Thursday, May 24, 2018

Ancient Mound Builders Carefully Timed Their Occupation of Coastal Louisiana Site

A study of ancient mound builders who lived hundreds of years ago on the Mississippi River Delta near present-day New Orleans offers new insights into how Native peoples selected the landforms that supported their villages and earthen mounds - and why these sites were later abandoned.

The study, reported in the Journal of Island and Coastal Archaeology, also offers a timeline of the natural and human events that shaped one particular site, said University of Illinois anthropology professor Jayur Mehta, who conducted the work with Vanderbilt University postdoctoral researcher Elizabeth Chamberlain while both were at Tulane University in New Orleans.



Hundreds of ancient mound sites, depicted here with yellow triangles, still survive in coastal Louisiana. A new study teases out the natural and human history of one of these mound-top villages, a site known as Grand Caillou, shown in red.
 
Graphic by Julie McMahon after Mehta and Chamberlain.


The site, now known as Grand Caillou, is one of hundreds of mound sites in coastal Louisiana, Mehta said. (Watch a video about the research and history of the site.)

"Louisiana is incredibly important in the history of ancient mound-building cultures," he said. "In what is now the United States, earthen monument and mound construction began on the Louisiana coast."

Ancient peoples began building mounds in North America as early as 4,500 B.C., Mehta said. They often situated their mounds near resource-rich waterways, which could support larger human settlements. As many as 500 people lived at Grand Caillou in its heyday. Some mounds also served ceremonial functions.

That so many mound sites have survived in coastal Louisiana is a testament to their careful construction, Mehta said. Neglect, however, and coastal subsidence - the result of engineered changes to the flow of the Mississippi River - are wearing away at the mounds.

"Louisiana loses about two ancient mounds and/or Native American villages a year," Mehta said.

The researchers used a variety of methods - sediment coring, radiocarbon dating, carbon-isotope analysis, the dating of ceramics found onsite and a method called optically stimulated luminescence - to figure out how and when the land underneath the Grand Caillou mound was formed by natural forces and when the mound builders arrived and established their settlement.

"We wanted to understand at a deeper level how Indigenous peoples of the coast were choosing where to build their villages," Mehta said.

The mound at Grand Caillou.

Photo courtesy Jayur Mehta

Grand Caillou is situated on a natural levee of the Lafourche sub-delta, one of several major lobes of the Mississippi River Delta near New Orleans. Fed by sediments deposited by the river, Lafourche expanded in size over a period of several hundred years, a process that ended at about 800 A.D., the researchers found. The mound builders set up their village around 1200 A.D., long after the site was stable and covered over with vegetation, the team found.

Core samples and excavations revealed that the mound was built in distinct layers, with clay on the bottom, looser sediments piled in the middle and a clay cap on top. This finding confirms earlier archaeological reports that ancient mounds were engineered in layers to withstand the elements.

"The way they were constructed contributes to their durability," Mehta said.

The Grand Caillou mound was built on top of a river deposit that was naturally higher than surrounding land.

"It's only a few feet higher than nearby areas," Mehta said. "But in a landscape where there's no topography, one or two feet can make a world of difference."

Ceramics found at the site date to between 1000 and 1400 A.D. Radiocarbon dating of charcoal found evidence that the site was abandoned by about 1400. By looking at ratios of carbon isotopes - carbon atoms with differing masses - the team saw changes over time that were likely the result of saltwater incursion into the area. These changes coincided with the ultimate abandonment of the village site.

The new study is a much-needed addition to research on threatened cultural sites in coastal regions, said University of Tennessee anthropology professor David G. Anderson, an expert on U.S. Paleoindian archaeology who was not involved in the research.

"We are facing the loss of much of the record of human settlement and use of coastal zones - and must take steps to address the challenge," Anderson said. "Mehta and Chamberlain's study exemplifies the kind of work that will be needed."
 



Contacts and sources:
Jayur Mehta
University of Illinois


Citation: "Mound construction and site selection in the Lafourche subdelta of the Mississippi River delta, Louisiana, USA" is available online

Earth's Temperature to Increase by 4 Degrees by 2084



A collaborative research team from China has published a new analysis that shows the Earth's climate would increase by 4 °C, compared to pre-industrial levels, before the end of 21st century.

To understand the severity of this, consider the Paris Agreement )\\ of the United Nations. It's a global effort to prevent an increase of 2°C. Nearly every country on the planet--the United States is the only country to withdraw--has agreed to work to prevent the catastrophic effects of two degrees of warming.

The study is selected as the cover article of Issue No. 8 of Advances in Atmospheric Sciences in 2018. The levels of future global warming relative to the pre-industrial period have been extensively addressed, in which 2 C and 1.5 C warming have attracted the most attention. A special report 'Turn Down the Heat: Why a 4°C Warmer World must be Avoided' by the World Bank in 2012 described a 4 C warmer world with significant changes in mean and extreme climates on the basis of earlier-generation climate models and emission scenarios.
Image by Advances in Atmospheric Sciences

The researchers published their analysis projecting a doubling of that increase in Advances in Atmospheric Sciences on May 18, 2018.

"A great many record-breaking heat events, heavy floods, and extreme droughts would occur if global warming crosses the 4 °C level, with respect to the preindustrial period," said Dabang Jiang, a senior researcher at the Institute of Atmospheric Physics of the Chinese Academy of Sciences. "The temperature increase would cause severe threats to ecosystems, human systems, and associated societies and economies."

In the analysis, Jiang and his team used the parameters of scenario in which there was no mitigation of rising greenhouse gas emissions. They compared 39 coordinated climate model experiments from the fifth phase of the Coupled Model Intercomparison Project (), which develops and reviews climate models to ensure the most accurate climate simulations possible.

They found that most of the models projected an increase of 4°C as early as 2064 and as late as 2095 in the 21st century, with 2084 appearing as the median year.

This increase translates to more annual and seasonal warming over land than over the ocean, with significant warming in the Arctic. The variability of temperature throughout one year would be lower in the tropics and higher in polar regions, while precipitation would most likely increase in the Arctic and in the Pacific. These are the same effects that would occur under 1.5°C or 2°C increases, but more severe.

"Such comparisons between the three levels of global warming imply that global and regional climate will undergo greater changes if higher levels of global warming are crossed in the 21st century," wrote Jiang.

The researchers continue to investigate the changes associated with 4°C of global warming in extreme climates.

"Our ultimate goal is to provide a comprehensive picture of the mean and extreme climate changes associated with higher levels of global warming based on state-of-the art climate models, which is of high interest to the decision-makers and the public," said Jiang.





Contacts and sources:
Zheng Lin
Institute of Atmospheric Physics
Chinese Academy of Sciences

Researchers from the Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences, the Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters at the Nanjing University of Information Science & Technology, the Joint Laboratory for Climate and Environmental Change at Chengdu University of Information Technology, and the University of Chinese Academy of Sciences contributed to this study.

This work was supported by the National Basic Research Program of China and the National Natural Science Foundation of China.

Wednesday, May 23, 2018

Quantum Computer Simulates Deuteron



Scientists at the Department of Energy's Oak Ridge National Laboratory are the first to successfully simulate an atomic nucleus using a quantum computer. The results, published in Physical Review Letters, demonstrate the ability of quantum systems to compute nuclear physics problems and serve as a benchmark for future calculations.

Quantum computing, in which computations are carried out based on the quantum principles of matter, was proposed by American theoretical physicist Richard Feynman in the early 1980s. Unlike normal computer bits, the qubit units used by quantum computers store information in two-state systems, such as electrons or photons, that are considered to be in all possible quantum states at once (a phenomenon known as superposition).

An image of a deuteron, the bound state of a proton and a neutron.

Credit:  Andrew Sproles, Oak Ridge National Laboratory

"In classical computing, you write in bits of zero and one," said Thomas Papenbrock, a theoretical nuclear physicist at the University of Tennessee and ORNL who co-led the project with ORNL quantum information specialist Pavel Lougovski. "But with a qubit, you can have zero, one, and any possible combination of zero and one, so you gain a vast set of possibilities to store data."

In October 2017 the multidivisional ORNL team started developing codes to perform simulations on the IBM QX5 and the Rigetti 19Q quantum computers through DOE's Quantum Testbed Pathfinder project, an effort to verify and validate scientific applications on different quantum hardware types. Using freely available pyQuil software, a library designed for producing programs in the quantum instruction language, the researchers wrote a code that was sent first to a simulator and then to the cloud-based IBM QX5 and Rigetti 19Q systems.

The team performed more than 700,000 quantum computing measurements of the energy of a deuteron, the nuclear bound state of a proton and a neutron. From these measurements, the team extracted the deuteron's binding energy--the minimum amount of energy needed to disassemble it into these subatomic particles. The deuteron is the simplest composite atomic nucleus, making it an ideal candidate for the project.

"Qubits are generic versions of quantum two-state systems. They have no properties of a neutron or a proton to start with," Lougovski said. "We can map these properties to qubits and then use them to simulate specific phenomena--in this case, binding energy."

A challenge of working with these quantum systems is that scientists must run simulations remotely and then wait for results. ORNL computer science researcher Alex McCaskey and ORNL quantum information research scientist Eugene Dumitrescu ran single measurements 8,000 times each to ensure the statistical accuracy of their results.

"It's really difficult to do this over the internet," McCaskey said. "This algorithm has been done primarily by the hardware vendors themselves, and they can actually touch the machine. They are turning the knobs."

The team also found that quantum devices become tricky to work with due to inherent noise on the chip, which can alter results drastically. McCaskey and Dumitrescu successfully employed strategies to mitigate high error rates, such as artificially adding more noise to the simulation to see its impact and deduce what the results would be with zero noise.

"These systems are really susceptible to noise," said Gustav Jansen, a computational scientist in the Scientific Computing Group at the Oak Ridge Leadership Computing Facility (OLCF), a DOE Office of Science User Facility located at ORNL. "If particles are coming in and hitting the quantum computer, it can really skew your measurements. These systems aren't perfect, but in working with them, we can gain a better understanding of the intrinsic errors."

At the completion of the project, the team's results on two and three qubits were within 2 and 3 percent, respectively, of the correct answer on a classical computer, and the quantum computation became the first of its kind in the nuclear physics community.

The proof-of-principle simulation paves the way for computing much heavier nuclei with many more protons and neutrons on quantum systems in the future. Quantum computers have potential applications in cryptography, artificial intelligence, and weather forecasting because each additional qubit becomes entangled--or tied inextricably--to the others, exponentially increasing the number of possible outcomes for the measured state at the end. This very benefit, however, also has adverse effects on the system because errors may also scale exponentially with problem size.

Papenbrock said the team's hope is that improved hardware will eventually enable scientists to solve problems that cannot be solved on traditional high-performance computing resources--not even on the ones at the OLCF. In the future, quantum computations of complex nuclei could unravel important details about the properties of matter, the formation of heavy elements, and the origins of the universe.





Contacts and sources:
Rachel Harken
Department of Energy's Oak Ridge National Laboratory

Citation: Results from the study, titled "Cloud Quantum Computing of an Atomic Nucleus," were published in Physical Review Letters.

The paper's coauthors, all from ORNL, were Eugene F. Dumitrescu, Alex J. McCaskey, Gaute Hagen, Gustav R. Jansen, Titus D. Morris, Thomas Papenbrock, Raphael C. Pooser, David J. Dean, and Pavel Lougovski. Hagen, Morris, Papenbrock, and Pooser also are affiliated with the University of Tennessee, Knoxville.

Tuesday, May 22, 2018

Drinking Baking Soda an Inexpensive, Safe Way to Combat Autoimmune Disease Says Study



A daily dose of baking soda may help reduce the destructive inflammation of autoimmune diseases like rheumatoid arthritis, scientists say.

They have some of the first evidence of how the cheap, over-the-counter antacid can encourage our spleen to promote instead an anti-inflammatory environment that could be therapeutic in the face of inflammatory disease, Medical College of Georgia scientists report in The Journal of Immunology.

They have shown that when rats or healthy people drink a solution of baking soda, or sodium bicarbonate, it becomes a trigger for the stomach to make more acid to digest the next meal and for little-studied mesothelial cells sitting on the spleen to tell the fist-sized organ that there’s no need to mount a protective immune response.

Credit:

“It’s most likely a hamburger not a bacterial infection,” is basically the message, says Dr. Paul O’Connor, renal physiologist in the MCG Department of Physiology at Augusta University and the study’s corresponding author.

Mesothelial cells line body cavities, like the one that contains our digestive tract, and they also cover the exterior of our organs to quite literally keep them from rubbing together. About a decade ago, it was found that these cells also provide another level of protection. They have little fingers, called microvilli, that sense the environment, and warn the organs they cover that there is an invader and an immune response is needed.

Drinking baking soda, the MCG scientists think, tells the spleen – which is part of the immune system, acts like a big blood filter and is where some white blood cells, like macrophages, are stored – to go easy on the immune response. “Certainly drinking bicarbonate affects the spleen and we think it’s through the mesothelial cells,” O’Connor says.

The conversation, which occurs with the help of the chemical messenger acetylcholine, appears to promote a landscape that shifts against inflammation, they report.

In the spleen, as well as the blood and kidneys, they found after drinking water with baking soda for two weeks, the population of immune cells called macrophages, shifted from primarily those that promote inflammation, called M1, to those that reduce it, called M2. Macrophages, perhaps best known for their ability to consume garbage in the body like debris from injured or dead cells, are early arrivers to a call for an immune response.

In the case of the lab animals, the problems were hypertension and chronic kidney disease, problems which got O’Connor’s lab thinking about baking soda.

One of the many functions of the kidneys is balancing important compounds like acid, potassium and sodium. With kidney disease, there is impaired kidney function and one of the resulting problems can be that the blood becomes too acidic, O’Connor says. Significant consequences can include increased risk of cardiovascular disease and osteoporosis.

“It sets the whole system up to fail basically,” O’Connor says. Clinical trials have shown that a daily dose of baking soda can not only reduce acidity but actually slow progression of the kidney disease, and it’s now a therapy offered to patients.

“We started thinking, how does baking soda slow progression of kidney disease?” O’Connor says.

That’s when the anti-inflammatory impact began to unfold as they saw reduced numbers of M1s and increased M2s in their kidney disease model after consuming the common compound.

When they looked at a rat model without actual kidney damage, they saw the same response. So the basic scientists worked with the investigators at MCG’s Georgia Prevention Institute to bring in healthy medical students who drank baking soda in a bottle of water and also had a similar response.

“The shift from inflammatory to an anti-inflammatory profile is happening everywhere,” O’Connor says. “We saw it in the kidneys, we saw it in the spleen, now we see it in the peripheral blood.”

The shifting landscape, he says, is likely due to increased conversion of some of the proinflammatory cells to anti-inflammatory ones coupled with actual production of more anti-inflammatory macrophages. The scientists also saw a shift in other immune cell types, like more regulatory T cells, which generally drive down the immune response and help keep the immune system from attacking our own tissues. That anti-inflammatory shift was sustained for at least four hours in humans and three days in rats.

The shift ties back to the mesothelial cells and their conversations with our spleen with the help of acetylcholine. Part of the new information about mesothelial cells is that they are neuron-like, but not neurons O’Connor is quick to clarify.

“We think the cholinergic (acetylcholine) signals that we know mediate this anti-inflammatory response aren’t coming directly from the vagal nerve innervating the spleen, but from the mesothelial cells that form these connections to the spleen,” O’Connor says.

In fact, when they cut the vagal nerve, a big cranial nerve that starts in the brain and reaches into the heart, lungs and gut to help control things like a constant heart rate and food digestion, it did not impact the mesothelial cells’ neuron-like behavior.

The affect, it appears, was more local because just touching the spleen did have an effect.

When they removed or even just moved the spleen, it broke the fragile mesothelial connections and the anti-inflammatory response was lost, O’Connor says. In fact, when they only slightly moved the spleen as might occur in surgery, the previously smooth covering of mesothelial cells became lumpier and changed colors.

“We think this helps explain the cholinergic (acetylcholine) anti-inflammatory response that people have been studying for a long time,” O’Connor says.

Studies are currently underway at other institutions that, much like vagal nerve stimulation for seizures, electrically stimulate the vagal nerve to tamp down the immune response in people with rheumatoid arthritis. While there is no known direct connection between the vagal nerve and the spleen – and O’Connor and his team looked again for one – the treatment also attenuates inflammation and disease severity in rheumatoid arthritis, researchers at the Feinstein Institute for Medical Research reported in 2016 in the journal Proceedings of the National Academy of Sciences.

O’Connor hopes drinking baking soda can one day produce similar results for people with autoimmune disease.

“You are not really turning anything off or on, you are just pushing it toward one side by giving an anti-inflammatory stimulus,” he says, in this case, away from harmful inflammation. “It’s potentially a really safe way to treat inflammatory disease.”

The spleen also got bigger with consuming baking soda, the scientists think because of the anti-inflammatory stimulus it produces. Infection also can increase spleen size and physicians often palpate the spleen when concerned about a big infection.

Other cells besides neurons are known to use the chemical communicator acetylcholine. Baking soda also interact with acidic ingredients like buttermilk and cocoa in cakes and other baked goods to help the batter expand and, along with heat from the oven, to rise. It can also help raise the pH in pools, is found in antacids and can help clean your teeth and tub.

The research was funded by the National Institutes of Health.



Contacts and sources:
Toni Baker
Medical College of Georgia at Augusta University
Citation:  Oral NaHCO3 Activates a Splenic Anti-Inflammatory Pathway: Evidence That Cholinergic Signals Are Transmitted via Mesothelial Cells Sarah C. Ray, Babak Baban, Matthew A. Tucker, Alec J. Seaton, Kyu Chul Chang, Elinor C. Mannon, Jingping Sun, Bansari Patel, Katie Wilson, Jacqueline B. Musall, Hiram Ocasio, Debra Irsik, Jessica A. Filosa, Jennifer C. Sullivan, Brendan Marshall, Ryan A. Harris, Paul M. O’Connor.. The Journal of Immunology, 2018; ji1701605 DOI: 10.4049/jimmunol.1701605

Birds of a Different Feather Can Form Lasting Friendships

Cooperation among different species of birds is common. Some birds build their nests near those of larger, more aggressive species to deter predators, and flocks of mixed species forage for food and defend territories together in alliances that can last for years. In most cases, though, these partnerships are not between specific individuals of the other species—any bird from the other species will do.

But in a new study published in the journal Behavioral Ecology, scientists from the University of Chicago and University of Nebraska show how two different species of Australian fairy-wrens not only recognize individual birds from other species, but also form long-term partnerships that help them forage and defend their shared space as a group.
Splendid fairy-wren
Photos by Allison Johnson

“Finding that these two species associate was not surprising, as mixed species flocks of birds are observed all over the world,” said Allison Johnson, PhD, a postdoctoral scholar at the University of Nebraska who conducted the study as part of her dissertation research at UChicago. “But when we realized they were sharing territories with specific individuals and responding aggressively only to unknown individuals, we knew this was really unique. It completely changed our research and we knew we had to investigate it.”

Variegated fairy-wren

Photos by Allison Johnson 

Variegated fairy-wrens and splendid fairy-wrens are two small songbirds that live in Australia. The males of each species have striking, bright blue feathers that make them popular with bird watchers. Their behavior also makes them an appealing subject for biologists. Both species feed on insects, live in large family groups, and breed during the same time of year. They are also non-migratory, meaning they live in one area for their entire lives, occupying the same eucalyptus scrublands that provide plenty of bushes and trees for cover.

When these territories overlap, the two species interact with each other. They forage together, travel together, and seem to be aware of what the other species is doing. They also help each other defend their territory from rivals. Variegated fairy-wrens will defend their shared territory from both variegated and splendid outsiders; splendid fairy-wrens will do the same, while fending off unfamiliar birds from both species.

“Splendid and variegated fairy-wrens are so similar in their habitat preferences and behavior, we would expect them to act as competitors. Instead, we've found stable, positive relationships between individuals of the two species,” said Christina Masco, PhD, a graduate student at UChicago and a co-author on the new paper.

Many songbirds can recognize familiar members of their own species on the basis of the unique songs each bird sings. However, in this research the investigators believed this recognition occurred across species. How could they be so certain?

From 2012-2015, Johnson, Masco, and their former advisor, Stephen Pruett-Jones, PhD, associate professor of ecology and evolution at UChicago, studied these species at Brookfield Conservation Park in South Australia. The first unusual observation Johnson made was that when playing a recorded vocalization of one species, the other species would respond and fly in to investigate what was going on.

Splendid fairy-wren  
Photos by Allison Johnson

To follow up on this observation, the researchers monitored both fairy-wren species in the darkness before dawn and captured clear recordings of their signature songs. After sunrise, they broadcast the recorded songs from a speaker to simulate an intrusion by a particular bird into a group’s territory. The objective was to see how territory owners reacted to the songs of familiar and unfamiliar members of the other species.

The researchers placed a speaker about 30 meters away from a subject fairy-wren and played the songs of four different individuals: a fairy-wren that occupied the same territory (a co-resident or “friendly” bird), a fairy-wren from an adjacent territory (a neighbor), a fairy-wren from an area five or more territories away (an unknown bird), and a red-capped robin, a common species in the park that doesn’t pose a threat to the fairy-wrens (as a control group).

Both splendid and variegated fairy-wrens demonstrated the ability to recognize their co-residents’ songs despite the species difference. Socially dominant males of both species responded more aggressively to songs of neighbors and unknown birds of the other fairy-wren species than they did to friendly birds sharing their territory, or to the red-capped robin. When they heard songs from friendly birds, they didn’t respond, suggesting they didn’t see them as a threat.

By forming and keeping these associations with another species, fairy-wrens can better defend their nests from predators and their territories from rivals. There is also evidence that interacting with the other species has additional benefits besides territorial defense. While the splendid fairy-wrens didn’t change their behavior when associating with the other species, the variegated fairy-wrens spent more time foraging, were less vigilant, and had more success raising their young.

Variegated fairy-wren

Photos by Allison Johnson 

Johnson, Masco, and Pruett-Jones believe the fairy-wrens associate with the other species as a form of cooperation. By interacting with other species that share the same territory instead of working against them, these already social species create a larger group to help defend their territory and ward off intruders. In other words, if you can’t beat ‘em, join ‘em.

“Although our discovery that individuals of different species recognize each other was unexpected, it is likely that something similar occurs whenever species of non-migratory birds live on overlapping territories,” Pruett-Jones said. “Recognition facilitates sociality within species, and it follows that it could also facilitate associations between species.”

The study, “Song recognition and heterospecific associations between two fairy-wren species (Maluridae),” was supported by the National Science Foundation, UChicago, the Norman Wettenhall Foundation, and the American Ornithological Society.



Contacts and sources:
Matt Wood
University of Chicago Medical Center.

Citation: Song recognition and heterospecific associations between 2 fairy-wren species (Maluridae)
Allison E Johnson, Christina Masco, Stephen Pruett-Jones.. Behavioral Ecology, 2018; DOI: 10.1093/beheco/ary071

Monday, May 21, 2018

Lightning in the Eyewall of a Hurricane Beamed Antimatter toward the Ground

Hurricane Patricia, which battered the west coast of Mexico in 2015, was the most intense tropical cyclone ever recorded in the Western Hemisphere. Amid the extreme violence of the storm, scientists observed something new: a downward beam of positrons, the antimatter counterpart of electrons, creating a burst of powerful gamma-rays and x-rays.

Detected by an instrument aboard NOAA's Hurricane Hunter aircraft, which flew through the eyewall of the storm at its peak intensity, the positron beam was not a surprise to the UC Santa Cruz scientists who built the instrument. But it was the first time anyone has observed this phenomenon.

Hurricane Patricia was the most intense tropical cyclone ever recorded in the Western Hemisphere as it approached the west coast of Mexico in 2015. Researchers detected a reverse positron beam from a terrestrial gamma-ray flash associated with lightning in the eyewall of the hurricane.

Credit: NASA image by Jeff Schmaltz, LANCE/EOSDIS Rapid Response



According to David Smith, a professor of physics at UC Santa Cruz, the positron beam was the downward component of an upward terrestrial gamma-ray flash that sent a short blast of radiation into space above the storm. Terrestrial gamma-ray flashes (TGFs) were first seen in 1994 by space-based gamma-ray detectors. They occur in conjunction with lightning and have now been observed thousands of times by orbiting satellites. A reverse positron beam was predicted by theoretical models of TGFs, but had never been detected.

"This is the first confirmation of that theoretical prediction, and it shows that TGFs are piercing the atmosphere from top to bottom with high-energy radiation," Smith said. "This event could have been detected from space, like almost all the other reported TGFs, as an upward beam caused by an avalanche of electrons. We saw it from below because of a beam of antimatter (positrons) sent in the opposite direction."

Researchers at the SCIPP labs at UC Santa Cruz built the Airborne Detector for Energetic Lightning Emissions (ADELE) mark II to observe TGFs up close by measuring x-rays and gamma-rays from aircraft flown into or above thunderstorms.

Credit: Gregory Bowers



One unexpected implication of the study, published May 17 in the Journal of Geophysical Research: Atmospheres, is that many TGFs could be detected via the reverse positron beam using ground-based instruments at high altitudes. It's not necessary to fly into the eye of a hurricane.

"We detected it at an altitude of 2.5 kilometers, and I estimated our detectors could have seen it down to 1.5 kilometers. That's the altitude of Denver, so there are a lot of places where you could in theory see them if you had an instrument in the right place at the right time during a thunderstorm," Smith said.

Despite the confirmation of the reverse positron beam, many questions remain unresolved about the mechanisms that drive TGFs. Strong electric fields in thunderstorms can accelerate electrons to near the speed of light, and these "relativistic" electrons emit gamma-rays when they scatter off of atoms in the atmosphere. The electrons can also knock other electrons off of atoms and accelerate them to high energies, creating an avalanche of relativistic electrons. A TGF, which is an extremely bright flash of gamma-rays, requires a large number of avalanches of relativistic electrons.

"It's an extraordinary event, and we still don't understand how it gets so bright," Smith said.

The source of the positrons, however, is a well known phenomenon in physics called pair production, in which a gamma ray interacts with the nucleus of an atom to create an electron and a positron. Since they have opposite charges, they are accelerated in opposite directions by the electric field of the thunderstorm. The downward moving positrons produce x-rays and gamma-rays in their direction of travel when they collide with atomic nuclei, just like the upward moving electrons.

"What we saw in the aircraft are the gamma-rays produced by the downward positron beam," Smith said.

First author Gregory Bowers, now at Los Alamos National Laboratory, and coauthor Nicole Kelley, now at Swift Navigation, were both graduate students at UC Santa Cruz when they worked together on the instrument that made the detection. The Airborne Detector for Energetic Lightning Emissions (ADELE) mark II was designed to observe TGFs up close by measuring x-rays and gamma-rays from aircraft flown into or above thunderstorms.

The ADELE mark II flew aboard NOAA's Hurricane Hunter WP-3D Orion during the Atlantic hurricane season.

Credit: Gregory Bowers


Getting too close to a TGF could be hazardous, although the risk drops off rapidly with distance from the source. The gamma-ray dose at a distance of one kilometer would be negligible, Smith said. "It's hypothetically a risk, but the odds are quite small," he said. "I don't ask pilots to fly into thunderstorms, but if they're going anyway I'll put an instrument on board."

Smith's group was the first to detect a TGF from an airplane using an earlier instrument, the ADELE mark I. In that case, the upward beam from the TGF was detected above a thunderstorm. For this study, the ADELE mark II flew aboard NOAA's Hurricane Hunter WP-3D Orion during the Atlantic hurricane season.

In addition to Bowers, Smith, and Kelley, the coauthors of the paper include Forest Martinez-McKinney at UC Santa Cruz, Joseph Dwyer at the University of New Hampshire, and scientists at Duke University, Earth Networks, University of Washington, NOAA, and Florida Institute of Technology. This work was funded by the National Science Foundation.




Contacts and sources:
Tim Stephens
University of California  Santa Cruz

Citation: A Terrestrial Gamma‐Ray Flash inside the Eyewall of Hurricane PatriciaG. S. BowersD. M. SmithN. A. Kelley, G. F. Martinez‐McKinney, S. A. Cummer, J. R. Dwyer, S. Heckman, R. H. Holzworth, F. Marks,  P. Reasor, J. Gamache, J. Dunion, T. Richards, H. K. Rassoul, First published: 04 May 2018    http://dx.doi.org/10.1029/2017JD027771

Extrasolar Asteroid Has Been Orbiting the Sun for 4.5 Billion Years

The Solar System is much vaster and more complex than is usually assumed. The Sun's gravitational pull on the gravitational fields of the nearest stars is estimated to extend for approximately two light-years (125 astronomical units), meaning the light emitted by the Sun takes approximately two years to reach the outer edge of the Solar System.

This enormous gravitational niche is home to millions of objects, from planets and moons to comets, asteroids and meteoroids. One object differs from all the rest, like an "odd man out", as it were: asteroid (514107) 2015 BZ509.

The motion of 2015 BZ509 (red line) relative to that of Jupiter (small blue circle) repeats every six years, always avoiding collision with the planet. Jupiter and the asteroid orbit the Sun (yellow circle) every 12 years. Their relative motion is projected on the plane of Jupiter's orbit. The asteroid moves close to but not exactly in this plane.

Credit: Maria Helena Moreira Morais

The difference is its retrograde orbit: this asteroid revolves around the Sun in the opposite direction to the planets and other celestial bodies. This retrograde orbit and its stability since the Solar System began are considered strong evidence that it is of extrasolar origin and was captured by Jupiter's gravitational field toward the end of the era in which the planets were formed. According to an article published in Monthly Notices of the Royal Astronomical Society-Letters, a study based on robust computer simulation has now corroborated this hypothesis.

The article is by Maria Helena Moreira Morais, a professor at São Paulo State University's Institute of Geosciences & Exact Sciences (IGCE-UNESP), with co-author Fathi Namouni, a researcher at the Côte d'Azur Observatory in France. Morais's participation in the study was supported by the São Paulo Research Foundation - FAPESP via the project "Topics of orbital dynamics and machine learning tools applied to planetary systems data".

"We'd already constructed a theory to explain the movement of this asteroid. In 2017, we published an article on it in Nature," Morais said. "In order to try to understand the origin of the object, we later performed large-scale simulations, which resulted in a new article that's coming out now in Monthly Notices of the Royal Astronomical Society: Letters."

Large-scale simulation is needed for the following two reasons: first, the margin of error in astronomical observations relating to the orbits of celestial bodies, and second, the chaotic component introduced into the movements of celestial bodies by gravitational interactions with the planets of the Solar System such that a very small difference in initial conditions can result in huge differences billions of years later.

"To surmount these problems, we had to do a very large statistical study simulating a million orbits," Morais explained. "Studies on this scale had never been done before. Simulations typically consider a thousand possibilities at most."

The simulations included not only the gravitational effect of planets but also the gravitational influence of the Galaxy because for objects at a great distance from the Sun, this component becomes relevant. They recreated the trajectory of (514107) 2015 BZ509 since the end of our Solar System's planet-formation phase approximately 4.5 billion years ago and showed that its orbit has remained stable throughout this period within the limits of the margin of error.

Hence, the uniqueness of (514107) 2015 BZ509 compared with other asteroids in the group of retrograde Centaurs, ordinary asteroids that were expelled to a remote region of the Solar System, the Oort Cloud, by the gravitational instability due to the rapid growth of the giant planets.

The retrograde Centaurs originally orbited the Sun in the same direction as all other bodies in the Solar System, but owing to their extreme distance from the Sun, the Galaxy's gravity affected their movement to such an extent that some became retrograde. This process took approximately one billion years. Later, some Centaurs were pulled back into the region influenced by the giant planets.

The statistical study showed that none of this happened to (514107) 2015 BZ509. This asteroid has stably occupied the path corresponding to Jupiter's orbit for at least 4.5 billion years and is a retrograde co-orbital asteroid of Jupiter.

"The conclusion must be that this asteroid came from outside the Solar System. It must have been cut loose from a neighboring star system and been captured by Jupiter's powerful gravitational field. Synchronism with Jupiter makes its orbit stable," Morais said.

'Oumuamua

The migration of objects from one system to another is not impossible. The Sun was formed together with other stars in a star nursery, so the density of stars in the Sun's vicinity was greater in the past than it is now. Nearby stars later moved away. Recent studies suggest that the Oort Cloud itself may partly consist of objects captured from other stars in the Solar System's infancy.

"At the end of 2017, our system was visited by another extrasolar asteroid called 'Oumuamua ['messenger from afar arriving first' in Hawaiian]," Morais recalled. "It traveled so fast that the Sun's attraction bent its path slightly and made it hyperbolic. It would have had to be moving less fast for the trajectory to become elliptical, in which case it would have been captured by the Solar System."

The study of (514107) 2015 BZ509 is far from over and in fact has only just begun. The object is a witness to the Solar System's infancy and could provide precious information about the environment that existed in the Sun's vicinity when the Solar System was formed.

"We may possibly be able to advance more if we can determine its chemical composition," Morais said. "Given that star systems have distinct chemical compositions, immigrant asteroids like (514107) 2015 BZ509 may have enriched the Solar System with elements that didn't exist here originally. In this way, they may have contributed to the emergence of life on Earth."



Contacts and sources:
Joao Carlos da Silva
The São Paulo Research Foundation (FAPESP)



Citation: An interstellar origin for Jupiter’s retrograde co-orbital asteroid
F Namouni M H M Morais
Monthly Notices of the Royal Astronomical Society: Letters, Volume 477, Issue 1, 11 June 2018, Pages L117–L121, https://doi.org/10.1093/mnrasl/sly057
 

First Known Permanent Immigrant to Our Solar System



A new study has discovered the first known permanent immigrant to our Solar System. The asteroid, currently nestling in Jupiter's orbit, is the first known asteroid to have been captured from another star system. The work is published in Monthly Notices of the Royal Astronomical Society: Letters.

The object known as 'Oumuamua was the last interstellar interloper to hit the headlines in 2017. However it was just a tourist passing through, whereas this former exo-asteroid - given the catchy name (514107) 2015 BZ509 - is a long-term resident.

All of the planets in our Solar System, and the vast majority of other objects as well, travel around the Sun in the same direction. However 2015 BZ509 is different - it moves in the opposite direction in what is known as a 'retrograde' orbit.




"How the asteroid came to move in this way while sharing Jupiter's orbit has until now been a mystery," explains Dr Fathi Namouni, lead author of the study. "If 2015 BZ509 were a native of our system, it should have had the same original direction as all of the other planets and asteroids, inherited from the cloud of gas and dust that formed them."

However the team ran simulations to trace the location of 2015 BZ509 right back to the birth of our Solar System, 4.5 billion years ago when the era of planet formation ended. These show that 2015 BZ509 has always moved in this way, and so could not have been there originally and must have been captured from another system.


These are images of 2015 BZ509 obtained at the Large Binocular Telescope Observatory (LBTO) that established its retrograde co-orbital nature. The bright stars and the asteroid (circled in yellow) appear black and the sky white in this negative image.

Credit: C. Veillet / Large Binocular Telescope Observatory
"Asteroid immigration from other star systems occurs because the Sun initially formed in a tightly-packed star cluster, where every star had its own system of planets and asteroids," comments Dr Helena Morais, the other member of the team.

"The close proximity of the stars, aided by the gravitational forces of the planets, help these systems attract, remove and capture asteroids from one another."

The discovery of the first permanent asteroid immigrant in the Solar System has important implications for the open problems of planet formation, solar system evolution, and possibly the origin of life itself.



This is an image of stellar nursery NGC 604 (NASA/HST), where star systems are closely packed and asteroid exchange is thought to be possible. Asteroid (514107) 2015 BZ 509 emigrated from its parent star and settled around the Sun in a similar environment.
Credit:NASA / Hubble Heritage Team (AURA/STScI)
Understanding exactly when and how 2015 BZ509 settled in the Solar System provides clues about the Sun's original star nursery, and about the potential enrichment of our early environment with components necessary for the appearance of life on Earth.



Contacts and sources:
Morgan Hollis
Royal Astronomical Society


Citation: An interstellar origin for Jupiter’s retrograde co-orbital asteroidF Namouni M H M MoraisMonthly Notices of the Royal Astronomical Society: Letters, Volume 477, Issue 1, 11 June 2018, Pages L117–L121, https://doi.org/10.1093/mnrasl/sly057 http://dx.doi.org/10.1093/mnrasl/sly057

Quantum Dots Derived from Tea Leaves Destroy Lung Cancer Cells



Nanoparticles derived from tea leaves inhibit the growth of lung cancer cells, destroying up to 80% of them, new research by a joint Swansea University and Indian team has shown.

The team made the discovery while they were testing out a new method of producing a type of nanoparticle called quantum dots. These are tiny particles which measure less than 10 nanometres. A human hair is 40,000 nanometres thick.

Although nanoparticles are already used in healthcare, quantum dots have only recently attracted researchers' attention. Already they are showing promise for use in different applications, from computers and solar cells to tumour imaging and treating cancer.

This image shows a size comparison in nanometres of a football, human hair and quantum dots, which are less than 10 nanometres.

Credit: S Pitchaimuthu, Swansea University


Quantum dots can be made chemically, but this is complicated and expensive and has toxic side effects. The Swansea-led research team were therefore exploring a non-toxic plant-based alternative method of producing the dots, using tea leaf extract.

Tea leaves contain a wide variety of compounds, including polyphenols, amino acids, vitamins and antioxidants. The researchers mixed tea leaf extract with cadmium sulphate (CdSO4) and sodium sulphide (Na2S) and allowed the solution to incubate, a process which causes quantum dots to form. They then applied the dots to lung cancer cells.

They found:
  • Tea leaves are a simpler, cheaper and less toxic method of producing quantum dots, compared with using chemicals, confirming the results of other research in the field.
  • Quantum dots produced from tea leaves inhibit the growth of lung cancer cells. They penetrated into the nanopores of the cancer cells and destroyed up to 80% of them. This was a brand new finding, and came as a surprise to the team.
These are microscope images of A549 lung cancer cell; left = untreated; right = treated with quantum dots.
 
Credit: Swansea University

The research, published in Applied Nano Materials, is a collaborative venture between Swansea University experts and colleagues from two Indian universities.

Dr Sudhagar Pitchaimuthu of Swansea University, lead researcher on the project, and a Ser Cymru-II Rising Star Fellow, said:

"Our research confirmed previous evidence that tea leaf extract can be a non-toxic alternative to making quantum dots using chemicals.

The real surprise, however, was that the dots actively inhibited the growth of the lung cancer cells. We hadn't been expecting this.

The CdS quantum dots derived from tea leaf extract showed exceptional fluorescence emission in cancer cell bioimaging compared to conventional CdS nanoparticles.

Quantum dots are therefore a very promising avenue to explore for developing new cancer treatments.


These are Swansea University researchers who worked, with Indian partners, on the project, showing that nanoparticles derived from tea leaves destroy lung cancer cells. L-r Dr Catherine Suenne De Castro, Dr Matthew Lloyd Davies, Dr Sudhagar Pitchaimuthu.

Credit: Swansea University

They also have other possible applications, for example in anti-microbial paint used in operating theatres, or in sun creams."

Dr Pitchaimuthu outlined the next steps for research:

"Building on this exciting discovery, the next step is to scale up our operation, hopefully with the help of other collaborators. We want to investigate the role of tea leaf extract in cancer cell imaging, and the interface between quantum dots and the cancer cell.

We would like to set up a "quantum dot factory" which will allow us to explore more fully the ways in which they can be used."

Lung cancer mortality: survival rates for lung cancer are generally lower than for other cancers. Cancer Research reports that the 5 year survival rate is less than 10%.





Contacts and sources:
Ben Donovan
Swansea University

Citation: "Green-Synthesis-Derived CdS Quantum Dots Using Tea Leaf Extract:Antimicrobial, BioImaging and Therapeutic Applications in Lung Cancer Cells".
The authors: Kavitha Shivaji, Suganya Mani, Mythili Gnanamangai Balasubramanian (K. S. Rangasamy College of Technology, Tamil Nadu, India); Ponnosamy Ponmurugan (Bharathiar University, Coimbatore, India); Catherine Suenne De Castro, Matthew Lloyd Davies, Sudhagar Pitchaimuthu (SPECIFIC, Materials Research Centre, Swansea University).   Published in Applied Nano Materials, April 2018

Night Loving Material: Flexible in the Dark, Brittle in the Light



Researchers at Nagoya University find an inorganic semiconductor is brittle when exposed to light, but flexible in the dark 

Inorganic semiconductors such as silicon are indispensable in modern electronics because they possess tunable electrical conductivity between that of a metal and that of an insulator. The electrical conductivity of a semiconductor is controlled by its band gap, which is the energy difference between its valence and conduction bands; a narrow band gap results in increased conductivity because it is easier for an electron to move from the valence to the conduction band. However, inorganic semiconductors are brittle, which can lead to device failure and limits their application range, particularly in flexible electronics. 



Fig.1 Extraordinary plasticity appeared in darkness: inorganic semiconducting crystals generally tend to fail in a brittle manner. This is true for zinc sulfide (ZnS); ZnS crystals (A) show catastrophic fracture after mechanical tests under ordinary light-exposure environments (B). However, we found out that ZnS crystals can be plastically deformed up to a deformation strain of εt = 45 % when deformed along the [001] direction in complete darkness even at room temperature (C). Moreover, the optical band gap of the deformed ZnS crystals decreased by 0.6 eV after deformation

Credit:  ©Atsutomo Nakamura


A group at Nagoya University recently discovered that an inorganic semiconductor behaved differently in the dark compared with in the light. They found that crystals of zinc sulfide (ZnS), a representative inorganic semiconductor, were brittle when exposed to light but flexible when kept in the dark at room temperature. The findings were published in Science.

"The influence of complete darkness on the mechanical properties of inorganic semiconductors had not previously been investigated," study coauthor Atsutomo Nakamura says. "We found that ZnS crystals in complete darkness displayed much higher plasticity than those under light exposure."

Fig.2 Dislocations inducing the extraordinary plasticity: plastic deformation of materials is caused by nucleation and multiplication of dislocations under an external force (A and B). It is generally believed that brittle inorganic semiconducting materials have difficulty in formation of dislocations due to their strong chemical bonds. However, we found that a great number of dislocations are generated and multiplied in ZnS crystals during deformation in darkness (C), resulting in the extraordinary plasticity.



Credit: ©Atsutomo Nakamura

The ZnS crystals in the dark deformed plastically without fracture until a large strain of 45%. The team attributed the increased plasticity of the ZnS crystals in the dark to the high mobility of dislocations in complete darkness. Dislocations are a type of defect found in crystals and are known to influence crystal properties. Under light exposure, the ZnS crystals were brittle because their deformation mechanism was different from that in the dark.

The high plasticity of the ZnS crystals in the dark was accompanied by a considerable decrease in the band gap of the deformed crystals. Thus, the band gap of ZnS crystals and in turn their electrical conductivity may be controlled by mechanical deformation in the dark. The team proposed that the decreased band gap of the deformed crystals was caused by deformation introducing dislocations into the crystals, which changed their band structure.

"This study reveals the sensitivity of the mechanical properties of inorganic semiconductors to light," coauthor Katsuyuki Matsunaga says. "Our findings may allow development of technology to engineer crystals through controlled light exposure."

The researchers' results suggest that the strength, brittleness, and conductivity of inorganic semiconductors may be regulated by light exposure, opening an interesting avenue to optimize the performance of inorganic semiconductors in electronics.

 
Contacts and sources:
Nagoya University

Citation: "Extraordinary Plasticity of an Inorganic Semiconductor in Darkness" Authors: Yu Oshima, Atsutomo Nakamura, and Katsuyuki Matsunaga, Science at DOI: 10.1126/science.aar6035.

1/3 of World Protected Areas Under Intense Human Pressure



A shocking study in the journal Science by the University of Queensland, Wildlife Conservation Society (WCS), and University of Northern British Columbia confirms that one third of the world’s protected areas – an astonishing 2.3 million square miles or twice the size of the state of Alaska – are now under intense human pressure including road building, grazing, and urbanization.

The study is a reality check for nations striving to meet commitments under the Convention on Biological Diversity (CBD) to halt biodiversity loss through protected area creation. Since 1992, the global extent of protected areas has roughly doubled in size; more than 202,000 cover more than 15 percent of the world’s terrestrial area, with a goal of at least 17 percent coverage by 2020.






  Giraffes and drilling rig 
 Giraffes and drilling rig CREDIT: Paul Mulondo/WCS
Credit: Paul Mulondo/WCS

Though management objectives differ, ranging from strict biodiversity conservation areas to zones permitting certain human activities and sustainable resource extraction, the primary goal of all protected areas is to conserve nature.

The authors looked at global “Human Footprint” maps to make their assessment which shows that 32.8 percent of protected land is highly degraded. For protected areas created before the CBD was ratified 1992, 55 percent have since experienced human pressure increases. The authors warn that CBD goals will be severely undermined if widespread human pressure continues inside protected areas.

Said the paper’s lead author, Kendall Jones of University of Queensland: “A well-run protected area network is essential in saving species. If we allow our protected area network to be degraded there is a no doubt biodiversity losses will be exacerbated.”

The study shows that governments are overestimating the space available for nature inside protected areas. Governments are claiming these places are protected for the sake of nature when in reality they aren’t. It is a major reason why biodiversity is still in catastrophic decline, despite more and more land being ‘protected’.

However, the authors are not suggesting that high pressure protected areas be de-gazetted or defunded. To the contrary, it is crucial that nations recognize the profound conservation gains that can be realized by upgrading and restoring degraded protected areas while respecting the needs of local people.

THE GOOD NEWS

The most impacted protected areas were found in Asia, Europe, and Africa in places with massive human populations. But the study did find some good news: protected areas with strict biodiversity conservation objectives are subject to significantly lower levels of human pressure.

Some of these least impacted protected areas include Keo Seima Wildlife Sanctuary in Cambodia, Madidi National Park in Bolivia, and Yasuni Biosphere Reserve in Ecuador – places where WCS has made considerable conservation investments and therefore has successfully staved off degradation.

Said Professor James Watson of WCS and University of Queensland, and the study’s senior author: “We know protected areas work – when well-funded, well-managed and well placed, they are extremely effective in halting the threats that cause biodiversity loss and ensure species return from the brink of extinction. There are also many protected areas that are still in good condition and protect the last strongholds of endangered species worldwide. The challenge is to improve the management of those protected areas that are most valuable for nature conservation to ensure they safeguard it.”

Protected areas are at the core of WCS’s conservation strategy, as these are areas that are most effective at protecting natural ecosystems and their complement of biodiversity and ecosystem services – over 80 percent of WCS’s site-based field work takes place within or around protected areas. When well-managed (through sound enforcement, monitoring, clear boundaries) and funded appropriately, protected areas are effective in reducing the loss of natural habitat, and sustaining wildlife populations.

Said Watson: “Most importantly we’ve got to recognize that these jewels in the crown need support– there are some protected areas that are safeguarding nature and that still haven’t got any evidence of human encroachment in them. We must ensure these values are maintained.”




Contacts and sources:
Stephen Sautner
Wildlife Conservation Society


Citation: One-third of global protected land is under intense human pressure Kendall R. Jones, Oscar Venter, Richard A. Fuller, James R. Allan, Sean L. Maxwell, Pablo Jose Negret, James E. M. Watson. . Science, 2018; 360 (6390): 788 DOI: 10.1126/science.aap9565

Robot Takes Flight: Autonomous Glider Can Fly Like an Albatross, Cruise Like a Sailboat.



MIT engineers have designed a robotic glider that can skim along the water’s surface, riding the wind like an albatross while also surfing the waves like a sailboat.

In regions of high wind, the robot is designed to stay aloft, much like its avian counterpart. Where there are calmer winds, the robot can dip a keel into the water to ride like a highly efficient sailboat instead.

The robotic system, which borrows from both nautical and biological designs, can cover a given distance using one-third as much wind as an albatross and traveling 10 times faster than a typical sailboat. The glider is also relatively lightweight, weighing about 6 pounds. The researchers hope that in the near future, such compact, speedy robotic water-skimmers may be deployed in teams to survey large swaths of the ocean. 
 
An albatross glider, designed by MIT engineers, skims the Charles River.
 An albatross glider, designed by MIT engineers, skims the Charles River.
Photo: Gabriel Bousquet


“The oceans remain vastly undermonitored,” says Gabriel Bousquet, a former postdoc in MIT’s Department of Aeronautics and Astronautics, who led the design of the robot as part of his graduate thesis. “In particular, it’s very important to understand the Southern Ocean and how it is interacting with climate change. But it’s very hard to get there. We can now use the energy from the environment in an efficient way to do this long-distance travel, with a system that remains small-scale.”

Bousquet will present details of the robotic system this week at IEEE’s International Conference on Robotics and Automation, in Brisbane, Australia. His collaborators on the project are Jean-Jacques Slotine, professor of mechanical engineering and information sciences and of brain sciences; and Michael Triantafyllou, the Henry L. and Grace Doherty Professor in Ocean Science and Engineering.


Credit: MIT

The physics of speed

Last year, Bousquet, Slotine, and Triantafyllou published a study on the dynamics of albatross flight, in which they identified the mechanics that enable the tireless traveler to cover vast distances while expending minimal energy. The key to the bird’s marathon voyages is its ability to ride in and out of high- and low-speed layers of air.

Specifically, the researchers found the bird is able to perform a mechanical process called a “transfer of momentum,” in which it takes momentum from higher, faster layers of air, and by diving down transfers that momentum to lower, slower layers, propelling itself without having to continuously flap its wings.

Interestingly, Bousquet observed that the physics of albatross flight is very similar to that of sailboat travel. Both the albatross and the sailboat transfer momentum in order to keep moving. But in the case of the sailboat, that transfer occurs not between layers of air, but between the air and water.

“Sailboats take momentum from the wind with their sail, and inject it into the water by pushing back with their keel,” Bousquet explains. “That’s how energy is extracted for sailboats.” 

An albatross glider, designed by MIT engineers, skims the Charles River.


Credit: MIT

Bousquet also realized that the speed at which both an albatross and a sailboat can travel depends upon the same general equation, related to the transfer of momentum. Essentially, both the bird and the boat can travel faster if they can either stay aloft easily or interact with two layers, or mediums, of very different speeds.

The albatross does well with the former, as its wings provide natural lift, though it flies between air layers with a relatively small difference in windspeeds. Meanwhile, the sailboat excels at the latter, traveling between two mediums of very different speeds — air versus water — though its hull creates a lot of friction and prevents it from getting much speed. Bousquet wondered: What if a vehicle could be designed to perform well in both metrics, marrying the high-speed qualities of both the albatross and the sailboat?

“We thought, how could we take the best from both worlds?” Bousquet says.

Out on the water

The team drafted a design for such a hybrid vehicle, which ultimately resembled an autonomous glider with a 3-meter wingspan, similar to that of a typical albatross. They added a tall, triangular sail, as well as a slender, wing-like keel. They then performed some mathematical modeling to predict how such a design would travel.

According to their calculations, the wind-powered vehicle would only need relatively calm winds of about 5 knots to zip across waters at a velocity of about 20 knots, or 23 miles per hour.

“We found that in light winds you can travel about three to 10 times faster than a traditional sailboat, and you need about half as much wind as an albatross, to reach 20 knots,” Bousquet says. “It’s very efficient, and you can travel very fast, even if there is not too much wind.”

The team built a prototype of their design, using a glider airframe designed by Mark Drela, professor of aeronautics and astronautics at MIT. To the bottom of the glider they added a keel, along with various instruments, such as GPS, inertial measurement sensors, auto-pilot instrumentation, and ultrasound, to track the height of the glider above the water.

“The goal here was to show we can control very precisely how high we are above the water, and that we can have the robot fly above the water, then down to where the keel can go under the water to generate a force, and the plane can still fly,” Bousquet says.

The researchers decided to test this “critical maneuver” — the act of transitioning between flying in the air and dipping the keel down to sail in the water. Accomplishing this move doesn’t necessarily require a sail, so Bousquet and his colleagues decided not to include one in order to simplify preliminary experiments.

In the fall of 2016, the team put its design to the test, launching the robot from the MIT Sailing Pavilion out onto the Charles River. As the robot lacked a sail and any mechanism to get it started, the team hung it from a fishing rod attached to a whaler boat. With this setup, the boat towed the robot along the river until it reached about 20 miles per hour, at which point the robot autonomously “took off,” riding the wind on its own.

Once it was flying autonomously, Bousquet used a remote control to give the robot a “down” command, prompting it to dip low enough to submerge its keel in the river. Next, he adjusted the direction of the keel, and observed that the robot was able to steer away from the boat as expected. He then gave a command for the robot to fly back up, lifting the keel out of the water.

“We were flying very close to the surface, and there was very little margin for error — everything had to be in place,” Bousquet says. “So it was very high stress, but very exciting.”

The experiments, he says, prove that the team’s conceptual device can travel successfully, powered by the wind and the water. Eventually, he envisions fleets of such vehicles autonomously and efficiently monitoring large expanses of the ocean.

“Imagine you could fly like an albatross when it’s really windy, and then when there’s not enough wind, the keel allows you to sail like a sailboat,” Bousquet says. “This dramatically expands the kinds of regions where you can go.”

This research was supported, in part, by the Link Ocean Instrumentation fellowship.




Contacts and sources:
Jennifer Chu
Massachusetts Institute of Technology
 

Sunday, May 20, 2018

3D Smart Gel Walks Underwater, Grabs and Moves Objects



Engineers have created a 3D-printed smart gel that walks underwater and grabs objects and moves them.

The watery creation could lead to soft robots that mimic sea animals like the octopus, which can walk underwater and bump into things without damaging them. It may also lead to artificial heart, stomach and other muscles, along with devices for diagnosing diseases, detecting and delivering drugs and performing underwater inspections.

Soft materials like the smart gel are flexible, often cheaper to manufacture than hard materials and can be miniaturized. Devices made of soft materials typically are simple to design and control compared with mechanically more complex hard devices.

A human-like 3D-printed smart gel walks underwater.  
 https://news.rutgers.edu/sites/medrel/files/inline-img/Howonhigh%20res%20image.jpg
Photo: Daehoon Han/Rutgers University-New Brunswick
“Our 3D-printed smart gel has great potential in biomedical engineering because it resembles tissues in the human body that also contain lots of water and are very soft,” said  Howon Lee, senior author of a new study and an assistant professor in the Rutgers University–New Brunswick Department of Mechanical and Aerospace Engineering. “It can be used for many different types of underwater devices that mimic aquatic life like the octopus.”

The study, published online in ACS Applied Materials & Interfaces, focuses on a 3D-printed hydrogel that moves and changes shape when activated by electricity. Hydrogels, which stay solid despite their 70-plus percent water content, are found in the human body, diapers, contact lenses, Jell-O and many other things.

YouTube video by Daehoon Han/Rutgers University–New Brunswick

Credit:

During the 3D-printing process, light is projected on a light-sensitive solution that becomes a gel. The hydrogel is placed in a salty water solution (or electrolyte) and two thin wires apply electricity to trigger motion: walking forward, reversing course and grabbing and moving objects, said Lee. The human-like walker that the team created is about one inch tall.

The speed of the smart gel’s movement is controlled by changing its dimensions (thin is faster than thick), and the gel bends or changes shape depending on the strength of the salty water solution and electric field. The gel resembles muscles that contract because it’s made of soft material, has more than 70 percent water and responds to electrical stimulation, Lee said.

“This study demonstrates how our 3D-printing technique can expand the design, size and versatility of this smart gel,” he said. “Our microscale 3D-printing technique allowed us to create unprecedented motions.”

The study’s lead author is Daehoon Han, a doctoral student in mechanical and aerospace engineering in Rutgers’ School of Graduate Studies. Co-authors include former Rutgers undergraduate student Cindy Farino; Chen Yang, a doctoral student in mechanical and aerospace engineering; Tracy Scott, a former postdoc; Daniel Browe, a doctoral student in biomedical engineering; Joseph W. Freeman, an associate professor in the Department of Biomedical Engineering; and Wonjoon Choi, an associate professor in the School of Mechanical Engineering at Korea University in Seoul, Republic of Korea.







Contacts and sources:
Todd Bates
Rutgers University–New Brunswick


Citation: . Soft Robotic Manipulation and Locomotion with a 3D Printed Electroactive Hydrogel. Daehoon Han, Cindy Farino, Chen Yang, Tracy Scott, Daniel Browe, Wonjoon Choi, Joseph W. Freeman, Howon LeeACS Applied Materials & Interfaces, 2018; DOI: 10.1021/acsami.8b04250

Drumstick Made of Light Beats Quantum Drum So It Vibrates and Is Still at the Same Time

Researchers have studied how a ‘drumstick’ made of light could make a microscopic ‘drum’ vibrate and stand still at the same time.

A team of researchers from the UK and Australia have made a key step towards understanding the boundary between the quantum world and our everyday classical world.

Quantum mechanics is truly weird. Objects can behave like both particles and waves, and can be both here and there at the same time, defying our common sense. Such counterintuitive behavior is typically confined to the microscopic realm and the question “why don’t we see such behavior in everyday objects?” challenges many scientists today. 
Experimental setup
 Credit ICL


Now, a team of researchers have developed a new technique to generate this type of quantum behaviour in the motion of a tiny drum just visible to the naked eye. The details of their research are published today in New Journal of Physics.

Project principal investigator, Dr Michael Vanner from the Quantum Measurement Lab at Imperial College London, said: “Such systems offer significant potential for the development of powerful new quantum-enhanced technologies, such as ultra-precise sensors, and new types of transducers.



“Excitingly, this research direction will also enable us to test the fundamental limits of quantum mechanics by observing how quantum superpositions behave at a large scale.”

Mechanical vibrations, such as those that create the sound from a drum, are an important part of our everyday experience. Hitting a drum with a drumstick causes it to rapidly move up and down, producing the sound we hear.

In the quantum world, a drum can vibrate and stand still at the same time. However, generating such quantum motion is very challenging. lead author of the project Dr Martin Ringbauer from the University of Queensland node of the Australian Research Council Centre for Engineered Quantum Systems, said: “You need a special kind of drumstick to make such a quantum vibration with our tiny drum.”

In recent years, the emerging field of quantum optomechanics has made great progress towards the goal of a quantum drum using laser light as a type of drumstick. However, many challenges remain, so the authors’ present study takes an unconventional approach.

Dr Ringbauer continues: “We adapted a trick from optical quantum computing to help us play the quantum drum. We used a measurement with single particles of light—photons—to tailor the properties of the drumstick.

“This provides a promising route to making a mechanical version of Schrodinger’s cat, where the drum vibrates and stands still at the same time.”

These experiments have made the first observation of mechanical interferences fringes, which is a crucial step forward for the field.

In the experiment, the fringes were at a classical level due to thermal noise, but motivated by this success, the team are now working hard to improve their technique and operate the experiments at temperatures close to absolute zero where quantum mechanics is expected to dominate.

These future experiments may reveal new intricacies of quantum mechanics and may even help light the path to a theory that links the quantum world and the physics of gravity.

 





Contacts and sources:
Hayley Dunning
Imperial College London  (ICL)

Citation: ‘Generation of Mechanical Interference Fringes by Multi-Photon Counting’ by M Ringbauer, T J Weinhold, L A Howard, A G White & M R Vanner is published in New Journal of Physics. http://dx.doi.org/10.1088/1367-2630/aabb8d

Hippo Foul Rivers and Cause Fish Kills

Humans have competitors in their ability to befoul the world’s waterways: Hippos clog Africa’s Mara River with tons of their oxygen-eating, fish-killing feces, a new Yale University-led study has shown.

Sections of the Mara River in East Africa provide researchers a glimpse at what river systems once looked like when they supported huge herds of large animals, the new study published May 16 in the journal Nature Communications suggests.
 

 Pod of Hippos (Hippopotamus amphibius) in Luangwa Valley, Zambia

Credit: Paul Maritz/ Wikimedia Commons

And it wasn’t always a pretty sight.

In the Mara River, 4,000 hippopotami defecate 8,500 kg of organic matter each day in river pools where they congregate. These feces settle on the river bottom, particularly during the dry season, where they decompose and lead to hypoxia — or lack of oxygen that can kill fish — and create other toxic chemicals. When flushing flows scour the hippo pools, they wash the feces and hypoxic waters downstream, which can cause rapid declines in dissolved oxygen in the river and fish kills. 
Credit: Yale University

“This appears to be a natural process that may have been more common in Sub-Saharan African rivers prior to the extirpation of hippos from much of their historical range,” said Yale’s Christopher Dutton, the study’s lead author.

“Human sewage, drought, hog farms, or cattle pens all can lead to hypoxia but we show it also can be caused by wildlife in unregulated rivers,” said David Post, professor of ecology and evolutionary biology and senior author. “And oxygen is the master variable for all aquatic life.”


The common hippopotamus (Hippopotamus amphibius), or hippo, is a large, mostly herbivorous, semiaquatic mammal native to sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae, the other being the pygmy hippopotamus


 Range map of the African hippopotamus. Historic range is in red while current range is in green
 File:Hippo distribution.gif
Credit: Wikipedia

The paper’s other authors are Amanda Subalusky and Emma Rosi from the Cary Institute of Ecosystems Studies and Stephen Hamilton from Michigan State University.


Contacts and sources:
Bill Hathaway
Yale University

Citation: Organic matter loading by hippopotami causes subsidy overload resulting in downstream hypoxia and fish kills
Christopher L. Dutton, Amanda L. Subalusky, Stephen K. Hamilton, Emma J. Rosi & David M. Post
Nature Communicationsvolume 9, Article number: 1951 (2018)
doi:10.1038/s41467-018-04391-6   https://www.nature.com/articles/s41467-018-04391-6