Understanding of invisible but mighty particles in Earth's radiation belts

Tiny charged electrons and protons which can damage satellites and alter the ozone have revealed some of their mysteries to University of Otago scientists.

In a study, published in Geophysical Research Letters, the group looked at charged particles interacting with a type of radio wave called 'EMIC' -- a wave generated in Earth's radiation belts (invisible rings of charged particles orbiting the Earth).

Lead author Dr Aaron Hendry, of the Department of Physics, says it is important to understand how these waves affect the belts -- which are filled with expensive and important satellites -- and Earth's climate.

"Much like the Earth's atmosphere, the Earth's magnetosphere -- the region around the Earth where our magnetic field is stronger than the Sun's -- sometimes experiences strong 'storms', or periods of high activity. These storms can cause significant changes to the number of particles in the radiation belts and can accelerate some of them to very high speeds, making them a danger to our satellites. Knowing how many of these particles there are, as well as how fast they're moving, is very important to us, so that we can make sure our satellites keep working.

"Activity within the radiation belts can sometimes cause the orbits of these particles to change. If these changes bring the particles low enough to reach the Earth's upper atmosphere, they can hit the dense air, lose all of their energy and fall out of orbit.

"EMIC waves are known to be able to cause these changes and drive the loss of particles from the radiation belts. As well as causing beautiful light displays that we call aurora, this rain of particles can also cause complex chemical changes to the upper atmosphere that can in turn cause small, but important, changes the amount of ozone present in atmosphere.

"Although these changes are small, understanding them is very important to properly understanding how the chemistry of the atmosphere works, how it is changing over time, and the impact it is having on the climate," Dr Hendry says.

For their latest study, the researchers used data from GPS satellites to look at how many electrons EMIC waves can knock into the Earth's atmosphere.

A general rule in the radiation belts is that at slower speeds, you have many more electrons. So, if the minimum speed of the EMIC wave interaction is lowered, there are a lot more electrons around to interact with waves.

By looking at data from satellites that monitor how many electrons there are in the radiation belts and how fast they're going, the researchers have been able to show that you can see the number of electrons in the radiation belts go down significantly when EMIC waves are around.

"Excitingly, we have also seen changes in the number of electrons at speeds significantly lower than the current 'accepted' minimum speed. This means that EMIC can affect much larger numbers of electrons than we previously thought possible. Clearly, we need to rethink how we're modelling this interaction, and the impact it has on the radiation belts. There are a lot of electrons in the radiation belts, so being able to knock enough of them into the atmosphere to make a noticeable change is quite remarkable.

"This has shown that we need to take these EMIC waves into account when we're thinking about how the radiation belts change over time, and how these changes in the radiation belt affect the climate on Earth."

Dr Hendry says the impact of EMIC-driven electrons on atmospheric chemistry is not currently being included by major climate models, which try to predict how the Earth's climate will change over time, so making sure this process is understood and included in these models is very important.

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New tool activates deep brain neurons by combining ultrasound, genetics

Neurological disorders such as Parkinson's disease and epilepsy have had some treatment success with deep brain stimulation, but those require surgical device implantation. A multidisciplinary team at Washington University in St. Louis has developed a new brain stimulation technique using focused ultrasound that is able to turn specific types of neurons in the brain on and off and precisely control motor activity without surgical device implantation.

The team, led by Hong Chen, assistant professor of biomedical engineering in the McKelvey School of Engineering and of radiation oncology at the School of Medicine, is the first to provide direct evidence showing noninvasive, cell-type-specific activation of neurons in the brain of mammal by combining ultrasound-induced heating effect and genetics, which they have named sonothermogenetics. It is also the first work to show that the ultrasound- genetics combination can robustly control behavior by stimulating a specific target deep in the brain.

Results of the three years of research, which was funded in part by the National Institutes of Health's BRAIN Initiative, were published online in Brain Stimulation May 11, 2021.

The senior research team included experts from both the McKelvey School of Engineering and the School of Medicine, including Jianmin Cui, professor of biomedical engineering; Joseph P. Culver, professor of radiology, of physics and of biomedical engineering; Mark J. Miller, associate professor of medicine in the Division of Infectious Diseases in the Department of Medicine; and Michael Bruchas, formerly of Washington University, now professor of anesthesiology and pharmacology at the University of Washington.

"Our work provided evidence that sonothermogenetics evokes behavioral responses in freely moving mice while targeting a deep brain site," Chen said. "Sonothermogenetics has the potential to transform our approaches for neuroscience research and uncover new methods to understand and treat human brain disorders."

Using a mouse model, Chen and the team delivered a viral construct containing TRPV1 ion channels to genetically-selected neurons. Then, they delivered small burst of heat via low-intensity focused ultrasound to the select neurons in the brain via a wearable device. The heat, only a few degrees warmer than body temperature, activated the TRPV1 ion channel, which acted as a switch to turn the neurons on or off.

"We can move the ultrasound device worn on the head of free-moving mice around to target different locations in the whole brain," said Yaoheng Yang, first author of the paper and a graduate student in biomedical engineering. "Because it is noninvasive, this technique has the potential to be scaled up to large animals and potentially humans in the future."

The work builds on research conducted in Cui's lab that was published in Scientific Reports in 2016. Cui and his team found for the first time that ultrasound alone can influence ion channel activity and could lead to new and noninvasive ways to control the activity of specific cells. In their work, they found that focused ultrasound modulated the currents flowing through the ion channels on average by up to 23%, depending on channel and stimulus intensity. Following this work, researchers found close to 10 ion channels with this capability, but all of them are mechanosensitive, not thermosensitive.

The work also builds on the concept of optogenetics, the combination of the targeted expression of light-sensitive ion channels and the precise delivery of light to stimulate neurons deep in the brain. While optogenetics has increased discovery of new neural circuits, it is limited in penetration depth due to light scattering and requires surgical implantation of optical fibers.

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Astronomer reveals never-before-seen detail of the center of our galaxy

New research by University of Massachusetts Amherst astronomer Daniel Wang reveals, with unprecedented clarity, details of violent phenomena in the center of our galaxy. The images, published recently in Monthly Notices of the Royal Astronomical Society, document an X-ray thread, G0.17-0.41, which hints at a previously unknown interstellar mechanism that may govern the energy flow and potentially the evolution of the Milky Way.

"The galaxy is like an ecosystem," says Wang, a professor in UMass Amherst's astronomy department, whose findings are a result of more than two decades of research. "We know the centers of galaxies are where the action is and play an enormous role in their evolution." And yet, whatever has happened in the center of our own galaxy is hard to study, despite its relative proximity to Earth, because, as Wang explains, it is obscured by a dense fog of gas and dust. Researchers simply can't see the center, even with an instrument as powerful as the famous Hubble Space Telescope. Wang, however, has used a different telescope, NASA's Chandra X-Ray Observatory, which "sees" X-rays, rather than the rays of visible light that we perceive with our own eyes. These X-rays are capable of penetrating the obscuring fog -- and the results are stunning.

Wang's findings, which were supported by NASA, give the clearest picture yet of a pair of X-ray-emitting plumes that are emerging from the region near the massive black hole lying at the center of our galaxy. Even more intriguing is the discovery of an X-ray thread called G0.17-0.41, located near the southern plume. "This thread reveals a new phenomenon," says Wang. "This is evidence of an ongoing magnetic field reconnection event." The thread, writes Wang, probably represents "only the tip of the reconnection iceberg."

A magnetic field reconnection event is what happens when two opposing magnetic fields are forced together and combine with one another, releasing an enormous amount of energy. "It's a violent process," says Wang, and is known to be responsible for such well-known phenomena as solar flares, which produce space weather powerful enough to disrupt power grids and communications systems here on Earth. They also produce the spectacular Northern Lights. Scientists now think that magnetic reconnection also occurs in interstellar space and tends to take place at the outer boundaries of the expanding plumes driven out of our galaxy's center.

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Gravitational wave search no hum drum hunt

The hunt for the never before heard "hum" of gravitational waves caused by mysterious neutron stars has just got a lot easier, thanks to an international team of researchers.

Gravitational waves have only been detected from black holes and neutron stars colliding, major cosmic events that cause huge bursts that ripple through space and time.

The research team, involving scientists from the LIGO Scientific Collaboration (LSC), Virgo Collaboration and the Centre for Gravitational Astrophysics (CGA) at The Australian National University (ANU), are now turning their eagle eye to spinning neutron stars to detect the waves.

Unlike the massive bursts caused by black holes or neutron stars colliding, the researchers say single spinning neutron stars have a bulge or "mountain" only a few millimetres high, which may produce a steady constant stream or "hum" of gravitational waves.

The researchers are using their methods that detected gravitational waves for the first time in 2015 to capture this steady soundtrack of the stars over the thunderous noise of massive black holes and dense neutron stars colliding.

They say it's like trying to capture the squeak of a mouse in the middle of a stampeding herd of elephants.

If successful, it would be the first detection of a gravitational wave event that didn't involve the collision of massive objects like black holes or neutron stars.

ANU Distinguished Professor, Susan Scott from the ANU Research School of Physics, said the collision of dense neutron stars sent a "burst" of gravitational waves rippling through the Universe.

"Neutron stars are mystery objects," Professor Scott, also a Chief Investigator with the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), said.

"We don't really understand what they are made up of, or how many types of them exist. But what we do know is that when they collide, they send incredible bursts of gravitational waves across the Universe.

"In contrast, the gentle hum of a spinning neutron star is very faint and almost impossible to detect."

Three new papers have just been published by the LSC and Virgo collaborations detailing the most sensitive searches to date for the faint hum of gravitational waves from spinning neutron stars.

Their work offers a "map to the potential El Dorado of gravitational waves."

"One of our searches targets young supernova remnants. These neutron stars, recently born, are more deformed, and should emit a stronger stream of gravitational waves," Dr Lilli Sun, from CGA and an Associate Investigator with OzGrav, said.

As these searches become more and more sensitive they are providing more detail than ever of the possible shape and make-up of neutron stars.

"If we can manage to detect this hum, we'll be able to look deep into the heart of a neutron star and unlock its secrets," Dr Karl Wette, a postdoctoral researcher with OzGrav and the CGA, said.

Professor Scott, who is also the leader of the General Relativity Theory and Data Analysis Group at ANU, added: "Neutron stars represent the densest form of matter in the Universe before a black hole will form."

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Exoskeleton-assisted walking may improve bowel function in people with spinal cord injury

A team of researchers has shown that physical intervention plans that included exoskeleton-assisted walking helped people with spinal cord injury evacuate more efficiently and improved the consistency of their stool.

The authors of the new article in Journal of Clinical Medicine are Peter H. Gorman, MD, of the University of Maryland School of Medicine, Gail F. Forrest, PhD, of Kessler Foundation's Tim and Caroline Reynolds Center for Spinal Stimulation, Dr. William Scott, of VA Maryland Healthcare System, Pierre K. Asselin, MS, Stephen Kornfeld, MD, Eunkyoung Hong, PhD, and Ann M. Spungen, EdD, of the James J. Peters VA Medical Center.

Bowel dysfunction, a common experience after spinal cord injury, can lead to chronic constipation and incontinence, causing discomfort and frustration. In one survey, more than a third of men with spinal cord injury reported that bowel and bladder dysfunction had the most significant effect on their lives post-injury. Unfortunately, these issues are not easily managed.

Rehabilitation professionals have traditionally managed bowel dysfunction using approaches that target the gastrointestinal system or require manual intervention, but some newer research suggests that physical activity and upright posture may enhance bowel motility. However, few studies have explored the possibility that exoskeletal-assisted walking -- in which a person with spinal cord injury wears a robotic suit, enabling them to stand and walk -- may be an effective addition to existing intervention plans.

In this study, the research team investigated whether exoskeletal-assisted walking improved bowel function in people with chronic spinal cord injury. They performed a three-center, randomized, controlled, crossover clinical trial in which 50 participants completed 36 sessions of exoskeletal-assisted walking. The researchers evaluated bowel function as a secondary outcome in 49 participants. Bowel function was measured via a 10-question bowel function survey, the Bristol Stool Form Scale, and the Spinal Cord Injury Quality of Life Bowel Management Difficulties instrument.

Results showed that the exoskeletal-assisted walking program provided some improvement in bowel function when compared to a control group. "We saw a notable reduction in bowel evacuation time, with 24 percent of participants reporting an improved experience," said Dr. Forrest, co-author and associate director of the Center for Mobility and Rehabilitation Engineering Research at Kessler Foundation. "We also noted that participants' stools trended toward better consistency, supporting our hypothesis that this intervention may improve several measures of bowel function."

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Biologists construct a 'periodic table' for cell nuclei

One hundred fifty years ago, Dmitri Mendeleev created the periodic table, a system for classifying atoms based on the properties of their nuclei. This week, a team of biologists studying the tree of life has unveiled a new classification system for cell nuclei and discovered a method for transmuting one type of cell nucleus into another.

The study, which appears this week in the journal Science, emerged from several once-separate efforts. One of these centered on the DNA Zoo, an international consortium spanning dozens of institutions including Baylor College of Medicine, the National Science Foundation-supported Center for Theoretical Biological Physics (CTBP) at Rice University, the University of Western Australia and SeaWorld.

Scientists on the DNA Zoo team had been working together to classify how chromosomes, which can be several meters long, fold up to fit inside the nuclei of different species from across the tree of life.

"Whether we were looking at worms or urchins, sea squirts or coral, we kept seeing the same folding patterns coming up," said Dr. Olga Dudchenko, co-first author of the new study and a member of the Center for Genome Architecture at Baylor and CTBP.

Eventually, the team realized it was just seeing variants on two overall nuclear designs. "In some species, chromosomes are organized like the pages of a printed newspaper, with the outer margins on one side and the folded middle at the other," explained Dudchenko, who also is co-director of DNA Zoo. "And then in other species, each chromosome is crumpled into a little ball."

"So we had a puzzle," said Dr. Erez Lieberman Aiden, an associate professor of molecular and human genetics and Emeritus McNair Scholar at Baylor, co-director of the DNA Zoo and senior author on the new study. "The data implied that over the course of evolution, species can switch back and forth from one type to the other. We wondered: What is the controlling mechanism? Might it be possible to change one type of nucleus into another in the lab?" Aiden also is director of the Center for Genome Architecture and a senior investigator at CTBP.

Meanwhile, an independent team in the Netherlands had discovered something unexpected. "I was doing experiments on a protein called condensin II, which we knew plays a role in how cells divide," said Claire Hoencamp, co-first author of the study and a member of the laboratory of Dr. Benjamin Rowland at the Netherlands Cancer Institute. "But we observed the strangest thing: When we mutated the protein in human cells, the chromosomes would totally rearrange. It was baffling!"

The two teams met at a conference in the Austrian mountains, where Rowland presented his lab's latest work. They soon realized that Hoencamp had hit on a way to convert human cells from one nuclear type to another.

"When we looked at the genomes being studied at the DNA Zoo, we discovered that evolution had already done our experiment many, many times! When mutations in a species break condensin II, they usually flip the whole architecture of the nucleus," said Rowland, senior author on the study. "It's always a little disappointing to get scooped on an experiment, but evolution had a very long head start."

The team decided to work together to confirm condensin II's role. But then the COVID-19 pandemic struck, and much of the world shut down.

"Without access to our laboratories, we were left with only one way to establish what condensin II was doing," Hoencamp said. "We needed to create a computer program that could simulate the effects of condensin II on the chain of hundreds of millions of genetic letters that comprise each human chromosome."

The team turned to Dr. José Onuchic, the Harry C. and Olga K. Wiess Chair of Physics at Rice. "Our simulations showed that by destroying condensin II, you could make a human nucleus reorganize to resemble a fly nucleus," said Onuchic, co-director of CTBP, which includes collaborators at Rice, Baylor, Northeastern University and other institutions in Houston and Boston.

The simulations were performed by a team within Onuchic's lab at CTBP, led by postdoctoral fellow and co-first author Dr. Sumitabha Brahmachari, working with Dr. Vinicius Contessoto, a former postdoc at CTBP, and Dr. Michele Di Pierro, a CTBP senior investigator and currently an assistant professor at Northeastern University.

"We began with an incredibly broad survey of 2 billion years of nuclear evolution," Brahmachari said. "And we found that so much boils down to one simple mechanism, that we can simulate as well as recapitulate, on our own, in a test tube. It's an exciting step on the road to a new kind of genome engineering -- in 3D!"

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Dark matter map reveals hidden bridges between galaxies

A new map of dark matter in the local universe reveals several previously undiscovered filamentary structures connecting galaxies. The map, developed using machine learning by an international team including a Penn State astrophysicist, could enable studies about the nature of dark matter as well as about the history and future of our local universe.

Dark matter is an elusive substance that makes up 80% of the universe. It also provides the skeleton for what cosmologists call the cosmic web, the large-scale structure of the universe that, due to its gravitational influence, dictates the motion of galaxies and other cosmic material. However, the distribution of local dark matter is currently unknown because it cannot be measured directly. Researchers must instead infer its distribution based on its gravitational influence on other objects in the universe, like galaxies.

"Ironically, it's easier to study the distribution of dark matter much further away because it reflects the very distant past, which is much less complex," said Donghui Jeong, associate professor of astronomy and astrophysics at Penn State and a corresponding author of the study. "Over time, as the large-scale structure of the universe has grown, the complexity of the universe has increased, so it is inherently harder to make measurements about dark matter locally."

Previous attempts to map the cosmic web started with a model of the early universe and then simulated the evolution of the model over billions of years. However, this method is computationally intensive and so far has not been able to produce results detailed enough to see the local universe. In the new study, the researchers took a completely different approach, using machine learning to build a model that uses information about the distribution and motion of galaxies to predict the distribution of dark matter.

The researchers built and trained their model using a large set of galaxy simulations, called Illustris-TNG, which includes galaxies, gasses, other visible matter, as well as dark matter. The team specifically selected simulated galaxies comparable to those in the Milky Way and ultimately identified which properties of galaxies are needed to predict the dark matter distribution.

"When given certain information, the model can essentially fill in the gaps based on what it has looked at before," said Jeong. "The map from our models doesn't perfectly fit the simulation data, but we can still reconstruct very detailed structures. We found that including the motion of galaxies -- their radial peculiar velocities -- in addition to their distribution drastically enhanced the quality of the map and allowed us to see these details."

The research team then applied their model to real data from the local universe from the Cosmicflow-3 galaxy catalog. The catalog contains comprehensive data about the distribution and movement of more than 17 thousand galaxies in the vicinity of the Milky Way -- within 200 megaparsecs. The resulting map of the local cosmic web is published in a paper appearing online May 26 in the Astrophysical Journal.

The map successively reproduced known prominent structures in the local universe, including the "local sheet" -- a region of space containing the Milky Way, nearby galaxies in the "local group," and galaxies in the Virgo cluster -- and the "local void" -- a relatively empty region of space next to the local group. Additionally, it identified several new structures that require further investigation, including smaller filamentary structures that connect galaxies.

"Having a local map of the cosmic web opens up a new chapter of cosmological study," said Jeong. "We can study how the distribution of dark matter relates to other emission data, which will help us understand the nature of dark matter. And we can study these filamentary structures directly, these hidden bridges between galaxies."

For example, it has been suggested that the Milky Way and Andromeda galaxies may be slowly moving toward each other, but whether they may collide in many billions of years remains unclear. Studying the dark matter filaments connecting the two galaxies could provide important insights into their future.

"Because dark matter dominates the dynamics of the universe, it basically determines our fate," said Jeong. "So we can ask a computer to evolve the map for billions of years to see what will happen in the local universe. And we can evolve the model back in time to understand the history of our cosmic neighborhood."

The researchers believe they can improve the accuracy of their map by adding more galaxies. Planned astronomical surveys, for example using the James Web Space Telescope, could allow them to add faint or small galaxies that have yet to be observed and galaxies that are further away.

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Deep oceans dissolve the rocky shell of water-ice planets

 What is happening deep beneath the surface of ice planets? Is there liquid water, and if so, how does it interact with the planetary rocky "seafloor"? New experiments show that on water-ice planets between the size of our Earth and up to six times this size, water selectively leaches magnesium from typical rock minerals. The conditions with pressures of hundred thousand atmospheres and temperatures above one thousand degrees Celsius were recreated in a lab and mimicked planets similar, but smaller than Neptune and Uranus.

The mechanisms of water-rock interaction at the Earth's surface are well known, and the picture of the complex cycle of H2O in the deep interior of our and other terrestrial planets is constantly improving. However, we do not know what happens at the interface between hot, dense H2O and the deep rocky shell of water-ice planets at pressures and temperatures orders of magnitude higher than at the bottom of the deepest oceans on Earth. In the solar system Neptune and Uranus are classified as ice-giants; they have a thick external water-ice layer, which is underlain by a deep rocky layer, and it is still discussed whether the temperature at the interface is high enough to form liquid water.

An international research team lead by Taehyun Kim of the Yonsei University of Seoul, Korea, including scientists from the University of Arizona, from DESY, from Argonne National Laboratory, and Sergio Speziale of the GFZ German Research Centre for Geosciences, conducted a series of challenging experiments both at PETRA III (Hamburg) and the Advanced Photon Source (Argonne, U.S.A.) showing how water strongly leaches magnesium oxide (MgO) from certain minerals, i.e. ferropericlase (Mg,Fe)O and olivine (Mg,Fe)2SiO4 at pressures between 20 and 40 Gigapascal (GPa). This equals 200,000 to 400,000 times the atmospheric pressure on Earth and temperatures above 1500 K (? 1230 °C), conditions which are present at the interface between deep oceans and the rocky mantle in sub-Neptune class of water planets. Sergio Speziale says: "These findings open new scenarios for the thermal history of large icy planets such as Neptune and Uranus." The results of this study are published in the scientific journal Nature Astronomy.

Tiny pellets of either ferropericlase or olivine powder were loaded together with water in a tiny sample chamber (less than a millimetre in diameter) drilled in a metal foil and squeezed between two gem-quality diamonds culets using a diamond anvil cell (DAC). The samples were heated by shining an infrared laser through the diamond anvils. Synchrotron x-ray diffraction was used to determine minerals transformation and breakdown induced by reactions with water. A sudden decrease of diffraction signal from the starting minerals, and the appearance of new solid phases including brucite (magnesium hydroxide) were observed across full heating and quenching cycles. Sergio Speziale explains: "This demonstrated the onset of chemical reactions and the dissolution of the magnesium oxide component of both ferropericlase and olivine; the dissolution was strongest in a specific pressure-temperature range between 20 to 40 Gigapascal and 1250 to 2000 Kelvin." The details of the reaction process and the consequent chemical segregation of MgO from the residual phases, were confirmed by thorough Scanning Electron Microscopy (SEM) and X-ray spectroscopy of the recovered samples. "At these extreme pressures and temperatures the solubility of magnesium oxide in water reaches levels similar to that of salt at ambient conditions," Sergio Speziale says.

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Banning the sale of fossil-fuel cars benefits the climate when replaced by electric cars

If a ban were introduced on the sale of new petrol and diesel cars, and they were replaced by electric cars, the result would be a great reduction in carbon dioxide emissions. That is the finding of new research from Chalmers University of Technology, Sweden, looking at emissions from the entire life cycle -- from manufacture of electric cars and batteries, to electricity used for operation. However, the total effect of a phasing out of fossil-fuelled cars will not be felt until the middle of the century -- and how the batteries are manufactured will affect the extent of the benefit.

A rapid and mandatory phasing in of electric cars could cause emissions from Swedish passenger cars' exhausts to approach zero by 2045. The Swedish government has proposed an outright ban on the sale of new fossil fuel cars from the year 2030 -- but that alone will not be enough to achieve Sweden's climate targets on schedule.

"The lifespan of the cars currently on the roads and those which would be sold before the introduction of such a restriction mean that it would take some time -- around 20 years -- before the full effect becomes visible," says Johannes Morfeldt, researcher in Physical Resource Theory at Chalmers University of Technology and lead author of the recently published scientific study.

To have the desired effect, a ban would either need to be introduced earlier, by the year 2025, or, if the ban is not brought in until 2030, then the use of biofuels in petrol and diesel cars needs to increase significantly before then -- in accordance with the revised Swedish "reduction obligation." The combination of these two measures would have the effect of achieving zero emissions from passenger vehicles and keeping to Sweden's climate targets.

"The results from our study show that rapid electrification of the Swedish car fleet would reduce life cycle emissions, from 14 million tonnes of carbon dioxide in 2020 to between 3 and 5 million tonnes by the year 2045. The end result in 2045 will depend mainly on the extent to which possible emission reductions in the manufacturing industry are realised," says Johannes Morfeldt.

A transition from petrol and diesel cars to electric cars will mean an increased demand for batteries. Batteries for electric cars are often criticised, not least for the fact that they result in high levels of greenhouse gas emissions during manufacture.

"There are relatively good opportunities to reduce emissions from global battery manufacturing. Our review of the literature on this shows that average emissions from global battery manufacturing could decrease by about two thirds per kilowatt hour of battery capacity by the year 2045. However, most battery manufacturing takes place overseas, so Swedish decision-makers have more limited opportunities to influence this question," says Johannes Morfeldt.

From a climate perspective, it does not matter where the emissions take place, and the risk with decisions taken at a national level for lowering passenger-vehicle emissions is that they could lead to increased emissions elsewhere -- a phenomenon sometimes termed 'carbon leakage'. In this case, the increase in emissions would result from greater demand for batteries, and the risk is thus greater the higher the emissions from battery production.

In that case, the Swedish decision would not have as great an effect on reducing the climate impact as desired. The life-cycle emissions would end up in the upper range -- around 5 million tonnes of carbon dioxide instead of around 3 million tonnes. Due to this, there may be reason to regulate emissions in both vehicle and battery production, from a life cycle perspective.

"Within the EU, for example, there is a discussion about setting a common standard for the manufacture of batteries and vehicles -- in a similar way as there is a standard that regulates what may be emitted from exhausts," says Johannes Morfeldt.

But, given Sweden's low emissions from electricity production, a ban on sales of new fossil-fuel cars would indeed result in a sharp reduction of the total climate impact, regardless of how the manufacturing industry develops.

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Amazon indigenous group's lifestyle may hold a key to slowing down aging

A team of international researchers has found that the Tsimane indigenous people of the Bolivian Amazon experience less brain atrophy than their American and European peers. The decrease in their brain volumes with age is 70% slower than in Western populations. Accelerated brain volume loss can be a sign of dementia.

The study was published May 26, 2021 in the Journal of Gerontology, Series A: Biological Sciences and Medical Sciences.

Although people in industrialized nations have access to modern medical care, they are more sedentary and eat a diet high in saturated fats. In contrast, the Tsimane have little or no access to health care but are extremely physically active and consume a high-fiber diet that includes vegetables, fish and lean meat.

"The Tsimane have provided us with an amazing natural experiment on the potentially detrimental effects of modern lifestyles on our health," said study author Andrei Irimia, an assistant professor of gerontology, neuroscience and biomedical engineering at the USC Leonard Davis School of Gerontology and the USC Viterbi School of Engineering. "These findings suggest that brain atrophy may be slowed substantially by the same lifestyle factors associated with very low risk of heart disease."

The researchers enrolled 746 Tsimane adults, ages 40 to 94, in their study. To acquire brain scans, they provided transportation for the participants from their remote villages to Trinidad, Bolivia, the closest town with CT scanning equipment. That journey could last as long as two full days with travel by river and road.

The team used the scans to calculate brain volumes and then examined their association with age for Tsimane. Next, they compared these results to those in three industrialized populations in the U.S. and Europe.

The scientists found that the difference in brain volumes between middle age and old age is 70% smaller in Tsimane than in Western populations. This suggests that the Tsimane's brains likely experience far less brain atrophy than Westerners as they age; atrophy is correlated with risk of cognitive impairment, functional decline and dementia.

The researchers note that the Tsimane have high levels of inflammation, which is typically associated with brain atrophy in Westerners. But their study suggests that high inflammation does not have a pronounced effect upon Tsimane brains.

According to the study authors, the Tsimane's low cardiovascular risks may outweigh their infection-driven inflammatory risk, raising new questions about the causes of dementia. One possible reason is that, in Westerners, inflammation is associated with obesity and metabolic causes whereas, in the Tsimane, it is driven by respiratory, gastrointestinal, and parasitic infections. Infectious diseases are the most prominent cause of death among the Tsimane.

"Our sedentary lifestyle and diet rich in sugars and fats may be accelerating the loss of brain tissue with age and making us more vulnerable to diseases such as Alzheimer's," said study author Hillard Kaplan, a professor of health economics and anthropology at Chapman University who has studied the Tsimane for nearly two decades. "The Tsimane can serve as a baseline for healthy brain aging."

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