Trading Surfboards for Snowboards: Storms Have Left Abundant Snow Atop Hawaii’s Tallest Volcanic Mountains
Three storms in three weeks have left abundant snow atop Hawaii’s tallest volcanic mountains.
Snow is not as rare as you might think in the Hawaiian Islands. But it never stops being beautiful.
On February 6, 2021, the Operational Land Imager (OLI) on Landsat 8 acquired natural-color images of the “Big Island” of Hawai’i with abundant snow on its two tallest peaks. Nearly every year, Mauna Kea and Mauna Loa (elevation above 13,600 feet/4200 meters) receive at least a dusting that lasts a few days. Sometimes, like this year, it is more like a winter blanket of snow.
Starting with a moderate storm on January 18, 2021, snow has fallen three times on the highlands of Hawai’i in the past three weeks. The snow cover has persisted on Mauna Kea and Mauna Loa—the two tallest volcanoes in the island chain—since January 25. Some snow also briefly crowned Haleakalā volcano (elevation 10,000 feet/3000 meters) on the island of Maui.
The bar chart below shows the Normalized Difference Snow Index (NDSI) for Hawai’i as observed by NASA’s Terra satellite. NDSI incorporates a blend of visible light and shortwave infrared to assess the amount of snow within a given geographic area. The chart shows the combined NDSI for Mauna Loa (teal) and Mauna Kea (blue) for the first week of February in each year from 2001 to 2021. The combined weekly NDSI in 2021 for the two volcanoes is the highest since 2014 and second-highest in the record.
According to news and social media accounts, Hawaiians have found their way up the volcanic mountains with snowboards and boogie boards to sled through the fluffy white blanket. Others have filled their pickup truck beds to bring snow down to friends. Hawaiian weather blogger Weatherboy posted several photos from the scene.
Snowfall in Hawai’i is often associated with a weather phenomenon referred to as a Kona low. Winds that typically blow out of the northeast shift and blow from the southwest. The winds from the leeward or “Kona” side draw moisture from the tropical Pacific, turning it from rain to snow as the air rises up into the high elevations.
With the recent snowfall in Hawai’i, Florida is now the only state that has not yet seen snow this winter, according to The Weather Channel.
NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S. Geological Survey and data from the National Snow and Ice Data Center.
Peanut Allergy Affects Even More Adults Than Children in U.S. – Many Report Their First Symptom as Adults
2.9% of U.S. adults report a current peanut allergy. About one in six adults with a peanut allergy developed it after age 18. Approximately one in five adults with peanut allergy report visiting the emergency department for food allergy treatment each year. Patients who developed their peanut allergy during adulthood are less likely to report having an epinephrine auto-injector prescription than those who developed their peanut allergy during childhood, despite similar frequencies of severe reactions among both groups.
Peanut allergy affects at least 4.5 million adults in the U.S., many of whom report developing their first allergy symptoms during adulthood, reports a new Northwestern Medicine study.
However, despite the fact that roughly three out of four Americans with peanut allergy are over 17 years old, peanut allergy is often considered a predominantly pediatric concern. For example, earlier this year the U.S. Food and Drug Administration (FDA) approved a peanut allergy therapy for initiation in pediatric patients ages 4-17. There are currently no FDA-approved therapies for patients with adult-onset food allergy.
The new study provides the first detailed estimates of peanut allergy among U.S. adults in all 50 states, which was previously unknown. These data indicate peanut allergy may be more common than previously acknowledged, and while younger adults are most affected, peanut allergy impacts U.S. adults of all ages.
“Currently, the sole FDA-approved peanut allergy therapy — Palforzia — is only indicated for pediatric patients. Given the high prevalence of peanut allergy among U.S. adults, additional therapies are needed to help address this growing burden of disease,” said senior study author Dr. Ruchi Gupta, professor of pediatrics at Northwestern University Feinberg School of Medicine and a physician at Ann & Robert H. Lurie Children’s Hospital of Chicago.
Gupta also is director of the Center for Food Allergy and Asthma Research at Feinberg.
The paper will be published today (February 9, 2021) in the Journal of Allergy and Clinical Immunology.
The study found 2.9% of U.S. adults report a current peanut allergy, while 1.8% report a physician-diagnosed peanut allergy and/or a history of peanut-allergic reaction symptoms. In addition, researchers found two in three adults with peanut allergy have at least one other food allergy — most commonly tree nuts but more than one in five are also allergic to shellfish.
The data also indicate many individuals who report peanut allergies and experience potentially severe allergic reactions are not obtaining clinical diagnosis of their allergies.
“Clinical confirmation of suspected food allergies, no matter when their reported onset, is critical to reduce the risk of unnecessary allergen exposure as well as to ensure patients receive essential counseling and prescription of emergency epinephrine,” said study co-first author Dr. Dawn Lei, a clinical instructor of pediatrics at Feinberg and an allergist and immunologist at Edward Hines Jr. VA Hospital.
Christopher Warren, director of population health at Feinberg’s Center for Food Allergy and Asthma Research and co-first author added, “Unlike allergies such as milk or egg, which often develop early in life and are outgrown by adolescence, peanut allergy appears to affect children and adults to a similar degree. Our study shows many adults are not outgrowing their childhood peanut allergies, and many adults are developing peanut allergies for the first time.
“Worryingly, despite reporting similar rates of severe reactions and annual food allergy-related emergency room visits, patients with adult-onset peanut allergy were less likely to report a physician-diagnosis as well as a current epinephrine prescription.”
Together, these data suggest additional efforts are needed to ensure optimal food allergy diagnosis and management among adults with peanut allergy, study authors said.
Reference: 9 February 2021, Journal of Allergy and Clinical Immunology.
Study investigators administered a survey via telephone and web to more than 40,000 U.S. adults asking detailed information about any suspected food allergies, including specific allergic-reaction symptoms, details about clinical diagnosis of food allergies, as well as demographic information.
Other Northwestern authors include Robert Schleimer.
The research was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, grant R21AI135702.
Antibiotic Game-Changer: Phages Can Anticipate Bacteria’s Location and Destroy Them Before They Cause an Infection
Researchers at Baylor College of Medicine and other institutions have identified a novel strategy that can eliminate bacteria in a specific location before they cause an infection. The strategy uses a phage, a virus that infects and destroys bacteria, that can specifically locate in the same place the bacteria live in the gastrointestinal tract. The proximity between phage and bacteria facilitates the phage’s attack and subsequent elimination of the bacteria.
This strategy has the potential of becoming a game changer in the fight against antibiotic-resistant bacteria that live in hard-to-reach places, such as the mucus layer of the gut. The study appears in the journal mBio.
“Phages are very specific in their ability to infect and destroy certain species or strains of bacteria and not others, such as good bacteria. In the U.S., phage therapy is increasingly becoming an available option to treat antibiotic-resistant bacterial infections, a serious health concern,” said first author Dr. Sabrina Green, director of research and development for TAILΦR labs at Baylor.
Antibiotic-resistant bacteria, such as ExPEC ST131, can colonize the human intestine without causing disease, but they also can exit the gut and infect other organs. For instance, these bacteria have been associated with infections of the urinary tract, brain, peritoneum, peripheral organs, blood and in-dwelling devices, such as urinary catheters, vascular devices, feeding tubes and wound drains, resulting in 9 million infections per year.
The team showed in previous work that phages can effectively treat an infection caused by ExPEC ST131 bacteria. In this study, they wanted to see if they could use phages to remove these bacteria to prevent an infection.
Finding the right phage
Many phages have a hard time fighting bacteria in the gut. The team discovered that there is a factor present in mammalian intestines that prevents phages from destroying bacteria. They identified the factor as mucin, sticky proteins that form a layer between intestinal epithelial cells and the layer of microorganisms.
The researchers reasoned that although mucins prevent many phages from infecting bacteria, there may be some that have evolved a way to counter the effect of mucins and, as a result, are able to target bacteria in high-mucin environments.
“We screened human sewage and animal feces for phages with unique properties that facilitate their ability to destroy bacteria in the presence of mucins,” said corresponding author Dr. Anthony Maresso, associate professor of molecular virology and microbiology at Baylor. “We discovered a novel phage called ES17 that binds to mucins, and this property seemed to enhance its ability to infect bacteria in mucin-rich environments, such as the gut.”
Further studies looked closer at this novel phage-mucin interaction. Green, Maresso and their colleagues discovered that phage ES17 binds to particular molecules called heparan sulfate which can be found not only in mucins, but also on the surface of various cells types, including epithelial cells. This prompted the researchers to investigate whether binding to heparan sulfate on epithelial cells, which the researchers had also discovered is the same binding site used by ES17’s host bacteria ExPEC, would contribute to ES17’s ability to target and destroy the bacteria in the gut environment.
“We tested the effect of phage ES17 on its bacterial host ExPEC in a murine intestine, comparing it with phages known to be unable to infect their bacterial host in complex environments,” Green said. “We found that only ES17 had the unique ability to target and eliminate ExPEC bacteria in animal models.”
A novel strategy to prevent bacterial infections
Taken altogether, the findings suggest that the ability of phage ES17 to bind to heparan sulfate on mucin-rich surfaces and directly on mammalian epithelial cells mediates its localization in areas deep in the gut where reservoirs of bacteria may be present. The researchers propose that being close to ExPEC bacteria facilitates phage invasion and bacterial elimination before they have the opportunity to exit the gut and infect other organs.
“Phages are viruses that specialize in invading and eliminating specific bacteria. Here we have shown the first phage that also binds to epithelial human cells and that this property mediates a novel mechanism for fighting bacterial infections we call positional targeting, as it enables the phage to anticipate where the bacteria it targets will be located,” Maresso said. “We foresee the possibility that positional targeting will be the way smart drugs work in the future. Drugs won’t be just distributed all through the body in the hopes that some of it will end in the right spot. The drugs of the future will go only precisely where they are supposed to work. Our work with phages is the first case in which this has been achieved.”
Reference 9 February 2021, mBio.
Other contributors to this work include Carmen Gu Liu, Xue Ya, Shelley Gibson, Wilhem Salmen, Anubama Rajan, Hannah E. Carter, Justin R. Clark, Xuezheng Song, Robert F. Ramig, Barbara W. Trautner and Heidi B. Kaplan. The authors are affiliated with one or more of the following institutions: Baylor College of Medicine, Emory University, Michael E. DeBakey Veterans Affairs Medical Center and University of Texas Health Science Center at Houston.
This work is supported in part by a grant from U.S. Veterans Affairs (VA I01-RX002595), Roderick D. MacDonald Research Fund at Baylor St. Luke’s Medical Center, the Mike Hogg Foundation and Baylor College of Medicine Seed Fund.
Groundbreaking New Study Compares Vegan and Mediterranean Diets for Weight Loss and Cholesterol Control
A vegan diet is more effective for weight loss than a Mediterranean diet, according to a groundbreaking new study that compared the diets head to head. The randomized crossover trial, which was published in the Journal of the American College of Nutrition, found that a low-fat vegan diet has better outcomes for weight, body composition, insulin sensitivity, and cholesterol levels, compared with a Mediterranean diet.
The study randomly assigned participants–who were overweight and had no history of diabetes–to a vegan diet or a Mediterranean diet in a 1:1 ratio. For 16 weeks, half of the participants started with a low-fat vegan diet that eliminated animal products and focused on fruits, vegetables, whole grains, and legumes. The other half started with the Mediterranean diet, which followed the PREDIMED protocol, which focuses on fruits, vegetables, legumes, fish, low-fat dairy, and extra virgin olive oil, while limiting or avoiding red meat and saturated fats. Neither group had a calorie limit, and participants did not change exercise or medication routines, unless directed by their personal doctors. As part of the crossover design, participants then went back to their baseline diets for a four-week washout period before switching to the opposite group for an additional 16 weeks.
The study found that within 16 weeks on each diet:
Participants lost an average of 6 kilograms (or about 13 pounds) on the vegan diet, compared with no mean change on the Mediterranean diet. Participants lost 3.4 kg (about 7.5 pounds) more fat mass on the vegan diet. Participants saw a greater reduction in visceral fat by 315 cm3 on the vegan diet. The vegan diet decreased total and LDL cholesterol levels by 18.7 mg/dL and 15.3 mg/dL, respectively, while there were no significant cholesterol changes on the Mediterranean diet. Blood pressure decreased on both diets, but more on the Mediterranean diet (6.0 mm Hg, compared to 3.2 mmHg on the vegan diet).
“Previous studies have suggested that both Mediterranean and vegan diets improve body weight and cardiometabolic risk factors, but until now, their relative efficacy had not been compared in a randomized trial,” says study author Hana Kahleova, MD, PhD, director of clinical research for the Physicians Committee. “We decided to test the diets head to head and found that a vegan diet is more effective for both improving health markers and boosting weight loss.”
The authors note that the vegan diet likely led to weight loss, because it was associated with a reduction in calorie intake, increase in fiber intake, decrease in fat consumption, and decrease in saturated fat consumption.
“While many people think of the Mediterranean diet as one of the best ways to lose weight, the diet actually crashed and burned when we put it to the test,” says study author Neal Barnard, MD, president of the Physicians Committee. “In a randomized, controlled trial, the Mediterranean diet caused no weight loss at all. The problem seems to be the inclusion of fatty fish, dairy products, and oils. In contrast, a low-fat vegan diet caused significant and consistent weight loss.”
“If your goal is to lose weight or get healthy in 2021, choosing a plant-based diet is a great way to achieve your resolution,” adds Dr. Kahleova.
Reference: “A Mediterranean Diet and Low-Fat Vegan Diet to Improve Body Weight and Cardiometabolic Risk Factors: A Randomized, Cross-over Trial” by Neal D. Barnard, Jihad Alwarith, Emilie Rembert, Liz Brandon, Minh Nguyen, Andrea Goergen, Taylor Horne, Gabriel F. do Nascimento, Kundanika Lakkadi, Andrea Tura, Richard Holubkov and Hana Kahleova, 5 February 2021, Journal of the American College of Nutrition.
NASA and three international partners have signed a statement of intent to advance a possible robotic Mars ice mapping mission, which could help identify abundant, accessible ice for future candidate landing sites on the Red Planet. The agencies have agreed to establish a joint concept team to assess mission potential, as well as partnership opportunities.
Under the statement, NASA, the Italian Space Agency (ASI), the Canadian Space Agency (CSA), and the Japan Aerospace Exploration Agency (JAXA) announced their intention to develop a mission plan and define their potential roles and responsibilities. If the concept moves forward, the mission could be ready to launch as early as 2026.
The international Mars Ice Mapper mission would detect the location, depth, spatial extent, and abundance of near-surface ice deposits, which would enable the science community to interpret a more detailed volatile history of Mars. The radar-carrying orbiter would also help identify properties of the dust, loose rocky material – known as regolith – and rock layers that might impact the ability to access ice.
The ice-mapping mission could help the agency identify potential science objectives for initial human missions to Mars, which are expected to be designed for about 30 days of exploration on the surface. For example, identifying and characterizing accessible water ice could lead to human-tended science, such as ice coring to support the search for life. Mars Ice Mapper also could provide a map of water-ice resources for later human missions with longer surface expeditions, as well as help meet exploration engineering constraints, such as avoidance of rock and terrain hazards. Mapping shallow water ice could also support supplemental high-value science objectives related to Martian climatology and geology.
“This innovative partnership model for Mars Ice Mapper combines our global experience and allows for cost sharing across the board to make this mission more feasible for all interested parties,” said Jim Watzin, NASA’s senior advisor for agency architectures and mission alignment. “Human and robotic exploration go hand in hand, with the latter helping pave the way for smarter, safer human missions farther into the solar system. Together, we can help prepare humanity for our next giant leap – the first human mission to Mars.”
As the mission concept evolves, there may be opportunities for other space agencies and commercial partners to join the mission.
Beyond promoting scientific observations while the orbiter completes its reconnaissance work, the agency partners will explore mission-enabling rideshare opportunities as part of their next phase of study. All science data from the mission would be made available to the international science community for both planetary science and Mars reconnaissance.
This approach is similar to what NASA is doing at the Moon under the Artemis program – sending astronauts to lunar South Pole, where ice is trapped in the permanently shadowed regions of the pole.
Access to water ice would also be central to scientific investigations on the surface of Mars that are led by future human explorers. Such explorers may one day core, sample, and analyze the ice to better understand the record of climatic and geologic change on Mars and its astrobiological potential, which could be revealed through signs of preserved ancient microbial life or even the possibility of living organisms, if Mars ever harbored life.
Ice is also a critical natural resource that could eventually supply hydrogen and oxygen for fuel. These elements could also provide resources for backup life support, civil engineering, mining, manufacturing, and, eventually, agriculture on Mars. Transporting water from Earth to deep space is extremely costly, so a local resource is essential to sustainable surface exploration.
“In addition to supporting plans for future human missions to Mars, learning more about subsurface ice will bring significant opportunities for scientific discovery,” said Eric Ianson, NASA Planetary Science Division Deputy Director and Mars Exploration Program Director. “Mapping near-surface water ice would reveal an as-yet hidden part of the Martian hydrosphere and the layering above it, which can help uncover the history of environmental change on Mars and lead to our ability to answer fundamental questions about whether Mars was ever home to microbial life or still might be today.”
The Red Planet is providing great research return for robotic exploration and the search for ancient life in our solar system. This latest news comes ahead of the agency’s Perseverance rover landing on Mars, which is scheduled to take place on February 18, following a seven-month journey in space. NASA and the European Space Agency (ESA) also recently announced they are moving forward with the Mars Sample Return mission.
Our consumer products, such as food, cosmetics, and clothes, might be filled with nanomaterials — unbeknownst to us. The use of nanomaterials remains unregulated and they do not show up in lists of ingredients. This is a cause of concern since nanomaterials can be more dangerous than COVID-19 in the long term if no safety action is taken: they are tricky to measure, they enter our food chain and, most alarmingly, they can penetrate cells and accumulate in our organs.
Nanotechnology is appearing everywhere, to change our daily lives. Thanks to applications of nanotechnology, we can treat many diseases so efficiently that they’ll soon be a thing of the past. We also have materials that are 100 times stronger than steel, batteries that last 10 times longer than before, solar panels that yield twice as much energy than old ones, skincare products that keep us looking young, not to mention self-cleaning cars, windows, and clothes. These used to be the stuff of science fiction and Hollywood movies, but are now the reality we live in.
Nanotechnology has the potential to become the next industrial revolution. The global market for nanomaterials is growing, estimated at 11 million tonnes at a market value of 20 billion euros. The current direct employment in the nanomaterial sector is estimated between 300,000 and 400,000 in Europe alone.
Yet, nanomaterials and their use in consumer products is far from unproblematic. A new study published in Nature Communications today sheds light on whether they are harmful and what happens to them when they enter an organism. An international team of researchers developed a sensitive method to find and trace nanomaterials in blood and tissues, and traced nanomaterials across an aquatic food chain, from microorganisms to fish, which is a major source of food in many countries. This method can open new horizons for taking safety actions.
“We found that nanomaterials bind strongly to microorganisms, which are a source of food for other organisms, and this is the way they can enter our food chain. Once inside an organism, nanomaterials can change their shape and size and turn into a more dangerous material that can easily penetrate cells and spread to other organs. When looking at different organs of an organism, we found that nanomaterials tend to accumulate especially in the brain,” lead author Dr. Fazel A. Monikh from the University of Eastern Finland says.
According to the researchers, nanomaterials are also difficult to measure: their amount in an organism cannot be measured only by using their mass, which is the standard method for measuring other chemicals for regulations. The findings emphasize the importance of assessing the risk of nanomaterials before they are introduced to consumer products in large amounts. A better understanding of nanomaterials and their risks can help policymakers to introduce stricter rules on their use, and on the way they are mentioned in products’ lists of ingredients.
“It could be that you are already using nanomaterials in your food, clothes, cosmetic products, etc., but you still don’t see any mention of them in the ingredient list. Why? Because they are still unregulated and because they are so small that we simply can’t measure them once they’re in your products,” Dr Fazel A. Monikh says.
“People have the right to know what they are using and buying for their families. This is a global problem which needs a global solution. Many questions about nanomaterials still need to be answered. Are they safe for us and the environment? Where will they end up after we’re done using them? How can we assess their possible risk?” Dr. Fazel A. Monikh concludes.
Reference: “Particle number-based trophic transfer of gold nanomaterials in an aquatic food chain” by Fazel A. Monikh, L. Chupani, D. Arenas-Lago, Z. Guo, P. Zhang, G. Krishna Darbha, E. Valsami-Jones, I. Lynch, M. G. Vijver 1, P. M. van Bodegom and W. J.G.M. Peijnenburg, 9 February 2021, Nature Communications.
The study was conducted in collaboration between the University of Eastern Finland (Finland), Leiden University (the Netherlands), the National Institute of Public Health and the Environment (the Netherlands), the University of South Bohemia (Czech Republic), the University of Birmingham (the United Kingdom), the Environmental Nanoscience Laboratory (India), and the University of Vigo (Spain).
Study of Supergiant Star Betelgeuse Unveils the Cause of Its Pulsations – Not at All Close to Exploding
Recalibrated Betelgeuse’s mass, radius, and distance.
Betelgeuse is normally one of the brightest, most recognizable stars of the winter sky, marking the left shoulder of the constellation Orion. But lately, it has been behaving strangely: an unprecedentedly large drop in its brightness has been observed in early 2020 (Figure 1), which has prompted speculation that Betelgeuse may be about to explode.
To find out more, an international team of scientists, including Ken’ichi Nomoto at the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), conducted a rigorous examination of Betelgeuse. They concluded that the star is in the early core helium-burning phase (which is more than 100,000 years before an explosion happens) and has smaller mass and radius—and is closer to Earth—than previously thought. They also showed that smaller brightness variations of Betelgeuse have been driven by stellar pulsations, and suggested that the recent large dimming event involved a dust cloud.
The research team is led by Dr. Meridith Joyce from the Australian National University (ANU), who was an invited speaker at Kavli IPMU in January 2020, and includes Dr. Shing-Chi Leung, a former Kavli IPMU project researcher and a current postdoctoral scholar at the California Institute of Technology, and Dr. Chiaki Kobayashi, an associate professor at the University of Hertfordshire, who has been an affiliate member of Kavli IPMU.
The team analyzed the brightness variation of Betelgeuse (Figure 2) by using evolutionary, hydrodynamic and seismic modelling. They achieved a clearer idea than before that Betelgeuse is currently burning helium in its core. They also showed that stellar pulsations driven by the so-called kappa-mechanism is causing the star to continuously brighten or fade with two periods of 185 (±13.5) days and approximately 400 days. But the large dip in brightness in early 2020 is unprecedented, and is likely due to a dust cloud in front of Betelgeuse, as seen in the image (Figure 1).
Their analysis reported a present-day mass of 16.5 to 19 solar mass—which is slightly lower than the most recent estimates. The study also revealed how big Betelgeuse is, as well as its distance from Earth. The star’s actual size has been a bit of a mystery: earlier studies, for instance, suggested it could be bigger than the orbit of Jupiter. However, the team’s results showed Betelgeuse only extends out to two-thirds of that, with a radius 750 times the radius of the sun. Once the physical size of the star is known, it will be possible to determine its distance from Earth. Thus far, the team’s results show it is a mere 530 light years from us, or 25 percent closer than previously thought.
Their results imply that Betelgeuse is not at all close to exploding, and that it is too far from Earth for the eventual explosion to have significant impact here, even though it is still a really big deal when a supernova goes off. And as Betelgeuse is the closest candidate for such an explosion, it gives us a rare opportunity to study what happens to stars like this before they explode.
Reference: “Standing on the Shoulders of Giants: New Mass and Distance Estimates for Betelgeuse through Combined Evolutionary, Asteroseismic, and Hydrodynamic Simulations with MESA” by Meridith Joyce, Shing-Chi Leung, László Molnár, Michael Ireland, Chiaki Kobayashi and Ken’ichi Nomoto, 13 October 2020, The Astrophysical Journal.
Contrast is a sensory property that makes stimuli stand out. Writers, designers, and musicians all use contrast to emphasize striking differences in text, visual displays and melodies. In vision, luminance contrast describes the difference in light intensity between a stimulus and its surround.
It is what makes a dark letter easier to read than a gray letter in a white page. Vision research has operated for decades under the assumption that luminance contrast does not change with light intensity. That is, a dark letter in a white page is assumed to have the same contrast outdoors (under the brightest light) than indoors (under the dimmest light). Such contrast constancy seemed obviously important. How could it be otherwise? If contrast was not preserved across different light intensities, a black letter indoors would become white outdoors because it reflects much more light.
State University of New York College of Optometry researcher Hamed Rahimi-Nasrabadi, PhD, and collaborators now demonstrate that this decades-old assumption is incorrect and can cause important measurement errors that have general implications in basic research, the eye clinic and the multiple disciplines that depend on accurate estimates of visual contrast.
For example, it can lead to inaccurate measurements of visual sensitivity in eye disease, the rendering of contrast in medical images or the architectural design of spaces for the visually impaired and elderly.
The new findings demonstrate that, as visual acuity, contrast sensitivity is strongly dependent on the amount of light. Increasing the amount of light shifts the contrast sensitivity for dark and light stimuli (i.e. stimuli darker or lighter than their surround) in opposite directions. It improves the discrimination of the darkest contrasts (e.g. making it easier to see subtle differences in eye shadow) while severely impairing the discrimination of the brightest contrasts (e.g. making it more difficult to discriminate luminance differences between the brightest specular reflections of a shiny car).
The opposite shifts of dark and light contrast with light intensity can be demonstrated in neurons of the visual cortex, natural scenes, and appear to be well preserved across different species of mammals. The new findings can be also used to improve current algorithms of image processing and metrics of visual contrast.
Findings from the investigation conclude that you can now feel good when you decide to read your favorite book outdoors. You can say that it is scientifically proven that visual contrast increases outdoors and, therefore, reading under bright light stimulates your visual brain more effectively, allows you to see the letters better, and helps your eyesight.
Reference: “Image luminance changes contrast sensitivity in visual cortex” by Hamed Rahimi-Nasrabadi, Jianzhong Jin, Reece Mazade, Carmen Pons, Sohrab Najafian and Jose-Manuel Alonso, 2 February 2021, Cell Reports.
The investigation was conducted by Dr. Hamed Rahimi-Nasrabadi and collaborators in the laboratories of Jose Manuel Alonso, MD, PhD, at the State University of New York College of Optometry.
Scientists shed light on how the magnetic properties of 2D interlayers can enhance spin accumulation effects in thermoelectric heterostructures.
Spin thermoelectric materials are an area of active research because of their potential applications in thermal energy harvesters. However, the physics underlying the effects of interlayers in these materials on spin transport phenomena are unclear. In a recent study, scientists from Chung-Ang University, Korea, shed light on this topic using a newly developed platform to measure the spin Seebeck effect. Their findings pave the way to large-area thermoelectric materials with enhanced properties.
Thermoelectric materials, which can generate an electric voltage in the presence of a temperature difference, are currently an area of intense research; thermoelectric energy harvesting technology is among our best shots at greatly reducing the use of fossil fuels and helping prevent a worldwide energy crisis. However, there are various types of thermoelectric mechanisms, some of which are less understood despite recent efforts. A recent study from scientists in Korea aims to fill one such gap in knowledge. Read on to understand how!
One of these mechanisms mentioned earlier is the spin Seebeck effect (SSE), which was discovered in 2008 by a research team led by Professor Eiji Saitoh from Tokyo University, Japan. The SSE is a phenomenon in which a temperature difference between a nonmagnetic and a ferromagnetic material creates a flow of spins. For thermoelectric energy harvesting purposes, the inverse SSE is especially important. In certain heterostructures, such as yttrium iron garnet—platinum (YIG/Pt), the spin flow generated by a temperature difference is transformed into a current with an electric charge, offering a way to generate electricity from the inverse SSE.
Because this spin-to-charge conversion is relatively inefficient in most known materials, researchers have tried inserting an atomically thin layer of molybdenum disulfide (MoS2) between the YIG an Pt layers. Though this approach has resulted in enhanced conversion, the underlying mechanisms behind the role of the 2D MoS2 layer in spin transport remains elusive.
To tackle this knowledge gap, Professor Sang-Kwon Lee of the Department of Physics at Chung-Ang University, Korea, has recently led an in-depth study on the topic, which has been published in Nano Letters. Various colleagues from Chung-Ang University participated, as well as Professor Saitoh, in an effort to understand the effect of 2D MoS2 on the thermoelectric power of YIG/Pt.
To this end, the scientists prepared two YIG/MoS2/Pt samples with different morphologies in the MoS2 layer, as well as a reference sample without MoS2 altogether. They prepared a measurement platform in which a temperature gradient can be enforced, a magnetic field applied, and the voltage difference caused by the ensuing spin flow monitored. Interestingly, they found that the inverse SSE, and in turn the thermoelectric performance of the whole heterostructure, can be either enhanced or diminished depending on the size and type of MoS2 used. In particular, using a holey MoS2 multilayer between the YIG and Pt layers yielded a 60% increase in thermoelectric power compared with YIG/Pt alone.
Through careful theoretical and experimental analyses, the scientists determined that this marked increase was caused by the promotion of two independent quantum phenomena that, together, account for the total inverse SSE. These are called the inverse spin Hall effect, and the inverse Rashba–Edelstein effect, which both produce a spin accumulation that is then converted into a charge current. Moreover, they investigated how the holes and defects in the MoS2 layer altered the magnetic properties of the heterostructure, leading to a favorable enhancement of the thermoelectric effect. Excited about the results, Lee remarks: “Our study is the first to prove that the magnetic properties of the interfacial layer cause spin fluctuations at the interface and ultimately increase spin accumulation, leading to a higher voltage and thermopower from the inverse SSE.”
The results of this work represent a crucial piece in the puzzle of thermoelectric materials technology and could soon have real-world implications, as Lee explains: “Our findings reveal important opportunities for large-area thermoelectric energy harvesters with intermediate layers in the YIG/Pt system. They also provide essential information to understand the physics of the combined Rashba–Edelstein effect and SSE in spin transport.” He adds that their SSE measurement platform could be of great help to investigate other types of quantum transport phenomena, such as the valley-driven Hall and Nernst effects.
Let us hope that thermoelectric technology progresses rapidly so that we can make our dreams of a more ecofriendly society a reality!
Reference: “Enhanced Spin Seebeck Thermopower in Pt/Holey MoS2/Y3Fe5O12 Hybrid Structure” by Won-Yong Lee, No-Won Park, Gil-Sung Kim, Min-Sung Kang, Jae Won Choi, Kwang-Yong Choi, Ho Won Jang, Eiji Saitoh and Sang-Kwon Lee, 4 December 2020, Nano Letters.
About Chung-Ang University
Chung-Ang University is a private comprehensive research university located in Seoul, South Korea. It was started as a kindergarten in 1918 and attained university status in 1953. It is fully accredited by the Ministry of Education of Korea. Chung-Ang University conducts research activities under the slogan of “Justice and Truth.” Its new vision for completing 100 years is “The Global Creative Leader.” Chung-Ang University offers undergraduate, postgraduate, and doctoral programs, which encompass a law school, management program, and medical school; it has 16 undergraduate and graduate schools each. Chung-Ang University’s culture and arts programs are considered the best in Korea.
About Professor Sang-Kwon Lee
Dr. Sang-Kwon Lee obtained a PhD in Electronic Engineering from the Royal Institute of Technology, Sweden, in 2002. He was then first appointed Assistant Professor in the Department of Semiconductor Science and Technology at Chonbuk National University, Korea, in 2002 and subsequently joined the Department of Physics at Chung-Ang University in 2013 as a Professor. He is currently in charge of teaching Modern Physics and Mathematical Physics at Chung-Ang University. His research interests mainly revolve around solid state physics, such as the development and modelling of nanoscale thermoelectric materials and devices. He works on nanobiotechnology—such as nanobiological semiconducting sensors and cancer cell characterization through devices such as nanowires—microfluidics, and microelectromechanical systems. Currently, he is also interested in working on valley-related effects, such as the valley-Nernst effect, valley-Hall effect and various new Seebeck effects for energy harvesting applications in his quantum transport research lab at Chung-Ang University. He has over 140 publications to his name.
Pangolin Coronavirus Could Jump to Humans – Similarities Found Between SARS-CoV-2 and a Pangolin Coronavirus
Scientists at the Francis Crick Institute have found important structural similarities between SARS-CoV-2 and a pangolin coronavirus, suggesting that a pangolin coronavirus could infect humans.
While SARS-CoV-2 is thought to have evolved from a bat coronavirus, its exact evolutionary path is still a mystery. Uncovering its history is challenging as there are likely many undiscovered bat coronaviruses and, due to differences between bat coronaviruses and SARS-CoV-2, it is thought that the virus may have passed to humans via at least one other species.
In their study, published in Nature Communications, the scientists compared the structures of the spike proteins found on SARS-CoV-2, the most similar currently identified bat coronavirus RaTG13, and a coronavirus isolated from Malayan pangolins which were seized by authorities after being smuggled to China. They found that the pangolin virus was able to bind to receptors from both pangolins and humans. This differs to the bat coronavirus, which could not effectively bind with human or pangolin receptors.
Antoni Wrobel, co-lead author and postdoctoral training fellow in the Structural Biology of Disease Processes Laboratory at the Crick, says: “By testing if the spike protein of a given virus can bind with cell receptors from different species, we’re able to see if, in theory, the virus could infect this species.”
“Importantly here, we’ve shown two key things. Firstly, that this bat virus would unlikely be able to infect pangolins. And secondly that a pangolin virus could potentially infect humans.”
The team used cryo-electron microscopy to uncover in minute detail the structure of the pangolin coronavirus’ spike protein, which is responsible for binding to and infecting cells. While some parts of the pangolin virus’ spike were found to be incredibly similar to SARS-CoV-2, other areas differed.
In terms of understanding the evolutionary path of SARS-CoV-2, this work does not confirm whether or not this pangolin virus is definitely part of the chain of evolution for SARS-CoV-2. But the findings do support various possible scenarios for how the coronavirus jumped from bats to humans. One potential route is that SARS-CoV-2 originated from a different, currently unknown bat coronavirus which could infect pangolins, and from this species it then moved to humans. Or alternatively, RaTG13 or a similar bat coronavirus might have merged with another coronavirus in a different intermediate species, other than a pangolin.
Donald Benton, co-lead author and postdoctoral training fellow in the Structural Biology of Disease Processes Laboratory at the Crick, says: “We still don’t have evidence to confirm the evolutionary path of SARS-CoV-2 or to prove definitively that this virus did pass through pangolins to humans.”
“However, we have shown that a pangolin virus could potentially jump to humans, so we urge caution in any contact with this species and the end of illegal smuggling and trade in pangolins to protect against this risk.”
Steve Gamblin, group leader of the Structural Biology of Disease Processes Laboratory at the Crick says: “A lot is still to be uncovered about the evolution of SARS-CoV-2, but the more we know about its history and which species it passed through, the more we understand about how it works, and how it may continue to evolve.”
This work builds upon previous studies from the Crick team, including research published in July 2020, which found that the bat coronavirus RaTG13 could not effectively bind to human receptors.
The team are continuing to examine the spikes of SARS-CoV-2 and related coronaviruses, including other bat viruses, to better understand the mechanisms of infection and evolution.
Reference: “Structure and binding properties of Pangolin-CoV spike glycoprotein inform the evolution of SARS-CoV-2” by Antoni G. Wrobel, Donald J. Benton, Pengqi Xu, Lesley J. Calder, Annabel Borg, Chloë Roustan, Stephen R. Martin, Peter B. Rosenthal, John J. Skehel and Steven J. Gamblin, 5 February 2021, Nature Communications.