Unintended consequences of fire suppression

The escalation of extreme wildfires globally has prompted a critical examination of wildfire management strategies. A new study reveals how fire suppression ensures that wildfires will burn under extreme conditions at high severity, exacerbating the impacts of climate change and fuel accumulation.

The study used computer simulations to show that attempting to suppress all wildfires results in fires burning with more severe ecological impacts, with accelerated increases in burned area beyond those expected from fuel accumulation or climate change.

Fire suppression has unintended consequences, say the researchers. We've known for a long time that suppressing fires leads to fuel accumulation. Here, the researchers show a separate counter-intuitive outcome.

Though fire suppression reduces the overall area burned, it mainly eliminates low- and moderate-intensity fires. As a result, the remaining fires are biased to be more extreme. The study, "Fire suppression makes wildfires more severe and accentuates impact...," published in Nature Communications, shows how this "suppression bias" causes average fire severity to increase substantially.

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Over a human lifespan, the modeled impacts of the suppression bias outweigh those from fuel accumulation or climate change alone. This suggests that suppression may exert a significant and underappreciated influence on patterns of fire globally.

Fire suppression exacerbated the trends already caused by climate change and fuel accumulation, the study found, causing areas burned to increase three to five times faster over time relative to a world with no suppression.

Suppression, through preferentially removing low- and moderate-severity fire, also raised average fire severity by an amount equivalent to a century of fuel accumulation or climate change.

"By attempting to suppress all fires, we are bringing a more severe future to the present", say the researchers.

However, the new findings also show that allowing more low- and moderate-intensity fire can reduce or reverse the impacts of the suppression bias. Suppression strategies that allow fire to burn under moderate weather conditions—while still suppressing fires during more dangerous fire weather—reduced average fire severity and moderated the rate of burned area increase, the team found.

Developing and implementing technologies and strategies to safely manage wildfires during moderate burning conditions is essential. This approach may be just as effective as other necessary interventions, like mitigating climate change and decreasing unintentional human-related ignitions.

 Kreider, M.R., et al. Fire suppression makes wildfires more severe and accentuates impacts of climate change and fuel accumulation. Nature Communications (2024). doi.org/10.1038/s41467-024-46702-0

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The world is one step closer to secure quantum communication on a global scale

Researchers have brought together two Nobel prize-winning research concepts to advance the field of quantum communication.

Scientists can now efficiently produce nearly perfect entangled photon pairs from quantum dot sources. The research, "Oscillating photonic Bell state from a semiconductor quantum dot for quantum key distribution," was published in Communications Physics.

Entangled photons are particles of light that remain connected, even across large distances, and the 2022 Nobel Prize in Physics recognized experiments on this topic. Combining entanglement with quantum dots, a technology recognized with the Nobel Prize in Chemistry in 2023, the IQC research team aimed to optimize the process for creating entangled photons, which have a wide variety of applications, including secure communications.

By embedding semiconductor quantum dots into a nanowire, the researchers created a source that creates near-perfect entangled photons 65 times more efficiently than previous work.

This new source can be excited with lasers to generate entangled pairs on command. The researchers then used high-resolution single photon detectors provided by Single Quantum in The Netherlands to boost the degree of entanglement.

Using their new quantum dot entanglement source, the researchers simulated a secure communications method known as quantum key distribution, proving that the quantum dot source holds significant promise in the future of secure quantum communications.

Matteo Pennacchietti et al, Oscillating photonic Bell state from a semiconductor quantum dot for quantum key distribution, Communications Physics (2024). DOI: 10.1038/s42005-024-01547-3

Astronauts have surprising ability to know how far they 'fly' in space

New research finds that astronauts have a surprising ability to orient themselves and gauge distance traveled while free from the pull of gravity.

The findings of the study, done in collaboration with the Canadian Space Agency and NASA, have implications for crew safety in space and could potentially give clues to how aging affects people's balance systems here on Earth.

It has been repeatedly shown that the perception of gravity influences perceptual skill. The most profound way of looking at the influence of gravity is to take it away, which is why the researchers took their research into space.

Based on these findings it seems as though humans are surprisingly able to compensate adequately for the lack of an Earth-normal environment using vision.

The researchers studied a dozen astronauts aboard the International Space Station, which orbits about 400 kilometers from the Earth's surface.

Here, Earth's gravity is approximately canceled out by centrifugal force generated by the orbiting of the station. In the resulting microgravity, the way people move is more like flying. People have previously anecdotally reported that they felt they were moving faster or further than they really were in space, so this provided some motivation actually to record this.

The researchers compared the performance of a dozen astronauts—six men and six women—before, during, and after their year-long missions to the space station and found that their sense of how far they traveled remained largely intact.

The study, published recently in npj Microgravity, has been a decade in the making and represents the first of three papers that will emerge from the research investigating the effects of microgravity exposure on different perceptual skills including the estimation of body tilt, traveled distance, and object size.

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This research shows exposure to microgravity mimics the aging process on a largely physiological level—wasting of bones and muscles, changes in hormonal functioning, and increased susceptibility to infection—but this paper finds that self-motion is mainly unaffected, suggesting the balance issues that frequently come from old age may not be related to the vestibular system.

It suggests that the mechanism for the perception of movement in older people should be relatively unaffected and that the issues involved in falling may not be so much in terms of the perception of how far they've moved, but perhaps more to do with how they're able to convert that into a balance reflex.

Björn Jörges et al, The effects of long-term exposure to microgravity and body orientation relative to gravity on perceived traveled distance, npj Microgravity (2024). DOI: 10.1038/s41526-024-00376-6

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Pregnancy advances ‘biological age’
Studies in mice and humans suggest that being pregnant can increase a person’s ‘biological age’ by a couple of years — but giving birth reverses these changes. Biological age can be estimated from patterns of DNA methylation, which occurs when chemical methyl groups are added to DNA. The patterns reflect the stresses that a body accrues over time. The work supports the idea that “biological age is quite flexible; it’s a fluid parameter. It can go up and down”, says biomedical scientist Vadim Gladyshev.

https://www.nature.com/articles/d41586-024-00843-w?utm_source=Live+...

https://www.sciencedirect.com/science/article/abs/pii/S155041312400...

Pregnancy advances a woman's ‘biological’ age — but giving birth turns it back

The chemical tags analysed in the study are called methyl groups, and they are added to DNA in a process called methylation. They are one example of the ‘epigenome’, features of DNA that change gene activity without altering the genetic code.
DNA-methylation patterns can be used to estimate a person’s ‘biological age’, which reflects the physiological stresses that a person’s body has accrued over time. Some research has found that biological age is a better predictor of health problems such as cardiovascular disease3 and dementia4 than a person’s chronological age.
But unlike chronological age, “biological age is quite flexible; it’s a fluid parameter. It can go up and down”.

Physicists Capture Elusive 4D 'Ghost' in CERN Particle Accelerator

There's a specter haunting the tunnels of a particle accelerator at CERN.

In the Super Proton Synchrotron, physicists have finally measured and quantified an invisible structure that can divert the course of the particles therein, and create problems for particle research.

It's described as taking place in phase space, which can represent one or more states of a moving system. Since four states are required to represent the structure, the researchers view it as four-dimensional.

This structure is the result of a phenomenon known as resonance, and being able to quantify and measure it takes us a step closer to solving a problem universal to magnetic particle accelerators.

"With these resonances, what happens is that particles don't follow exactly the path we want and then fly away and get lost," says physicist Giuliano Franchetti of GSI in Germany. "This causes beam degradation and makes it difficult to reach the required beam parameters."

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Resonance occurs when two systems interact and sync up. It could be a resonance emerging between planetary orbits as they gravitationally interact in their journey around a star, or a tuning fork that starts to sympathetically ring when sound waves from another tuning fork hit its tines.

Particle accelerators use powerful magnets that generate electromagnetic fields to guide and accelerate beams of particles to where physicists want them to go. Resonances can occur in the accelerator due to imperfections in the magnets, creating a magnetic structure that interacts with particles in problematic ways.

The more degrees of freedom a dynamic system exhibits, the more complex it is to describe mathematically. Particles moving through a particle accelerator are usually described using just two degrees of freedom, reflecting the two coordinates needed to define a point on a flat grid.

To describe structures therein requires mapping them using additional features in phase space beyond just the up-down, left-right dimensions; that is, four parameters are needed to map each point in the space.

This, the researchers say, is something that could very easily "elude our geometric intuition".

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"In accelerator physics, the thinking is often in only one plane," Franchetti says. In order to map a resonance, however, the particle beam needs to be measured across both the horizontal and the vertical planes.

It sounds pretty straightforward, but if you're used to thinking about something a specific way, it might take an effort to think outside the box. Understanding the effects of resonance on a particle beam took quite a few years, and some hefty computer simulations.

However, that information opened the way for Franchetti, along with physicists Hannes Bartosik and Frank Schmidt of CERN, to finally measure the magnetic anomaly.

Using beam position monitors along the Super Proton Synchrotron, they measured the position of the particles for approximately 3,000 beams. By carefully measuring where the particles were centered, or skewed to one side, they were able to generate a map of the resonance haunting the accelerator.

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"What makes our recent finding so special is that it shows how individual particles behave in a coupled resonance," Bartosik says. "We can demonstrate that the experimental findings agree with what had been predicted based on theory and simulation."

The next step is to develop a theory that describes how individual particles behave in the presence of an accelerator resonance. This, the researchers say, will ultimately give them a new way to mitigate beam degradation, and achieve the high-fidelity beams required for ongoing and future particle acceleration experiments.

The team's research has been published in Nature Physics.

https://www.nature.com/articles/s41567-023-02338-3

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Scientists Ignited a Thermonuclear Explosion Inside a Supercomputer

Computer simulations are giving us new insight into the riotous behavior of cannibal neutron stars.

When a neutron star slurps up material from a close binary companion, the unstable thermonuclear burning of that accumulated material can produce a wild explosion that sends X-radiation bursting across the Universe.

How exactly these powerful eruptions evolve and spread across the surface of a neutron star is something of a mystery. But by trying to replicate the observed X-ray flares using simulations, scientists are learning more about their ins and outs – as well as the ultra-dense neutron stars that produce them.

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Neutron stars are some of the densest objects in the Universe. They're what's left over after a massive star has lived its life, run out of fuel, and exploded in a supernova.

While the outer material blasts off into space, though, the core of the star collapses under gravity, forming a super dense ball around 20 kilometers (12 miles) across, packing as much mass into that tiny sphere as up to 2.3 Suns or so.

Matter that is squished so densely is expected to be a bit wacky, to put it mildly. But scientists can study their thermonuclear bursts to place constraints on their size, which in turn can help model their interiors.

We can't exactly go cozy up to a neutron star to look at them more closely, for a number of reasons (distance, danger, that sort of thing), but we can collect all the information we can about neutron star X-ray bursts, and try to put together a simulation whose results match the observational data.

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That sounds simple, but the physics of neutron stars is really complicated; simulating their behavior requires a lot of computing power.

In previous work, the researchers used the Summit supercomputer at Oak Ridge National Laboratory to simulate the thermonuclear flames in two dimensions. Now they've built on that work, and scaled their simulations up to a third dimension.

The model 3D neutron star had a temperature several million times hotter than the Sun, and a spin speed of 1,000 rotations per second, which is pretty close to the theoretical upper limit of neutron star spin speed. Then, they simulated the early evolution of the thermonuclear flame.

Although the flame in the 2D simulation spread slightly faster than the 3D version, the growth trends in both models were very similar. This agreement means that the 2D simulation remains a good tool for studying these hectic explosions, but there are still some things it can't do.

For example, turbulence behaves differently in two and three dimensions; but being able to use the 2D sim for the parts it can do will free up computing power for other things, like increasing the fidelity of the burning

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With this information to hand, the simulations can be put to work to provide real insights into how neutron stars throw their tremendous tantrums.

"We're close to modeling the flame spread across the whole star from pole to pole.

https://iopscience.iop.org/article/10.3847/1538-4357/ace04e

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Scientists Warn The Price of Food Is Expected to Increase Every Year From Now on
Climate change, and specifically rising temperatures, may cause food prices to increase by 3.2% per year, according to a new study by researchers in Germany.

As climate change continues to worsen, this price inflation will mean more and more people around the world don't have a varied and healthy diet, or simply don't have enough food.

The new analysis shows that global warming could cause food price inflation to increase by between 0.9 and 3.2 percentage points per year by 2035. The same warming will cause a smaller rise in overall inflation (between 0.3 and 1.2 percentage points), so a greater proportion of household income would need to be spent on buying food.

This effect will be felt worldwide, by high and low-income countries alike, but nowhere more so than in the global south. As with various other consequences of climate change, Africa will be worst affected despite contributing little to its causes.

Shifting seasons, pests and diseases
The first is that the same climate change effects that are causing the inflation are already making food harder to get hold of. For instance, higher temperatures can cause long-established and predictable farming seasons to shift and so may hinder crop production.

Other consequences can include more pest and disease outbreaks that deplete livestock and food reserves, and heat stress to already-poor roads which makes it harder to access rural communities.
Part 1

https://files.springernature.com/getResource/Full%20text%20article....

All of these factors push prices higher and reduce the purchasing power of affected households. The drivers of food inflation are already worsening food insecurity.

The second part of this problem is the rise in inflation itself. A 3% annual price increase would mean households are less able to purchase what they need.

They would likely need to compromise on quality or perhaps even culturally important foods. This in turn makes people more vulnerable to disease and other health issues. Malnutrition is the leading cause of immunodeficiency globally.

Alterations in the climate are a hunger-risk multiplier for those populations with entrenched vulnerability. In light of this, 134 countries at COP28 signed a declaration to incorporate food systems into their climate action, to ensure everyone has enough to eat in light of climate change.

The researchers behind the new study suggest that reducing greenhouse gas emissions could limit any impacts on the global economy. We also suggest that diversifying economies would serve as some protection for those communities reliant on agriculture for both their food and income.

Government intervention could also ensure financial protection and nutritional aid for those vulnerable to becoming trapped in the poverty cycle by inflation and diminished accessibility to food.

https://theconversation.com/food-prices-will-climb-everywhere-as-te...

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Tiniest 'starquakes' detected

At a distance of 11.9 light years, Epsilon Indi (ε Indi) is an orange dwarf star (also known as a K dwarf) with 71% of the sun's diameter. An international team, led by Instituto de Astrofísica e Ciências do Espaço (IA) researcher Tiago Campante, studied this star with the ESPRESSO spectrograph, mounted at the European Southern Observatory's (ESO) Very Large Telescope (VLT), and detected the tiniest "starquakes" ever recorded.

The team used a technique dubbed asteroseismology, which measures oscillations in stars. These provide indirect glimpses of stellar interiors, just as earthquakes tell us about Earth's interior. In ε Indi, the peak amplitude of the detected oscillations is just 2.6 centimeters per second (about 14% of the sun's oscillation amplitude), which makes it the smallest and coolest dwarf star observed to date with confirmed solar-like oscillations.

These measurements are so precise that the detected speed is slower than the average speed of a sloth.

The extreme precision level of these observations is an outstanding technological achievement. Importantly, this detection conclusively shows that precise asteroseismology is possible down to cool dwarfs with surface temperatures as low as 4,200 degrees Celsius, about 1,000 degrees cooler than the sun's surface, effectively opening up a new domain in observational astrophysics.

This level of precision might help scientists settle a long-standing disagreement between theory and observations in what concerns the relation between the mass and the diameter of these cool-dwarf stars.

These "starquakes" can now be used to help plan the future European Space Agency's (ESA) PLATO space telescope, a mission in which IA is strongly involved. The oscillation amplitudes measured in this study can be converted to amplitudes in photometry, as they will be measured by PLATO, this being a key piece of information to help accurately predict the seismic yield of PLATO, scheduled to be launched in 2026.

Campante et al, Expanding the frontiers of cool-dwarf asteroseismology with ESPRESSO. Detection of solar-like oscillations in the K5 dwarf ϵ Indi, Astronomy & Astrophysics (2024). DOI: 10.1051/0004-6361/202449197

Albedo can reduce climate benefit of tree planting: New tool identifies locations with high climate-cooling potential

As efforts to restore tree cover accelerate to help avoid runaway climate change, a new study highlights how restoring tree cover can, in some locations, heat up the Earth rather than cool it by affecting how much sunlight the surface reflects (i.e. "the albedo").

This new study by researchers published recently in the journal Nature Communications, provides a global analysis of where restoration of tree cover is most effective at cooling the global climate system, considering not just the cooling from carbon storage but also the warming from decreased albedo.

The researchers provide a tool practitioners and land managers can use to determine just how much of a problem albedo is for any reforestation or afforestation project on the globe. The authors use these new maps to show that previously published 'carbon-only' estimates of the global climate mitigation potential of restoring trees worldwide provided significant overestimation, being anywhere from 20 to 81% too high. Because comprehensive maps of the consequences of albedo change were not previously available, these carbon-only estimates tend to identify too many options in landscapes—particularly semi-arid settings and snowy, boreal regions—where changes in albedo would significantly offset, or even negate, the carbon-removing benefits provided by these trees.

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The balance of carbon storage versus albedo change that comes from restoring tree cover varies from place to place, but until now we didn't have the tools to tell the good climate solutions from the bad.

This study aims to change that, providing the maps needed to empower smarter decisions while also ensuring that limited finance is directed at those locations where restoring tree cover can make the most positive difference as a natural climate solution.

On the positive, the study also identifies locations within every biome on Earth where the climate mitigation benefits of tree-planting can be achieved. Better still, it also finds that most of the thousands of on-the-ground projects underway globally to restore tree cover are concentrated in these zones of greatest opportunity. Even in these locations, however, albedo changes are likely to offset the net climate benefit by at least 20 percent in around two-thirds of cases.

Researchers have now addressed a significant research gap and gained a much more complete picture of how restoring tree cover can impact our global climate—both positively and also sometimes negatively.

However, it's important to remember that there are many other sound reasons to restore tree cover, even in locations where the climate benefits aren't stellar: clean water, resilient food production, wildlife habitat, the list goes on... Researchers are 're simply calling on governments and land managers to more carefully integrate albedo in their environmental decision-making and are open-sourcing this robust new set of tools to help them do so.

Hasler N., Accounting for albedo change to identify climate positive tree cover restoration., Nature Communications (2024). DOI: 10.1038/s41467-024-46577-1 , www.nature.com/articles/s41467-024-46577-1

To read more about efforts to restore tree cover and to chart the full potential of nature to mitigate climate change, visit naturebase.org to learn more.

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Dust storms may spread bacteria and fungi around the world

When allergy season hits, many blame their reactions on the local flora in the spring. However, African Saharan-Sahelian dust plumes, large enough to register on weather radar, travel around the globe every summer, bringing their own form of air pollution.

Researchers  have furthered previous research to identify microorganisms that might have hitched a ride in the du.... 

We all get allergies and potentially other more severe health effects when we breathe in dust, and it's not fully known as to what causes those allergies. Some people may think it is just the sand or clay minerals in the dust. Others think it is the metals or organics in the dust, and then some think it's the bacteria and fungi.

This research, published in the journal Environmental Science & Technology, is the first to study the association of bacteria and fungi with North American–Saharan dust storms.

Scientists noted that dust events can vary annually, with different elemental compositions each year.

 Microbiota was detected by extracting DNA from filters. Meticulous sequencing techniques detected bacterial genomes from 117 families and fungal genomes from 164 families. The technique did not show whether the microbes were alive, but it did detect several pathogenic bacteria and fungi, many of which are listed in the World Health Organization's global priority list of human pathogens.

It doesn't tell us if they are going to be able to infect us and make us sick. But at least the DNA of several pathogenic bacteria and fungi were identified in the African dust.

The biodiversity of bacteria and fungi was strongly correlated to a few elements, most notably calcium. The study showed that calcium and zirconium are important for explaining bacterial and fungal beta diversity, the ratio between regional and local species diversity.

A similar caveat was found in biota detections. Over 2,000 different organic groups were detected. 

Sourav Das et al, Respirable Metals, Bacteria, and Fungi during a Saharan–Sahelian Dust Event in Houston, Texas, Environmental Science & Technology (2023). DOI: 10.1021/acs.est.3c04158

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If you've got a dark roof, you're spending almost $700 extra a year to keep your house cool

A dark roof means you'll pay considerably more to keep your house cool in summer.When suburbs are full of dark colored roofs, the whole area heats up. And up. And up. This is part of the urban heat island effect.

Light coloured roofs or Cool roofs have many benefits. They slash how much heat gets into your house from the sun, keep the air surrounding your home cooler, boost your aircon efficiency, and make your solar panels work more efficiently.

At present, the world's cities account for 75% of all energy-related carbon dioxide emissions. It's vitally important we understand what makes cities hotter or cooler.

Brick, concrete, tarmac and tiles can store more heat than grass and tree-covered earth can, and release it slowly over time. This keeps the air warmer, even overnight.

Built-up areas also block wind, which cuts cooling. Then there's transport, manufacturing and air-conditioning, all of which increase heat.

The main way people had to keep cool was through how they designed their homes. In hot countries, buildings are often painted white, as well as having small windows and thick stone walls.

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How can we cool our cities

Weird electron behaviour thrills physicists

Two teams have observed that electrons, which usually have a charge of –1, can behave as if they had fractional charges (such as –⅔) — and do so without being nudged by an external magnetic field. It’s the first time this ‘fractional quantum anomalous Hall effect’ has been observed experimentally, and physicists are scratching their heads over exactly how it works. It’s a fundamental discovery that might also someday have practical applications: fractionally charged particles are a key requirement for a certain type of quantum computer. 

symbolic gesture in birds

Japanese tits (Parus minor) flutter their wings to invite their mate to enter the nest first. Scientists who observed eight breeding pairs of wild tits noticed that when one of the birds sat in front of the next box and fluttered its wings, the other would go in first. It’s the first documented evidence of birds using a symbolic gesture: one that has a specific meaning (like waving ‘goodbye’) but isn’t simply pointing at an object of interest. “It implies that birds have a level of understanding of symbolism that probably a lot of people wouldn’t have given them credit for before.

Astronomers unveil strong magnetic fields spiraling at the edge of Milky Way's central black hole

A new image from the Event Horizon Telescope (EHT) collaboration—which includes scientists from the Center for Astrophysics | Harvard & Smithsonian (CfA)— has uncovered strong and organized magnetic fields spiraling from the edge of the supermassive black hole Sagittarius A* (Sgr A*).

Seen in polarized light for the first time, this new view of the monster lurking at the heart of the Milky Way galaxy has revealed a magnetic field structure strikingly similar to that of the black hole at the center of the M87 galaxy, suggesting that strong magnetic fields may be common to all black holes. This similarity also hints toward a hidden jet in Sgr A*.

The results were published in The Astrophysical Journal Letters.

Scientists unveiled the first image of Sgr A*—which is approximately 27,000 light-years away from Earth—in 2022, revealing that while the Milky Way's supermassive black hole is more than a thousand times smaller and less massive than M87's, it looks remarkably similar.

So scientists decided to check whether they are similar in all the  ways possible.

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Light is an oscillating or moving, electromagnetic wave that allows us to see objects. Sometimes, light oscillates in a preferred orientation, and we call it "polarized." Although polarized light surrounds us, to human eyes it is indistinguishable from "normal" light.

In the plasma around these black holes, particles whirling around magnetic field lines impart a polarization pattern perpendicular to the field. This allows astronomers to see in increasingly vivid detail what's happening in black hole regions and map their magnetic field lines.

By imaging polarized light from hot glowing gas near black holes, researchers are directly inferring the structure and strength of the magnetic fields that thread the flow of gas and matter that the black hole feeds on and ejects. Polarized light teaches us a lot more about the astrophysics, the properties of the gas, and mechanisms that take place as a black hole feeds.

Scientists are excited to have images of both supermassive black holes in polarized light because these images and the data that come with them provide new ways to compare and contrast black holes of different sizes and masses. As technology improves, the images are likely to reveal even more secrets of black holes and their similarities or differences.

 "M87* and Sgr A* are different in a few important ways: M87* is much bigger, and it's pulling in matter from its surroundings at a much faster rate. So, we might have expected that the magnetic fields also look very different. But in this case, they turned out to be quite similar, which may mean that this structure is common to all black holes.

A better understanding of the magnetic fields near black holes helps us answer several open questions—from how jets are formed and launched to what powers the bright flares we see in infrared and X-ray light. 

Issaoun, S. et al, First Sagittarius A* Event Horizon Telescope Results. VII. Polarization of the Ring, The Astrophysical Journal Letters (2024), DOI: 10.3847/2041-8213/ad2df0

Ricarte A. et al, "First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring," The Astrophysical Journal Letters (2024), DOI: 10.3847/2041-8213/ad2df1

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Making long-term memories requires DNA damage, researchers discover

Just as you can't make an omelet without breaking eggs, scientists at Albert Einstein College of Medicine have found that you can't make long-term memories without DNA damage and brain inflammation. Their surprising findings were published in the journal Nature in a paper titled "Formation of memory assemblies through the DNA sensing TLR9 pathway."

Inflammation of brain neurons is usually considered to be a bad thing, since it can lead to neurological problems such as Alzheimer's and Parkinson's disease. But these new findings suggest that inflammation in certain neurons in the brain's hippocampal region is essential for making long-lasting memories.

The hippocampus has long been known as the brain's memory center.  Researchers found that a stimulus sets off a cycle of DNA damage and repair within certain hippocampal neurons that leads to stable memory assemblies—clusters of brain cells that represent our past experiences.

The researchers discovered this memory-forming mechanism by giving mice brief, mild shocks sufficient to form a memory of the shock event (episodic memory). They then analyzed neurons in the hippocampal region and found that genes participating in an important inflammatory signaling pathway had been activated.

Researchers observed strong activation of genes involved in the Toll-Like Receptor 9 (TLR9) pathway. This inflammatory pathway is best known for triggering immune responses by detecting small fragments of pathogen DNA. So at first scientists assumed the TLR9 pathway was activated because the mice had an infection. But looking more closely, they found, to their surprise, that TLR9 was activated only in clusters of hippocampal cells that showed DNA damage.

Brain activity routinely induces small breaks in DNA that are repaired within minutes. But in this population of hippocampal neurons, the DNA damage appeared to be more substantial and sustained.

Part 1

Triggering inflammation to make memories

Further analysis showed that DNA fragments, along with other molecules resulting from the DNA damage, were released from the nucleus, after which the neurons' TLR9 inflammatory pathway was activated; this pathway in turn stimulated DNA repair complexes to form at an unusual location: the centrosomes.

These organelles are present in the cytoplasm of most animal cells and are essential for coordinating cell division. But in neurons—which don't divide—the stimulated centrosomes participated in cycles of DNA repair that appeared to organize individual neurons into memory assemblies.

Cell division and the immune response have been highly conserved in animal life over millions of years, enabling life to continue while providing protection from foreign pathogens.

It seems likely that over the course of evolution, hippocampal neurons have adopted this immune-based memory mechanism by combining the immune response's DNA-sensing TLR9 pathway with a DNA repair centrosome function to form memories without progressing to cell division.

Part 2

During the week required to complete the inflammatory process, the mouse memory-encoding neurons were found to have changed in various ways, including becoming more resistant to new or similar environmental stimuli.

This is noteworthy because we're constantly flooded by information, and the neurons that encode memories need to preserve the information they've already acquired and not be 'distracted' by new inputs.

Importantly, the researchers found that blocking the TLR9 inflammatory pathway in hippocampal neurons not only prevented mice from forming long-term memories but also caused profound genomic instability, i.e., a high frequency of DNA damage in these neurons.

Genomic instability is considered a hallmark of accelerated aging as well as cancer and psychiatric and neurodegenerative disorders such as Alzheimer's.

Drugs that inhibit the TLR9 pathway have been proposed for relieving the symptoms of long COVID. But caution needs to be shown because fully inhibiting the TLR9 pathway may pose significant health risks, say the researchers. 

 Jelena Radulovic, Formation of memory assemblies through the DNA-sensing TLR9 pathway, Nature (2024). DOI: 10.1038/s41586-024-07220-7. www.nature.com/articles/s41586-024-07220-7

Part 3

Scientists discover how caterpillars can stop their 'bleeding' in seconds

Fully grown tobacco hornworms, ready to pupate, are between 7.5cm and 10cm long. They only contain a minute amount of hemolymph, which typically clots within seconds

Blood is a remarkable material: it must remain fluid inside blood vessels, yet clot as quickly as possible outside them, to stop bleeding. The chemical cascade that makes this possible is well understood for vertebrate blood. But hemolymph, the equivalent of blood in insects, has a very different composition, being notably lacking in red blood cells, hemoglobin, and platelets, and having amoeba-like cells called hemocytes instead of white blood cells for immune defense.

Just like blood, hemolymph clots quickly outside the body. How it does so has long remained an enigma. Now, materials scientists have shown in Frontiers in Soft Matter how this feat is managed by caterpillars of the Carolina sphinx moth. This discovery has potential applications for human medicine, the authors said.

 These caterpillars, called tobacco hornworms, can seal the wounds within a minute. They do that in two steps: first, in a few seconds, their thin, water-like hemolymph becomes 'viscoelastic' or slimy, and the dripping hemolymph retracts back to the wound.

Next, hemocytes aggregate, starting from the wound surface and moving up to embrace the coating hemolymph film that eventually becomes a crust sealing the wound.

To seal a wound, caterpillars transform blood from a viscous to a viscoelastic fluid in a few seconds, Frontiers in Soft Matter (2024). DOI: 10.3389/frsfm.2024.1341129. www.frontiersin.org/articles/1 … fm.2024.1341129/full

Risk factors for faster aging in the brain revealed in new study

In a new study published in Nature Communications, researchers investigated the genetic and modifiable influences on fragile brain regions by looking at the brain scans of 40,000 UK Biobank participants aged over 45.

Previously, the researchers had identified a 'weak spot' in the brain, which is a specific network of higher-order regions that not only develop later during adolescence, but also show earlier degeneration in old age. They showed that this brain network is also particularly vulnerable to schizophrenia and Alzheimer's disease.

In their latest study, the researchers examined 161 risk factors for dementia, and ranked their impact on this vulnerable brain network, over and above the natural effects of age.

They classified these so-called 'modifiable' risk factors—as they can potentially be changed throughout life to reduce the risk of dementia—into 15 broad categories: blood pressure, cholesterol, diabetes, weight, alcohol consumption, smoking, depressive mood, inflammation, pollution, hearing, sleep, socialization, diet, physical activity, and education.

We know that a constellation of brain regions degenerates earlier in aging, and in this new study researchers  have shown that these specific parts of the brain are most vulnerable to diabetes, traffic-related air pollution—increasingly a major player in dementia—and alcohol, of all the common risk factors for dementia.

They have found that several variations in the genome influence this brain network, and they are implicated in cardiovascular deaths, schizophrenia, Alzheimer's and Parkinson's diseases, as well as with the two antigens of a little-known blood group, the elusive XG antigen system, which was an entirely new and unexpected finding.

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In fact, two of these seven genetic findings are located in this particular region containing the genes of the XG blood group, and that region is highly atypical because it is shared by both X and Y sex chromosomes. This is really quite intriguing as we do not know much about these parts of the genome; our work shows there is benefit in exploring further this genetic terra incognita.

It is with this kind of comprehensive, holistic approach—and once we had taken into account the effects of age and sex—that three emerged as the most harmful: diabetes, air pollution, and alcohol.

This research sheds light on some of the most critical risk factors for dementia, and provides novel information that can contribute to prevention and future strategies for targeted intervention.

The effects of genetic and modifiable risk factors on brain regions vulnerable to ageing and disease, Nature Communications (2024). DOI: 10.1038/s41467-024-46344-2

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'Exhausted' immune cells in healthy women could be target for breast cancer prevention

Risk-reducing surgery, in which the breasts are removed, is offered to those at increased risk of breast cancer. This can be a difficult decision for young women to make and can have a significant effect on body image and conjugal relationships.

Late-stage breast cancer tends to be very unpredictable and hard to manage. As we make better and better drugs, the tumors just seem to find a way around it.

The best way to prevent breast cancer is to really understand how it develops in the first place. Then we can identify these early changes and intervene.

Researchers at the University of Cambridge have created the world's largest catalogue of human breast cells, which has revealed early cell changes in healthy carriers of BRCA1 and BRCA2 gene mutations.

Everyone has BRCA1 and BRCA2 genes, but mutations in these genes—which can be inherited—increase the risk of breast and ovarian cancer.

The study found that the immune cells in breast tissue of healthy women carrying BRCA1 or BRCA2 gene mutations show signs of malfunction known as exhaustion. This suggests that the immune cells can't clear out damaged breast cells, which can eventually develop into breast cancer.
This is the first time that exhausted immune cells have been reported in non-cancerous breast tissues at such scale—normally these cells are only found in late-stage tumors. The results raise the possibility of using existing immunotherapy drugs as early intervention to prevent breast cancer developing, in carriers of BRCA1 and BRCA2 gene mutations.

The researchers plan to trial this preventative approach in mice. Existing drugs have serious side effects, so testing in mice is necessary to find the right safe dosage. If effective, this will pave the way to a pilot clinical trial in women carrying BRCA gene mutations.

The research  results suggest that in carriers of BRCA mutations, the immune system is failing to kill off damaged breast cells—which in turn seem to be working to keep these immune cells at bay.

Scientists are very excited about this discovery, because it opens up potential for a preventative treatment other than surgery for carriers of BRCA breast cancer gene mutations. Drugs already exist that can overcome this block in immune cell function, but so far, they've only been approved for late-stage disease. No one has really considered using them in a preventative way before.

Using samples of healthy breast tissue collected from 55 women across a range of ages, the researchers catalogued over 800,000 cells—including all the different types of breast cell. The resulting Human Breast Cell Atlas is now available as a resource for other researchers to use and add to. It contains huge amounts of information on other risk factors for breast cancer including Body Mass Index (BMI), menopausal status, contraceptive use and alcohol consumption. Researchers found that there are multiple breast cell types that change with pregnancy, and with age, and it's the combination of these effects—and others—that drives the overall risk of breast cancer.

A single-cell atlas enables mapping of homeostatic cellular shifts in the adult human breast, Nature Genetics (2024). DOI: 10.1038/s41588-024-01688-9

Google Street View reveals how built environment correlates with risk of cardiovascular disease

Researchers have used Google Street View to study hundreds of elements of the built environment, including buildings, green spaces, pavements and roads, and how these elements relate to each other and influence coronary artery disease in people living in these neighborhoods.

Their findings, published in the European Heart Journal recently, show that these factors can predict 63% of the variation in the risk of coronary heart disease from one area to another.

Coronary heart disease, where a build-up of fatty substances in the coronary arteries interrupts the blood supply to the heart, is one of the most common forms of cardiovascular disease.

Researchers say that using Google Street View can help provide an overview of physical environmental risk factors in the built and natural environments that could help not only in understanding risk factors in these environments, but ultimately help towards building or adapting towns and cities to make them healthier places to live.

The research revealed that features of the built environment visible on Google Street View images could predict 63% of the variation in coronary heart disease between these small regions.

The association of residential location with outcomes often supersedes that of known biological risk factors. This is often summarized with the expression that a person's postal code is a bigger determinant of their health than their genetic code. However, our ability to appropriately classify environmental risk factors has relied on population surveys that track wealth, pollution, and community resources.

Zhuo Chen et al, Artificial intelligence-based assessment of built environment from Google Street View and coronary artery disease prevalence, European Heart Journal (2024). DOI: 10.1093/eurheartj/ehae158

Rohan Khera, Artificial intelligence-enhanced exposomics: novel insights into cardiovascular health, European Heart Journal (2024). DOI: 10.1093/eurheartj/ehae159

Researchers have shown that  they can use computer vision approaches to help identify environmental factors influencing cardiovascular risk and this could play a role in guiding heart-healthy urban planning. The fact that they  can do this at scale is something that is absolutely unique and important for urban planning.

Climate change is slowing Earth’s rotation
Melting ice caps are slowing the rotation of the Earth and could delay the next leap second by three years. Adding or removing seconds every few years keeps official atomic-clock time in line with the natural day, which varies slightly in line with the planet’s rotation rate. Since the early 1990s, the flow of water away from Earth’s axis of rotation and towards the Equator has worked to slightly slow down its spin. “It’s yet another way of impressing upon people just how big a deal [climate change] is,” says geophysicist and study author Duncan Agnew.

https://www.nature.com/articles/d41586-024-00932-w?utm_source=Live+...

Old immune system becomes young again
Antibodies rejuvenate immune responses in old mice by targeting stem cells that replenish white and red blood cells. The balance of these stem cells changes as mice (and humans) age — this might be one reason why older animals mount less of an immune response against pathogens. Aged mice that received the antibody treatment had a stronger reaction to vaccination, and were better able to fend off viral infection, than untreated rodents.

Nature | 
Read an expert analysis by developmental biologist Yasar Arfat Kasu and stem-cell biologist Robert Signer in the Nature News & Views article 
Reference: Nature paper

Gravitational waves may have made human life possible

Could it be that human existence depends on gravitational waves? Some key elements in our biological makeup may come from astrophysical events that occur because gravitational waves exist, a research team suggests.

In particular, iodine and bromine are found on Earth thanks to a particular nuclear process that happens when neutron stars collide. In turn, orbiting neutron star pairs inspiral and collide due to their emissions of energy in the form of gravitational waves. There may thus be a direct path from the existence of gravitational waves to the existence of mammals.

Humans are mostly made up of hydrogen, carbon and oxygen, with many additional trace elements. (There are 20 elements essential to human life.) Those with an atomic number less than 35 are produced in supernovae, implosions of stars that have exhausted their nuclear fuel and collapsed inward. The collapse results in an explosion that spews their atoms all over the universe.

But two elements are provided by other means—iodine, needed in key hormones produced by the thyroid, and bromine, used to create collagen scaffolds in tissue development and architecture.

Thorium and uranium have been indirectly important for human life, as their radioactive decays in Earth's interior heat the lithosphere and allow tectonic activity. The movement of tectonic plates removes and submerges carbon from the crust of the planet, which is itself removed from the atmosphere via water reacting with carbon dioxide and silicates, avoiding the possibility of a runaway greenhouse effect like has happened on Venus.

About half the heavy elemental atoms on Earth (heavier than iron) are produced by what's known as the "r-process"—the rapid neutron-capture process. The r-process occurs when a heavy atomic nucleus captures a succession of free neutrons before the nucleus has had a chance to decay (usually by beta decay). With a high enough density of free neutrons, calculated to be about 1024 per cubic centimeter, and at high temperatures, around a billion Kelvin, neutrons are absorbed and heavier isotopes of an element are synthesized.

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Researchers calculate that the r-process has provided 96% of the abundance of 127I on Earth, an isotope essential for human life, and most of the abundance of bromine and gadolinium in the Earth's crust, plus all of the Earth's thorium and uranium and a fraction of the molybdenum and cadmium.

Where does the r-process occur? One possibility is the material ejected during the rebound from a core-collapse supernova, the explosions of stars near the end of their thermonuclear lifetimes. But there is long-standing uncertainty in the detailed physics of this process.
One phenomenon where the r-process does occur is the merger of two neutron stars, called a kilonova. Such mergers are directly caused by gravitational waves.

As the binary pair spiral towards one another over hundreds of millions of years, they radiate an enormous amount of energy in the form of gravitational waves near the end. The amount of energy can be huge—trillions of trillions of watts in the last few milliseconds.
Kilonovae outbursts are important sites of the r-process, as neutron stars are made almost entirely of neutrons. Besides the gravitational wave observatories, other detectors detected GW170817 in the electromagnetic spectrum, and found spectroscopic evidence of the material created and tossed out from the merger.

The paper concludes that the iodine essential for human life was "probably produced by the r-process in the collisions of neutron stars that were induced by the emissions of gravitational waves, as well as other essential heavy elements." The group suggests searching for 129I in lunar regolith, which is uncontaminated by manmade sources.
Neutron star collisions occur because binary systems lose energy by emitting gravitational waves - so these fundamental physics phenomena may have made human life possible.

John Ellis et al, Do we owe our existence to gravitational waves?, arXiv (2024). DOI: 10.48550/arxiv.2402.03593

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An infamous 'inflammasome'—a rogue protein complex—appears to underlie a rare and disabling autoimmune disorder

Autoimmune diseases are among the most puzzling because turncoat constituents of the body wage a constant state of war. Sometimes the underlying cause of an autoimmune condition is so obscure—hidden within chemical miscues of the body—that a long investigatory search must be mounted to sleuth out a cause.

And so it has been with in-depth research to understand an extremely rare autoimmune disorder. The condition is known as CAPS—cryopyrin-associated periodic syndrome. It afflicts patients with an array of disparate symptoms, ranging from skin rashes to permanent hearing loss.

To understand the disorder, scientists have had to explore the influences of cellular biomechanics and the roles of chemical miscues linked to an infamous inflammasome, a protein complex that triggers extreme inflammatory activity. CAPS, scientists now say, occurs because of an inflammasome that's gone rogue. Inflammasomes are multi-protein complexes found in the cytosol of cells that rapidly assemble and activate proinflammatory signaling in response to a diverse number of stimuli.

Normally, inflammasomes guard us against infection and cancer by triggering the domino effect of a powerful immune response. But inflammasome activity can also go awry and cause uncontrolled inflammation. Indeed, conditions known as autoinflammatory disorders, like CAPS, can occur when the body creates an immune response without an easily discernable cue, leading to a host of debilitating lifelong symptoms.

Like CAPS, there are other rare autoinflammatory conditions that cause a range of symptoms, from skin rashes to devastating inflammatory responses leading to fever, blindness, deafness, and cognitive decline.

CAPS, researchers say, is related to the overactivation of a notorious inflammasome—NLRP3—which can be influenced by miscues in mechanical signaling. Mechanical signaling occurs when cells in close contact with each other send errant signals that move through the cytoskeletons of affected cells.

The new research describes how mechanical signaling involving immune cells' membrane proteins can lead to autoimmunity affecting patients with CAPS. The rare disorder, which usually begins in infancy, is marked by waxing and waning lifelong symptoms. It's characterized by rashes, joint pain, red eyes and severe headaches with vomiting. Hearing loss usually occurs during the teen years and is often permanent.

Li Ran et al, KCNN4 links PIEZO-dependent mechanotransduction to NLRP3 inflammasome activation, Science Immunology (2023). DOI: 10.1126/sciimmunol.adf4699

Genetic causes of cerebral palsy uncovered through whole-genome sequencing

A new study by researchers  has identified genes which may be partially responsible for the development of cerebral palsy.

Cerebral palsy (CP), a condition that affects the development of motor skills in children, is the most common childhood-onset physical disability. CP can have different causes, such as infections, injuries, or lack of oxygen before or during birth, but the genetic contributors to CP have remained largely unknown till recently.

Novel research by scientists  provides a more detailed look into the genetic causes of the condition. Their findings suggest the existence of many genetic variants contributing to CP, which may inform future diagnosis and treatment.

Now that we have a better understanding into the complex relationship between cerebral palsy's genetic and environmental factors, we hope we can improve care for these children.

One in ten children with CP have a genetic variant associated with their condition Published in Nature Genetics, the scientists conducted whole-genome sequencing in 327 children with CP, including their biological parents, and compared it to three independent clinical cohorts as well as two pediatric control cohorts, to identify whether genetic variants may be involved in CP.

The seven-year study found that more than one in ten children (11.3 percent) had a genetic variant or likely genetic variant for their CP, and 17.7 percent of children had variants of uncertain significance that may be linked with CP after further research. Many of the variants also overlapped with other neurodevelopmental conditions, including autism spectrum disorder (ASD), which is highly prevalent in children with CP.

The findings suggest that CP and its causes may be much more diverse than previously thought and showcases the strength of combining precision medicine programs, a movement to deliver individualized care to each patient.

Comprehensive whole-genome sequence analyses provide insights into the genomic architecture of cerebral palsy, Nature Genetics (2024). DOI: 10.1038/s41588-024-01686-x. www.nature.com/articles/s41588-024-01686-x

Women with obesity do not need to gain weight during pregnancy, new study suggests

The guidelines for weight gain during pregnancy in obese women have long been questioned. New research  supports the idea of lowering or removing the current recommendation of a weight gain of at least 5 kg. The results are published in The Lancet.

International guidelines from the U.S. Institute of Medicine (IOM) state that women with obesity should gain a total of 5 to 9 kg during pregnancy, compared to 11.5 to 16 kg for normal-weight women. The guidelines have long been questioned, but there has been no evidence to warrant a re-examination.

A new study from Karolinska Institutet in Sweden now shows that there are no increased health risks for either the mother or the child with weight gain below current guidelines for women with obesity class 1 and 2 (BMI of 30–34.9 and 35–39.9 respectively). On the contrary, for women with obesity class 3 (BMI over 40), weight gain below current guidelines might even be beneficial for those with class 3 obesity.

The study supports previous calls to either lower or remove the current recommended lower limit of a weight gain of at least 5 kg.

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The study is based on electronic medical records and registry data for 15,760 women with obesity in Stockholm and Gotland (the so-called Stockholm Gotland Perinatal Cohort). Of the women in the study, 11,667 had obesity class 1; 3,160 had obesity class 2; and 933 had obesity class 3. The study included singleton pregnancies that delivered between 2008 and 2015. The women were followed for a median of eight years after delivery.

Ten known adverse outcomes associated with weight gain during pregnancy were studied: pre-eclampsia, gestational diabetes, excess postpartum weight retention, maternal cardiometabolic disease, unplanned cesarean delivery, preterm birth, large for gestational age and small for gestational age at birth, stillbirth and infant death. These adverse outcomes were assigned weights according to their severity and combined into an adverse composite outcome.

Overall, the study shows no increased risks of the adverse composite outcome with weight gain below current IOM guidelines in women with obesity classes 1 and 2. For women with obesity class 3, on the contrary, weight gain values below the guidelines or weight loss were associated with reduced risk of the adverse composite outcome. For example, an absence of weight gain (i.e., 0kg) was associated with a risk reduction of about 20%.

Based on this, researchers have concluded that weight gain below current recommendations is likely safe in pregnancies with obesity, and might even be beneficial for those with class 3 obesity.
The results also indicate that there is a need for specific recommendations for women with class 3 obesity. Unlike today, this group could receive separate recommendations.

Kari Johansson et al, Safety of low weight gain or weight loss in pregnancies with class 1, 2, and 3 obesity: a population-based cohort study, The Lancet (2024). DOI: 10.1016/S0140-6736(24)00255-1

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What causes a landslide? | Natural Disasters

Study shows common water pollutants cause heart damage in fish

Recent findings highlight the persistence of dihalogenated nitrophenols (2,6-DHNPs) in drinking water, resisting standard treatments like sedimentation, filtration, and boiling. The research demonstrates the severe cardiotoxic effects of these contaminants on zebrafish embryos at concentrations as low as 19 μg/L, indicating potential health risks for humans.

2,6-DHNPs, a group of disinfection byproducts (DBPs), are raising alarm bells for public health. These bad actors in the water world are tougher and more toxic than many other pollutants, making it hard for typical water cleaning methods to get rid of them.

They pack a powerful punch, being significantly more harmful to marine life and cells than similar pollutants. Found in places like sewage, swimming pools, and our drinking taps, 2,6-DHNPs are everywhere, signaling a pressing need for better ways to clean our water and keep us safe.

A new study, published in Eco-Environment & Health has uncovered the severe cardiotoxic impacts 2,6-DHNPs have on zebrafish embryos, serving as a model for potential human health risks.

2,6-DHNPs, a group of DBPs resistant to traditional water purification methods like boiling and filtration. These DBPs pose a significant risk, showing a toxicity level 248 times higher than the known regulated DBPs, dichloroacetic acid, in zebrafish embryos. Using zebrafish as a biological model due to their genetic similarity to humans the study meticulously detailed how these emerging contaminants wreak havoc on cardiac health.

The zebrafish embryos exposed to 2,6-DHNPs suffered from severe heart damage characterized by increased production of harmful reactive oxygen species, cell death (apoptosis), and disrupted heart development.

This research underscores a critical environmental and public health issue: the contaminants that survive water treatment processes can lead to severe health outcomes in exposed organisms, hinting at the possible public health risks faced by these persistent waterborne chemicals.

The study revealed that 2,6-DCNP and 2,6-DBNP, two types of DBPs, exhibited significant resistance to removal in drinking water treatment plants. Boiling and filtration were found to be the most effective household water treatment methods, reducing 2,6-DCNP and 2,6-DBNP levels by 47% and 52%, respectively. Exposure to 2,6-DHNPs caused heart failure in zebrafish embryos through increased production of harmful reactive oxygen species (ROS) and delayed heart development. Notably, the antioxidant N-acetyl-L-cysteine was able to mitigate the cardiotoxic effects induced by 2,6-DHNPs.

Hongjie Sun et al, Dihalogenated nitrophenols in drinking water: Prevalence, resistance to household treatment, and cardiotoxic impact on zebrafish embryo, Eco-Environment & Health (2024). DOI: 10.1016/j.eehl.2024.02.004

Keeping cells together—how our body resists mechanical stress

Our body consists of ~30 trillion cells. These cells need to tightly attach to each other to maintain the integrity of our body. However, we are constantly exposed to mechanical stress, which continuously challenges the integrity of our bodies. How are cells able to resist mechanical force to maintain the integrity of our body? Why doesn't our body fall apart when we fall down on the street or when the guts move to digest the food? The secret lies in the cell-to-cell adhesion apparatus that keeps our cells together.

Cells hold on to each other through junctions that serve to connect the neighboring cells. At least three types of junctions are known: tight junctions, adherens junctions, and desmosomes. Previous studies have shown that adherens junctions and desmosomes play critical roles in maintaining the integrity of our body. However, the roles of tight junctions in resisting mechanical stress have not been demonstrated till recently.
One reason that hindered the attempts to understand the roles of tight junctions was that it had been difficult to specifically and completely eliminate its activity due to the overlapping functions of its key constituents. A few years ago, a research group succeeded in generating an epithelial cell line that specifically and completely lacks tight junction membrane proteins claudins and JAM-A, and demonstrated that these cells completely lack tight junctions.

In carefully examining these cells, the researchers found something bizarre. While normal cells are always connected to each other by a continuous belt of cell-to-cell junctions, sporadic disruption and fragmentation of cell-to-cell junctions were observed in these cells. Scientists had never seen something like this before and became curious about this issue.
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The researchers decided to take a movie to find out how the junctions become broken in these cells and found that the junctions fractured when the cells were stretched. The research group further showed that tight junction membrane proteins regulate the conformation change of a protein called ZO-1 in response to mechanical force, suggesting that this mechanosensor is important for cells to resist mechanical stress.
This study shows that tight junctions in addition to adherens junctions and desmosomes are important for cells to resist mechanical stress. An interesting question is why we need so many junctions to resist force and how these junctions collaborate to provide mechanical resistance. Scientists would like to tackle these issues in the future.

Thanh Phuong Nguyen et al, Tight junction membrane proteins regulate the mechanical resistance of the apical junctional complex, Journal of Cell Biology (2024). DOI: 10.1083/jcb.202307104

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Do sweeteners increase your appetite? New evidence from randomized controlled trial says no

Replacing sugar with artificial and natural sweeteners in foods does not make people hungrier—and also helps to reduce blood sugar levels, a new study has found.

The double-blind randomized controlled trial found that consuming food containing sweeteners produced a similar reduction in appetite sensations and appetite-related hormone responses as sugary foods—and provides some benefits such as lowering blood sugar, which may be particularly important in people at risk of developing type 2 diabetes.

The use of sweeteners in place of sugar in foods can be controversial due to conflicting reports about their potential to increase appetite. Previous studies have been carried out but did not provide robust evidence.

However, the researchers say their study, which meets the gold standard level of proof in scientific investigation, provides very strong evidence that sweeteners and sweetness enhancers do not negatively impact appetite and are beneficial for reducing sugar intake.

The trial consisted of three two-week consumption periods, where participants consumed biscuits with either fruit filling containing sugar, natural sugar substitute Stevia, or artificial sweetener Neotame, each separated by a break of 14-21 days. Day 1 and day 14 of the consumption periods took place in the lab.

The results from the sweetener types showed no differences in appetite or endocrine responses compared to sugar, but insulin levels measured over two hours after eating were reduced, as were blood sugar levels.

: Acute and two-week effects of Neotame, Stevia Rebaudioside M and sucrosesweetened biscuits on postprandial appetite and endocrine response in adults with overweight/obesity – a randomised crossover trial from the SWEET Consortium, eBioMedicine (2024).

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How might fiber lower diabetes risk?

Eating more dietary fiber may help prevent type 2 diabetes by promoting beneficial gut bacteria and substances produced during metabolism, according to new research in Hispanic adults.

Consistent evidence suggests diabetes-protective effects of dietary fiber intake, but exactly how does that protection occur?

Consistent evidence suggests diabetes-protective effects of dietary fiber intake, but exactly how that protection occurs remained unclear until recently.

Discovering the connections between dietary fiber, gut bacteria, metabolites and type 2 diabetes—a leading risk factor for heart disease, stroke and kidney disease—could lead to more effective prevention of the condition.

For example, identifying which bacteria and metabolites in the body are linked to type 2 diabetes risk paves the way for personalized diets and treatments to improve gut and metabolic health for people at risk.

The study, published in Circulation Research, looked at data from up to 11,000-plus participants in the ongoing Hispanic Community Health Study/Study of Latinos.

The researchers found that higher fiber intake was associated with specific "good" gut bacteria and certain favorable metabolites in the blood—some of which were actually produced by gut bacteria. Those gut microbes and metabolites were associated with lower risk of developing type 2 diabetes during an average follow-up of six years.

This is new evidence of why a higher intake in dietary fiber is beneficial, specifically to reduce the incidence of new-onset type 2 diabetes.

Dietary fiber is mostly found in fruits, vegetables, nuts, whole grains and cereals. It cannot be broken down, and much of it passes through the system undigested. Its most well-known job is to promote regular bowel movements. But the new research suggests fiber might also be feeding bacteria in the gut.

Bacteria can affect disease risk through a vast array of mechanisms. The complexity was both surprising and fascinating, revealing the deep and nuanced interactions within our gut microbiome.

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Although the study's observational design means it could not prove cause and effect, the findings possess strong biological plausibility since some of the specific metabolites highlighted in this study can only be produced by bacteria and not by the human body.

The study also relied on self-reported dietary fiber intake from participants. Dietary fiber is important to metabolic health, and we're beginning to understand why.

Zheng Wang et al, Gut Microbiota and Blood Metabolites Related to Fiber Intake and Type 2 Diabetes, Circulation Research (2024). DOI: 10.1161/CIRCRESAHA.123.323634

Part 2