It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Thursday, March 11, 2021
UH geologists discover powerful 'river of rocks' below Caribbean
Study finds flows in softer layer under tectonic plates are stronger, faster
Geologists have long thought tectonic plates move because they are pulled by the weight of their sinking portions and that an underlying, hot, softer layer called asthenosphere serves as a passive lubricant. But a team of geologists at the University of Houston has found that layer is actually flowing vigorously, moving fast enough to drive plate motions.
In their study published in Nature Communications, researchers from the UH College of Natural Sciences and Mathematics looked at minute changes in satellite-detected gravitational pull within the Caribbean and at mantle tomography images - similar to a CAT Scan - of the asthenosphere under the Caribbean. They found a hot "river of rocks" being squeezed from the Pacific Ocean through a gateway under Central America and reaching to the middle of the Caribbean Sea. This underground "river of rocks" started flowing eight million years ago, when the Central American gateway opened, uplifting the overlying seafloor by several hundred feet and tilting it to the northeast toward the Lesser Antilles.
"Without the extra support generated by this flow in the asthenosphere, portions of Central America would still be below sea level. The Atlantic and the Pacific Oceans would be connected without a need for the Panama Canal," said study co-author Lorenzo Colli, assistant professor of geophysics, geodynamics and mantle structure in the Department of Earth and Atmospheric Sciences.
The findings have implications for understanding the shape of the Earth's surface, of its evolution over time through the appearance and disappearance of shallows seas, low-lying land bridges and the forces that move tectonic plates and cause earthquakes.
Another fascinating discovery, according to the researchers, is the asthenosphere is moving six inches per year, which is three times faster than an average plate. It can move independently from the overlying plates and drag them in a different direction.
"This challenges the top-down notion that subduction is always the driver," explained Jonny Wu, study co-author and assistant professor of structural geology, tectonics and mantle structure. "Think of the plates moving like an air hockey puck and being lubricated from below. Instead, what we found is the air hockey table is imposing its own currents on the puck that's moving around, creating a bottom-up movement that has not been well recognized, and that's being quantified here."
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Other authors of the study include lead author and UH doctoral student Yi-Wei Chen; Dale Bird, UH research associate professor; and Hejun Zhu, assistant professor of geosciences at the University of Texas at Dallas.
Pandemic emphasizes need for digital literacy education
IMAGE: AN IOWA STATE UNIVERSITY RESEARCHER SAYS THE PANDEMIC HAS ACCELERATED THE NEED FOR DIGITAL LITERACY EDUCATION. view more
CREDIT: IOWA STATE UNIVERSITY
AMES, Iowa - Parents would never give their children the keys to the car without supervised training and driver's education. An Iowa State University researcher says parents and educators need to take a similar approach before handing children a keyboard to access the digital world.
ISU psychology professor Douglas Gentile worked with the DQ (Digital Intelligence) Institute, an international think tank, to design a framework for digital literacy education. In a commentary, published by the journal Nature Human Behaviour, Gentile and his colleagues outlined how the COVID-19 pandemic has accelerated the need to implement this global standard for digital literacy.
"Children are exposed to various risks online, and COVID increases the odds because now they're online more than ever," Gentile said. "If children haven't had the training to know what to look out for, they're perhaps subject to more risks."
Gentile and colleagues Joshua Jackman, assistant professor with Sungkyunkwan University in South Korea; Nam-Joon Cho, professor with Nanyang Technological University in Singapore; and Yuhyun Park, founder of the DQ Institute, examined the responses of more than 145,000 children and adolescents from 30 countries, finding that 60% were exposed to cyber risks such as cyberbullying, gaming disorder and violence. Gentile says the results show this is a universal problem that needs a global solution.
Despite extensive efforts to create digital skills programming, the researchers wrote that the impact has been limited because a common framework did not exist and there was weak coordination between programs. In response, the Institute of Electrical and Electronics Engineers (IEEE) Standards Association last fall approved the DQ framework as the standard for digital education. The DQ framework focuses on digital skills education across eight competencies, including identity, use, safety, security, emotional intelligence, literacy, communication and rights.
Gentile says approval of the framework is just a first step toward getting digital literacy education in K-12 classrooms. He says it is imperative that students have the tools to become savvy digital consumers, especially with the growing number of risks and misinformation online.
"If anyone can post information online, whether it's true or false, we need to give consumers the skills to detect it and guard against it," Gentile said. "Digital literacy will not eliminate the risks online, but it will develop good digital citizens who have the skills to work within the system so they can gain the benefits, without the harms that the risks might pose."
1 Billion Digital Skills Project
Gentile and his colleagues are calling on academic researchers, educators and others to join the efforts of the Coalition for Digital Intelligence (see sidebar for partners) to support the 1 Billion Digital Skills Project. As the name suggests, the project aims to equip one billion people, primarily K-12 students, teachers and parents, with digital skills within 10 years. The coalition is working to achieve the following objectives:
Build a global network to develop/implement digital skills education and training.
Develop a certification system to evaluate digital skills programs.
Develop microbadge credits students can earn to incentivize learning.
Create an online assessment platform to measure digital skills.
Support ongoing improvement of DQ standards and evaluation of educational programs.
Gentile says achieving these objectives will require state and federal investment to train K-12 teachers and provide programming in schools. The return on the investment is twofold, he said. The training will not only protect children from online risks, but help prepare the future workforce.
"More and more jobs include an online component," Gentile said. "If we train people to be good digital citizens, we'd likely have fewer breaches in corporate America. There is a financial incentive to put resources into our schools to provide this training."
Coalition for Digital Intelligence
The Coalition for Digital Intelligence is working to implement the digital intelligence framework across the technology and education sectors, making sure that both work together toward universal digital intelligence. Coalition partners include:
DQ Institute
Organisation for Economic Cooperation and Development (OECD)
IEEE Standards Association
World Economic Forum
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After cracking the "sum of cubes" puzzle for 42, researchers discover a new solution for 3
The 21-digit solution to the decades-old problem suggests many more solutions exist.
What do you do after solving the answer to life, the universe, and everything? If you're mathematicians Drew Sutherland and Andy Booker, you go for the harder problem.
In 2019, Booker, at the University of Bristol, and Sutherland, principal research scientist at MIT, were the first to find the answer to 42. The number has pop culture significance as the fictional answer to "the ultimate question of life, the universe, and everything," as Douglas Adams famously penned in his novel "The Hitchhiker's Guide to the Galaxy." The question that begets 42, at least in the novel, is frustratingly, hilariously unknown.
In mathematics, entirely by coincidence, there exists a polynomial equation for which the answer, 42, had similarly eluded mathematicians for decades. The equation x3+y3+z3=k is known as the sum of cubes problem. While seemingly straightforward, the equation becomes exponentially difficult to solve when framed as a "Diophantine equation" -- a problem that stipulates that, for any value of k, the values for x, y, and z must each be whole numbers.
When the sum of cubes equation is framed in this way, for certain values of k, the integer solutions for x, y, and z can grow to enormous numbers. The number space that mathematicians must search across for these numbers is larger still, requiring intricate and massive computations.
Over the years, mathematicians had managed through various means to solve the equation, either finding a solution or determining that a solution must not exist, for every value of k between 1 and 100 -- except for 42.
In September 2019, Booker and Sutherland, harnessing the combined power of half a million home computers around the world, for the first time found a solution to 42. The widely reported breakthrough spurred the team to tackle an even harder, and in some ways more universal problem: finding the next solution for 3.
Booker and Sutherland have now published the solutions for 42 and 3, along with several other numbers greater than 100, this week in the Proceedings of the National Academy of Sciences.
Picking up the gauntlet
The first two solutions for the equation x3+y3+z3 = 3 might be obvious to any high school algebra student, where x, y, and z can be either 1, 1, and 1, or 4, 4, and -5. Finding a third solution, however, has stumped expert number theorists for decades, and in 1953 the puzzle prompted pioneering mathematician Louis Mordell to ask the question: Is it even possible to know whether other solutions for 3 exist?
"This was sort of like Mordell throwing down the gauntlet," says Sutherland. "The interest in solving this question is not so much for the particular solution, but to better understand how hard these equations are to solve. It's a benchmark against which we can measure ourselves."
As decades went by with no new solutions for 3, many began to believe there were none to be found. But soon after finding the answer to 42, Booker and Sutherland's method, in a surprisingly short time, turned up the next solution for 3:
The discovery was a direct answer to Mordell's question: Yes, it is possible to find the next solution to 3, and what's more, here is that solution. And perhaps more universally, the solution, involving gigantic, 21-digit numbers that were not possible to sift out until now, suggests that there are more solutions out there, for 3, and other values of k.
"There had been some serious doubt in the mathematical and computational communities, because [Mordell's question] is very hard to test," Sutherland says. "The numbers get so big so fast. You're never going to find more than the first few solutions. But what I can say is, having found this one solution, I'm convinced there are infinitely many more out there."
A solution's twist
To find the solutions for both 42 and 3, the team started with an existing algorithm, or a twisting of the sum of cubes equation into a form they believed would be more manageable to solve:
k ? z3 = x3 + y3 = (x + y)(x2 ? xy + y2)
This approach was first proposed by mathematician Roger Heath-Brown, who conjectured that there should be infinitely many solutions for every suitable k. The team further modified the algorithm by representing x+y as a single parameter, d. They then reduced the equation by dividing both sides by d and keeping only the remainder -- an operation in mathematics termed "modulo d" -- leaving a simplified representation of the problem.
"You can now think of k as a cube root of z, modulo d," Sutherland explains. "So imagine working in a system of arithmetic where you only care about the remainder modulo d, and we're trying to compute a cube root of k."
With this sleeker version of the equation, the researchers would only need to look for values of d and z that would guarantee finding the ultimate solutions to x, y, and z, for k=3. But still, the space of numbers that they would have to search through would be infinitely large.
So, the researchers optimized the algorithm by using mathematical "sieving" techniques to dramatically cut down the space of possible solutions for d.
"This involves some fairly advanced number theory, using the structure of what we know about number fields to avoid looking in places we don't need to look," Sutherland says.
A global task
The team also developed ways to efficiently split the algorithm's search into hundreds of thousands of parallel processing streams. If the algorithm were run on just one computer, it would have taken hundreds of years to find a solution to k=3. By dividing the job into millions of smaller tasks, each independently run on a separate computer, the team could further speed up their search.
In September 2019, the researchers put their plan in play through Charity Engine, a project that can be downloaded as a free app by any personal computer, and which is designed to harness any spare home computing power to collectively solve hard mathematical problems. At the time, Charity Engine's grid comprised over 400,000 computers around the world, and Booker and Sutherland were able to run their algorithm on the network as a test of Charity Engine's new software platform.
"For each computer in the network, they are told, 'your job is to look for d's whose prime factor falls within this range, subject to some other conditions,'" Sutherland says. "And we had to figure out how to divide the job up into roughly 4 million tasks that would each take about three hours for a computer to complete."
Very quickly, the global grid returned the very first solution to k=42, and just two weeks later, the researchers confirmed they had found the third solution for k=3 -- a milestone that they marked, in part, by printing the equation on t-shirts.
The fact that a third solution to k=3 exists suggests that Heath-Brown's original conjecture was right and that there are infinitely more solutions beyond this newest one. Heath-Brown also predicts the space between solutions will grow exponentially, along with their searches. For instance, rather than the third solution's 21-digit values, the fourth solution for x, y, and z will likely involve numbers with a mind-boggling 28 digits.
"The amount of work you have to do for each new solution grows by a factor of more than 10 million, so the next solution for 3 will need 10 million times 400,000 computers to find, and there's no guarantee that's even enough," Sutherland says. "I don't know if we'll ever know the fourth solution. But I do believe it's out there."
This research was supported, in part, by the Simons Foundation.
As far back as the Greek historian Herodotus, a group of people called the Scythians were considered highly mobile warrior nomads.
Scythian-era people lived across Eurasia from about 700 BCE to 200 BCE, and have long been considered highly mobile warriors who ranged widely across the steppe grasslands. Herodotus describes Scythian populations as living in wagons and engaging in raiding and warfare, and this view has persisted throughout history--supported by archeologists' observations of similar styles of horse harnesses, weapons, burial mounds and animal style motifs throughout what is now Ukraine.
Because of this, history has lumped the diverse cultures and periods of people in this region as a single "Scythian" identity, even calling it an "empire." But a study including University of Michigan research reveals what previously was considered one group was likely a set of diverse peoples with varied diets.
By analyzing human bone and tooth enamel, the international team of researchers found that, rather than being wide-ranging warriors, people in this region more likely lived in urban locales, growing millet and raising livestock in mixed economic systems. The team's results are published in the journal PLOS ONE.
"Our study demonstrates overall low levels of human mobility in the vicinity of key urban locales of the Scythian era, in contrast to previous stereotypes of highly nomadic populations," said Alicia Ventresca Miller, lead author of the study and U-M assistant professor of anthropology. "While long-distance mobility increased during the Scythian era relative to preceding periods, it was limited to a small percentage of individuals."
Ventresca Miller, formerly of the Max Planck Institute for the Science of Human History, and her team took samples of bone and tooth enamel from 56 human skeletons at three burial sites--Bel'sk, Mamai-Gora and Medvin--in modern-day Ukraine. The team examined these samples using isotope analysis. This kind of analysis examines isotopes of elements--in this study, strontium, oxygen, nitrogen and carbon--deposited in human tissues through eating and drinking. This allows researchers to determine where an individual traveled and lived based on the unique isotope composition in their tissue.
Together, these analyses showed that urban locales were places of social and economic diversity where people farmed millet and raised livestock. These findings suggest people largely stayed where they farmed and raised livestock--though they did tend to move around more than previous eras.
"The Scythian epoch was clearly a period of contradictions, with strong evidence for complex interactions between agro-pastoralists and pastoralists that contributed to population aggregation in urban locales," said Ventresca Miller, who is also assistant curator of Asian archeology at the U-M Museum of Anthropological Archaeology. "This study highlights the potential use of using isotopic analysis to directly assess prevailing models of economies and mobilities during the Scythian era."
In the future, researchers hope to provide further insights into how people moved between site types, such as urban centers versus rural settings, as well as between individuals with different grave goods and apparent social status.
"In this way, we can move further away from assumed stereotypes of migration and nomadism toward dynamic and complex insights into globalized Scythian societies," Ventresca Miller said.
IMAGE: TROPICAL FORESTS IN PANAMA ARE THREATENED DUE TO AGRICULTURE, MINING, DEVELOPMENT, AND CLIMATE CHANGE. REFORESTATION IS AN IMPORTANT STRATEGY TO PROTECT THE TROPICAL CARBON SINK. NITROGEN-FIXING TREES ARE KNOWN TO... view more
CREDIT: CREDIT: SARAH BATTERMAN.
A new study, published this week in Proceedings of the National Academy of Sciences, reveals that nitrogen-fixing trees play an underrecognized role in recovering tropical forests by enriching nutrient-poor soils with scarce elements such as phosphorus and molybdenum.
Coauthor Sarah Batterman, a tropical forest ecologist at Cary Institute of Ecosystem Studies, explains, "We've long known that nitrogen-fixing trees work with soil microbes to make atmospheric nitrogen available to plants. Our study found that nitrogen fixers also play a vital role in unlocking other nutrients by weathering rocks beneath their roots. These nutrients include things like phosphorus, which is very limited in tropical forest soils and important to plant growth."
In this study, the team compared the soils of nitrogen-fixing and non-fixing trees across young recovering tropical forest plots that are part of the Agua Salud Secondary Forest Dynamics Network in the Panama Canal Area. They measured soil pH and mineral weathering - a process that releases nutrients trapped in rocks. They also assessed the composition of the soil microbial community.
To measure weathering, they buried 504 mesh bags of rocks (crushed dunite) under trees, and measured nutrient weathering from the rocks over eight months. Dunite was chosen because it weathers at a rate comparable to minerals in local soils. Trees sampled included five species of nitrogen fixers (51 trees), five species of non-fixers situated in a legume-rich area (39 trees), and five species of non-fixers situated far from any legumes (36 trees).
Batterman explains, "Mineral weathering under nitrogen fixers happened twice as fast as weathering under non-fixers. The soil under nitrogen fixers was far more acidic than the soil under non-fixers. This increased acidity promotes weathering and the release of chemical elements locked in minerals as they break down."
The team also discovered that soils beneath nitrogen fixers were teeming with a bacterial genus new to science (Candidatus Acidoferrum) that thrives in the acidic conditions created by nitrogen-fixing trees. These bacteria are highly enriched under nitrogen fixers, where they enable phosphorus release by breaking down iron-bearing minerals.
Two important products of weathering include available phosphorus and molybdenum. Phosphorus boosts plant growth, and molybdenum helps plants assimilate nitrogen. Before weathering, these scarce but critical elements are trapped in the aluminum and iron found in Panamanian soils. The acidic conditions found beneath the roots of nitrogen fixers catalyze the weathering needed to release phosphorus and molybdenum in bioavailable forms that plants can use.
Co-author Kristin Saltonstall of Smithsonian Tropical Research Institute explains, "Together, acidic soil conditions and a distinct community of bacteria enhance nitrogen fixers' ability to weather rocks and access nutrients. Benefits aren't limited to fixers themselves. We also found that nitrogen fixers help fertilize other plants throughout the forest, with broad effects on nutrient cycling in the forest community."
Lead author Dimitar Epihov of the University of Sheffield points out, "Tree diversity has long been recognized as vital for successful forest recovery. Current views dictate that nitrogen-fixing trees supply nitrogen to help speed up the recovery process. Our work expands these views by revealing that these trees also modulate the microbiome of soils belowground, enabling the release of other non-nitrogen nutrients from rocks. Benefits can be passed on to neighboring trees, and aid in the productivity of regrowing forests in the tropics."
Batterman notes, "Nitrogen-fixing trees have presented ecologists with a longstanding paradox. They are abundant in tropical forests, but so is nitrogen in the soil. Why are they so common, if access to nitrogen does not typically limit growth? Our findings offer an answer to this puzzle. Regardless of whether they are actively fixing, nitrogen fixers also have a unique ability to unlock phosphorus, which is very limited."
Tropical forests are responsible for 70% of the global forest carbon sink, yet they are under threat due to mining, logging, agriculture, development, and climate change. Understanding how different tree species influence tropical forests is essential to informing science-based reforestation strategies.
Batterman concludes, "Tropical soils tend to be nutrient-poor, which can slow forest recovery. Including nitrogen-fixing species in reforestation projects could helping neighboring trees obtain more nutrients, grow quicker, and ultimately help protect the tropical carbon sink."
Nitrogen fixation by bacteria occurs in root nodules of nitrogen-fixing trees. This nitrogen fixer, a member of the genus Inga, is growing in a recovering tropical forest in Panama. Trees with the ability to fix nitrogen also are able to access rock-derived nutrients like phosphorus by partnering with unique microbial communities in soil beneath their roots.
CREDIT
Credit: Sarah Batterman.
Investigators
Dimitar Z. Epihov - Department of Animal and Plant Sciences, University of Sheffield; Leverhulme Centre for Climate Change Mitigation, University of Sheffield
Kristin Saltonstall - Smithsonian Tropical Research Institute, Balboa, Ancón, Panamá
Sarah A. Batterman - Smithsonian Tropical Research Institute, Balboa, Ancón, Panamá; School of Geography and Priestley International Centre for Climate, University of Leeds; Cary Institute of Ecosystem Studies
Lars O. Hedin - Department of Ecology and Evolutionary Biology, Princeton University
Jefferson S. Hall - ForestGEO, Smithsonian Tropical Research Institute, Balboa, Ancón, Panamá
Michiel van Breugel - ForestGEO, Smithsonian Tropical Research Institute, Balboa, Ancón, Panamá; Yale-NUS College, Singapore; Department of Biological Sciences, National University of Singapore
Jonathan R. Leake - Department of Animal and Plant Sciences, University of Sheffield; Leverhulme Centre for Climate Change Mitigation, University of Sheffield
David J. Beerling - Department of Animal and Plant Sciences, University of Sheffield; Leverhulme Centre for Climate Change Mitigation, University of Sheffield
Acknowledgements
Funding for this research was made possible in part by the Leverhulme Research Centre, the Princeton University Carbon Mitigation Initiative, the Natural Environment Research Council, the British Council, the Leverhulme Trust, and the European Research Council.
This work is a contribution of the Agua Salud Project, a collaboration between the Smithsonian Tropical Research Institute, the Panama Canal Authority, and the Ministry of the Environment of Panama. The Agua Salud Secondary Forest Dynamics network is supported by HSBC, Stanley Motta, Small World Institute Fund, the Hoch family, and the National Science Foundation. Agua Salud is part of the Smithsonian Institution Forest Global Earth Observatory.
Cary Institute of Ecosystem Studies is an independent nonprofit center for environmental research. Since 1983, our scientists have been investigating the complex interactions that govern the natural world and the impacts of climate change on these systems. Our findings lead to more effective management and policy actions and increased environmental literacy. Staff are global experts in the ecology of: cities, disease, forests, and freshwater.
Bioaccumulation of phased-out fire retardants is slowly declining in bald eagles
IMAGE: EIGHT-WEEK-OLD BALD EAGLE NESTLING IN ITS NEST OVERLOOKING LAKE SUPERIOR FROM APOSTLE ISLANDS NATIONAL LAKESHORE. THE STUDY TARGETED 5 TO 8-WEEK-OLD NESTLINGS BECAUSE THEY CAN THERMOREGULATE AT THAT AGE... view more
CREDIT: JIM CAMPBELL-SPICKLER
Research published in Environmental Toxicology and Chemistry shows that the presence of polybrominated diphenyl ethers (PBDEs) in bald eagle populations is slowly declining. Bald eagles are apex predators that nest and, more importantly, feed along water bodies, making them excellent bioindicators of environmental contaminants that bioaccumulate up the aquatic food web. The findings are both good news for eagles and instructive for regulators tasked with managing surface water quality by setting protective levels for wildlife, as well as fish consumption advisories for humans.
Lead author Bill Route from the National Park Service Great Lakes Inventory and Monitoring Network, explained, "Bald eagles are similar to humans in that both are tertiary predators in aquatic systems. The patterns we observed in nestlings may be indicative of those in humans who consume fish from the same water bodies."
Introduced in the 1970s, PBDEs were designed as flame retardants and come in three primary formulations: penta-BDE, used primarily in furniture and cars; octa-BDE, used mainly in the electronics industry; and deca-BDE, used in a variety of appliances. Penta- and octa-BDE were phased out of use in the early 2000s and banned internationally in 2009 under the Stockholm Convention. Deca-BDEs were reduced and ultimately eliminated from manufacturing by 2013. Despite the regulations, PBDEs are still present in many products and continue to find their way into the environment. These chemical compounds are hydrophobic, which means they do not dissolve in water; instead, they stick to particles and settle at the bottom of rivers and lakes, where they are ingested by animals. Since they don't easily dissolve in water, they tend to sequester and accumulate in fatty tissue and subsequently get passed up the food chain.
CAPTION
Eight-week-old bald eagle nestling. At this age nestlings have the dark plumage of adults and can use their beaks and feet to fend off unwary biologists. Proper handlings skills are required to safely capture and sample these nestlings.
CREDIT
Jim Campbell-Spickler
Route and his co-authors assessed patterns and trends in PBDE concentrations in 492 bald eagle nestlings' blood samples from 241 territories across 12 study areas in Minnesota and Wisconsin. This work built upon previous studies in the same region, which enabled the authors to reveal trends. Perhaps unsurprisingly, the highest levels of PBDEs were found in urban areas, such as Minneapolis-St. Paul, and the lowest concentrations were in sparsely populated areas. However, overall, the research shows a sustained 3.8% annual rate of decline in the concentrations of five primary PBDEs in the samples collected across the region since PBDE production was reduced.
A monumental particle accelerator in the Cygnus Cocoon
THE HENRYK NIEWODNICZANSKI INSTITUTE OF NUCLEAR PHYSICS POLISH ACADEMY OF SCIENCES
IMAGE: THE CYGNUS COCOON REGION WITH THE SOURCE OF PHOTONS UP TO 100 TEV, COINCIDING WITH THE YOUNG CYGNUS OB2 CLUSTER OF MASSIVE STARS. (SOURCE: IFJ PAN / HAWC) view more
CREDIT: SOURCE: IFJ PAN / HAWC
At the heart of Cygnus, one of the most beautiful constellations of the summer sky, beats a source of high-energy cosmic ray particles: the Cygnus Cocoon. An international group of scientists at the HAWC observatory has gathered evidence that this vast astronomical structure is the most powerful of our galaxy's natural particle accelerators known of up to now.
This spectacular discovery is the result of the work of scientists from the international High-Altitude Water Cherenkov (HAWC) gamma-ray observatory. Located on the slopes of the Mexican Sierra Negra volcano, the observatory records high-energy particles and photons flowing from the abyss of space. In the sky of the Northern Hemisphere, their brightest source is the region known as the Cygnus Cocoon. At the HAWC, it was established that photons with energies even several dozen times greater than those recorded earlier by the Fermi-LAT and ARGO detectors arrive from the Cocoon. This fact suggests that the Cygnus Cocoon is the most powerful of the hitherto known particle accelerators in the Milky Way. The results of the research, in which scientists from the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow played an important role, are presented in the prestigious journal Nature Astronomy.
"The discovery made thanks to the HAWC observatory is an important element of a scientific puzzle that has been going on for over a hundred years, the aim of which is to decipher the nature of cosmic rays, especially when speaking of particles with the highest energies occurring in our galaxy," says Dr. Sabrina Casanova (IFJ PAN), initiator of the latest data analysis from the Cygnus Cocoon region and its significant co-author.
The Cygnus Cocoon, a vast astronomical structure about 180 light years across, lies 4.6 thousand light years from the Sun. In our sky, we can find it almost exactly in the centre of the Cygnus constellation where it occupies an area of angular width similar to the four discs of the Moon. It is a region of intense formation of massive (and consequently short-lived) stars, with two young star clusters Cygnus OB2 and NGC 6910.
"The HAWC detector has greater sensitivity and angular resolution than previous devices of this type. With its use, during 1,343 days of observation we recorded photons of gamma rays with energies up to one hundred teraelectronvolts, coming from the direction of the Cygnus OB2 cluster. What could have been the source of such high-energy radiation?" wonders Dr. Casanova.
What emerges from the latest analysis of gamma radiation reaching the Earth from the Cygnus Cocoon is an interesting picture of phenomena of complex, multi-stage nature. High-energy cosmic rays are usually expected to come from supernova remnants, including pulsars. However, in supernova remnants protons or electrons do not have enough time to accelerate to a kinetic energy reaching several hundred teraelectronvolts. But then, inside a young cluster of massive stars, the turbulences of powerful stellar winds interacting with each other help to confine the particles for millions of years. Some of these particles have the chance to gain energies reaching petaelectronvolts.
"The situation is very complicated," notes Dr. Casanova, and clarifies: "Some particles are expected to gain really enormous energies inside these associations of massive stars thanks to the long confinement time, comparable to the million-year lifetime of the associations themselves. But the higher the energy of the particles, the shorter the confinement time. We expect that the highest energy particles escape the cluster before they emit the gamma photons we can observe. The question is: where is the maximum acceleration energy?"
The key question is the nature of the particles responsible for the emission of the high-energy photons that were recorded at the HAWC observatory. If the source of the photons were electrons, their energies would have to be several times greater than the energy of photons. However, if the source were protons, their energies would have to be as high as a petaelectronvolt. This value is one hundred times greater than the energy of proton collisions inside the LHC accelerator.
"Our analysis does not provide a clear conclusion regarding the origin of photons with energies reaching 100 TeV. It does, however, point to a clear favourite - protons with extreme energies, accelerated in collisions of stellar winds and then emitting gamma photons when colliding with interstellar material," says Dr Casanova.
If future observations confirm the present interpretation, the Cygnus OB2 star cluster in the interior of the Cygnus Cocoon would be the most powerful of all our galaxy's accelerators identified so far.
The Henryk Niewodniczanski Institute of Nuclear Physics (IFJ PAN) is currently one of the largest research institutes of the Polish Academy of Sciences. A wide range of research carried out at IFJ PAN covers basic and applied studies, from particle physics and astrophysics, through hadron physics, high-, medium-, and low-energy nuclear physics, condensed matter physics (including materials engineering), to various applications of nuclear physics in interdisciplinary research, covering medical physics, dosimetry, radiation and environmental biology, environmental protection, and other related disciplines. The average yearly publication output of IFJ PAN includes over 600 scientific papers in high-impact international journals. Each year the Institute hosts about 20 international and national scientific conferences. One of the most important facilities of the Institute is the Cyclotron Centre Bronowice (CCB), which is an infrastructure unique in Central Europe, serving as a clinical and research centre in the field of medical and nuclear physics. In addition, IFJ PAN runs four accredited research and measurement laboratories. IFJ PAN is a member of the Marian Smoluchowski Kraków Research Consortium: "Matter-Energy-Future", which in the years 2012-2017 enjoyed the status of the Leading National Research Centre (KNOW) in physics. In 2017, the European Commission granted the Institute the HR Excellence in Research award. The Institute holds A+ Category (the highest scientific category in Poland) in the field of sciences and engineering.
CAPTION
The High-Altitude Water Cherenkov (HAWC) gamma-ray observatory, located on the slopes of the Mexican Sierra Negra volcano. (Source: HAWC Observatory)
Dr. Sabrina Casanova Institute of Nuclear Physics, Polish Academy of Sciences tel: +48 12 6628274 email: sabrina.casanova@ifj.edu.pl
SCIENTIFIC PUBLICATIONS:
"HAWC observations of the acceleration of very-high energy cosmic rays in the Cygnus Cocoon" The HAWC Collaboration Nature Astronomy, 2021 DOI: https://doi.org/10.1038/s41550-021-01318-y
LINKS:
http://www.ifj.edu.pl/ The website of the Institute of Nuclear Physics, Polish Academy of Sciences.
http://press.ifj.edu.pl/ Press releases of the Institute of Nuclear Physics, Polish Academy of Sciences.
IMAGES:
IFJ210311b_fot01s.jpg HR: http://press.ifj.edu.pl/news/2021/03/11/IFJ210311b_fot01.jpg The Cygnus Cocoon region with the source of photons up to 100 TeV, coinciding with the young Cygnus OB2 cluster of massive stars. (Source: IFJ PAN / HAWC)
IFJ210311b_fot02s.jpg HR: http://press.ifj.edu.pl/news/2021/03/11/IFJ210311b_fot02.jpg Cygnus X, one of the brightest and closest star forming region in the Galaxy (marked in red), is at the centre of the Cygnus Cocoon, a vast astronomical structure that covers an area of Earth's sky an angular width of four lunar discs. (Source: IFJ PAN / Stellarium)
IMAGE: ARMY-FUNDED RESEARCH SENDS ENTANGLED QUBIT STATES THROUGH A COMMUNICATION CABLE LINKING ONE QUANTUM NETWORK NODE TO A SECOND NODE. THIS RESEARCH COULD HELP LAY NEW GROUNDWORK FOR FUTURE QUANTUM COMMUNICATION... view more
CREDIT: NANCY WONG, UNIVERSITY OF CHICAGO
RESEARCH TRIANGLE PARK, N.C. -- New Army-funded research could help lay the groundwork for future quantum communication networks and large-scale quantum computers.
Researchers sent entangled qubit states through a communication cable linking one quantum network node to a second node.
Scientists at the Pritzker School of Molecular Engineering at the University of Chicago, funded and managed by the U.S. Army Combat Capability Development, known as DEVCOM, Army Research Laboratory's Center for Distributed Quantum Information, also amplified an entangled state via the same cable first by using the cable to entangle two qubits in each of two nodes, then entangling these qubits further with other qubits in the nodes. The peer-reviewed journal published the research in its Feb. 24, 2021, issue.
"The entanglement distribution results the team achieved brought together years of their research related to approaches for transferring quantum states and related to advanced fabrication procedures to realize the experiments," said Dr. Sara Gamble, program manager at the Army Research Office, an element of the Army's corporate research laboratory, and co-manager of the CDQI, which funded the work. "This is an exciting achievement and one that paves the way for increasingly complex experiments with additional quantum nodes that we'll need for the large-scale quantum networks and computers of ultimate interest to the Army."
Qubits, or quantum bits, are the basic units of quantum information. By exploiting their quantum properties, like superposition, and their ability to be entangled together, scientists and engineers are creating next-generation quantum computers that will be able solve previously unsolvable problems.
The research team uses superconducting qubits, tiny cryogenic circuits that can be manipulated electrically.
"Developing methods that allow us to transfer entangled states will be essential to scaling quantum computing," said Prof. Andrew Cleland, the John A. MacLean senior professor of Molecular Engineering Innovation and Enterprise at University of Chicago, who led the research.
Entanglement is a correlation that can be created between quantum entities such as qubits. When two qubits are entangled and a measurement is made on one, it will affect the outcome of a measurement made on the other, even if that second qubit is physically far away.
Entanglement is a correlation that can be created between quantum entities such as qubits. When two qubits are entangled and a measurement is made on one, it will affect the outcome of a measurement made on the other, even if that second qubit is physically far away.
To send the entangled states through the communication cable--a one-meter-long superconducting cable--the researchers created an experimental set-up with three superconducting qubits in each of two nodes. They connected one qubit in each node to the cable and then sent quantum states, in the form of microwave photons, through the cable with minimal loss of information. The fragile nature of quantum states makes this process quite challenging.
The researchers developed a system in which the whole transfer process--node to cable to node--takes only a few tens of nanoseconds (a nanosecond is one billionth of a second). That allowed them to send entangled quantum states with very little information loss.
The system also allowed them to amplify the entanglement of qubits. The researchers used one qubit in each node and entangled them together by essentially sending a half-photon through the cable. They then extended this entanglement to the other qubits in each node. When they were finished, all six qubits in two nodes were entangled in a single globally entangled state.
"We want to show that superconducting qubits have a viable role going forward," Cleland said.
A quantum communication network could potentially take advantage of this advance. The group plans to extend their system to three nodes to build three-way entanglement.
The researchers developed a system in which the whole transfer process--node to cable to node--takes only a few tens of nanoseconds (a nanosecond is one billionth of a second).
"The team was able to identify a primary limiting factor in this current experiment related to loss in some of the components," said Dr. Fredrik Fatemi, branch chief for quantum sciences, DEVCOM ARL, and co-manager of CDQI. "They have a clear path forward for increasingly complex experiments which will enable us to explore new regimes in distributed entanglement."
