Researchers produce laser pulses with record-breaking intensity

High-intensity pulses allow astrophysical phenomena to be studied in the lab

THE OPTICAL SOCIETY

Research News 

IMAGE: RESEARCHERS CREATED HIGH-INTENSITY PULSES USING THE PETAWATT LASER (PICTURED) AT THE CENTER FOR RELATIVISTIC LASER SCIENCE (CORELS) IN THE REPUBLIC OF KOREA. THIS HIGH INTENSITY LASER WILL ALLOW SCIENTISTS TO... view more 

CREDIT: CHANG HEE NAM, CORELS

WASHINGTON -- Researchers have demonstrated a record-high laser pulse intensity of over 1023 W/cm2 using the petawatt laser at the Center for Relativistic Laser Science (CoReLS), Institute for Basic Science in the Republic of Korea. It took more than a decade to reach this laser intensity, which is ten times that reported by a team at the University of Michigan in 2004. These ultrahigh intensity light pulses will enable exploration of complex interactions between light and matter in ways not possible before.

The powerful laser can be used to examine phenomena believed to be responsible for high-power cosmic rays, which have energies of more than a quadrillion (1015) electronvolts (eV). Although scientists know that these rays originate from somewhere outside our solar system, how they are made and what is forming them has been a longstanding mystery.

"This high intensity laser will allow us to examine astrophysical phenomena such as electron-photon and photon-photon scattering in the lab," said Chang Hee Nam, director of CoReLS and professor at Gwangju Institute of Science & Technology. "We can use it to experimentally test and access theoretical ideas, some of which were first proposed almost a century ago."

In Optica, The Optical Society's (OSA) journal for high impact research, the researchers report the results of years of work to increase the intensity of laser pulses from the CoReLS laser. Studying laser matter-interactions requires a tightly focused laser beam and the researchers were able to focus the laser pulses to a spot size of just over one micron, less than one fiftieth the diameter of a human hair. The new record-breaking laser intensity is comparable to focusing all the light reaching earth from the sun to a spot of 10 microns.

"This high intensity laser will let us tackle new and challenging science, especially strong field quantum electrodynamics, which has been mainly dealt with by theoreticians," said Nam. "In addition to helping us better understand astrophysical phenomena, it could also provide the information necessary to develop new sources for a type of radiation treatment that uses high-energy protons to treat cancer."

Making pulses more intense

The new accomplishment extends previous work in which the researchers demonstrated a femtosecond laser system, based on Ti:Sapphire, that produces 4 petawatt (PW) pulses with durations of less than 20 femtoseconds while focused to a 1 micrometer spot. This laser, which was reported in 2017, produced a power roughly 1,000 times larger than all the electrical power on Earth in a laser pulse that only lasts twenty quadrillionths of a second.

To produce high-intensity laser pulses on target, the generated optical pulses must be focused extremely tightly. In this new work, the researchers apply an adaptive optics system to precisely compensate optical distortions. This system involves deformable mirrors -- which have a controllable reflective surface shape -- to precisely correct distortions in the laser and generate a beam with a very well-controlled wavefront. They then used a large off-axis parabolic mirror to achieve an extremely tight focus. This process requires delicate handling of the focusing optical system.

"Our years of experience gained while developing ultrahigh power lasers allowed us to accomplish the formidable task of focusing the PW laser with the beam size of 28 cm to a micrometer spot to accomplish a laser intensity exceeding 1023 W/cm2," said Nam.

Studying high-energy processes

The researchers are using these high-intensity pulses to produce electrons with an energy over 1 GeV (109 eV) and to work in the nonlinear regime in which one electron collides with several hundred laser photons at once. This process is a type of strong field quantum electrodynamics called nonlinear Compton scattering, which is thought to contribute to the generation of extremely energetic cosmic rays.

They will also use the radiation pressure created by the ultrahigh intensity laser to accelerate protons. Understanding how this process occurs could help develop a new laser-based proton source for cancer treatments. Sources used in today's radiation treatments are generated using an accelerator that requires a huge radiation shield. A laser-driven proton source is expected to reduce the system cost, making the proton oncology machine less costly and thus more widely accessible to patients.

The researchers continue to develop new ideas for enhancing the laser intensity even more without significantly increasing the size of the laser system. One way to accomplish this would be to figure out a new way to reduce the laser pulse duration. As lasers with peaks power ranging from 1 to 10 PW are now in operation and several facilities reaching 100 PW are being planned, there is no doubt that high-intensity physics will progress tremendously in the near future.

CAPTION

A laser-matter interaction chamber for proton acceleration, in which the focal intensity over 1023 W/cm2 was demonstrated by tightly focusing a multi-petawatt laser beam with an F/1.1 off-axis parabolic mirror.

CREDIT

Chang Hee Nam

Paper: J. W. Yoon, Y. G. Kim, I. W. Choi, J. H. Sung, H. W. Lee, S. K. Lee, C. H. Nam, "Realization of laser intensity over 1023 W/cm2," Optica, 8, 5, 630-635 (2021).

DOI: https://doi.org/10.1364/OPTICA.420520.

About Optica

Optica is an open-access, journal dedicated to the rapid dissemination of high-impact peer-reviewed research across the entire spectrum of optics and photonics. Published monthly by The Optical Society (OSA), Optica provides a forum for pioneering research to be swiftly accessed by the international community, whether that research is theoretical or experimental, fundamental or applied. Optica maintains a distinguished editorial board of more than 60 associate editors from around the world and is overseen by Editor-in-Chief Prem Kumar, Northwestern University, USA. For more information, visit Optica.

About The Optical Society

Founded in 1916, The Optical Society (OSA) is the leading professional organization for scientists, engineers, students and business leaders who fuel discoveries, shape real-life applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership initiatives, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of optics and photonics experts. For more information, visit osa.org.

Realization of the highest laser intensity

ever reached

The record-breaking laser intensity over 1023 W/cm2 enables us to explore novel physical phenomena occurring under extreme physical conditions

INSTITUTE FOR BASIC SCIENCE

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IMAGE: PANORAMIC VIEW OF THE CORELS PW LASER. view more 

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Recently, laser scientists at the Center for Relativistic Laser Science (CoReLS) within the Institute for Basic Science (IBS) in South Korea realized the unprecedented laser intensity of 1023 W/cm2. This has been a milestone that has been pursued for almost two decades by many laser institutes around the world.

An ultrahigh intensity laser is an important research tool in several fields of science, including those which explore novel physical phenomena occurring under extreme physical conditions. Since the demonstration of the 1022 W/cm2 intensity laser by a team at the University of Michigan in 2004, the realization of laser intensity over 1023 W/cm2 has been pursued for nearly 20 years.

In general, achieving such a level of ultra-high laser intensity requires two things: laser with extremely high power output, and focusing that laser to the smallest spot as possible. While continuous-wave lasers are limited to megawatt-scale intensity, far higher peak power output (on the order of petawatt) is possible in pulsed laser systems by delivering the energy in the time scale as short as femtoseconds. In order to reach the goal of developing the world's most powerful laser, several ultrahigh power laser facilities with outputs of 10 PW and beyond, such as ELI (EU), Apollon (France), EP-OPAL (USA), and SEL (China), have been built or are being planned. A recent study from Osaka University even proposed a concept prototype for an exawatt class laser.

Meanwhile, the CoReLS laser team has been operating a 4-PW laser system since 2016. This year in April 2021, they have finally achieved the record-breaking milestone of 1023 W/cm2 by tightly focusing the multi-PW laser beam.

Several special techniques have been employed to achieve this feat. The power intensity was maximized by using a focusing optics called an off-axis parabolic mirror, which was used to focus a 28 cm laser beam down to a spot only 1.1 micrometers wide. Such a diffraction-limited tight focusing can be obtained only with a clean laser beam without wavefront distortion. The CoReLS laser team, thus, made its PW laser beam as clean as possible using a set of deformable mirrors to correct the wavefront distortion of the PW laser.

The CoReLS 4-PW laser is a femtosecond, ultrahigh power Ti:sapphire laser, based on the chirped pulse amplification (CPA) technique. The layout of the CoReLS 4-PW laser, including the experimental setup to control the wavefront and to measure the intensity, is given in Fig. 1. A low-energy femtosecond laser pulse from the front-end was stretched to a nanosecond pulse by the pulse stretcher. The initial laser pulse was then amplified to 4.5 J by the two power amplifiers and then up to 112 J by the two booster amplifiers. The size of the laser beam increased along the beam path by a series of beam expanders; 25 mm right after the power amplifiers, 65 mm at the entrance of the 1st booster amplifier, 85 mm at the entrance of the 2nd booster amplifier, and 280 mm at the entrance of the pulse compressor. In the pulse compressor, the laser pulse was recompressed to 20 fs (FWHM), which caused its peak power to become 4 PW after the compression.

In order to compensate for the wavefront distortion of the PW laser beam, two deformable mirrors were employed in the PW laser beamline. The first deformable mirror (DM1) with a diameter of 100 mm was installed after the final booster amplifier, with its role being to correct the wavefront distortion accumulated from the front end to the final beam expander. The second deformable mirror (DM2) with a diameter of 310 mm was installed after the pulse compressor, which corrects the additional aberrations induced from large aperture optics in the pulse compressor, the beam delivery line, and the target area. In the target chamber, the PW laser beam was tightly focused with an f /1.1 off-axis parabolic mirror, which possessed an effective focal length of 300 mm. For imaging and characterization of the focused spot, the focused beam was collimated by an objective lens. It was then divided into two beams with a beam splitter for the focal spot and wavefront characterization. A camera was used for the focal spot monitoring of the transmitted laser beam, and a wavefront sensor was used to measure the wavefront of the reflected laser beam. Figure 3 shows the 3-D focal spot image measured by the camera in the target chamber.

Prof. NAM Chang Hee, the Director of CoReLS, notes, "This work has shown that the CoReLS PW laser is the most powerful laser in the world. With the highest laser intensity achieved ever, we can tackle new challenging areas of experimental science, especially strong field quantum electrodynamics (QED) that has been dealt with mainly by theoreticians. We can explore new physical problems of electron-photon scattering (Compton scattering) and photon-photon scattering (Breit-Wheeler process) in the nonlinear regime. This kind of research is directly related to various astrophysical phenomena occurring in the universe and can help us to further expand our knowledge horizon."

CAPTION

Layout of the CoReLS petawatt laser and the experimental setup to achieve the laser intensity of over 1023W/cm2. BS, beam splitter; DM1-2, deformable mirrors; EM, energy meter; OAP, f /1.1 off-axis parabolic mirror; OL, objective lens; WFS1-2, wavefront sensors.

CREDIT

Institute for Basic Science

CAPTION

Measured 3-D focal spot image showing the laser intensity of 1.4x1023 W/cm2.

CREDIT

Institute for Basic Science

First nanoscale look at a reaction that limits the efficiency of generating hydrogen fuel

With a new suite of tools, scientists discovered exactly how tiny plate-like catalyst particles carry out a key step in that conversion - the evolution of oxygen in an electrocatalytic cell -- in unprecedented detail

DOE/SLAC NATIONAL ACCELERATOR LABORATORY

VIDEO: THIS ANIMATION COMBINES IMAGES OF A TINY, PLATE-LIKE CATALYST PARTICLE AS IT CARRIES OUT A REACTION THAT SPLITS WATER AND GENERATES OXYGEN GAS - PART OF A CLEAN, SUSTAINABLE PROCESS... view more 

CREDIT: TYLER MEFFORD AND ANDREW AKBASHEV/STANFORD UNIVERSITY

Transitioning from fossil fuels to a clean hydrogen economy will require cheaper and more efficient ways to use renewable sources of electricity to break water into hydrogen and oxygen.

But a key step in that process, known as the oxygen evolution reaction or OER, has proven to be a bottleneck. Today it's only about 75% efficient, and the precious metal catalysts used to accelerate the reaction, like platinum and iridium, are rare and expensive.

Now an international team led by scientists at Stanford University and the Department of Energy's SLAC National Accelerator Laboratory has developed a suite of advanced tools to break through this bottleneck and improve other energy-related processes, such as finding ways to make lithium-ion batteries charge faster. The research team described their work in Nature today.

Working at Stanford, SLAC, DOE's Lawrence Berkeley National Laboratory (Berkeley Lab) and Warwick University in the UK, they were able to zoom in on individual catalyst nanoparticles - shaped like tiny plates and about 200 times smaller than a red blood cell - and watch them accelerate the generation of oxygen inside custom-made electrochemical cells, including one that fits inside a drop of water.

They discovered that most of the catalytic activity took place on the edges of particles, and they were able to observe the chemical interactions between the particle and the surrounding electrolyte at a scale of billionths of a meter as they turned up the voltage to drive the reaction.

By combining their observations with prior computational work performed in collaboration with the SUNCAT Institute for Interface Science and Catalysis at SLAC and Stanford, they were able to identify a single step in the reaction that limits how fast it can proceed.

"This suite of methods can tell us the where, what and why of how these electrocatalytic materials work under realistic operating conditions," said Tyler Mefford, a staff scientist with Stanford and the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC who led the research. "Now that we have outlined how to use this platform, the applications are extremely broad."

CAPTION

An illustration shows bubbles of oxygen rising from the edges of a six-sided, plate-like catalyst particle, 200 times smaller than a red blood cell, as it carries out a reaction called OER that splits water molecules and generates oxygen gas. The small arm at left is from an atomic force microscope. It's one of a suite of techniques that researchers from SLAC, Stanford, Berkeley Lab and the University of Warwick brought together to study this reaction - a key step in producing clean hydrogen fuel - in unprecedented detail. The concentric rings represent the scanning transmission X-ray microscope's Fresnel zone plate used to image the process at Berkeley Lab's Advanced Light Source.

CREDIT

CUBE3D Graphic

Scaling up to a hydrogen economy

The idea of using electricity to break water down into oxygen and hydrogen dates back to 1800, when two British researchers discovered that they could use electric current generated by Alessandro Volta's newly invented pile battery to power the reaction.

This process, called electrolysis, works much like a battery in reverse: Rather than generating electricity, it uses electrical current to split water into hydrogen and oxygen. The reactions that generate hydrogen and oxygen gas take place on different electrodes using different precious metal catalysts.

Hydrogen gas is an important chemical feedstock for producing ammonia and refining steel, and is increasingly being targeted as a clean fuel for heavy duty transportation and long-term energy storage. But more than 95% of the hydrogen produced today comes from natural gas via reactions that emit carbon dioxide as a byproduct. Generating hydrogen through water electrolysis driven by electricity from solar, wind, and other sustainable sources would significantly reduce carbon emissions in a number of important industries.

But to produce hydrogen fuel from water on a big enough scale to power a green economy, scientists will have to make the other half of the water-splitting reaction - the one that generates oxygen ­- much more efficient, and find ways to make it work with catalysts based on much cheaper and more abundant metals than the ones used today.

"There aren't enough precious metals in the world to power this reaction at the scale we need," Mefford said, "and their cost is so high that the hydrogen they generate could never compete with hydrogen derived from fossil fuels."

Improving the process will require a much better understanding of how water-splitting catalysts operate, in enough detail that scientists can predict what can be done to improve them. Until now, many of the best techniques for making these observations did not work in the liquid environment of an electrocatalytic reactor.

In this study, scientists found several ways to get around those limitations and get a sharper picture than ever before.

CAPTION

An illustration shows bubbles of oxygen rising from the edges of six-sided, plate-like catalyst particles, 200 times smaller than a red blood cell, as they carries out a reaction called OER that splits water molecules and generates oxygen gas. Researchers from SLAC, Stanford, Berkeley Lab and the University of Warwick have brought together a suite of techniques to study this reaction - a key step in producing clean hydrogen fuel - in unprecedented detail.

CREDIT

CUBE3D Graphic

New ways to spy on catalysts

The catalyst they chose to investigate was cobalt oxyhydroxide, which came in the form of flat, six-sided crystals called nanoplatelets. The edges were sharp and extremely thin, so it would be easy to distinguish whether a reaction was taking place on the edges or on the flat surface.

About a decade ago, Patrick Unwin's research group at the University of Warwick had invented a novel technique for putting a miniature electrochemical cell inside a nanoscale droplet that protrudes from the tip of a pipette tube. When the droplet is brought into contact with a surface, the device images the topography of the surface and electronic and ionic currents with very high resolution.

For this study, Unwin's team adapted this tiny device to work in the chemical environment of the oxygen evolution reaction. Postdoctoral researchers Minkyung Kang and Cameron Bentley moved it from place to place across the surface of a single catalyst particle as the reaction took place.

"Our technique allows us to zoom in to study extremely small regions of reactivity," said Kang, who led out the experiments there. "We are looking at oxygen generation at a scale more than one hundred million times smaller than typical techniques."

They discovered that, as is often the case for catalytic materials, only the edges were actively promoting the reaction, suggesting that future catalysts should maximize this sort of sharp, thin feature.

Meanwhile, Stanford and SIMES researcher Andrew Akbashev used electrochemical atomic force microscopy to determine and visualize exactly how the catalyst changed shape and size during operation, and discovered that the reactions that initially changed the catalyst to its active state were much different than had been previously assumed. Rather than protons leaving the catalyst to kick off the activation, hydroxide ions inserted themselves into the catalyst first, forming water inside the particle that made it swell up. As the activation process went on, this water and residual protons were driven back out.

In a third set of experiments, the team worked with David Shapiro and Young-Sang Yu at Berkeley Lab's Advanced Light Source and with a Washington company, Hummingbird Scientific, to develop an electrochemical flow cell that could be integrated into a scanning transmission X-ray microscope. This allowed them to map out the oxidation state of the working catalyst - a chemical state that's associated with catalytic activity - in areas as small as about 50 nanometers in diameter.

"We can now start applying the techniques we developed in this work toward other electrochemical materials and processes," Mefford said. "We would also like to study other energy-related reactions, like fast charging in battery electrodes, carbon dioxide reduction for carbon capture, and oxygen reduction, which allows us to use hydrogen in fuel cells."

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The Advanced Light Source is a DOE Office of Science user facility, and major funding for this research came from the DOE Office of Science, including Small Business Innovation Research awards to Hummingbird Scientific. Parts of the research were performed at the Stanford Nanofabrication Facility.

Citation: J. Tyler Mefford et al., Nature, 6 May 2021 (10.1038/s41586-021-03454-x)

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

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

Sharks use Earth's magnetic fields to guide them like a map

CELL PRESS

VIDEO: THIS VIDEO IS FOOTAGE FROM AN EXPERIMENTAL TRIAL, WHERE THE BONNETHEAD'S SWIMMING BEHAVIOR IS AFFECTED BY THE MAGNETIC FIELD IT IS EXPERIENCING. view more 

CREDIT: BRYAN KELLER

Sea turtles are known for relying on magnetic signatures to find their way across thousands of miles to the very beaches where they hatched. Now, researchers reporting in the journal Current Biology on May 6 have some of the first solid evidence that sharks also rely on magnetic fields for their long-distance forays across the sea.

"It had been unresolved how sharks managed to successfully navigate during migration to targeted locations," said Save Our Seas Foundation project leader Bryan Keller, also of Florida State University Coastal and Marine Laboratory. "This research supports the theory that they use the earth's magnetic field to help them find their way; it's nature's GPS."

Researchers had known that some species of sharks travel over long distances to reach very specific locations year after year. They also knew that sharks are sensitive to electromagnetic fields. As a result, scientists had long speculated that sharks were using magnetic fields to navigate. But the challenge was finding a way to test this in sharks.

"To be honest, I am surprised it worked," Keller said. "The reason this question has been withstanding for 50 years is because sharks are difficult to study."

Keller realized the needed studies would be easier to do in smaller sharks. They also needed a species known for returning each year to specific locations. He and his colleagues settled on bonnetheads (Sphyrna tiburo).

"The bonnethead returns to the same estuaries each year," Keller said. "This demonstrates that the sharks knows where 'home' is and can navigate back to it from a distant location."

The question then was whether bonnetheads managed those return trips by relying on a magnetic map. To find out, the researchers used magnetic displacement experiments to test 20 juvenile, wild-caught bonnetheads. In their studies, they exposed sharks to magnetic conditions representing locations hundreds of kilometers away from where the sharks were actually caught. Such studies allow for straightforward predictions about how the sharks should subsequently orient themselves if they were indeed relying on magnetic cues.

If sharks derive positional information from the geomagnetic field, the researchers predicted northward orientation in the southern magnetic field and southward orientation in the northern magnetic field, as the sharks attempted to compensate for their perceived displacement. They predicted no orientation preference when sharks were exposed to the magnetic field that matched their capture site. And, it turned out, the sharks acted as they'd predicted when exposed to fields within their natural range.

The researchers suggest that this ability to navigate based on magnetic fields may also contribute to the population structure of sharks. The findings in bonnetheads also likely help to explain impressive feats by other shark species. For instance, one great white shark was documented to migrate between South Africa and Australia, returning to the same exact location the following year.

"How cool is it that a shark can swim 20,000 kilometers round trip in a three-dimensional ocean and get back to the same site?" Keller asked. "It really is mind blowing. In a world where people use GPS to navigate almost everywhere, this ability is truly remarkable."

In future studies, Keller says he'd like to explore the effects of magnetic fields from anthropogenic sources such as submarine cables on sharks. They'd also like to study whether and how sharks rely of magnetic cues not just during long-distance migration but also during their everyday behavior.

CAPTION

This figure shows how the experiment assessed the ability of bonnethead sharks to use the Earth's magnetic field to navigate.

CREDIT

Keller et al./Current Biology

This work was supported by the Save Our Seas Foundation and the Florida State University Coastal and Marine Laboratory.

Current Biology, Keller et al.: "Map-like use of earth's magnetic field in sharks" https://www.cell.com/current-biology/fulltext/S0960-9822(21)00476-0

Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.

CAPTION

This image shows an overhead shot of bonnetheads in the holding tank.

CREDIT

Bryan Keller

Engineers and biologists join forces to reveal how seals evolved to swim

New research combines cutting-edge engineering with animal behaviour to explain the origins of efficient swimming in Nature's underwater acrobats: Seals and Sea Lions

MONASH UNIVERSITY

Research News

 

New research combines cutting-edge engineering with animal behaviour to explain the origins of efficient swimming in Nature's underwater acrobats: Seals and Sea Lions.

Seals and sea lions are fast swimming ocean predators that use their flippers to literally fly through the water. But not all seals are the same: some swim with their front flippers while others propel themselves with their back feet.

In Australia, we have fur seals and sea lions that have wing-like front flippers specialised for swimming, while in the Northern Hemisphere, grey and harbor seals have stubby, clawed paws and swim with their feet. But the reasons why these two different ways of swimming evolved has perplexed biologists for generations. Is one style better than the other?

But now a Monash University-led interdisciplinary study published in Current Biology has used cutting-edge computer simulations alongside footage of live seals to finally answer this evolutionary mystery.

"The difference in swimming style between forelimb and hindlimb propelled seals is so great that these groups were originally thought to have evolved from separate land-dwelling ancestors," said lead study author Dr David Hocking from the Monash University School of Biological Sciences, "but the genetics clearly shows that all living seals come from the same group of animals."

The question is, how could such different swimming styles evolve within the one animal group?

To reveal the answer, Dr Hocking teamed up with Monash University engineer Dr Shibo Wang from the Department of Mechanical and Aerospace Engineering, and used advanced Fluid Dynamics simulations to show how water flows around seal flippers of different shapes.

"Our analysis showed that some Antarctic seals, like leopard seals, actually have very streamlined, wing-like forelimbs, despite being from the 'foot-propelled' seal family," said Dr Wang. This is supported by footage of live leopard seals swimming at Taronga Zoo, where they used their front limbs to swim in a similar way to the fur seals and sea lions.

This discovery shows how wing-like flippers can evolve in seals that already swim with their back feet, providing a pathway for the evolution of forelimb swimming in the fur seals and sea lions.

"Wing-like flippers help leopard seals to surge forward and ambush fast-swimming penguins," said Associate Professor Alistair Evans who also collaborated on the study, "and it seems likely that the earliest sea lions also needed this extra speed to capture their preferred prey: schooling fish".

"We finally have a window into the early evolution of swimming in seals," Dr Evans said.

But as well as explaining the origin of seals, this study also has a more practical outcome: improved human designs. "Seals have had millions of years to perfect their swimming, and they can teach us a thing or two about underwater grace and elegance," said Dr Hocking. "Learning from them may help us to improve the design of human-built machines like underwater drones and submersibles, increasing their speed, manoeuvrability or energy efficiency."

Who knows? Perhaps in future we will be able to know how it feels to swim like a seal thanks to seal-shaped submarines.

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The cerebellum may have played an important role in the evolution of the human brain

Study compares epigenetic modifications to DNA in the cerebellum of humans, chimpanzees and monkeys

PLOS

Research News

 

The cerebellum--a part of the brain once recognized mainly for its role in coordinating movement--underwent evolutionary changes that may have contributed to human culture, language and tool use. This new finding appears in a study by Elaine Guevara of Duke University and colleagues, published May 6th in the journal PLOS Genetics.

Scientists studying how humans evolved their remarkable capacity to think and learn have frequently focused on the prefrontal cortex, a part of the brain vital for executive functions, like moral reasoning and decision making. But recently, the cerebellum has begun receiving more attention for its role in human cognition. Guevara and her team investigated the evolution of the cerebellum and the prefrontal cortex by looking for molecular differences between humans, chimpanzees, and rhesus macaque monkeys. Specifically, they examined genomes from the two types of brain tissue in the three species to find epigenetic differences. These are modifications that do not change the DNA sequence but can affect which genes are turned on and off and can be inherited by future generations.

Compared to chimpanzees and rhesus macaques, humans showed greater epigenetic differences in the cerebellum than the prefrontal cortex, highlighting the importance of the cerebellum in human brain evolution. The epigenetic differences were especially apparent on genes involved in brain development, brain inflammation, fat metabolism and synaptic plasticity--the strengthening or weakening of connections between neurons depending on how often they are used.

The epigenetic differences identified in the new study are relevant for understanding how the human brain functions and its ability to adapt and make new connections. These epigenetic differences may also be involved in aging and disease. Previous studies have shown that epigenetic differences between humans and chimpanzees in the prefrontal cortex are associated with genes involved in psychiatric conditions and neurodegeneration. Overall, the new study affirms the importance of including the cerebellum when studying how the human brain evolved.

Guevara adds, "Our results support an important role for the cerebellum in human brain evolution and suggest that previously identified epigenetic features distinguishing the human neocortex are not unique to the neocortex."

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Peer reviewed Experimental study People; Animals; Cells

Citation: Guevara EE, Hopkins WD, Hof PR, Ely JJ, Bradley BJ, Sherwood CC (2021) Comparative analysis reveals distinctive epigenetic features of the human cerebellum. PLoS Genet 17(5): e1009506. https://doi.org/10.1371/journal.pgen.1009506

Funding: The work was supported by funding from the Center for the Advanced Study of Human Paleobiology at The George Washington University (https://cashp.columbian.gwu.edu/) to CCS and EEG, Duke University Department of Evolutionary Anthropology to EEG (https://evolutionaryanthropology.duke.edu/), the James S. McDonnell Foundation (https://www.jsmf.org/) Grant #220020293 to CCS, and National Science Foundation (https://www.nsf.gov/) Grants SMA-1542848 to CCS, WDH, and BJB; EF-2021785 to CCS, and BSC-1919780 to CCS and EEG. The National Chimpanzee Brain Resource was supported by National Institutes of Health (https://www.nih.gov/) Grant NS092988 to CCS and WDH. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Many consumers misinterpret food date labels, yet use them with confidence

Consumer education is needed to increase understanding of food date labels according to a new study in the Journal of Nutrition Education and Behavior

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IMAGE: EXAMPLE OF AN ILLUSTRATED MESSAGE. view more 

CREDIT: JOURNAL OF NUTRITION EDUCATION AND BEHAVIOR

Philadelphia, May 6, 2021 - Misunderstanding food date labeling is common and educational communications are needed to improve consumer understanding, according to a new study in the Journal of Nutrition Education and Behavior, published by Elsevier.

Does it mean "spoiled - throw it out," or "might not taste as good as it could anymore?" Food date labels (e.g., "USE By August 16") can play an important role in helping consumers make informed decisions about food, and ultimately prevent unsafe consumption and waste of food. Researchers surveyed 2,607 adults in the United States to assess consumer understanding of the streamlined 2-date labeling system and explore the relative effectiveness of educational messages in increasing understanding.

"Our study showed that an overwhelming majority of consumers say that they use food date labels to make decisions about food and say they know what the labels mean," said Catherine Turvey, MPH, Department of Exercise and Nutrition Sciences, Milken Institute School of Public Health, The George Washington University, Washington, DC, USA. "Despite confidently using date labels, many consumers misinterpreted the labels and continued to misunderstand even after reading educational messaging that explained the labels' meaning."

Less than half (46 percent) of study respondents knew that the "BEST If Used By" label specifically indicates that food quality may deteriorate after the date on the label. Less than one-quarter (24 percent) of study respondents knew that the "USE By" label means that food is not safe to eat after the date on the label.

Researchers explored if framing the messages with values like saving money or avoiding waste, would impact the effectiveness of messages at increasing consumer understanding. None of the seven value frames tested was significantly more effective at increasing understanding than another, but all messages significantly increased consumer's general understanding of the labels.

After viewing educational messages, 37 percent of consumers still did not understand the specific meaning of the "BEST If Used By" label and 48 percent did not understand the specific meaning of the "USE By" label.

"Responses to the survey suggest that date labels are so familiar that some consumers believe they are boring, self-explanatory, or common sense despite misunderstanding the labels," said Ms. Turvey. "Unwarranted confidence and the familiarity of date labels may make consumers less attentive to educational messaging that explains the food industry's labeling system."

Future communication campaigns will have to capture the attention of people who think they already know what date labels mean, find the information tedious, or are satisfied with a rough understanding of labels. Educating consumers about the meaning of the labels has growing implications for food waste and food safety as the 2-date labeling system becomes more widely adopted and gains support from non-profits and government institutions.

Many consumers misinterpret food date labels, yet use them with confidence (AUDIO)

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Misunderstanding food date labeling is common and educational communications are needed to improve consumer understanding, according to a new study.

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Journal of Nutrition Education and Behavior

Hydrogen instead of electrification? Potentials and risks for climate targets

POTSDAM INSTITUTE FOR CLIMATE IMPACT RESEARCH (PIK)

Research News

 

Hydrogen-based fuels should primarily be used in sectors such as aviation or industrial processes that cannot be electrified, finds a team of researchers. Producing these fuels is too inefficient, costly and their availability too uncertain, to broadly replace fossil fuels for instance in cars or heating houses. For most sectors, directly using electricity for instance in battery electric cars or heat pumps makes more economic sense. Universally relying on hydrogen-based fuels instead and keeping combustion technologies threatens to lock in a further fossil fuel dependency and greenhouse gas emissions.

"Hydrogen-based fuels can be a great clean energy carrier - yet great are also their costs and associated risks," says lead author Falko Ueckerdt from the Potsdam Institute for Climate Impact Research (PIK). "Fuels based on hydrogen as a universal climate solution might be a bit of false promise. While they're wonderfully versatile, it should not be expected that they broadly replace fossil fuels. Hydrogen-based fuels will likely be scarce and not competitive for at least another decade. Betting on their wide-ranging use would likely increase fossil fuel dependency: if we cling to combustion technologies and hope to feed them with hydrogen-based fuels, and these turn out to be too costly and scarce, then we will end up further burning oil and gas and emit greenhouse gases. This could endanger short- and long-term climate targets."

Prioritizing to applications like aviation and steel productions

"We should hence prioritize those precious hydrogen-based fuels to applications for which they are indispensable: long-distance aviation, feedstocks in chemical production, steel production and potentially some high-temperature industrial processes," says Ueckerdt. "These are sectors and applications that we can hardly electrify directly." The researchers identify a "merit-order of hydrogen and e-fuel demand": a priorization of where to use these new fuels.

So-called green hydrogen is produced through a process called electrolysis. To crack the stable H2O water molecules into Hydrogen and Oxygen, a lot of electricity is needed. The hydrogen can then be used to synthesize hydrocarbon fuels by adding carbon from CO2. The resulting electro-fuels or e-fuels are easier to store and transport than electricity or pure hydrogen. "Most importantly, e-fuels can be burned in conventional combustion processes and engines and thus directly substitute fossil fuels," says Gunnar Luderer, co-author of the paper. "However, given their limited availability, it would be wrong to think that fossils can be fully replaced this way."

Driving a car with hydrogen-based fuels needs five times more energy than a battery-electric car

"We are currently far from 100% renewable electricity - so making efficient use of it is key. However, if we use hydrogen-based fuels instead of direct electrification alternatives, two to fourteen times the amount of electricity generation is needed, depending on the application and the respective technologies," says co-author Romain Sacchi from the Paul Scherrer Institute. "Efficiency losses happen both on the supply side, in the production process of the hydrogen-based fuels, and on the demand side - a combustion engine wastes a lot more energy than an electrical one."

"Low energy efficiencies cause a fragile climate effectiveness," says Sacchi. "If produced with the current electricity mixes, hydrogen-based fuels would increase - not decrease - greenhouse gas emissions. For the German electricity mix in 2018, using hydrogen-based fuels in cars, trucks or planes would produce about three to four times more greenhouse gas emissions than using fossil fuel." In contrast, electric cars or trucks cause greenhouse-gas emissions that are comparable to or lower than those of diesel or gasoline cars already based on today's electricity mixes in most countries, the researchers show based on a full cradle-to-grave life-cycle analysis that includes also those emission associated with the battery production.

"Only for truly renewable-based power systems do hydrogen-based fuels become an effective means to help stabilize our climate", says co-author Jordan Everall. "Hydrogen-based fuels thus clearly require building up loads of additional renewable energy production facilities."

Greenhouse gas abatement costs of hydrogen-based fuels are currently around 1000 Euro per ton CO2

Even if assuming 100% renewable electricity, the costs of avoiding one ton of CO2 emissions by using hydrogen-based fuels would currently be 800 Euro for liquid and 1200 Euro for gaseous fuels, the researchers calculated. This is much higher than current CO2 prices for instance in the European Emissions Trading Scheme, which currently are below 50 Euro per ton. However, if there is continued technological progress driven by CO2 prices as well as subsidies and investments into hydrogen and related industries, by 2050 these CO2 abatement costs could drop to roughly 20 Euro for liquid and 270 Euro for gaseous e-fuels.

Hence, with increasing CO2 prices hydrogen-based fuels could become cost competitive probably by 2040. This is too late for those sectors where direct electrification alternatives exist, given the urgency of greenhouse gas emissions reductions to stabilize our climate.

Carbon pricing is needed to make hydrogen-based fuels competitive

"Despite the uncertainties about future costs, hydrogen-based fuels have the potential to become a backstop technology for replacing all remaining fossil fuels around 2040-50. However, the realization hinges on substantial large-scale policy support and in fact subsidies for about two decades before business cases might be secured solely by increasing carbon pricing," says Falko Ueckerdt. "An overall policy strategy could rest on two pillars: First, broad technology support to foster innovation and initial scale-up including direct electrification. Second, substantial carbon pricing and an energy tax reform that together create a level-playing field for all technologies and thus a sensible balance between direct and indirect electrification."

"The long term vision of hydrogen-based fuels is promising," says Gunnar Luderer. "Tapping into the huge wind and solar energy potential of the global sun belts, e-fuels can be globally traded and thus resolve renewable energy bottlenecks in densely populated countries such as Japan or in Europe. However, as international and national climate targets require immediate emission reductions, from a climate perspective direct electrification should come first to assure a safe future for all."

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Article: Falko Ueckerdt, Christian Bauer, Alois Dirnaichner, Jordan Everall, Romain Sacchi, Gunnar Luderer (2021): Potential and risks of hydrogen-based e-fuels in climate change mitigation. Nature Climate Change [DOI:10.1038/s41558-021-01032-7]

 

Men with chest pain receive faster, more medical attention than women

Women with possible heart attack wait longer and undergo less testing, study finds

AMERICAN COLLEGE OF CARDIOLOGY

Research News

 

Among younger adults visiting the emergency department for chest pain, women may be getting the short end of the stick. Compared with men of similar age, women were triaged less urgently, waited longer to be seen, and were less likely to undergo basic tests or be hospitalized or admitted for observation to diagnose a heart attack, according to new research being presented at the American College of Cardiology's 70th Annual Scientific Session.

The study is the first to examine emergency room management of chest pain specifically among younger adults (age 18-55 years). Heart disease is the leading cause of death in women and is becoming more common in younger adults. About one-third of women who were hospitalized for a heart attack in the past two decades were under the age of 55, a proportion that has grown in recent years.

"Women should trust their instincts," said Darcy Banco, MD, an internal medicine resident at NYU Langone Health and the study's lead author. "Women should seek care right away if they experience new chest discomfort, difficulty breathing, nausea, vomiting, fatigue, sweating or back pain, as these could all be signs of a heart attack. The most important thing a woman can do is to seek medical care if she is worried and to ask specific questions of her doctor."

Chest discomfort is the most common symptom of a heart attack in both men and women, but research shows that women can have a broader range of accompanying symptoms that may not initially be recognized as a sign of a heart attack. Chest discomfort caused by a heart attack can be perceived as pain, pressure, tightness or another uncomfortable sensation.

The study is based on data collected by the National Hospital Ambulatory Medical Care Survey between 2014-2018. Researchers extrapolated the data to represent an estimated 29 million emergency department visits for chest pain in the U.S. among adults aged 18-55; women comprised nearly 57% of those visits.

Researchers found that women reporting chest pain were equally likely to arrive at the hospital by ambulance but significantly less likely than men to be triaged as emergent. On average, women waited about 11 minutes longer to be evaluated by a clinician. Women were also significantly less likely to undergo an electrocardiogram (EKG), the standard initial test used to diagnose a heart attack, or to receive cardiac monitoring or be seen by a consultant, such as a cardiologist.

Medical guidelines recommend that all patients with possible heart attack symptoms receive an EKG within 10 minutes of arrival in the emergency department to minimize the time to treatment.

"Time is very important when you're treating heart attacks," Banco said. "The longer people wait, the worse their outcomes can be."

The study did not examine the reasons why women with chest pain were treated differently than men. Banco suggested that pre-conceived notions of risk--rather than overt discrimination--likely play a role. Historically, heart attacks have been most common in older men, and clinicians may be less likely to suspect a heart attack among patients outside of that demographic. Banco suggested clinicians should appreciate that younger women represent a growing portion of heart attack patients.

"We, as health care providers, should continue to learn about how best to triage and diagnose patients with heart attacks, particularly among those who have historically been under-diagnosed or under-treated," Banco said. "We are learning that heart attacks take many forms. We need to continue to raise awareness and make sure all patients are diagnosed and treated properly, even if they're not the 'classic' demographic for a heart attack. [This knowledge] will help us improve care for all."

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Banco will present the study, "Sex Differences in Evaluation and Management of Young Adults Presenting to the Emergency Department with Chest Pain," on Saturday, May 15, at 9:30 a.m. ET / 13:30 UTC.

To learn more about women and heart disease, visit CardioSmart.org/women.

ACC.21 will take place May 15-17 virtually, bringing together cardiologists and cardiovascular specialists from around the world to share the newest discoveries in treatment and prevention. Follow @ACCinTouch, @ACCMediaCenter and #ACC21 for the latest news from the meeting.

The American College of Cardiology envisions a world where innovation and knowledge optimize cardiovascular care and outcomes. As the professional home for the entire cardiovascular care team, the mission of the College and its 54,000 members is to transform cardiovascular care and to improve heart health. The ACC bestows credentials upon cardiovascular professionals who meet stringent qualifications and leads in the formation of health policy, standards and guidelines. The College also provides professional medical education, disseminates cardiovascular research through its world-renowned JACC Journals, operates national registries to measure and improve care, and offers cardiovascular accreditation to hospitals and institutions. For more, visit ACC.org.

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