Also on board are two important Italian instruments created thanks to the contribution of the Italian Space Agency, INAF and Sapienza University of Rome. Alessandro Mura (Inaf): “Jiram’s data will finally be able to reveal how the surface of Ganymede interacts with the external environment, and will be invaluable for planning future observations such as those of the Juice mission currently scheduled for launch next year”
It will be a very close flyby what the NASA probe Juno , in orbit around Jupiter since 2016, will do today with Ganymede , one of its many moons. On board the probe there are numerous scientific instruments, including two with Italian participation with the support of the Italian Space Agency ( ASI ): the Jiram instrument , made in Italy by Leonardo and led by the National Institute of Astrophysics (Inaf); and the radioscience instrument KaT ( Ka-band Translator ), created by Thales Alenia Space and led by the La Sapienza University of Rome.
Juno was launched in August 2011 and is currently studying Jupiter’s magnetic field and atmosphere in an orbit that passes over its poles. The probe has collected an important amount of information to date, so much so that NASA, at the beginning of this year, extended the mission until 2025 .
Jiram ( Jovian Infrared Auroral Mapper , dedicated to Angioletta Coradini, an INAF astronomer who died in 2011 and former Principal Investigator of Jiram) is a near infrared camera (2-5 microns) capable of collecting both images and spectrograms, while the KaT allows the measurement of Jupiter’s gravity through the Doppler effect of a microwave signal.
This extension will make Juno “an explorer” of the entire Jovian system – the planet, its rings and moons – with multiple close passages, called flybys , planned for the three of Jupiter’s most intriguing Galilean moons: Ganymede, Europa and Io . Satellite encounters begin today with a low-altitude flyby – about 1,000 kilometers from the surface – of Ganymede during Juno’s 34th orbit around the giant planet. Among other things, these steps will serve to reduce the orbital period of the probe from about 53 days to 43 days.
Of all the objects in the Solar System, Ganymede is certainly one of the most interesting. It is the largest object without an atmosphere, the largest of all known satellites of the planets, the one with the lowest moment of inertia, and the only one known to possess an intrinsic magnetic field, which in turn is immersed in the most large magnetic field of Jupiter.
“Italy and the Italian Space Agency are once again at the forefront in the exploration of our solar system”, adds Giuseppe Sindoni , ASI project manager for Jiram: “Such accurate measurements and such high spatial resolution will help us to reveal the mysteries of Jupiter and its satellites ».
Alessandro Mura , head of Jiram for Inaf, notes that “Jiram data will finally be able to reveal how the surface of Ganymede interacts with the external environment, and will be invaluable for planning future observations such as those of the Juice mission currently scheduled for launch in the next year”. Finally, in two months, Juno will again observe Ganymede from a greater distance, and Jiram, thanks to its ability to acquire high resolution images, will have an additional observation window to complete those started today.
Juno will study these characteristics using his tools. The plasma instruments will investigate how charged particles of the Jovian environment circulate and precipitate around the moon, creating a kind of peculiar auroras. The magnetometer will make us understand how the magnetic fields of Ganymede and Jupiter “communicate” with each other. The radiometer will investigate the properties beneath the surface of Ganymede. Finally, the cameras, including the Italian infrared imaging spectrometer Jiram, will provide us with very high resolution images and spectra (up to a few hundred meters) of the moon’s surface.
Featured image: An image of Ganymede taken in 2019 by the Jiram instrument aboard Juno showing the north pole area and part of the illuminated face of the Jovian moon. The grid indicating the position of the parallels and meridians of the celestial body has been artificially superimposed on it. The thickest line indicates the zero meridian, the others are plotted every 30 ° of longitude. The parallels, on the other hand, have a spacing of 10 °. Credits: Nasa / Jpl / Jiram team
A new study of over 3000 people led by King’s College London in collaboration with Lund University, has shown for the first time that a single biomarker can accurately indicate the presence of underlying neurodegeneration in people with cognitive issues.
A new study of over 3000 people led by King’s College London in collaboration with Lund University, has shown for the first time that a single biomarker can accurately indicate the presence of underlying neurodegeneration in people with cognitive issues.
Levels of a protein called neurofilament light chain (NfL) in the blood can identify those who might have neurodegenerative diseases such as Down’s syndrome dementia, motor neuron disease (ALS) and frontotemporal dementia, when clinical symptoms are not definitive.
Published in Nature Communications and part-funded by the NIHR Maudsley Biomedical Research Centre, the research determined a set of age-related cut-off levels of NfL which could inform its potential use in primary care settings through a simple blood test.
Joint Senior Author on the study, Dr Abdul Hye from the NIHR Maudsley Biomedical Research Centre at King’s College London and South London and Maudsley NHS Foundation Trust said: ‘For the first time we have shown across a number of disorders that a single biomarker can indicate the presence of underlying neurodegeneration with excellent accuracy. Though it is not specific for any one disorder, it could help in services such as memory clinics as a rapid screening tool to identify whether memory, thinking or psychiatric problems are a result of neurodegeneration.’
Neurodegenerative diseases are debilitating conditions that result in ongoing degeneration or death of nerve cells, leading to problems in thought, attention and memory. There are currently around 850,000 people with dementia in the UK which is projected to rise to 1.6 million by 2040. In order to help identify the onset of these debilitating diseases and put in place preventative measures as early as possible there has been a drive to develop reliable and accessible biomarkers that can recognise or rule out whether the processes in the brain that are responsible for neurodegeneration are occurring.
Current biomarkers used to identify neurodegenerative disorders are taken from the fluid that surrounds the brain and spinal column (cerebrospinal fluid – CSF) which has to be extracted using an invasive procedure called lumbar puncture. Advances have been made to use biomarkers from the blood which would provide a more accessible and comfortable assessment. A central and irreversible feature in many neurodegenerative disorders is damage to the nerve fibre which results in the release of neurofilament light chain (NfL). Using ultrasensitive tests, NfL can be detected in blood at low levels and is increased in a number of disorders, unlike phosphorylated tau which is specific for Alzheimer’s disease. This means NfL can be of use in the diagnostic process of many neurodegenerative diseases most notably in this study Down’s syndrome dementia, ALS and frontotemporal dementia.
‘For neurodegenerative diseases like Alzheimer’s, Parkinson’s or motor neuron disease, a blood test to allow early diagnosis and help us monitor disease progression and response to treatment would be very helpful. Neurofilament light chain is a promising biomarker that could speed diagnosis of neurodegenerative diseases and shorten clinical trials.’
The study examined 3138 samples from King’s College London, Lund University and Alzheimer’s Disease Neuroimaging Initiative, including people with no cognitive impairment, people with neurodegenerative disorders, people with Down syndrome and people with depression. The study showed that concentrations of NfL in the blood were higher across all neurodegenerative disorders compared to those with no cognitive problems, the highest being in people with Down’s syndrome dementia, motor neuron disease and frontotemporal dementia.
The study also showed that although blood based NfL could not differentiate between all the disorders, it could provide insight into different groups within certain disorders. For example, in those with Parkinson’s a high concentration of NfL indicated atypical Parkinson’s disorder and in patients with Down syndrome, NfL levels differentiated between those with and without dementia.
Co-author Andre Strydom, Professor in Intellectual Disabilities at King’s College London said: ‘This study shows that neurofilament light chain levels were particularly increased in adults with Down syndrome who have a genetic predisposition for Alzheimer’s disease. Furthermore, we showed that those individuals with a dementia diagnosis following onset of Alzheimer’s disease had higher levels than those who did not. This suggests that the new marker could potentially be used to improve the diagnosis of Alzheimer’s in people with Down syndrome, as well as to be used as biomarker to show whether treatments are effective or not. It is exciting that all that could be needed is a simple blood test, which is better tolerated in Down syndrome individuals than brain scans.’
The study assessed age-related thresholds or cut-offs of NfL concentrations that could represent the point at which an individual would receive a diagnosis. These age-related cut-off points were 90% accurate in highlighting neurodegeneration in those over 65 years of age and 100% accurate in detecting motor neurone disease and Down syndrome dementia in the King’s College London samples, with a very similar result in the Lund samples. Importantly, NfL was able to distinguish individuals with depression from individuals with neurodegenerative disorders which commonly present with primary psychiatric disorder in the onset of disease development such as frontotemporal dementia.
Joint-Senior author Professor Oskar Hansson from Lund University said ‘Blood tests have great potential to improve the diagnosis of dementia both in specialised memory clinics and in primary care. Plasma NfL can be extremely useful in a number of clinical scenarios which can greatly inform doctors, as shown in this large study’.
Dr Hye said ‘Blood-based NfL offers a scalable and widely accessible alternative to invasive and expensive tests for dementia. It is already used as a routine assessment in some European countries such as Sweden or Netherlands, and our age-related cut-offs can provide a benchmark and quick accessible test for clinicians, to indicate neurodegeneration in people who are exhibiting problems in thinking and memory.’
Lead author Dr Nicholas Ashton from King’s College London concludes ‘We are entering an exciting period where blood tests like plasma NfL, in combination with other emerging blood biomarkers like phosphorylated tau (p-tau), are starting to give us a meaningful and non-invasive insight into brain disorders’.
‘A multicentre validation study of the diagnostic value of plasma neurofilament light’ Ashton et al is published in Nature Communications 7th June 2021 doi 10.1038/s41467-021-23620-z and will be available on this link on publication https://www.nature.com/articles/s41467-021-23620-z
New research identified a novel interaction between the SARS-CoV-2 spike protein and the galectin-3-binding protein (LGALS3BP) which could be a new therapeutic anti-viral target. The research also found the presence of detectable viral RNA in blood in COVID-19 patients is a strong predictor of mortality.
The paper, published today in Nature Communications, was led by a group of researchers from King’s, Guy’s and St Thomas’ NHS Foundation Trust and King’s British Heart Foundation Centre. The research was funded by the NIHR Guy’s and St Thomas’ Biomedical Research Centre and supported by grants from BHF.
In the study, authors analysed close to 500 blood samples from patients admitted to Guy’s and St Thomas’ and King’s College Hospitals. The authors compared plasma and serum samples between patients admitted to intensive care units (ICU) with COVID-19 and hospitalised non-ICU COVID-19 patients and non-COVID-19 patients in ICU.
Almost a quarter of COVID-19 ICU patients had detectable RNAemia – severe acute respiratory syndrome coronavirus 2 RNA – within the first six days of admission to ICU. The presence of RNAemia was a strong predictor of 28-day mortality. RNAemia was detectable in 56% of deceased patients but in only 13% of survivors.
Researchers also identified LGALS3BP as a binding protein to the SARS-CoV-2 spike protein. Rising levels of LGALS3BP in the lungs offered protection to cells from the harmful effects of the SARS-CoV-2 spike protein.
The identification of LGALS3BP as a potential antiviral protein is encouraging as the UK government launched an Antivirals Taskforce in April 2021 to find effective treatments that could prevent future waves of infections and limit the effect of new variants.
“We report that presence of detectable viral RNA in plasma or serum of COVID-19 patients is associated with increased risk of severe illness. We also highlight a novel interaction with potential antiviral effect between the SARS-CoV-2 spike protein and a protein called galectin-3-binding protein.”
– Professor Manu Shankar Hari, a NIHR Clinician Scientist from the School of Immunology & Microbial Sciences
He added: “Our research findings have two main implications. First, there is an unmet diagnostic technology need for near patient tests to identify presence of viral RNA in blood in COVID-19 patients. Second, our research potentially highlights an antiviral drug target, which is a priority area highlighted within the UK government’s launch of a COVID-19 antivirals Taskforce.”
Professor Manuel Mayr, British Heart Foundation Professor at King’s College London, said: “As British Heart Foundation Professor I am delighted that we could join forces with our clinical colleagues to contribute to a better understanding of COVID-19. This is the first time blood proteins with the ability to bind to the SARS-CoV-2 spike protein have been analysed thanks to the specialised equipment available in King’s British Heart Foundation Centre.”
Reference: Gutmann, C., Takov, K., Burnap, S.A. et al. SARS-CoV-2 RNAemia and proteomic trajectories inform prognostication in COVID-19 patients admitted to intensive care. Nat Commun 12, 3406 (2021). https://doi.org/10.1038/s41467-021-23494-1
Amore reliable way of estimating the size of megalodon shows the extinct shark may have been bigger than previously thought, measuring up to 65 feet, nearly the length of two school buses. Earlier studies had ball-parked the massive predator at about 50 to 60 feet long.
The revised estimate is the result of new equations based on the width of megalodon’s teeth – and began with a high school lesson that went awry.
Victor Perez, then a doctoral student at the Florida Museum of Natural History, was guiding students through a math exercise that used 3D-printed replicas of fossil teeth from a real megalodon and a set of commonly used equations based on tooth height to estimate the shark’s size. But something was off: Students’ calculations ranged from about 40 to 148 feet for the same shark. Perez snapped into trouble-shooting mode.
“I was going around, checking, like, did you use the wrong equation? Did you forget to convert your units?” said Perez, the study’s lead author and now the assistant curator of paleontology at the Calvert Marine Museum in Maryland. “But it very quickly became clear that it was not the students that had made the error. It was simply that the equations were not as accurate as we had predicted.”
Although the equations have been widely used by scientists since their publication in 2002, the classroom exercise revealed they generate varying size estimates for a single shark, depending on which tooth is measured.
“I was really surprised,” Perez said. “I think a lot of people had seen that study and blindly accepted the equations.”
For more than a century, scientists have attempted to calculate the size of megalodon, whose name means “big tooth.” But the only known remains of the fearsome shark that dominated oceans from about 23 to 3.6 million years ago are fossilized teeth and a few, rare vertebrae. Like other sharks, the rest of megalodon’s skeleton, including its jaw, was composed of lightweight cartilage that decomposed quickly after death. Tooth enamel, however, “preserves really well,” Perez said. “It’s probably the most structurally stable thing in living organisms.” Megalodon sharks shed thousands of teeth over a lifetime, leaving abundant traces of the species in the fossil record.
The most accepted methods for estimating the length of megalodon have used great white sharks as a modern proxy, relying on the relationship between tooth size to total body length. While great white sharks and megalodon belong to different families, they share similar predatory lifestyles and broad, triangular teeth serrated like steak knives – ideal adaptations for hunting large, fleshy marine mammals such as whales and dolphins, Perez said.
But these methods also present a challenge: To generate body length estimates, they require the researcher to correctly identify a fossil tooth’s former position in a megalodon jaw. As in humans, the size and shape of shark teeth vary depending on where they’re located in the mouth, and megalodon teeth are most often found as standalone fossils.
So, Perez was ecstatic when fossil collector Gordon Hubbell donated a nearly complete set of teeth from the same megalodon shark to the Florida Museum in 2015, reducing the guesswork. After museum researchers CT scanned the teeth and made them available online, Perez collaborated with teacher Megan Higbee Hendrickson on a plan to incorporate them into her middle school curriculum at the Academy of the Holy Names school in Tampa.
“We decided to have the kids 3D-print the teeth, determine the size of the shark and build a replica of its jaw for our art show,” Hendrickson said.
Perez and Hendrickson co-designed a lesson for students based on the then-most popular method for estimating shark size: Match the tooth to its position in the shark jaw, look up the corresponding equation, measure the tooth from the tip of the crown to the line where root and crown meet and plug the number into the equation.
After a successful pilot test of a few teeth with Hendrickson’s students, he expanded the lesson plan to include the whole set of megalodon teeth for high school students at Delta Charter High School in Aptos, California. Perez expected a slight variability of a couple millimeters in their results, but this time, variations in students’ estimates shot to more than 100 feet. The farther a tooth position was from the front of the jaw, the larger the size estimate.
After Perez detailed the lesson’s results in a fossil community newsletter, he received an email from Teddy Badaut, an avocational paleontologist in France. Badaut suggested a different approach. Why not measure tooth width instead of height? Previous research had suggested tooth width was limited by the size of a shark’s jaw, which would be proportional to its body length.
Ronny Maik Leder, then a postdoctoral researcher at the Florida Museum, worked with Perez to develop a new set of equations based on tooth width.
By measuring the set of teeth from Hubbell, “we could actually sum up the width of the teeth and get an even better approximation of the jaw width,” Perez said.
The researchers analyzed sets of fossil teeth from 11 individual sharks, representing five species, including megalodon, its close relatives and modern great white sharks.
By measuring the combined width of each tooth in a row, they developed a model for how wide an individual tooth was in relation to the jaw for a given species. Now when a paleontologist unearths a lone megalodon tooth the size of their hand, they can compare its width to the average obtained in the study and get an accurate estimate of how big the shark was.
“I was quite surprised that indeed no one had thought of this before,” said Leder, now director of the Natural History Museum in Leipzig, Germany. “The simple beauty of this method must have been too obvious to be seen. Our model was much more stable than previous approaches. This collaboration was a wonderful example of why working with amateur and hobby paleontologists is so important.”
Perez cautioned that because individual sharks vary in size, the team’s methods still have a range of error of about 10 feet when applied to the largest individuals. It’s also unclear exactly how wide megalodon’s jaw was and difficult to guess based on teeth alone – some shark species have gaps between each tooth while the teeth in other species overlap.
“Even though this potentially advances our understanding, we haven’t really settled the question of how big megalodon was. There’s still more that could be done, but that would probably require finding a complete skeleton at this point,” he said.
“Since then, we’ve used the lesson to talk about the nature of science – the fact that we don’t know everything. There are still unanswered questions,” he said.
For Hendrickson, the lesson sparked her students’ enthusiasm for science in ways that textbooks could not.
“Victor was an amazing role model for the kids. He is the personification of a young scientist that followed his childhood interest and made a career out of it. So many of these kids had never worked with or spoken to a scientist who respected their point of view and was willing to answer their questions.”
The research was published in the open-access journal Palaeontologia Electronica.
Leder and Badaut co-authored the study.
The research was based on work supported by the Florida Education Fund McKnight Doctoral Fellowship, the National Science Foundation Graduate Research Fellowship program and the NSF Advancing Informal STEM Learning program.
Early-phase clinical trials show that a vaccine called KCONVAC is safe and stimulates antibody production in Chinese adults
The COVID-19 pandemic continues to disrupt and end lives around the world, and public health officials worldwide have recognized vaccines as the critical tools required for controlling the COVID-19 death toll and achieving a return to normal life. Several vaccines against COVID-19 are already in use, but the limited supplies of these vaccines and the possibility of safety and efficacy issues of the existing vaccines mean that it is important for scientists to develop more (and even better) vaccines. In fact, as of February 2021, 69 different vaccines are in various phases of clinical development.
One type of vaccine that could prove quite useful is the inactivated vaccine, which contains an inactivated form of the virus. The inactivated virus cannot harm the recipient, but it still serves to trigger an immune response that causes the recipient’s immune system to produce antibodies that can later fight off the real virus if need be. Inactivated vaccines have been in use for decades and have several advantages, including a well-documented safety record, well-developed manufacturing processes, and the capacity to present multiple viral proteins for recognition by the immune system. So far, Chinese authorities have issued conditional approval to three different inactivated vaccines for use in controlling the COVID-19 pandemic.
One inactivated vaccine currently in development is the KCONVAC vaccine developed by the Shenzhen Kangtai Biological Products Company and the Beijing Minhai Biotechnology Company. The KCONVAC vaccine is evaluated in ongoing phase 1 and phase 2 clinical trials, which aim to generate preliminary evidence of safety and preliminary evidence of efficacy, respectively. In a paper recently published in Chinese Medical Journal, a team of researchers led by Dr. Wen-Jie Tan of the Chinese Center for Disease Control and Prevention, Dr. Wei-Jin Huang of the China National Institutes for Food and Drug Control, and Dr. Feng-Cai Zhu of the Jiangsu Provincial Center for Disease Control and Prevention explore the existing clinical evidence for KCONVAC’s safety and ability to generate an immune response in healthy adults.
The phase 1 trial included 60 healthy Chinese adults, and the phase 2 trial included 500 healthy Chinese adults. In each trial, the participants were randomly assigned to groups that received 5 micrograms of the vaccine, 10 micrograms of the vaccine, or a placebo injection. The phase 2 trial participants received two separate injections administered either two or four weeks apart. Importantly, each trial was double-blind, meaning that neither the participants nor the clinical personnel they interacted with knew which group a participant had been assigned to. This “double-blinding,” a common procedure in clinical trials, served to increase the likelihood that any treatment effects would be due to the treatment administered rather than the participants’ expectations about what they would experience. “From the phase 1 and 2 trials, we wanted to know how many participants would experience adverse events within 28 days of the injections, and how effective the vaccine would be at inducing the production of antibodies against the novel coronavirus, respectively,” reports Dr. Tan.
In the phase 1 trial, participants who received the vaccine were no more likely to experience adverse events than participants who received the placebo injections were. The same pattern emerged in the phase 2 trial, and no severe vaccine-related adverse events occurred. In the phase 2 trial, KCONVAC successfully induced antibody production, and antibody production was stronger in participants who received their injections four weeks apart than in those who received their injections two weeks apart.
What’s more, as Dr. Huang notes, “these findings show that KCONVAC, both at a 5-microgram dose and a 10-microgram dose, is well tolerated and able to induce robust immune responses in adults and support the testing 5-microgram vaccine doses spaced four weeks apart in an upcoming phase 3 trial.”
“With this upcoming phase 3 trial, we hope to provide solid evidence that KCONVAC is safe and capable of reducing a recipient’s likelihood of developing COVID-19,” states Dr. Zhu. If the phase 3 trial returns positive results, then KCONVAC may become a valuable new tool in the fight to end the COVID-19 pandemic.
International research team uncovers underappreciated metal’s role in lowering blood pressure
High blood pressure, or hypertension, is the leading modifiable risk factor for cardiovascular diseases and premature death worldwide. And key to treating patients with conditions ranging from chest pain to stroke is understanding the intricacies of how the cells around arteries and other blood vessels work to control blood pressure. While the importance of metals like potassium and calcium in this process are known, a new discovery about a critical and underappreciated role of another metal – zinc – offers a potential new pathway for therapies to treat hypertension.
All the body’s functions depend on arteries channeling oxygen-rich blood – energy – to where it’s needed, and smooth muscle cells within these vessels direct how fast or slow the blood gets to each destination. As smooth muscles contract, they narrow the artery and increase the blood pressure, and as the muscle relaxes, the artery expands and blood pressure falls. If the blood pressure is too low the blood flow will not be enough to sustain a person’s body with oxygen and nutrients. If the blood pressure is too high, the blood vessels risk being damaged or even ruptured.
“Fundamental discoveries going back more than 60 years have established that the levels of the calcium and potassium in the muscle surrounding blood vessels control how they expand and contract,” say lead author Ashenafi Betrie, Ph.D., and senior authors Scott Ayton, Ph.D., and Christine Wright, Ph.D., of the Florey Institute of Neuroscience and Mental Health and The University of Melbourne in Australia.
Specifically, the researchers explain, potassium regulates calcium in the muscle, and calcium is known to be responsible for causing the narrowing of the arteries and veins that elevate blood pressure and restrict blood flow. Other cells that surround the blood vessel, including endothelial cells and sensory nerves, also regulate the calcium and potassium within the muscle of the artery, and are themselves regulated by the levels of these metals contained within them.
“Our discovery that zinc is also important was serendipitous because we’d been researching the brain, not blood pressure,” says Betrie. “We were investigating the impact of zinc-based drugs on brain function in Alzheimer’s disease when we noticed a pronounced and unexpected decrease in blood pressure in mouse models treated with the drugs.”
In collaboration with researchers at the University of Vermont’s Larner College of Medicine in the United States and TEDA International Cardiovascular Hospital in China, the investigators learned that coordinated action by zinc within sensory nerves, endothelial cells and the muscle of arteries triggers lower calcium levels in the muscle of the blood vessel. This makes the vessel relax, decreasing blood pressure and increasing blood flow. The scientists found that blood vessels in the brain and the heart were more sensitive to zinc than blood vessels in other areas of the body – an observation that warrants further research.
“Essentially, zinc has the opposite effect to calcium on blood flow and pressure,” says Ayton. “Zinc is an important metal ion in biology and, given that calcium and potassium are famous for controlling blood flow and pressure, it’s surprising that the role of zinc hasn’t previously been appreciated.”
Another surprising fact is that genes that control zinc levels within cells are known to be associated with cardiovascular diseases including hypertension, and hypertension is also a known side effect of zinc deficiency. This new research provides explanations for these previously known associations.
“While there are a range of existing drugs that are available to lower blood pressure, many people develop resistance to them,” says Wright, who added that a number of cardiovascular diseases, including pulmonary hypertension, are poorly treated by currently available therapies. “New zinc-based blood pressure drugs would be a huge outcome for an accidental discovery, reminding us that in research, it isn’t just about looking for something specific, but also about just looking.”
This press release has been adapted from an article featured by Pursuit and written by Ashenafi Betrie and Scott Ayton from the Florey Institute of Neuroscience and Mental Health, and Christine Wright of The University of Melbourne.
The aurora borealis, or northern lights, that fill the sky in high-latitude regions have fascinated people for thousands of years. But how they’re created, while theorized, had not been conclusively proven.
In a new study, a team of physicists led by University of Iowa reports definitive evidence that the most brilliant auroras are produced by powerful electromagnetic waves during geomagnetic storms. The phenomena, known as Alfven waves, accelerate electrons toward Earth, causing the particles to produce the familiar atmospheric light show.
The study, published online June 7 in the journal Nature Communications, concludes a decades-long quest to demonstrate experimentally the physical mechanisms for the acceleration of electrons by Alfven waves under conditions corresponding to Earth’s auroral magnetosphere.
“Measurements revealed this small population of electrons undergoes ‘resonant acceleration’ by the Alfven wave’s electric field, similar to a surfer catching a wave and being continually accelerated as the surfer moves along with the wave,” says Greg Howes, associate professor in the Department of Physics and Astronomy at Iowa and study co-author.
Scientists have known that energized particles that emanate from the sun—such as electrons racing at approximately 45 million miles per hour—precipitate along the Earth’s magnetic field lines into the upper atmosphere, where they collide with oxygen and nitrogen molecules, kicking them into an excited state. These excited molecules relax by emitting light, producing the colorful hues of the aurora.
The theory was supported by spacecraft missions that frequently found Alfven waves traveling Earthward above auroras, presumably accelerating electrons along the way. Although space-based measurements had supported the theory, limitations inherent to spacecraft and rocket measurements had prevented a definitive test.
The physicists were able to find confirmatory evidence in a series of experiments conducted at the Large Plasma Device (LPD) in UCLA’s Basic Plasma Science Facility, a national collaborative research facility supported jointly by the U.S. Department of Energy and National Science Foundation.
“The idea that these waves can energize the electrons that create the aurora goes back more than four decades, but this is the first time we’ve been able to confirm definitively that it works,” says Craig Kletzing, professor in the Department of Physics and Astronomy at Iowa and a study co-author. “These experiments let us make the key measurements that show that the space measurements and theory do, indeed, explain a major way in which the aurora are created.”
The phenomenon of electrons “surfing” on the electric field of a wave is a theoretical process known as Landau damping, first proposed by Russian physicist Lev Landau in 1946. Through numerical simulations and mathematical modeling, the researchers demonstrated that the results of their experiment agreed with the predicted signature for Landau damping.
The agreement of experiment, simulation, and modeling provides the first direct evidence that Alfven waves can produce accelerated electrons, causing the aurora, says Troy Carter, professor of physics at UCLA and director of the UCLA Plasma Science and Technology Institute.
“This challenging experiment required a measurement of the very small population of electrons moving down the LPD chamber at nearly the same speed as the Alfven waves, numbering less than one in a thousand of the electrons in the plasma,” Carter says.
James Schroeder, assistant professor of physics at Wheaton College and the study’s corresponding author, earned a doctorate at Iowa. Frederick Skiff, professor in the UI Department of Physics and Astronomy, is a study co-author. Stephen Vincena, a research physicist at UCLA, and Seth Dorfman, with the Space Science Institute and a visiting researcher at UCLA, are contributing authors.
The U.S. National Science Foundation, the U.S. Department of Energy, and NASA funded the research.
Featured image: Physicists led by the University of Iowa report definitive evidence of how auroras are created. In experiments, the physicists demonstrated the physical mechanisms for the acceleration of electrons by Alfven waves under conditions corresponding to Earth’s auroral magnetosphere. Photo courtesy of NASA.
Analysis of dietary patterns for over 350,000 women suggests eating more anti-inflammatory foods helps lower risk
A new study of more than 350,000 women found that women with diets incorporating more foods that increase inflammation in the body had a 12% increase in their risk of breast cancer compared to women who consume more anti-inflammatory diets. The new findings are being presented at NUTRITION 2021 LIVE ONLINE.
The study authors found that moving from a more anti-inflammatory diet toward one that increases inflammation upped breast cancer risk in an almost linear manner. Foods that increase inflammation include red and processed meat; high-fat foods such as butter, margarines and frying fats; and sweets including sugar, honey and foods high in sugar. Fruits, vegetables, legumes, tea and coffee all have potentially anti-inflammatory properties.
“Most studies examining diet and breast cancer risk have focused on single nutrients or foods rather than the whole diet,” said the study’s first author Carlota Castro-Espin, a predoctoral fellow at the Catalan Institute of Oncology and Bellvitge Biomedical Research Institute in Barcelona, Spain. “People consume food not nutrients, thus examining overall dietary patterns, rather than single components of diets can lead to more accurate conclusions when analysing associations with a health outcome such as breast cancer.”
The new results are based on data from the European Investigation into Cancer and Nutrition (EPIC) study, a prospective study that recruited more than 500,000 participants across 10 European countries starting in the mid-1990s. The study included more than 13,000 breast cancer diagnoses during approximately 15 years of follow-up.
The typical diet for EPIC participants was measured for a year using food frequency or diet history questionnaires. The researchers used this information to calculate an inflammatory score for each study participant based on their intake of 27 foods.
The researchers examined dietary patterns linked with inflammation because long-term, low grade inflammation has been linked with the development of breast cancer. The large number of women in the study allowed the researchers to take a more nuanced look at the relationship between dietary patterns and breast cancer risk.
Their analysis showed that the increase in breast cancer risk due to pro-inflammatory diets appears to be more pronounced among premenopausal women. They also found that the association did not vary by breast cancer hormone receptor subtypes.
“Our results add more evidence of the role that dietary patterns play in the prevention of breast cancer,” said Castro-Espin. “With further confirmation, these findings could help inform dietary recommendations aimed at lowering cancer risk.”
As a next step, the researchers plan to evaluate the association of the inflammatory potential of diet and other dietary patterns with breast cancer survival using participants in the EPIC study.
Castro-Espin will present this research on-demand during NUTRITION 2021 LIVE ONLINE from noon on Monday, June 7 through 5:30 p.m. on Friday, June 10 (abstract; presentation details).
Study confirms unusual electron behavior in a quantum material
Researchers have discovered a new electronic property at the frontier between the thermal and quantum sciences in a specially engineered metal alloy – and in the process identified a promising material for future devices that could turn heat on and off with the application of a magnetic “switch.”
In this material, electrons, which have a mass in vacuum and in most other materials, move like massless photons or light – an unexpected behavior, but a phenomenon theoretically predicted to exist here. The alloy was engineered with the elements bismuth and antimony at precise ranges based on foundational theory.
Under the influence of an external magnetic field, the researchers found, these oddly behaving electrons manipulate heat in ways not seen under normal conditions. On both the hot and cold sides of the material, some of the electrons generate heat, or energy, while others absorb energy, effectively turning the material into an energy pump. The result: a 300% increase in its thermal conductivity.
Take the magnet away, and the mechanism is turned off.
“The generation and absorption form the anomaly,” said study senior author Joseph Heremans, professor of mechanical and aerospace engineering and Ohio Eminent Scholar in Nanotechnology at The Ohio State University. “The heat disappears and reappears elsewhere – it is like teleportation. It only happens under very specific circumstances predicted by quantum theory.”
This property, and the simplicity of controlling it with a magnet, makes the material a desirable candidate as a heat switch with no moving parts, similar to a transistor that switches electrical currents or a faucet that switches water, that could cool computers or increase the efficiency of solar-thermal power plants.
“Solid-state heat switches without moving parts are extremely desirable, but they don’t exist,” Heremans said. “This is one of the possible mechanisms that would lead to one.”
The bismuth-antimony alloy is among a class of quantum materials called Weyl semimetals – whose electrons don’t behave as expected. They are characterized by properties that include negatively and positively charged particles, electrons and holes, respectively, that behave as “massless” particles. Also part of a group called topological materials, their electrons react as if the material contains internal magnetic fields that enable the establishment of new pathways along which those particles move.
In physics, an anomaly – the electrons’ generation and absorption of heat discovered in this study – refers to certain symmetries that are present in the classical world but are broken in the quantum world, said study co-author Nandini Trivedi, professor of physics at Ohio State.
Bismuth alloys and other similar materials also feature classical conduction like most metals, by which vibrating atoms in a crystal lattice and the movement of electrons carry heat. Trivedi described the new pathway along which light-like electrons manipulate heat among themselves as a highway that seems to appear out of nowhere.
“Imagine if you were living in a small town that had tiny roads, and suddenly there’s a highway that opens up,” she said. “This particular pathway only opens up if you apply a thermal gradient in one direction and a magnetic field in the same direction. So you can easily close the highway by putting the magnetic field in a perpendicular direction.
“No such highways exist in ordinary metals.”
When a metal like copper is heated and electrons flow from the hot end to the cold end, both the heat and the charge move together. Because of the way this highway opens in the experimental Weyl semimetal material, there’s no net charge motion – only energy movement. The absorption of heat by certain electrons represents a break in chirality, or directionality, meaning that it’s possible to pump energy between two particles that wouldn’t be expected to interact – another characteristic of Weyl semimetals.
The theoretical physicists and engineers collaborating on this study predicted that these properties existed in specific bismuth alloys and other topological materials. For these experiments, the scientists constructed the specialized alloy to test their predictions.
“We worked hard to synthesize the correct material, which was designed from the ground up by us to show this effect. It was important to purify it way below the levels of impurities that you find in nature,” Heremans said. As composed, the alloy minimized background conduction so the researchers could detect the behavior of the massless electrons, known as Weyl Fermions.
“In ordinary materials, electrons drag around with them a small magnet. However, the peculiar electronic structure of these bismuth alloys means the electrons drag around a magnet almost 50 times bigger than normal,” said Michael Flatté, professor of physics and astronomy at the University of Iowa and a study co-author. “These huge subatomic magnets allowed the novel electronic state to be formed using laboratory magnetic fields.
“These results show that theories developed for high-energy physics and subatomic particle theories can often be realized in specially designed electronic materials.”
Like everything quantum, Heremans said, “what we observed looks a little like magic, but that is what our equations say it should do and that is what we proved experimentally that it does.”
One catch: The mechanism in this material works only at a low temperature, below minus 100 degrees Fahrenheit. With the fundamentals now understood, the researchers have lots of options as they work toward potential applications.
“Now we know what materials to look for and what purity we need,” Heremans said. “That is how we get from discovery of a physical phenomenon to an engineering material.”
Additional co-authors include Dung Vu and Wenjuan Zhang of Ohio State and Cüneyt Şahin of the University of Iowa. Flatté and Şahin were also affiliated with the University of Chicago at the time this work was done.
Featured image: The cones in this image illustrate the equations of motion of electrons when an external magnetic field is applied to the bismuth alloy engineered for the study. Green lines and purple lines represent electrons that generate and absorb energy, respectively.Illustration by Renee Ripley