Tech

In almost all situations, even in a vacuum, light cannot travel endlessly without dissipating. Pulses of light known as solitons that propagate along fibres for long distances without changing their shape or losing focus have found applications in data transmission, but even these gradually dissipate unless the medium they travel through has ultra-low absorbance. Nikolay Rosanov of the National Research University of Information Technologies, Mechanics, and Optics (ITMO), St. Petersburg, Russia and his team have been working on a solution to this problem - laser solitons - since the 1980s; a colloquium paper summarising their recent work in this area has now been published in EPJ D.

Rosanov and his group began their work with computer simulations, suggesting that it was theoretically possible to produce a stable soliton in a wide-aperture laser if it was stabilised by external radiation. This prediction was soon confirmed experimentally, and the group has studied these so-called dissipative solitons ever since.

Most recently, the researchers have demonstrated theoretically that it is possible to create such solitons without the use of coherent and stable external radiation. Using parallel programming on high-performance supercomputers, they first modelled a light pulse that is localised in one dimension (a 1D soliton) before extending their technique to model solitons in two and then three dimensions. These three-dimensional solitons have a complex internal structure with distinctive topologies; these have been given descriptive names such as 'apple', 'trefoil' and 'Solomon knot' and they have been shown to merge.

There are still questions for Rosanov and his colleagues to answer before their theory can be put into practice. Once it has been, however, the stability of these solitons and of their topology suggests potential applications in storing digital information. It is by no means impossible that we could, one day, use computers that have laser soliton arrays in place of today's hard disks.

While structures which emulate foam-like arrangements of bubbles are lightweight and cheap to build, they are also remarkably stable. The bubbles which cover the iconic Beijing Aquatics Centre, for example, each have the same volume, but are arranged in a way which minimises the total area of the structure - optimising the building's construction. The mathematics underlying this behaviour is now well understood, but if the areas of the bubbles are not equal, the situation becomes more complicated. Ultimately, this makes it harder to make general statements about how the total surface area or, in 2D, edge length, or 'perimeter', can be minimised to optimise structural stability. In new research published in EPJ E, Francis Headley and Simon Cox at Aberystwyth University in the UK explore how different numbers of 2D bubbles of two different areas can be arranged within circular discs, in ways which minimise their perimeters.

Using computer simulations of up to ten bubbles, the duo investigated how the shapes of the bubbles could be optimised, while obeying the mathematical laws for bubble formation. Their work could pave the way for new designs of complex foam-like structures which are both stronger and cheaper than previous designs. It could also provide new insights into the general physical laws which govern the optimal layouts of bubbles with differing areas. To arrive at these conclusions, Headley and Cox noted how complexity increases rapidly for larger numbers of total bubbles; while five bubbles can be arranged in 20 different ways, a total of 314,748 structures are possible for ten bubbles.

Headley and Cox calculated their optimal bubble arrangements using advanced software to find the lowest perimeter arrangement of bubbles for each area ratio. For each quantity of bubbles, they ultimately determined that the number of structures with the smallest perimeter for some range of area ratios increased as the number of bubbles increased, and hence that the range of area ratios which yields a particular bubble structure with the smallest perimeter became narrower.

Researchers at the Faculty of Physics at the University of Warsaw, Poland used liquid crystal elastomer technology to demonstrate a bio-inspired microrobot capable of mimicking the adhesive locomotion of snails and slugs in natural scale. The 10-millimeter long soft robot harvests energy from a laser beam and can crawl on horizontal surfaces, climb vertical walls and an upside-down glass ceiling.

Crawling by traveling deformation of a soft body is a widespread mode of locomotion - from microscopic nematodes to earthworms to gastropods - animals across scales use it to move around different, often challenging environments. Snails, in particular, use mucus - a slippery, aqueous secretion - to control the interaction between their ventral foot and the surface. Their adhesive locomotion has some unique properties: it can be used on different surfaces, including wood, metal, glass, teflon (PTFE) or sand in various configuration, including crawling upside-down. For robotics, low complexity of a single continuous foot could offer resistance to adverse external conditions and wear and tear, while the constant contact with the ground may provide high margins of failure resistance. Adhesive locomotion in robots have been limited so far to externally powered, centimeter-scale demonstrators with electro-mechanical drives.

Liquid Crystalline Elastomers (LCEs) are smart materials that can exhibit macroscopic, fast, reversible shape change under different stimuli, including illumination with visible light. They can be fabricated in various forms in the micro- and millimeter scales and, by the molecular orientation engineering, can perform complex modes of actuation.

Researcher from the University of Warsaw with colleagues from the Department of Mathematical Sciences at Xi'an Jiaotong-Liverpool University in Suzhou, China have now developed a natural-scale soft snail robot based on the opto-mechanical response of a liquid crystalline elastomer continuous actuator. The robot propulsion is driven by light-induced traveling deformations of the soft body and their interaction with the artificial mucus layer (glycerin). The robot can crawl at the speed of a few millimeters per minute, about 50 times slower than snails of comparable size, also up a vertical wall, on a glass ceiling and across obstacles.

Despite the slow speed, need of constant lubrication and low energy efficiency, our elastomer soft robot offers unique insights into micromechanics with smart materials and may also provide a convenient platform for studying adhesive locomotion - says Piotr Wasylczyk, head of the Photonic Nanostructure Facility at the Faculty of Physics of the University of Warsaw, Poland, who led the study.

Researchers, who have already demonstrated a natural-scale light-power caterpillar robot, believe that new generation of smart materials, together with novel fabrication techniques will soon allow them to explore more areas of small-scale soft robotics and micro-mechanics.

The research on soft micro-robots and polymer actuators are funded by the National Science Center (Poland) within the project "Micro-scale actuators based on photo-responsive polymers" and by the Polish Ministry of Science and Higher Education with "Diamentowy Grant" awarded to M. Rogoz.

Worcester, Mass. - July 31, 2019 - Researchers at Worcester Polytechnic Institute (WPI) have developed a chip made of carbon nanotubes that can capture circulating tumor cells (CTCs) of all sizes and types, and can do so with far greater sensitivity than existing technologies. The unique design of the device makes it possible to easily identify and even culture the captured cells, which could make it possible to detect early-stage tumors, predict the course of a cancer, and monitor the effects of therapy.

Details of the new technology are reported in the journal Lab on a Chip (Liquid biopsy using the nanotube-CTC-chip: capture of invasive CTCs with high purity using preferential adherence in breast cancer patients) by a team consisting of researchers at WPI, the Department of Neurological Surgery at the University of Massachusetts Medical School, and the James Graham Brown Cancer Center at the University of Louisville School of Medicine. Balaji Panchapakesan, professor of mechanical engineering at WPI, is the project lead.

High cancer mortality rates are largely attributable to tumors developing undetected until they reach advanced or inoperable stages, and to metastasis (when tumor cells travel through the bloodstream and initiate new tumors in other organs). Scientists have long sought a method that can reliably snare tumor cells as they travel through the bloodstream. Such technology could make it possible to detect cancers at very early stages, when treatment is more likely to be successful, and to spot the genetic changes that tumor cells undergo when a cancer is beginning to metastasize.

"Isolating CTCs with high purity is a significant challenge, akin to finding a needle in a haystack," Panchapakesan said. "These cells comprise as few as one to 10 cells among a billion blood cells, and the shedding of CTCs from tumors is a highly discontinuous process."

A number of research labs and companies have created so-called liquid biopsy devices, but the devices currently available have important limitations, Panchapakesan said. These include low sensitivity; the inability to trap CTCs of all sizes and types, or to capture clusters of CTCs along with individual cells; difficulty in retrieving captured cells from the devices for laboratory analysis; and high manufacturing costs. In addition, contamination of captured CTCs by white blood cells, which are similar in size to and can be mistaken for CTCs, is a problem for many liquid biopsy devices.

The device developed by Panchapakesan's team, described in the Lab on a Chip paper, has none of these limitations. The centerpiece of the device is a layer of carbon nanotubes that lines the bottom of a small well formed in a silicon/glass wafer. Panchapakesan says the chip design takes advantage of a natural tendency of CTCs to attach. "In order to travel to a distant site in the body and start a new tumor," he said, "CTCs need the ability to attach in an environment that is not conducive to attachment. In previous research, we have shown that they will attach preferentially to carbon nanotubes, but that white blood cells will not, by and large."

In addition, recent studies have shown that CTCs are far more fragile than previously believed and are subject to the environmental and mechanical stresses inherent in the blood stream. "These cells won't survive unless you give them a rocklike matrix to attach to--a softer matrix requires too much energy from the cell," Panchapakesan said.

"It's a medical problem at the intersection of mechanical engineering and biology," he said. "An understanding of the biology of cancer cells and how CTCs behave enabled us to design a mechanical engineering-based device."

The fact that white blood cells do not adhere to the nanotubes makes it possible to remove them from the chip, leaving the CTCs behind to be counted and identified. Red blood cells, which vastly outnumber the circulating tumor cells, also pose a problem. Since they tend to settle to the bottom of the chip, they could prevent CTCs from adhering to the nanotubes. The research team addressed this problem by lysing, or breaking up, the red blood cells before adding a blood sample to the chip. They found that the lysing process has no effect on the CTCs.

Tests of the chip using blood spiked with a known number of cancer cells tagged with fluorescent dye showed that it has a high sensitivity, with between 89 and 100 percent of cells in the test samples being captured. (The sensitivity of the chip increased the longer the blood remained in contact with the nanotubes.) Tests were also run with blood samples from actual breast cancer patients (stages 1-4) and yielded 100 percent sensitivity for detecting CTCs. CTCs were captured from all seven patient samples, while no tumor cells were captured from the samples from two healthy patients.

What's more, the chip captured individual CTCs exhibiting multiple phenotypes from early- and late-stage cancer patients, another potential advantage of the device. While other methods used to capture cells in other devices exhibit biases that prevent them from capturing the full range of cancer cell phenotypes, the WPI carbon nanotube chip appears to have the potential to do so.

"These initial clinical studies," Panchapakesan said, "in which we were able to capture and identify individual CTCs of varying phenotypes, show that this device could become an important tool not only for tracking the progression of cancers and their response to radiation or chemotherapy, but also in making predictions about the likely course of the cancer, which could help physicians identity the most effective course of therapy."

The tests also showed that the carbon nanotube chip can capture cells regardless of their size and can also capture clusters of CTCs in addition to individual cells. (CTC clusters are rare, but they appear to have a greater ability to seed new tumors than individual CTCs.) Because the cells settle gently onto the nanotubes and latch on with tendrils that extend from the cell body, they are not damaged.

And while captured cells must be removed from other devices for analysis, which can be difficult with devices that use narrow microfluidic channels and often results in damage to the cells, the cells captured by the carbon nanotube chip remain viable and can even be cultured. In addition, because the chips are transparent, it is possible to stain and study captured cells without removing them.

The chip described in the Lab on a Chip paper is the latest generation of a liquid biopsy chip that has been under development for several years in Panchapakesan's Small Systems Laboratory at WPI in collaboration with the University of Massachusetts Medical School and the University of Louisville.

The chips are made with materials and batch fabrication techniques similar to those used to make semiconductors. The current generation is a 76-element array of test wells on a glass and silicon wafer. In addition to making mass production possible, the multi-well design makes it easy to split a blood sample among multiple wells. The small volume of blood placed in each well makes it possible to more accurately count the attached CTCs.

Panchapakesan said he believes the latest generation of carbon nanotube liquid biopsy chip is ready for clinical trials. Toward that end, he is working with StrandSmart Inc., a Silicon-Valley start-up led by CEO Adrianna Davies. The team envisions testing a point of care (POC) device to detect cancer in the earliest stages globally.

"This potentially life-saving technology could have multiple beneficial applications," Panchapakesan said. "It could help shed light on the complex biological and genetic processes at play in cancer. It could detect cancers at a very early stage by capturing the cells that nascent tumors shed into the blood. It could identify CTCs with metastatic potential before new tumors even begins, and it could help shape treatments customized to each person's cancer."

The discovery that an essential protein plays a protective role during cell division, could open the door to better targeted treatment of fast-growing cancer cells.

Polo-like kinase (PLK1) was previously thought to have a major function - helping chromosome alignment during mitosis for cell division.

But scientists at the Genome Damage and Stability Centre (GDSC) at the University of Sussex, have found that it also plays a crucial protective role, guarding against severe DNA damage caused during mitosis in cultured human cells.

It casts doubts over theories that by inhibiting PLK1, fast-growing cancerous cells could be stopped from dividing and replicating, suggesting that this technique needs further research to avoid damaging side effects.

Dr Kok-Lung Chan, Wellcome Trust and Royal Society Sir Henry Dale Fellow at the GDSC said: "Up until now, scientists thought that one of the key roles of PLK1 was to help chromosomes to be stably captured for partition during mitosis.

"So it was thought that if that protein was inhibited or lacking, the duplicated chromosomes couldn't be grasped properly and, in the case of cancerous cells, wouldn't be able to segregate equally.

"We've discovered that PLK1 actually has a crucial protective role and is needed to avoid ruptures and splits of chromosomes, of which inhibition could have dangerous side effects on otherwise healthy growing cells."

The new findings, published in Nature Communications, suggest that any interference with the function of this essential protein could remove a protective barrier, resulting in specific DNA damage and chromosome rearrangements.

Dr Chan said: "For the first time, we have found that PLK1 works to maintain the rigidity of a critical part of the chromosome called the centromere.

"When the protein is lacking, centromeres become very fragile and rupture during cell division, causing 'whole chromosome arm splitting'.

"Effectively, this means that, when they divide, chromosome arms are split in the wrong place. In principle, they can rearrange themselves resulting in characteristic whole-arm rearrangements, which are commonly observed in cancers and were also reported in some genetic disorders like Downs Syndrome."

Interestingly, Dr Chan believes that the identification of the new role played by PLK1 could help clinicians develop cancer treatments which better target fast growing cells by not just blocking their division but also by simultaneously damaging their chromosome integrity.

Dr Chan explained: "Further investigation on this new function might actually help us to understand how the PLK1 inhibitors kill cancerous cells and could potentially improve future cancer therapies."

CLEVELAND, Ohio (July 31, 2019)--Diabetes is a global health concern expected to affect 693 million people worldwide by 2045. It's been well documented how diet and exercise influence risk of type 2 diabetes; however, a new study suggests that early menarche also is associated with a higher risk, but body mass index (BMI) may mediate this association. Study results are published online today in Menopause, the journal of The North American Menopause Society (NAMS).

Type 2 diabetes mellitus has become one of the most common diseases worldwide. In 2015, it affected nearly 8.8% of people aged 20 to 79 globally, and by 2040, it is expected to affect 10.4%. With so many people affected, it is not surprising how much research has been devoted to identifying determinants of the disease in order to prevent its development. Various lifestyle and environmental factors have already been confirmed, but there is also growing evidence pointing to some physiologic factors.

A new study analyzing more than 15,000 postmenopausal women in China has found that women who begin menstruating at an earlier age have a higher risk of developing type 2 diabetes. More specifically, each year of delay in menarche age correlated with a 6% lower risk of type 2 diabetes.

Although this is not the first study to suggest the association between menarche and diabetes, it provides added evidence regarding the increased risk, as well as the fact that BMI can partially mediate the association and the proportion of that effect is 28%.

Study results appear in the article "Early menarche is associated with an increased risk of type 2 diabetes in rural Chinese women and is partially mediated by BMI: the Henan Rural Cohort Study."

"This study of rural Chinese women indicates that the average age of menarche is delayed relative to western countries at 16.1 years and is linked with lower risk of type 2 diabetes. Earlier onset of menses (14 y) was associated with diabetes in later life, likely driven by adult BMI. Other factors such as nutrition and BMI in childhood may also play a role in this association," says Dr. Stephanie Faubion, NAMS medical director.

Just as we blend, cut, and fold ingredients together to follow a recipe, farmers use equipment to stir together soil and crop residue (stalks and roots of previous crops) before planting. This mechanical action is called tillage.

Similar to our kitchen cupboard with a blender, mixer, and beater, farmers have access to a variety of tillage equipment. Farmers choose the "right" piece of tillage based on many factors, including location, soil type, crop, and landscape.

Tillage has been around for thousands of years. "It is difficult for nearly anyone to grow a crop, or even a garden, without unconsciously going through the motions of tillage," says Aaron Daigh. "I see it as a near equivalent to muscle memory or a natural reflex." Daigh is a researcher and professor at North Dakota State University.

Modern conservation tillage practices protect the soil and environment. For example, they can reduce erosion from water or wind and keep nutrients in the right place.

Farmers are showing more and more interest in adapting conservation practices on their operations. But, adopting a new tillage system can be intimidating due to many real and perceived concerns. For example, some farmers presume conservation tillage will lead to lower yields and an increased risk for seedling diseases.

Scientists are making it easier for farmers in the Midwest to make the right tillage decisions when considering modern conservation practices. Daigh and his team compared the effects of three common conservation tillage systems to the traditional method of a chisel plow with field cultivation:

Shallow vertical till

Strip till using shanks

Strip till using coulters

After four years, researchers observed that yields rarely, if ever, differed among the four tillage systems at any of the farms. Still, change is never easy. The study by Daigh and his team suggests that adapting conservation tillage practices will not cause yield losses. In fact, conservation tillage practices will lower on-farm costs while preserving long-term productivity.

"These results may ease farmers' concerns about switching to conservation tillage," says Daigh. "Perhaps more farmers will consider if conservation tillage practices are a good fit for their operations."

"I encourage farmers who are interested, but hesitant, to try conservation tillage practices on one field to get more accustomed to the new system," he says. "Then, try it out on more fields until you get your farm designed to meet your needs and goals."

As always, the whole picture should be evaluated before making on-farm decisions. "It's not just about yield," says Daigh. "Economics and crop-residue for erosion protection should also guide farmer decisions."

The research team continues to investigate. "We are currently looking at the incorporation of cover crops into reduced tillage practices," says Daigh.

This study focused on farms with one type of tillage used per field. However, newer equipment allows for variable tillage methods at once. For example, it may be capable of vertical tillage and strip tillage at the same time. In the future, Daigh and his colleagues would like to see researchers evaluate the effects of these new technologies.

Read more about this work in Agricultural & Environmental Letters. This research was partially funded by the North Dakota Soybean and Corn Councils, Minnesota Soybean and Corn Research and Promotion Councils, North Dakota Agricultural Experiment Station, University of Minnesota Extension, North Dakota Extension, USDA-NRCS Conservation Innovation Grant 69-3A75-17-282, and USDA-NIFA Hatch project 1005366.

Since 1995, parents in many Organisation for Economic Cooperation and Development countries and in the United States have been having their first babies at a later age. Amid this trend in delayed childbearing, a new Dutch study considered the behavior problems of children born to older parents. Specifically, researchers looked at externalizing behaviors (e.g., aggression) and internalizing behaviors (e.g., anxiety, depression) of children born to older parents when the youth were 10 to 12 years old. They found that children of older parents tend to have fewer externalizing behavior problems than children of younger parents. The researchers also found that parents' age was unrelated to children's internalizing behaviors.

The study was done by researchers at Utrecht University, Vrije Universiteit Amsterdam, Erasmus Medical Center, and University Medical Center Groningen. It appears in Child Development, a journal of the Society for Research in Child Development.

"Evidence points to an association between fathers' age and autism spectrum disorders and schizophrenia, so we wanted to know if there is an association in the general population between parents' age and common behavior problems in children, beyond the clinical diagnoses," says Marielle Zondervan-Zwijnenburg, a postdoctoral researcher in methodology and statistics at Utrecht University, who led the study. "With respect to common behavior problems, we found no reason for future parents to worry about a harmful effect of having a child at an older age."

Researchers analyzed the problem behavior of 32,892 Dutch children when they were 10 to 12 years old. Problem behavior was rated by fathers, mothers, teachers, and the children themselves through a series of standardized instruments.

The children, all of whom were born after 1980, were part of four studies--Generation R, the Netherlands Twin Register, the Research on Adolescent Development and Relationships-Young Cohort (RADAR-Y), and the Tracking Adolescents' Individual Lives Survey. The children represented the entire Dutch geographic region across all strata of society and a range of socioeconomic statuses.

In the Generation R study, mothers' age at child's birth ranged from 16 to 46 and fathers' age at child's birth ranged from 17 to 68. In the Netherlands Twin Register, mothers' age at child's birth ranged from 17 to 47 and fathers' from 18 to 63. In the RADAR-Y study, mothers' age at child's birth ranged from 17 to 48 and fathers' from 20 to 52. And in the Tracking Adolescents' Individual Lives Survey, mothers' age at child's birth ranged from 16 to 44 and fathers' from 18 to 52.

The study found that the children of older parents had fewer externalizing behavior problems, as reported by the parents. The findings of fewer externalizing behavior problems persisted--as reported by parents and teachers--even after considering the families' socioeconomic status, so the researchers concluded that the favorable effect of parents' age on children's behavior was not solely due to their income level. The study also found that parents' age appeared unrelated to children's internalizing behavior problems.

The study's authors note that they focused only on children's externalizing and internalizing behavior problems, so the findings cannot be generalized to other behaviors--though they are extending their research to cognition and attention problems. In addition, the researchers assessed children's behavior problems during early adolescence; they plan to extend their work to other points in development.

"It's possible that some of the reason why older parents have children with fewer problems like aggression is that older parents have more resources and higher levels of education," explains Dorret Boomsma, professor of biological psychology and behavior genetics at Vrije Universiteit Amsterdam, who coauthored the study. "But it is important to note that the higher average educational level of older parents does not completely explain the decreased levels of externalizing problems in their children."

More than one million plant and animal species worldwide are facing extinction, according to a recent United Nations report. Now, a new UBC-led study suggests that Indigenous-managed lands may play a critical role in helping species survive.

The researchers analyzed land and species data from Australia, Brazil and Canada - three of the world's biggest countries - and found that the total numbers of birds, mammals, amphibians and reptiles were the highest on lands managed or co-managed by Indigenous communities.

Protected areas like parks and wildlife reserves had the second highest levels of biodiversity, followed by randomly selected areas that were not protected.

The study, which focused on 15,621 geographical areas in Canada, Brazil and Australia, also found that the size of an area and its geographical location did not affect species diversity.

"This suggests that it's the land-management practices of many Indigenous communities that are keeping species numbers high," said lead author Richard Schuster, the Liber Ero Postdoctoral Fellow at Carleton University, who undertook the research while at UBC. "Going forward, collaborating with Indigenous land stewards will likely be essential in ensuring that species survive and thrive."

The study is the first to compare biodiversity and land management on such a broad geographic scale, the researchers say.

"We looked at three countries with very different climates and species, to see if the pattern held true across these different regions--and it did," said co-author Ryan Germain, a postdoctoral fellow at Cornell University. "From frogs and songbirds right up to large mammals like grizzly bears, jaguars and kangaroos, biodiversity was richest in Indigenous-managed lands."

Traditional conservation programs relied on designating certain areas as parks and reserves, and these results highlight the importance of expanding conservation beyond its typical boundaries, says the study's senior author, UBC forestry professor Peter Arcese.

"Protected areas are a cornerstone of biodiversity conservation globally, but current levels of protection will be insufficient to halt the planetary extinction crisis," said Arcese, the Forest Renewal B.C. Chair in Conservation Biology at UBC. "We must manage a larger fraction of world's area in ways that protect species and leads to positive outcomes for people and the species they've relied on for millennia."

The researchers noted that in the past, when protected areas were established, Indigenous peoples were sometimes excluded from using land they had previously relied on for food and materials. This was harmful to many Indigenous communities and did not necessarily achieve the original goals of conservation.

"Indigenous-managed lands represent an important repository of biodiversity in three of the largest countries on Earth, and Indigenous peoples currently manage or have tenure to roughly one-quarter of the planet's land area," said co-author Nick Reo, an associate professor of environmental studies and Native American studies at Dartmouth College and a citizen of the Sault Ste. Marie, Ontario tribe of Chippewa Indians.

"In light of this, collaborating with Indigenous governments, communities and organizations can help to conserve biodiversity as well as support Indigenous rights to land, sustainable resource use and well-being."

James Cook University scientists in Australia are using 3D printing to create fuels for rockets, and using tailor-made rocket motors they've built to test the fuels.

JCU lecturer in mechanical engineering Dr Elsa Antunes led the study, which made use of the revolutionary and rapidly advancing 3D printing technology.

The JCU scientists 3D printed fuel grains (solid, plastic-based fuel) for the hybrid rockets using plastics and other materials.

"We wanted to explore the viability of using commercially available 3D printing materials in the manufacture of hybrid rocket fuel grains. We knew that the common plastic Acrylonitrile Butadiene Styrene (ABS) has shown promise so we decided to test that against six other compounds," she said.

Dr Antunes said the use of hybrid fuelled rockets has become almost commonplace. These types of rockets are safer and easier to control than conventional rockets.

"3D printing has meant designers have been able to make more complex geometries for rockets and has also opened up the possibility of using novel fuels to power them," she said.

"The last decade has seen an almost exponential increase in the number of rocket launches for sub-orbital scientific missions or for delivering payloads into low Earth orbits. There are many new investors and there is an increased demand for satellites."

The scientists 3D printed the rocket and then made a test rig for it at JCU's Townsville campus. They tested the fuel grain recipes in three second burns of the motor, before dissecting the fuel cells to further analyse their performance.

"We were disappointed with the polylactic acid and aluminium composite, we think it is largely due to the size, shape and surface area of the aluminium particles - but that's another thing that we can explore in the near future while taking advantage of modern manufacturing techniques," said Dr Antunes.

She said the experiment design was relatively simple, as the main objective was to select the best 3D printed fuel grains for a large-scale test, as a first step toward a large-scale engine firing campaign and testing of innovative materials.

"There are many new avenues opening up for people working in the field. With new manufacturing techniques such as 3D printing we are able to do things that were just impossible in the past," she said.

Working with mouse and human tissue, Johns Hopkins Medicine researchers report new evidence that a protein pumped out of some -- but not all -- populations of "helper" cells in the brain, called astrocytes, plays a specific role in directing the formation of connections among neurons needed for learning and forming new memories.

Using mice genetically engineered and bred with fewer such connections, the researchers conducted proof-of-concept experiments that show they could deliver corrective proteins via nanoparticles to replace the missing protein needed for "road repairs" on the defective neural highway.

Since such connective networks are lost or damaged by neurodegenerative diseases such as Alzheimer's or certain types of intellectual disability, such as Norrie disease, the researchers say their findings advance efforts to regrow and repair the networks and potentially restore normal brain function.

The findings are described in the May issue of Nature Neuroscience.

"We are looking at the fundamental biology of how astrocytes function, but perhaps have discovered a new target for someday intervening in neurodegenerative diseases with novel therapeutics," says Jeffrey Rothstein, M.D., Ph.D., the John W. Griffin Director of the Brain Science Institute and professor of neurology at the Johns Hopkins University School of Medicine.

"Although astrocytes appear to all look alike in the brain, we had an inkling that they might have specialized roles in the brain due to regional differences in the brain's function and because of observed changes in certain diseases," says Rothstein. "The hope is that learning to harness the individual differences in these distinct populations of astrocytes may allow us to direct brain development or even reverse the effects of certain brain conditions, and our current studies have advanced that hope."

In the brain, astrocytes are the support cells that act as guides to direct new cells, promote chemical signaling, and clean up byproducts of brain cell metabolism.

Rothstein's team focused on a particular astrocyte protein, glutamate transporter-1, which previous studies suggested was lost from astrocytes in certain parts of brains with neurodegenerative diseases. Like a biological vacuum cleaner, the protein normally sucks up the chemical "messenger" glutamate from the spaces between neurons after a message is sent to another cell, a step required to end the transmission and prevent toxic levels of glutamate from building up.

When these glutamate transporters disappear from certain parts of the brain -- such as the motor cortex and spinal cord in people with amyotrophic lateral sclerosis (ALS) -- glutamate hangs around much too long, sending messages that overexcite and kill the cells.

To figure out how the brain decides which cells need the glutamate transporters, Rothstein and colleagues focused on the region of DNA in front of the gene that typically controls the on-off switch needed to manufacture the protein. They genetically engineered mice to glow red in every cell where the gene is activated.

Normally, the glutamate transporter is turned on in all astrocytes. But, by using between 1,000- and 7,000-bit segments of DNA code from the on-off switch for glutamate, all the cells in the brain glowed red, including the neurons. It wasn't until the researchers tried the largest sequence of an 8,300-bit DNA code from this location that the researchers began to see some selection in red cells. These red cells were all astrocytes but only in certain layers of the brain's cortex in mice.

Because they could identify these "8.3 red astrocytes," the researchers thought they might have a specific function different than other astrocytes in the brain. To find out more precisely what these 8.3 red astrocytes do in the brain, the researchers used a cell-sorting machine to separate the red astrocytes from the uncolored ones in mouse brain cortical tissue, and then identified which genes were turned on to much higher than usual levels in the red compared to the uncolored cell populations. The researchers found that the 8.3 red astrocytes turn on high levels of a gene that codes for a different protein known as Norrin.

Rothstein's team took neurons from normal mouse brains, treated them with Norrin, and found that those neurons grew more of the "branches" -- or extensions -- used to transmit chemical messages among brain cells. Then, Rothstein says, the researchers looked at the brains of mice engineered to lack Norrin, and saw that these neurons had fewer branches than in healthy mice that made Norrin.

In another set of experiments, the research team took the DNA code for Norrin plus the 8,300 "location" DNA and assembled them into deliverable nanoparticles. When they injected the Norrin nanoparticles into the brains of mice engineered without Norrin, the neurons in these mice began to quickly grow many more branches, a process suggesting repair to neural networks. They repeated these experiments with human neurons too.

Rothstein notes that mutations in the Norrin protein that reduce levels of the protein in people cause Norrie disease -- a rare, genetic disorder that can lead to blindness in infancy and intellectual disability. Because the researchers were able to grow new branches for communication, they believe it may one day be possible to use Norrin to treat some types of intellectual disabilities such as Norrie disease.

For their next steps, the researchers are investigating if Norrin can repair connections in the brains of animal models with neurodegenerative diseases, and in preparation for potential success, Miller and Rothstein have submitted a patent for Norrin.

Philadelphia, July 30, 2019 - The propensity to overeat may, in part, be a function of the satisfaction derived from eating. A new study in the Journal of the Academy of Nutrition and Dietetics, published by Elsevier, found no significant difference in taste perceptions between participants of normal weight and those who were overweight. However, participants with obesity had initial taste perceptions that were greater than participants who were not obese, which declined at a more gradual rate than participants who were not obese. This quantification of satisfaction from food may help explain why some people eat more than others.

"Obesity is a major public-health problem. Thirty percent of the US population is obese, and obesity-related health problems (diabetes, hypertension, etc.) are increasing. Causes of obesity are varied, but food consumption decisions play an important role, especially decisions about what foods to eat and how much to consume. Taste perceptions may lead to overeating. If people with obesity have different taste perceptions than nonobese people, it could lead to better understanding of obesity and possibly designing new approaches to prevent obesity," explained lead investigator Linnea A. Polgreen, PhD, Department of Pharmacy Practice and Science, University of Iowa, Iowa City, IA, USA.

As individuals consume more of a food item, they experience diminishing marginal taste perception, which means their level of perceived taste from additional consumption may tend to decline (ie, additional consumption may become less pleasurable). The relationship between perceived taste and quantity consumed has traditionally been referred to as sensory-specific satiety.

In order to determine if marginal taste perceptions differ among participants of normal-weight, those who are overweight and those with obesity, and whether knowledge of nutritional information affects marginal taste perception, researchers at the University of Iowa conducted a non-clinical, randomized controlled trial of 290 adults (161 with normal BMI, 78 considered overweight, and 51 considered obese) to measure instantaneous taste perceptions. Eighty percent of the participants were female, and ages ranged from 18 to 75 years. Participants were offered and rated one piece of chocolate at a time in a controlled environment and could eat as much as they wanted without feeling uncomfortable. They consumed between two and 51 pieces. Half of the study participants received nutritional information about the chocolate before the chocolate tasting began.

The study identified a consistent association between taste from food, specifically chocolate, and BMI by directly observing instantaneous taste changes over a period of time, rather than just at the beginning and end of a period of consumption, as in prior studies.

Typically, the appeal of a specific food may decline as more of that food is eaten: the first bite of chocolate is better than the 10th, a phenomenon consistent with the concept of sensory-specific satiety. As anticipated, researchers found that ratings generally went down after each piece of chocolate consumed with no significant difference in taste perceptions between normal and overweight participants reported. However, participants with obesity had higher levels of initial taste perception, rated subsequent pieces higher than their counterparts without obesity, and their ratings declined at a more gradual rate compared to participants with normal weight and those with obesity. People hungrier prior to the study had greater taste perception; women's taste perceptions declined faster than men's; and providing nutritional information prior to chocolate consumption did not affect taste perception.

"In our study population, people with obesity reported a higher level of satisfaction for each additional piece of chocolate compared to nonobese people. Thus, their taste preferences appear markedly different," noted co-investigator Aaron C. Miller, PhD, Department of Epidemiology, University of Iowa, Iowa City, IA, USA. "Our findings further indicate that obese participants needed to consume a greater quantity of chocolate than nonobese participants to experience a similar decline in taste perceptions. Specifically, obese women needed to eat 12.5 pieces of chocolate to fall to the same level of taste perception as nonobese women who ate only 10 pieces, which corresponds to a difference of 67.5 calories. This may, in part, explain why obese people consume more than nonobese people."

'Tickling' the ear with a small electrical current appears to rebalance the autonomic nervous system for over-55s, potentially slowing down one of the effects of ageing, according to new research.

Scientists found that a short daily therapy delivered for two weeks led to both physiological and wellbeing improvements, including a better quality of life, mood and sleep.

The therapy, called transcutaneous vagus nerve stimulation, delivers a small, painless electrical current to the ear, which sends signals to the body's nervous system through the vagus nerve.

The new research, conducted at the University of Leeds, suggests the therapy may slow down an important effect associated with ageing.

This could help protect people from chronic diseases which we become more prone to as we get older, such as high blood pressure, heart disease and atrial fibrillation. The researchers, who published their findings today in the journal Aging, suggest that the 'tickle' therapy has the potential to help people age more healthily, by recalibrating the body's internal control system.

Lead author Dr Beatrice Bretherton, from the School of Biomedical Sciences at the University of Leeds, said: "The ear is like a gateway through which we can tinker with the body's metabolic balance, without the need for medication or invasive procedures. We believe these results are just the tip of the iceberg.

"We are excited to investigate further into the effects and potential long-term benefits of daily ear stimulation, as we have seen a great response to the treatment so far."

The study was conducted by scientists from the University of Leeds and funded by the Dunhill Medical Trust.

What is the autonomic nervous system?

The autonomic nervous system controls many of the body's functions which don't require conscious thought, such as digestion, breathing, heart rate and blood pressure.

It contains two branches, the sympathetic and the parasympathetic, which work against each other to maintain a healthy balance of activity.

The sympathetic branch helps the body prepare for high intensity 'fight or flight' activity, whilst the parasympathetic is crucial to low intensity 'rest and digest' activity.

As we age, and when we are fighting diseases, the body's balance changes such that the sympathetic branch begins to dominate. This imbalance makes us more susceptible to new diseases and leads to the breakdown of healthy bodily function as we get older.

Clinicians have long been interested in the potential for using electrical currents to influence the nervous system. The vagus nerve, the major nerve of the parasympathetic system, has often been used for electrical stimulation and past research has looked at the possibility of using vagus nerve stimulation to tackle depression, epilepsy, obesity, stroke, tinnitus and heart conditions.

However, this kind of stimulation needs surgery to implant electrodes in the neck region, with associated expense and a small risks of side effects.

Fortunately, there is one small branch of the vagus nerve that can be stimulated without surgery, located in the skin of specific parts of the outer ear.

In Leeds, previous research has shown that applying a small electrical stimulus to the vagus nerve at the ear, which some people perceive as a tickling sensation, improves the balance of the autonomic nervous system in healthy 30-year-olds.

Other researchers worldwide are now investigating if this transcutaneous vagus nerve stimulation (tVNS) could provide a therapy for conditions ranging from heart problems to mental health.

Diane Crossley, aged 70, from Leeds, took part in the study and received the tVNS therapy for two weeks. She said: "I was happy to be a participant in this really interesting study, it helped me with my awareness of my own health.

"It was a fascinating project and I was proud to be part of it."

In their new study, scientists at the University of Leeds wanted to see whether tVNS could benefit over 55-year-olds, who are more likely to have out-of-balance autonomic systems that could contribute to health issues associated with ageing.

They recruited 29 healthy volunteers, aged 55 or above, and gave each of them the tVNS therapy for 15 minutes per day, over a two week period. Participants were taught to self-administer the therapy at home during the study.

The therapy led to an increase in parasympathetic activity and a decrease in sympathetic activity, rebalancing the autonomic function towards that associated with healthy function. In addition, some people reported improvements in measures of mental health and sleeping patterns.

Being able to correct this balance of activity could help us age more healthily, as well as having the potential to help people with a variety of disorders such as heart disease and some mental health issues.

Additionally, improving the balance of the autonomic nervous system lowers an individual's risk of death, as well as the need for medication or hospital visits.

Researchers found that individuals who displayed the greatest imbalance at the start of the study experienced the most pronounced improvements after receiving the therapy.

They suggest that in future it may be possible to identify who is most likely to benefit from the therapy, so it can be offered through a targeted approach.

tVNS therapy has previously been shown to have positive psychological effects for patients with depression, and this study shows it could also have significant physiological benefits.

Dr Susan Deuchars, one of the senior authors on the study, said: "We believe this stimulation can make a big difference to people's lives, and we're now hoping to conduct further studies to see if tVNS can benefit multiple disorders."

Further studies are now needed to understand what the long-term health effects of tVNS might be, as this study involved a small number of participants over a short time period.

High-energy shock waves driven by solar flares and coronal mass ejections of plasma from the sun erupt throughout the solar system, unleashing magnetic space storms that can damage satellites, disrupt cell phone service and blackout power grids on Earth. Also driving high-energy waves is the solar wind -- plasma that constantly flows from the sun and buffets the Earth's protective magnetic field.

Now experiments led by researchers at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) in the Princeton Center for Heliophysics have for the first time reproduced the process behind the source of such shocks. The findings bridge the gap between laboratory and spacecraft observations and advance understanding of how the universe works.

Sudden jumps

The experiments, reported in Physical Review Letters, show how the interaction of plasma -- the state of matter composed of free electrons and atomic nuclei, or ions -- can cause sudden jumps in plasma pressure and magnetic field strength that can accelerate particles to near the speed of light. Such shocks are "collisionless" because they are formed by the interaction of waves and plasma particles rather than by collisions between the particles themselves.

The research produced measurement of the full run-up to shocks. "Direct measurement is an elegant way to see how the particles are moving and interacting," said physicist Derek Schaeffer of PPPL and Princeton University, who led the research. "Our paper shows that we can employ a powerful diagnostic to study the particle motions that lead to shocks."

The research, conducted on the Omega laser facility at the University of Rochester, produced a laser-driven plasma -- called a "piston" plasma -- that expanded at the supersonic rate of more than one million miles per hour through a pre-existing ambient plasma. The expansion accelerated ions in the ambient plasma to speeds of roughly half-a-million miles per hour, simulating the forerunner to collisionless shocks that occur throughout the cosmos.

The research unfolded in several stages:

First, creation of the piston plasma reproduced the supersonic plasmas that form in outer space. The piston acted like a snowplow, sweeping up ions in the ambient plasma embedded in a magnetic field.

As more of these ions became swept up, they formed a barrier that kept the piston from acting further. "Once you've piled up enough 'snow', the shock decouples from the piston," Schaeffer said.

The halted piston handed off formation of the shock to the highly compressed magnetized plasma, which gave rise to the sudden collisionless jump.

Researchers used a diagnostic called Thompson scattering to track these developments. The diagnostic detects laser light scattered off the electrons in plasma, enabling measurement of the temperature and density of the electrons and the speed of the flowing ions. The results, the authors write, show that laboratory experiments can probe the behavior of plasma particles in the precursor to collisionless astrophysical shocks, "and can complement, and in some cases overcome the limitations of similar measurements undertaken by spacecraft missions."

Ultimate goal

While this research reproduced the process that sets off shocks, the ultimate goal is to measure the shock-accelerated particles themselves. For that step, said Schaeffer, "the same diagnostic can be used once we develop the capability to drive strong enough shocks. As a bonus," he adds, "this diagnostic is similar to how spacecraft measure particle motions in space shocks, so future results can be directly compared."

All matter consists of one or more phases -- regions of space with uniform structure and physical properties. The common phases of H2O (solid, liquid and gas), also known as ice, water and steam, are well known. Similarly, though less familiar, perhaps, polymeric materials also can form different solid or liquid phases that determine their properties and ultimate utility. This is especially true of block copolymers, the self-assembling macromolecules created when a polymer chain of one type ("Block A") is chemically connected with that of a different type ("Block B").

"If you want a block copolymer that has a certain property, you pick the right phase for a given application of interest," explained Chris Bates, an assistant professor of materials in the UC Santa Barbara College of Engineering. "For the rubber in shoes, you want one phase; to make a membrane, you want a different one."

Only about five phases have been discovered in the simplest block copolymers. Finding a new phase is rare, but Bates and a team of other UC Santa Barbara researchers including professors Glenn Fredrickson (chemical engineering) and Craig Hawker (materials), Morgan Bates, staff scientist and assistant director for technology at the Dow Materials Institute at UCSB, and postdoctoral researcher Joshua Lequieu, have done just that.

Their findings are published in the Proceedings of the National Academy of Sciences.

About 12 months ago, Morgan Bates was doing some experimental work on polymers she had synthesized in the lab, in an effort, she said, "to understand the fundamental parameters that govern self-assembly of block copolymers by examining what happens when you tweak block chemistry."

There are endless possibilities for the chemistry of "A" and "B" blocks, according to Chris Bates. "Modern synthetic chemistry allows us to pick basically any type of A polymer and connect it with a different B block," he said. "Given this vast design space, the real challenge is figuring out the most crucial knobs to turn that control self-assembly."

Morgan Bates was trying to understand that relationship between chemistry and structure.

"I had chemically tweaked a parameter related to what is called 'conformational asymmetry,' which describes how the two blocks fill space," she recalled of the process that led to the discovery. "We weren't necessarily trying to find a new phase but thought that maybe we'd uncover some new behavior. In this case, the A and B blocks that are covalently tied together fill space very differently, and that seems to be the underlying parameter that gives rise to some unique self-assembly."

After creating the block copolymers, she took them to the Advanced Photon Source at Argonne National Laboratory, in Illinois, where a technique called "small-angle X-ray scattering" was used to characterize them. The process yields a two-dimensional signature of scattered X-rays arranged in concentric rings. The relative placement and intensity of the rings indicates a particular phase. Morgan needed to travel to a national lab, because the process requires X-rays more powerful than what can be produced on campus.

After that work, said Chris Bates, "Using knowledge of crystallography, you can interpret the scattering data and produce an image as if you were looking at the structure with your eye. And in this case, the data was of such high quality that we were able to do that unambiguously."

Morgan Bates recalled that when she examined the X-ray pattern, one thing was unmistakably clear: "It looked different. I thought, 'What is that?'"

It was, of course, their newly discovered phase, known as A15. "With these types of AB block copolymers, there are only a handful of phases that people have observed previously, and we've found another one, which adds to the palette of possible options from a design standpoint," Chris said.

"Among the ways of categorizing structures, this phase belongs to a class known as 'tetrahedrally close-packed'," added Lequieu, an expert in computer simulations who modeled the phase behavior of polymers. "The phase we've found in block copolymers was actually first observed in 1931 with an allotrope [or form] of tungsten. But in that case, A15 forms from metal atoms, which create a very small structure at the atomic length scale. Our block copolymers adopt the same structure but at a length scale two orders of magnitude larger, and, of course, no metal atoms are involved.

"If you were to look at both with a microscope," he continued, "their structures would look the same, but just at different sizes. It's fascinating that nature chooses to use the same structural motifs for completely different materials having entirely unrelated chemistry and physics."

The project demonstrates the ease of, and proclivity for, collaboration among UC Santa Barbara researchers. It began with new chemistry developed by Hawker and Bates to tune the properties of materials, which was followed by Morgan's unexpected characterization results. "From there, we went to Josh and told him there's something strange in the experiments that we didn't expect and asked him why," Chris Bates said. Lequieu then worked with Fredrickson to develop the computer simulations.

"There was a really nice back and forth on this project," Lequieu said. "An experiment was done that was challenging to understand, so we performed simulations to explain it. Morgan then did more experiments, informed by the results of the initial simulations, and observed that the computations were actually predictive. The phases observed experimentally showed up right where the simulations said they would. In some places, however the experiments and simulations disagreed, so we iterated multiple times to improve the models and really understand the subtleties involved."

"Moving forward," added Chris Bates, "our team continues to integrate materials synthesis and theory in a search of more unique phase behavior."

Lequieu described the feedback loop from experiment to simulation to theory and back around as "sort of the dream of modern materials science. It takes a lot of work for Morgan to make these samples. It's much easier if someone predicts outcomes on a computer and can say, 'Here's a subset of polymers to synthesize that should form the desired structure.' This so-called 'inverse design' approach saves her a lot of time and effort."

In terms of nature falling back on preferred designs for otherwise unrelated materials, a bit of history is worth noting. In 1887, Lord Kelvin -- he of the eponymous units of absolute temperature -- was working on what later came to be known as the "Kelvin problem." It was an effort to determine how space could be partitioned into cells of equal volume with the least surface area between them. His proposed solution, which indicated the most efficient bubble foam, became known as the "Kelvin structure."

It held for about a hundred years, but in 1994 was shown to be incorrect. Kelvin had chosen what could be called "Structure A," but a team of British scientists showed that "Structure B" was even better. Since then, Structure B has gained fame in scientific circles and even well beyond, appearing, for instance, in the form of giant bubbles that serve as both functional architectural elements and design elements on the roof of the Beijing National Aquatics Center built for the 2008 Olympics.

It turns out that the new phase discovered by the researchers in this project, A15, is Structure B, confirming once again that nature likes a previously successful design.