Friday, September 03, 2021

 

Natural exposure to wildfire smoke increased pregnancy loss in rhesus macaques


Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - DAVIS

Natural Exposure to Wildfire Smoke Increased Pregnancy Loss in Rhesus Macaques 

IMAGE: RHESUS MACAQUE MOTHERS WITH INFANTS AT THE CALIFORNIA NATIONAL PRIMATE RESEARCH CENTER. THE 2018 BREEDING SEASON COINCIDED WITH THE PEAK OF WILDFIRE SMOKE FROM THE CAMP FIRE, WITH A REDUCED RATE OF LIVE BIRTHS THE FOLLOWING SPRING. view more 

CREDIT: CALIFORNIA NATIONAL PRIMATE RESEARCH CENTER

Rhesus macaques naturally exposed to wildfire smoke early in pregnancy had an increased rate of miscarriage, according to new research from the California National Primate Research Center at the University of California, Davis. The work is published online in the journal Reproductive Toxicology.

In November 2018, smoke from the Camp Fire in Paradise, California, about 100 miles away blanketed the Davis area. Air quality exceeded national limits and reached unhealthy levels. 

The disaster coincided with the peak of breeding season for the center’s colony of rhesus macaques. Hundreds of animals at the center live in outdoor corrals in large family groups. Breeding typically takes place in the fall, with offspring born in spring after an average gestation of 166 days. 

Bryn Willson, an OB/GYN resident at UC Davis Health, began the research project in collaboration with Professor Kent Pinkerton, UC Davis Center for Health and Environment, and Bill Lasley, professor emeritus at the Center for Health and Environment and School of Veterinary Medicine, and colleagues. 

The researchers randomly selected 66 female animals of reproductive age from the colony to follow for pregnancy outcomes. They were compared to pregnancies from nine previous years. 

Of the 66, 45 became pregnant while levels of smoke pollution were high, based on measurements of small particles (PM2.5). Twenty animals conceived after air quality had returned to normal levels in December. One animal did not become pregnant. 

There were 37 live births among the 45 animals exposed to wildfire smoke during early pregnancy, a rate of 82%. The average rate of live births in the previous nine years, with normal air quality, varied from 86% to 93%. The 20 animals not exposed to smoke during pregnancy all had successful live births. 

“There was an increase in miscarriage among the primates exposed to wildfire smoke during the 2018-2019 breeding season compared to primates from the nine preceding breeding seasons,” Willson said. Most pregnancies did result in a successful birth, she noted. 

Although there are some important differences, rhesus macaques are considered a useful animal model for human pregnancy. Previous studies have associated poor air quality with reduced birth weight in human babies but not with increased risk of miscarriage. 

Pregnant women a sensitive group for air quality

Pregnant women should consider themselves as being a “sensitive group” for poor air quality, she said, similar to people with asthma or other lung conditions. Willson recommended minimizing time spent outdoors when the air is unhealthy for sensitive groups, and wearing a mask that can filter fine particles. 

The study did not establish a cause for the increased rate of miscarriage, but air sampling showed that Camp Fire smoke contained both oxidized organic material — probably from burning vegetation — and phthalates, likely from burning plastic in houses or other human-made structures. Phthalates are known to be endocrine disruptors, Willson said. 

High levels of small particles (PM2.5) are known to increase morbidity overall. Previous work from the California National Primate Research Center, led by Professor Lisa Miller, UC Davis School of Veterinary Medicine, has shown that natural exposure of infant macaques to wildfire smoke has long-term effects on their lungs comparable to chronic obstructive pulmonary disease, or COPD, in humans.

###

Additional co-authors on the study were: Nancy Gee at the Center for Health and Environment and California National Primate Research Center; Lijuan Li and Qi Zhang, UC Davis Department of Environmental Toxicology; and Neil Willits, Department of Statistics. Willson is currently a fellow at Cedars-Sinai Medical Center, Los Angeles. 

Funding was provided by the National Institute for Occupational Safety and Health and the National Institute for Environmental Health Sciences.

 AS IF WE DID NOT HAVE ENOUGH TO WORRY ABOUT DEPT.

Study reveals threat of catastrophic supervolcano eruptions ever-present


Peer-Reviewed Publication

CURTIN UNIVERSITY

 

Curtin scientists are part of an international research team that studied an ancient supervolcano in Indonesia and found such volcanoes remain active and hazardous for thousands of years after a super-eruption, prompting the need for a rethink of how these potentially catastrophic events are predicted.

Associate Professor Martin Danišík, lead Australian author from the John de Laeter Centre based at Curtin University, said supervolcanoes often erupted several times with intervals of tens of thousands of years between the big eruptions but it was not known what happened during the dormant periods.

“Gaining an understanding of those lengthy dormant periods will determine what we look for in young active supervolcanoes to help us predict future eruptions,” Associate Professor Danišík said.

“Super-eruptions are among the most catastrophic events in Earth’s history, venting tremendous amounts of magma almost instantaneously. They can impact global climate to the point of tipping the Earth into a ‘volcanic winter’, which is an abnormally cold period that may result in widespread famine and population disruption.

“Learning how supervolcanoes work is important for understanding the future threat of an inevitable super-eruption, which happen about once every 17,000 years.”

Associate Professor Danišík said the team investigated the fate of magma left behind after the Toba super-eruption 75,000 years ago, using the minerals feldspar and zircon, which contain independent records of time based on the accumulation of gasses argon and helium as time capsules in the volcanic rocks.

“Using these geochronological data, statistical inference and thermal modelling, we showed that magma continued to ooze out within the caldera, or deep depression created by the eruption of magma, for 5000 to 13,000 years after the super-eruption, and then the carapace of solidified left-over magma was pushed upward like a giant turtle shell,” Associate Professor Danišík said.

“The findings challenged existing knowledge and studying of eruptions, which normally involves looking for liquid magma under a volcano to assess future hazard. We must now consider that eruptions can occur even if no liquid magma is found underneath a volcano - the concept of what is ‘eruptible’ needs to be re-evaluated.

 “While a super-eruption can be regionally and globally impactful and recovery may take decades or even centuries, our results show the hazard is not over with the super-eruption and the threat of further hazards exists for many thousands of years after.

“Learning when and how eruptible magma accumulates, and in what state the magma is in before and after such eruptions, is critical for understanding supervolcanoes.”

The study was led by researchers from Oregon State University, and co-authored by researchers from Heidelberg University, the Geological Agency of Indonesia, and by Dr Jack Gillespie from Curtin’s School of Earth and Planetary Sciences and The Institute for Geoscience Research (TIGeR), Curtin’s flagship earth sciences research institute.

The paper, ‘Resurgence initiation and subsolidus eruption of cold carapace of warm magma at Toba Caldera, Sumatra’, was published in journal Nature - Earth and Environmental Sciences.

 

Cost, bleeding cited as major reasons for not taking newer anti-coagulant as prescribed


Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - LOS ANGELES HEALTH SCIENCES

BACKGROUND

Direct-acting oral anticoagulants such as apixaban are the most widely used medications of this type in people with atrial fibrillation, yet 26% to 45% of people fail to properly adhere to them.

 

METHOD

The researchers interviewed 42 UCLA and UCSF adults with atrial fibrillation who had been prescribed apixaban between August 2019 and July 2020 but had reported nonadherence to the medication. Of those people, 83% stopped, skipped or decreased dosing and 17% percent never took the medication.

 

FINDINGS

People with atrial fibrillation, or irregular heartbeat, who were prescribed the direct-acting oral anticoagulant apixaban cited six reasons for failing to adhere to their prescriptions:

 

  • Cost - some felt that the out-of-pocket cost was too high, physicians were not helpful in addressing their cost concerns, or physician-provided coupons did not work
  • Bleeding - some people worried about major or minor bleeding, including during activities such as hiking or construction work
  • Lack of Symptoms – some believed that they did not need to take the medication if they did not experience symptoms or the symptoms were periodic, with some believing their stroke risk was small.
  • Safe to skip doses – some believed the medication was still effective when they reduced doses from twice daily to once, and others believed that their physician gave tacit approval to occasional nonadherence when told to stop taking the medication a few days before surgery or if they experienced excess bleeding.
  • Confusion about effects - some believed that the medication was intended to reduce atrial fibrillation symptoms and were puzzled when they continued experiencing them, or felt few effects from it and wanted measurable lab results.
  • Incomplete or discordant communication – some did not tell their physician about their nonadherence, or said they were not asked about it, and others were confused by differing physician opinions.

 

IMPACT

The findings are useful in devising strategies to increase adherence to the medication.

 

AUTHORS

Dr. Derjung Tarn and Kevin Shih of UCLA, and Dr. Janice Schwartz of UCSF.

 

JOURNAL

The peer-reviewed Journal of the American Geriatrics Society published this study.

 

FUNDING

Bristol-Myers Squibb and Pfizer funded this study.

 

Media Contact

Enrique Rivero

erivero@mednet.ucla.edu

 

NTU Singapore and Hyundai Motor Group to develop advanced solutions for electric vehicle manufacturing

Business Announcement

NANYANG TECHNOLOGICAL UNIVERSITY

NTU Singapore and Hyundai Motor Group to develop advanced solutions for electric vehicle manufacturing 

IMAGE: (L-R) HYUNDAI MOTOR GROUP SENIOR VICE PRESIDENT HONG BUM JUNG, PRESIDENT & CHIEF INNOVATION OFFICER OF HYUNDAI MOTOR GROUP, YOUNGCHO CHI, NTU PRESIDENT PROFESSOR SUBRA SURESH AND PRESIDENT & NTU SENIOR VICE PRESIDENT (RESEARCH) PROFESSOR LAM KHIN YONG WERE IN ATTENDANCE AT THE SIGNING CEREMONY HELD AT NTU ON 1 SEP 2021. view more 

CREDIT: NTU SINGAPORE

Nanyang Technological University, Singapore (NTU Singapore) and Hyundai Motor Group (the Group) have entered into an agreement to conduct a series of joint research projects focusing on advanced solutions for the manufacturing of electric vehicles (EVs) and to develop future mobility solutions.

Focusing on Industry 4.0 technologies, these projects aim to develop solutions that can transform conventional car manufacturing facilities into state-of-the-art factories of the future.

Four pilot projects on artificial intelligence (AI) and additive manufacturing (3D printing) will be explored in the initial stage which starts this month.

To ensure the quality of Battery Electric Vehicles (vehicles powered entirely by batteries), one of the projects aims to develop machine learning algorithms for vehicle image processing. The application of an AI-based image processing sensor in the plant will help detect defects and anomalies during the manufacturing process, ensuring high levels of safety and reliability of the final product.

Another project will look at integrating 3D printing in EV manufacturing. Researchers will explore how 3D printers can be effectively used in the customisation of automotive components, and how they may be implemented in a smart factory operation. This will support the smart manufacturing vision, where customers can order and customise a car model to their taste.

NTU Senior Vice President (Research) Professor Lam Khin Yong and Hyundai Motor Group Senior Vice President Hong Bum Jung signed the collaboration agreement at a ceremony held at NTU on Wednesday (1 Sep). It was witnessed by NTU President Professor Subra Suresh and President & Chief Innovation Officer of Hyundai Motor Group, Youngcho Chi.

NTU President Professor Subra Suresh said, “The partnership between NTU and Hyundai Motor Group provides one more example of how our close collaboration with industry plays an important role in developing relevant solutions to address real world issues. This is in line with the NTU 2025 strategic plan, which aims to address some of the grand challenges facing humanity. This collaboration with Hyundai Motor Group will build on NTU’s core strengths, in areas such as additive manufacturing, AI, autonomous and electric vehicles, and big data to bring about benefits to the automotive industry, Singapore and the global society.”

The signing ceremony follows an earlier announcement made in October 2020 during the virtual groundbreaking ceremony for Hyundai Motor Group Innovation Centre in Singapore (HMGICS). During the ceremony, NTU was announced as the first academic research partner for the Group’s HMGICS initiative.

President & Chief Innovation Officer of Hyundai Motor Group, Youngcho Chi said, “HMGICS aims to build an ecosystem for the future mobility industry based on open innovation. We are going to strengthen collaboration with NTU and develop advanced solutions to revolutionise future mobility value chain going forward.”

The HMGICS is an open research facility for the Group’s future mobility research and development. Located at Singapore’s Jurong Innovation District, the construction of HMGICS is expected to be completed at the end of 2022. The facility will only be five- minute drive from the NTU Smart Campus, which is a living testbed of innovative digital and tech-enabled solutions.

Future initiatives to nurture talent

Aside from research and development projects, the latest agreement between NTU and Hyundai Motor Group also paves the way for future collaborations aimed at nurturing talent in the automotive sector.

For example, the partners will launch 3D printing competitions, focusing on the innovative use of the technology in automotive engineering. The aim is to drive interest in EV manufacturing and to encourage undergraduates to imagine what future mobility could look like. At the same time, the competition will be an opportunity for people to gain insights into the benefits of 3D printing technology in EVs.

NTU students and researchers will also benefit from joint educational seminars, which will provide a platform for industrial experts from the Group and NTU academics to exchange ideas and build their skills.
 

***END***

 

Improving buyer-freelancer communications in the gig economy

News from the Journal of Marketing

Peer-Reviewed Publication

AMERICAN MARKETING ASSOCIATION

Researchers from University of Melbourne, Vrije Universiteit, Babson College, and University of Surrey published a new paper in the Journal of Marketing that provides generalized communication principles, and examples of how to apply them, for successful bid writing in the gig economy.

The study, forthcoming in the Journal of Marketing, is titled “Communication in the Gig Economy: Buying and Selling in Online Freelance Marketplaces” and is authored by Stephan Ludwig, Dennis Herhausen, Dhruv Grewal, Liliana Bove, Sabine Benoit, Ko de Ruyter, and Peter Urwin.

The gig economy is global and growing exponentially. In the US alone, millions of buyers and freelancers in freelance marketplaces contribute $1.2 trillion in value to the economy. Online freelance marketplaces, such as Upwork, Fiverr, PeoplePerHour, and Toptal have prompted massive transformations of work. In relatively anonymous interactions via text-based messages, buyers first post call-for-bids for their gigs. In turn, interested freelancers submit bids to offer their services.

Yet, while 59% of U.S. companies use a flexible workforce to some degree, more than one-third of their gigs are never filled or completed. The research team explains that “Uncertainty during these text-based interactions leads to high rates of gigs that go unfulfilled, reduced freelancers’ bid success, or less-than-optimal pricing for freelancers. Our investigation uncovers principles for writing call-for-bids and bids that manage that uncertainty and lead to greater success filling gigs and finding work.”

How Buyers Can Write a Good Call-for-Bids

Freelancers choose whether to offer their services in response to a buyer’s call for bids. The number of freelancers who respond is consequential for the buyer because attracting more bids implies a greater likelihood of finding a suitable freelancer. Here are key principles buyers can use to entice freelancers to bid: 
 
• Moderate length: While buyers may be inclined to supply as much information as possible, successful buyers keep their calls for bids moderately succinct. 

• Enough task information: Buyers should focus on providing information about the task and the required skills. Importantly, providing excessive task information is ineffective, even if it might reduce freelancers’ uncertainty. Excessive details can make the gig appear too overwhelming, restrictive, or prescriptive and thus not appealing to freelancers. 

• Limit personal information: Buyers may want to provide a lot of personal information in their call for bids. Yet, this research finds that the less buyers describe themselves (and instead focus on describing the task), the more freelancers apply. Extensive personal information provision by buyers is unusual, potentially even inappropriate, in initial online exchanges. 

• Enough concreteness: Buyers can vary the concreteness of the gig description. Greater concreteness can be more efficient because freelancers can process the information with less time and effort. Concrete terms help by making information more perceptible, precise, and specific. Only a moderate to high level of concreteness is attractive to freelancers, though. Notably, if buyers are too concrete in their calls for bids, the task might appear narrow, which reduces the gig’s appeal.

• Limit affective intensity: Affective intensity reflects the proportion of emotive terms included in a message. Greater intensity tends to be more persuasive, memorable, and accessible than communication that is unemotional. However, calls for bids are more effective if they are formulated relatively impassively. Overly enthusiastic project descriptions, for example, might raise freelancers’ suspicion that the project is too good to be true.

How Freelancers Can Write Good Bids

Buyers also face uncertainty when deciding whom to hire and how much to pay. By managing these uncertainties through their bids, freelancers can affect their chances of winning bids and their price premiums. Freelancers are not necessarily natural marketers, but here is what they can do in their bid formulations to increase their marketability:
 
• Stars matter, communication too: Existing online reputation systems provide some assistance, but they also create entry barriers to new freelancers who first must earn good ratings. Fortunately, winning gigs and achieving price premiums also depend on freelancers’ communication. 

• Mimicking the buyer: In line with the mantra of adaptive selling, the call for bids provides a starting point, such that mimicking the buyer’s task information and affective intensity increases freelancers’ success—even if the buyer provides few task details or seems very impassive. 

• Personal information and concreteness: Freelancers should always offer personal information and be concrete. Even if a buyer does not provide personal information or the call is relatively abstract, freelancers’ chances of success and price premiums increase if their bids contain more personal information and are at least somewhat concrete.

• Build relationships: The strongest predictor of bid success is a preexisting buyer relationship. Thus, freelancers should focus on developing buyer relationships. 
  
This research shows that buyers and freelancers in online freelance marketplaces should carefully manage uncertainty in their communications to improve their chances of achieving success in the gig economy.

Full article and author contact information available at: https://doi.org/10.1177/00222429211030841

About the Journal of Marketing 

The Journal of Marketing develops and disseminates knowledge about real-world marketing questions useful to scholars, educators, managers, policy makers, consumers, and other societal stakeholders around the world. Published by the American Marketing Association since its founding in 1936, JM has played a significant role in shaping the content and boundaries of the marketing discipline. Christine Moorman (T. Austin Finch, Sr. Professor of Business Administration at the Fuqua School of Business, Duke University) serves as the current Editor in Chief.
https://www.ama.org/jm

About the American Marketing Association (AMA) 

As the largest chapter-based marketing association in the world, the AMA is trusted by marketing and sales professionals to help them discover what is coming next in the industry. The AMA has a community of local chapters in more than 70 cities and 350 college campuses throughout North America. The AMA is home to award-winning content, PCM® professional certification, premiere academic journals, and industry-leading training events and conferences.
https://www.ama.org

 

Researchers discover connection between brain’s opioid system and eating behavior

Peer-Reviewed Publication

UNIVERSITY OF TURKU

Brain regions 

IMAGE: BRAIN REGIONS WHERE CONNECTIONS BETWEEN THE OPIOID SYSTEM AND EATING TRIGGERED BY EXTERNAL STIMULI WERE DISCOVERED. YELLOW COLOR INDICATES A STRONGER CONNECTION. view more 

CREDIT: UNIVERSITY OF TURKU

Brain regulation of feeding behavior traits has remained incompletely understood. In their latest study, researchers at the Turku PET Centre, Finland, discovered a connection between the function of the opioid system and food craving triggered by appetitive external stimuli.

Animal studies have established that the brain’s opioid and endocannabinoid systems are important in regulating eating behavior and mediate the food reward experience. For instance, alterations in these systems’ signaling have been associated with obesity. In general, both internal signals of the body, such as fluctuation in blood sugar levels, and external stimuli, such as food advertisements, can spark an appetite in humans.

In their new study, researchers at the University of Turku, Finland, investigated the connection between the brain’s opioid and endocannabinoid signaling and different types of eating behavior. They discovered that the function of the opioid system is connected to eating triggered by external stimuli.

“The less binding sites there were for the opioids, the greater was the tendency to eat in response to external stimuli, such as seeing appetizing food. Moreover, the number of binding sites for endocannabinoids was connected to several different types of eating behavior, describes first author,” Doctoral Candidate Tatu Kantonen from the University of Turku.

According to Kantonen, the results indicate that especially the opioid system could be a potential target for anti-obesity drugs in humans.

The research data was obtained from the AIVO database hosted by the Turku PET Centre.


Icarus can fly high and save on wax too


Risk from solar flares to planes is real but not worth costly mitigation

Peer-Reviewed Publication

KYOTO UNIVERSITY

How much of a risk do solar flares pose to airline passengers and staff? 

IMAGE: A RECENT STUDY SUGGESTS THAT AIRLINE TRAVEL MAY NOT CARRY AS MUCH RADIATION RISK AS PREVIOUSLY CONJECTURED. view more 

CREDIT: NAMI KIMURA/KYOTO UNIVERSITY

Kyoto, Japan -- "Don't fly too close to the sun," said Daedalus to Icarus. Flying too high would melt the wax in his wings, while going too low would cause the sea's moisture to create drag.

Commercial flight crews do not usually appear in Greek mythology, but they have to work with the occupational hazard of aviation radiation exposure.

Aviation guidelines aim to mitigate the effects of radiation, mainly caused by galactic cosmic rays and solar energetic particles, or SEP. The fluxes in the former are stable and predictable: dose rates are no higher than 10 µSv/h at the normal flight altitude of 12 km.

But in the case of SEP, does the frequency of detected solar flares justify the costs of countermeasures? Current mitigation procedures instruct planes to lower altitude or change or cancel flight paths altogether, significantly raising expenses.

A research team led by Kyoto University's Yosuke Yamashiki set out to answer this question by assessing eight flight routes during five ground level enhancements, or GLE: unpredicted radiation spikes recorded by ground-based detectors.

"During a large solar particle event we see sudden SEP fluxes with dose rates exceeding 2 mSv/h," says Yamashiki, "but these are rare and short-lived."

Writing in the journal Scientific Reports, the researchers estimate that the maximum flight route dose and dose rate arising from major GLE events would need to exceed 1.0 mSv and 80 µSv/h, respectively, for countermeasures to be deemed necessary.

However, annual frequency estimates of GLE events of that magnitude came to only once every 47 and 17 years for maximum dose and dose rate.

So do the risks justify the costs?

"There is no denying the potentially debilitating effects of radiation exposure," continues Yamashiki, "but the data suggest that current measures may be over-compensating for the actual risks."

 

###

The paper "Probabilistic Risk Assessment of Solar Particle Events Considering the Cost of Countermeasures to Reduce the Aviation Radiation Dose" appeared 2 September 2021 in the journal Scientific Reports, with doi: 10.1038/s41598-021-95235-9

 

About Kyoto University

Kyoto University is one of Japan and Asia's premier research institutions, founded in 1897 and responsible for producing numerous Nobel laureates and winners of other prestigious international prizes. A broad curriculum across the arts and sciences at both undergraduate and graduate levels is complemented by numerous research centers, as well as facilities and offices around Japan and the world. For more information please see: http://www.kyoto-u.ac.jp/en

 

Anatomy of the impact of a protostellar jet in the Orion Nebula

Peer-Reviewed Publication

INSTITUTO DE ASTROFÍSICA DE CANARIAS (IAC)

View of HH204, a Herbig-Haro object in the Orion Nebula 

IMAGE: THE LEFT PANEL SHOWS THE ORION NEBULA OBSERVED WITH THE HUBBLE SPACE TELESCOPE, PICKING OUT THE AREA AROUND HH204. IN THE RIGHT PANEL, WE CAN SEE IN DETAIL THE STRUCTURE OF HH204 AND OF ITS APPARENT COMPANION, HH203. IN THIS PANEL, THE IMAGES BY THE HUBBLE SPACE TELESCOPE TAKEN DURING 20 YEARS AND ARTIFICIALLY HIGHLIGHTED WITH DIFFERENT COLOURS SHOW THE ADVANCE OF THE JETS OF GAS THROUGH THE ORION NEBULA. CREDIT: GABRIEL PÉREZ DÍAZ, SMM (IAC). view more 

CREDIT: CREDIT: GABRIEL PÉREZ DÍAZ, SMM (IAC).

An international team led by researchers from the Instituto de Astrofísica de Canarias (IAC) has uncovered, with an new high degree of detail, the physical and chemical effects of the impact of a protostellar jet in the interior of the Orion Nebula. The study was made using observations with the Very Large Telescope (VLT) and 20 years of images with the Hubble Space Telescope (HST). The observations show evidence of compression and heating produced by the shock front, and the destruction of dust grains, which cause a dramatic increase in the gas phase abundance of the atoms of iron, nickel, and other heavy elements in the Orion Nebula. The results were recently published in The Astrophysical Journal.

VIDEO HH204, a Herbig-Haro object in [VIDEO] | EurekAlert! Science News Releases

The Orion Nebula, one of the known and brightest objects in the night sky, is the nearest region of massive star formation to Earth, and it has a complex and extensive gas structure. Some of the newborn stars within it emit jets of gas at high speed which, when they impact their surroudings, produce shock fronts which compress and heat the nebular gas. These impact zones are bow-shaped, and are called Herbig-Haro objects, after their discoverers, the US astonomer George Herbig, and the Mexican astronomer Guillermo Haro.

These objects have been observed previously in many dark nebulae, where the cold gas is neutral, and its main source of energy is the heat generated by the shock. However, the jets of gas in the Orion Nebula are immersed in a large radiation field produced by the most massive stars in the Trapezium of Orion, situated at the centre of the nebula. Due to this radiation the gas within the shock front and also the gas compressed after it has passed through, is warm and ionized, and this allows us to measure precisely the physical conditions and the chemical composition of the jet.

The research carried out by a team of astronomers in Spain, Mexico and the United States, led by José Eduardo Méndez Delgado, a doctoral student at the IAC and the University of La Laguna (ULL), has uncovered the complex relations between the ionic abundances of the gas and its physical conditions in HH204, one of the most prominent Herbig-Haro objects in the Orion Nebula.

“Our work shows that the in the shock front of HH204 the gas abundances of heavy elements such as iron and nickel are increased by up to 350% compared to the values usually found in the Orion Nebula, and this allows us to determine the proportion of other chemical elements more accurately, which contributes to an improved knowledge of the chemical evolution in the solar neighbourhood”, explains José Eduardo Méndez Delgado, the first author of the article.

“As well as the heavy element enrichment in the gas phase, we have observed a heated post-shock zone which comprises a very small fraction of the gas, and which lets us understand the different layers of the structure of the Herbig-Haro object generated by the impact of the shock front”, says César Esteban, and IAC researcher and a co-author of the article.

“The origin of HH204 appears to be associated with one of the most brilliant and star formation rich zones of the Orion Nebula, the regions called Orion South, although there are many interactions of gas which appear to feed it from several directions”, adds William Henney, a researcher at the Institute of Radioastronomy and Astrophysics at the National Autonomous University of Mexico, and a co-author of the article.

“Thanks to the images of the Hubble Space Telescope we have shown that HH204 is propagating at an angle of 32º with the plane of the sky, which lets us observe the compression of the gas transversely as we approach the shock front”, points out Karla Arellano Córdova, a researcher at the University of Texas at Austin, and a co-author of the article.

“We have seen that the impact of these objects can be important when determining the local physical conditions in ionized nebulae. In fact, if we don’t take these effects into account we can make incorrect determinations of the chemical composition of the ionized nebulae, which are fundamental techniques for understanding the chemical evolution of the Universe”, sums up Jorge García Rojas, an IAC researcher and a co-author of the article.

Article: Méndez-Delgado, J. E.; Henney, W. J.; Esteban, C.; García-Rojas, J.; Mesa-Delgado, A. & Arellano-Córdova, K. Z. “Photoionized Herbig-Haro objects in the Orion Nebula through deep high-spectral resolution spectroscopy II: HH204”. The Astrophysical Journal. DOI: https://iopscience.iop.org/article/10.3847/1538-4357/ac0cf5#artAbst

- Arxiv: https://arxiv.org/abs/2106.08667