cooled and returned to their habitats after testing. He also took advantage of long-term weather station data provided by the Smithsonian Tropical Research Institute to document temperature differences across forest microclimates.

"If you measure temperature in an open area versus in the forest, there are large differences," said Pollock, now the executive director of the Southern Plains Land Trust. "But we did not find any evidence that those differences translated into greater temperature tolerance among groups of tropical birds."

Long-term observations indicate that when tropical forests become fragmented due to deforestation, an increasing phenomenon, certain groups of birds are more likely to decline. Insect-eating understory birds are among the hardest hit. For decades, tropical ornithologists believed narrow temperature tolerances may have been to blame for the declines of understory birds, but this study suggests otherwise.

Pollock is quick to point out that he only measured one aspect of an organism's thermal environment. In the real world, temperature doesn't increase in isolation; typically, when temperature goes up, so does solar radiation. Humidity and precipitation come into play, as well. And all of these things are part of the equation with habitat loss and climate change.

Still, one aspect of the climate variability and microclimate hypotheses can, for now, be put to rest for tropical birds.

"There's very little good news for tropical birds these days, but it's comforting that we've eliminated one factor as to what may go wrong with climate change. It's actually not a surprise; birds are very adaptable," Brawn said. "Heat tolerance alone presents an incomplete situation, but this is further empirical evidence that, if it does get warmer, tropical birds may be able to tolerate a certain level of that."

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Chimp moms play with their offspring through good times and bad

When it comes to nurturing their young, mother chimpanzees go the extra mile, according to a new study. Using 10 years of observational data on wild chimpanzees, researchers found that while adults often play, and young chimps play a lot, when food gets scarce, the adults put mutual play aside and focus on survival.

But in the meantime, mother chimps continue to be their offspring's primary playmate, tickling, chasing, playing 'airplane'. That suggests the mother chimps take on an indispensable role fostering their young's physical and social development even when they are under food stress.

The study observations took place in Kibale National Park in Uganda, and the study analysis, published in Current Biology, was led by Zarin Machanda, an assistant professor of anthropology and biology, and her former postdoctoral associate Kris Sabbi, who is currently a college fellow in human evolutionary biology at Harvard University.

Kibale is the most primate-dense forest in the world, with thirteen species living there including over 1,000 chimpanzees. Researchers started habituating the chimps to the presence of humans in 1987. Over the decades, teams of researchers took detailed field notes of almost every observable behavior -- including climbing, feeding, grooming, calling, aggression, and play.

Through their previous work, Machanda and Sabbi were familiar with the playfulness of chimpanzees and decided to look deeper into the patterns of play behavior. They expected seasonal variations in food availability would affect adult chimps' time spent playing.

For example, when supplies of quality fruits were low, the chimps focused on finding and gathering figs and leaves, and put play time aside. Surprisingly, although chimp mothers had the same challenge in finding food, they continued devoting a lot of their time to nurturing their offspring's development through play.

Learning Lessons from Play

"The research on play ties into an effort to understand the evolution of leadership among chimps," said Machanda. "We were trying to see whether chimps have only one pathway to leadership, which has always been assumed to be aggressiveness, or whether play and other behaviors build multiple dimensions of character that might make them more or less successful."

Play is not very common in the wild, at least among adult animals. Young mammals do play often, but mostly with each other, or at the expense of an exasperated and passive adult. Exceptions include dolphins, monkeys, and apes. Natural selection tends to suppress the costly exercise after it serves its purpose for development, and time comes to focus on finding food, watching out for predators, and mating. With chimps, however, adult play serves to cement social bonds.

Why do some primates play throughout life and other mammals don't? "I think what sets primates apart is that they spend more time growing up compared to other mammals," said Machanda. "They also have highly developed brains and live in structured groups, with very specific rules governing interactions between individuals. Play permits them to build not only physical skills, but also the skills of social interaction."

Social structure in the chimpanzee world may also explain why mother chimps sometimes become the primary play partners for their young. The chimpanzees have a very fluid social system called fission-fusion, which means a group of 60 chimps, for example, may have smaller groups break away for days or weeks, which then merge again while other groups break off.

When food becomes scarce, chimp mothers tend to break away into smaller groups or solo with their babies. "But when they're doing that, they are also limiting the ability of their young ones to play with others, and the moms become the primary playmates," said Sabbi. "They're trading off that lower feeding competition in the larger group for more time and energy being spent playing with their little ones."

By comparison, a troop of 60 baboons always sticks together, so baby baboons always have other baboons close to their age nearby to play with. Baboon mothers usually do not play with their babies.

Types of Play

Play among the chimps often divides depending on their sex. "It's not uncommon to see male chimps to engage in more aggressive types of play, while females are doing a type of play related to parenting," said Machanda. "You see them practice carrying things -- a kind of preparation for future maternal behavior. Males often size each other up, and when they hit their second birthday, play style changes and can get rougher."

Mothers are often the ones that juveniles and older infants come back to. "If they're playing with somebody and it starts to get a little bit too rough, they'll switch it up and go back to playing with mom, because at the end of the day it's a very safe place," said Sabbi.

"If we compare to humans, it's very easy to find lots of evidence in the child psychology literature for how important it is for human mothers and fathers to be playing with their children, especially at really young ages. Moms and dads are important first play partners before kids branch out into their own social networks," she said.

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Study: Best way to memorize stuff? It depends...

Recent experiments by psychologists at Temple University and the University of Pittsburgh shed new light on how we learn and how we remember our real-world experiences.

The research, described in the March 12 online edition of Proceedings of the National Academy of Sciences (PNAS), suggests that varying what we study and spacing out our learning over time can both be helpful for memory -- it just depends on what we're trying to remember.

"Lots of prior research has shown that learning and memory benefit from spacing study sessions out," said Benjamin Rottman, an associate professor of psychology and director of the Causal Learning and Decision-Making Lab at Pitt.

"For example, if you cram the night before a test, you might remember the information the next day for the test, but you will probably forget it fairly soon," he added. "In contrast, if you study the material on different days leading up to the test, you will be more likely to recall it for a longer period of time."

But while the "spacing effect" is one of the most replicated findings in psychological research, much of this work has been predicated on the idea that what you are trying to learn -- the content of the experience itself -- repeats identically each time. Yet that is rarely the case in real life, when some features of our experiences may stay the same, but others are likely to change. For example, imagine repeat trips to your local coffeeshop. While many features may stay the same on each visit, a new barista may be serving you. How does the spacing effect work in light of such variation across experiences?

In two experiments, Temple and Pitt researchers asked participants to repeatedly study pairs of items and scenes that were either identical on each repetition or in which the item stayed the same but the scene changed each time.

One of the experiments asked participants to learn and to test their memory via their smartphones -- an unusual approach for learning and memory research. This enabled researchers to ask participants to learn pairs at various times of the day across 24 hours, more accurately representing how people actually learn information.

In the second experiment, researchers collected data online in a single session.

Emily Cowan, lead author on the PNAS paper and a postdoctoral fellow in Temple's Adaptive Memory Lab, explained: "The combination of these two large-scale experiments allowed us to look at the timing of these 'spacing effects' across both long timescales -- for example, hours to days -- in Experiment No. 1 versus short timescales -- for example, seconds to minutes -- in Experiment No. 2. With this, we were able to ask how memory is impacted both by what is being learned -- whether that is an exact repetition or instead, contains variations or changes -- as well as when it is learned over repeated study opportunities.

"In other words, using these two designs, we could examine how having material that more closely resembles our experiences of repetition in the real world -- where some aspects stay the same but others differ -- impacts memory if you are exposed to that information in quick succession versus over longer intervals… from seconds to minutes, or hours to days."

As in prior experiments, researchers found that spaced learning benefited item memory. But they also found that memory was better for the items that had been paired with different scenes compared with those shown with the same scene each time. For example, if you want to remember a new person's name, repeating the name but associating it with different information about the person can actually be helpful.

"In contrast," Rottman said, "we found that for associative memory -- memory for the item and which scene it was paired with -- benefited from stability. Spacing only benefited memory for the pairs that were repeated exactly, and only if there were pretty long gaps -- hours to days -- between study opportunities. For example, if you are trying to remember the new person's name and something about them, like their favorite food, it is more helpful to repeat that same exact name-food pairing multiple times with spacing between each."

The Pitt-Temple experiments represent basic memory research. "Because of how nuanced memory is, it is hard to provide clear advice for things like studying for a test because the sort of material can be so different," Rottman said. "But in theory our findings should be broadly relevant to different sorts of tasks, like remembering someone's name and things about them, studying for a test, and learning new vocabulary in a foreign language.

"At the same time, because all these sorts of tasks have lots of differences, it is hard to make really concrete advice for them. We would need to do follow-up research to provide more concrete guidance for each case."

Cowan continued: "This work demonstrates the benefits of spaced learning on memory are not absolute, instead depending on the variability present in the content across repetitions and the timing between learning opportunities, expanding our current understanding of how the way in which we learn information can impact how it is remembered. Our work suggests that both variability and spacing may present methods to improve our memory for isolated features and associative information, respectively, raising important applications for future research, education, and our everyday lives."

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Ancient ice may still exist in distant space objects, researchers find

A paper recently accepted by Icarus presents findings about the Kuiper Belt Object 486958 Arrokoth, shedding new light on the preservation of volatile substances like carbon monoxide (CO) in such distant celestial bodies.

Co-authored by Dr. Samuel Birch at Brown University and SETI Institute senior research scientist Dr. Orkan Umurhan, the paper "Retention of CO Ice and Gas Within 486958 Arrokoth" uses Arrokoth as a case study to propose that many Kuiper Belt Objects (KBOs) -- remnants from the dawn of our solar system -- could still retain their original volatile ices, challenging previous notions about the evolutionary path of these ancient entities.

Previous KBO evolution models have needed help predicting the fate of volatiles in these cold, distant objects.

Many relied on cumbersome simulations or flawed assumptions, underestimating how long these substances could last.

The new research offers a simpler yet effective approach, likening the process to how gas escapes through porous rock.

It suggests that KBOs like Arrokoth can maintain their volatile ices for billions of years, forming a kind of subsurface atmosphere that slows further ice loss.

"I want to emphasize that the key thing is that we corrected a deep error in the physical model people had been assuming for decades for these very cold and old objects," said Umurhan.

"This study could be the initial mover for re- evaluating the comet interior evolution and activity theory."

This study challenges existing predictions and opens up new avenues for understanding the nature of comets and their origins.

The presence of such volatile ices in KBOs supports a fascinating narrative of these objects as "ice bombs," which activate and display cometary behavior upon altering their orbit closer to the sun.

This hypothesis could help explain phenomena like the intense outburst activity of comet 29P/Schwassmann- Wachmann, potentially changing the understanding of comets.

Read more at Science Daily

Multiple air pollutants linked to asthma symptoms in children

Exposure to several combinations of toxic atmospheric pollutants may be triggering asthma symptoms among children, a recent analysis suggests.

The study, published in the journal Science of the Total Environment, showed that 25 different combinations of air pollutants were associated with asthma symptoms among 269 elementary school children diagnosed with asthma in Spokane, Washington. In line with previous research, the Washington State University-led study revealed a socioeconomic disparity -- with one group of children from a lower-income neighborhood exposed to more toxic combinations, a total of 13 of the 25 identified in this research.

"It's not just one pollutant that can be linked to asthma outcomes. This study examined the variety and combinations of air toxics that may be associated with asthma symptoms," said lead author Solmaz Amiri, a WSU researcher in the Elson S. Floyd College of Medicine.

While other studies have focused on a limited number of pollutants, Amiri and her colleagues used the data-crunching power of machine learning techniques to analyze the potential exposure effects of 109 air pollutants and their combinations on asthma outcomes.

The researchers drew on data collected and modeled by the Environmental Protection Agency on air toxics present in individual neighborhoods surrounding 10 Spokane elementary schools. They also accessed anonymized data from the elementary schools for reports of students diagnosed with asthma who experienced symptoms such as coughing, wheezing, difficulty breathing and the need to use an inhaler.

The study looked at asthma symptoms occurring in 2019 and 2020 in the six months before the pandemic lockdowns started in March 2020. The researchers then associated these data with air pollutant exposures that occurred within those six months and with two longer-term exposure periods of three years and five years prior to the asthma symptoms.

The researchers found that three specific pollutants were significantly associated with asthma symptoms across all three exposure periods.

The toxicants involved may have unfamiliar names -- 1,1,1 trichloroethane, 2-nitropropane and 2, 4, 6 trichlorophenol -- but they derive from commonly used materials. The first is a widely used solvent in industry but was formerly used in household cleaners and glues. The second is an additive to paints and other finishes, and the third is an anti-septic and anti-mildew agent that was banned in the 1980s but may still be found in some pesticides and preservatives made before then.

"Some of these air toxics were discontinued in the U.S., but they can still be found in materials that may be in storage or people have in their backyard or garage. Other air toxics still exist at least in the environment," said Amiri.

This study did not intend to pinpoint the source of any one air pollutant or the exact reason why one group of children from a lower-income neighborhood was highly exposed to air pollutants. However, proximity of known air pollution sources may play a role, Amiri said, such as living close to a highway with a lot of traffic or facilities that use solvents, such as paint producers or factories.

The finding of a likely socioeconomic disparity in air toxic exposures is consistent with previous research showing that children from lower-income areas, often indicated by schools with a higher percentage of students who qualify for free or reduced meals, are exposed to a wide variety of air pollutants in the neighborhoods where they live.

While the current study is limited to the mid-sized city of Spokane, Amiri noted that the findings align with another study in New York City which found similar air pollutants significantly associated with asthma outcomes.

"Both in Spokane and New York City, regardless of the setting -- how large or small the cities are -- these air toxics appear to be influencing asthma among children," she said.

Read more at Science Daily