EU/EEA: HIV diagnoses rise for the first time in a decade

The increase in 2022 can be attributed to several factors including restoring surveillance activities, scale-up and introduction of novel testing strategies in many countries, migration patterns, lifting of COVID-19 restrictions and arrival of refugees

Peer-Reviewed Publication

EUROPEAN CENTRE FOR DISEASE PREVENTION AND CONTROL (ECDC)

 

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THE TOTAL HIV DIAGNOSES REPORTED DURING THE PERIOD WERE 204,929. OF THESE, HIV CASES AMONG PEOPLE BORN IN UKRAINE TOTALLED 3,183.
EACH MONTH, THE AUTHORS CALCULATED THE MEDIAN NUMBER OF DIAGNOSED CASES FOR BOTH THE OVERALL NUMBER OF CASES AND THE NUMBER OF CASESEXCLUDING HIV CASES AMONG PEOPLE BORN IN UKRAINE. TO CAPTURE THE NON-LINEAR TREND IN BOTH GROUPS, THEY APPLIED CUBIC SPLINES FOR OPTIMAL REPRESENTATION.
THE VERTICAL RED LINE INDICATES FEBRUARY 2022, WHEN THE WAR IN
UKRAINE BEGAN.

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CREDIT: EUROSURVEILLANCE

Across the 30 countries of the European Union and European Economic Area (EU/EEA), 22,995 new HIV diagnoses were reported in 2022. Almost every second new HIV diagnosis (49%, n=11,103) was among migrants, i.e. among people who were not born in in the country they were diagnosed in. born abroad from the country of their diagnosis.

In the aftermath of Russia’s invasion of Ukraine in 2022, more than 4 million Ukrainians took refuge in countries of the European Union and European Economic Area (EU/EEA). In a rapid communication published in Eurosurveillance prior to World AIDS Day 2023 on 1 December, Reyes-Urueña et al. look at most recent surveillance data to assess potential impact on HIV case reporting in the region since the start of the war in Ukraine. [1]

Based on 2022 data, EU/EEA countries have observed an increase in new HIV diagnoses which is attributed to several factors including restoring surveillance activities,  scale-up and introduction of novel testing strategies in many countries, migration patterns, lifting of COVID-19 restrictions and the arrival of refugees. However, 10% of all new HIV diagnoses in the EU/EEA last year were made among Ukrainian refugees (n=2,338). This constitutes a 10-fold increase compared with 2021 (n=223).

Among the 2,338 Ukrainian refugees diagnosed with HIV in the EU/EEA in 2022, 9% (n=217) were diagnosed for the first time in the reporting country while the majority (59%, n=1,368) had been notified about their HIV status before 2022. For around a third (32%), this information was unknown. Half of those that had previously been diagnosed with HIV were on antiretroviral treatment at the time of reporting in 2022.

Host countries need tailored early testing and treatment approaches
Overall, the EU/EEA notification rate of HIV cases in 2022 was 5.1 per 100,000 population which constitutes a 31% increase compared with 2021 (3.9/100,000 population), but a decrease of 3.8% compared with 2019 (5.3/100,000 population).

In the group of Ukrainian people diagnosed with HIV, women are the most affected accounting for the bigger part of new diagnoses (n=1,585) with heterosexual sex as primary transmission mode.

The authors also highlight that “among cases with known data on previous diagnosis, the prevalence of late HIV diagnosis (47.0%) and AIDS (18.9%) among newly diagnosed people underscores the urgent need for tailored early testing and linking to care in host countries.”

According to Reyes-Urueña et al., the results of their study have important implications for HIV prevention, testing, treatment, stigma-reduction and surveillance in EU/EEA countries: “Prevention that is accessible to new migrant populations, including pre-exposure prophylaxis for HIV (PrEP) as well as needle and syringe programmes and drug treatment for people who use drugs are crucial, especially given that refugees have well-documented vulnerabilities that may incur higher HIV acquisition risk.”

 

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References/notes to editors:
[1] Reyes-Urueña Juliana, Marrone Gaetano, Noori Teymur, Kuchukhidze Giorgi, Martsynovska Violetta, Hetman Larysa, Basenko Anton, Bivol Stela, van der Werf Marieke J, Pharris Anastasia, on behalf of the EU/EEA HIV network, Euro Surveill. 2023;28(48):pii=2300642. Available from: https://doi.org/10.2807/1560-7917.ES.2023.28.48.2300642

[2] See also the paper in the same Eurosurveillance issue from Wärnberg et al. on “The molecular epidemiology of HIV-1 in Sweden 1996 to 2022, and the influence of migration from Ukraine”. The authors look at the distribution of HIV-1 subtypes in Sweden since the beginning of the AIDS epidemic. Available from: https://doi.org/10.2807/1560-7917.ES.2023.28.48.2300224

[3] World AIDS Day was introduced by the World Health Organization (WHO) in 1988 and is observed annually on 1 December to raise awareness of the AIDS pandemic caused by HIV infection. See also: World AIDS Day 2023 (europa.eu)

[4] HIV/AIDS: The human immunodeficiency virus (HIV) is a virus, which attacks the immune system and causes a lifelong severe illness with a long incubation period. The end-stage of the untreated infection, acquired immunodeficiency syndrome (AIDS), results from the destruction of the immune system. AIDS is defined by the presence of one or more “opportunistic” illnesses (other illnesses due to decreased immunity).

[5] Late diagnosis is defined as having a CD4 cell count below 350 cells/mm3 blood at the time of diagnosis. This is a measure of the person’s immune system functioning. 

[6] Sustainable Development Goals (SDG) and 90–90–90 targets: in 2015, 17 Sustainable Development Goals (SDGs), each with specific targets for 2030, were introduced by the UN, including target 3.3 to end AIDS as a public health threat by 2030. In 2014, UNAIDS and partners launched the so-called ‘90–90–90 targets’ with the aim for 2020 that 90% people living with HIV are diagnosed (early) and 90% of those diagnosed receive antiretroviral treatment (ART), which leads to viral suppression among 90% of those on such treatment, i.e. the virus is no longer detectable in the blood. Such an undetectable viral load also means that HIV-positive people on effective treatment do not transmit the virus. In 2021, the Joint United Nations Programme on HIV/AIDS (UNAIDS) updated the HIV targets for 2025 as part of the global strategy to end HIV transmission by 2030. The latest data on progress towards these 95-95-95 targets across Europe and Central Asia can be found here: Continuum of HIV care - Monitoring implementation of the Dublin Declaration on partnership to fight HIV/AIDS in Europe and Central Asia: 2022 progress report (europa.eu)

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JOURNAL

Eurosurveillance

DOI

10.2807/1560-7917.ES.2023.28.48.2300642 

METHOD OF RESEARCH

Data/statistical analysis

ARTICLE TITLE

HIV diagnoses among people born in Ukraine reported by EU/EEA countries in 2022: impact on regional HIV trends and implications for healthcare planning, EU/EEA, 2022

ARTICLE PUBLICATION DATE

30-Nov-2023

 

Researchers extend non-line-of-sight imaging towards longer wavelengths

New system uses superconducting nanowire single-photon detector; could be useful for self-driving vehicles, robotic vision and more

Peer-Reviewed Publication

OPTICA

 

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NON-LINE-OF-SIGHT IMAGING CAN DETECT OBJECTS EVEN IF THEY ARE BEHIND A WALL. RESEARCHERS HAVE NOW EXTENDED THIS METHOD FROM VISIBLE WAVELENGTHS INTO THE NEAR AND MID-INFRARED REGION.

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CREDIT: XIAOLONG HU, TIANJIN UNIVERSITY

WASHINGTON — Emerging technologies for non-line-of-sight imaging can detect objects even if they are around a corner or behind a wall. In new work, researchers use a new type of detector to extend this method from visible light into near and mid-infrared wavelengths, an advance that could be especially useful for unmanned vehicles, robotic vision, endoscopy and other applications.

“Infrared non-line-of-sight imaging can improve the safety and efficiency of unmanned vehicles by helping them detect and navigate around obstacles that are not directly visible,” said Xiaolong Hu from Tianjin University in China. His team collaborated with a group led by Jingyu Yang, also from Tianjin University. “Using near-infrared wavelengths could also help reduce eye safety concerns and lower the background noise, which could potentially allow imaging over longer distances during daytime.”

In the Optica Publishing Group journal Optics Express, the researchers describe the first demonstration of non-line-of-sight imaging using an advanced light-sensing component known as a superconducting nanowire single-photon detector. This detector exhibits single-photon sensitivity from x-ray to the mid-IR wavelengths, enabling researchers to extend the imaging technique’s spectral range to the near and mid-infrared wavelengths of 1560 and 1997 nm. The researchers also developed a new algorithm to further improve the images obtained by the system.

“This proof-of-principle demonstration opens doors for more research opportunities and potential applications,” said Hu. “Moving non-line-of-sight imaging toward the mid-infrared wavelengths brings advantages for many applications. In addition to improving navigation for robots and vehicles, it could also enhance the signal-to-noise ratio for biological imaging.”

Creating a sensitive eye

Non-line-of-sight imaging technologies use photodetectors to detect multiple rays of reflected light emitted or reflected from objects outside the line of sight. Unlike traditional line-of-sight imaging techniques such as LiDAR and photography, the light detected for non-line-of-sight imaging is very faint. This requires very high sensitivity detectors.

“We designed and made a superconducting nanowire single-photon detector that acts as a very sensitive eye for seeing an object hidden around a corner,” said Hu. “This detector outperforms other single-photon detectors in terms of detection efficiency in the near and mid-infrared spectral ranges, which made it possible to perform non-line-of-sight imaging at longer wavelengths.”

Superconducting nanowire single-photon detectors are based on the fact that a single photon will disrupt superconductivity. This creates a measurable change in electrical resistance that allows the detection of individual photons with high efficiency. In the new work, the researchers created a single-photon detector with 40-nm-wide nanowires arranged in a fractal pattern. This pattern, which exhibits similar shapes at various magnifications, makes it possible to effectively detect photons in all polarizations. The detector was cooled to ~2 K (just above absolute zero), which is required to achieve superconductivity.

Imaging in the infrared

After demonstrating that their superconducting nanowire single-photon detector exhibited better timing resolution and lower noise than an InGaAs/InP single-photon avalanche diode, the researchers used the new detector to acquire non-line-of-sight imaging at both 1560 and 1997 nm. They were able to achieve a spatial resolution of less than 2 cm for both wavelengths. They also showed that images reconstructed using their new algorithm had a significantly lower root mean square error — a measure of the deviation from the ideal image — than those reconstructed using other methods.

The researchers are now working to extend their work by exploring other wavelengths of interest and examining how arranging multiple superconducting nanowire single-photon detectors into arrays might enable additional capabilities. They also want to experiment with using their new system to achieve non-line-of-sight imaging over longer distances during the day.

Paper: Y. Feng, X. Cui, Y. Meng, X. Yin, K. Zou, Z. Hao, J. Yang, X. Hu, “Non-line-of-sight imaging at infrared wavelengths using a superconducting nanowire single-photon detector,” Opt. Express, Vol. 31, Issue 25, pp. 42240-42254 (2023). doi.org/10.1364/OE.497802

About Optics Express

Optics Express reports on scientific and technology innovations in all aspects of optics and photonics. The bi-weekly journal provides rapid publication of original, peer-reviewed papers. It is published by Optica Publishing Group and led by Editor-in-Chief James Leger of the University of Minnesota, USA. Optics Express is an open-access journal and is available at no cost to readers online.  For more information, visit Optics Express.

About Optica Publishing Group (formerly OSA)

Optica Publishing Group is a division of Optica, the society advancing optics and photonics worldwide. It publishes the largest collection of peer-reviewed content in optics and photonics, including 18 prestigious journals, the society’s flagship member magazine, and papers from more than 835 conferences, including 6,500+ associated videos. With over 400,000 journal articles, conference papers and videos to search, discover and access, Optica Publishing Group represents the full range of research in the field from around the globe.

The researchers created a superconducting nanowire single-photon detector with nanowires arranged in a fractal pattern, which extended the imaging technique’s spectral range into near and mid-infrared wavelengths.

CREDIT

Xiaolong Hu, Tianjin University

JOURNAL

Optics Express

DOI

10.1364/OE.497802 

 

Antarctica's ancient ice sheets foreshadow dynamic changes in Earth’s future

Peer-Reviewed Publication

UNIVERSITY OF WISCONSIN-MADISON

MADISON – Nineteen million years ago, during a time known as the early Miocene, massive ice sheets in Antarctica rapidly and repeatedly grew and receded. The Miocene is widely considered a potential analog for Earth's climate in the coming century, should humanity remain on its current carbon emissions trajectory.

Identifying how and why Antarctica's major ice sheets behaved the way they did in the early Miocene could help inform understanding of the sheets' behavior under a warming climate. Together, the ice sheets lock a volume of water equivalent to more than 50 meters of sea level rise and influence ocean currents that affect marine food webs and regional climates. Their fate has profound consequences for life nearly everywhere on Earth.

While fluctuations in Antarctica's ice sheets have, over the span of millions of years, grown and diminished at regular intervals tied to natural oscillations in Earth’s journey in orbit, researchers at the University of Wisconsin–Madison and their collaborators around the world have uncovered evidence that Antarctica's ice sheets grew and shrank more frequently during the Miocene epoch than was previously known.

            This new evidence, published recently in the Proceedings of the National Academy of Sciences, indicates that between about 19.2 and 18.8 million years ago, the ice sheets grew and receded multiple times over cycles of just a few thousand years. That is much more rapidly than can be explained by periodic shifts in the planet’s orbit and rotational axis, known as Milankovitch cycles, which typically advance slowly, altering Earth's climate and ice sheets over tens or hundreds of thousands of years.

            "Our observation of this rapid volatility of the Antarctic ice sheets raises the interesting question of what's causing it," says Nick Sullivan, a 2022 UW–Madison PhD graduate who led the analysis for his dissertation research.

The study offers an unprecedented window into the sheets' past behavior, and it relies on a well-preserved sediment record from the Antarctic Drilling Project, or ANDRILL. The project was an international scientific collaboration to gather evidence of past climatic conditions via sediment and rock drilled from hundreds of meters below the Antarctic seabed.

In 2006 and 2007, drilling in McMurdo Sound off the coast of Antarctica in an area influenced by both of the continent's large ice sheets recovered detailed sediment records from the Miocene, close to the ice sheet.

“We could clearly see the influence of long-term climate cycles on ice sheet extent in the rock and sediment cores we recovered in 2007, but our initial observations weren’t detailed enough to detect shorter-term changes,” says co-author Richard Levy, a professor at Victoria University of Wellington and principal scientist at GNS Science, a public research institute in New Zealand.

The latest analysis led by Sullivan now allows scientists to “document past ice sheet change on timescales as short as five centuries or so,” says Stephen Meyers, a UW–Madison geoscience professor who worked with Sullivan in his analysis.

In fact, Meyers calls it a remarkable archive.

That’s because it contains small bits of gravel that fell to the seafloor as icebergs drifted away from the ice sheets after breaking away. The amount of gravel in ocean sediment records ice sheet changes, such as when the edge of an ice sheet gets closer to or further away from that particular part of the seafloor.

While testing for evidence of Milankovitch cycles within the sediment, Sullivan found variations in the abundance of gravel, suggesting nearby ice sheets advanced and retreated in recurring intervals as brief as 1,200 years.

It's unclear what triggered the ice sheets to advance and retreat at these geologically frequent intervals, but the team proposes several potential causes based on prior studies of ice sheets.

One idea suggests that the ice sheets, building up over time, became steeper and top heavy, leading them to collapse. Another proposes that as thick ice sheets advanced over rough terrain, heat from friction helped to temporarily speed them up.

"There are likely multiple mechanisms that were going on and interacting with each other," says Sullivan, including variations in the local climate and the ocean.

Scientists around the world are working to better understand the many factors beyond Earth’s orbit that control ice sheet behavior as the planet continues to warm. The early Miocene isn’t perfectly analogous to today’s world, but the new study suggests Antarctica's ice sheets could change rapidly and in unexpected ways in the coming centuries if carbon dioxide levels and temperatures continue to rise due to anthropogenic greenhouse gas emissions.

“It was long thought that Antarctica’s ice sheets remained large and stable over long periods of time. But the closer we look, the more we realize just how sensitive the ice sheets are to environmental change,” says Levy. “This insight is key as we consider the pace at which we need to adapt to future sea level rise driven by melt and retreat of our planet’s ice sheets.”

# # #

 

– Will Cushman, wcushman@wisc.edu, 608-263-1986

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JOURNAL

Proceedings of the National Academy of Sciences

METHOD OF RESEARCH

Meta-analysis

Tis the season to recognize chocolate: researchers highlight high quality cacao in Colombia

Peer-Reviewed Publication

SOCIETY OF CHEMICAL INDUSTRY

Scientists are working to protect the unique qualities of cacao beans grown in the Buenaventura region on the Pacific coast of Colombia.

In a study published in the Journal of the Science of Food and Agriculture, researchers from the Colombian Corporation for Agricultural Research (AGROSAVIA) have examined a wealth of metrics to uncover the complex interactions between environmental factors and cacao quality.

In a pioneering move, they have proposed that Buenaventura should be designated as a new Denomination of Origin (DO) for cacao trees. This is a legal recognition given to products that originate from a specific geographic region which certifies their unique quality and characteristics. 

The Benefits of Buenaventura

The peer review study, which is the first to scientifically document the unique properties of cacaos in Colombia, notes that Buenaventura stands out from other cacao producing regions because of the distinctive fruity aroma of the cocoa derived from the area, attributed to the rich biodiversity of the lowland rainforest.

Colombia is recognised worldwide as a producer of cacao beans for fine quality chocolate products. Despite this, a lack of scientific research to characterise its unique regional conditions and cocoa quality mean Colombia lags behind in the realm of cacao DOs.

Sebastián Escobar Parra, an associate PhD researcher at AGROSAVIA and co-author on the study, explained the significance of cacao DOs for a region. ‘Economically, it can lead to higher market prices for the region's cacao products, boosting local economies and providing financial incentives for farmers. Culturally, it preserves traditional knowledge and practices related to cacao cultivation, contributing to the cultural heritage of the region.’

Importantly, establishing denominations of origin also promotes sustainable practices and the preservation of biodiversity in cacao production. Carlos E González-Orozco, an associate PhD researcher at AGROSAVIA and corresponding author on the study, explained:

‘Cacao denominations of origin play a vital role in promoting sustainable practices by emphasising traditional farming methods, conserving native varieties, encouraging agroforestry, conserving water resources, promoting organic pest management, educating farmers, and aligning with certification standards. Through these efforts, denominations of origin contribute significantly to the preservation of biodiversity and the sustainable future of cacao production.’

Characterising the region

The study proposes a framework encompassing multiple variables which, when quantified, could collectively contribute to the establishment of cacao DOs. Amongst these are:

·    Geography – conditions of the natural environment including soil composition, climate, and altitude.

·   Genetics – the genetic diversity of cacao plants within a region can be used to identify characteristics contributing to distinct flavour profiles and disease resistance.

·   Pests and Diseases – Understanding and managing region-specific pest and disease challenges are essential for sustaining cacao production and maintaining the unique qualities associated with denominations of origin.

·   Microbial Diversity in the soil and on cacao pods – this can influence the fermentation process, a critical step in chocolate production. Unique microbial communities in a region contribute to the development of specific flavours during fermentation, impacting the final chocolate product.

·  Cocoa Quality - flavour, aroma, texture, and chemical composition are all crucial factors in identifying superior quality cacao from specific regions.

Expanding the Framework

The authors hope that this framework can be expanded to other regions of Colombia to provide cacao denominations of origin for the local farmers.

González-Orozco explained, ‘This scalability is invaluable, as it enables the establishment of denominations of origin not only in Colombia but also in other parts of the world. Consistent standards and recognition of regional uniqueness contribute to the global reputation of cocoa-producing regions.’

‘Future directions might also include studying the long-term economic and environmental sustainability of cacao cultivation in these designated regions,’ noted Parra.

 

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JOURNAL

Journal of the Science of Food and Agriculture

DOI

10.1002/jsfa.13016 

ARTICLE TITLE

Integrating new variables into a framework to support cacao denomination of origin: a case study in Southwest Colombia

 

Researchers show an old law still holds for quirky quantum materials

This surprising result is important for understanding unconventional superconductors and other materials where electrons band together to act collectively.

Peer-Reviewed Publication

DOE/SLAC NATIONAL ACCELERATOR LABORATORY

 

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AN ILLUSTRATION SHOWS STRONGLY INTERACTING ELECTRONS CARRYING HEAT AND CHARGE FROM WARMER TO COOLER REGIONS OF A QUANTUM MATERIAL. A THEORETICAL STUDY BY SLAC, STANFORD AND THE UNIVERSITY OF ILLINOIS FOUND THAT THE RATIO OF HEAT TRANSPORT TO CHARGE TRANSPORT IN CUPRATES ­– QUANTUM MATERIALS LIKE THIS ONE, WHERE ELECTRONS GLOM TOGETHER AND ACT COOPERATIVELY ­– SHOULD BE SIMILAR TO THE RATIO IN NORMAL METALS, WHERE ELECTRONS BEHAVE AS INDIVIDUALS. THIS SURPRISING RESULT OVERTURNS THE IDEA THAT THE 170-YEAR-OLD WIEDEMANN-FRANZ LAW DOES NOT APPLY TO QUANTUM MATERIALS. 

 

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CREDIT: GREG STEWART/SLAC NATIONAL. ACCELERATOR LABORATORY

Long before researchers discovered the electron and its role in generating electrical current, they knew about electricity and were exploring its potential. One thing they learned early on was that metals were great conductors of both electricity and heat.

And in 1853, two scientists showed that those two admirable properties of metals were somehow related: At any given temperature, the ratio of electronic conductivity to thermal conductivity was roughly the same in any metal they tested. This so-called Wiedemann-Franz law has held ever since – except in quantum materials, where electrons stop behaving as individual particles and glom together into a sort of electron soup. Experimental measurements have indicated that the 170-year-old law breaks down in these quantum materials, and by quite a bit.

Now, a theoretical argument put forth by physicists at the Department of Energy’s SLAC National Accelerator Laboratory, Stanford University and the University of Illinois suggests that the law should, in fact, approximately hold for one type of quantum material – the copper oxide superconductors, or cuprates, which conduct electricity with no loss at relatively high temperatures. 

In a paper published in Science today, they propose that the Wiedemann-Franz law should still roughly hold if one considers only the electrons in cuprates. They suggest that other factors, such as vibrations in the material’s atomic latticework, must account for experimental results that make it look like the law does not apply.

This surprising result is important to understanding unconventional superconductors and other quantum materials, said Wen Wang, lead author of the paper and a PhD student with the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC.

“The original law was developed for materials where electrons interact with each other weakly and behave like little balls that bounce off defects in the material’s lattice,” Wang said. “We wanted to test the law theoretically in systems where neither of these things was true.”

Peeling a quantum onion

Superconducting materials, which carry electric current without resistance, were discovered in 1911. But they operated at such extremely low temperatures that their usefulness was quite limited.

That changed in 1986, when the first family of so-called high-temperature or unconventional superconductors – the cuprates – was discovered. Although cuprates still require extremely cold conditions to work their magic, their discovery raised hopes that superconductors could someday work at much closer to room temperature – making revolutionary technologies like no-loss power lines possible. 

After nearly four decades of research, that goal is still elusive, although a lot of progress has been made in understanding the conditions in which superconducting states flip in and out of existence. 

Theoretical studies, performed with the help of powerful supercomputers, have been essential for interpreting the results of experiments on these materials and for understanding and predicting phenomena that are out of experimental reach.

For this study, the SIMES team ran simulations based on what’s known as the Hubbard model, which has become an essential tool for simulating and describing systems where electrons stop acting independently and join forces to produce unexpected phenomena. 

The results show that when you only take electron transport into account, the ratio of electronic conductivity to thermal conductivity approaches what the Wiedemann-Franz law predicts, Wang said. “So, the discrepancies that have been seen in experiments should be coming from other things like phonons, or lattice vibrations, that are not in the Hubbard model,” she said.

SIMES staff scientist and paper co-author Brian Moritz said that although the study did not investigate how vibrations cause the discrepancies, “somehow the system still knows that there is this correspondence between charge and heat transport amongst the electrons. That was the most surprising result.”

From here, he added, “maybe we can peel the onion to understand a little bit more.”

Major funding for this study came from the DOE Office of Science. Computational work was carried out at Stanford University and on resources of the National Energy Research Scientific Computing Center, which is a DOE Office of Science user facility.

Citation: Wen O. Wang et al., Science, 01 December 2023 (10.1126/science.ade3232)

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SLAC is a vibrant multiprogram laboratory that explores how the universe works at the biggest, smallest and fastest scales and invents powerful tools used by scientists around the globe. With research spanning particle physics, astrophysics and cosmology, materials, chemistry, bio- and energy sciences and scientific computing, we help solve real-world problems and advance the interests of the nation.

SLAC is operated by Stanford University for the U.S. Department of Energy’s Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time.

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JOURNAL

Science

DOI

10.1126/science.ade3232 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

The Wiedemann-Franz law in doped Mott insulators without quasiparticles

ARTICLE PUBLICATION DATE

1-Dec-2023

 

Armed to the hilt: Study solves mystery behind bacteria’s extensive weaponry

Peer-Reviewed Publication

UNIVERSITY OF OXFORD

• New study tackles the mystery of why bacteria often carry diverse ranges of weapons.
• The findings show that different weapons are best suited to different competition scenarios.
• Short-range weapons help bacteria to invade established communities; long-range weapons are useful once established.

A new study led by the University of Oxford has shed light on why certain species of bacteria carry astonishing arsenals of weapons. The findings, published today in the journal Nature Ecology & Evolution, could help us to engineer microbes that can destroy deadly pathogens, reducing our reliance on antibiotics.

Many species of bacteria possess multiple weapons to attack competitors. These include both short-range weapons that require direct contact with neighbouring cells, and long-range weapons, such as toxins that are released into the environment. Up to now, why bacteria have evolved to carry such a wide array of weapons has been a mystery.

Study co-author Professor Kevin Foster (Departments of Biology and Biochemistry, University of Oxford), said: ‘Unlike animals, which tend to carry a single weapon type such as horns, antlers, or tusks, bacterial species commonly carry multiple weapons. But it was unclear what the evolutionary basis for this was – why not just invest in a single type? One theory was that bacteria carry multiple weapons because they serve different functions during competition.’

The researchers tested this using the opportunistic pathogen Pseudomonas aeruginosa, a priority one pathogen by the World Health Organization, due to the rapid emergence of multidrug-resistant strains. P. aeruginosa possesses diverse weapons, including the ability to produce various toxic molecules (a long-range weapon), and toxin-loaded filaments anchored to its outer membrane (a short-range weapon).

The team designed a series of experiments to determine under which conditions short- versus long-range weapons give a greater advantage. They used genome editing to generate P. aeruginosa strains that lacked and were susceptible to either the toxin-loaded filaments or long-range toxins called tailocins. The susceptible strains were then grown on agar plates with control P. aeruginosa over two days, at a series of different ratios. Because the strains each expressed a different fluorescent protein, the researchers could quantify the ratio of attacker vs susceptible bacteria.

The results clearly demonstrated that the two weapons perform best under different conditions. Tailocins, the long-range weapon, only became effective when the attacking bacteria were at a high density and more common than the competition. On the other hand, carrying toxin-loaded filaments gave a competitive advantage over a much greater range of conditions. This included situations when the attacking bacteria were only present in low initial numbers and had to compete with a larger population of susceptible bacteria.

The researchers then challenged the two engineered strains in direct head-to-head competitions. When the strains started at an equal frequency, the bacteria carrying toxin-loaded filaments had a distinct advantage. However, both weapon users were able to win when they started in the majority.

Moreover, when cells could use both weapons simultaneously, they were able to suppress susceptible bacteria significantly better than strains that used only one weapon, demonstrating that the short- and long-range weapons complemented each other.

According to the researchers, the results show that short- and long-range weapons perform differently depending on the competition scenario. Co-author Dr Sean Booth (University of Oxford) said: ‘Our results demonstrate that a particular advantage of contact-dependent weapons is that they are effective even when users are at a numerical disadvantage. This suggests that they may have evolved to enable bacteria to invade an established population, when they are outnumbered by resident bacteria.’

This theory was supported by a computational model which simulated a low number of attacker cells attacking a larger population of susceptible cells. In the model, cells using short-range weapons were able to successfully invade the community, whereas cells using long-range weapons were not. However, when cells using long-range weapons were present in large numbers and were more common than the competition, these became extremely effective, giving the attackers a significant competitive advantage.

The researchers are now investigating how to apply the findings to custom-design beneficial microorganisms that can out-compete pathogenic strains.

Co-author Dr William Smith (University of Oxford and University of Manchester) said: ‘These results have given us valuable insights into the types of weapons bacteria need to successfully invade and persist in a community. Ultimately, this could help us to develop antibiotic-free ways to fight multi-drug resistant bacteria.’

Notes for editors:

For media enquiries and interview requests, contact Dr Sean Booth, University of Oxford: sean.booth@biology.ox.ac.uk or Dr William Smith: willpjsmith@gmail.com

Images relating to the study are available on request.

The study ‘The evolution of short- and long-range weapons for bacterial competition’ will be published in Nature Ecology & Evolution at 16:00 GMT / 11:00 ET Thursday 30 November 2023 at https://www.nature.com/articles/s41559-023-02234-2 (DOI 10.1038/s41559-023-02234-2). To view a copy of the manuscript before this under embargo, contact Dr Sean Booth, University of Oxford: sean.booth@biology.ox.ac.uk or Dr William Smith: willpjsmith@gmail.com

About the University of Oxford

Oxford University has been placed number 1 in the Times Higher Education World University Rankings for the eighth year running, and ​number 3 in the QS World Rankings 2024. At the heart of this success are the twin-pillars of our ground-breaking research and innovation and our distinctive educational offer.

Oxford is world-famous for research and teaching excellence and home to some of the most talented people from across the globe. Our work helps the lives of millions, solving real-world problems through a huge network of partnerships and collaborations. The breadth and interdisciplinary nature of our research alongside our personalised approach to teaching sparks imaginative and inventive insights and solutions.

Through its research commercialisation arm, Oxford University Innovation, Oxford is the highest university patent filer in the UK and is ranked first in the UK for university spinouts, having created more than 300 new companies since 1988. Over a third of these companies have been created in the past five years. The university is a catalyst for prosperity in Oxfordshire and the United Kingdom, contributing £15.7 billion to the UK economy in 2018/19, and supports more than 28,000 full time jobs.

 

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JOURNAL

Nature Ecology & Evolution

DOI

10.1038/s41559-023-02234-2 

ARTICLE TITLE

The evolution of short- and long-range weapons for bacterial competition

ARTICLE PUBLICATION DATE

30-Nov-2023

A mineral produced by plate tectonics has a global cooling effect, study finds

An accordion-textured clay called smectite efficiently traps organic carbon and could help buffer global warming over millions of years

Peer-Reviewed Publication

MASSACHUSETTS INSTITUTE OF TECHNOLOGY

MIT geologists have found that a clay mineral on the seafloor, called smectite, has a surprisingly powerful ability to sequester carbon over millions of years. 

Under a microscope, a single grain of the clay resembles the folds of an accordion. These folds are known to be effective traps for organic carbon. 

Now, the MIT team has shown that the carbon-trapping clays are a product of plate tectonics: When oceanic crust crushes against a continental plate, it can bring rocks to the surface that, over time, can weather into minerals including smectite. Eventually, the clay sediment settles back in the ocean, where the minerals trap bits of dead organisms in their microscopic folds. This keeps the organic carbon from being consumed by microbes and expelled back into the atmosphere as carbon dioxide. 

Over millions of years, smectite can have a global effect, helping to cool the entire planet. Through a series of analyses, the researchers showed that smectite was likely produced after several major tectonic events over the last 500 million years. During each tectonic event, the clays trapped enough carbon to cool the Earth and induce the subsequent ice age. 

The findings are the first to show that plate tectonics can trigger ice ages through the production of carbon-trapping smectite. 

These clays can be found in certain tectonically active regions today, and the scientists believe that smectite continues to sequester carbon, providing a natural, albeit slow-acting, buffer against humans’ climate-warming activities. 

“The influence of these unassuming clay minerals has wide-ranging implications for the habitability of planets,” says Joshua Murray, a graduate student in MIT’s Department of Earth, Atmospheric, and Planetary Sciences. “There may even be a modern application for these clays in offsetting some of the carbon that humanity has placed into the atmosphere.”

Murray and Oliver Jagoutz, professor of geology at MIT, have published their findings today in Nature Geoscience. 

A clear and present clay

The new study follows up on the team’s previous work, which showed that each of the Earth’s major ice ages was likely triggered by a tectonic event in the tropics. The researchers found that each of these tectonic events exposed ocean rocks called ophiolites to the atmosphere. They put forth the idea that, when a tectonic collision occurs in a tropical region, ophiolites can undergo certain weathering effects, such as exposure to wind, rain, and chemical interactions, that transform the rocks into various minerals, including clays.

“Those clay minerals, depending on the kinds you create, influence the climate in different ways,” Murray explains. 

At the time, it was unclear which minerals could come out of this weathering effect, and whether and how these minerals could directly contribute to cooling the planet. So, while it appeared there was a link between plate tectonics and ice ages, the exact mechanism by which one could trigger the other was still in question. 

With the new study, the team looked to see whether their proposed tectonic tropical weathering process would produce carbon-trapping minerals, and in quantities that would be sufficient to trigger a global ice age. 

The team first looked through the geologic literature and compiled data on the ways in which major magmatic minerals weather over time, and on the types of clay minerals this weathering can produce. They then worked these measurements into a weathering simulation of different rock types that are known to be exposed in tectonic collisions. 

“Then we look at what happens to these rock types when they break down due to weathering and the influence of a tropical environment, and what minerals form as a result,” Jagoutz says. 

Next, they plugged each weathered, “end-product” mineral into a simulation of the Earth’s carbon cycle to see what effect a given mineral might have, either in interacting with organic carbon, such as bits of dead organisms, or with inorganic , in the form of carbon dioxide in the atmosphere. 

From these analyses, one mineral had a clear presence and effect: smectite. Not only was the clay a naturally weathered product of tropical tectonics, it was also highly effective at trapping organic carbon. In theory, smectite seemed like a solid connection between tectonics and ice ages. 

But were enough of the clays actually present to trigger the previous four ice ages? Ideally, researchers should confirm this by finding smectite in ancient rock layers dating back to each global cooling period. 

“Unfortunately, as clays are buried by other sediments, they get cooked a bit, so we can’t measure them directly,” Murray says. “But we can look for their fingerprints.”

A slow build

The team reasoned that, as smectites are a product of ophiolites, these ocean rocks also bear characteristic elements such as nickel and chromium, which would be preserved in ancient sediments. If smectites were present in the past, nickel and chromium should be as well. 

To test this idea, the team looked through a database containing thousands of oceanic sedimentary rocks that were deposited over the last 500 million years. Over this time period, the Earth experienced four separate ice ages. Looking at rocks around each of these periods, the researchers observed large spikes of nickel and chromium, and inferred from this that smectite must also have been present. 

By their estimates, the clay mineral could have increased the preservation of organic carbon by less than one-tenth of a percent. In absolute terms, this is a miniscule amount. But over millions of years, they calculated that the clay’s accumulated, sequestered carbon was enough to trigger each of the four major ice ages.

“We found that you really don’t need much of this material to have a huge effect on the climate,” Jagoutz says. 

“These clays also have probably contributed some of the Earth’s cooling in the last 3 to 5 million years, before humans got involved,” Murray adds. “In the absence of humans, these clays are probably making a difference to the climate. It’s just such a slow process.”

“Jagoutz and Murray’s work is a nice demonstration of how important it is to consider all biotic and physical components of the global carbon cycle,” says Lee Kump, a professor of geosciences at Penn State University, who was not involved with the study. “Feedbacks among all these components control atmospheric greenhouse gas concentrations on all time scales, from the annual rise and fall of atmospheric carbon dioxide levels to the swings from icehouse to greenhouse over millions of years.”

Could smectites be harnessed intentionally to further bring down the world’s carbon emissions? Murray sees some potential, for instance to shore up carbon reservoirs such as regions of permafrost. Warming temperatures are predicted to melt permafrost and expose long-buried organic carbon. If smectites could be applied to these regions, the clays could prevent this exposed carbon from escaping into and further warming the atmosphere. 

“If you want to understand how nature works, you have to understand it on the mineral and grain scale,” Jagoutz says. “And this is also the way forward for us to find solutions for this climatic catastrophe. If you study these natural processes, there’s a good chance you will stumble on something that will be actually useful.”

This research was funded, in part, by the National Science Foundation.

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Written by Jennifer Chu, MIT News

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JOURNAL

Nature Geoscience

DOI

10.1038/s41561-023-01342-9 

ARTICLE TITLE

“Palaeozoic cooling modulated by ophiolite weathering through organic carbon preservation”