Dark matter could make our galaxy's innermost stars immortal

Stars near the center of our galaxy are acting kind of weird. Dark matter may be the explanation.

A team of scientists have discovered a potential new class of stars that could exist within a light-year of the Milky Way's center that could be operating according to an unusual mechanism: dark matter annihilation. This process would produce an outward pressure on the stars other than hydrogen fusion, keeping them from gravitationally collapsing—and making them essentially immortal, their youth being refreshed constantly. The findings are published  on the arXiv preprint server.

Collectively, the dark matter–powered stars would inhabit a new region of a long-established diagram that classifies stars by their temperature and luminosity, placing them away from the so-called main sequence where the vast majority of stars exist.

Observing our Galactic Center, around which the galaxy's stars rotate, is quite difficult, as the region is extremely bright. A supermassive black hole, Sagittarius A*, sits at the center, with a mass four million times that of the sun. It is a bright source of radio waves, and was imaged in 2022. Stars near Sgr A* orbit it at speeds of several thousands of kilometers per second (compared to the sun's orbital speed of 240 km/s).
These close inner stars, called S-cluster stars, are very puzzling, with properties unlike any others in the Milky Way. Their provenance is unknown, since the environment within about three light-years of the center is considered hostile to star formation. They appear to be much younger than would be expected if they had moved inward from someplace else. Most mysterious of all, they look unusually young, with fewer older stars in the neighborhood than expected, and also unexpectedly, there seem to be many heavy stars.
Part 1

Stars are nuclear ovens, generating heat burning hydrogen via nuclear fusion. The thermal radiation from this reaction, as well as thermodynamic convection of the stellar plasma, exerts an outward force on a star's constituents—mostly hydrogen and helium. That force is balanced by the inward force of self-gravity.

The Hertzsprung–Russell (HR) diagram classifies stars by plotting their luminosity against the effective temperature of their surface. Excluding white dwarfs and red giants, the "main sequence" of this diagram curves from its upper left to lower right, and most stars fall on this curve. (The sun falls near the middle, as their luminosities are plotted as their ratio with the sun's). Stars in different locations on the sequence correspond to stars of different masses and ages.

However, dark matter also exists in the galaxy. Its presence has been inferred by observations that find insufficient ordinary matter to account for the higher-than-expected rotational speeds of stars around the Galactic Center.

Dark matter's density is highest near the center and falls off with the distance from it. It's reasonable to expect it would be incorporated within stars near the center, where dark matter is densest. If so, dark matter annihilation—dark matter particles and antiparticles that collide and produce photons, electrons, etc.—would exert an additional outward pressure within a star and could even dominate over nuclear fusion.
A research team has found that incorporating dark matter power into the dynamics of the innermost stars—those within about a third of a light-year of the center (equivalent to about 8% of the distance to the sun's nearest star)—solves many of the known paradoxes.
To incorporate dark matter annihilation, the group used relatively standard star formation parameters over the evolutionary course of the Milky Way, and dark matter particles just slightly more massive than the proton. Using a stellar evolution computer model, they assumed that stars migrate on the main sequence towards the Galactic Center, then they began to inject dark matter energy into a star's composition. The star then evolved until it reached the red giant branch on the HR diagram, or until it reached an age of 10 billion years, the lifetime of the Milky Way.
Part 2

They calculated stellar populations without and with the presence of dark matter. With dark matter, more massive stars experienced a lower dark matter density, and hydrogen in their core fused more slowly and their evolution was slowed down. But stars in a higher dark matter density region were changed significantly—they maintained equilibrium through dark matter burning with less fusion or no fusion, which led to a new stellar population in an HR region above the main sequence.
The scientists' simulations show that stars can survive on dark matter as a fuel alone and because there is an extremely large amount of dark matter near the Galactic Center, these stars become immortal staying forever young, occupying a new, distinct, observable region of the HR diagram.
Their dark matter model may be able to explain more of the known mysteries. For lighter stars, scientists saw in their simulations that they become very puffy and might even lose parts of their outer layers something similar to this might be observed at the Galactic Center: the so-called G-objects, which might be star-like, but with a gas cloud around them.
There are a limited number of individual stars known to exist so close to the Galactic Center, as the region is extremely bright. Upcoming 30-meter telescopes will be able to see much better into the region, which will allow scientists to better understand the population of its stars and verify or rule out the dark main sequence.

Isabelle John et al, Dark Branches of Immortal Stars at the Galactic Center, arXiv (2024). DOI: 10.48550/arxiv.2405.12267

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Most powerful anti-fungal chemistries cause fungal pathogens to self-destruct

Scientists have discovered that the most widely-used class of antifungals in the world causes pathogens to self-destruct. The  research could help improve ways to protect food security and human lives.

Fungal diseases account for the loss of up to a quarter of the world's crops. They also pose a risk to humans and can be fatal for those with weakened immune systems.

Our strongest weapons against fungal plant diseases are azole fungicides. These chemical products account for up to a quarter of the world agricultural fungicide market, worth more than $3.8 billion per year. Antifungal azoles are also widely used as a treatment against pathogenic fungi which can be fatal to humans, which adds to their importance in our attempt to control fungal disease.

Azoles target enzymes in the pathogen cell that produce cholesterol-like molecules, named ergosterol. Ergosterol is an important component of cellular bio-membranes. Azoles deplete ergosterol, which results in killing of the pathogen cell. However, despite the importance of azoles, scientists know little about the actual cause of pathogen death.

In a new study published in Nature Communications,  scientists have uncovered the cellular mechanism by which azoles kill pathogenic fungi. The paper is titled "Azoles activate type I and type II programmed cell death pathways in crop pathogenic fungi." 

Part 1

The team of researchers combined live-cell imaging approaches and molecular genetics to understand why the inhibition of ergosterol synthesis results in cell death in the crop pathogenic fungus Zymoseptoria tritic (Z. tritici). This fungus causes septoria leaf blotch in wheat, a serious disease in temperate climates.
The team observed living Z. tritici cells, treated them with agricultural azoles and analyzed the cellular response. They showed that the previously-accepted idea that azoles kill the pathogen cell by causing perforation of the outer cell membrane does not apply. Instead, they found that azole-induced reduction of ergosterol increases the activity of cellular mitochondria, the "powerhouse" of the cell, required to produce the cellular fuel that drives all metabolic processes in the pathogen cell.
While producing more "fuel" is not harmful in itself, the process leads to the formation of more toxic by-products. These by-products initiate a "suicide" program in the pathogen cell, named apoptosis. In addition, reduced ergosterol levels also trigger a second "self-destruct" pathway, which causes the cell to eat its own nuclei and other vital organelles—a process known as macroautophagy. The authors show that both cell death pathways underpin the lethal activity of azoles. They conclude that azoles drive the fungal pathogen into "suicide" by initiating self-destruction.

The authors found the same mechanism azoles killing pathogen cells in the rice-blast fungus Magnaporthe oryzae

Azoles activate type I and type II programmed cell death pathways in crop pathogenic fungi, Nature Communications (2024). www.nature.com/articles/s41467-024-48157-9

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A new way of healing wounds in diabetics fast

Wounds that are superficial for some can be life-threatening for others. With diabetic wounds, healing can be slow, particularly in the feet, increasing the tissue's susceptibility to infection. Foot ulcers and other diabetic foot complications have similar mortality rates to some cancers, yet progress toward improved treatments has plateaued. Now, researchers may have found a better way to kickstart the healing process.

B ioengineers have developed a multistep strategy that applies different nanomaterials to wounds at different times to support both early- and late-stage healing. In a study published in the journal Biomaterials, the authors' method outperformed a common wound dressing in a diabetic mouse model, closing wounds faster and producing more robust skin tissue.

Clinically, the standard practice for wounds is to keep them clean and use a dressing to protect them while they heal. This approach gets the job done for most injuries but falls short for patients with conditions that interfere with the healing process, such as diabetes. In addition to causing poor circulation and neuropathy, diabetes can disrupt wound healing by impairing the function of various immune cells.

The researchers' analysis also suggests that their approach unexpectedly activated an immune cell population not normally seen in wounds that can resolve inflammation, which highlights a new potential avenue to accelerate healing.

The researchers devised a strategy to treat wounds like these and compared it to a commonly used dressing in a diabetic mouse model.

For the first step, the team fabricated a silk nanomaterial dressing embedded with gold nanorods. Because gold nanoparticles readily convert light to heat, the team was able to direct a laser at dressings placed over fresh wounds in mice, producing heat that quickly sealed them in place and provided a high level of protection.

The strategy, which the authors previously found success with, creates something akin to an instantaneous scab.

This time around, the authors added histamine to the mix, a natural biochemical produced by the immune system that plays important roles in inflammation, blood vessel development, and allergic reactions.

Inflammation dominates the body's initial response to injuries, but eventually subsides to allow the body to rebuild. However, diabetic wounds can get stuck in first gear, maintaining persistent, low-grade inflammation, which can inhibit the healing process.

Since the wound is stalled, the researchers wanted to co-deliver histamine with the dressing, to give a push and bring the inflammation stage to a resolution.

Part 1

The authors monitored the wounded mice for 11 days and found that animals treated with a combination of the nanomaterial dressing and histamine healed at the fastest rate compared to those treated with the standard dressing with histamine or the nanomaterial dressing alone.

The researchers mechanically tested the healed skin as well, finding that the tissue treated with both the nanomaterial and histamine was strongest and most similar to unwounded skin.
For a better understanding, the team analyzed tissue samples by assessing gene expression and examining cells under the microscope.

They found that a specific immune cell type, N2 neutrophils, were highly prevalent in treated wounds up to seven days post-injury. As the first responders of the immune system, these cells usually clear out within a day or two, making their presence in the wound after a week highly unusual. But since they are known to produce histamine and other reparative molecules, it is also possible that these immune cells are the linchpin of the treatment.
The team injected the nanoparticles at various time points into the nanomaterial-dressed wound bed, finding that delivery on day six had the best outcomes with regards to wound closure and tissue strength. This time point corresponds to a transitionary phase in which cells begin proliferating and remodeling tissue.
With promising results in mice behind them, the authors are now testing their strategy in larger animal models more relevant to human health, such as pigs.

Deepanjan Ghosh et al, Bioactive nanomaterials kickstart early repair processes and potentiate temporally modulated healing of healthy and diabetic wounds, Biomaterials (2024). DOI: 10.1016/j.biomaterials.2024.122496

Part 2

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An outlandish molecule may be lurking inside Uranus and Neptune, affecting their magnetic fields

Scientists  have determined the conditions that enable the existence of a very peculiar ion. Dubbed aquodiium, it can be conceptualized as an ordinary neutral molecule of water with two additional protons stuck to it, resulting in a net double positive charge.

They  suggest that the ion could be stable in the interior of the ice giants Uranus and Neptune, and if so, it must play a part in the mechanism that gives rise to these planets' unusual magnetic fields. The study is published in Physical Review B

The magnetic fields of Uranus and Neptune are not understood quite as well as those of Jupiter and Saturn—or our own planet, for that matter.

In the Earth's interior, circulation of the electronically conductive liquid iron-nickel alloy produces magnetism. Deep inside Jupiter and Saturn, hydrogen is thought to be pressed into a metallic state and give rise to magnetic fields in much the same way.

By contrast, the magnetic fields of Uranus and Neptune are hypothesized to stem from the circulation of ionically conductive media, where the constituent ions are themselves charge carriers, rather than merely a support structure enabling the flow of electrons.

If planetary scientists knew exactly what ions and in which proportions are involved, perhaps they could figure out why the ice giants' magnetospheres are so quirky: misaligned with the direction of the planets' rotation and offset from their physical centers.

They explain how ionic and electronic conductivity are different and where the newly predicted ion fits into this: The hydrogen surrounding Jupiter's rocky core at those conditions is a liquid metal: It can flow, the way molten iron in the Earth's interior flows, and its electrical conductivity is due to the free electrons shared by all the hydrogen atoms pressed together.

In Uranus, they think that hydrogen ions themselves—i.e., protons—are the free charge carriers. Not necessarily as standalone H⁺ ions, but perhaps in the form of hydronium H₃O⁺, ammonium NH₄⁺, and a series of other ions. This new study adds one more possibility, the H₄O²⁺ ion, which is extremely interesting from the chemical viewpoint."

Part 1

In chemistry, there's the notion of sp3 hybridization, which refers to the way electron orbitals combine with each other and amounts to something like a natural template for making plausible molecules and ions. Under sp3 hybridization, the nucleus of an atom—e.g., carbon, nitrogen, or oxygen—occupies the center point of an imaginary tetrahedron.

Each of the four vertices hosts either a valence electron or two paired electrons that are not available for making bonds with other atoms. The simplest example would be a carbon atom with four unpaired electrons at the four vertices—add four hydrogen atoms and you get a methane molecule: CH4.

For an oxygen atom, which has two electron pairs of its own in the outermost shell, along with two valence electrons, sp3 hybridization would mean only two of the vertices could host a covalent bond with hydrogen, with the remaining two occupied by electron pairs, which yields H2O, water.

If you attach a hydrogen ion (a proton) to one of the electron pairs, you get a hydronium ion H3O+, and this is actually what you get in an acid solution, because acids donate protons H+ into the solution and lone protons are immediately drawn to electron pairs.
Part 2

But the question was: Can you add yet another proton to the hydronium ion to fill in the missing piece? Such a configuration at normal conditions is energetically very unfavorable, but scientists' calculations show there are two things that can make it happen.
First, very high pressure compels matter to reduce its volume, and sharing a previously unused electron pair of oxygen with a hydrogen ion (proton) is a neat way of doing that: like a covalent bond with hydrogen, except both electrons in the pair come from oxygen. Second, you need lots of available protons, and that means an acidic environment, because that's what acids do—they donate protons.
The team used advanced computational tools to predict what happens to hydrofluoric acid and water under extreme conditions. The result: Given a pressure of about 1.5 million atmospheres and a temperature around 3,000 degrees Celsius, well-separated aquodiium H4O2+ ions turn up in the simulation.

The scientists think that their newly discovered ion should play an important role in the behavior and properties of water-based media, specifically those under pressure and containing acid.

This roughly corresponds to conditions on Uranus and Neptune, where an immensely deep liquid water ocean produces extremely high pressures and some amount of acid might be expected, too. If so, aquodiium ions will form and by participating in the ocean's circulation, will contribute to these planets' magnetic fields and other properties in ways distinct from other ions.
Perhaps, aquodiium might even form as yet unknown minerals under those extreme conditions.

ingyu Hou et al, H₄O²⁺ ion stabilized by pressure, Physical Review B (2024). DOI: 10.1103/PhysRevB.109.174102

Part 3

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From a purely technical point of view, sound in the air cannot be more intense than 194 dB. At this intensity, the individual sound waves interfere with each other and create a vacuum. Of course, it is possible to go beyond this limit, but we should talk more about a shock wave instead of a sound wave then.

Earthquakes are hardly ever associated with a loud noise, but the opposite is true. The most intense is submarine earthquakes. Even those registered 5.0 on the Richter scale reach a noise intensity of 235 dB in water.

Study Suggests Young Children Trust Robots Over Humans!

Many of us will be familiar with tales of kids befriending robots, which suggest generations of young children are more trusting of advice from machines than their own flesh and blood. An international research team has now found it's not just in fiction. In a study involving 111 kids aged between 3 and 6 years old, the youngsters showed a preference for believing robots more and being more accepting when robots made mistakes.
Where both humans and robots were shown to be equally reliable in the experiments, the youngsters were more likely to want to ask robots the names of new objects and accept their labels as accurate. What's more, the children were more likely to favor robots when asked about who they would share secrets with, who they would want to be friends with, and who they would want to have as teachers.
Children's conceptualizations of the agents making a mistake also differed, such that an unreliable human was selected as doing things on purpose, but not an unreliable robot.
These findings suggest that children's perceptions of a robot's reliability are separate from their evaluation of its desirability as a social interaction partner and its perceived agency."

There were individual differences in the responses: older kids were more trusting of humans than younger kids, but only when the robot was shown to be unreliable compared to the human. Taken as a whole though, the results showed these children thought reliable robots were more trustworthy than reliable humans.

One area where this research might be useful is in education, especially in a world where kids are increasingly surrounded by technology.

The researchers didn't ask anything about why these children felt that the robots they met could be trusted more than people.

https://www.sciencedirect.com/science/article/pii/S0747563224000979

Study sheds new light on the contribution of dopamine to reinforcement learning

The neurotransmitter dopamine has often been linked to pleasure-seeking behaviors and making stimuli paired with rewards  valuable. Nonetheless, the processes through which this key chemical messenger contributes to learning have not yet been fully elucidated.

Researchers carried out a study now aimed at better understanding how dopaminergic neurons (i.e., brain cells supporting the production of dopamine) support reward-based learning. Their findings, published in Nature Neuroscience, suggest that rather than representing the value attributed to different stimuli, these neurons contribute to the formation of new mental associations between stimuli and reward (or other neutral stimuli), which help us form cognitive maps of our environment.

This recent research has shown that firing of dopamine neurons act as the brain's teaching signal. This occurs whenever something new or salient happens, which helps us learn to associate events together to make a new memory. Critically, this work has shown that dopamine neurons do this without making things 'valuable' or 'good' in and of themselves.

This work is at odds with past studies that have defined dopamine as the neurotransmitter producing "happiness" or "pleasure." However, if dopaminergic neurons do not carry value signals, they should be unable to attribute positive or pleasurable qualities to specific experiences or actions.

The results of their experiment suggest that when dopamine neurons fire in everyday life, they're not making things valuable. Instead, they function to help us form new memories or how things in our environment are related. In a case where dopamine neurons fire more than they are supposed to (e.g., when taking drugs of abuse), this may be encoded in the brain as a rewarding event that makes us more likely to seek out drugs in future.

Overall, this recent study by researchers could greatly contribute to the understanding of dopamine and its role in reward-based (i.e., reinforcement) learning. In particular, their findings suggest that dopamine neurons do not carry value signals that attach pleasure or happiness to stimuli in the environment.

The researchers are now interested in finding how different dopamine circuits contribute to different types of learning and how this helps us to create a complex but unified representation of our environment.

Samuel J. Millard et al, Cognitive representations of intracranial self-stimulation of midbrain dopamine neurons depend on stimulation frequency, Nature Neuroscience (2024). DOI: 10.1038/s41593-024-01643-1

Greener, more effective termite control: Natural compound attracts wood eaters

Scientists have discovered a highly effective, nontoxic, and less expensive way to lure hungry termites to their doom.

The method, detailed in the Journal of Economic Entomology, uses a pleasant-smelling chemical released by forest trees called pinene that reminds western drywood termites of their food. They follow the scent to a spot of insecticide injected into wood.

Researchers saw significant differences in the death rates using insecticide alone versus the insecticide plus pinene. Without pinene, they got about 70% mortality. When they added it in, it was over 95%.

Fumigation is one of the most common drywood termite control techniques. Homes are covered with tents and then bombed with gas that kills the insects.

The pest control industry is under pressure to find new methods because the chemical, sulfuryl fluoride, is both a greenhouse gas and is also toxic to humans. Additionally, fumigation is an expensive process that does not provide lasting protection against termites.

Even though it is very thorough, a home can be infested again soon after fumigation is completed. Some people fumigate every three to five years because it doesn't protect structures from future infestations.

Localized injection is an alternative strategy to control drywood termites that does not involve gas. Technicians drill holes into the infested wood to reach the termite "gallery" or lair, then inject poison into the hole to inundate the bugs.

This is a more localized treatment, and in theory, it is a better strategy when you want to control drywood termites with fewer chemicals. It's less expensive, and the treated wood may also stay protected from future infestations.

The challenge with localized injection is figuring out exactly where the bugs are hiding. Typically, this method uses a contact-based insecticide, meaning the insects must touch the poison for it to work.

Using an attractant like pinene eliminates the need to hunt for the termites. Even at low concentrations, pinene is good at attracting termites from a distance.

 Nicholas A Poulos et al, Potential use of pinenes to improve localized insecticide injections targeting the western drywood termite (Blattodea: Kalotermitidae), Journal of Economic Entomology (2024). DOI: 10.1093/jee/toae101

Doctors develop minimally invasive procedure to avoid drilling a 'burr hole' in the skull to treat clot on the brain

In 2018, a New York surgeon-scientist and his team demonstrated in a proof-of-concept study that a minimally invasive procedure could effectively treat one of the world's most common conditions requiring neurosurgical intervention.

The condition is called chronic subdural hematoma, an accumulation of blood and blood breakdown products on the brain's surface just beneath the dura, the brain's protective covering. The mass is caused by damaged vessels that chronically leak blood between the brain and the dura. Risk factors for the abnormality, which can reach significant size, include older age; untreated head trauma; long-term use of blood thinning agents, such as warfarin, or extensive time on anti-inflammatory drugs, like ibuprofen.

Now doctors at Stony Brook Medicine report that not only is the new method of alleviating chronic subdural hematoma effective, it's destined to replace the invasive old-school surgery to remove the accumulation of blood.

The new method of treatment is called middle meningeal artery embolization—MMAE—which relies on an injectable fluid to plug the leakage. Studies conducted around the world show that it's safe, effective and eliminates the risks of surgery. Research at Stony Brook led to a global study of the procedure, and doctors have now demonstrated that the new method not only stops the leakage, it forces the hematoma into permanent retreat.

The standard of care for decades has been surgery, which was designed to provide drainage by drilling a burr hole into the skull or performing a craniotomy, the surgical removal of a portion of the skull to release accumulated blood. While these procedures can alleviate the mass, a chronic subdural hematoma can recur despite the highly invasive attempt to eliminate it. The recurrence rate runs as high as 20%, studies have shown.

Worse, surgery is often poorly tolerated by a broad population of patients.

Chronic subdural hematoma as an insidious condition, developing slowly, often over weeks to months. The mass can put pressure on the brain causing a range of symptoms: slurred speech, forgetfulness, impaired motor function, even coma.

The new approach uses a specialized fluid that is injected into the middle meningeal arteries through a micro-catheter. The liquid embolic agent blocks—embolizes—the abnormal blood vessels that are responsible for the chronic leakage of blood onto the brain's surface. The liquid embolic agent solidifies once it enters the vasculature. Doctors view each step of the procedure via imaging technology.

The enormous potential of a minimally invasive procedure that is safe and effective has captured the attention of neurosurgeons around the world.

David Fiorella et al, Middle meningeal artery embolization for the management of chronic subdural hematoma: what a difference a few years make, Journal of NeuroInterventional Surgery (2023). DOI: 10.1136/jnis-2023-020498

Arindam Rano Chatterjee, Invited Commentary: A New Era in the Treatment of Chronic Subdural Hematomas, RadioGraphics (2024). DOI: 10.1148/rg.240038

Researchers identify first step in allergic reactions, paving the way for preventative strategies

Scientists  have identified how the first domino falls after a person encounters an allergen, such as peanuts, shellfish, pollen or dust mites. Their discovery, published in the journal Nature Immunology, could herald the development of drugs to prevent these severe reactions.

It is well established that when mast cells, a type of immune cell, mistake a harmless substance, such as peanuts or dust mites, as a threat, they release an immediate first wave of bioactive chemicals against the perceived threat. When mast cells, which reside under the skin, around blood vessels and in the linings of the airways and the gastrointestinal tract, simultaneously release their pre-stored load of bioactive chemicals into the blood, instant and systemic shock can result, which can be lethal without quick intervention.

More than 10% of the global population suffers from food allergies, according to the World Health Organization (WHO). As allergy rates continue to climb, so does the incidence of food-triggered anaphylaxis and asthma worldwide.

What the researchers have now discovered is that the release of particulate mast cell granules, which contain these bioactive chemicals, is controlled by two members of an intracellular multiprotein complex called inflammasome. Until now, these inflammasome proteins were only known to spontaneously assemble within immune cells to secrete soluble chemicals to alert other parts of the immune system upon detection of an infection.

They discovered that the inflammasome components played a surprisingly crucial role in transporting particulate mast cell granules which are typically packed in the cell center to the cell surface where they are released. This surprising discovery gives us a precise target where we can intervene to prevent the cascade of events initiated in mast cells that leads to anaphylactic shock.

Andrea Mencarelli et al, Anaphylactic degranulation by mast cells requires the mobilization of inflammasome components, Nature Immunology (2024). DOI: 10.1038/s41590-024-01788-y

Some countries could meet their total electricity needs from floating solar panels, research shows

Floating solar photovoltaic panels could supply all the electricity needs of some countries, new research has shown.

The study 's aimed to calculate the global potential for deploying low-carbon floating solar arrays. The researchers calculated the daily electrical output for floating photovoltaics (FPVs) on nearly 68,000 lakes and reservoirs around the world, using available climate data for each location.

The researchers' calculations included lakes and reservoirs where floating solar technology is most likely to be installed. They were no more than 10km from a population center, not in a protected area, didn't dry up and didn't freeze for more than six months each year. The researchers calculated output based on FPVs covering just 10% of their surface area, up to a maximum of 30 km².

While output fluctuated depending on altitude, latitude and season, the potential annual electricity generation from FPVs on these lakes was 1,302 terawatt hours (TWh), around four times the total annual electricity demand of the UK.

FPVs have a number of additional advantages over land-based solar installations: they free up land for other uses and they keep panels cooler, making them more efficient.

There is some evidence for other environmental benefits, including reducing water loss through evaporation, by sheltering the lake surface from the sun and wind; and reducing algal blooms by limiting light and preventing nutrient circulation.

However, the researchers point out that we still don't know exactly how floating panels might affect the ecosystem within a natural lake, in different conditions and locations. But the potential gain in energy generation from FPVs is clear, so we need to put that research in place so this technology can be safely adopted. 

 Decarbonisation potential of floating solar photovoltaics on lakes worldwide, Nature Water (2024). DOI: 10.1038/s44221-024-00251-4. www.nature.com/articles/s44221-024-00251-4

Study finds maternal obesity in mice increases microRNA levels in the hypothalamus in offspring, leading to overeating

Maternal obesity impacts the eating behaviours of offspring via long-term overexpression of the microRNA miR-505-5p, according to a study publishing June 4 in the open-access journal PLOS Biology.

 Previous studies in both humans and animal models have shown that the offspring of obese mothers have a higher risk of obesity and type 2 diabetes. While this relationship is likely the result of a complex relationship between genetics and environment, emerging evidence has implicated that maternal obesity can disrupt the hypothalamus—the region of the brain responsible for nutrition sensing and energy homeostasis.

In animal models, offspring exposed to overnutrition during key periods of development eat more, but little is known about the molecular mechanisms that lead to these changes in eating behaviour.

In this new study, researchers found that mice born from obese mothers had higher levels of the microRNA miR-505-5p in their hypothalamus—from as early as the fetal stage into adulthood. The researchers found that the mice ate more and showed a preference for high-fat foods. Interestingly, the effect of maternal obesity on miR-505-5p and eating behaviours was mitigated if the mothers exercised during pregnancy.

Cell culture experiments showed that miR-505-5p expression could be induced by exposing hypothalamic neurons to long-chain fatty acids and insulin, which are both high in pregnancies complicated by obesity. The researchers identified miR-505-5p as a novel regulator of pathways involved in fatty acid uptake and metabolism, therefore, high levels of the miRNA make the offspring brain unable to sense when eating high fat foods.

Several of the genes that miR-505-5p regulates have been associated with high body mass index in human genetic studies. The study is one of the first to demonstrate the molecular mechanism linking nutritional exposure in utero to eating behaviour.

This research work helps us understand why the children of mothers living with obesity are more likely to become obese themselves, with early life exposures, genetics and current environment all being contributing factors.

Dearden L, Furigo IC, Pantaleão LC, Wong LWP, Fernandez-Twinn DS, de Almeida-Faria J, et al. Maternal obesity increases hypothalamic miR-505-5p expression in mouse offspring leading to altered fatty acid sensing and increased intake of high-fat food. PLoS Biology (2024). DOI: 10.1371/journal.pbio.3002641

Commonly used alcohol-based mouthwash brand may disrupt the balance of your oral microbiome, scientists say

The oral microbiome is the community of bacteria that live in the mouth. It helps us digest our food and keep our mouth healthy. Changes to the composition of the oral microbiome have been linked to periodontal diseases and some cancers.

New research, published in Journal of Medical Microbiology is a follow-up to a larger study investigating the use of mouthwash as a method to reduce the transmission of sexually transmitted diseases in men who have sex with men. Researchers wanted to explore further and investigate whether the mouthwash used had an impact on the oral microbiome of the patients.

Researchers found that two species of opportunistic bacteria were significantly more abundant in the mouth after three months of daily use of the alcohol-based mouthwash, Fusobacterium nucleatum and Streptococcus anginosus. These two bacteria have been previously linked to gum disease, esophageal and colorectal cancers. Researchers also saw a decrease in a group of bacteria called Actinobacteria, which are crucial contributors to the regulation of blood pressure.

Alcohol-based mouthwashes are widely available. The public may use them daily to tackle bad breath or prevent periodontitis, but they should be aware of the potential implications.

The effect of daily usage of Listerine Cool Mint mouthwash on the oropharyngeal microbiome: a substudy of the PReGo trial, Journal of Medical Microbiology (2024). DOI: 10.1099/jmm.0.001830

New model suggests partner anti-universe could explain accelerated expansion without the need for dark energy

The accelerated expansion of the present universe, believed to be driven by a mysterious dark energy, is one of the greatest puzzles in our understanding of the cosmos. The standard model of cosmology called Lambda-CDM, explains this expansion as a cosmological constant in Einstein's field equations. However, the cosmological constant itself lacks a complete theoretical understanding, particularly regarding its very small positive value.

To explain the accelerated expansion, physicists have proposed alternative explanations such as quintessence and modified gravity theories, including scalar-tensor-vector gravity. Additionally, explanations beyond four dimensions, like the braneworld scenarios in the Dvali-Gabadadze-Porrati (DGP) model, modify gravity at large distances due to the effect of a higher-dimensional bulk on our four-dimensional brane, and variable brane tension.

Some researchers are now proposing another model to explain the present accelerated expansion of the universe. Unlike existing models, this does not require any form of dark energy or modified gravity approaches. However, there is a price to pay: we need a partner anti-universe whose time flow is oppositely related to our universe.

There are strong arguments supporting this concept. From a quantum theory perspective, it is natural for the universe to be created in pairs. Recently, Boyle et al proposed that the universe does not spontaneously violate CPT (Charge, Parity, and Time reversal symmetry), but rather, the universe after the Big Bang is the CPT image of the universe before it, pointing towards a partner anti-universe.

In a recent paper published in Gravitation and Cosmology, researchers used key concepts from quantum theory, such as relative entropy, and from general relativity, such as the null energy condition, which corresponds to the positive energy condition. The findings suggest that the universe naturally expands in an accelerated manner.

Part 1

Relative entropy, which requires two states, in this case, corresponds to the universe and its partner anti-universe. Accelerated expansion seems inevitable in a universe created in pairs that respect the null energy condition. This result is quite surprising and readers familiar with Hawking's area theorem may notice some similarities. The area theorem also deals with causal horizons and requires the null energy condition to hold.

In this new model, the causal horizon corresponds to the Big Bang. The results apply equally to the partner anti-universe.

 Naman Kumar, On the Accelerated Expansion of the Universe, Gravitation and Cosmology (2024). DOI: 10.1134/S0202289324010080

Part 2

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Nocturnal heat exposure and stroke risk

Hot Nights Linked With Increased Risk of Stroke, Scientists Warn

The risk of suffering a stroke is significantly higher with high overnight temperatures, posing a potential health concern around the globe as the world gets warmer.

Mapping night-time temperatures against the number of stroke cases recorded in the German city of Augsburg across the course of 15 years, a research team found a statistically significant increase in stroke risk on days where extremely warm night-time temperatures were recorded, with older people and women particularly vulnerable.

Overall, the risk of stroke increased by 7 percent during nights categorized as "tropical". For the purposes of this research, a tropical night was one where the temperature remained above 14.6 °C (58.3 °F). These nights represented the hottest 5 percent of nights across the course of the study period.

There was evidence of a higher number of stroke incidents over time, too: from 2006 to 2012, hot nights were linked to two additional strokes per year, whereas from 2013 to 2020, hot nights were associated with 33 additional cases per year. That reflects increasing temperatures as the years went by.

The researchers say a variety of factors could be behind the statistics, including a greater chance of dehydration – already known to increase the likelihood of suffering a stroke. Limited access to technology such as air conditioning could also play a part.

https://academic.oup.com/eurheartj/advance-article/doi/10.1093/eurh...

"In summary, changes in underlying drivers from climatic factors, stroke risk factors, and socioeconomic conditions may contribute to the increased susceptibility to night-time heat-related stroke over time," write the researchers in their published paper.

'Painting with light' illuminates photo evidence of air pollution

Rate of global warming caused by humans is at an all-time high, say scientists

The second annual Indicators of Global Climate Change report reveals that human-induced warming has risen to 1.19 °C over the past decade (2014-2023)—an increase from the 1.14 °C seen in 2013-2022 (set out in last year's report).

Looking at 2023 in isolation, warming caused by human activity reached 1.3 °C. This is lower than the total amount of warming we experienced in 2023 (1.43 °C), indicating that natural climate variability, in particular El Niño, also played a role in 2023's record temperatures.

The analysis also shows that the remaining carbon budget—how much carbon dioxide can be emitted before committing us to 1.5 °C of global warming—is only around 200 gigatons (billion tons), around five years' worth of current emissions.

In 2020, the Intergovernmental Panel on Climate Change (IPCC) calculated that the remaining carbon budget for 1.5 °C was in the 300–900 gigatonnes of carbon dioxide range, with a central estimate of 500. Since then, CO₂ emissions and global warming have continued. At the start of 2024, the remaining carbon budget for 1.5 °C stood at 100 to 450 gigatons, with a central estimate of 200.

This analysis by scientists shows that the level of global warming caused by human action has continued to increase over the past year, even though climate action has slowed the rise in greenhouse gas emissions. Global temperatures are still heading in the wrong direction and faster than ever before.

The latest Indicator report, which is published by more than 50 scientists in the journal Earth System Science Data, also provides new insight into the effects of reductions in sulfur emissions from the global shipping industry. The sulfur has a cooling effect on the climate by directly reflecting sunlight back to space and by helping more reflective clouds to form, but ongoing reductions in those emissions have lessened that effect.

Although this was offset last year by the aerosol emissions from the Canadian wildfires, the report says the longer-term trend nonetheless indicates that the amount of cooling we can expect from aerosol emissions is continuing to decline.

 Indicators of Global Change report, Earth System Science Data (2024).

Scientists sound the alarm on pharmaceutical pollution crisis

Our increasing dependency on pharmaceuticals comes at a major environmental cost, researchers have warned.

In an article published in the journal Nature Sustainability, researchers warn that discharges to the environment during drug production, use, and disposal have resulted in ecosystems around the globe being polluted with mixtures of pharmaceuticals, posing a growing danger to wildlife and human health.

While emphasizing that pharmaceuticals are indispensable in modern health care and will remain crucial in the future, the researchers highlight the need for designing and manufacturing more sustainable drugs to combat this issue at source.

A wide variety of drugs have now been detected in environments spanning all continents on Earth.

Exposure to even trace concentrations of some of these drugs can have severe impacts on the health of wildlife and human populations, and has already led to severe population crashes in vultures throughout India and Pakistan, as well as widespread sex-reversal of fish populations exposed to the human contraceptive pill.

Pharmaceutical pollution is a complex problem that demands a multifaceted solution. So far, environmental protection efforts have mainly been focused on upgrading wastewater treatment infrastructure to remove drugs before release into waterways more effectively.

Part 1

Despite being an important part of an overall solution, wastewater treatment is unable to address this issue in isolation.

In the article, 17 leading international scientists call for an increased focus on designing greener and more sustainable pharmaceuticals to tackle this issue at its source.

Tomas Brodin et al, The urgent need for designing greener drugs, Nature Sustainability (2024). DOI: 10.1038/s41893-024-01374-y

Part 2

Scientists develop electrified charcoal 'sponge' that can soak up CO₂ directly from the air

Researchers have developed a low-cost, energy-efficient method for making materials that can capture carbon dioxide directly from the air.

They used a method similar to charging a battery to instead charge activated charcoal, which is often used in household water filters.

By charging the charcoal 'sponge' with ions that form reversible bonds with CO₂, the researchers found the charged material could successfully capture CO₂ directly from the air.

The charged charcoal sponge is also potentially more energy efficient than current carbon capture approaches, since it requires much lower temperatures to remove the captured CO₂ so it can be stored. The results are reported in the journal Nature.

Alexander Forse et al, Capturing carbon dioxide from air with charged-sorbents, Nature (2024). DOI: 10.1038/s41586-024-07449-2. www.nature.com/articles/s41586-024-07449-2

Study shows orexin neurons can track how fast blood glucose changes
The concentration of glucose in the blood of humans continuously changes in response to what they eat and the activities they engage in. While many studies have investigated changes in blood glucose, the role of different neurons in tracking and predicting these changes remains poorly understood.
Researchers recently carried out a study investigating the potential role of a specific type of neuron, called orexin neurons, in tracking blood glucose levels. Their findings, published in Nature Neuroscience, suggest that orexin neurons in the mouse brain are responsible for tracking how fast blood glucose levels are changing.

In the 2000s, a lot of scientific effort went into identifying the so-called 'glucose-sensing neurons,' since these cells may alter our brain function based on what is happening minute-to-minute inside our body. With the huge 'diabesity [diabetes + obesity] epidemic' happening in some countries this was also important because sugar was implicated. Between 2005 and 2011, Burdakov's research lab contributed to the identification and characterization of glucose-sensing in orexin neurons. These are specialized neurons that have been found to sense glucose and produce the neurotransmitter orexin/hypocretin.
Orexin/hypocretin is a chemical "messenger" that contributes to the regulation of various physiological processes, including arousal, wakefulness and appetite. Orexin-producing neurons, identified about three decades ago, are only found in the hypothalamus, yet they innervate the entire central nervous system in humans and other mammals.
Orexin neurons are so important for our arousal and consciousness that without this small cluster of cells our normal consciousness is lost (as in narcolepsy—which is a disorder caused by loss of orexin cells or orexin in humans)
Part 1

Earlier experiments indicated that orexin cells are profoundly silenced by glucose, but that was 'in a dish,' in the experiments in isolated orexin cells. It since transpired that, in the living brain of a behaving mammal, orexin cells are profoundly controlled by many other things, including direct neural inputs from much of the brain.
The concentration of glucose in the blood is not only controlled by eating and exercising, it is known to also be regulated by the naturally occurring hormone insulin and the liver, which produce dynamic waves of blood glucose. Researchers used their sensors introduced in arteries to monitor these wave-like changes in glucose concentration over time.
This allowed them to note at what point in the waves (i.e., at their crest, trough, rise, fall) orexin neurons in the mouse brain became excited or fell silent. In addition, the researchers observed the behavior of the mice, particularly their spontaneous running, to determine whether it was influenced by blood glucose in normal mice and in mice that did not have orexin-producing neurons.
They found that the biggest modulation of orexin cell activity happened during the rise and fall of blood glucose waves. Surprisingly, orexin cells appeared almost blind to absolute levels of blood glucose, but mostly tracked the rises and falls, especially the rate-of-change of glucose during these rises and falls.
The findings gathered by the researchers highlight the potential role of orexin cells in tracking blood glucose levels, particularly their temporal features (i.e., their changes over time). They thus shed new light on the complex neurobiology of blood glucose perception in the brain.

Paulius Viskaitis et al, Orexin neurons track temporal features of blood glucose in behaving mice, Nature Neuroscience (2024). DOI: 10.1038/s41593-024-01648-w

Part 2

The first example of cellular origami discovered in protist

Combining a deep curiosity and "recreational biology,"  researchers have discovered how a simple cell produces remarkably complex behavior, all without a nervous system. It's origami, they say.

It is a  single teardrop-shaped cell that swims in a droplet of pond water. In an instant, a long, thin "neck" projects out from the bulbous lower end. And it keeps going. And going. Then, just as quickly, the neck retracts back, as if nothing had happened.

In seconds, a cell that was just 40 microns tip-to-tail sprouted a neck that extended 1,500 microns or more out into the world. It is the equivalent of a 6-foot human projecting its head more than 200 feet. All from a cell without a nervous system. All this is because of origami!

Eliott Flaum et al, Curved crease origami and topological singularities enable hyperextensibility of L. olor, Science (2024). DOI: 10.1126/science.adk5511. www.science.org/doi/10.1126/science.adk5511

Study links nanoparticles to altered blood vessel formation in embryos

Human life begins with a single egg cell that grows into a human being with trillions of cells. To ensure that the highly complex development of tissues and organs is as protected as possible, the placental barrier keeps pathogens and foreign substances out. Some researchers are investigating how this protective mechanism copes with nanoparticles.

The findings are published in the journal Advanced Science.

Nanoparticles are contained in a large number of products, but they are also produced during wear and tear as well as through combustion processes. We absorb these substances from the environment via our food, cosmetics or the air we breathe.

Some of these nanoparticles are suspected of harming babies in the womb. Low birth weight, autism and respiratory diseases are among the possible consequences for the child.

It is still unclear how the nanoparticles affect the unborn child. We already know that the placental barrier retains many nanoparticles or at least delays their transport to the embryo. However, damage to the fetal tissue occurs, even if no particles have been detected in the fetus. The researchers are now getting to the bottom of this long-range effect of nanoparticles. They are investigating the consequences of common nanoparticles such as titanium dioxide or diesel soot on the function of the placenta and their indirect damage to embryonic development.

For this purpose, the team used fully functional human placentas that were made available after planned cesarean sections. Human placental tissue is the only way to obtain meaningful results on the transport and effect of nanoparticles. The structure, metabolism and interaction of maternal and fetal tissue are unique and species-specific.

Part 1

The experiments showed that nanoparticles in placental tissue disrupt the production of a large number of messenger substances. And it is these messengers that can trigger serious changes in embryonic development, such as disturbed blood vessel formation.
These effects can be visualized in laboratory models using chicken eggs. The blood vessels in the egg actually grow at an enormous speed and density to enable embryonic development. A dense network of fine blood vessels covers the inside of the eggshell.

The situation is strikingly different in eggs treated with the altered messenger substances from the nanoparticle-treated placenta: In the experiments, the blood vessel system was not as dense but rather coarse-meshed. "Nanoparticles apparently have an indirect effect on the child in the womb by inhibiting the formation of blood vessels via messenger substances.
The researchers are currently investigating the health consequences of this.

Battuja Dugershaw‐Kurzer et al, Nanoparticles Dysregulate the Human Placental Secretome with Consequences on Angiogenesis and Vascularization, Advanced Science (2024). DOI: 10.1002/advs.202401060

Part 2

Dad’s diet affects sons’ health

Epigenetic inheritance of diet-induced and sperm-borne mitochondrial RNAs

A father’s sperm records his diet, which affects his sons’ metabolism — in both mice and in humans. The male offspring of mice that ate high-fat foods were more likely to have problems such as glucose intolerance, a characteristic of diabetes. And the sons of human dads with a high body-mass index had similar problems, according to an analysis of more than 3,000 children. In mice, an unhealthy diet changed certain types of sperm RNA, which could alter the offspring’s epigenome — the collection of chemical tags hanging from DNA and its associated proteins. Why this seems to only affect sons is “a very good question for future studies."

https://www.nature.com/articles/s41586-024-07472-3?utm_source=Live+...

https://www.nature.com/articles/d41586-024-01623-2?utm_source=Live+...

Bird flu in cows could spread through milk
Astonishing amounts of H5N1 virus have been found in the raw milk of cows infected with avian influenza. The virus can survive for hours in splattered milk. This reinforces that the milking process is probably driving transmission among cows and might be spreading the virus to humans. The fact that H5N1 doesn’t seem to spread through airborne particles is good news. It means changes to milking procedures — such as disinfecting equipment between cows and protective equipment to farm workers — could help to bring the outbreak under control.

Nature | 5 min read
Reference: bioRxiv preprint & medRxiv preprint (not peer reviewed)

Timing drug administration to endogenous circadian rhythms may enhance treatment efficacy

Taking blood pressure medication at a time that aligns with your personal chronotype – the way your body's circadian rhythm affects when you go to sleep and get up – could help to protect the heart against the risk of heart attack, a new study shows.

It may be beneficial for night owls to take their medication in the evening, and for early birds to take it in the morning. These timings seem to offer some protection against the risks associated with BP (also known as hypertension). The international team of researchers behind the new study looked at records for more than 5,300 individuals, who answered questions about their chronotype, before being randomly split into groups and instructed to take their blood pressure meds at different times. Participants were then monitored over several months. These results are exciting because they could represent a paradigm shift in the treatment of hypertension. This research has now shown for the first time that considering chronotype when deciding [the] dosing time of antihypertensives – [a strategy called] personalized chronotherapy – could reduce the risk of heart attack. Each person's circadian rhythm (24-hour biological cycle) varies slightly, based on genetics and other factors. These rhythms are well known for influencing our sleep patterns, but they also help to dictate body temperature, hormones, metabolism – and, importantly for this study, BP levels. If blood pressure cycles up and down throughout the day, the time that medications are taken might matter, the researchers hypothesized.

https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(24)...

Microplastics found in every semen sample tested by research team
A team of public health researchers affiliated with multiple institutions in China has found microplastics in the semen of every sample they tested. In their study, published in the journal Science of the Total Environment, the group looked for microplastics in semen samples obtained from 36 healthy adult men.

Prior research has shown that microplastics are nearly everywhere, found on mountaintops, remote islands in the upper atmosphere and the depths of the world's oceans. They have also been found in every organ in the human body.

In a recent discovery, scientists found that the average person consumes plastic in amounts equal to about one credit card every week. The researchers note that plastics can enter the body in multiple ways, such as through drinking from water bottles, breathing air particulates, or eating food heated in plastic containers. They further note that it is now practically impossible for people to avoid ingesting microplastics.

The health impacts remain unknown, but many scientists around the world are looking into it, suspecting microplastic ingestion may be behind many inflammatory diseases.
In this new effort, the research team wondered if ingested microplastics might be behind the global drop in fertility rates. To find out, they recruited 36 healthy adult males living in the city of Jinan, in the eastern part of China, who did not work in the plastics industry—each donated a sample of semen for testing.

Each of the samples was prepared by mixing it with a chemical solution then filtered for analysis by a team member using a microscope. The researchers found microplastics in every sample. They also found eight types of plastics, the most common of which was polystyrene, which is commonly used in packaging foam.
The team also found lower sperm motility in the semen samples containing polyvinyl chloride plastic bits, a finding that may help explain the decline in fertility rates.

Ning Li et al, Prevalence and implications of microplastic contaminants in general human seminal fluid: A Raman spectroscopic study, Science of The Total Environment (2024). DOI: 10.1016/j.scitotenv.2024.173522

Highlights of the study:

• •An early study to detect microplastics in semen from a general population cohort
• •Eight MP polymer types were identified, with PS, PE, and PVC most prevalent.
• •Raman microspectroscopy enabled sub-micron microplastic characterization.
• •PS and PVC correlated with differential effects on sperm motility.

• As widespread environmental pollution, MPs/NPs raise concerns about reproductive toxicity.

• •

  Infertility affects 15 % couples globally, with environmental factors playing a significant role.

• •

  Limited understanding of MPs/NPs effects on testes and ovaries necessitates further research.

• •

  Contaminants carried by particles may synergistically contribute to reproductive toxicity.

https://www.sciencedirect.com/science/article/pii/S0048969723048830

Part 2

Researcher suggests that gravity can exist without mass, mitigating the need for hypothetical dark matter

Dark matter is a hypothetical form of matter that is implied by gravitational effects that can't be explained by general relativity unless more matter is present in the universe than can be seen. It remains virtually as mysterious as it was nearly a century ago when first suggested by Dutch astronomer Jan Oort in 1932 to explain the so-called "missing mass" necessary for things like galaxies to clump together.

Now Dr. Richard Lieu at The University of Alabama in Huntsville (UAH) has published a paper in the Monthly Notices of the Royal Astronomical Society that shows, for the first time, how gravity can exist without mass, providing an alternative theory that could potentially mitigate the need for dark matter.  

The researcher contends the "excess" gravity necessary to bind a galaxy or cluster together could be due instead to concentric sets of shell-like topological defects in structures commonly found throughout the cosmos that were most likely created during the early universe when a phase transition occurred. A cosmological phase transition is a physical process where the overall state of matter changes together across the entire universe.

It is unclear presently what precise form of phase transition in the universe could give rise to topological defects of this sort.

Topological effects are very compact regions of space with a very high density of matter, usually in the form of linear structures known as cosmic strings, although 2D structures such as spherical shells are also possible.

Part 1

The shells in this paper consist of a thin inner layer of positive mass and a thin outer layer of negative mass; the total mass of both layers—which is all one could measure, mass-wise—is exactly zero, but when a star lies on this shell it experiences a large gravitational force pulling it towards the center of the shell.
As gravitational force fundamentally involves the warping of space-time itself, it enables all objects to interact with each other, whether they have mass or not. Massless photons, for example, have been confirmed to experience gravitational effects from astronomical objects.
Gravitational bending of light by a set of concentric singular shells comprising a galaxy or cluster is due to a ray of light being deflected slightly inwards—that is, towards the center of the large-scale structure, or the set of shells—as it passes through one shell.
The sum total effect of passage through many shells is a finite and measurable total deflection which mimics the presence of a large amount of dark matter in much the same way as the velocity of stellar orbits.

Both the deflection of light and stellar orbital velocities is the only means by which one gauges the strength of the gravitational field in a large-scale structure, be it a galaxy or a cluster of galaxies. The contention of this paper is that at least the shells it posits are massless. There is then no need to perpetuate this seemingly endless search for dark matter.

Richard Lieu, The binding of cosmological structures by massless topological defects, Monthly Notices of the Royal Astronomical Society (2024). DOI: 10.1093/mnras/stae1258

Part 2

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Researchers discover Earth and space share the same turbulence

In a paper published in Geophysical Research Letters, researchers have discovered that the turbulence in the thermosphere exhibits the same physical laws as the wind in the lower atmosphere. Furthermore, wind in the thermosphere predominantly rotates in a cyclonic direction, in that it rotates counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

The findings reveal a new unified principle for the Earth's varied environmental systems and can potentially improve future forecasting of both earth and space weather.

Facundo L. Poblet et al, Third‐Order Structure Functions of Zonal Winds in the Thermosphere Using CHAMP and GOCE Observations, Geophysical Research Letters (2024). DOI: 10.1029/2024GL108367

When Water Flows Uphill

Does magic really exist?

Study finds fresh water and key conditions for life appeared on Earth a half-billion years earlier than thought

We need two ingredients for life to start on a planet: dry land and (fresh) water. Strictly, the water doesn't have to be fresh, but fresh water can only occur on dry land.

Only with those two conditions met can you convert the building blocks of life, amino acids and nucleic acids into tangible bacterial life that heralds the start of the evolutionary cycle.

The oldest life on Earth left in our fragmented rock record is 3.5 billion years old, with some chemical data showing it may even be as old as 3.8 billion years. Scientists have hypothesized life might be even older, but we have no records of that being the case.

A new study published in Nature Geoscience provides the first evidence of fresh water and dry land on Earth by 4 billion years ago. Knowing when the cradle of life—water and land—first appeared on Earth ultimately provides clues as to how we came to be.

Fresh water is very different from sea water. Obviously, you might say, but how do you know if one or both were present on Earth if you can't actually go back in a time machine?

The answer is in the rock record and chemical signals preserved in that time capsule. Earth is a bit over 4.5 billion years old, and the oldest rocks scientists have found are just a little older than 4 billion years.

To really understand our planet in its first 500 million years, we have to turn to crystals that once came from older rocks and ended up deposited in younger rocks.

Unlike rocks, the oldest preserved crystals go back as far as 4.4 billion years. And the bulk of these super-old crystals comes from one place on Earth: the Jack Hills in Western Australia's midwest.

This is precisely where the researchers of this study went. They dated over a thousand crystals of a mineral called zircon, famed for its extreme resistance to weathering and alteration.

Part 1

This work shows that about 10% of all the crystals the researchers analyzed were older than 4 billion years. That might seem small, but it's an enormous amount of super-old grains compared to other places around the world.

To figure out whether these grains held a record of fresh water, they used tiny beams of ions on these dated zircon grains to measure the ratio of heavier to lighter oxygen. This ratio, known as an oxygen isotopic ratio, is thought to be nearly constant through time for seawater, but much lighter for fresh water.

Conspicuously, a small portion of zircon crystals from 4 billion years ago had a very light signature that could only have formed from the interaction of fresh water and rocks.
Zircon is extremely resistant to alteration. For the Jack Hills' zircon to obtain this light oxygen signature, the rock altered by fresh water had to melt and then re-solidify to impart the light oxygen isotopic signature into the zircon.

Thus, fresh water had to be present on Earth before 4 billion years ago.
Researchers now at least found evidence for the cradle of life on Earth some time before 4 billion years ago—extremely early in our planet's 4.5-billion-year history..

Hamed Gamaleldien et al, Onset of the Earth's hydrological cycle four billion years ago or earlier, Nature Geoscience (2024). DOI: 10.1038/s41561-024-01450-0

Part 2

Improved prime editing system makes gene-sized edits in human cells at therapeutic levels

Scientists have improved a gene-editing technology that is now capable of inserting or substituting entire genes in the genome in human cells efficiently enough to be potentially useful for therapeutic applications.

The advance could one day help researchers develop a single gene therapy for diseases such as cystic fibrosis that are caused by one of hundreds or thousands of different mutations in a gene. Using this new approach, they would insert a healthy copy of the gene at its native location in the genome, rather than having to create a different gene therapy to correct each mutation using other gene-editing approaches that make smaller edits.

The new method uses a combination of prime editing, which can directly make a wide range of edits up to about 100 or 200 base pairs, and newly developed recombinase enzymes that efficiently insert large pieces of DNA thousands of base pairs in length at specific sites in the genome. This system, called eePASSIGE, can make gene-sized edits several times more efficiently than other similar methods, and is reported in Nature Biomedical Engineering.

Pandey S, Gao XD, et al. Efficient site-specific integration of large genes in mammalian cells via continuously evolved recombinases and prime editing, Nature Biomedical Engineering (2024). DOI: 10.1038/s41551-024-01227-1

Compressed titanium and sulfur nanoribbons can transmit electricity without energy loss, scientists find

When compressed, nanoribbons of titanium and sulfur can change properties dramatically, turning into materials with the ability to conduct electricity without losing energy, according to a study published in the journal Nano Letters.

The authors have made the discovery during their painstaking search for new materials that can transmit electricity without loss of energy, a hot topic that has for long haunted the scientific community.

This new research focused on one such promising material: TiS₃ nanoribbons, which are tiny, ribbon-like structures made of titanium and sulfur. In their natural state, TiS₃ nanoribbons act as insulators, meaning they do not conduct electricity well.  The researchers, however, discovered that by applying pressure to these nanoribbons, we could change their electrical properties dramatically.

The scientists exposed TiS₃ to gradual pressure. As they increased the pressure, they found that the TiS₃ system underwent a series of transitions, from being insulators to becoming metals and superconductors, for the first time.

TiS₃ materials are known to work as good insulators, but it is the first time scientists have discovered that under pressure they can function as superconductors, paving the way for the development of superconducting materials.

Mahmoud Abdel-Hafiez et al, From Insulator to Superconductor: A Series of Pressure-Driven Transitions in Quasi-One-Dimensional TiS3 Nanoribbons, Nano Letters (2024). DOI: 10.1021/acs.nanolett.4c00824

Study: An estimated 135 million premature deaths linked to fine particulate matter pollution between 1980 and 2020

A study led by researchers from Nanyang Technological University, Singapore (NTU Singapore) revealed that fine particulate matter from 1980 to 2020 was associated with approximately 135 million premature deaths globally. The findings were published in April in the peer-reviewed journal Environment International.

In the study, premature deaths refer to fatalities that occur earlier than expected based on average life expectancy, resulting from preventable or treatable causes such as diseases or environmental factors.

The study found that the impact of pollution from fine particulate matter was worsened by climate variability phenomena such as the El Niño-Southern Oscillation, the Indian Ocean Dipole, and the North Atlantic Oscillation, and led to a 14 percent rise in premature deaths.

The researchers explain that during such weather events, the increased temperature, changes in wind patterns, and reduced precipitation can lead to stagnant air conditions and the accumulation of pollutants in the atmosphere. These result in higher concentrations of PM2.5 particles that are particularly harmful to human health when inhaled.
Fine particulate matter, or PM2.5, refers to particulate matter 2.5 micrometers in diameter or smaller. These tiny particles come from vehicle emissions, industrial processes, and natural sources such as wildfires and dust storms.

As they are so small, PM2.5 particles can easily get into the air we breathe and penetrate deep into our lungs, leading to a range of health problems, especially for vulnerable groups like children, the elderly, and people with respiratory conditions.

The study estimated that a third of the premature deaths from 1980 to 2020 were associated with stroke (33.3%); another third with ischemic heart disease (32.7%), while chronic obstructive pulmonary disease, lower respiratory infections, and lung cancer made up the rest of premature deaths.

S.H.L. Yim et al, Global health impacts of ambient fine particulate pollution associated with climate variability, Environment International (2024). DOI: 10.1016/j.envint.2024.108587

New study helps disentangle role of soil microbes in the global carbon cycle

When soil microbes eat plant matter, the digested food follows one of two pathways. Either the microbe uses the food to build its own body, or it respires its meal as carbon dioxide (CO₂) into the atmosphere.

Now a research team has, for the first time, tracked the pathways of a mixture of plant waste as it moves through bacteria's metabolism to contribute to atmospheric CO₂. The researchers discovered that microbes respire three times as much CO₂ from lignin carbons (non-sugar aromatic units) compared to cellulose carbons (glucose sugar units), which both add structure and support to plants' cellular walls.

These findings help disentangle the role of microbes in soil carbon cycling—information that could help improve predictions of how carbon in soil will affect climate change.

The study, "Disproportionate carbon dioxide efflux in bacterial metabolic pathways for different organic substrates leads to variable contribution to carbon use efficiency," was published on June 11 in the journal Environmental Science & Technology.

The carbon pool that's stored in soil is about 10 times the amount that's in the atmosphere.

What happens to this reservoir will have an enormous impact on the planet. Because microbes can unlock this carbon and turn it into atmospheric CO₂, there is a huge interest in understanding how they metabolize plant waste. As temperatures rise, more organic matter of different types will become available in soil. That will affect the amount of CO₂ that is emitted from microbial activities.

Caroll Mendonca et al, Disproportionate carbon dioxide efflux in bacterial metabolic pathways for different organic substrates leads to variable contribution to carbon use efficiency, Environmental Science & Technology (2024). DOI: 10.1021/acs.est.4c01328. pubs.acs.org/doi/10.1021/acs.est.4c01328

Chemists discover spontaneous nanoparticle formation in charged microdroplets

A team of chemists has found that particles of minerals sometimes break down spontaneously when immersed in charged microdroplets, leading to the formation of nanoparticles.

In their study, published in the journal Science, the group conducted experiments with minerals and an electrospray device

Prior research has shown that natural processes often result in the creation of nanoparticles and that many types of such nanoparticles exist in nature. But not much is known about how they are formed. In this new effort, the research team suspected that some of them may be the result of minerals becoming immersed in charged liquid particles. To find out if that might be the case, they designed an experiment to replicate such natural processes.
The researchers note that charged microdroplets are plentiful in the natural world, found in clouds and sea spray. To create their own charged microdroplets, they used an electrospray device.

When filled with water and electrically charged, it can produce a mist of charged droplets. In their experiments, the research team added mineral particles to the water before putting it in the spray device. They then captured samples of the charged microdroplets and other materials that were in the mist. They found many instances of nanoparticles being spontaneously expelled from the microdroplets into the air around them.

The researchers found that shortly after droplet formation, a double electric field was generated across its surface, producing a reactive sphere. That was followed by droplet fission when coulombic energy in the droplet exceeded its surface tension—and that was followed by expulsion of a mineral nanoparticle in the form of a microdroplet.

B. K. Spoorthi et al, Spontaneous weathering of natural minerals in charged water microdroplets forms nanomaterials, Science (2024). DOI: 10.1126/science.adl3364

R. Graham Cooks et al, Breaking down microdroplet chemistry, Science (2024). DOI: 10.1126/science.adp7627