New tool for analyzing large superconducting circuits

The next generation of computing and information processing lies in the intriguing world of quantum mechanics. Quantum computers are expected to be capable of solving large, extremely complex problems that are beyond the capacity of today’s most powerful supercomputers.

New research tools are needed to advance the field and fully develop quantum computers. Now Northwestern University researchers have developed and tested a theoretical tool for analyzing large superconducting circuits. These circuits use superconducting quantum bits, or qubits, the smallest units of a quantum computer, to store information.

Circuit size is important since protection from detrimental noise tends to come at the cost of increased circuit complexity. Currently there are few tools that tackle the modeling of large circuits, making the Northwestern method an important contribution to the research community.

“Our framework is inspired by methods originally developed for the study of electrons in crystals and allows us to obtain quantitative predictions for circuits that were previously hard or impossible to access,” said Daniel Weiss, corresponding and first author of the paper. He is a fourth-year graduate student in the research group of Jens Koch, an expert in superconducting qubits.

Koch, an associate professor of physics and astronomy in Weinberg College of Arts and Sciences, is a member of the Superconducting Quantum Materials and Systems Center (SQMS) and the Co-design Center for Quantum Advantage (C2QA). Both national centers were established last year by the U.S. Department of Energy (DOE). SQMS is focused on building and deploying a beyond-state-of-the-art quantum computer based on superconducting technologies. C2QA is building the fundamental tools necessary to create scalable, distributed and fault-tolerant quantum computer systems.

“We are excited to contribute to the missions pursued by these two DOE centers and to add to Northwestern’s visibility in the field of quantum information science,” Koch said. 

In their study, the Northwestern researchers illustrate the use of their theoretical tool by extracting from a protected circuit quantitative information that was unobtainable using standard techniques. 

Details were published in the open access journal Physical Review Research.

The researchers specifically studied protected qubits. These qubits are protected from detrimental noise by design and could yield coherence times (how long quantum information is retained) that are much longer than current state-of-the-art qubits.  

These superconducting circuits are necessarily large, and the Northwestern tool is a means for quantifying the behavior of these circuits. There are some existing tools that can analyze large superconducting circuits, but each works well only when certain conditions are met. The Northwestern method is complementary and works well when these other tools may give suboptimal results.

The research was supported by the Army Research Office (Contract No. W911NF-17-C-0024).

Source/Credit: Northwestern University/Megan Fellman

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Fountain of youth for ageing stem cells in bone marrow

Stained calcium (dark brown) in stem cells from the bone marrow: 

Young stem cells (left) produce more material for bone than old stem cells (center). 

They can be rejuvenated by adding sodium acetate (right).

Credit/Source: Pouikli/Max Planck Institute for Biology of Ageing

As we age, our bones become thinner, we suffer fractures more often, and bone-diseases such as osteoporosis are more likely to occur. One responsible mechanism involves the impaired function of the bone-marrow stem cells, which are required for the maintenance of bone integrity. Researchers from the Max Planck Institute for Biology of Ageing and CECAD Cluster of Excellence for Ageing Research at the University of Cologne have now shown that the reduced stem cell function upon ageing is due to changes in their epigenome. They were able to reverse these changes in isolated stem cells by adding acetate. This fountain of youth for the epigenome could become important for the treatment of diseases such as osteoporosis.

Ageing Researchers have been looking at epigenetics as a cause of ageing processes for some time. Epigenetics looks at changes in genetic information and chromosomes that do not alter the sequence of the genes themselves, but do affect their activity. One possibility is changes in proteins called histones, which package the DNA in our cells and thus control access to DNA. The Cologne research group of Peter Tessarz has now studied the epigenome of mesenchymal stem cells. These stem cells are found in bone marrow and can give rise to different types of cells such as cartilage, bone and fat cells.

The epigenetic changes of ageing stem cells

"We wanted to know why these stem cells produce less material for the development and maintenance of bones as we age, causing more and more fat to accumulate in the bone marrow. To do this, we compared the epigenome of stem cells from young and old mice," explains Andromachi Pouikli, first author of the study. "We could see that the epigenome changes significantly with age. Genes that are important for bone production are particularly affected."

Rejuvenation of the epigenome

The researchers then investigated whether the epigenome of stem cells could be rejuvenated. To do this, they treated isolated stem cells from mouse bone marrow with a nutrient solution which contained sodium acetate. The cell converts the acetate into a building block that enzymes can attach to histones to increase access to genes, thereby boosting their activity. "This treatment impressively caused the epigenome to rejuvenate, improving stem cell activity and leading to higher production of bone cells," Pouikli said.

To clarify whether this change in the epigenome could also be the cause of the increased risk in old age for bone fractures or osteoporosis in humans, the researchers studied human mesenchymal stem cells from patients after hip surgery. The cells from elderly patients who also suffered from osteoporosis showed the same epigenetic changes as previously observed in the mice.

A new therapeutic approach against osteoporosis?

"Sodium acetate is also available as a food additive, however, it is not advisable to use it in this form against osteoporosis, as our observed effect is very specific to certain cells. However, there are already first experiences with stem cell therapies for osteoporosis. Such a treatment with acetate could also work in such a case. However, we still need to investigate in more detail the effects on the whole organism in order to exclude possible risks and side effects," explains Peter Tessarz, who led the study.

Source/Credit: Max-Planck-Gesellschaft

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Engineers grow pancreatic organoids

 

MIT and Cancer Research UK Manchester Institute researchers have
developed a synthetic gel that can be used to grow tiny
pancreatic organoids, seen here, from human pancreatic cells.
Credits: Courtesy of the researchers.

MIT engineers, in collaboration with scientists at Cancer Research UK Manchester Institute, have developed a new way to grow tiny replicas of the pancreas, using either healthy or cancerous pancreatic cells. Their new models could help researchers develop and test potential drugs for pancreatic cancer, which is currently one of the most difficult types of cancer to treat.

Using a specialized gel that mimics the extracellular environment surrounding the pancreas, the researchers were able to grow pancreatic “organoids,” allowing them to study the important interactions between pancreatic tumors and their environment. Unlike some of the gels now used to grow tissue, the new MIT gel is completely synthetic, easy to assemble and can be produced with a consistent composition every time.

“The issue of reproducibility is a major one,” says Linda Griffith, the School of Engineering Professor of Teaching Innovation and a professor of biological engineering and mechanical engineering. “The research community has been looking for ways to do more methodical cultures of these kinds of organoids, and especially to control the microenvironment.”

The researchers have also shown that their new gel can be used to grow other types of tissue, including intestinal and endometrial tissue.

Griffith and Claus Jorgensen, a group leader at the Cancer Research UK Manchester Institute, are the senior authors of the paper, which appears today in Nature Materials. The lead author is Christopher Below, a former graduate student at the Cancer Research UK Manchester Institute.

Mimicking the microenvironment

The researchers were also able to use their system to grow
supportive cells such as fibroblasts (green) and macrophages (orange)
surrounding the pancreatic organoids.
Credits: Joanna Kelly and Christopher Below

Traditionally, labs have used commercially available tissue-derived gel to grow organoids in a lab dish. However, as the most widely used commercial gel is a complex mixture of proteins, proteoglycans, and growth factors derived from a tumor grown in mice, it is variable from lot to lot and has undesirable components present, Griffith says. It also doesn’t always allow for growth of multiple types of cells. About 10 years ago, Griffith’s lab started to work on designing a synthetic gel that could be used to grow epithelial cells, which form the sheets that line most organs, along with other supportive cells.

The gel they developed is based on polyethylene glycol (PEG), a polymer that is often used for medical applications because it doesn’t interact with living cells. By studying the biochemical and biophysical properties of the extracellular matrix, which surrounds organs in the body, the researchers were able to identify features they could incorporate into the PEG gel to help cells grow in it.

One key feature is the presence of molecules called peptide ligands, which interact with cell surface proteins called integrins. The sticky binding between ligands and integrins allows cells to adhere to the gel and form organoids. The researchers found that incorporating small synthetic peptides derived from fibronectin and collagen in their gels allowed them to grow a variety of epithelial tissues, including intestinal tissue. They showed that supportive cells called stromal cells, along with immune cells, can also thrive in this environment.

In the new study, Griffith and Jorgensen wanted to see if the gel could also be used to support the growth of normal pancreatic organoids and pancreatic tumors. Traditionally, it has been difficult to grow pancreatic tissue in a manner that replicates both the cancerous cells and the supporting environment, because once pancreatic tumor cells are removed from the body, they lose their distinctive cancerous traits.

Griffith’s lab developed a protocol to produce the new gel, and then teamed up with Jorgensen’s lab, which studies the biology of pancreatic cancer, to test it. Jorgensen and his students were able to produce the gel and use it to grow pancreatic organoids, using healthy or cancerous pancreatic cells derived from mice.

“We got the protocol from Linda and we got the reagents in, and then it just worked,” Jorgensen says. “I think that speaks volumes of how robust the system is and how easy it is to implement in the lab.”

Other approaches they had tried were too complicated or did not recapitulate the microenvironment seen in living tissues, he says. Using this gel, Jorgensen’s lab was able to compare the pancreatic organoids to tissues they have studied in living mice, and they found that the tumor organoids express many of the same integrins seen in pancreatic tumors. Furthermore, other types of cells that normally surround tumors, including macrophages (a type of immune cells) and fibroblasts (a type of supportive cells), were also able to grow in the microenvironment.

Patient-derived cells

The researchers also showed that they can use their gel to grow organoids from pancreatic cancer cells from patients. They believe it could also be useful for studying lung, colorectal, and other cancers. Such systems could be used to analyze how potential cancer drugs affect tumors and their microenvironment.

“The discoveries described in this paper will facilitate further important questions concerning responses to novel drug treatment approaches,” says Hilary Critchley, a professor of reproductive medicine and co-deputy director of the MRC Centre for Reproductive Health at the University of Edinburgh, who was not involved in the study. “The cancer field has long relied upon other approaches (mouse models or isolated cell studies), and the contribution of the organoid approach, and notably the gel structure in which these mini groups of cells grow, will be pivotal to research advancement.”

Griffith also plans to use the gel to grow and study tissue from patients with endometriosis, a condition that causes the tissue that lines the uterus to grow outside the uterus. This can lead to pain and sometimes infertility.

One of the advantages of the new gel is that it is completely synthetic, and can be made easily in a lab by mixing together specific precursors, including PEG and some polypeptides. The researchers have filed a patent on the technology and are in the process of licensing it to a company that could produce the gel commercially.

The research was funded by Cancer Research UK, the Rosetrees Trust, a European Research Council Consolidator Award, the National Science Foundation, the National Institutes of Health, and the Defense Advanced Research Projects Agency.

Source/Credit: Massachusetts Institute of Technology

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Researchers Create Materials for Shape-Shifting Architecture

 

Source/Credit: North Carolina State University

Researchers at North Carolina State University have developed materials that can be used to create structures capable of transforming into multiple different architectures. The researchers envision applications ranging from construction to robotics.

“The system we’ve developed was inspired by metamorphosis,” says Jie Yin, corresponding author of a paper on the work and an associate professor of mechanical and aerospace engineering at NC State. “With metamorphosis in nature, animals change their fundamental shape. We’ve created a class of materials that can be used to create structures that change their fundamental architecture.”

Kirigami is a fundamental concept for Yin’s work. Kirigami is a variation of origami that involves cutting and folding paper. But while kirigami traditionally uses two-dimensional materials, Yin applies the same principles to three-dimensional materials.

The metamorphosis system starts with a single unit of 3D kirigami. Each unit can form multiple shapes in itself. But these units are also modular – they can be connected to form increasingly complex structures. Because the individual units themselves can form multiple shapes, and can connect to other units in multiple ways, the overall system is capable of forming a wide variety of architectures.

“Think of what you can build with conventional materials,” Yin says. “Now imagine what you can build when each basic building block is capable of transforming in multiple ways.”

Yin’s lab previously demonstrated a similar concept, in which 3D kirigami units were stacked on each other. In that system, the units could be used to assemble a structure – but the structure could also then be disassembled.

The metamorphosis system involves actually connecting the kirigami units. In other words, once the units are connected to each other they cannot be disconnected. However, the larger structures they create are capable of transforming into multiple, different architectures.

“There are two big differences between our first kirigami system and the metamorphosis system,” Yin explains.

“The first kirigami system involved units that could be assembled into architectures and then disassembled, which is an advantage. However, when the units were assembled, the architecture wouldn’t be capable of transforming. Because the sides of the unit were not rigid and fixed at 90-degree angles, the assembled structure could bend and move – but it could not fundamentally change its geometry.

“The metamorphosis kirigami system does not allow you to disassemble a structure,” Yin says. “And because the sides of each cubic unit are rigid and fixed at 90-degree angles, the assembled structure does not bend or flex very much. However, the finished structure is capable of transforming into different architectures.”

In proof-of-concept testing, the researchers demonstrated that the metamorphosis system was capable of creating many different structures that are capable of bearing significant weight while maintaining their structural integrity.

That structural integrity is important, because Yin thinks construction is one potential application for the metamorphosis system.

“If you scale this approach up, it could be the basis for a new generation of construction materials that can be used to create rapidly deployable structures,” Yin says. “Think of the medical units that have had to be expanded on short notice during the pandemic, or the need for emergency housing shelters in the wake of a disaster.”

The researchers also think the metamorphosis system could be used to create a variety of robotic devices that can transform in order to respond to external stimuli or to perform different functions.

“We also think this system could be used to create a new line of toys – particularly toys that can help people explore some fundamental STEM concepts related to physics and engineering,” Yin says. “We’re open to working with industry collaborators to pursue these and other potential applications for the system.”

The paper, “Metamorphosis of three-dimensional kirigami-inspired reconfigurable and reprogrammable architected matter,” is published in the journal Materials Today Physics. First author of the paper is Yanbin Li, a Ph.D. student at NC State. The work was done with support from the National Science Foundation, under grant 2005374.

Source/Credit: North Carolina State University

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Crop-eating moths will flourish as climate warms

 

The top map shows the distribution of diamondback moths as of 2016. Overwintering regions are shown in red. The bottom map shows regions where the diamondback moth’s range has expanded in the past 50 years, based on a climate change model in which mean global temperatures will increase 2 degrees Celsius this century. Darker colors indicate a greater chance for overwinter survival.
(Image courtesy of V. Rudolf/Rice University)

Climate change in this century will allow one of the world’s costliest agricultural pests, the diamondback moth, to both thrive year-round and rapidly evolve resistance to pesticides in large parts of the United States, Europe and China where it previously died each winter, according to a study by U.S. and Chinese researchers.

The moth, Plutella xylostella, which is also known as the cabbage moth, already causes more than $4 billion in damage worldwide each year to broccoli, cauliflower, cabbage, kale, mustard, radishes, turnips, watercress, Brussels sprouts and other crops. It is also one the world’s most pesticide-resistant species, with a documented resistance to at least 97 insecticides.

In a first-of-its-kind study published in the open-access journal Nature Communications, researchers from Rice University and the Chinese Academy of Agricultural Sciences combined results from years of laboratory and field experiments, computer simulations of future climate warming scenarios and a meta-analysis of decades of prior moth research.

“It’s well-documented that climate change is shifting the distribution and ranges of species, but the challenge is trying to predict where species will go,” said study co-author Volker Rudolf, an ecologist, evolutionary biologist and professor of biosciences at Rice University.

Rudolf said the team, which was led by co-lead authors Chun-Sen Ma and Wei Zhang, began with laboratory experiments aimed at isolating a specific mechanism that could be used to accurately predict how the range of diamondback moths would evolve in response to climate change. Previous experiments had found the coldest temperature individual moths could survive, but it was also well-known the moths died out each winter in places where temperatures were considerably higher. Rudolf said the lab studies allowed the team to predict where the moths can “overwinter,” or survive year-round, based on the daily accumulated low temperatures below a critical threshold in winter, a metric they dubbed “low temperature degree days.”

“That variable alone predicts over 90% of mortality, which is pretty nuts,” Rudolf said. “You don’t normally get correlations that strong.”

That gave the researchers “a simple variable that was both mechanistically linked to the survival of the species and really easy to calculate from either past climate data or future-climate models,” he said.

Diamondback moth
(This work, “Plutella.xylostella.7383,” by of Olaf Leillinger
is used and provided under
CC BY SA 2.5 courtesy of Wikimedia Commons)

The researchers found climate change over the past 50 years has increased the overwintering range of the diamondback moth by more than 925,000 square miles. They also showed each increase in mean global temperature of 1 degree Celsius will allow the moth’s overwintering range to expand by about 850,000 square miles. Current climate models predict mean global temperatures will increase by 2-6 degrees Celsius during the coming 100-150 years, the study said.

Rudolf said the overwintering data combined with a meta-analysis of decades of previous studies of diamondback moth pesticide resistance allowed the team to show how climate change could dramatically worsen the problem of evolved pesticide resistance in parts of the U.S., China, Japan and the Mediterranean that are currently “marginal” overwintering regions for the moth.

“We care about overwintering because if they survive winters and stay year-round that allows for rapid evolution of pesticide resistance,” Rudolf said.

Diamondback moths and many other crop pests like armyworms, planthoppers, leafrollers and some species of aphids overwinter in warm regions and migrate annually, causing significant damage to crops in regions where they cannot overwinter. Where these species cannot overwinter, they are slower to evolve pesticide resistance, Rudolf said.

“Because they always come from somewhere else to recolonize a particular site, the individuals are most likely coming from different ancestors every year,” he said. “So, you can have within-season selection for pesticide resistance, but selection across-seasons gets interrupted.”

The researchers’ global meta-analysis of pesticide resistance in diamondback moths illustrated the critical difference between these two types of evolutionary processes: Mean pesticide resistance was 158 times higher at overwintering sites compared to non-overwintering sites, the research showed.

The double whammy of an expanded year-round range and more rapid evolution of pesticide resistance could severely impede control efforts and allow diamondback moths to cause greater economic losses for farmers, the study found.

But the study’s authors said the research also presents an opportunity, both as a template for studying similar crop pests and as a guide to designing and coordinating more effective control efforts.

The findings could be used to “develop proactive pest management in a changing world, reduce costs of control efforts and assure food security while minimizing impacts on natural enemies and other aspects of the ecosystem,” they wrote in the study. “In practice, our results emphasize the importance of adjusting pest management strategies to adapt to differences in winter survival across regions and how this will change under future climate scenarios.”

Study co-authors include Yu Peng, Liang Zhu and Gang Ma of the Chinese Academy of Agricultural Sciences in Beijing, Fei Zhao and Kun Xing of both the Chinese Academy of Agricultural Sciences and Shanxi Agricultural University in Shanxi, Xiang-Qian Chang of both the Chinese Academy of Agricultural Sciences and Hubei Academy of Agricultural Sciences in Wuhan, and He-Ping Yang of the National Meteorological Information Centre in Beijing.

The research was supported by the National Natural Science Foundation of China (31471764, 31620103914, 31501630), the National Key R&D Program of China (2018YFD0201400, 2019YFD1002100), the Chinese Academy of Agricultural Sciences’ Fundamental Research Fund (Y2017LM10) and the Chinese Academy of Agricultural Sciences’ Innovation Program (CAAS-ZDRW202012).

Source/Credit: Rice University

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Fat matters more than muscle for heart health, research finds

 

Photo by Polina Tankilevitch from Pexels

New research has found that changes in body fat impact early markers of heart health more than changes in body muscle, suggesting there are greater benefits to be expected from losing fat than from gaining muscle.

The observational study, led by researchers from the University of Bristol, was published in PLoS Medicine.

More than 3,200 young people in Bristol’s Children of the 90s birth cohort study were measured repeatedly for levels of body fat and lean mass using a body scanning device. These scans were performed four times across participants’ lives, when they were children, adolescents, and young adults (at ages 10, 13, 18 and 25 years). Handgrip strength was also tested when they were aged 12 and 25 years.

When the participants were 25 years old, blood samples were collected and a technique called “metabolomics” was used to measure over 200 detailed markers of metabolism including different types of harmful cholesterol, glucose, and inflammation, which together indicate one’s susceptibility to developing heart disease and other health conditions.

Dr Joshua Bell, senior research associate in epidemiology and lead author of the report, said: “We knew that fat gain is harmful for health, but we didn’t know whether gaining muscle could really improve health and help prevent heart disease. We wanted to put those benefits in context.”

The findings showed that gaining fat mass was strongly and consistently related to poorer metabolic health in young adulthood, as indicated, for example, by higher levels of harmful cholesterol. These effects were much larger (often about 5-times larger) than any beneficial effect of gaining muscle. Where there were benefits of gaining muscle, these were specific to gains that had occurred in adolescence – suggesting that this early stage of life is a key window for promoting muscle gain and reaping its benefits.

Dr Bell added: “Fat loss is difficult, but that does seem to be where the greatest health benefits lie. We need to double down on preventing fat gain and supporting people in losing fat and keeping it off.

“We absolutely still encourage exercise – there are many other health benefits and strength is a prize in itself. We may just need to temper expectations for what gaining muscle can really do for avoiding heart disease – fat gain is the real driver.”

The study also found that improving strength (based on handgrip) has slightly greater benefits for markers of heart health than gaining muscle itself, suggesting that the frequent use of muscle, rather than the bulking up of muscle, may matter more.

Professor Nic Timpson, the Principal Investigator of the Children of the 90s and one of the study’s authors, said: “This research provides greater clarity in the relative roles of fat and lean mass in the basis of cardio-metabolic disease. This is an important finding and clearly part of a complex picture of health that involves weight gain, but also the other indirect costs and benefits of different types of lifestyle. It is only through detailed, longitudinal, studies like Children of the 90s that these relationships can be uncovered. We extend our thanks to the participants of the Children of the 90s who make all of this work possible.”

Source/Credit: University of Bristol

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Mapping project completed, helping to save world’s reefs

 

Ailinginae Atoll - Ailinginae Atoll in the Marshall Islands.
Photo credit: Greg Asner

All of the world’s shallow coral reefs have been digitally mapped, thanks to a three-year project combining two million satellite images, enormous amounts of field data and University of Queensland-developed mapping techniques.

The Allen Coral Atlas project has officially launched its high-resolution maps of the world’s reefs which, together with the Atlas’s coral monitoring tool launched in May, will revolutionize reef management.

The project is an international research collaboration led by Arizona State University in partnership with UQ, Planet Ltd, National Geographic and Vulcan Inc.

UQ’s Remote Sensing Research Centre researcher Dr Chris Roelfsema said the digital atlas is a comprehensive and continually updated tool, perfect for scientists, policy makers and planners.

“To manage environmental assets like the world’s reefs, you need to know what’s happening at any given time,” Dr Roelfsema said.

“The Allen Coral Atlas provides maps that accurately describe the composition and extent of our reefs globally, and at a level of detail not seen before.

“These maps are connecting people with the data they need to save our reefs – it’s momentous.”

The Allen Coral Atlas, now available online, has been a global effort with UQ scientists playing the leading role in gathering verification data, developing and implementing the mapping approach for the world’s coral reefs.

“The verification and mapping approaches we’ve developed are based on 20 years of experience UQ has in combining reef knowledge, field data and earth observation processes to map and monitor coral reefs,” Dr Roelfsema said.

“This work combined 450 field data sets from global collaborators with machine learning and automated contextual-editing approaches, which helps us achieve the highest spatial and thematic resolution of coral reefs anyone has ever seen.”

The data is needed now more than ever, with models predicting 70 to 90 per cent of coral reefs will be lost by 2050, because of warming, polluted and acidic oceans.

Professor Greg Asner, Director of Arizona State University's Center for Global Discovery and Conservation Science and Managing Director of the Atlas project, said he was thrilled to announce the platform.

“It is a gratifying milestone after years of dedicated non-stop teamwork to bring this global map to fruition,” Dr Asner said.

“But the true value of the work will come when coral conservationists are able to better protect coral reefs based on the high-resolution maps and monitoring system.

“We must double down and use this tool as we work to save coral reefs from the impacts of our climate crisis and other threats.”

The Allen Coral Atlas is named for the late Microsoft co-founder Paul G. Allen, and founder of Vulcan Inc.

Source/Credit: University of Queensland

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Silicon, Subatomic Particles and Possible ‘Fifth Force’

 

As neutrons pass through a crystal, they create two different standing waves – one along atomic planes and one between them. The interaction of these waves affects the path of the neutron, revealing aspects of the crystal structure.  Credit: NIST

Using a groundbreaking new technique at the National Institute of Standards and Technology (NIST), an international collaboration led by NIST researchers has revealed previously unrecognized properties of technologically crucial silicon crystals and uncovered new information about an important subatomic particle and a long-theorized fifth force of nature.

By aiming subatomic particles known as neutrons at silicon crystals and monitoring the outcome with exquisite sensitivity, the NIST scientists were able to obtain three extraordinary results: the first measurement of a key neutron property in 20 years using a unique method; the highest-precision measurements of the effects of heat-related vibrations in a silicon crystal; and limits on the strength of a possible “fifth force” beyond standard physics theories.

The researchers report their findings in the journal Science.

In a regular crystal such as silicon, there are many parallel sheets of atoms, each of which forms a plane. Probing different planes with neutrons reveals different aspects of the crystal.  Credit: NIST

To obtain information about crystalline materials at the atomic scale, scientists typically aim a beam of
particles (such as X-rays, electrons or neutrons) at the crystal and detect the beam’s angles, intensities and patterns as it passes through or ricochets off planes in the crystal’s lattice-like atomic geometry.

That information is critically important for characterizing the electronic, mechanical and magnetic properties of microchip components and various novel nanomaterials for next-generation applications including quantum computing. A great deal is known already, but continued progress requires increasingly detailed knowledge.

“A vastly improved understanding of the crystal structure of silicon, the ‘universal’ substrate or foundation material on which everything is built, will be crucial in understanding the nature of components operating near the point at which the accuracy of measurements is limited by quantum effects,” said NIST senior project scientist Michael Huber.

Neutrons, Atoms and Angles

Like all quantum objects, neutrons have both point-like particle and wave properties. As a neutron travels through the crystal, it forms standing waves (like a plucked guitar string) both in between and on top of rows or sheets of atoms called Bragg planes. When waves from each of the two routes combine, or “interfere” in the parlance of physics, they create faint patterns called pendellösung oscillations that provide insights into the forces that neutrons experience inside the crystal.

“Imagine two identical guitars,” said Huber. “Pluck them the same way, and as the strings vibrate, drive one down a road with speed bumps — that is, along the planes of atoms in the lattice — and drive the other down a road of the same length without the speed bumps — analogous to moving between the lattice planes. Comparing the sounds from both guitars tells us something about the speed bumps: how big they are, how smooth, and do they have interesting shapes?”

The latest work, which was conducted at the NIST Center for Neutron Research (NCNR) in Gaithersburg, Maryland, in collaboration with researchers from Japan, the U.S. and Canada, resulted in a fourfold improvement in precision measurement of the silicon crystal structure.

Not-Quite-Neutral Neutrons

Each neutron in an atomic nucleus is made up of three elementary particles called quarks. The three quarks’ electrical charge sum to zero, making it electrically neutral. But the distribution of those charges is such that positive charges are more likely to be found in the center of the neutron, and negative charges toward the outside.  Credit: NIST

In one striking result, the scientists measured the electrical “charge radius” of the neutron in a new way with an uncertainty in the radius value competitive with the most-precise prior results using other methods. Neutrons are electrically neutral, as their name suggests. But they are composite objects made up of three elementary charged particles called quarks with different electrical properties that are not exactly uniformly distributed.

As a result, predominantly negative charge from one kind of quark tends to be located toward the outer part of the neutron, whereas net positive charge is located toward the center. The distance between those two concentrations is the “charge radius.” That dimension, important to fundamental physics, has been measured by similar types of experiments whose results differ significantly. The new pendellösung data is unaffected by the factors thought to lead to these discrepancies.

Measuring the pendellösung oscillations in an electrically charged environment provides a unique way to gauge the charge radius. “When the neutron is in the crystal, it is well within the atomic electric cloud,” said NIST’s Benjamin Heacock, the first author on the Science paper.

“In there, because the distances between charges are so small, the interatomic electric fields are enormous, on the order of a hundred million volts per centimeter. Because of that very, very large field, our technique is sensitive to the fact that the neutron behaves like a spherical composite particle with a slightly positive core and a slightly negative surrounding shell.”

Vibrations and Uncertainty

A valuable alternative to neutrons is X-ray scattering. But its accuracy has been limited by atomic motion caused by heat. Thermal vibration causes the distances between crystal planes to keep changing, and thus changes the interference patterns being measured.

The scientists employed neutron pendellösung oscillation measurements to test the values predicted by X-ray scattering models and found that some significantly underestimate the magnitude of the vibration.

The results provide valuable complementary information for both x-ray and neutron scattering. “Neutrons interact almost entirely with the protons and neutrons at the centers, or nuclei, of the atoms,” Huber said, “and x-rays reveal how the electrons are arranged between the nuclei. This complementary knowledge deepens our understanding.

“One reason our measurements are so sensitive is that neutrons penetrate much deeper into the crystal than x-rays – a centimeter or more – and thus measures a much larger assembly of nuclei. We have found evidence that the nuclei and electrons may not vibrate rigidly, as is commonly assumed. That shifts our understanding on the how silicon atoms interact with one another inside a crystal lattice.”

Force Five

The Standard Model is the current, widely accepted theory of how particles and forces interact at the smallest scales. But it’s an incomplete explanation of how nature works, and scientists suspect there is more to the universe than the theory describes.

The Standard Model describes three fundamental forces in nature: electromagnetic, strong and weak. Each force operates through the action of “carrier particles.” For example, the photon is the force carrier for the electromagnetic force. But the Standard Model has yet to incorporate gravity in its description of nature. Furthermore, some experiments and theories suggest the possible presence of a fifth force.

“Generally, if there’s a force carrier, the length scale over which it acts is inversely proportional to its mass,” meaning it can only influence other particles over a limited range, Heacock said. But the photon, which has no mass, can act over an unlimited range. “So, if we can bracket the range over which it might act, we can limit its strength.” The scientists’ results improve constraints on the strength of a potential fifth force by tenfold over a length scale between 0.02 nanometers (nm, billionths of a meter) and 10 nm, giving fifth-force hunters a narrowed range over which to look.

The researchers are already planning more expansive pendellösung measurements using both silicon and germanium. They expect a possible factor of five reduction in their measurement uncertainties, which could produce the most precise measurement of the neutron charge radius to date and further constrain — or discover — a fifth force. They also plan to perform a cryogenic version of the experiment, which would lend insight into how the crystal atoms behave in their so-called “quantum ground state,” which accounts for the fact that quantum objects are never perfectly still, even at temperatures approaching absolute zero.

Source/Credit: National Institute of Standards and Technology

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How land birds cross the open ocean

 

Terrestrial birds are capable of flying for hundreds of kilometers over the open sea. Nourani et al. show that the autumn migration trajectories of some of these birds correspond with uplift over the sea surface. Suitable uplift means less drag, making sea-crossing less energetically demanding. Moreover, strong uplift can allow the birds to soar.
© Elham Nourani / Max Planck Institute of Animal Behavior

Migrating birds choose routes with the best wind and uplift conditions, helping them to fly nonstop for hundreds of kilometers over the sea

Researchers at the Max Planck Institute of Animal Behavior and University of Konstanz in Germany have identified how large land birds fly nonstop for hundreds of kilometers over the open ocean—without taking a break for food or rest. Using GPS tracking technology, the team monitored the global migration of five species of large land birds that complete long sea crossings. They found that all birds exploited wind and uplift to reduce energy costs during flight—even adjusting their migratory routes to benefit from the best atmospheric conditions. This is the most wide-ranging study of sea-crossing behavior yet and reveals the important role of the atmosphere in facilitating migration over the open sea for many terrestrial birds.

Flying over the open sea can be dangerous for land birds. Unlike seabirds, land birds are not able to rest or feed on water, and so sea crossings must be conducted as nonstop flights. For centuries, bird-watchers assumed that large land birds only managed short sea crossings of less than 100 kilometers and completely avoided flying over the open ocean.

However, recent advances in GPS tracking technology have overturned that assumption. Data obtained by attaching small tracking devices on wild birds has shown that many land birds fly for hundreds or even thousands of kilometers over the open seas and oceans as a regular part of their migration.

But scientists are still unraveling how land birds are able to accomplish this. Flapping is an energetically costly activity, and trying to sustain nonstop flapping flight for hundreds of kilometers would not be possible for large, heavy land birds. Some studies have suggested that birds sustain such journeys using tailwind, a horizontal wind blowing in the bird’s direction of flight, which helps them save energy. Most recently, a study revealed that a single species—the osprey—used rising air thermals known as “uplift” to soar over the open sea.

Now, the new study has examined sea-crossing behavior of 65 birds across five species to gain the most wide-ranging insight yet into how land birds survive long flights over the open sea. The researchers analyzed 112 sea-crossing tracks, collected over nine years, with global atmospheric information to pinpoint the criteria that the birds use for selecting their migration routes over the open sea. A large international collaboration of scientists shared their tracking data to make this study possible.

The findings not only confirm the role of tailwind in facilitating sea-crossing behavior, but also reveal the widespread use of uplift for saving energy during these nonstop flights. Suitable uplift means less drag, making sea crossing less energetically demanding.

“Until recently, uplift was assumed to be weak or absent over the sea surface. We show that is not the case,” says first author Elham Nourani, a DAAD PRIME postdoctoral fellow at the Department of Biology at the University of Konstanz, who did the work when she was at the Max Planck Institute of Animal Behavior.

Terrestrial birds are capable of flying for hundreds of kilometers over the open sea. Nourani et al. show that the autumn migration trajectories of

some of these birds correspond with uplift over the sea surface. Suitable uplift means less drag, making sea-crossing less energetically demanding. Moreover, strong uplift can allow the birds to soar.

“Instead, we find that migratory birds adjust their flight routes to benefit from the best wind and uplift conditions when they fly over the sea. This helps them sustain flight for hundreds of kilometers,” says Nourani.

The oriental honey buzzard, for example, flies 700 kilometers over the East China Sea during its annual migration from Japan to southeast Asia. The roughly 18-hour nonstop sea crossing is conducted in autumn when the air movement conditions are optimal. “By making use of uplift, these birds can soar up to one kilometer above the sea surface,” says Nourani.

The study also raises the question of how migration will be affected by a changing climate. “Our findings show that many land birds are dependent on atmospheric support to complete their migrations over the open sea, indicating their vulnerability to any changes to the Earth’s atmospheric circulation patterns,” says Nourani. “Collaborative studies like this are important to unravel general patterns about how migratory birds depend on the weather patterns. This enables future studies to make robust predictions about how these birds will be impacted by climate change.”

Source/Credit: Max-Planck-Gesellschaft

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The development of non-opioid painkillers to treat chronic pain

 

An image of the cryogenic electron microscopy structure of the human adenosine
A1 receptor (colored blue) bound to its signaling protein
(colored pink, green, and purple), adenosine (purple spheres)
and a proof-of-concept non-opioid analgesic (colored as orange spheres).

Monash University researchers have made a breakthrough discovery that could pave the way for the development of novel non-opioid painkillers (analgesics) to safely and effectively treat neuropathic pain.

The research was published today in the prestigious journal Nature.

Neuropathic pain is a type of chronic pain that can occur if your nervous system is damaged or not working correctly, and can be caused by injury, virus infection or cancer treatment, or be a symptom or complication of conditions such as multiple sclerosis and diabetes.

The new study, led by world-renowned drug researchers from the Monash Institute of Pharmaceutical Sciences (MIPS) and the Monash Biomedicine Discovery Institute (BDI), has demonstrated a new mode of targeting the adenosine A1 receptor protein, which has long been recognized as a promising therapeutic target for non-opioid painkillers to treat neuropathic pain but for which the development of painkillers had failed due to a lack of sufficient on-target selectivity, as well as undesirable adverse effects.

In the study, Monash researchers used electrophysiology and preclinical pain models to demonstrate that a particular class of molecule, called a ‘positive allosteric modulator’ (PAM), can provide much more selective targeting of the A1 receptor by binding to a different region of the protein than traditional, previously investigated, activators.

Another breakthrough in the study was facilitated by the application of cryo electron microscopy (cryoEM) to solve the high-resolution structure of the A1 receptor bound to both its natural activator, adenosine, and an analgesic PAM, thus providing the first atomic level snapshot of where these drugs bind.

Chronic pain remains a widespread global health burden, with lack of current therapeutic options leading to an over-reliance on opioid painkillers, which provide limited relief in patients with chronic (particularly neuropathic) pain, while exhibiting severe adverse effects, such as respiratory depression and addiction.

The new Monash discovery provides the opportunity for researchers to develop non-opioid drugs that lack such side effects.

Co-corresponding author of the study and Dean of the Faculty of Pharmacy and Pharmaceutical Sciences (home to MIPS), Professor Arthur Christopoulos said: “The world is in the grip of a global opioid crisis and there is an urgent need for non-opioid drugs that are both safe and effective.”

Associate Professor Wendy Imlach, who is the head of the Pain Mechanisms lab at Monash BDI and a co-corresponding author of the work, stated: “This study has helped us to better understand mechanisms underpinning allosteric drug actions. One of the exciting things we found is that not only were the PAMs able to decrease neuropathic pain with minimal unwanted effects, but they actually increase their level of effectiveness as the pain signals in the spinal cord get stronger – thus highlighting the potential for allosteric medicines that are uniquely sensitive to disease context”.

Professor Christopoulos added: “This multidisciplinary study now provides a valuable launchpad for the next stage in our drug discovery pipeline, which will leverage structure-based insights for the design of novel non-opioid allosteric drugs to successfully treat chronic pain.”

This work was performed in collaboration with researchers from the Universities of Sydney, Kansas and Tokyo, Uppsala University, and the ARC Centre for cryo-Electron Microscopy of Membrane Proteins. It was supported by the National Health and Medical Research Council of Australia, the Australian Research Council, the Australian Heart Foundation, the American Heart Association and the National Institutes of Health, and the Swedish Research Council.

Source/Credit: Monash University

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