In world first, scientists demonstrate continuous-wave lasing of deep-ultraviolet laser diode at room temperature

Peer-Reviewed Publication

NAGOYA UNIVERSITY

 

IMAGE: RESEARCHERS THAT SUCCESSFULLY CONDUCTED THE WORLD'S FIRST ROOM-TEMPERATURE CONTINUOUS-WAVE LASING OF A DEEP-ULTRAVIOLET LASER DIODE view more 

CREDIT: 2022 ASAHI KASEI CORP. AND NAGOYA UNIVERSITY

A research group led by 2014 Nobel laureate Hiroshi Amano at Nagoya University's Institute of Materials and Systems for Sustainability (IMaSS) in central Japan, in collaboration with Asahi Kasei Corporation, has successfully conducted the world's first room-temperature continuous-wave lasing of a deep-ultraviolet laser diode (wavelengths down to UV-C region). These results, published in Applied Physics Letters, represent a step toward the widespread use of a technology with the potential for a wide range of applications, including sterilization and medicine.

 

Since they were introduced in the 1960s, and after decades of research and development, successful commercialization of laser diodes (LDs) was finally achieved for a number of applications with wavelengths ranging from infrared to blue-violet. Examples of this technology include optical communications devices with infrared LDs and blue-ray discs using blue-violet LDs. However, despite the efforts of research groups around the world, no one could develop deep ultraviolet LDs. A key breakthrough only occurred after 2007 with the emergence of technology to fabricate aluminum nitride (AlN) substrates, an ideal material for growing aluminum gallium nitride (AlGaN) film for UV light-emitting devices.

 

Starting in 2017, Professor Amano's research group, in cooperation with Asahi Kasei, the company that provided 2-inch AlN substrates, began developing a deep-ultraviolet LD. At first, sufficient injection of current into the device was too difficult, preventing further development of UV-C laser diodes. But in 2019, the research group successfully solved this problem using a polarization-induced doping technique. For the first time, they produced a short-wavelength ultraviolet-visible (UV-C) LD that operates with short pulses of current. However, the input power required for these current pulses was 5.2 W. This was too high for continuous-wave lasing because the power would cause the diode to quickly heat up and stop lasing.

 

But now, researchers from Nagoya University and Asahi Kasei have reshaped the structure of the device itself, reducing the drive power needed for the laser to operate at only 1.1W at room temperature. Earlier devices were found to require high levels of operating power because of the inability of effective current paths due to crystal defects that occur at the laser stripe. But in this study, the researchers found that the strong crystal strain creates these defects. By clever tailoring of the side walls of the laser stripe, they suppressed the defects, achieving efficient current flow to the active region of the laser diode and reducing the operating power.

 

Nagoya University’s industry-academic cooperation platform, called the Center for Integrated Research of Future Electronics, Transformative Electronics Facilities (C-TEFs), made possible the development of the new UV laser technology. Under C-TEFs, researchers from partners such as Asahi Kasei share access to state-of-the-art facilities on the Nagoya University campus, providing them with the people and tools needed to build reproducible high-quality devices.  Zhang Ziyi, a representative of the research team, was in his second year at Asahi Kasei when he became involved in the project’s founding. “I wanted to do something new,” he said in an interview. “Back then everyone assumed that the deep ultraviolet laser diode was an impossibility, but Professor Amano told me, ‘We have made it to the blue laser, now is the time for ultraviolet’.”

 

This research is a milestone in the practical application and development of semiconductor lasers in all wavelength ranges. In the future, UV-C LDs could be applied to healthcare, virus detection, particulate measurement, gas analysis, and high-definition laser processing. “Its application to sterilization technology could be groundbreaking,” Zhang said. “Unlike the current LED sterilization methods, which are time-inefficient, lasers can disinfect large areas in a short time and over long distances”. This technology could especially benefit surgeons and nurses who need sterilized operating rooms and tap water.

  

In world first, scientists demonstrate continuous-wave lasing of deep-ultraviolet laser diode at room temperature

CREDIT

Issey Takahashi

The successful results have been reported in two papers in Applied Physics Letters as below.

Title: Key temperature-dependent characteristics of AlGaN-based UV-C laser diode and demonstration of room-temperature continuous-wave lasing
Authors: Ziyi Zhang, Maki Kushimoto, Akira Yoshikawa, Koji Aoto, Chiaki Sasaoka, Leo J. Schowalter, and Hiroshi Amano
DOI: 10.1063/5.0124480 (to be published online on November 28, 2022)
Nagoya University Institutional Repository URL: http://hdl.handle.net/2237/0002003984 (to be published at 5pm on November 24, 2022, JST)

Title: Local stress control to suppress dislocation generation for pseudomorphically grown AlGaN UV-C laser diodes
Authors: Maki Kushimoto, Ziyi Zhang, Akira Yoshikawa, Koji Aoto, Yoshio Honda, Chiaki Sasaoka, Leo J. Schowalter, and Hiroshi Amano
DOI: 10.1063/5.0124512 (to be published online on November 28, 2022)
Nagoya University Institutional Repository URL: http://hdl.handle.net/2237/0002003985 (to be published at 5pm on November 24, 2022, JST)

Demonstration of room-temperature continuous-wave lasing (VIDEO)

---

JOURNAL

Applied Physics Letters

DOI

10.1063/5.0124512 

ARTICLE TITLE

Local stress control to suppress dislocation generation for pseudomorphically grown AlGaN UV-C laser diodes

ARTICLE PUBLICATION DATE

28-Nov-2022

SAY AHHH

Study sheds new light on the link between oral bacteria and diseases

Peer-Reviewed Publication

KAROLINSKA INSTITUTET

Researchers at Karolinska Institutet in Sweden have identified the bacteria most commonly found in severe oral infections. Few such studies have been done before, and the team now hopes that the study can provide deeper insight into the association between oral bacteria and other diseases. The study is published in Microbiology Spectrum.

Previous studies have demonstrated clear links between oral health and common diseases, such as cancer, cardiovascular disease, diabetes and Alzheimer’s disease. However, there have been few longitudinal studies identifying which bacteria occur in infected oral- and maxillofacial regions. Researchers at Karolinska Institutet have now analysed samples collected between 2010 and 2020 at the Karolinska University Hospital in Sweden from patients with severe oral infections and produced a list of the most common bacteria.

This was a collaborative study that was performed by Professor Margaret Sällberg Chen and adjunct Professor Volkan Özenci’s research groups.

“We’re reporting here, for the first time, the microbial composition of bacterial infections from samples collected over a ten-year period in Stockholm County,” says Professor Sällberg Chen of the Department of Dental Medicine at Karolinska Institutet. “The results show that several bacterial infections with link to systemic diseases are constantly present and some have even increased over the past decade in Stockholm.”

A role in other diseases

The study shows that the most common bacterial phyla amongst the samples were Firmicutes, Bacteroidetes, Proteobacteria and Actinobacteria, while the most common genera were Streptococcus spp, Prevotella spp, and Staphylococcus spp.

“Our results provide new insight into the diversity and prevalence of harmful microbes in oral infections,” says Professor Sällberg Chen. “The finding isn’t only of importance to dental medicine, it also helps us understand the role of dental infection in patients with underlying diseases. If a certain bacterium infects and causes damage in the mouth, it’s very likely that it can be harmful to tissues elsewhere in the body as the infection spreads.”

The research group has previously shown that the occurrence of oral bacteria in the pancreas reflects the severity of pancreatic tumours.

Useful method in dental care

The study was conducted using 1,014 samples from as many patients, of whom 469 were women and 545 men, and a mass-spectrometric method called MALDI-TOF that rapidly identifies individual living bacteria in a sample, but that is rarely used in dental care. 

“Our study was a single centre epidemiology study and to ensure the validity of the results we need to make more and larger studies,” says Volkan Özenci at the Department of Laboratory Medicine, Karolinska Institutet. “We now hope that dentists will  collaborate with clinical microbiology laboratories more to gain a better understanding of the bacteria that cause dental infections, to improve diagnostics and therapeutic management of oral infections.”

The study is part of Khaled Al-Manei’s doctoral thesis, the next step of which is a similar epidemiological study of fungal infections in the mouth that aims to identify new fungi and microbes and understand what causes their possible malignancy. 

The study was financed by the Swedish Research Council, the Swedish Cancer Society and CIMED (the Centre for Innovative Medicine).

Publication: “Clinical Microbial Identification of Severe Oral Infections by MALDI-TOF Mass Spectrometry in Stockholm County: An 11-Year (2010-2020) Epidemiological Investigation”. Khaled Al-Manei, Mahin Ghorbani, Sabrina Naud, Kholod Khalil Al-Manei, Michał J. Sobkowiak, Bodil Lund, Gulsen Hazirolan, Margaret Sällberg Chen och, Volkan Özenci. Microbiology Spectrum, online 24 November 2022, doi: 10.1128/spectrum.02487-22.

---

JOURNAL

Microbiology Spectrum

DOI

10.1128/spectrum.02487-22 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Clinical Microbial Identification of Severe Oral Infections by MALDI-TOF Mass Spectrometry in Stockholm County: An 11-Year (2010-2020) Epidemiological Investigation

ARTICLE PUBLICATION DATE

24-Nov-2022

A warmer Arctic Ocean leads to more snowfall further south

Peer-Reviewed Publication

HOKKAIDO UNIVERSITY

 

IMAGE: AN INCREASINGLY WARM AND ICE-FREE ARCTIC OCEAN HAS, IN RECENT DECADES, LED TO MORE MOISTURE IN HIGHER LATITUDES. THIS MOISTURE IS TRANSPORTED SOUTH BY CYCLONIC WEATHER SYSTEMS WHERE IT PRECIPITATES AS SNOW, INFLUENCING THE GLOBAL HYDROLOGICAL CYCLE AND MANY TERRESTRIAL SYSTEMS THAT DEPEND ON IT (ILLUSTRATION: TOMONORI SATO). view more 

CREDIT: TOMONORI SATO

A new model explains that water evaporating from the Arctic Ocean due to a warming climate is transported south and can lead to increased snowfall in northern Eurasia in late autumn and early winter. This information will allow for more accurate predictions of severe weather events.

Rising air temperatures due to global warming melt glaciers and polar ice caps. Seemingly paradoxically, snow cover in some areas in northern Eurasia has increased over the past decades. However, snow is a form of water; global warming increases the quantity of moisture in the atmosphere, and thus the quantity and likelihood of rain and snow. Understanding where exactly the moisture comes from, how it is produced and how it is transported south is relevant for better predictions of extreme weather and the evolution of the climate.

Hokkaido University environmental scientist Tomonori Sato and his team developed a new tagged moisture transport model that relies on the "Japanese 55-year reanalysis dataset", a painstaking reanalysis of world-wide historical weather data over the span of the past 55 years. The group used this material to keep their model calibrated over much longer distances than hitherto possible and were thus able to shed light onto the mechanism of the moisture transport in particular over the vast landmasses of Siberia.

A standard technique to analyse moisture transport is the "tagged moisture transport model". This is a computer modelling technique that tracks where hypothetical chunks of atmospheric moisture form, how they are moved around, and where they precipitate due to the local climatic conditions. But the computer models become more and more inaccurate as the distance to the ocean increases. In particular, this makes quantitative predictions difficult. Thus, these methods have not been able to satisfyingly explain the snowfall in northern Eurasia.

The results of the study, published in the journal npj Climate and Atmospheric Science show that water evaporation from the Arctic Ocean has increased over the past four decades, and that the biggest changes have occurred from the Barents and Kara Seas north of western Siberia, as well as over the Chukchi and East Siberian Seas north of eastern Siberia, between October and December. At this time of year, the Arctic Ocean is still warm and the area not covered by ice is still large. Importantly, this development coincides with the area where sea ice retreat has been strongest over the time frame of the study. In addition, the quantitative model shows that evaporation and snowfall are especially strong during certain weather events such as cyclonic systems taking up unusually large quantities of moisture and transporting them south into Siberia, thus also highlighting detailed and specific mechanistic insights into the weather dynamics of the region.

With the Arctic Ocean being twice as sensitive to rapid warming than the global average, evaporation and subsequent changes to the hydrological cycle over northern Eurasia will become even more pronounced in the years to come. The researchers say that, since snowfall often delays the downstream effects of the abnormal weather events that cause it, "knowledge of the precursor signal stored as a snow cover anomaly is expected to help improve seasonal predictions of abnormal weather, e.g., the potential for heatwaves that enhance the risk of fire in boreal forests." This study therefore yields a key element to understanding the mechanism of this weather system as well as others that are influenced by it, and thus to making better predictions of severe events that could do harm to people and infrastructure.

---

JOURNAL

npj Climate and Atmospheric Science

DOI

10.1038/s41612-022-00310-1 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Enhanced Arctic moisture transport toward Siberia in autumn revealed by tagged moisture transport model experiment

ARTICLE PUBLICATION DATE

24-Nov-2022

Researchers from Gwangju Institute of Science and Technology develop an intelligent observer for Esports

It utilizes an object detection algorithm that learns human spectating data to find engaging viewports

Peer-Reviewed Publication

GIST (GWANGJU INSTITUTE OF SCIENCE AND TECHNOLOGY)

 

IMAGE: AN ARTIFICIAL OBSERVER WILL INTERACT WITH COMMENTATORS WHILE ANALYZING REAL-TIME IN-GAME STATE FOR THE BEST SPECTATOR EXPERIENCE. view more 

CREDIT: KYUNG-JOONG KIM

Esports, already a billion-dollar industry, is growing, partly because of human game observers. They control the camera movement and show spectators the most engaging portions of the game screen. However, these observers might miss significant events occurring concurrently across multiple screens. They are also difficult to afford in small tournaments. Consequently, the demand for automatic observers has grown. Artificial observing methods can either be rule-based or learning-based. Both of them predefine events and their importance, necessitating extensive domain knowledge. Moreover, they cannot capture undefined events or discern changes in the significance of the events.

Recently, researchers from South Korea, led by Dr. Kyung-Jong Kim, Associate Professor in Gwangju Institute of Science and Technology, have proposed an approach to overcome these problems. “We have created an automatic observer using object detection algorithm, Mask R-CNN, to learn human spectating data,” explains Dr. Kim. Their findings were made available online on 10 October 2022 and published in Volume 213 Part B of Expert Systems with Applications journal.

The novelty lies in defining the object as the two-dimensional spatial area viewed by the spectator. In contrast, conventional object detection treats a single unit, for instance, a worker or a building, as the object. In this study, the researchers first collected StarCraft in-game human observation data from 25 participants. Next, the viewports—areas viewed by the spectator—were identified and labeled as “one.” The rest of the screen was filled with “zeroes.” While the in-game features are used as input data, the human observations constituted the target information.

The researchers then fed the data into the convolution neural network (CNN), which learnt the patterns of the viewports to find the “region of common interest” (ROCI)—the most exciting area for the spectators to watch. They then compared the ROCI Mask R-CNN approach with other existing methods quantitatively and qualitatively. The former evaluation showed that CNN’s predicted viewports were similar to the collected human observational data. Additionally, the ROCI-based method outperformed others in the long run during the generalization test, which involved different matchup races, starting locations, and playing maps. The proposed observer was able to capture the scenes of interest to humans. In contrast, it could not be done by behavior cloning—an imitation learning technique.

Dr. Kim points out the future applications of their work. “The framework can be applied to other games representing some of the overall game state, not only StarCraft. As services such as multi-screen transmission continue to grow in Esports, the proposed automatic observer will play a role in these deliverables. It will also be actively used in additional content developed in the future.”

 

***

 

Reference

DOI: https://doi.org/10.1016/j.eswa.2022.118979

 

Authors: Ho-Taek Joo1, Sung-Ha Lee2, Cheong-mok Bae1, Kyung-Joong Kim1,2

 

Affiliations:     

1School of Integrated Technology, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, South Korea

2AI Graduate School, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, South Korea

 

About the Gwangju Institute of Science and Technology (GIST)
The Gwangju Institute of Science and Technology (GIST) is a research-oriented university situated in Gwangju, South Korea. Founded in 1993, GIST has become one of the most prestigious schools in South Korea. The university aims to create a strong research environment to spur advancements in science and technology and to promote collaboration between international and domestic research programs. With its motto of “A Proud Creator of Future Science and Technology,” GIST has consistently received one of the highest university rankings in Korea.

Website: http://www.gist.ac.kr/

 

About the author
KYUNG-JOONG KIM (Member, IEEE) received the B.S., M.S., and Ph.D. degrees in computer science from Yonsei University, in 2000, 2002, and 2007, respectively. He worked as a Postdoctoral Researcher with the Department of Mechanical and Aerospace Engineering, Cornell University, in 2007. He is currently an Associate Professor with the School of Integrated Technology, Gwangju Institute of Science and Technology (GIST). His research interests include artificial intelligence, game, and robotics.

 

Funding Information:
This research was supported by the National Research Foundation of Korea (NRF) funded by the MSIT (2021R1A4A1030075).

---

JOURNAL

Expert Systems with Applications

DOI

10.1016/j.eswa.2022.118979 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Learning to automatically spectate games for Esports using object detection mechanism

Wireless smart bandage provides new insights on healing chronic wounds

A new type of bandage combines wireless electrical stimulation and biosensors to bring hope to patients with slow-to-heal injuries.

Peer-Reviewed Publication

STANFORD WEARABLE ELECTRONICS INITIATIVE

 

IMAGE: DRAWING OF WIRELESS SMART BANDAGE ON HUMAN ARM view more 

CREDIT: JIAN-CHENG LAI, BAO RESEARCH GROUP @ STANFORD UNIVERSITY

By Andrew Myers

Some wounds just won’t heal. Infections, diseases like diabetes, and suppressed immune systems often stack up to slow healing. Chronic wounds can last months and lead to anxiety and depression. In the worst cases, they are life threatening. Cost of treatment has soared to $25 billion each year.

So far, however, solutions for treating chronic wounds have been few and far between, but researchers at Stanford University now report that they have developed a wireless smart bandage that has shown promise in speeding up tissue repair by monitoring the wound healing process and treating the wound simultaneously. The researchers say in a paper published November 24th in Nature Biotechnology that their device promotes faster closure of wounds, increases new blood flow to injured tissue, and enhances skin recovery by significantly reducing scar formation.

The smart bandage is composed of wireless circuitry that uses impedance/temperature sensors to monitor the progression of wound healing. If the wound is less healed or an infection is detected, the sensors inform a central processing unit to apply more electrical stimulation across the wound bed to accelerate tissue closure and reduce infection. The researchers were able to track the sensor data in real time on a smart phone, all without the need for wires.

Engineering marvel

The electronic layer, including a microcontroller unit (MCU), radio antenna, memory, electrical stimulator, biosensors, and other components, is just 100 microns thick—about the thickness of a single coat of latex paint.

All that circuitry rides atop a cleverly engineered hydrogel—a rubbery, skin-like polymer—that is integrated to both deliver healing electrical stimulation to the injured tissue and collect real-time biosensor data.

The polymer in the hydrogel is carefully designed to adhere securely to the wound surface when needed, yet to pull away cleanly and gently without harm to the wound when warmed to just a few degrees above body temperature (40°C/104°F).

“In sealing the wound, the smart bandage protects as it heals,” says Yuanwen Jiang, co-first author of the study and a post-doctoral scholar in the lab of Zhenan Bao, the K.K. Lee Professor in Chemical Engineering in the Stanford School of Engineering. “But it is not a passive tool. It is an active healing device that could transform the standard of care in the treatment of chronic wounds.”

Electrical stimulation, also known as galvanotaxis, has been previously reported to accelerate the migration of keratinocytes to the wound site, limit bacterial infections and prevent the development of biofilms on wound surfaces, to proactively promote tissue growth and help with tissue repair. The researchers were able to take this well-studied technology and integrate it with real-time biosensor data to provide a novel automated treatment modality that is informed by biosensors.

The smart bandage’s biosensing capabilities monitor biophysical changes in the local environment, providing a real-time, rapid, robust, and extremely accurate way to measure wound condition. Technically speaking, the smart bandage senses conductivity and temperature changes in the skin as the wound heals—electrical impedance increases as wounds heal and local temperatures decline as inflammation subsides. “With stimulation and sensing in one device, the smart bandage speeds healing, but it also keeps track as the wound is improving,” says Artem Trotsyuk, likewise a co-first author of the study who completed his graduate work in the lab of Geoffrey Gurtner, MD, formerly the Johnson & Johnson Distinguished Professor of Surgery (Emeritus) in the Stanford School of Medicine, and currently the Chair of the Department of Surgery and Professor of Biomedical Engineering at the University of Arizona in Tucson. “We think it represents a new modality that will enable new biological discovery and the exploration of previously difficult-to-test hypotheses on the human healing process.”

Photographs of the smart bandage showing the microcontroller unit (MCU), crystal oscillator, high-pass filter (HPF), stimulation and sensing electrodes, flexibility of the printed circuit board, adhesion of the hydrogel interface to skin, and thin layout of the board

CREDIT

Jian-Cheng Lai, Bao Research Group @ Stanford University

Welcome results, new directions

The researchers took their study a step further, venturing to understand why and how electrical stimulation heals the wound faster. They now believe that electrical stimulation promotes the activation of pro-regenerative genes such as Selenop, an anti-inflammatory gene that has been found to help with pathogen clearance and wound repair, and Apoe, which has been shown to increase muscle and soft tissue growth. Likewise, electrical stimulation increased the amount of white blood cell populations, namely monocytes and macrophages, through the recruitment of greater amounts of M2 anti-inflammatory macrophages, which have been previously reported as pro-regenerative and playing a key role in the extracellular matrix formation that is required during the proliferative phases of wound healing.

The researchers caution that the smart bandage is, as yet, a proof of concept, albeit a promising one. Many challenges remain, however. These include increasing the size of the device to human scale, reducing cost, and solving long-term data storage issues - all necessary to scale up to mass production should need and opportunity arise. Likewise, there are potentially new sensors not currently integrated that might be added, such as those that measure metabolites, biomarkers, and pH. And there are some potential roadblocks to clinical use, such as hydrogel rejection, in which the skin may react to the device and create a bad gel-to-skin combination, or biofouling of the sensors, which can cause irritation.

Despite these hurdles, the researchers are pushing ahead and remain optimistic about the potential of their smart bandage to provide hope for patients suffering with chronic wounds.

Stanford co-first authors: Yuanwen Jiang is a postdoctoral fellow in the Bao Group; Artem Trotsyuk is a former graduate student in the Gurtner Lab; Simiao Niu is a former postdoctoral scholar in the Bao Group.

Other Stanford co-authors: Dominic Henn, Kellen Chen, Zeshaan Maan, Melanie Rodrigues, Clark A. Bonham, Michael Januszyk, Ethan Beard, Tanish Jain, Jagannath Padmanabhan, Katharina Fischer and Sun Hyung Kwon are members of the Gurtner Lab; Alana Mermin-Bunnell, Smiti Mittal, Sydney Steele, Gurupranav Gurusankar, Christopher Neimeth, Hudson Kussie, Madelyn Larson, and Serena Jing are undergraduates in the Gurtner Lab; Dharshan Sivaraj and Melissa Leeolou are MD students in the Gurtner Lab; David Perrault and Arhana Chattopadhyay are residents in plastic surgery and are members of the Gurtner Lab; Chien-Chung Shih, Jian-Cheng Lai, Jing Tang and Donglai Zhong are postdoctoral fellows; Willian Viana and Eric Zhao are graduate students; Ronjon Nag is a Stanford Distinguished Careers Institute Fellow and an Adjunct Professor of Genetics; Michael Snyder is professor and Chair of the Genetics Department; Aref Saberi, Kefan Sun, and Kui Liang; Zhenan Bao is also a member of Stanford Bio-X, the Stanford Cardiovascular Institute, the Maternal & Child Health Research Institute (MCHRI), the Precourt Institute for Energy, Sarafan ChEM-H, Stanford Woods Institute for the Environment, the Wu Tsai Human Performance Alliance, the Wu Tsai Neurosciences Institute, and an investigator of CZ Biohub; Geoffrey Gurtner is also a member of Stanford Bio-X, the Stanford Cardiovascular Institute, the Stanford Cancer Institute, and the Wu Tsai Neurosciences Institute and was the founding director of the Stanford Advanced Wound Care Center (AWCC). Kailiang Zhang is a Research Scientist with BOE Technology Group.

The eWEAR-TCCI awards for science writing is a project commissioned by the Wearable Electronics Initiative (eWEAR) at Stanford University and made possible by funding through eWEAR industrial affiliates program member Shanda Group and the Tianqiao and Chrissy Chen Institute (TCCI®).

---

JOURNAL

Nature Biotechnology

DOI

10.1038/s41587-022-01528-3 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Wireless, closed-loop, smart bandage with integrated sensors and stimulators for advanced wound care and accelerated healing

ARTICLE PUBLICATION DATE

24-Nov-2022

A study offers new insights into the record 2021 Western North America heat wave

Combined unusual weather systems, supercharged by climate change

Peer-Reviewed Publication

COLUMBIA CLIMATE SCHOOL

 

IMAGE: HE 2021 HEAT WAVE OVER WESTERN NORTH AMERICA CAME IN PART FROM BENDING OF THE NORTHERN HEMISPHERE’S JET STREAM INTO FOUR HUGE NORTH-SOUTH PEAKS AND TROUGHS. ABOVE, REDDER COLORS INDICATE HIGHER TEMPERATURES; BLACK ARROWS SHOW WIND DIRECTIONS. UNDER THE PEAKS, WESTERN EURASIA AND NORTHEAST SIBERIA EXPERIENCED TEMPERATURE SPIKES, BUT NORTH AMERICA (INSIDE BOX) SAW THE WORST. WITHIN A FOURTH PEAK, ICELAND ALSO SAW ELEVATED TEMPERATURES. view more 

CREDIT: ADAPTED FROM BARTUSEK ET AL., NATURE CLIMATE CHANGE 2022

The heat wave that hammered western North America in late June and early July 2021 was not just any midsummer event. Over nine days, from British Columbia through Washington and Oregon and beyond, it exceeded average regional temperatures for the period by 10 degrees C (18 F), and on single days in some locales, by an astounding 30 C, or 54 F. Among many new daily records, it set a new national benchmark for all of Canada, at 121.3 F in Lytton, British Columbia. The next day, the entire town burned down amid an uncontrollable wildfire—one of many sparked by the hot, dry weather. Across the region, at least 1,400 people died from heat-related causes.

Within weeks, scientists blamed the event’s extremity largely on climate change. Now, a new study in the journal Nature Climate Change affirms that conclusion, and for the first time comprehensively elucidates the multiple mechanisms—some strictly climate-related, others more in the realm of disastrous coincidences—that they say led to the mind-bending temperatures.

“It was so extreme, it’s tempting to apply the label of a ‘black swan’ event, one that can’t be predicted,” said lead author Samuel Bartusek, a Ph.D. student at the Columbia Climate School’s Lamont-Doherty Earth Observatory. “But there’s a boundary between the totally unpredictable, the plausible, and the totally expected that’s hard to categorize. I would call this more of gray swan.”

The study pulled climate data starting in the 1950s together with daily weather observations from the weeks preceding and during the heat wave to form an intimate portrait. A core conclusion: Such an event would have been virtually impossible absent human-induced warming. It was impossible in the 1950s, but atmospheric warming since then has moved the needle to a prospective 1-in-200-year event—still rare, but now feasible. The researchers predicts that if warming continues at even a moderate pace, such heat waves could hit the region about every 10 years by 2050.

Average global temperatures have risen less than 2 degrees F in the last century. But small upward increments may shift interactions between atmosphere and land in ways that drive chances of extreme temperature spikes far beyond just the average temperature rise. Boiled down to the simplest terms, the study says much of the 2021 heat wave arose from the multiplying effects of higher overall temperatures, including drying of soils in some areas. Additionally, about a third of the heat wave came from what the researchers call “nonlinear” forces—short-term weather patterns that helped lock in the heat that may also have been amplified by changing climate.

One major driver, they say, was a disruption of the jet stream, which normally carries air west to east across the Northern Hemisphere midlatitudes along a more or less circular path. Preceding the heat wave, though, the jet stream stalled and bent into huge waves, with four north-south peaks and troughs. These concentrated high-pressure systems underneath each peak; high pressure compresses air more and more as it approaches the surface, and this generates heat. One of those systems settled on western North America, then stayed there there day after day, creating what meteorologists call a “heat dome.”

Some scientists believe big jet-stream waves are becoming more frequent and extreme due to human-induced warming. The jet stream normally forms a boundary between frigid polar air and warmer southern air, but recent outsize warming in the Arctic is breaking down the temperature difference, destabilizing the system, they say. This idea is still being debated. That said, part of the groundwork for the new study was laid by coauthor Kai Kornhuber, who published a 2019 study identifying such meanders as threats to world food security should they hit multiple major agricultural regions simultaneously. In 2021, concurrent major heat waves tied to the meanders hit not just North America, but within a dome spanning much of Scandinavia, Eastern Europe, western Russia and the Caucasus; and another over northwestern Siberia.

Western North America’s was by far the worst. One factor, the authors say, was a series of smaller-scale atmospheric waves generated in the western Pacific Ocean. These moved east, and upon hitting land, latched onto the larger jet-stream wave and amplified it. Meteorologists could see these patterns coming some 10 days out, and thus accurately warned of the heat wave well in advance.

A longer-term key factor, the researchers say, is climate-driven drying that has overtaken much of the U.S. and Canadian west in recent decades, reducing soil-moisture levels in many areas. During the heat wave, that meant reduced evaporation of water from vegetation that previously would have helped counteract heating of the air near the surface. With less evaporation, in some places the surface more effectively heated the air above it. Indeed, the researchers found that the heat wave was most extreme in areas with the driest soils.

“Global warming is gradually making the Pacific Northwest drier,” said study coauthor Mingfang Ting, a Lamont-Doherty professor, pushing it into a long-term state where such extreme events are becoming ever more likely.

Extraordinary heat and drought continue to affect the region. In mid-October of this year, many daily temperature records were shattered with spikes more characteristic of high summer than mid-autumn. These included 88 degrees in Seattle on Oct. 16—a full 16 degrees above the previous daily record. The same day, there were records in Vancouver (86); Olympia, Wash. (85); and Portland, Ore. (86), its fifth consecutive day in the 80s. The hot, dry weather has sparked forest fires so fierce and widespread that on Oct. 20, smoke caused Seattle to see the worst air quality of any big city in the world, ahead of usual favorites like Beijing and Delhi.

“We can certainly expect more hot periods in this area and other areas, just due to the increase in global temperatures, and the way it shifts the probability of extreme events by huge amounts,” said Bartusek

Hot, dry weather during the heat wave sparked numerous wildfires, destroying large areas and worsening air quality.

CREDIT

USDA photo by Kari Greer

JOURNAL

Nature Climate Change

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

2021 North American Heat Wave Amplified by Climate-Change-Driven Nonlinear Reactions

ARTICLE PUBLICATION DATE

24-Nov-2022