Tech

Research mapping the evolution of mosquitos against rising CO2 levels over millions of years, has suggested that more mosquito-related diseases could have consequences for future human health as the climate continues to change.

The research showed that whilst there is a link between rising CO2 levels and mosquito evolution, it is less directly linked than previously thought, with other factors, such as the diversity of mammal hosts, contributing to an increase in the species richness of mosquitos.

Many mosquito-borne diseases have been eradicated in areas of Europe, whilst many parts of Asia and Africa still harbour diseases such as malaria, Yellow fever, Zika virus, and Dengue fever.

Female mosquitos can identify sources of blood-meal from the CO2 levels that mammals release from their bodies. There is now concern that as CO2 levels rise as a result of human activity, so too will the diversity of disease-carrying mosquitos.

There is limited research, however, on how the mosquito is evolving in a changing climate and how and why the species is diversifying.

The new study, from researchers at the University of York, the University of Bath, and China Agricultural University, shows for the first time the impact that climate change is having on the rate in which mosquitos diversify, and what this might mean for human health in the future.

Dr Katie Davis, from the University of York's Department of Biology, said: "We constructed an evolutionary tree of mosquito species, and then mapped it against past climate change. We then used a mathematical model to look at direct cause and effect, which revealed that rising CO2 levels overtime has increased species of mosquito, but less directly than we previously thought.

"We found that the increase in the diversity of mammals led directly to a rise in the number of mosquito species, and also that there is a relationship between CO2 levels and the number of mammal species, but there are missing pieces of this puzzle, so we can still only speculate at this stage."

More research is needed to understand what climate change means for the future of the mosquito and the work will contribute to further discussions about the value of the mosquito to the ecosystem and how to manage the diseases they carry.

Professor Matthew Wills, from the University of Bath, said: "It's only the female mosquitos that take a blood meal, and they use the CO2 that mammals and other vertebrates exhale as a very general cue to locate their hosts. One line of thinking is that as ambient levels of atmospheric CO2 rose, mosquitos may have found it increasingly difficult to distinguish between the CO2 from their hosts and those background levels.

"Vision, body heat and other smells might then have become more important in locating their blood meals, but many of these cues tend to be more specific to particular hosts. As a general rule, we know that a strong host specificity can be an important driver of speciation in parasites, and the same may be true in mosquitos."

Chufei Tang, from China Agricultural University, said: "The rising atmospheric CO2 has been proven to influence various kinds of organisms, but this is the first time such impact has been found on insects. This research provides yet another reason for people to participate in low-carbon lifestyles."

Dr Davis added: "Despite some uncertainties we can now show that mosquito species are able to evolve and adapt to climate change in high numbers. With increased speciation, however, comes the added risk of disease increase and the return of certain diseases in countries that had eradicated them or never experienced them before."

New research has uncovered genetic variations that may contribute to the development of non-alcoholic fatty liver disease (NAFLD), the leading cause of liver disease.

NAFLD is major health concern in Western countries, with one in four people, including children, affected.

The international collaboration led by Associate Professor Mohammed Eslam and Professor Jacob George of the Westmead Institute for Medical Research, studied more than 1,000 patients with NAFLD to establish a link between genes and a build-up of fat in the liver, known as hepatic steatosis.

The team found that three genetic variations - FNDC5 rs3480, PNPLA3 1148M, and TM6SF2 E167K - were linked to increased fat in the liver.

Lead author Dr Mayada Metwally said the findings strengthened the link between genetics and liver disease, which could lead to new treatment options.

"Hepatic steatosis is one of the major risk factors for NAFLD, so if we can understand its causes, we can work towards preventing it," she explained.

"We've previously thought that genes such as FNDC5, which help make a protein called irisin, play a role in depositing fat in the liver, but this is the first time we've demonstrated the link and identified the mechanisms.

"Our findings show that these genetic variants contribute to liver fat in people with NAFLD. The more variants a person has, the more likely they are to accumulate fat in the liver."

Left untreated, NAFLD can also cause complications in the heart and kidneys.

"The growing number of people with NAFLD is alarming, particularly since many patients don't develop symptoms until the condition is advanced," Dr Metwally said.

"Understanding the genetic causes of NAFLD is crucial. We can now look towards targeting these genetic variations as a potential treatment to slow the progression of disease."

About the science

The team discovered how a single-letter variation in the FNDC5 gene mediates differences between those at risk of severe steatosis, and those who are not. The authors show that a particular microRNA is induced in the liver of people with NAFLD.

MicroRNAs are silencers: they stop the 'messengers' that transmit information to produce a protein from a gene, in this case, the production of the protective protein FNDC5. The researchers also observed that this 'bad' microRNA binds too and represses FNDC5 production.

Glasgow, UK: A chemical that highlights tumour cells has been used by surgeons to help spot and safely remove brain cancer in a trial presented at the 2018 NCRI Cancer Conference.

The research was carried out with patients who had suspected glioma, the disease that killed Dame Tessa Jowell, and the most common form of brain cancer. Treatment usually involves surgery to remove as much of the cancer as possible, but it can be challenging for surgeons to identify all of the cancer cells while avoiding healthy brain tissue.

Researchers say that using the fluorescent marker helps surgeons to distinguish the most aggressive cancer cells from other brain tissue and they hope this will ultimately improve patient survival.

The research was presented by Dr Kathreena Kurian, a Reader/Associate Professor in brain tumour research at the University of Bristol and consultant neuropathologist at North Bristol NHS Trust, UK. The study was led by Colin Watts, Professor of Neurosurgery and chair of the Birmingham brain cancer programme at the University of Birmingham, UK.

Dr Kurian explained: "Gliomas are difficult to treat with survival times often measured in months rather than years. Many patients are treated with surgery and the aim is to safely remove as much of the cancer as possible. Once a tumour is removed, it is passed on to a pathologist who examines the cells under a microscope to see if they are 'high-grade', fast growing cells, or 'low-grade' slower growing cells. And we can plan further treatment, such as radiotherapy or chemotherapy, based on that diagnosis.

"We wanted to see if using a fluorescent marker could help surgeons objectively identify high-grade tumour cells during surgery, allowing them to remove as much cancer as possible while leaving normal brain tissue intact."

The researchers used a compound called 5-aminolevulinic acid or 5-ALA, which glows pink when a light is shone on it. Previous research shows that, when consumed, 5-ALA accumulates in fast growing cancer cells and this means it can act as a fluorescent marker of high-grade cells.

The study involved patients with suspected high-grade gliomas treated at the Royal Liverpool Hospital, Kings College Hospital in London or Addenbrooke's Hospital in Cambridge, UK. They were aged between 23 and 77 years, with an average (median) age of 59 years. Before surgery to remove their brain tumours, each patient was given a drink containing 5-ALA.

Surgeons then used operating microscopes to help them look for fluorescent tissue while removing tumours from the patients' brains. The tissue they removed was sent to the pathology lab where scientists could confirm the accuracy of the surgeons' work.

A total of 99 patients received the 5-ALA marker and could be assessed for signs of fluorescence. During their operations, surgeons reported seeing fluorescence in 85 patients and 81 of these were subsequently confirmed by pathologists to have high-grade disease, one was found to have low-grade disease and three could not be assessed.

In the 14 patients where surgeons did not see any fluorescence, only seven tumours could be subsequently evaluated by pathology but in all these cases, low-grade disease was confirmed.

Professor Watts said: "Neurosurgeons need to be able to distinguish tumour tissue from other brain tissue, especially when the tumour contains fast-growing, high-grade cancer cells. This is the first prospective trial to show the benefits of using 5-ALA to improve the accuracy of diagnosing high-grade glioma during surgery. These results show that the marker is very good at indicating the presence and location of high-grade cancer cells.

"The advantage of this technique is that it may highlight more quickly high-grade disease within a tumour during neurosurgery. What this means is that more of the tumour can be removed more safely and with fewer complications, and that's better for the patient."

The researchers caution that the study looked at patients who were already suspected to have high-grade tumours, and a larger study in which more patients have low-grade disease would provide more information on the use of this technique. They say that other types of markers may need to be tested for detecting low-grade glioma cells.

Next steps could include testing the 5-ALA in children with brain tumours, or to help surgeons distinguish between tumour tissue and scar tissue in adult patients whose brain cancers have recurred following treatment.

Professor Anthony Chalmers is Chair of NCRI's Clinical and Translational Radiotherapy Research Working Group and Chair of Clinical Oncology at the University of Glasgow, UK, and was not involved in the research. He said: "There is a desperate need for better treatments for brain tumours and to achieve that we need more high quality research in this area.

"The benefit of using a fluorescent marker is that it helps neurosurgeons see more accurately where the high-grade cancer is within the brain, in real time. In treating cancer, we are trying to improve survival by tailoring treatments to each individual patient. This technique provides on-the-spot information to help surgeons tailor the operation according to the location, size and grade of the tumour. We know that patients who have near total removal of their tumour have better outcomes, so we are optimistic that, in the long term, these new data will help to increase survival times for glioma patients."

Donnelly Centre researchers have uncovered a genetic network linked to autism. The findings, described in the journal Molecular Cell, will facilitate developing new therapies for this common neurological disorder.

As part of a collaborative research program focusing on autism led by Benjamin Blencowe, a professor in the University of Toronto's Donnelly Centre for Cellular and Biomolecular Research, postdoctoral fellow Thomas Gonatopoulos-Pournatzis, lead author of the study, uncovered a network of more than 200 genes involved in controlling alternative splicing events that are often disrupted in autism spectrum disorder (ASD). Alternative splicing is a process that functionally diversifies protein molecules--cells' building blocks--in the brain and other parts of the body. Blencowe's laboratory previously showed that disruption of this process is closely linked to altered brain wiring and behaviour found in autism.

"Our study has revealed a mechanism underlying the splicing of very short coding segments found in genes with genetic links to autism," says Blencowe, who is also a professor in the Department of Molecular Genetics and holds the Banbury Chair of Medical Research at U of T.

"This new knowledge is providing insight into possible ways of targeting this mechanism for therapeutic applications".

Best known for its effects on social behaviour, autism is thought to be caused by mishaps in brain wiring laid down during embryo development. Hundreds of genes have been linked to autism, making its genetic basis difficult to untangle. Alternative splicing of small gene fragments, or microexons, has emerged as a rare, unifying concept in the molecular basis of autism after Blencowe's team previously discovered that microexons are disrupted in a large proportion of autistic patients.

Learn how microexons contribute to autism

As tiny protein-coding gene segments, microexons impact the ability of proteins to interact with each other during the formation of neural circuits. Microexons are especially critical in the brain, where they are included into the RNA template for protein synthesis during the splicing process. Splicing enables the utilization of different combinations of protein-coding segments, or exons, as a way of boosting the functional repertoires of protein variants in cells.

And while scientists have a good grasp of how exons, which are about 150 DNA letters long, are spliced, it remained unclear how the much-smaller microexons-- a mere 3-27 DNA letters long--are utilized in nerve cells.

"The small size of microexons' presents a challenge for the splicing machinery and it has been a puzzle for many years how these tiny exons are recognized and spliced," says Blencowe.

To answer this question, Gonatopoulos-Pournatzis developed a method for identifying genes that are involved in microexon splicing. Using the powerful gene editing tool CRISPR, and working with Mingkun Wu and Ulrich Braunschweig in the Blencowe lab as well as with Jason Moffat's lab in the Donnelly Centre, Gonatopoulos-Pournatzis removed from cultured brain cells each of the 20,000 genes in the genome to find out which ones are required for microexon splicing. He identified 233 genes whose diverse roles suggest that microexons are regulated by a wide network of cellular components.

"A really important advantage of this screen is that we've been able to capture genes that affect microexon splicing both directly and indirectly and learn how various molecular pathways impinge on this process," says Blencowe.

Furthermore, Gonatopoulos-Pournatzis was able to find other factors that work closely with a previously identified master regulator of microexon splicing, a protein called nSR100/SRRM4, discovered previously in the Blencowe lab. Working with Anne-Claude Gingras' team at Sinai Health System's Lunenfeld-Tanenbaum Research Institute, they identified proteins called Srsf11 and Rnps1 as forming a molecular complex with nSR100.

Knowing the precise molecular mechanisms of microexon splicing will help guide future efforts to develop potential therapeutics for autism and other disorders. For example, because the splicing of microexons is disrupted in autism, researchers could look for drugs capable of restoring their levels to those seen in unaffected individuals.

"We now better understand the mechanism of how the microexons are recognized and spliced specifically in the brain," says Gonatopoulos-Pournatzis, who recently won the Donnelly Centre's newly established Research Excellence Award . "When you know the mechanism, you can potentially target it using rational approaches to develop therapies for neurodevelopmental disorders."

PROVIDENCE, R.I. [Brown University] -- Researchers from Brown University and the Institute of Metals Research at the Chinese Academy of Sciences have found a new way to use nanotwins -- tiny linear boundaries in a metal's atomic lattice that have identical crystalline structures on either side -- to make stronger metals.

In a paper in the journal Science, the researchers show that varying the spacing between twin boundaries, as opposed to maintaining consistent spacing throughout, produces dramatic improvements in a metal's strength and rate of work hardening -- the extent to which a metal strengthens when deformed.

Huajian Gao, a professor in Brown's School of Engineering who co-led the work, says the research could point toward new manufacturing techniques for high-performance materials.

"This work deals with what's known as a gradient material, meaning a material in which there's some gradual variation in its internal makeup," Gao said. "Gradient materials are a hot research area because they often have desirable properties compared to homogeneous materials. In this case, we wanted to see if a gradient in nanotwin spacing produced new properties."

Gao and his colleagues have already shown that nanotwins themselves can improve material performance. Nanotwinned copper, for example, has shown to be significantly stronger than standard copper, with an unusually high resistance to fatigue. But this is the first study to test the effects of variable nanotwin spacing.

Gao and his colleagues created copper samples using four distinct components, each with different nanotwin boundary spacing. Spacings ranging from 29 nanometers between boundaries to 72 nanometers. The copper samples were comprised of different combinations of the four components arranged in different orders across the thickness of the sample. The researchers then tested the strength of each composite sample, as well as the strength of each of the four components.

The tests showed that all of the composites were stronger than the average strength of the four components from which they were made. Remarkably, one of the composites was actually stronger than the strongest of its constituent components.

"To give an analogy, we think of a chain as being only as strong as its weakest link," Gao said. "But here, we have a situation in which our chain is actually stronger than its strongest link, which is really quite amazing."

Other tests showed that the composites also had higher rates of work hardening than the average of their constituent components.

To understand the mechanism behind these increases in performance, the researchers used computer simulations of their samples' atomic structure under strain. At the atomic level, metals respond to strain through the motion of dislocations -- line defects in the crystalline structure where atoms are pushed out of place. The way in which those dislocations grow and interact with each other is what determines a metal's strength.

The simulations revealed that the density of dislocations is much higher in the gradient copper than in a normal metal.

"We found a unique type of dislocation we call bundles of concentrated dislocations, which lead to dislocations an order of magnitude denser than normal," Gao said. "This type of dislocation doesn't occur in other materials and it's why this gradient copper is so strong."

Gao said that while the research team used copper for this study, nanotwins can be produced in other metals as well. So it's possible that nanotwin gradients could improve the properties of other metals.

"We're hoping that these findings will motivate people to experiment with twin gradients in other types of materials," Gao said.

Knots are indispensable tools for such human activities as sailing, fishing and rock climbing, (not to mention, tying shoes). But tying a knot in a lacelike strand of DNA, measuring just billionths of a meter in length, requires patience and highly specialized expertise.

Hao Yan, a researcher at ASU, is a practiced hand in this delicate and exotic field, operating at the crossroads of nanotechnology and fine art.

In new research appearing in the journal Nature Communications, Yan and his colleagues Fei Zhang, Xiaodong Qi and others describe a method for coaxing segments of single-stranded DNA into complex 2- and 3D knotted structures.

The results represent an important advance in the fast-paced field of DNA nanotechnology, in which the molecule of life is used as a structural building material for a vast array of tiny configurations. Among these are miniscule robotic devices, photonic applications, drug delivery systems, logic gates, as well as diagnostic and therapeutic applications.

"The knotted DNA structures demonstrated in this work exhibit unprecedented topological complexity, far beyond what has been achieved before using single stranded folding," Yan says. "Indeed, it is not only amazing but also surprising that the single-stranded DNA and RNA can thread through its own chains and find a way to form such highly knotted structures, given the fact that the single strand has to weave through so many tangles."

Yan directs the Biodesign Center for Molecular Design and Biomimetics and is the Martin D. Glick Distinguished Professor in the School of Molecular Sciences at ASU.

Bringing DNA into the fold

The new study involves innovations in the field of DNA origami, which, as the name implies, uses nucleic acids like DNA and RNA to fold and self-assemble into complex forms. This occurs when complementary nucleotide bases in DNA's 4-letter alphabet come in contact and bind, according to a strict regimen: C bases always pair with G and A bases always pair with T.

In nature, strings of nucleic acids provide the code needed to make complex proteins. This basic biology provides the underpinning for all earthly life. Taking advantage of the simple base-pairing properties of DNA, it is possible to design structures that will self-assemble in the lab. The method has been applied to both single-stranded and double-stranded DNA forms, resulting in nanostructures of increasing complexity and sophistication.

While DNA origami has made startling advances since its inception, one technical innovation has been vexingly difficult to achieve. Until now, creating complex knotted structures in DNA in a predictable and programmable way has eluded researchers.

The new work overcomes this hurdle, establishing precise design rules that permit single-stranded segments of DNA (or RNA) ranging from 1800-7500 nucleotides to form knot-like nanostructures with crossing numbers (where the DNA strand weaves in and out of its own length) ranging from 9 to 57.

The group further demonstrated that these nucleic acid nanostructures can be replicated and amplified, both under laboratory conditions and within living systems.

Nature's knots

Knotted structures, like those Yan has fabricated, (but much simpler than the synthetic ones), have correlates in the natural world. They have been observed in DNA and proteins and generally form during replication and transcription, (when a DNA sequence is copied into messenger RNA). They can also occur in the genomes of phages--viruses that infect bacterial cells.

Nevertheless, the construction of molecular knots at the nanometer scale, displaying well-defined and consistent geometries requires enormous control and precision. As it happens, nucleic acids like DNA are ideal for the design and synthesis of such molecular knots.

Previously, lengths of double-stranded DNA have been used for nanoscale constructions, with the addition of short pieces or "staple strands" to fasten resulting structures together. The new study instead uses a single length of DNA designed to wrap around itself in a precise, pre-programmed sequence of steps.

Once the knotted DNA nanostructures successfully assemble themselves, they are imaged using atomic force microscopy. Careful calculation allows the researchers to optimize the folding pathways to produce the highest yield for each synthetic structure. The use of single- rather than double-stranded DNA allows the structures to be produced in abundance at much lower cost.

A single-stranded approach opens the door for the design of nanoarchitectures with specific, well-defined functions, which can be produced through successive rounds of in vitro evolution, where desired attributes are selected for in a repetitive process of refinement. Further, the approach outlined in the new study provides a general platform for the design of molecular structures of increased size and unprecedented complexity, paving the way for advances in nanophotonics, drug delivery, cryo-EM analysis and DNA-based memory storage.

Designer DNA (and RNA)

For one of the initial knot designs the strategy Yan and his colleagues developed involved threading a single strand of DNA or RNA through itself 9 times according to a pre-programmed sequence, demonstrating that the new method is capable of producing intricate geometric shapes that are programmable, replicable and scalable.

The design strategy was subsequently expanded to include single-stranded RNA structures and 3D DNA knots, whose forms were reconstructed using a technique known as cryogenic transmission electron microscopy, confirming their proper folding into the desired shapes.

"One of the challenges in this work is how to increase the assembly yield of highly knotted structures." Said Fei. Unlike classic DNA nanostructures, the single-stranded knots are less forgiving in terms of precise folding order due to the topological complexity. If a single crossing is misfolded during the process, the error will hardly be self-corrected and most of the misfoldings will remain in the completed structure. "We developed a hierarchical folding strategy to guide the correct formation of knots. We compared the folding efficiency of a knot with 23 crossings by using different folding pathways. The AFM images showed a dramatic increase in the folding yield of well-form structures from 0.9% to 57.9% by applying optimized hierarchical folding pathway." Fei added.

The design rules used to optimize the folding pathways are based on the number of crossing points, the length of DNA and the number of base pairs in the designed structure. Three primary rules were established. First, linear folding paths were found to be preferable to branched paths. Second, the unfolded section of a DNA strand should not thread through itself in the early stages when the strand is still long. Finally, edges of the desired form that have three crossings should fold before those with two crossings.

Following the design strategy, the team was able to create more complex DNA knots with increasing crossing numbers.

Longer chains of single-stranded DNA pose unique challenges for designing programmed nanostructures due to the increased likelihood of unintended self-complementarity of the bases making up the chain. A DNA knot structure boasting 57 crossed nodes successfully assembled, though with lower yield and less precision. When the crossing number was increased to 67, the yield significantly dropped and the resulting structures, imaged by AFM, showed more errors of assembly.

The study reports the largest DNA knots yet assembled, formed from up to 7.5k bases, featuring the most complicated topologies, with up to 57 crossing regions. The single-stranded DNA sequences can be mass produced in living cells for greater efficiency at lower cost. Ultimately, DNA nanostructures of diverse function may be formed within cells, innovations to be pursued in future work.

Researchers at the U.S. Army Research Laboratory and the Joint Quantum Institute have created a pristine quantum light source that has the potential to lead to more secure communications and enhanced sensing capabilities for Soldiers.

ARL's Dr. Elizabeth Goldschmidt and JQI's Dr. Sunil Mittal and Prof. Mohammad Hafezi discuss this research in their paper titled "A topological source of quantum light" that is featured in the journal Nature.

Photons, the smallest amount of light that exists, are useful when it comes to carrying quantum information, which can be used for encryption to avoid interception from adversaries and enhanced sensitivity to the environment.

According to the researchers, one major part of the puzzle is that the photons must be undisturbed and as similar as possible in order for secure communications and Soldier systems to operate at the highest quality.

The research team has successfully developed a silicon chip that guides light around the device's edge, where it is protected from disruptions.

"Quantum sources, such as the one demonstrated in our research, are an enabling technology for integrated photonics-based scalable quantum networks and quantum information systems that require indistinguishable photons," Goldschmidt said

For this experiment, the researchers used silicon to convert infrared laser light into pairs of different-colored single photons.

"We injected light into a chip containing an array of miniscule silicon loops, and the light circulates around each loop thousands of times before moving on to a neighboring loop," Goldschmidt said.

According to Goldschmidt, the issue with the long journey the light takes, while necessary to get many pairs of single photons out of the silicon chip, is that small differences and defects in the material reduce photon quality.

"This is a problem for quantum information applications, as researchers need photons to be truly identical," Goldschmidt said.

To solve this issue, the team rearranged the loops in a way that allows the light to travel undisturbed around the edge of the chip, shielding the light from disruptions.

"This so-called topological protection uses the geometry of the system, rather than the local material properties, to guide the light," Goldschmidt said. "The relatively new field of topological photonics has focused to date on classical, rather than quantum, light fields and this work takes a step forward by demonstrating generation of quantum light in the topologically protected mode."

An added benefit to the silicon chip developed is that it works at room temperature unlike other quantum light sources that must be cooled down, making the process a whole lot simpler.

For Goldschmidt, this project opens up a new research chapter for her, and is one that she hopes includes similar collaborative opportunities.

"My research interests span many aspects of quantum optics, and this work has allowed me to learn more about the emerging field of topological photonics," Goldschmidt said. "I hope that this paper acts as a foundation for future work at the intersection of quantum optics and topological photonics and I am looking forward to continuing to collaborate with Professor Hafezi."

As far as next steps to turn this research into reality, the team has plans to improve this source by using waveguides with less unwanted absorption and will continue to study the quantum properties of their topological photonic system.

Transportation--Going with the flow

Self-driving cars promise to keep traffic moving smoothly and reduce fuel usage, but proving those advantages has been a challenge with so few connected and automated vehicles, or CAVs, currently on the road. To study the potential benefits, researchers at Oak Ridge National Laboratory developed a simulation framework that analyzes the impact of partial market penetration of CAVs on fuel consumption, travel time and traffic flow in a merging on-ramp scenario under low, medium and heavy traffic volumes. "We observed that an increased number of CAVs communicating and coordinating driving activity stabilize traffic flow and, depending on the traffic volume, can reduce fuel use by more than 40 percent," said ORNL's Jacky Rios-Torres. "A steady traffic pattern, in turn, improves travel time." Future research will explore the impact of CAVs in various traffic scenarios and determine whether CAVs can indirectly influence the driving performance of human-driven cars. The team's results were published in IEEE Transactions on Intelligent Vehicles. [Contact: Jennifer Burke, (865) 576-3212; burkejj@ornl.gov]

Image: https://www.ornl.gov/sites/default/files/Autonomous_vehicle_simulation_ORNL.jpg

Caption: ORNL researchers created a simulation framework to study how coordinated connected and automated vehicles could improve traffic flow and reduce energy consumption during a merging on-ramp scenario while interacting with human drivers. Credit: Oak Ridge National Laboratory, U.S. Dept. of Energy

Physics--Elements at extremes

In neutron star mergers and supernovae, lighter elements absorb neutrons to create heavier elements whose nuclei are neutron-rich and radioactive. To better understand this phenomenon, physicists turned to the "doubly magic" tin isotope Sn-132, colliding it with a target at Oak Ridge National Laboratory to assess its properties as it lost a neutron to become Sn-131. The results, published after years of complex data analysis, were combined with a prior experiment in which a nucleus of Sn-132 gained a neutron to become Sn-133. "Many ambiguities are reduced by systematically studying the addition and subtraction of neutrons," said ORNL's Steven Pain. "This is the first time this technique has been applied to such a heavy neutron-rich nucleus. These results will help benchmark theoretical models and guide future investigations of unstable nuclei with even greater neutron surpluses." The experiment was the last conducted at ORNL's Holifield Radioactive Ion Beam Facility before it ceased operations in 2012. [Contact: Dawn Levy, (865) 576-6448; levyd@ornl.gov]

Image: https://www.ornl.gov/sites/default/files/Physics_silicon-detectors.jpg

Caption: Position-sensitive silicon detectors form the "nerves" of the Super Oak Ridge Rutgers University Barrel Array and yield high spatial resolution that enabled the Sn-132 experiment at ORNL--the first neutron-removal reaction on such a heavy, neutron-rich nucleus. The array, installed at Michigan State University, should begin operations in 2022. Credit: Steven Pain/Oak Ridge National Laboratory, U.S. Dept. of Energy

Grid--Balancing act

Oak Ridge National Laboratory scientists have devised a method to control the heating and cooling systems of a large network of buildings for power grid stability--all while ensuring the comfort of occupants. Buildings consume about 73 percent of the nation's electricity and about half of that is for heating, ventilation and air conditioning systems. Harnessing the HVAC-related demand of a fleet of buildings "can make a difference in frequency regulation," or what grid operators refer to as the balance between electricity supply and demand, said ORNL's Mohammed Olama. "We developed control schemes that don't require a large number of calculations and can be implemented easily on existing HVAC systems that have simple on-off controls." Simulations found that the controls are successful in providing frequency regulation from a fleet of 50 buildings, while keeping indoor temperatures within 0.5 degrees Celsius of a set range. The research is detailed in the journal Energies. [Contact: Stephanie Seay, (865) 576-9894; seaysg@ornl.gov]

Image: https://www.ornl.gov/sites/default/files/hvac_grid03.png

Caption: ORNL scientists have devised a control architecture for a fleet of HVAC units, which could allow utilities to harness the demand from a city's worth of buildings to help balance the power grid. The research is funded by DOE's Building Technologies Office. Credit: Andy Sproles/Oak Ridge National Laboratory, U.S. Dept. of Energy

Neutrons--Gentle strain

Scientists from AK Steel Corporation are using neutrons at Oak Ridge National Laboratory's Spallation Neutron Source to discover how different manufacturing processes will affect the performance of the company's new AHSS, or advanced high strength steel, called NEXMET 1000. Neutrons, unlike electrons or X-rays, are highly penetrating, non-destructive and sensitive to lighter elements, making them an ideal probe for this novel category of steel materials. "The VULCAN instrument at SNS provides information about the crystal structure of AHSS during different stages of the stamping process that we cannot get anywhere else in the United States," said Wei Wu of AK Steel. "This data will be vital to improving our manufacturing methods and will make it easier to quickly identify the best new materials to blend with NEXMET® 1000 to produce lighter, safer and more durable automotive components." [Contact: Kelley Smith, (865) 576-5668; smithks@ornl.gov]

Image: https://www.ornl.gov/sites/default/files/AK_Steel_story-tip.jpg

Caption: AK Steel Corporation scientist Wei Wu holds a sample of the company's new advanced high strength steel. Wu is using neutrons to study how the material is affected by various manufacturing processes to produce automotive components that improve fuel efficiency, last longer and are safer. Credit: Kelley Smith/Oak Ridge National Laboratory, U.S. Department of Energy

MIAMI--A new study led by researchers at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science found that a common coral species might have evolved unique immune strategies to cope with environmental change.

Roughly 30 percent of the cauliflower coral's (Pocillopora damicornis) genome was unique compared to several other reef-building corals. In this 30%, many of these genes were related to immune function. This diversity of genes related to immune function, the researchers say, may be important for the long-term survival of coral reefs as climate change and ocean acidification continue to alter the environment to which corals are adapted.

"This coral is traditionally thought of as a weed, and yet it may be one of the last corals to survive environmental changes such as climate change," said senior author of the study Nikki Traylor-Knowles, an assistant professor of marine biology and ecology at the UM Rosenstiel School.

To conduct the research, the scientists extracted and sequenced the genomic DNA from two healthy fragments and two bleached fragments of P. damicornis, which is one of the most abundant and widespread reef-building corals in the world. Their genome was then compared to publicly available genomes for several other coral species and several other cnidarian species.

"The study shows that this is an important coral with a very complex and unique immune system, which may explain why it is able to survive in so many different locations," said the paper's lead author Ross Cunning, who conducted the research as a postdoctoral scientist at the UM Rosenstiel School and is now a researcher at Shedd Aquarium.

These results suggest that the evolution of an innate immune system has been a defining feature of the success of hard corals like P. damicornis, and may help facilitate their continued success under climate change scenarios.

The immune system of corals, like humans, is vital to protect its overall health and deal with changes in its surroundings. If an animal has a stronger immune system then it will be better equipped to deal with environmental changes. These new findings suggest that some corals have many more and diverse immunity genes than would be expected, which is the hallmark of a very robust immune system.

"This study helps us better understand how corals deal with stress," said Traylor-Knowles. "Its complex immune system indicates that it may have the tools to deal with environmental change much more easily than other corals."

The study, titled "Comparative analysis of the Pocillopora damicornis genome highlights role of immune system in coral evolution," was published in the October 31, 2018 issue of the journal Scientific Reports. The paper's coauthors include: Nikki Traylor-Knowles, Andrew Baker, and Phil Gillette of the UM Rosenstiel School; UM alumnus Ross Cunning of Shedd Aquarium; and UM alumna Rachael Bay of the University of California Davis.

The day after Halloween, something scary may still lurk inside your showerhead. Researchers at CIRES have identified Mycobacterium as the most abundant genus of bacteria growing in the slimy "biofilm" that lines the inside of residential showerheads--and some of those bacteria can cause lung disease.

In a new study, they report that mycobacteria are more prevalent in the United States than in Europe, thrive more in municipal tap water than in well water, and are especially common in geographical "hot spots" where certain types of lung disease caused by mycobacteria are also common.

It's important to understand routes of mycobacterial exposure, especially in the household. We can learn a lot from studying the biofilm that accumulates inside your showerhead, and the associate water chemistry," said Matt Gebert, CIRES researcher and lead author of the new study published this week in the American Society for Microbiology's journal mBio. "There is a lot of interesting ecology at work, and it allows us to begin to understand how it can impact human health."

The research team, CIRES Fellow and Professor of Ecology and Evolutionary Biology at CU Boulder Noah Fierer's group, began this work in 2017, funded partially by an CIRES Innovative Research Program grant. The team analyzed DNA collected from 656 household showers in the United States and 13 countries in Europe. Citizen scientists swabbed the inside of their showerheads with specialized kits, and mailed the "biofilm" samples to Boulder.

By harnessing DNA sequencing technology, the researchers were able to identify which bacterial species that lived in showerhead slime, and how abundant they were. Mycobacteria were far more abundant in showerheads receiving municipal tap water than in those receiving well water, as well as more abundant in U.S. households versus European.

These patterns are probably driven in part by differences in the use of chlorine disinfectants, the team reported. Mycobacteria tend to be somewhat resistant to the chlorine-based disinfectants used more heavily in the United States than in Europe--so in Europe, other bacterial species may be better able to thrive and outcompete the disease-causing strains.

Showerhead materials seemed to matter, too, with more mycobacteria in metal showerheads than in plastic ones--plastic leaches some chemicals that support diverse bacterial communities, possibly preventing the mycobacteria from becoming too abundant.

When the researchers mapped out where potentially pathogenic mycobacteria thrived, the maps revealed "hot spots" that roughly match regions where a nontuberculous mycobacterial (NTM) lung disease is most prevalent--parts of Southern California, Florida, and New York, highlighting the potentially important role of these showerhead bacteria in disease transmission.

There is a fascinating microbial world thriving in your showerhead and you can be exposed every time you shower," Fierer said. "Most of those microbes are harmless, but a few are not, and this kind of research is helping us understand how our own actions--from the kinds of water treatment systems we use to the materials in our plumbing--can change the makeup of those microbial communities."

"In terms of what's next, we're hoping to begin to explore, beyond identification and abundance, what is causing this striking geographic variation within the genus Mycobacterium, and what is potentially driving these 'hot spots'," said Gebert.

"And don't worry," he added. "There is definitely no reason to fear showering."

Traveling with young children can be a challenge. As ride-share apps continue to surge in popularity, transporting children safely via these services has become a growing concern.

The average Uber or Lyft vehicle does not generally come equipped with a car seat, and only in certain cities is it an option to request one. Although parents can provide their own, many infant and convertible car seats are bulky, heavy, and require a separate base, making this an unwieldy option for vacations or extended travel.

With the goal of increasing child safety, researchers at the Virginia Tech Transportation Institute (VTTI) and Texas A&M Transportation Institute (TTI) have released a new study about child ridership and child safety seat use in ride-share vehicles. They have also published a corresponding website to help educate the public on various child restraint guidelines across the country.

"It can be a challenge to figure out what the rules are for transporting kids in a ride-share vehicle, as the laws vary from state to state. We hope this website will serve as a valuable reference that parents, ride-share drivers, and others can use to identify the child passenger regulations in their area and other states they may visit," said Justin Owens, a research scientist at VTTI and principal investigator on the project.

Owens and his colleagues analyzed child restraint laws nationwide in the initial phase of the study. According to their findings, 34 states, including Virginia, exempt taxis and for-hire vehicles from child restraint requirements. Whether these exemptions also apply to ride-share vehicles is often less clear, however. Currently, Georgia is the only state that distinguishes between ride-sharing and other for-hire vehicles in its legislation: for-hire vehicles are exempt, but ride-share drivers in Georgia are required to provide car seats if needed.

How are parents and ride-share drivers navigating this uncertain territory? To gauge this, the project team conducted both a series of focus groups in Texas with parents and ride-share drivers and a nationwide internet survey of parents of young children. The goal was to reveal the safety attitudes and practices of parents who use ride-share vehicles with their children, as well as any barriers that exist to appropriate child seat use.

While some findings diverged between the two methodologies, consistent trends emerged. These include:

More than a third of parents in the study utilized ride-share services with their children.

Up to half of parents reported not providing appropriate child safety seats while riding in an Uber, Lyft, or other ride-share vehicle with their families.

Three quarters of drivers in the focus groups had given rides to young children. Among these drivers, only half of them recounted car seat usage.

Overall, parents were interested in using child seats in ride-shares, but often felt deterred by the lack of car seat options and uncertainty surrounding the rules.

"These findings suggest that parents would like to be able to transport their children more safely when using ride-share vehicles, but there is a real need for user-friendly information about rules, regulations, and resources surrounding travel with children," said Owens. "For that reason, we have created a website, http://www.kidsridesafe.org, that aims to provide caregivers and ride-share drivers with this information in an easy-to-access manner."

Chestnut Hill, Mass. (10/31/2018) Two-dimensional magnetism has long intrigued and motivated researchers for its potential to unleash new states of matter and utility in nano-devices.

In part the excitement is driven by predictions that the magnetic moments of electrons - known as "spins" - would no longer be able to align in perfectly clean systems. This enhancement in the strengths of the excitations could unleash numerous new states of mater, and enable novel forms of quantum computing.

A key challenge has been the successful fabrication of perfectly clean systems and their incorporation with other materials. However, for more than a decade, materials known as "van der Waals" crystals, held together by friction, have been used to isolate single-atom-thick layers leading to numerous new physical effects and applications.

Recently this class has been expanded to include magnetic materials, and it may offer one of the most ambitious platforms yet in scientific efforts to investigate and manipulate phases of matter at the nanoscale, researchers from Boston College, the University of Tennessee, and Seoul National University, write in the latest edition of the journal Nature.

Two-dimensional magnetism, the subject of theoretical explorations and experimentation for the past 80 years, is enjoying a resurgence thanks to a group of materials and compounds that are relatively plentiful and easy to manipulate, according to Boston College Associate Professor of Physics Kenneth Burch, a first author of the article "'Magnetism in two-dimensional van der Waals materials."

The most oft-cited example of these materials is graphene, a crystal constructed in uniform, atom-thick layers. A procedure as simple as applying a piece of scotch tape to the crystal can remove a single layer, providing a thin, uniform section to serve as a platform to create novel materials with a range of physical properties open to manipulation.

"What's amazing about these 2-D materials is they're so flexible," said Burch. "Because they are so flexible, they give you this huge array of possibilities. You can make combinations you could not dream of before. You can just try them. You don't have to spend this huge amount of time and money and machinery trying to grow them. A student working with tape puts them together. That adds up to this exciting opportunity people dreamed of for a long time, to be able to engineer these new phases of matter."

At that single layer, researchers have focused on spin, what Burch refers to as the "magnetic moment" of an electron. While the charge of an electron can be used to send two signals - either "off" or "on", results represented as either zero or one - spin excitations offer multiple points of control and measurement, an exponential expansion of the potential to signal, store or transmit information in the tiniest of spaces.

"One of the big efforts now is to try to switch the way we do computations," said Burch. "Now we record whether the charge of the electron is there or it isn't. Since every electron has a magnetic moment, you can potentially store information using the relative directions of those moments, which is more like a compass with multiple points. You don't just get a one and a zero, you get all the values in between."

Potential applications lie in the areas of new "quantum" computers, sensing technologies, semiconductors, or high-temperature superconductors.

"The point of our perspective is that there has been a huge emphasis on devices and trying to pursue these 2-D materials to make these new devices, which is extremely promising," said Burch. "But what we point out is magnetic 2D atomic crystals can also realize the dream of engineering these new phases - superconducting, or magnetic or topological phases of matter, that is really the most exciting part. It is not just fundamentally interesting to realize these theorems that have been around for 40 years. These new phases would have applications in various forms of computing, whether in spintronics, producing high temperature superconductors, magnetic and optical sensors and in topological quantum computing."

Burch and his colleagues - the University of Tennessee's David Mandrus and Seoul National University's Je-Geun Park - outline four major directions for research into magnetic van der Waals materials:

Discovering new materials with specific functionality. New materials with isotropic or complex magnetic interactions, could play significant roles in the development of new supercondcutors.

These new materials can also lead to a deeper understanding of fundamental issues in condensed matter physics, serving as unique platforms for experimentation.

The materials will be tested for the potential to become unique devices, capable of delivering novel applications. The two-dimensional structure of these materials makes them more receptive to external signals.

These materials possess quantum and topological phases that could potentially lead to exotic states, such as quantum spin liquids, "skyrmions," or new iterations of superconductivity.

Germano Iannacchione, a National Science Foundation (NSF) program officer who oversees grants to Burch and other materials scientists, said the co-authors offer the broader community of scientists ideas that can serve to guide a dynamic field pushing beyond boundaries in materials research.

"Magnetism in 2D van Der Waals materials has grown into a vibrant field of study," said Iannacchione. "Its investigators have matured from highly focused researchers to statesmen shepherding a field, broadening applications into as many channels as possible. The review captures the multiplicative aspect of steady, focused, and sometimes risky research that opens vast new frontiers, with tremendous potential for applications in quantum computing and spintronics."

ITHACA, N.Y. - General-purpose robots have plenty of limitations. They can be expensive and cumbersome. They often accomplish only a single type of task.

But modular robots - composed of several interchangeable parts, or modules - are far more flexible. If one part breaks, it can be removed and replaced. Components can be rearranged as needed - or better yet, the robots can figure out how to reconfigure themselves, based on the tasks they're assigned and the environments they're navigating.

Now, a Cornell University-led team has developed modular robots that can perceive their surroundings, make decisions and autonomously assume different shapes in order to perform various tasks - an accomplishment that brings the vision of adaptive, multipurpose robots a step closer to reality.

"This is the first time modular robots have been demonstrated with autonomous reconfiguration and behavior that is perception-driven," said Hadas Kress-Gazit, associate professor of mechanical and aerospace engineering at Cornell and principal investigator on the project.

The results of this research were published in Science Robotics.

The robots are composed of wheeled, cube-shaped modules that can detach and reattach to form new shapes with different capabilities. The modules have magnets to attach to each other, and Wi-Fi to communicate with a centralized system.

Other modular robot systems have successfully performed specific tasks in controlled environments, but these robots are the first to demonstrate fully autonomous behavior and reconfigurations based on the task and an unfamiliar environment, Kress-Gazit said.

"I want to tell the robot what it should be doing, what its goals are, but not how it should be doing it," she said. "I don't actually prescribe, 'Move to the left, change your shape.' All these decisions are made autonomously by the robot."

(Millbrook, NY) Insect repellents containing picaridin can be lethal to salamanders. So reports a new study published today in Biology Letters that investigated how exposure to two common insect repellents influenced the survival of aquatic salamander and mosquito larvae.

Insect repellents are a defense against mosquito bites and mosquito-borne diseases like dengue, chikungunya, Zika, and West Nile virus. Salamanders provide natural mosquito control. During their aquatic juvenile phase, they forage on mosquito larvae, keeping populations of these nuisance insects in check.

Emma Rosi, a freshwater ecologist at Cary Institute of Ecosystem Studies and a co-author on the paper explains, "Use of insect repellents is on the rise globally. Chemicals in repellents enter aquatic ecosystems through sewage effluent and are now common in surface waters. We set out to understand the impact of repellent pollution on both larval mosquitoes and the larval salamanders that prey on them."

The paper is the first to suggest that environmentally realistic concentrations of picaridin-containing repellents in surface waters may increase the abundance of adult mosquitoes due to a decrease in predation pressure on mosquitoes at the larval stages.

Testing the two most popular repellents

The research team tested the effects of two of the most widely used insect repellents - DEET (Repel 100 Insect Repellent) and picaridin (Sawyer Premium Insect Repellent) - on larval salamanders and mosquitoes. In a lab, they exposed mosquito larvae and just-hatched spotted salamander larvae to three environmentally relevant concentrations of these chemicals, as well as a control treatment.

Rosi notes, "The concentrations in our experiments are conservative; we prepared them based on unadulterated commercial formulations, not concentrations of pure active compounds."

Mosquito larvae were not impacted by any of the treatments and matured unhindered. After four days of exposure to repellent with picaridin, salamanders in all of the treatment groups began to display signs of impaired development such as tail deformities. By day 25, 45-65% of picaridin-exposed salamander larvae died.

Co-author Barbara Han, a disease ecologist at Cary Institute explains, "Our findings demonstrate that larval salamanders suffer severe mortality and developmental deformities when exposed to environmentally relevant concentrations of commercially available repellent containing the active ingredient picaridin."

Adding, "The expediency of salamander mortality was disconcerting. When studying the effects of a chemical on an amphibian, we usually look for a suite of abnormalities. We couldn't collect these data because the salamanders died so quickly."

How toxic is toxic?

LC50 tests are used to define a chemical's environmental toxicity. These standard tests, based on one life stage of a single species, measure how long it takes for 50% of a test population to die with increasing exposure to a chemical in a lab over a four-day period.

Co-author Alexander Reisinger, an Assistant Professor at University of Florida, Gainesville
says, "We observed heavy salamander mortality with picaridin, but not until after the fourth day of exposure. By the LC50 measure, picaridin would be deemed 'safe', but clearly, this is not the case. If a substance doesn't kill organisms within the first few days of exposure, it can still be toxic and have ecological impacts."

Results may underestimate the problem

Lethal in a controlled setting, picaridin may cause greater mortality in a natural context, where organisms are exposed to numerous stressors. Rosi notes, "Animals don't exist in isolation. In nature, competition, predation, resource limitation, and social interactions make it difficult for an organism to tolerate the added stress of exposure to a harmful substance, even in small amounts."

Timing - of both repellent use and amphibian reproduction - is also key. Many amphibians breed in a single seasonal pulse, putting all their eggs in one basket, so to speak. Mosquitoes have an extended breeding season, and reproduce multiple times.

Lead author Rafael Almeida, a postdoctoral researcher at Cornell University, conducted the research as a visiting PhD student at the Cary Institute. He explains, "The amount of repellents entering waterways peaks seasonally. If amphibians are exposed during a sensitive life stage, entire cohorts could perish. The population would not have a chance to recover until the following year. Meanwhile, mosquitoes would continue to reproduce. It suggests a negative feedback loop."

Additional study

Future work is needed to explore the relationship among mosquito repellents, amphibians, and other ecological factors, and to better assess the severity of repellents' impact in the wild.

Almeida concludes, "The effects of repellents containing DEET and picaridin need to be studied further to determine the extent to which these chemicals disrupt aquatic ecosystems and potentially increase mosquito-borne disease risk worldwide."

In a newly published study, researchers dug into how fertilizing with manure affects soil quality, compared with inorganic fertilizer.

Ekrem Ozlu of the University of Wisconsin-Madison and his team studied two fields in South Dakota. From 2003 to 2015, the research team applied either manure or inorganic fertilizer to field plots growing corn and soybeans. They used low, medium, and high manure levels, and medium and high inorganic fertilizer levels. They also had a control treatment of no soil additives to provide a comparison.

In the summer of 2015, they collected soil samples at a variety of depths using a push probe auger. Then they analyzed the samples.

>>Manure helped keep soil pH--a measure of acidity or alkalinity--in a healthy range for crops. Inorganic fertilizer made the soil more acidic.

>>Manure increased soil organic carbon for all the measured soil depths compared to inorganic fertilizer and control treatments. More carbon means better soil structure.

>>Manure significantly increased total nitrogen compared to fertilizer treatments. Nitrogen is key to plant growth.

>>Manure increased water-stable aggregates. These are groups of soil particles that stick to each other. Increased water-stable aggregates help soil resist water erosion. Inorganic fertilizer application decreased these aggregates.

>>Manure increased soil electrical conductivity at all soil depths in comparison to inorganic fertilizer and control treatments. Higher soil electrical conductivity means higher salt levels in the soil.

Ozlu and his team concluded that long-term annual application of manure improved most soil quality properties compared to inorganic fertilizer. "Increased electrical conductivity is one of the few negative impacts of manure," Ozlu said.

The team also measured the effects of larger and smaller doses of each treatment at different soil depths. This will provide useful guidance to growers.

So, what could a backyard gardener learn from this study? Ozlu said, "I recommend gardeners use composted manure, especially in solid form, because manure is the fertilizer that supports better soil quality by improving almost all soil properties. Inorganic fertilizer is better in terms of electrical conductivity, but it does not improve other soil properties and crop yields better than manure."

Ozlu concluded, "If you think of soil as a heart, manure is the lifeblood going through it."

This is a poetic view of manure, to be sure. But perhaps this humble yet enormously useful substance deserves a little poetry.