Why do some environmental shocks lead to disaster while others don't?

It's no longer just about stopping, but how we can live with climate change. To figure this out, we must delve into our cultures, as highlighted in a special issue of The Royal Society. A study by the Complexity Science Hub points out how our history could help guide the way.

Currently, we are grappling with a global crisis convergence. Various types of threats intersect, intertwine, and test our collective resilience, from climate change and economic inequality to political polarization. Although the scale and global reach of these challenges present new hurdles, these threats have been faced and, sometimes, overcome in the past. Societies today barely have time to recover from one crisis to the next, but we possess a significant advantage: knowledge. The knowledge we can obtain from our history through new methods.

DATA FROM MORE THAN 15O CRISES

CSH researchers Peter Turchin and Daniel Hoyer have pioneered fresh approaches to drawing lessons from history. Together with colleagues from different fields, they have compiled the Crisis Database (CrisisDB) as part of the Global History Databank Seshat, containing over 150 past crises spanning different time periods and regions.

When earthquakes shook the earth, droughts parched the land, or floods ravaged regions, some societies succumbed to social unrest, civil violence, or total collapse, while others exhibited resilience, maintaining essential social functions or even achieving improvement through systemic reforms that promoted well-being and increased democratic participation. Daniel Hoyer remarks, "What we observe is that not every ecological shock or climatic anomaly leads to collapse or even a severe crisis, and not every crisis involves a major environmental stressor." But what makes the difference? What drives collapse versus positive change?

DIVERGENT EXPERIENCES IN DIFFERENT TIMES AND PLACES

To illustrate the divergent dynamics experienced by past societies, and to highlight the comprehensiveness of their data, the researchers provide three examples. The Zapotec hilltop settlement of Monte Albán in southern Mexico emerged as the most significant settlement in the region. Extreme, persistent drought hit the region in the 9th century, and the once-great site of Monte Albán was entirely abandoned along with many other cities in Mesoamerica. However, recent research presented here shows that this was hardly a case of 'societal collapse', as many former residents of Monte Albán resettled in smaller communities nearby, likely without massive mortality, but rather through an ideological and socio-economic reorientation that also preserved many aspects of their society.

On the opposite end of the spectrum, the immensely wealthy Qing Dynasty in China proved resilient to adverse ecological conditions -- recurrent floods, droughts, swarms of locusts -- during the early part of their reign, but by the 19th century, social pressures had built up leaving them more vulnerable to these same challenges. It was in this period that suffered the Taiping Rebellion, often seen as the bloodiest civil war in human history, and ultimately collapsed completely in 1912 after 250 years of rule. Learn more about the causes in a new study.

In between, the researchers highlight the Ottoman Empire, which faced daunting environmental conditions during the 16th century, including recurrent droughts and the Little Ice Age, leading to social unrest and numerous rebellions led by disgruntled local officials and wealthy families, yet they managed to maintain key social and political structures and avoided collapse, ruling a large swath of territory for several hundreds of years more.

GENERALIZABLE TO MULTIPLE CASES

"Many studies typically concentrate on a single event or a specific society. However, it is only by exploring the responses of all, or at least many, societies affected by a particular climate 'regime' that we can ascertain the causal influence and overall effectiveness of the environmental stressor," Peter Turchin says. With this objective in mind, the researchers have developed a methodological framework aimed at producing insights that can be applied to numerous cases across different regions and time periods, helping identify the underlying causes of divergent outcomes.

UNDERSTANDING THE DYNAMICS

"The course of a crisis hinges on numerous factors. Environmental forces are undeniably pivotal, but it's not as straightforward as a specific climate event triggering a predetermined societal response," asserts Turchin. Instead, these forces interact with cultural, political, and economic dynamics. Only by comprehending these dynamics can we fathom the interactions. Through their work on the CrisisDB program, the researchers and colleagues aim to unveil these patterns and pinpoint the key factors that either fortify or undermine resilience to contemporary climate shocks.

Read more at Science Daily

Pearl Harbor: Bombed battleships' boost for climate science

Weather data from several ships bombed by Japanese pilots at Pearl Harbor has been recovered in a rescue mission that will help scientists understand how the global climate is changing.

Crew members aboard various vessels -- such as the USS Pennsylvania and the USS Tennessee -- died when their battleships were targeted in December 1941. Despite these losses, many boats returned to service during the Second World War and US naval servicemen continued their daily duties, which included recording weather data.

A new research paper, published in Geoscience Data Journal, tells the story of the recovery of World War II weather data that comes from 19 US Navy ships. Its rescue was made possible thanks to the hard work of over 4,000 volunteers who transcribed more than 28,000 logbook images from the US Navy fleet stationed at Hawai'i from 1941-1945. Previous studies have suggested these years were abnormally warm. The new dataset, encompassing over 630,000 records with more than 3 million individual observations, will help to show whether this was the case.

Dr Praveen Teleti, the University of Reading research scientist who led the research, said: "Disruptions to trade routes in World War II led to a significant reduction in marine weather observations. Until recently, records from that time were still only available in classified paper documents. The scanning and rescuing of this data provides a window into the past, allowing us to understand how the world's climate was behaving during a time of tremendous upheaval.

"There are two sets of people we need to thank for making this mission a success. We are very grateful to the global team of citizen scientists for transcribing these observations and creating a huge dataset that includes millions of entries about air and sea surface temperatures, atmospheric pressure, wind speed, and wind direction.

"The greatest respect must go to the brave servicemen who recorded this data. War was all around them, but they still did their jobs with such professionalism. It is thanks to their dedication and determination that we have these observations 80 years on."

Data from devastated ships

The logbooks used in the project come from 19 different ships, including battleships, aircraft carriers, destroyers, and cruisers, most of which played pivotal roles in World War II events. Many ships that data was recovered from were present at Pearl Harbor during the attack by Japanese bombers on 7 December 1941, although all ships listed in the study saw action in the Pacific at some point during the war. USS Pennsylvania was hit when Pearl Harbour was attacked by the Japanese air force in December 1941. One bomb fell on the battleship and caused the deaths of nine servicemen, but it remained in service. The USS Tennessee was bombed twice in December 1941, resulting in the death of five servicemen. It returned to service in February 1942.

Future climate studies

Observations from naval vessels were the primary sources of marine observations for the World War II period but many records were destroyed as an act of war, or simply forgotten due to the length of time they were considered classified.

The recovered dataset reveals how wartime necessitated changes in observation practices. For example, more observations were taken during daytime than nighttime to reduce exposure to the enemy ships and avoid being detected. It is believed that changes such as this could have led to slightly warmer temperatures being recorded, meaning today's history books show a period of abnormal warmth in global datasets during World War II. The new data will help resolve this uncertainty.

Read more at Science Daily

Mature sperm lack intact mitochondrial DNA

New research provides insight about the bedrock scientific principle that mitochondrial DNA -- the distinct genetic code embedded in the organelle that serves as the powerplant of every cell in the body -- is exclusively passed down by the mother.

The study, a collaboration among Oregon Health & Science University and other institutions, published today in the journal Nature Genetics.

Scientists have long recognized the fact that mitochondrial DNA, or mtDNA, comes exclusively from egg cells in humans, meaning only the mother contributes the genetic code carried by thousands of mitochondria necessary for energy production in every cell in the body.

Previously, it was believed that paternal mtDNA was eliminated soon after a sperm fuses with an oocyte, or developing egg, during fertilization, possibly through an immune-like search-and-destroy response.

However, the study found that while mature sperm do carry a small number of mitochondria, they lack intact mtDNA.

"We found that each sperm cell does bring 100 or so mitochondria as organelles when it fertilizes an egg, but there is no mtDNA in them," said co-author Shoukhrat Mitalipov, Ph.D., director of the Center for Embryonic Cell and Gene Therapy at OHSU.

Researchers found that sperm cells are not only devoid of intact mtDNA, but they also lacked a protein essential for mtDNA maintenance, known as mitochondrial transcription factor A, or TFAM.

Scientists aren't sure why sperm are not allowed to contribute mtDNA, but Mitalipov theorizes that it may relate to the fact that a sperm uses a lot of mitochondrial energy in its biological impetus to fertilize an egg. It would thus accumulate mutations in mtDNA. The developing eggs known as oocytes, by contrast, draw energy primarily from surrounding cells, not from their own mitochondria, so maintain relatively pristine mtDNA.

"Eggs pass on really good mtDNA at least partly because they don't use mitochondria as a source of energy," Mitalipov said.

The 100 or so organelles in sperm are swamped by hundreds of thousands of mitochondria embedded in each egg cell -- each carrying the 37 genes in mitochondrial DNA. The contribution of only maternal mtDNA is believed to confer an evolutionary advantage by limiting the risk of accumulations of mtDNA mutations that cause disease in offspring.

Mitochondria control respiration and energy production within every cell of the body, so mutations in mtDNA can cause a range of potentially fatal disorders affecting organs with high-energy demands, such as the heart, muscle and brain.

To help mothers prevent passing on known mtDNA disorders to their children, Mitalipov pioneered a method called mitochondrial replacement therapy to replace mutant mtDNA through in vitro fertilization using healthy mtDNA from donor eggs.

Congress has prevented the Food and Drug Administration from overseeing clinical trials using the procedure in the U.S., so clinical trials are instead being conducted overseas, including clinical trials in the United Kingdom to prevent disease and in Greece to treat infertility.

Read more at Science Daily

New findings suggest Moon may have less water than previously thought

A team including Southwest Research Institute's Dr. Raluca Rufu recently calculated that most of the Moon's permanently shadowed regions (PSRs) are at most around 3.4 billion years old and can contain relatively young deposits of water ice. Water resources are considered key for sustainable exploration of the Moon and beyond, but these findings suggest that current estimates for cold-trapped ices are too high.

The current tilt of the Moon's spin axis combined with its orbital inclination -- the angle to Earth's orbital plane -- and the Sun's low angle creates permanent shadows at its poles. PSRs are some of the coldest spots in the solar system, allowing them to trap volatile chemicals, including water ice, that would immediately transform directly from a solid to a gas in the harsh, airless sunshine that falls in most other places on the Moon.

"We think the Earth-Moon system formed following a giant impact between early Earth and another protoplanet," said Rufu, a Sagan Fellow who is the second author of a Science Advances paper. "The Moon formed from the impact-generated debris disk, migrating away from Earth over time. Around 4.1 billion years ago the Moon experienced a major spin axis reorientation when its tilt reached high angles before it damped down to the configuration we see today. As the axial tilt decreased, PSRs appeared at the poles and grew over time."

The team used AstroGeo22, a new Earth-Moon evolution simulation tool, to calculate the Moon's axial tilt over time. Together with surface height measurements from the Lunar Orbital Altimeter Laser data (LOLA), the team estimated the evolution of the shadowed areas over time.

"The time evolution of the Moon-Earth distance remained an unsolved problem for half a century," Rufu said. "However, these new geological proxies for the history of the Earth-Moon system allow us to calculate the Moon's axial tilt and the extent of PSRs over time."

In 2009, NASA crashed the two-ton Atlas Centaur rocket body, part of the Lunar Crater Observation and Sensing Satellite (LCROSS), near the south pole of the Moon. It struck the floor of Cabeus crater, creating a plume of debris examined for the presence of water and other chemicals in the lunar regolith. A shepherding satellite travelling four minutes behind the Centaur and several Earth-orbiting satellites, including the Hubble Space Telescope, monitored the impact.

"Our work suggests that Cabeus crater became a PSR less than a billion years ago. The various volatiles detected in the plume created by LCROSS indicate that ice-trapping continued into relatively recent times," said Norbert Schörghofer, the lead author of this paper from the Planetary Science Institute. "Impacts and outgassing are potential sources of water but peaked early in lunar history, when the present-day PSRs did not yet exist. The age of PSRs largely determines the amount of water ice that could be trapped in the lunar polar regions. Information about the abundance of water ice in PSRs is particularly important in planning for upcoming crewed and uncrewed missions to the Moon searching for water."

Read more at Science Daily

Brilliant galaxies of early universe

Rochester Institute of Technology scientists have once again used data from the James Webb Space Telescope (JWST) as part of the Cosmic Evolution Early Release Science (CEERS) Survey to change the way we think about the universe and its distant galaxies.

Jeyhan Kartaltepe, associate professor in the School of Physics and Astronomy, and Rebecca Larson, postdoctoral research associate, co-authored a paper, "Confirmation and refutation of very luminous galaxies in the early Universe," published in Nature confirming very bright galaxies in the early universe, while also disproving the identification of what would have been the most distant galaxy ever found.

Kartaltepe and Larson, along with co-authors from around the world, studied the redshift (or displacement of the spectrum of an object toward longer, red wavelengths) of several specific galaxies to see how much the light shifted, which indicates how far away the galaxies are. The CEERS team focused on Maisie's Galaxy, which was theorized to have a redshift of z ≈ 11.5, while a team in Scotland researched a nearby galaxy that they believed could have a redshift of z ≈ 16, far larger than any ever found before.

To examine further, the two teams partnered on a proposal to receive follow-up spectroscopy. When the new data came in, the teams were able to precisely measure the redshifts of both of these candidates, along with a few others.

"Spectra are how you really confirm what a galaxy's redshift is," explained Kartaltepe. "For these two galaxies, the answer was very clear -- the spectra look completely different. We confirmed that Maisie's Galaxy is at the high redshift we thought it was."

The group also found that because of a coincidence that mimicked the colors of a high redshift galaxy, the other galaxy is not at a redshift of z ≈ 16, but at a redshift of z ≈ 4.9. Both the initial and follow-up data from JWST turned the theories into discoveries.

"Not only did JWST find these galaxies we didn't know about before, but then it confirmed the redshift for them," said Larson. "This paper in particular speaks to the power of not only JWST finding galaxies in the really early universe but also confirming and characterizing them."

The research and the paper would not have been possible without dedicated collaboration between the CEERS team and the team in Scotland. Instead of working separately on their individual galaxies and submitting separate proposals, the partnership allowed for the follow-up spectroscopy to be accepted, and the subsequent analysis to be conducted efficiently, leading to new information about the universe.

When researching the data from JWST, scientists aim to find the highest redshift galaxies, or the most distant galaxies. Finding galaxies in the very early universe was one of the goals for the JWST. These and other early discoveries have proven the success of the telescope, even this early in its existence.

Read more at Science Daily

Polar experiments reveal seasonal cycle in Antarctic sea ice algae

In the frigid waters surrounding Antarctica, an unusual seasonal cycle occurs. During winter, from March to October, the sun barely rises. As seawater freezes it rejects salts, creating pockets of extra-salty brine where microbes live in winter. In summer, the sea ice melts under constant daylight, producing warmer, fresher water at the surface.

This remote ecosystem is home to much of the Southern Ocean's photosynthetic life. A new University of Washington study provides the first measurements of how sea-ice algae and other single-celled life adjust to these seasonal rhythms, offering clues to what might happen as this environment shifts under climate change.

The study, published Sept. 15 in the International Society for Microbial Ecology's ISME Journal, contains some of the first measurements of how sea-ice microbes respond to changing conditions.

"We know very little about how sea-ice microbes respond to changes in salinity and temperature," said lead author Hannah Dawson, a UW postdoctoral researcher who did the work while pursuing her doctorate in oceanography at the UW. "And until now we knew almost nothing about the molecules they produce and use in chemical reactions to stay alive, which are important for supporting higher organisms in the ecosystem as well as for climate impacts, like carbon storage and cloud formation."

The polar oceans play an important role in global ocean currents and in supporting marine ecosystems. Microbes form the base of the food web, supporting larger life forms.

"Polar oceans make up a significant portion of the world's oceans, and these are very productive waters," said senior author Jodi Young, a UW assistant professor of oceanography. "These waters support big swarms of krill, the whales that come to feed on those krill, and either polar bears or penguins. And the start of that whole ecosystem are these single-celled microscopic algae. We just know so little about them."

The tiny organisms are also important for the climate, since they quietly perform photosynthesis and soak up carbon from the atmosphere. Polar algae are especially good at producing sulfur-containing molecules that give beaches their distinctive smell and, when lofted into the air in sea spray, promote formation of clouds that can reduce penetration of solar rays.

Antarctic sea ice, though long stable, is at an all-time record low this year.

In other oceans, satellite instruments can capture dramatic seasonal phytoplankton blooms from space -- but that isn't possible for microbes hidden under sea ice. And Antarctic waters are particularly challenging to visit, leaving researchers with almost no measurements in winter.

In late 2018, Dawson and co-author Susan Rundell traveled to Palmer Station, a U.S. research station on the West Antarctic Peninsula. They used a small boat to sample seawater and sea ice at the same nearby sites every three days.

Back on shore, the two graduate students performed 10-day experiments in tanks to see which microbes grew as temperature and salinity were adjusted to mimic sea-ice formation and melt. They also shipped samples back to Seattle for more complex measurements of the samples' genetics and metabolites, the small organic molecules produced by the cell.

Results revealed how single-celled algae deal with their fluctuating environments. As temperatures drop, the cells produce cryoprotectants, similar to antifreeze, to prevent their cellular fluid from crystallizing. Many of the most common cryoprotectant molecules were the same across different microbial lifeforms.

As salinity changes, to avoid either bursting in freshening waters or becoming desiccated like raisins in salty conditions, the cells change the concentration of salt-like organic molecules. Many such molecules serve a dual role as cryoprotectants, to balance conditions inside and outside the cell to maintain water balance.

The results show that under short-term temperature and salinity changes, community structure in each sample remained stable while adjusting the production of protective molecules. Different microbe species showed consistent responses to changing conditions. This should simplify modeling future responses to climate change, Young said.

Results also hint that the production of omega-3 fatty acids may decline in lower-salinity environments. This would be bad news for consumers of krill oil supplements, and for the marine ecosystem that relies on those algae-derived nutrients. Future research now underway by the UW group aims to confirm that result -- especially with the prospect of increasing freshwater input from melting sea ice and glaciers.

"We're interested in how these sea-ice algae contend with changes in temperature, salinity and light under normal conditions," Dawson said. "But then we also have climate change, which is completely remodeling the landscape in terms of when sea ice is forming, how much sea ice forms, how long it stays before it melts, as well as the quantity of freshwater input from glaciers. So we're both trying to capture what's happening now, and also asking how that can inform what might happen in the future."

Read more at Science Daily

Brain-altering parasite turns ants into zombies at dawn and dusk

It takes over the brains of ants, causing them to cling to the tops of blades of grass where they can be eaten by cattle and deer. The common liver fluke has an exceptional life cycle as it moves through snails, ants and grass-grazing herbivores. And now, researchers from the University of Copenhagen know a bit more about the workings of this tiny parasite. The new knowledge adds to our understanding of parasites, which could be the most widespread life form on Earth.

Imagine coming-to, jaws gripping the top of a swaying blade of grass, unaware of how you got there. That's the reality for ants infected with the lancet liver fluke, a tiny parasitic flatworm. Liver flukes have a complicated, almost insanely conceived life cycle, which begins with the hijacking of the ant's brain. The unsuspecting ant climbs up and clamps its powerful jaws onto the top of a blade of grass, making it more likely to be eaten by grazers such as cattle and deer.

Researchers from the University of Copenhagen's Department of Plant and Environmental Sciences have discovered that the parasite's ability to control the ant is even more cunning than previously believed. Impressively, the parasite can even get the ant to crawl back down the blade of grass when it gets too hot.

"Getting the ants high up in the grass for when cattle or deer graze during the cool morning and evening hours, and then down again to avoid the sun's deadly rays, is quite smart. Our discovery reveals a parasite that is more sophisticated than we originally believed it to be," explains Associate Professor Brian Lund Fredensborg, who conducted the study together with former graduate student Simone Nordstrand Gasque, now a PhD student at Wageningen University in the Netherlands.

Zombie "on/off switch"

The researchers tagged several hundred infected ants in the Bidstrup Forests near Roskilde, Denmark.

"It took some dexterity to glue colors and numbers onto the rear segments of the ants, but it allowed us to keep track of them for longer periods of time," says Brian Lund Fredensborg.

They then observed the infected ants' behavior in relation to light, humidity, time of day and temperature. It was clear that temperature had an effect on ant behavior. When the temperature was low, the ants were more likely to be attached to the top of a blade of grass. When the temperature rose, the ants relinquished the grass and crawled back down.

"We found a clear correlation between temperature and ant behavior. We joked about having found the ants' zombie switch," says Brian Lund Fredensborg.

Trojan horse

Once the liver fluke infects the ant, several hundred parasites invade the ant's body. But only one makes its way to the brain, where it can influence the ant's behavior. The rest of the liver flukes conceal themselves in the ant's abdomen.

"Here, there can be hundreds of liver flukes waiting for the ant to get them into their next host. They are wrapped in a capsule which protects them from the consequent host's stomach acid, while the liver fluke that took control of the ant, dies. You could say that it sacrifices itself for the others," explains Brian Lund Fredensborg.

Animals infected with many liver flukes can suffer liver damage as the parasite moves around the host's liver and bile ducts.

Nature's biggest influencer

Brian Lund Fredensborg notes that there are many other examples of parasites that alter animal behavior. As such, parasites that hijack their host'sbehavior have a greater hand in the food chain than many might think. According to Fredensborg, this new study sheds light on an extremely underrated group of creatures.

"Historically, parasites have never really been focused on that much, despite there being scientific sources which say that parasitism is the most widespread life form. This is in part due to the fact that parasites are quite difficult to study. Nevertheless, the hidden world of parasites forms a significant part of biodiversity, and by changing the host's behavior, they can help determine who eats what in nature. That's why they're important for us to understand," he says.

The tiny liver fluke is widespread in Denmark, and other temperate regions worldwide. The researcher and his colleagues will continue to investigate the parasite, and excactly how it takes over an ant's brain.

Read more at Science Daily

The universe caught suppressing cosmic structure growth

As the universe evolves, scientists expect large cosmic structures to grow at a certain rate: dense regions such as galaxy clusters would grow denser, while the void of space would grow emptier.

But University of Michigan researchers have discovered that the rate at which these large structures grow is slower than predicted by Einstein's Theory of General Relativity.

They also showed that as dark energy accelerates the universe's global expansion, the suppression of the cosmic structure growth that the researchers see in their data is even more prominent than what the theory predicts. Their results are published in Physical Review Letters.

Galaxies are threaded throughout our universe like a giant cosmic spider web. Their distribution is not random. Instead, they tend to cluster together. In fact, the whole cosmic web started out as tiny clumps of matter in the early universe, which gradually grew into individual galaxies, and eventually galaxy clusters and filaments.

"Throughout the cosmic time, an initially small clump of mass attracts and accumulates more and more matter from its local region through gravitational interaction. As the region becomes denser and denser, it eventually collapses under its own gravity," said Minh Nguyen, lead author of the study and postdoctoral research fellow in the U-M Department of Physics.

"So as they collapse, the clumps grow denser. That is what we mean by growth. It's like a fabric loom where one-, two- and three-dimensional collapses look like a sheet, a filament and a node. The reality is a mixture of all three cases, and you have galaxies living along the filaments while galaxy clusters -- groups of thousands of galaxies, the most massive objects in our universe bounded by gravity -- sit at the nodes."

The universe is not only made of matter. It also likely contains a mysterious component called dark energy. Dark energy accelerates the expansion of the universe on a global scale. As dark energy accelerates the expansion of the universe, it has the opposite effect on large structures.

"If gravity acts like an amplifier enhancing matter perturbations to grow into large-scale structure, then dark energy acts like an attenuator damping these perturbations and slowing the growth of structure," Nguyen said. "By examining how cosmic structure has been clustering and growing, we can try to understand the nature of gravity and dark energy."

Nguyen, U-M physics professor Dragan Huterer and U-M graduate student Yuewei Wen examined the temporal growth of large-scale structure throughout cosmic time using several cosmological probes.

First, the team used what's called the cosmic microwave background. The cosmic microwave background, or CMB, is composed of photons emitted just after the Big Bang. These photons provide a snapshot of the very early universe. As the photons travel to our telescopes, their path can become distorted, or gravitationally lensed, by large-scale structure along the way. Examining them, the researchers can infer how structure and matter between us and the cosmic microwave background are distributed.

Nguyen and colleagues took advantage of a similar phenomenon with weak gravitational lensing of galaxy shapes. Light from background galaxies is distorted through gravitational interactions with foreground matter and galaxies. The cosmologists then decode these distortions to determine how the intervening matter is distributed.

"Crucially, as the CMB and background galaxies are located at different distances from us and our telescopes, galaxy weak gravitational lensing typically probes matter distributions at a later time compared to what is probed by CMB weak gravitational lensing," Nguyen said.

To track the growth of structure to an even later time, the researchers further used motions of galaxies in the local universe. As galaxies fall into the gravity wells of the underlying cosmic structures, their motions directly track structure growth.

"The difference in these growth rates that we have potentially discovered becomes more prominent as we approach the present day," Nguyen said. "These different probes individually and collectively indicate a growth suppression. Either we are missing some systematic errors in each of these probes, or we are missing some new, late-time physics in our standard model."

The findings potentially address the so-called S8 tension in cosmology. S8 is a parameter that describes the growth of structure. The tension arises when scientists use two different methods to determine the value of S8, and they do not agree. The first method, using photons from the cosmic microwave background, indicates a higher S8 value than the value inferred from galaxy weak gravitational lensing and galaxy clustering measurements.

Neither of these probes measures the growth of structure today. Instead, they probe structure at earlier times, then extrapolate those measurements to present time, assuming the standard model. Cosmic microwave background probes structure in the early universe, while galaxy weak gravitational lensing and clustering probe structure in the late universe.

The researchers' findings of a late-time suppression of growth would bring the two S8 values into perfect agreement, according to Nguyen.

"We were surprised with the high statistical significance of the anomalous growth suppression," Huterer said. "Honestly, I feel like the universe is trying to tell us something. It is now the job of us cosmologists to interpret these findings.

Read more at Science Daily

Genetically modified bacteria break down plastics in saltwater

Researchers have genetically engineered a marine microorganism to break down plastic in salt water. Specifically, the modified organism can break down polyethylene terephthalate (PET), a plastic used in everything from water bottles to clothing that is a significant contributor to microplastic pollution in oceans.

"This is exciting because we need to address plastic pollution in marine environments," says Nathan Crook, corresponding author of a paper on the work and an assistant professor of chemical and biomolecular engineering at North Carolina State University.

"One option is to pull the plastic out of the water and put it in a landfill, but that poses challenges of its own. It would be better if we could break these plastics down into products that can be re-used. For that to work, you need an inexpensive way to break the plastic down. Our work here is a big step in that direction."

To address this challenge, the researchers worked with two species of bacteria. The first bacterium, Vibrio natriegens, thrives in saltwater and is remarkable -- in part -- because it reproduces very quickly. The second bacterium, Ideonella sakaiensis, is remarkable because it produces enzymes that allow it to break down PET and eat it.

The researchers took the DNA from I. sakaiensis that is responsible for producing the enzymes that break down plastic, and incorporated that genetic sequence into a plasmid. Plasmids are genetic sequences that can replicate in a cell, independent of the cell's own chromosome. In other words, you can sneak a plasmid into a foreign cell, and that cell will carry out the instructions in the plasmid's DNA. And that's exactly what the researchers did here.

By introducing the plasmid containing the I. sakaiensis genes into V. natriegens bacteria, the researchers were able to get V. natriegens to produce the desired enzymes on the surface of their cells. The researchers then demonstrated that V. natriegens was able to break down PET in a saltwater environment at room temperature.

"This is scientifically exciting because this is the first time anyone has reported successfully getting V. natriegens to express foreign enzymes on the surface of its cells," Crook says.

"From a practical standpoint, this is also the first genetically engineered organism that we know of that is capable of breaking down PET microplastics in saltwater," says Tianyu Li, first author of the paper and a Ph.D. student at NC State. "That's important, because it is not economically feasible to remove plastics from the ocean and rinse high concentration salts off before beginning any processes related to breaking the plastic down."

"However, while this is an important first step, there are still three significant hurdles," Crook says. "First, we'd like to incorporate the DNA from I. sakaiensis directly into the genome of V. natriegens, which would make the production of plastic-degrading enzymes a more stable feature of the modified organisms. Second, we need to further modify V. natriegens so that it is capable of feeding on the byproducts it produces when it breaks down the PET. Lastly, we need to modify the V. natriegens to produce a desirable end product from the PET -- such as a molecule that is a useful feedstock for the chemical industry.

"Honestly, that third challenge is the easiest of the three," says Crook. "Breaking down the PET in saltwater was the most challenging part.

"We are also open to talking with industry groups to learn more about which molecules would be most desirable for us to engineer the V. natriegens into producing," Crook says. "Given the range of molecules we can induce the bacteria to produce, and the potentially vast scale of production, which molecules could industry provide a market for?"

Read more at Science Daily

Making hydrogen from waste plastic could pay for itself

Hydrogen is viewed as a promising alternative to fossil fuel, but the methods used to make it either generate too much carbon dioxide or are too expensive. Rice University researchers have found a way to harvest hydrogen from plastic waste using a low-emissions method that could more than pay for itself.

"In this work, we converted waste plastics -- including mixed waste plastics that don't have to be sorted by type or washed -- into high-yield hydrogen gas and high-value graphene," said Kevin Wyss, a Rice doctoral alumnus and lead author on a study published in Advanced Materials. "If the produced graphene is sold at only 5% of current market value -- a 95% off sale! -- clean hydrogen could be produced for free."

By comparison, 'green' hydrogen -- produced using renewable energy sources to split water into its two component elements -- costs roughly $5 for just over two pounds. Though cheaper, most of the nearly 100 million tons of hydrogen used globally in 2022 was derived from fossil fuels, its production generating roughly 12 tons of carbon dioxide per ton of hydrogen.

"The main form of hydrogen used today is 'gray' hydrogen, which is produced through steam-methane reforming, a method that generates a lot of carbon dioxide" said James Tour, Rice's T. T. and W. F. Chao Professor of Chemistry and a professor of materials science and nanoengineering. "Demand for hydrogen will likely skyrocket over the next few decades, so we can't keep making it the same way we have up until now if we're serious about reaching net zero emissions by 2050."

The researchers exposed plastic waste samples to rapid flash Joule heating for about four seconds, bringing their temperature up to 3100 degrees Kelvin. The process vaporizes the hydrogen present in plastics, leaving behind graphene -- an extremely light, durable material made up of a single layer of carbon atoms.

"When we first discovered flash Joule heating and applied it to upcycle waste plastic into graphene, we observed a lot of volatile gases being produced and shooting out of the reactor," Wyss said. "We wondered what they were, suspecting a mix of small hydrocarbons and hydrogen, but lacked the instrumentation to study their exact composition."

Using funding from the United States Army Corps of Engineers, the Tour lab acquired the necessary equipment to characterize the vaporized contents.

"We know that polyethylene, for example, is made of 86% carbon and 14% hydrogen, and we demonstrated that we are able to recover up to 68% of that atomic hydrogen as gas with a 94% purity," Wyss said. "Developing the methods and expertise to characterize and quantify all the gases, including hydrogen, produced by this method was a difficult but rewarding process for me.

"I am glad that techniques I learned and used in this work -- specifically life-cycle assessment and gas chromatography -- can be applied to other projects in our group. I hope that this work will allow for the production of clean hydrogen from waste plastics, possibly solving major environmental problems like plastic pollution and the greenhouse gas-intensive production of hydrogen by steam methane reforming."

Read more at Science Daily