Science

The words of Greta Thunberg this week

https://www.youtube.com/watch?v=-Pyi0L7_vwo

Activists are being systemically targeted with repression and are paying the price for defending life and the right to protest.

We are seeing now extremely worrying developments where activists all over the world are experiencing increased repressions just for fighting for our present and our future.

There is extreme hypocrisy when it comes to this. All over the world we're experiencing this. Not the least, for example, here in France. Just the other day - that activists are being systemically targeted with repression and are paying the price for defending life and the right to protest.

We're still speeding in the wrong direction

We are now at an extremely critical point. The emissions of greenhouse gasses are at an all-time-high, and the concentration of Co2 in the atmosphere hasn't been this high in the entire history of humanity.

And we're still speeding in the wrong direction. The emissions are on the rise, and science has been very clear on this. And the people living on the front-lines of the climate emergency have been sounding the alarm for a long time

Using surveys, cognitive tests and brain imaging, researchers have identified a type of depression that affects about a quarter of patients. The goal is to diagnose and treat the condition more precisely.

The global economy will grow slower in the 21st century than economists have expected, a finding that has implications for our ability to adapt to climate change in the coming decades, according to new research.

A new study projecting the economic futures of four income groups of countries over the next century finds growth will be slower than predicted, with developing countries taking longer to close the wealth gap and approach the income of wealthier nations. What economists have thought of as a worst-case scenario for global economic growth may, in fact, be a best-case scenario, according to the new study published today in Communications Earth & Environment.

The findings suggest governments need to start planning for slower growth and wealthier countries may need to help lower-income nations finance climate change adaptations in the coming decades, according to the study authors.

"We're at a point where we maybe need to significantly increase financing for [climate] adaptation in developing countries, and we're also at a point where we might be overestimating our future ability to provide that financing under the current fiscal paradigm," said Matt Burgess, a CIRES fellow, director of the Center for Social and Environmental Futures, and assistant professor of environmental studies at CU Boulder who led the new study.

"We can now start to winnow down the range of possibilities and move forward in more tangible ways," said Ryan Langendorf, a postdoctoral scholar at CU Boulder and co-author of the new study.

In the new study, Burgess and his colleagues used two economic models to project how much the global economy will grow over the next century and how quickly developing countries will approach the income levels of wealthier nations.

Both models found the global economy will continue to grow, but that growth will be slower than most economists expected and there will be a larger income gap between wealthier and poorer nations. This means richer countries may need to help finance climate adaptations for poorer countries, and debt-ceiling crises, like what the United States experienced this spring, may become more common.

"Slower growth than we think means higher deficits than we expect, all else equal," Burgess said. "That means debt would likely become more contentious and important over time, and could mean more frequent debt-ceiling fights."

Similar to a flight emergency, where individuals should put their own oxygen masks on first, wealthier nations should focus on getting their own financial houses in order so they can be in a position to support lower-income nations in financing climate adaptations, according to the researchers.

"We're talking about relatively less growth, relatively more inequality, but we're still talking about a world that is richer than today and more equal across countries than today's world," Burgess said.

Still, many wealthy nations are accustomed to growing their way out of debt, but that may not be possible under the new scenario, according to Ashley Dancer, a graduate student at CU Boulder and co-author of the study.

"The next question is: what are some ways that we should be or could be helping [lower-income countries] adapt, if the expectation is that they're not going to meet the level of wealth that would allow them to do that quickly and aggressively?" Dancer said.

An artist's impression shows an immensely energetic explosion called a gamma ray burst. Astronomers studying a powerful gamma-ray burst (GRB) with the International Gemini Observatory, operated by NSF's NOIRLab, may have observed the collision of stars or stellar remnants in the jam-packed environment surrounding a supermassive black hole at the core of an ancient galaxy.

International Gemini Observatory/NOIRLab/NSF/AURA/M. Garlick/M. Zamani/Handout via REUTERS

Very massive stars - more than 10 times the sun's mass - die in a supernova blast that leaves behind neutron stars or even denser black holes, whose gravitational pull is so strong no matter or light can escape

WASHINGTON, DC, USA – Astronomers have spotted an immensely energetic explosion emanating from an ancient galaxy, apparently triggered by a type of star destruction hypothesized for decades but never before observed. You might call it stellar death by demolition derby.

Researchers said the gamma-ray burst they observed may have been caused by the collision of two compact stars in the densely packed and chaotic environment near a supermassive black hole at the center of this elliptically shaped galaxy. They suspect the two doomed stars were neutron stars, which pack roughly the mass of our sun into a sphere only the size of a city.

“In order to explain the gamma-ray burst, it has to have been a compact star, so not one like the sun,” said astronomer Andrew Levan of Radboud University in the Netherlands, lead author of the research published this week in the journal Nature Astronomy.

“Gamma-ray bursts are the most powerful explosions in the universe. They release more energy per unit time than any other known cosmic phenomena. So they are really superlative in their properties. Their name comes from the first type of light that we see, gamma-rays, but they actually emit across the electromagnetic spectrum,” said astrophysicist and study co-author Wen-fai Fong of Northwestern University in Illinois.

Immense gravitational forces exerted by the black hole at the galactic center may wreak havoc, perturbing the motion of nearby stars and other objects and increasing the chances of collisions – akin, the researchers said, to a demolition derby.

“Most stars in the universe die in a predictable way, which is just based on their mass,” Levan said. “This research shows a new route to stellar destruction.”

Very massive stars – more than 10 times the sun’s mass – die in a supernova blast that leaves behind neutron stars or even denser black holes, whose gravitational pull is so strong no matter or light can escape. Relatively low-mass stars like our sun puff up and blow off their outer layers, transforming into a stellar remnant called a white dwarf.

The new findings show another path to stellar demise.

“The idea that stars also can die through collisions in extremely dense regions has been around since at least the 1980s. So we’ve been waiting for 40 years for the signatures to be found observationally,” Levan said.

Debris recovered in Bataan likely from Chinese rocket – PH Space Agency

The researchers used data from orbiting and ground-based telescopes to study the gamma-ray burst in a galaxy about 3 billion light-years away from Earth, roughly in the direction of the constellation Aquarius. A light year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).

This ancient galaxy was populated primarily by stars several billion years old.

“The galaxy is what we call ‘quiescent’ – a galaxy that is not actively forming stars at a high rate and is past its heyday,” Fong said. “These quiescent galaxies are very massive and have built up large supermassive black holes in their centers, making them a perfect breeding ground for stellar collisions.”

The distance between our sun and the nearest star, Proxima Centauri, is about 4 light years. This same expanse of space would be filled with perhaps ten million stars in a galactic core, with the supermassive black hole’s destabilizing influence stirring things up.

“You certainly wouldn’t want a front-row seat to one of these events,” Levan said.

“But, if you were close enough, you would see the two neutron stars get ever closer until their gravity deforms them and they begin to shred,” Levan added. “Then the cores of the stars would merge to make a black hole, surrounded by a disc of the remaining material. A fraction of a second later, this material would flow into the black hole, and a jet of material moving at 99.99% of the speed of light would launch,” representing the gamma-ray burst.

. . .

So far, the most promising dark matter candidates are axions, neutrinos, and weakly interacting massive particles. Recently, however, some physicists also started investigating the possibility that another type of hypothetical particles, massive gravitons, could be viable dark matter candidates.

Theory suggests that massive gravitons were produced during collisions between ordinary particles in the hot and dense environment of the early Universe, in the few instants following the Big Bang. While theories predict their existence, these particles have so far never been directly detected.

Researchers at Korea University and University of Lyon have recently carried out a theoretical study exploring the possibility that massive gravitons could be good dark matter candidates. The results of their theoretical calculations were published in a paper in Physical Review Letters.

. . .

The calculations performed by Cai, Lee and Cacciapaglia show that instead of being associated with unknown physics occurring shortly after the Big Bang, the production of massive gravitons is most effective below the energy scale in which Higgs bosons reside. Higgs bosons are elementary particles that carry the Higgs field, the field that gives mass to fundamental particles such as electrons and quarks.

"This draws a direct connection between the physics studied at the Large Hadron Collider in Geneva and the early Universe physics of gravity and Dark Matter," Cacciapaglia said. "Our results imply that gravitational dark matter is produced 1 picosecond after the Big Bang, at a time when particle physics is well described by the current theories."

. . .

#gravity #astronomy #gravitationalwaves

Discussions of valuable but threatened ocean ecosystems often focus on coral reefs or coastal mangrove forests. Seagrass meadows get a lot less attention, even though they provide wide-ranging services to society and store lots of climate-warming carbon.

But the findings of a new University of Michigan-led study show that seagrass ecosystems deserve to be at the forefront of the global conservation agenda, according to the authors. It's the first study to put a dollar value on the many services -- from storm protection to fish habitat to carbon storage -- provided by seagrasses across the Caribbean, and the numbers are impressive.

Using newly available satellite data, the researchers estimate that the Caribbean holds up to half the world's seagrass meadows by surface area, and it contains about one-third of the carbon stored in seagrasses worldwide.

They calculated that Caribbean seagrasses provide about $255 billion in services to society annually, including $88.3 billion in carbon storage.

In the Bahamas alone, the ecosystem services provided by seagrasses are valued at more than 15 times the country's 2020 gross domestic product, according to the study published online June 21 in the journal Biology Letters.

"Our study is the first to show that seagrass beds in the Caribbean are of global importance in their areal extent, in the amount of carbon they store, and in the value of the economic services they provide to society," said study lead author Bridget Shayka, a doctoral student in the U-M Department of Ecology and Evolutionary Biology.

"The findings underscore the importance of conserving and protecting these highly threatened and globally important ecosystems, which are critical allies in the fight against climate change."

One way to prioritize seagrass conservation would be to include those verdant undersea meadows in global carbon markets through projects that minimize loss, increase areal extent or restore degraded beds.

The idea of selling "blue carbon" offset credits, which monetize carbon stored in coastal and marine ecosystems, is gaining traction for several reasons.

For one, many island nations that have already been impacted by climate change -- through increasingly intense hurricanes or rising sea levels, for example -- have large areas of valuable coastal ecosystems that store carbon and that provide other services to society.

Blue carbon (the name refers specifically to carbon stored in coastal and open-ocean ecosystems while "green carbon" refers more broadly to carbon stored in all natural ecosystems) offset credits could be a way for wealthier countries to compensate for their contribution to human-caused climate change while at the same time benefiting the economies of impacted countries and helping to conserve coastal ecosystems, which are among the most impaired in the world.

Threats to seagrass meadows include coastal development, chemical pollution, recreation, shipping and climate change.

"Because seagrass ecosystems are both highly important for carbon storage and sequestration, and are highly degraded globally, they represent an important burgeoning market for blue carbon," said marine ecologist and study senior author Jacob Allgeier, an associate professor in the U-M Department of Ecology and Evolutionary Biology.

"Yet, to date, a fundamental impediment to both evaluating seagrass and promoting it in the blue carbon market has been the lack of thorough seagrass distribution data."

For their study, the U-M-led team used newly available seagrass distribution data collected by the PlanetScope constellation of small DOVE satellites. They classified Caribbean seagrass ecosystems as either sparse or dense and estimated the amount of carbon in plants and sediments using data from Thalassia testudinum, the dominant seagrass species in the region.

The researchers then calculated a conservative economic value for the total ecosystem services provided by seagrasses in the Caribbean and for the stored carbon, using previously published estimates for the value of services including food production, nursery habitat for fishes and invertebrates, recreation and carbon storage.

Grouper, queen conch and lobster are among the commercially harvested animals that rely on Caribbean seagrass. Green sea turtles, tiger sharks and manatees also depend on it.

To estimate the dollar value of the carbon stored in Caribbean seagrass beds, the researchers used $18 per metric ton of carbon dioxide equivalents, borrowed from California's cap and trade program.

In addition to Caribbean-wide estimates, the researchers calculated values for individual countries in the region:

The Bahamas has the largest share of Caribbean seagrass (61%), providing total ecosystem services valued at $156 billion annually, including $54 billion in carbon storage.

Cuba ranks second in areal seagrass coverage (33% of the Caribbean total), with a value of $84.6 billion per year for all ecosystem services, including $29.3 billion for carbon storage.

The dollar value of the carbon in seagrasses around Cuba is equivalent to 27% of the country's 2020 GDP.

"Importantly, the degradation of seagrass beds often leads to erosion and sediment resuspension, which can create a positive feedback of increased seagrass loss and the release of C stored in sediments," the authors wrote. "Blue carbon finance thus represents a potential mechanism by which the global community can invest in conserving and protecting these vital ecosystems."

More than 60 species of seagrasses grow in shallow coastal waters around the world. They evolved from land plants that recolonized the oceans 70 to 100 million years ago.

In a separate paper accepted for publication in the journal Proceedings of the Royal Society, Allgeier and colleagues show that the construction of artificial reefs in the Caribbean can help protect seagrass ecosystems from human impacts, including nutrient pollution and overfishing.

Seagrasses use photosynthesis to pull carbon dioxide from the atmosphere, then store the carbon in plant tissues. The seagrasses are quickly inundated by sediments, slowing decomposition. As a result, more than 90% of the carbon stored in seagrass beds is in the top meter of sediment.

Caribbean seagrasses and associated sediments store an estimated 1.3 billion metric tons of carbon, according to the new study. That's a big number, but it's just 1.09% of the carbon contained in above- and below-ground woody biomass in the Amazon, and just 1.12% of the carbon in the biomass and soils of the world's temperate forests, according to the new study.

Study authors, in addition to Shayka and Allgeier, are Maximilian Hesselbarth of the U-M Department of Ecology and Evolutionary Biology, Steven Schill of The Nature Conservancy and William Currie of the U-M School for Environment and Sustainability.

Support for the study was provided by the David and Lucile Packard Fellowship and the National Science Foundation.

International Gemini Observatory traces gamma-ray burst to nucleus of ancient galaxy, suggesting stars can undergo demolition-derby-like collisions.

Astronomers studying a powerful gamma-ray burst (GRB) with the Gemini South telescope, operated by NSF's NOIRLab, may have detected a never-before-seen way to destroy a star. Unlike most GRBs, which are caused by exploding massive stars or the chance mergers of neutron stars, astronomers have concluded that this GRB came instead from the collision of stars or stellar remnants in the jam-packed environment surrounding a supermassive black hole at the core of an ancient galaxy.

Most stars in the Universe die in predictable ways, depending on their mass. Relatively low-mass stars like our Sun slough off their outer layers in old age and eventually fade to become white dwarf stars. More massive stars burn brighter and die sooner in cataclysmic supernova explosions, creating ultradense objects like neutron stars and black holes. If two such stellar remnants form a binary system, they also can eventually collide. New research, however, points to a long-hypothesized, but never-before-seen, fourth option.

While searching for the origins of a long-duration gamma-ray burst (GRB), astronomers using the Gemini South telescope in Chile, part of the International Gemini Observatory operated by NSF's NOIRLab, and other telescopes [1], have uncovered evidence of a demolition-derby-like collision of stars or stellar remnants in the chaotic and densely packed region near an ancient galaxy's supermassive black hole.

"These new results show that stars can meet their demise in some of the densest regions of the Universe where they can be driven to collide," said Andrew Levan, an astronomer with Radboud University in The Netherlands and lead author of a paper appearing in the journal Nature Astronomy. "This is exciting for understanding how stars die and for answering other questions, such as what unexpected sources might create gravitational waves that we could detect on Earth."

Ancient galaxies are long past their star-forming prime and would have few, if any, remaining giant stars, the principal source of long GRBs. Their cores, however, are teeming with stars and a menagerie of ultra-dense stellar remnants, such as white dwarf stars, neutron stars, and black holes. Astronomers have long suspected that in the turbulent beehive of activity surrounding a supermassive black hole, it would only be a matter of time until two stellar objects collide to produce a GRB. Evidence for that type of merger, however, has been elusive.

The first hints that such an event had occurred were seen on 19 October 2019 when NASA's Neil Gehrels Swift Observatory detected a bright flash of gamma rays that lasted for a little more than one minute. Any GRB lasting more than two seconds is considered "long." Such bursts typically come from the supernova death of stars at least 10 times the mass of our Sun -- but not always.

The researchers then used Gemini South to make long-term observations of the GRB's fading afterglow to learn more about its origins. The observations allowed the astronomers to pinpoint the location of the GRB to a region less than 100 light-years from the nucleus of an ancient galaxy, which placed it very near the galaxy's supermassive black hole. The researchers also found no evidence of a corresponding supernova, which would leave its imprint on the light studied by Gemini South.

"Our follow-up observation told us that rather than being a massive star collapsing, the burst was most likely caused by the merger of two compact objects," said Levan. "By pinpointing its location to the center of a previously identified ancient galaxy, we had the first tantalizing evidence of a new pathway for stars to meet their demise."

In normal galactic environments, the production of long GRBs from colliding stellar remnants such as neutron stars and black holes is thought to be vanishingly rare. The cores of ancient galaxies, however, are anything but normal and there may be a million or more stars crammed into a region just a few light-years across. Such extreme population density may be great enough that occasional stellar collisions can occur, especially under the titanic gravitational influence of a supermassive black hole, which would perturb the motions of stars and send them careening in random directions. Eventually, these wayward stars would intersect and merge, triggering a titanic explosion that could be observed from vast cosmic distances.

It is possible that such events occur routinely in similarly crowded regions across the Universe but have gone unnoticed until this point. A possible reason for their obscurity is that galactic centers are brimming with dust and gas, which could obscure both the initial flash of the GRB and the resulting afterglow. This particular GRB, identified as GRB 191019A, may be a rare exception, allowing astronomers to detect the burst and study its after effects.

The researchers would like to discover more of these events. Their hope is to match a GRB detection with a corresponding gravitational-wave detection, which would reveal more about their true nature and confirm their origins, even in the murkiest of environments. The Vera C. Rubin Observatory, when it comes online in 2025, will be invaluable in this kind of research.

"Studying gamma-ray bursts like these is a great example of how the field is really advanced by many facilities working together, from the detection of the GRB, to the discoveries of afterglows and distances with telescopes like Gemini, through to detailed dissection of events with observations across the electromagnetic spectrum," said Levan.

"These observations add to Gemini's rich heritage developing our understanding of stellar evolution," says Martin Still, NSF's program director for the International Gemini Observatory. "The time sensitive observations are a testament to Gemini's nimble operations and sensitivity to distant, dynamic events across the Universe."

A new IIASA-led study explored fairness and feasibility in deep mitigation pathways with novel carbon dioxide removal, taking into account institutional capacity to implement mitigation measures.

Meeting the 1.5°C goal of the Paris Agreement will require ambitious climate action this decade. Difficult questions remain as to how warming can be limited within technical realities while respecting the common but differentiated responsibilities and respective capabilities of nations on the way to a sustainable future. Meeting this challenge requires substantial emissions reductions to reach net-zero emissions globally.

Among the new options being studied in scientific literature, engineered Carbon Dioxide Removal (CDR) like Direct Air Capture of CO2 with Carbon Capture and Storage (DACCS), is a potentially promising technology to help bridge this gap. DACCS captures carbon by passing ambient air over chemical solvents, which can be considered a form of CDR if the captured carbon is stored permanently underground. But whether these novel technologies can help make ambitious goals more attainable, or whether they can help reach them more equitably remains an open question.

In their study published in Environmental Research Letters, an interdisciplinary research group led by IIASA scientists developed new scenarios exploring fairness and feasibility in deep mitigation pathways, including novel CDR technologies. For the first time, the team implemented DACCS in a well-established integrated assessment model called MESSAGEix-GLOBIOM, and studied how this technology could impact global mitigation pathways under different scenarios of environmental policy effectiveness based on country-level governance indicators.

"In current policy debates, concerns about the political feasibility and fairness of the current generation of climate mitigation scenarios are raised, and DACCS is often proposed as a possible solution. In our study we quantified under what conditions and how DACCS might address those concerns," explains Elina Brutschin, a study coauthor and researcher in the Transformative Institutional and Social Solutions Research Group of the IIASA Energy, Climate, and Environment Program.

The researchers emphasize that the goal of limiting warming to 1.5°C does not change when considering novel forms of CDR. For a broader perspective on pathways to limit warming, the research team investigated how novel CDR interacts under different assumptions of technoeconomic progress and the evolution of regional institutional capacity. The researchers highlight the risks of dependency on unproven carbon removal while also discussing the role novel CDR and similar technologies could play in the future for developing countries.

The results indicate that novel CDR can keep pre-Paris climate targets within reach when accounting for such risks, but that increasing institutional capacity beyond historical trends is necessary for limiting warming to the Paris Agreement's 1.5°C goal, even with novel CDR processes. The study also suggests that substantially improving institutional capacity to implement environmental policies, regulations, and legislation is critical to keep warming below 2°C if new forms of CDR fail to emerge in the near future.

The authors further point out that, when accounting for the possible future evolution of novel CDR technologies combined with inherent risks, the 'fairness' of overall outcomes did not meaningfully improve. DACCS did not impact near-term required global mitigation ambition, and additional carbon removal in developed economies accounted for only a small component of the mitigation necessary to achieve stringent climate targets. This is because the removal of carbon dioxide in these areas does not compensate sufficiently for their historical emissions by mid-century.

The inability of DACCS to enhance the fairness of outcomes, like cumulative carbon emissions, in 1.5°C scenarios, emphasizes the notion that meeting global climate targets is a global effort requiring an 'all-of-the-above' mitigation strategy. There is no room for flexibility when it comes to reaching climate goals.

The results, however, show that engineered removals can play a role in making the post-peak temperature stabilization (or decline) phase more equitable. This means that the full timeframe under which accounting takes place is critical for exploring fair outcomes that are agreeable by most Parties to the United Nations Framework Convention on Climate Change (UNFCCC).

"Our results show that new technologies for removing carbon from the atmosphere can play a role in ambitious climate policy, but they won't be a silver bullet for solving the climate crisis. Developed countries especially need to cut emissions by more than half this decade, primarily by reducing existing sources of emissions while scaling up CDR technologies to be in line with the Paris Agreement," says study lead author Matthew Gidden, a researcher in the IIASA Energy, Climate, and Environment Program.

The researchers emphasize that there is a clear need for the modeling community to assess the role of novel CDR in a structured way to better understand robust outcomes and insights versus observations related to a given model framework or approach. Looking forward, these issues can be explicitly included in scenario design to arrive at more equitable outcomes while incorporating political realities of the capabilities of governments and institutions to enact strong climate policy.

cross-posted from: https://lemmy.ml/post/1451517

Isotope ratios found in meteorites suggest that a supernova exploded nearby while the Sun and Solar System were still forming. But the blast wave from a supernova that close could have potentially destroyed the nascent Solar System. New calculations shows that a filament of molecular gas, which is the birth cocoon of the Solar System, aided the capture of the isotopes found in the meteorites, while acting as a buffer protecting the young Solar System from the nearby supernova blast.

Primitive meteorites preserve information about the conditions at the birth of the Sun and planets. The meteorite components show an inhomogeneous concentration of a radioactive isotope of aluminum. This variation suggests that an additional amount of the radioactive aluminum was introduced shortly after the Solar System started forming. A nearby supernova explosion is the best candidate for this injection of new radioactive isotopes. But a supernova that was close enough to deliver the amount of isotopes seen in meteorites would have also created a blast wave strong enough to rip the nascent Solar System apart.

A team led by Doris Arzoumanian at the National Astronomical Observatory of Japan proposed a new explanation of how the Solar System acquired the amount of isotopes measured in meteorites while surviving the supernova shock. Stars form in large groups called clusters inside giant clouds of molecular gas. These molecular clouds are filamentary. Small stars like the Sun usually form along the filaments and large stars, which will explode in a supernova, usually form at the hubs where multiple filaments cross.

Assuming that the Sun formed along a dense molecular gas filament, and a supernova exploded at a nearby filament hub, the team's calculation showed that it would take at least 300,000 years for the blast wave to break up the dense filament around the forming Solar System. The components of meteorites enriched in radioactive isotopes formed in approximately the first 100,000 years of Solar System formation inside the dense filament. The parent filament may have acted as a buffer to protect the young Sun and helped catch the radioactive isotopes from the supernova blast wave and channel them into the still forming Solar System.

Adults who live in walkable neighborhoods are more likely to interact with their neighbors and have a stronger sense of community than people who live in car-dependent communities, report researchers at the Herbert Wertheim School of Public Health and Human Longevity Science at University of California San Diego.

The findings of the study, published online in the journal Health & Place, support one of six foundational pillars suggested by United States Surgeon General Vivek Murthy as part of a national strategy to address a public health crisis caused by loneliness, isolation and lack of connection in this country.

In May 2023, the Surgeon General Advisory stated that loneliness and isolation can lead to a 29% increased risk of heart disease, a 32% increased risk of stroke, a 50% increased risk of developing dementia among older adults, and increases risk of premature death by more than 60%.

To address this public health crisis, the Surgeon General recommends strengthening social infrastructure by designing environments that promote connection.

"Our built environments create or deny long-lasting opportunities for socialization, physical activity, contact with nature, and other experiences that affect public health," said James F. Sallis, Ph.D., Distinguished Professor at the Herbert Wertheim School of Public Health and senior author of the UC San Diego study.

"Transportation and land use policies across the U.S. have strongly prioritized car travel and suburban development, so millions of Americans live in neighborhoods where they must drive everywhere, usually alone, and have little or no chance to interact with their neighbors."

Walkable neighborhoods promote active behaviors like walking for leisure or transportation to school, work, shopping or home.

The study analyzed data from the Neighborhood Quality of Life Study, which included 1,745 adults ages 20 to 66 living in 32 neighborhoods located in and around Seattle, Baltimore and Washington, D.C.

Neighborhood walkability may promote social interactions with neighbors -- like waving hello, asking for help or socializing in their homes, said the first author, Jacob R. Carson, M.P.H., a student in the UC San Diego -- San Diego State University Joint Doctoral Program in Public Health. Carson began the research while a Master of Public Health student at the Herbert Wertheim School of Public Health.

Neighborhoods where people must drive in and out, and where there is an absence of gathering places, may have the opposite effect, preventing neighbors from socializing.

"Promoting social interaction is an important public health goal. Understanding the role of neighborhood design bolsters our ability to advocate for the health of our communities and the individuals who reside in them," said Carson.

"Fewer traffic incidents, increases in physical activity, and better neighborhood social health outcomes are just a few of the results of designing walkable neighborhoods that can enrich our lives."

Co-authors include: Terry L. Conway and Kelli L. Cain, UC San Diego; Lilian G. Perez, RAND Corporation; Lawrence D. Frank, UC San Diego Department of Urban Studies and Planning and Urban Design 4 Health, Inc.; and Brian E. Saelens, Seattle Children's Research Institute and University of Washington.

Researchers have demonstrated how carbon dioxide can be captured from industrial processes -- or even directly from the air -- and transformed into clean, sustainable fuels using just the energy from the Sun.

The researchers, from the University of Cambridge, developed a solar-powered reactor that converts captured CO2 and plastic waste into sustainable fuels and other valuable chemical products. In tests, CO2 was converted into syngas, a key building block for sustainable liquid fuels, and plastic bottles were converted into glycolic acid, which is widely used in the cosmetics industry.

Unlike earlier tests of their solar fuels technology however, the team took CO2 from real-world sources -- such as industrial exhaust or the air itself. The researchers were able to capture and concentrate the CO2 and convert it into sustainable fuel.

Although improvements are needed before this technology can be used at an industrial scale, the results, reported in the journal Joule, represent another important step toward the production of clean fuels to power the economy, without the need for environmentally destructive oil and gas extraction.

For several years, Professor Erwin Reisner's research group, based in the Yusuf Hamied Department of Chemistry, has been developing sustainable, net-zero carbon fuels inspired by photosynthesis -- the process by which plants convert sunlight into food -- using artificial leaves. These artificial leaves convert CO2 and water into fuels using just the power of the sun.

To date, their solar-driven experiments have used pure, concentrated CO2 from a cylinder, but for the technology to be of practical use, it needs to be able to actively capture CO2 from industrial processes, or directly from the air. However, since CO2 is just one of many types of molecules in the air we breathe, making this technology selective enough to convert highly diluted CO2 is a huge technical challenge.

"We're not just interested in decarbonisation, but de-fossilisation -- we need to completely eliminate fossil fuels in order to create a truly circular economy," said Reisner. "In the medium term, this technology could help reduce carbon emissions by capturing them from industry and turning them into something useful, but ultimately, we need to cut fossil fuels out of the equation entirely and capture CO2 from the air."

The researchers took their inspiration from carbon capture and storage (CCS), where CO2 is captured and then pumped and stored underground.

"CCS is a technology that's popular with the fossil fuel industry as a way to reduce carbon emissions while continuing oil and gas exploration," said Reisner. "But if instead of carbon capture and storage, we had carbon capture and utilisation, we could make something useful from CO2 instead of burying it underground, with unknown long-term consequences, and eliminate the use of fossil fuels."

The researchers adapted their solar-driven technology so that it works with flue gas or directly from the air, converting CO2 and plastics into fuel and chemicals using only the power of the sun.

By bubbling air through the system containing an alkaline solution, the CO2 selectively gets trapped, and the other gases present in air, such as nitrogen and oxygen, harmlessly bubble out. This bubbling process allows the researchers to concentrate the CO2 from air in solution, making it easier to work with.

The integrated system contains a photocathode and an anode. The system has two compartments: on one side is captured CO2 solution that gets converted into syngas, a simple fuel. On the other plastics are converted into useful chemicals using only sunlight.

"The plastic component is an important trick to this system," said co-first author Dr Motiar Rahaman. "Capturing and using CO2 from the air makes the chemistry more difficult. But, if we add plastic waste to the system, the plastic donates electrons to the CO2. The plastic breaks down to glycolic acid, which is widely used in the cosmetics industry, and the CO2 is converted into syngas, which is a simple fuel."

"This solar-powered system takes two harmful waste products -- plastic and carbon emissions -- and converts them into something truly useful," said co-first author Dr Sayan Kar.

"Instead of storing CO2 underground, like in CCS, we can capture it from the air and make clean fuel from it," said Rahaman. "This way, we can cut out the fossil fuel industry from the process of fuel production, which can hopefully help us avoid climate destruction."

"The fact that we can effectively take CO2 from air and make something useful from it is special," said Kar. "It's satisfying to see that we can actually do it using only sunlight."

The scientists are currently working on a bench-top demonstrator device with improved efficiency and practicality to highlight the benefits of coupling direct air capture with CO2 utilisation as a path to a zero-carbon future.

Tidal range schemes are financially viable and could lower energy bills say researchers.

Research by Lancaster University's School of Engineering and the UK Centre for Ecology and Hydrology combined a tidal range power generation model with its cost model to demonstrate the viability of tidal power.

Professor George Aggidis, Head of Energy Engineering at Lancaster University, said: "The obvious question for the UK, with one of the best tidal resources globally, is why haven't we already got a tidal barrage scheme?"

The research published in Energy demonstrates the benefits of tidal energy, which does not suffer from unpredictable intermittency as power is generated both day and night.

The creation of a tidal barrage could operate for 120 years or more to meet future demand and storage problems.

Professor Aggidis said: "There is an urgent need to kick-start the selection and development of schemes around Britain. Tidal range generation is predictable renewable energy driven by the gravitational pull of the moon and sun. The environmental and economic benefits are huge as barrages can protect coastal areas from flooding and sea level rise. With two-way generation and pumping, the full range of existing tides can be maintained within impoundments to protect and support low-lying intertidal areas such as saltmarshes and mudflats.

Our studies show that with modern technology and operating procedures, estuarine barrages are the only practical way to protect these vital habitats. Coastal lagoons have also been proposed for several locations around Britain's coast. Schemes will provide jobs in construction and manufacturing for generations to come as well as opportunities for transport, communication, conservation, and recreation. In the long-term they will provide reliable power with reduced costs."

The UK has the second highest tidal range in the world and offers the UK a level of independence from global prices and in the long-term cheap clean power.

Currently the Tidal Range projects under commercial consideration offer an achievable 10 GW installed capacity, delivering over 20TWh/y, about 5% of UK energy use. Based on the UK relevant resource availability there is the potential to further increase this installed capacity over 4 to 5 times with other tidal range project sites around the UK.

Such developments are essential to assist the UK to reduce its carbon emissions by replacing fossil fuel power stations. The current UK total generating capacity is around 42.8 GW that includes fossil fuels (19.2GW 44.9%), renewables (16.5GW, 38.5%), and low carbon (7.1GW -- 16.6%). The La Rance Tidal Range plant in France today generates the cheapest electricity in the EDF fleet -- cheaper than nuclear.

Probiotics can help maintain a healthy gut microbiome or restore populations of "good bacteria" after a heavy course of antibiotics. But now, they could also be used as an effective treatment strategy for certain intestinal diseases, such as Crohn's disease. Researchers reporting in ACS Central Science have developed a microgel delivery system for probiotics that keeps "good" bacteria safe while actively clearing out "bad" ones. In mice, the system treated intestinal inflammation without side effects.

In the digestive system, there's a delicate balance of bacterial populations. When this balance is disrupted, bad bacteria can take over the colon, causing it to swell, resulting in colitis. Certain diseases, including inflammatory bowel disease and Crohn's disease, involve chronic colitis and currently require immunosuppressants to treat them. These drugs are expensive and non-specific, sometimes giving rise to antibiotic-resistant bacteria.

An alternative strategy is to deliver beneficial bacteria, or probiotics, to help restore balance. But to reach the colon, a treatment must first pass through stomach acid, withstand being cleared out by the intestine, then fight for space alongside the numerous invading bacteria. Pairing probiotics with a drug delivery system could make this strategy feasible, though most current approaches simply protect the probiotics from digestion without affecting the microbes responsible for the condition. So, Zhenzhong Zhang, Junjie Liu, Jinjin Shi and colleagues wanted to combine probiotics with specialized microgel spheres that could not only protect the good bacteria, but also actively help clear out the bad.

To create their system, the researchers combined sodium alginate, tungsten and calcium-containing nanoparticles into small, spherical microgels, then coated them with beneficial, probiotic bacteria. The gels protected the bacteria as they made their way through the stomach and increased their retention time in the colon. Once there, calprotectin proteins -- highly expressed during colitis -- bound to the calcium and disassembled the gels, allowing the tungsten to escape. By displacing molybdenum in a key enzyme substrate of the bad bacterium Enterobacteriaceae, tungsten inhibited the microbe's growth while leaving the probiotics unaffected. In experiments using a colitis mouse model, the system allowed probiotics to proliferate in the intestine without any side effects. Additionally, mice with the microgel spheres did not exhibit many of the hallmarks of colitis, such as shortened colons or damaged intestinal barriers, showing that the delivery system could be a viable treatment strategy. Though the researchers also want to prove its utility in more advanced preclinical models, they say that this work provides a new perspective into treatments using colonizing probiotics.