Hidden acid-base clusters drive rapid formation of atmospheric ultrafine particles

Peer-Reviewed Publication

SCIENCE CHINA PRESS

 

IMAGE: ON SUNNY DAYS IN MEGACITIES SUCH AS BEIJING, GASEOUS ACID AND BASE POLLUTANTS FORM A LARGE AMOUNT OF NEW ULTRAFINE PARTICLES. THE CLUSTERING BETWEEN ONE ACID AND ONE BASE IS THE RATE-LIMITING STEP FOR NEW PARTICLE FORMATION. view more 

CREDIT: ©SCIENCE CHINA PRESS

A joint research team led by Dr. Jingkun Jiang from Tsinghua University and Dr. Markku Kulmala from the University of Helsinki has reported an efficient mechanism for gaseous sulfuric acid and bases to form atmospheric ultrafine particles. The findings explain the rapid formation of secondary ultrafine particles, which could further influence air quality and the climate.

The team found that acid-base reactions are the major driving forces for gaseous precursors to overcome surface tension and form ultrafine particles, and the key mechanism is the formation of hidden acid-base heterodimers. This hidden mechanism explains the high particle formation rate in Chinese megacities.

Their findings were published in National Science Review.

“There are hundreds of thousands of ultrafine particles in per cubic centimeter air in Chinese megacities, and a new particle formation event on a sunny noon can readily elevate their concentration by one order of magnitude within several hours,” Jiang says.

To explain how new particles can be so efficiently converted from gaseous precursors, Jiang and Kulmala, together with Dr. Runlong Cai, are determined to seek the key mechanism for rapid new particle formation. They have known that sulfuric acid is a primary precursor, whereas the challenge is to find the key bases among many candidates. “Urban air is a complex cocktail of chemicals with poorly understood interactions and feedbacks”, Kulmala commented.

The researchers observed highly abundant molecular clusters containing sulfuric acid during new particle formation in Beijing and Shanghai. Some of the measured clusters contain sulfuric acid and amine molecules. These provide strong evidence for amine participation in the formation of stable sulfuric acid clusters, which increases the conversion rate from gaseous sulfuric acid to new particles.

“It is intriguing that we measured fewer bases than acids in a cluster. There must be some key information hidden behind the measured signals,” Cai says. It was previously proposed that the clustering between a base molecule and a sulfuric acid homodimer is the key mechanism for new particle formation, as there were no base molecules in the measured clusters containing one sulfuric acid molecule. The research team, however, found that this was a measurement artifact.

Combining long-term measurements and theory based on quantum chemistry and cluster kinetics, they found that the formation of hidden acid-base heterodimers is the key mechanism. This mechanism is far more efficient than the previously proposed mechanism with acid-acid homodimers, ensuring the rapid formation of sulfuric acid clusters and new particles.

The hidden heterodimers solve the puzzle of why new particles could be frequently formed against a high background particle loading in megacities. The hidden acid-base heterodimers with a considerable fraction in the measured sulfuric acid signals can effectively cluster with each other. This ensures a high particle formation rate approaching the theoretical maximum even at a low ambient amine concentration. The hidden heterodimers also explain the temperature dependency of new particle formation in Beijing and Shanghai. “Atmospheric measurements are often perturbed by many factors. I did not expect such an amazing consistency between the measurements and the new theory,” Cai says.

The team also sought the hidden base molecules using thermodynamic and kinetic analyses. Among the measured gaseous molecules, strong amines such as dimethylamine serve as the key bases in acid-base heterodimers, whereas the highly abundant ammonia and other weak bases are more likely to be involved in the subsequent cluster growth process.

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See the article:

The missing base molecules in atmospheric acid-base nucleation

https://doi.org/10.1093/nsr/nwac137

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JOURNAL

National Science Review

DOI

10.1093/nsr/nwac137 

Spatiotemporal variation of mortality burden attributable to heatwaves in China, 1979-2020

Peer-Reviewed Publication

SCIENCE CHINA PRESS

 NEWS RELEASE 2-SEP-2022

 

IMAGE: HEALTH RISKS OF HEATWAVES WERE CHARACTERIZED BY RAPID GROWTH, NONLINEAR TEMPORAL EVOLUTION AND EXTREMITY. NATIONALLY, THE NUMBER OF ANNUAL ATTRIBUTABLE DEATHS WAS AN AVERAGE OF 3,679 IN 1980S BUT INCREASED TO 15,500 IN 2010S. TAKING A 5-YEAR MOVING AVERAGE, IT TOOK 2.8 YEARS FOR EVERY INCREASE OF 1,000 ANNUAL HEATWAVE-RELATED DEATHS FROM 1980S TO 2000S, BUT JUST ONE YEAR FOR THE SAME INCREASE TO OCCUR IN 2010S. ALSO, THE ATTRIBUTABLE DEATHS REACHED A HIGHEST RECORD OF 26,486 IN 2017, FOLLOWED BY THE SECOND 21,219 IN 2019 AND THE THIRD 20,431 IN 2013. REGIONALLY, EAST AND CENTRAL CHINA HAD THE LARGEST NUMBER OF ATTRIBUTABLE DEATHS IN GENERAL, ACCOUNTING FOR MORE THAN 50% OF DEATHS NATIONWIDE. AMONG THE PROVINCES, DEATHS ASCRIBED TO HEATWAVES WERE HIGHEST IN SHANDONG, FOLLOWED BY HENAN, HEBEI AND JIANGSU. A-D, THE NUMBER OF ATTRIBUTABLE DEATHS TO HEATWAVES IN GRID DURING THE PAST FOUR DECADES. E, ATTRIBUTABLE DEATHS TO HEATWAVES IN CHINA FROM 1979 TO 2020. THE SOLID LINE SHOWS THE ESTIMATED NUMBER OF ATTRIBUTABLE DEATHS TO HEATWAVES; GREY AREAS SHOW THE 95% CONFIDENCE INTERVALS; THE HORIZONTAL DASHED LINE SHOWS THE AVERAGE ANNUAL DEATHS IN 1980S, 1990S, 2000S, 2010S. F, CHANGES IN ATTRIBUTABLE DEATHS TO HEATWAVES IN 2010S RELATIVE TO THE BASELINE PERIOD OF 1980-2009. AD, ATTRIBUTABLE DEATHS TO HEATWAVES. THE MAP NO. IS GS(2019)1673. ART BY HUIQI CHEN. view more 

CREDIT: ©SCIENCE CHINA PRESS

This study is led by Dr. Cunrui Huang (Vanke School of Public Health, Tsinghua University). Heatwaves impose heavy disease burden by increasing the risk of mortality and morbidity, which has been exacerbated worldwide under climate change. "In China, evidence documenting the impact of heatwaves on the number of attributable deaths, spatiotemporal variations and their driving factors is still limited, hindering the understanding of dangerous heatwaves. " Huang says.

Huang, together with his group member Chen and meteorological expert Zhao, sought to identify what was the spatial and temporal trends of heatwave-attributable deaths in China over the past four decades. The team performed event-based attributable loss estimation to quantify the gridded attributable deaths.

The team found that health risks of climate change were characterized by rapid growth, nonlinear evolution and extremity. The attributable deaths to heatwaves in China have increased dramatically by four times in the past four decades, with the rising trends becoming more apparent in the recent decade but some fluctuations among individual years. Regionally, east and central China had the largest number of attributable deaths in general, accounting for more than 50% of deaths nationwide. Among the provinces, deaths ascribed to heatwaves were highest in Shandong, followed by Henan, Hebei and Jiangsu.

The researchers also decomposed the driving factors to changes in attributable deaths. The increase in attributable deaths to heatwaves in China over time was primarily due to increased heatwave exposure, followed by population growth, population aging and the mounting baseline mortality. Notably, population aging has played an increasingly important role in attributable deaths over time. This work could serve important information for policy-makers to develop effective climate mitigation and adaptation measures in response to increasing heatwaves, especially for the most vulnerable elderly populations.

See the article:

Spatiotemporal Variation of Mortality Burden Attributable to Heatwaves in China, 1979-2020

https://doi.org/10.1016/j.scib.2022.05.006

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JOURNAL

Science Bulletin

DOI

10.1016/j.scib.2022.05.006 

CAPTION

The increase in attributable deaths to heatwaves in China was primarily due to increased heatwave exposure, followed by population growth, population aging and the mounting baseline mortality. Notably, population aging has played an increasingly important role in attributable deaths over time, increased from 10.6% in the period between 1980s and 1990s to 15.8% afterward, reaching as high as 20.8% in the period between 2000s and 2010s. a, Decomposition of the contribution of driving factors in seven regions (left) and for the whole nation (right) from 1980s to 1990s. b, Decomposition of the contribution of driving factors in seven regions (left) and for the whole nation (right) from 1990s to 2000s. c, Decomposition of the contribution of driving factors in seven regions (left) and for the whole nation (right) from 2000s to 2010s. AD, attributable deaths to heatwaves. The Map NO. is GS(2019)1673. Art by Huiqi Chen.

CREDIT

©Science China Press

Mortality caused by heatwaves in China has increased since 1979

Peer-Reviewed Publication

INSTITUTE OF ATMOSPHERIC PHYSICS, CHINESE ACADEMY OF SCIENCES

 

IMAGE: HEATWAVES SWEEPS THROUGH NORTHERN CHINA. PHOTO TAKEN IN BEIJING ON JULY 20. view more 

CREDIT: LIANG ZHAO

Since the beginning of the summer in 2022, China has been sweltering under the worst heatwave in decades. A number of people in Zhejiang, Henan, Jiangsu, and Sichuan provinces were diagnosed with thermoplegia, the most severe form of heatstroke, and some even died of this disease.

In a warming world, the threat of heatwaves to human health is increasing. Researchers led by Liang Zhao from the Institute of Atmospheric Physics of the Chinese Academy of Sciences and Cunrui Huang from Tsinghua University investigated the spatial and temporal variation of heatwaves-related human deaths in China from 1979 to 2020.

The study was published in Science Bulletin.

They also explored the relative contributions of drivers such as heatwaves exposure, population growth, population aging, and baseline mortality to changes in attributable mortality.

"We found that the number of deaths caused by heatwaves in China has increased rapidly since 1979, from 3,679 persons per year in the 1980s to 15,500 persons per year in the 2010s," said Zhao. "We also found strong spatial heterogeneity across the country, with more human deaths in East and Central China."

Then what are the main drivers of the large increase in heatwaves-related deaths in China over the past four decades?

"The main drivers are the rapid increase in the frequency of heatwaves, followed by population growth, population aging, and rising baseline mortality. From the 2000s to the 2010s, these four factors accounted for 40.6%, 22.4%, 20.8%, and 16.2% of the change in attributed human deaths, respectively," said Huang.

The research team hopes this study's accurate assessment of the number of heatwaves-related deaths in China and the contribution of their different drivers can help policy makers to fully understand human health hazards of heatwaves and to develop response policies to reduce health losses from increased heatwaves exposure under climate change.

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DOI

10.1016/j.scib.2022.05.006 

ARTICLE TITLE

Spatiotemporal variation of mortality burden attributable to heatwaves in China, 1979–2020

Dragons and brain evolution

A molecular atlas of an Australian dragon’s brain sheds new light on over 300 million years of brain evolution

Peer-Reviewed Publication

MAX-PLANCK-GESELLSCHAFT

 

IMAGE: THE AUSTRALIAN BEARDED DRAGON POGONA VITTICEPS. view more 

CREDIT: MAX PLANCK INSTITUTE FOR BRAIN RESEARCH / G. LAURENT

These days, dragons are keeping Game of Thrones fans on their toes. But they are also providing important insights into vertebrate brain evolution, as revealed by the work of Max Planck scientists on the brain of the Australian bearded dragon Pogona vitticeps. Vertebrate evolution took a major turn 320 million years ago when early tetrapods (animals with four limbs) transitioned from water to land, eventually giving rise to three major clades: the reptiles, the birds (an offshoot of the reptilian tree) and the mammals. Because of common ancestry, the brains of all tetrapods share a similar basal architecture established during early development. Yet, how variations on this common “Bauplan” contributed to clade-specific attributes remains unclear. Neuroscientists at the Max Planck Institute for Brain Research in Frankfurt tackled this question by generating a molecular atlas of the dragon brain and comparing it with one from mice. Their findings suggest that, contrary to popular belief that a mammalian brain consists of an ancient “reptilian” brain supplemented with new mammalian features, both reptilian and mammalian brains evolved their own clade-specific neuron types and circuits, from a common ancestral set.

“Neurons are the most diverse cell types in the body. Their evolutionary diversification reflects alterations in the developmental processes that produce them and may drive changes in the neural circuits they belong to”, says Prof. Gilles Laurent, Director at the Max Planck Institute for Brain Research who led the new study published in Science. “For example, distinct brain areas do not work in isolation, suggesting that the evolution of interconnected regions, such as the thalamus and cerebral cortex, might in some way be correlated. Also, a brain area in reptiles and mammals that derived from a common ancestral structure might have evolved in such a way that it remains ancestral in one clade today, while it is “modern” in the other. Conversely, it could be that both clades now contain a mix of common (ancient) and specific (novel) neuron types. These are the sorts of questions that our experiments tried to address”, Laurent adds.

While traditional approaches to compare developmental regions and projections in the brain do not have the necessary resolution to reveal these similarities and differences, Laurent and his team took a cellular transcriptomic approach. Using a technique called single-cell RNA sequencing that detects a large fraction of the RNA molecules (transcriptomes) present in single cells, the scientists generated a cell-type atlas of the brain of the Australian bearded dragon Pogona vitticeps and compared it to existing mouse brain datasets.

CAPTION

Reptiles and mammals are evolutionary separated by over 300 million years. Max Planck scientists generated a cell type atlas from the brain of a lizard. Computationally integration of this data with mouse transcriptomics revealed that multiple brain areas contain mixtures of similar and divergent neurons, suggesting ubiquitous neuron diversification in these brain regions.

CREDIT

Max Planck Institute for Brain Research / G. Laurent; Hain et al. Science 2022 DOI: 10.1126/science.abp8202

Transcriptomic comparisons reveal shared classes of neuron types

“We profiled over 280,000 cells from the brain of Pogona and identified 233 distinct types of neurons”, explains David Hain, graduate student in the Laurent Lab and co-first author of the study. “Computational integration of our data with mouse data revealed that these neurons can be grouped transcriptomically in common families, that probably represent ancestral neuron types”, says Hain. In addition, he found that that most areas of the brain contain a mix of common (ancient) and specific (novel) neuron types, as shown in the figure below.

Graduate student Tatiana Gallego-Flores used histological techniques to map these cell types throughout the dragon brain and observed (among other) that neurons in the thalamus could be grouped in two transcriptomic and anatomical domains, defined by their connectivity to other regions of the brain. Because these connected regions have had different fates in mammals and in reptiles, one of these regions being highly divergent, comparing the thalamic transcriptomes of these two domains proved to be very interesting. Indeed, it revealed that transcriptomic divergence matched that of the target regions.

“This suggests that neuronal transcriptomic identity somewhat reflects, at least in part, the long-range connectivity of a region to its targets. Since we do not have the brains of ancient vertebrates, reconstructing the evolution of the brain over the past half billion years will require connecting together very complex molecular, developmental, anatomical and functional data in a way that is self-consistent. We live in very exciting times, because this is becoming possible”, concludes Laurent.

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JOURNAL

Science

DOI

10.1126/science.abp8202 

METHOD OF RESEARCH

Meta-analysis

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Molecular diversity and evolution of neuron types in the amniote brain.

From wound healing to regeneration

Heidelberg scientists demonstrate how injuries are converted to regeneration signals at the molecular level

Peer-Reviewed Publication

HEIDELBERG UNIVERSITY

The phenomenon of regeneration was discovered over 200 years ago in the freshwater polyp Hydra. Until now, however, it was largely unclear how the orderly regeneration of lost tissues or organs is activated after injury. In its investigations of Hydra, an interdisciplinary research team at Heidelberg University was able to show how wound healing signals released upon injury are converted into specific signals of pattern formation and cell differentiation. Essential components are the mitogen-activated protein kinases (MAPK) and the Wnt signalling pathway – molecular mechanisms that have remained relatively unchanged throughout evolution.

The ability to regenerate varies widely in animals. Most mammals and vertebrates have only limited regeneration capacity, while basal and simple animals that emerged early in evolution, like cnidarians and planarians, can regenerate their whole body. In all cases, the process of regeneration begins with wound healing. The cells at the site of injury proliferate and form an undifferentiated mass – a blastema – from which the missing structures are re-patterned. This activates genetic processes that also control embryonic development. To determine the molecular mechanisms involved, the research team led by Prof. Dr Thomas W. Holstein studied the freshwater polyp Hydra to understand the basic features of this activation of regeneration.

The core of their investigations is the doctoral thesis of Anja Tursch. She repeated the key experiment of Geneva naturalist Abraham Trembley (1710 to 1784) which led him to discover the regeneration phenomenon. The Hydra polyp is bisected, prompting the upper half to regenerate a new “head” and the lower half a new “foot” – hence totally different body parts can grow from the exact same tissue at the cut surface in the middle. Building on their previous work on Hydra regeneration, the researchers at the Centre for Organismal Studies (COS) of Heidelberg University have now shown how this is possible.

Regardless of where it occurs, any damage triggers nonspecific signals for an injury response, i.e. wound healing, via calcium ions and the production of reactive oxygen species. The signals are transmitted intracellularly by three mitogen-activated protein kinases – p38, JNKs, and ERK. Activation of these three molecules is required for both head and foot regeneration. Wnt signalling pathways are then activated that are important during embryonic development for the formation of rudimentary organs and the body axis. The generic signals of wound healing are thus transferred into position-specific signals of patterning and cell differentiation for regeneration.

“Our experiments show that the Wnt signalling pathway is a main component of the initially general injury response and, depending on signal strength, directs the tissue toward head or foot development,” explains Prof. Holstein. This is why, in the case of MAPK inhibition, the otherwise absent regeneration can be induced by artificially generated, recombinant Wnt proteins. “It was also surprising that in middle body parts that had both head and foot removed, heads can be induced at both ends in this way,” adds Dr Suat Özbek, a member of Prof. Holstein’s “Molecular Evolution and Genomics” research group at the COS.

Wnt/β-catenin, one piece of the Wnt signalling pathway, was already known to encode positional information for new head structure formation. In collaboration with mathematicians led by Prof. Dr Anna Marciniak-Czochra, the research team of Prof. Holstein and Dr Özbek developed a model that shows how basal positional information in the tissue transforms the initially undifferentiated injury response into a differential patterning process via the Wnt signalling pathway. “Because MAPKs and Wnts are highly evolutionarily conserved, this mechanism is likely deeply embedded in our genome, which is important for regenerative processes in vertebrates and mammals as well,” stresses Thomas Holstein.

The research was done under the auspices of the “Mechanisms and Functions of Wnt Signaling” Collaborative Research Centre (CRC 1324) funded by the German Research Foundation. The results were published in the “Proceedings of the National Academy of Sciences” (PNAS).

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JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2204122119 

ARTICLE TITLE

Injury-induced MAPK activation triggers body axis formation in Hydra by default Wnt signaling

Researchers propose new and more effective model for automatic speech recognition

Consumer-focused new framework improves automatic speech recognition by including context information, an improved solution for video conferencing and live interviews

Peer-Reviewed Publication

TSINGHUA UNIVERSITY PRESS

 

IMAGE: THE PHONETIC-SEMANTIC PRE-TRAINING (PSP) FRAMEWORK USES “NOISE-AWARE CURRICULUM” LEARNING TO EFFECTIVELY IMPROVE THE PERFORMANCE OF ASR IN NOISY ENVIRONMENTS. INTEGRATING WARM-UP, SELF-SUPERVISED LEARNING, AND FINE-TUNING. view more 

CREDIT: CAAI ARTIFICIAL INTELLIGENCE RESEARCH, TSINGHUA UNIVERSITY PRESS

Popular voice assistants like Siri and Amazon Alexa have introduced automatic speech recognition (ASR) to the wider public. Though decades in the making, ASR models struggle with consistency and reliability, especially in noisy environments. Chinese researchers developed a framework that effectively improves the performance of ASR for the chaos of everyday acoustic environments.

 

Researchers from the Hong Kong University of Science and Technology and WeBank proposed a new framework - phonetic-semantic pre-training (PSP) and demonstrated the robustness of their new model against synthetic highly noisy speech datasets.

 

Their study was published in CAAI Artificial Intelligence Research on Aug. 28.

 

“Robustness is a long-standing challenge for ASR,” said Xueyang Wu from the Hong Kong University of Science and Technology Department of Computer Science and Engineering. “We want to increase the robustness of the Chinese ASR system with a low cost.”

 

ASR uses machine-learning and other artificial intelligence techniques to automatically translate speech into text for uses like voice-activated systems and transcription software. But new consumer-focused applications increasingly call for voice recognition to work better — handle more languages and accents, and perform more reliably in real-life situations like video conferencing and live interviews.

 

Traditionally, training the acoustic and language models that comprise ASR requires large amounts of noise-specific data, which can be time- and cost-prohibitive.

 

The acoustic model (AM) turns words into a “phones,” which are sequences of basic sounds. The language model (LM) decodes phones into natural-language sentences, usually with a two-step process: a fast but relatively weak LM generates a set of sentence candidates, and a powerful but computationally expensive LM selects the best sentence from the candidates.

 

“Traditional learning models are not robust against noisy acoustic model outputs, especially for Chinese polyphonic words with identical pronunciation,” Wu said. “If the first pass of the learning model decoding is incorrect, it is extremely hard for the second pass to make it up.”

 

The newly proposed framework PSP makes it easier to recover misclassified words. By pre-training a model that translates the AM outputs directly to sentence along with the full context information, researchers can help the LM efficiently recover from the noisy outputs of the AM.

 

The PSP framework allows the model to improve through a pre-training regime called noise-aware curriculum that gradually introduces new skills, starting easy and gradually moving into more complex tasks.

 

“The most crucial part of our proposed method, Noise-aware Curriculum Learning, simulates the mechanism of how human beings recognize a sentence from noisy speech,” Wu said.  

 

Warm-up is the first stage, where researchers pre-train a phone-to-word transducer on a clean phone sequence, which is translated from unlabeled text data only — to cut back on the annotation time. This stage “warms up” the model, initializing the basic parameters to map phone sequences to words.

 

In the second stage, self-supervised learning, the transducer learns from more complex data generated by self-supervised training techniques and functions. Finally, the resultant phone-to-word transducer is fine-tuned with real-world speech data.

 

The researchers experimentally demonstrated the effectiveness of their framework on two real- life datasets collected from industrial scenarios and synthetic noise. Results showed that the PSP framework effectively improves the traditional ASR pipeline, reducing the relative character error rates by 28.63% for the first dataset and 26.38% for the second.

 

In next steps, researchers will investigate more effective PSP pre-training methods with larger unpaired datasets, seeking to maximize the effectiveness of pretraining for noise-robust LM.

 

Other contributors include Rongzhong Lian, Di Jiang, Yuanfeng Song, Weiwei Zhao, and Qian Xu, and Qiang Yang from WeBank Co. Ltd. Qian Xu and Qiang Yang are also affiliated with The Hong Kong University of Science and Technology.

 

CAAI Artificial Intelligence Research is a new journal jointly sponsored by Chinese Association for Artificial Intelligence (CAAI) and Tsinghua University. This is the first paper published in the journal.

 

About CAAI Artificial Intelligence Research 

 

CAAI Artificial Intelligence Research is a peer-reviewed journal jointly sponsored by Chinese Association for Artificial Intelligence (CAAI) and Tsinghua University. The journal aims to reflect the state-of-the-art achievement in the field of artificial intelligence and its application, including knowledge intelligence, perceptual intelligence, machine learning, behavioral intelligence, brain and cognition, and AI chips and applications, etc. Original research and review articles from all over the world are welcome for rigorous peer-review and professional publishing support.

 

About SciOpen 

 

SciOpen is a professional open access resource for discovery of scientific and technical content published by the Tsinghua University Press and its publishing partners, providing the scholarly publishing community with innovative technology and market-leading capabilities. SciOpen provides end-to-end services across manuscript submission, peer review, content hosting, analytics, and identity management and expert advice to ensure each journal’s development by offering a range of options across all functions as Journal Layout, Production Services, Editorial Services, Marketing and Promotions, Online Functionality, etc. By digitalizing the publishing process, SciOpen widens the reach, deepens the impact, and accelerates the exchange of ideas.

 

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DOI

10.26599/AIR.2022.9150001 

ARTICLE TITLE

A Phonetic-Semantic Pre-Training Model for Robust Speech Recognition

EP-WXT pathfinder catches first wide-field snapshots of X-ray universe

Reports and Proceedings

CHINESE ACADEMY OF SCIENCES HEADQUARTERS

 

IMAGE: EP-WXT PATHFINDER TARGETS A REGION OF THE GALACTIC CENTER AT THE CORE OF THE MILKY WAY. INSET SHOWS THE 800-SECOND TIME-LAPSE PHOTOGRAPH FROM THE OBSERVATION. view more 

CREDIT: CAS/ESA/GAIA/DPAC

EP-WXT Pathfinder, the experimental version of a module that will eventually be part of the wide-field X-ray telescope (WXT) aboard the astronomical satellite Einstein Probe (EP), released its first results Aug. 27 from an earlier test flight. These include an 800-second X-ray time-lapse photograph of a region of the Galactic center, a dense area at the core of our home galaxy, the Milky Way. 

These mark the first wide-field X-ray snapshots of our universe available to the public so far, captured by the first truly wide-field X-ray focusing imaging telescope ever flown in space.

The results were reported by scientists from the Chinese Academy of Sciences (CAS) at the Second China Space Science Assembly held in Taiyuan, China.

Since the first detection of X-ray signals from the depths of the universe 60 years ago, no wide-field X-ray focusing telescope has been available for X-ray surveys and monitoring until Pathfinder.

The Pathfinder was sent into orbit to verify the module's in-orbit performance. The experimental journey is meant to pave the way for the future in-orbit science operation of EP as it makes observations in the soft X-ray waveband.

EP will explore open questions in time-domain astrophysics through observation of transients. The mission is sponsored by CAS in cooperation with the European Space Agency (ESA) and the Max Planck Institute for Extraterrestrial Physics and is expected to fly by the end of 2023.

The WXT test module covers a field of view up to 340 square degrees (18.6°×18.6°) wide, which makes it the first truly wide-field X-ray focusing imaging telescope. X-ray imaging by bending light rays (focusing) is notoriously difficult due to the high energy of X-ray photons; and it is even more difficult to obtain clear images from a wide field of view. Thanks to a state-of-the-art technology called lobster-eye micropore optics, the test module boasts a field of view at least 100 times those of other focusing X-ray imagers. The complete WXT to fly aboard EP will be composed of 12 such identical modules, covering a field of view up to 3,600 square degrees wide.

During the test flight, Pathfinder conducted a total of four days of in-orbit experimental observations and obtained authentic X-ray spectra and images based on real measurements.

The key components of Pathfinder include the X-ray imaging mirror assembly, which features an array of 36 micropore lobster-eye plates and a focal-plane detector composed of four sets of large-format imaging sensors.

Even though these results are still preliminary and extensive data processing must be done, the test flight demonstrates that even a one-shot observation can cover X-ray sources from all directions within the observed patch of sky, including stellar-mass black holes and neutron stars. The observation also captured the brightening of X-rays from a binary system containing a neutron star. The data from these observations provide information about how X-ray radiation from such celestial bodies changes over time, as well as the X-ray spectra of these celestial bodies. The images and spectra resulting from the test observations are highly consistent with simulations.

The instrument also targeted a number of other X-ray sources, including the Large Magellanic Cloud (LMC), one of our neighboring galaxies. The results demonstrate that even a one-shot observation can cover the whole of this galaxy, detecting multiple X-ray sources, including black holes, neutron stars and supernova remnants. The instrument's clear imaging of a distant quasar, 3C 382, at a distance of 810 million light-years, reveals its capacity to detect relatively faint X-ray sources. In its future observations, the imager is expected to effectively monitor the X-ray variability of celestial bodies and discover new transient sources.

According to Dr. YUAN Weimin, principal investigator (PI) of the EP mission and researcher at the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), initial results show that "the instrument operates smoothly" and meets EP WXT module requirements. "It's exciting to see the decade-long effort bearing its first fruit," he smiled.

Other researchers involved with the EP mission were also satisfied.

Dr. ZHANG Chen, PI of the WXT mirror assembly, said the results promise "abundant, high-quality data" after the probe is launched.

Prof. Paul O'Brien, ESA-appointed scientist for the EP mission and researcher at the University of Leicester, said the results are "really impressive."

"We have been waiting for a true wide-field, soft X-ray imager for many decades, so it is wonderful to see the WXT test module in flight on EP-WXT Pathfinder," said Prof. Richard Willingale, Prof. O'Brien's colleague at the University of Leicester.

The preliminary X-ray “time-lapse photograph” (right) in 0.5–4 keV band as the result from a 700-second one-shot observation on the Large Magellanic Cloud (LMC), our neighbor galaxy, in comparison with the DSS optical image of LMC.

CREDIT

CAS/DSS

CAPTION

X-ray image of the Cygnus Loop nebula (2.5-degree diameter) obtained with several observations totaling 2,400 seconds.

CREDIT

CAS

Climate anxiety an important driver for climate action – new study

Peer-Reviewed Publication

UNIVERSITY OF BATH

The first-ever detailed study of climate anxiety among the UK adult population suggests that whilst rates are currently low, people’s fears about the future of the planet might be an important trigger for action when it comes to adapting our high-carbon lifestyles to become more environmentally friendly.

Interest in climate or eco-anxiety – characterised by the American Psychological Association as the chronic fear of environmental doom that comes from observing the impacts of climate change – has risen over recent years. A high-profile University of Bath study in 2021 found it to be particularly prevalent among young people right across the world. 

This latest study, led by a team from the Centre for Climate Change and Social Transformations, also based at the University of Bath, sought the views of 1,338 UK adults over two time points (in 2020 and 2022) to delve deeper into the prevalence of climate anxiety, factors that predict it, and whether it could predict individual behavioural changes and climate action.

Despite over three-quarters of the UK public saying they are worried about climate change, only 4.6% of the public reported experiencing climate anxiety in 2022 (only fractionally higher than in 2020, when 4% reported this). Younger people and those with higher generalised anxiety were more likely to experience eco-anxiety.

However, climate anxiety was not always a negative; for many it could be a motivating force for taking action to reduce emissions. This included saving energy, buying second-hand, borrowing, renting, or repurposing items. Lifestyle changes such as cutting down on red meat were not related to climate anxiety, despite being highly effective for reducing emissions.

Significantly, the study found that media exposure – for example TV images of raging storms or heatwaves - rather than direct, personal experiences of climate impacts predicted climate anxiety. The authors say there are important implications of these findings for organisations responsible for communicating climate change.

The study published in the Journal of Environmental Psychology coincides with a new briefing paper from the Centre for Climate Change & Social Transformations focused on UK public preferences for low-carbon lifestyles. Its analysis suggests that lifestyle changes (for example, reducing car use or eating less meat), are increasingly seen as both feasible and desirable.

Environmental psychologist at the University of Bath, Professor Lorraine Whitmarsh MBE, led the study. She explained: “With increasing media coverage of climate impacts, such as droughts and fires in the UK and devastating flooding in Pakistan, climate anxiety may well increase. Our findings suggest this can spur some people to take action to help tackle the issue – but we also know there are barriers to behaviour change that need to be addressed through more government action.”

In the paper, the authors emphasise the importance of the media as a motivating force for the lifestyle changes required as we decarbonise. They suggest that the media and public discourse about climate anxiety has the power to create a positive vision for a greener, cleaner future which is significantly less dependent on fossil fuels. 

Lois Player, co-author of the study also from the Department of Psychology at the University of Bath, explained: “Our results suggest that the media could play an important role in creating positive pro-environmental behaviour change, but only if they carefully communicate the reality of climate change without inducing a sense of hopelessness.”  

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JOURNAL

Journal of Environmental Psychology

DOI

10.1016/j.jenvp.2022.101866 

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Climate anxiety: What predicts it and how is it related to climate action?